Could Nonenhanced Computer Tomography Suffice as the Imaging Study of Choice for the Screening of Asymptomatic Microscopic Hematuria?

OBJECTIVE: To compare the diagnostic accuracy of the noncontrast and contrast-enhanced phases of computed tomographic urography for detection of upper urinary tract findings in adults undergoing initial evaluation of newly diagnosed asymptomatic microscopic hematuria to determine if less-intensive noncontrast imaging has the potential to become a suitable imaging alternative in the work-up of this common condition.

MATERIALS AND METHODS: Retrospective review from 2010-2015 for adults who underwent computed tomographic urography for initial evaluation of asymptomatic microscopic hematuria. Three nonblinded physicians independently categorized the upper urinary tract findings described in the computed tomography reports into one of three groups: normal, benign, or suspicious for malignancy. The noncontrast images of a randomized portion of the studies categorized as normal and all studies categorized as suspicious and benign were submitted to two blinded radiologists who independently classified each study into one of the aforementioned categories.

RESULTS: The noncontrast images for 475 subjects were blindly reviewed. When compared to the computed tomographic urography reports, the negative predictive values of noncontrast images were 97.25% and 94.92% for radiologist 1 and radiologist 2, respectively, with an associated specificity of 88.6% and 97.95%. Of the 5 true upper tract malignancies, both blinded radiologists correctly identified 4 of the 5.

CONCLUSION: Contrast imaging added little diagnostic value when compared with noncontrast imaging for most subjects undergoing initial evaluation for asymptomatic microscopic hematuria. Less-intensive imaging with nonenhanced computed tomography could reduce the nontrivial risks associated with multiphasic contrast imaging but further work is necessary to identify risk-stratifying criteria.