While state-of the-art angiographic CTs allow to get detailed information about the heart anatomy, the consequences of detected lesions on cardiac function remain unclear. On the other hand, parameters of cardiac function are routinely assessed with PET or SPECT scans using appropriate radiotracers, although with poor anatomical informtion. Therefore, the combination of the precise angio CT anatomy with function promises to allow for easier and more accurate diagnosis of cardiac lesions.

History

• 59-year old female patient.
  
• The patient had typical anginal chest pain since 3 months and positive exercise treadmill test.
  
• The cardiovascular risk factors included hypertension, diabetes, hypercholesterolemia and cigarette smoking.
  
• The patient was referred for SPECT myocardial perfusion imaging.

Acquisition Protocol

• SPECT perfusion scan on a GE Infinia with Hawkeye attenuation correction using 99m-Tc-tetrofosmine to examine for obstructive coronary artery disease. Pharmacological stress was induced with adenosine.
  
• An additional CT angiography on a 64-slice CT scanner (GE VCT) was performed for study purposes.

Visual Inspection and QPS/QGS Analysis

• SPECT images indicated a mixed (fixed and reversible) perfusion defect in the lateral wall (territory of the left circumflex coronary artery).

Clik on the image for viewing of the other QPS analysis screen.

Image Fusion and 3D Rendering

• CT angiography revealed an occlusion of the first marginal branch of the left circumflex artery with a calcified plaque.

• The rest and stress SPECT images were interactively matched to the 75% phase of the CT angiography study using the PMOD fusion tool (PFUS).
• The matched CT and SPECT data were combined in a virtual 3D fusion scene using the PMOD 3D tool (P3D). The CT data provided the morphological information, while the functional SPECT information was added as a perfusion color. The color could be shown or hidden on demand.
• The 3D fusion clearly documented a match of the lateral perfusion defect and the territory of the first marginal branch (culprit lesion), whereas the left circumflex could be seen throughout its whole course without significant stenosis.

Diagnosis

• Coronary 1-vessel disease with occlusion of the first marginal branch of the left circumflex coronary artery with scar of the lateral wall and mild but significant ischemia.