Assessment of tissue perfusion of pancreatic cancer as potential imaging biomarker by means of Intravoxel incoherent motion MRI and CT perfusion: correlation with histological microvessel density as ground truth

Background/objectives: The aim of this study was to compare intravoxel incoherent motion (IVIM) diffusion weighted (DW) MRI and CT perfusion to assess tumor perfusion of pancreatic ductal adenocarcinoma (PDAC). Methods: In this prospective study, DW-MRI and CT perfusion were conducted in nineteen patients with PDAC on the day before surgery. IVIM analysis of DW-MRI was performed and the parameters perfusion fraction f, pseudodiffusion coefficient D*, and diffusion coefficient D were extracted for tumors, upstream, and downstream parenchyma. With a deconvolution-based analysis, the CT perfusion parameters blood flow (BF) and blood volume (BV) were estimated for tumors, upstream, and downstream parenchyma. In ten patients, intratumoral microvessel density (MVDtumor) and microvessel area (MVA(tumor)) were analyzed microscopically in resection specimens. Correlation coefficients between IVIM parameters, CT perfusion parameters, and histological microvessel parameters in tumors were calculated. Receiver operating characteristic (ROC) analysis was performed for differentiation of tumors and upstream parenchyma. Results: f(tumor) significantly positively correlated with BFtumor (r = 0.668, p = 0.002) and BVtumor (r = 0.672, p = 0.002). There were significant positive correlations between f(tumor) and MVDtumor/ MVA(tumor) (r >= 0.770, p <= 0.009) as well as between BFtumor and MVDtumor/ MVA(tumor) (r >= 0.697, p <= 0.025). Correlation coefficients between f(tumor) and MVDtumor/ MVA(tumor) were not significantly different from correlation coefficients between BFtumor and MVDtumor/ MVA(tumor) (p >= 0.400). Moreover, f, BF, BV, and permeability values (PEM) showed excellent performance in distinguishing tumors from upstream parenchyma (area under the ROC curve >= 0.874). Conclusions: The study shows that IVIM derived f(tumor) and CT perfusion derived BFtumor similarly reflect vascularity of PDAC and seem to be comparably applicable for the evaluation of tumor perfusion for tumor characterization and as potential quantitative imaging biomarker.

Automated summary

This study compares IVIM-derived f(tumor) and CT perfusion-derived BFtumor for evaluating tumor vascularity in PDAC, showing they can be equally applicable as quantitative imaging biomarkers for tumor perfusion evaluation and characterization. The correlation coefficients between IVIM and CT perfusion parameters along with histological microvessel parameters suggest their potential for clinical use in distinguishing tumors from upstream parenchyma effectively.