Unusual left hemispheric developmental venous anomaly (DVA) involving the basal ganglia

This 19 year old female presented with anorexia.
The diagnostic work-up included a cerebral CT scan that discovered a deep hemispheric vascular lesion on the right side. Subsequent MRI and MRA confirmed the vascular character of the lesion that was felt to be an arteriovenous malformation. Before therapeutic decision making a conventional, catheter based cerebral angiography was also performed, which ruled out a true arteriovenous malformation and the diagnosis of an unusual form of DVA was made. For this reason, no therapeutic measures were considered.

(Unusual supratentorial DVA, 1.5T)
Fig.1 Sagittal Gadolinium-enhanced T1-weighted spin-echo images. Dilated, serpentine vascular structures involving the postero-inferior part of the frontal lobe and the anterior basal ganglia. This appearance is quite typical for arteriovenous malformations.
Fig.2 Transverse source images from a non-enhanced 3D TOF sequence using the MOTSA technique. With this technique, usually only arteries are visualized and venous structures typically remain invisible, due to intravolume spin saturation.
Fig.3 Transverse MIP image from the non-enhanced 3D TOF acquisition. Here, an early draining vein (arrow) is faintly seen, suggesting an arteriovenous malformation.
Fig.4 Transverse source images from a Gadolinium-enhanced 3D TOF sequence using the MOTSA technique. Dilated venous structures are now clearly identified (lower images).
Fig.5 Transverse MIP image from the Gadolinium-enhanced 3D TOF acquisition. Drainage of the vascular lesion is assured by the deep midline venous system (internal cerebral vein, vein of Galen, straight sinus).
Fig.6 Transverse targeted MIP images from the non-enhanced (above) and the Gadolinium-enhanced (below) 3D TOF sequences for comparison and appreciation of the effect of contrast injection on 3D TOF imaging. The left posterior communicating artery was cut off accidentally during post-processing of the non-enhanced image.
Fig.7 Coronal targeted MIP images from the non-enhanced (above) and the Gadolinium-enhanced (below) 3D TOF sequences for comparison and appreciation of the effect of contrast injection on 3D TOF imaging. Note the artifacts at every slab interface (abrupt signal intensity variation, due to spin saturation within each slab) on the non-enhanced image (above), typical of the MOTSA technique. These artifacts are hardly visible after Gadolinium injection (below).
Fig.8 Sagittal Gadolinium-enhanced 2D Phase Contrast image with Venc: 45 cm/s, as it was believed to be a relatively high-flow lesion. Indeed, diagnosis after the MRI-MRA study was that of an arteriovenous malformation.
Fig.9 Conventional, catheter based cerebral angiography after right internal carotid artery injection (a-p views). On these images, the vascular lesion appears to have slightly increased flow velocity only. Moreover, no true pathological arterial feeder is seen.
Fig.10 Conventional, catheter based cerebral angiography after right internal carotid artery injection (lateral views). Morphologically, the venous components are very suggestive of a large DVA. Indeed, this lesion was felt to represent an unusual form of DVA and no treatment was advocated.
Fig.11 Reviewing the different sagittal targeted MIPs from the Gadolinium-enhanced 3D TOF acquisition the caput medusae component of the lesion is now clearly identified (lowest image).
N.B. This case clearly illustrates the possible differential diagnostic problems and potential diagnostic failures of MRA when dealing with vascular lesions where accurate morphological and hemodynamic information is mandatory. Therefore, prior to any therapeutic decision for an arteriovenous malformations diagnosed by MRI-MRA, as in this case, conventional catheter based angiography remains indispensable. Attempts to treat this patient (by embolization or radiotherapy) could have had serious complications. Fortunately, errors in the other direction (DVA mistaken for an AVM) are much less likely to occur, hence if MRA suggests a DVA, usually no further imaging investigations are required.

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