CT urography: principles and indications

Abstract

Abstract. CT urography (CTU) is an imaging method tailored specifically for the evaluation of the upper urothelial tract and urinary bladder. High diagnostic accuracy in detecting primary and recurrent urothelial tumours, their differentiation from benign lesions, anatomic variation and malformation characterization, and evaluation of important pathology in the surrounding tissues, renders CTU a valuable imaging study of the urothelial tract. Haematuria, initial staging and post treatment follow up of upper urinary tract and bladder malignancies are the most important indications for CTU. Triple phase and split bolus techniques are most commonly used CTU protocols that consist of a non-contrast, nephrographic, and excretory phase, obtained by three or two acquisitions. CTU scanning protocols are tailored to achieve adequate image quality with optimal opacification and distension of the urinary tract at the lowest achievable radiation dose within the range of 5-15 mSv, comparable to the doses of intravenous urography. Detailed patient history, clinical examination, and urine analysis are essential for proper patient selection and targeted CTU protocol, which are the most important tools for increasing diagnostic accuracy and lowering patient radiation dose of CT urography.Key words: computed tomography; hematuria; urography; urologic neoplasms Sažetak. CT urografija (CTU) je slikovna metoda specifično prilagođena oslikavanju i procjeni gornjeg mokraćnog sustava i mokraćnog mjehura. Visoka dijagnostička točnost u detekciji primarnih i recidivnih tumora urotela, razlikovanje malignih od benignih lezija, karakterizacija anatomskih varijacija i malformacija te procjena relevantnih patomorfoloških promjena u okolnim tkivima čine CT urografiju vrijednom metodom za oslikavanje mokraćnog sustava. Hematurija, inicijalna procjena proširenosti i praćenje tumora gornjeg mokraćnog sustava i mokraćnog mjehura najvažnije su indikacije za CTU. "Triple phase" i "split bolus" tehnike su najčešće korišteni CTU protokoli koje sačinjavaju nativna, nefrografska i ekskretorna faza, dobivene skeniranjem regije tri ili dva puta. CTU protokoli skeniranja su dizajnirani s ciljem ostvarivanja najbolje kvalitete slike te optimalne distenzije i opacifikacije mokraćnog sustava uz najmanju moguću dozu zračenja, u rasponu od 5 -15 mSv, što je usporedivo s dozama zračenja intravenske urografije. Detaljna anamneza, klinički pregled i analiza urina ključni su za pravilan probir pacijenata i ciljani odabir CTU protokola, te su ujedno najučinkovitiji način poboljšavanja dijagnostičke točnosti i smanjivanja doze zračenja CT urografije.