Contrast-enhanced ultrasound reveals renal artery aneurysm after detection of ‘parapelvic lithiasis’

Abstract

To the Editor Renal parapelvic calcifications are frequent ultrasonographic findings but are not always solely an expression of lithiasis; they may also occur in the setting of arterial aneurysms. Renal artery aneurysms account for 22 % of all visceral aneurysms, with a reported incidence of 0.7–1.0 % in large-scale screening studies [1–3]. Ultrasound plays a major role in the diagnosis of renal artery aneurysms, primarily because it is comparatively inexpensive, widely available and risk-free. However, this diagnostic approach has certain risks, as exemplified by the case we describe below. A 66-year-old Caucasian female with a history of hypertension and dyslipidemia was referred to our department for a colour Doppler examination. The aim of the examination was to exclude the presence of renal artery stenosis. Serum creatinine, blood urea and urinalysis were within normal limits. Abdominal ultrasonography (Sequoia Acuson 512 system, 4.0 MHz electronic probe, Siemens), revealed a roughly hyperechoic parapelvic mass in the right kidney, with a wide posterior shadow cone which made it impossible to study the entire structure of the lesion adequately, either with colouror power-flow. The mass had been previously described as lithiasis, but a hypoechoic space was noted below the hyperechoic stria (Fig. 1a). To better ascertain the nature of the lesion, contrast-enhanced ultrasonography was performed which revealed contrast medium flow below the hyperechoic structure, as through a vessel. This suggested a calcified renal artery aneurysm (Fig. 1b). Confirmatory contrast-enhanced computed tomography (CT) was then performed which revealed a 27 9 25-mm saccular aneurysm of the right renal artery middle branch (Fig. 1c). This case highlights the need to carefully examine renal vessels when performing renal ultrasonography, particularly when parapelvic calcifications are noted. Aneurysms may be identified along the entire course of the main renal artery as an outpouching tract, containing colour flow. Slow velocities and whirling flow patterns can usually be observed on Doppler studies. However, a calcified renal artery aneurysm may be difficult to distinguish from lithiasis or complicated cyst based only on power, colour or pulsed Doppler, due to the frequent presence of a posterior shadow cone. In this instance, contrast-enhanced ultrasonography might help clinicians in the diagnosis, thanks to low mechanical index and the use of contrast medium. A. Granata A. Clementi Department of Nephrology and Dialysis, ‘‘San Giovanni di Dio’’ Hospital, ASP, Agrigento, Italy