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Cerebral venous oxygenation (Y v ) is a valuable biomarker for a variety of brain diseases. T 2 relaxation under spin tagging (TRUST) MRI is a widely used method for Y v quantification. In this work, there were two main objectives. The first was to evaluate the reproducibility of TRUST Y v measurements across MRI scanners from different vendors. The second was to examine the correlation between Y v and end-tidal CO 2 (EtCO 2 ) in a multisite, multivendor setting and determine the usefulness of this correlation to account for variations in Y v caused by normal variations and physiological fluctuations. Standardized TRUST pulse sequences were implemented on three scanners from major MRI vendors (GE, Siemens, Philips). These scanners were located at two research institutions. Ten healthy subjects were scanned. On each scanner, the subject underwent two scan sessions, each of which included three TRUST scans, to evaluate the intrasession and intersession reproducibility of Y v . Each scanner was also equipped with a capnograph device to record the EtCO 2 of the subject during the MRI scan. We found no significant bias in Y v measurements across the three scanners (P = 0.18). The measured Y v values on the three scanners were also strongly correlated with each other (intraclass correlation coefficients > 0.85, P < 0.001). The intrasession and intersession coefficients of variation of Y v were less than 4% and showed no significant difference among the scanners. In addition, our results revealed that (1) within the same subject, Y v increased with EtCO 2 at a rate of 1.24 ± 0.17%/mmHg (P < 0.0001), and (2) across different subjects, individuals with a higher EtCO 2 had a higher Y v , at a rate of 0.94 ± 0.36%/mmHg (P = 0.01). These results suggest that (1) the standardized TRUST sequences had similar accuracies and reproducibilities for the quantification of Y v across the scanners, and (2) recording of EtCO 2 may be a useful complement to Y v measurement to account for CO 2 -related physiological fluctuations in Y v in multisite, multivendor studies., (© 2023 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd.)

Objective: Diffusion-weighted magnetic resonance imaging (MRI) has shown increased sensitivity in detecting brain white matter disease compared to traditional T2-weighted MRI. Diffusion-weighted imaging (DWI) can quantitatively assess the microstructural integrity of white matter using the average apparent diffusion coefficient (ADCav), a measure of the extent to which water molecules move freely within tissue. On the basis of numerous studies suggesting white matter disease in bipolar patients, particularly patients with more severe illness, this study aimed to test the utility of DWI in assessing the white matter integrity of bipolar patients with severe illness. Methods: The existing MRI scans of eight bipolar patients and eight age-matched controls with neurological illness were examined retrospectively. ADCav values for pixels within white matter regions of interest (ROIs) were calculated and used to plot ADCav frequency histograms for each ROI. Mean ADCav values for the two groups were then compared by ANCOVA. Results: The bipolar mean ADCav (0.855 ± 0.051 × 10−3 mm2/s) for combined white matter ROIs significantly exceeded that of controls (0.799 ± 0.046 × 10−3 mm2/s), while covarying for age ( F = 4.47, df = 3, p = 0.025). Conclusions: This is the first report of an elevated ADCav in the white matter of a group of patients with bipolar disorder. In this group of patients with severe illness, increased white matter ADCav suggests microstructural changes consistent with decreased white matter integrity. DWI may be an additional, useful tool to assess white matter abnormalities in bipolar disorder. [ABSTRACT FROM AUTHOR]

Elevated plasma neurofilament light chain (NfL) is associated with dementia though underlying mechanisms remain unknown. We examined cross-sectional relationships of time-dependent plasma NfL with selected brain structural magnetic resonance imaging (sMRI) prognostic markers of dementia. The sample was drawn from the Healthy Aging in Neighborhoods of Diversity Across the Life Span (HANDLS) study, selecting participants with complete v 1 (2004–2009) and v 2 (2009–2013) plasma NfL exposure and ancillary sMRI data at v scan (2011–2015, n = 179, mean v 1 to v scan time: 5.4 years). Multivariable-adjusted linear regression models were conducted, overall, by sex, and race, correcting for multiple testing with q-values. NfL (v1) was associated with larger WMLV (both Log e transformed), after 5–6 years' follow-up, overall (β = +2.131 ± 0.660, b = +0.29, p = 0.001, and q = 0.0029) and among females. NfLv 2 was linked to a 125 mm3 lower left hippocampal volume (p = 0.004 and q = 0.015) in reduced models, mainly among males, as was observed for annualized longitudinal change in NfL (δNfL bayes). Among African American adults, NfL v1 was inversely related to total, gray and white matter volumes. Plasma NfL may reflect future brain pathologies in middle-aged adults. [ABSTRACT FROM AUTHOR]