Contrast-enhanced transcranial Doppler US with a new transpulmonary echo contrast agent based on saccharide microparticles.

The purpose of this first patient study (phase II) was to evaluate the clinical usefulness of a new echo contrast agent at transcranial Doppler ultrasonography (US). Twenty patients were selected from a group of 242 patients undergoing conventional transcranial Doppler US who had low (n = 18) or absent (n = 2) Doppler signals from the middle cerebral artery (MCA). The extent and duration of Doppler signal increase was measured in 30 MCAs and in 14 basilar arteries following the intravenous injection of a transpulmonary galactose microparticle suspension (SH U 508 A) at three concentrations (200, 300, and 400 mg/mL). Doppler waveform analysis became possible in 93% (28 of 30) of the MCAs following injection. The maximal increase in average Doppler signal intensity (11 dB at 200 mg/mL, 15 dB at 300 mg/mL, and 17 dB at 400 mg/mL) and the increase in average duration of the signal enhancement (163 seconds at 200 mg/mL, 219 seconds at 300 mg/mL, and 240 seconds at 400 mg/mL) depended on contrast agent concentration. Doppler waveform analysis became possible in 79% (11 of 14) of the basilar arteries. The intravenous injection of this new echo contrast agent markedly increases Doppler signal intensity in patients with nondiagnostic results at conventional Doppler US.