title: Skeletal muscle metastases on magnetic resonance imaging: analysis of 31 cases.
abstract: OBJECTIVE
  To investigate the magnetic resonance imaging (MRI) features of skeletal muscle metastases (SMM).
  
  
  METHODS
  The records of 31 patients with proven SMM were retrospectively reviewed. Clinical history, type of primary malignancy, location of metastases, and MRI features of SMM were evaluated. Based on MRI findings, SMM were divided into three MRI types. The correlation between MRI types with ages and pathology category, between MRI types of SMM and ages, as well as MRI types of SMM and pathology category were analysed with Spearman's rho.
  
  
  RESULTS
  The most common primary tumour was genital tumour (25.8%) and bronchial carcinoma (19.4%), and the most common cell type was adenocarcinoma (58.1%). SMM were located in the iliopsoas muscle (26.3%), paravertebral muscles (21.1%), and upper extremity muscles (18.4%). MRI features: (1) Type-I localised lesions (12.90%), round-like mass limited to local regions with heterogeneous iso-signal intensity in T1WI and heterogeneous hyper-intensity in T2WI; (2) Type-II diffuse lesions without bone destruction (35.48%), abnormal diffuse swelling of the muscle with irregular boundaries and slightly hypo- to iso-intensity in T1WI and hyper-intensity in T2WI; and (3) Type-III diffuse lesions with bone destruction (51.61%), distinct irregular lump with iso-intensity in T1WI and heterogeneous hyper-intensity in T2WI with adjacent bone invasion. There was positive correlation between MRI types and ages (r = 0.431, p < 0.05). There were no significant differences of MRI types with pathology category (p > 0.05).
  
  
  CONCLUSIONS
  SMM features on MRI can be broadly used to classify lesions, which is beneficial for SMM diagnosis.
authors.affiliation: Department of Radiology, Shengjing Hospital of China Medical University, China; Department of Radiology, Liaoning Electric Power Central Hospital, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Li
authors.affiliation: Department of Radiology, Liaoning Electric Power Central Hospital, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Radiology, Shengjing Hospital of China Medical University, China.
authors.forename: Shinong
authors.initials: S
authors.lastname: Pan
authors.affiliation: Department of Pathology, Shengjing Hospital of China Medical University, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Shu
authors.affiliation: Department of Pathology, Shengjing Hospital of China Medical University, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Ma
authors.affiliation: Department of Radiology, Shengjing Hospital of China Medical University, China.
authors.forename: Zaiming
authors.initials: Z
authors.lastname: Lu
authors.affiliation: Department of Radiology, Shengjing Hospital of China Medical University, China.
authors.forename: Xihu
authors.initials: X
authors.lastname: Fu
authors.affiliation: Department of Radiology, Liaoning Electric Power Central Hospital, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Jiang
authors.affiliation: Department of Radiology, Shengjing Hospital of China Medical University, China.
authors.forename: Qiyong
authors.initials: Q
authors.lastname: Guo
keywords: MRI; metastases; skeletal muscle; tumour