How can we use positron emission tomography/computed tomography more accurately for characterization of asbestos-related pleural thickening?

Our plain-English summary of How can we use positron emission tomography/computed tomography more accurately for characterization of asbestos-related pleural thickening?, by F.S. Simsek, M. Cakmak, D. Kuslu, et al (Archives of Medical Science, 2023).

The study

• Authors: F.S. Simsek, M. Cakmak, D. Kuslu, T.A. Balci, E. In, I.H. Ozercan, Y. Narin
• Journal: Archives of Medical Science
• Published: 2023;19(2):385-391
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Introduction: There is no consensus about the standardized uptake value maximum (SUVmax) cut-off value to characterize pleural thickening worldwide. Sometimes, this causes unnecessary invasive diagnostic procedures. Our first aim is to determine a cut-off value for SUVmax. Secondly, we try to answer the following question: If we use this cut-off value together with morphological parameters, can we differentiate benign thickening from malignant pleural mesothelioma (MPM) more accurately?

Material And Methods: Thirty-seven patients who underwent 2-deoxy-2-fluoro-D-glucose ([18F]FDG) positron emission tomography/computed tomography (PET/CT) before pleural biopsy were included the study. All of patients had histopathologically proven primary pleural disease. Their [18F]FDG-PET/CT imaging reports were re-assessed. If a patient's SUVmax or size of the thickening was not mentioned in the report, we calculated it with their [18F]FDG-PET/CT.

Results: Age, pleural effusion, size, and SUVmax were found to have a relationship with MPM. We found the size > 14 mm, and SUVmax > 4.0 as cut-off values for MPM. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for size > 14 mm were found to be 86.4%, 85.2%, 82.6%, 88.5%, respectively. For SUVmax > 4.0, sensitivity, specificity, PPV, NPV were 90.9%, 87.0%, 85.1%, 92.2%, respectively.

Conclusions: If a patient has SUVmax > 4.0 and/or size > 14 mm, the risk of MPM is high. These patients should undergo biopsy. If a patient's SUVmax < 4.0, size < 14 mm and does not have pleural effusion, he/she has low risk for MPM. These patients can undergo the follow-up. If a patient's SUVmax < 4, size < 14, and has pleural effusion the MPM risk is approximately 4%. These patients can undergo biopsy/cytology/follow-up. Novel studies are needed for these patients.

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In plain English

This retrospective study asked whether PET/CT scan measurements could separate benign pleural thickening from malignant pleural mesothelioma in patients with asbestos-related pleural thickening. Of 98 patients scanned in 2013 to 2017, 37 without distant spread who had a pleural biopsy were included: 25 (67.6%) had mesothelioma and 12 had benign thickening. Of patients with pleural effusion (fluid around the lung), 83.3% had mesothelioma, but only 56.0% of mesothelioma patients had effusion. Thickening pattern and calcification did not differ significantly. In the results section, thickening over 14 mm had 85.7% sensitivity and 83.3% specificity, and an uptake value (SUVmax) above 4.0 had 88.0% and 83.3%. The abstract prints different figures. Twenty-four of the 25 mesothelioma patients had one of these findings, and 7 of 12 benign patients had neither and no effusion. The authors concluded that patients with SUVmax above 4.0 or size above 14 mm should have a biopsy, while those below both and without effusion are at low risk and could be followed. They noted the retrospective design and few benign cases.

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: retrospective diagnostic study comparing PET/CT findings with biopsy results
• Who was studied: 37 patients with asbestos-related pleural thickening and no distant metastases on PET/CT, all with pathologically proven primary pleural disease (25 malignant pleural mesothelioma, 12 benign pleural thickening). They were selected from 98 patients who had PET/CT between 1 January 2013 and 31 December 2017. The authors are from Turkish institutions.
• Exposure: Asbestos exposure described only in general terms as long-term exposure related to the region. No fiber types, jobs or doses were reported. The study measured [18F]FDG-PET/CT uptake (SUVmax) and CT features of the thickening.
• Main results:
  • 25 of 37 patients (67.6%) were diagnosed with malignant pleural mesothelioma; the other 12 had benign pleural thickening
  • Among patients with pleural effusion, 83.3% were diagnosed with mesothelioma (p = 0.01)
  • Only 56.0% of mesothelioma patients had pleural effusion
  • Diffuse or nodular thickening pattern and pleural calcification did not differ significantly between mesothelioma and benign thickening (p greater than 0.1)
  • Mean SUVmax was 2.96 in benign pleural thickening and 10.6 in mesothelioma. Mean thickening size, from Table II, was 11.8 mm in benign thickening and 25.6 mm in mesothelioma. Both differences were statistically significant.
  • For thickening size above 14 mm: sensitivity 85.7%, specificity 83.3%, PPV 90.0%, NPV 76.9% (results section figures)
  • For size above 14 mm, the area under the ROC curve was 0.887 (standard error 0.05; 95% confidence interval 0.772 to 1.0)
  • For SUVmax above 4.0: sensitivity 88.0%, specificity 83.3%, PPV 91.7%, NPV 76.9%
  • False positive results were associated with inflammation. For example, one patient diagnosed with pleuritis had an SUVmax of 5.8.
  • 24 of 25 mesothelioma patients (96.0%) had SUVmax above 4.0 or size above 14 mm. The remaining patient had pleural effusion.
  • 7 of 12 benign pleural thickening patients (58.3%) had SUVmax below 4.0, size below 14 mm and no pleural effusion
• The authors' conclusion: The authors concluded that patients with SUVmax above 4.0 or thickening above 14 mm should undergo biopsy. Patients below both values without pleural effusion have a low likelihood of mesothelioma and can be followed up. For those below both values with effusion, mesothelioma cannot be excluded, and biopsy or cytology may be appropriate. They called for multicentre, high-volume prospective studies.
• Limitations the authors state:
  • Retrospective design
  • Few biopsy-proven benign pleural thickening cases, which the authors attributed to their biopsy selection criteria
  • MRI and contrast-enhanced CT results were not included

Topics

Medical terms in this study, explained in our Lexicon: Pleural Thickening, Pleural Mesothelioma, Pleural Biopsy, Pleural Effusion, Biopsy, Cytology.

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