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Background: Amide proton transfer (APT) imaging is a chemical exchange saturation transfer (CEST) technique offering potential clinical applications such as diagnosis, characterization, and treatment planning and monitoring in glioma patients. While APT-CEST has demonstrated high potential, reproducibility remains underexplored. Purpose: To investigate whether cerebral APT-CEST with clinically feasible scan time is reproducible in healthy tissue and glioma for clinical use at 3 T. Study Type: Prospective, longitudinal. Subjects: Twenty-one healthy volunteers (11 females; mean age ± SD: 39 ± 11 years) and 6 glioma patients (3 females; 50 ± 17 years: 4 glioblastomas, 1 oligodendroglioma, 1 radiologically suspected low-grade glioma). Field Strength/Sequence: 3 T, Turbo Spin Echo - ampling perfection with application optimized contrasts using different flip angle evolution - chemical exchange saturation transfer (TSE SPACE-CEST). Assessment: APT-CEST measurement reproducibility was assessed within-session (glioma patients, scan session 1; healthy volunteers scan sessions 1, 2, and 3), between-sessions (healthy volunteers scan sessions 1 and 2), and between-days (healthy volunteers, scan sessions 1 and 3). The mean APT CEST values and standard deviation of the within-subject difference (SD diff) were calculated in whole tumor enclosed by regions of interest (ROIs) in patients, and eight ROIs in healthy volunteers—whole-brain, cortical gray matter, putamen, thalami, orbitofrontal gyri, occipital lobes, central brain—and compared. Statistical Tests: Brown-Forsythe tests and variance component analysis (VCA) were used to assess the reproducibility of ROIs for the three time intervals. Significance was set at P < 0.003 after Bonferroni correction. Results: Intratumoral mean APT CEST was significantly higher than APT CEST in healthy-appearing tissue in patients (0.5 ± 0.46%). The average within-session, between-sessions, and between-days SD diff of healthy control brains was 0.2% and did not differ significantly with each other (0.76 > P > 0.22). The within-session SD diff of whole-brain was 0.2% in both healthy volunteers and patients, and 0.21% in the segmented tumor. VCA showed that within-session factors were the most important (60%) for scanning variance. Data Conclusion: Cerebral APT-CEST imaging may show good scan–rescan reproducibility in healthy tissue and tumors with clinically feasible scan times at 3 T. Short-term measurement effects may be the dominant components for reproducibility. Level of Evidence: 2. Technical Efficacy: Stage 2.

Background Each ultrafast dynamic contrast-enhanced (DCE) MRI sequence for breast cancer generates thousands of images in a 4D stack that need to be reviewed by a radiologist. Purpose To assess whether color intensity projections (CIP) effectively summarizes-using only the time of arrival (ToA) and amount of signal enhancement (AoE) of the contrast agent-the thousands of ultrafast images. Study type Retrospective cohort clinical trial. Subjects The study included 89 patients who had been scanned with an MRI beast protocol, of which 26 had breast cancer and 63 did not. Field strength/sequence The 115-second ultrafast DCE sequence at 3T acquired 19 consecutive frames every 4.26 seconds with 152 slices per frame, yielding a 4D stack with 2888 2D images for each of water and fat. Assessment For each slice of the water 4D stack a single CIP image was generated that encoded the ToA in the hue (red, orange, yellow, green, cyan, blue) and AoE in the brightness. Each of three experienced radiologists assigned a Breast Imaging and Reporting Data System (BI-RADS) score for each patient, first using only the CIP images, and subsequently using both CIP and the full 4D stack. Statistical tests The one-sided Fisher's exact test was used to determine statistical significance of both the sensitivity and specificity between the CIP alone and the CIP plus 4D stack. Results All malignancies were detected using only CIP by at least one of the radiologists. The CIP and CIP+4D sensitivities for reader 1 were 96% and 96% (P = 0.57), specificities were 59% and 65% (P = 0.29). For reader 2, the values were 96% and 100% (P = 0.51) with 62% and 71% (P = 0.17). For reader 3 the values were 92% and 96% (P = 0.50) with 51% and 62% (P = 0.07). Data conclusion With a 95% sensitivity, CIP provides an effective summary of ultrafast DCE images of breast cancer. Level of evidence 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:1391-1399.

Purpose To compare cerebral blood flow (CBF) values measured using magnetic resonance imaging (MRI) arterial spin labeling (ASL) with those obtained with [15O]H2O positron emission tomography (PET), the gold standard for measuring CBF in vivo. Materials and Methods Data were collected in 11 healthy men and in 20 age- and body mass index (BMI)-matched type 1 diabetic men. Pseudo-continuous ASL (PCASL) data were acquired at 3 T and [15O]H2O PET scans were acquired using a high-resolution PET scanner. Input functions were obtained using on-line arterial blood sampling. Whole brain and regional CBF values were compared. Results For both modalities, whole brain CBF was similar in both subject groups. In groups combined, average whole brain CBF was 0.30 ± 0.05 mL·cm−3·min−1 for [15O]H2O PET and 0.34 ± 0.05 mL·cm−3·min−1 for ASL MRI (P < 0.01). A significant correlation between methods was observed for whole brain, gray and white matter. In 12 out of 33 brain regions a significant difference between methods was observed. Conclusion PCASL provides CBF values that correlate with [15O]H2O PET-derived values, but is less accurate. PCASL may be an attractive alternative when absolute quantification is not needed.J. Magn. Reson. Imaging 2014;40:1300–1309. © 2013 Wiley Periodicals, Inc.

Purpose: To test whether a 3D imaging sequence with phase contrast (PC) velocity encoding based on steady-state free precession (SSFP) improves 3D velocity quantification in the heart compared to the currently available gradient echo (GE) approach. Materials and Methods: The 3D PC-SSFP sequence with 1D velocity encoding was compared at the mitral valve in 12 healthy subjects with 3D PC-GE at 1.5T. Velocity measurements, velocity-to-noise-ratio efficiency (VNReff), intra- and interobserver variability of area and velocity measurements, contrast-to-noise-ratio (CNR), and artifact sensitivity were evaluated in both long- and short-axis orientation. Results: Descending aorta mean and peak velocities correlated well (r2 = 0.79 and 0.93) between 3D PC-SSFP and 3D PC-GE. At the mitral valve, mean velocity correlation was moderate (r2 = 0.70 short axis, 0.56 long axis) and peak velocity showed good correlation (r2 = 0.94 short axis, 0.81 long axis). In some cases VNReff was higher, in others lesser, depending on slab orientation and cardiac phase. Intra- and interobserver variability was generally better for 3D PC-SSFP. CNR improved significantly, especially at end systole. Artifact levels did not increase. Conclusion: 3D SSFP velocity quantification was successfully tested in the heart. Blood-myocardium contrast improved significantly, resulting in more reproducible velocity measurements for 3D PC-SSFP at 1.5T. J. Magn. Reson. Imaging 2009;30:947–955. © 2009 Wiley-Liss, Inc.

A tracking algorithm was developed for calculation of three-dimensional point-specific myocardial motion. The algorithm was designed for images acquired with simultaneous magnetic resonance imaging (MRI) grid tagging and through-plane velocity quantification. The tagging grid provided the in- plane motion while the velocity quantification measured the through-plane motion. In four healthy volunteers, the in vivo performance was evaluated by comparing the systolic through-plane displacement with the displacement of tagging-grid intersections in long-axis images. The correlation coefficient was 0.93 (P < 0.001, N = 183). A t-test for paired samples revealed a small underestimation of the through-plane displacement by 0.04 ± 0.09 cm (mean ± SD, P < 0.001) on an average displacement of 0.77 ± 0.23 cm toward the apex. The authors conclude that three-dimensional point-specific motion tracking based on simultaneous tagging and velocity quantification is competitive with other methods such as tagging in mutually orthogonal image planes or quantification of three orthogonal velocity components.