MRI的假性脊髓空洞与参数选择

PSEUDOSYRINGOMYELIAANDPARAMETERS SELECTIONINMRI

通过对脊髓模型及健康志愿者的ＭＲＩ研究，探讨了假性脊髓空洞与横贯脊髓象素数Ｎ的关系，认为当ＰＥ（相位编码）＝２５６时，髓内（矢状面）一般不出现单条低信号伪影带。当ＰＥ＝１２８时，且选择的ＦＯＶ使①Ｎ（Ｎ＝脊髓前后径×１２８／ＦＯＶ）接近、等于或略大于４时，髓内可出现单条低信号带即假性空洞；②Ｎ＞５时，髓内可出现双条低信号带；③Ｎ＝５或Ｎ≤３时，髓内伪影不明显。

Arelationship between the pixelsspanning the spinal cord and the occurringof the pseudosyringomyelia was investigated by using a spinal cord phantom andnormal volunteer. The single hypointensive band in the spinal cord was usuallyabsent if 256 phase-encoding steps(PE) was selected. However,if PE=128,andthrough a selection of FOV that makes:①the number of pixels(N)(N=A-Pdiameter of the spinal cord×128/FOV) spanning the cord near by,equal to,orslightly larger than 4, the low intensive band along the long axis of the spinalcord,i.e. the pseudosyringomyelia,was appeared;②N>5,a double low inten-sive striations within the cord could be seen;③N=5or N≤3, no pseudosy-ringomyelia was showed in the spinal cord.