Cerebral MR oximetry during acetazolamide augmentation: Beyond cerebrovascular reactivity in hemodynamic failure. Issue 1 (3rd November 2018)

• Record Type: Journal Article
• Authors: Leatherday, Christopher; Dehkharghani, Seena; Nahab, Fadi; Allen, Jason W.; Wu, Junjie; Hu, Ranliang; Qiu, Deqiang
• Is Part Of: Journal of magnetic resonance imaging. Volume 50:Issue 1(2019)
• Page Start: 175
• Page End: 182
• Publication Date: 2018-11-03
• Subjects: acetazolamide -- CVR -- oximetry -- QSM -- stroke; Magnetic resonance imaging -- Periodicals; 616
• DOI: 10.1002/jmri.26546
• Languages: English
• ISSNs: 1053-1807

Abstract

Abstract : Background: Oxygen extraction fraction (OEF) elevation predicts increased ischemic stroke incidence among patients with carotid steno‐occlusive disease, and can be estimated from quantitative susceptibility mapping (QSM) MRI. Purpose: To explore QSM oximetry during acetazolamide (ACZ) challenge, hypothesizing that detectable OEF alterations will reflect hemodynamic compromise in unilateral cerebrovascular disease (CVD) patients. Study Type: Retrospective. Subjects: Fourteen unilateral CVD patients, and 24 healthy controls (HC). Field Strength/Sequence: Multiecho gradient echo (GRE) and T1 ‐weighted images at 3T. Assessment: We constructed QSM images and R2* maps from multiecho GRE images. QSM‐OEF maps were generated from the susceptibility difference between venous blood and background brain tissue. Intrasubject diseased/contralateral hemisphere OEF ratios in the middle cerebral artery (MCA) territories were calculated. Intravascular susceptibility in the straight sinus (SS) and MCA was also measured. Statistical Tests: The result significance was determined using t ‐tests and Pearson's correlation. Results: Mean and standard deviation for the patient diseased/contralateral OEF ratios were 1.15 ± 0.14 at baseline and 1.23 ± 0.17 post‐ACZ. Disease group R2* ratios were 0.95 ± 0.05 at baseline and 1.03 ± 0.08 post‐ACZ. Left/right OEF and R2* ratios for the HC group were 0.98 ± 0.06 and 0.99 ± 0.038, respectively. Susceptibility (ppb) in the SS and MCA in patients was 162.63 ± 35.4 and –22.33 ± 13.70, respectively, at baseline, 124.56 ± 37.43 and –19.27 ± 23.14 post‐ACZ. The HC group SS and MCA susceptibility was 146.10 ± 24.79 and –19.59 ± 12.37, respectively. Patient group OEF ratios were greater than 1.0 before and after ACZ challenge ( P < 0.01 and < 0.001, respectively, one‐sample t ‐test), and were greater than HC ratios ( P < 0.001 unpaired t ‐test). OEF and R2* ratios increased from baseline to post‐ACZ ( P = 0.024, 0.004, respectively, paired t ‐test). Detectable blood oxygenation change was confirmed by finding SS susceptibility decreased from baseline to post‐ACZ ( P < 0.001, paired t ‐test), while MCA susceptibility did not change significantly ( P = 0.67, paired t ‐test). Data Conclusion: These results suggest QSM is sensitive to dynamic OEF modulation during hemodynamic augmentation. Level of Evidence: 3 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2019;50:175–182.