Selective and superselective angiography of pediatric moyamoya disease angioarchitecture: the anterior circulation

Arterial spin labeling as an ancillary assessment to postoperative conventional angiogram in pediatric moyamoya disease

OBJECTIVE

Digital subtraction angiography (DSA) is commonly performed after pial synangiosis surgery for pediatric moyamoya disease to assess the degree of neovascularization. However, angiography is invasive, and the risk of ionizing radiation is a concern in children. In this study, the authors aimed to identify whether arterial spin labeling (ASL) can predict postoperative angiogram grading. In addition, they sought to determine whether patients who underwent ASL imaging without DSA had similar postoperative outcomes when compared with patients who received ASL imaging and postoperative DSA.

METHODS

The medical records of pediatric patients who underwent pial synangiosis for moyamoya disease at a quaternary children's hospital were reviewed during a 10-year period. ASL-only and ASL+DSA cohorts were analyzed. The frequency of preoperative and postoperative symptoms was analyzed within each cohort. Three neuroradiologists assigned a visual ASL grade for each patient indicating the change from the preoperative to postoperative ASL perfusion sequences. A postoperative neovascularization grade was also assigned for patients who underwent DSA.

RESULTS

Overall, 21 hemispheres of 14 patients with ASL only and 14 hemispheres of 8 patients with ASL+DSA were analyzed. The groups had similar rates of MRI evidence of acute or chronic stroke preoperatively (61.9% in the ASL-only group and 64.3% in the ASL+DSA group). In the entire cohort, transient ischemic attack (TIA) (p = 0.027), TIA composite (TIA or unexplained neurological symptoms; p = 0.0006), chronic headaches (p = 0.035), aphasia (p = 0.019), and weakness (p = 0.001) all had decreased frequency after intervention. The authors found a positive association between revascularization observed on DSA and the visual ASL grading (p = 0.048). The visual ASL grades in patients with an angiogram indicating robust neovascularization demonstrated improved perfusion when compared with the ASL grades of patients with a poor neovascularization.

CONCLUSIONS

Noninvasive ASL perfusion imaging had an association with postoperative DSA neoangiogenesis following pial synangiosis surgery in children. There were no significant postoperative stroke differences between the ASL-only and ASL+DSA cohorts. Both cohorts demonstrated significant improvement in preoperative symptoms after surgery. Further study in larger cohorts is necessary to determine whether the results of this study are validated in order to circumvent the invasive catheter angiogram.

Visualization and Classification of Deeply Seated Collateral Networks in Moyamoya Angiopathy with 7T MRI

BACKGROUND AND PURPOSE

Collateral networks in Moyamoya angiopathy have a complex angioarchitecture difficult to comprehend on conventional examinations. This study aimed to evaluate morphologic patterns and the delineation of deeply seated collateral networks using ultra-high-field MRA in comparison with conventional DSA.

MATERIALS AND METHODS

Fifteen white patients with Moyamoya angiopathy were investigated in this prospective trial. Sequences acquired at 7T were TOF-MRA with 0.22 × 0.22 × 0.41 mm³ resolution and MPRAGE with 0.7 × 0.7 × 0.7 mm³ resolution. Four raters evaluated the presence of deeply seated collateral networks and image quality in a consensus reading of DSA, TOF-MRA, and MPRAGE using a 5-point scale in axial source images and maximum intensity projections. Delineation of deeply seated collateral networks by different imaging modalities was compared by means of the McNemar test, whereas image quality was compared using the Wilcoxon signed-rank test.

RESULTS

The relevant deeply seated collateral networks were classified into 2 categories and 6 pathways. A total of 100 collateral networks were detected on DSA; 106, on TOF-MRA; and 73, on MPRAGE. Delineation of deeply seated collateral networks was comparable between TOF-MRA and DSA (P = .25); however, both were better than MPRAGE (P < .001).

CONCLUSIONS

This study demonstrates excellent delineation of 6 distinct deeply seated collateral network pathways in Moyamoya angiopathy in white adults using 7T TOF-MRA, comparable to DSA.

The collateral circulation in pediatric moyamoya disease

PURPOSE

The descriptions of collateral circulation in moyamoya have so far been a mixture of topography-based and vessels' source-based analyses. We aimed to investigate the anatomy and systematize the vascular anastomotic networks in pediatric moyamoya disease.

METHODS

From a series of 25 consecutive complete angiographic studies of newly diagnosed children with moyamoya, 14 children had moyamoya disease and 11 were diagnosed with moyamoya syndrome, i.e., moyamoya angiopathy with some additional concomitant systemic disease. We retrospectively analyzed the arterial branches supplying the moyamoya anastomotic networks, their origin, course, location, and connections with the recipient vessels.

RESULTS

We describe four types of anastomotic networks in children with moyamoya disease, two superficial-meningeal and two deep-parenchymal. As superficial-meningeal, we defined the leptomeningeal and the durocortical networks. Apart from the previously described leptomeningeal network observed in the convexial watershed zones, we report on the basal temporo-orbitofrontal leptomeningeal network. The second superficial-meningeal network is the durocortical network, which can be basal or calvarian in location. We define as deep-parenchymal networks the nonpreviously described subependymal network and the inner striatal and inner thalamic networks. The subependymal network is fed by the intraventricular branches of the choroidal system and diencephalic perforators, which at the level of the periventricular subependymal zone, anastomose with medullary-cortical arteries as well as with striatal arteries. The inner striatal and thalamic networks are constituted by intrastriatal connections among striatal arteries and intrathalamic connections among thalamic arteries when the disease compromises the origin of one or more sources of their supply.

CONCLUSION

The previously inexplicitly described "moyamoya abnormal network" in pediatric moyamoya disease can be described as a composition of four anastomotic networks with distinct angioarchitecture. A better understanding of the collateralization in moyamoya may help in defining a new staging system of the disease with clinical relevance.