Imaging of infection in nephro-urology : a practical nuclear medicine–focused review

Abstract

Infection of the nephro-urological system remains a common and clinically challenging problem, particularly in patients with atypical presentations, prior instrumentation, or underlying immunosuppression. Conventional anatomical imaging plays a central role in identifying obstruction, collections, and complications but is often limited in distinguishing active infection from sterile inflammation or post-interventional change. Nuclear medicine techniques provide complementary functional and molecular information that can clarify disease activity, define extent, and influence patient management. This review presents a practical, nuclear medicine-focused overview of imaging approaches for nephro-urological infection. Established techniques, including ⁹⁹ᵐTc-DMSA imaging, radiolabelled white blood cell scintigraphy, and 18F-FDG PET/CT, are discussed with emphasis on tracer biology, physiological renal handling, and common interpretive pitfalls. Clinical scenarios such as acute and chronic pyelonephritis, renal abscess, transplant infection, and device-related infection are used to illustrate appropriate tracer selection and integration with anatomical imaging. Special populations, including paediatric patients, immunocompromised individuals, and renal transplant recipients, are considered, alongside practical algorithms and teaching points aimed at improving clinical applicability. Emerging developments in bacteria-specific tracers, quantitative imaging, and hybrid modalities are also reviewed. By adopting a biologically informed and question-driven approach, nuclear medicine can play an increasingly important role in the diagnosis and management of nephro-urological infection.

KEY TEACHING POINTS • Nuclear medicine imaging of nephro-urological infection reflects biological activity and inflammatory response, providing information beyond structural imaging. • Physiological renal tracer handling and urinary excretion are major challenges; optimized preparation, delayed imaging, and hybrid techniques are essential for accurate interpretation. • ¹⁸F-FDG PET/CT offers high sensitivity and whole-body assessment and is particularly valuable in complicated infection, renal transplant recipients, and fever of unknown origin. • Radiolabelled white blood cell scintigraphy provides greater specificity for active infection and is especially useful in chronic, recurrent, or device-related infection. • ⁹⁹ᵐTc-DMSA is best suited for evaluating renal cortical involvement and long-term sequelae rather than distinguishing active infection. • Selection of imaging technique should be question-driven, tailored to disease acuity, chronicity, and clinical context. • Nuclear medicine imaging is most effective when integrated into a multimodality diagnostic pathway alongside ultrasound, CT, and MRI. • Awareness of common pitfalls, including post-procedural inflammation and malignancy-related uptake, is essential to avoid false-positive interpretations. • When appropriately applied, nuclear medicine imaging can directly influence management, supporting targeted intervention and rational antimicrobial stewardship.