Diagnostic accuracy of flair in detection of acute subarachnoid hemorrhage in patients presenting with severe headache.

BACKGROUND: Fluid attenuation inversion recovery (FLAIR) magnetic resonance imaging (MRI) sequences are previously described for the evaluation of acute subarachnoid hemorrhage (SAH) and demonstrated good sensitivity. This study was designed to find the diagnostic accuracy of FLAIR in detection of acute SAH in patients presenting with severe headache considering the fact that controversy has been observed in previous studies.

OBJECTIVE: To determine diagnostic accuracy of FLAIR in detection of acute subarachnoid hemorrhage in patients presenting with severe headache using lumber puncture as gold standard.

METHODOLOGY: A total of 245 patients fulfilling selection criteria were enrolled in the study through the emergency department of Combined Military Hospital, Lahore. MRI was performed by Philips Intera Achieva 1.5T super conducting MR unit (Philips Medical Systems, the Netherlands), with the use of a head coil. FLAIR examination was performed at 6700/150 (TR/TE) with an inversion time (TI) of 2200ms, a field of view 230mm, matrix 189×256, scan time of 3min 50s and section thickness 5mm in axial plane. Following MRI, patients underwent lumbar puncture for cerebrospinal fluid (CSF) examination after 8-12h from the onset of event. MRI and CSF analysis results were then compared.

RESULTS: Out of 245 cases, 49.39% (n=121) were between 20-55 years of age while 50.61% (n=124) were between 56-70 years of age, mean±sd was calculated as 52.13±10.45 years, 53.88% (n=132) were male while 46.12% (n=113) were females, frequency of acute subarachnoid hemorrhage in patients presenting with severe headache was recorded as 5.71%(n=14), diagnostic accuracy of FLAIR in detection of acute subarachnoid hemorrhage in patients presenting with severe headache taking lumbar puncture as gold standard as 78.57% sensitivity, 96.53% specificity, 57.89% positive predictive value, 98.67% negative predictive value and accuracy rate was calculated as 95.29%.

CONCLUSION: Diagnostic accuracy of FLAIR in detection of acute subarachnoid hemorrhage in patients presenting with severe headache taking lumbar puncture as gold standard is higher and reliable.