Anne Hitzel

A false-positive finding in therapeutic evaluation: hypermetabolic axillary lymph node in a lymphoma patient following FDG extravasation

We report a case of a false-positive finding in FDG PET/CT following radiotracer extravasation. A 15-year-old male patient was referred for therapeutic evaluation status post-chemotherapy for a lymphoblastic lymphoma. FDG PET/CT showed discordant findings with a marked decrease in a liver/hepatic hilum uptake, disappearance of a subcutaneous left supraclavicular uptake, and appearance of intense right axillary nodal uptake. Extravasation in the right superior limb was noted. Comparison with the previous scan showed that the axillary nodes were present, measured less than 1 cm in their short axis, had not increased in size, and had a fatty hilum. We concluded that FDG uptake was caused by a migration in lymphatic vessels.

What is the role of 18F-FDG uptake intensity in suspected atrial myxoma exploration?

Atrial myxomas are the most common primary cardiac tumors in adults. Although they are benign tumors, they can lead to symptoms as left-sided heart failure, systemic embolism or arrhythmia. Because of their slow natural history and their benign pattern, they are theoritically considered as not uptaking 18F-FDG. However, few reports suggest that atrial myxomas can express moderate 18F-FDG uptake with maximum standardized uptake value (SUVmax) ranging from 3 to 5.3. Thereby, recent integrated 18F-FDG PET/MR imaging considered that a threshold of 5.2 or greater for SUVmax yield 100% sensitivity for the differentiation between malignant and nonmalignant tumors. The panel A of the enclosed image show a hypermetabolic area in the right atrium with a SUVmax of 5.1 corresponding to an iso-echogenic mass by transthoracic echocardiography (panel B) and hypodense mass by computed tomography (panel C). Coronary angiography showed a strong vascularization of the mass, which was confirmed as myxoma after surgical extraction and pathologic exploration (Figure 1). We can suppose that, in this case, the intense FFDG uptake by the tumor is the consequence of the strong neovascularization. This finding encourages to not exclude the diagnosis of atrial myxoma on the basis of PET results alone and to integrate multimodality cardiac imaging approach for the exploration of cardiac tumors.

Value of PET/CT 3D visualization of head and neck squamous cell carcinoma extended to mandible

PURPOSE To study an original 3D visualization of head and neck squamous cell carcinoma extending to the mandible by using [18F]-NaF PET/CT and [18F]-FDG PET/CT imaging along with a new innovative FDG and NaF image analysis using dedicated software. The main interest of the 3D evaluation is to have a better visualization of bone extension in such cancers and that could also avoid unsatisfying surgical treatment later on. PATIENTS AND METHODS A prospective study was carried out from November 2016 to September 2017. Twenty patients with head and neck squamous cell carcinoma extending to the mandible (stage 4 in the UICC classification) underwent [18F]-NaF and [18F]-FDG PET/CT. We compared the delineation of 3D quantification obtained with [18F]-NaF and [18F]-FDG PET/CT. In order to carry out this comparison, a method of visualisation and quantification of PET images was developed. This new approach was based on a process of quantification of radioactive activity within the mandibular bone that objectively defined the significant limits of this activity on PET images and on a 3D visualization. Furthermore, the spatial limits obtained by analysis of the PET/CT 3D images were compared to those obtained by histopathological examination of mandibular resection which confirmed intraosseous extension to the mandible. RESULTS The [18F]-NaF PET/CT imaging confirmed the mandibular extension in 85% of cases and was not shown in [18F]-FDG PET/CT imaging. The [18F]-NaF PET/CT was significantly more accurate than [18F]-FDG PET/CT in 3D assessment of intraosseous extension of head and neck squamous cell carcinoma. This new 3D information shows the importance in the imaging approach of cancers. All cases of mandibular extension suspected on [18F]-NaF PET/CT imaging were confirmed based on histopathological results as a reference. CONCLUSIONS The [18F]-NaF PET/CT 3D visualization should be included in the pre-treatment workups of head and neck cancers. With the use of a dedicated software which enables objective delineation of radioactive activity within the bone, it gives a very encouraging results. The [18F]-FDG PET/CT appears insufficient to confirm mandibular extension. This new 3D simulation management is expected to avoid under treatment of patients with intraosseous mandibular extension of head and neck cancers. However, there is also a need for a further study that will compare the interest of PET/CT and PET/MRI in this indication.

Can positron emission tomography be useful to manage systemic sclerosis cardiac involvement

a Department of Pneumology, University Hospital of Larrey, Toulouse, France b Department of Nuclear Medicine, Toulouse University Hospital, Toulouse, France c Cardiac Imaging Center, Toulouse University Hospital, Toulouse, France d Medical School of Rangueil, University Paul Sabatier, Toulouse, France e Medical School of Purpan, University Paul Sabatier, Toulouse, France f Department of Internal Medicine, University Hospital of Purpan, Toulouse, France g Department of Internal Medicine, Toulouse University Hospital, Toulouse Cedex 9, France