Prevalence and patterns of soft tissue metastasis: detection with true whole-body F-18 FDG PET/CT.
BACKGROUND
The aim of this retrospective study was to report the prevalence and patterns of soft tissue (ST) metastasis detected with true whole-body (TWB) F-18 FDG PET/CT acquired from the top of the skull through the bottom of the feet and to compare such findings to that of the typically acquired skull-base to upper-thigh, thus limited whole-body (LWB) field of view (FOV).


METHODS
TWB FDG-PET/CT scans were performed in 500 consecutive cancer patients. Suspected ST metastasis was verified by correlation with surgical pathology, other imaging modalities, or clinical follow-up.


RESULTS
Nine out of 500 patients (1.8 %) had ST metastasis with a prevalence of 4/41 (9.8%) for melanoma, 2/60 (3.3%) for lung carcinoma, 2/88 (2.3%) for lymphoma and 1/13 (77%) for esophageal cancer. Those nine patients had a total of 41 ST lesions: 22 lesions within and 19 outside of LWB FOV. Of those 41 lesions, 19 (46%) were subcutaneous and 22 (54%) were muscular lesions. The presence of ST metastasis neither changed the staging nor the treatment in any of these patients. However, the ST lesions provided a biopsy site in 4 of the 9 patients (44%). Seven out of nine studied patients died of their disease within 1-22 months after ST metastasis was diagnosed.


CONCLUSIONS
The detection of ST metastasis may have prognostic implications, provide more accessible biopsy sites and help avoid invasive procedures. A LWB scanning may underestimate the true extent of ST metastasis since a significant percentage of ST metastasis (46%) occurred outside the typical LWB FOV.
Nguyen
Nghi C
NC
Division of Nuclear Medicine, Department of Radiology, Saint Louis University Hospital, St, Louis, USA. Nghihoaben@yahoo.com
Chaar
Bassem T
BT
Osman
Medhat M
MM
D000328:Adult; D000368:Aged; D001706:Biopsy; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis / Q000000981:diagnostic imaging; D015995:Prevalence; D011379:Prognosis; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D012983:Soft Tissue Neoplasms / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000556:secondary*; D014055:Tomography, Emission-Computed; D014057:Tomography, X-Ray Computed; D051598:Whole Body Imaging
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18