Moving toward a consensus DSC-MRI protocol: Validation of a low-flip angle single-dose option as a reference standard for brain tumors

Abstract

BACKGROUND AND PURPOSE: DSC-MR imaging using preload, intermediate (60°) flip angle and postprocessing leakage correction has gained traction as a standard methodology. Simulations suggest that DSC-MR imaging with flip angle = 30° and no preload yields relative CBV practically equivalent to the reference standard. This study tested this hypothesis in vivo. MATERIALS AND METHODS: Eighty-four patients with brain lesions were enrolled in this 3-institution study. Forty-three patients satisfied the inclusion criteria. DSC-MR imaging (3T, single-dose gadobutrol, gradient recalled-echo-EPI, TE = 20-35 ms, TR = 1.2-1.63 seconds) was performed twice for each patient, with flip angle = 30°-35° and no preload (P -), which provided preload (P+) for the subsequent intermediate flip angle = 60°. Normalized relative CBV and standardized relative CBV maps were generated, including postprocessing with contrast agent leakage correction (C+) and without (C -) contrast agent leakage correction. Contrast-enhancing lesion volume, mean relative CBV, and contrast-to-noise ratio obtained with 30°/P - /C -, 30°/P - /C +, and 60°/P+/C - were compared with 60°/P+/C + using the Lin concordance correlation coefficient and Bland-Altman analysis. Equivalence between the 30°/P - /C+ and 60°/P+/C + protocols and the temporal SNRfor the 30°/P - and 60°/P+ DSC-MR imaging data was also determined. RESULTS: Compared with 60°/P+/C+, 30°/P - /C+ had closest mean standardized relative CBV (P =.61), highest Lin concordance correlation coefficient (0.96), and lowest Bland-Altman bias (μ = 1.89), compared with 30°/P - /C - (P =.02, Lin concordance correlation coefficient = 0.59, μ = 14.6) and 60°/P+/C - (P =.03, Lin concordance correlation coefficient = 0.88, μ = - 10.1) with no statistical difference in contrast-to-noise ratios across protocols. The normalized relative CBV and standardized relative CBV were statistically equivalent at the 10% level using either the 30°/P - /C+ or 60°/P+/C+ protocols. Temporal SNR was not significantly different for 30°/P - and 60°/P+ (P =.06). CONCLUSIONS: Tumor relative CBV derived from low-flip angle, no-preload DSC-MR imaging with leakage correction is an attractive single-dose alternative to the higher dose reference standard.