The clinical use of contrast-enhanced ultrasound in the kidney

Abstract

Traditional B-Mode and Doppler sonography have been the stalwart of renal tract imaging for many years, and indeed, are in daily use in most centres as the modality of choice for the initial assessment of renal pathology. However, traditional ultrasound scanning can be limited in its ability to accurately characterise renal pathology, and can be inaccurate at determining benign from malignant lesions. Contrast-enhanced ultrasound conveys many benefits, being safe (especially in patients with renal dysfunction), does not require the use of ionising radiation, is quick and relatively cheap and can help to establish whether a focal renal lesion is sinister. Furthermore, it is our experience that contrast-enhanced ultrasound is not a difficult technique to master for the experienced ultrasound practitioner. In this article, we discuss the technique, interpretation and value of contrast-enhanced ultrasound in renal imaging, and describe how we use it in our practice.

Romanian National Guidelines on Contrast Enhanced Ultrasound in clinical practice

“…Benign lesions typically show no enhancement; this reliably confirms benignity with a 100% PPV [112]. CEUS can identify more septa, characterize them as thicker and pick up solid components within cystic lesions at least as accurately as CT [106,107,109,112]. CEUS can demonstrate slow and low flow within lesions and allows their characterization as solid [113].…”

“…Kidney CEUS is a safe diagnostic method (especially in patients with renal dysfunction) and cancels the risk of nephrotoxicity due to CT contrast agents [106,107]. [70,108].…”

“…The enhancement pattern of pseudotumours mirrors that of the surrounding parenchyma in all phases. Any other enhancing pattern should be considered suspicious for malignancy [107,109,110].…”

“…The differentiation between renal cell carcinomas (RCCs) and various benign entities, such as angiomyolipomas or oncocytomas is difficult [113], therefore CEUS alone is not recommended for the purpose of characterising solid lesions [109]. The typical enhancement pattern of solid RCCs includes a rapid "wash-in" phase, with a hyper-enhanced appearance at peak enhancement, followed by "wash-out" [107,109,110].…”

“…CEUS is an effective and reproducible method for detecting acute renal infarction, with accuracy comparable to CT. On CEUS it appears as a "wedge-shaped" area of nonperfusion; cortical necrosis appearance is similar, but with preserved hilar vascularity [70,107,108].…”