Diagnostic accuracy assessment of ST-segment displacements, chest pain and stress myocardial perfusion imaging exercise test in coronary stenosis compared with angiography findings

Nowadays, myocardial perfusion imaging [MPI] plays an important role in the early diagnosis of patients with coronary artery disease [CAD]. This study sought to assess the performance of MPI alongside chest paint and ST-segment changes during the stress test by comparison with angiography in the diagnosis of coronary artery stenosis. To that end, the accuracy of these modalities in terms of sensitivity and specificity and the degree of greement between their results in the diagnosis of coronary artery stenosis were evaluated. The study population, selected from those with known or suspected CAD, was comprised of 85 patients [67 males] at a mean age of 53.7 +/- 9.6 years. All the patients were subjected to SPECT imaging of the blood supply to the heart muscle during a two-day state of stress [either pharmacologically with Dipyridamole or through exercise test] and during rest via the injection of 99m Tc - MIBI. ST-segment changes during stress as well as clinical symptoms were recorded. All the patients underwent coronary angiography within two weeks, and coronary artery stenosis >50% was considered positive. Finally, the results of chest pain, ECG changes, and MPI for the evaluation of coronary artery involvement were compared with those of angiography as the gold standard. Of the 85 patients, who underwent angiography, 10 patients had normal coronary angiography, 22 single-vessel disease, 28 two-vessel disease, and 25 three-vessel disease. ST- segment depression and ST-segment elevation were observed in 40 and 6 patients, respectively. The ECG had sensitivity of 57% and specificity of 70% in the diagnosis of coronary artery stenosis. Fifteen patients had chest pain during stress; all of them had coronary involvement according to angiography. Of the 70 patients with no chest pain, coronary angiography was positive in 62 cases; accordingly, chest pain had sensitivity of 20% and specificity of 100% in the diagnosis of coronary artery stenosis. There were 80 patients with abnormal MPI, including 387 fixed and reversible defects. Therefore, MPI had sensitivity of 79%, specificity of 70%, and diagnostic accuracy of 76% in the diagnosis of coronary artery stenosis. MPI enjoyed higher diagnostic accuracy and agreement coefficient than did chest pain and ST-segment changes in the diagnosis of coronary artery stenosis. Given the acceptable results of MPI in the diagnosis of coronary artery stenosis, this modality could be valuable in the management of CAD patients

Respiratory Motion Detection and Correction in ECG-Gated SPECT: a New Approach

OBJECTIVE: Gated myocardial perfusion single-photon emission computed tomography (GSPECT) has been established as an accurate and reproducible diagnostic and prognostic technique for the assessment of myocardial perfusion and function. Respiratory motion is among the major factors that may affect the quality of myocardial perfusion imaging (MPI) and consequently the accuracy of the examination. In this study, we have proposed a new approach for the tracking of respiratory motion and the correction of unwanted respiratory motion by the use of respiratory-cardiac gated-SPECT (RC-GSPECT). In addition, we have evaluated the use of RC-GSPECT for quantitative and visual assessment of myocardial perfusion and function. MATERIALS AND METHODS: Twenty-six patients with known or suspected coronary artery disease (CAD)-underwent two-day stress and rest (99m)Tc-Tetrofosmin myocardial scintigraphy using both conventional GSPECT and RC-GSPECT methods. The respiratory signals were induced by use of a CT real-time position management (RPM) respiratory gating interface. A PIO-D144 card, which is transistor-transistor logic (TTL) compatible, was used as the input interface for simultaneous detection of both ECG and respiration signals. RESULTS: A total of 26 patients with known or suspected CAD were examined in this study. Stress and rest myocardial respiratory motion in the vertical direction was 8.8-16.6 mm (mean, 12.4 +/- 2.9 mm) and 7.8-11.8 mm (mean, 9.5 +/- 1.6 mm), respectively. The percentages of tracer intensity in the inferior, inferoseptal and septal walls as well as the inferior to lateral (I/L) uptake ratio was significantly higher with the use of RC-GSPECT as compared to the use of GSPECT (p < 0.01). In a left ventricular ejection fraction (LVEF) correlation analysis between the use of rest GSPECT and RC-GSPECT with echocardiography, better correlation was noted between RC-GSPECT and echocardiography as compared with the use of GSPECT (y = 0.9654x + 1.6514; r = 0.93, p < 0.001 versus y = 0.8046x + 5.1704; r = 0.89, p < 0.001). Nineteen (19/26) patients (73.1%) showed abnormal myocardial perfusion scans with reversible regional myocardial defects; of the 19 patients, 14 (14/26) patients underwent coronary angiography. CONCLUSION: Respiratory induced motion can be successfully corrected simultaneously with the use of ECG-gated SPECT in MPI studies using this proposed technique. Moreover, the use of ECG-gated SPECT improved image quality, especially in the inferior and septal regions that are mostly affected by diaphragmatic attenuation. However, the effect of respiratory correction depends mainly on the patient respiratory pattern and may be clinically relevant in certain cases.