Computed tomography

Computed tomography (CT) has increased in use exponentially for the assessment of patients with renal tract pathology. This has been promoted by the availability of multidetector thin-slice CT so that intravenous urography has been superseded by CT urography. The latter may be considered as a ‘one-stop’ imaging investigation for haematuria, with increased detection of both urinary tract cancers and urolithiasis. Multiplanar reformats are made possible with the use of thin slices, allowing clear delineation of other pathologies such as urinary tract injury. In the transplant recipient, protocols have been developed for the assessment of more immediate complications such as thrombotic and stenotic disease. During follow-up, CT continues to inform the management of post-transplant lymphoproliferative disorder and other immunosuppressant-related complications. Unenhanced CT of the urinary tract has established its role in assessment of patients with renal colic, with the ability to detect pathology outside of the urinary tract. Renal CT has been developed for the characterization of renal masses, accompanied by the now well-established Bosniak renal cyst classification system. As the usefulness of CT increases, clear awareness of safety issues has to be maintained. These include the administration of intravenous iodinated contrast medium in higher-risk patient groups, particularly those with renal impairment. The radiation burden that comes with CT poses an added risk to the patient that should not be ignored. This necessitates clear referral guidelines for its use, which should be applied in careful balance with the global assessment of the patient.