title: What is the clinical and ethical importance of incidental abnormalities found by knee MRI?
abstract: BACKGROUND
  Magnetic resonance imaging (MRI) is increasingly used to examine joints for research purposes. It may detect both suspected and unsuspected abnormalities. This raises both clinical and ethical issues, especially when incidental abnormalities are detected. The prevalence of incidental, potentially clinically significant abnormalities identified by MRI and their clinical significance in a population undergoing knee MRI in research studies are unknown.
  
  
  METHODS
  We examined the prevalence of such lesions in healthy asymptomatic adults and those with symptomatic knee osteoarthritis (OA) undergoing knee MRI with limited sequences for the purpose of research. The MRI findings in 601 asymptomatic subjects and 132 with knee OA who underwent at least one limited knee MRI scan for cartilage volume measurement were examined by an MRI radiologist for the presence of potentially clinically significant abnormalities.
  
  
  RESULTS
  These were present in 2.3% of healthy and 2.3% of OA subjects. All required further investigation to exclude non-benign disease, including four with bone marrow expansion (0.7%), requiring further investigation and management. A single potentially life-threatening lesion, a myeloma lesion, was identified in a subject with symptomatic knee OA on their second MRI scan in a longitudinal study.
  
  
  CONCLUSIONS
  As musculoskeletal MRI is increasingly used clinically and for research purposes, the potential for detecting unsuspected abnormalities that require further investigation should be recognized. Incorporating a system to detect these, to characterize unexpected findings, and to facilitate appropriate medical follow-up when designing studies using this technology should be considered ethical research practice.
authors.affiliation: Department of Medicine, Wellington School of Medicine, University of Otago, 23A Mein St, Newtown, Wellington South 6021, New Zealand. rgrainger@malaghan.org.nz
authors.forename: Rebecca
authors.initials: R
authors.lastname: Grainger
authors.forename: Stephen
authors.initials: S
authors.lastname: Stuckey
authors.forename: Richard
authors.initials: R
authors.lastname: O'Sullivan
authors.forename: Susan R
authors.initials: SR
authors.lastname: Davis
authors.forename: Peter R
authors.initials: PR
authors.lastname: Ebeling
authors.forename: Anita E
authors.initials: AE
authors.lastname: Wluka
mesh_terms: D000368:Aged; D001853:Bone Marrow / Q000473:pathology; D001859:Bone Neoplasms / Q000175:diagnosis; D002812:Chondroma / Q000175:diagnosis; D026690:Ethics, Clinical; D005260:Female; D006801:Humans; D006965:Hyperplasia; D015994:Incidence; D033162:Incidental Findings; D007592:Joint Diseases / Q000175:diagnosis* / Q000453:epidemiology; D007719:Knee Joint / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009101:Multiple Myeloma / Q000175:diagnosis; D020370:Osteoarthritis, Knee / Q000175:diagnosis*; D015831:Osteochondroma / Q000175:diagnosis; D011151:Popliteal Cyst / Q000175:diagnosis