To compare the interobserver agreement and degree of confidence in anatomical localisation of lesions using 2-[fluorine-18]fluoro-2-deoxy-
D
-glucose (
18
F-FDG) positron emission tomography (PET)/computed tomography (CT) and
18
F-FDG PET alone in patients with head and neck tumours. A prospective study of 24 patients (16 male, eight female, median age 59 years) with head and neck tumours was undertaken.
18
F-FDG PET/CT was performed for staging purposes. 2D images were acquired over the head and neck area using a GE Discovery LS™ PET/CT scanner.
18
F-FDG PET images were interpreted by three independent observers. The observers were asked to localise abnormal
18
F-FDG activity to an anatomical territory and score the degree of confidence in localisation on a scale from 1 to 3 (1=exact region unknown; 2=probable; 3=definite). For all
18
F-FDG-avid lesions, standardised uptake values (SUVs) were also calculated. After 3 weeks, the same exercise was carried out using
18
F-FDG PET/CT images, where CT and fused volume data were made available to observers. The degree of interobserver agreement was measured in both instances. A total of six primary lesions with abnormal
18
F-FDG uptake (SUV range 7.2–22) were identified on
18
F-FDG PET alone and on
18
F-FDG PET/CT. In all, 15 nonprimary tumour sites were identified with
18
F-FDG PET only (SUV range 4.5–11.7), while 17 were identified on
18
F-FDG PET/CT. Using
18
F-FDG PET only, correct localisation was documented in three of six primary lesions, while
18
F-FDG PET/CT correctly identified all primary sites. In nonprimary tumour sites,
18
F-FDG PET/CT improved the degree of confidence in anatomical localisation by 51%. Interobserver agreement in assigning primary and nonprimary lesions to anatomical territories was moderate using
18
F-FDG PET alone (kappa coefficients of 0.45 and 0.54, respectively), but almost perfect with
18
F-FDG PET/CT (kappa coefficients of 0.90 and 0.93, respectively). We conclude that
18
F-FDG PET/CT significantly increases interobserver agreement and confidence in disease localisation of
18
F-FDG-avid lesions in patients with head and neck cancers.
Complete staging is mandatory for the management and therapy of neuroendocrine tumours. Various radiotracers are available but the best imaging strategy has yet to be defined. In this study we retrospectively compared 123I-MIBG, 111In-[D-Phe1]-DTPA-octreotide and 18F-FDG (PET) imaging in 15 patients with metastatic neuroendocrine tumours (11 carcinoid tumours, 4 paragangliomas). Planar images were acquired 1, 4, 24 and 48 h following the injection of 111In-[D-Phe1]-DTPA-octreotide and 123I-MIBG. Whole-body PET scans were performed 45 min after injection of 18F-FDG. 111In-[D-Phe1]-DTPA-octreotide was positive in 11/15 patients and identified 44 lesions, 18F-FDG PET was positive in 11/15 patients and identified 107 lesions and 123I-MIBG was positive in 8/15 patients and identified 67 lesions. No single scintigraphic technique identified all metastatic sites. In one patient all studies were negative. 18F-FDG PET identified more abnormal sites than the other two modalities. Combination of all three imaging modalities with X-ray CT helps to provide a more comprehensive map of the disease.
Quetiapine treatment results in significant in vivo blockade of cortical 5-HT2A, similar to other atypical antipsychotic drugs. This effect may contribute to its placebo level extrapyramidal side-effect profile.
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