Transcranial harmonic power duplex sonography for the evaluation of cerebral arteries

Harmonic power-based duplex sonography is a new ultrasound method that impr oves the signal-to-noise ratio of extracranial vascular imaging. The author s evaluated this new method for transtemporal imaging of the basal cerebral arteries. Fundamental power-based duplex sonography (p-TCCS) and harmonic power-based duplex sonography (HI-p-TCCS) in combination with a novel perfl uoropropane-containing ultrasound contrast agent (Optison) were investigate d for the evaluation of the basal cerebral arteries in 12 healthy volunteer s. The number of identified vascular segments and the blood flow velocities in the middle and posterior cerebral arteries were determined for p-TCCS a nd for two doses of Optison (0.5 and 1.5 mL) using HI-p-TCCS. Furthermore, the authors determined the time course of signal enhancement after Optison bolus injections. The results were compared using Friedman two-way ANOVA te st. Significantly more arterial segments were visualized using HI-p-TCCS wi th enhancement of either 0.5 mt or 1.5 mt Optison (p < 0.01, each) than usi ng p-TCCS. the spatial resolution was markedly increased with HI-p-TCCS, re sulting in a striking difference in the detection of distal arterial segmen ts and cortical and parenchymal branches. Except for the diastolic blood fl ow velocities (BFVs) in the M1 segment, the BFVs did not differ significant ly between p-TCCS and HI-p-TCCS. Comparing HI-p-TCCS with 0.5 mt and 1.5 mt Optison, the authors found a small but significant reduction of the latenc y period (18.2 vs. 15.9 seconds, respectively; p < 0.01), a significant inc rease of the blooming phase (62.7 vs. 99.8 seconds, respectively; p < 0.000 6) and a significant prolongation of the diagnostically useful signal enhan cement (233.7 vs. 427.6 seconds, respectively; p < 0.004).