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Clinical Nuclear Medicine:
doi: 10.1097/RLU.0b013e3182a20d5c
Original Articles

The Additional Value of Attenuation Correction CT Acquired During 18F-FDG PET/CT in Differentiating Mature From Immature Teratomas

Cho, Arthur MD*; Kim, Se-woong BS; Choi, Jiyoun MD*; Kang, Wonjun MD, PhD*; Lee, Jong-doo MD, PhD*; Yun, Mijin MD, PhD*

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Abstract

Introduction

Increased 18F-FDG uptake is often seen in soft-tissue components or in neuronal components of teratomas, which makes differentiation of mature and immature teratoma difficult using only 18F-FDG uptake. The distribution pattern of fat and calcification in teratomas is characteristic on CT, which can also be well seen on attenuation correction CT (AC-CT). We hypothesize that the fat and calcification distribution patterns on AC-CT taken during PET/CT will provide additional diagnostic information in differentiating between mature and immature teratomas.

Patients and Methods

This retrospective study included 34 patients (44 masses; mean age 32 ± 16.3 years, range 0.2–70 years) who underwent 18F-FDG PET/CT before surgical resection for teratomas. 18F-FDG equal to or higher than the liver was visually considered positive. AC-CT images acquired during PET/CT were reviewed for calcification and fat distribution patterns. AC-CT findings for immature teratomas were scattered fat and/or disperse coarse calcification. Pathologic results were categorized into mature and immature teratomas. SUVmax and AC-CT findings were correlated with pathologic results.

Results

Out of the 44 lesions, 11 teratomas were immature, with higher 18F-FDG uptake in these tumors (7.8 ± 4.10 vs. 2.1 ± 2.28, P < 0.001). SUVmax higher than 2.8 were 91% accurate, but fat and/or calcification patterns on AC-CT were extremely helpful in reducing false-positive findings based on 18F-FDG uptake alone.

Conclusion

Characteristic fat and calcification patterns on AC-CT of PET/CT were extremely helpful in differentiating mature from immature teratomas, especially in mature teratomas with increased 18F-FDG uptake. This can potentially reduce unnecessary radiation exposure from additional contrast-enhanced CT.

Copyright © 2013 by Lippincott Williams & Wilkins

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