Bertil Svane

Cross-sectional area of the thigh muscle in man measured by computed tomography

Nine subjects with different training background were studied by means of muscle biopsy from musculus vastus lateralis. The cross-cut area of the different muscle fibre types was measured. By the use of a soft tissue X-ray technique, computed tomography, a cross-sectional picture of the thigh was produced at the same level as the biopsy was taken. The total cross-cut area of the vastus lateralis muscle was measured from this picture. This technique to measure a cross-cut muscle area from an X-ray picture was evaluated and found to be accurate and reproducible. The mean fibre area was highly correlated (r = 0.91; P less than 0.001) to the cross-cut area of the vastus lateralis muscle. The total number of fibres in the vastus lateralis muscle was estimated. It was concluded that the cross-sectional area of the thigh muscle can be accurately determined by means of computed tomography. The larger cross-sectional area of the vastus lateralis muscle in well trained subjects was primarily explained by a larger cross-sectional area of the fibre, while the total number of fibres in the vastus lateralis muscle seemed to be fairly equal among the subjects.

A comparison of spiral computed tomography and latex agglutination D-dimer assay in acute pulmonary embolism using pulmonary arteriography as gold standard.

Objective : To compare the diagnostic accuracy of contrast medium enhanced spiral computed tomography of the pulmonary arteries (s-CTPA) and a latex agglutination D-dimer assay in patients with suspected acute pulmonary embolism (PE) by using pulmonary arteriography (PA) and clinical follow-up as reference method. Design : Ninety hemodynamically stable patients with symptoms of acute pulmonary embolism were prospectively evaluated with s-CTPA and pulmonary arteriography (PA) within 24 h from admission. Plasma D-dimer levels on admittance were analyzed using a rapid latex agglutination D-dimer assay. The outcome of D-dimer concentrations in plasma below 0.25 and 0.5 mg/l was studied. Results : All PA and s-CTPA investigations were regarded as of acceptable diagnostic quality in a consensus reading. Thirty-three patients had a positive PA (37%). Three patients had false negative and two patients had false positive s-CTPA findings. s-CTPA had 91% sensitivity, 96% specificity, 94% positive predictive value (PPV) and 95% negative predictive value (NPV). The sensitivity and specificity for D-dimer below 0.5 mg/l were 79 and 88%, respectively. The PPV and NPV were 81 and 87%. If a cut-off level of 0.25 mg/l was used the corresponding figures were 91, 65, 63 and 92%. Conclusion : s-CTPA has a higher sensitivity and specificity than latex agglutination D-dimer. A cut-off level of 0.25 mg/l can be used as screening method, but s-CTPA must be performed to exclude false positive cases.

Polar presentation of coronary angiography and thallium-201 single photon emission computed tomography : a method for comparing anatomic and pathologic findings in coronary angiography with isotope distribution in thallium-201 myocardial SPECT

Individual results of coronary angiography were compared with tomographic myocardial scintigraphy (SPECT) in 99 patients. Coronary angiography findings were transferred to polar maps. Borders between arteries were assigned angles in a coordinate system constructed as a compass-rose. Areas perfused by different arteries were described by sectors. Findings were visually compared with the perfusion defects in a polar presentation of thallium-201 SPECT also described by angles. The mean values and SD for the angles representing arterial borders and perfusion defects were presented. The left ventricular myocardium was perfused by 3 coronary arteries in 92/99 patients. Dominant left artery was present in 7/99 patients; 79 perfusion defects were related to 118 arterial sectors 84 per cent had totally or partially matched stenotic arteries. Inter-individual differences in distribution of coronary arteries influence the localization of perfusion defects in myocardial SPECT and can be estimated with this polar presentation method.

Visual classification of emphysema heterogeneity compared with objective measurements: HRCT vs spiral CT in candidates for lung volume reduction surgery

Abstract. The aim of this study was to investigate whether spiral CT is superior to high-resolution computed tomography (HRCT) in evaluating the radiological morphology of emphysema, and whether the combination of both CT techniques improves the evaluation in patients undergoing lung volume reduction surgery (LVRS). The material consisted of HRCT (with 2-mm slice thickness) and spiral CT (with 10-mm slice thickness) of 94 candidates for LVRS. Selected image pairs from these examinations were evaluated. Each image pair consisted of one image from the cranial part of the lung and one image from the caudal part. The degree of emphysema in the two images was calculated by computer. The difference between the images determined the degree of heterogeneity. Five classes of heterogeneity were defined. The study was performed by visual classification of 95 image pairs (spiral CT) and 95 image pairs (HRCT) into one of five different classes of emphysema heterogeneity. This visual classification was compared with the computer-based classification. Spiral CT was superior to HRCT with 47% correct classifications of emphysema heterogeneity compared with 40% for HRCT-based classification (p<0.05). The combination of the techniques did not improve the evaluation (42%). Spiral CT is superior to HRCT in determining heterogeneity of emphysema visually, and should be included in the pre-operative CT evaluation of LVRS candidates.

Visual grading of emphysema severity in candidates for lung volume reduction surgery: Comparison between HRCT, spiral CT and density-masked images

Purpose: To investigate which of three types of CT imaging yielded the best results in estimating the degree of emphysema in patients undergoing evaluation for lung volume reduction surgery (LVRS), whether there was any difference in this regard between the cranial and caudal part of the lung, and whether the degree of emphysema had an impact on the estimation. Material and Methods: Four radiologists visually classified different degrees of emphysema on three different types of CT images into four groups. The degree of emphysema was calculated by a computer. The three types of images were as follows: HRCT images (2-mm slice thickness); spiral CT images (10-mm slice thickness); and density-masked images (spiral CT images printed with pixels below -960 HU, depicted in white). Results: The conventionally presented images from HRCT and spiral CT yielded the same results (60% respective 62% correct classifications) in assessing the degree of emphysema irrespective of localisation. Significantly improved results were obtained when the spiral CT images were presented as density-masked images (74%). Conclusion: There was no difference between HRCT and spiral CT in assessing the degree of emphysema in candidates for LVRS. Improvement can be achieved by the use of density-masked images.

Coronary angiography and thallium-201 single photon emission computed tomography in multiple vessel coronary artery disease

Polar presentations of selective coronary angiography and myocardial 201T1 SPECT were compared in 141 patients with multiple vessel disease, 80 with 3-vessel disease, 34 with 2-vessel disease and 27 post-bypass patients. Perfusion defects were present in 125/141 patients (89%) and were located within the area supplied by 194/359 stenotic arteries (54%) and 9 non-stenotic arteries. The type and extent of disease was correctly indicated by 201T1 SPECT in 16/80 patients (20%) with 3-vessel disease, 5/34 patients (15%) with 2-vessel disease and 8/27 post-bypass patients (30%). Perfusion defects indicated the artery with the most severe lesion in 107/125 patients (86%). False negative isotope studies were present in 15 patients (11%).

C-reactive protein and myocardial infarction during percutaneous coronary intervention

Objective.  To evaluate the prognostic information of preprocedural C‐reactive protein (CRP) levels in serum to predict myocardial infarction during percutaneous coronary interventions (PCI).

Catheter‐guided Open Ligation of a Pulmonary Artery to Left Atrium Connection

Congenital malformations causing mild cyanosis can be overlooked. A large intrapulmonary right pulmonary artery to left atrium connection was the unusual etiology of arterial oxygen desaturation and erythrocytosis in an asymptomatic 30-year-old patient. The shunt was not possible to detect at echocardiography. It was closed via a median sternotomy without the aid of cardiopulmonary bypass. A novel technique was to use an angiographic catheter inserted through the wide shunt into the left atrium before the operation to securely identify it at the surgical dissection.

Validation of a new system in quantitative coronary arteriography

Purpose: To validate ANCOR, a new system in quantitative coronary arteriography (QCA). Material and Methods: The validation procedure was performed by comparing the calibration factors of catheters filled with saline solution or contrast medium, and by measuring precision-drilled lumens in a test phantom filled with contrast medium. The results were compared with a well established and validated system, CMS. Results: The calibration test showed that the çalibration factors in the saline and contrast-medium catheters differed only a few percent when catheters with diameters of 2.0-2.67 mm were used. The phantom test showed that both systems overestimated smaller and larger diameters than these. The best results for both systems were achieved in the middle-diameter range. Conclusion: The ANCOR and CMS systems gave comparable results in catheter calibrations and phantom tests.

Thallium-201 Single Photon Emission Computed Tomography in Patients with Symptoms of Heart Disease and Non-Significant Coronary Artery Lesions

Polar presentations of coronary angiograms and myocardial 201T1 SPECT were compared in 44 patients without significant coronary artery disease (< 50% stenosis at angiography). Regions of reduced isotope activity (defects) were present in 18 patients (41%). Nine of these had angiographic and/or clinical evidence of non-coronary heart disease, such as documented or suspected myocardial infarction, dilated cardiomyopathy or other myocardial diseases. Such defects could be caused by impaired small vessel blood flow, abnormalities in cell membrane transport or relative differences in left ventricular wall thickness. In 9 patients defects were probably due to attenuation artifacts. Defects in patients with heart diseases were significantly larger than in those without obvious disease. The information content in coronary angiography and 201T1 SPECT overlap but are not congruent. Coronary angiography describes morphology of large coronary vessels, whereas 201T1 SPECT contains information of large and small vessel perfusion as well as membrane transport of 201T1 ions.