Pre-embolization evaluation of a small right parieto-occipital cortical AVM

This 39 year old patient had three generalized epileptic seizures. Conventional MRI revealed intraparenchymal signal abnormalities consistent with sequelae of a right occipital hemorrhage. Subsequent MRA confirmed the diagnosis of an underlying small cortical AVM.
Endovascular embolization by cyanoacrylate was elected for therapy.

Small parieto-occipital cortical AVM, 1.5 T
Fig.1 Sagittal T1-weighted spin-echo images. An abnormal serpiginous signal void structure is seen on the medial surface of the right cerebral hemisphere in the parieto-occipital region, suggesting a vascular malformation. Note the slightly lower position of the cerebellar tonsils, probably without pathological significance in this case.
Fig.2 Transverse T2-weighted fast spin-echo (left) and gradient-echo (right) images. The nidus is not clearly visualized. The abnormal low signal intensity intraparenchymal structures (hemosiderin deposits) and cortical lining (leptomeningeal hemosiderosis), secondary to a previous hemorrhagic episode, are better seen on the gradient-echo images. A small increased signal intensity area is also demonstrated in the subcortical white matter.
Fig.3 Transverse targeted MIP reconstruction from a high resolution, multi-slab 3D TOF MRA acquisition data set. The small right parieto-occipital cortical AVM is well visualized. However, the venous drainage of the lesion is not seen, due to progressive intravolume saturation, despite the MOTSA technique employed. This was felt to be a small slow-flow cortical AVM, in fact the smallest diagnosed by MRA in our series.
Fig.4 Coronal (above) and sagittal (below) targeted MIP reconstructions from the non-enhanced high resolution multi-slab 3D TOF MRA acquisition. Only the arterial feeder and the nidus are detected on these images.
Fig.5 Sagittal survey, single-slice 2D PC MR angiogram (matrix: 256, Venc: 40 cm/s). This image provides equivocal information and would be difficult to interpret alone.
Fig.6 Sagittal averaged modulus (left) and corresponding magnitude of complex differences (right) type source images from a Gadolinium-enhanced 3D PC MRA acquisition. The intraparenchymal and leptomeningeal hemosiderin deposits are well appreciated on the anatomical images as signal void structures. Pathological vessels, corresponding to the nidus of the AVM, are also detected on the flow images (arrows).
Fig.7 Sagittal targeted MIP reconstruction from the Gadolinium-enhanced 3D PC MRA acquisition data set. The small AVM is better seen than on the 3D PC image, but the angioarchitecture is impossible to evaluate.

Exam 2 (embolization)
Fig.8 DSA images after selective injection of the right internal carotid artery (above) and the right vertebral artery (below). In agreement with the MRI-MRA findings, this cortical AVM was found to be a small and slow flow lesion, fed by a branch of the calcarine artery.
Fig.9 DSA image (lateral view) with superselective catheterization during embolization of the AVM. Total disappearance of the lesion was achieved in one session.

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