PT  - JOURNAL ARTICLE
AU  - Lunn, Brendan
AU  - Broski, Stephen
TI  - Imaging characteristics of intramuscular myxomas on F-18 FDG PET/CT.
DP  - 2017 May 01
TA  - Journal of Nuclear Medicine
PG  - 123--123
VI  - 58
IP  - supplement 1
4099  - http://jnm.snmjournals.org/content/58/supplement_1/123.short
4100  - http://jnm.snmjournals.org/content/58/supplement_1/123.full
SO  - J Nucl Med2017 May 01; 58
AB  - 123Objectives: To examine the qualitative and semi-quantitative imaging characteristics of intramuscular myxomas on F-18 FDG PET/CT and compare these findings with MRI imaging characteristics.Methods: With IRB approval, our institutional F-18 FDG PET/CT database was searched for patients with pathologically proven intramuscular myxomas between 1/2003 and 11/2016. Comparison imaging, including MRI, and the electronic medical record were cross-referenced for included patients. PET/CT imaging characteristics, including, SUVmax, SUVmean, total lesion glycolysis (TLG), metabolic tumor volume (MTV), and CT attenuation characteristics were analyzed and compared to the MRI. MRI imaging characteristics examined included T1 signal intensity, T2 signal intensity, pattern of contrast enhancement, presence of a fatty rim, and presence of perilesional edema.Results: Our search identified eight patients with an average age of 65.6 years +/- 10.4 years (range 52-81 years). There were two males and six females. Locations of the tumors included the vastus lateralis, vastus medialis, quadratus femoris, infraspinatus, psoas, inferior gemellus, and rectus femoris muscles. Mean maximal lesion diameter was 5.6 +/- 2.5 cm. On PET/CT evaluation, the mean SUV max was 2.7 +/- 0.8, SUVmean was 1.7 +/- 0.4, TLG was 98.1 +/- 106.1 cm3[asterisk]g/m, MTV was 34.2 +/- 70.5 cm3, and mean CT Hounsfield units was 15.5 +/- 5.7. Seven patients had comparison MRIs. On MRI evaluation, 5/7 (71.4%) of the intramuscular myxomas were T1 hypointense, while 2/7 (28.6%) were T1 isointense. All myxomas studied were T2 hyperintense. A fatty rim was observed in 4/7 (57.1%) of the tumors and 5/7 (71.4%) exhibited perilesional edema. 6/7 patients undergoing MRI received contrast. Of these, 3/6 (50%) had peripheral and hazy internal enhancement, while 3/6 (50%) had heterogeneous solid enhancement. There was no significant correlation between any of the PET/CT and MRI imaging characteristics.Conclusion: This study represents the largest to date examining characteristics of intramuscular myxomas on F-18 FDG PET/CT. These benign tumors most commonly present as mildly FDG avid masses, with rare cases showing moderate FDG activity. Their intramuscular location and homogenous low attenuation on CT may help to suggest the diagnosis. While we found no correlation between MRI and PET/CT imaging characteristics, MRI is useful in imaging evaluation given the often-diagnostic appearance of myxomas on MRI. Research Support: