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Background:To evaluate the advantages of contrast enhanced F-18-fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-contrast enhanced CT [CECT]) when used as an initial imaging modality in patients presenting with metastatic malignancy of undefined primary origin (MUO).Materials and Methods:A total of 243 patients with fine needle aspiration cytology/biopsy proven MUO were included in this prospective study. Patients who were thoroughly evaluated for primary or primary tumor was detected by any other investigation were excluded from the analysis. Totally, 163 patients with pathological diagnosis of malignancy but no apparent sites of the primary tumor were finally selected for analysis. The site of probable primary malignancy suggested by PET-CECT was confirmed by biopsy/follow-up.Results:PET-CECT suggested probable site of primary in 128/163 (78.52%) patients. In 30/35 remaining patients, primary tumor was not detected even after extensive work-up. In 5 patients, where PET-CECT was negative, primary was found on further extensive investigations or follow-up. The sensitivity, specificity, positive predictive value and negative predictive value of the study were 95.76%, 66.67%, 88.28% and 85.71% respectively.Conclusions:F-18 FDG PET-CECT aptly serves the purpose of initial imaging modality owing to high sensitivity, negative and positive predictive value. PET-CECT not only surveys the whole body for the primary malignancy but also stages the disease accurately. Use of contrast improves the diagnostic utility of modality as well as help in staging of the primary tumor. Although benefits of using PET-CECT as initial diagnostic modality are obvious from this study, there is a need for a larger study comparing conventional methods for diagnosing primary in patients with MUO versus PET-CECT.

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Background: Accumulated evidence indicates that exposure to trauma is associated with the development of cognitive impairments and psychiatric symptoms in children and adolescents. Objective: In this case study of a female adolescent of 17 years, we aimed to evaluate how cortical positron emission tomography (PET) abnormalities relate to psychogenic non-epileptic seizure (PNES) dissociative state, post-traumatic stress disorder (PTSD), attention-deficit/hyperactivity disorder (ADHD), and domestic violence exposure. Methods: Detailed psychiatric and neuropsychological assessment was performed initially, followed by a PET study. The PET imaging was carried out in the resting-state and in the dissociative-state. Results: The adolescent was suffering from multiple episodes of unconsciousness, all found to be psychogenic; thus, PNES was diagnosed. However, at the psychopathology symptom level, the adolescent had heightened impulsivity, hyperactivity, hyperarousal, anxiety, somatic, and dissociative/ functional neurological symptoms present separately or concurrently at some point during her life; thus, the criteria for PTSD and ADHD were also fulfilled. In the resting state, significant hypometabolism was observed in the occipital, occipitotemporal, polar, and mesial parts of the temporal regions bilaterally, fronto-parietal medial and lateral pericental regions, and fronto-temporal and insular region on the left. The most intense metabolism was observed in the posterior cingulate gyrus and the medial parts of the posterior parietal lobe. In the dissociative state, there was a slight increase in the metabolism of the brain globally compared with the resting state, but with identical distribution of the regional changes observed. Conclusions: Widespread cortical PET abnormalities were found, possibly indicating alterations in large-scale brain networks, in a patient with PNES and a dissociative state, PTSD, and ADHD, who was exposed to chronic domestic violence