Magnetic resonance imaging of the thorax in the evaluation of asbestosis

Our plain-English summary of Magnetic resonance imaging of the thorax in the evaluation of asbestosis, by S.I. Bekkelund, U. Aasebø, C. Pierre-Jerome, et al (The European Respiratory Journal, 1998).

The study

• Authors: S.I. Bekkelund, U. Aasebø, C. Pierre-Jerome, J. Holmboe
• Journal: The European Respiratory Journal
• Published: 1998;11(1):194-7
• Cited by: 8 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The purpose of the study was to evaluate the accuracy of magnetic resonance imaging (MRI) in detecting subclinical morphological changes caused by asbestos exposure. Conventional chest radiographs according to the International Labour Organisation (ILO) categories 0-11 and spirometric data were compared with MRI in 17 men with mean (+/-2SD) asbestos exposure time of 24.6+/-13.0 yrs. Mean age was 62.0+/-9.4 yrs. The inclusion criterion was an ILO score of 2 or more. Electrocardiographic registrations and antirespiratory movement artefact techniques were used in all MRI examinations to avoid movement artefacts. Mean ILO grading was found to be 7.7+/-3.8 on chest radiography and 9.8+/-2.0 with MRI (p=0.01). Five patients had a higher ILO stage as evaluated by MRI, but in nine patients the staging remained unchanged. MRI revealed mediastinal adenopathy in four patients. Forced expiratory volume in one second (expressed as a percentage of the predicted value) was negatively correlated with ILO score as assessed by MRI (r=-0.4, p=0.032). Magnetic resonance imaging seems to be more sensitive than conventional radiographs in detecting subclinical fibrosis as well as the extent of pleural asbestosis.

In plain English

This short report from Tromsø University Hospital in North Norway compared chest MRI (magnetic resonance imaging) with ordinary X-rays in men with known asbestosis. Twenty male outpatients were included. They had been exposed to asbestos at work as mechanics, carpenters or fishermen for an average of 24.5 years. Three could not have MRI because of claustrophobia, breathlessness or obesity. Physicians scored both kinds of image on the International Labour Organisation (ILO) scale, which runs from 0 to 11. The average score was 7.7 on X-ray and 9.8 on MRI (p=0.01). Lung fibrosis was seen in 5 subjects on X-ray and 13 on MRI; the printed percentages fit neither 17 nor 20 patients. Nine subjects scored higher on MRI, and none scored lower. Higher MRI scores were linked to lower lung function (FEV1); X-ray scores were not. In one patient, MRI showed a round atelectasis (a rounded area of collapsed lung) that the X-ray did not show. The authors concluded that MRI seems more sensitive than X-rays. They noted the small number of patients and the lack of comparison with CT scans. Other patient numbers in the article also conflict.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Comparative imaging study (short report) comparing MRI with conventional chest radiographs and spirometry in the same patients
• Who was studied: 20 male outpatients with known asbestosis at the pulmonary department of Tromsø University Hospital, North Norway. Mean age 62.0 years; 15 were smokers. Three were excluded from MRI (claustrophobia, dyspnoea, obesity).
• Exposure: Occupational asbestos exposure as mechanics, carpenters or fishermen, often in more than one profession. Mean exposure time 24.5 years. Fiber type not stated.
• Main results:
  • Mean ILO score was 7.7 (plus or minus 3.8) on chest radiography and 9.8 (plus or minus 2.0) on MRI, p=0.01
  • Fibrosis was found in 5 subjects on radiography and in 13 on MRI. The article prints these as 33% and 87%, which correspond to 15 subjects, not the 17 who had MRI or the 20 who were included.
  • Nine subjects (45%) had a higher ILO score when plaques were assessed by MRI; no subject scored lower on MRI than on radiograph
  • ILO score on MRI was negatively correlated with FEV1 percentage predicted (r=-0.4, p=0.032); ILO score on radiograph was not associated with lung function
  • Years of asbestos exposure correlated with ILO score on radiograph (r=0.56, p=0.016) but not with ILO score on MRI
  • MRI identified parahilar adenopathies not detectable on radiographs, and in one patient a mass consistent with round atelectasis not visualized on the chest radiograph
  • No evidence of increased pathology was found in smokers
• The authors' conclusion: The authors concluded that MRI seems to be more sensitive than conventional radiographs in displaying subclinical fibrosis and the degree of pleural plaques, and that whether MRI is superior to high-resolution CT remains to be investigated.
• Limitations the authors state:
  • CT scans were not performed for comparison
  • Limited number of patients and no comparison with high-resolution CT
  • MRI failed to show interlobular septal thickening, parenchymal bands and honeycombing, which are identified on CT

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis.

Medical terms in this study, explained in our Lexicon: Thorax, Asbestos Exposure, Chest X-Ray, Staging, Fibrosis.

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