The role of nuclear medicine in the management of thymomas.

AIM OF THE STUDY: To evaluate the role of nuclear medicine techniques in the management of patients with thymoma. MATERIALS AND METHODS: The Authors performed a review of the literature about the usefulness of traditional nuclear medicine and positron emission tomography in patients with thymic tumours. RESULTS AND DISCUSSION: Nuclear medicine imaging can provide additional information in cases of thymoma such as in differential diagnosis between thymic tumours, staging and restaging. Thallium-201 (201Tl), 99mTc-sestamibi and 99mTc-tetrofosmin are useful tumour-imaging agent. Another radiopharmaceutical useful in the management of thymomas is 111In-pentetreotide, a somatostatin analogue, used to define the receptor status and the extent of disease in malignant thymomas. Positron emission tomography (PET) is a powerful diagnostic tool for diagnosis, staging and restaging of neoplasms in general. The most used PET radiopharmaceutical is the fluorodeoxyglucose (18F-FDG), a glucose analogue. The uptake of FDG reflects the metabolic activity of organs and neoplasms and correlates with the tumour growth rate. There is a paucity of literature on the use of PET scanning in the diagnosis of thymoma. Further perspective studies with a larger number of cases, considering the development of hybrid imaging PET-CT and new PET radiopharmaceuticals, may increase the role of nuclear medicine in the diagnostic and therapeutic management of thymic neoplasms.

Malignant pleural mesothelioma: utility of 18 F-FDG PET.

Malignant Pleural Mesothelioma is a rare tumour that arise from the mesothelial cells of the pleura and in recent time the incidence of this disease is rising. Because of the implications for management and therapy, it is important to assess the accurate staging. 18F-fluorodeoxiglucose Positron Emission Tomography (18F-FDG PET) is become a useful tool in the diagnosis of many neoplasms, such as Malignant Pleural Mesothelioma. In particular it has been shown to be useful in the evaluation of the extent of pleural disease, in the establishment of lymph node involvement, in the evaluation of tumour invasion into the lung and thoracic wall, in the diagnosis of extrathoracic metastases, in the assessment of the response to treatment, and in planning radiotherapy. Developments in system technology, like improvements in hybrid system (integrated Positron Emission Tomography/Computed Tomography) and the discovery of new radiopharmaceuticals, promise to make PET much more useful and versatile in the future.

Role of myocardial gated SPECT scintigraphy in the clinical suspicion of ischemic cardiomyopathy: discussion of an unusual case.

The case of a 72-year-old patient affected by myasthenia gravis under pyridostigmine therapy, admitted to the hospital for the onset of oppressive thoracic pain associated with mild enzyme increase, electrocardiographic and echocardiographic disorders, is discussed. Dypiridamole/gated SPECT perfusion scintigraphy at rest evidenced reduced coronary reserve at the level of the lateral wall with apical akinesia and normokinesia of mediobasal left ventricle. On coronarography, coronary arteries were free of significant stenoses and left ventricular apical akinesia. The diagnostic approach to ischemic cardiomyopathy with the correct sequence of performed diagnostic imaging led to the presumptive identification of a rare syndrome.

¹8F-FDG PET-CT during chemo-radiotherapy in patients with non-small cell lung cancer: the early metabolic response correlates with the delivered radiation dose.

BACKGROUND: To evaluate the metabolic changes on ¹8F-fluoro-2-deoxyglucose positron emission tomography integrated with computed tomography (¹8 F-FDG PET-CT) performed before, during and after concurrent chemo-radiotherapy in patients with locally advanced non-small cell lung cancer (NSCLC); to correlate the metabolic response with the delivered radiation dose and with the clinical outcome. METHODS: Twenty-five NSCLC patients candidates for concurrent chemo-radiotherapy underwent ¹8F-FDG PET-CT before treatment (pre-RT PET-CT), during the third week (during-RT PET-CT) of chemo-radiotherapy, and 4 weeks from the end of chemo-radiotherapy (post-RT PET-CT). The parameters evaluated were: the maximum standardized uptake value (SUVmax) of the primary tumor, the SUVmax of the lymph nodes, and the Metabolic Tumor Volume (MTV). RESULTS: SUVmax of the tumor and MTV significantly (p=0.0001, p=0.002, respectively) decreased earlier during the third week of chemo-radiotherapy, with a further reduction 4 weeks from the end of treatment (p<0.0000, p<0.0002, respectively). SUVmax of lymph nodes showed a trend towards a reduction during chemo-radiotherapy (p=0.06) and decreased significantly (p=0.0006) at the end of treatment. There was a significant correlation (r=0.53, p=0.001) between SUVmax of the tumor measured at during-RT PET-CT and the total dose of radiotherapy reached at the moment of the scan. Disease progression free survival was significantly (p=0.01) longer in patients with complete metabolic response measured at post-RT PET-CT. CONCLUSIONS: In patients with locally advanced NSCLC, ¹8F-FDG PET-CT performed during and after treatment allows early metabolic modifications to be detected, and for this SUVmax is the more sensitive parameter. Further studies are needed to investigate the correlation between the metabolic modifications during therapy and the clinical outcome in order to optimize the therapeutic strategy. Since the metabolic activity during chemo-radiotherapy correlates with the cumulative dose of fractionated radiotherapy delivered at the moment of the scan, special attention should be paid to methodological aspects, such as the radiation dose reached at the time of PET.