Radiologic Assessment of Native Renal Vasculature: A Multimodality Review.

A wide range of clinically important anatomic variants and pathologic conditions may affect the renal vasculature, and radiologists have a pivotal role in the diagnosis and management of these processes. Because many of these entities may not be suspected clinically, renal artery and vein assessment is an essential application of all imaging modalities. An understanding of the normal vascular anatomy is essential for recognizing clinically important anatomic variants. An understanding of the protocols used to optimize imaging modalities also is necessary. Renal artery stenosis is the most common cause of secondary hypertension and is diagnosed by using both direct ultrasonographic (US) findings at the site of stenosis and indirect US findings distal to the stenosis. Fibromuscular dysplasia, while not as common as atherosclerosis, remains an important cause of renal artery hypertension, especially among young female individuals. Fibromuscular dysplasia also predisposes individuals to renal artery aneurysms and dissection. Although most renal artery dissections are extensions of aortic dissections, on rare occasion they occur in isolation. Renal artery aneurysms often are not suspected clinically before imaging, but they can lead to catastrophic outcomes if they are overlooked. Unlike true aneurysms, pseudoaneurysms are typically iatrogenic or posttraumatic. However, multiple small pseudoaneurysms may be seen with underlying vasculitis. Arteriovenous fistulas also are commonly iatrogenic, whereas arteriovenous malformations are developmental (ie, congenital). Both of these conditions involve a prominent feeding artery and draining vein; however, arteriovenous malformations contain a nidus of tangled vessels. Nutcracker syndrome should be suspected when there is distention of the left renal vein with abrupt narrowing as it passes posterior to the superior mesenteric artery. Filling defects in a renal vein can be due to a bland or tumor thrombus. A tumor thrombus is most commonly an extension of renal cell carcinoma. When an enhancing mass is located predominantly within a renal vein, leiomyosarcoma of the renal vein should be suspected. ©RSNA, 2017.

Imaging of non-neoplastic intratesticular masses.

The use of high-frequency ultrasound is increasing for the treatment of cystic, vascular, and solid non-neoplastic intratesticular masses. Cystic lesions examined include simple testicular cysts, tunica albuginea cysts, epidermoid cysts, tubular ectasia of rete testis, and intratesticular abscesses. Vascular lesions examined include intratesticular varicocele and intratesticular arteriovenous malformations. Solid lesions examined include fibrous pseudotumor of the testis, focal or segmental testicular infarct, fibrosis of the testis, testicular hematoma, congenital testicular adrenal rests, tuberculoma, and sarcoidosis. Gray-scale and color-flow Doppler sonography facilitate the visualization of the benign characteristics of the lesions. Magnetic resonance imaging can also help as a problem-solving modality in some cases.