Faculty Bibliography

OBJECTIVE. The objective of our study was to compare interreader reproducibility of the recently proposed "Prostate Imaging Reporting and Data System," or "PI-RADS," scale incorporating fixed criteria and a standard Likert scale based on overall impression for prostate cancer localization using multiparametric MRI. MATERIALS AND METHODS. Fifty-five patients who underwent a 3-T prostate MRI examination using a pelvic phased-array coil and incorporating T2-weighted imaging, diffusion-weighted imaging, and dynamic contrast-enhanced imaging were included in the study. Three radiologists (6, 4, and 1 year of experience) independently scored 18 regions (12 in the peripheral zone [PZ] and six in the transition zone [TZ]) using PI-RADS (range, 3-15) and Likert (range, 1-5) scales, which were based on fixed criteria and overall impression, respectively. Interreader reproducibility was evaluated using the concordance correlation coefficient (CCC), which assesses exact agreement between scores (minimal, < 0.2; poor, 0.2-<0.4; moderate, 0.4-<0.6; strong, 0.6-<0.8; almost perfect, >/= 0.8). RESULTS. Agreement between experienced readers was strong in the PZ and TZ combined and in the PZ for both the PI-RADS and Likert scales (CCC = 0.608-0.677), moderate in the TZ for the Likert scale (CCC = 0.519), and poor in the TZ for PI-RADS (CCC = 0.376). Agreement between experienced and inexperienced readers was moderate to poor in the PZ and TZ combined for PI-RADS (CCC = 0.340-0.477), moderate in the PZ and TZ combined for the Likert scale (CCC = 0.471-0.497), moderate in the PZ for PI-RADS and Likert scales (CCC = 0.472-0.542), minimal to poor in the TZ for PI-RADS (CCC = 0.094-0.283), and poor in the TZ for the Likert scale (CCC = 0.287-0.400). CONCLUSION. Interreader reproducibility tended to be higher for relatively experienced readers than for less experienced readers and to be higher in the PZ than in the TZ. For the relatively experienced readers, reproducibility was similar for PI-RADS and Likert scales in the PZ but was somewhat higher for the Likert scale than for PI-RADS in the TZ.

PURPOSE: To compare tumor detection on acquired diffusion-weighted (DW) images and apparent diffusion coefficient (ADC) maps, obtained using b-values of 1000 s/mm(2) and 2000 s/mm(2) , using radical prostatectomy as the reference. MATERIALS AND METHODS: In all, 29 prostate cancer patients who underwent 3T magnetic resonance imaging (MRI) including DW imaging using b-values of 1000 s/mm(2) and 2000 s/mm(2) were included. Two radiologists independently evaluated four image sets during different sessions and recorded the location and diameter of the dominant lesion: DW images acquired using b-values of 1000 s/mm(2) and 2000 s/mm(2) and ADC maps calculated using maximal b-values of 1000 s/mm(2) and 2000 s/mm(2) . Findings were correlated with the location and diameter of the dominant lesion at prostatectomy. Tumor-to-PZ contrast was also calculated, unblinded to pathology. RESULTS: Both readers achieved significantly higher sensitivity for DW images obtained using a b-value of 2000 s/mm(2) than 1000 s/mm(2) (P < 0.001), although there was no difference in sensitivity between ADC maps calculated using the two b-values (P >/= 0.309). Tumor-to-PZ contrast was higher for DW images using a b-value of 2000 s/mm(2) (P = 0.067), although it was not different between the two corresponding ADC maps (P = 0.544). For both readers, correlations with tumor diameters were higher for either ADC map (r = 0.59-0.73) than for either acquired DW image set (r = 0.03-0.57). CONCLUSION: Use of a b-value of 2000 s/mm(2) compared with a b-value of 1000 s/mm(2) resulted in improved tumor sensitivity and higher tumor-to-PZ contrast on the acquired DW images, although performance of the ADC maps corresponding with the two b-values was similar. Correlation with tumor size was greater for either ADC map than for either acquired DW image set. J. Magn. Reson. Imaging 2013;. (c) 2013 Wiley Periodicals, Inc.

OBJECTIVE. The objective of this study was to compare the performance of different methodologies for interpretation of dynamic contrast-enhanced MRI (DCE-MRI) in localization of peripheral zone prostate cancer. MATERIALS AND METHODS. Forty-three men (mean age, 59 +/- 8 years) with biopsy-proven prostate cancer who underwent prostate MRI including DCE-MRI before prostatectomy were included. Two observers independently reviewed DCE-MRI data using three methodologies: qualitative, in which kinetic curves of signal intensity versus time were generated for foci showing rapid enhancement on subtracted contrast-enhanced images; semiquantitative, in which a biexponential heuristic model was used to generate color-coded maps depicting maximum slope and washout of contrast enhancement; and quantitative, in which a Tofts model was used to generate color-coded influx rate transfer constant (K(trans)) and efflux rate transfer constant (Kep) maps. Findings were stratified by whether suspicious foci showed evidence of washout with each method and compared with histopathologic results in each sextant. RESULTS. There was similar accuracy for the semiquantitative and quantitative models for both observers irrespective of requiring evidence of washout. For the more experienced observer, requiring washout resulted in lower sensitivity and higher specificity for the qualitative and semiquantitative models. Also for the more experienced observer, use of either a semiquantitative or quantitative model provided greater sensitivity compared with a qualitative model when requiring washout. There was no association between tumor detection and Gleason score for any DCE-MRI methodology for either reader. CONCLUSION. For the experienced reader, sensitivity for peripheral zone tumor was increased by use of either a semiquantitative or quantitative model compared with a qualitative model and decreased by requiring washout. We failed to identify a difference in performance between semiquantitative and quantitative models.