Correlation of Intravoxel Incoherent Motion and Diffusion Kurtosis MR Imaging Models With Reactive Stromal Grade in Prostate Cancer

Abstract

Background: Reactive stroma is recognized as one of the independent prognostic factors in prostate cancer (PCa). Intravoxel incoherent motion (IVIM) and diffusion kurtosis imaging (DKI) may be useful for assessing the reactive stromal grade (RSG).

Purpose: To investigate whether IVIM and DKI models can evaluate RSG in PCa patients.

Study type: Retrospective.

Subjects: A total of 56 PCa patients aged 73 years on average confirmed by MRI and transrectal ultrasound (MRI/TRUS) fusion biopsy divided into two subgroups (18 high RSG and 38 low RSG).

Field strength/sequence: A 3 T/T₁ WI-fs, T₁ WI, T₂ WI-fs, T₂ WI, DWI, IVIM, and DKI.

Assessment: Apparent diffusion coefficient (ADC), pure diffusion coefficient (D), pseudo-diffusion coefficient (D*), perfusion fraction (f), mean diffusion (MD), mean kurtosis (MK) were obtained. Patients were divided into high RSG PCa (>50% reactive stroma) and low RSG PCa (≤50% reactive stroma) groups on hematoxylin and eosin (H&E) stained sections.

Statistical tests: Spearman correlation and independent sample t-test or Wilcoxon's rank sum test was used to investigate the relationship between each imaging parameter and RSG. The combined parameters were calculated using a binary logistic regression model. Receiver operating characteristic (ROC) analysis was used to explore the value of individual and combined parameters to differentiate between high and low RSG group. Area under the ROC curves (AUC) > 0.7 were used as reference standards.

Results: ADC, D, f, and MD values showed positive correlation with RSG (r = 0.489, 0.619, 0.318, and 0.544, respectively); MK showed negative correlation with RSG (r = -0.444). ADC, D, f, and MD values were significantly lower in the low RSG group than in the high RSG group. The combined model showed the best diagnostic ability to differentiate low and high RSG groups (AUC = 0.887).

Data conclusion: Parameters of IVIM and DKI may be promising methods for assessment of RSG in PCa patients.

Evidence level: 3.

Technical efficacy: Stage 3.

Keywords: diffusion magnetic resonance imaging; prostate cancer; reactive stromal grade.