Novel parameter for the diagnosis of distal middle cerebral artery stenosis with transcranial Doppler sonography.
OBJECTIVE
Transcranial Doppler sonography (TCD) is commonly used for the diagnosis of middle cerebral artery (MCA) stenosis. However, TCD indices to predict distal MCA (M2) stenosis have not yet been established. We compared TCD and magnetic resonance angiography (MRA) to validate a new index for the diagnosis of M2 stenosis.


METHODS
Consecutive patients who underwent TCD and MRA were included. Based on MRA, M2 stenosis was defined as >50% narrowing beyond the bifurcation area. TCD index of the M2/M1 ratio was defined as the ratio between the mean flow velocity (MFV) obtained at a depth of 30-44 mm (M2) and a depth of 45-65 mm (M1). Sensitivity and specificity of the M2/M1 ratio were calculated from the receiver operating characteristic curve. The diagnostic yield of elevated MFV (>80 cm/s) and asymmetry index of >30% for M2 stenosis were also investigated.


RESULTS
Among the consecutive patients, 105 with M2 stenosis were compared with 123 without MCA stenosis. The M2/M1 ratio was significantly higher in the M2 stenosis group (1.10 versus 0.86, p < 0.001). Sensitivity and specificity for M2 stenosis were most satisfying when the M2/M1 ratio of 0.97 was adopted as the cutoff value. Diagnostic yield of the M2/M1 ratio was better than MFV or asymmetry index.


CONCLUSIONS
The M2/M1 ratio may be a highly specific parameter for assessing M2 stenosis with TCD.
Ahn
Suk-Won
SW
Department of Neurology, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Korea.
Park
Sang-Soon
SS
Lee
Yong-Seok
YS
D002539:Cerebral Arterial Diseases / Q000000981:diagnostic imaging*; D003251:Constriction, Pathologic / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging*; D012680:Sensitivity and Specificity; D017585:Ultrasonography, Doppler, Transcranial