title: Background subtraction from time-intensity curves in videodensitometry: a pitfall in flow assessment using contrast echocardiography.
abstract: Background subtraction for contrast echocardiography is considered a prerequisite for an appropriate assessment of flow from the time-intensity curves. We evaluated the influence of different background intensities on flow determinations with contrast echocardiography. Experiments were performed with a mixing chamber as a phantom for myocardial perfusion. Three regions of interest with different background intensities but equal flow were examined. Time-intensity curves were obtained and, after background subtraction, a number of curve parameters were determined: peak intensity, area under the curve, curve width and decay after peak intensity. The values of these parameters differed significantly between a region with a low and a region with a high background. In addition, a model is presented to describe these findings. It is concluded that subtraction of the background intensity from a time-intensity curve induces errors that make a quantitative interpretation of the curves ambiguous. These drawbacks are avoided if regions of interest with equal background intensities are compared.
authors.affiliation: Department of Cardiology, Academic Medical Centre of Amsterdam, Netherlands.
authors.forename: L J
authors.initials: LJ
authors.lastname: Bos
authors.forename: J J
authors.initials: JJ
authors.lastname: Piek
authors.forename: J A
authors.initials: JA
authors.lastname: Spaan
mesh_terms: D000418:Albumins; D001783:Blood Flow Velocity; D002302:Cardiac Output; D003287:Contrast Media; D003326:Coronary Circulation; D003720:Densitometry; D004452:Echocardiography / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D019047:Phantoms, Imaging; D012815:Signal Processing, Computer-Assisted; D013382:Subtraction Technique; D013997:Time Factors; D014743:Videotape Recording
chemical_list: D000418:Albumins; D003287:Contrast Media