Abdomen/PelvisLive 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.

CT Urography

📋 Indications

⛔ Contraindications & Cautions

🧑‍⚕️ Patient Preparation

⚙️ Technique & Parameters

🔎 Systematic Review

🩻 Key Findings & Significance

🧠 Differential Considerations

💡 Pearls & Pitfalls

📝 Structured Report

📚 References