Diaschisis Profiles in the Cerebellar Response to Hemodynamic Stimuli: Insights From Dynamic Measurement of Cerebrovascular Reactivity to Identify Occult and Transient Maxima.

BACKGROUND

Crossed cerebellar diaschisis (CCD) refers to depressions in perfusion and metabolism within the cerebellar hemisphere contralateral to supratentorial disease. Prior investigation into CCD in cerebrovascular reactivity (CVR) has been limited to terminal CVR estimations (CVR ). We recently have demonstrated the presence of unsustained CVR maxima (CVR ) using dynamic CVR analysis, offering a fully dynamic characterization of CVR to hemodynamic stimuli.

PURPOSE

To investigate CCD in CVR from dynamic blood oxygen level-dependent (BOLD) MRI, by comparison with conventional CVR estimation.

STUDY TYPE

Retrospective.

POPULATION

A total of 23 patients (median age: 51 years, 10 females) with unilateral chronic steno-occlusive cerebrovascular disease, without prior knowledge of CCD status.

FIELD STRENGTH/SEQUENCE: A 3-T, T1-weighted magnetization-prepared rapid gradient-echo (MPRAGE) and acetazolamide-augmented BOLD imaging performed with a gradient-echo echo-planar imaging (EPI) sequence.

ASSESSMENT

A custom denoising pipeline was used to generate BOLD-CVR time signals. CVR was established using the last minute of the BOLD response relative to the first-minute baseline. Following classification of healthy versus diseased cerebral hemispheres, CVR and CVR were calculated for bilateral cerebral and cerebellar hemispheres. Three independent observers evaluated all data for the presence of CCD.

STATISTICAL TESTS

Pearson correlations for comparing CVR across hemispheres, two-proportion Z-tests for comparing CCD prevalence, and Wilcoxon signed-rank tests for comparing median CVR. The level of statistical significance was set at P ≤ 0.05.

RESULTS

CCD-related changes were observed on both CVR and CVR maps, with all CCD+ cases identifiable by inspection of either map. Diseased cerebral and contralateral cerebellar hemispheric CVR correlations in CCD+ patients were stronger when using CVR (r = 0.728) as compared to CVR (r = 0.676). CVR correlations between healthy cerebral hemispheres and contralateral cerebellar hemispheres were stronger for CVR (r = 0.739) than for CVR (r = 0.705).

DATA CONCLUSION

CCD-related alterations could be observed in CVR examinations. Conventional CVR may underestimate CVR and could exaggerate CCD.

EVIDENCE LEVEL

TECHNICAL EFFICACY

Stage 3.