Purpose

Extent of resection of low grade glioma (LGG) is an important prognostic variable, and may influence decisions regarding adjuvant therapy in certain patient populations. Immediate postoperative magnetic resonance image (MRI) is the mainstay for assessing residual tumor. However, previous studies have suggested that early postoperative MRI fluid-attenuated inversion recovery (FLAIR) (within 48 h) may overestimate residual tumor volume in LGG. Intraoperative magnetic resonance imaging (iMRI) without subsequent resection may more accurately assess residual tumor. Consistency in MRI techniques and utilization of higher magnet strengths may further improve both comparisons between MRI studies performed at different time points as well as the specificity of MRI findings to identify residual tumor. To evaluate the utility of 3 T iMRI in the imaging of LGG, we volumetrically analyzed intraoperative, early, and late (~ 3 months after surgery) postoperative MRIs after resection of LGG.

Methods

A total of 32 patients with LGG were assessed retrospectively. Residual tumor was defined as hyperintense T2 signal on FLAIR. Volumetric assessment was performed with intraoperative, early, and late postoperative FLAIR via TeraRecon iNtuition.

Results

Perilesional FLAIR parenchymal abnormality volumes were significantly different comparing intraoperative and early postoperative MRI (2.17 ± 0.45 cm³ vs. 5.47 ± 1.07 cm³, respectively (p = 0.0002)). A significant difference of perilesional FLAIR parenchymal abnormality volumes was also found comparing early and late postoperative MRI (5.47 ± 1.07 cm³ vs. 3.22 ± 0.64 cm³, respectively (p = 0.0001)). There was no significant difference between intraoperative and late postoperative Perilesional FLAIR parenchymal abnormality volumes.

Conclusions

Intraoperative 3 T MRI without further resection appears to better reflect the volume of residual tumor in LGG compared with early postoperative 3 T MRI. Early postoperative MRI may overestimate residual tumor. As such, intraoperative MRI performed after completion of tumor resection may be more useful for making decisions regarding adjuvant therapy.

中文翻译：

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与术后早期 MRI 相比，术中 3 T MRI 与残留病变范围的相关性更高

目的

低级别胶质瘤 (LGG) 的切除范围是一个重要的预后变量，可能会影响某些患者群体的辅助治疗决策。术后即刻磁共振图像（MRI）是评估残留肿瘤的主要手段。然而，先前的研究表明，术后早期 MRI 流体衰减反转恢复（FLAIR）（48 小时内）可能会高估 LGG 中的残余肿瘤体积。没有后续切除的术中磁共振成像 (iMRI) 可以更准确地评估残留肿瘤。MRI 技术的一致性和更高磁体强度的利用可以进一步改善在不同时间点进行的 MRI 研究之间的比较以及 MRI 发现识别残留肿瘤的特异性。

方法

回顾性评估了 32 例 LGG 患者。残留肿瘤定义为 FLAIR 上的高信号 T2 信号。通过 TeraRecon iNtuition 对术中、术后早期和晚期 FLAIR 进行体积评估。

结果

与术中和术后早期 MRI 相比，病灶周围 FLAIR 实质异常体积显着不同（分别为 2.17 ± 0.45 cm ³和 5.47 ± 1.07 cm ³（p = 0.0002））。对比术后早期和晚期 MRI，还发现病灶周围 FLAIR 实质异常体积存在显着差异（分别为 5.47 ± 1.07 cm ³和 3.22 ± 0.64 cm ³（p = 0.0001））。术中和术后晚期周围FLAIR实质异常体积之间没有显着差异。

结论

与术后早期 3 T MRI 相比，无需进一步切除的术中 3 T MRI 似乎能更好地反映 LGG 中残留肿瘤的体积。术后早期 MRI 可能会高估残留肿瘤。因此，在完成肿瘤切除后进行的术中 MRI 可能更有助于做出有关辅助治疗的决定。