Research Of Cortical Thickness And Changes Of Hemodynamic Response In Patients With Moyamoya Disease

Objective: Moyamoya disease(MMD) is characterized by spontaneous and progressive stenosis or occlusion of the internal carotid artery and its proximal branches. This disorder, predominantly common in East Asia, presents with repeated transient ischemic attacks(TIA), strokes, intracranial hemorrhage, headaches and seizures. Cortical thickness has been demonstrated as a sensitively structural measure to disease. The question of whether long-term, recurrent brain dysfunction, like motor deficits, aphasia and cognition impairment, and compensation of collateral circulation can cause brain structural alterations has not been stressed. This investigation explored the relationship between the degree of pathological changes of intracranial aorta and size of intracerebral focus, and to understand how the cortex is affected by the intracranial aorta and intracerebral focus, we used structural magnetic resonance imaging to evaluate changes of cerebral cortical thickness.Methods: A volumetric magnetization prepared 2 rapid acquisition gradient echoes(MP2RGE) T1-weighted sequence(TR=4000ms, TE=2.98 ms, flip angle=0, FOV=256×256mm, slice number=176, voxel size=1×1×1mm), FLAIR(TR=20ms, TE=3.43 ms, flip angle=18°, FOV=640×580mm, slice thickness=0.5mm) and MRA(TR=9000ms, TE=85ms, flip angle=150°, FOV=512×512mm, slice thickness=6mm) scans with a 3.0-Tesla skyra(Siemens AG, Erlangen, Germany) were obtained from 45 participants with MMD(25 males, 20 females, age range 21-50 years, average age 37 years). We used a set of automated tools(Free Surfer) to perform surface reconstruction and cortical thickness measurement. The ischemic or hemorrhagic cerebrovascular accident(CVA) lesions were evaluated on FLAIR and divided into different categories. The steno-occlusive severity of intracranial vesselswas evaluated on MRA. Spearman rank order correlation was used in analyzing the relation between CVA score and MRA score, and relation between the imaging scores and cortical thickness was measured by GLM.Results: A significant relationship was observed between CVA score and MRA score in patients with MMD(P<0.05). There was no significant correlation between MRA score and cortical thickness(P>0.05). And cortical thickness of multiple cerebral areas, especially bilateral superior temporal gyrus and right superior frontal gyrus, inferior temporal gyrus, insula, fusiform gyrus and precentral gyrus, was inversely correlated with CVA score(P<0.05). On the other hand, no statistically positive correlation was observed between CVA score and cortical thickness(P>0.05).Conclusion: Pathological changes degree of intracranial aorta were consistent with the severity of cerebrovascular accident and did not directly affect the cortical thickness. CVA lesions, meanwhile, can cause regional thinning of cortical thickness. These findings suggest that collateral circulation may play definite role in occurrence of CVA and changes of cortical thickness, and cortical thickness may have considerable potential to be a biomarker of diagnosis and assessment of MMD in the future. The effect of collateral circulation on cortical thickness need to be further gone into.Objective: Moyamoya disease(MMD) presents with repeated transient ischemic attacks(TIA), strokes, intracranial hemorrhage, headaches and seizures. Stroke is most commonly found in above initial symptoms, which usually results in dysphagia. To preserve blood-supply quantity of brain tissue, patients with MMD may develop compensatory changes of hemodynamics in local cerebral vasculature with a resultant loss of vascular reactivity. These alterations may produce a corresponding influence on the blood-oxygen-level-dependent(BOLD) signal that is the basis for functional magnetic resonance imaging(f MRI). This investigation exploited to hemodynamic response traits of motor area in patients with MMD.Methods: A sequence of echo planar imaging(TR=2000ms, TE=30mm, flip angle =90°, FOV=384×384mm, slice number=33, voxel size=3×3×3mm) with a 3.0-Tesla skyra(Siemens AG, Erlangen, Germany) were obtained from 45 participants with MMD(25 males, 20 females, age range 21-50 years, average age 37 years) and 15 healthy volunteers matched for age and sex. The f MRI was acquired for each subject using a block design of left/right grasping task. Activation maps were calculated, and individual hemodynamic response curves were generated for left and right primary motor cortices after post-processing of the data. And negative response time, time-to-peak and positive response time can be measured through the curves. Both the left and right side hemisphere was divided into 3 groups according to the symptom: affected sides of dyskinesia patients, unaffected sides of dyskinesia patients and bilateral sides of non-dyskinesia patients. Adoptive statistical methods included independent-samples t test, Mann-Whitney U test and paired t test.Results: Relative to controls, negative response time, time-to-peak and positive response time were increased in all patients with MMD(P<0.05), and the former two parameters were more significant(P<0.05). In the 3 groups of MMD, significance of negative response time and time-to-peak was successively reduced: affected sides of dyskinesia patients were the most significant group and the non-dyskinesia patients were the least one(P<0.05). No statistical significance was found between two sides of control’s negative response time, time-to-peak and positive response time(P>0.05). Affected sides of dyskinesia patients’ time-to-peak were longer than that ofunaffected sides of dyskinesia patients(P<0.05), and there was no significant difference between unaffected sides of dyskinesia patients and bilateral sides of non-dyskinesia patients of the 3 parameters(P>0.05).Conclusion: With or without dyskinesia, hemodynamic response changes of bilateral motor area, especially the prolonged negative response time and delayed time-to-peak, were a universal phenomenon in patients with MMD. And the most significant hemodynamic response changes were the affected sides of dyskinesia patients. Moreover, time-to-peak could be a good indicator for severe ischemia corresponding to misery perfusion. We suspect that hemodynamic response changes in patients with MMD were not isolated to motor area but spread across the entire cerebrum. Brain tissue could tolerate these changes within some range and once beyond the threshold, functional deficits may occur. Therefore, f MRI remains a useful clinical tool of evaluating hemodynamics, meanwhile, caution is warranted when studying patients with MMD.