title: Effect of destructive pulse duration on the detection of myocardial perfusion in myocardial contrast echocardiography: In vitro and in vivo observations.
abstract: Myocardial perfusion is detected with contrast echocardiography by comparing a contrast-enhanced image with a baseline obtained before contrast injection (true baseline) or after myocardial bubble destruction after a high-power destructive pulse (postdestructive pulse baseline). Although it is assumed that all bubbles are destroyed by a destructive pulse insuring optimal contrast detection, this assumption has not been tested. In 18 participants we compared the videointensity (VI) differences among the contrast-enhanced image, the postdestructive pulse baseline, and the true baseline using both triggered high-mechanical index imaging and real-time imaging. VI difference was significantly greater for the true baseline with both techniques at all ventricular levels. The benefit of using a true baseline was less when the duration of the destructive pulse was increased. Similarly, we quantified VI in a flow phantom using continuous Optison (commercially available perfluoropropane-filled albumin microbubbles) (Amersham, Princeton, NJ) infusion and variable durations of destructive pulses. VI decreased with the duration of the destructive pulse and reached a plateau after a duration of 8 to 15 frames. The plateau reached after a long destructive pulse was dependent on flow rate and concentration and never reached a true baseline, unless concentration (<100 microL/L) and flow rate (<0.5 cm/s) were very low.
  
  
  CONCLUSIONS
  (1) in clinical studies, the difference in VI between contrast-enhanced and baseline images is greater when true baseline is used; (2) the longer the destructive pulse, the closer the postdestructive pulse baseline to true baseline; and (3) this effect exists in all regions of the left ventricle.
authors.affiliation: Cardiac Ultrasound Laboratory at the Massachusetts General Hospital, Harvard Medical School, Boston 02114, USA.
authors.forename: Edda B
authors.initials: EB
authors.lastname: Bahlmann
authors.forename: Brendan M
authors.initials: BM
authors.lastname: McQuillan
authors.forename: Mark D
authors.initials: MD
authors.lastname: Handschumacher
authors.forename: Chi-Ming
authors.initials: CM
authors.lastname: Chow
authors.forename: J Luis
authors.initials: JL
authors.lastname: Guerrero
authors.forename: Michael H
authors.initials: MH
authors.lastname: Picard
authors.forename: Arthur E
authors.initials: AE
authors.lastname: Weyman
authors.forename: Marielle
authors.initials: M
authors.lastname: Scherrer-Crosbie
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000418:Albumins / Q000378:metabolism; D001776:Blood Circulation Time; D003287:Contrast Media / Q000378:metabolism; D003331:Coronary Vessels / Q000000981:diagnostic imaging* / Q000502:physiology*; D004452:Echocardiography / Q000379:methods; D005260:Female; D005466:Fluorocarbons / Q000378:metabolism; D006321:Heart / Q000502:physiology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008297:Male; D008875:Middle Aged; D011674:Pulse; D012039:Regional Blood Flow / Q000502:physiology
chemical_list: D000418:Albumins; D003287:Contrast Media; C099458:FS 069; D005466:Fluorocarbons