DCE-MRI of hepatocellular carcinoma: perfusion quantification with Tofts model versus shutter-speed model-initial experience

To quantify hepatocellular carcinoma (HCC) perfusion and flow with the fast exchange regime-allowed Shutter-Speed model (SSM) compared to the Tofts model (TM). In this prospective study, 25 patients with HCC underwent DCE-MRI. ROIs were placed in liver parenchyma, portal vein, aorta and HCC lesions. Signal intensities were analyzed employing dual-input TM and SSM models. ART (arterial fraction), K (trans) (contrast agent transfer rate constant from plasma to extravascular extracellular space), v (e) (extravascular extracellular volume fraction), k (ep) (contrast agent intravasation rate constant), and tau (i) (mean intracellular water molecule lifetime) were compared between liver parenchyma and HCC, and ART, K (trans), v (e) and k (ep) were compared between models using Wilcoxon tests and limits of agreement. Test-retest reproducibility was assessed in 10 patients. ART and v (e) obtained with TM; ART, v (e) , k (e) and tau (i) obtained with SSM were significantly different between liver parenchyma and HCC (p < 0.04). Parameters showed variable reproducibility (CV range 14.7-66.5 % for both models). Liver K (trans) and v (e) ; HCC v (e) and k (ep) were significantly different when estimated with the two models (p < 0.03). Our results show differences when computed between the TM and the SSM. However, these differences are smaller than parameter reproducibilities and may be of limited clinical significance.