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Abdomen/PelvisDemonstration data

CT Urography

CT urography is a multiphase contrast-enhanced study that comprehensively evaluates the kidneys, ureters, and bladder, combining nephrographic-phase parenchymal assessment with excretory-phase opacification of the collecting system. It is the preferred imaging test for gross hematuria in patients at risk of urothelial malignancy and characterizes renal masses, stones, and obstruction in a single examination. A non-contrast phase detects calculi and provides baseline attenuation for lesion characterization.

Indications

  • Gross or unexplained hematuria, especially with risk factors for urothelial carcinoma
  • Surveillance of known upper-tract urothelial malignancy
  • Suspected renal or ureteral calculus disease with anatomical assessment
  • Hydronephrosis and evaluation of ureteral strictures or obstruction
  • Characterization of complex renal masses and congenital collecting-system anomalies
  • Assessment of upper-tract filling defects or suspected transitional cell carcinoma

Contraindications & Cautions

  • Iodinated contrast allergy (premedicate) and significant renal impairment (weigh contrast risk; excretory phase may be poor)
  • Pregnancy: consider ultrasound or MR urography to avoid ionizing radiation
  • Cumulative radiation dose from multiphase acquisition; use split-bolus or dose-reduction techniques and limit phases to those needed
  • Metformin per local policy in renal impairment
  • Inability to lie still or maintain hydration for adequate distension

Patient Preparation

  • Screen renal function, contrast allergy, and pregnancy status; obtain consent per policy
  • Oral hydration (and/or IV saline) to promote diuresis and improve collecting-system distension
  • Establish large-bore IV access for power injection
  • Consider a low-dose diuretic (furosemide) or compression to improve ureteral opacification per protocol
  • Position supine, arms up; prone or delayed imaging may improve distal ureteral filling
  • Explain the multiphase nature and expected duration (excretory imaging at ~8-15 minutes)

Technique & Parameters

  • Non-contrast phase from kidneys to bladder base to detect calculi and provide baseline attenuation
  • Nephrographic phase (~90-100 s) for homogeneous parenchymal enhancement and renal mass detection
  • Excretory (pyelographic) phase (~8-15 min) for opacification of the collecting systems, ureters, and bladder
  • Split-bolus technique combines nephrographic and excretory phases to reduce total dose
  • IV contrast ~100-125 mL at 2.5-3 mL/s; thin-section (1-2 mm) reconstruction for coronal/curved reformats and MIP
  • 120 kVp with tube-current modulation; low-dose settings for the non-contrast and excretory phases

Systematic Review

  • Non-contrast: search for calculi within the kidneys, ureters, and bladder and measure size/density
  • Renal parenchyma: assess for masses, scarring, enhancement pattern, and symmetry of nephrograms
  • Collecting systems: evaluate for hydronephrosis, filling defects, and urothelial thickening
  • Ureters: trace fully on excretory/coronal reformats for strictures, defects, and obstruction level
  • Bladder: assess wall thickness, filling defects, and diverticula (allowing for layering artifact)
  • Perinephric and periureteric fat for stranding, urinoma, or collections
  • Adjacent organs, lymph nodes, and bones for metastatic or incidental disease

Key Findings & Significance

  • Non-enhancing calculus in the collecting system or ureter with proximal hydronephrosis: obstructing stone
  • Enhancing filling defect or focal urothelial thickening: upper-tract urothelial carcinoma
  • Enhancing solid renal mass (>20 HU enhancement): renal cell carcinoma until proven otherwise
  • Smooth long-segment ureteral narrowing: benign stricture; abrupt shouldered narrowing: neoplasm
  • Bladder wall mass or focal thickening with enhancement: bladder carcinoma
  • Delayed or absent nephrogram/excretion: obstruction, renovascular, or parenchymal compromise
  • Congenital variants: duplex system, ectopic ureter, or ureterocele

Differential Considerations

  • Collecting-system filling defect: urothelial tumor vs non-opaque calculus vs blood clot vs fungus ball
  • Renal mass: RCC vs oncocytoma vs angiomyolipoma (fat-containing) vs complex cyst
  • Ureteral stricture: post-inflammatory/iatrogenic vs urothelial malignancy vs extrinsic compression
  • Hydronephrosis: obstructive (stone, tumor, stricture) vs non-obstructive (reflux, extrarenal pelvis)
  • Bladder filling defect: tumor vs clot vs stone vs instrument/catheter effect
  • Papillary abnormality: papillary necrosis vs calyceal diverticulum vs tuberculosis

Pearls & Pitfalls

  • Correlate the excretory phase with nephrographic images to distinguish tumor from adherent clot or debris
  • Incomplete ureteral distension causes pseudo-defects; use prone, delayed, or diuretic techniques and trace the whole ureter
  • Measure stones on non-contrast images; contrast in the collecting system obscures and mimics calculi
  • Layering of dense contrast in the bladder can hide small tumors; assess with the patient repositioned or on early phases
  • A hyperdense (>70 HU) non-enhancing renal lesion suggests a hemorrhagic/proteinaceous cyst rather than tumor
  • Do not overlook synchronous or multifocal urothelial lesions along the entire urinary tract

Structured Report

  • State protocol, phases performed, contrast, and distension adequacy
  • Report calculi with size, location, and density, and describe any obstruction
  • Characterize renal masses (size, enhancement, fat, complexity; Bosniak category for cysts)
  • Describe collecting-system, ureteral, and bladder findings, including urothelial lesions and their level
  • Comment on nodes, adjacent organs, and incidental findings
  • Impression: primary diagnosis, malignancy concern, and recommended follow-up (urology referral, cystoscopy, biopsy)

References

  • ACR Appropriateness Criteria: Hematuria
  • ACR-SAR-SPR Practice Parameter for the Performance of CT Urography
  • AUA Guideline on Microhematuria and Diagnosis, Evaluation, and Follow-up of Asymptomatic Microhematuria
  • Bosniak Classification of Cystic Renal Masses, Version 2019

Educational clinical decision support only. Protocols vary by institution and equipment; always confirm with a qualified radiologist and local guidelines before clinical use.