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R J Lamers

Publications and source records attributed to R J Lamers.

7 recordsLinked to original sources
PubMed1995

Scanner conformity in CT densitometry of the lungs.

PURPOSE: To quantify inter- and intrascanner conformity in computed tomographic (CT) densitometry of the lungs. MATERIALS AND METHODS: With six scanners from four manufacturers, a lung densitometry protocol with several variations was applied for performance comparison. Phantoms included water, air, and a humanoid thorax phantom equipped with a dog lung and exchangeable pseudolungs of polyethylene foam. RESULTS: All scanners produced acceptable CT numbers (Hounsfield units) for water, but some not for air. An incorrect calibration of air density affected all CT numbers at lung densities, but the error was easily correctable. Some systems were more sensitive to object size than others were. Sensitivity of CT numbers to section thickness, reconstruction filter, zoom factor, and table height was small, except for two scanners in relation to section thickness. CONCLUSION: After correction for poor air calibration, scanner conformity was acceptable when the reproducibility of lung densitometry in clinical practice was set as a reference.

Absorptiometry, Photon↗
PubMed1990

A forme fruste of Marfan's syndrome: case history.

A thirty nine year old woman presented with multiple aneurysms and dissections of the arterial system secondary to cystic medial necrosis is presented. After assessment of the family history a diagnosis of a forme fruste of Marfan's syndrome was made. Preoperative consideration of this rare diagnosis is important for treatment and surgical management.

Abnormalities, Multiple↗
PubMed1989

[Once again, the routine preoperative thorax photo].

A prospective study of the influence of radiological findings upon operation policy was carried out in 810 patients over 40 years of age who underwent elective non cardiopulmonary surgery. Only in 5 patients did it appear that a preoperative X-ray yielded any relevant extra information, and only in 3 cases was the operation planning influenced. If no preoperative chest X-rays has been taken, all except one of the significant abnormalities would have been discovered anyway. By differentiating between patients graded ASA 1 and those classed ASA 2 or higher, it would be possible to reduce the number of preoperative chest X-rays by 41% without any loss of precision. Preoperative chest X-rays in patients over 40 years of age scheduled for non-cardiopulmonary surgery can be restricted to those whose history requires further radiological analysis.

Adult↗
PubMedDate not supplied

Computed tomographic staging of esophageal carcinoma: a study on interobserver variation and correlation with pathological findings.

Despite numerous reports on the efficacy of CT in the staging of esophageal carcinoma, no data are available on the reproducibility of the procedure. Three experienced radiologists independently reviewed the CT scans of 35 patients retrospectively. Calculation of interobserver variation was performed using the kappa statistic. The CT findings of each observer were subsequently correlated with the surgical and pathological findings of 17 patients. There was a large interobserver variation concerning involvement of the aorta, pulmonary vessels, vertebral column, stomach and lymph nodes, ranging from poor to excellent agreement. Agreement between observers on extension of the disease to the tracheobronchial tree, pericardium and liver was good or excellent. Agreement between the CT findings of all observers and the surgical findings for invasive growth was poor. CT pathological correlation of the three observers showed sensitivities ranging from 50 to 57%, specificities ranging from 50 to 60% and accuracies ranging from 46 to 71%. It can be concluded from this study that patients with positive CT findings for involvement of the tracheobronchial tree, the pericardium and the liver should be considered unresectable for cure. Negative findings, however, should be interpreted with caution, because involvement of other structures may still be present. Despite optimistic reports on the efficacy of CT in the pretherapy staging of esophageal neoplasms, this modality has its limitations.

Adenocarcinoma↗
PubMedDate not supplied

Enteroclysis. Improved performance using a flow inducer.

In enteroclysis the flow rate of the barium is important but not easily controlled with an infusion bag system. To improve the technique, an electric flow inducer was used in 156 consecutive examinations to infuse the barium suspension at a constant rate of 75 ml/min. Detailed demonstration of mucosal folds was achieved in 90 per cent. The examinations were of moderate quality in 8 per cent and of poor quality in 2 per cent. The maximum transit time was 20 minutes and the total examination time never exceeded 35 minutes. Sensitivity and specificity were 94 and 97 per cent, respectively. Examinations indicated by specific small bowel symptoms had a positive yield of 49 versus 13 per cent with non-specific indications. Both examination performance and patient tolerance were improved.

Adolescent↗