Comparison of quantitative apparent diffusion coefficient parameters with prostate imaging reporting and data system V2 assessment for detection of clinically significant peripheral zone prostate cancer

Abstract

Purpose To compare diagnostic performance of PI-RADSv2 with ADC parameters to identify clinically significant prostate cancer (csPC) and to determine the impact of csPC definitions on diagnostic performance of ADC and PI-RADSv2. Methods We retrospectively identified treatment-naïve pathology-proven peripheral zone PC patients who underwent 3T prostate MRI, using high b-value diffusion-weighted imaging from 2011–2015. Using 3D slicer, areas of suspected tumor (T) and normal tissue (N) on ADC (b=0,1400) were outlined volumetrically. Mean ADCT, mean ADCN, ADCratio (ADCT/ADCN) were calculated. PI-RADSv2 was assigned. Three csPC definitions were used: (A) Gleason score (GS)≥4+3; (B) GS≥3+4; (C) MRI-based tumor volume>0.5cc. Performances of ADC parameters and PI-RADSv2 in identifying csPC were measured using nonparametric comparison of receiver operating characteristic curves using the area under the curve (AUC). Results 85 cases met eligibility requirements. Diagnostic performances (AUC) in identifying csPC using 3 definitions were: (A) ADCT (0.83) was higher than PI-RADSv2 (0.65, p=0.006); (B) ADCT (0.86) was higher than ADCratio (0.68, p<0.001), and PI-RADSv2 (0.70, p=0.04); (C) PI-RADSv2 (0.73) performed better than ADCratio (0.56, p=0.02). ADCT performance was higher when csPC was defined by A or B versus C (p=0.038 and p=0.01, respectively). ADCratio performed better when csPC was defined by A versus C (p=0.01). PI-RADSv2 performance was not affected by csPC definition. Conclusions When csPC was defined by GS, ADC parameters provided better csPC discrimination than PI-RADSv2, with ADCT providing best result. When csPC was defined by MRI-calculated volume, PI-RADSv2 provided better discrimination than ADCratio. csPC definition did not affect PI-RADSv2 diagnostic performance.

A Pilot Study of Multidimensional Diffusion MRI for Assessment of Tissue Heterogeneity in Prostate Cancer

“…Monoexponential ADC is considered standard of care for assessment of patients who have a clinical suspicion of having PCa and is an established predictive biomarker for PCa. 7,8,28,38 The ROC analysis in differentiating tumor from normal tissue found AUC values similar to those published previously for ADC, 43 validating our measurements. It is difficult to improve on an AUC of 95% in differentiation of tumor and benign tissue, and indeed the combined MddMRI parameters MKa + MKi do not improve on the differentiation (AUC 90%).…”

“…Monoexponential ADC is considered standard of care for assessment of patients who have a clinical suspicion of having PCa and is an established predictive biomarker for PCa 7,8,28,38 . The ROC analysis in differentiating tumor from normal tissue found AUC values similar to those published previously for ADC, 43 validating our measurements.…”

“…Diffusion-weighted imaging (DWI) can discriminate indolent from clinically significant PCa. [3][4][5] The apparent diffusion coefficient (ADC) value, derived from DWI, has a negative correlation with pathology Gleason grade [6][7][8][9][10] and with tumor cellularity on pathology. 11 It is thought to be determined by water diffusion in luminal and ductal space 12,13 and cellular density.…”

Predictive role of PI-RADSv2 and ADC parameters in differentiating Gleason pattern 3 + 4 and 4 + 3 prostate cancer

“…All MRI examinations were performed on a 3.0 T magnet (GE Signa HDx, GE Healthcare, Waukesha, WI) using an eight-channel abdominal array and endorectal coil (Medrad, Pittsburgh, PA), as previously described [23,24]. Our protocol included: spoiled gradient echo (SPGR) T1-weighted sequences with repetition time (TR)/echo time (TE)/α = 385 ms/6.2 ms/65°, over a 16-cm2 field of view (FOV); fast relaxation fast spin echo (FRFSE) T2-weighted sequences with TR/TE = 3500 ms/102 ms over a 16-cm2 FOV; single-shot echo planar (EPI) DWI sequences with TR/TE = 2500 ms/65 ms and TR/TE = 3000 ms /80 ms for 0,500 0,1400 s/mm 2 b-values respectively.…”

Is perfect the enemy of good? Weighing the evidence for biparametric MRI in prostate cancer

“…[14] [15] [26] ADC metrics have been found to be inversely related to the Gleason grade, an established measure of prostate tumor aggressiveness. [27] [28] [29] The DWI is one of the most important contributors to the overall PI-RADS assessment and must be combined with data from the T2W and DCE images. [20] [5] Just as diffusion weighted sequences provide information about disordered cellular proliferation, contrast enhanced sequences reveal tumor neovascularization, a process largely mediated by increased androgen receptor expression seen in higher grade tumors.…”