Atlas S W, Grossman R I, Hackney D B, Goldberg H I, Bilaniuk L T, Zimmerman R A
Department of Radiology, Hospital of the University of Pennsylvania, Philadelphia 19104.
AJR Am J Roentgenol. 1988 Nov;151(5):1025-30. doi: 10.2214/ajr.151.5.1025.
Fifteen patients with CT-documented orbital lesions were evaluated with MR imaging at 1.5 T with both conventional spin-echo (SE) and short inversion time inversion recovery (STIR) sequences. Fat signal was reliably nulled at inversion times of approximately 120-200 msec in all cases, thereby allowing clear detection of all retrobulbar lesions and normal structures on STIR images as markedly hyperintense relative to fat. All lesions were also clearly depicted on SE images; in fact, short repetition time/short echo time SE sequences were at least as useful as STIR images for illustrating anatomic structures and mass lesions, and in a much shorter scanning time. Separation of optic nerve from perioptic subarachnoid space was clear on SE images, but often difficult or impossible on STIR images owing to the relatively high intensity of normal optic nerves on STIR images. The synergism of relaxation prolongation with STIR actually resulted in loss of information, as any ability to separate the effects of T1 from T2 on signal intensity was impossible when STIR was the sole pulse sequence. We believe that more information is obtained with standard SE sequences than with STIR sequences, and therefore SE remains the method of choice for orbital MR imaging.
对15例经CT证实有眼眶病变的患者进行了1.5T磁共振成像检查，采用了传统的自旋回波（SE）序列和短反转时间反转恢复（STIR）序列。在所有病例中，反转时间约为120 - 200毫秒时脂肪信号可靠地被抑制，从而在STIR图像上能够清晰地检测到所有球后病变和正常结构，相对于脂肪呈明显高信号。所有病变在SE图像上也能清晰显示；事实上，短重复时间/短回波时间的SE序列在显示解剖结构和肿块病变方面至少与STIR图像一样有用，而且扫描时间更短。在SE图像上视神经与视神经周围蛛网膜下腔的分离清晰可见，但在STIR图像上往往难以或无法分辨，这是因为正常视神经在STIR图像上信号强度相对较高。STIR序列中弛豫时间延长的协同作用实际上导致了信息丢失，因为当STIR作为唯一的脉冲序列时，无法区分T1和T2对信号强度的影响。我们认为，标准SE序列比STIR序列能获得更多信息，因此SE仍然是眼眶磁共振成像的首选方法。
