Abstract
To clarify the clinical significance of transcranial harmonic perfusion imaging (HPI), we investigated qualitative comparisons between second- and ultra-harmonic imaging (SHI, UHI), power Doppler harmonic imaging (PHI), and quantitative correlations with dynamic CT (DCT) and/or transcranial Doppler (TCD) during acetazolamide vasoreactivity tests in neurological patients. Methods : The contrast images after a bolus Levovist® injection were compared on the basis of the transmitting and receiving frequencies (MHz) of SONOS 5500, SHI and PHI (1.8/3.6) utilizing an S4 transducer (n=28), and UHI (1.3/3.6), SHI (1.3/2.6), and PHI (1.3/2.6 and 1.6/3.2) utilizing an S3 transducer (n=10). HPI parameters from time-intensity curves in the temporal lobe, basal ganglia, and thalamus were correlated with those of DCT parameters (n=25), and with TCD and DCT parameters during vasoreactivity tests (n=12). Refill kinetics during continuous Levovist® infusion was analyzed at rest and during vasoreactivity tests. Results : a) Visualization of contrast effects was more sensitive in SHI, with a particularly low receiving frequency of 2.6 MHz, than UHI or PHI. b) Correlation of parameters was reduced in inter-individual variations, however mean transit time indicated closer correlations. Vasoreactivity of HPI tended to correlate with that of DCT and/or TCD. Conclusions : HPI allows qualitative and relatively quantitative comparisons of brain tissue perfusion, is non-invasively repeatable at bedside, and has a clinical significance in the evaluation of treatment and follow-ups for ischemic stroke patients.
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