, not only PI but also the area under the TIC was shown to be significantly higher in the BG and white matter ROIs than in the Th ROI. Furthermore, SHI utilizing an alternative UCA (Optison) showed significantly higher Th ROI in the ipsilateral hemisphere than in the contralateral hemisphere . More recent studies utilizing phase-inversion CX-5461 manufacturer harmonic imaging (PIHI) utilizing Optison and SonoVue  showed typical depth dependant PI attenuation in the contralateral hemisphere rather than the ipsilateral hemisphere in bilateral or unilateral (ipsilateral) approaches. A bilateral approach utilizing PIHI  and  has been suggested
for evaluating contralateral hemispheres. Our previous study of ultrasound perfusion imaging also showed that PMI utilizing transient response high power images is superior to conventional SHI in evaluation of the contra-lateral cerebral hemisphere . This study
reconfirmed that result. However, limitations of the contralateral approach, e.g. shadowing , have been pointed out . In order to overcome the problems in quantifying brain tissue perfusion, e.g. depth dependant ultrasound attenuation, we have applied transcranial ultrasound perfusion imaging to the ACZ vasoreactivity test  and . In ACZ vasoreactivity tests, the same ROI placements before and after ACZ are very important for accurate quantification. From this point of view, the Sonopod is very useful for precise quantification of brain tissue perfusion. TCDS-Sonopod monitoring succeeds in continuously PD0325901 order and quantitatively evaluating precise and reproducible intracranial hemodynamics in the major
cerebral arteries and brain tissue. “
“Assessment of cerebral perfusion is highly relevant for the immediate PIK-5 diagnostic work-up of acute ischemic stroke. MRI and CT perfusion are routinely used to identify patients who may benefit from recanalizing therapy beyond the standard time window, identifying salvageable tissue at risk of infarction by the MR diffusion-perfusion-based mismatch concept . Other perfusion imaging methods like PET-CT and SPECT are not feasible in acute stroke patients because of logistic limitations. Ultrasound perfusion imaging (UPI) has been shown to be able to likewise identify perfusion deficits of the brain parenchyma ,  and . The advantages of UPI are the possibility to perform and repeat the examination at patient’s bedside, allowing a non-invasive, cheap and quickly applicable assessment of cerebral perfusion on an intensive care unit or a stroke unit. The main limitations of this method are the attenuation of ultrasound by the human skull and the interindividual variance of skull thickness . In order to guarantee a sufficient penetration of ultrasound, a high ultrasound energy (high mechanical index = MI) was necessary in earlier UPI protocols.