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. Multimodality imaging of renal inflammatory lesionsCore 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.

Urinary Obstruction, Stone Disease, and Infection

“…In about 50% of the patients, lung involvement cannot be detected. Caliectasis is seen in early stages in urographic phases with a feathery contour; in the protracted course, a "phantom calyx" or a cavity communicating with a malformed calyx can be present [1]. Later, the granulomas coalesce forming mass-like lesions (tuberculoma) which may rupture into the pelvic collective system.…”

“…Immunocompromission might predispose patients to more severe or even life-threatening clinical courses like emphysematous pyelonephritis. Renal infections can develop into a permanently damaging chronic pyelonephritis or xanthogranulomatous pyelonephritis [1]. Prolonged untreated tuberculosis may lead to scarring, fibrosis, and stricture of the urinary collective system.…”

“…Fetal lobulations can be discriminated by depressions located in between calyces rather than overlying calyces. Lobar infarctions are distinguished by absence of calyceal involvement [1].…”

“…Imaging of uncomplicated cystitis or pyelonephritis is regarded as unnecessary by most authors. In contrary, patients who suffer from complicated urinary tract infections may benefit from imaging [1,2].…”

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Acute infection is mostly diagnosed based on clinical presentation and laboratory tests without imaging examinations [1]. Urinary tract infections are regarded as uncomplicated in otherwise healthy patients without structural or functional urinary abnormalities.

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