A comparative analysis of 7.0-Tesla magnetic resonance imaging and histology measurements of knee articular cartilage in a canine posterolateral knee injury model: a preliminary analysis.
BACKGROUND
There has recently been increased interest in the use of 7.0-T magnetic resonance imaging for evaluating articular cartilage degeneration and quantifying the progression of osteoarthritis.


OBJECTIVE
The purpose of this study was to evaluate articular cartilage cross-sectional area and maximum thickness in the medial compartment of intact and destabilized canine knees using 7.0-T magnetic resonance images and compare these results with those obtained from the corresponding histologic sections.


METHODS
Controlled laboratory study.


METHODS
Five canines had a surgically created unilateral grade III posterolateral knee injury that was followed for 6 months before euthanasia. The opposite, noninjured knee was used as a control. At necropsy, 3-dimensional gradient echo images of the medial tibial plateau of both knees were obtained using a 7.0-T magnetic resonance imaging scanner. Articular cartilage area and maximum thickness in this site were digitally measured on the magnetic resonance images. The proximal tibias were processed for routine histologic analysis with hematoxylin and eosin staining. Articular cartilage area and maximum thickness were measured in histologic sections corresponding to the sites of the magnetic resonance slices.


RESULTS
The magnetic resonance imaging results revealed an increase in articular cartilage area and maximum thickness in surgical knees compared with control knees in all specimens; these changes were significant for both parameters (P <.05 for area; P <.01 for thickness). The average increase in area was 14.8% and the average increase in maximum thickness was 15.1%. The histologic results revealed an average increase in area of 27.4% (P = .05) and an average increase in maximum thickness of 33.0% (P = .06). Correlation analysis between the magnetic resonance imaging and histology data revealed that the area values were significantly correlated (P < .01), but the values for thickness obtained from magnetic resonance imaging were not significantly different from the histology sections (P > .1).


CONCLUSIONS
These results demonstrate that 7.0-T magnetic resonance imaging provides an alternative method to histology to evaluate early osteoarthritic changes in articular cartilage in a canine model by detecting increases in articular cartilage area.


CONCLUSIONS
The noninvasive nature of 7.0-T magnetic resonance imaging will allow for in vivo monitoring of osteoarthritis progression and intervention in animal models and humans for osteoarthritis.
University of Minnesota Orthopaedic Biomechanics Laboratory, Department of Orthopaedic Surgery, University of Minnesota, 2450 Riverside Avenue South, Minneapolis, MN 55454, USA.
Scott R
SR
Pepin
Chad J
CJ
Griffith
Coen A
CA
Wijdicks
Ute
U
Goerke
Margaret A
MA
McNulty
Josh B
JB
Parker
Cathy S
CS
Carlson
Jutta
J
Ellermann
Robert F
RF
LaPrade
D000818:Animals; D002357:Cartilage Diseases / Q000175:diagnosis*; D002358:Cartilage, Articular / Q000033:anatomy & histology* / Q000503:physiopathology; D004285:Dogs; D006653:Histology; D007718:Knee Injuries / Q000175:diagnosis* / Q000601:surgery; D007719:Knee Joint / Q000502:physiology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D023421:Models, Animal; D010003:Osteoarthritis / Q000175:diagnosis