Diagnostic Benefit of Echocontrast Enhancement for the Insufficient Transtemporal Bone Window

Abstract

Echocontrast agents (ECA) are known to improve transcranial color-coded duplex (TCCD) imaging, but its diagnostic benefit in the routine clinical setting has not clearly been defined. The authors investigated the diagnostic benefit of ECA application in 54 patients with insufficient transtemporal bone window, consecutively referred to their ultrasound laboratory. According to the precontrast imaging quality, patients were assigned to three categories: A, no intracranial structures or vessel segments visible on B-mode imaging and TCCD (n = 5); and intracranial structures visible on B-mode imaging and vessel segments less than 5 mm in length (B, n = 21), or larger than 5 mm in length (C, n = 28) visible on TCCD. The effect of the echocontrast enhancement was assessed with respect to signal enhancement, imaging quality, and diagnostic confidence. In 49 out of 54 patients (91%), a significant improvement of the imaging quality was noted, enabling 43 (80%) neurovascular diagnoses of sufficient diagnostic confidence. The diagnostic ECA effect was strongly dependent on the precontrast imaging quality: upon echoenhancement, a satisfactory image quality was obtained in none of the patients of category A, as opposed to 16 (76%) and 27 (96%) patients of categories B and C, respectively. In summary, in 80% of our consecutive patient series with insufficient transtemporal bone window, application of ECA allowed for a conclusive TCCD study. Properties of the transtemporal precontrast scans are strongly predictive of the diagnostic benefit and should be taken into the decisive consideration.

Echo Contrast–Enhanced Transcranial Ultrasound

“…This is in line with previous studies 1,4,19,20 that analyzed the benefit of UCA application during transtemporal insonation with TCCD. An improvement in the signal quality for the posterior circulation after application of UCA 8,9 was also reported, although the BA could be visualized only over a mean distance of 1.7 cm.…”

Assessment: Transcranial Doppler ultrasonography: [RETIRED]

“…141 Compared with the temporal bone window, use of the lateral frontal bone window appears to increase the detection of intracranial cross-flow patterns via the PCoA. 128 Limited data suggest that intracranial stenoocclusive disease, 26,[130][131][132][133] including Ͼ50% diameter reduction stenosis 27 or distinction between vessel patency or occlusion with reduced flow velocity, 132,133 can be detected more reliably with contrastenhanced TCCS than with TCD. TCCS can demonstrate areas of parenchymal hypoechogenicity in the MCA distribution suggestive of ischemic cerebral infarction shown on brain CT scan, accompanied by abnormal blood flow velocity pattern, with fair to good sensitivity and specificity.…”

“…136,137 However, if non-contrast-enhanced TCCS does not reveal any intracranial structures such as the midbrain or any cerebral artery, then contrast-enhanced TCCS will not be diagnostically conclusive. 130,133 A recent power-based TCCS study of 687 consecutive patients 138 showed that an indication for use of an ECA was present in 8.8% of cases. There was a diagnostic result in 75% of cases during transtemporal insonation and 81% of cases during transforaminal insonation.…”

“…129 The use of an ECA enhances the ability of TCCS to visualize the number and length of basal cerebral arteries and second-or third-order branches of major cerebral arteries, 126 particularly in patients with poor transtemporal windows. [130][131][132][133][134][135] The use of ECA may increase the peak systolic velocities in a cerebral artery segment by as much as 26 Ϯ 10% and produce "bubble noise." 136,137 However, if non-contrast-enhanced TCCS does not reveal any intracranial structures such as the midbrain or any cerebral artery, then contrast-enhanced TCCS will not be diagnostically conclusive.…”

Measurement of Vasomotor Reserve in the Transcranial Doppler-CO 2 Test Using an Ultrasound Contrast Agent (Levovist)

“…Intravenous injection of an ultrasound contrast agent (USCA) that is not eliminated via the lungs (eg, Levovist) considerably improves the quality of the Doppler signal even if penetration of the temporal bone is poor. [5][6][7][8][9][10] Therefore, it seemed to be logical to perform the TCD-CO 2 test with such an agent. The effect of a single-bolus injection is only of short duration.…”