טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentKovalski Gil
SubjectNew Acquisition and Processing Techniques in Nuclear
Cardiology Imaging
DepartmentDepartment of Biomedical Engineering
Supervisors Professor Haim Azhari
Professor Emeritus Ora Israel
Full Thesis textFull thesis text - English Version


Abstract

Precise and reliable assessment of myocardial perfusion and function is of utmost significance as the number of heart diseases in the western world increases. Several imaging techniques are available for assessing myocardial perfusion, with myocardial perfusion imaging (MPI) using single photon emission computed tomography (SPECT) considered as the gold standard for assessing myocardial perfusion. Nonetheless, MPI-SPECT is a signal “starving” modality. Therefore photons acquired during the entire respiratory and cardiac cycles are used for the reconstruction phase of the perfusion image ignoring the dynamic morphological changes. Consequently, myocardial motion due to respiration and cardiac contraction blurs the final perfusion image and may introduce artifacts.

In this research, a novel approach aiming to compensate for myocardial motion due to respiration and cardiac contraction via enhanced acquisition and processing techniques was developed. This suggested new method generates a perfusion image of the heart as if the heart was stationary during the duration of the acquisition (referred herein as a “frozen heart”).

Phantom simulations assessed the impact of myocardial motion due to respiration and cardiac contraction on the MPI-SPECT perfusion image. The application of compensation for these effects leads to an increase in perfusion image accuracy. The technique was further applied in clinical studies. Blind reading and comparison of corrected and uncorrected patients’ data have shown that image quality improved following correction for myocardial motion due to respiration and cardiac contraction.

Blurring of the perfusion image due to cardiac contraction may be compensated by co-mapping between MPI and other high-resolution cardiac modalities such as echocardiography. In the current research thesis, a technique for co-mapping between MPI and 3D-echocardiography is also presented and it is demonstrated that it may results in improved perfusion image.