Explore the role of US, CT and MRI in the diagnostic work up of incidental renallesions. Discuss the imaging characteristics of commonly identified renal lesionson US, CT and MRI, illustrated with examples from our institution. Provide a step-wise framework for assessment and management of incidental renallesions.

Incidentally detected renal lesions are an increasingly common occurence in everyday practice for radiologists, largely driven by thethe rapidly increasinguse of abdominal imaging in medical practice.1Whilst the majority of these incidental lesions represent simple cysts, a significant proportion of incidental lesions are too small to reliablycharacterise or are identified on examinations that are not designed to fully evaluate them, i.e.they are 'indeterminate' in nature. The majority of incidental lesions are benign cysts and although these canlargely be characterised on the initial imaging examination, some lesions...

Ultrasound Ultrasound is a quick, widely available and inexpensive method for characterising small indeterminate lesions identified on portal venous phase CT, for example a small lesion demonstratingattenuation values between 20-40 HUwhichmost probablyrepresents a hyperattenuating cyst. Focused ultrasound is particularly useful for the elderly co-morbid patient who cannot undergo contrast CT due to renal impairment, or if the patient is unable totolerate an MRI scan due to claustrophobia. A lesion can be safely dismissed as a simple cyst if it is (figure 1): Well-circumscribed Anechoic Avascular...

The exponential growth of cross-sectional imaging has significantly contributed to a similar rise in the detection of incidental renal lesions. Small indeterminate renal lesions on conventional abdominal CT (portal venous phase) should be carefully compared to previous available imaging or undergo further imaging characterisation with focused ultrasound, multi-phase renal CT or contrast-enhanced MRI as proposedin figure 11. On multi-phase CT, a contrast enhancement gradient of ≥ 20 HU signifies solid vascularised tissue compatible with a primary renal lesion. Benign lesions also demonstrate variable contrast enhancement...

Dr Geoffrey Chow MBBS/BSc (Hons) Radiology trainee (3rd year) Dr Amit Patel MB ChB (Hons), MRCS, FRCR Consultant Uro-radiologist Lister Hospital, Stevenage

1. Hollingsworth JM, Miller DC, Duignalt S et al. Rising Incidence of Small Renal Masses: a Need to Reassess Treatment Effect. J Nat Cancer Inst 2006; 98: 1331–4. 2. Carrim ZI, Murchison JT et al. The prevalence of simple renal and hepatic cysts detected by spiral computed tomography. Clin Radiol. 2003; 58: 626–629. 3. Duchene DA, Lotan Y, Cadeddu JA et al. Histopathology of surgically managed renal tumors: Analysis of a contemporary series. J Urol. 2003 Nov;62(5):827-30. 4. Johnson DC, Vukina J, Smith AB et...