Positron Emission Tomography --

PET Scans Advance Diagnostic Testing

By Andrew Gorosko

Danbury Hospital is among several area hospitals that are now using an advanced form of imaging technology –– combining nuclear medicine, biochemistry, and radiology –– to help diagnose and plan treatments for patients with cancerous tumors, heart irregularities, and neurological disorders.

Donald H. Hulnick, MD, a radiologist who uses Positron Emission Tomography (PET) scanning in his work at Danbury Hospital, said PET scanning is a safe and painless process that takes about one hour.

PET scanning spots medical problems sooner than they would otherwise be noticed. These conditions include the presence and growth of benign and malignant pulmonary nodules; the extent of lung cancer; the extent, location, and activity level of lymphoma; the extent and recurrence of colorectal cancer; the extent, recurrence, and response to treatment of breast cancer; the extent and recurrence of skin cancer, plus the extent and recurrence of head and neck cancers.

PET scanning also is useful in assessing the condition of the heart muscle, analyzing brain seizures, and probing dementia, Dr Hulnick said. Doctors hope PET scanning becomes a valuable tool for evaluating Alzheimer’s disease, he added.

Unlike Computed Tomography (CT) scanners and Magnetic Resonance Imaging (MRI) scanners, both of which provide anatomical information, PET scanning identifies chemical changes that are occurring within the body.

“We’re looking at [metabolic] functioning. We’re looking at [cellular] activity,” Dr Hulnick said.

Before receiving a PET scan, patients are injected with pharmaceutical-grade glucose, to which short-lived radioisotopes known as “positrons” have been added. The injection, which serves as a “tracer,” allows doctors to monitor the metabolic activity of abnormal cells within the body. The tracer becomes concentrated in cancer cells and in other bodily areas with abnormalities.

The PET scanner measures the biochemical activity of injected positrons, which are positively-charged electrons, in recording the varying metabolic rates among tissues within the body.

PET scanning analyzes metabolic processes from three physical planes, providing frontal views, side views, and cross-sectional views of the body, explained Dr Hulnick.

The multiple interior images allow doctors to view biochemical activity three-dimensionally, letting them precisely gauge the location and extent of medical problems, he said.

A PET scanner is an electronic device, which has a circular opening, through which a patient is moved when the scanner’s sensors are running.

A portable PET scanner is parked at Danbury Hospital on Tuesdays. The device is transported by truck among six Fairfield County hospitals each week.

In the nine months that the PET scanner has been in use at Danbury Hospital, it has scanned about 360 patients there, Dr Hulnick said.

Besides Dr Hulnick, other Danbury Hospital doctors working with PET scanning are Bradford Bottger, MD; William Johns, MD; and Shiv Gupta, MD.

After conducting PET scans on patients, doctors analyze the collected electronic data on computer monitors.

Displayed are finely detailed monochromatic images, with metabolic differences depicted via an extended range of gray tones. The detailed information on metabolic functioning helps doctors pinpoint the nature and extent of medical problems.

The physiological information provided by PET scanning, when augmented with the anatomical information provided by other forms of scanning, aids doctors in determining the best course of treatment for patients, Dr Hulnick said.  

PET scanning has already proved its value, but the technology is still in its infancy, Dr Hulnick said.

Before last September, patients seeking PET scans had to travel to other hospitals, according to Thorsten Krebs, MD, chairman of Danbury Hospital’s radiology department. “They [patients] like the accessibility and convenience of having it right here in Danbury now,” he said.

Other Hospitals

New Milford Hospital also has the shared use of a mobile PET scanner.

“This technology provides physicians with unique diagnostic information and a better chance of detecting cancers, and heart [diseases] and neurology diseases for patients in early [disease] stages, when treatments are simpler, more effective, and in many cases, less expensive,” according to Mark Glicklich, MD, who is New Milford Hospital’s clinical director of radiology.

According to Alan Kaye, MD, the chairman of the radiology department at Bridgeport Hospital, “Clinical trials have shown the effectiveness of PET scans, helping to move them from the research environment to mainstream clinical practice. PET scans are becoming essential to physicians in making decisions regarding patient care.” Bridgeport Hospital shares a mobile PET scanner with other hospitals.

St Vincent’s Medical Center in Bridgeport also has the use of a shared PET scanner.

Robert Russo, MD, chairman of St Vincent’s radiology department, said, “PET is the first tool we’ve had to look at cancer with one body image. We can see results without multiple tests. It allows us to do an entire body exam.”