Department of Neurosurgery, University of Ulm, Günzburg, Germany.
J Neurosurg. 2014 Feb;120(2):346-56. doi: 10.3171/2013.9.JNS122207. Epub 2013 Dec 13.
Intraoperative MRI (iMRI) provides updated information for neuronavigational purposes and assessments on the status of resection during transsphenoidal surgery (TSS). The high-field technique additionally provides information about vascular structures at risk and precise information about extrasellar residual tumor, making it readily available during the procedure. The imaging, however, extends the duration of surgery. To evaluate the benefit of this technique, the authors conducted a retrospective study to compare postoperative outcome and residual tumor in patients who underwent conventional microsurgical TSS with and without iMRI.
A total of 143 patients were assessed. A cohort of 67 patients who had undergone surgery before introduction of iMRI was compared with 76 patients who had undergone surgery since iMRI became routine in TSS at the authors' institution. Residual tumor, complications, hormone dependency, biochemical remission rates, and improvement of vision were assessed at 6-month follow-up. A volumetric evaluation of residual tumor was performed in cases of parasellar tumor extension.
The majority of patients in both groups suffered from nonfunctioning pituitary adenomas. At the 6-month follow-up assessment, vision improved in 31% of patients who underwent iMRI-assisted surgery versus 23% in the conventional group. One instance of postoperative intrasellar bleeding was found in the conventional group. No major complications were found in the iMRI group. Minor complications were seen in 9% of patients in the iMRI group and in 5% of those in the conventional group. No differences between groups were found for hormone dependency and biochemical remission rates. Time of surgery was significantly lower in the conventional treatment group. Overall a residual tumor was found after surgery in 35% of the iMRI group, and 41% of the conventional surgery group harbored a residual tumor. Total resection was achieved as intended significantly more often in the iMRI group (91%) than in the conventional group (73%) (p < 0.034). Patients with a planned subtotal resection showed higher mean volumes of residual tumor in the conventional group. There was a significantly lower incidence of intrasellar tumor remnants in the iMRI group than in the conventional group. Progression-free survival after 30 months was higher according to Kaplan-Meier analysis with the use of iMRI, but a statistically significant difference could not be shown.
The use of high-field iMRI leads to a significantly higher rate of complete resection. In parasellar tumors a lower residual volume and a significantly lower rate of intrasellar tumor remnants were shown with the technique. So far, long-term follow-up is limited for iMRI. However, after 2 years Kaplan-Meier analyses show a distinctly higher progression-free survival in the iMRI group. No significant benefit of iMRI was found for biochemical remission rates and improvement of vision. Even though the surgical time was longer with the adjunct use of iMRI, it did not increase the complication rate significantly. The authors therefore recommend routine use of high-field iMRI for pituitary surgery, if this technique is available at the particular center.
术中磁共振成像（iMRI）为经蝶窦手术（TSS）提供了用于神经导航和评估切除状态的更新信息。高场技术还提供了有关风险血管结构的信息和关于鞍旁残留肿瘤的精确信息，使其在手术过程中随时可用。然而，成像会延长手术时间。为了评估该技术的益处，作者进行了一项回顾性研究，比较了在引入 iMRI 之前接受传统显微镜下 TSS 手术和引入 iMRI 后接受 TSS 手术的患者的术后结果和残留肿瘤。
评估了 143 名患者。将在 iMRI 引入之前接受手术的 67 名患者与在作者所在机构将 iMRI 常规应用于 TSS 后接受手术的 76 名患者进行比较。在 6 个月的随访中评估残留肿瘤、并发症、激素依赖性、生化缓解率和视力改善情况。对鞍旁肿瘤延伸的病例进行残留肿瘤的体积评估。
两组患者中大多数患有无功能垂体腺瘤。在 6 个月的随访评估中，接受 iMRI 辅助手术的患者中有 31%的视力得到改善，而常规组为 23%。在常规组中发现一例术后鞍内出血。iMRI 组未发现重大并发症。iMRI 组有 9%的患者和常规组有 5%的患者出现轻微并发症。两组在激素依赖性和生化缓解率方面无差异。常规治疗组的手术时间明显较低。总体而言，iMRI 组术后有 35%的患者存在残留肿瘤，常规手术组有 41%的患者存在残留肿瘤。iMRI 组的完全切除率（91%）明显高于常规组（73%）（p<0.034）。计划行次全切除术的患者在常规组中的残留肿瘤平均体积更高。iMRI 组的鞍内肿瘤残留发生率明显低于常规组。根据 Kaplan-Meier 分析，使用 iMRI 后 30 个月的无进展生存率更高，但未显示出统计学意义上的显著差异。
使用高场 iMRI 可显著提高完全切除率。在鞍旁肿瘤中，该技术显示出较低的残留体积和显著较低的鞍内肿瘤残留率。到目前为止，iMRI 的长期随访是有限的。然而，在 2 年后，Kaplan-Meier 分析显示 iMRI 组的无进展生存率明显更高。iMRI 对生化缓解率和视力改善没有明显的益处。尽管使用 iMRI 辅助手术的手术时间较长，但并未显著增加并发症发生率。因此，如果特定中心具备该技术，作者建议常规使用高场 iMRI 进行垂体手术。
