The many uses of PET

Primarily known to help in cancer diagnoses, the Positron Emission Tomography (PET) Center of St. Luke’s Medical Center can also detect the early onset of Alzheimer’s Disease and the hardly heard Lubag (a rare disease affecting males with maternal roots from Panay Island). Both are neurological or brain illnesses with no known cure at present.

"PET scans are not yet widely used in the diagnosis of Alzheimer’s Disease since at the moment there is no effective cure for it; the available medicines serve just to delay its onset or lessen the symptoms," says Dr. Jonas Santiago, the center’s head.

With a PET scan, the parts of the brain affected by the disease are either seen as areas where a radioactive tracer accumulates or areas where a radioactive tracer does not go to.

The same thing is true with Lubag. Affecting males while in their productive years like those in their 20s, 30s and 40s, Lubag (or X-linked Dystonia-Parkinsonism) is a debilitating illness that can be found in males.

The disease is characterized by involuntary movements which may become severe enough to impair daily activities.

Introduced by the St. Luke’s Medical Center in the country three years ago, the PET scanning technology has helped over a thousand patients and the medical community in the precise diagnoses of the spread of various forms of cancer and as a result, guides the right combination of management for these diseases.

The fully equipped center is the only one of its kind in the Philippines today and among the few in the world with a Cyclotron (a machine that prepares the radioactive tracers used in the procedure). The only Asian countries that operate similar centers are China, Hong Kong, Japan, Singapore and South Korea.

What exactly is PET and how is it different from the conventional scans most Filipinos are familiar with?

Classified under nuclear medicine, PET is a non-invasive imaging technique that shows the metabolism or function of the different organs and tissues of the body.

It uses small amounts of radiopharmaceuticals for tracing bodily processes and measuring cellular and tissue changes. These are given to the patient one hour before the actual procedure.

Compared to Magnetic Resonance Imaging (MRI) and Computerized Tomography (CT) that only give images of organ anatomy and structures, PET provides direct measure of biochemistry and functional activity which enables diagnosis of the diseases.

The PET Center is manned by physicists and chemists who had their training with the renowned Memorial Sloan-Kettering Cancer Center.

"When they go and see us at the center, referred by their oncologists or surgeons, people have more or less already undergone either a CT scan or MRI. With the PET scan, since it is a whole-body scan, the extent of the cancer is clearly seen (whether it has metastasized or not) and the physician can recommend the proper management," says Santiago.

"As with the case of lymphoma or cancer of the glands, some histologic types of this cancer are highly responsive to treatment and proper chemotherapy can be given based on how extensive the disease is."

A PET scan is also good in following up cases of cancer management. If the disease goes into remission, it will be for the patient’s peace of mind to know that the cancer has responded to treatment and for him to go on with life with renewed hope.

Santiago is a nuclear medicine specialist with certifications from the American Board of Nuclear Medicine, Board of Nuclear Cardiology and Philippine Specialty Board of Nuclear Medicine. He had his fellowship at St. Vincents Hospital and Memorial Sloan Kettering Cancer Center, New York.

For more information, contact the PET Center of St. Luke’s Medical Center at 726-8369 or 723-0101 local 4157 or 4158.