Multimodality imaging of renal inflammatory lesions

Abstract

Spectrum of acute renal infections includes acute pyelonephritis, renal and perirenal abscesses, pyonephrosis, emphysematous pyelonephritis and emphysematous cystitis. The chronic renal infections that we routinely encounter encompass chronic pyelonephritis, xanthogranulomatous pyelonephritis, and eosinophilic cystitis. Patients with diabetes, malignancy and leukaemia are frequently immunocompromised and more prone to fungal infections viz. angioinvasive aspergillus, candida and mucor. Tuberculosis and parasitic infestation of the kidney is common in tropical countries. Imaging is not routinely indicated in uncomplicated renal infections as clinical findings and laboratory data are generally sufficient for making a diagnosis. However, imaging plays a crucial role under specific situations like immunocompromised patients, treatment non-responders, equivocal clinical diagnosis, congenital anomaly evaluation, transplant imaging and for evaluating extent of disease. We aim to review in this article the varied imaging spectrum of renal inflammatory lesions.

Keywords: Imaging modalities; Renal infection; Cystitis; Pyelonephritis; Pyonephrosis; Xanthogranulomatous; Magnetic resonance imaging

Core tip: Imaging in renal infections is challenging, given the relatively non-specific nature of findings in majority of the cases. A careful assessment of clinical situation in question is essential to accurately choose the imaging modality which would provide most information. In this review we discuss the appropriateness of specific imaging modalities, to allow the radiologist to choose the best modality for a given clinical situation. In addition, some entities such as acute pyelonephritis, Xanthogranulomatous pyelonephritis and emphysematous pyelonephritis have some specific imaging features. In this review we describe and illustrate such specific features, to facilitate their recognition when present.