Transtemporal acoustic bone window adequacy can be determined by B-mode sonography: Prospective transcranial B-mode and color Doppler ultrasound in 375 neurologically asymptomatic volunteers

INTRODUCTION: The success and quality of transcranial color Doppler insonation of the middle cerebral artery (MCA) can be determined by visualization of craniocerebral sonoanatomical markers defined by transcranial B-mode sonography. This strategy can bring practical gains to the neurosonology examination. METHODS: Transcranial B-mode sonography and transcranial color Doppler ultrasonography were performed in 375 healthy control patients (Female: 217, age: 64 ± 9 years) over 50 years of age with no apparent neurological disease. The quality of sonic imaging of the contralateral temporal bone (CTB), mesencephalon (MB) and ipsilateral sphenoid bone small wing (LSW) was determined by the Suzuki classification, and their diagnostic properties were determined in terms of recordability of the MCA Doppler signal. RESULTS: Failure to record the MCA Doppler signal on at least one side is 4.6% (95% CI: 3.2 -6.4%) and is significantly higher in women (11.1% vs. 0.6%). For failure to receive MCA doppler signal, lower limit of 95% confidence interval of the sensitivity of MB total nonvisualisation in B-mode was 87%, along with specificity of 99%; the sensitivity of LSW sonic absence was 80% and specificity was 93%; sensitivity and specificity of non-sufficient insonation of CTB were 29% and 99.5%; sensitivity and specificity of suboptimal (visualization of less than half of the border of CTB) insonation of CTB were 89.5% and 99.5%, respectively. DISCUSSION AND CONCLUSION: B mode sonography can easily identify the inadequacy of the transtemporal acoustic window for MCA Doppler examination. Failure of imaging of the contralateral temporal bone may be more guiding than mesencephalon and ipsilateral sphenoid bone.