18-FDG positron emission tomography in the evaluation of malignant pleural diseases - a pilot study

Our plain-English summary of 18-FDG positron emission tomography in the evaluation of malignant pleural diseases - a pilot study, by A. Carretta, C. Landoni, G. Melloni, et al (European Journal of Cardio-thoracic Surgery, 2000).

The study

• Authors: A. Carretta, C. Landoni, G. Melloni, G.L. Ceresoli, A. Compierchio, F. Fazio, P. Zannini
• Journal: European Journal of Cardio-thoracic Surgery
• Published: 2000;17(4):377-83
• Cited by: 82 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objective: The diagnostic approach to pleural diseases may be difficult. The CT scan, which is the current diagnostic technique, has limited accuracy both in the differentiation between benign and malignant pleural diseases and in the diagnosis of primary and metastatic pleural neoplasms. Invasive procedures, such as thoracoscopy, are therefore frequently required to complete the diagnostic approach. The increasing incidence of malignant pleural mesothelioma has led to the development of new treatment strategies, which still need to be fully validated. There is, therefore, a need for new diagnostic techniques that can lead to a definite diagnosis and a satisfactory evaluation of the response to treatment. Encouraging results have been reported with the F-18-labeled analogue of 2-deoxyglucose (18-FDG) positron emission tomography (PET) in the evaluation of chest tumors such as lung cancer. The aim of this study was to evaluate the role of 18-FDG PET in the diagnostic assessment of pleural diseases.

Methods: Patients with CT scan evidence of pleural thickening, or fluid, entered a study to evaluate the accuracy of 18-FDG PET in diagnosing pleural diseases. Image analysis was performed both with visual interpretation and using a semiquantitative method, standardized uptake values (SUV), on coronal, sagittal and axial reconstructions. The results of PET imaging were compared to histological data. PET was also performed before and after treatment in patients who underwent chemotherapy to evaluate the accuracy of this technique in the assessment of the response.

Results: Fourteen patients entered the study. Histology demonstrated a malignant pleural disease in 13 patients; malignant pleural mesothelioma in ten patients, adenocarcinoma in two and liposarcoma in one. Benign pleural disease was diagnosed in the remaining patient. PET assessment demonstrated significant 18-FDG uptake in 12 of the 13 patients with a malignant disease, also revealing distant metastases in two of them. A false-negative result was observed in a patient with an epithelial mesothelioma. The overall accuracy was 92%. A benign pleural disease without significant uptake was correctly diagnosed in another patient. An aspecific uptake was observed in two patients who had undergone pleurectomy and intrapleural chemotherapy. A decreased tracer uptake was observed after chemotherapy in four patients.

Conclusions: These preliminary results demonstrate that 18-FDG PET may have a great potential, both in the differential diagnosis of pleural diseases and in the evaluation of the response to treatment. At present, however, histological thoracoscopic diagnosis remains mandatory before planning treatment. Further studies in larger groups of patients are needed to draw definite conclusions on the role of PET in the assessment of pleural diseases.

In plain English

This small pilot study, from a hospital in Milan, Italy, tested whether a PET scan using the tracer 18-FDG could tell malignant from benign pleural disease. Fourteen patients whose CT scans showed pleural fluid, masses or thickening had PET scans, and the results were compared with tissue diagnosis. Ten patients had malignant mesothelioma, two adenocarcinoma, one liposarcoma and one benign pleural fibrosis. PET identified malignant disease in 12 of the 13 patients with cancer. The one missed case was a patient with epithelial mesothelioma. The authors reported a sensitivity of 92% and an accuracy of 92%. In four mesothelioma patients scanned before and after chemotherapy, tracer uptake fell while CT stayed substantially stable. Two other patients were excluded because their uptake was read as an effect of recent treatment. The authors concluded that PET was encouraging but could not replace biopsy or thoracoscopy, partly because it cannot tell mesothelioma from other tumors, and that larger studies were needed. The article did not report patients' 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: Pilot diagnostic study (small case series) comparing 18-FDG PET results with histological diagnosis, with PET repeated before and after chemotherapy in some patients
• Who was studied: 14 patients at the authors' institution in Milan, Italy, with CT evidence of pleural fluid, masses or thickening; 11 male and 3 female, mean age 58 years. Study dates not given.
• Exposure: Asbestos exposure was not assessed. The article does not report the patients' exposure histories. The study evaluated a diagnostic test, 18-FDG PET imaging.
• Main results:
  • Histology showed malignant mesothelioma in ten patients (eight epithelial, one mixoid, one sarcomatous), adenocarcinoma in two, liposarcoma in one and benign pleural fibrosis in one
  • PET identified malignant disease in 12 of the 13 patients with cancer. There was one false-negative, in a patient with epithelial mesothelioma.
  • Benign disease was correctly assessed in the patient with pleural fibrosis. The authors reported a sensitivity of 92% and an accuracy of 92% for all 14 patients.
  • PET showed distant metastases in two patients: adrenal metastases in a patient with sarcomatous mesothelioma, and metastases to lymph nodes, lung and ribs in a patient with pulmonary adenocarcinoma
  • Of six mesothelioma patients scanned before and after chemotherapy, two were excluded because their uptake after pleurectomy and intrapleural bleomycin was interpreted as related to that treatment
  • In the remaining four patients, mean SUV (based on maximum values) fell from 7.2 before chemotherapy to 2.5 after, while their CT scans remained substantially stable
• The authors' conclusion: The authors concluded that PET results were encouraging, for both diagnosis and judging response to treatment. They found that tissue diagnosis by CT-guided biopsy or thoracoscopy was still needed before planning treatment, and that larger studies were required.
• Limitations the authors state:
  • PET could not distinguish pleural tumors from spread of other cancers to the pleura, such as adenocarcinoma
  • Tumors with low uptake, such as epithelial mesothelioma, were difficult to tell apart from benign lesions
  • Increased uptake seen 1 to 3 months after pleurectomy and intrapleural bleomycin was interpreted as treatment-related. The authors said a 2-month wait after treatment would not be enough to tell this apart from recurrence.
  • The treatment-response findings came from very few patients. The authors called for longer follow-up and larger groups.

Topics

Medical terms in this study, explained in our Lexicon: CT Scan, Neoplasm, Thoracoscopy, Pleural Mesothelioma, Lung Cancer, Pleural Thickening, Chemotherapy, Histology.

Related studies

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• Clinical value of fluorodeoxyglucose-positron emission tomography/computed tomography in differentiation of malignant mesothelioma from asbestos-related benign pleural disease: an observational pilot study — H. Yildirim, M. Metintas, et al. (2009)
• Positron emission tomography in the diagnosis of mesothelioma — U. Haberkorn (2004)
• Good vibrations and the power of positron thinking: positron emission tomography and endoscopic ultrasound in staging of mesothelioma-two case reports — C.P. Carden, J.S. Myerson, et al. (2008)
• Integrated positron emission tomography-computed tomography does not accurately stage intrathoracic disease of patients undergoing trimodality therapy for malignant pleural mesothelioma — J. Pilling, J.A. Dartnell, et al. (2010)
• Contribution of positron emission tomography in pleural disease — B. Duysinx, J.L. Corhay, et al. (2010)

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