NEW YORK (Reuters Health) – Transcranial Doppler ultrasound (TCD) and magnetic resonance angiography (MRA) are useful in diagnosing intracranial arterial stenosis, according to a report in the June 12th Neurology.
"Physicians should recognize that all tests have limitations, and that tests can be employed to good use in patients if research is performed and the true test capabilities are known," Dr. Edward Feldmann from Brown University School of Medicine, Providence, Rhode Island told Reuters Health. "Too often, inaccurate assumptions are made about test performance, because research on the tests was not performed or is biased."
Dr. Feldmann and colleagues investigated the ability of TCD and MRA to diagnose intracranial atherosclerosis compared with catheter angiography in 407 patients at 46 sites across the U.S.
Compared with catheter angiography, TCD had a positive predictive value (PPV) of 36% and a negative predictive value (NPV) of 86%, the authors report. MRA had a PPV of 59% and an NPV of 91%.
"Positive tests are less reliable and need to be confirmed with a second test," Dr. Feldmann said. "Negative tests are very reliable and can exclude disease and ensure the patient is not in a high risk category from intracranial stenosis."
"Much as there has been a move toward dual modality concordant imaging for extracranial carotid stenosis in defining candidacy for carotid endarterectomy or stenting, the same concept may be proven for intracranial disease," write Dr. Michael D. Hill and colleagues from the University of Calgary, Alberta, Canada in a related editorial.
"Meanwhile, despite the attractiveness of noninvasive imaging, where treatment decisions will be altered, we should continue to regard abnormal noninvasive imaging results as an indication for digital subtraction angiography," the editorial concludes.
–Will Boggs, MD
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