title: Classification of arterial plaque by spectral analysis of in vitro radio frequency intravascular ultrasound data.
abstract: To test whether radio-frequency analysis of coronary plaques predicts the histological classification, r.f. data were collected using a 30 MHz intravascular ultrasound scanner. Two hundred ninety-nine regions-of-interest from eight postmortem coronary arteries were selected and identified by histology as falling into one of seven different tissue types. These are loose fibrous tissue (n = 78), moderate fibrous tissue (n = 27), dense fibrous tissue (n = 33), microcalcification (n = 14), calcified plaque (n = 55), lipid/fibrous mixture (n = 51) and homogeneous areas of lipid pool (n = 29). On the basis of a previous study, four spectral parameters were calculated for each of the regions-of-interest: maximum power (dB), mean power (dB), spectral slope (dB/MHz) over the bandwidth 18-35 MHz and the intercept of the spectral slope with the 0 Hz axis (dB). A minimum-distance classifier using the Mahalanobis (1948) distance was applied to the data. Following resubstitution of the training data into the classifier, the total correctly classified was 54%. The data were reclassified using three broader tissue groups: (1) calcified plaque, (2) lipid pool and (3) a mixed fibrous category, incorporating loose fibrous tissue, moderate fibrous tissue, dense fibrous tissue, lipid/fibrous mixture and microcalcification. The total correctly classified was 86%. Using "leave-one-out" cross-validation, the classification rates were 48% for seven tissue subgroups and 83% for three broader categories of tissue type.
authors.affiliation: Department of Medical Physics and Medical Engineering, University of Edinburgh, UK. robin.watson@ed.ac.uk
authors.forename: R J
authors.initials: RJ
authors.lastname: Watson
authors.forename: C C
authors.initials: CC
authors.lastname: McLean
authors.forename: M P
authors.initials: MP
authors.lastname: Moore
authors.forename: T
authors.initials: T
authors.lastname: Spencer
authors.forename: D M
authors.initials: DM
authors.lastname: Salter
authors.forename: T
authors.initials: T
authors.lastname: Anderson
authors.forename: K A
authors.initials: KA
authors.lastname: Fox
authors.forename: W N
authors.initials: WN
authors.lastname: McDicken
mesh_terms: D002102:Cadaver; D002114:Calcinosis / Q000000981:diagnostic imaging; D002118:Calcium / Q000032:analysis; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000473:pathology; D003331:Coronary Vessels / Q000000981:diagnostic imaging* / Q000473:pathology; D005355:Fibrosis; D006801:Humans; D012815:Signal Processing, Computer-Assisted; D018084:Ultrasonography, Interventional
chemical_list: D002118:Calcium