A doctor can take a medical history, perform a physical exam, and order lab work, but sometimes even more information is needed to make an accurate diagnosis, develop the best treatment plan, or monitor a treatment’s progress. A broad spectrum of sophisticated imaging technologies are available today that can provide invaluable data to the treating physician: X-ray, computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, and nuclear medicine each offer unique views of the human body.

Doctors who specialize in this area of medicine are radiologists. After they receive their medical degrees, these physicians complete several years of specialized training as residents in such areas as diagnostic radiology, nuclear medicine, or radiation oncology; most will become board certified. There are other subspecialty programs and fellowships radiologists can pursue in such areas as interventional radiology, neuroradiology, and pediatric radiology.

Radiology is a rapidly growing, technologically dynamic specialty that intersects with virtually every other area of medicine. Academic medical centers, such as University Hospital, often have access to some of the gold standards in radiological equipment. The University Heights Advanced Imaging Center, located on University Hospital’s campus, has a sophisticated PET/CT unit and a powerful MRI scanner. The Center also has the expert radiologists and skilled technicians to use these tools and interpret the findings. Below, some of these radiologists explain the “basics” of their field and share many of the new developments in their specialty. Dr. Stephen Baker, professor and chair of radiology at New Jersey Medical School, also addresses the ethical question: Are these technologies being overused?

	Chest x-rays, which are among the most common imaging tests, can reveal abnormalities of the lungs (such as pneumonia, tumor or fluid), heart (such as congestive heart failure or enlarged heart), and rib cage (such as broken or abnormal bones).

X-rays: For more than 100 years, the X-ray has been the “backbone” of radiology. Beams of low-dose radiation are emitted from the X-ray machine and absorbed by the specified parts of the body prior to passing through the body and striking a radiation detector. Nearly half of all diagnostic radiographs are chest X-rays, which are taken routinely before surgery to secure images of the patient’s lungs and heart. Bones are well identified using plain X-ray because they absorb more radiation than soft tissue, causing them to appear brighter on film. With contrast materials (dyes), radiographs can be used to take images of soft tissue and blood vessels.

X-rays expose the patient to radiation, albeit in low doses. Technological advances enable X-rays to be more precisely delivered to specific parts of the body, and researchers are investigating new ways to minimize a patient’s exposure to radiation. For example, a new digital X-ray system can take a full body scan in seconds and expose the patient to 75 percent less radiation than a conventional full body X-ray series. While that might sound good, says Dr. Baker, a full body scan isn’t often necessary. “Why not focus on the area of the body that needs imaging? Even though such a system might use less radiation, it still could unnecessarily expose parts of the body to radiation,” he notes.

Developed in the early to mid 1970s, CT scanning is fast, patient-friendly and has the unique ability to image a combination of soft tissue, bone, and blood vessels(top). CT scan showing small olfactory groove meningioma (above).

Computed Tomography: Computed axial tomography, commonly referred to as CT or CAT scanning, combines X-ray and computer technology to produce thin “slice” images of the body. With CT, the patient lays on a table, which is moved through a doughnut-shaped scanning system. The X-ray tube revolves around the patient, sending image information to the computer. One advantage of CT scanning is that it can differentiate between soft tissue structures; contrast material can be used to enhance the images.

CT scanning is commonly used to image the head and the abdominal region. As the technology has become more sophisticated, its applications have expanded. One specialized test performed at University Hospital, CT angiography, visualizes blood vessels and blood flow. It is less invasive than traditional angiography, which involves placement of a catheter. To Dr. Kyunghee Cho, professor of radiology at New Jersey Medical School and chief of the abdominal imaging section, the advantages of CT angiography are crystal clear. “CT angiography is fast, the resolution is incredibly good, and we’re able to perform 3-D reconstruction at a work station,” she says. CT angiography can determine the presence of an aortic aneurysm or a pulmonary embolism and be used for a variety of studies. But Dr. Cho says the technology’s capabilities only are beginning to be realized. “In delivery of chemotherapy infusion therapy for liver cancer, for example, it’s crucial to know the anatomy of many tiny blood vessels,” she notes. “CT angiography provides that information in a less invasive way than catheter angiography. With its ability to create intricate 3-D images, CT angiography will increasingly have a significant role as a guide for interventional techniques where precise delivery of a medication is needed.”

Another application of computed tomography, says Dr. Cho, is CT colonography (CTC), also known as virtual colonoscopy, a screening test for polyps and other abnormalities within the colon and the rectum. Standard colonoscopy involves a physician guiding an endoscopy tube through the colon, which often requires that the patient be given sedation. “People who would otherwise avoid a standard colonoscopy are more willing to have CTC,” says Dr. Cho. If a polyp is found by CTC, the patient has to undergo standard colonoscopy to remove it, but all things considered, the use of CTC avoids many unnecessary standard colonoscopies. Much of the scientific data show that CTC is accurate and effective, in some cases picking up polyps that were missed during standard colonoscopy. CTC has also detected other significant lesions such as kidney tumors. Dr. Cho is co-investigator of a large, multi-institutional study at University Hospital that compares standard colonoscopy, CTC, and barium enema, a third type of screening procedure for colon cancer.

While CT has certainly proved its usefulness, some in the medical community believe it is used too often on children. The reasons for concern are many: CTs emit more radiation than plain X-ray; research indicates that damage from radiation, namely cancer, occurs from lower doses than had been thought; and children, with their developing bodies, are more sensitive to radiation than adults. “It’s caused us to rethink whether a CT scan is necessary for every child who comes to the ER with a bump on the head, and the answer is no. Sometimes an ultrasound will be appropriate; in selected instances, a CT is needed; and for other children, no radiological testing is necessary,” says Dr. Baker.

	Polestar MRI allows for real-time visualization during all stages of brain surgery: pre-, intra- and post-operative image guidance. This enables the neurosurgeon to plan the extent and path of the surgical procedure at every stage (top). Preoperative image is taken in the operating room (above).

MRI: Unlike X-rays, which use radiation to produce images of the body, the forces behind MRI are a strong magnetic field and radio waves. MRI is especially useful in producing detailed, 3-D images of the heart, the brain, and other internal organs, as well as soft tissue around bones.

MRI has some very specialized and sophisticated applications. MRI angiography can be used to view blood vessels without the need for contrast dye. Functional MRI maps the areas of the brain that control speech and other eloquent functions. And with intraoperative MRI, the imaging unit is located physically in the operating room, enabling neurosurgeons to have real-time visualization of the brain during surgery.

As part of an exciting and innovative clinical study at New Jersey Medical School, researchers are using a powerful 3-Tesla (3T) MRI scanner to detect and monitor brain lesions in multiple sclerosis (MS) patients. Tesla is the measure of power of an MRI scanner, and most hospitals have equipment with a 2-Tesla (2T) strength or less. The University Heights Advanced Imaging Center is one of only seven centers in the country with a 3T MRI. What difference does that make? To the MS researchers, a dramatic one. The 3T MRI provides improved demonstration of the small brain lesions that are commonly seen in MS patients, better information than was available with a less-powerful MRI.

The MRI has a reputation for being noisy and uncomfortable for people who don’t like being in close spaces, but “open” MRI and mild sedatives for those patients can offset those problems. However, because of the magnet, people with pacemakers or any other type of non-removable electronic or metallic devices cannot undergo MRI testing.

A patient undergoes an abdominal nuclear medicine study(top). A nuclear scan of a healthy thyroid (middle). A nuclear scan of a nodular thyroid (bottom).

Nuclear Medicine: The emergence of nuclear medicine in the 1970s opened a new window for radiologists. “While earlier technologies enabled us to view the anatomy of the human body, for the first time, nuclear medicine provided a way to examine its physiological processes at the molecular level,” says Dr. Baker.

A patient undergoing a nuclear medicine procedure receives a small amount of a radioactive material either by IV, swallowing capsules or a liquid, or inhalation. The radioactive material, called a radiopharmaceutical, is targeted to the specific area to be studied; the gamma rays it gives off provide images that can be reviewed using a special camera. Single Photon Emission Computed Tomography (SPECT) is a type of nuclear medicine imaging method that provides cross-sectional information about the distribution of the radiopharmaceutical. SPECT is an integral part of modern cardiac and brain imaging and has other applications, especially in oncology. Positron Emission Tomography, another nuclear medicine procedure, is discussed in the PET/CT section below.

Currently, nuclear medicine is well-established as a diagnostic modality, especially in cardiac, endocrinologic, oncologic, renal, and orthopaedic applications, and has a unique role in treatment of thyroid diseases. The future of this technology encompasses more therapeutic procedures, such as treatment of painful bone metastases and certain cancers, such as lymphomas.

	The Discovery™ LS PET scanner(top). A PET scan of a 63 year old woman pinpoints a tumor in her lung (above).

Positron Emission Tomography/Computed Tomography (PET/CT): By themselves, PET scans and CT scans provide important molecular and structural information; together, these technologies have taken radiology to a new level. PET uses glucose modified with a radioactive tracer (F-18) to identify unusual molecular activity. Cancer cells, for example, metabolize glucose more avidly than normal cells. As the tracer decays, positrons (positively charged electrons) are emitted and in turn combine with negatively charged electrons to produce a pair of oppositely directed photons. These are recorded by a scanner and then re-created into a 3-D image by a computer. CT scanning provides detailed anatomical information through a combination of X-ray and computer technology.

Although radiologists can combine images obtained from separate PET and CT machines, it’s virtually impossible to line them up exactly. “It’s extremely difficult to cross reference one image with the other,” says Dr. Lionel Zuckier, director of nuclear medicine at New Jersey Medical School. “With PET/CT, the images are intrinsically lined up. There’s no judging or eyeballing.” This information enables radiologists not only to determine that a tumor exists, but also its precise location and size and how far it has spread; PET/CT can also indicate how well treatment has worked.

Ultrasound (US) imaging, also called ultrasound scanning or sonography, is a method of obtaining images of internal organs by sending high-frequency sound waves into the body.

While PET/CT has applications in cardiac and brain imaging, at present it is most commonly used with oncology patients. But that might change as new radioactive tracers are developed and approved by the FDA. “The applications for PET/CT will dramatically increase once other radiopharmaceuticals are approved,” believes Dr. Zuckier.

Ultrasound: The late 1970s brought about another technological innovation in radiology: the use of sound waves to create images. As the high-frequency sound waves are passed through the body, the “echoes” are recorded in real time and displayed on a monitor.

Ultrasound, or sonography, is performed without using radiation, an important consideration in one of its well-known and common applications, imaging of the womb and the developing fetus. But ultrasound’s usefulness extends well beyond obstetrics. Ultrasound is used for blood flow studies and to evaluate damage to the heart after a heart attack; it also is used as a guide during certain procedures, such as biopsies. While ultrasound is excellent at imaging soft tissue and organs, the sound waves do not penetrate bone very well.

	This is a CT Angiogram of a 78 year old woman. The green arrow demonstrates a blocked cerebral artery at the base of the brain (top). The same patient after intra-arterial stroke therapy. Notice how the vessel flow has been restored to normal. This patient recovered completely and no stroke was seen on the CT scans even days later (above).

Interventional Radiology/Interventional Neuroradiology: One of the most important developments in radiology has been the emergence of two subspecialty fields: interventional radiology and interventional neuroradiology. In both, the radiologist’s role changes from a physician who helps diagnose a condition to one who treats it. Some of the conditions that interventional practitioners treat are traditionally done by surgeons: uterine fibroids and abdominal aortic aneurysms. Uterine fibroid embolization (UFE), for example, is a non-surgical, uterus-preserving treatment that blocks the blood supply to fibroids, causing them to shrink. During UFE, a catheter is inserted in the woman’s groin and threaded through her femoral artery and to her uterine artery. Once the catheter is in place, the interventional radiologist releases tiny, polyvinyl alcohol particles to the vessels leading to the fibroid. The particles cut off the blood supply to the fibroids. UFE is relatively new, and University Hospital is one of the few hospitals in northern New Jersey to offer the procedure.

Interventional neuroradiologists perform minimally invasive therapeutic procedures to evaluate and treat such conditions as stroke, cerebral aneurysms; arteriovenous malformations; tumors of the brain, head, neck and spinal cord; cavernous-carotid fistulas; and dural a-v fistulas. In the case of acute ischemic stroke, an interventional neuroradiologist can deliver a clot-busting drug, tPA, directly to the blood clot in the brain. By quickly dissolving the clot and restoring the blood flow and oxygen supply to the brain, this technique can minimize the effects of stroke and even save lives. University Hospital is one of less than 150 hospitals in the nation offering this procedure and the specialized CT scans that go along with it.

Too Much of a Good Thing?

The advancements in radiology come with some caveats. “Imaging is growing even faster than pharmaceuticals, and the reliance on expensive, sophisticated technology is a uniquely American phenomenon,” says Dr. Baker. “However, imaging should not be a substitute for a physician taking a medical history or performing a physical examination.”

Some tests can be expensive, fruitless searches on the “worried well,” believes Dr. Baker. An example, he says, is the full body scan CT screening. In theory, the full body scan sounds quite impressive: In only a few pain-free minutes, a person can learn the intricacies of his or her body, conceivably identifying cancer, cardiac problems, or other abnormalities in the earliest, easiest-to-treat stages. Except that the promise doesn’t really mesh with reality, says Dr. Baker. CT can find tiny nodules in the lungs, but determining whether they are cancer or the aftermath of tuberculosis has to be done by a second, invasive test. Ultrasound can detect an aortic aneurysm comparably to the CT scan, but without radiation and at a lesser cost. And as far as cancer goes, only one type, renal cancer, can be detected by the CT full body scan in the absence of signs and symptoms indicative of that cancer (in part, because this test does not use contrast dye). In almost every other type of cancer, either recognition does not prolong survival or the identification comes by another means. And yet even with renal cancer, the chances of detecting a malignancy are about 1 in 20,000. “The public has started to figure out these full body scans don’t measure up to the hype, and many of the centers that offer them are going out of business,” says Dr. Baker.

Dr. Baker acknowledges that, as a radiologist and chair of a medical school radiology department, his stance against overutilization of radiological technology might seem confusing or even contradictory. “I’m excited about the many wonderful advancements in radiology, and there are more to come,” he says. “But they need to be used wisely, with the physician computing the cost of the study and considering the impact of dose accumulation over the patient’s lifespan.”

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