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.
From the *Department of Nuclear Medicine, Yonsei University Health System, Seoul, and †Yonsei University Medical School, Seoul, Korea.
Received for publication January 23, 2013; and revision accepted June 20, 2013.
This content was presented at the 2012 SNMMI Meeting in Miami: http://jnumedmtg.snmjournals.org/cgi/content/meeting_abstract/53/1_MeetingAbstracts/1337.
Conflicts of interest and sources of funding: none declared.
Reprints: Mijin Yun, MD, PhD, Department of Nuclear Medicine, Yonsei University Health System, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-752, South Korea. E-mail: firstname.lastname@example.org.