Novel 3D heart left ventricle muscle segmentation method for PET-gated protocol and its verification

OBJECTIVE: The aim of this study was to propose and verify a universal method of left ventricular myocardium segmentation, able to operate on heart gated PET data with different sizes, shapes and uptake distributions. The proposed method can be classified as active model method and is based on the BEAS (B-spline Explicit Active Surface) algorithm published by Barbosa et al. The method was implemented within the Pmod PCARD software package. Method verification by comparison with reference software and phantom data is also presented in the paper. METHODS: The proposed method extends the BEAS model by defining mechanical features of the model: tensile strength and bending resistance. Formulas describing model internal energy increase during its stretching and bending are proposed. The segmentation model was applied to the data of 60 patients, who had undergone cardiac gated PET scanning. QGS by Cedars-Sinai and ECTb by Emory University Medical Centre served as reference software for comparing ventricular volumes. The method was also verified using data of left ventricular phantoms of known volume. RESULTS: The results of the proposed method are well correlated with the results of QGS (slope: 0.841, intercept: 0.944 ml, R(2): 0.867) and ECTb (slope: 0.830, intercept: 2.109 ml, R(2): 0.845). The volumes calculated by the proposed method were very close to the true cavity volumes of two different phantoms. CONCLUSIONS: The analysis of gated PET data by the proposed method results in volume measurements comparable to established methods. Phantom experiments demonstrate that the volume values correspond to the physical ones.