Riksta Dikkers

Assessment of image quality of 64-row Dual Source versus Single Source CT coronary angiography on heart rate: A phantom study

PURPOSE To assess the influence of temporal resolution on image quality of computed tomographic (CT) coronary angiography by comparing 64-row Dual Source CT (DSCT) and Single Source CT (SSCT) at different heart rates. METHODS An anthropomorphic moving heart phantom was scanned at rest, and at 50 beats per minute (bpm) up to 110 bpm, with intervals of 10 bpm. 3D volume rendered images and curved multi-planar reconstructions (MPRs) were acquired and image quality of the coronary arteries was rated on a 5-points scale (1=poor image quality with many artefacts, 5=excellent image quality) for each heart rate and each scanner by 3 observers. Paired sample t-test and Wilcoxon Signed Ranks test were used to assess clinically relevant differences between both modalities. RESULTS The mean image quality scores at 70, 100 and 110 bpm were significantly higher for DSCT compared to SSCT. The overall mean image quality scores for DSCT (4.2+/-0.6) and SSCT (3.0+/-1.1) also differed significantly (p<0.001). CONCLUSION These initial results show a clinically relevant overall higher image quality for DSCT compared to SSCT, especially at heart rates of 70, 100 and 110 bpm. With its comparatively high image quality and low radiation dose, DSCT appears to be the method of choice in CT coronary angiography at heart rates above 70 bpm.

Accuracy of noninvasive coronary stenosis quantification of different commercially available dedicated software packages.

Purpose: The purpose of this study was to investigate the noninvasive quantification of coronary artery stenosis using cardiac software packages and vessel phantoms with known stenosis severity. Materials and Methods: Four different sizes of vessel phantoms were filled with contrast agent and scanned on a 64-slice multidetector computed tomography. Diameter and area stenosis were evaluated by 2 observers blinded from the true measures using 5 different software packages. Measurements were compared with the true measure of the vessel phantoms. The absolute difference in stenosis measurements and intraobserver and interobserver variabilities were assessed. Results: All software packages show a trend toward larger differences for the smaller vessel phantoms. The absolute difference of the automatic measurements was significantly higher compared with that of the manual measurements in all 5 evaluated software packages for all vessel phantoms (P < 0.05). Conclusion: Manual stenosis measurements are significantly more accurate compared with automatic measurements, and therefore, manual adjustments are still essential for noninvasive assessment of coronary artery stenosis.

The role of coronary artery calcification score in clinical practice

BackgroundCoronary artery calcification (CAC) measured by electron-beam computed tomography (EBCT) has been well studied in the prediction of coronary artery disease (CAD). We sought to evaluate the impact of the CAC score in the diagnostic process immediately after its introduction in a large tertiary referral centre.Methods598 patients with no history of CAD who underwent EBCT for evaluation of CAD were retrospectively included into the study. Ischemia detection test results (exercise stress test, single photon emission computed tomography or ST segment analysis on 24 hours ECG detection), as well as the results of coronary angiography (CAG) were collected.ResultsThe mean age of the patients was 55 ± 11 years (57% male). Patients were divided according to CAC scores; group A < 10, B 10 – 99, C 100 – 399 and D ≥ 400 (304, 135, 89 and 70 patients respectively). Ischemia detection tests were performed in 531 (89%) patients; negative ischemia results were found in 362 patients (183 in group A, 87 in B, 58 in C, 34 in D). Eighty-eight percent of the patients in group D underwent CAG despite negative ischemia test results, against 6% in group A, 16% in group B and 29% in group C. A positive ischemia test was found in 74 patients (25 in group A, 17 in B, 16 in C, 16 in D). In group D 88% (N = 14) of the patients with a positive ischemia test were referred for CAG, whereas 38 – 47% in group A-C.ConclusionOur study showed that patients with a high CAC score are more often referred for CAG. The CAC scores can be used as an aid in daily cardiology practice to determine further decision making.

Quantitative image analysis for the detection of motion artefacts in coronary artery computed tomography.

Multi detector-row CT (MDCT), the current preferred method for coronary artery disease assessment, is still affected by motion artefacts. To rule out motion artefacts, qualitative image analysis is usually performed. Our study aimed to develop a quantitative image analysis for motion artefacts detection as an added value to the qualitative analysis. An anthropomorphic moving heart phantom with adjustable heart-rate was scanned on 64-MDCT and dual-source-CT. A new software technique was developed which detected motion artefacts in the coronaries and also in the myocardium, where motion artefacts are more apparent; with direct association to the qualitative analysis. The new quantitative analysis managed to detect motion artefacts in phantom scans and relate them to artefact-induced vessel stenoses. Quantifying these artefacts at corresponding locations in the myocardium, artefact-induced vessel stenosis findings could be avoided. In conclusion, the quantitative analysis together with the qualitative analysis rules out artefact-induced stenosis.

5 Year-old Boy with a Hearth Murmur and Fever

A 5 year old boy was admitted to the emergency ward. Physical examination revealed a heart murmur and fever. During his stay on the emergency ward oxygen saturation progressively worsened. A cardiac ultrasound showed an occlusion of the right pulmonic artery and severe narrowing of the left pulmonic artery. Computed Tomography Angiography (CTA) confirmed the diagnosis. Pathology examination of the retrieved thrombus during emergency thoracotomy revealed a fungus cast from Zygomycete; Rhizopus microsporus. The patient was treated with Posaconazole and high dose of liposomal Amphotericin B. The patient was fully recovered forty-five days after admittance to the emergency ward.

Measurement of coronary calcium scores or exercise testing as initial screening tool in asymptomatic subjects with ST-T changes on the resting ECG: an evaluation study

BackgroundAsymptomatic subjects at intermediate coronary risk may need diagnostic testing for risk stratification. Both measurement of coronary calcium scores and exercise testing are well established tests for this purpose. However, it is not clear which test should be preferred as initial diagnostic test. We evaluated the prevalence of documented coronary artery disease (CAD) according to calcium scores and exercise test results.MethodsAsymptomatic subjects with ST-T changes on a rest ECG were selected from the population based PREVEND cohort study and underwent measurement of calcium scores by electron beam tomography and exercise testing. With calcium scores ≥10 or a positive exercise test, myocardial perfusion imaging (MPS) or coronary angiography (CAG) was recommended. The primary endpoint was documented obstructive CAD (≥50% stenosis).ResultsOf 153 subjects included, 149 subjects completed the study protocol. Calcium scores ≥400, 100–399, 10–99 and <10 were found in 16, 29, 18 and 86 subjects and the primary endpoint was present in 11 (69%), 12 (41%), 0 (0%) and 1 (1%) subjects, respectively. A positive, nondiagnostic and negative exercise test was present in 33, 27 and 89 subjects and the primary endpoint was present in 13 (39%), 5 (19%) and 6 (7%) subjects, respectively. Receiver operator characteristics analysis showed that the area under the curve, as measure of diagnostic yield, of 0.91 (95% CI 0.84–0.97) for calcium scores was superior to 0.74 (95% CI 0.64–0.83) for exercise testing (p = 0.004).ConclusionMeasurement of coronary calcium scores is an appropriate initial non-invasive test in asymptomatic subjects at increased coronary risk.

Ductus Arteriosus Aneurysm and Vocal Cord Paralysis

A 3-day-old full-term infant was transferred to our pediatric intensive care unit because of significant biphasic stridor with desaturation spells. The history revealed an uncomplicated pregnancy and normal spontaneous vaginal delivery. The mother was known to have hypothyroidism caused by Hashimoto thyroiditis (negative thyroid-stimulating immunoglobulin). Apgar scores were 6 and 9 after 1 and 5 minutes; no resuscitation was needed. Umbilical arterial and venous blood gas values showed marked acidosis (pH 6.81 and 6.88, respectively) without signs of encephalopathy. General and cardiovascular examinations were normal. In particular, there was no marfanoid habitus, heart sounds were normal, and peripheral pulses were preserved. Chest x-ray illustrated a pronounced cardiac silhouette …