Rapid Contour-based Segmentation for 18F-FDG PET Imaging of Lung Tumors by Using ITK-SNAP: Comparison to Expert-based Segmentation.

Purpose To assess the performance of the ITK-SNAP software for fluorodeoxyglucose (FDG) positron emission tomography (PET) segmentation of complex-shaped lung tumors compared with an optimized, expert-based manual reference standard. Materials and Methods Seventy-six FDG PET images of thoracic lesions were retrospectively segmented by using ITK-SNAP software. Each tumor was manually segmented by six raters to generate an optimized reference standard by using the simultaneous truth and performance level estimate algorithm. Four raters segmented 76 FDG PET images of lung tumors twice by using ITK-SNAP active contour algorithm. Accuracy of ITK-SNAP procedure was assessed by using Dice coefficient and Hausdorff metric. Interrater and intrarater reliability were estimated by using intraclass correlation coefficients of output volumes. Finally, the ITK-SNAP procedure was compared with currently recommended PET tumor delineation methods on the basis of thresholding at 41% volume of interest (VOI; VOI41) and 50% VOI (VOI50) of the tumor's maximal metabolism intensity. Results Accuracy estimates for the ITK-SNAP procedure indicated a Dice coefficient of 0.83 (95% confidence interval: 0.77, 0.89) and a Hausdorff distance of 12.6 mm (95% confidence interval: 9.82, 15.32). Interrater reliability was an intraclass correlation coefficient of 0.94 (95% confidence interval: 0.91, 0.96). The intrarater reliabilities were intraclass correlation coefficients above 0.97. Finally, VOI41 and VOI50 accuracy metrics were as follows: Dice coefficient, 0.48 (95% confidence interval: 0.44, 0.51) and 0.34 (95% confidence interval: 0.30, 0.38), respectively, and Hausdorff distance, 25.6 mm (95% confidence interval: 21.7, 31.4) and 31.3 mm (95% confidence interval: 26.8, 38.4), respectively. Conclusion ITK-SNAP is accurate and reliable for active-contour-based segmentation of heterogeneous thoracic PET tumors. ITK-SNAP surpassed the recommended PET methods compared with ground truth manual segmentation.

F-18 FDG-PET/CT in aseptic abscesses with recurrent febrile abdominal pain.

OBJECTIVE: Mendelian and complex autoinflammatory disorders frequently manifest as recurrent abdominal pain and fever. Diagnosis may be difficult and scant data are available about the interest of 2-deoxy-2-[18F]fluoro-D-glucose-positron emission tomography/computed tomography (FDG-PET/CT) in such conditions, particularly aseptic abscesses (AA). MATERIAL AND METHODS: We analyzed five cases of AA in which FDG-PET/CT was performed at diagnosis (n = 2) and after a suspected relapse (n = 5). Follow-up FDG-PET/CT was performed in two patients 9 days and 6 weeks after the initiation of oral corticosteroids. RESULTS: FDG-PET/CT showed intense uptake foci in the abdominal lymph nodes (n = 4), liver (n = 2) and spleen (n = 4) before treatment. A marked metabolic response was observed while patients were being treated. In a relapsing patient with abdominal pain but no raised CRP, although CT scan was unchanged, abnormal uptake of FDG was observed. By contrast, some lesions previously observed on CT scan displayed no fixation on new FDG-PET/CT and were suggestive of sequelae in three patients. CONCLUSION: Although nonspecific, FDG-PET/CT may be an interesting tool for the diagnosis and management of recurrent and febrile abdominal pain in AA. At the time of relapse, it can differentiate between a sequela of previous flares and a new localization. It can be used for whole-body screening to look for other asymptomatic disease localizations.

PET/CT and MRI Imaging of a Eumycetoma of the Right Thigh.

Eumycetoma is a chronic tropical fungal disease that infiltrates subcutaneous tissues, mainly in the feet and legs. Standard antifungal drugs are ineffective, and mutilating surgery is common. Morphological imaging is useful for assessing the local extent of the disease before surgery. FDG PET/CT may be of potential interest for the general extent, but PET descriptions remain scarce and mostly relate to the feet. Here, the authors present FDG PET/CT and MRI study of a very rare case of an extensive, biopsy-proven eumycetoma of the right thigh that was performed to guide potential surgery.

Is (18)F-fluorodeoxyglucose positron emission tomography scanning a reliable way to assess disease activity in Takayasu arteritis?

OBJECTIVE: (18)F-fluorodeoxyglucose-positron emission tomography (FDG-PET) scanning has been proposed as a new way of assessing disease activity in Takayasu arteritis (TA), but previous studies have used the nonvalidated National Institutes of Health (NIH) global activity criteria, and thus might be biased. This study was undertaken to determine the value of PET scanning for assessment of disease activity in TA, by comparing PET scan data with clinical, biologic, and magnetic resonance imaging (MRI) data assessed separately. METHODS: Twenty-eight patients with TA (according to the American College of Rheumatology criteria) underwent a total of 40 PET scans. Images were reviewed by 2 pairs of independent nuclear medicine physicians and assessed for pattern and intensity of vascular uptake. TA activity data were obtained within 15 days of the PET scans. RESULTS: PET scanning revealed abnormal vascular uptake in 47% of the 40 examinations. The uptake intensity grade was 0 in 7 scans, grade 1 in 7 scans, grade 2 in 13 scans, and grade 3 in 13 scans. Morphologic analysis was conducted by grading the pattern of the vascular uptake as diffuse (73%), segmental (20%), or focal (13%). There was a trend toward an association between clinically active disease and the semiquantitative assessment of FDG uptake (P = 0.08). We found no statistical association between levels of acute-phase reactants and intensity of uptake. There was no significant association between the semiquantitative assessment of FDG uptake and the presence of vascular wall thickening (P = 0.23), gadolinium uptake (P = 0.73), or the presence of vascular wall edema (P = 0.56). CONCLUSION: Our findings indicate that there is no association between FDG vascular uptake intensity and clinical, biologic, or MRI assessment of disease activity. Previous studies using the nonvalidated NIH global activity criteria are likely biased.