Ultrasound & Colour Doppler
Ultrasonography is used to see internal body structures such as tendons, muscles, joints, blood vessels, and internal organs. Its aim is often to find a source of a disease or to exclude any pathology. The practice of examining pregnant women using ultrasound is called obstetric ultrasound, and is widely used.
Compared to other prominent methods of medical imaging, ultrasound has several advantages. It provides images in real-time, it is portable and can be brought to the bedside, it is substantially lower in cost, and it does not use harmful ionizing radiation. It is possible to perform both diagnosis and therapeutic procedures, using ultrasound to guide interventional procedures (for instance biopsies or drainage of fluid collections). Sonography is effective for imaging soft tissues of the body. Superficial structures such as muscles, tendons, testes, breast, thyroid and parathyroid glands, and the neonatal brain are imaged at a higher frequency (7–18 MHz), which provides better axial and lateral resolution. Deeper structures such as liver and kidney are imaged at a lower frequency 1–6 MHz with lower axial and lateral resolution but greater penetration.
A general-purpose ultrasound scanner may be used for most imaging purposes. Usually specialty applications may be served only by use of a specialty transducer. Most ultrasound procedures are done using a transducer on the surface of the body, but improved diagnostic confidence is often possible if a transducer can be placed inside the body. For this purpose, specialty transducers, including endovaginal, endorectal, and transesophageal transducers are commonly employed. At the extreme of this, very small transducers can be mounted on small diameter catheters and placed into blood vessels to image the walls and disease of those vessels.
Ultrasound is commonly used by anesthesiologists to guide injecting needles when placing local anaesthetic solutions near nerves.
Doppler ultrasonography and Intravascular ultrasound
In angiology or vascular medicine, duplex ultrasound (B Mode vessels imaging combined with Doppler flow measurement) is daily used to diagnose arterial and venous disease all over the body. This is particularly important in neurology, where ultrasound is used for assessing blood flow and stenoses in the carotid arteries (Carotid ultrasonography) and the big intracerebral arteries (Transcranial Doppler).
Intravascular ultrasound (IVUS) is a methodology using a specially designed catheter with a miniaturized ultrasound probe attached to the distal end of the catheter. The proximal end of the catheter is attached to computerized ultrasound equipment. It allows the application of ultrasound technology, such as piezoelectric transducer or CMUT, to see from inside blood vessels out through the surrounding blood column, visualizing the endothelium (inner wall) of blood vessels in living individuals.
On the legs, ultrasonography of deep venous thrombosis focuses on the deep veins, while ultrasonography of chronic venous insufficiency of the legs focuses on more superficial veins.
Echocardiography is an essential tool in cardiology, to diagnose e.g. dilatation of parts of the heart and function of heart ventricles and valves.
Point of care emergency ultrasound has many applications in emergency medicine, including the Focused Assessment with Sonography for Trauma (FAST) exam for assessing significant hemoperitoneum or pericardial tamponade after trauma.
Abdominal and endoanal ultrasound are frequently used in gastroenterology and colorectal surgery. In abdominal sonography, the solid organs of the abdomen such as the pancreas, aorta, inferior vena cava, liver, gall bladder, bile ducts, kidneys, and spleen are imaged. Sound waves are blocked by gas in the bowel and attenuated in different degree by fat, therefore there are limited diagnostic capabilities in this area. The appendix can sometimes be seen when inflamed (as in e.g.: appendicitis). Endoanal ultrasound is used particularly in the investigation of anorectal symptoms such as fecal incontinence or obstructed defecation. It images the immediate perianal anatomy and is able to detect occult defects such as tearing of the anal sphincter. Ultrasonography of liver tumors allows for both detection and characterization.
Gynecology and obstetrics:
Gynecologic ultrasonography examines female pelvic organs (specifically the uterus, the ovaries, and the Fallopian tubes) as well as the bladder, the adnexa, and the Pouch of Douglas. It commonly uses vaginal ultrasonography. Obstetrical sonographyis commonly used during pregnancy to check on the development of the fetus.
Obstetric ultrasound can be used to identify many conditions that would be harmful to the mother and the baby, many health care professionals consider the risk of leaving these conditions undiagnosed to be much greater than the very small risk, if any, associated with undergoing an ultrasound scan. Obstetric ultrasound is primarily used to:
Date the pregnancy (gestational age)
Confirm fetal viability
Determine location of fetus, intrauterine vs ectopic
Location of the placenta in relation to the cervix
Number of fetuses (multiple pregnancy)
Major physical abnormalities.
Assess fetal growth (for evidence of intrauterine growth restriction (IUGR))
Foetal movement and heartbeat.
Otolaryngology (head and neck):
Most structures of the neck, including the thyroid and parathryoid glands, lymph nodes, and salivary glands, are well-visualized by high-frequency ultrasound with exceptional anatomic detail. Ultrasound is the preferred imaging modality for thyroid tumors and lesions, and ultrasonography is critical in the evaluation, preoperative planning, and postoperative surveillance of patients with thyroid cancer. Many other benign and malignant conditions in the head and neck can be evaluated and managed with the help of diagnostic ultrasound and ultrasound-guided procedures.
In neonatology, transcranial Doppler can be used for basic assessment of intracerebral structural abnormalities, bleeds, ventriculomegaly or hydrocephalus and anoxic insults (Periventricular leukomalacia). The ultrasound can be performed through the soft spots in the skull of a newborn infant (Fontanelle) until these completely close at about 1 year of age and form a virtually impenetrable acoustic barrier for the ultrasound. The most common site for cranial ultrasound is the anterior fontanelle. The smaller the fontanelle, the poorer the quality of the picture.
In ophthalmology and optometry, there are two major forms of eye exam using ultrasound:
A-scan ultrasound biometry, commonly referred to as an A-scan (short for Amplitude scan). It is an A-mode that provides data on the length of the eye, which is a major determinant in common sight disorders.
B-scan ultrasonography, or B-scan, which is a B-mode scan that produces a cross-sectional view of the eye and the orbit. It is commonly used to see inside the eye when media is hazy due to cataract or any corneal opacity.
In pulmonology, endobronchial Ultrasound (EBUS) probes are applied to standard flexible endoscopic probes and used by pulmonologists to allow for direct visualization of endobronchial lesions and lymph nodes prior to transbronchial needle aspiration. Among its many uses, EBUS aids in lung cancer staging by allowing for lymph node sampling without the need for major surgery.
Ultrasound is routinely used in urology to determine, for example, the amount of fluid retained in a patient's bladder. In a pelvic sonogram, organs of the pelvic region are imaged. This includes the uterus and ovaries or urinary bladder. Males are sometimes given a pelvic sonogram to check on the health of their bladder, the prostate, or their testicles (for example to distinguish epididymitis from testicular torsion). In young males, it is used to distinguish more benign testicular masses (varicocele or hydrocele) from testicular cancer, which is highly curable but which must be treated to preserve health and fertility. There are two methods of performing a pelvic sonography – externally or internally. The internal pelvic sonogram is performed either transvaginally (in a woman) or transrectally (in a man). Sonographic imaging of the pelvic floor can produce important diagnostic information regarding the precise relationship of abnormal structures with other pelvic organs and it represents a useful hint to treat patients with symptoms related to pelvic prolapse, double incontinence and obstructed defecation. It is used to diagnose and, at higher frequencies, to treat (break up) kidney stones or kidney crystals (nephrolithiasis).
Scrotal ultrasonography is used in the evaluation of testicular pain, and can help identify solid masses.
Musculoskeletal ultrasound in used to examine tendons, muscles, nerves, ligaments, soft tissue masses, and bone surfaces. Ultrasound is an alternative to x-ray imaging in detecting fractures of the wrist, elbow and shoulder for patients up to 12 years (Fracture sonography).
Quantitative ultrasound is an adjunct musculoskeletal test for myopathic disease in children; estimates of lean body mass in adults; proxy measures of muscle quality (i.e., tissue composition) in older adults with sarcopenia
In nephrology, ultrasonography of the kidneys is essential in the diagnosis and management of kidney-related diseases. The kidneys are easily examined, and most pathological changes in the kidneys are distinguishable with ultrasound.
Doppler ultrasonography employs the Doppler effect to assess whether structures (usually blood) are moving towards or away from the probe, and its relative velocity. By calculating the frequency shift of a particular sample volume, for example flow in an artery or a jet of blood flow over a heart valve, its speed and direction can be determined and visualized. Color Doppler is the measurement of velocity by color scale.
The use of Doppler ultrasonography to examine the heart. An echocardiogram can, within certain limits, produce accurate assessment of the direction of blood flow and the velocity of blood and cardiac tissue at any arbitrary point using the Doppler effect. Velocity measurements allow assessment of cardiac valve areas and function, any abnormal communications between the left and right side of the heart, any leaking of blood through the valves (valvular regurgitation), calculation of the cardiac output and calculation of E/A ratio (a measure of diastolic dysfunction). Contrast-enhanced ultrasound using gas-filled microbubble contrast media can be used to improve velocity or other flow-related medical measurements.
Transcranial Doppler (TCD) and transcranial color Doppler (TCCD), which measure the velocity of blood flow through the brain's blood vessels transcranially (through the cranium). They are used as tests to help diagnose emboli, stenosis, vasospasm from a subarachnoid hemorrhage (bleeding from a ruptured aneurysm), and other problems.
Doppler fetal monitors, although usually not technically -graphy but rather sound-generating, use the Doppler effect to detect the fetal heartbeat for prenatal care. These are hand-held, and some models also display the heart rate in beats per minute (BPM). Use of this monitor is sometimes known as Doppler auscultation. The Doppler fetal monitor is commonly referred to simply as a Doppler or fetal Doppler. Doppler fetal monitors provide information about the fetus similar to that provided by a fetal stethoscope.
X-rays are a type of radiation called electromagnetic waves. X-ray imaging creates pictures of the inside of the body. The images show the parts of the body in different shades of black and white. This is because different tissues absorb different amounts of radiation. Calcium in bones absorbs x-rays the most, so bones look white. Fat and other soft tissues absorb less, and look gray. Air absorbs the least, so lungs look black.
The most familiar use of x-rays is checking for broken bones, but x-rays are also used in other ways. For example, chest x-rays can spot pneumonia. Mammograms use x-rays to look for breast cancer.
Radiographs are useful in the detection of pathology of the skeletal system as well as for detecting some disease processes in soft tissue. Some notable examples are the very common chest X-ray, which can be used to identify lung diseases such as pneumonia, lung cancer, or pulmonary edema, and the abdominal x-ray, which can detect bowel (or intestinal) obstruction, free air (from visceral perforations) and free fluid (in ascites). X-rays may also be used to detect pathology such as gallstones (which are rarely radiopaque) or kidney stones which are often (but not always) visible. Traditional plain X-rays are less useful in the imaging of soft tissues such as the brain or muscle. One area where projectional radiographs are used extensively is in evaluating how an orthopedic implant, such as a knee, hip or shoulder replacement, is situated in the body with respect to the surrounding bone.
Dental radiography is commonly used in the diagnoses of common oral problems, such as cavities.
Fluoroscopy is an imaging technique commonly used by physicians or radiation therapists to obtain real-time moving images of the internal structures of a patient through the use of a fluoroscope. In its simplest form, a fluoroscope consists of an X-ray source and a fluorescent screen, between which a patient is placed.
Computed Tomography(CT Scan)
16 Slice CT scan at Chandan Hospital makes use of computer-processed combinations of many X-ray measurements taken from different angles to produce cross-sectional (tomographic) images (virtual "slices") of specific areas of a scanned object, allowing the user to see inside the object without cutting. Other terms include computed axial tomography (CAT scan) and computer aided tomography.
CT scanning of the head is typically used to detect infarction, tumors, calcifications, haemorrhage and bone trauma. Of the above, hypodense (dark) structures can indicate edema and infarction, hyperdense (bright) structures indicate calcifications and haemorrhage and bone trauma can be seen as disjunction in bone windows. Tumors can be detected by the swelling and anatomical distortion they cause, or by surrounding edema. Ambulances equipped with small bore multi-sliced CT scanners respond to cases involving stroke or head trauma. CT scanning of the head is also used in CT-guided stereotactic surgery and radiosurgery for treatment of intracranial tumors, arteriovenous malformations and other surgically treatable conditions using a device known as the N-localizer.
Magnetic resonance imaging (MRI) of the head provides superior information as compared to CT scans when seeking information about headache to confirm a diagnosis of neoplasm, vascular disease, posterior cranial fossa lesions, cervicomedullary lesions, or intracranial pressure disorders. It also does not carry the risks of exposing the patient to ionizing radiation. CT scans may be used to diagnose headache when neuroimaging is indicated and MRI is not available, or in emergency settings when hemorrhage, stroke, or traumatic brain injury are suspected. Even in emergency situations, when a head injury is minor as determined by a physician's evaluation and based on established guidelines, CT of the head should be avoided for adults and delayed pending clinical observation in the emergency department for children.
CT scan can be used for detecting both acute and chronic changes in the lung parenchyma, that is, the internals of the lungs. It is particularly relevant here because normal two-dimensional X-rays do not show such defects. A variety of techniques are used, depending on the suspected abnormality. For evaluation of chronic interstitial processes (emphysema, fibrosis, and so forth), thin sections with high spatial frequency reconstructions are used; often scans are performed both in inspiration and expiration. This special technique is called high resolution CT. Therefore, it produces a sampling of the lung and not continuous images.
Computed tomography angiography (CTA) is contrast CT to visualize arterial and venous vessels throughout the body. This ranges from arteries serving the brain to those bringing blood to the lungs, kidneys, arms and legs. An example of this type of exam is CT pulmonary angiogram(CTPA) used to diagnose pulmonary embolism (PE). It employs computed tomography and an iodine based contrast agent to obtain an image of the pulmonary arteries.
A CT scan of the heart is performed to gain knowledge about cardiac or coronary anatomy. Traditionally, cardiac CT scans are used to detect, diagnose or follow up coronary artery disease.
The main forms of cardiac CT scanning are:
Coronary CT angiography (CTA): the use of CT to assess the coronary arteries of the heart. The subject receives an intravenous injection of radiocontrast and then the heart is scanned using a high speed CT scanner, allowing radiologists to assess the extent of occlusion in the coronary arteries, usually in order to diagnose coronary artery disease.
Coronary CT calcium scan: also used for the assessment of severity of coronary artery disease. Specifically, it looks for calcium deposits in the coronary arteries that can narrow arteries and increase the risk of heart attack. A typical coronary CT calcium scan is done without the use of radiocontrast, but it can possibly be done from contrast-enhanced images as well.
Abdominal and pelvic:
CT is an accurate technique for diagnosis of abdominal diseases. Its uses include diagnosis and staging of cancer, as well as follow up after cancer treatment to assess response. It is commonly used to investigate acute abdominal pain.
CT is often used to image complex fractures, especially ones around joints, because of its ability to reconstruct the area of interest in multiple planes. Fractures, ligamentous injuries and dislocations can easily be recognised with a 0.2 mm resolution. With modern Dual-energy CT scanners, new areas of use have been established, such as aiding in the diagnosis of gout.
Dental X-ray – OPG (Orthopantomogram)
A panoramic radiograph is a panoramic scanning dental X-ray of the upper and lower jaw. It shows a two-dimensional view of a half-circle from ear to ear. Panoramic radiography is a form of focal plane tomography; thus, images of multiple planes are taken to make up the composite panoramic image, where the maxilla and mandibleare in the focal trough and the structures that are superficial and deep to the trough are blurred.
An OPG is a panoramic or wide view x-ray of the lower face, which displays all the teeth of the upper and lower jaw on a single film. It demonstrates the number, position and growth of all the teeth including those that have not yet surfaced or erupted. It is different from the small close up x-rays dentists take of individual teeth. An OPG may also reveal problems with the jawbone and the joint which connects the jawbone to the head, called the Temporomandibular joint or TMJ. An OPG may be requested for the planning of orthodontic treatment, for assessment of wisdom teeth or for a general overview of the teeth and the bone which supports the teeth.
Panoramic radiograph showing horizontally impacted lower wisdom teeth.
Minimally-displaced fracture in right mandibular. Arrow marks fracture.
Panoramic radiograph showing Stafne defect (arrowed).
Dental panoramic radiograph showing dentigerous cyst (arrowed).
OPTs are used by health care professionals to provide information on:
- Impacted wisdom teeth diagnosis and treatment planning - the most common use is to determine the status of wisdom teeth and trauma to the jaws.
- Periodontal bone loss and periapical involvement.
- Finding the source of dental pain
- Assessment for the placement of dental implants
- Orthodontic assessment. pre and post operative
- Diagnosis of developmental anomalies such as cherubism, cleido cranial dysplasia
- Carcinoma in relation to the jaws
- Temporomandibular joint dysfunctions and ankylosis.
- Diagnosis of osteosarcoma, ameloblastoma, renal osteodystrophy affecting jaws and hypophosphatemia.
- Diagnosis, and pre- and post-surgical assessment of oral and maxillofacial trauma, e.g. dentoalveolar fractures and mandibular fractures.
- Salivary stones (Sialolithiasis).
Principal advantage of panoramic images:
- Broad coverage of facial bone and teeth
- Low patient radiation dose
- Convenience of examination for the patient (films need not be placed inside the mouth)
- Ability to be used in patients who cannot open the mouth or when the opening is restricted e.g.: due to trismus
- Short time required for making the image
- Patient's ready understandability of panoramic films, making them a useful visual aid in patient education and case presentation.
- Easy to store compared to the large set of intra oral x-rays which are typically used.
Doppler ultrasonography at Chandan Hospital is medical ultrasonography that employs the Doppler effect to generate imaging of the movement
of tissues and body fluids (usually blood), and their relative velocity to the probe. By calculating the frequency shift of a particular sample volume,
for example flow in an artery or a jet of blood flow over a heart valve, its speed and direction can be determined and visualized. Color Doppler or
color flow Doppler is the presentation of the velocity by color scale. Color Doppler images are generally combined with grayscale (B-mode) images
to display duplex ultrasonography images, allowing for simultaneous visualization of the anatomy of the area.
This is particularly useful in cardiovascular studies (sonography of the vascular system and heart) and essential in many areas such as determining reverse blood flow in the liver vasculature in portal hypertension.
Transcranial Doppler of the cerebral circulation
Transcranial Doppler (TCD) and transcranial color Doppler (TCCD) measure the velocity of blood flow through the brain's blood vessels transcranially
(through the cranium). These modes of medical imaging conduct a spectral analysis of the acoustic signals they receive and can therefore be
classified as methods of active acoustocerebrography. They are used as tests to help diagnose emboli, stenosis, vasospasm from a subarachnoid hemorrhage
(bleeding from a ruptured aneurysm), and other problems. These relatively quick and inexpensive tests are growing in popularity.
The tests are effective for detecting sickle cell disease, ischemic cerebrovascular disease, subarachnoid hemorrhage, arteriovenous malformations,
and cerebral circulatory arrest. The tests are possibly useful for perioperative monitoring and meningeal infection.
The tests are often used in conjunction with other tests such as MRI, MRA, carotid duplex ultrasound and CT scans.
The tests are also used for research in cognitive neuroscience.
Doppler ultrasound showing a deep vein thrombosis, with no flow through the thrombus.
Vascular ultrasonography helps determine multiple factors within the circulatory system.
It can evaluate central (abdominal) and peripheral arteries and veins; it helps determine the amount of vascular stenosis (narrowing) or
occlusion (complete blockage) within an artery; it assists in ruling out aneurysmal disease; and it is the main aid to rule out thrombotic events.
Duplex is an inexpensive, non-invasive way to determine pathology. It is used in for example:
- Carotid ultrasonography
- Ultrasonography of deep venous thrombosis
- Ultrasonography of chronic venous insufficiency of the legs
Duplex evaluation is usually done prior to any invasive testing or surgical procedure. Ultrasound duplex scanning can provide additional information that may guide therapeutic decisions. The location and severity of arterial narrowings and occlusions can be identified. The vascular sonographer can map disease in lower-extremity segments with great accuracy, though duplex scanning is more time-consuming than other lower-extremity arterial studies.
An alternative to Doppler to visualize vessels is B-flow, which digitally highlights weak flow reflectors (mainly red blood cells) while suppressing the signals from the surrounding stationary tissue. It can visualize flowing blood and surrounding stationary tissues simultaneously.
Renal ultrasonography with using duplex technique of a normal adult kidney, with the estimation of the systolic velocity (Vs), the diastolic velocity (Vd), acceleration time (AoAT), systolic acceleration (Ao Accel) and resistive index (RI). Red and blue colors in the color box represent flow towards and away from the transducer, respectively. The specrogram below the B-mode image shows flow velocity (m/s) against time (s) obtained within the range gate. The small flash icons on the spectrogram represent initiation of the flow measurement.
Doppler ultrasonography is widely used in renal ultrasonography. Renal vessels are easily depicted by the color Doppler technique in order to evaluate perfusion.
Doppler echocardiography is the use of Doppler ultrasonography to examine the heart. An echocardiogram can, within certain limits, produce accurate assessment of the direction of blood flow and the velocity of blood and cardiac tissue at any arbitrary point using the Doppler effect. One of the limitations is that the ultrasound beam should be as parallel to the blood flow as possible. Velocity measurements allow assessment of cardiac valve areas and function, any abnormal communications between the left and right side of the heart, any leaking of blood through the valves (valvular regurgitation), calculation of the cardiac output and calculation of E/A ratio (a measure of diastolic dysfunction). Contrast-enhanced ultrasound using gas-filled microbubble contrast media can be used to improve velocity or other flow-related medical measurements.
Doppler fetal monitor:
Doppler fetal monitors, although usually not technically -graphy but rather sound-generating, use the Doppler effect to detect the fetal heartbeat for prenatal care. These are hand-held, and some models also display the heart ratein beats per minute (BPM). Use of this monitor is sometimes known as Doppler auscultation. The Doppler fetal monitor is commonly referred to simply as a Doppler or fetal Doppler. Doppler fetal monitors provide information about the fetus similar to that provided by a fetal stethoscope.
Mammographyat Chandan Hospital is a low dose x-ray picture of the breast.
It can be used to check for breast cancer in women who have no signs or symptoms of the disease.
It can also be used if a women have a lump or other sign of breast cancer.
Studies reveal that over 16% of Indian women of the age group 40-60 are at risk of being diagnosed with breast cancer.
Further, delayed detection can result in 1 of every 22 women developing breast cancer in India.
1 The best way to detect breast cancer early is to go for regular breast screening exams.
As with all X-rays, mammograms use doses of ionizing radiation to create images. These images are then analyzed for abnormal findings.
Screening mammography is the type of mammogram that checks you when you have no symptoms. It can help reduce the number of deaths from breast cancer among women ages 40 to 70.
Ultrasound, ductography, positron emission mammography (PEM), and magnetic resonance imaging (MRI) are adjuncts to mammography. Ultrasound is typically used for further evaluation of masses found on mammography or palpable masses not seen on mammograms. Ductograms are still used in some institutions for evaluation of bloody nipple discharge when the mammogram is non-diagnostic. MRI can be useful for further evaluation of questionable findings, as well as for screening pre-surgical evaluation in patients with known breast cancer, in order to detect additional lesions that might change the surgical approach, for example, from breast-conserving lumpectomy to mastectomy.
Sono-mammography (Ultrasound of Breast) :
Sonomammography or breast ultrasound is a non-invasive procedure performed to assess the breasts and the blood flow to areas inside it. This test allows quick visualization of the breast tissue. The examination is often done along with mammography (x-ray of breast tissue) to study a mass or lump.
A breast ultrasound or sono-mammography is recommended for women,
- When a breast lump (mass) or a general lumpiness is felt in the breast
- To determine if the abnormality detected through mammography or a palpable lump is a fluid-filled cyst or a solid tumour
- Breast tissue is too dense to be assessed accurately by mammography
In high risk patients with family history of breast cancer, past history of breast cancer or in
females older than 35 years of age as a preventive measure to screen for breast cancer
- Additional method to evaluate the breast, when mammography is not so clear
How it is done?
- WUnlike mammography, sonomammography can be performed anytime during the menstrual cycle with no special preparation.
Being a simple ultrasound procedure, it does not require much groundwork. The person to be examined lies down on examining table. Radiologist applies a gel on the breast area and with uses a special probe (linear, high frequency probe) to scan the whole chest area and armpits for any lump or mass.
- Quick & non-invasive
- Does not require any prior preparation
- Useful for evaluating breast masses
- Identifies if a suspicious mass is a cyst (fluid-filled sac) without even placing a needle into it to aspirate fluid
During the procedure, the breast is compressed using a dedicated mammography unit. Parallel-plate compression evens out the thickness of breast tissue to increase image quality by reducing the thickness of tissue that x-rays must penetrate, decreasing the amount of scattered radiation (scatter degrades image quality), reducing the required radiation dose, and holding the breast still (preventing motion blur). In screening mammography, both head-to-foot (craniocaudal, CC) view and angled side-view (mediolateral oblique, MLO) images of the breast are taken. Diagnostic mammography may include these and other views, including geometrically magnified and spot-compressed views of the particular area of concern. Deodorant, talcum powder or lotion may show up on the X-ray as calcium spots, so women are discouraged from applying them on the day of their exam. There are two types of mammogram studies: screening mammograms and diagnostic mammograms. Screening mammograms, consisting of four standard X-ray images, are performed yearly on patients who presents with no symptoms. Diagnostic mammograms are reserved for patients with breast symptoms, changes, or abnormal findings seen on their screening mammograms. Diagnostic mammograms are also performed on patients with breast implants, breast reductions, and patients with personal and/or family histories of breast cancer.
Digital mammography is a specialized form of mammography that uses digital receptors and computers instead of x-ray film
to help examine breast tissue for breast cancer. The electrical signals can be read on computer screens, permitting more
manipulation of images to allow radiologists to view the results more clearly . Digital mammography may be "spot view",
for breast biopsy, or "full field" (FFDM) for screening.
Digital mammography is also utilized in stereotactic biopsy. Breast biopsy may also be performed using
a different modality, such as ultrasound or magnetic resonance imaging (MRI).
Three-dimensional mammography, also known as digital breast tomosynthesis (DBS), tomosynthesis,
and 3D breast imaging, is a mammogram technology that creates a 3D image of the breast using X-rays.
When used in addition to usual mammography, it results in more positive tests.
Mammogram results are often expressed in terms of the BI-RADS Assessment Category,
often called a "BI-RADS score." The categories range from 0 (Incomplete) to 6 (Known biopsy – proven malignancy).
In the UK mammograms are scored on a scale from 1-5 (1 = normal, 2 = benign, 3 = indeterminate, 4 = suspicious of malignancy, 5 = malignant).
Evidence suggests that accounting for genetic risk factors improve breast cancer risk prediction.
Bone Mineral Density (BMD)
Bone density, or bone mineral density (BMD), is the amount of bone mineral in bone tissue. The concept is of mass of mineral per volume of bone (relating to density in the physics sense), although clinically it is measured by proxy according to optical density per square centimeter of bone surface upon imaging. Bone density measurement is used in clinical medicine as an indirect indicator of osteoporosis and fracture risk. It is measured by a procedure called densitometry. The measurement is painless and non-invasive and involves low radiation exposure. Measurements are most commonly made over the lumbar spine and over the upper part of the hip. The forearm may be scanned if the hip and lumbar spine are not accessible.
There is a statistical association between poor bone density and higher probability of fracture. Fractures of the legs and pelvis due to falls are a significant public health problem, especially in elderly women, leading to much medical cost, inability to live independently and even risk of death. Bone density measurements are used to screen people for osteoporosis risk and to identify those who might benefit from measures to improve bone strength.
Indications for Testing
The following are risk factors for low bone density and primary considerations for the need for a bone density test.
- Females age 65 or older
- Males age 70 or older
- People over age 50 with any of the following:
- previous bone fracture from minor trauma
- rheumatoid arthritis
- low body weight
- a parent with a hip fracture
- Individuals with vertebral abnormalities.
- Individuals receiving, or planning to receive, long-term glucocorticoid (steroid) therapy.
- Individuals with primary hyperparathyroidism.
- Individuals being monitored to assess the response or efficacy of an approved osteoporosis drug therapy.
- Individuals with a history of eating disorders
Other considerations which related to risk of low bone density and the need for a test include smoking habits, drinking habits, the long-term use of corticosteroid drugs, and a vitamin D deficiency.
Types of Tests
DXA is currently the most widely used, but quantitative ultrasound (QUS) has been described as a more cost-effective approach to measure bone density. The DXA test works by measuring a specific bone or bones, usually the spine, hip, and wrist. The density of these bones is then compared with an average index based on age, sex, and size. The resulting comparison is used to determine risk for fractures and the stage of osteoporosis (if any) in an individual.
Average bone mineral density = BMC / W [g/cm2]
- BMC = bone mineral content = g/cm
- W = width at the scanned line
Results are generally scored by two measures, the T-score and the Z-score. Scores indicate the amount one's bone mineral density varies from the mean. Negative scores indicate lower bone density, and positive scores indicate higher.
The T-score is the relevant measure when screening for osteoporosis. It is the bone mineral density (BMD) at the site when compared to the young normal reference mean. It is a comparison of a patient's BMD to that of a healthy 30-year-old. The US standard is to use data for a 30-year-old of the same sex and ethnicity, but the WHO recommends using data for a 30-year-old white female for everyone. Values for 30-year-olds are used in post-menopausal women and men over age 50 because they better predict risk of future fracture. The criteria of the World Health Organization are:
- Normal is a T-score of −1.0 or higher
- Osteopenia is defined as between −1.0 and −2.5
- Osteoporosis is defined as −2.5 or lower, meaning a bone density that is two and a half standard deviations below the mean of a 30-year-old man/woman.
|Hip fractures per 1000 patient-years
||Age > 64
The Z-score is the comparison to the age-matched normal and is usually used in cases of severe osteoporosis. This is the number of standard deviations a patient's BMD differs from the average BMD of their age, sex, and ethnicity. This value is used in premenopausal women, men under the age of 50, and in children. It is most useful when the score is less than 2 standard deviations below this normal. In this setting, it is helpful to scrutinize for coexisting illnesses or treatments that may contribute to osteoporosis such as glucocorticoid therapy, hyperparathyroidism, or alcoholism.
Breast Cancer Screening
Breast cancer is cancer that develops from breast tissue. Signs of breast cancer may include a lump in the breast, a change in breast shape, dimpling of the skin, fluid coming from the nipple, a newly inverted nipple, or a red or scaly patch of skin. In those with distant spread of the disease, there may be bone pain, swollen lymph nodes, shortness of breath, or yellow skin.
It is recommended that screening for Breast Cancer should be done every two years in women 50 to 74 years old.
The medications tamoxifen or raloxifenemay be used in an effort to prevent breast cancer in those who are at high risk of developing it.
Surgical removal of both breasts is another preventative measure in some high risk women.
In those who have been diagnosed with cancer, a number of treatments may be used, including surgery, radiation therapy, chemotherapy, hormonal therapy and targeted therapy.
Types of surgery vary from breast-conserving surgery to mastectomy. Breast reconstruction may take place at the time of surgery or at a later date.
Worldwide, breast cancer is the leading type of cancer in women, accounting for 25% of all cases. In 2012 it resulted in 1.68 million new cases and 522,000 deaths. It is more common in developed countries and is more than 100 times more common in women than in men.
Modifiable risk factors- things that people can change themselves, such as consumption of alcoholic beverages.
Fixed risk factors- things that cannot be changed, such as age and biological sex.
The primary risk factors for breast cancer are being female and older age. Other potential risk factors include genetics,
lack of childbearing or lack of breastfeeding, higher levels of certain hormones, certain dietary patterns, and obesity.
One study indicates that exposure to light pollution is a risk factor for the development of breast cancer.
Smoking tobacco appears to increase the risk of breast cancer, with the greater the amount smoked and the earlier in life that smoking began, the higher the risk.
In those who are long-term smokers, the risk is increased 35% to 50%. A lack of physical activity has been linked to about 10% of cases.
High fat diet, high alcohol intake, and obesity-related high cholesterol levels, dietary iodine deficiency may also play a role.
Genetics is the primary cause of 5–10% of all cases.
Women whose mother was diagnosed before 50 have an increased risk of 1.7 and those whose mother was diagnosed at age 50 or after has an increased risk of 1.4.
Atypical ductal hyperplasia and lobular carcinoma in situ, found in benign breast conditions such as fibrocystic breast changes increases breast cancer risk.
Diabetes mellitus also increases the risk of breast cancer. Autoimmune diseases such as lupus erythematosusincreases the risk for breast cancer.
Early signs of possible breast cancer. Breast cancer showing an inverted nipple, lump, and skin dimpling.
Signs and symptoms :
The first noticeable symptom of breast cancer is typically a lump that feels different from the rest of the breast tissue. More than 80% of breast cancer cases are discovered when the woman feels a lump. The earliest breast cancers are detected by a mammogram. Lumps found in lymph nodes located in the armpits can also indicate breast cancer.
Indications of breast cancer other than a lump may include thickening different from the other breast tissue, one breast becoming larger or lower, a nipple changing position or shape or becoming inverted, skin puckering or dimpling, a rash on or around a nipple, discharge from nipple/s, constant pain in part of the breast or armpit, and swelling beneath the armpit or around the collarbone. Pain ("mastodynia") is an unreliable tool in determining the presence or absence of breast cancer, but may be indicative of other breast health issues.
Inflammatory breast cancer is a particular type of breast cancer which can pose a substantial diagnostic challenge. Symptoms may resemble a breast inflammation and may include itching, pain, swelling, nipple inversion, warmth and redness throughout the breast, as well as an orange-peel texture to the skin referred to as peaud'orange. As inflammatory breast cancer does not present as a lump there can sometimes be a delay in diagnosis.
Another reported symptom complex of breast cancer is Paget's disease of the breast. This syndrome presents as skin changes resembling eczema, such as redness, discoloration, or mild flaking of the nipple skin. As Paget's disease of the breast advances, symptoms may include tingling, itching, increased sensitivity, burning, and pain. There may also be discharge from the nipple. Approximately half of women diagnosed with Paget's disease of the breast also have a lump in the breast.
In rare cases, what initially appears as a fibroadenoma (hard, movable non-cancerous lump) could in fact be a phyllodes tumor. Phyllodes tumors are formed within the stroma (connective tissue) of the breast and contain glandular as well as stromal tissue. Phyllodes tumors are classified on the basis of their appearance under the microscope as benign, borderline, or malignant.
Occasionally, breast cancer presents as metastatic disease—that is, cancer that has spread beyond the original organ. The symptoms caused by metastatic breast cancer will depend on the location of metastasis. Common sites of metastasis include bone, liver, lung and brain. Unexplained weight loss can occasionally signal breast cancer, as can symptoms of fevers or chills. Bone or joint pains can sometimes be manifestations of metastatic breast cancer, as can jaundice or neurological symptoms.
These symptoms are called non-specific, meaning they could be manifestations of many other illnesses.
Fewer than 20% of lumps are cancerous, and benign breast diseases such as mastitis and fibroadenoma of the breast are more common causes of breast disorder symptoms.
Mammography is a common screening method, since it is relatively fast and widely available in developed countries.
Medical ultrasonography is a diagnostic aid to mammography. Adding ultrasonography testing for women with dense breast tissue increases the detection of breast cancer.
Magnetic resonance imaging(MRI) :
Magnetic resonance imaging (MRI) has been shown to detect cancers not visible on mammograms. A negative MRI can rule out the presence of cancer to a high degree of certainty, making it an excellent tool for screening in patients at high genetic risk or radiographically dense breasts, and for pre-treatment staging where the extent of disease is difficult to determine on mammography and ultrasound. MRI can diagnose benign proliferative change, fibroadenomas, and other common benign findings at a glance, often eliminating the need for costly and unnecessary biopsies or surgical procedures. The spatial and temporal resolution of breast MRI has increased markedly in recent years, making it possible to detect or rule out the presence of small in situ cancers, including ductal carcinoma in situ.
Breast cancer is usually treated with surgery, which may be followed by chemotherapy or radiation therapy, or both.
An Echocardiogramat Chandan Hospital is a sonogram of the heart. Echocardiography uses standard two-dimensional,
three-dimensional, and Doppler ultrasound to create images of the heart.
Echocardiography has become routinely used in the diagnosis, management, and follow-up of patients with any suspected or known heart diseases.
It is one of the most widely used diagnostic tests in cardiology.
It can provide a wealth of helpful information, including the size and shape of the heart (internal chamber size quantification), pumping capacity, and the location and extent of any tissue damage.
An echocardiogram can also give physicians other estimates of heart function, such as a calculation of the cardiac output, ejection fraction, and diastolic function (how well the heart relaxes).
Echocardiography can help detect cardiomyopathies, such as hypertrophic cardiomyopathy, dilated cardiomyopathy, and many others.
The use of stress echocardiography may also help determine whether any chest pain or associated symptoms are related to heart disease.
The biggest advantage to echocardiography is that it is not invasive (does not involve breaking the skin or entering body cavities) and has no known risks or side effects.
Not only can an echocardiogram create ultrasound images of heart structures, but it can also produce accurate assessment of the blood flowing through the heart by Doppler echocardiography, using pulsed- or continuous-wave Doppler ultrasound.
This allows assessment of both normal and abnormal blood flow through the heart.
Color Doppler, as well as spectral Doppler, is used to visualize any abnormal communications between the left and right sides of the heart, any leaking of blood through the valves (valvular regurgitation), and estimate how well the valves open (or do not open in the case of valvular stenosis). The Doppler technique can also be used for tissue motion and velocity measurement, by tissue Doppler echocardiography.
How Safe Is Echocardiography?
It is absolutely safe. There are no known risks of the ultrasound in this type of testing.
Medical Uses :
Echocardiography is a significant tool in providing the physician important information about heart on the following :
- Size of the chambers, volume and the thickness of the walls
- Pumping function, if it is normal or reduced to a mild/severe degree
- Valve function – structure, thickness and movement of heart’s valves
- Volume status as low blood pressure may occur as a result of poor heart function
- Pericardial effusion (fluid in the pericardium and the sac that surrounds the heart), congenital heart disease, blood clots or tumours, abnormal elevation of pressure within the lungs etc.
Trans-Thoracic Echocardiogram :
A standard echocardiogram is also known as a transthoracic echocardiogram, or cardiac ultrasound.
In this case, the echocardiography transducer (or probe) is placed on the chest wall (or thorax) of the subject, and images are taken through the chest wall.
This is a noninvasive, highly accurate, and quick assessment of the overall health of the heart.
Trans-Esophageal Echocardiogram :
This is an alternative way to perform an echocardiogram.
A specialized probe containing an ultrasound transducer at its tip is passed into the patient's esophagus.
This allows image and Doppler evaluation from a location directly behind the heart. This is known as a transesophageal echocardiogram.
Transesophageal echocardiograms are most often used when transthoracic images are suboptimal and when a more clear and precise image is needed for assessment.
Stress Echocardiography :
A stress echocardiogram, also known as a stress echo, uses ultrasound imaging of the heart to assess the wall motion in response to physical stress.
First, images of the heart are taken "at rest" to acquire a baseline of the patient's wall motion at a resting heart rate.
The patient then walks on a treadmill or uses another exercise modality to increase the heart rate to his or her target heart rate,
or 85% of the age-predicted maximum heart rate (220 − patient's age). Finally, images of the heart are taken "at stress" to assess wall motion at the peak heart rate.
A stress echo assesses wall motion of the heart; it does not, however, create an image of the coronary arteries directly.
Ischemia of one or more coronary arteries could cause a wall motion abnormality, which could indicate coronary artery disease.
The gold standard test to directly create an image of the coronary arteries and directly assess for stenosis or occlusion is a cardiac catheterization.
A stress echo is not invasive and is performed in the presence of a licensed medical professional, such as a cardiologist, and a cardiac sonographer.
Three-Dimensional Echocardiography :
Three-dimensional echocardiogram of a heart viewed from the apex Three-dimensional echocardiography (also known as four-dimensional echocardiography when the picture is moving)
is now possible, using a matrix array ultrasound probe and an appropriate processing system.
This enables detailed anatomical assessment of cardiac pathology, particularly valvular defects, and cardiomyopathies.
The ability to slice the virtual heart in infinite planes in an anatomically appropriate manner and to reconstruct
three-dimensional images of anatomic structures make it unique for the understanding of the congenitally malformed heart.
Real-time three-dimensional echocardiography can be used to guide the location of bioptomes during right ventricular endomyocardial biopsies,
placement of catheter-delivered valvular devices, and in many other intraoperative assessments.
Contrast Echocardiography :
Contrast echocardiography, or contrast-enhanced ultrasound is the addition of an ultrasound contrast medium, or imaging agent, to traditional ultrasonography.
The ultrasound contrast is made up of tiny microbubbles filled with a gas core and protein shell. This allows the microbubbles to circulate through
the cardiovascular system and return the ultrasound waves, creating a highly reflective image.
There are multiple applications in which contrast-enhanced ultrasound can be useful.
The most commonly used application is in the enhancement of LV endocardial borders for assessment of global and regional systolic function.
Contrast may also be used to enhance visualization of wall thickening during stress echocardiography, for the assessment of LV thrombus,
or for the assessment of other masses in the heart. Contrast echocardiography has also been used to assess blood perfusion
throughout myocardium in the case of coronary artery disease.
Magnetic Resonance Imaging(MRI)
Magnetic resonance imaging is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body in both health and disease.
MRI scanners use strong magnetic fields, electric field gradients, and radio waves to generate images of the organs in the body.
MRI does not involve X-rays and the use of ionizing radiation, which distinguishes it from CT or CAT scans. Magnetic resonance imaging is a medical application of nuclear magnetic resonance (NMR).
NMR can also be used for imaging in other NMR applications such as NMR spectroscopy.
While the hazards of X-rays are now well-controlled in most medical contexts, MRI may still be seen as a better choice than CT.
MRI is widely used in hospitals and clinics for medical diagnosis, staging of disease and follow-up without exposing the body to radiation. However, MRI may often yield different diagnostic information compared with CT.
There may be risks and discomfort associated with MRI scans. Compared with CT scans, MRI scans typically take longer and are louder, and they usually need the subject to enter a narrow, confining tube.
In addition, people with some medical implants or other non-removable metal inside the body may be unable to undergo an MRIexamination safely.
MRI has a wide range of applications in medical diagnosis and more than 25,000 scanners are estimated to be in use worldwide. MRI affects diagnosis and treatment in many specialties although the effect on improved health outcomes is uncertain.
MRI is the investigation of choice in the preoperative staging of rectal and prostate cancer and, has a role in the diagnosis, staging, and follow-up of other tumors.
MRI is the investigative tool of choice for neurological cancers, as it has better resolution than CT and offers better visualization of the posterior fossa. The contrast provided between grey and white matter makes MRI the best choice for many conditions of the central nervous system, including demyelinating diseases, dementia, cerebrovascular disease, infectious diseases, and epilepsy. Since many images are taken milliseconds apart, it shows how the brain responds to different stimuli, enabling researchers to study both the functional and structural brain abnormalities in psychological disorders. MRI also is used in guided stereotactic surgery and radiosurgery for treatment of intracranial tumors, arteriovenous malformations, and other surgically treatable conditions using a device known as the N-localizer.
Cardiac MRI is complementary to other imaging techniques, such as echocardiography, cardiac CT, and nuclear medicine. Its applications include assessment of myocardial ischemia and viability, cardiomyopathies, myocarditis, iron overload, vascular diseases, and congenital heart disease.
Applications in the musculoskeletal system include spinal imaging, assessment of joint disease, and soft tissue tumors.
Liver and gastrointestinal :
Hepatobiliary MR is used to detect and characterize lesions of the liver, pancreas, and bile ducts. Focal or diffuse disorders of the liver may be evaluated using diffusion-weighted, opposed-phase imaging, and dynamic contrast enhancement sequences. Extracellular contrast agents are used widely in liver MRI and newer hepatobiliary contrast agents also provide the opportunity to perform functional biliary imaging. Anatomical imaging of the bile ducts is achieved by using a heavily T2-weighted sequence in magnetic resonance cholangiopancreatography (MRCP). Functional imaging of the pancreas is performed following administration of secretin. MR enterography provides non-invasive assessment of inflammatory bowel disease and small bowel tumors. MR-colonography may play a role in the detection of large polyps in patients at increased risk of colorectal cancer.
Magnetic resonance angiography (MRA) generates pictures of the arteries to evaluate them for stenosis (abnormal narrowing) or aneurysms (vessel wall dilatations, at risk of rupture). MRA is often used to evaluate the arteries of the neck and brain, the thoracic and abdominal aorta, the renal arteries, and the legs (called a "run-off"). A variety of techniques can be used to generate the pictures, such as administration of a paramagnetic contrast agent (gadolinium) or using a technique known as "flow-related enhancement" (e.g., 2D and 3D time-of-flight sequences), where most of the signal on an image is due to blood that recently moved into that plane (see also FLASH MRI). Techniques involving phase accumulation (known as phase contrast angiography) can also be used to generate flow velocity maps easily and accurately. Magnetic resonance venography (MRV) is a similar procedure that is used to image veins. In this method, the tissue is now excited inferiorly, while the signal is gathered in the plane immediately superior to the excitation plane—thus imaging the venous blood that recently moved from the excited plane.
Pulmonary Function Test(PFT)
Pulmonary function test (PFT) is a complete evaluation of the respiratory system including patient history, physical
examinations, and tests of pulmonary function. The primary purpose of pulmonary function testing is to identify the severity
of pulmonary impairment. Pulmonary function testing has diagnostic and therapeutic roles and helps clinicians
answer some general questions about patients with lung disease. PFTs are normally performed by a respiratory therapist.
Pulmonary function testing is a diagnostic and management tool used for a variety of reasons, such as:
- Chronic shortness of breath
- Chronic obstructive pulmonary disease
- Restrictive lung disease
- Preoperative testing
- Impairment or disability
Spirometry includes tests of pulmonary mechanics – measurements of FVC, FEV1, FEF values, forced inspiratory flow rates (FIFs), and MVV.
Measuring pulmonary mechanics assesses the ability of the lungs to move huge volumes of air quickly through the airways to identify airway obstruction.
The measurements taken by the spirometry device are used to generate a pneumotachograph that can help to assess lung conditions such as: asthma, pulmonary fibrosis, cystic fibrosis, and chronic obstructive pulmonary disease.
Physicians may also use the test results to diagnose bronchial hyperresponsiveness to exercise, cold air, or pharmaceutical agents.
There are four lung volumes and four lung capacities. A lung's capacity consists of two or more lung volumes.
The lung volumes are tidal volume (VT), inspiratory reserve volume (IRV), expiratory reserve volume (ERV), and residual volume(RV).
The four lung capacities are total lung capacity (TLC), inspiratory capacity (IC), functional residual capacity (FRC) and vital capacity (VC).
Maximal respiratory pressures-
Measurement of maximal inspiratory and expiratory pressures is indicated whenever there is an unexplained decrease
in vital capacity or respiratory muscle weakness is suspected clinically.
Maximal inspiratory pressure (MIP) is the maximal pressure that can be produced by
the patient trying to inhale through a blocked mouthpiece. Maximal expiratory pressure
(MEP) is the maximal pressure measured during forced expiration (with cheeks bulging)
through a blocked mouthpiece after a full inhalation. Repeated measurements of MIP and MEP are useful in following the course of patients with neuromuscular disorders.
Measurement of the single-breath diffusing capacity for carbon monoxide (DLCO) is
a fast and safe tool in the evaluation of both restrictive and obstructive lung disease.
Oxygen desaturation during exercise-
The six-minute walk test is a good index of physical function and therapeutic response in patients with chronic
lung disease, such as COPD or idiopathic pulmonary fibrosis.
Arterial blood gases-
Arterial blood gases (ABGs) are a helpful measurement in pulmonary function testing in selected patients.
The primary role of measuring ABGs in individuals that are healthy and stable is to confirm hypoventilation when it is suspected
on the basis of medical history, such as respiratory muscle weakness or advanced COPD.
ABGs also provide a more detailed assessment of the severity of hypoxemia in patients who have low normal oxyhemoglobin saturation.
Nerve Conduction Velocity
Nerve conduction velocity is an important aspect of nerve conduction studies. It is the speed at which an electrochemical impulse propagates down a neural pathway. Conduction velocities are affected by a wide array of factors, including age, sex, and various medical conditions. Studies allow for better diagnoses of various neuropathies, especially demyelinating conditions as these conditions result in reduced or non-existent conduction velocities.
Nerve conduction studies:
Nerve Conduction Velocity is just one of many measurements commonly made during a nerve conduction study (NCS). The purpose of these studies is to determine whether nerve damage is present and how severe that damage may be.
Nerve conduction studies are performed as follows:
- Two electrodes are attached to the subject's skin over the nerve being tested.
- Electrical impulses are sent through one electrode to stimulate the nerve.
- The second electrode records the impulse sent through the nerve as a result of stimulation.
- The time difference between stimulation from the first electrode and pick-up by the downstream electrode is known as the latency. Nerve conduction latencies are typically on the order of milliseconds.
Although conduction velocity itself is not directly measured, calculating conduction velocities from NCS measurements is trivial. The distance between the stimulating and receiving electrodes is divided by the impulse latency, resulting in conduction velocity.
Many times, Needle EMG is also performed on subjects at the same time as other NCS procedures because they aid in detecting whether muscles are functioning properly in response to stimuli sent via their connecting nerves. EMG is the most important component of electrodiagnosis of motor neuron diseases as it often leads to the identification of motor neuron involvement before clinical evidence can be seen.
Micromachined 3D electrode arrays:
Typically, the electrodes used in an EMG are stuck to the skin over a thin layer of gel/paste. This allows for better conduction between electrode and skin. However, as these electrodes do not pierce the skin, there are impedances that result in erroneous readings, high noise levels, and low spatial resolution in readings.
To address these problems, new devices are being developed, such as 3-dimensional electrode arrays. These are MEMS devices that consist of arrays of metal micro-towers capable of penetrating the outer layers of skin, thus reducing impedance.
Compared with traditional wet electrodes, multi-electrode arrays offer the following:
- Electrodes are about 1/10 the size of standard wet surface electrodes
- Arrays of electrodes can be created and scaled to cover areas of almost any size
- Reduced impedance
- Improved signal power
- Higher amplitude signals
- Allow better real-time nerve impulse tracking
Medical conditions -
Amyotrophic lateral sclerosis (ALS) -
Amyotrophic Lateral Sclerosis (ALS) is a progressive and inevitably fatal neurodegenerative disease affecting the motor neurons. Because ALS shares many symptoms with other neurodegenerative diseases, it can be difficult to diagnose properly. The best method of establishing a confident diagnosis is via electrodiagnostic evaluation. To be specific, motor nerve conduction studies of the Median, Ulnar, and peroneal muscles should be performed, as well as sensory nerve conduction studies of the Ulnar and Sural nerves.
In patients with ALS, it has been shown that distal motor latencies and slowing of conduction velocity worsened as the severity of their muscle weakness increased. Both symptoms are consistent with the axonal degeneration occurring in ALS patients.
Carpal tunnel syndrome -
Carpal tunnel syndrome (CTS) is a form of nerve compression syndrome caused by the compression of the median nerve at the wrist. Typical symptoms include numbness, tingling, burning pains, or weakness in the hand. CTS is another condition for which electrodiagnostic testing is valuable. However, before subjecting a patient to nerve conduction studies, both Tinel's test and Phalen's test should be performed. If both results are negative, it is very unlikely that the patient has CTS, and further testing is unnecessary.
Carpal tunnel syndrome presents in each individual to different extents. Measurements of nerve conduction velocity are critical to determining the degree of severity.
These levels of severity are categorized as:
- Mild CTS: Prolonged sensory latencies, very slight decrease in conduction velocity. No suspected axonal degeneration.
- Moderate CTS: Abnormal sensory conduction velocities and reduced motor conduction velocities. No suspected axonal degeneration.
- Severe CTS: Absence of sensory responses and prolonged motor latencies (reduced motor conduction velocities).
- Extreme CTS: Absence of both sensory and motor responses.
One common electrodiagnostic measurement includes the difference between sensory nerve conduction velocities in the pinkie finger and index finger. In most instances of CTS, symptoms will not present until this difference is greater than 8 m/s.
Guillain–Barré syndrome -
Guillain–Barré syndrome (GBS) is a peripheral neuropathy involving the degeneration of myelin sheathing and/or nerves that innervate the head, body, and limbs. This degeneration is due to an autoimmune response typically initiated by various infections.
Two primary classifications exist: demyelinating (Schwann cell damage) and axonal (direct nerve fiber damage). Each of these then branches into additional sub-classifications depending on the exact manifestation. In all cases, however, the condition results in weakness or paralysis of limbs, the potentially fatal paralysis of respiratory muscles, or a combination of these effects.
The disease can progress very rapidly once symptoms present (severe damage can occur within as little as a day). Because electrodiagnosis is one of the fastest and most direct methods of determining the presence of the illness and its proper classification, nerve conduction studies are extremely important. Without proper electrodiagnostic assessment, GBS is commonly misdiagnosed as Polio, West Nile virus, Tick paralysis, various Toxic neuropathies, CIDP, Transverse myelitis, or Hysterical paralysis. Two sets of nerve conduction studies should allow for proper diagnosis of Guillain–Barré syndrome. It is recommended that these be performed within the first 2 weeks of symptom presentation and again sometime between 3 and 8 weeks.
Electrodiagnostic findings that may implicate GBS include:
- Complete conduction blocks
- Abnormal or absent F waves
- Attenuated compound muscle action potential amplitudes
- Prolonged motor neuron latencies
- Severely slowed conduction velocities (sometimes below 20 m/s)
Lambert-Eaton myasthenic syndrome -
Lambert–Eaton myasthenic syndrome (LEMS) is an autoimmune disease in which auto-antibodies are directed against voltage-gated calcium channels at presynaptic nerve terminals. Here, the antibodies inhibit the release of neurotransmitters, resulting in muscle weakness and autonomic dysfunctions.
Nerve conduction studies performed on the Ulnar motor and sensory, Median motor and sensory, Tibial motor, and Peroneal motor nerves in patients with LEMS have shown that the conduction velocity across these nerves is actually normal. However, the amplitudes of the compound motor action potentials may be reduced by up to 55%, and the duration of these action potentials decreased by up to 47%.
Peripheral diabetic neuropathy -
At least half the population with diabetes mellitus is also affected with diabetic neuropathy, causing numbness and weakness in the peripheral limbs. Studies have shown that the Rho/Rho-kinase signaling pathway is more active in individuals with diabetes and that this signaling activity occurs mainly in the nodes of Ranvier and Schmidt-Lanterman incisures. Therefore, over-activity of the Rho/Rho-kinase signaling pathway may inhibit nerve conduction.
Motor nerve conduction velocity studies revealed that conductance in diabetic rats was about 30% lower than that of the non-diabetic control group. In addition, activity along the Schmidt-Lanterman incisures was non-continuous and non-linear in the diabetic group, but linear and continuous in the control. These deficiencies were eliminated after the administration of Fasudil to the diabetic group, implying that it may be a potential treatment.