Evaluation of pleural disease using MR and CT. With special reference to malignant pleural mesothelioma

Our plain-English summary of Evaluation of pleural disease using MR and CT. With special reference to malignant pleural mesothelioma, by A. Knuuttila, L. Kivisaari, A. Kivisaari, et al (Acta Radiologica, 2001).

The study

• Authors: A. Knuuttila, L. Kivisaari, A. Kivisaari, M. Palomäki, P. Tervahartiala, K. Mattson
• Journal: Acta Radiologica
• Published: 2001;42(5):502-7
• Cited by: 32 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Purpose: To evaluate MR imaging and CT in differentiating malignant pleural mesothelioma from other malignancies or benign pleural disease.

Material And Methods: Thirty-four patients (18 pleural mesotheliomas, 9 other malignancies, 7 benign pleural diseases) were examined using enhanced CT and MR. Two radiologists reviewed the CT and two others the MR images. Comparisons were made between the diagnostic groups and the imaging methods.

Results: The abnormalities commonly found in malignant disease, but significantly less frequently in benign pleural disease, were focal thickening and enhancement of interlobar fissures. In mesothelioma, enhancement of interlobar fissures, tumour invasion of the diaphragm, mediastinal soft tissue or chest wall, were significantly more often observed than in other malignancies and MR was the most sensitive method. In other malignancies, invasion of bony structures was a more common finding and was also better shown by MR. The contrast-enhanced T1 fat-suppressed (CET1fs) sequence detected these features better than other MR sequences.

Conclusion: MR, especially the CET1fs sequence in three planes, gave more information than enhanced CT. Focal thickening and enhancement of interlobar fissures were early abnormalities indicating malignant pleural disease. MR could be clinically useful for differentiating mesothelioma from other pleural diseases.

In plain English

This study in Helsinki, Finland, compared contrast-enhanced MR imaging with contrast-enhanced CT scans in 34 patients with diffuse pleural disease examined between January 1997 and December 1998. Of these, 18 had malignant pleural mesothelioma, 9 had other cancers and 7 had benign pleural disease. Two radiologists read the CT scans and two others read the MR images, without knowing the patients' clinical details. Focal thickening and enhancement of the interlobar fissures (the clefts between lung lobes) were common in cancer and significantly less frequent in benign disease. Invasion of the diaphragm, mediastinal soft tissue and chest wall was significantly more frequent in mesothelioma than in other cancers, while invasion of bone was more common in the other cancers. MR showed all of these better than CT. CT showed pleural calcifications more accurately. One patient first diagnosed with benign pleuritis was diagnosed with mesothelioma 2.5 years later. The authors concluded that MR, especially one contrast-enhanced fat-suppressed sequence, gave more information than CT. They noted the findings could not be checked surgically and the study was small. The article does not discuss asbestos exposure.

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 diagnostic imaging study: each patient had both contrast-enhanced CT and contrast-enhanced MR. The scans were read independently and blinded by separate pairs of thoracic radiologists.
• Who was studied: 34 patients with diffuse pleural disease seen at Helsinki University Central Hospital, Finland, between January 1997 and December 1998: 29 men and 5 women, median age 62. They included 18 with malignant pleural mesothelioma, 9 with other malignancies (8 adenocarcinomas, 1 lymphoma) and 7 with benign pleural disease.
• Main results:
  • Focal thickening of the interlobar fissures and enhancement of the interlobar fissures were common in the malignant diseases and occurred significantly less often in benign pleural diseases.
  • Enhancement of interlobar fissures was seen in 39% of CT readings and 86% of MR (CET1fs) readings in mesothelioma patients. The figures were 0% (CT) and 33% (MR) in other malignancies, and 7% (CT) and 21% (MR) in benign pleural disease.
  • Invasion of the diaphragm, mediastinal soft tissue and chest wall was significantly more frequent in mesothelioma than in other malignancies. Invasion of bony structures was more often seen in other malignancies. All of these changes were better shown using MR.
  • Invasion of the diaphragm was seen in 36% of CT readings and 75% of MR readings in mesothelioma patients. The figures were 6% (CT) and 28% (MR) in other malignancies, and 0% (CT) and 28% (MR) in benign pleural disease.
  • Pleural calcifications were not associated with any particular diagnostic group, and CT depicted them more accurately than MR.
  • Detection of mediastinal lymph nodes (N1, N2 or N3) did not differ between the diagnostic groups.
  • In the majority of lesions, the contrast-enhanced T1-weighted fat-suppressed (CET1fs) MR sequence detected positive findings more sensitively than the other MR sequences.
  • One patient in the benign group, originally diagnosed with benign pleuritis, was diagnosed with histologically confirmed mesothelioma 2.5 years later. In that patient, MR had shown abnormal enhancement of an interlobar fissure that CT did not show.
  • Distinguishing smooth from focal pleural thickening was difficult on CT, giving poor agreement between the two CT radiologists. These changes were more uniformly interpreted on MR.
• The authors' conclusion: The authors concluded that MR, especially the CET1fs sequence in three planes, gave more information than enhanced CT. They concluded that focal thickening and enhancement of interlobar fissures are early signs of malignant pleural disease, and that MR can be clinically useful for differentiating pleural mesothelioma from other malignancy or from benign pleural diseases.
• Limitations the authors state:
  • The imaging findings could not be verified surgically. Verification was possible only from the pathological diagnosis.
  • Because the study was small, the authors' suggestion that focal pleural thickening points to mesothelioma was not statistically significant.
  • The authors' earlier hypothesis that MR better shows tumour growth through the diaphragm could not be confirmed, because this abnormality was seen in few cases.
  • N2 and N3 lymph nodes were seen slightly more often on MR than on CT, but the number of cases was small.

Topics

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

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, Mesothelioma, Diaphragm.

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