Purpose To evaluate the effect of different methods to convert MR signal intensity (SI) to gadolinium concentration ([Gd]) on estimation and reproducibility of model-free and modeled hepatic perfusion parameters measured with DCE-MRI. Materials and Methods In this IRB-approved prospective study, 23 DCE-MRI examinations of the liver were performed on 17 patients. SI was converted to [Gd] using linearity vs. non linearity assumptions (using SPGR signal equations). [Gd] vs. time curves were analyzed using model-free parameters and a dual-input single compartment model. Perfusion parameters obtained with the two conversion methods were compared using paired Wilcoxon test. Test-retest and inter-observer reproducibility of perfusion parameters were assessed in 6 patients. Results There were significant differences between the two conversion methods for the following parameters: AUC60 (area under the curve at 60 seconds, p <0.001), peak gadolinium concentration (Cpeak, p <0.001), upslope (p <0.001), Fp (portal flow, p=0.04), total hepatic flow (Ft, p=0.007), and MTT (mean transit time, p <0.001). Our preliminary results showed acceptable to good reproducibility for all model-free parameters for both methods [mean coefficient of variation (CV) range, 11.87–23.7%], except for upslope (CV = 37%). Among modeled parameters, DV (distribution volume) had CV <22% with both methods, PV and MTT showed CV <21% and <29% using SPGR equations, respectively. Other modeled parameters had CV >30% with both methods. Conclusion Linearity assumption is acceptable for quantification of model-free hepatic perfusion parameters while the use of SPGR equations and T1 mapping may be recommended for the quantification of modeled hepatic perfusion parameters.

ObjectivesLearn about the prevalence and characteristics of the palliative procedures performed by Interventional Radiology. Understand how Interventional Radiology practitioners might become formidable allies in improving symptoms and function for patients with advanced illness. Original Research Background. Many of the procedures performed by an Interventional Radiology (IR) department are palliative in nature. With less toxicity and risk, IR procedures are ideal for patients with advanced illnesses seeking improvement in symptoms or function.Research Objectives. We aim to quantify and describe the palliative procedures performed by an IR department at a tertiary care hospital.