Wacker F K, Bolze X, Felsenberg D, Wolf K J
Benjamin Franklin University Hospital, Free University Berlin, Germany.
Skeletal Radiol. 1998 Jun;27(6):306-10. doi: 10.1007/s002560050387.
To study magnetic resonance (MR) imaging pattern of normal hyaline articular cartilage in the knee joint with regard to the contribution of the "magic angle" effect to the MR signal.
Thirty-two healthy volunteers were imaged in a standard supine position in a 1.5-T unit using spin echo and gradient echo sequences. Nine volunteers were reimaged with the knee flexed. The signal behavior of the hyaline cartilage of the femoral condyles was evaluated qualitatively and quantitatively. The extended and flexed positions of the nine volunteers were compared.
A superficial and a deep hyperintense layer and a hypointense middle cartilage layer were observed. Segments of increased signal intensity were visible along the condyles; a magic angle effect on signal intensity was evident in the hypointense middle layer with both gradient echo and spin echo images.
The MR signal behavior of hyaline cartilage is influenced by the alignment of the collagen fibers within the cartilage in relation to the magnetic field. Failure to recognize this effect may lead to inaccurate diagnosis.
研究膝关节正常透明关节软骨的磁共振（MR）成像模式，以及“魔角”效应对MR信号的影响。
32名健康志愿者在1.5-T设备上采用自旋回波和梯度回波序列以标准仰卧位进行成像。9名志愿者在膝关节屈曲时再次成像。对股骨髁透明软骨的信号表现进行定性和定量评估。比较9名志愿者膝关节伸展和屈曲位的情况。
观察到浅层和深层高信号层以及中间低信号软骨层。沿髁可见信号强度增加的节段；在低信号中间层，梯度回波和自旋回波图像均显示出明显的信号强度魔角效应。
透明软骨的MR信号表现受软骨内胶原纤维相对于磁场排列的影响。未能认识到这种效应可能导致诊断不准确。
