title: Intramuscular dissociation of echogenicity in the triceps surae characterizes sporadic inclusion body myositis.
abstract: OBJECTIVE
  Differential diagnosis of sporadic inclusion body myositis (s-IBM) and polymyositis (PM)/dermatomyositis (DM) is difficult and can affect proper disease management. Detection of heterogeneous muscular involvement in s-IBM by muscle sonography could be a unique diagnostic feature.
  
  
  METHODS
  Sonography of the lower leg and forearm was performed in patients with s-IBM, PM/DM and control subjects (n = 11 each). Echo intensities (EIs) of the adjacent muscles [medial head of the gastrocnemius versus soleus and the flexor digitorum profundus (FDP) versus flexor carpi ulnaris (FCU)] were scored by three blinded raters. The mean EIs of these muscles were compared using computer-assisted histogram analysis.
  
  
  RESULTS
  Both evaluation methods showed high echoic signals in the gastrocnemius of patients with s-IBM. EIs were significantly different between the gastrocnemius and soleus in patients with s-IBM, but not in those with DM/PM and the controls. In the forearm, although the EI of the FDP was higher in the s-IBM group than in the other groups, the EI differences between the FDP and FCU did not differ significantly between disease groups. The difference in area under the curves to differentiate between s-IBM and DM/PM was greatest between the gastrocnemius-soleus EIs (0.843; P = 0.006).
  
  
  CONCLUSIONS
  High echoic signals in the medial gastrocnemius compared with those of the soleus are suggestive of s-IBM over PM/DM.
authors.affiliation: Department of Neurology, Tokushima University, Tokushima, Japan.
authors.forename: H
authors.identifier: http://orcid.org/0000-0002-5357-5081
authors.initials: H
authors.lastname: Nodera
authors.affiliation: Department of Neurology, Tokushima University, Tokushima, Japan.|Vihara Hananosato Hospital, Miyoshi, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Takamatsu
authors.affiliation: Department of Neurology, Tokushima University, Tokushima, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Matsui
authors.affiliation: Department of Neurology, Tokushima University, Tokushima, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Mori
authors.affiliation: Department of Neurology, Tokushima University, Tokushima, Japan.|Department of Neurology, Jikei University School of Medicine, Tokyo, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Terasawa
authors.affiliation: Department of Neurology, Tokushima University, Tokushima, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Shimatani
authors.affiliation: Department of Neurology, Tokushima University, Tokushima, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Osaki
authors.affiliation: Department of Neurology, Tokushima University, Tokushima, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Maruyama
authors.affiliation: Department of Neurology, Tokushima University, Tokushima, Japan.|Vihara Hananosato Hospital, Miyoshi, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Izumi
authors.affiliation: Department of Neurology, Tokushima University, Tokushima, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Kaji
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003882:Dermatomyositis / Q000000981:diagnostic imaging*; D003937:Diagnosis, Differential; D005260:Female; D005542:Forearm / Q000000981:diagnostic imaging*; D006801:Humans; D007866:Leg / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging*; D018979:Myositis, Inclusion Body / Q000000981:diagnostic imaging*
keywords: echogenicity; histogram; inclusion body myositis; sonography; triceps surae