Contrast-Enhanced Ultrasound as a Diagnostic Procedure in Renal Diseases: A Case Report

Abstract

Standard ultrasound (US) finds wide use in renal diseases as a screening procedure, but it is not always able to characterize lesions, especially in differential diagnosis between benign and malignant lesions. In contrast, contrast-enhanced ultrasonography (CEUS) is appropriate in differentiating between solid and cystic lesions as well as between tumors and pseudotumors. We show the case of a nephropathic patient who showed a complex, large, growing renal mass, characterized through a CEUS. This seventy-five-year-old diabetic heart patient showed a 6 cm-complex and plurisected cyst on ultrasound of left kidney. Laboratory data showed the presence of stage IIIb chronic renal failure with GFR 30 ml/min, creatinine 2.33 mg/dl, azotemia 88 mg/dl. The patient performed abdominal CT without contrast medium, showing at the level of the left upper pole, a roundish formation with the dimensions of approximately 70x53x50 mm. At the semiannual checkup, the nephrology examination showed a slight rise in creatinine and, therefore, after six months, it was decided to perform a CT scan without contrast medium again. CT showed a slight increase in the size of the mass located at the left kidney (74x56x57 mm). Given the increased size of the left mass, albeit modest, a CEUS was performed to reach a diriment diagnosis. CEUS concluded for complex cystic formation with presence of intraluminal solid-corpuscular material, with thrombotic-hemorrhagic etiology, in progressive phase of organization, classifiable as Bosniak type II cyst. CEUS in the kidneys is a cost-effective and valuable imaging technique; it is accurate in the characterization of indeterminate lesions and complex cysts.

Keywords: Contrast-Enhanced Ultrasound, CEUS, Renal Cyst, Indeterminate Renal Mass

Introduction

Ultrasound (US) is a non-invasive technique commonly used for first level investigation in renal diseases. It is known to be an easy-to-use and relatively inexpensive approach. Computed tomography (CT) and magnetic resonance (RM) are also used for these indications, but they certainly have a higher cost and risks such as exposure to ionizing radiation in the case of CT. Standard US finds wide use as a screening procedure, but it is not always able to characterize lesions. In fact, lesions may present as isoechoic to the renal parenchyma on grey-scale imaging, and the micro-circulation can be detected with difficulty using Doppler. In addition, the standard US fails to make differential diagnosis between benign and malignant lesions [1].

In contrast, the clinical use of contrast-enhanced ultrasonography (CEUS) in the kidney has been very well defined by the guidelines of the European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB) published in 2017. Based on these indications, CEUS is appropriate in identifying suspected vascular disorders such as infarction and cortical necrosis; in differentiating between solid and cystic lesions as well as between tumors and pseudotumors. CEUS is useful in the characterization and follow-up of complex cystic masses and in the identification of renal abscesses, as also in radiofrequency ablation of non-surgical masses [2]. 

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