Combined structural and diffusion tensor imaging detection of ischemic injury in moyamoya disease: relation to disease advancement and cerebral hypoperfusion

Outcome prediction of pediatric moyamoya disease using midterm cerebral blood flow measured between staged anastomoses

PURPOSE

Cognitive outcomes of pediatric moyamoya disease are variable and difficult to predict on the basis of initial neurological signs and examinations. To determine the best early time point for outcome prediction, we retrospectively analyzed the correlation between cognitive outcomes and the cerebrovascular reserve capacity (CRC) measured before, between, and after staged bilateral anastomoses.

METHODS

Twenty-two patients aged 4-15 years were included in this study. CRC was measured before the first hemispheric surgery (preoperative CRC), 1 year after the first surgery (midterm CRC), and 1 year after the surgery on the other side (final CRC). The cognitive outcome was the Pediatric Cerebral Performance Category Scale (PCPCS) grade more than 2 years after the final surgery.

RESULTS

The 17 patients with favorable outcomes (PCPCS grades 1 or 2) showed a preoperative CRC of 4.9% ± 11.2%, which was not better than that of the five patients with unfavorable outcomes (grade 3; 0.3% ± 8.5%, p = 0.5). The 17 patients with favorable outcomes showed a midterm CRC of 23.8% ± 15.3%, which was significantly better than that of the five patients with unfavorable outcomes (-2.5% ± 12.1%, p = 0.004). The difference was much more significant for the final CRC, which was 24.8% ± 13.1% in the patients with favorable outcomes and -11.3% ± 6.7% in those with unfavorable outcomes (p = 0.00004).

CONCLUSION

Cognitive outcomes were first clearly discriminated by the CRC after the first-side unilateral anastomosis, which is the optimal early timing for the prediction of individual prognosis.

Characteristics and Clinical Implication of White Matter Lesions in Patients With Adult Moyamoya Disease

BACKGROUND AND OBJECTIVES

White matter hyperintensities (WMHs) are reportedly increased in moyamoya disease (MMD); however, their clinical importance is not well-established owing to their pathophysiologic heterogeneity by distribution. This study aimed to evaluate the burden and pattern of WMHs and its clinical implications in the MMD trajectory.

METHODS

Adult patients with MMD without significant structural lesions were 1:1 propensity score-matched with healthy controls for sex and vascular risk factors. The total, periventricular, and subcortical WMH volumes were segmented and quantified fully automatically. WMH volumes were detrended by age and compared between the 2 groups. MMD severity based on Suzuki stage and future ischemic events were assessed for their association with WMH volumes.

RESULTS

A total of 161 pairs of patients with MMD and controls were analyzed. MMD significantly correlated with increased total WMH volume (B [standard error], 0.126 [0.030]; p < 0.001), periventricular WMH volume (0.114 [0.027]; p < 0.001), and periventricular-to-subcortical ratio (0.090 [0.034]; p = 0.009). In the MMD subgroup (n = 187), advanced MMD had an independent association with the total WMH volume (0.120 [0.035]; p < 0.001), periventricular WMH volume (0.110 [0.031]; p < 0.001), and periventricular-to-subcortical ratio (0.139 [0.038]; p < 0.001). Periventricular WMH volume (adjusted hazard ratio [95% confidence interval], 5.12 [1.26-20.79]) and periventricular-to-subcortical ratio (3.80 [1.51-9.56]) were associated with future ischemic events in patients with medically followed up MMD. However, no demonstrable association was found between subcortical WMH volume and MMD, MMD severity, or future ischemic events.

DISCUSSION

Periventricular WMHs, but not subcortical WMHs, may represent the main pathophysiology of MMD. Periventricular WMHs may be used as a marker for ischemic vulnerability in patients with MMD.

18F-FDG PET and a classifier algorithm reveal a characteristic glucose metabolic pattern in adult patients with moyamoya disease and vascular cognitive impairment

Vascular cognitive impairment (VCI) is a critical issue in moyamoya disease (MMD). However, the glucose metabolic pattern in these patients is still unknown. This study aimed to identify the metabolic signature of cognitive impairment in patients with MMD using ¹⁸F-2-fluoro-2-deoxy-D-glucose positron emission tomography (¹⁸F-FDG PET) and establish a classifier to identify VCI in patients with MMD. One hundred fifty-two patients with MMD who underwent brain ¹⁸F-FDG PET scans before surgery were enrolled and classified into nonvascular cognitive impairment (non-VCI, n = 52) and vascular cognitive impairment (VCI, n = 100) groups according to neuropsychological test results. Additionally, thirty-three health controls (HCs) were also enrolled. Compared to HCs, patients in the VCI group exhibited extensive hypometabolism in the bilateral frontal and cingulate regions and hypermetabolism in the bilateral cerebellum, while patients in the non-VCI group showed hypermetabolism only in the cerebellum and slight hypometabolism in the frontal and temporal regions. In addition, we found that the patients in the VCI group showed hypometabolism mainly in the left basal ganglia compared to those in the non-VCI group. The sparse representation-based classifier algorithm taking the SUVr of 116 Anatomical Automatic Labeling (AAL) areas as features distinguished patients in the VCI and non-VCI groups with an accuracy of 82.4%. This study demonstrated a characteristic metabolic pattern that can distinguish patients with MMD without VCI from those with VCI, namely, hypometabolic lesions in the left hemisphere played a more important role in cognitive decline in patients with MMD.

Thalamic structure and anastomosis in different hemispheres of moyamoya disease

Objective

The progression of the asymptomatic hemisphere of moyamoya disease (MMD) is largely unknown. In this study, we investigated the differences in subcortical gray matter structure and angiographic features between asymptomatic and symptomatic hemispheres in patients with MMD.

Methods

We retrospectively reviewed patients with MMD in consecutive cases in our center. We compared subcortical gray matter volume and three types of collaterals (lenticulostriate anastomosis, thalamic anastomosis, and choroidal anastomosis) between symptomatic and asymptomatic hemispheres. Symptomatic hemispheres were classified as ischemic hemisphere (i-hemisphere) and hemorrhagic hemisphere (h-hemisphere). Asymptomatic hemispheres were classified as contralateral asymptomatic hemisphere of i-hemisphere (ai-hemisphere), contralateral asymptomatic hemisphere of h-hemisphere (ah-hemisphere), bilateral asymptomatic hemispheres in asymptomatic group (aa-hemisphere).

Results

A total of 117 MMD patients were reviewed, and 49 of them met the inclusion criteria, with 98 hemispheres being analyzed. The thalamic volume was found to differ significantly between the i- and ai-hemispheres (P = 0.010), between the i- and ah-hemispheres (P = 0.004), as well as between the h- and ai-hemispheres (P = 0.002), between the h- and ah-hemispheres (P < 0.001). There was a higher incidence of thalamic anastomosis in the ai-hemispheres than i-hemispheres (31.3% vs. 6.3%, P = 0.070), and in the ah-hemispheres than h-hemispheres (29.6% vs. 11.1%, P = 0.088). Additionally, the hemispheres with thalamic anastomosis had a significantly greater volume than those without thalamic anastomosis (P = 0.024). Univariate and multivariate logistic regression analysis showed that thalamic volume was closely associated with thalamic anastomosis.

Conclusion

The thalamic volume and the incidence of thalamic anastomosis increase in asymptomatic hemispheres and decrease in symptomatic hemispheres. Combining these two characteristics may be helpful in assessing the risk of stroke in the asymptomatic hemispheres of MMD as well as understanding the pathological evolution of the disease.

Abnormal brain functional and structural connectivity between the left supplementary motor area and inferior frontal gyrus in moyamoya disease

BACKGROUND

Disruption of brain functional connectivity has been detected after stroke, but whether it also occurs in moyamoya disease (MMD) is unknown. Impaired functional connectivity is always correlated with abnormal white matter fibers. Herein, we used multimodal imaging techniques to explore the changes in brain functional and structural connectivity in MMD patients.

METHODS

We collected structural images, resting-state functional magnetic resonance imaging (rs-fMRI) and diffusion tensor imaging for each subject. Cognitive functions of MMD patients were evaluated using the Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), and Trail Making Test parts A and B (TMT-A/-B). We calculated the functional connectivity for every paired region using 90 regions of interest from the Anatomical Automatic Labeling Atlas and then determined the differences between MMD patients and HCs. We extracted the functional connectivity of paired brain regions with significant differences between the two groups. Correlation analyses were then performed between the functional connectivity and variable cognitive functions. To explore whether the impaired functional connectivity and cognitive performances were attributed to the destruction of white matter fibers, we further analyzed fiber integrity using tractography between paired regions that were correlated with cognition.

RESULTS

There was lower functional connectivity in MMD patients as compared to HCs between the bilateral inferior frontal gyrus, between the bilateral supramarginal gyrus, between the left supplementary motor area (SMA) and the left orbital part of the inferior frontal gyrus (IFGorb), and between the left SMA and the left middle temporal gyrus (P < 0.01, FDR corrected). The decreased functional connectivity between the left SMA and the left IFGorb was significantly correlated with the MMSE (r = 0.52, P = 0.024), MoCA (r = 0.60, P = 0.006), and TMT-B (r = -0.54, P = 0.048) in MMD patients. White matter fibers were also injured between the SMA and IFGorb in the left hemisphere and were positively correlated with reduced functional connectivity.

CONCLUSIONS

Brain functional and structural connectivity between the supplementary motor area and inferior frontal gyrus in the left hemisphere are damaged in MMD. These findings could be useful in the evaluation of disease progression and prognosis of MMD.

Moyamoya Disease With Initial Ischemic or Hemorrhagic Attack Shows Different Brain Structural and Functional Features: A Pilot Study

Objective

Cerebral ischemia and intracranial hemorrhage are the two main phenotypes of moyamoya disease (MMD). However, the pathophysiological processes of these two MMD phenotypes are still largely unknown. Here, we aimed to use multimodal neuroimaging techniques to explore the brain structural and functional differences between the two MMD subtypes.

Methods

We included 12 patients with ischemic MMD, 10 patients with hemorrhagic MMD, and 10 healthy controls (HCs). Each patient underwent MRI scans and cognitive assessment. The cortical thickness of two MMD subtypes and HC group were compared. Arterial spin labeling (ASL) and diffusion tensor imaging (DTI) were used to inspect the cerebral blood flow (CBF) of cortical regions and the integrity of related white matter fibers, respectively. Correlation analyses were then performed among the MRI metrics and cognitive function scores.

Results

We found that only the cortical thickness in the right middle temporal gyrus (MTG) of hemorrhagic MMD was significantly greater than both ischemic MMD and HC (p < 0.05). In addition, the right MTG showed higher ASL-CBF, and its associated fiber tract (arcuate fasciculus, AF) exhibited higher fractional anisotropy (FA) values in hemorrhagic MMD. Furthermore, the cortical thickness of the right MTG was positively correlated with its ASL-CBF values (r = 0.37, p = 0.046) and the FA values of right AF (r = 0.67, p < 0.001). At last, the FA values of right AF were found to be significantly correlated with cognitive performances within patients with MMD.

Conclusions

Hemorrhagic MMD shows increased cortical thickness on the right MTG in comparison with ischemic MMD and HCs. The increased cortical thickness is associated with the higher CBF values and the increased integrity of the right AF. These findings are important to understand the clinical symptoms and pathophysiology of MMD and further applied to clinical practice.

Progression in Moyamoya Disease: Clinical Feature, Neuroimaging Evaluation and Treatment

Moyamoya disease (MMD) is a chronic cerebrovascular disease characterized by progressive stenosis of the arteries of the circle of Willis, with the formation of collateral vascular network at the base of the brain. Its clinical manifestations are complicated. Numerous studies have attempted to clarify the clinical features of MMD, including its epidemiology, genetic characteristics, and pathophysiology. With the development of neuroimaging techniques, various neuroimaging modalities with different advantages have deepened the understanding of MMD in terms of structural, functional, spatial, and temporal dimensions. At present, the main treatment for MMD focuses on neurological protection, cerebral blood flow reconstruction, and neurological rehabilitation, such as pharmacological treatment, surgical revascularization, and cognitive rehabilitation. In this review, we discuss recent progress in understanding the clinical features, in the neuroimaging evaluation and treatment of MMD.

Faded Critical Dynamics in Adult Moyamoya Disease Revealed by EEG and fMRI

Criticality is considered a dynamic signature of healthy brain activity that can be measured on the short-term timescale with neural avalanches and long-term timescale with long-range temporal correlation (LRTC). It is unclear how the brain dynamics change in adult moyamoya disease (MMD). We used BOLD-fMRI for LRTC analysis from 16 hemorrhagic (H_MMD) and 34 ischemic (I_MMD) patients and 25 healthy controls. Afterwards, they were examined by EEG recordings in the eyes-closed (EC), eyes-open (EO), and working memory (WM) states. The EEG data of 11 H_MMD and 13 I_MMD patients and 21 healthy controls were in good quality for analysis. Regarding the 4 metrics of neural avalanches (e.g., size (α), duration (β), κ value, and branching parameter (σ)), both MMD subtypes exhibited subcritical states in the EC state. When switching to the WM state, H_MMD remained inactive, while I_MMD surpassed controls and became supercritical (p < 0.05). Regarding LRTC, the amplitude envelope in the EC state was more analogous to random noise in the MMD patients than in controls. During state transitions, LRTC decreased sharply in the controls but remained chaotic in the MMD individuals (p < 0.05). The spatial LRTC reduction distribution based on both EEG and fMRI in the EC state implied that, compared with controls, the two MMD subtypes might exhibit mutually independent but partially overlapping patterns. The regions showing decreased LRTC in both EEG and fMRI were the left supplemental motor area of H_MMD and right pre-/postcentral gyrus and right inferior temporal gyrus of I_MMD. This study not only sheds light on the decayed critical dynamics of MMD in both the resting and task states for the first time but also proposes several EEG and fMRI features to identify its two subtypes.

Preliminary Study on the Application of Ultrahigh Field Magnetic Resonance in Moyamoya Disease

Magnetic resonance imaging (MRI) is widely used for the evaluation of moyamoya disease (MMD). In this paper, we describe the features of time-of-flight magnetic resonance angiography (TOF-MRA) and susceptibility-weighted imaging (SWI) at 7 T in a series of MMD patients. In this prospective pilot study, 7 patients (median age: 45.6 years; range: 30-52 years) with MMD and no contraindications for MRI underwent T2-weighted, SWI, and TOF-MRA sequences using a research 7 T head-only scanner. We show that such sequences at ultrahigh field (UHF) represent new and valuable approaches to unravel and characterize MMD. While SWI reveals more remarkable imaging signs related to an improved magnitude and phase contrast imaging, the collateral network pathways in MMD could be excellently delineated using 7 T TOF-MRA. In particular, using SWI and MRA fusion images in UHF MRI helps to improve the detection of bleeding points in hemorrhagic MMD. Our findings indicate that ultrahigh field MRI is very promising to access the severity of the disease and may facilitate revascularization surgery of MMD patients.