title: Predicting the fidelity of JPEG2000 compressed CT images using DICOM header information.
abstract: OBJECTIVE
  To propose multiple logistic regression (MLR) and artificial neural network (ANN) models constructed using digital imaging and communications in medicine (DICOM) header information in predicting the fidelity of Joint Photographic Experts Group (JPEG) 2000 compressed abdomen computed tomography (CT) images.
  
  
  METHODS
  Our institutional review board approved this study and waived informed patient consent. Using a JPEG2000 algorithm, 360 abdomen CT images were compressed reversibly (n = 48, as negative control) or irreversibly (n = 312) to one of different compression ratios (CRs) ranging from 4:1 to 10:1. Five radiologists independently determined whether the original and compressed images were distinguishable or indistinguishable. The 312 irreversibly compressed images were divided randomly into training (n = 156) and testing (n = 156) sets. The MLR and ANN models were constructed regarding the DICOM header information as independent variables and the pooled radiologists' responses as dependent variable. As independent variables, we selected the CR (DICOM tag number: 0028, 2112), effective tube current-time product (0018, 9332), section thickness (0018, 0050), and field of view (0018, 0090) among the DICOM tags. Using the training set, an optimal subset of independent variables was determined by backward stepwise selection in a four-fold cross-validation scheme. The MLR and ANN models were constructed with the determined independent variables using the training set. The models were then evaluated on the testing set by using receiver-operating-characteristic (ROC) analysis regarding the radiologists' pooled responses as the reference standard and by measuring Spearman rank correlation between the model prediction and the number of radiologists who rated the two images as distinguishable.
  
  
  RESULTS
  The CR and section thickness were determined as the optimal independent variables. The areas under the ROC curve for the MLR and ANN predictions were 0.91 (95% CI; 0.86, 0.95) and 0.92 (0.87, 0.96), respectively. The correlation coefficients of the MLR and ANN predictions with the number of radiologists who responded as distinguishable were 0.76 (0.69, 0.82, p < 0.001) and 0.78 (0.71, 0.83, p < 0.001), respectively.
  
  
  CONCLUSIONS
  The MLR and ANN models constructed using the DICOM header information offer promise in predicting the fidelity of JPEG2000 compressed abdomen CT images.
authors.affiliation: Department of Radiation Applied Life Science, Seoul National University College of Medicine, 28 Yongon-dong, Chongno-gu, Seoul, 110-744, Korea.
authors.forename: Kil Joong
authors.initials: KJ
authors.lastname: Kim
authors.forename: Bohyoung
authors.initials: B
authors.lastname: Kim
authors.forename: Hyunna
authors.initials: H
authors.lastname: Lee
authors.forename: Hosik
authors.initials: H
authors.lastname: Choi
authors.forename: Jong-June
authors.initials: JJ
authors.lastname: Jeon
authors.forename: Jeong-Hwan
authors.initials: JH
authors.lastname: Ahn
authors.forename: Kyoung Ho
authors.initials: KH
authors.lastname: Lee
mesh_terms: D000465:Algorithms; D044962:Data Compression / Q000379:methods*; D016247:Information Storage and Retrieval / Q000379:methods*; D016571:Neural Networks, Computer; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D011860:Radiography, Abdominal / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed / Q000379:methods*