COMPARISON BETWEEN PERFUSION COMPUTED TOMOGRAPHY AND DYNAMIC CONTRAST-ENHANCED MAGNETIC RESONANCE IMAGING IN RECTAL CANCER

Purpose: To compare pretreatment scans with perfusion computed tomography (pCT) vs. dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in rectal tumors. Methods and Materials: Nineteen patients diagnosed with rectal cancer were included in this prospective study. All patients underwent both pCT and DCE-MRI. Imaging was performed on a dedicated 40-slice CT positron emission tomography system and a 3-T MRI system. Dynamic contrast enhancement was measured in tumor tissue and the external iliac artery. Tumor perfusion was quantified in terms of pharmacokinetic parameters: transfer constant K-trans, fractional extravascular extracellular space nu(e), and fractional plasma volume nu(p). Pharmacokinetic parameter values and their heterogeneity (by 80% quantile value) were compared between pCT and DCE-MRI. Results: Tumor K-trans values correlated significantly for the voxel-by-voxel derived median (Kendall's tau correlation, tau = 0.81, p <0.001) and 80% quantile (tau = 0.54, p = 0.04), as well as for the averaged uptake (r = 0.58, p = 0.03). However, no significant correlations were found for nu(e) and nu(p), derived from the voxel-by-voxel derived median and 80% quantile and derived from the averaged uptake curves. Conclusions: This study demonstrated for the first time that pCT provides K-trans values comparable to those of DCE-MRI. However, no correlation was found for the nu(e) and nu(p) parameters between CT and MRI. Computed tomography can serve as an alternative modality to MRI for the in vivo evaluation of tumor angiogenesis in terms of the transfer constant K-trans. (C)2010 Elsevier Inc.