Three-Dimensional Cardiac Image Fusion Using New CT Angiography and SPECT Methods

A novel approach to the selection of an appropriate pacing position for optimal cardiac resynchronization therapy using CT coronary venography and myocardial perfusion imaging: FIVE STaR method (fusion image using CT coronary venography and perfusion SPECT applied for cardiac resynchronization therapy)

BACKGROUND

Nearly one-third of patients with advanced heart failure (HF) do not benefit from cardiac resynchronization therapy (CRT). We developed a novel approach for optimizing CRT via a simultaneous assessment of the myocardial viability and an appropriate lead position using a fusion technique with CT coronary venography and myocardial perfusion imaging.

METHODS AND RESULTS

The myocardial viability and coronary venous anatomy were evaluated by resting Tc-99m-tetrofosmin myocardial perfusion imaging (MPI) and contrast CT venography, respectively. Using fusion images reconstructed by MPI and CT coronary venography, the pacing site and lead length were determined for appropriate CRT device implantations in 4 HF patients. The efficacy of this method was estimated by the symptomatic and echocardiographic functional parameters. In all patients, fusion images using MPI and CT coronary venograms were successfully reconstructed without any misregistration and contributed to an effective CRT. Before the surgery, this method enabled the operators to precisely identify the optimal indwelling site, which exhibited myocardial viability and had a lead length necessary for an appropriate device implantation.

CONCLUSIONS

The fusion image technique using myocardial perfusion imaging and CT coronary venography is clinically feasible and promising for CRT optimization and enhancing the patient safety in patients with advanced HF.

The incremental clinical value of cardiac hybrid SPECT/CTA imaging in coronary artery disease

Coronary artery disease (CAD) is a major cause of death worldwide. It is significantly important to assess the coronary lesion and its pathophysiological relevance comprehensively. Coronary computed tomography angiography (CTA) or myocardial perfusion imaging alone suffers from some limitations in the evaluation of CAD. Through the integration and spatial colocalization of complementary morphological and functional information, the results of published hybrid single-photon emission computed tomography (SPECT)/CTA studies in patients with CAD are promising for detecting functionally relevant coronary artery lesion and evaluating the relationship between diseased coronary artery, coronary artery anomaly, myocardial bridging, or coronary calcification and myocardial ischemia. Compared with other diagnostic procedures, such as CTA, myocardial perfusion imaging alone, and side-by-side SPECT-CTA analysis, SPECT/CTA imaging has incremental value in the evaluation of CAD. Hybrid SPECT/CTA imaging can provide the physicians with more clinical evidence that helps with the treatment strategy decision-making process, thus acting as a gatekeeper to reduce unnecessary invasive examinations and revascularization procedures. In addition, follow-up SPECT/CTA fusion imaging plays a role in predicting prognosis by displaying clearly the relationship between postoperative vessel and myocardial blood supply. However, several limitations should be considered, including the increased radiation exposure, the limited number of patients, and the lack of a uniform gold standard. More data are needed to better specify the role of hybrid SPECT/CTA imaging in the management of CAD.

[Motion-frozen Imaging by Gated Myocardial Perfusion Single Photon Emission Computed Tomography Using Multi-focus Fan Beam Collimator in Thallium-201 Study]

PURPOSE

This study aimed to evaluate the statistical noise of motion-frozen (MF) image generated by gated myocardial perfusion single photon emission computed tomography (SPECT) imaging using IQ · SPECT and to determine the optimal acquisition and reconstruction parameters for MF image using IQ · SPECT.

METHODS

A movement cardiac phantom and static cardiac phantom were used to acquire the MF images. The acquisition times used were different in 8 and 16 frames per R-R interval, and varying reconstruction parameters (subset and iteration) were used. We determined the %CV value, contrast, and normalized mean square error (NMSE) to evaluate the image quality.

RESULTS

The %CV value for a MF image with IQ · SPECT was lower than that for a conventional non-gated myocardial perfusion SPECT (MPS) image with low energy high resolution (LEHR). With regard to the acquisition parameters, the contrast did not change when the acquisition time was increased in 8 and 16 frames per R-R interval. NMSE converged in 56 beats/view in 8 frames per R-R interval. With regard to the reconstruction parameters, the contrast and the %CV value of the anterior and septal wall converged in update 40. The minimum NMSE in subsets 1, 2, and 3 were almost similar.

CONCLUSIONS

Uniformity in the MF image with IQ · SPECT was higher than that in the conventional image. The results of this MF image with IQ · SPECT study suggest that the optimal acquisition parameter should be 56 beats/view in 8 frames per R-R interval, and the optimal reconstruction parameters should be subset 3 and iteration 14.

In Vivo CT Direct Volume Rendering: A Three-Dimensional Anatomical Description of the Heart

BACKGROUND

Since cardiac anatomy continues to play an important role in the practice of medicine and in the development of medical devices, the study of the heart in three dimensions is particularly useful to understand its real structure, function and proper location in the body.

MATERIAL/METHODS

This study demonstrates a fine use of direct volume rendering, processing the data set images obtained by Computed Tomography (CT) of the heart of 5 subjects with age range between 18 and 42 years (2 male, 3 female), with no history of any overt cardiac disease. The cardiac structure in CT images was first extracted from the thorax by marking manually the regions of interest on the computer, and then it was stacked to create new volumetric data.

RESULTS

The use of a specific algorithm allowed us to observe with a good perception of depth the heart and the skeleton of the thorax at the same time. Besides, in all examined subjects, it was possible to depict its structure and its position within the body and to study the integrity of papillary muscles, the fibrous tissue of cardiac valve and chordae tendineae and the course of coronary arteries.

CONCLUSIONS

Our results demonstrated that one of the greatest advantages of algorithmic modifications of direct volume rendering parameters is that this method provides much necessary information in a single radiologic study. It implies a better accuracy in the study of the heart, being complementary to other diagnostic methods and facilitating the therapeutic plans.

Clinical usefulness of novel cardiac MDCT/SPECT fusion image

BACKGROUND

We evaluated the relationship between computed tomography angiography (CTA) and SPECT, and assessed to determine the clinical usefulness of the fusion image using CTA and myocardial perfusion imaging (MPI).

METHODS

Forty-one consecutive patients [after coronary artery bypass operation (n = 13) and suspected stenosis (n = 28)] underwent MPI and CTA. SPECT/CTA fused images were generated.

RESULTS

In total, 687 segments including bypass graft in 164 coronary arteries were analyzed. Myocardial ischemia on MPI was observed in 11 patients among 28 with CTA abnormalities, one had both ischemia and infarction, and 7 had only infarction. Segment-based analysis showed that ischemia was found in 14 segments (24%) among 59 stenoses on CTA. Forty stenotic segments (69%) were not associated with perfusion abnormality. The rest 5 stenotic segments were considered equivocal (8%). A fusion image made it possible to associate perfusion defects with its corresponding coronary artery in 4 out of 5 equivocal lesions on side-by-side analysis. Patients with incremental diagnostic information on SPECT/CTA fusion (n = 4) had significant smaller coronary diameter than that of not-improved coronary vessels (2.0 +/- 0.4 vs. 3.9 +/- 0.4 mm, p = 0.001).

CONCLUSION

Cardiac fusion imaging accurately diagnosed functionally relevant coronary stenosis. SPECT/CTA fusion images in coronary artery disease may provide added diagnostic information on functional relevance of coronary artery disease.

Visualization of myocardial perfusion derived from coronary anatomy

Visually assessing the effect of the coronary artery anatomy on the perfusion of the heart muscle in patients with coronary artery disease remains a challenging task. We explore the feasibility of visualizing this effect on perfusion using a numerical approach. We perform a computational simulation of the way blood is perfused throughout the myocardium purely based on information from a three-dimensional anatomical tomographic scan. The results are subsequently visualized using both three-dimensional visualizations and bull's eye plots, partially inspired by approaches currently common in medical practice. Our approach results in a comprehensive visualization of the coronary anatomy that compares well to visualizations commonly used for other scanning technologies. We demonstrate techniques giving detailed insight in blood supply, coronary territories and feeding coronary arteries of a selected region. We demonstrate the advantages of our approach through visualizations that show information which commonly cannot be directly observed in scanning data, such as a separate visualization of the supply from each coronary artery. We thus show that the results of a computational simulation can be effectively visualized and facilitate visually correlating these results to for example perfusion data.

Noninvasive assessment of coronary anatomy and myocardial perfusion: going toward an integrated imaging approach

Many noninvasive imaging techniques are available for the evaluation of patients with known or suspected chronic coronary artery disease. Among these, computed tomography-based techniques allow the quantification of coronary atherosclerotic calcium and noninvasive imaging of coronary arteries, whereas nuclear cardiology is the most widely used noninvasive approach for the assessment of myocardial perfusion. The available single-photon emission computed tomography flow agents are characterized by a cardiac uptake proportional to myocardial blood flow. In addition, different positron emission tomography tracers may be used for the quantitative measurement of myocardial blood flow and coronary flow reserve. Extensive research is currently being performed in the development of noninvasive coronary angiography and myocardial perfusion imaging using cardiac magnetic resonance. Finally, new multimodality imaging systems have been recently developed, bringing together anatomical and functional information. This review sought to provide a description of the relative merits of noninvasive imaging techniques in the assessment of coronary anatomy and myocardial perfusion in patients with known or suspected coronary artery disease.

Interactive 3D hybrid PET/CT imaging in the identification of myocardial viability in patients after myocardial infarction: feasibility study and clinical implications

BACKGROUND/PURPOSE

Clinical decision-making in coronary artery disease requires integrated information on myocardial viability and coronary arteries, and cross-modality registration could facilitate this process. The recent emergence of hybrid positron emission tomography (PET)/computed tomography (CT) allows acquisition of this information in one study session; however, clinically useful software capable of presenting three-dimensional (3D) fused images to assess the relationship between myocardium and coronary arteries is limited.

METHODS

Patients with prior myocardial infarction were examined using electrocardiographically gated 18F-fluorodeoxyglucose PET and 16-slice CT.

RESULTS

There were seven patients; mean age was 59 +/- 15 years and six were male. Using 3D reconstruction, coregistration and interactive display, the topographical relationship between myocardial viability and coronary arteries was clearly identified.

CONCLUSION

We present a protocol to acquire CT coronary angiography and PET data and to visualize 3D fused images with an interactive visualization interface. This image coregistration is potentially useful to facilitate the process of image interpretation and decision-making.

Training for the future of radiology: a report of the 2005 Intersociety Conference

The field of radiology has expanded dramatically and now encompasses a broad range of imaging examinations and image guided procedures. These imaging technologies are powerful tools which provide valuable information, and combining modalities further enhances their value. The changes our imaging technologies have brought bring into question our training methods, especially the value of the clinical year prior to entering radiology. As the quality of our health care systems is being challenged, demonstration of both quality processes and outcomes are needed. Maintenance of Certification, which demonstrates continuing learning and practice improvement, has become an important part of a radiologist's quality credentials.

Understanding the Heart

Methods of noninvasive evaluation of coronary artery disease-including multidetector row computed tomography, electron beam computed tomography, magnetic resonance imaging, and nuclear studies (single photon emission computed tomography, positron emission tomography)-are reviewed.

Validation of a new cardiac image fusion software for three-dimensional integration of myocardial perfusion SPECT and stand-alone 64-slice CT angiography

PURPOSE

Combining the functional information of SPECT myocardial perfusion imaging (SPECT-MPI) and the morphological information of coronary CT angiography (CTA) may allow easier evaluation of the spatial relationship between coronary stenoses and perfusion defects. The aim of the present study was the validation of a novel software solution for three-dimensional (3D) image fusion of SPECT-MPI and CTA.

METHODS

SPECT-MPI with adenosine stress/rest 99mTc-tetrofosmin was fused with 64-slice CTA in 15 consecutive patients with a single perfusion defect and a single significant coronary artery stenosis (>or=50% diameter stenosis). 3D fused SPECT/CT images were analysed by two independent observers with regard to superposition of the stenosed vessel onto the myocardial perfusion defect. Interobserver variability was assessed by recording the X, Y, Z coordinates for the origin of the stenosed coronary artery and the centre of the perfusion defect and measuring the distance between the two landmarks.

RESULTS

SPECT-MPI revealed a fixed defect in seven patients, a reversible defect in five patients and a mixed defect in three patients and CTA documented a significant stenosis in the respective subtending coronary artery. 3D fused SPECT/CT images showed a match of coronary lesion and perfusion defect in each patient and the fusion process took less than 15 min. Interobserver variability was excellent for landmark detection (r = 1.00 and r = 0.99, p < 0.0001) and very good for the 3D distance between the two landmarks (r = 0.94, p < 0.001).

CONCLUSION

3D SPECT/CT image fusion is feasible, reproducible and allows correct superposition of SPECT segments onto cardiac CT anatomy.