CT urography (CTU)

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CT Urography (CTU) is a specialized multiphase CT examination of the urinary tract (kidneys, ureters, bladder) performed after intravenous (IV) contrast administration, designed to evaluate both the renal parenchyma and urothelium.

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It is now considered the imaging modality of choice for hematuria work-up and urothelial malignancy evaluation.

Indications

Evaluation of hematuria (gross or microscopic).
Suspicion of urothelial carcinoma (renal pelvis, ureter, bladder).
Detection of urolithiasis and secondary obstructive changes.
Congenital anomalies of urinary tract.
Preoperative staging and follow-up of urothelial tumors.

Technique

Typical Multiphase Protocol:

Phase	Timing	Main Use
Non-contrast	Pre-contrast	Stones, hemorrhage
Corticomedullary	30–40 sec	Vascular anatomy, cortical lesions
Nephrographic	80–120 sec	Parenchymal lesions, small renal masses
Excretory	5–15 min	Urothelium (renal pelvis, ureters, bladder)

![The CT urography protocol used in the case of hematuria at Oslo University Hospital, Aker. The red arrow indicates the point from which the contrast-enhanced sequences are timed

Rud, E., Galtung, K.F., Lauritzen, P.M. et al. Examining the upper urinary tract in patients with hematuria—time to revise the CT urography protocol?. Eur Radiol 30, 1664–1670 (2020). https://doi.org/10.1007/s00330-019-06521-0](attachment:7663c244-9938-41bc-b27a-e4466e4696a0:330_2019_6521_Fig1_HTML.webp)

The CT urography protocol used in the case of hematuria at Oslo University Hospital, Aker. The red arrow indicates the point from which the contrast-enhanced sequences are timed

Split bolus technique:

![ Schematic of single-bolus versus split-bolus imaging protocols. The split-bolus technique is shown approximating the 30/70 dosage division and both with ∼8 min timing of excretory phase

Froemming A, Potretzke T, Takahashi N, Kim B. Upper tract urothelial cancer. European Journal of Radiology. 2017;98:50-60. doi:10.1016/j.ejrad.2017.10.021](attachment:5f25f4ed-c875-4a6d-abf1-70b9ea3b400a:1-s2.0-S0720048X17304126-gr5_lrg.jpg)

Schematic of single-bolus versus split-bolus imaging protocols. The split-bolus technique is shown approximating the 30/70 dosage division and both with ∼8 min timing of excretory phase

Froemming A, Potretzke T, Takahashi N, Kim B. Upper tract urothelial cancer. European Journal of Radiology. 2017;98:50-60. doi:10.1016/j.ejrad.2017.10.021

Diuretic (furosemide):

![Axial excretory phase images from CTU. The intrarenal collecting system was suboptimally distended in the original imaging, with heterogeneous opacification in a left calyx but difficult to characterize (a). Repeat images with improved distension clearly show a discrete papillary lesion (b, arrow), which was then biopsy proven papillary urothelial carcinoma.

Froemming A, Potretzke T, Takahashi N, Kim B. Upper tract urothelial cancer. European Journal of Radiology. 2017;98:50-60. doi:10.1016/j.ejrad.2017.10.021](attachment:cd6fd959-7efa-4f3e-94e5-2bed4684b19e:1-s2.0-S0720048X17304126-gr4.jpg)

Axial excretory phase images from CTU. The intrarenal collecting system was suboptimally distended in the original imaging, with heterogeneous opacification in a left calyx but difficult to characterize (a). Repeat images with improved distension clearly show a discrete papillary lesion (b, arrow), which was then biopsy proven papillary urothelial carcinoma.

Froemming A, Potretzke T, Takahashi N, Kim B. Upper tract urothelial cancer. European Journal of Radiology. 2017;98:50-60. doi:10.1016/j.ejrad.2017.10.021

![Computed tomography urography (CTU): MIP (maximum intensity projection) (a) and coronal (b) images. Furosemide administration allows distention of the entire urinary tract, without blooming artifacts due to high attenuation of intraluminal contrast medium; the split-bolus technique allows simultaneous luminal and parenchymal assessment.

Martingano P, Cavallaro MFM, Bozzato AM, Baratella E, Cova MA. CT Urography Findings of Upper Urinary Tract Carcinoma and Its Mimickers: A Pictorial Review. Medicina. 2020; 56(12):705. https://doi.org/10.3390/medicina56120705](attachment:46a9bdaf-a324-4f99-95f7-332c33e01f82:medicina-56-00705-g001.png)

Computed tomography urography (CTU): MIP (maximum intensity projection) (a) and coronal (b) images. Furosemide administration allows distention of the entire urinary tract, without blooming artifacts due to high attenuation of intraluminal contrast medium; the split-bolus technique allows simultaneous luminal and parenchymal assessment.