Decreased 18F-Fluorodeoxyglucose Uptake in Lumbar Vertebrae of Stroke Patients

Imaging increased metabolism in the spinal cord in mice after middle cerebral artery occlusion

Emerging evidence indicates crosstalk between the brain and hematopoietic system following cerebral ischemia. Here, we investigated metabolism and oxygenation in the spleen and spinal cord in a transient middle cerebral artery occlusion (tMCAO) model. Sham-operated and tMCAO mice underwent [18F]fluorodeoxyglucose (FDG)-positron emission tomography (PET) to assess glucose metabolism. Naïve, sham-operated and tMCAO mice underwent multispectral optoacoustic tomography (MSOT) assisted by quantitative model-based reconstruction and unmixing algorithms for accurate mapping of oxygenation patterns in peripheral tissues at 24 h after reperfusion. We found increased [18F]FDG uptake and reduced MSOT oxygen saturation, indicating hypoxia in the thoracic spinal cord of tMCAO mice compared with sham-operated mice but not in the spleen. Reduced spleen size was observed in tMCAO mice compared with sham-operated mice ex vivo. tMCAO led to an increase in the numbers of mature T cells in femoral bone marrow tissues, concomitant with a stark reduction in these cell subsets in the spleen and peripheral blood. The combination of quantitative PET and MSOT thus enabled observation of hypoxia and increased metabolic activity in the spinal cord of tMCAO mice at 24 h after occlusion compared to sham-operated mice.

Impact of Metabolic Activity of Vertebra and Amygdala on Stroke Recurrence: A Prospective Cohort Study

BACKGROUND

Elevated metabolic activity of amygdala is known to be related to atherosclerotic cardiovascular event by increasing inflammatory cell production from bone marrow. We tried to identify the factors of metabolic activity in the amygdala, vertebrae, liver, spleen, and internal carotid artery related to the future vascular events after stroke.

METHODS

A total of 110 patients with acute stroke were included (72±10 years of age, 39% women) and underwent whole-body ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography between August 1, 2015 and February 28, 2020. We compared the FDG uptake in the amygdala, vertebrae, liver, spleen, and internal carotid artery between patients with and without recurrent vascular event. Cox proportional hazards model was used to identify factors related to recurrent stroke and vascular event.

RESULTS

During the median follow-up period of 18 months, 22 patients experienced vascular events, including 15 stroke recurrence. Patients with recurred vascular event had a significantly higher FDG uptake in the amygdala and vertebrae than those without. The Cox proportional hazard model including diabetes, renal function, and carotid stenosis showed that a higher FDG uptake in the amygdala was independently associated with total vascular events (hazard ratio, 3.11 [95% CI, 1.11-8.70]) and higher FDG uptake in the vertebrae with stroke recurrence (hazard ratio, 4.94 [95% CI, 1.29-18.9]).

CONCLUSIONS

The increased metabolic activities of the vertebrae and amygdala are related to future vascular event among stroke survivors.

The uptake pattern of 18F-sodium fluoride radioligand in brain tissue after cerebral infarction

Positron emission tomography with ¹⁸F-sodium fluoride (NaF) radioligand has been actively investigated in atherosclerosis research because it is known to detect microcalcification activity within atheroma. We studied whether NaF shows any uptake in the brain tissue of patients with acute ischemic stroke. This is a post-hoc analysis of previously reported cerebral atherosclerosis research with positron emission tomography which applied the two radioligands, ¹⁸F-fluorodeoxyglucose and NaF for the detection of culprit atheroma among 20 acute cerebral infarction patients (mean age = 75.1 ± 9.0 years; 10 women). In this study, we measured the maximum and mean standardized uptake value (SUVmax and SUVmean) of NaF uptake level in the cerebral infarct region between lesions with and without diffusion weighted image (DWI) positivity, indicating acute ischemic cell death. Correlation analysis was performed between NaF uptake levels and imaging and clinical variables, including neurological severity. The NaF uptake levels were significantly higher in DWI positive lesions than in negative lesions (SUVmax: 2.0 [0.60-4.2] versus 0.20 [0.10-0.40], p = 0.021 by Mann-Whitney U test). The intensity of NaF uptake (SUVmax) was significantly correlated with the initial neurological severity (Spearman's ρ = 0.579, p= 0.007) and white blood cell count (Spearman's ρ = 0.626, p p 0.003). During ischemic stroke NaF was concentrated in brain tissue undergoing acute cell death and its uptake intensity was correlated with neurological severity, suggesting that NaF could reflect acute ischemic cell death after stroke.