Crossed cerebellar diaschisis on 18F-FDG PET: Frequency across neurodegenerative syndromes and association with 11C-PIB and 18F-Flortaucipir

We used 18F-FDG-PET to investigate the frequency of crossed cerebellar diaschisis (CCD) in 197 patients with various syndromes associated with neurodegenerative diseases. In a subset of 117 patients, we studied relationships between CCD and cortical asymmetry of Alzheimer’s pathology (β-amyloid (11C-PIB) and tau (18F-Flortaucipir)). PET images were processed using MRIs to derive parametric SUVR images and define regions of interest. Indices of asymmetry were calculated in the cerebral cortex, basal ganglia and cerebellar cortex. Across all patients, cerebellar 18F-FDG asymmetry was associated with reverse asymmetry of 18F-FDG in the cerebral cortex (especially frontal and parietal areas) and basal ganglia. Based on our operational definition (cerebellar asymmetry >3% with contralateral supratentorial hypometabolism), significant CCD was present in 47/197 (24%) patients and was most frequent in corticobasal syndrome and semantic and logopenic variants of primary progressive aphasia. In β-amyloid-positive patients, mediation analyses showed that 18F-Flortaucipir cortical asymmetry was associated with cerebellar 18F-FDG asymmetry, but that cortical 18F-FDG asymmetry mediated this relationship. Analysis of 18F-FDG-SUVR values suggested that CCD might also occur in the absence of frank cerebellar 18F-FDG asymmetry due to symmetrical supratentorial degeneration resulting in a bilateral diaschisis process.

Crossed cerebellar diaschisis after stroke detected noninvasively by arterial spin-labeling MR imaging

Background As a noninvasive perfusion-weighted MRI technique, arterial spin-labeling (ASL) was becoming increasingly used to evaluate cerebral hemodynamics in many studies. The relation between ASL-MRI and crossed cerebellar diaschisis (CCD) was rarely discussed. In this study, the aim of our study was to assess the performance of ASL-MRI in the detection of crossed cerebellar diaschisis after stroke in compared with single-photon emission CT (SPECT). Results 17 of 51(33.3%) patients revealed CCD phenomenon by the SPECT method. In CCD-positive group, CBFASL of ipsilateral cerebellar were significantly increased compared with contralateral cerebellar (p < 0.0001) while no significant differences (p = 0.063, > 0.001) in the CCD-negative group. Positive correlation was detected between admission National institute of health stroke scale (NIHSS) and asymmetry index of SPECT (AISPECT) (r = 0.351, p = 0.011), AIASL (r = 0.372, p = 0.007); infract volume and AISPECT (r = 0.443, p = 0.001), AIASL (r = 0.426, p = 0.002). Significant correlation was also found between cerebral blood flow of SPECT (CBFSPECT) and CBFASL, AISPECT and AIASL (r = 0.204, p = 0.04; r = 0.467, p = 0.001, respectively). Furthermore, the area under the receiver operating characteristic (ROC) curve value of AIASL was 0.829. Conclusions CBF derived from ASL-MRI could be valuable for assessment of CCD in supratentorial stroke patients. Additionally, CCD was significantly associated with larger ischemic volume and higher initial NIHSS score.

Crossed Cerebellar Diaschisis: Risk Factors and Prognostic Value in Medically Intractable Epilepsy by 18F-FDG PET/CT

Purpose Crossed cerebellar diaschisis (CCD) has been widely studied in hemispheric stroke but is less characterized in epilepsy. In this study, we used 18F-FDG positron emission tomography (PET)/computed tomography (CT) to investigate the risk factors for CCD and its prognostic value for intractable epilepsy. Methods One hundred medically intractable epilepsy patients pathologically diagnosed with focal cortical dysplasia (FCD) postoperatively were included and classified into two groups: CCD+ and CCD-. All patients underwent 18F-FDG PET/CT preoperatively. PET/CT images were analysed qualitatively by visual assessment and semi-quantitatively using the absolute asymmetry index (|AI|). Clinical factors, including age, sex, body mass index (BMI), age at seizure onset, epilepsy duration, seizure type, epilepsy severity, electroencephalography(EEG) and brain magnetic resonance imaging (MRI), were retrospectively assessed from medical records. Follow-up outcomes were evaluated according to the Engel classification at 3, 6, 12, 24 and 36 months postoperatively.Results Of the 100 patients, 77 (77%) were classified as CCD-, and 23 (23%) were classified as CCD+. CCD+ patients had a higher number of lobes involved on PET (3.61±2.16 vs 2.26±1.01, P<0.001) and more cases of occipital hypometabolism (21.74% vs 5.19%, P=0.03) than CCD- patients. CCD- patients showed more negative MRI results than CCD+ patients (P=0.02). Patients with a poor prognosis had more cases of parietal hypometabolism on PET (P=0.02). At 12 months postoperatively, 71%(29/41) of CCD- patients and 31%(4/13) of CCD+ patients presented a favourable prognosis (P=0.02). Significant differences in the average |AI| values in the posterior frontal and anterior temporal lobes were found between CCD+ and CCD- patients (P<0.05), but no significant correlation of the |AI| between supratentorial regions and the contralateral cerebellum was identified in CCD+ patients. Conclusion The number of lobes involved on PET, structural anomalies on MRI, the lesion location on PET, the |AI| values in the posterior frontal and anterior temporal lobes may be predisposing factors for CCD. CCD occurrence may help predict the prognosis of FCD patients at 12 months postoperatively, and parietal hypometabolism on PET may indicate a poor prognosis.