IS Case 390: Renal AVM
2009 URMC Imaging Sciences
Publication Date: 2010-03-09
CT revealed a partially calcified lesion in the left kidney (A) with strong enhancement on post-contrast images (B).The left renal vein was enlarged with similar enhancement to the aorta in the arterial phase (C).
Arteriovenous malformation (AVM) may be congenital or acquired, with the most common cause being trauma. Other causes are surgery, tumors, or idiopathic. Arteriovenous fistulas compromise 70-80% of AVMs in the kidney. Renal AVMs may be intraparenchymal or in the renal sinus, and therefore may be difficult to distinguish from a renal malignancy such as renal cell carcinoma or transitional carcinoma on contrast-enhanced CT because both these lesions will show enhancement.
Sonography can exclude the possibility of a solid mass by showing anechoic spaces in the lesion that fill with color in color flow Doppler sonography. A mass can be confirmed to be an AVM when a typical arteriovenous flow pattern is depicted in the lesion.
MRI can also be useful in differentiating an AVM from other lesions by showing internal flow void in the lesion. Gadolinium-enhanced MRI can confirm an AVM during early arterial phase imaging, where it reveals the presence of abnormal tortuous vessels and an early draining vein characteristic of an AVM.
Direct arterial to venous branch communication can be identified with angiography.
- Bhatt S, MacLennan G, Dogra V. Renal pseudotumors. AJR Am J Roentgenol. 2007 May;188(5):1380-7. PMID: 17449786