Healthy Perspectives

Technologies for Looking
Inside the Human Body

JOHN MUIT/MT. DIABLO HEALTH SYSTEM

Today's advanced imaging technologies make accurate diagnosis of internal problems much easier for patients. Using Ultrasound (US) Magnetic Resonance Imaging (MRI, or Computed Tomography (CT), the body's inner workings are revealed in amazing detail.

"Each technology has applications for which its use is best suited," explains radiologist Robert M Schick, M.D., who is on staff at Mt. Diablo and John Muir Medical Centers.

"Ultrasound (US) is excellent for revealing the solid organs of the upper abdomen, gallbladder, and the female pelvis, for e,0mple During pregnancy, it can monitor fetal growth and development."

Other uses for US are evaluating leg veins for clots, studying carotid arteries in the neck for possible blockages, and for imaging the scrotum and thyroid glands. It also supplements mammography to clarify findings.

HOW DOES ULTRASOUND WORK?

The patient lies in a darkened room on a soft examining table while a smooth plastic transducer glides painlessly over the skin. Sound waves with frequency above the audible range create images. The echoes of the sound waves are recorded and analyzed by a computer, resulting in a display of internal anatomy. There are no harmful effects from the ultrasound exam.

MAGNETIC RESONANCE

Magnetic Resonance is the most sensitive imaging test for evaluating the brain, spine and joints. It can also create images of blood vessels and reveal areas of narrowing.

"There is no X-ray exposure or other known harmful effect from MRI," says Dr. Schick. "We sometimes inject a contrast agent to enhance the images and provide important diagnostic information."

HOW ARE MRI SCANS CONDUCTED?

The conventional MRI is designed as a tunnel surrounded by windings of the magnet. In the newer, open design, the magnet does not completely surround the patient. The patient lies completely still during scans on a padded table within a magnetic field. Radio waves are broadcast and then a receiver analyzes the edloes to reconstruct an internal image. The MRI machine is noisy, as electrical switches open and close at high speed to regulate the circuitry. There is no contact with the patient or any perception of the changing magnetic fields. Exams usually take between 20 and 40 minutes.

"Some patients are not candidates for MRI," Dr. Schick adds, "Those with pacemakers or prior intracranial aneurysm surgery may be ruled out."

WHAT IS COMPUTED TOMOGRAPHY?

Computed Tomography, often referred to as a CAT scan, examines the body using a thin T-ray beam. A ring of X-ray ~tors measures the transmitted energy and supplies this data to a computer, which creates an image of the internal body structure. Contrast agents are sometimes given either intravenously or orally to improve image detail.

The patient lies on a padded table that moves through a doughout-shaped ring that houses the X-ray tube and detectors. The exam is very quiet and lasts between 20 and 40 minutes, on average.

HOW IS CT BEST USED?

CT provides excellent visualization of detail in the chest, abdomen and pelvis. It often clarifies findings on US screenings or chest X-rays. A specialized (helical) technique improves the accuracy of imaging the lungs and liver. It can also detect acute pulmonary embolism (a clot in the lungs). Highly effective for studies of the urinary tract, CT can detect stones in the kidneys and ureters. Even sources of abdominal pain, including diverticulitis and acute appendicitis, are found.

"These rather miraculous imaging technologies allow us to provide the patient's physician with highly accurate and often life-saving information," Dr. Schick concludes.