Perfusion and flow extraction product as potential discriminators in untreated follicular and diffuse large B cell lymphomas using volume perfusion CT with attempt at histopathologic explanation.

Abstract

The purpose of this article is to measure perfusion parameters, including transit constant (K(trans)), in untreated follicular and diffuse large B cell lymphoma using volume perfusion CT, to establish their discriminating role and to search for a possible histopathologic background. Between January 2010 and June 2011, 46 consecutive patients with untreated histologically confirmed follicular lymphoma (n = 16) or diffuse large B cell lymphoma (n = 30) were enrolled. A 40-second volume perfusion CT of the tumor bulk using 6.9-cm z-axis coverage and a total of 26 volume measurements was performed. Blood flow (BF), blood volume (BV), and K(trans) were determined. Tumor size was recorded as the product of long- and short-axis diameters. In 13 of 46 patients, pathologic specimens of an appropriate size were available for assessment of microvessel density (MVD) and microvascular luminal diameter for comparison with volume perfusion CT measurements. Mean BF, BV, and K(trans) values were significantly higher in follicular lymphoma than in diffuse large B cell lymphoma, even after controlling for patient age and tumor size (p < 0.05, respectively). Although MVD was slightly, but not significantly, higher in follicular lymphoma versus diffuse large B cell lymphoma (p > 0.05), microvascular luminal diameter was significantly larger in follicular lymphoma than in diffuse large B cell lymphoma (p < 0.05). We defined cutoff values for BF, BV, and K(trans). If the cutoff points are met for all three parameters, the overall accuracy for correctly identifying diffuse large B cell lymphoma and follicular lymphoma was 90.5% and 87.5%, respectively. Volume perfusion CT allows assessment of differences in vascularity of follicular and diffuse large B cell lymphomas, reflecting vascular luminal variability and histopathologic anatomy.