Maria Lucia Calcagni

We report an unusual case of malignant pseudothyroiditis (MPT) occurred in a 35-year-old female patient presenting with symptoms and signs of thyroiditis. Fine-needle aspiration biopsy of the thyroid demonstrated the presence of a MPT induced by a metastatic extrathyroidal carcinoma. F-FDG-PET/CT showed increased radiopharmaceutical uptake in the thyroid, in multiple cervical and mediastinal lymph nodes, and in a right pulmonary nodule. Histological examination demonstrated the presence of a metastatic non-small cell lung cancer (NSCLC). In this unusual case of MPT F-FDG-PET/CT has been useful in staging the disease and in detecting the primary tumor site

Purpose To evaluate whether standardized uptake value (SUV) and/or metabolic rate of glucose (MRglu) are different among epithelioid, mixed, and spindle cell uveal melanomas, as well as between low and high risk melanomas; to correlate ultrasonographic data and metabolic parameters with histopathological features; and to assess the role of ¹⁸F-FDG PET/CT for evaluating prognosis. Methods Of 34 eligible patients prospectively enrolled with clinical suspicion of medium/large uveal melanoma, 26 (15 men, mean age 62.8 ± 11.8 years) were evaluated. All patients underwent metastatic work-up, 3-D dynamic brain and whole-body ¹⁸F-FDG PET/CT, and surgery. Results Of the 26 ocular lesions, 23 showed ¹⁸F-FDG uptake, with a sensitivity of 88 %. MRglu was significantly higher in the epithelioid cell melanomas than in the spindle cell melanomas, as well as in high-risk lesions than in low-risk lesions (p = 0.01, p = 0.02, respectively). SUV and MRglu were correlated with histopathological features while ultrasonographic data were not. Conclusion MRglu is useful for distinguishing the different cell types in uveal melanoma, as well as high-risk from low-risk lesions, while SUV is not. MRglu provides a more accurate evaluation of glucose consumption, whereas SUV provides only an estimation. In addition, the metabolic parameters correlate with histopathological features, well also reflecting cellular behaviour in ocular malignancy. A longer follow-up is needed to assess the role of ¹⁸F-FDG in evaluating prognosis.

PURPOSE:\ud We prospectively evaluated the regional cerebral metabolic rate of glucose (CMRglu) before and after ventricular shunt placement in idiopathic normal-pressure hydrocephalus (iNPH) patients, to investigate whether some brain regions are more involved than others; we also correlated the individual variations of CMRglu with the clinical scale score assessment after shunting.\ud METHODS:\ud Twenty iNPH patients (12 men; mean age 73 ± 9 years) underwent clinical scale score assessment and F-FDG PET-CT before and 1 week after shunting.\ud RESULTS:\ud Before shunting, CMRglu values were similar in right and left brain regions, as well as after shunting. After shunting, 17 of 20 iNPH patients were clinically improved; all scale scores decreased, and CMRglu significantly increased in all regions (P < 10). In 3 of 20 iNPH patients, the symptoms persisted, the scale scores did not change, and CMRglu increased only in 3 regions: left frontal, left putamen, and right thalamus. Before shunting, no difference in global CMRglu between clinically improved (n = 17) and not improved (n = 3) iNPH patients was found. After shunting, a significant (P = 0.01) correlation between individual variations of CMRglu and clinical assessment was found.\ud CONCLUSIONS:\ud These findings confirm that iNPH is a disease involving all cerebral regions almost in the same way, and shunt procedure has a similar effect on regional cerebral metabolism almost in the same way. Individual variations of CMRglu are more important than absolute values and correlate with clinical status after shunting. Clinical improvement depends not only on the capability to restore the cerebrospinal fluid dynamic, but also on the ability of cerebral parenchyma to recover the metabolic function

Background: To evaluate the metabolic changes on ¹⁸ F-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 ¹⁸ F-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 (p18 F-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.

18F-fluoro-deoxy-glucose (18 F-FDG) positron emission tomography integrated/combined with computed tomography (PET-CT) provides the best diagnostic results in the metabolic characterization of undetermined solid pulmonary nodules. The diagnostic performance of 18 F-FDG is similar for nodules measuring at least 1 cm and for larger masses, but few data exist for nodules smaller than 1 cm.

A 64-year-old man was referred to our center for metabolic characterization of 2 bilateral pulmonary lesions, incidentally detected at computed tomography (CT). 18F-FDG PET/CT scan showed a weak radiopharmaceutical uptake in both pulmonary lesions. A subsequent 68Ga-DOTANOC PET/CT showed intense radiopharmaceutical uptake in both pulmonary lesions. Subsequently, the patient underwent histopathological examinations of both lesions, which showed a synchronous well-differentiated pulmonary neuroendocrine carcinoma (typical carcinoid tumor). This case reports a rare occurrence of synchronous pulmonary carcinoid, highlighting the role of different PET tracers for metabolic characterization of pulmonary nodules.

We evaluated the relationships between the cerebral metabolic rate of glucose (CMRglu) measured by dynamic ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) and the clinical and neuropsychological assessment before and after the surgical procedure in idiopathic normal pressure hydrocephalus (INPH) patients.

Purpose: (1) To investigate the diagnostic value of some O-(2-[¹⁸F]fluoroethyl)-L-tyrosine (F-18 FET) indices derived from the dynamic acquisition to differentiate low-grade gliomas from high-grade; (2) to analyze the course of tumor time-activity curves (TACs); and (3) to calculate the individual probability of a high-grade glioma using the logistic regression. Methods: Seventeen low-grade (WHO I–II) and 15 high-grade (WHO III–IV) gliomas were studied with dynamic F-18 FET PET. Regions of interests were drawn over the tumor and contralateral brain, and TACs were analyzed. We considered early standardized uptake value (SUV), middle SUV, late SUV, early-to-middle SUV tumor ratio, early-to-late SUV tumor ratio; time to peak (Tpeak), in minutes, from the beginning of the dynamic acquisition up to the maximum SUV of the tumor; and SoD (sum of the frame-to-frame differences). To assess the individual probability of high-grade, logistic regression was also used. Results: High-grade gliomas showed significantly (P < 0.0001) higher values when compared with low-grade gliomas in early SUV, early-to-middle ratio, early-to-late ratio, Tpeak, and SoD. For the grading of gliomas, the best indices were early-to-middle ratio and Tpeak providing a diagnostic accuracy of 94%. TACs analysis provided an 87% diagnostic accuracy. For individual high-grade diagnosis, the logistic regression provided 93% sensitivity, 100% specificity, and 97% accuracy. Conclusion: Early-to-middle SUV tumor ratio and Tpeak were the best indices for assessing the grading of gliomas. Since early-to-middle ratio derives from the first 35 minutes of the dynamic acquisition, the PET study could last half an hour instead of 1 hour. By logistic regression, it is possible to assess the individual probability of high-grade, useful for prognosis and treatment.