To evaluate lesion detection of MR1 in knee joint osteoarthritis in patients with symptoms of pain,the correlation between MRI findings and varying degrees of reported pain was assessed.Twenty-eight patients(31 knees)with osteoarthritis were recruited for this study.The degree of knee pain was assessed by VRS scores.The knees were evaluated by plain film radiograph utilizing Kellgren-Lawrence scores.Multiple MR sequences were performed on a 1.5T MR-system,including sagittal and coronal dual fast spin echo(TR/TE 3660/11/120 ms,slice thickness 5 mm),coronal spin echo T1-weighted(TR/TE 360/9 ms,slice thickness 5 mm),sagittal fat saturated 3D-spoiled gradient-recalled echo(TR/TE 50/6 ms; slice thickness 1.5 mm; flip angle 40°),and 3D steady-state free precession (TR/TE 6/2.2 ms; slice thickness 1.6 mm: flip angle 30°)pulse sequences for the purpose of detecting abnormities of cartilage,menisci,the anterior cruciate ligaments,bone marrow edema-like lesions,osteophytes,synovitis,and joint effusions.MR findings were compared with the degree of pain using Fisher exact test with P values less than 0.05 indicating a statistically significant difference.The results showed that,of the 31 knees evaluated,mild pain was reported in 11 and severe pain in the remainder.Kellgren-Lawrence scores of all 31 evaluated OA knees were as follows: grade 1 lesions(n=6),grade 2 lesions(n=14),grade 3 lesions(n=8),and grade 4 lesions(n=3).Articular cartilaginous defects were found in 37.1% of knees.Abnormalities of the menisci and anterior cruciate ligaments,bone marrow edema-like lesions,osteophytes,synovitis,and joint effusions were detected in 32.3%,38.7%,45.2%,100%,15.1% and 67.7% of knees,respectively.Of these variables,only the differences in prevalence of joint effusions were significantly different in the mild and severe pain groups(P=0.004).It is concluded that MRI evaluates the entire joint structure of the osteoarthritic knee,demonstrating abnormalities of the cartilage,menisci,and anterior cruciate ligaments as well as bone marrow edema-like lesions,osteophytes,synovitis,and joint effusions.The difference in pain grading between OA patients reporting mild and severe degrees of pain is related to the presence of joint effusion.