¹⁸F Fluorocholine Dynamic Time-of-Flight PET/MR Imaging in Patients with Newly Diagnosed Intermediate- to High-Risk Prostate Cancer: Initial Clinical-Pathologic Comparisons

Abstract

Purpose:To investigate the initial clinical value of fluorine 18 ( 18 F) fluorocholine (FCH) dynamic positron emission tomography (PET)/ magnetic resonance (MR) imaging by comparing its parameters with clinical-pathologic findings in patients with newly diagnosed intermediate-to high-risk prostate cancer (PCa) who plan to undergo radical prostatectomy. Materials andMethods:The institutional review board approved the study protocol, and informed written consent was obtained from all subjects for this HIPAA-compliant study. Results:Of the PET parameters, maximum SUV of primary tumors showed significant correlations with several clinical-pathologic parameters including serum prostate-specific antigen level (r = 0.71, P = .01), pathologic stage (r = 0.59, P = .043), and postsurgical CAPRA score (r = 0.72, P = .008). The overall PI-RADS score showed significant correlations with pathologic tumor volume (r = 0.81, P , .001), percentage of tumor cells with Gleason scores greater than 3 (r = 0.59, P = .02), and postsurgical CAPRA score (r = 0.58, P = .046). The high-risk postsurgical CAPRA score patient group had a significantly higher maximum SUV than did the intermediate-risk group. Combined PET and MR imaging showed improved sensitivity (88%) for prediction of pathologic extraprostatic extension compared with that with MR imaging (50%) and PET (75%) performed separately. Conclusion:Maximum SUVs and PI-RADS scores from FCH PET/MR imaging show good correlation with clinical-pathologic characteristics, such as postsurgical CAPRA score, which are related to prognosis in patients with newly diagnosed intermediate-to high-risk PCa.q RSNA, 2016

Optimization of temporal sampling for 18F-choline uptake quantification in prostate cancer assessment

“…Seven different time samplings with a total study duration of 5 min were compared. Three time samplings were based on previous studies: 10 × 30″ [ 17 ], 6 × 10″–8 × 30″ [ 19 ], and 10 × 5″–4 × 10″–3 × 20″–5 × 30″ [ 16 ]. In addition, four time samplings with different frame durations were arbitrarily chosen: 5 × 60″, 15 × 15″–1 × 75″, 12 × 5″–8 × 30″, and 8 × 3″–8 × 12″–6 × 30″.…”

“…To extract kinetic parameters (PMOD software version 3.8; PMOD Technologies; Zürich, Switzerland), the one-tissue compartment model (with K1 = transfer coefficient from the arterial blood to the tissue compartment and k2 = transfer coefficient from the tissue compartment to the arterial blood) with a blood volume parameter (VB) reversible (1T2k + VB) and irreversible (1T1k + VB) were applied [ 16 , 19 ]. The model providing the best fits (Levenberg-Marquadt algorithm) to the tumoral TAC with the seven different time samplings was selected on the basis of the Akaike information criterion (AIC) for small sample sizes [ 26 ].…”

“…Concerning this time sampling for the kinetic analysis, no recommendations are available at the moment. Authors who published results with FCH kinetic analysis in PC were using different time samplings [ 16 – 19 ], with time bins ranging from 5 s to several minutes or more. The quantification of FCH uptake with kinetic analysis mandates careful optimization of time sampling.…”

Effect of Time-of-Flight and Regularized Reconstructions on Quantitative Measurements and Qualitative Assessments in Newly Diagnosed Prostate Cancer With 18F-Fluorocholine Dual Time Point PET/MRI

“…18 F-fluorocholine uptake was recorded in list mode and the list -mode data were replayed into 2 time points, 1 to 6 minutes summed and 7 to 30 minutes summed after administration of the radiotracer. Based on the observation of the tracer kinetics over 30 minutes from dynamic reconstructions of the entire 30 minutes, 16 the early time duration (1-6 minutes), excluding the first minute of mostly blood pool uptake, was determined since the rapid uptake of 18 F-fluorocholine reaches a plateau mostly around 5 to 6 minutes. In addition, the late time duration (7-30 minutes), with at least a minute gap from the early time point, was determined to capture accumulated activity after the radiotracer reached the plateau.…”

“…Further technological advance in TOF-PET, particularly the use of solid-state photomultipliers instead of photomultiplier tubes as the photodetector, made it possible for the TOF capability to be implemented even in a strong magnetic field, translating it into clinical PET/MRI systems as well. 12 , 14 - 16 …”