Joint Program in Nuclear Medicine

PET Imaging of Pleural Mesothelioma

Hossein Jadvar, MD, PhD
Alan J. Fischman, MD, PhD

March 16, 1999

Presentation

A 67 year old male presented with cough and dyspnea. A chest radiograph (not showm) revealed moderately large left pleural effusion. A chest MRI (not shown) was also performed that showed contrast enhancement of the left pleura. FDG PET imaging and thoracoscopy were then performed.

Imaging Technique

Coronal FDG PET: Attenuation-corrected imaging 45 minutes after intravenous injection of 17 mCi FDG.

Imaging Findings

The series of coronal PET images, from anterior (top left) to posterior (bottom right), show asymmetric abnormal hypermetabolism surrounding the left hemithorax highly suspicious for malignancy.

Differential Diagnosis

The differential diagnosis for pleural disease is as follows:
  1. Pleuritis
    1. Serofibrinous (TB, pneumonia, infarct, rheumatoid arthritis, uremia)
    2. Suppurative (empyema)
    3. Hemorrhagic (bleeding dyscrasia, neoplasm)
  2. Neoplasm
    1. Metastatic (lung cancer, breast cancer, ovarian cancer)
    2. Primary (benign and malignant mesothelioma)

Diagnosis

The patient underwent thoracoscopy with pleural biopsy followed by left extrapleural pneumonectomy. Both the biopsy and the surgical specimen demonstrated extensive malignant mesothelioma involving both parietal and visceral pleura.

Discussion

Malignant mesothelioma is an uncommon tumor of mesothelial cells in the pleura or peritoneum. It is associated with previous occupational exposure to asbestos in 90% of cases with a lifetime risk of approximately 10% in heavily exposed individuals at a long latent period of 25-45 years. Pleural mesotheliomas spread diffusely over the lung surface, may invade the pulmonary parenchyma, and can metastasize. Prognosis is very poor and mean survival is usually less than two years after the initial diagnosis (1). Diagnosis is difficult with CT, which often cannot differentiate between benign pleural thickening and malignant mesothelioma. Thoracentesis and CT-guided biopsy are invasive and may be inconclusive. Benard et al. evaluated the use of FDG PET in the evaluation of malignant mesothelioma in 28 patients (2). They determined that a specific uptake value (SUV) cutoff of 2.0 differentiates between malignant and benign pleural disease with a sensitivity of 91% and a specificity of 100% . In another study by the same group, the level of metabolic activity (SUV > 3.5) was correlated inversely with survival (3). Lowe et al. found a SUV cutoff of 2.5 to be useful in separating benign from malignant pleural abnormality (4). However, two patients with active infectious pleuritis also demonstrated increased FDG uptake. Bury et al. reported similar findings for the value of PET in assessing patients with pleural disease (5).

References

1. Robins SL, Cotran RS, Kumar V. Pathologic basis of disease. WB Saunders Co.; 1991.

2. Benard F, Sterman D, Smith RJ, et al. Metabolic imaging of malignant pleural mesothelioma with fluorodeoxyglucose positron emission tomography. Chest 1998; 114(3): 713-722.

3. Benard F, Alavi A, Sterman D, et al. The prognostic value of FDG-PET imaging in malignant pleural mesothelioma. J Nucl Med 1998; 39(5): 81P. (Abstr.)

4. Lowe VJ, Patz E, Harris L, et al. FDG-PET evaluation of pleural abnormalities. J Nucl Med 1994; 35: 228P. (Abstr.)

5. Bury T, Paulus P, Weber T, et al. Evaluation of pleural diseases by FDG-PET imaging: preliminary report. Eur J Nucl Med 1996; 23: 1186.

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J. Anthony Parker, MD PhD, Tony_Parker@CareGroup.harvard.edu