Larchmont Imaging is proud to be the first and only provider in Burlington County and surrounding communities to offer DIGITAL MAMMOGRAPHY - a woman's newest ally in the fight against breast cancer.

EVLT (Endovenous Laser Therapy)
For The Treatment Of Varicose Veins
by Omar Lalani, M.D.

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At least 25 million Americans suffer from venous disease secondary to superficial venous insufficiency. It is estimated that approximately 25% of women and 15% of men have lower extremity superficial venous insufficiency. This medical problem results in what is seen clinically as varicose veins in the legs. Although often thought of as a strictly cosmetic concern, varicose veins associated with superficial venous insufficiency cause significant clinical problems. The disease is more common in women and in the middle-aged to elderly population. Women frequently develop varicose veins during pregnancy, and it tends to worsen with future pregnancies. Approximately 50% of the population over the age of 50 has some form of this disorder. There is a large genetic component to this disease, and it is common for multiple members of a given family to be affected. Additionally, people with lifestyles or jobs that require them to stand for long periods of time are also at increased risk. Patients usually complain of burning, aching, itching, or throbbing legs. The varicose veins that result are part of a progressive disease, which, if left untreated, can lead to swollen ankles, skin color changes and skin ulcers.

The condition of varicose veins is primarily due to nonfunctioning valves in the superficial veins of the legs, primarily the greater saphenous vein (GSV). This allows blood to pool in the legs rather than returning to the heart. As a result, varicose veins form as large, dilated, often worm-like vessels in the legs. In order to treat this condition, the insufficient vein (the GSV in the majority of cases) needs to be sealed. This disease is diagnosed by the history given by the patient, a physical examination, and a diagnostic ultrasound of the legs. Vein stripping and ligation, a surgical procedure, has been the gold standard for treating this disease. It involves surgically removing the GSV. Although generally effective, the procedure can lead to complications and requires longer recovery time, i.e. 3 days bed rest. Additionally, the operation requires the use of general anesthesia in an operating room.

The new less-invasive, catheter-based treatments for venous disease include endovenous laser therapy, or EVLT. This is an outpatient procedure performed in a radiology suite, usually without any sedation required. A small incision is made at the level of the knee. Through this, a small catheter is placed in the GSV. This is the only incision made for this procedure. Once this is done, local anesthetic is applied in the skin and soft tissues around the GSV from the knee to the groin. At this point, a small laser probe is used to seal off the GSV through thermal effect. The entire procedure usually takes about 45-60 minutes. There is minimal, if any, discomfort during the procedure. Once finished, the leg is wrapped and the patient is instructed to wear compression stockings for several days. The patient is encouraged to ambulate immediately. Mild discomfort and bruising are not uncommon during the first week and can usually be managed with over-the-counter medication. The risks are minimal, especially when compared to the surgical alternative.

This relatively new, minimally-invasive, technique for the treatment of varicose veins has shown great promise. There is greater than 95% success in sealing the GSV. Follow-up examinations have demonstrated significant reductions in the diameter of the GSV after treatment, resulting in marked cosmetic and clinical improvement after the procedure in the vast majority of cases. This procedure is performed at our Mount Laurel facility. Please call 609-261-4500 to schedule an appointment. Health insurance coverage for this procedure varies by insurance carriers and plans.

Click here for more information on this procedure.

Imaging of Acute Stroke
by Sungtae Lim, M.D.

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What is acute stroke? An acute stroke occurs when there is lack of adequate blood flow to parts of the brain. Usually, this is caused by an abrupt blockage of one or more blood vessels that supply blood flow to the brain. As a result, brain tissue dies from lack of oxygen. Depending on what part of the brain is affected, a stroke can permanently cause serious physical and mental disabilities, such as the ability to talk, think, or use parts of the body. A large stroke, or one that affects key areas of the brain can cause permanent unconsciousness, and even death. Atherosclerotic disease accounts for the vast majority of these strokes. Other causes include blood clots that form elsewhere in the body, such as the heart, which flow through blood vessels into the brain. Early recognition of stroke is important because early treatment is essential to minimize the degree of permanent damage to the brain.

How is a stroke diagnosed?

An acute stroke is usually identifiable by symptoms exhibited by the patient and by careful physical examinations performed by a physician. The diagnosis and characterization of acute stroke took a major leap forward with the advent of computerized axial tomography, or CT scan. CT scanning, otherwise known as CAT scan, came into widespread clinical use during the late 1970's and 1980's. CT scans are essentially x-ray images of the body that are acquired in such a fashion so that the area that is scanned is represented as many individual serial slices. This imaging modality, for the first time, allowed doctors to actually see what happens to the brain when an acute stroke occurs. Over the years, as CT scanners have become faster and better, CT scanning has become an integral part in the diagnosis of acute stroke.

The field of diagnostic imaging took another quantum leap when magnetic resonance imaging, or MRI, evolved perhaps a decade after the advent of CT imaging. Unlike CT imaging which uses x-rays, MRI uses strong magnetic fields to generate images of different parts of the body. Both CT and MRI offer different kinds of advantages over the other. MRI, however, has one major advantage over CT scanning in the field of stroke imaging. A CT scan may not demonstrate a stroke until many hours have passed. In fact, it may take up to a full day or more until a stroke becomes evident on a CT scan. With MRI scans, acute strokes are picked up much earlier, usually becoming evident within several hours. When available, MRI scans have significantly helped physicians recognize, characterize, and ultimately treat stroke in the emergent setting.

As powerful a tool MRI scans have become, it took another major leap forward in the 1990's with the advent of diffusion weighted imaging.

What is diffusion weighted imaging?

Diffusion weighted imaging, or DWI, is the newest and most powerful armamentarium in the field of stroke imaging. DWI is a type of MRI scan that became possible when scanners became powerful enough to have echo planar capabilities, a special type of MRI sequence which utilizes very rapid and powerful shifts in magnetic fields. An acute stroke can potentially become evident on a DWI scan within an hour after onset of symptoms. In addition, DWI scans have the ability to distinguish between areas of new stroke within the brain (which may require prompt treatment), from old strokes (which require no treatment). Often on conventional MRI scans without DWI images, new and old strokes can be very difficult to distinguish from each other. Finally, DWI scan can pick up very small strokes which can be missed on conventional MRI scans. Such small strokes may cause minimal symptoms, but they can be harbingers of a very large stroke that can potentially happen in the near future. Thus DWI scan can alert the physician to aggressively search for conditions that can predispose an individual for a major stroke and treat it before the stroke occurs.

Other Advanced Stroke Imaging Techniques

The final category of advanced stroke imaging falls under the heading of “perfusion imaging”. Perfusion imaging can be performed with MRI (MR perfusion), and more recently, CT scans (CT perfusion). The exact methods between MR perfusion and CT perfusion scans differ, but they are both based upon rapid scanning of the brain during the injection of special drugs, or contrast agents, into the veins. As these contrast agents flow through the blood vessels that supply the brain, the MRI or CT scanner rapidly scans the brain, usually over the course of several seconds. Subtle changes occur in the appearance of the brain during this time as the contrast agent passes through. These changes are then analyzed by the computer, and after performing complex mathematical computations, perfusion images are generated. Since perfusion imaging is based upon the passage of the contrast agents through the blood vessels in the brain, any disturbance of the blood vessel will affect the way the perfusion images look. Thus perfusion images can theoretically become abnormal the very instant a stroke occurs, even faster than with DWI scans. Practically speaking, however, it is virtually impossible to scan a patient at the very onset of a stroke. In fact, it is very rare to scan a patient any sooner than perhaps one or two hours after onset of a stroke because of the logistics involved. In many instances, therefore, physicians have little use for perfusion scans in the management of acute strokes. However, in some large university hospitals where acute strokes are managed very aggressively, perfusion imaging may play a significant role. Used in conjunction with DWI scans, perfusion imaging can help delineate areas of the brain that are not getting enough blood flow, but still viable…..that is, brain tissue that is at risk for death, but is still salvageable. Recognizing such salvageable brain tissue may prompt instituting aggressive procedures to try and restore blood flow to that area of the brain, and thus limit the amount of damage. Such procedures are to be carefully considered, as they carry risks of undesirable complications, and because they are useless when brain tissue is already dead.

Magnetic Resonance Imaging of Gynecologic Disease
by Barry Livstone, M.D.

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The diagnosis of gynecologic disease has long been achieved with ultrasound examinations. When a woman first experiences pelvic or genital symptoms, an ultrasound is typically the first imaging test employed, and most women are familiar with this modality. In recent years, Magnetic Resonance Imaging (MRI) has emerged as the most advanced imaging method available to physicians, and has become a powerful adjuvant to ultrasound. MRI provides the greatest detail of the female pelvic anatomy when compared to other imaging modalities. This allows for the improved ability to visualize normal anatomy and detect pathology to its fullest extent. One advantage of MRI over ultrasound includes patient comfort due to the fact that a vaginal probe is not used, and the patient does not need a full bladder. MRI allows for a more specific characterization of findings discovered on the initial ultrasound scan. Imaging is performed in multiple planes, with the potential for intravenous contrast administration, resulting in improved contrast and resolution of different tissues.

MRI scanners use a very strong magnetic field, which is delivered by a large superconducting magnet. It is within the bore of this magnet that the patient is placed. Radio waves are then introduced and echoes of these waves form the images which radiologists interpret. MRI does not use any ionizing radiation and is safe as well as comfortable unless the patient suffers from claustrophobia, in which case a mild sedative may be prescribed. Gadolinium, which is used as an intravenous contrast agent, has long been considered safe, and lacks the risks of allergic reaction associated with the iodine agents used in Computed Tomography (CT) scans. This article will discuss several of the more common conditions for which MRI offers an advantage.

Ultrasound is often performed on women with pelvic pain. Adenomyosis is a condition which is a leading cause of pelvic pain. It is present when endometrial glands extend into the uterine wall, and often escapes detection on ultrasound examination. This diagnosis is, however, easily made with MRI. Fibroids are another common cause of pelvic pain. Although well characterized with ultrasound, MRI is superior for determining the number, size, and location of fibroids, which when in a submucosal location can be of particular clinical concern. It is important to accurately distinguish between adenomyosis and fibroids since the former is typically treated with a hysterectomy while the latter may be treated with a myomectomy (partial resection), medication, or a new technique called catheter embolization which diminishes blood flow to the fibroids and causes them to shrink. It is also extremely helpful in distinguishing a benign exophytic fibroid from a possibly malignant ovarian mass.

A common ultrasound finding is thickening of the endometrium, which in itself is fairly non-specific, though concerning for endometrial carcinoma, particularly in a postmenopausal woman. MRI can more easily distinguish endometrial cancer from an endometrial polyp, adenomyosis, or submucosal fibroids, which would not be easily differentiated by ultrasound since they are only seen as a widened "endometrial stripe".
MRI is the best imaging modality to evaluate ovarian masses. Ultrasound exams often discover ovarian cysts, which are usually benign. When larger than 2.5 centimeters, they require follow up to ensure resolution with subsequent menstrual cycles. Sometimes these cysts appear complex, and then malignancy cannot be ruled out. In such an instance, MRI allows for the detection of internal septations, nodules, papillary projects, and wall thickening and nodularity, all findings suspicious for ovarian malignancy. MRI can also detect pelvic wall implants, enlarged lymph nodes, and pelvic fluid, which can be seen with metastatic disease, if present in an advanced stage. MRI allows for the most accurate staging of cervical, uterine, and ovarian carcinoma, if needed.

One common pelvic mass is the endometrioma, which is a focal mass of endometriosis. Endometriosis is the presence of endometrial glands outside of the uterus, and a common cause of pelvic pain. These lesions are filled with blood products of varying age, and are readily diagnosed as endometriosis with MRI. Another common pelvic mass is the benign dermoid tumor, which contains fat elements, and is also reliably diagnosed with MRI.

MRI can also be used as an adjuvant in the work up of patients with infertility. Up to 25 percent of women with infertility have congenital anomalies resulting in various deformities, including bicornuate and septate uteri, which are difficult to distinguish on ultrasound and more completely visualized with MRI. This is critical, since a septate uterus can be treated with a simple outpatient surgical procedure called hysteroscopic metroplasty, whereas a bicornuate uterus requires a more extensive operation.

Yet another role for MRI is in the diagnosis of urinary bladder abnormalities and specifically the detection of urethral diverticula, which are a common cause of urinary incontinence in women. In the past, the only reliable method to diagnose this condition was the double balloon urethrogram, which is an uncomfortable and invasive test, requiring urethral catheterization. MRI is also being used to successfully diagnose a variety of pelvic floor prolapses, since the images can be obtained so rapidly as to allow imaging of the pelvis under both normal conditions as well as with increased intraabdominal pressure.

These advances have given the radiologist an ability to characterize and more fully evaluate a myriad of gynecologic as well as urinary diseases. Ultrasound remains an appropriate front line imaging modality for the initial work up of pelvic symptoms. However, once an abnormality is found, MRI plays a powerful adjuvant role in the more complete characterization of such findings.

Magnetic Resonance Imaging of the Breast
Bernadette R. Curtis, MD

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Diagnostic imaging as it relates to women's health has been a priority at Larchmont Imaging Associates (LIA) since the group was established over twenty years ago. The arrival of state-of-the-art MRI imaging capability of the breast to LIA is the latest imaging technique to be offered to our patients and their physicians in the diagnosis and treatment of breast disease. Until recently, MRI of the breast had only been available to a select group of patients treated at major academic centers. Now, however, with the publication of specific guidelines by the American College of Radiology governing terminology and the technical parameters of a breast MRI examination, LIA is now pleased to provide this service to our community. Many of you have heard of MRI of the breast through the news media or the Internet. Sound bites like "MRI appears to be more sensitive than mammography in detecting tumors in women" are everywhere but what does that mean to your health? Should you now be getting MRI of the breast instead of mammography? If your doctor recommends an MRI, what should you expect?

First and most importantly, an MRI of the breast does not replace mammography in screening for breast disease. Research studies have shown that the use of screening mammography in the general population reduces death associated with breast cancer by at least 24 percent. The average lifetime risk of an American woman developing breast cancer is one in seven. Recommendations by the American College of Surgeons, the American Cancer Society, and the American College of Radiology are unified in supporting the need for a baseline mammogram for every woman beginning at age 35 and then every one to two years thereafter beginning at age 40. If you have a family history of breast cancer in a first degree relative (i.e., sister or mother), your first mammogram should be about ten years before the age your relative was diagnosed with breast cancer. Risk factors that increase a woman's chance of developing breast cancer include age, family history, use of hormone replacement therapy, radiation exposure, early onset of the menstrual period, and late menopause. Women who carry genetic mutations in BRCA-1 or BRCA-2 genes have a 30X greater risk of developing breast cancer in their lifetime than women without the mutation. Recent clinical research on these women with dense breasts and these genetic mutations suggest that there is a role for both a yearly mammogram and an MRI in screening for breast cancer. Combining mammography with clinical breast examination and MR imaging appears to increase the accurate identification of breast cancer in women at high risk when compared with the ability of each individual test alone. This recommendation, however, does not extend to women with other risk factors or to women with no risk factors.

If you are diagnosed with breast cancer, your breast surgeon or oncologist may request an MRI of the breast. Current accepted indications for MRI of the breast include: Determining the extent of disease in a patient with newly diagnosed breast cancer; after surgery to identify residual tumor; after chemotherapy to determine tumor response to treatment; cancer found in axillary lymph nodes in women with a normal mammogram.

An understanding of the basic technical differences between an MRI of the breast and a mammogram will help explain the complementary role each modality plays in detecting breast cancer. Mammography consists of using of low-strength x-rays to image a woman or man's breast while the breast is compressed. This x-ray produces a picture unique to each patient (like a fingerprint) that reflects overlapping densities in the breast. Skin, fat, muscle, glandular and fibrous tissue, calcium, fluid in cysts, are superimposed to form a black and white picture. The exam takes about ten minutes and costs about $75 - $250. Mammograms detect about 75 - 85% of breast cancers. Cancer in the breast is often detected on a mammogram by the radiologist as a change in density or architecture over time. This requires comparing the current mammogram with previous mammograms. A developing density seen on a mammogram could represent an early localized cancer (ductal carcinoma in-situ) that may not be detected with MRI. Importantly, an MRI of the breast should only be performed after a woman has had a mammogram.

For a magnetic resonance imaging examination of the breast, the patient lies within a magnet while on her stomach with her breasts positioned though a hole in the table and lightly compressed. The examination takes about an hour and costs about $1000 - $2500. Forces from the magnet interact with water and fat molecules in the human body and cause radio waves to be emitted from the body. Antennae or special coils that surround the patient's breast detect these radio waves. A computer program then uses the detected radio waves to generate a highly detailed picture of the breast. The last part of the examination includes injection of a liquid contrast agent that has weak magnetic properties. When viewed with MRI, this contrast agent outlines the blood supply to the breast and is important in detecting abnormal blood vessels that feed a cancer. Unfortunately, common benign lesions may also demonstrate blood flow patterns similar to a cancer. This overlap requires careful correlation of the MRI images with the patient's mammogram(s) and often necessitates further testing that might include an ultrasound or even biopsy of the breast. While an MRI examination with contrast is highly likely to detect a hidden breast cancer (high sensitivity over 90-95%), many benign lesions will appear malignant (low specificity ranging from 37-97%) thus requiring a large number of biopsies for lesions that are benign.

As with any MRI examination, patients are screened carefully to ensure their safety during the study. Pacemakers, metallic foreign bodies near the eye, cerebral aneurysm clips and claustrophobia are among the reasons a patient might be excluded from having an MRI examination. If you and your doctor decide that you should have an MRI of the breast, please call our scheduling office at 1-609-261-4500

Warner, E., Plewes, D., Hill, K., et. al. Surveillance of BRCA1 and BRCA2 Mutation Carriers With Magnetic Resonance Imaging, Ultrasound, Mammography, and Clinical Breast Examination ,JAMA. 2004; 292:1317-1325.

Magnetic Resonance Imaging: High Field vs. Open MRI
by Andrew Zeiberg, M.D.

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Magnetic resonance imaging (MRI) is the most sophisticated imaging technique available today. Unlike standard x-rays or computed tomography (CT), MRI does not utilize x-rays which expose patients to small amounts of ionizing radiation. Instead, MRI uses strong magnetic fields to image the body. The advantages of MRI over other imaging modalities is that it allows pictures to be generated of internal organs, bones, muscles and joints which have more detail and accuracy than images produced by x-rays, computed tomography or ultrasound. Over the last decade, advances in MRI have allowed it to become the most accurate non-invasive imaging test used in radiology.

Traditional MRI scanners use very strong magnetic fields in order to optimize the strength of the signal detected by the scanner which in turn optimizes the image quality. These strong magnetic fields, which are thirty thousand times stronger than the earth's magnetic field, require the patient to be placed in a tunnel within a large super conducting magnet. While most patients have no difficulty having scans performed in this way, some people may feel claustrophobic and be uncomfortable when having such scans. In order to permit almost all patients to have MRI scans, efforts were made to design MR systems that could detect weaker signals and thus operate at lower magnetic field strengths. By using a lower magnetic field strength, the scanner could be designed with an open configuration. This permits patients who are claustrophobic or who are very large in stature to have MRI scans without any problems. The more recently produced open MRI designs allow imaging of many body parts with nearly the image quality that high field scanners produce. In fact, today's open MRI images are often better than those that were produced on high field MRI scanners seven or eight years ago. Acceptable image quality and diagnostic accuracy for open MRI scanners depends on both the body part being imaged and the type of scan that is performed. Below are general guidelines for the pros and cons of open MRI scans for different clinical problems. One important point to consider is that for some patients, open MRI scans may be the only option. In these cases, it is appropriate not to follow these guidelines.

Brain Imaging

Because of the excellent contrast between normal and diseased tissue, MRI has become the definitive test for evaluating the brain for strokes, tumors and infections. Today's open MRI scanners can image the brain with nearly identical image quality as high field MRI scanners. There are still some advantages in using the high field scanners. Newer techniques that produce MR arteriograms, which are pictures of the blood vessels in the brain or neck, generally have better image quality when performed on high field MRI systems.

Musculoskeletal Imaging

Unlike x-rays, which only show injuries to bones, MRI can show injuries to muscles, tendons, ligaments and cartilage. Fractures may not even show up on x-rays, but MRI can detect the most subtle "stress fractures" or "bone bruises." These features have helped MRI to become the definitive test in evaluating the major joints (knees, shoulder, hips, ankles, wrists, feet) and the spine for injuries. Using MRI radiologists can locate and characterize tears of ligaments, tendons and cartilage which can assist orthopedic surgeons in planning their treatment of the patient's injuries. Back pain is one of the most common causes of pain in adults. MRI is considered the best technique for finding herniated discs and other causes of back pain. Modern open MRI scanners generally produce images close to that of high field MRI scanners for this type of imaging. On some very large patients, the open MRI images may be somewhat "grainier" or "nosier," but it is unusual for significant injuries to be undetected on open MRI's.

Abdominal Imaging

Computed tomography and ultrasound are often used as initial tests in evaluating abdominal or pelvic symptoms. Often these tests detect potential abnormalities but are unable to completely characterize them. MRI can often provide more detailed information about abnormalities in the solid abdominal organs and determine if there is an underlying tumor. This can help your doctor determine if surgery or a biopsy is indicated and help in the planning for such procedures. Because MRI is a more sensitive test, often it detects abnormalities even when CT scans or ultrasound scans are "normal." MRI has become the most accurate way of characterizing lesions in the liver, kidneys, pancreas and adrenal glands. Benign (non-cancerous) lesions are very common in these organs and are often detected on CT scans performed for other reasons. These "incidental findings" on CT scans often require your doctor to perform additional tests in order to be sure that you don't have cancer. MRI has been shown to be so accurate in characterizing lesions in these organs that often a biopsy or surgery can be avoided completely when MRI scans show benign findings. Imaging of the abdomen and pelvis require special fast techniques that allow each individual scan to be done while the patient holds their breath. This minimizes motion related artifacts from breathing. Additionally, the fast techniques allow each organ to be scanned several times after an injection of intravenous contrast. Cancerous and non-cancerous tumors enhance differently after such injections of contrast. This difference in enhancement pattern aids radiologists in making the correct diagnosis. Because today's open MRI scanners cannot perform such fast scan techniques, generally the accurate assessment of abdominal masses can only be done on high field MRI scanners.

Vascular Imaging

Magnetic resonance angiography (MRA) uses techniques that image flowing blood and provides detailed pictures of the arteries and veins in the body. This can help diagnose blockages in arteries, aneurysms or vascular malformations. Older techniques required insertion of catheters into these vessels and injection of contrast (x-ray dye). Because of the invasive nature of the older tests, they are usually performed in a hospital. Now, using MRA, these tests can be performed non-invasively in a radiology office. Both open and high field MRI scanners can perform MRA's of the arteries in the neck and brain. Generally, the high field scans of these areas look prettier than the open MRI scans, but any abnormality is apparent on both types of scans. Recently new techniques have been developed to image the large vessels in the abdomen (aorta, renal arteries, iliac arteries) using fast scan techniques after the injection of intravenous contrast. As in other types of abdominal imaging, today's open MRI scanners still are not fast enough to perform this type of imaging.

These recent advances have given the patient options when scheduling MRI tests. Generally patients who know they are claustrophobic or who are very large are best served with an open MRI which can perform most MRI scans nearly as well as a high field system. Patients who don't have these constraints should consider having their test done on a high field scanner which will give slightly better image quality. Additionally, the high field scans generally take half the time to perform as identical open MRI scans. Some tests may only be available on high field MRI scanners, but even claustrophobic patients can often have these tests if given a mild sedative.

Larchmont Imaging Associates is fully accredited in MRI, mammography and ultrasound by the American College of Radiology and provides comprehensive mammography services and breast ultrasound. The physicians in the practice also perform both ultrasound guided and stereotactic breast biopsies at Virtua Memorial Hospital of Burlington County.

Multislice Computed Tomography (CT): An Astounding Technological Evolution
Jay Rosenblatt, MD

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Computed Tomography, more commonly referred to as “CT”, has undergone almost constant change during its relatively short 25 year existence. The improvement in speed, resolution and overall image quality has been striking.

Perhaps the easiest way in which to understand CT as an imaging modality is to begin with an explanation of how x-rays are used to create images. Many individuals have had some form of “regular x-ray study” or plain film by the time they reach adulthood. Essentially, an x-ray beam is aimed at the part of a patient to be imaged. The x-rays pass into the patient in a single direction, interact with the various tissues along the way, and for the most part, exit in a single direction to expose the film. Take an arm or a leg for example. When the x-rays encounter bone, they will be stopped or absorbed and will not make it through to expose the film underneath. A bright or white area will result on the x-ray film. When the x-rays encounter fatty tissue, which is much less dense, they will easily penetrate or pass through and will expose the film underneath. A dark or black area will result on the film. Lastly, soft tissues such as solid organs or muscle will have an effect on the x-ray beam, that is somewhere in between that of bone or fat, and will therefore yield an intermediate shade of gray on the x-ray film. It is in this fashion that x-rays, by providing a composite of varying shades of gray, yield a diagnostic image or picture.

Back to CT…similar physics is employed to create a CT image. That is except for one crucial difference: when obtaining a plain film, the x-rays travel in only one direction, pass through the patient and exit, generally, in a single direction; in CT, x-rays originate sequentially from multiple directions as the x-ray source encircles the patient. After passing through the patient, the x-rays reach a receptor called a detector. This replaces film used in “regular x-ray.” In addition, the patient lying on a table actually moves through the CT unit as an entire segment of the body is imaged (i.e., head, chest or abdomen). It is then, with the use of very sophisticated computers and software, that an accurate representation of human anatomy is reproduced. The same principles apply regarding distinction of various tissues or structures within the body (recall the example above of bone, fatty tissue and solid organs or soft tissue). When the actual images are finally produced, they in fact represent slices of the patient. It is as if you actually “sliced” through the patient and were looking up at the patient’s body from below. The anatomic relationship of structures and organs are easily seen, detail is exquisite and in many cases abnormalities are plainly visible. It is a way to see “inside” the intact body that has revolutionized the diagnostic approach to a sick or injured patient.

Early on, CT scanners were relatively slow. It could take several minutes to acquire a single slice (a head CT for example is around 20 slices). Only one level or slice could be acquired at a time. The scanner would image a given level or slice and then pause as the patient was moved to the next level. Then the next slice could be obtained. A single study could take over an hour. These older single slice or axial CT scanners eventually improved and were eventually able to obtain a single slice in one to two seconds. Subsequently this technology was replaced by single slice helical CT. In a helical CT scanner, the patient moves continuously through the machine as x-rays continuously expose the patient. The “stop and shoot” approach of single slice axial CT had now become obsolete for all but a few applications. An entire region of a patient could be scanned in a matter of seconds. What followed was the development of today’s multislice helical scanners. In these “state of the art” units, there are multiple rows of detectors and a wider x-ray beam. A patient can be imaged even faster and an entire region can be covered in only a few seconds! This feature can be used either to vastly diminish the length of the exam as just mentioned or alternatively to obtain very thin slices for superb detail. In either case, the results are astounding.

This new technology can be used to perform routine exams more effectively. There are also many advanced applications which can now be performed with great ease. Good examples would be CT Angiography (CTA) of the carotid arteries which are in the neck, CTA of the renal arteries which supply the kidneys and CTA of the pulmonary arteries which supply the lungs. The aorta and the arteries to the legs can also be studied. In many cases a patient can avoid a more invasive interventional procedure such as catheter angiography if a CTA can be performed.

Additional potential advanced applications include CTA of the coronary arteries, calcium scoring of the coronary arteries and CT colonoscopy. These studies also can possibly replace or supplement more invasive procedures. Lastly, CT screening, a much debated topic in the imaging literature and the lay press, bears close watching. If ongoing research eventually proves CT to be an appropriate method to screen for certain diseases, this could perhaps be a future application of multislice CT technology as well.

Nuclear Cardiac Stress Testing
by Michael S. Kaufman, M.D.

WHAT IS A NUCLEAR STRESS TEST?

The nuclear stress test is a diagnostic procedure used to evaluate the distribution of blood flow to the heart. This test is also known as myocardial perfusion imaging. The test can be performed in a hospital’s radiology or nuclear medicine department, in a doctor's office, or at an outpatient clinic.

WHY AM I HAVING THIS TEST?

A nuclear stress test is one of several types of cardiac stress tests that a doctor can request. Each is tailored to an individual patient's condition. A nuclear stress test is indicated for individuals with unexplained chest pain (angina) or chest pain brought on by exercise. It is used to determine if the pain is due to a partial blockage of one or more arteries of the heart. This type of heart disease is called ischemic heart disease.

For individuals with possible or known coronary artery disease, the test can help determine whether the disease should be treated with medication, angioplasty or bypass surgery. For patients with a previous heart attack or myocardial infarction, the test can evaluate the location and amount of permanent injury to the heart. For individuals who have had prior angioplasty, bypass surgery or other revascularization procedures to restore the blood supply to the heart, the test can characterize the results of these treatments.

Some other reasons a physician may request a nuclear stress test include:
• You are getting short of breath during ordinary activity
• You are taking heart medicines and the doctor wants to assess how well they are working
• You are having skipped beats or palpitations (arrhythmias)
• The doctor has noted a change in your electrocardiogram (EKG)
• You are scheduled for surgery
• You are being tested for exercise tolerance

The principle behind the test is to increase the blood flow to the heart muscle through exercise, thereby putting stress on the heart, and then to take pictures of the heart and its blood flow. Myocardial perfusion imaging enables the assessment of heart chamber size, heart muscle thickness, and blood-flow patterns to the heart walls. With an advanced technique called “gating”, heart wall movement and overall cardiac function can be determined. With gating, the heart images are synchronized to the EKG. This provides additional information on how well the heart muscle is moving as it pumps blood.

WHAT WILL HAPPEN DURING THE TEST?

In a typical nuclear stress test, two sets of images will be taken: the first at rest and the second following stress. Hence, this technique is sometimes called the “Rest/Stress” method. As there are many effective variations of a nuclear stress test, the doctor will select the best choice for each patient.

In the first step of a Rest/Stress protocol, an intravenous tube (IV) is placed in the arm for injection of a small amount of radioactive tracer. Radiotracers are either Technetium-99m based, such as sestamibi (Cardiolite) or tetrofosmin (Myoview), or Thallium-201. After the tracer has circulated through the bloodstream, the patient lies flat on his or her back on a table and the gamma camera moves slowly and automatically in an arc over the front of the chest. Typically, the left arm is positioned above the head, so that it doesn’t get between the camera and the heart. These “resting” images are acquired in less than 20 minutes.

For the “gated stress” portion of the test, electrodes are placed on the chest so that an EKG can monitor the heart rhythm during exercise. Walking on a treadmill is the typical exercise, though in some instances an exercise bicycle may be used. As exercise continues, the speed and incline of the treadmill are gradually increased, so that the exercise becomes more and more difficult. During exercise, the physician looks for changes in the EKG pattern and any symptoms that the patient may experience. Exercise is stopped if the patient becomes fatigued, has symptoms such as chest pain or shortness of breath, or when the doctor feels that the patient has achieved an acceptable level of exercise.

When the patient can exercise no longer, a second dose of radiotracer is injected through the IV. The patient has time to rest before being positioned under the gamma camera for the “gated stress” images of the heart. These images are compared to the resting images to evaluate how coronary blood flow has changed during exercise.

WHAT IF I CAN'T WALK ON THE TREADMILL?

While many people can walk on the treadmill even if they feel they are in poor condition, some people cannot walk for enough time to generate sufficient stress on the heart. Others cannot walk for physical reasons - such as people who have had a stroke, have severe respiratory problems, or have leg problems. For people who cannot walk on a treadmill, a "pharmacologic” stress test is performed.

In a pharmacologic test, instead of the exercise phase described above, the patient receives medicine through the IV line to increase the blood flow to the heart. This medicine may be dipyridamole (Persantine), adenosine or dobutamine. Dipyridamole and adenosine expand the coronary arteries, increasing the blood flow to the heart muscle. Dobutamine makes the heart beat faster and stronger. These effects are similar to what happens to the heart during vigorous exercise. A second set of images will be obtained following the pharmacologic stress test, as previously described.

TEST PREPARATION

Preparation for a nuclear stress test depends on several factors, including age, fitness level and pre-existing medical problems.

The patient may be asked to:
• Not eat anything three to four hours before the test is performed because eating causes increased blood flow to the stomach and intestines. Also, some people may get an upset stomach if they exercise too soon after eating.
• Not smoke at least four hours prior to the test.
• Wear comfortable clothing (shorts or pants with shirt or blouse) and walking or athletic shoes.
• Bring a detailed list of current medications.

Some patients will need to discuss additional factors with their doctor:
• If you are diabetic, ask how to adjust insulin and food intake prior to the test.
• If you regularly take heart or blood pressure medicine, ask whether they should be taken prior to the test.
• If you are taking a Beta-blocker, ask whether this can be stopped 72 hours before the test, as this is often recommended for best results.

If the patient is having a dipyridamole (Persantine) or adenosine stress test:
• Caffeine products and medication containing Theophylline must be avoided 48 hours prior to the test.
• Advise your doctor if you are allergic to Theophylline or Persantine.
• Advise your doctor if you have asthma, chronic lung disease or any heart conditions.

WHAT ARE THE RISKS AND BENEFITS?

RISKS

A nuclear stress test may cause some discomfort from the intravenous injection of the radiopharmaceutical. Allergic reactions to radiopharmaceuticals are extremely rare.

The use of a radioactive substance will expose the body to a small amount of radiation. However, the amount of radioactivity administered is the smallest possible to provide adequate images. Nuclear medicine procedures have been performed for more than three decades, and no long-term adverse effects have been reported from such low-dose studies.

For a patient with coronary artery disease, a nuclear stress test may cause chest pain, or angina, when stress by exercise or medication is applied to your heart. However, the test will be carried out under the supervision of a specialist trained to monitor you and your heart by using information being provided by the electrocardiogram, by your heart rhythm, and by your blood pressure. If necessary, medication can be given for chest pain.

During pharmacologic stress tests, temporary side effects of dipyridamole or adenosine may include headache, flushing, dizziness, nausea, or chest discomfort. If the side effects are severe, the medication can be stopped or other drugs can be given to reverse the effects.

BENEFITS

A nuclear stress test is a safe, non-invasive way to study disturbances in cardiac blood flow, which may be the cause of chest pain, shortness of breath or fatigue.

Computer generated images allow accurate measurement of cardiac function and of the amount of heart muscle not receiving adequate blood flow.

Because the procedure is performed according to standardized protocols, making the information easy to understand or to transfer to all doctors who may be involved in your care.

Most patients can resume regular activities immediately after the procedure. No special precautions are needed after the test. The radioactivity decreases naturally due to the process of radioactive decay and passes out of the body in
urine and stool, typically within 24 hours.

Myocardial perfusion imaging assesses blood flow to the heart and also how well the heart is beating. By comparing the blood flow to the heart muscle during the stress portion of the test to the blood flow while the heart is at rest, blood flow problems are identified, including the size of the affected area and the severity of the problem.

Early detection of coronary artery disease is essential, as it allows therapeutic intervention before permanent damage (myocardial infarction) occurs.

Nuclear Medicine
by William A. Morgan, M.D.

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Nuclear Medicine is generally considered a subspecialty of Radiology. Scans are ordered by your doctor but interpreted by a Radiologist or Nuclear Physician. These studies assist in the diagnosis of disease, as well as aid in the planning of medical and surgical therapies. Nuclear Medicine is occasionally used in surgical procedures and some medical therapies. The technique of acquiring these studies greatly differs from the general radiology and CT scan. Instead of an external x-ray passing through the patient’s body to a film or detecting device, a very small amount of a radioactive pharmaceutical [RADIOTRACER] is administered into the patient. Radiotracers are radioactive compounds chemically designed to accumulate in a particular region called the target organ. The mechanism of localization of radiotracers within the target organ or system depends upon the route of administration (e.g. intravenous, ingested or inhaled) and the properties of the radiotracer such as size, charge and chemical composition. This is greatly influenced by circulation as well as other physiologic parameters. The radioactive element bound to the radiotracer is produced in either a nuclear reactor or a cyclotron. The amount of radiation is often less than many General Radiology procedures and is considered not harmful. Each type of study will require a radiotracer specifically designed for localizing in a target organ allowing an appropriate time interval (which varies for each type of study) for this to occur is sometimes critical. A specialized detector commonly referred to as a nuclear or gamma camera is placed over the area of interest. This camera is very sensitive, detecting the minute amounts of radiotracer within the target organ resulting in a functional image as well as defining anatomy.

Probably the most common study utilized is the bone scan. This scan can evaluate the skeletal system to determine the presence of fractures, infection, and tumor as well as evaluate pain and arthritis. Changes in bone are detected much earlier than plain radiographs (x-rays) which are often used in the evaluation for comparison. These studies can also determine if a compression fracture of the spine (a complication of osteoporosis) is recent or old. Also, 3-D imaging, or SPECT allows more precise localization of many abnormalities.

Cine is a term used when multiple images obtained in a computer over time are displayed in a motion picture. This is especially useful in evaluating the kidneys. Renal scans utilize a radiotracer which is concentrated then eliminated by the kidneys, allowing renal function visualization and computer quantification of renal function. This is used to investigate renal insufficiency or search for obstruction of the collecting system or renal artery stenosi