Introduction: There is limited information about transitional venous anomalies (TVAs), lesions that resemble developmental venous anomalies (DVAs) on cross-sectional imaging but demonstrate early arteriovenous shunting without a parenchymal nidus, a feature that is characteristic of an AVM. We investigate the radiographic and clinical features of TVAs using arterial spin labeling (ASL)-MRI and recommend potential management.

Methods: We conducted a retrospective single-institution review of patients with DVA-like lesions on MRI but with increased ASL-signal from January 2010 to December 2016. Clinical histories and follow-up information were obtained. Location of abnormal ASL-signal with respect to the vascular lesion on MRI and, if available, the presence of arteriovenous shunting on DSA were assessed.

Results: 30 patients (mean age: 48.8 years, 57% male) were included. 29 patients had their initial MRI for symptoms unrelated to the TVA while the remaining patient for TVA-associated hemorrhage. Location of ASL-signal relative to the TVA on MRI was as follows: 17 (57%) in the parenchyma, 10 (33%) in the TVA, and six (20%) in a distal vein/sinus. Of seven patients who had DSA, five (71%) showed arteriovenous shunting, corresponding to ASL-signal in the parenchyma or distal vein/sinus on MRI. The remaining two patients without shunting on DSA had ASL-signal in the DVA itself. 10 patients had follow-up MRIs at a median of 18.7 months. All demonstrated unchanged ASL-signal except for two with decreased signal.

Conclusions: Abnormal ASL-signal in the parenchyma or distal vein/sinus associated with a DVA-like lesion likely represents arteriovenous shunting related to a TVA. Based on our series, TVAs are often incidentally detected in patients without symptoms or unrelated pathology and have a lower risk of hemorrhage than AVMs. Given their relatively benign clinical presentation, we believe that TVAs can be assessed and followed with non-invasive ASL-MRI without the potential need for DSA.

Patient Care: The findings here expand the application of a promising and easily accessible radio-diagnostic tool (ASL-imaging), and aid in the safe work-up of an otherwise poorly understood cerebrovascular malformation (TVAs). Future cases consistent with those presented are likely to further reassure patients of their condition.

Learning Objectives: 1. Understand the imaging features associated with a transitional venous anomaly. 2. Appreciate the natural history and role of MR imaging in the clinical work-up of transitional venous anomalies. 3. Consider the value of non-invasive assessment and monitoring of transitional venous anomalies in specific clinical settings.

References: PMID: 21161024, 25236477, 27399378