Diagnostic performance of resting CT myocardial perfusion in patients with possible acute coronary syndrome

Abstract

Objective: Coronary CT angiography has high sensitivity, but modest specificity, to detect acute coronary syndrome. We studied whether adding resting CT myocardial perfusion imaging improved the detection of acute coronary syndrome.

Subjects and methods: Patients with low-to-intermediate cardiac risk presenting with possible acute coronary syndrome received both the standard of care evaluation and a research thoracic 64-MDCT examination. Patients with an obstructive (> 50%) stenosis or a nonevaluable coronary segment on CT were diagnosed with possible acute coronary syndrome. CT perfusion was determined by applying gray and color Hounsfield unit maps to resting CT angiography images. Adjudicated patient diagnoses were based on the standard of care and 3-month follow-up. Patient-level diagnostic performance for acute coronary syndrome was calculated for coronary CT, CT perfusion, and combined techniques.

Results: A total of 105 patients were enrolled. Of the nine (9%) patients with acute coronary syndrome, all had obstructive CT stenoses but only three had abnormal CT perfusion. CT perfusion was normal in all other patients. To detect acute coronary syndrome, CT angiography had 100% sensitivity, 89% specificity, and a positive predictive value of 45%. For CT perfusion, specificity and positive predictive value were each 100%, and sensitivity was 33%. Combined cardiac CT and CT perfusion had similar specificity but a higher positive predictive value (100%) than did CT angiography.

Conclusion: Resting CT perfusion using CT angiographic images may have high specificity and may improve CT positive predictive value for acute coronary syndrome without added radiation and contrast. However, normal resting CT perfusion cannot exclude acute coronary syndrome.

Trial registration: ClinicalTrials.gov NCT00855231.

Figures

Fig. 1. 58-year-old woman with tobacco use who presented with chest pain radiating to back and was scanned urgently to exclude aortic dissection (patient 1 in Table 3)

A, Color and gray-scale CT–myocardial perfusion imaging showed significant lateral wall hypoperfusion (arrows). B and C, Cardiac CT (B) showed 90% obtuse marginal stenosis (asterisk), which was confirmed by invasive angiography (asterisk, C); stent was placed.

Fig. 2. 67-year-old woman with hypertension and diabetes who presented with atypical chest pain (patient 5 in Table 3)

A and B, Color and gray-scale CT–myocardial perfusion imaging (A) showed significant anterior wall hypoperfusion (arrows), which corresponded to hypoperfusion on stress SPECT (arrow, B). C and D, Cardiac CT (C) showed 80% proximal left anterior descending (LAD) artery stenosis (asterisk), which was also seen on invasive angiography (asterisk, D). Patient was diagnosed with unstable angina, and stent was placed in LAD.

Fig. 3. 68-year-old man with hypertension, obesity, and dyslipidemia who presented with atypical chest pain (patient 3 in Table 3)

A, Short-axis view shows hypoperfusion (arrows) of lateral wall on color and gray-scale perfusion maps. B, Cardiac CT showed 95% stenosis (asterisk) of second obtuse marginal branch. Patient ruled in for myocardial infarction. C, Obtuse margin (asterisk) was confirmed by invasive angiography, and patient received single stent.

Fig. 4. 63-year-old obese man with sedentary lifestyle who presented with atypical chest pain (patient 2 in Table 3)

A, Color and gray-scale CT–myocardial perfusion imaging showed anterior artifacts where hypoperfusion areas did not cross phase boundaries (arrows), but no myocardial regions had defined hypoperfusion. B, Cardiac CT showed right coronary artery ostial 70% stenosis, mid maximal 90% stenosis, and distal 70% stenosis (asterisks) as well as left anterior descending artery and ramus stenoses of ≤ 50%. C, Patient was ruled in for myocardial infarction, and invasive angiography also showed stenoses (asterisks); he received two right coronary stents.

Fig. 5. Common artifacts with CT–myocardial perfusion imaging (MPI)

A, Variations in CT–myocardial perfusion imaging (MPI) over cardiac R-R cycle, or beat-to-beat variability, may result in either false-positive or false-negative findings; 40% R-R interval image was false-positive. B, CT-MPI defects that are adjacent to phase-determined boundary, but that fail to cross phase-determined boundary (arrows), are deemed artifact. C, Inferolateral defect due to beam-hardening from spine or descending aorta.