3T MRI - 3D DSA Fusion Technique on Posterior Cerebral Artery Dissecting Aneurysm: Understanding a Potential Pathophysiologic Mechanism

High-Degree Middle Cerebral Artery Stenosis : Can Advanced 3D DSA-MRI Fusion Imaging Better Illustrate Plaques and Perforators?

Purpose

Endovascular treatment in severe middle cerebral artery (MCA) stenosis is controversial owing to high rates of periprocedural complications, especially occlusion of the lenticulostriate arteries (LSA). The characteristics of LSAs and the spatial relationships between MCA plaques and LSAs using the fusion of three-dimensional (3D) digital subtraction angiography (DSA) and magnetic resonance imaging (3D DSA-MRI fusion) were investigated.

Methods

We retrospectively analyzed data from 32 ischemic stroke or transient ischemic attack patients with severe MCA stenosis, who underwent MRI and DSA within 2 weeks after symptom onset. The patients were divided into culprit and non-culprit MCA stenosis groups. The 3D DSA-MRI fusion was performed on dedicated workstations, which allowed automated overlays of the target vessels. The characteristics of LSAs, plaque distribution and lesion patterns, and their relationships were evaluated.

Results

The 3D DSA-MRI fusion image was able to illustrate the spatial relationships between MCA plaques and LSA orifices. Of 42 LSA stems in 32 patients, 10 had MCA plaque over the LSA orifice and were all found in the culprit MCA stenosis group. Over half (51.9%) of the LSA stems in patients with culprit MCA stenosis originated from the stenotic MCA segment. The MCA plaque-LSA orifice spatial relationships were classified into four types, which were significantly different between the two groups (p = 0.016).

Conclusion

The 3D DSA-MRI fusion technique enables visualization of the LSA orifice and MCA plaque and their spatial relationships. This classification of the type of spatial relationships can provide insights into the pathogenesis of MCA stroke and useful guides for treatment strategies.

Functional Vascular Anatomy of the Brain

Functional vascular anatomy is the study of anatomy in its relation to the function that figures out the normal and pathological vascularization of the brain and spinal cord. The mechanism of anatomical variations (e.g. fenestration of the basilar artery, persistent primitive trigeminal artery, and aberrant subclavian artery) can be explained according to the embryological development of the cardiovascular system. The most developmental process is common among the species of the vertebrates from the fish to the mammalian in the early phase of embryo. Thus, it is possible to deduce the reasons of vascular variants in terms of phylogeny. Such an embryological parallelism like the comparative anatomy provides the new insights into the nature of our vascular system. In addition, learning more about the hemodynamic consequence may help to realize the underlying physiopathology of cerebral arterial remodeling and stroke in patients with these vascular variants. This perception may facilitate better understanding of the vascular pathologies and lead to the appropriate decision making not only in the diagnostic work, but also in the interventional procedures. The aim of this study is to introduce the meanings of functional anatomy in the clinical application of vascular diseases and anomalous of the central nervous system.

Posterior Cerebral Artery Aneurysm with Posteromedial Choroidal Artery-P3 Segment Anastomosis

We describe the case of a patient with an aneurysm of the P2 segment of the PCA with a persistent anastomosis between the posteromedial choroidal artery and the P3 segment of the posterior cerebral artery.