MRI of degenerative bone marrow lesions in experimental osteoarthritis of canine knee joints.
OBJECTIVE
The objective of this study was to determine the value of MRI in the detection of degenerative bone marrow abnormalities in an animal osteoarthritis model.


METHODS
In 10 dogs with experimentally induced unilateral osteoarthritis of the knee, MRI was performed using two-dimensional spin-echo (2D-SE) and three-dimensional gradient-echo (3D-GE) imaging. Contrast enhanced T1-weighted 2D-SE sequences were also obtained after injection of gadolinium-DTPA. The results were compared with the gross and histopathologic findings and with radiography.


RESULTS
Histopathologic specimens revealed 21 osteosclerotic lesions and 5 intraosseous cysts. On 2D-SE images, 24 of 26 lesions were detected, while 21 of 26 lesions were identified on 2D-GE sequences. Radiography, including conventional tomography, demonstrated 9 of 26 lesions. Regardless of the sequence weighting, all osteosclerotic lesions appeared hypointense on MRI. Signal loss in bone sclerosis resulted primarily from the reduction of intact fat marrow, the increased bone density being of secondary importance. Quantitative signal analysis allowed approximate estimation of the grade of sclerosis. On postcontrast images, sclerotic bone remained hypointense, although significant but non-specific enhancement relative to the normal fat marrow was observed. The extent of contrast enhancement did not correlate with the grade of osteosclerosis. All five cysts were readily diagnosed by MRI. Cysts displayed either central or marginal contrast enhancement within their cavities.


CONCLUSIONS
MRI provides a sensitive method for the diagnosis of osteoarthritic bone abnormalities, allowing their differentiation from most non-degenerative subarticular lesions.
Nolte-Ernsting
C C
CC
Department of Diagnostic Radiology, University of Technology, Aachen, Germany.
Adam
G
G
Bühne
M
M
Prescher
A
A
Günther
R W
RW
D000818:Animals; D001845:Bone Cysts / Q000175:diagnosis; D001853:Bone Marrow / Q000000981:diagnostic imaging / Q000473:pathology*; D003287:Contrast Media; D004195:Disease Models, Animal; D004285:Dogs; D005682:Gadolinium; D019786:Gadolinium DTPA; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D009942:Organometallic Compounds; D010003:Osteoarthritis / Q000175:diagnosis*; D004369:Pentetic Acid / Q000031:analogs & derivatives; D011859:Radiography
D003287:Contrast Media; D009942:Organometallic Compounds; D004369:Pentetic Acid; D005682:Gadolinium; D019786:Gadolinium DTPA