Moving Toward a Consensus DSC-MRI Protocol: Validation of a Low–Flip Angle Single-Dose Option as a Reference Standard for Brain Tumors

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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. 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-) or provided preload (P+) for an intermediate flipangle = 60°. Compared with 60°/P+/C+, 30°/P-/C+ had closest mean standardized relative CBV, highest Lin concordance correlation coefficient, and lowest Bland-Altman bias.

 

Abstract

BACKGROUND AND PURPOSE

Figure 2. Images and sRCBV parameter maps from a patient with glioblastoma.
Figure 2. Images and sRCBV parameter maps from a patient with glioblastoma.

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 SNR for 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.

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Moving Toward a Consensus DSC-MRI Protocol: Validation of a Low–Flip Angle Single-Dose Option as a Reference Standard for Brain Tumors
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