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We evaluated the accuracy of PET/CT with 68 Ga-PSMA-HBED-CC-a 68 Ga-conjugated ligand of human prostate-specific membrane antigen (PSMA)-to localize cancer in the prostate and surrounding tissue at initial diagnosis. Methods: Twenty-one patients with biopsy-proven prostate cancer underwent 68 Ga-PSMA-HBED-CC ( 68 Ga-PSMA) PET/CT at a median of 4 d (range, 0-47 d) before radical prostatectomy. Based on a 6-segment model, the Gleason score and proportion of tumor tissue within each segment (segmental tumor burden, or STB) as determined by histopathology (STB HP ) were correlated with SUV max and STB as determined by different SUV cutoffs for 68 Ga-PSMA PET (STB ). Furthermore, the involvement of seminal vesicles and other extracapsular extension were assessed by histopathology and PET/CT. Results: Histopathology-positive segments (n 5 100 of 126; 79%) demonstrated a significantly higher mean ± SD SUV max (11.8 ± 7.6) than histopathology-negative segments (4.9 ± 2.9; P , 0.001). Receiver-operating-characteristic analysis revealed an optimal SUV max cutoff of 6.5 for discrimination of histopathology-positive segments from histopathology-negative segments (area under the curve, 0.84; P , 0.001), which gave 67% sensitivity, 92% specificity, a 97% positive predictive value, a 42% negative predictive value, and 72% accuracy. STB PET3 as determined by (2 · blood SUV) 1 (2 · SD) correlated best with STB HP (Pearson ρ 5 0.68; P , 0.001; mean difference ± SD, 19% ± 15%). PET/CT correctly detected invasion of seminal vesicles (n 5 11 of 21 patients; 52%) with 86% accuracy and tumor spread through the capsule (n 5 12; 57%) with 71% accuracy. Conclusion: 68 Ga-PSMA PET/CT accurately detected the location and extent of primary prostate cancer. Our preliminary findings warrant further investigation of 68 Ga-PSMA PET/CT in conjunction with needle biopsy.

Recent technical developments in MRI allow the use of accelerated, spatially-selective excitation (parallel-transmit, pTX). pTX can be used for zoomed echo-planar prostate imaging (pTX-EPI). pTX-EPI improves different aspects of image quality in prostate MRI. Distortion artefacts are reduced by the use of pTX-EPI in prostate MRI. Further studies should aim at assessing the diagnostic accuracy of pTX-EPI.

The velocity of collateral filling can be assessed in dynamic time-resolved computed tomography (CT) angiographies and may predict initial CT perfusion (CTP) and follow-up lesion size. We included all patients with an M1 ± internal carotid artery (ICA) occlusion and follow-up imaging from an existing cohort of 1791 consecutive patients who underwent multimodal CT for suspected stroke. The velocity of collateral filling was quantified using the delay of time-to-peak (TTP) enhancement of the M2 segment distal to the occlusion. Cerebral blood volume (CBV) and mean transit time (MTT)-CBV mismatch were assessed in initial CTP. Follow-up lesion size was assessed by magnetic resonance imaging (MRI) or non-enhanced CT (NECT). Multivariate analyses were performed to adjust for extent of collateralization and type of treatment. Our study comprised 116 patients. Multivariate analysis showed a short collateral blood flow delay to be an independent predictor of a small CBV lesion (P o 0.001) and a large relative mismatch (P o 0.001) on initial CTP, of a small follow-up lesion (P o 0.001), and of a small difference between initial CBV and follow-up lesion size (P = 0.024). Other independent predictors of a small lesion on follow-up were a high morphologic collateral grade (P = 0.001), lack of an additional ICA occlusion (P = 0.009), and intravenous thrombolysis (P = 0.022). Fast filling of collaterals predicts initial CTP and follow-up lesion size and is independent of extent of collateralization.