Cardiac Myocardial Perfusion Imaging Research Articles

Deep learning for improving PET/CT attenuation correction by elastic registration of anatomical data.

For PET/CT, the CT transmission data are used to correct the PET emission data for attenuation. However, subject motion between the consecutive scans can cause problems for the PET reconstruction. A method to match the CT to the PET would reduce resulting artifacts in the reconstructed images. This work presents a deep learning technique for inter-modality, elastic registration of PET/CT images for improving PET attenuation correction (AC). The feasibility of the technique is demonstrated for two applications: general whole-body (WB) imaging and cardiac myocardial perfusion imaging (MPI), with a specific focus on respiratory and gross voluntary motion. A convolutional neural network (CNN) was developed and trained for the registration task, comprising two distinct modules: a feature extractor and a displacement vector field (DVF) regressor. It took as input a non-attenuation-corrected PET/CT image pair and returned the relative DVF between them-it was trained in a supervised fashion using simulated inter-image motion. The 3D motion fields produced by the network were used to resample the CT image volumes, elastically warping them to spatially match the corresponding PET distributions. Performance of the algorithm was evaluated in different independent sets of WB clinical subject data: for recovering deliberate misregistrations imposed in motion-free PET/CT pairs and for improving reconstruction artifacts in cases with actual subject motion. The efficacy of this technique is also demonstrated for improving PET AC in cardiac MPI applications. A single registration network was found to be capable of handling a variety of PET tracers. It demonstrated state-of-the-art performance in the PET/CT registration task and was able to significantly reduce the effects of simulated motion imposed in motion-free, clinical data. Registering the CT to the PET distribution was also found to reduce various types of AC artifacts in the reconstructed PET images of subjects with actual motion. In particular, liver uniformity was improved in the subjects with significant observable respiratory motion. For MPI, the proposed approach yielded advantages for correcting artifacts in myocardial activity quantification and potentially for reducing the rate of the associated diagnostic errors. This study demonstrated the feasibility of using deep learning for registering the anatomical image to improve AC in clinical PET/CT reconstruction. Most notably, this improved common respiratory artifacts occurring near the lung/liver border, misalignment artifacts due to gross voluntary motion, and quantification errors in cardiac PET imaging.

Diagnostic value of dobutamine-stressed cardiac morphing myocardial perfusion imaging for coronary artery disease in middle-aged patients

Objective To evaluate the diagnostic value of dobutamine-stressed cardiac morphing (CM) MPI (CMMPI) for coronary artery disease (CAD) in middle-aged patients. Methods A total of 97 middle-aged patients (52 males, 45 females, age 40-65 (52.98±7.74) years) from March 2011 to February 2015 with chest distress, cardiopalmus and chest pain symptoms (suspected CAD) were retrospectively studied. Informed consents were signed by patients before examination. All patients underwent one-day dobutamine-stressed/rest CMMPI and CAG within one month. The diagnostic value of CMMPI was assessed and compared with CAG. Results CMMPI revealed 42 abnormal cases and 9 normal cases in 51 cases with coronary artery stenosis by CAG. CMMPI found 11 abnormal cases and 35 normal cases in 46 cases with normal coronary artery by CAG. In comparison with CAG, the sensitivity, specificity, accuracy, positive predictive value and negative predictive value of CMMPI were 82.35%(42/51), 76.09%(35/46), 79.38%(77/97), 79.25%(42/53)and 79.55%(35/44) respectively. The side effect was slight and transient with an incidence of 82.47%(80/97). Conclusion The dobutamine-stressed CMMPI has an important value for the diagnosis of CAD and the assessment of myocardial damage in middle-aged patients. Key words: Coronary disease; Tomography, emission-computed, single-photon; Image processing, computer-assisted; Dobutamine; MIBI

Improvement of Performance of Cardiac SPECT Camera Using Curved Detectors With Pinholes.

SPECT is primarily used in the clinic for cardiac myocardial perfusion imaging. However, for SPECT, sensitivity is impaired due to the need for collimation. System resolution FWHM is poor as well (~ 1 cm). In this work the resolution of a curved detector was theoretically derived. The advantage of a curved detector over a flat detector with pinhole collimation was demonstrated for cardiac applications using theoretical derivations as well as a ray-tracing voxel-based forward projector. For the flat detector using parameters close to what was expected for the new multi-pinhole GE Discovery system, it is shown that using a paraboloid detector one may obtain a better system resolution (about 29% better on the average), keeping same pinhole opening. Alternately, sensitivity gains of as much as 2.25 may be obtained, for similar resolutions as a flat detector by just using a different pinhole with higher hole-diameter.

Cardiac myocardial perfusion imaging using dual source computed tomography

The ability to simultaneously visualize both coronary atherosclerosis and myocardial perfusion may enable the assessment of the anatomical burden and physiological significance of coronary lesions in a single exam. In this paper we introduce a novel use of the dual source CT: pharmacologically induced stress myocardial perfusion imaging, (SP-DSCT). We describe an experimental protocol by which we used the DSCT to assess both stress and rest myocardial perfusion in order to identify areas of infarcted and ischemic myocardium. Based on our initial investigations, this protocol is feasible and can be used to identify hemodynamically significant stenosis. Nevertheless, further studies are required to determine the incremental value of this technique to traditional coronary CT angiography and/or nuclear stress myocardial perfusion imaging.