Is There an Added Value of Quantitative DCE-MRI by Magnetic Resonance Dispersion Imaging for Prostate Cancer Diagnosis?

Abstract

In this multicenter, retrospective study, we evaluated the added value of magnetic resonance dispersion imaging (MRDI) to standard multiparametric MRI (mpMRI) for PCa detection. The study included 76 patients, including 51 with clinically significant prostate cancer (csPCa), who underwent radical prostatectomy and had an mpMRI including dynamic contrast-enhanced MRI. Two radiologists performed three separate randomized scorings based on mpMRI, MRDI and mpMRI+MRDI. Radical prostatectomy histopathology was used as the reference standard. Imaging and histopathology were both scored according to the Prostate Imaging-Reporting and Data System V2.0 sector map. Sensitivity and specificity for PCa detection were evaluated for mpMRI, MRDI and mpMRI+MRDI. Inter- and intra-observer variability for both radiologists was evaluated using Cohen's Kappa. On a per-patient level, sensitivity for csPCa for radiologist 1 (R1) for mpMRI, MRDI and mpMRI+MRDI was 0.94, 0.82 and 0.94, respectively. For the second radiologist (R2), these were 0.78, 0.94 and 0.96. R1 detected 4% additional csPCa cases using MRDI compared to mpMRI, and R2 detected 20% extra csPCa cases using MRDI. Inter-observer agreement was significant only for MRDI (Cohen's Kappa = 0.4250, p = 0.004). The results of this study show the potential of MRDI to improve inter-observer variability and the detection of csPCa.

Keywords: dynamic constrast-enhanced MRI; multiparametric MRI; pharmacokinetic analysis; prostate cancer.

Figure 1

(a) Example of MRDI map; (b) sector map of PIRADS 2.0 used for scoring.

Figure 2

Example of histopathology result.

Figure 3

Schematic representation comparing the performance of mpMRI and MRDI. (a,b) represents the true positives found by mpMRI alone (dark blue), MRDI alone (light blue) and both MRDI and mpMRI (MRDI ∩ mpMRI, mid-tone blue) for radiologists 1 and 2, respectively; (c,d) represents the true negatives found by mpMRI alone (dark orange), MRDI alone (light orange) and both MRDI and mpMRI (MRDI ∩ mpMRI, mid-tone orange) for radiologists 1 and 2, respectively.

Figure 4

Example cases for two patients showing mpMRI images, MRDI maps and the corresponding visually matched histopathology slice. For both cases, the lesion was diagnosed as Gleason score 4 + 3. For (a), both R1 and R2 missed csPCa on MRDI but found it on mpMRI, while for (b), both R1 and R2 missed csPCa on mpMRI but found it on MRDI.