MRI-Derived Restriction Spectrum Imaging Cellularity Index is Associated with High Grade Prostate Cancer on Radical Prostatectomy Specimens.
OBJECTIVE
We evaluate a novel magnetic resonance imaging (MRI) technique to improve detection of aggressive prostate cancer (PCa).


METHODS
We performed a retrospective analysis of pre-surgical prostate MRI scans using an advanced diffusion-weighted imaging technique called restriction spectrum imaging (RSI), which can be presented as a normalized z-score statistic. Scans were acquired prior to radical prostatectomy. Prostatectomy specimens were processed using whole-mount sectioning and regions of interest (ROIs) were drawn around individual PCa tumors. Corresponding ROIs were drawn on the MRI imaging and paired with ROIs in regions with no pathology. RSI z-score and conventional apparent diffusion coefficient (ADC) values were recorded for each ROI. Paired t-test, ANOVA, and logistic regression analyses were performed.


RESULTS
We evaluated 28 patients with 64 ROIs (28 benign and 36 PCa). The mean difference in RSI z-score (PCa ROI-Benign ROI) was 2.17 (SE = 0.11; p < 0.001) and in ADC was 551 mm(2)/s (SE = 80 mm(2)/s; paired t-test, p < 0.001). The differences in the means among all groups (benign, primary Gleason 3, and primary Gleason 4) was significant for both RSI z-score (F 3,64 = 97.7, p < 0.001) and ADC (F 3,64 = 13.9, p < 0.001). A t-test was performed on only PCa tumor ROIs (n = 36) to determine PCa aggressiveness (Gleason 3 vs. Gleason 4) revealing that RSI z-score was still significant (p = 0.03), whereas, ADC values were no longer significant (p = 0.08). In multivariable analysis adjusting for age and race, RSI z-score was associated with PCa aggressiveness (OR 10.3, 95% CI: 1.4-78.0, p = 0.02) while ADC trended to significance (p = 0.07).


CONCLUSIONS
The RSI-derived normalized cellularity index is associated with aggressive PCa as determined by pathologic Gleason scores. Further utilization of RSI techniques may serve to enhance standardized reporting systems for PCa in the future.
Department of Urology, University of California San Diego School of Medicine , San Diego, CA , USA.
Michael A
MA
Liss
Department of Radiology, University of California San Diego School of Medicine , San Diego, CA , USA.
Nathan S
NS
White
Department of Urology, University of California San Diego School of Medicine , San Diego, CA , USA.
J Kellogg
JK
Parsons
Department of Radiology, University of California San Diego School of Medicine , San Diego, CA , USA.
Natalie M
NM
Schenker-Ahmed
Department of Radiology, University of California San Diego School of Medicine , San Diego, CA , USA.
Rebecca
R
Rakow-Penner
Department of Radiology, University of California San Diego School of Medicine , San Diego, CA , USA.
Joshua M
JM
Kuperman
Department of Radiology, University of California San Diego School of Medicine , San Diego, CA , USA.
Hauke
H
Bartsch
Department of Radiology, University of California San Diego School of Medicine , San Diego, CA , USA.
Hyung W
HW
Choi
Department of Radiology, University of California San Diego School of Medicine , San Diego, CA , USA.
Robert F
RF
Mattrey
Department of Radiology, University of California San Diego School of Medicine , San Diego, CA , USA.
William G
WG
Bradley
Department of Pathology, University of California San Diego School of Medicine , San Diego, CA , USA.
Ahmed
A
Shabaik
Department of Pathology, University of California Los Angeles Geffen School of Medicine , Los Angeles, CA , USA.
Jiaoti
J
Huang
Department of Radiology, University of California Los Angeles Geffen School of Medicine , Los Angeles, CA , USA.
Daniel J A
DJ
Margolis
Department of Radiology, University of California Los Angeles Geffen School of Medicine , Los Angeles, CA , USA.
Steven S
SS
Raman
Department of Urology, University of California Los Angeles Geffen School of Medicine , Los Angeles, CA , USA.
Leonard S
LS
Marks
Department of Urology, University of California San Diego School of Medicine , San Diego, CA , USA.
Christopher J
CJ
Kane
Department of Urology, University of California Los Angeles Geffen School of Medicine , Los Angeles, CA , USA.
Robert E
RE
Reiter
Department of Radiology, University of California San Diego School of Medicine , San Diego, CA , USA ; Department of Neurosciences, University of California San Diego , La Jolla, CA , USA.
Anders M
AM
Dale
Department of Radiology, University of California San Diego School of Medicine , San Diego, CA , USA.
David S
DS
Karow
Gleason score; MRI imaging; cellularity; prostate; prostate cancer