Use of coronary artery calcium scanning beyond coronary computed tomographic angiography in the emergency department evaluation for acute chest pain: the ROMICAT II trial.

BACKGROUND: Whether a coronary artery calcium (CAC) scan provides added value to coronary computed tomographic angiography (CCTA) in emergency department patients with acute chest pain remains unsettled. We sought to determine the value of CAC scan in patients with acute chest pain undergoing CCTA. METHODS AND RESULTS: In the multicenter Rule Out Myocardial Infarction using Computer-Assisted Tomography (ROMICAT) II trial, we enrolled low-intermediate risk emergency department patients with symptoms suggesting acute coronary syndrome (ACS). In this prespecified subanalysis of 473 patients (54±8 years, 53% men) who underwent both CAC scanning and CCTA, the ACS rate was 8%. Overall, 53% of patients had CAC=0 of whom 2 (0.8%) developed ACS, whereas 7% had CAC>400 with 49% whom developed ACS. C-statistic of CAC>0 was 0.76, whereas that using the optimal cut point of CAC≥22 was 0.81. Continuous CAC score had lower discriminatory capacity than CCTA (c-statistic, 0.86 versus 0.92; P=0.03). Compared with CCTA alone, there was no benefit combining CAC score with CCTA (c-statistic, 0.93; P=0.88) or with selective CCTA strategies after initial CAC>0 or optimal cut point CAC≥22 (P≥0.09). Mean radiation dose from CAC acquisition was 1.4±0.7 mSv. Higher CAC scores resulted in more nondiagnostic CCTA studies although the majority remained interpretable. CONCLUSIONS: In emergency department patients with acute chest pain, CAC score does not provide incremental value beyond CCTA for ACS diagnosis. CAC=0 does not exclude ACS, nor a high CAC score preclude interpretation of CCTA in most patients. Thus, CAC results should not influence the decision to proceed with CCTA, and the decision to perform a CAC scan should be balanced with the additional radiation exposure required. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: NCT01084239.

Comparison of dual-source 64-slice adenosine stress CT perfusion with stress-gated SPECT-MPI for evaluation of left ventricular function and volumes.

BACKGROUND: Evaluation of left ventricular (LV) volumes and ejection fraction (LVEF) represent important components of pharmacologic stress imaging with either myocardial CT perfusion (CTP) or gated single-photon emission CT (SPECT) myocardial perfusion imaging (SPECT-MPI). OBJECTIVES: We compared measurements of left ventricular function and volumes obtained with CTP and SPECT-MPI. METHODS: Forty-seven patients (mean age, 62 ± 11 years; male, n = 39) underwent stress CTP and SPECT-MPI. LVEF (in %), end-systolic volume (ESV; in mL), and end-diastolic volume (EDV; in mL) derived from stress CTP images were compared with SPECT-MPI. RESULTS: Stress CTP was in good agreement with SPECT-MPI for quantification of LVEF (r = 0.91), EDV (r = 0.75), and ESV (r = 0.83; all P < 0.001). The mean LVEF measured by stress CTP (66% ± 17%) was similar to SPECT-MPI (64% ± 15%). Similar values were also derived for mean EDV (123 ± 30 mL vs 120 ± 34 mL) and ESV (44 ± 28 mL vs 51 ± 34 mL) for CTP and SPECT-MPI, respectively. Good agreement was also shown between both techniques for the assessment of regional wall motion with identical wall motion scores in 95.3% of the segments (κ = 0.79). CONCLUSIONS: LVEF and LV volume parameters as determined by dual-source 64-slice adenosine stress CTP show a high correlation with values obtained with stress-gated SPECT-MPI.

Appropriateness and utilization of cardiac CT: implications for development of future criteria.

BACKGROUND: The cardiac CT (CCT) appropriateness criteria (AC) were jointly published by multiple societies to ensure effective utilization of CCT. We sought to determine how these criteria apply to CCT scans performed at a tertiary-care hospital. METHODS AND RESULTS: Data were collected from medical records and interviews of 267 consecutive patients referred for CCT. Two physicians designated exam indication as appropriate, inappropriate, or uncertain as per AC, or "not known" if not listed in AC. CCT exam indication was appropriate in 47%, inappropriate in 9%, uncertain in 15%, and not known in 29%. The most common appropriate indication was evaluation of CAD in symptomatic patients with equivocal stress test, whereas the most common inappropriate referral was evaluation of asymptomatic patients with low pretest probability of CAD. Most exams (69%) were for evaluation of CAD, with the remaining exams performed to evaluate other elements of cardiac structure or function. Exams for these non-CAD indications were more likely to be appropriate and less likely to have an undetermined (uncertain or not known) level of appropriateness than those for CAD indications. There was no difference in exam appropriateness whether ordered by cardiologists or internists, but providers who completed training >25 years ago ordered fewer appropriate and more inappropriate exams than younger providers. CONCLUSIONS: In applying the AC to a large academic medical center, few CCT exams were inappropriate; however, many patients referred for CCT, particularly for evaluation of CAD, had an indication for which the level of appropriateness remained undetermined. Given the rapid adoption of CCT, these results emphasize the need to refine current criteria for appropriate utilization.

Intravenous leiomyoma extending into the right ventricle.

We present a case of a retroperitoneal leiomyoma invading the inferior vena cava and extending to the right ventricle. The tumor was visualized with electrocardiographic-gated dual-source computed tomography, showing a low-density, lobulated mass invading the inferior vena cava and prolapsing through the tricuspid valve during diastole. Cardiac computed tomography is useful in assessing the extension and hemodynamic effect of intracardiac masses.

Incremental value of adenosine-induced stress myocardial perfusion imaging with dual-source CT at cardiac CT angiography.

PURPOSE: First, to assess the feasibility of a protocol involving stress-induced perfusion evaluated at computed tomography (CT) combined with cardiac CT angiography in a single examination and second, to assess the incremental value of perfusion imaging over cardiac CT angiography in a dual-source technique for the detection of obstructive coronary artery disease (CAD) in a high-risk population. MATERIALS AND METHODS: Institutional review board approval and informed patient consent were obtained before patient enrollment in the study. The study was HIPAA compliant. Thirty-five patients at high risk for CAD were prospectively enrolled for evaluation of the feasibility of CT perfusion imaging. All patients underwent retrospectively electrocardiographically gated (helical) adenosine stress CT perfusion imaging followed by prospectively electrocardiographically gated (axial) rest myocardial CT perfusion imaging. Analysis was performed in three steps: (a)Coronary arterial stenoses were scored for severity and reader confidence at cardiac CT angiography, (b)myocardial perfusion defects were identified and scored for severity and reversibility at CT perfusion imaging, and (c)coronary stenosis severity was reclassified according to perfusion findings at combined cardiac CT angiography and CT perfusion imaging. The sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) of cardiac CT angiography before and after CT perfusion analysis were calculated. RESULTS: With use of a reference standard of greater than 50% stenosis at invasive angiography, all parameters of diagnostic accuracy increased after CT perfusion analysis: Sensitivity increased from 83% to 91%; specificity, from 71% to 91%; PPV, from 66% to 86%; and NPV, from 87% to 93%. The area under the receiver operating characteristic curve increased significantly, from 0.77 to 0.90 (P < .005). CONCLUSION: A combination protocol involving adenosine perfusion CT imaging and cardiac CT angiography in a dual-source technique is feasible, and CT perfusion adds incremental value to cardiac CT angiography in the detection of significant CAD.

Direct comparison of rest and adenosine stress myocardial perfusion CT with rest and stress SPECT.

INTRODUCTION: We have recently described a technique for assessing myocardial perfusion using adenosine-mediated stress imaging (CTP) with dual source computed tomography. SPECT myocardial perfusion imaging (SPECT-MPI) is a widely utilized and extensively validated method for assessing myocardial perfusion. The aim of this study was to determine the level of agreement between CTP and SPECT-MPI at rest and under stress on a per-segment, per-vessel, and per-patient basis. METHODS: Forty-seven consecutive patients underwent CTP and SPECT-MPI. Perfusion images were interpreted using the 17 segment AHA model and were scored on a 0 (normal) to 3 (abnormal) scale. Summed rest and stress scores were calculated for each vascular territory and patient by adding corresponding segmental scores. RESULTS: On a per-segment basis (n = 799), CTP and SPECT-MPI demonstrated excellent correlation: Goodman-Kruskall gamma = .59 (P < .0001) for stress and .75 (P < .0001) for rest. On a per-vessel basis (n = 141), CTP and SPECT-MPI summed scores demonstrated good correlation: Pearson r = .56 (P < .0001) for stress and .66 (P < .0001) for rest. On a per-patient basis (n = 47), CTP and SPECT-MPI demonstrated good correlation: Pearson r = .60 (P < .0001) for stress and .76 (P < .0001) for rest. CONCLUSIONS: CTP compares favorably with SPECT-MPI for detection, extent, and severity of myocardial perfusion defects at rest and stress.

Adenosine-induced stress myocardial perfusion imaging using dual-source cardiac computed tomography.

OBJECTIVES: This study sought to determine the feasibility of performing a comprehensive cardiac computed tomographic (CT) examination incorporating stress and rest myocardial perfusion imaging together with coronary computed tomography angiography (CTA). BACKGROUND: Although cardiac CT can identify coronary stenosis, very little data exist on the ability to detect stress-induced myocardial perfusion defects in humans. METHODS: Thirty-four patients who had a nuclear stress test and invasive angiography were included in the study. Dual-source computed tomography (DSCT) was performed as follows: 1) stress CT: contrast-enhanced scan during adenosine infusion; 2) rest CT: contrast-enhanced scan using prospective triggering; and 3) delayed scan: acquired 7 min after rest CT. Images for CTA, computed tomography perfusion (CTP), and single-photon emission computed tomography (SPECT) were each read by 2 independent blinded readers. RESULTS: The DSCT protocol was successfully completed for 33 of 34 subjects (average age 61.4 +/- 10.7 years; 82% male; body mass index 30.4 +/- 5 kg/m(2)) with an average radiation dose of 12.7 mSv. On a per-vessel basis, CTP alone had a sensitivity of 79% and a specificity of 80% for the detection of stenosis > or =50%, whereas SPECT myocardial perfusion imaging had a sensitivity of 67% and a specificity of 83%. For the detection of vessels with > or =50% stenosis with a corresponding SPECT perfusion abnormality, CTP had a sensitivity of 93% and a specificity of 74%. The CTA during adenosine infusion had a per-vessel sensitivity of 96%, specificity of 73%, and negative predictive value of 98% for the detection of stenosis > or =70%. CONCLUSIONS: Adenosine stress CT can identify stress-induced myocardial perfusion defects with diagnostic accuracy comparable to SPECT, with similar radiation dose and with the advantage of providing information on coronary stenosis.

Radiation dose and image quality of prospective triggering with dual-source cardiac computed tomography.

Prospectively triggered (PT) cardiac computed tomography (CT), whereby radiation is administered only at a predefined phase of the cardiac cycle, has been shown to substantially decrease radiation dose. The aim of our study was to assess the use of this technique in a clinical population using dual-source cardiac CT. Of 312 consecutive patients referred for a dual-source cardiac computed tomographic examination, PT was used in 42 patients for whom, based on physician judgment, it was decided to minimize radiation, whereas retrospective gating was used for 188 patients (coronary artery bypass grafting and pulmonary vein studies were excluded). Kilovolt and milliampere per second were chosen for each patient based on assessment of body habitus and effective radiation dose was calculated. Analysis of nonevaluable vessels was based on clinical readings. For each study, image quality (IQ) was rated on a subjective IQ score and contrast-to-noise and signal-to-noise ratios were calculated. Of the 42 PT examinations (mean age 44.3 years, body mass index 27.8 kg/m(2), 62% men), 28 were referred for coronary evaluation, 11 for aortic disease with/without coronaries, and 3 for other reasons (i.e., suspected mass and congenital disease). Average heart rate was 64.5 beats/min. Average radiation dose of all 42 PT scans was 3.2 +/- 1.6 vs 13.4 +/- 7.8 mSv for the 188 non-PT scans. There was no significant difference in IQ score and contrast-to-noise and signal-to-noise ratios between the 2 groups. Furthermore, the incidence of limited right coronary artery evaluation and of limitations related to right coronary artery motion did not differ between PT and non-PT scans. In conclusion, in selected patients, prospective triggering with dual-source cardiac CT is feasible and results in a dramatic decrease of radiation dose without compromising IQ. Future advances in cardiac CT may further improve this technique, thus allowing for wider use.