Different imaging methods in the assessment of radiation-induced lung injury following hemithorax irradiation for pleural mesothelioma

Our plain-English summary of Different imaging methods in the assessment of radiation-induced lung injury following hemithorax irradiation for pleural mesothelioma, by P. Maasilta, L. Kivisaari, K. Mattson (Radiotherapy and Oncology, 1990).

The study

• Authors: P. Maasilta, L. Kivisaari, K. Mattson
• Journal: Radiotherapy and Oncology
• Published: 1990;19(2):159-67
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

We have characterized the radiation-induced lung injury on serial chest X-rays, CTs and ultralow field MRs and evaluated the clinical value and cost/benefit ratio of the different imaging methods in 30 patients receiving high-dose hemithorax irradiation for pleural mesothelioma. Lung injury was severe in all patients, but non-specific and essentially as described in text-books. CT provided no clinically relevant, cost effective diagnostic advantage over conventional X-rays in the detection of early or late radiation-induced lung injury, but it was necessary for the evaluation of the disease status of mesothelioma. The possible advantage of MR over CT could not be evaluated and needs further studies. Optimal time-points for imaging CTs or MRs to detect early radiation-induced lung injury following high dose hemithorax irradiation were during the latter part of treatment or very shortly after the end of irradiation. Late injury or irreversible fibrosis developed rapidly after 6 months and was clearly documented by chest X-rays. We recommend serial chest X-rays at 1-2, 6 and 12 months following radiotherapy as a cost-effective method for the detection of radiation-induced lung injury with additional CTs to document the stage of mesothelioma, when needed.

In plain English

This study from Helsinki University Central Hospital followed 30 patients with malignant pleural mesothelioma who were given high-dose radiation to one whole side of the chest. It compared how chest X-rays, CT scans and, in six patients, an ultralow field MR scanner showed radiation damage to the lung. Some patients had a history of asbestos exposure, but none had asbestosis as defined by International Labour Office criteria. Lung injury began during the latter part of radiotherapy or within a month after it, and then progressed. At 12 months all surviving patients had nearly maximal or maximal injury. CT detected changes earlier and was the only reliable way to judge the tumour's response. However, a CT cost 12.5 times as much as an X-ray and took 6 times longer. The authors concluded that CT gave no cost-effective, clinically relevant advantage over X-rays for detecting the lung injury. They recommended serial chest X-rays at 1-2, 6 and 12 months, with CTs to stage the mesothelioma when needed. They noted they could not relate the radiation dose to the injury.

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: Serial imaging comparison (chest X-ray, CT, ultralow field MR) carried out within three prospective, consecutive, open phase II treatment studies of high-dose hemithorax irradiation, with a cost comparison of the imaging methods
• Who was studied: 30 patients with histologically verified malignant pleural mesothelioma at Helsinki University Central Hospital, Finland (mean age 58, range 39 to 71; 73% male; 67% current or former smokers)
• Exposure: The exposure studied was radiation therapy to the whole hemithorax, given in three schedules: 55 Gy, 70 Gy, and 35 + 36 Gy. Asbestos was not the exposure studied. Some patients had a history of asbestos exposure, but none had asbestosis as defined by the ILO criteria.
• Main results:
  • Evaluable patients numbered 14 in the 55 Gy group, 6 in the 70 Gy group and 10 in the 35 + 36 Gy group. In total, 117 X-rays and CTs and 32 MRs were evaluated.
  • Radiation-induced lung injury began during the latter part of radiotherapy or by one month after it, and then steadily progressed.
  • At 6 months, every treatment group included patients with no normal aerated lung left on the irradiated side.
  • At 12 months, all surviving patients had nearly maximal or maximal radiological injury.
  • Changes were detected earlier on CT than on X-ray.
  • Tumour response of mesothelioma could be evaluated reliably only with CT.
  • Compared with a chest X-ray, one CT cost 12.5 times as much and took 6 times longer. In 1988 a chest X-ray cost 150 FIM (36 US dollars) and a CT 1877 FIM (447 US dollars).
  • Chest X-rays could be obtained from all patients up to death; CTs could not.
  • In the pilot of six patients, ultralow field MR showed changes earlier and more pronounced than CT in the early stages.
  • The authors judged that CT provided no cost-effective, clinically relevant advantage over X-rays in imaging radiation injury.
• The authors' conclusion: The authors recommended serial chest X-rays at 1-2, 6 and 12 months after irradiation as a cost-effective way to detect radiation lung injury, with additional CTs to document the stage of mesothelioma when needed.
• Limitations the authors state:
  • Without computer-assisted dosimetry, the authors could not relate the radiation dose absorbed in the lung to the injury seen.
  • The MR machine was ultralow field, with poor resolution for lung tissue.
  • Some changes read as radiation injury on X-rays may have been tumour or pleural fluid, which may have led to underestimating the value of CT.
  • After 6 months, CTs and MRs could not be obtained systematically in the 70 Gy group.
  • The injury in these patients was exceptionally severe. With less severe injury, CT or MR might have been more effective.
  • The cost calculation method applies only where costs such as wages and machinery are similar to those at this hospital.

Topics

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

Medical terms in this study, explained in our Lexicon: Hemithorax, Pleural Mesothelioma, Chest X-Ray, Mesothelioma, Fibrosis.

Related studies

• Changes in surfactant in bronchoalveolar lavage fluid after hemithorax irradiation in patients with mesothelioma — M. Hallman, P. Maasilta, et al. (1990)
• Patterns of failure, toxicity, and survival after extrapleural pneumonectomy and hemithoracic intensity-modulated radiation therapy for malignant pleural mesothelioma — D.R. Gomez, D.S. Hong, et al. (2013)
• Radiation pneumonitis in a patient exposed to asbestos — R.F. Ashford, J. Maher, et al. (1981)
• Unusual radiologic findings in the thorax after radiation therapy — B. Mesurolle, S.D. Qanadli, et al. (2000)
• Hemithoracic radiation therapy after extrapleural pneumonectomy for malignant pleural mesothelioma: Toxicity and outcomes at an Australian institution — A. Bece, M.M. Tin, et al. (2015)
• Single-institution experience of intensity-modulated radiotherapy for malignant pleural mesothelioma at University of Catania — C. Spatola, C. Militello, et al. (2018)

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