Neuroimaging provides important data at reasonable cost

The authors of this retrospective study examined the diagnostic yield of neuroimaging conducted in patients seen at one neuro-ophthalmology service and estimated its economic impact on clinical practice. They report in the June issue of the Journal of Neuro-Ophthalmology that in comparison to the diagnostic yield of neuroimaging studies in other specialties, they found that CT and MRI of the brain requested by neuro-ophthalmologists provide significant and relevant data at a reasonable cost.

More specifically, they found that 28.9 percent (95% confidence interval, 22.5%-36.2%) of imaging studies had significant abnormalities relevant to the neuro-ophthalmic complaint, with the cost per clinically significant and relevant finding totaling $1,764.19. Imaging obtained for evaluation of progressive optic nerve dysfunction and cranial nerve palsy had significantly higher diagnostic yield than studies performed for other reasons.

The study included all patients referred by the division of neuro-ophthalmology at the Scheie Eye Institute at the University of Pennsylvania Health System in Philadelphia for CT, CT angiography, MRI, MRA or magnetic resonance venography during a 12-month period. This included the evaluation of 211 imaging studies of 157 patients, the total cost of which was $107,615.72.

Abnormal imaging findings were categorized as significant (those that elicited changes in management) and/or relevant (those that related to the patient's neuro-ophthalmic complaint or examination findings). The diagnostic yield of the test ordered was analyzed according to the patient's chief complaint, neuro-ophthalmic examination finding and indication for imaging. The total costs for each diagnostic group and costs per significant finding were calculated using the global Resource-Based Relative Value Units for each examination from the Centers for Medicare and Medicaid Services Web site.

Two percent had significant findings unrelated to the patient's neuro-ophthalmic condition, 19.4 percent had imaging findings that were not significant and not relevant, and results in 47.4 percent were reported as normal. The authors note that the diagnostic yield was higher if the patient complained of proptosis (66.7 percent), eye pain (60.0 percent), double vision (30.6 percent) or decreased vision (30.5 percent), but there was no diagnostic yield in patients complaining of headache or facial pain.

They say this study may underestimate the diagnostic yield of imaging as they did not include normal findings, which may have important diagnostic and prognostic indications (e.g., in cases of idiopathic intracranial hypertension or optic neuritis).