Amyloid imaging with (11)C-PIB PET/CT and glucose metabolism with (18)F-FDG PET/CT in a study on cognitive impairment in the clinical setting.

OBJECTIVE: The objective of this study was to evaluate the contribution of amyloid imaging with (11)C-Pittsburgh compound B ((11)C-PIB) and of glucose metabolism on F-fluorodeoxyglucose ((18)F-FDG) PET/CT to the study of cognitive impairment in the clinical setting. PATIENTS AND METHODS: Thirty-four patients (15 male, 19 female) were enrolled in the study. They were classified according to their clinically presented symptoms. Six patients had subjective memory complaints, five had nonamnestic mild cognitive impairment (MCI), seven had amnestic MCI, seven had prodromal Alzheimer's disease (AD), five had frontotemporal dementia, two had dementia with Lewy bodies, and two had cortical degeneration. All the scans were conducted to determine the likelihood of AD or to differentiate between AD and other dementia. Static 30-min (11)C-PIB and 15-min (18)F-FDG PET/CT scans were obtained. A visual analysis of images was performed. RESULTS: Three of the six patients with subjective memory complaints had positive (11)C-PIB scans and one of them also had (18)F-FDG hypometabolism. All five nonamnestic MCI patients had normal (11)C-PIB and (18)F-FDG. Four of the seven amnestic MCI patients showed (11)C-PIB cortical retention but only one had positive (18)F-FDG. Positive (11)C-PIB and (18)F-FDG were detected in five of the seven prodromal AD patients. All the five patients with FDT had positive (18)F-FDG scans, but only one of the five had (11)C-PIB cortical retention. Both dementia with Lewy bodies and cortical degeneration patients had positive (11)C-PIB and (18)F-FDG scans. CONCLUSION: The combined use of (11)C-PIB and (18)F-FDG PET provides relevant information for the clinical management of cognitive impairment. The detection of positive (11)C-PIB cortical retention in patients may be an indicator of the need for further clinical assessment and monitoring.

Aortic 18F-FDG PET/CT uptake pattern at 60 min (early) and 180 min (delayed) acquisition in a control population: a visual and semiquantitative comparative analysis.

18F-Fluoro-2-deoxy-D-glucose (F-FDG) PET/CT acquisition is generally performed 60 min after injection. The normal biodistribution pattern of F-FDG includes activity in the aortic territory due to blood pool activity, which could interfere in the diagnosis of aortic diseases by overlapping the wall uptake. The aim of the study was to evaluate the change over time of F-FDG uptake by the aortic wall and the activity in the lumen in a control population and to establish normal reference values. This prospective study included 15 control patients (mean age: 58.2 years). PET/CT was acquired 60 min (early scan) and 180 min (delayed scan) after an F-FDG injection at a dose of 7 MBq/kg. A visual and semiquantitative analysis of the F-FDG aortic wall uptake was carried out, and lumen activity and the aortic wall to lumen ratio [target-to-background ratio (TBR)] were determined. In the visual analysis all patients showed F-FDG activity at the aortic territory at 60 and 180 min. The pattern of uptake at 60 min was diffuse in all 15 patients (100%), without delineation of the aortic wall uptake; however, at 180 min the uptake pattern of the aortic wall changed to lineal in 14 patients (93.3%). The aortic wall maximum standardized uptake value decreased from 2.07±0.34 to 1.7±0.46 during the delayed acquisition (P=0.0279) and the lumen maximum standardized uptake value decreased highly significantly (1.99±0.35 vs. 1.36±0.32, P=0.0001). Therefore, TBR also increased highly significantly from 1.04±0.06 to 1.25±0.16 (P<0.0001). The high decrease in blood pool activity from 60 to 180 min provides a better delineation of the aortic wall uptake, which corresponds to the normal pattern at that time. The TBR increased significantly at 180 min, and 1.25±0.16 is suggested as the threshold for diagnostic purposes, especially for the diagnosis of vasculitis.

Diagnosis of recurrence and assessment of post-recurrence survival in patients with extracranial non-small cell lung cancer evaluated by 18F-FDG PET/CT.

UNLABELLED: The accurate diagnosis of recurrence of non small cell lung cancer (NSCLC) is crucial for the appropriate management of patients with suspicion of recurrence (SOR). We evaluated prospectively in the clinical setting the contribution of FDG PET/CT in patients with SOR of NSCLC in terms of sensitivity, specificity, impact on therapy and on survival. METHODS: Of the 55 patients included in the study, recurrence was confirmed in 37 but, follow up data for survival evaluation was available in 34. There were 59 SOR in the 55 patients and in 41 recurrence was confirmed. 53 of the 59 suspicions, had a contrast enhanced CT. All patients had a FDG PET/CT scan after iv injection of 8 MBq/kg of F18-FDG. RESULTS: Of the 59 SOR, FDG PET/CT was positive in all 41 in which recurrence was confirmed (100% sensitivity) and, it was negative in 15 of the 18 in which it was ruled out (specificity 83%). In 27 SOR with inconclusive CT, FDG PET/CT showed 100% sensitivity (18/18) and 78% specificity (7/9). FDG PET/CT had an impact on treatment in 42 of the 59 SOR. In all 34 patients, FDG PET/CT diagnosed recurrence and overall survival at 20 months and 5 years was 44% and 11%, respectively. When the extent of recurrence assessed by FDG PET/CT was considered, survival at 20 months and at 5 years of patients with loco-regional recurrence was 77% and 28% and in patients with distant recurrence 14% and 0% (p < 0.001). CONCLUSION: Despite the small number of patients, our study demonstrates that FDG PET/CT is highly accurate for the detection of NSCLC recurrence. Therefore it has a great impact on the therapy regimen and on survival depending on the extent of the recurrent disease, survival being better for patients with local recurrence. By differentiating local from distant recurrence, it allows the selection of patients who, could potentially benefit from new therapies. The results also suggest that there are grounds to include FDG PET/CT in the guidelines for surveillance for NSCLC.