title: Automatic cardiac T2* relaxation time estimation from magnetic resonance images using region growing method with automatically initialized seed points.
abstract: OBJECTIVE
  Heart failure due to iron-overload cardiomyopathy is one of the main causes of mortality. The cardiomyopathy is reversible if intensive iron chelation treatment is done in time, but the diagnosis is often delayed because the cardiac iron deposition is unpredictable and the symptoms are lately detected. There are many ways to assess iron-overload. However, the widely used and approved method is by using MRI which is performed by calculating the T2* (T2-star). In order to compute the T2* value, the region of interest (ROI) is manually selected by an expert which may require considerable time and skills. The aim of this work is hence to develop the cardiac T2* measurement by using region growing algorithm for automatically segmenting the ROI in cardiac MR images. Mathematical morphologies are also used to reduce some errors.
  
  
  METHODS
  Thirty MR images with free-breathing and respiratory-trigger technique were used in this work. The segmentation algorithm yields good results when compared with the manual segmentation performed by two experts.
  
  
  RESULTS
  The averages of positive predictive value, the sensitivity, the Hausdorff distance, and the Dice similarity coefficient are 0.76, 0.84, 7.78 pixels, and 0.80 when compared with the two experts' opinions. The T2* values were carried out based on the automatically segmented ROI's. The mean difference of T2* values between the proposed technique and the experts' opinion is about 1.40ms.
  
  
  CONCLUSIONS
  The results demonstrate the accuracy of the proposed method in T2* value estimation. Some previous methods were implemented for comparisons. The results show that the proposed method yields better segmentation and T2* value estimation performances.
authors.affiliation: Biomedical Engineering Program, Faculty of Engineering, Chiang Mai University, Chiang Mai, Thailand; Biomedical Engineering Center, Chiang Mai University, Chiang Mai, Thailand.
authors.forename: Kittichai
authors.initials: K
authors.lastname: Wantanajittikul
authors.affiliation: Biomedical Engineering Program, Faculty of Engineering, Chiang Mai University, Chiang Mai, Thailand; Biomedical Engineering Center, Chiang Mai University, Chiang Mai, Thailand; Department of Electrical Engineering, Faculty of Engineering, Chiang Mai University, Chiang Mai, Thailand. Electronic address: nipon@ieee.org.
authors.forename: Nipon
authors.initials: N
authors.lastname: Theera-Umpon
authors.affiliation: Biomedical Engineering Program, Faculty of Engineering, Chiang Mai University, Chiang Mai, Thailand; Biomedical Engineering Center, Chiang Mai University, Chiang Mai, Thailand; Department of Radiologic Technology, Faculty of Associated Medical Sciences, Chiang Mai University, Chiang Mai, Thailand.
authors.forename: Suwit
authors.initials: S
authors.lastname: Saekho
authors.affiliation: Biomedical Engineering Program, Faculty of Engineering, Chiang Mai University, Chiang Mai, Thailand; Biomedical Engineering Center, Chiang Mai University, Chiang Mai, Thailand; Department of Computer Engineering, Faculty of Engineering, Chiang Mai University, Chiang Mai, Thailand.
authors.forename: Sansanee
authors.initials: S
authors.lastname: Auephanwiriyakul
authors.affiliation: Department of Internal Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
authors.forename: Arintaya
authors.initials: A
authors.lastname: Phrommintikul
authors.affiliation: Northern Cardiac Center, Maharaj Nakorn Chiang Mai Hospital, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
authors.forename: Krit
authors.initials: K
authors.lastname: Leemasawat
mesh_terms: D001331:Automation; D006321:Heart / Q000502:physiology*; D008279:Magnetic Resonance Imaging / Q000379:methods*
keywords: Cardiac T2* (T2-star); Iron-overload; Magnetic resonance image (MRI); Mathematical morphology; Region growing