3D assessment of myocardial perfusion parameter combined with 3D reconstructed coronary artery tree from digital coronary angiograms

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.

Cardiac hybrid imaging

Computed tomography coronary angiography (CTCA) and myocardial perfusion imaging techniques (single photon emission computed tomography, SPECT, or positron emission tomography, PET) are established non-invasive modalities for the diagnosis of coronary artery disease (CAD). Cardiac hybrid imaging consists of the combination (or 'fusion') of both modalities and allows obtaining complementary morphological (coronary anatomy, stenoses) and functional (myocardial perfusion) information in a single setting. However, hybrid cardiac imaging has also generated controversy with regard to which patients should undergo such integrated examinations for clinical effectiveness and minimization of costs and radiation dose. The feasibility and clinical value of hybrid imaging has been documented in small cohort studies and selected series of patients. Hybrid imaging appears to offer superior diagnostic and prognostic information compared with stand-alone or side-by-side interpretation of data sets. Particularly in patients with multivessel disease, the hybrid approach allows identification of flow-limiting coronary lesions and thereby provides useful information for the planning of revascularization procedures. Furthermore, integration of the detailed anatomical information from CTCA with the high molecular sensitivity of SPECT and PET may be useful to evaluate targeted molecular and cellular abnormalities in the future. While currently still restricted to specialized cardiac centres, the ongoing efforts to reduce radiation exposure and the increasing clinical interest will further pave the way for an increasing use of cardiac hybrid imaging in clinical practice.

Sequential reconstruction of vessel skeletons from X-ray coronary angiographic sequences

X-ray coronary angiography (CAG) is one of widely used imaging modalities for diagnosis and interventional treatment of cardiovascular diseases. Dynamic CAG sequences acquired from several viewpoints record coronary arterial morphological information as well as dynamic performances. The aim of this work is to propose a semi-automatic method for sequentially reconstructing coronary arterial skeletons from a pair of CAG sequences covering one or several cardiac cycles acquired from different views based on snake model. The snake curve deforms directly in 3D through minimizing a predefined energy function and ultimately stops at the global optimum with the minimal energy, which is the desired 3D vessel skeleton. The energy function combines intrinsic properties of the curve and acquired image data with a priori knowledge of coronary arterial morphology and dynamics. Consequently, 2D extraction, 3D sequential reconstruction and tracking of coronary arterial skeletons are synchronously implemented. The main advantage of this method is that matching between a pair of angiographic projections in point-by-point manner is avoided and the reproducibility and accuracy are improved. Results are given for clinical image data of patients in order to validate the proposed method.

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.

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.

Coronary x-ray angiographic reconstruction and image orientation

We have developed an interactive geometric method for 3D reconstruction of the coronary arteries using multiple single-plane angiographic views with arbitrary orientations. Epipolar planes and epipolar lines are employed to trace corresponding vessel segments on these views. These points are utilized to reconstruct 3D vessel centerlines. The accuracy of the reconstruction is assessed using: (1) near-intersection distances of the rays that connect x-ray sources with projected points, (2) distances between traced and projected centerlines. These same two measures enter into a fitness function for a genetic search algorithm (GA) employed to orient the angiographic image planes automatically in 3D avoiding local minima in the search for optimized parameters. Furthermore, the GA utilizes traced vessel shapes (as opposed to isolated anchor points) to assist the optimization process. Differences between two-view and multiview reconstructions are evaluated. Vessel radii are measured and used to render the coronary tree in 3D as a surface. Reconstruction fidelity is demonstrated via (1) virtual phantom, (2) real phantom, and (3) patient data sets, the latter two of which utilize the GA. These simulated and measured angiograms illustrate that the vessel center-lines are reconstructed in 3D with accuracy below 1 mm. The reconstruction method is thus accurate compared to typical vessel dimensions of 1-3 mm. The methods presented should enable a combined interpretation of the severity of coronary artery stenoses and the hemodynamic impact on myocardial perfusion in patients with coronary artery disease.

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

OBJECTIVE

The purpose of this study was to develop a method of fused images of coronary CT angiography and myocardial perfusion SPECT.

CONCLUSION

Four patients with ischemic heart disease underwent 3D volume-rendering fused images using a conversion program and volume-rendering fusion function of a computer workstation. The fusion images clearly showed the relationship of relevant coronary arteries and the abnormal perfusion territory in all patients and were useful for the evaluation of coronary artery disease.

Coregistered MR Imaging Myocardial Viability Maps and Multi–Detector Row CT Coronary Angiography Displays for Surgical Revascularization Planning: Initial Experience

PURPOSE

To evaluate assignment of left ventricular (LV) myocardial segments to coronary arterial territories by using coregistered magnetic resonance (MR) imaging and multi-detector row computed tomography (CT) displays; to assess the accuracy of coregistered displays in determining the distribution of clinically important coronary artery disease (CAD) and regional effect of CAD on LV myocardium in patients with chronic ischemic heart disease (CIHD); and to determine the utility of coregistered displays in optimizing surgical revascularization planning.

MATERIALS AND METHODS

This study was HIPAA compliant and was approved by the local Institutional Review Board, with waiver of informed consent. Twenty-six patients (19 men, seven women; age, 56 years +/- 12 [+/- standard deviation]) with CIHD underwent MR imaging assessment of myocardial viability and multi-detector row CT assessment of CAD on the same day. For coregistration, a population-based LV model was fit to each data set separately; models were then registered spatially. For data analysis, correspondence between coregistered displays and the 17-segment LV model for assessment of CIHD was evaluated, accuracy of using coregistered displays to evaluate the extent of CAD and myocardial disease was assessed, and utility of coregistered displays in optimizing surgical revascularization planning was determined.

RESULTS

Coronary assignment for coregistered displays and the 17-segment LV model differed in 17% of myocardial segments. For the majority of patients, three segments (midanterolateral [62%], apical lateral [73%], and apical inferior [58%]) were discordant. Segments were supplied by the left anterior descending artery, a diagonal branch, or a ramus intermedius with diagonal distribution in all but one case. Coregistered displays were deemed concordant with selective coronary angiography and alternate myocardial imaging in all cases. Overall, surgical planning was potentially enhanced in 83% of cases because, compared with alternate imaging modalities, coregistered displays were believed to demonstrate the relationship between coronary arteries and underlying myocardial tissue more definitively and efficiently (for patients in whom surgery was performed) or more correctly and comprehensively (for a presumably better-tailored surgery).

CONCLUSION

Assessment of CIHD can be improved by using coregistered displays that directly relate the condition of LV myocardium to the anatomy of the coronary arteries in individual patients.

Integrated approach to evaluating coronary artery disease and ischemic heart disease

Integrated imaging, using multidetector computed tomography-based coronary computed tomography angiography and magnetic resonance imaging myocardial-viability maps, can help to noninvasively provide information about the morphologic and physiologic significance of obstructive and nonobstructive coronary lesions. Lesion characteristics and the presence or absence of collaterals beyond an occlusive coronary arterial lesion can be assessed in relation to the size and distribution of the resulting myocardial necrosis, thereby improving understanding of the association between atherosclerotic lesion development and subsequent myocardial damage. To this end, coregistered displays can be produced to permit establishment of the direct spatial relationship between a specific coronary artery system anatomy and specific myocardial regions of the left ventricle under consideration for treatment in an individual patient. Consequently, additional insights about the appropriateness of and/or approach to revascularization of specific myocardial regions can be provided.

Factor analysis of medical image sequences improves evaluation of first-pass MR imaging acquisitions for myocardial perfusion

RATIONALE AND OBJECTIVES

Factor analysis of medical image sequences (FAMIS) applied to gadolinium chelate-enhanced subsecond magnetic resonance (MR) imaging was evaluated as a postprocessing method for assessing myocardial perfusion in coronary artery disease (CAD).

MATERIALS AND METHODS

To assess the accuracy of motion correction, five normal volunteers underwent MR imaging at rest. Thirteen patients with well-documented CAD and no myocardial infarction underwent MR imaging at rest and after dipyridamole administration. After motion correction, a single myocardial tissue factor (FAMISt) image was obtained with FAMIS for each raw MR imaging series acquisition. To evaluate how FAMIS could improve the analysis of these acquisitions, five readers visually assessed myocardial perfusion with FAMISt and raw MR images, and a multicase, multireader receiver operating characteristic analysis was performed.

RESULTS

FAMISt images significantly improved detection of the perfusion defects when compared with raw MR images (P = .002). Areas under the receiver operating characteristic curves ranged from 0.84 to 0.93 with FAMISt images and from 0.48 to 0.85 with raw MR images.

CONCLUSION

FAMIS applied to first-pass MR imaging series provided myocardial perfusion images that improve the objective assessment of myocardial perfusion in patients with CAD.