Ultrasound perfusion imaging of small stroke involving the thalamus

Ultrasound (US) perfusion imaging of ischemic stroke has mainly been applied to large middle cerebral artery infarction. We investigated whether small stroke involving the thalamus can also be detected.

Phase inversion harmonic imaging (PIHI) was applied to patients with small infarctions involving the thalamus (maximal longitudinal infarct diameter less than 3 cm). PIHI was performed from both the left and right side in axial diencephalic planes. Infarct size and location as well as perfusion properties (MTT maps) were known from MRI. US perfusion parameters were derived from the signal enhancement time course (bolus kinetics, SonoVue for peak-signal increase and time-to-peak.

Seventeen patients (52 +/- 11 years, 24% female) with 18 strokes (16 unilateral, 1 bilateral) were included. Six US examinations (18%) were inadequate for analysis due to an insufficient transtemporal bone window. US perfusion depicted 90 % of infarcts with a longitudinal diameter of more than 2 cm. Infarcts with a longitudinal diameter of less than 2 cm were hardly identified.

PIHI allows identification of a small infarction involving the thalamus subject to infarct size.