title: MR imaging features of foot involvement in ankylosing spondylitis.
abstract: OBJECTIVE
  To determine alterations of the soft tissue, tendon, cartilage, joint space, and bone of the foot using magnetic resonance (MR) imaging in ankylosing spondylitis (AS) patients.
  
  
  METHODS
  Clinical and MR examination of the foot was performed in 23 AS patients (46 feet). Ten asymptomatic volunteers (20 feet) were studied on MR imaging, as a control group. MR imaging protocol included; T1-weighted spin-echo, T2-weighted fast-field echo (FFE) and fat-suppressed short tau inversion recovery (STIR) sequences in sagittal, sagittal oblique, and coronal planes using a head coil. Specifically, we examined: bone erosions, tendinitis (acute and chronic), para-articular enthesophyte, joint effusion, plantar fasciitis, joint space narrowing, soft tissue edema, bone marrow edema, enthesopathy in the Achilles tendon and plantar fascia attachment, subchondral signal intensity abnormalities (edema and sclerosis), tenosynovitis, retrocalcaneal bursitis, subchondral cysts, subchondral fissures, and bony ankylosis. Midfoot, hindfoot, and ankle were included in examined anatomic regions.
  
  
  RESULTS
  Clinical signs and symptoms (pain and swelling) due to foot involvement were present in 3 (13%) of the patients while frequency of involvement was 21 (91%) with MR imaging assessment. The MR imaging findings were bone erosions (65%), Achilles tendinitis (acute and chronic) (61%), para-articular enthesophyte (48%), joint effusion (43%), plantar fasciitis (40%), joint space narrowing (40%), subchondral sclerosis (35%), soft tissue edema (30%), bone marrow edema (30%), enthesopathy of the Achilles attachment (30%), subchondral edema (26%), enthesopathy in the plantar fascia attachment (22%), retrocalcaneal bursitis (22%), subchondral cysts (17%), subchondral fissures (17%), tendinitis and enthesopathy of the plantar ligament (13%), and bony ankylosis (9%). The most common involved anatomical region was the hindfoot (83%) following by midfoot (69% ) and ankle (22%).
  
  
  CONCLUSIONS
  In our experience, MR imaging may detect inflammatory and/or erosive bone, soft tissue, cartilage, tendon, and joint abnormalities in AS patients, even if AS patients did not have clinical signs and symptoms of foot involvement. If these data prove to be confirmed in further MR studies, MR imaging may be of importance especially in early diagnosis of inflammatory changes in the foot.
authors.affiliation: Department of Radiology, School of Medicine, Zonguldak Karaelmas University, 67600 Kozlu/Zonguldak, Turkey. sunarerdem@yahoo.com
authors.forename: C Zuhal
authors.initials: CZ
authors.lastname: Erdem
authors.forename: Selda
authors.initials: S
authors.lastname: Sarikaya
authors.forename: L Oktay
authors.initials: LO
authors.lastname: Erdem
authors.forename: Senay
authors.initials: S
authors.lastname: Ozdolap
authors.forename: Sadi
authors.initials: S
authors.lastname: Gundogdu
mesh_terms: D000125:Achilles Tendon / Q000473:pathology; D000328:Adult; D000843:Ankle Joint / Q000473:pathology; D000844:Ankylosis / Q000175:diagnosis; D001845:Bone Cysts / Q000175:diagnosis; D001855:Bone Marrow Diseases / Q000175:diagnosis; D002062:Bursitis / Q000175:diagnosis; D004487:Edema / Q000175:diagnosis; D036981:Fasciitis, Plantar / Q000175:diagnosis; D005260:Female; D005529:Foot Bones / Q000473:pathology; D005534:Foot Diseases / Q000175:diagnosis*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D011446:Prospective Studies; D012216:Rheumatic Diseases / Q000175:diagnosis; D012598:Sclerosis; D013167:Spondylitis, Ankylosing / Q000150:complications*; D013582:Synovial Fluid; D052256:Tendinopathy / Q000175:diagnosis; D013717:Tenosynovitis / Q000175:diagnosis