Multimodality Cardiac Diagnosis: Cardiac Fusion Imaging Comes to the Desktop

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GE LightSpeed VCT and workstationSponsored by an educational grant from GE Healthcare

Sixty-four slice CT scanners, like GE Healthcare’s LightSpeed VCT, have re-invented cardiac imaging. At the same time, anatomical imaging alone does not provide physicians all of the data needed to make an accurate diagnosis. Many cases require an analysis of physiologic data such as perfusion or viability data generated by PET or SPECT scans as well as review of the 64-slice CT dataset. Conventional means of reviewing images generated by separate imaging modalities are far from ideal. A remedy for the situation, however, has moved from the drawing board into clinical practice.

Last year, GE Healthcare introduced VolumeShare2, a new advanced visualization and analysis toolkit for its Advantage Workstation (AW). This platform incorporates CardIQ Fusion, a new application that allows physicians to fuse CT and PET or SPECT imaging data on the AW workstation. The application was awarded the Society of Nuclear Medicine (SNM) annual 2006 Image of the Year.

Philipp Kaufmann, MD, director of nuclear cardiology at University Hospital Zurich in Switzerland, explains the clinical significance of CardIQ Fusion. “It can be difficult to determine if a cardiac lesion is likely to produce ischemia with anatomic data alone. The problem is exacerbated in patients with multiple lesions. The physician interpreting the CT angiogram may not be able to associate each lesion with its territory and ischemia. Intermediate grade lesions present another diagnostic challenge as the severity of the patient’s disease can be unclear based on anatomical data.”

Accurate diagnosis for such cases hinges on analyzing perfusion data and anatomical images. Until recently, physicians were hampered by archaic manual processes. Functional images generated by nuclear medicine scans and anatomical data garnered during the CT angiogram resided on separate workstations or applications. Physicians needed to switch back and forth between applications to review both types of data; then, they might mentally overlay typical coronary vessel anatomy on the physiologic data or theoretically fuse physiologic and anatomic datasets. In both cases, the process presented clinical and workflow challenges.

“GE has solved this challenge of fusing anatomical and functional data,” says Kaufmann. The company’s VolumeShare2 advanced image visualization and analysis tool with CardIQFusion transforms the AW into a cross-modality viewing platform. It provides a one-stop shop process for fusing CT, PET and nuclear medicine imaging datasets.

CardIQ Fusion fuses perfusion images produced from nuclear medicine or PET studies with the anatomical data generated during a CT study on the AW. The application provides clinicians with the tools to review and analyze angiographic data from CT for standard anatomic assessments such as vessel analysis, stenosis detection and quantification. The plus with CardIQ Fusion is that the software also allows physicians to assess physiological data such as perfusion and viability from PET or SPECT studies on the same workstation. Kaufmann and his colleagues helped refine the application and have used it in conjunction with the LightSpeed VCT scanner and AW on a daily basis for nearly two years.

“The fusion of perfusion and anatomical images helps us determine whether or not a specific lesion is associated with a perfusion defect and ischemia,” explains Kaufmann. The clinical impact is significant. “Associating the lesion with its territory allows us to make a more appropriate diagnosis, which results in a better treatment,” Kaufmann notes. In the end, CardIQ Fusion could help physicians meet the ultimate goal of improved prognosis for patients with cardiac ischemia.

CardIQ Fusion: The clinical process

University Hospital relies on a team approach to cardiac imaging. The team consists of nuclear cardiologists and CT radiologists. The group uses the LightSpeed VCT and the Discovery PET/CT in conjunction with AW and CardIQ Fusion on an array of patients including those with coronary artery disease, ischemia and arrhythmia. CardIQ Fusion can be deployed if a previous PET or SPECT study exists. CardIQ Fusion also may be used if the patient undergoes a hybrid PET/CT or SPECT/CT scan.

Two groups of physicians refer patients for CT angiography. Cardiologists form the first group. “They appreciate CardIQ Fusion because its enables a comprehensive assessment of the patient. The cardiologists send