Does a CT urogram with contrast agent (iodinated contrast media) diagnose urinary tract obstruction, kidney stones, or tumors in patients with normal renal function and no history of contrast allergy?

From the Guidelines

A CT urogram with contrast agent is a highly effective diagnostic tool for identifying urinary tract obstruction, kidney stones, and tumors in patients with normal renal function and no history of contrast allergy, with a pooled sensitivity of 96% and specificity of 99% for identifying urothelial cancer 1. The procedure involves the administration of iodinated contrast media, which helps to provide detailed visualization of the urinary system. For urinary tract obstruction, the contrast material accumulation above the obstruction clearly demonstrates the location and cause of blockage. For kidney stones, the contrast helps to differentiate stones from other structures and can reveal associated hydronephrosis. For tumors, the contrast enhancement patterns during different phases help to characterize masses in the kidneys, ureters, or bladder, with a diagnostic accuracy of 91% in detecting urothelial cancers 1. Some key points to consider when using CT urogram with contrast include:

• The importance of confirming normal renal function before the procedure, typically by checking serum creatinine levels 1
• The need for patients to be well-hydrated before the procedure
• The use of non-ionic contrast agents such as iohexol or iopamidol, which are generally well-tolerated and effective 1
• The ability of CT urogram to evaluate nonfunctioning or obstructed kidneys, which would not be possible with excretory urography 1
• The high sensitivity and specificity of CT urogram for identifying urothelial cancer, making it a valuable tool for diagnosis and staging 1.

From the FDA Drug Label

OMNIPAQUE 300 at a concentration of 300 mg Iodine/mL or OMNIPAQUE 350 at a concentration of 350 mg Iodine/mL is indicated for use in adults in excretory urography to provide diagnostic contrast of the urinary tract. Adults OMNIPAQUE 300 and OMNIPAQUE 350 at dosages from 200 mg Iodine/kg body weight to 350 mg Iodine/kg body weight have produced diagnostic opacification of the excretory system in patients with normal renal function.

CT Urogram with Contrast can diagnose urinary tract obstruction, kidney stones, or tumors in patients with normal renal function and no history of contrast allergy, as it provides diagnostic contrast of the urinary tract. The recommended dosage for adults is between 200 mg Iodine/kg body weight to 350 mg Iodine/kg body weight 2.

From the Research

CT Urogram with Contrast Agent

• A CT urogram with contrast agent (iodinated contrast media) can be used to diagnose urinary tract obstruction, kidney stones, or tumors in patients with normal renal function and no history of contrast allergy 3.
• The study found that precontrast CTU correctly diagnosed 39 of 40 urolithiasis cases (97.5%) and precontrast and contrast-enhanced CTU correctly diagnosed 23 cases of renal or ureteral tumors 3.
• CT urography is a good modality for demonstrating urinary tract disorders, especially for showing radiolucent stones and non-opacified urinary system, and provides more soft tissue information than intravenous urography (IVU) in patients with urinary tract tumors 3.

Safety and Tolerability of Contrast Agents

• The administration of intravenous contrast medium (iobitridol) in a large multicentre postmarketing surveillance study found that only 0.9% of patients experienced acute adverse events, which were non-serious and transient 4.
• The study also found that patients with pre-existing renal insufficiency or allergies were at higher risk of adverse reactions, and that females were more likely to experience contrast-agent-related symptoms than males 4.
• Other studies have compared the safety and tolerability of different contrast agents, such as iohexol, and found that they are generally well-tolerated and produce few adverse events 5, 6, 7.

Diagnostic Usefulness of CT Urogram

• CT urography has been found to be a useful diagnostic tool for evaluating urinary tract abnormalities, including urolithiasis, renal or ureteral tumors, and other urinary system disorders 3.
• The use of contrast agents, such as iohexol, can enhance the diagnostic usefulness of CT urography by providing high radiographic contrast and allowing for better visualization of the urinary tract 5, 6, 7.