PET/MR imaging efficacious for mapping recurrent prostate cancer

A relatively new imaging system demonstrates a higher capacity for mapping recurrent prostate cancer than integrated positron emission tomography and computed tomography, researchers recently reported at the Society of Nuclear Medicine and Molecular Imaging annual meeting in Vancouver, British Columbia.

In this comparative study, recurrent prostate cancer was imaged both with positron emission tomography/magnetic resonance and positron emission tomography/computed tomography (PET/CT) with the molecular imaging agent C-11 choline, which was approved for this use by the FDA last year.

“The combination of PET, here with C-11 choline, and functional MRI provides complementary information that increases diagnostic certainty with higher detection rates, especially for more precise localization of recurrence. This could help to better tailor specific therapy; eg, radiation of the pelvis versus antihormonal therapy, for patients with metastatic prostate cancer,” said lead author Matthias Eiber, MD, of Technical University Munich in Munich, Germany.

The study included 31 patients who had both PET/CT and PET/MR performed for restaging of recurrent prostate cancer with a single injection of the imaging agent C-11 choline. PET/CT scans occurred about 5 minutes after injection, and PET/MR scans occurred about 51 minutes after injection. Scans were interpreted separately, and all detected lesions were categorized according to suspected metastases as definitely, probably, or indeterminately metastatic.

The authors discovered that PET/MR found more areas of metastases-17 in 12 different patients-when compared to PET/CT, which found 12 areas of metastases in eight subjects. PET/MR also found more lymph node metastases: 42 versus 39 areas of interest with PET/CT. The same held true for bone metastases, which were detected in 17 areas for five patients with PET/MR and 14 areas for four patients with PET/CT.

PET/MR was also associated with considerably lower radiation exposure compared to PET/CT. As many of these patients often get a series of examinations in the course of their disease, despite their high average age, radiation protection could be another argument for the promotion of PET/MR.

“In principle, whole-body integrated PET/MR is a technique that is officially commercially available; however, so far only a limited number of these scanners have been installed worldwide,” said Dr. Eiber. “Showing a concrete example of how combining PET and functional MR imaging benefits patients with metastatic prostate cancer could potentially motivate continued PET/MR research in this field.”