Background 4D flow MRI shows great potential in neurovascular disorders such as stenosis, atherosclerotic disease, aneurysms, and vascular malformations. Its widespread application in the neurovascular system requires evidence of good test–retest multicenter reproducibility. Purpose To assess the multicenter reproducibility, test–retest reliability and interobserver dependence of 4D flow MRI in measurements of cerebral blood flow/velocity in main intracranial vessels. Study Type Prospective study. Subjects Ten healthy subjects underwent 4D flow scans at three different centers. All subjects were scanned twice at 2 different days at each center. Field Strength/Sequence 3.0 T; 4D flow sequence. Assessment Multicenter reproducibility, test–retest reliability and interobserver agreement for measurements of the blood flow and peak velocity from five regions of interest were assessed (bilateral internal carotid arteries, bilateral medial cerebral arteries, and sagittal sinus). Statistical Test A Shapiro–Wilks test was conducted to assess normality of measurements in each scan. Coefficient of variances (CVs) was computed to evaluate intra‐ and intersite variances of all measurements. The multicenter reproducibility was assessed by two‐way mixed intraclass correlation coefficient (ICC). A Bland–Altman plot and Pearson correlation were used to evaluate test–retest reliability. ICC was calculated to assess interobserver agreements. Results All P‐values for Shapiro–Wilks tests were greater than 0.05, which indicated the normality of all measurements. Both intra‐ and intersite CVs were lower than 12%. There was good test–retest reliability for both blood flow and peak velocity of all ROIs (r = 0.75–0.94). In addition, high multicenter reproducibility was detected (ICC = 0.77–0.96, all P < 0.001). The results of these measurements also showed great interobserver agreement (all ICC > 0.9 and all P < 0.001). Data Conclusion High multicenter reproducibility and test–retest reliability was shown for 4D flow in the measurements of blood flow and peak velocity of intracranial vessels. In addition, these measurements showed great interobserver agreement. Level of Evidence: 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;49:1543–1552.

Background: The application value of T 2 mapping in evaluating cervical cancer (CC) features remains unclear. Purpose: To investigate the role of T 2 values in evaluating CC classification, grade, and lymphovascular space invasion (LVSI) in comparison to apparent diffusion coefficient (ADC), and to compare synthetic T 2-weighted (T 2 W) images calculated from T 2 values to conventional T 2 W images for CC staging. Study Type: Retrospective. Population: Sixty-three patients with histopathologically confirmed CC. Field Strength/Sequence: 3T, conventional T 2 W turbo spin-echo, diffusion-weighted echo-planar, and accelerated T 2 mapping sequence. Assessment: T 2 and ADC values between different pathological features of CC were compared. The diagnostic accuracies of conventional and synthetic T 2 W images in staging were also compared. Statistical Tests: Parameters were compared using an independent t-test, Wilcoxon signed-rank test, and the chi-square test. Receiver operating characteristic analysis was performed. Results: The T 2 values varied significantly between well/moderately differentiated and poorly differentiated tumors ([92.8 AE 9.5 msec] vs. [83.8 AE 9.5 msec], P < 0.05) and between LVSI-positive and LVSI-negative CC ([82.2 AE 8.2 msec] vs. [93.9 AE 9.1 msec], P < 0.05). The ADC values showed a significant difference for grade ([0.76 AE 0.10 × 10 −3 mm 2 /s] vs. [0.65 AE 0.11 × 10 −3 mm 2 /s], P < 0.05) and no difference for LVSI status ([0.71 AE 0.11× 10 −3 mm 2 /s] vs. [0.73 AE 0.12× 10 −3 mm 2 /s], P = 0.472). There was no significant difference in T 2 and ADC values between squamous cell carcinoma and adenocarcinoma (P = 0.378 and P = 0.661, respectively). In MRI staging, the conventional and synthetic T 2 W images resulted in a similar accuracy (71% vs. 68%, P = 0.698). Data Conclusion: The accelerated T 2 mapping sequence may facilitate grading and staging of CC by providing quantitative T 2 maps and synthetic T 2 W images in one acquisition. T 2 values may be superior to ADC in predicting LVSI. Level of Evidence: 2 Technical Efficacy Stage: 2

Objectives To explore the utility of whole-lesion apparent diffusion coefficient (ADC) histogram analysis for differentiating parotid gland tumors following readout-segmented diffusion-weighted imaging (RESOLVE). Methods 80 patients (40 with pleomorphic adenomas, 14 with Warthin tumors, and 26 with malignant parotid gland tumors) who underwent routine head-and-neck MRI and RESOLVE examinations, were retrospectively evaluated. RESOLVE data were acquired from a MAGNETOM Skyra 3T MR system. Eleven whole-lesion histogram parameters derived from histogram analysis (ADC_mean, ADC_minimum, ADC_maximum, ADC_1th, ADC_10th, ADC_50th, ADC_90th, ADC_99th, skewness, variance and kurtosis) were calculated for each patient using MaZda. Receiver operating characteristic (ROC) curve analysis was used to assess the diagnostic performance of the ADC for distinguishing among the three groups. Results In total, nine parameters (ADC_minimum, ADC_maximum, ADC_mean, ADC_10th, ADC_50th, ADC_90th, ADC_99th, variance, skewness) were statistically significant (all p < 0.05) for all three groups, in the comparison of pleomorphic adenomas to Warthin tumors; the ADC_mean, ADC_50th, and skewness revealed high diagnostic efficiency with areas under the receiver operating characteristic curve of 0.976, 0.970, and 0.970, respectively. In the comparison of pleomorphic adenomas to malignant parotid gland tumors, these nine parameters were also found to be statistically different (all p < 0.05); the ADC_mean, ADC_10th and ADC_50th revealed high diagnostic efficiency with area under the curve of 0.851, 0.866, and 0.841, respectively. However, in the comparison of Warthin tumors to malignant parotid gland tumors, only three parameters (ADC_mean, ADC_50th, skewness) were statistically significant (all p < 0.05). Conclusions Whole-lesion ADC histograms are effective in differentiating common parotid gland tumors.

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Background It is difficult to distinguish between invasive pituitary adenomas (IPAs) and skull base chordomas based on tumor location and clinical manifestations. Purpose To investigate the value of the apparent diffusion coefficient (ADC), T2-weighted (T2W) imaging, and dynamic contrast enhancement (DCE) in differentiating skull base chordomas and IPAs. Material and Methods Data for 21 patients with skull base chordomas and 27 patients with IPAs involving the paranasal sinus were retrospectively reviewed, and all diagnoses were pathologically confirmed. Each patient underwent conventional 3.0 T magnetic resonance imaging (MRI), including, ADC, T2W imaging, and DCE sequences. Regions of interest were drawn in the mass and in normal white matter on ADC maps and T2W imaging. The mean ADC, normal ADC, T2W imaging signal intensity (SI), and relative T2-weighted (rT2W) imaging values were measured. DCE parameters, including types of time signal-intensity curves (TIC), enhancement peak (EP), and maximum contrast enhancement ratio (MCER), were calculated. Differences between skull base chordomas and IPAs were evaluated using the independent samples t-test. Receiver operating characteristic (ROC) curve analyses were also performed. Results When comparing IPAs and chordomas, there were significant differences in mean ADC, normal ADC, rT2W imaging values, TIC, EP, and MCER ( P < 0.01). The areas under curves in the ROC analyses for normal ADC, mean ADC, T2W imaging, rT2W imaging, TIC, EP, and MCER were 1.0, 0.996, 1.0, 0.81, 0.987, and 0.987, respectively. Conclusion ADC, T2W imaging SI, and DCE-related parameters can contribute to the differential diagnosis of skull base chordomas and IPAs.