Wright T, Yoon C, Schmit B P
Department of Radiology, University of Utah, Salt Lake City 84132, USA.
Semin Ultrasound CT MR. 2001 Aug;22(4):383-95. doi: 10.1016/s0887-2171(01)90028-9.
One of the difficulties with rotator cuff imaging lies in the normal variability of the tendon's signal. There may be intermediate signal present within the tendon because of magic-angle phenomenon, muscle and tendon fiber interdigitation, or tendinopathy related to degenerative changes or overuse injury. Partial and complete rotator cuff tears should be distinguishable from these causes of intermediate signal if water signal is reliably identified. This article reviews the important issue of distinguishing between rotator cuff tear and other causes of high signal in the rotator cuff, including artifacts and tendonosis. We include a review of the literature and a brief report of a study we conducted on 20 shoulders of 14 asymptomatic, young volunteers. In this study, the rotator cuff tendons were evaluated for abnormal signal at different TE values to determine at what TE the interpreters were able to confidently distinguish the high-signal intensity of a tear (water) from the intermediate signal intensity associated with artifact and tendinopathy. Readers were able to distinguish water and tendon signal in 70% to 100% of fast-spin echo (FSE) fat-saturated images with TE of 66, but there was interobserver variability at this TE, suggesting that it is less reliable than 88 ms in the identification of rotator cuff tears. By using FSE fat-saturated sequences with TE of 88 and fast spin echo inversion recovery (FSEIR) sequences, readers at all levels of experience were able to differentiate water signal intensity from tendon signal intensity in 100% of cases. Therefore, we suggest that either FSEIR images or FSE fat-saturated images with TE greater than 66 be used to facilitate the differentiation of fluid signal from intermediate increased signal intensity in rotator cuff imaging. Additionally, this article reviews the normal findings of shoulder magnetic resonance imaging (MRI) as revealed by the asymptomatic subjects included in our study, and assesses these findings in respect to previous publications. The normal features reviewed include the subacromion-subdeltoid (SA/SD) bursa, the biceps tendon sheath, the acromioclavicular (AC) joint, and the greater tuberosity of the humerus. A small amount of fluid was commonly seen in the SA/SD bursa, as well as the biceps tendon sheath. Subjective down-sloping of the acromion in the coronal plane, mild degenerative change of the AC joint, and undersurface spurring of the AC joint were uncommon in our normal subjects. Cystic change limited to the posterior aspect of the greater tuberosity was identified in 15% to 45% of shoulders.
肩袖成像的困难之一在于肌腱信号的正常变异性。由于魔角现象、肌肉与肌腱纤维相互交错，或与退变改变或过度使用损伤相关的肌腱病，肌腱内可能会出现中等信号。如果能可靠地识别出水样信号，部分和完全性肩袖撕裂应可与这些中等信号的成因区分开来。本文回顾了区分肩袖撕裂与肩袖内其他高信号成因（包括伪影和肌腱病）这一重要问题。我们纳入了文献综述以及我们对14名无症状年轻志愿者的20个肩部进行的一项研究的简要报告。在这项研究中，在不同的回波时间（TE）值下评估肩袖肌腱的异常信号，以确定在哪个TE值时，解读人员能够自信地将撕裂的高信号强度（水样信号）与与伪影和肌腱病相关的中等信号强度区分开来。在TE为66的快速自旋回波（FSE）脂肪抑制图像中，解读人员能够在70%至100%的图像中区分出水样信号和肌腱信号，但在此TE值时存在观察者间差异，这表明在识别肩袖撕裂方面，它不如88毫秒可靠。通过使用TE为88的FSE脂肪抑制序列和快速自旋回波反转恢复（FSEIR）序列，各级经验的解读人员在100%的病例中都能够区分出水样信号强度和肌腱信号强度。因此，我们建议使用FSEIR图像或TE大于66的FSE脂肪抑制图像，以利于在肩袖成像中区分液体信号与中等程度的信号强度增加。此外，本文回顾了我们研究中无症状受试者肩部磁共振成像（MRI）的正常表现，并参照以往出版物评估了这些表现。所回顾的正常特征包括肩峰下 - 三角肌（SA/SD）滑囊、肱二头肌肌腱腱鞘、肩锁（AC）关节以及肱骨大结节。在SA/SD滑囊以及肱二头肌肌腱腱鞘中通常可见少量液体。在我们的正常受试者中，肩峰在冠状面的主观下斜、AC关节的轻度退变改变以及AC关节下表面的骨刺并不常见。在15%至45%的肩部中发现了局限于大结节后部的囊性改变。
