Role of CT perfusion imaging in evaluating the effects of multiple burr hole surgery on adult ischemic Moyamoya disease

Clinical Characteristics and Multi-Model Imaging Analysis of Moyamoya Disease: An Observational Study

PURPOSE

Previous studies have lacked a comprehensive analysis of imaging modalities for diagnosing Moyamoya disease (MMD). This study aims to bridge this gap by utilizing multi-modal imaging to provide a more detailed understanding of the clinical and imaging characteristics of MMD.

METHODS

A retrospective analysis was conducted on seventy-eight adult MMD patients enrolled from March 2018 to March 2021. The study focused on clinical features, imaging findings, and treatment outcomes, with a particular emphasis on the comparative efficacy of different imaging modalities.

RESULTS

In this series, clinical manifestations varied depending on the type of MMD, with intracerebral hemorrhage (ICH) being the most common (69.2%), followed by cerebral infarction (25.6%). Imaging techniques provided critical diagnostic insights: magnetic resonance imaging (MRI) demonstrated superior sensitivity over computed tomography (CT) in detecting hemorrhages, whereas computed tomography angiography (CTA) and digital subtraction angiography (DSA) identified intricate vascular lesions, including moyamoya vessels and aneurysms. Notably, cerebral perfusion imaging (CTP) highlighted significant differences in cerebral blood flow and volume between infarction and hemorrhage cases. This comprehensive imaging approach guided varied therapeutic strategies, including bypass surgery in 57 patients and interventional embolization for aneurysms in 14 patients.

CONCLUSION

The authors' findings underscore the critical role of early diagnosis using DSA, whereas highlighting CTA and MRA as valuable noninvasive tools for screening and follow-up. The integration of multi-modal imaging provides a detailed vascular assessment crucial for individualized patient management, facilitating timely interventions and significantly improving clinical outcomes.

How to reduce the complication rate of multiple burr holes surgery in moyamoya angiopathy

PURPOSE

This study is aimed at analyzing clinical outcome, absence of stroke recurrence, revascularization, and complications and long-term follow-up in the surgical treatment of moyamoya angiopathy (MMA) using the multiple burr holes (MBH) technique with dura opening and arachnoid preservation as a single procedure. To the best of our knowledge, this is the first to describe an MBH technique with arachnoid preservation.

METHOD

We retrospectively reviewed all patients operated from June 2001 to March 2021, for a symptomatic and progressive MMA operated with opening of the dura but arachnoid preservation. Clinical examinations were obtained in all patients, and radiological monitoring was performed by cerebral 3D-magnetic resonance angiography (MRA) with perfusion or single-photon emission computed tomography (SPECT) with acetazolamide.

RESULTS

In total, 21 consecutive patients (6 children and 15 adults) were included with a mean age of 7.4 years in the pediatric group and 36.9 years in the adult group. Initial presentation was permanent ischemic stroke in 15 cases, transient ischemic attack (TIA) in 5 cases, and cerebral hemorrhage in one case. The MBH with dura opening and arachnoid preservation was performed bilaterally in 9 cases (43%) and unilaterally in 12 cases (57%). One patient died due to intraoperative bilateral ischemic stroke. Of the 20 other patients, 30% demonstrated clinical stability and 70% showed partial or complete recovery. Although one patient experienced a perioperative stroke, we did not observe any pseudomeningocele or postoperative ischemic stroke (IS) recurrence in all surviving cases during the average follow-up period of 55.5 months (range: 1-195). These outcomes emphasize the importance of preoperative monitoring to ensure the effectiveness and safety of the intervention. Postoperative angiography studies showed revascularization in 96.3% of treated hemispheres (100% in the adult group vs 80% in the pediatric group).

CONCLUSIONS

Our results on this small cohort suggest that the MBH technique with opening of the dura and arachnoids preservation can prevent recurrent strokes and reduce the risk of pseudomeningocele.

Evaluation of surgical revascularization procedure outcomes for adult Moyamoya disease: a computed tomography perfusion-based study

BACKGROUND

The effectiveness of surgical interventions, whether direct or indirect, for Moyamoya disease (MMD) remains controversial. This study aims to investigate CT perfusion (CTP) as an objective method to evaluate the outcomes of different surgical modalities for adult MMD.

METHODS

The clinical and imaging data of 41 patients who underwent superficial temporal artery-middle cerebral artery (STA-MCA) bypass and 43 who received encephaloduroarteriosynangiosis (EDAS) were retrospectively analyzed. Intra- and intergroup differences in the Modified Rankin Scale (mRS) score, the change in clinical symptoms, collateral grade, and CTP parameters pre- and postoperatively were compared.

RESULTS

The overall level of the change in clinical symptoms in the STA-MCA group was higher than in the EDAS group (p < 0.05). In the operative area, the relative cerebral blood flow (rCBF) was significantly higher whereas the relative time to peak (rTTP) and the relative mean transit time (rMTT) were significantly lower in the STA-MCA and EDAS groups postoperatively than preoperatively (all p < 0.05). In the ipsilateral frontal lobe and basal ganglia, the postoperative rCBF was significantly higher, and the rTTP was significantly lower than the preoperative in the STA-MCA group (all p < 0.05). The postoperative rCBF improvement was higher in each brain area for STA-MCA than in the EDAS group (all p < 0.05).

CONCLUSION

Highlighting the utility of CTP, this study demonstrates its effectiveness in assessing postoperative cerebral hemodynamic changes in adult MMD patients. STA-MCA yielded a larger postoperative perfusion area and greater improvement compared to EDAS, suggesting CTP's potential to elucidate symptom variation between two surgical revascularization procedures.

CRITICAL RELEVANCE STATEMENT

We analyzed computed tomography perfusion parameters in pre- and postoperative adult Moyamoya disease patients undergoing superficial temporal artery-middle cerebral artery bypass and encephaloduroarteriosynangiosis. Our findings suggest computed tomography perfusion's potential in objectively elucidating symptom variations between these surgical revascularization approaches for MMD.

KEY POINTS

• Postoperative perfusion improvement is only confined to the operative area after EDAS. • Besides the operative area, postoperative perfusion in the ipsilateral frontal lobe and basal ganglia was also improved after STA-MCA. • The degree of perfusion improvement in each brain area in the STA-MCA group was generally greater than that in the EDAS group.

Salvage multiple burr hole surgery in patients with Moyamoya disease: efficacy evaluation using probabilistic independent component analysis of dynamic susceptibility contrast perfusion MRI

PURPOSE

Multiple burr hole surgery is considered to be an option for achieving indirect revascularization in patients with ischemic Moyamoya disease (MMD). We aimed to investigate the efficacy of stand-alone multiple burr hole surgery for salvage revascularization in patients with MMD by assessing the hemodynamic changes via normalized time-to-peak (nTTP) analysis and independent component analysis (ICA) of preoperative and postoperative dynamic susceptibility contrast (DSC) perfusion MRI data.

METHODS

The DSC perfusion MRI data of 25 hemispheres from 21 patients with MMD, who underwent multiple burr hole surgery for salvage revascularization due to persistent or recurrent symptoms after primary revascularization with modified encephaloduroarteriosynangiosis (mEDAS), were analyzed. The nTTP, which was measured using the region of interests covering the entire surgical hemisphere, was compared between the preoperative and postoperative images. ICA was used to compare the relative arterial and venous components of the surgical hemispheres between the respective preoperative and postoperative images.

RESULTS

The median postoperative nTTP (1.80 s) was significantly shorter than the median preoperative nTTP (4.10 s) (P < 0.001). The postoperative relative arterial component of the surgical hemisphere (median: 0.04) was significantly higher than the preoperative relative arterial component (median: - 0.02, P < 0.001). In contrast, the postoperative relative venous component of the surgical hemisphere (median: - 0.05) was significantly lower than the preoperative value (median: 0.05, P < 0.001).

CONCLUSION

The improvement in cerebral perfusion parameters observed on postoperative DSC perfusion MRI demonstrated that stand-alone multiple burr hole surgery could be a favorable salvage revascularization technique after mEDAS failure in patients with ischemic MMD.

Imaging methods for surgical revascularization in patients with moyamoya disease: an updated review

Neuroimaging is crucial in moyamoya disease (MMD) for neurosurgeons, during pre-surgical planning and intraoperative navigation not only to maximize the success rate of surgery, but also to minimize postsurgical neurological deficits in patients. This is a review of recent literatures which updates the clinical use of imaging methods in the morphological and hemodynamic assessment of surgical revascularization in patients with MMD. We aimed to assist surgeons in assessing the status of moyamoya vessels, selecting bypass arteries, and monitoring postoperative cerebral perfusion through the latest imaging technology.

Encephaloduroarteriosynangiosis (EDAS) treatment of moyamoya syndrome: evaluation by computed tomography perfusion imaging

OBJECTIVE

To explore the value of computed tomography perfusion (CTP) imaging for evaluating the efficacy of encephaloduroarteriosynangiosis (EDAS) treatment of moyamoya syndrome (MMS).

METHODS

Forty-three patients with MMS (48 hemispheres) who received EDAS treatment were examined using CTP and DSA before and after surgery. CTP of the ipsilateral cortex, contralateral mirror area, and pons region were measured, and the relative cerebral blood flow (rCBF) and volume (rCBV), mean transit time (rMTT), and time-to-peak (rTTP) were calculated. Based on postoperative DSA, 48 hemispheres were apportioned to two groups based on rich (grades 2, 3) or poor (grades 0, 1) collateral vessel formation, and the pre- and post-operative differences in perfusion changes were compared. The association between clinical outcome, CTP, and the degree of DSA collateral vessels was explored.

RESULTS

rCBF and rMTT significantly improved in both the poor and rich collateral vessel formation groups (n = 21 and 27, respectively), while rTTP significantly improved only in the latter. Postoperative CTP improved in the rich and the grade 1 collateral vessel groups (p < 0.01). The clinical improvement was consistent with the improvement of CTP (p = 0.07), but less consistent with the degree of collateral angiogenesis (p = 0.003).

CONCLUSION

CTP can quantitatively evaluate the improvement of brain tissue perfusion in the operated area after EDAS. Brain tissue perfusion in operated areas improved regardless of postoperative rich or poor collateral vessel formation observed via DSA. A significant improvement in rTTP in the operated area may indicate the formation of abundant collateral vessels.

KEY POINTS

• CTP showed that brain tissue perfusion in the operated area after EDAS improved regardless of rich or poor collateral vessel formation observed via DSA. • Significant improvement of rTTP in the operated area may indicate the formation of abundant collateral vessels.

Prognostic factors of delayed cerebral ischemia after subarachnoid hemorrhage including CT perfusion: a prospective cohort study

Background

Delayed cerebral ischemia (DCI) is the worst sequel following subarachnoid hemorrhage (SAH), representing a challenge in prediction and prevention. The current study aims to identify the optimum predictors of DCI including CT perfusion (CTP) and to determine the best prognostic thresholds.

This prospective study included 49 SAH patients. All patients were treated with the standard therapy and underwent non-contrast CT, CTP, and CTA within 3 days after SAH. Hunt and Hess and Fisher scales were assessed besides quantitative CTP parameters. The primary endpoint was DCI within 21 days after SAH, defined as clinical deterioration or infarction.

Results

Out of 49 eligible patients with SAH, 9 patients developed DCI. Univariate analysis revealed that Hunt and Hess scale, Fisher scale, the presence of a cerebral aneurysm, and mean transit time (MTT) were predictive for DCI. Diagnostic threshold values by ROC curve analysis with optimal sensitivity and specificity were Hunt and Hess scale > 2, Fisher scale > 2, and MTT of 4.65 s.

Conclusion

MTT is a sensitive and specific predictor of DCI. However, Hunt and Hess scale has the optimal sensitivity and specificity to distinguish between patients who developed DCI and clinically stable patients.

Preoperatively estimated graft flow rate contributes to the improvement of hemodynamics in revascularization for Moyamoya disease

OBJECTIVES

Superficial temporal artery (STA)-middle cerebral artery (MCA) bypass operation is an effective treatment for patients with Moyamoya disease, and the hemodynamic parameters are reported to be improved after operation. However, there is no report concerning hemodynamic changes from the viewpoint of the preoperative anatomical structure of grafts. In this study, we evaluated the correlation between the preoperatively estimated blood flow of the graft obtained through image-based computational fluid dynamics (CFD) analysis and the hemodynamic changes in the acute phase after revascularization.

MATERIALS AND METHODS

A total of 30 hemispheric sides of 23 patients were examined. The blood flow, that is, flow rate (FR) of the STA branches that were anastomosed to the MCA was evaluated using CFD analysis based on computed tomography (CT) angiography imaging data. The correlations between the FR and the hemodynamic changes in the acute phase after revascularization obtained through CT perfusion were assessed.

RESULTS

The preoperatively estimated FR of the graft was moderately correlated with the changes in the mean transit time significantly and weakly correlated with those in the cerebral blood flow and cerebral blood volume. In addition, the FR was strongly correlated with age and the diameter of the STA from the origin to the bifurcation.

CONCLUSION

The preoperatively estimated FR of the graft obtained through image-based CFD analysis contributed to the improvement of the mean transit time after revascularization. Because the FR of the graft was associated with the diameter of the STA, the size of the STA might be an important factor in postoperative hemodynamic changes. This might lead to the risk assessment of acute drastic hemodynamic changes as cerebral hyperperfusion, and consequently, better surgical outcomes might be expected.

A Novel Staging System to Evaluate Cerebral Hypoperfusion in Patients With Moyamoya Disease

Background and Purpose- The study goal was to evaluate cerebral perfusion in moyamoya patients with a novel staging system and investigate the association between differences of perfusion status and clinical outcomes in patients treated with revascularization. Methods- About 506 consecutive patients from 2009 to 2015 were enrolled. The perfusion status was evaluated by a staging system-the stage of preinfarction period based on the result of computed tomography perfusion. Hemisphere in different perfusion stage was compared between hemorrhagic patients (n=155) and ischemic patients (n=351). The modified Rankin Scale was applied to evaluate the prognosis of patients. Results- In the enrolled 506 patients: 229 hemispheres (22.6%) with normal perfusion, 72 hemispheres (7.1%) in stage I, 205 hemispheres (20.3%) in stage II, 308 hemispheres (30.4%) in stage III, and 198 hemispheres (19.6%) in stage IV. Significant difference was observed in stage distribution between hemorrhagic patients and ischemic patients ( P<0.01). The ratio of hemispheres with normal perfusion in hemorrhagic group is more than the ischemic group ( P<0.05; odds ratio, 1.440; 95% CI, 1.144-1.811). The ratio of hemispheres in stage III in ischemic group is more than the hemorrhagic group ( P<0.01; odds ratio, 0.618, 95% CI, 0.487-0.783). In the prognosis-related analysis, the stage I group has the highest improved ratio (73.9%) and the normal perfusion group has the lowest improved ratio (33.3%). The improved ratio has a decreasing tendency from stage I to stage IV. Conclusions- The novel preinfarction staging system is a valuable assessment tool to evaluate cerebral perfusion status in moyamoya patients and predict the efficacy of revascularization. Ischemic patients suffer more from hypoperfusion. Patients in stage I and stage II are more likely to obtain improvement after revascularization. This is a retrospective study.

Statistical properties of cerebral CT perfusion imaging systems. Part I. Cerebral blood volume maps generated from nondeconvolution-based systems

PURPOSE

The development and clinical employment of a computed tomography (CT) imaging system benefit from a thorough understanding of the statistical properties of the output images; cerebral CT perfusion (CTP) imaging system is no exception. A series of articles will present statistical properties of CTP systems and the dependence of these properties on system parameters. This Part I paper focuses on the signal and noise properties of cerebral blood volume (CBV) maps calculated using a nondeconvolution-based method.

METHODS

The CBV imaging chain was decomposed into a cascade of subimaging stages, which facilitated the derivation of analytical models for the probability density function, mean value, and noise variance of CBV. These models directly take CTP source image acquisition, reconstruction, and postprocessing parameters as inputs. Both numerical simulations and in vivo canine experiments were performed to validate these models.

RESULTS

The noise variance of CBV is linearly related to the noise variance of source images and is strongly influenced by the noise variance of the baseline images. Uniformly partitioning the total radiation dose budget across all time frames was found to be suboptimal, and an optimal dose partition method was derived to minimize CBV noise. Results of the numerical simulation and animal studies validated the derived statistical properties of CBV.

CONCLUSIONS

The statistical properties of CBV imaging systems can be accurately modeled by extending the linear CT systems theory. Based on the statistical model, several key signal and noise characteristics of CBV were identified and an optimal dose partition method was developed to improve the image quality of CBV.

Imaging of Moyamoya Disease and Moyamoya Syndrome: Current Status

Moyamoya disease (MMD) and Moyamoya syndrome (MMS) are referring to a progressive steno-occlusive vasculopathy at terminal portions of the bilateral internal carotid arteries and their proximal branches with prominent collateral artery formation. They can be found throughout the world and cause irreversible damage to the cerebral hemodynamics due to the progressive nature. Prompt diagnosis and accurate assessment could significantly improve the prognosis of MMD and MMS. Some imaging modalities could be used for diagnosis and nonquantitative evaluation of MMD and MMS, such as conventional computed tomography (CT) and magnetic resonance imaging (MRI), digital subtraction angiography, CT angiography (CTA), and magnetic resonance angiography. Some could quantitatively evaluate the cerebral hemodynamics of MMD and MMS, such as single-photon emission CT, positron emission tomography, xenon-enhanced CT, perfusion CT, dynamic susceptibility contrast MRI, arterial spin labeling MRI, and the hemodynamic parameters measured by those imaging methods could guide treatment of MMD and MMS. All the imaging modalities have their merits and demerits, and they can play a part in certain situation. We need establish standardized protocols for preoperative and postoperative evaluation with different imaging techniques in the further science for MMD and MMS.

Modified encephalo-duro-periosteal-synangiosis (EDPS) for the revascularization of anterior cerebral artery territory in moyamoya disease: A single-center experience

OBJECTIVES

Anterior cerebral artery (ACA) territory, a crucial area of intellectual development in children, is frequently involved in the progress of moyamoya disease (MMD). However, revascularization surgeries for this area are not as established as surgeries for middle cerebral artery (MCA) territory. This study aimed to describe our experience and study the effect of revascularizing ACA territory with periocranium and dural leaflets, which is referred to as 'encephalo-duro-periosteal-synangiosis (EDPS)'.

PATIENTS AND METHOD

Fourteen hemispheres of 9 MMD patients who had undergone EDPS from November 2015 till July 2017 in our hospital were retrospectively included. Clinical characteristics and procedure-related information were recorded. Cerebral perfusion was evaluated by computed tomography perfusion (CTP). Absolute and relative (r) CTP parameters of ROIs in ACA territory at the level of centrum semiovale and middle basal ganglia were calculated. Preoperative and postoperative parameters were compared.

RESULTS

All EDPS procedures were technically successful with no postoperative complications. The mean operating time was 75.00 ± 22.53 min per hemisphere. Postoperative absolute cerebral blood flow (CBF), rCBF were significantly increased and absolute time to peak (TTP), rTTP, absolute mean transit time (MTT) were significantly reduced in ACA territory at centrum semiovale level (P = 0.002, 0.045, 0.007, 0.005 and 0.039 respectively). Improved outcomes were achieved in five patients, stabilization in three and one patient had deterioration out of intracerebral hemorrhage during follow-up.

CONCLUSION

EDPS is a simple but effective technique to revascularize ACA territory for MMD. EDPS significantly improved cerebral blood perfusion of frontal lobe in the majority of patients without increasing procedure-related risks.

Time Course of Neoangiogenesis After Indirect Bypass Surgery for Moyamoya Disease : Comparison of Short-term and Long-term Follow-up Angiography

OBJECTIVE

Indirect bypass surgery, which induces spontaneous neoangiogenesis in ischemic brain tissue and improves cerebral blood flow, is an effective treatment for moyamoya disease (MMD). The time course of neoangiogenesis development has not yet been investigated. This study aimed to determine the critical period of neovascularization after indirect bypass in MMD patients.

METHODS

Patients with MMD who underwent indirect bypass surgery at Peking University International Hospital between January 2015 and October 2017 were retrospectively reviewed. Surgically treated hemispheres with short-term (3-6 months) and long-term (1 year) follow-up digital subtraction angiography (DSA) were included. The effects of revascularization were evaluated on lateral and anteroposterior views using angiography and compared between two follow-ups of the same hemisphere.

RESULTS

This study included 25 hemispheres from 24 MMD patients (mean age: 22.48 ± 14.83 years), among whom 13 were pediatric patients and 12 were adults. Qualitative measurements including the Matsushima scale and coverage of neoangiogenesis on anteroposterior views were not significantly different between the short term and long term (P = 0.083 and P = 0.157, respectively). Quantitative measurements including the greatest width and height of the area covered by neovascularization on lateral views of DSA and the greatest depth of neovascularization penetration on anteroposterior views (P = 0.488, 0.298 and 0.527, respectively) were also not significantly different. The mean count of newly formed veins was more at long-term than short-term follow-up (5.5 ± 2.5 vs. 5.1 ± 2.4, P = 0.005). Subgroup analysis of pediatric patients and adults yielded the same results as in the whole series.

CONCLUSION

After indirect bypass surgery, the major time window of arterial neoangiogenesis development was within 6 months after surgery. The general effect of revascularization was very similar in the short and long term; therefore, a follow-up angiography scheduled at 6 months after surgery is recommended. Growth of veins might continue after 6 months.

Assessment of Single-Barrel Superficial Temporal Artery-Middle Cerebral Artery Bypass in Treatment for Adult Patients with Ischemic-Type Moyamoya Disease

BACKGROUND Moyamoya disease (MMD) is an idiopathic disease caused by progressive steno-occlusion of the distal internal carotid artery. Ideal surgical treatment for adult patients with ischemic-type MMD has not been achieved. The aim of this study was to evaluate the efficacy of single-barrel superficial temporal artery-middle cerebral artery (STA-MCA) bypass in treatment for adult patients with ischemic-type MMD by analyzing clinical and radiological data retrospectively. MATERIAL AND METHODS The present study included 37 patients with non-hemorrhagic MMD, including 21 women and 16 men (21~55 years old, mean age 38.1 years). The bypass surgery was performed on 56 sides in the 37 patients. The clinical charts, angiographic revascularization, and hemodynamic changes were reviewed at 6-60 months after surgery. RESULTS Among the 37 patients, the clinical symptoms and signs of 32 patients were improved or stabilized. Five patients had complications, including 2 cases of acute cerebral infarction, 1 case of epidural hematoma, and 1 case of transient speech disturbance, and 1 patient died. Follow-up computed tomography perfusion (CTP) revealed that cerebral blood flow (CBF) was markedly improved after surgery (P<0.05). Time to peek (TTP) and mean transit time (MTT) were significantly decreased after surgery (P<0.05). No significant change in cerebral blood volume (CBV) was found after surgery (P>0.05). Postoperative patency was clearly verified in 52 bypasses (92.8%) of 56 bypasses on follow-up DSA imaging. CONCLUSIONS Single-barrel STA-MCA bypass can be considered as an effective surgical treatment, which exhibits satisfactory clinical efficacy in ischemic-type MMD patients.

Effect of pre-surgery assessments on the prognosis of patients received extracranial-intracranial bypass surgery

BACKGROUND

Extracranial-intracranial (EC-IC) bypass surgery has been used to improve the conditions of cerebral ischemia symptoms for selected patients resulting from diverse complications such as stroke and atherosclerotic disease. However, several clinical trials showed EC-IC bypass surgery failed to prevent recurrent ischemic stroke in certain patients.

OBJECTIVE

Our clinical trial aimed to investigate whether there is a correlation between pre-surgery assessments and prognosis of patients received EC-IC bypass operation.

METHODS

We divided all patients into 4 groups according to their compensatory stages of cerebral ischemia. The values of cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), time to peak (TTP), and oxygen extraction fraction (OEF) were obtained by computed tomography perfusion (CTP), single photon emission computed tomography (SPECT), and positron emission tomography (PET) at different time points before and after EC-IC bypass surgery. We assessed the correlations between the compensatory stage with modified Rankin scale (mRS) scores, survival rates, stroke and TIA incidences over the 12 months after surgery.

RESULTS

Patients with normal CBF, normal or increased CBV, and normal OEF tended to have a better prognosis after the EI-CI bypass operation than patients with abnormal CBF, CBV and OEF. However, patients with abnormal CBF and CBV, and increased OEF showed elevated mRS, less survival rates, and higher stroke and TIA incidences over the 12 months after surgery, compared to the groups with normal CBF, CBV and OEF.

CONCLUSIONS

Our results suggest that a defined compensatory stage of cerebral ischemia might be useful for the prognosis of patients receiving EI-CI bypass surgery.

Application of CT perfusion to assess hemodynamics in symptomatic Moyamoya syndrome: focus on affected side and parameter characteristic

OBJECTIVE

Vascular and hemodynamic changes were not consistent in symptomatic and non-symptomatic cerebral hemisphere in patients with symptomatic moyamoya syndrome (MMS). Thus, the purpose of this study is to evaluate the hemodynamic difference between symptomatic and non-symptomatic cerebral hemisphere in patients with symptomatic MMS.

METHODS

Patients who were diagnosed with symptomatic MMS were retrospectively collected. All cases underwent CTP examination. Regions of interest (ROIs) were chosen in the mirroring bilateral frontal lobes, temporal lobes, the basal ganglia, and the brainstem as control region. The relative perfusion parameter values of symptomatic side were compared with non-symptomatic side.

RESULTS

Of the 40 patients, 33 patients were taken into assessment. In all cases (n = 33), rCBF, rMTT, and rTTP in all regions of interest (ROIs) of the symptomatic side were significantly different from those of contralateral side. In unilateral MMS patients (n = 7), rCBF values were not significantly different between two sides in the temporal lobe and basal ganglia area; rTTP values were significantly higher in the symptomatic side. rMTT values were significantly higher only in the temporal lobe of symptomatic side. In bilateral MMS patients (n = 26), rCBF and rMTT in all ROIs of the symptomatic side were significantly different from those of contralateral side. However, there were no significant differences between two sides in all ROIs on rTTP values.

CONCLUSIONS

This study demonstrates that rCBF and rMTT were more sensitive than rTTP for evaluating hemodynamic changes in patients with symptomatic bilateral MMS. Furthermore, patients with unilateral MMS may have a preserved rCBF compared to those with bilateral disease.

Characteristics of cerebral hemodynamics assessed by CT perfusion in moyamoya disease

Due to the recent development of multidetector row computed tomography (CT), hemodynamic parameters can now be conveniently obtained with CT perfusion. The purpose of this study is to characterize the hemodynamic parameters of CT perfusion in moyamoya disease, and to discuss the differences in collateral circulation between moyamoya disease and atherosclerotic disease. A total of 16 hemispheric sides of 15 patients with moyamoya disease and 10 hemispheric sides of 9 patients with atherosclerotic disease who underwent bypass surgery were included. CT perfusion was performed with ¹²³I-IMP SPECT. Cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) values obtained by CT perfusion using standard singular value decomposition as the deconvolution algorithm in moyamoya disease were calculated. Preoperative values of these parameters were compared with those of atherosclerotic disease. Then, the postoperative changes of these parameters were analyzed. In the impaired side, CBF as measured by CT perfusion was correlated with that measured by ¹²³I-IMP SPECT. In moyamoya disease, CBV as measured by CT perfusion was significantly increased compared to in atherosclerotic disease, yet CBF was significantly decreased in atherosclerotic disease. Postoperatively, the asymmetry ratios of MTT were significantly improved, especially in atherosclerotic disease compared with moyamoya disease. On CT perfusion, the parameters included transit time and arrival time. CBV increase in moyamoya disease and postoperative improvement of MTT, especially in atherosclerotic disease, were unique characteristics in each. This might be due to the difference of collateral circulation and compensatory mechanisms between moyamoya disease and atherosclerotic disease.

Evaluation of Encephaloduroarteriosynangiosis Efficacy Using Probabilistic Independent Component Analysis Applied to Dynamic Susceptibility Contrast Perfusion MRI

BACKGROUND AND PURPOSE

Indirect cerebral revascularization has been successfully used for treatment in Moyamoya disease and symptomatic intracranial atherosclerosis. While angiographic neovascularization has been demonstrated after surgery, measurements of local tissue perfusion are scarce and may not reflect the reported successful clinical outcomes. We investigated probabilistic independent component analysis and conventional perfusion parameters from DSC-MR imaging to measure postsurgical changes in tissue perfusion.

MATERIALS AND METHODS

In this prospective study, 13 patients underwent unilateral indirect cerebral revascularization and DSC-MR imaging before and after surgery. Conventional perfusion parameters (relative cerebral blood volume, relative cerebral blood flow, and TTP) and probabilistic independent components that reflect the relative contributions of DSC signals consistent with arterial, capillary, and venous hemodynamics were calculated and examined for significant changes after surgery. Results were compared with postsurgical DSA studies to determine whether changes in tissue perfusion were due to postsurgical neovascularization.

RESULTS

Before surgery, tissue within the affected hemisphere demonstrated a high probability for hemodynamics consistent with venous flow and a low probability for hemodynamics consistent with arterial flow, whereas the contralateral control hemisphere demonstrated the reverse. Consistent with symptomatic improvement, the probability for venous hemodynamics within the affected hemisphere decreased with time after surgery (P = .002). No other perfusion parameters demonstrated this association. Postsurgical DSA revealed an association between an increased preoperative venous probability in the symptomatic hemisphere and neovascularization after surgery.

CONCLUSIONS

Probabilistic independent component analysis yielded sensitive measurements of changes in local tissue perfusion that may be associated with newly formed vasculature after indirect cerebral revascularization surgery.

Serum miRNA signature in Moyamoya disease

Moyamoya disease (MMD) is a cerebrovascular disease characterized by progressive stenosis of the intracranial internal carotid arteries and their proximal branches. However, the etiology of this rare disease remains unknown. Serum microRNA (miRNA) profiles have been screened to identify novel biomarkers of prognostic values. Here, we identified serum miRNAs that might play an important role in the pathogenesis of MMD. A genome-wide miRNA array analysis of two pooled serum samples from patients with MMD and controls revealed 94 differentially expressed serum miRNAs, including 50 upregulated and 44 downregulated miRNAs. In an independent MMD cohort, real-time PCR confirmed that miR-106b, miR-130a and miR-126 were significantly upregulated while miR-125a-3p was significantly downregulated in serum. GO analysis showed that the differentially expressed serum miRNAs were enriched in metabolic processes, transcription and signal transduction. Pathway analysis showed that the most enriched pathway was mTOR signaling pathway with 16 potential, functional targets. Finally, we found that 16 and 13 aberrant serum miRNAs coordinately inhibited RNF213 and BRCC3 protein expression at the posttranscriptional level, respectively, resulting in defective angiogenesis and MMD pathogenesis. To our knowledge, this is the first study to identify a serum miRNA signature in MMD. Modulation of the mechanism underlying the role of serum miRNAs in MMD is a potential therapeutic strategy and warrants further investigations.