Clinical vignette
SPECT-CT fusion imaging integrating anatomy and perfusion
Oliver Gaemperli1, Tiziano Schepis1, and Philipp A Kaufmann1,2,3*
1Cardiovascular Center, University Hospital Zurich NUK C 32, Raemistrasse 100, CH-8091 Zurich, Switzerland; 2Clinic of Nuclear Medicine, University Hospital Zurich, Switzerland; 3Center for Integrative Human Physiology, University Zurich, Switzerland
*Corresponding author. Tel: +41 44 255 35 55; fax: +41 44 255 44 14. E-mail address: pak@usz.ch
A 63-year-old male asymptomatic former aircraft pilot was referred to our department for follow-up myocardial perfusion imaging (MPI) with 99mTc-tetrofosmin-SPECT. Six months earlier, the patient had undergone percutaneous transluminal coronary angioplasty and stenting with a drug-eluting stent of a significant stenosis in the middle left anterior descending artery (LAD) at the origin of a thin second diagonal branch (DA2).
SPECT images showed a small reversible apical perfusion defect indicating apical ischaemia (Panel A, arrows). Cardiac CT angiography (CTA) on a 64-slice CT scanner (LightSpeed VCT, GE Medical Systems) provided visualization of the intracoronary stent in the middle LAD and the thin DA2 arising from the stent lumen (Panel B). The fusion images integrating the obtained CTA and MPI data using the CardIQ Fusion Software package (GE Medical Systems) showed a match of the apical perfusion defect (arrows) with the territory of the DA2, whereas the LAD could be seen throughout its whole course to the apex and was not causing any ischaemia (Panel C).
Volume-rendered fused images allow a panoramic view of the left ventricle with both anatomical and functional information superimposed. In addition to its eye-catching properties, it can be of additional diagnostic value in the case of small perfusion defects on MPI that are difficult to allocate to the corresponding artery. In this particular case, anatomical-functional fusion imaging was able to allocate the perfusion defect to the overstented ostium of the DA2. As this condition bears no further interventional options, his pilot license had to be downgraded to copilot.
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