• Nghi C Nguyen, Bassem T Chaar, and Medhat M Osman.
• Division of Nuclear Medicine, Department of Radiology, Saint Louis University Hospital, St, Louis, USA. Nghihoaben@yahoo.com
• BMC Med Imaging. 2007 Dec 12; 7: 8.

BackgroundThe 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).MethodsTWB 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.ResultsNine 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.ConclusionThe 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.

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