Computed Tomography has been widely used as the primary imaging modality for the diagnosis, staging, and monitoring of therapeutic response in MM. More recently, MRI and PET imaging with FDG have gained popularity for imaging MM because of the excellent resolution and superiority in the differentiation of malignant from benign disease. A prospective study comprising 32 patients, 19 with malignant and 13 with benign disease, found that FDG PET had a high negative predictive value of 92%. FDG PET imaging showed an Monensin sodium salt absence of FDG uptake, and correctly classified 31/35 benign lesions. Nevertheless, the usefulness of FDG is limited by its uptake in inflammatory cells such as macrophages and activated lymphocytes, which can cause false-positive results as seen in cases of parapneumonic effusion, tuberculous and uraemic pleural disease. In spite of recent advances in the diagnosis of MM, therapeutic outcomes have not greatly improved. Surgical resection and adjuvant radiation therapy remain the mainstay of treatment for patients with resectable MM. Occupational exposure to asbestos remains the major risk factor for MM. This exposure has been demonstrated to be associated with increased HER1 activation and expression. Therefore, HER1-targeted imaging can play a complimentary role in a better understanding of asbestos-induced mesothelioma. While traditional targeting of HER1 for therapy has not been successful, it is feasible that HER1 binding molecules could be used as vectors to effectively deliver imageable or cytotoxic radioactive payloads differentially to MM cells to potentially improve diagnostic as well as therapeutic outcomes. Towards this end, the in vivo targeting characteristics of two HER1-binding monoclonal antibodies, cetuximab and panitumumab, each labeled with 86Y, were comparatively evaluated as potential diagnostics by PET imaging, and to select a potential candidate for evaluation in monoclonal antibody targeted RIT applications. In vitro HER1 expression was observed in four MM cell lines evaluated similar to the clinical findings of HER1 over-expression in majority of MM. HER1- specific tumor targeting was observed in all three xenograft tumor models evaluated supporting the hypothesis that HER1 targeting can be used for imaging and SB 200646 hydrochloride radionuclide therapy of MM.