title: Magnetic resonance imaging of intramuscular metastases.
abstract: OBJECTIVE
  The aim of the present study was to analyse magnetic resonance findings of intramuscular metastases (IM) in a relatively large series.
  
  
  METHODS
  From January 2000 to January 2010, 28 patients (207 metastases) were retrospectively identified in the radiological database of the Martin-Luther-University. Several different scanning protocols were used depending on the localisation of IM. In 12 patients diffusion-weighted (DW) images were obtained with a multi-shot SE-EPI sequence. Apparent diffusion coefficient (ADC) maps were also calculated. Furthermore, fusion images were manually generated between the DW and half-Fourier acquisition single-shot turbo spin echo (HASTE) images.
  
  
  RESULTS
  On T2-weighted images, 97% of the recognised IM were hyperintense in comparison to unaffected musculature, and 3% were mixed iso- to hyperintense. On T1-weighted images most IM (91%) were homogeneously isointense in comparison to muscle tissue, whereas 4% were hypointense, and 5% lightly hyperintense. ADC maps were calculated for 91 metastases ranging from 0.99 to 4.00 mm(2)s(-1) (mean value 1.99 ± 0.66). ADC values of low (<1.5) signal intensity (SI) were identified in 26%, moderate SI (from 1.5 to 3.0) in 68%, and high SI (>3.0) in 6%. Of the IM that were investigated with contrast medium, 88.5% showed marked enhancement. It was homogeneous in 88% and heterogenous in 6%. Rim enhancement with central low attenuation was seen in 6%. There was no difference in enhancement characteristics with respect to ADC values or fusion patterns. Peritumoral enhancement was identified in 2.4%.
  
  
  CONCLUSIONS
  Magnetic resonance features of muscle metastases are relatively typical and consist of round or oval intramuscular masses with well-defined margins, marked enhancement, low or moderate ADC values, and moderate to high signal intensity on fusion images.
authors.affiliation: Department of Radiology, Martin-Luther-University Halle-Wittenberg, Halle, Germany. alex.surow@medizin.uni-halle.de
authors.forename: Alexey
authors.initials: A
authors.lastname: Surov
authors.forename: Eckhard
authors.initials: E
authors.lastname: Fiedler
authors.forename: Wieland
authors.initials: W
authors.lastname: Voigt
authors.forename: Andreas
authors.initials: A
authors.lastname: Wienke
authors.forename: Hans-Jürgen
authors.initials: HJ
authors.lastname: Holzhausen
authors.forename: Rolf-Peter
authors.initials: RP
authors.lastname: Spielmann
authors.forename: Curd
authors.initials: C
authors.lastname: Behrmann
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D018485:Muscle Fibers, Skeletal / Q000473:pathology*; D019042:Muscle Neoplasms / Q000175:diagnosis* / Q000556:secondary*; D015588:Observer Variation; D012189:Retrospective Studies