Assessment of calcium scoring performance in cardiac computed tomography

Electron beam tomography (EBT) has been used for cardiac diagnosis and the quantitative assessment of coronary calcium since the late 1980s. The introduction of mechanical multi-slice spiral CT (MSCT) scanners with shorter rotation times opened new possibilities of cardiac imaging with conventional CT scanners. The purpose of this work was to qualitatively and quantitatively evaluate the performance for EBT and MSCT for the task of coronary artery calcium imaging as a function of acquisition protocol, heart rate, spiral reconstruction algorithm (where applicable) and calcium scoring method. A cardiac CT semi-anthropomorphic phantom was designed and manufactured for the investigation of all relevant image quality parameters in cardiac CT. This phantom includes various test objects, some of which can be moved within the anthropomorphic phantom in a manner that mimics realistic heart motion. These tools were used to qualitatively and quantitatively demonstrate the accuracy of coronary calcium imaging using typical protocols for an electron beam (Evolution C-150XP, Imatron, South San Francisco, Calif.) and a 0.5-s four-slice spiral CT scanner (Sensation 4, Siemens, Erlangen, Germany). A special focus was put on the method of quantifying coronary calcium, and three scoring systems were evaluated (Agatston, volume, and mass scoring). Good reproducibility in coronary calcium scoring is always the result of a combination of high temporal and spatial resolution; consequently, thin-slice protocols in combination with retrospective gating on MSCT scanners yielded the best results. The Agatston score was found to be the least reproducible scoring method. The hydroxyapatite mass, being better reproducible and comparable on different scanners and being a physical quantitative measure, appears to be the method of choice for future clinical studies. The hydroxyapatite mass is highly correlated to the Agatston score. The introduced phantoms can be used to quantitatively assess the performance characteristics of, for example, different scanners, reconstruction algorithms, and quantification methods in cardiac CT. This is especially important for quantitative tasks, such as the determination of the amount of calcium in the coronary arteries, to achieve high and constant quality in this field. Electronic Publication     

Cardiac biopsy in childhood

Endomyocardial biopsy was attempted in 18 children aged 5 months to 15 years with 82% success. Biopsies obtained from 15 children were examined by light and electron microscope making positive morphological diagnoses in 3 cases. The biopsy findings were actively helpful in 7 other cases, which contrasts with experience in adult biopsy series. This is a low risk procedure which does not add to the hazards of cardiac catheterization in children.     

Prolonged QT interval and cardiac arrhythmias in two neonates: sudden infant death syndrome in one case

Two neonates with arrhythmias and the long QT syndrome are described. The arrhythmias were detected in utero and both infants were apparently well after birth. The first infant, although well, had a bradycardia for the first 9 days of life. A normal heart rate was documented at 10 days but a prolonged QT interval was not appreciated on the ECG. He was discharged from hospital but died suddenly and unexpectedly 3 days later. A post-mortem examination failed to find a cause for his death which therefore fell into the category of the sudden infant death syndrome (SIDS). A retrospective analysis of the perinatal electrocardiogram showed a probable junctional rhythm with 2:1 conduction to the ventricle; the QT interval was prolonged at 0.52 seconds (QTC = 0.63). The second infant had a QT interval of 0.52 seconds (QTC = 0.54) and frequent ventricular premature beats on a 24-hour electrocardiogram. She was treated with propranolol and remains well 2 years later. Sudden infant death has often been described in the siblings of children with the long QT syndrome and one other report described a case of SIDS which was said to have had a prolonged QT interval on the perinatal ECG. This report, however, provides unquestionable evidence, in one case, of an association between the long QT syndrome and SIDS.     

An anatomic coordinate system of the femoral neck for highly reproducible BMD measurements using 3D QCT.

In this paper, a procedure for the determination of an anatomically oriented coordinate system of the femoral neck (NCS) in 3D spiral CT datasets is described. The origin of the NCS is centered in the minimal cross-sectional area of the neck. Its three axes are defined as follows: the so called neck axis is perpendicular to this area and points towards the femoral head, the second axis is the principal axis of the minimal cross-sectional area and the third axis is perpendicular to the other two. After a semi-automatic 3D segmentation of the proximal femur the NCS is automatically determined in a two-step minimization procedure. Relative to the coordinate system volumes of interest (VOIs) are positioned in which bone mineral density (BMD) and cortical thickness are analyzed. We investigated intra- and inter-operator precision of the position of the NCS, the BMD in cortical and trabecular VOIs, and cortical thickness in nine pelvic CT datasets obtained from clinical routine examinations. We further investigated the effect of increased noise by adding Gaussian distributed noise to measured projections before tomographic reconstruction. The mean precision error (averaged form the results of the nine datasets) of the NCS position was less than 0.5 mm and smaller than 2.25 degrees . There were no significant differences between inter- and intra-operator analyses. Precision errors in trabecular BMD were smaller than 3% in a stack of five 1 mm thin slices cut perpendicularly to the neck axis and smaller than 1% in a spherical VOI encompassing the neck. Relative precision errors for cortical BMD were smaller than 3% for both VOIs. An increase of noise up to a factor of 5 caused a maximal displacement of the NCS origin position by less than 1mm and a rotation by less than 2 degrees .     

Ankle: surface coil MR imaging at 1.5 T

High-field surface coil magnetic resonance (MR) images were obtained of 12 ankles: two from healthy volunteers, seven from patients, and three from fresh cadavers. The cadaver ankles were sectioned in the coronal, sagittal, and axial planes for direct comparison with the MR images. Plain film confirmation of pathologic conditions was obtained in all patients, and five underwent arthroscopy or surgery, or both. MR imaging provided excellent delineation of ligaments and cartilaginous structures in all cases.     

Management of cerebral ischemia due to Takayasu''''s arteritis

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Spiral volumetric CT with single-breath-hold technique, continuous transport, and continuous scanner rotation

Continuous computed tomographic (CT) scanning of organ volumes during a single breath hold was studied. The authors modified the table feed mechanism of a continuously rotating CT scanner to allow patient transport at low, but accurately controlled, speeds (0.1-11.0 mm/sec) during continuous 1-second scanning. An algorithm was designed to reconstruct artifact-free images for arbitrary table positions from the helical data by interpolating between adjacent scans. Section sensitivity profiles were enlarged; the section width for a 10-mm section and a speed of 10.0 mm/sec was increased by a factor of 1.3, compared with the nominal value. Clinical examples were presented for studies of lung nodules and studies enhanced with contrast medium. Major advantages are the possibility of continuous scanning of extended volumes within a breath-hold period and retrospective, arbitrary selection of anatomic levels.     

The effects of acute phase proteins on serum albumin,transferrin and haemoglobin in haemodialysis patients

In the present study, the effects of C-reactive protein (CRP) and ferritin on serum albumin, transferrin and haemoglobin (Hb) were assessed to investigate the relationship between inflammation, hypoalbuminaemia and anaemia in haemodialysis patients. A total of 117 patients who were followed at three haemodialysis units in Kocaeli were enrolled. The mean age was 47.83 +/- 16.85 years. The median time on dialysis was 26 (minimum 1, maximum 209) months. Serum CRP albumin and ferritin concentrations were measured in our laboratory and transferrin, urea reduction ratio (URR) and Kt/V were calculated. There was significant inverse correlation between serum CRP level and albumin (p<0.001), serum CRP and Hb (p<0.001), and serum transferrin and ferritin (p<0.05). There was significant positive correlation between serum albumin and Hb (p<0.001), serum CRP and ferritin (p<0.05), and transferrin and URR (p<0.05). Our findings suggest that inflammation is a contributor in the development of hypoalbuminaemia and anaemia in haemodialysis patients as well as malnutrition and inadequate dialysis.     

Adverse reactions in blood donors with a history of seizures or epilepsy

BACKGROUND: Individuals with epilepsy or seizure disorders are restricted from donating blood because of concern that they are prone to adverse donor reactions such as syncope and convulsions. A study evaluating whether that concern is warranted is reported. STUDY DESIGN AND METHODS: During a 2-year period beginning in 1987, blood donors in Maryland with a history of seizures were actively recruited by the American Red Cross. Adverse donor reactions were classified as "slight", indicating dizziness and nausea without loss of consciousness; "moderate," denoting syncope; and "severe," indicating convulsive syncope. RESULTS: There were 329,143 satisfactory blood donations; 613 individuals reporting a history of seizures donated blood a total of 723 times. Among donors with seizures, 186 (35.7%) were taking antiepileptic medication, and 61 (8.4%) had had one or more seizures in the preceding year. Individuals with seizures had a low incidence of adverse reactions (3.34%). Although this incidence was slightly higher than that in the entire population (2.24%), the difference was not significant. In particular, the risk of syncope with or without convulsive activity was low for people with seizures (0.21%) and not significantly greater than that in other donors (0.28%). CONCLUSION: Individuals with seizures or epilepsy are not at greater risk for adverse reactions after blood donation, and major restrictions on their participation as blood donors are not warranted.