Abstract
In this work, the two compartment exchange model and two compartment uptake model were applied to obtain quantitative perfusion parameters in rectum carcinoma and the results were compared to those obtained by the deconvolution algorithm. Eighteen patients with newly diagnosed rectal carcinoma underwent 3 T MRI of the pelvis including a T1 weighted dynamic contrastenhanced (DCE) protocol before treatment. Mean values for Plasma Flow (PF), Plasma Volume (PV) and Mean Transit Time (MTT) were obtained for all three approaches and visualized in parameter cards. For the two compartment models, Akaike Information Criterion (AIC) and {{boldsymbol{chi }}}^{{bf{2}}} were calculated. Perfusion parameters determined with the compartment models show results in accordance with previous studies focusing on rectal cancer DCE-CT (PF2CX = 68 ± 44 ml/100 ml/min, PF2CU = 55 ± 36 ml/100 ml/min) with similar fit quality (AIC:169 ± 81/179 ± 77, {{boldsymbol{chi }}}^{{bf{2}}}:10 ± 12/9 ± 10). Values for PF are overestimated whereas PV and MTT are underestimated compared to results of the deconvolution algorithm. Significant differences were found among all models for perfusion parameters as well as between the AIC and {{boldsymbol{chi }}}^{{bf{2}}} values. Quantitative perfusion parameters are dependent on the chosen tracer kinetic model. According to the obtained parameters, all approaches seem capable of providing quantitative perfusion values in DCE-MRI of rectal cancer.
Highlights
Tissue perfusion and permeability can be measured non-invasively by dynamic contrast enhanced magnetic resonance imaging (DCE-MRI)[1]
The aim of our study was to investigate the results of different pharmacokinetic models for quantitative analysis of dynamic contrastenhanced (DCE)-MRI of rectal cancer
We investigated three different tracer kinetic approaches, namely the model-free fast deconvolution approach, the 2CU and the 2CX model, on its impact on the quantitative perfusion parameters for rectal cancer
Summary
Tissue perfusion and permeability can be measured non-invasively by dynamic contrast enhanced magnetic resonance imaging (DCE-MRI)[1]. A bolus of paramagnetic contrast media is injected as a tracer for the determination of hemodynamic parameters by analyzing the signal variation with respect to time This method enables the determination of tumor specific microvascular parameters such as blood flow, blood volume, mean transit time, and the permeability–surface area product[2]. For quantitative analysis of these perfusion parameters, DCE-MRI combined with either semi quantitative analysis[3], the model free deconvolution algorithm[4] or the Tofts-model[5] has been applied in literature These approaches either do not model the structure of the tissue (deconvolution) or are limited by not directly providing values for plasma flow and mean transit time (Toft’s model). We compared the fast deconvolution approach[4] as a model free method and two different compartment models: the two compartment uptake model (2CU)[13] and the two compartment exchange model (2CX)[14]
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