However, intramuscular lesions may have similar attenuation as the skeletal muscle and may be missed, unless there is muscle expansion, invasion of adjacent osseous structures, or enhancement after administration of intravenous (IV) contrast material. CT is also useful for image-guided biopsy of lesions [32]. FDG-PET/CT Skull Base to Mid-Thigh FDG-PET/CT is valuable in the staging (presurgical planning, detection of distant metastases) and follow-up of patients with primary soft-tissue sarcomas, with maximum standardized uptake value (SUVmax) measurements being correlated with greater glucose transporter protein expression and histologic aggressiveness [33]. In one study, FDG-PET/CT was shown to have prognostic value, with greater event-free survival in patients whose tumors measured less than SUVmax 10.2 [33]. In addition, FDG-PET/CT may be helpful in directing image-guided needle biopsy to areas of metabolic activity to improve diagnostic accuracy in heterogeneous tumors [32]. Although FDG- PET/CT is sensitive for the detection of FDG-avid tumors, false-positives may result from misinterpretation of various normal physiologic states, including skeletal muscle uptake, brown fat uptake, and some benign lesions, such as infection, inflammation, healing fractures, and fibrous dysplasia. In one large retrospective series, benign nonphysiologic FDG uptake was present in >25% of oncologic FDG-PET/CT, with 55.7% of lesions showing moderate or marked FDG uptake relative to background [34]. Choi et al [35] determined that FDG-PET/CT had poor performance (accuracy 57.2%) in differentiating between benign and metastatic rib lesions, with the best SUVmax cutoff to differentiate being low at 2.4. However, predictive value for metastases was improved when FDG- PET activity was combined with CT findings of correlative osteolytic and osteoblastic lesions [35]. FDG-PET/CT may identify CT occult bone metastases, which demonstrate focal FDG uptake without a corresponding lesion on
Nontraumatic Chest Wall Pain. However, intramuscular lesions may have similar attenuation as the skeletal muscle and may be missed, unless there is muscle expansion, invasion of adjacent osseous structures, or enhancement after administration of intravenous (IV) contrast material. CT is also useful for image-guided biopsy of lesions [32]. FDG-PET/CT Skull Base to Mid-Thigh FDG-PET/CT is valuable in the staging (presurgical planning, detection of distant metastases) and follow-up of patients with primary soft-tissue sarcomas, with maximum standardized uptake value (SUVmax) measurements being correlated with greater glucose transporter protein expression and histologic aggressiveness [33]. In one study, FDG-PET/CT was shown to have prognostic value, with greater event-free survival in patients whose tumors measured less than SUVmax 10.2 [33]. In addition, FDG-PET/CT may be helpful in directing image-guided needle biopsy to areas of metabolic activity to improve diagnostic accuracy in heterogeneous tumors [32]. Although FDG- PET/CT is sensitive for the detection of FDG-avid tumors, false-positives may result from misinterpretation of various normal physiologic states, including skeletal muscle uptake, brown fat uptake, and some benign lesions, such as infection, inflammation, healing fractures, and fibrous dysplasia. In one large retrospective series, benign nonphysiologic FDG uptake was present in >25% of oncologic FDG-PET/CT, with 55.7% of lesions showing moderate or marked FDG uptake relative to background [34]. Choi et al [35] determined that FDG-PET/CT had poor performance (accuracy 57.2%) in differentiating between benign and metastatic rib lesions, with the best SUVmax cutoff to differentiate being low at 2.4. However, predictive value for metastases was improved when FDG- PET activity was combined with CT findings of correlative osteolytic and osteoblastic lesions [35]. FDG-PET/CT may identify CT occult bone metastases, which demonstrate focal FDG uptake without a corresponding lesion on