03 Jun 21. Featured Paper
A comparison of CVR magnitude & delay assessed at 1.5 & 3T in patients with cerebral small vessel disease.
Background: Cerebrovascular reactivity (CVR) measures blood flow change in response to a vasoactive stimulus.
Impairment is associated with several neurological conditions & can be measured using blood oxygen level-dependent (BOLD) magnetic resonance imaging (MRI).
Field strength affects the BOLD signal, but the effect on CVR is unquantified in patient populations.
We assessed subcortical gray (GM) & white matter (WM) differences using Wilcoxon signed rank tests & scatterplots.
Additionally, we explored associations with demographic factors, WM hyperintensity burden, & small vessel disease score.
Results: Eighteen of twenty patients provided usable data.
At 3T vs. 1.5T: mean CVR magnitude showed less variance (WM 3T: 0.062 ± 0.018%/mmHg, range 0.035, 0.093; 1.5T: 0.057 ± 0.024%/mmHg, range 0.016, 0.094) but was not systematically higher (Wilcoxon signal rank tests, WM: r = −0.33, confidence interval (CI): −0.013, 0.003, p = 0.167); delay showed similar variance (WM 3T: 40 ± 12 s, range: 12, 56; 1.5T: 31 ± 13 s, range 6, 50) & was shorter in GM (r = 0.33, CI: −2, 9, p = 0.164) & longer in WM (r = −0.59, CI: −16, −2, p = 0.010).
Patients with higher disease severity tended to have lower CVR at 1.5 & 3T.
Conclusion: Mean CVR magnitude at 3T was similar to 1.5T but showed less variance.
GM/WM delay differences may be affected by low signal-to-noise ratio among other factors.
Although 3T may reduce variance in CVR magnitude, CVR is readily assessable at 1.5T & reveals comparable associations & trends with disease severity.
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Featured paper: A comparison of CVR magnitude & delay assessed at 1.5 & 3T in patients with cerebral small vessel disease.