Ahn J Y, Jung J Y, Kim J, Lee K S, Kim S H
Department of Neurosurgery, Brain Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea.
Acta Neurochir (Wien). 2008 Aug;150(8):763-71; discussion 771. doi: 10.1007/s00701-008-1505-1. Epub 2008 Jul 3.
Intra-operative MRI (iMRI) is used as an immediate intra-operative quality control, allowing surgeons to extend resections in situations involving residual tumour remnants. Despite these advantages, low-field iMRI has some limitations with regards to image quality and artefacts. The aim of this study is to report our experience with bone wax and Gadolinium-soaked cotton pledgets in obtaining precise tumour resection margins using low-field iMRI.
The study group included 63 consecutive patients who underwent endonasal trans-sphenoidal surgery with use of intra-operative low-field iMRI (0.15 T, PoleStar N20, Medtronic Navigation, Louisville, CO, U.S.A.). The indications for intra-operative MRI use included a suprasellar or retrosellar extension (n = 23), cavernous sinus invasion (n = 21), a tumour located in the vicinity of critical anatomic structures (such as the internal carotid artery, n = 10), recurrent or revision procedures (n = 5), and pre-operative imaging revealing unusual anatomy (n = 4).
Overall, among the 51 patients with intended complete tumour removal, iMRI revealed definite tumour remnants or suspicious findings in 13 patients (25.5%), leading to an extended resection and allowing completion of the resection in 10 patients. There was an increased rate of complete tumour removal from 74.5% (38 out of 51) to 94.1% (48 out of 51). The iMRI scan for complete tumour removal was more efficient in the group receiving Gadolinium-soaked cotton pledgets (85.2-100%) than in the group receiving bone wax or the conventional method (62.5-87.5%). The results of iMRI and the estimation by the surgeon concerning the extent of resection revealed a discrepancy in five patients (15.6%) in the Gadolinium-soaked cotton pledgets application group, and in 14 (45.2%) of the bone wax application group.
More valuable information for determining the resection margin can be obtained with the use of contrast-soaked cottonoid packing in the tumour resection cavity during iMRI scanning. We believe that the use of this simple method reduces the false-positive results and also overcomes the disadvantages of low-field iMRI.
术中磁共振成像（iMRI）用作术中即时质量控制，使外科医生能够在存在残留肿瘤残余的情况下扩大切除术范围。尽管有这些优点，但低场iMRI在图像质量和伪影方面存在一些局限性。本研究的目的是报告我们使用骨蜡和钆浸渍棉片，通过低场iMRI获得精确肿瘤切除边缘的经验。
研究组包括63例连续接受鼻内镜经蝶窦手术并使用术中低场iMRI（0.15T，PoleStar N20，美敦力导航公司，美国科罗拉多州路易斯维尔）的患者。术中使用MRI的指征包括鞍上或鞍后扩展（n = 23）、海绵窦侵犯（n = 21）、位于关键解剖结构附近的肿瘤（如颈内动脉，n = 10）、复发性或翻修手术（n = 5）以及术前影像学显示异常解剖结构（n = 4）。
总体而言，在51例计划完全切除肿瘤的患者中，iMRI显示13例患者（25.5%）有明确的肿瘤残余或可疑发现，导致扩大切除，并使10例患者完成切除。肿瘤完全切除率从74.5%（51例中的38例）提高到94.1%（51例中的48例）。在接受钆浸渍棉片的组中，用于完全切除肿瘤的iMRI扫描比接受骨蜡或传统方法的组更有效（85.2 - 100%）。iMRI结果与外科医生对切除范围的估计显示，在钆浸渍棉片应用组中有5例患者（15.6%）存在差异，在骨蜡应用组中有14例患者（45.2%）存在差异。
在iMRI扫描期间，在肿瘤切除腔内使用对比剂浸渍的棉片包装可获得更多用于确定切除边缘的有价值信息。我们认为，使用这种简单方法可减少假阳性结果，还可克服低场iMRI的缺点。
