title: Perfusion quantification using dynamic contrast-enhanced ultrasound: the impact of dynamic range and gain on time-intensity curves.
abstract: The objective of this study was to assess the impact of dynamic range and gain on perfusion quantification using linearized log-compressed data. An indicator-dilution experiment was developed with an in vitro flow phantom setup used with SonoVue contrast agent (Bracco SpA, Milan, Italy). Imaging was performed with a Philips iU22 scanner and a C5-1 curvilinear transducer using a contrast-specific nonlinear pulse sequence (power modulation) at 1.7MHz. Clinical dynamic contrast-enhanced ultrasound image loops of liver tumors were also collected for preliminary validation of the in vitro findings. Time-intensity curves were extracted from image loops with two different approaches: from linearized log-compressed data and from linear (uncompressed) data. The error of time-intensity curve parameters derived from linearized log-compressed data (deviation from linear data) was found to be less than 2.1% and 5.4% for all studied parameters in the in vitro experiment and in the clinical study, respectively, when a high dynamic range setting (at least 50dB on the iU22) is used. The gain must be carefully adjusted to ensure a high signal-to-noise ratio and to avoid signal saturation. From the time-intensity curve analysis it was also found that rise time of the bolus time-intensity curve is the least variable of all the studied time-intensity curve parameters.
authors.affiliation: Imaging Sciences Department, Faculty of Medicine, Imperial College, London W12 0NN, UK.
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Gauthier
authors.forename: Michalakis A
authors.initials: MA
authors.lastname: Averkiou
authors.forename: Edward L S
authors.initials: EL
authors.lastname: Leen
mesh_terms: D019540:Area Under Curve; D003287:Contrast Media; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted; D066298:In Vitro Techniques; D008113:Liver Neoplasms / Q000000981:diagnostic imaging*; D019047:Phantoms, Imaging; D010743:Phospholipids; D013459:Sulfur Hexafluoride; D014159:Transducers; D014463:Ultrasonography / Q000295:instrumentation / Q000379:methods*
chemical_list: D003287:Contrast Media; D010743:Phospholipids; C420843:contrast agent BR1; D013459:Sulfur Hexafluoride