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Diagnostic Accuracy of Magnetic Resonance Angiography for Detection of Intracranial Aneurysms in Patients with Acute Subarachnoid Hemorrhage; A Comparison to Digital Subtraction Angiography.

OBJECTIVES
To determine the diagnostic accuracy of magnetic resonance angiography (MRA) compared to intra-arterial digital subtraction angiography (DSA) in detection of intracranial aneurysms in those suffering from acute subarachnoid hemorrhage (SAH).


METHODS
This observational diagnostic study was performed at a tertiary teaching hospital and reference center in Shiraz, Iran. We included 55 patients who presented to our center with the diagnosis of acute SAH. All the patients underwent MRA and DSA during their hospital course in order to detect the intracranial aneurysms. The time-of-flight MRA protocol was used and the results were compared to the results of DSA as the gold standard test. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were calculated for MRA.


RESULTS
The mean age of the patients was 46.3 ± 7.9 including 26 (47.3%%) men and 29 (52.7%) women. In 46 patients, 51 intracranial aneurysms were diagnosed by DSA (5 patients had two aneurysms). No evidence of intracranial aneurysm was found in 9 patients with subarachnoid hemorrhage. MRA correctly identified 42 of the 51 aneurysms (sensitivity 82%) and missed 9 small aneurysms (less than 10 mm). MRA revealed one false- positive finding, resulting in a specificity of 88.8%. The PPC and NPV for MRA were 97% and 47%, respectively. The diagnostic accuracy per aneurysm was 0.83 for MRA.


CONCLUSION
High sensitivity and specificity of MRA compared to DSA in diagnosis of intracranial aneurysms in those with acute SAH indicate that MRA could be reliably used as a diagnostic tool for this purpose. However we cannot recommend it as a routine substitute for DSA before surgery.