title: Myocardial acoustics in pediatric allograft rejection.
abstract: BACKGROUND
  Ultrasonographic tissue characterization is the assessment of physical properties of biologic tissue on the basis of quantitative analysis of its acoustic characteristics. Abnormalities in microscopic structure that occur with cardiac allograft rejection may result in characteristic alterations in myocardial acoustics. Ultrasonographic tissue characterization may allow noninvasive detection of rejection.
  
  
  METHODS
  Findings in 22 pediatric heart transplant patients undergoing routine surveillance for rejection by endomyocardial biopsy were prospectively evaluated. Off-line ultrasonographic tissue characterization analysis was done on transthoracic echocardiograms obtained at each biopsy. Within patients, tissue characterization texture measures derived from the ultrasonographic image data were compared with histologic findings. Univariate multiple regression analysis was used to identify texture measures associated with acute allograft rejection in a subgroup (n = 8) with at least one biopsy-proven episode of moderate rejection.
  
  
  RESULTS
  Measures of homogeneity (co-occurrence matrix correlation and heterogeneity (run-length nonuniformity) decreased with moderate rejection (p < 0.03). Homogeneity measures decreased if the patient had a previous episode of rejection. Several measures of heterogeneity (gray level difference and run-length statistics) were affected by the presence of edema. Run-length nonuniformity was the only measure that differentiated moderate rejection from edema. Discriminant analysis on all 22 patients correctly identified 96% of first rejection episodes (sensitivity 80%, specificity 64%), 93% of moderate and severe rejection episodes (sensitivity 71%; specificity 62%), and 69% of all rejection episodes (sensitivity 51%, specificity 91%).
  
  
  CONCLUSIONS
  Histologic changes associated with moderate and severe pediatric allograft rejection as reflected by characteristic alterations in myocardial acoustics can be assessed with ultrasonographic tissue characterization. Histologic changes associated with transplantation itself (resolution of rejection and edema) also affect myocardial acoustics and must be taken into account in rejection surveillance.
authors.affiliation: Department of Pediatrics and Pathology, Children's Memorial Hospital, Northwestern University Medical School, Chicago, IL 60614, USA.
authors.forename: N L
authors.initials: NL
authors.lastname: Gotteiner
authors.forename: M J
authors.initials: MJ
authors.lastname: Vonesh
authors.forename: S E
authors.initials: SE
authors.lastname: Crawford
authors.forename: W R
authors.initials: WR
authors.lastname: Burns
authors.forename: C E
authors.initials: CE
authors.lastname: Duffy
authors.forename: V R
authors.initials: VR
authors.lastname: Zales
authors.forename: D D
authors.initials: DD
authors.lastname: McPherson
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D001706:Biopsy; D002648:Child; D002675:Child, Preschool; D016002:Discriminant Analysis; D004452:Echocardiography / Q000379:methods*; D005260:Female; D006084:Graft Rejection / Q000000981:diagnostic imaging* / Q000473:pathology; D016027:Heart Transplantation / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D019047:Phantoms, Imaging; D012044:Regression Analysis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014184:Transplantation, Homologous