Mitsumasa Kaji

The local efficacy of I-131 for F-18 FDG PET positive lesions in patients with recurrent or metastatic thyroid carcinomas.

Purpose: The aim of this study was to evaluate the local efficacy of I-131 for F-18 fluorodeoxyglucose positron emission tomography (FDG PET)-positive lesions. Methods: Whole-body FDG PET/CT was performed on 37 patients (55 cases: 16 men, 21 women; age range: 24–82 years; mean age ± standard deviation: 60.5 ± 16.0 years) with differentiated thyroid cancer after total thyroidectomy. The metastatic or recurrent lesions were divided into 5 categories: primary tumor bed, lymph node, lung, bone, and other. The well-defined lesions were measured on CT, and the sizes were compared before and after radioactive iodine therapy. Results: The analysis was performed on 37 patients with 44 lesions (lymph node:24, lung:16, bone:4). Sixteen lesions (70%) were increased and 7 (30%) showed no change or reduction when there was positive accumulation on FDG PET/CT and negative accumulation on I-131 (F(+)I(−)) group. In the positive accumulation for both FDG PET/CT and I-131 (F(+)I(+)) group, 5 lesions (63%) were increased and 3 (37%) showed no change or reduction. There was no significant difference for the tendency to increase in size between the F(+)I(−) and the F(+)I(+) groups. Conclusions: Lesions which show positive accumulations on FDG PET/CT have a greater tendency to increase in size. FDG-avid lesions are resistant to radioactive iodine therapy with or without I-131 uptake.

F-18 FDG-PET/CT Contributes to More Accurate Detection of Lymph Nodal Metastasis From Actively Proliferating Esophageal Squamous Cell Carcinoma

Purpose: Evaluating the status of disease progression is critical for planning a therapeutic strategy for esophageal cancer. In this regard, F-18 fluorodeoxyglucose-labeled positron emission tomography (PET) is one of the most useful diagnostic modalities. However, there is room to improve its diagnostic performance, such as distinguishing lymph nodal metastases from false positives. In this study, we examined the diagnostic accuracy of fluorodeoxyglucose PET accompanied by computed tomography imaging (PET/CT) to detect regional lymph nodal metastasis from esophageal squamous cell carcinoma (ESCC). Methods: A total of 102 patients diagnosed as ESCC were subjected to this study. These patients had a preoperative PET/CT examination to evaluate the existence of metastasis. The values of maximum standardized uptake value (SUVmax) in primary tumors and in metastasized lymph nodes were measured to analyze their relationship with various clinicopathologic characteristics including the status of tumor cell proliferation, which was assessed by immunohistochemistry for Ki-67. Results: The SUVmax of the primary tumor was positively correlated with tumor size and vessel invasion, and was positively related with the SUVmax of lymph nodal metastasis, especially in cases of poorly differentiated ESCC. The SUVmax of metastasized lymph nodes was higher in larger-sized metastasized lymph nodes, whereas the Ki-labeling index of lymph nodal metastasis was positively related with the SUVmax per unit area (SUVmax/mm2). The diagnostic accuracy of PET/CT (87.3%) was higher than that of conventional CT scans (78.4%). Conclusions: The improved diagnostic accuracy of PET/CT can be explained by its ability to detect actively progressive metastasis at an early phase regardless of size.

Conjunctival lymphoma can be detected by FDG PET

Four consecutive patients presented with extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) in the conjunctiva. After the initial resection, long-term follow-up without additional therapy showed the clinical relapse. Fluorodeoxyglucose positron emission tomography fused with computed tomography (PET/CT) showed abnormal uptake in the conjunctival relapsed lesions, which were, on reresection, again proven as MALT lymphoma. Small and thin lesions of MALT lymphoma in the conjunctiva can be detected by fluorodeoxyglucose PET/CT. The resolution of PET/CT, delineated in this study, could be applied to the other areas of the body to achieve more accurate staging of lymphoma.

Intrathoracic vagal nerve schwannoma preoperative diagnosis is correct because of clinical and characteristic ct findings —A case report and review of the literature—

A 60-year-old man was operated with the clinical diagnosis of intrathoracic vagal nerve schwannoma because of characteristic CT findings and no symptom of neurofibromatosis. Thoracoscopic surgery was performed and it was confirmed pathologically. Intrathoracic vagal nerve tumor is rare, so preoperative diagnosis seems to be difficult. We review the intrathoracic vagal nerve tumors reported in Japan (52 cases of schwannoma and 9 cases of neurofibroma), and analyzed the tumor location, furthermore, the relationship of neurofibromatosis and schwannoma and neurofibroma on vagal nerve tumor.