Categories
Diagnonistic Test

Magnetic Resonance Imaging (MRI)

fMRI - Functional magnetic resonance imaging s...
Image by MacRonin47 via Flickr

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Definition:
MRI is a noninvasive technique for visualizing many different body tissues. Unlike x-rays, MRI does not use any radiation. Instead, it uses radio waves, a large magnet, and a computer to create images.As with a CT scan, which does use x-rays, each MRI picture shows a different “slice,” or cross-section, of the area being viewed. Because these slices usually are spaced about a quarter-inch apart, your doctor can get a detailed representation of a particular area.

Most MRI machines are large, tube-shaped magnets. When you lie inside an MRI machine, the magnetic field temporarily aligns all the water molecules in your body. Radio waves cause these aligned particles to produce very faint signals, which are used to create cross-sectional MRI images — like slices in a loaf of bread.

The MRI machine can combine these slices to produce 3-D images that may be viewed from many different angles.

CLICK & SEE THE PICTURES 
You may click to see more MRI pictures

MRI of the brain and spinal cord:
MRI is the most sensitive imaging test of the brain and spinal cord. It’s often performed to help diagnose:

*Tumors
*Developmental abnormalities
*Aneurysms
*Stroke
*Pituitary gland diseases
*Multiple sclerosis
*Dementia progression
*Spinal cord injuries

Functional MRI of the brain (fMRI) can be used to identify important language and movement control areas in the brain in people who are being considered for brain surgery.

MRI of the heart and blood vessels:
An MRI that focuses on the heart or blood vessels can assess:

*The size and thickness of walls in the heart’s chambers
*The extent of damage caused by heart attack or heart disease
*The buildup of plaques and blockages in the blood vessels
*Structural problems in the aorta, such as aneurysms or dissections
*MRI of other internal organs

An MRI may be used to check for tumors or other abnormalities of the:

*Lungs
*Liver
*Kidneys
*Spleen
*Pancreas
*Uterus
*Ovaries
*Prostate
*Testicles

MRI of bones and joints
MRI may be used to help evaluate:

*Joint disorders, such as arthritis
*Joint abnormalities caused by traumatic or repetitive injuries
*Disk abnormalities in the spine
*Bone infections

MRI of the breasts
MRI may be used in addition to mammography to detect breast cancer, particularly in women who have dense breast tissue or who may be at high risk of the disease.


Risks Factors
:
For most individuals, there are no known harmful effects from exposure to the magnetic field or radio waves used in making MRI images. Allergic reactions to the dye are very rare.

Preparation for the test:-
Before an MRI exam, eat normally and continue to take your usual medications, unless otherwise instructed. You will be asked to change into a gown and to remove:

*Jewelry
*Hairpins
*Eyeglasses
*Watches
*Wigs
*Dentures
*Hearing aids
*Underwire bras

The presence of metal in your body may be a safety hazard or affect a portion of the MRI image. Tell the technologist if you have any metal or electronic devices in your body, such as:

*Metallic joint prostheses
*Artificial heart valves
*An implantable heart defibrillator
*A pacemaker
*Metal clips to prevent aneurysms from leaking
*Cochlear implants
*A bullet, shrapnel or any other type of metal fragment

Also tell the technologist if you think you’re pregnant, because the effects of magnetic fields on fetuses aren’t well understood. Your doctor may recommend choosing an alternative exam or postponing the MRI.

It’s also important to discuss any kidney or liver problems with your physician and the technologist, because problems with these organs may impose limitations on the use of injected contrast agents during your scan

If you know you have an implant, or are concerned, discuss the issue with your doctor, as other options may exist. (Some pacemakers, for example, can be reprogrammed prior to an MRI so that they are not disrupted.)

An IV is inserted into a vein if the particular scan you’re having requires a dye to make areas of inflammation or abnormality easier to detect. This dye is called gadolinium, and is different from the contrast dye used for x-rays or CT scans. Before undergoing the scan, remove metal objects such as belt buckles or watches, which could dislodge in the presence of the magnet and hurt you.

What happens when the test is performed?

During the test:
The MRI machine looks like a tunnel that has both ends open. You lie down on a movable table that slides into the opening of the tunnel. A technologist monitors you from another room. You can talk with him or her by microphone.

The MRI machine creates a strong magnetic field around you, and radio waves are directed at your body. The procedure is painless. You don’t feel the magnetic field or radio waves, and there are no moving parts around you.

During the MRI scan, the internal part of the magnet produces repetitive tapping, thumping sounds and other noises. Earplugs or music may be provided to help block the noise. If you are worried about feeling claustrophobic inside the MRI machine, talk to your doctor beforehand. He or she may make arrangements for you to receive a sedative before the scan.

An MRI typically lasts about an hour. You must hold very still because movement can blur the resulting images. In some cases, contrast agents are injected into your veins to enhance the appearance of certain tissues or blood vessels in the images.

During a functional MRI, you may be asked to perform a number of small tasks — such as tapping your thumb against your fingers, rubbing a block of sandpaper or answering simple questions. This helps pinpoint the portions of your brain that control these actions.

After the test:
If you haven’t been sedated, you may resume your usual activities immediately after the scan. Nursing mothers shouldn’t breast-feed for 36 to 48 hours after an MRI if a contrast material was used. Very rarely, the contrast material can cause hives and itching.

A radiologist — a doctor specially trained to interpret MRIs — will analyze the images from your scan and report the findings to your doctor. Your doctor will then discuss any important findings and next steps with you.

It can be difficult if you are uneasy in tight spaces or have trouble lying flat for that amount of time. If you think you might have trouble getting through the procedure, talk to your doctor beforehand and discuss whether an anti-anxiety medicine might help. After the test is done, you can go about your normal activities.

How long is it before the result of the test is known?
MRI images are often recorded on film; if so, it will take at least an hour for the MRI department to develop the images and additional time for a doctor to examine and interpret them. If the images are stored in and displayed by a computer, there is no time required to develop the images, although the doctor’s interpretation still takes time. You can probably get preliminary results within a day or two, but the complete results might take four to seven days.

Resources:
http://www.mayoclinic.com/health/mri/MY00227
https://www.health.harvard.edu/diagnostic-tests/magnetic-resonance-imaging-of-the-brain.htm
http://www.draimaging.com/mri.htm

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Categories
Diagnonistic Test

Lumbar Puncture (or Spinal Tap)

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Definition:
A lumbar puncture, also known as a spinal tap, uses a needle to remove a sample of fluid from the space surrounding the spinal cord. This fluid is known as cerebrospinal fluid (CSF). The test is used to diagnose meningitis infections and some neurological conditions.

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It is a procedure to collect cerebrospinal fluid to check for the presence of disease or injury. A spinal needle is inserted, usually between the 3rd and 4th lumbar vertebrae in the lower spine. Once the needle is properly positioned in the subarachnoid space (the space between the spinal cord and its covering, the meninges), pressures can be measured and fluid can be collected for testing.

Cerebral spinal fluid (CSF) is a clear fluid that circulates in the space surrounding the spinal cord and brain. CSF protects the brain and spinal cord from injury by acting like a liquid cushion. CSF is usually obtained through a lumbar puncture (spinal tap).

Preparation for the Test:

You will need to sign a consent form, which is generally required when the procedure is done outside of an emergency situation. Tell your doctor ahead of time if you have ever had an allergic reaction to lidocaine or the numbing medicine used at the dentist’s office.
Doctors routinely do a physical examination and in some cases order a brain scan before recommending a lumbar puncture, to make sure you do not have a medical condition that could put you at risk for movement of the brain during the procedure, a very rare but serious complication.

What happens when the test is performed?
Most patients wear a hospital gown. Typically, you lie on your side with your knees curled up against your chest. In some cases, the doctor asks you to sit on the bed or a table instead, leaning forward against some pillows.

The doctor feels your back to locate your lower vertebrae and feels the bones in the back of your pelvis. An area on your lower back is cleaned with soap. Medicine is injected through a small needle to numb the skin and the tissue underneath the skin in the area from which the sample is to be removed. This causes some very brief stinging.

A different needle is then placed in the same area and moved forward until fluid can be obtained through it from the spinal canal. Because the needle must be placed through a small opening between two bones, the doctor must sometimes move the needle in and out several times to locate the opening. Because of the numbing medicine used in this area, most patients experience only a sense of pressure from this movement. Occasionally some patients do get a sharp feeling in the back or (rarely) in the leg. Let your doctor know if you feel any pain.

Sometimes the doctor measures the pressure of the fluid before taking a sample. The pressure is measured with a tube that looks like a large thermometer held against the needle. The fluid sample collected is usually less than three tablespoons. You will not feel any discomfort when it is removed. After this, the needle is taken out. Usually a Band-Aid is the only dressing necessary.

The whole lumbar puncture, including set-up time, takes 30–45 minutes. The needle is in place for close to one minute.

Risk Factors:
The most common risk of a lumbar puncture is that it can cause a temporary headache. Lying down for a few hours after the test can make a headache less likely to occur. Other problems are rare and include infection or bleeding. Because the volume of fluid is small, a lumbar puncture almost never causes movement of the brain or spinal cord, a serious complication.

What Must you do special after the test is over?
You may be told to lie flat for a while after the test, sometimes for a few hours.

Time for the result of the test is known?
Depending on the tests being done on the fluid sample, results take anywhere from a few hours to a few days.
For more knowledge you may click to see:-…………………...(1).…….(2).…….(3)
Resources:
http://www.health.harvard.edu/diagnostic-tests/lumbar-puncture.htm
http://www.clarian.org/ADAM/doc/CancerCenter/10/000303.htm

http://www.nlm.nih.gov/medlineplus/ency/imagepages/9587.htm

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Categories
Diagnonistic Test

Electromyography and Nerve Conduction Studies (EMG)

Description: Electromyography (EMG) tests analyze nerve and muscle electrical activity. Some types of electrical activity are normal, whereas some patterns of electrical activity suggest a disease of nerves or muscles. Nerve conduction studies are tests that are often used in combination with the EMG evaluation. For nerve conduction studies, the muscles and nerves are stimulated with small bursts of electricity to see whether the nerves and muscles respond in a normal way.

CLICK & SEE

Preparation for the test: No preparation is necessary.

What happens when the test is performed?
For the EMG, thin needles are inserted one by one into the muscles being tested. These needles are not hollow, and they are thinner than the type of needle used to draw blood. Each needle is attached to a wire that gives signals to a machine. The needle acts like an antenna to detect electrical patterns inside the muscle and the nerves that are attached to that muscle. Most patients find this test mildly uncomfortable.

If you have nerve conduction studies done, small pads are taped to the skin on your hands or feet. These pads can both deliver mild electric shocks and detect electric signals coming through the skin. The shocks that are used are too small to be harmful. They feel similar to the kind of shock you might feel if you rubbed your feet on the carpet and then touched a doorknob. You might feel one of your muscles twitch when the electricity is delivered.

Testing times vary, depending on how many muscles are being tested. EMG testing takes 20 to 30 minutes. If nerve conduction studies are also done, testing may require as long as one hour.

Risk Factor : There are no risks. The needles used in the EMG are too small to put you at significant risk for bleeding or infection. The shocks do not shock your whole body and are too mild to cause any damage.

Anything special to be done after the test is over : Nothing.

Time to know the result:
A neurologist interprets the electrical signals measured in your muscles and sends a report to your doctor within a few days

Resources:
http://www.health.harvard.edu/diagnostic-tests/electromyography-and-nerve-conduction-studies.htm

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Categories
Diagnonistic Test

Carotid Ultrasound (Carotid Doppler)

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Definition:
Ultrasound uses sound waves instead of radiation to generate snapshots or moving pictures of structures inside the body. This imaging technique works in a manner similar to radar and sonar, developed in World War II to detect airplanes, missiles, and submarines that were otherwise invisible. After coating your skin with a lubricant to reduce friction, a radiologist or ultrasound technician places an ultrasound transducer, which looks like a microphone, on your skin and may rub it back and forth to get the right view. The transducer sends sound waves into your body and picks up the echoes of the sound waves as they bounce off internal organs and tissue. A computer transforms these echoes into an image that is displayed on a monitor…….....CLICK & SEE

Doppler ultrasound is a variation of this technique that not only shows internal structures but also examines the flow of blood through blood vessels. Using the Doppler effect—the change in the frequency of sound or light waves as they bounce off a moving object—this kind of ultrasound produces an image of blood in motion…..CLICK & SEE

A Carotid ultrasound shows the amount of blood flow in the carotid arteries, the major blood vessels to the brain located on either side of your neck. With this imaging technique, your doctor can see if there is any narrowing of your carotid arteries because of cholesterol deposits or some other problem. This test is often used to evaluate people who have had a stroke or who might be at high risk for one because of reduced blood flow in the carotid arteries…......CLICK & SEE.

Who Needs Carotid Ultrasound?
Carotid ultrasound checks for plaque buildup in the carotid arteries. This buildup can narrow or block your carotid arteries. You may need a carotid ultrasound if you:

*Had a stroke or ministroke recently.
*Have an abnormal sound in your carotid artery called a carotid bruit (broo-E).

Your doctor can hear a carotid bruit with the help of a stethoscope put on your neck over the carotid artery. A bruit can mean that there’s a partial blockage in your carotid artery that could lead to a stroke.
Your doctor also may order a carotid ultrasound if he or she suspects you may have:

*Blood clots that can slow blood flow in your carotid artery
*A split between the layers of your carotid artery wall that weakens the wall or reduces the blood flow to your brain
A carotid ultrasound also may be done to see whether carotid artery surgery has restored normal blood flow. If you had a procedure called carotid stenting, your doctor may order a carotid ultrasound afterward to check the position of the stent put in your carotid artery. (The stent, a small mesh tube, helps prevent the artery from becoming narrowed or blocked again.)

Sometimes carotid ultrasound is used as a preventive screening test in people who have medical conditions that increase their risk of stroke, including high blood pressure and diabetes. People with these conditions may benefit from having their carotid arteries checked regularly even if they show no signs of plaque buildup.

What To Expect Before Carotid Ultrasound
Carotid ultrasound is a painless test, and typically there is little to do in advance. Your doctor will tell you how to prepare for your carotid ultrasound.

Process of Performing the Test.:
After squirting some clear jelly onto one side of your neck to help the ultrasound sensor slide around easily, a technician places the sensor against your skin. An image then appears on a video screen . As the technician moves the sensor back and forth on your neck, different views of the carotid artery appear on the screen. As the equipment measures the blood flow through the artery, you hear a noise that sounds like your heartbeat. The other side of your neck is checked in the same way. This test usually takes 15–30 minutes.

The ultrasound machine includes a computer, a video screen, and a transducer, which is a hand-held device that sends and receives ultrasound waves into and from the body.

You will lie down on your back on an exam table for the test. Your technician or doctor will put a gel on your neck where your carotid arteries are located. This gel helps the ultrasound waves reach the arteries better. Your technician or doctor will put the transducer against different spots on your neck and move it back and forth.

FIG-A

 

 

 
……….Fig->A.
The above Figure shows how the ultrasound probe is placed over the carotid artery. Figure B is a color ultrasound image showing blood flow (the red color in the image) in the carotid artery. Figure C is a waveform image showing the sound of flowing blood in the carotid artery.

The transducer gives off ultrasound waves and detects their echoes after they bounce off the artery walls and blood cells. Ultrasound waves can’t be heard by the human ear.

A computer uses the echoes of the ultrasound waves bouncing off the carotid arteries to create and record images of the insides of the arteries (usually in black and white) and your blood flowing through them (usually in color; this is the Doppler ultrasound). A video screen displays these live images for your doctor to review.

Risk Factor:
There are no risks linked to having a carotid ultrasound, because the test uses harmless sound waves. These are the same type of sound waves that doctors use to record pictures of fetuses in pregnant women.

What one must do after the test is over?
Carotid ultrasound is usually done in a doctor’s office or hospital. The test is painless and usually doesn’t take more than 30 minutes.
Usually there is nothing special you have to do after a carotid ultrasound, and you should be able to return to normal activities immediately.

Often your doctor will be able to tell you the results of the carotid ultrasound when it occurs or soon afterward.

What Does a Carotid Ultrasound Show?
A carotid ultrasound can show whether buildup of a fatty material called plaque has narrowed one or both of your carotid arteries and reduced blood flow to your brain.

.Fig->B………………….
The illustration shows a normal artery with normal blood flow (figure A) and an artery containing plaque buildup ( figure B).

If your carotid arteries are narrowed by plaque, you may be at risk for having a stroke. That risk depends on how much of your artery is blocked and how much blood flow is restricted. To reduce your risk for stroke, your doctor may recommend medical or surgical treatments to reduce or remove the plaque buildup in your carotid arteries.

How long is it before the result of the test is known?
The technician records the test on videotape for review by a radiologist. The radiologist then makes measurements from the video picture and submits a report to your doctor. Your doctor should have the results within a few days.

Key Points to Note:
*Carotid ultrasound is a test that uses high-frequency sound waves to create images of the insides of the two large arteries in your neck. These arteries, called carotid arteries, supply your brain with blood.

*A carotid ultrasound can show whether buildup of a fatty material called plaque has narrowed one or both of your carotid arteries and reduced blood flow to your brain.

*If your carotid arteries are narrowed by plaque, you may be at risk for having a stroke, depending on how much of your artery is blocked and how much blood flow is restricted.

*You may need a carotid ultrasound if you had a stroke or ministroke recently or are at high risk for having a stroke.

*Carotid ultrasound is a painless test done in a doctor’s office or hospital. It usually doesn’t take more than 30 minutes and requires no preparation or followup.

*There are no risks linked to having a carotid ultrasound, because the test uses harmless sound waves.

Resources:
http://www.health.harvard.edu/diagnostic-tests/carotid-ultrasound.htm
http://www.nhlbi.nih.gov/health/dci/Diseases/cu/cu_all.html

Categories
Diagnonistic Test

Upper Endoscopy

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Upper endoscopy enables the physician to look inside the esophagus, stomach, and duodenum (first part of the small intestine). The procedure might be used to discover the reason for swallowing difficulties, nausea, vomiting, reflux, bleeding, indigestion, abdominal pain, or chest pain. Upper endoscopy is also called EGD, which stands for esophagogastroduodenoscopy (eh-SAH-fuh-goh-GAS-troh-doo-AH-duh-NAH-skuh-pee).

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For the procedure you will swallow a thin, flexible, lighted tube called an endoscope (EN-doh-skope). Right before the procedure the physician will spray your throat with a numbing agent that may help prevent gagging. You may also receive pain medicine and a sedative to help you relax during the exam. The endoscope transmits an image of the inside of the esophagus, stomach, and duodenum, so the physician can carefully examine the lining of these organs. The scope also blows air into the stomach; this expands the folds of tissue and makes it easier for the physician to examine the stomach.

The physician can see abnormalities, like inflammation or bleeding, through the endoscope that don’t show up well on x rays. The physician can also insert instruments into the scope to treat bleeding abnormalities or remove samples of tissue (biopsy) for further tests.

Possible complications of upper endoscopy include bleeding and puncture of the stomach lining. However, such complications are rare. Most people will probably have nothing more than a mild sore throat after the procedure.

The procedure takes 20 to 30 minutes. Because you will be sedated, you will need to rest at the endoscopy facility for 1 to 2 hours until the medication wears off.

Preparation
Your stomach and duodenum must be empty for the procedure to be thorough and safe, so you will not be able to eat or drink anything for at least 6 hours beforehand. Also, you must arrange for someone to take you home—you will not be allowed to drive because of the sedatives. Your physician may give you other special instructions.

For More Information
American Gastroenterological Association (AGA)
National Office
4930 Del Ray Avenue
Bethesda, MD 20814
Phone: 301–654–2055
Fax: 301–654–5920
Email: info@gastro.org
Internet: www.gastro.org

National Digestive Diseases Information Clearinghouse
2 Information Way
Bethesda, MD 20892–3570
Phone: 1–800–891–5389
TTY: 1–866–569–1162
Fax: 703–738–4929
Email: nddic@info.niddk.nih.gov
Internet: www.digestive.niddk.nih.gov

The National Digestive Diseases Information Clearinghouse (NDDIC) is a service of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). The NIDDK is part of the National Institutes of Health of the U.S. Department of Health and Human Services. Established in 1980, the Clearinghouse provides information about digestive diseases to people with digestive disorders and to their families, health care professionals, and the public. The NDDIC answers inquiries, develops and distributes publications, and works closely with professional and patient organizations and Government agencies to coordinate resources about digestive diseases.

Sources: http://digestive.niddk.nih.gov/ddiseases/pubs/upperendoscopy/index.htm

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