title: PET/CT imaging of skeletal muscle metastases.
abstract: BACKGROUND
  Skeletal muscle metastases (SMM) are very rare because of complex resistance of the musculature to metastatic invasion. Previously, positron emission tomography (PET) imaging of SMM has been reported only in few reports. A systematic analysis of SMM features in PET/CT has not been performed before.
  
  
  OBJECTIVE
  To study PET/CT findings of SMM in a larger group of patients with known malignancies and to determine PET/CT patterns of SMM in different primary tumors.
  
  
  METHODS
  Between January 2009 and December 2011 581 patients with lung cancer were investigated by PET with 18 F-fluordeoxyglucose (FDG PET) and computed tomography (CT) at the Center of Fusion Imaging, Halle. In five patients SMM were identified. Furthermore, PubMed database was screened for muscle metastases. Only articles containing SUV of SMM were considered in the study. Twenty-one articles with 33 patients could be included in this meta-analysis from the literature.
  
  
  RESULTS
  At our center the prevalence of SMM was 0.9%. Our analysis comprised 38 patients with 67 muscle metastases. All identified SMM presented as intramuscular focal abnormal activity with SUV ranging from 2.4 to 25.9, median SUV 7.8. The median size of the muscle metastases was 2.5 cm (range, 0.6-6.5 cm). There were no significant differences between SUV and size of SMM arising from lung cancer, renal cell carcinoma, and esophageal cancer. Also, there was no correlation between SUV and size of SMM (r = 0.101, P = 0.558) and between SUV of SMM and primary tumors (r = 0.138, P = 0.686). In nine (23.7%) of the 38 patients, the identified SMM were isolated distant metastases or isolated tumor recurrence.
  
  
  CONCLUSIONS
  SMM manifested on PET/CT as focal hypermetabolic intramuscular areas with different SUV. There were no significant differences between SUV or size of the identified SMM in esophageal cancer, renal cell carcinoma, and lung cancer.
authors.affiliation: Department of Radiology, Martin-Luther-University Halle-Wittenberg, Halle, Germany.
authors.forename: Alexey
authors.initials: A
authors.lastname: Surov
authors.forename: Maria Kerstin
authors.initials: MK
authors.lastname: Pawelka
authors.forename: Andreas
authors.initials: A
authors.lastname: Wienke
authors.forename: Dominik
authors.initials: D
authors.lastname: Schramm
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D019042:Muscle Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging* / Q000473:pathology; D049268:Positron-Emission Tomography; D014057:Tomography, X-Ray Computed
keywords: Positron emission tomography/computed tomography (PET/CT); skeletal muscle metastases