FDG PET/CT for Postoperative Surveillance in Malignant Pleural Mesothelioma: Temporal Evolution of Postsurgical Metabolic Activity and Diagnostic Performance for Recurrence Detection

Our plain-English summary of FDG PET/CT for Postoperative Surveillance in Malignant Pleural Mesothelioma: Temporal Evolution of Postsurgical Metabolic Activity and Diagnostic Performance for Recurrence Detection, by S.H. Boo, S.J. Kwon, S.W. Moon, et al (Cancers, 2026).

The study

• Authors: S.H. Boo, S.J. Kwon, S.W. Moon, Y.S. Kim, S.H. Hong, I.R. Yoo
• Journal: Cancers
• Published: 2026;18(12)
• Read it: PubMed · Publisher · Free full text

Abstract

Background/Objectives: Differentiating recurrent disease from postsurgical changes on 18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) remains challenging in malignant pleural mesothelioma (MPM). This study aimed to characterize the temporal patterns of postsurgical FDG uptake and evaluate the diagnostic performance of FDG PET/CT for detecting recurrent disease after radical surgery. Methods: We retrospectively analyzed 91 postsurgical PET/CT scans from 45 patients with MPM who underwent extrapleural pneumonectomy (EPP; n = 29) or pleurectomy/decortication (P/D; n = 16). Scans were stratified into four postoperative time intervals: <6 months, 6 to <12 months, 12 to <24 months, and ≥24 months. FDG uptake in the postsurgical bed and local recurrent lesions was quantified using maximum standardized uptake value ratios normalized to the mediastinal blood pool and liver. Recurrence was confirmed by histopathology or follow-up imaging. Results: Postsurgical FDG uptake showed a time-dependent decline, with significantly lower uptake beyond 24 months postoperatively (p < 0.05). EPP patients demonstrated significantly higher postsurgical FDG uptake than P/D patients (p < 0.01). FDG PET/CT identified occult recurrence in 23.4% of CT-negative scans. Local recurrent lesions showed significantly higher FDG uptake than postsurgical changes across all postoperative intervals (p < 0.001). Conclusions: Postsurgical FDG uptake in MPM demonstrates a time-dependent decline, and surgical extent is an important determinant of background metabolic activity. Despite this variable background, FDG PET/CT demonstrated high diagnostic accuracy for detecting recurrent disease, including CT-occult recurrences. Incorporating surgical type and postoperative interval into PET/CT interpretation may improve diagnostic accuracy in postoperative MPM surveillance.

In plain English

This retrospective study from one hospital in Seoul, Korea, reviewed 91 FDG PET/CT scans (scans that show where a sugar-based tracer collects) taken after surgery in 45 patients with malignant pleural mesothelioma operated on between March 2009 and December 2022. Twenty-nine had extrapleural pneumonectomy and 16 had pleurectomy/decortication, a lung-sparing operation. The study did not examine asbestos exposure. Tracer uptake in the surgical area was lower in scans taken 24 months or more after surgery than in earlier scans. It was higher after extrapleural pneumonectomy than after pleurectomy/decortication, and higher after radiotherapy. Recurrence was confirmed in 49 of 91 scans. In 47 scans where CT showed nothing suspicious, PET/CT found confirmed recurrences in 11 (23.4%). Overall sensitivity was 100.0% and specificity 95.2%. In the 11 examinations checked by tissue sampling, specificity was 33.3%. The authors concluded that PET/CT showed high diagnostic accuracy. They cautioned that most results were confirmed only by follow-up imaging, which could introduce bias, and that the study was small and single-center.

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 single-center study of diagnostic imaging (FDG PET/CT) after surgery
• Who was studied: 45 patients (30 male, 15 female; median age 65) with malignant pleural mesothelioma who had radical surgery at one institution in Seoul, Korea, between March 2009 and December 2022, contributing 91 postoperative FDG PET/CT scans
• Exposure: Not an asbestos exposure study. The factors studied were type of surgery (extrapleural pneumonectomy, 29 patients; pleurectomy/decortication, 16 patients), radiotherapy, and time since surgery, in relation to FDG uptake on PET/CT. No fiber types or asbestos doses are reported.
• Main results:
  • Across the four time intervals, postsurgical uptake did not differ significantly overall (p = 0.097 for OP/BP; p = 0.061 for OP/L).
  • Scans taken 24 months or more after surgery had lower postsurgical uptake than scans taken earlier (combined under 24 months): OP/BP 2.8 ± 1.4 vs 2.1 ± 1.1, p = 0.015; OP/L 1.9 ± 0.9 vs 1.4 ± 0.7, p = 0.012. At patient level this trend was not statistically significant.
  • Postsurgical uptake was higher after extrapleural pneumonectomy (63 scans) than after pleurectomy/decortication (27 scans): OP/BP 2.9 ± 1.4 vs 2.0 ± 0.8, p = 0.002; OP/L 2.0 ± 0.9 vs 1.4 ± 0.6, p = 0.001.
  • Scans after radiotherapy (53) had higher postsurgical uptake than scans without prior radiotherapy (37): OP/BP 3.0 ± 1.5 vs 2.0 ± 0.8, p less than 0.001.
  • Disease recurrence was confirmed in 49 of the 91 scans (53.8%).
  • Among 47 scans with no suspicious CT findings, PET/CT identified confirmed recurrence in 11 (23.4%). Two further PET-positive findings in this group were false positives.
  • PET/CT reclassified 6 of the 44 CT-positive scans as benign postsurgical changes.
  • At scan level (91 scans), PET/CT had sensitivity 100.0%, specificity 95.2%, positive predictive value 96.1%, negative predictive value 100.0% and accuracy 97.8% for detecting any recurrence.
  • Among the 11 examinations with histopathological confirmation, PET/CT had sensitivity 100.0%, specificity 33.3% and accuracy 81.8%.
  • Using only the first postoperative scan per patient, sensitivity was 100.0% (19/19) and specificity 96.2% (25/26).
  • Local recurrent lesions had higher uptake than postsurgical changes: blood-pool ratio 4.3 ± 1.8 vs 2.6 ± 1.3; liver ratio 3.0 ± 1.3 vs 1.8 ± 0.9 (both p less than 0.001).
  • Distant metastatic disease was found in 23 of 49 recurrence-confirmed scans (46.9%).
• The authors' conclusion: The authors concluded that postsurgical FDG uptake declines over time and is affected by the extent of surgery. Despite this variable background, they concluded, FDG PET/CT showed high diagnostic accuracy for recurrence, including recurrences not seen on CT, and surgical type and time since surgery should be taken into account when reading scans.
• Limitations the authors state:
  • Retrospective, single-center design and relatively small sample size may limit generalizability.
  • Multiple scans per patient may introduce statistical non-independence.
  • Few scans in the late period (24 months or more) may have limited statistical power for the time analysis.
  • Not all cases had tissue confirmation; relying on follow-up imaging, sometimes including PET/CT itself, may introduce verification and incorporation bias, and specificity was much lower in the tissue-confirmed subgroup.
  • Survivor-selection bias in the late period cannot be excluded.
  • Quantitative analysis may be less reliable with diffuse or miliary recurrence patterns.
  • Differences in treatment protocols and in timing of radiotherapy and scans may have influenced uptake; residual confounding cannot be excluded.

Topics

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, CT Scan, Extrapleural Pneumonectomy (EPP), Pleurectomy/Decortication (P/D), Histopathology.

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