Diagnostic performance of fusion of myocardial perfusion imaging (MPI) and computed tomography coronary angiography

Abstract

Background: We evaluated the incremental diagnostic value of fusion images of coronary computed tomography angiography (CTA) and myocardial perfusion imaging (MPI) over MPI alone or MPI and CTA side-by-side to identify obstructive coronary artery disease (CAD > 50% stenosis) using invasive coronary angiography (ICA) as the gold standard.

Methods: 50 subjects (36 men; 56 +/- 11 years old) underwent rest-stress MPI and CTA within 12-26 days of each other. CTAs were performed with multi-detector CT-scanners (31 on 64-slice; and 19 on 16-slice). 37 patients underwent ICA while 13 subjects did not because of low (<5%) pre-test likelihood (LLK) of disease. Three blinded readers scored the images in sequential sessions using (1) MPI alone (2) MPI and CTA side-by-side, (3) fused CTA/MPI images.

Results: One or more critical stenoses during ICA were found in 28 patients and non-critical stenoses were found in 9 patients. MPI, side-by-side MPI-CTA, and fused CTA/MPI showed the same normalcy rate (NR:13/13) in LLK subjects. The fusion technique performed better than MPI and MPI and CTA side-by-side for the presence of CAD in any vessel (overall area under the curve (AUC) for fused images: 0.89; P = .005 vs MPI, P = .04 vs side-by-side MPI-CTA) and for localization of CAD to the left anterior descending coronary artery (AUC: 0.82, P < .001 vs MPI; P = .007 vs side-by-side MPI-CTA). There was a non-significant trend for better detection of multi-vessel disease with fusion.

Conclusions: Using ICA as the gold standard, fusion imaging provided incremental diagnostic information compared to MPI alone or side-by-side MPI-CTA for the diagnosis of obstructive CAD and for localization of CAD to the left anterior descending coronary artery.

Figure 1

Detection and localization of coronary artery disease using myocardial perfusion imaging alone, myocardial perfusion imaging and computed tomography angiography side-by-side, and fusion of myocardial perfusion imaging and computed tomography angiography. Significant disease is defined as ≥50% luminal coronary stenosis by invasive coronary angiography. CAD, Coronary artery disease; CTA, computed tomography angiography; LAD, left anterior descending coronary artery; LCX, left circumflex coronary artery; MPI, myocardial perfusion imaging; RCA, right coronary artery.

Figure 2

Sensitivity for identification of single vessel and multi-vessel vessel coronary artery disease (CAD) of myocardial perfusion imaging alone (MPI), myocardial perfusion imaging and computed tomography angiography side-by-side (MPI + CTA), and fusion imaging (MPI + CTA FUSED).

Figure 3

Example of fusion imaging in a patient with single vessel coronary artery disease. A, Short axis, vertical and horizontal long axis slices of the Stress/Rest SPECT study. This perfusion study was read as probably normal. B, Polar maps of the same SPECT study. C, Multi-planar reconstructions of the coronary arteries on CT angiography showing a plaque in the proximal left anterior descending coronary artery. This was read as equivocal for coronary artery disease. D, Three-dimensional rendering of the coronary arteries on CT angiography showing the paths of the coronary arteries and the plaque location in the left anterior descending coronary artery. E, Fused display; the black area on the fused display identifies a region of myocardial hypoperfusion during stress. The white area within the black region indicates an area of reversibility of the perfusion abnormality. The segments of the coronary arteries rendered in green are segments distal to stenoses seen on CT angiography. This fused scan was read as showing obstructive coronary artery disease in the left anterior descending coronary artery territory. Since the invasive angiogram results showed a 50% proximal left anterior descending coronary artery lesion, only the fused display was interpreted accurately.

Figure 4

Example of fusion imaging in a patient with multi-vessel coronary artery disease. A, Short axis, vertical and horizontal long axis slices of the stress/rest SPECT. It was read as probably normal. B, Polar maps of the same SPECT study. C, Multi-planar reconstructions of the coronary arteries on CT angiography showing a plaque in the proximal left anterior descending coronary artery and possible stenosis in the left circumflex coronary artery. D, Three-dimensional rendering of the coronary arteries on CT angiography showing the paths of the coronary arteries and location of plaques seen in the multi-planar reformations in 3B. E, Fused display; the black area on the fused display identifies a region of myocardial hypoperfusion during stress. The segments of the coronary arteries rendered in green are segments distal to stenoses seen on CT angiography. This fused display was read as positive for coronary artery disease. Invasive angiography showed a 50% proximal left anterior descending coronary artery stenosis and a 90% stenosis in the first marginal vessel; thus the fused display was interpreted correctly.