Quantitative Multi-Parametric MRI of the Prostate Reveals Racial Differences

Abstract

Purpose: This study investigates whether quantitative MRI and histology of the prostate reveal differences between races, specifically African Americans (AAs) and Caucasian Americans (CAs), that can affect diagnosis. Materials and Methods: Patients (98 CAs, 47 AAs) with known or suspected prostate cancer (PCa) underwent 3T MRI (T2W, DWI, and DCE-MRI) prior to biopsy or prostatectomy. Quantitative mpMRI metrics: ADC, T2, and DCE empirical mathematical model parameters were calculated. Results: AAs had a greater percentage of higher Gleason-grade lesions compared to CAs. There were no significant differences in the quantitative ADC and T2 values between AAs and CAs. The cancer signal enhancement rate (α) on DCE-MRI was significantly higher for AAs compared to CAs (AAs: 13.3 ± 9.3 vs. CAs: 6.1 ± 4.7 s^-1, p < 0.001). The DCE signal washout rate (β) was significantly lower in benign tissue of AAs (AAs: 0.01 ± 0.09 s^-1 vs. CAs: 0.07 ± 0.07 s^-1, p < 0.001) and significantly elevated in cancer tissue in AAs (AAs: 0.12 ± 0.07 s^-1 vs. CAs: 0.07 ± 0.08 s^-1, p = 0.02). DCE significantly improves the differentiation of PCa from benign in AAs (α: 52%, β: 62% more effective in AAs compared to CAs). Histologic analysis showed cancers have a greater proportion (p = 0.04) of epithelium (50.9 ± 12.3 vs. 44.7 ± 12.8%) and lower lumen (10.5 ± 6.9 vs. 16.2 ± 6.8%) in CAs compared to AAs. Conclusions: This study shows that AAs have different quantitative DCE-MRI values for benign prostate and prostate cancer and different histologic makeup in PCa compared to CAs. Quantitative DCE-MRI can significantly improve the performance of MRI for PCa diagnosis in African Americans but is much less effective for Caucasian Americans.

Keywords: African Americans; Caucasian Americans; DCE-MRI; MRI; prostate cancer; quantitative; racial differences.

Figure 1

52-year-old African American patient with Gleason 4 + 3 cancer in the left apex in the peripheral zone (red arrows on MRI). The lesion is seen as a hypo-intense region on the T2W image, T2 (87.9 ± 16.4 ms), and mildly hypo-intense on ADC (1.32 ± 0.20 µm²/ms) maps with early focal enhancement on DCE-MRI, evidenced by high signal enhancement rate (19.3 s⁻¹) and rapid washout rate (0.07 s⁻¹). Surrounding benign tissue in the peripheral zone had ADC = 2.05 ± 0.10 µm²/ms, T2 = 308.9 ± 62.6 ms, α = 2.87 s⁻¹, and β = 0.04 s⁻¹. Another relevant finding is the presence of Gleason 3 + 3 cancers in the right apex. Cancers are outlined in blue on histology sections.

Figure 2

52-year-old Caucasian American patient with Gleason 3 + 4 cancer in the right apex in the peripheral zone (red arrows on mpMRI). The lesion is seen as a hypo-intense region on the T2W image, T2 (112.4 ± 54.6 ms), and mildly hypo-intense on ADC (0.86 ± 0.12 µm²/ms) maps with only diffuse early enhancement on DCE-MRI, evidenced by low signal enhancement rate (3.50 s⁻¹) and washout rate (0.03 s⁻¹). Surrounding benign tissue in the peripheral zone had ADC = 1.16 ± 0.19 µm²/ms, T2 = 125.1 ± 34.5 ms, α = 3.20 s⁻¹, and β = 0.01 s⁻¹. Cancers are outlined in blue on histology sections.