PET Tracer Imaging Changes Brain Tumor Management Plans

Imaging amino acid transporters used with positron emission tomography/computed tomography (PET/CT) have been shown to change significantly the intended management plans for patients with brain tumors, according to new findings. As a result of imaging with the radiopharmaceutical 3,4-dihydroxy-6-F-18-fluoro-l-phenylalanine (F-18-DOPA), physicians altered the intended management plan for 41% of patients with brain tumors.

Contrast-enhanced magnetic resonance imaging (MRI) is most frequently used to diagnose and monitor patients with brain tumors. After initial treatment, however, the assessment of recurrence by MRI can be difficult because contrast enhancement cannot effectively differentiate tumor recurrence from radiation necrosis. PET/CT imaging provides a highly accurate image that is useful for detecting primary and recurrent high- and low-grade brain tumors.

In the study published in the March 2012 issue of the Journal of Nuclear Medicine, referring physicians were given a survey before performing PET/CT scans with F-18-DOPA on patients with known or suspected brain tumors. The prescan surveys asked about indication, tumor histology or grade, level of suspicion for tumor recurrence, and planned management. Soon after the PET/CT scanning, the referring physicians were asked to complete a survey to categorize PET findings, level of suspicion for primary or recurrent brain tumors, and intended management alterations. Six months following the scans, the physicians took another survey dealing with recurrence and survival.

Of the 58 cases that were included in the survey, the clinical suspicion for recurrence increased in 33%, remained unchanged in 50%, and decreased in 17% of patients after adding the PET/CT findings to other diagnostic data. As a result, several changes in management were recommended, with changes from “watch and wait” to chemotherapy (25%) and from chemotherapy to “watch and wait” (17%) occurring most frequently. Seventy-five percent of the recommended changes were implemented.

“We know that F-DOPA PET/CT imaging is highly accurate for detecting brain tumors, and in our research we’ve shown that this imaging modality has a significant impact on patient management,” said Johannes Czernin, MD, a professor of cardiology from the University of California, Los Angeles’ (UCLA) David Geffen School of Medicine (USA), and one of the authors of the study. “In the future, we will initiate multicenter trials to determine whether these management changes have an impact on patient outcome. We believe that amino-acid transport imaging with PET will eventually be an important and frequently used imaging modality in brain cancer.”

The five year survival rates vary among tumor subtypes and range from 3.3% for high-grade tumors to 70% for low-grade tumors.

Related Links:
University of California, Los Angeles’ David Geffen School of Medicine