Combined imaging with 18F-FDG-PET/CT and 111In-labeled octreotide SPECT for evaluation of thymic epithelial tumors

Serena De Luca, Rosa Fonti, Giovannella Palmieri, Piera Federico, Giuseppina Del Prete, Roberto Pacelli, Leonardo Pace, Sabino De Placido, Marco Salvatore, Silvana Del Vecchio

Research output: Contribution to journalArticlepeer-review

Abstract

PURPOSE: This study aimed to test the role of combined imaging with F-FDG-PET/CT and In-octreotide SPECT in characterizing thymic epithelial tumors (TETs). METHODS: We evaluated 20 patients with newly diagnosed TETs who had undergone concomitant F-FDG-PET/CT and In-octreotide SPECT. Thymic epithelial tumors were classified by World Health Organization (WHO) as low-risk thymomas (5), high-risk thymomas (4), and thymic carcinomas (11, among which 6 neuroendocrine tumors). Patients were staged according to Masaoka system. F-FDG-PET/CT was performed and SUVmax of primary tumors was recorded. In-octreotide SPECT of the thorax was performed, and tumor-to-background ratio was determined on the 24-hour coronal sections. RESULTS: All patients showed increased F-FDG uptake in mediastinal lesions. SUVmax were significantly correlated with WHO classification (r = 0.66, P <0.01) and with Masaoka stage (r = 0.60, P <0.01). SUVmax of low-risk thymomas (mean [SD], 2.87 [0.83]) were significantly lower than those of high-risk thymomas (mean [SD], 7.21 [1.73], P <0.01) and of thymic carcinomas (mean [SD], 9.39 [5.80], P <0.05), whereas no significant difference was found between high-risk thymomas and thymic carcinomas. SUVmax of all high-risk thymomas and thymic carcinomas was 4.5 or greater. All primary tumors were detected by In-octreotide SPECT, and tumor-to-background ratios ranged between 1.67 and 10.10. No statistically significant correlation was found between tumor-to-background ratios and WHO classification (r = 0.24, P = 0.36) and Masaoka stages (r = 0.31, P = 0.23). However tumor-to-background ratios of thymic neuroendocrine tumors (mean [SD], 5.71 [3.09]) were significantly higher than those of all other TETs with SUVmax of 4.5 or greater (mean [SD], 2.41 [0.56]; P <0.05). CONCLUSIONS: F-FDG-PET/CT scan allows to differentiate high-risk epithelial tumors and thymic carcinomas from low-risk thymomas, whereas In-octreotide SPECT may identify neuroendocrine tumors among those showing high F-FDG uptake.

Original languageEnglish
Pages (from-to)354-358
Number of pages5
JournalClinical Nuclear Medicine
Volume38
Issue number5
DOIs
Publication statusPublished - May 2013

Keywords

  • 111In-octreotide
  • 18F-FDG-PET/CT
  • functional imaging
  • multimodality imaging
  • thymic epithelial tumors
  • thymic neuroendocrine tumors

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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