Temporal resolution improvement of calibration-free dynamic contrast-enhanced MRI with compressed sensing optimized turbo spin echo: The effects of replacing turbo factor with compressed sensing accelerations

Abstract

Purpose: To enhance the temporal resolution of calibration-free dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) by implementing compressed sensing assisted turbo spin echo (CS-TSE) acquisition. Materials and Methods: The dynamic sparse sampling variables including acceleration factor, randomized phase encoding distributions, and reconstruction constraints were retrospectively optimized by minimizing the difference from fully sampled dynamic TSE at 7T. The degree of contrast enhancement and the calibration-free quantification of gadolinium (Gd) concentration were evaluated among fast low-angle shot (FLASH), TSE, and CS-TSE acquisitions with multiple phantoms (0.1-6mM). The kidney-feeding in vivo arterial input function (AIF) was measured at multiple administration doses (0.1-0.3 mmol/kg) to evaluate the benefit of CS-TSE for quantifying rapidly changing high Gd concentrations in C57BL/6 mice (n=22). Results: In phantom studies, both calibration-free and calibrated conversions estimated equivalent Gd concentrations for CS-TSE (scatterplot slope=0.9801, r2=0.9998, P < 0.001). In in vivo studies, 4-fold higher temporal resolution (0.96 sec) of CS-TSE over the corresponding TSE enabled robust measurement of AIF first-pass peak and resulting peak enhancement with CS-TSE were observed, with 1.1439- and 2.1258-fold times higher than those with TSE and FLASH acquisitions, respectively, at the 0.1 mmol/kg dose. Calibration-free estimates of AIF peak concentration with CS-TSE were in good agreement with the calibrated approach at multiple administration doses (scatterplot slope=0.7800, r2=0.8014, P < 0.001). Conclusion: Temporal resolution-improved CS-TSE provides practical subsecond (0.96s) calibration-free dynamic MR quantification of high Gd concentration. J. Magn. Reson. Imaging 2015.