Abstract
BackgroundThe aim of this study is to investigate whether quantitative DW metrics can provide additive value to the reliable categorization of lesions within existing PI-RADSv2 guidelines. Fifty-eight patients with clinically suspicious prostate cancer who underwent PR examination, PSA serum levels, sextant TRUS-guided biopsies, and bi-parametric MR imaging were included in the study.ResultsSixty-six lesions were detected by histopathological analysis of surgical specimens. The mean ADC values were significantly lower in tumor than non-tumor tissue. The mean ADC value inversely correlated with Gleason score of tumors with a significant p value < 0.001.Conversely, a positive relationship was found between the ADC ratio (ADC of benign prostatic tissue to prostate cancer) and the pathologic Gleason score with a significant elevation of the ADC ratio along with an increase of the pathologic Gleason score (p < 0.001). ROC curves constructed for the tumor ADC and ADC ratio helped to distinguish pathologically aggressive (Gleason score ≥ 7) from non-aggressive (Gleason score ≤ 6) tumors and to correlate it with PIRADSv2 scoring to predict the presence of clinically significant PCA (PIRADSv2 DW ≥ 4). The ability of the tumor ADC and ADC ratio to predict highly aggressive tumors (GS> 7) was high (AUC for ADC and ADC ratio, 0.946 and 0.897; p = 0.014 and 0.039, respectively). The ADC cut-off value for GS ≥ 7 was < 0.7725 and for GS ≤ 6 was > 0.8620 with sensitivity and specificity 97 and 94%. The cutoff ADC ratio for predicting (GS > 7) was 1.42 and for GS ≤ 6 was > 1.320 with sensitivity and specificity 97 and 92%. By applying this ADC ratio cut-off value the sensitivity and specificity of reader 1 for correct categorization of PIRADSv2 DW > 4 increased from 90 and 68% to 95 and 90% and that of reader 2 increased from 94 and 88% to 97 and 92%, respectively.ConclusionEstimation of DW metrics (ADC and ADC ratio between benign prostatic tissue and prostate cancer) allow the non-invasive assessment of biological aggressiveness of prostate cancer and allow reliable application of the PIRADSv2 scoring to determine clinically significant cancer (DW score > 4) which may contribute in planning initial treatment strategies.
Highlights
The aim of this study is to investigate whether quantitative DW metrics can provide additive value to the reliable categorization of lesions within existing PI-RADSv2 guidelines
The specific aims of Prostate Imaging Reporting and Data System (PIRADS) 2 were to establish guidelines for minimum acceptable technical parameters in multi-parametric prostate Magnetic resonance imaging (MRI), to simplify and standardize the terminology and content of multi-parametric magnetic resonance imaging (mp-MRI) reports, and to develop assessment categories that summarize the levels of suspicion or risk of having significant prostatic cancer [7]
Even for the transition zone (TZ), Diffusion weighted imaging (DWI) enables a final determination of clinically significant cancer (CSC) when the findings of T2-weighted imaging (T2WI) are inconclusive [9].The role of dynamic contrast enhancement in routine evaluation of prostate cancer is uncertain
Summary
The aim of this study is to investigate whether quantitative DW metrics can provide additive value to the reliable categorization of lesions within existing PI-RADSv2 guidelines. Today with the use of multi-parametric magnetic resonance imaging (mp-MRI), accurate diagnosis and grading of prostatic cancer has become increasingly popular It includes a combination of T2-weighted, diffusion weighted, and dynamic contrast-enhanced imaging [4, 5]. The specific aims of PIRADS 2 were to establish guidelines for minimum acceptable technical parameters in multi-parametric prostate MRI, to simplify and standardize the terminology and content of mp-MRI reports, and to develop assessment categories that summarize the levels of suspicion or risk of having significant prostatic cancer [7]. Even for the TZ, DWI enables a final determination of clinically significant cancer (CSC) when the findings of T2-weighted imaging (T2WI) are inconclusive (e.g., a score of 3 on T2WI) [9].The role of dynamic contrast enhancement in routine evaluation of prostate cancer is uncertain. In the PIRADS version 2 suspicious enhancements (focal early enhancement) is considered a minor feature in evaluation [10]
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