Pre-embolization evaluation of a cerebellar AVM

This 44 year old male had a history of subarachnoid hemorrhage 16 years earlier and a cerebellar AVM was found by conventional catheter based angiography. At that time he refused any therapeutic intervention.
A follow-up MRA examination was however performed 2 years ago, confirming the presence of the previously diagnosed very complex vascular lesion. Neurologically he remained intact.
He recently presented with a new episode of subarachnoid bleeding. The patient is now scheduled for endovascular treatment.

Cerebellar AVM, 1.5 T
Examination 1
Fig.1 Sagittal T1-weighted spin-echo images. A large abnormal signal intensity area is seen in the vermis and right cerebellar hemisphere, consistent with the diagnosis of an AVM.
Fig.2 Transverse proton density weighted fast spin-echo images, demonstrating the nidus of the lesion.
Fig.3 Transverse T2-weighted fast spin-echo images. An increased signal intensity area is seen the cerebellar parenchyma adjacent to the nidus. Otherwise same observations as on Fig.2.
Fig.4 Transverse turbo FLAIR images. The secondary parenchymal lesion in the right cerebellar hemisphere is better appreciated with this technique.
Fig.5 Sagittal averaged modulus type source images from a Gadolinium-enhanced 3D PC MRA acquisition. These image allow accurate topographical analysis of the nidus. Note also the dilated draining veins in the midline (arrows).
Fig.6 Sagittal collapsed (above left) and targeted (above right), as well as transverse (below left) and coronal (below right) collapsed MIP reconstructions from the Gadolinium-enhanced 3D PC MRA acquisition data set (Venc: 65 cm/s). The feeders of the AVM are not clearly identified on these images. Conversely, most of the major draining veins (arrows) are well visualized. Note that the quality of the MIP images is best if the reconstruction plane is identical to the acquisition plane (sagittal in this case), due to the anisotropic voxel geometry employed.
Fig.7 DSA images (lateral views) after selective injection of the right vertebral artery. An important angioarchitectural feature of this AVM is detected, notably an aneurysm (arrow) on one of the main feeders of the lesion, which was not seen on the previous MR angiograms. This is a high-risk element for hemorrhagic complications, which influences further therapeutic considerations.

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