Asbestos-related pleural disease: value of dedicated magnetic resonance imaging techniques

Our plain-English summary of Asbestos-related pleural disease: value of dedicated magnetic resonance imaging techniques, by M.A. Weber, M. Bock, C. Plathow, et al (Investigative Radiology, 2004).

The study

• Authors: M.A. Weber, M. Bock, C. Plathow, K. Wasser, C. Fink, I. Zuna, A. Schmähl, I. Berger, H.U. Kauczor, S.O. Schoenberg
• Journal: Investigative Radiology
• Published: 2004;39(9):554-64
• Cited by: 30 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objectives: We sought to compare respiratory-gated high-spatial resolution magnetic resonance imaging (MRI) and radial MRI with ultra-short echo times with computed tomography (CT) in the diagnosis of asbestos-related pleural disease.

Methods: Twenty-one patients with confirmed long-term asbestos exposure were examined with a CT and a 1.5-T MR unit. High-resolution respiratory-gated T2w turbo-spin-echo (TSE), breath-hold T1w TSE, and contrast-enhanced fat-suppressed breath-hold T1w TSE images with an inplane resolution of less than 1 mm were acquired. To visualize pleural plaques with a short T2* time, a pulse sequence with radial k-space-sampling was used (TE = 0.5 milliseconds) before and after administration of Gd-DTPA. CT and MR images were assessed by 4 readers for the number and calcification of plaques, extension of pleural fibrosis, extrapleural fat, detection of mesothelioma and its infiltration into adjacent tissues, and detection of pleural effusion. Observer agreement was studied with the use of kappa statistics.

Results: The MRI protocol allowed for differentiation between normal pleura and pleura with plaques. Interobserver agreement was comparable for MRI and CT in detecting pleural plaques (median kappa = 0.72 for MRI and 0.73 for CT) and significantly higher with CT than with MRI for detection of plaque calcification (median kappa 0.86 for CT and 0.72 for MRI; P = 0.03). Median sensitivity of MRI was 88% for detection of plaque calcification compared with CT. For assessment of pleural thickening, pleural effusion, and extrapleural fat, interobserver agreement with MRI was significantly higher than with CT (median kappa 0.71 and 0.23 for pleural thickening, 0.87 and 0.62 for pleural effusion, and 0.7 and 0.56 for extrapleural fat, respectively; P < 0.05). For detection of mesothelioma, median kappa was 0.63 for MRI and 0.58 for CT.

Conclusion: High-resolution MR sequences and radial MRI achieve a comparable interobserver agreement in detecting pleural plaques and even a higher interobserver agreement in assessing pleural thickening, pleural effusion, and extrapleural fat when compared with CT.

In plain English

This study compared magnetic resonance imaging (MRI), including a radial technique with an ultra-short echo time, with computed tomography (CT) for asbestos-related pleural disease. Twenty-one patients (2 women, 19 men) in Heidelberg, Germany, with confirmed long-term asbestos exposure and pleural plaques seen on CT had both scans. Four readers independently assessed the images, and the study measured how closely the readers agreed with one another (kappa values). Agreement on pleural plaques was similar for the two methods: median kappa 0.72 for MRI and 0.73 for CT. CT gave higher agreement on plaque calcification (0.86 versus 0.72 for MRI). Compared with CT, MRI detected calcification with a median sensitivity of 88%. MRI gave significantly higher agreement for pleural thickening (0.71 versus 0.23), pleural effusion (0.87 versus 0.62) and extrapleural fat (0.7 versus 0.56). Mesothelioma was confirmed in 4 patients. For detecting it, agreement did not differ significantly (0.63 for MRI versus 0.58 for CT). The authors called this a preliminary study and noted that agreement between readers does not necessarily mean accuracy. They concluded that MRI reliably differentiated normal from abnormal pleura.

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: Imaging comparison study of MRI versus CT in consecutively enrolled patients, with 4 independent, blinded readers; reader-to-reader agreement was measured with kappa statistics, and MRI sensitivity and specificity were calculated using CT as the comparison
• Who was studied: 21 patients (2 women, 19 men; median age 64, range 47 to 80) with confirmed long-term asbestos exposure and asbestos-related pleural disease. They were referred to the Clinic for Thoracic Disease Heidelberg for an expert opinion on possible occupational disease and then to the German Cancer Research Center for MRI. Enrollment lasted 12 consecutive months; calendar years are not stated.
• Exposure: Confirmed long-term asbestos exposure, with occupational disease confirmed and pleural plaques shown on CT before MRI. Fiber types, jobs and doses are not reported. The study itself compared imaging methods (MRI versus CT).
• Main results:
  • Agreement between readers for detecting pleural plaques: median kappa 0.72 (range 0.44 to 0.82) for MRI and 0.73 (range 0.54 to 0.80) for CT. The difference was not significant.
  • Compared with CT, MRI had a median sensitivity of 97.5% (range 97 to 100%) and a median specificity of 100% (range 50 to 100%) for detecting pleural plaques.
  • Agreement for plaque calcification was significantly higher with CT: median kappa 0.86 (range 0.76 to 0.98) for CT versus 0.72 (range 0.66 to 0.92) for MRI.
  • Compared with CT, MRI had a median sensitivity of 88% (range 85 to 92%) and a median specificity of 94% (range 84 to 100%) for detecting plaque calcification.
  • In retrospect, each of the 4 readers could identify on MRI all plaques that CT had detected.
  • Agreement for pleural thickening was significantly higher with MRI: median kappa 0.71 (range 0.46 to 1.00) versus 0.23 (range 0.13 to 0.70) for CT.
  • Agreement for pleural effusion was significantly higher with MRI: median kappa 0.87 (range 0.74 to 1.00) versus 0.62 (range 0.45 to 1.00) for CT.
  • Agreement for extrapleural fat was significantly higher with MRI: median kappa 0.7 (range 0.70 to 1.00) versus 0.56 (range 0.32 to 1.00) for CT.
  • Mesothelioma was confirmed by tissue examination in 4 patients, and bronchial carcinoma in 3.
  • For detecting mesothelioma there was no significant difference in agreement: median kappa 0.63 (range 0.53 to 1.00) for MRI and 0.58 (range 0.58 to 1.00) for CT.
  • All readers found the T2-weighted MRI sequence most suitable for assessing pleural effusions in all cases.
• The authors' conclusion: The authors concluded that MRI reliably differentiated between normal and abnormal pleura, and that pleural thickening and effusion could be detected with higher interobserver agreement by MRI than by CT.
• Limitations the authors state:
  • The authors describe the study as preliminary.
  • The authors note that agreement between readers does not necessarily mean the readings are accurate.
  • Blurring artifacts on the radial MRI images reduced spatial resolution.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis, Pleural plaques and thickening.

Medical terms in this study, explained in our Lexicon: Asbestos-Related Pleural Disease, Asbestos Exposure, Pleural Plaques, Fibrosis, Mesothelioma, Pleural Effusion, Pleura, Pleural Thickening.

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