Gerd Muschiol

Variability of Repeated Coronary Artery Calcium Measurements by Electron Beam Tomography

In 120 patients, the mean interscan variability of coronary calcium quantification by electron beam tomography was 19.9% (median 7.8%) for the traditional calcium score, and 16.2% (median 5.7%) for volumetric scoring. Although this difference was not significant, there was a significant influence of the total amount of calcium, number of acquired images, and image noise on interscan reproducibility.

Accuracy of dual-source computed tomography to identify significant coronary artery disease in patients with atrial fibrillation: comparison with coronary angiography

AIMS It has been previously reported that the sensitivity and specificity of multislice computed tomography (CT) for detecting significant coronary artery disease (CAD) is high. However, regular sinus rhythm has been considered a prerequisite for an adequate examination, even though atrial fibrillation (AF) is common among patients evaluated for the presence of coronary heart disease. In this study, we investigated the sensitivity and specificity of dual-source CT (DSCT) to detect and rule out significant coronary stenoses in patients with AF referred for invasive coronary angiography. METHODS AND RESULTS One hundred and ten consecutive patients with AF who were admitted for a first diagnostic coronary angiogram were screened for participation. Out of these, 50 patients were excluded either due to renal insufficiency, inability to maintain an adequate breath hold or due to rapid AF non-responsive to β-blocker therapy (heart rate > 100 b.p.m.). Sixty remaining patients (mean age 71 ± 7 years) were included and subjected to CT angiography using DSCT within 24 h before invasive coronary angiography. A contrast-enhanced volume data set was acquired (330 ms gantry rotation, collimation 2 × 64 × 0.6 mm, retrospective electrocardiogram gating). Data sets were evaluated concerning the presence or absence of significant coronary stenoses and validated against invasive coronary angiography. A significant stenosis was assumed if the diameter reduction was ≥50%. Mean heart rate during CT was 70 ± 15 b.p.m. (range 32-107 b.p.m.). On a per-patient basis, the sensitivity and specificity for DSCT to detect significant coronary stenoses in vessels >1.5 mm diameter was 100% [14/14, 95% confidence interval (CI) 77-100] and 85% (39/46, 95% CI 71-94), respectively, with a negative predictive value (NPV) of 100% (39/39, 95% CI 91-100) and a positive predictive value (PPV) of 67% (14/21, 95% CI 43-85). On a per-artery basis, 240 vessels were evaluated (left main, left anterior descending, left circumflex, and right coronary artery in 60 patients, with 3 non-assessable vessels due to either severe calcification or motion artefacts which were considered positive for stenoses) with a sensitivity of 95% (21/22, 95% CI 77-100) and specificity of 94% (204/218, 95% CI 89-97); NPV was 99% (204/205, 95% CI 96-100), and PPV was 60% (21/35, 95% CI 38-80). CONCLUSION Our study demonstrates high sensitivity, specificity, and NPV of DSCT to detect significant CAD in selected patients with rate controlled AF.

Overlapping cross-sections significantly improve the reproducibility of coronary calcium measurements by electron beam tomography: a phantom study.

Purpose We conducted phantom studies to investigate whether overlapping cross-sections and volumetric scoring would significantly improve interscan reproducibility of electron beam tomography (EBT) for coronary artery calcium quantification. Method Fifteen phantoms simulating various amounts of coronary calcification were scanned in five different positions with a slice thickness of 3.0 mm and a table feed of 3.0, 2.5, and 2.0 mm. For the conventional “Agatston score” and a “volume score” (total volume of calcified lesions), interscan variabilities were compared between the three image acquisition protocols. Results Agatston score variability was significantly lower for the 2.0 mm table feed than for the 3.0 or 2.5 mm table feed (3.0 mm: 22.9 ± 10.3%; 2.5 mm: 13.6 ± 8.2%; 2.0 mm: 8.9 ± 5.5%). Volume score variability was significantly lower for 2.5 and 2.0 mm table feed than for 3.0 mm table feed (3.0 mm: 21.7 ± 11.0%; 2.5 mm: 10.9 ± 5.9%; 2.0 mm: 9.8 ± 5.9%). Conclusion Overlapping cross-sections, especially in combination with volumetric scoring, significantly improved interscan reproducibility of EBT calcium quantification in a phantom study.

Assessment of regional left ventricular function by Dual Source Computed Tomography: Interobserver variability and validation to laevocardiography

OBJECTIVE Assessment of left ventricular function is possible in contrast-enhanced cardiac CT data sets. However, rapid ventricular motion especially in systole can lead to artifacts. Dual Source Computed Tomography (DSCT) has high temporal resolution which effectively limits motion artifact. We therefore assessed the accuracy of DSCT to detect regional left ventricular wall motion abnormalities in comparison to invasive cine angiocardiography. METHODS We analyzed DSCT data sets of 50 patients (39 male, 11 female, mean age: 61+/-10 years) which were acquired after intravenous injection of 55-70 mL contrast agent (rotation time: 330 ms, collimation: 2 mm x 64 mm x 0.6 mm, 120 kV, 380 mAs, ECG-correlated tube current modulation). 10 data sets consisting of transaxial slices with a slice thickness of 1.5 mm, an increment of 1.0 mm and a matrix of 256 x 256 pixels were reconstructed at 10 time instants during the cardiac cycle (0-90% in 10% increments). The data sets were analyzed visually by two independent readers, using standard left ventricular planes, concerning regional wall motion abnormalities. DSCT was verified in a blinded fashion against cine ventriculography performed during cardiac catheterization (RAO and LAO projection), using a 7-segment model. Analysis was performed on a per-patient (presence of at least one hypo-, a- or dyskinetic segment) and on a per-segment basis. RESULTS Concerning the presence of a wall motion abnormality, the two observers agreed in 340/350 segments (97%) and 48/50 patients (96%). In invasive cine angiocardiography, 22 of 50 patients displayed at least one segment with abnormal contraction. To detect these patients, DSCT showed a sensitivity of 95% (21/22), specificity of 96% (27/28), positive predictive value of 95% and negative predictive value of 96%. Out of a total of 350 left ventricular segments, 66 segments had abnormal contraction in cine angiocardiography (34 hypokinetic, 26 akinetic, 6 dyskinetic). For detection of these segments, DSCT had a sensitivity of 88% (58/66), specificity of 98% (278/284), positive predictive value of 91% (58/64) and negative predictive value of 97% (278/286). CONCLUSION DSCT allows the detection of regional wall motion abnormalities with high interobserver agreement as well as high sensitivity and specificity. Whereas sensitivity and positive predictive value were higher in a per-patient- in comparison to a per-segment-based analysis, specificity, negative predictive value and interobserver agreement did not differ considerably between both analyzing methods.

Left ventricular thrombus attenuation characterization in cardiac computed tomography angiography.

BACKGROUND Because of their similar visual appearance, differentiation of left ventricular thrombotic material and myocardial wall can be difficult in contrast-enhanced coronary computed tomography (CT) angiography. OBJECTIVE We identified typical thrombi attenuation of left ventricular thrombi with the use of CT measurement. METHODS Over a time period of 6 years, we retrospectively identified 31 patients who showed a left ventricular thrombus in CT angiography datasets. Patients underwent routine contrast cardiac CT to investigate coronary artery disease. CT attenuation of each thrombus was assessed in the 4-chamber view. CT densities were also determined in the ascending aorta, left ventricle, and myocardial wall both in the mid-septal and mid-lateral segments. The mean CT attenuation of thrombi and the difference between attenuation in thrombi, left ventricular cavity, and myocardial wall were determined. The ratio of attenuation values in thrombus versus aorta and myocardium versus aorta were also determined. RESULTS Mean (±SD) CT attenuation of all left ventricular thrombi in 31 patients was 43.2 ± 15.3 HU (range, 25-80 HU). Mean CT densities of septal and lateral myocardial wall were 102.9 ± 23.1 HU (range, 63-155 HU) and 99.3 ± 28.7 HU (range, 72-191 HU), respectively, and were thus significantly higher than the CT attenuation of thrombi (P < 0.001). A threshold of 65 HU yielded a sensitivity, specificity, and positive and negative predictive values of 94%, 97%, 94%, and 97%, respectively, to differentiate thrombus from the myocardial wall. The mean ratio between CT attenuation of thrombus and CT attenuation within the ascending aorta was 0.11 ± 0.05 (range, 0.04-0.23), which was significantly lower compared with the mean ratio between CT attenuation of the myocardial wall and the CT attenuation within the ascending aorta. CONCLUSION CT attenuation within left ventricular thrombi was significantly lower than myocardial attenuation in CT angiography datasets. Assessment of CT attenuation may contribute to the differentiation of thrombi.

Ventricular septal rupture and right ventricular intramyocardial dissection secondary to acute inferior myocardial infarction

A 61-year-old female patient presented with sub acute myocardial infarction with an occluded right coronary artery on invasive evaluation and a ventricular septal rupture on echocardiogram. Cardiac computed tomography (CT) was performed to better define the septal anatomy. As the anatomy on cardiac CT was considered unfavorable for percutaneous intervention, the patient underwent successful surgical repair.

LOW-DOSE CORONARY CTA AT 70 KV: EFFECT OF ITERATIVE RECONSTRUCTION ON IMAGE QUALITY AND CORONARY ATHEROSCLEROTIC PLAQUE DETECTION

Low tube voltage is one approach to limit radiation exposure in coronary CTA. Third generation dual source CT newly permits to use 70 kVp. We evaluated the influence of reconstruction parameters, including iterative reconstruction, on image quality and coronary atherosclerotic plaque when performing

Suture-induced right coronary artery stenosis.

An 82-year-old patient developed right heart failure in the days after surgical aortic valve replacement. Coronary CT angiography showed a high-grade stenosis of the mid-right coronary artery. Adjacent suture material seen on noncontrast CT suggested that the lesion was related to surgical closure of the right atrial cannulation site. Invasive angiography confirmed the stenosis, and percutaneous intervention was successfully performed.

Calcified right intraventricular thrombus in a patient with systemic lupus erythematous and antiphospholipid syndrome

A 37-year-old patient with known systemic lupus erythematous, antiphospholipid syndrome and previous pulmonary embolism presented with non-ST elevation myocardial infarction while on adequate anticoagulation therapy. The patient was further evaluated with cardiac computed tomography. A small diagonal branch occlusion was the only coronary lesion present. A partially calcified right ventricular thrombus was incidentally found. Because of the small vessel size, cardiac catheterization was deemed unnecessary, and the patient was discharged with adjustment of immunosuppressive therapy and anticoagulation.