Han Na Lee MD, Presenter: Nothing to Disclose

Ji Seon Park MD, PhD, Abstract Co-Author: Nothing to Disclose

Sung Eun Ahn, Abstract Co-Author: Nothing to Disclose

Kyung Nam Ryu MD, PhD, Abstract Co-Author: Nothing to Disclose

Wook Jin, Abstract Co-Author: Nothing to Disclose

So Young Park, Abstract Co-Author: Nothing to Disclose

Jung Eun Lee, Abstract Co-Author: Nothing to Disclose

Sohee Yoon MD, Abstract Co-Author: Nothing to Disclose

Even in asymptomatic knees, the increased signal intensities(SI) of lateral collateral ligament(LCL) at femoral attachment are commonly seen on fat-suppressed(FS) proton-density-weighted(PDW) MR images, unlike the midportion of LCL. We evaluated the histological differences between the above two portions of LCL and clarified the cause of these signal differences using cadaveric knees.

MRI was obtained from 11 cadaveric knees (M:F = 7:4, mean age at death = 77.5 years, age range, = 58~96 years). Two musculoskeletal radiologists evaluated the SI at both the femoral attachment and midportion of LCL using FS PDW coronal and axial images. The SI are classified into 3 grades (I = low, II = slightly high, III = high or fluid-like). These MR findings were correlated with the corresponding gross and histological sections.

All LCLs revealed the increased SI at femoral attachment including 9 cases of grade II and 2 cases of grade III. Two cases of grade III had a thin layer of fluid-like high signal, but smooth contour was preserved. SI of LCLs at midportion was grade I in all cases. On histological examinations, LCL at femoral attachment showed loose collagen fibers with twisted or irregular distribution, whereas LCL at midportion revealed dense collagen fibers with parallel or well-organized distribution. Additionally, interspersed vessels within loose fibrous layer were found. These findings were prominent at deeper portion than superficial layer within the femoral attachment. Degeneration or tear of LCL was none even in the cases of grade III.

Based on this study, increased SI of LCL at femoral attachment on FS PDW image is due to differences in density and orientation of collagen fibers, rather than true degeneration or tear.

Normal LCL at femoral attachment can demonstrate the increased SI on FS PDW MR images caused by histological differences.

Lee, H, Park, J, Ahn, S, Ryu, K, Jin, W, Park, S, Lee, J, Yoon, S, Increased Signal Intensity of Lateral Collateral Ligament at Femoral Attachment on Fat-suppressed Proton-density-weighted MR Images: Is it Normal or Abnormal?.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14007813.html