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The authors assessed delay and transit time-uncorrected and transit time-corrected CBF maps in 87 healthy controls. Data analysis included voxelwise permutation-based between-sequence comparisons of 3-delay versus 7-delay, within-sequence comparison of transit time-uncorrected versus transit time-corrected maps, and average CBF calculations in regions that have been shown to differ. The 7-delay sequence estimated a higher CBF value than the 3-delay for the transit time-uncorrected and transit time-corrected maps in regions corresponding to the watershed areas. In the peripheral regions of the brain, the estimated delay was found to be longer for the 3-delay sequence while the inverse was found in the center of the brain. This study supports the necessity of standardizing acquisition parameters in multidelay arterial spin-labeling and identifying basic parameters as a confounding factor in CBF quantification studies.

From January 2013 to January 2016, fifty-five consecutive patients with histopathologically proved lymphomas, glioblastomas, and metastases were included in this study after undergoing MR imaging. The perfusion parameters (maximum relative CBV, maximum percentage of signal intensity recovery) and spectroscopic concentration ratios (lactate/Cr, Cho/NAA, Cho/Cr, and lipids/Cr) were analyzed individually and in optimal combinations. The highest differential diagnostic performance was obtained with the following combined classifiers: 1) maximum percentage of signal intensity recovery-Cho/NAA to discriminate lymphomas from glioblastomas and metastases; 2) relative CBV-Cho/NAA to discriminate glioblastomas from lymphomas and metastases; and 3) maximum percentage of signal intensity recovery-lactate/Cr and maximum percentage of signal intensity recovery-Cho/Cr to discriminate metastases from lymphomas and glioblastomas. The authors conclude that spectroscopy yielded an added performance value to perfusion using optimal combined classifiers of these modalities.