Nuclear Medicine & Radiation Therapy

Long-Term Post-Treatment MR and PET/CT Imaging in Prostate Cancer Patients in Complete Remission after Curative Radiotherapy with or without Androgen Deprivation: The Image of Cure

Abstract

Raymond Miralbell, Hansjörg Vees, Osman Ratib, Michael Wissmeyer, Charles Steiner, Yann Seimbille, Haleem G. Khan and Franz Buchegger

Purpose: To investigate the risk of false positive MRI and 18F-Fluorocholine (FCH) or 11Cacetate (AC) PET/ CT in prostate cancer patients with long term biochemical and clinical remission after curative radiation therapy (RT).
Methods and Materials: Twenty patients underwent MRI studies including T2-weighted, diffusion weighted, dynamic contrast-enhanced, and spectroscopic imaging. Nine of these patients were selected to have FCH and 10 AC PET/CT studies.
Results: MR spectroscopy suggested positive or equivocal results in 16/20 patients. However, the combined interpretation of all MRI sequences dropped the rate of suspicious or equivocal studies to 8/20. All but one patient underwent also PET/CT and early PET frames showed suspicious or equivocal local images in 15/19 patients (8/10 with AC, 7/9 with FCH). However, a combined evaluation of early and late PET frames was judged equivocal in only 1 patient.
Conclusions: Multimodal MRI, early single FCH or AC PET frames of the prostate after curative RT may not be accurate enough to differentiate remission from early recurrence. Multiple-phase evaluation of PET images, however, may reduce significantly the risk of reporting equivocal or false positive results.