Frequency and Prognostic Relevance of Volumetric MRI Changes in Contrast- and Non-Contrast-Enhancing Tumor Compartments between Surgery and Radiotherapy of IDHwt Glioblastoma

Abstract

In newly diagnosed IDH-wildtype glioblastoma, the frequency and prognostic relevance of tumor regrowth between resection and the initiation of adjuvant radiochemotherapy are unclear. In this retrospective single-center study we included 64 consecutive cases, for whom magnetic resonance imaging (MRI) was available for both the volumetric assessment of the extent of resection immediately after surgery as well as the volumetric target delineation before the initiation of adjuvant radiochemotherapy (time interval: 15.5 ± 1.9 days). Overall, a median new contrast-enhancement volume was seen in 21/64 individuals (33%, 1.5 ± 1.5 cm3), and new non-contrast lesion volume in 18/64 patients (28%, 5.0 ± 2.3 cm3). A multidisciplinary in-depth review revealed that new contrast-enhancement was either due to (I) the progression of contrast-enhancing tumor remnants in 6/21 patients or (II) distant contrast-enhancing foci or breakdown of the blood–brain barrier in previously non-contrast-enhancing tumor remnants in 5/21 patients, whereas it was unspecific or due to ischemia in 10/21 patients. For non-contrast-enhancing lesions, three of eighteen had progression of non-contrast-enhancing tumor remnants and fifteen of eighteen had unspecific changes or changes due to ischemia. There was no significant association between findings consistent with tumor regrowth and a less favorable outcome (overall survival: 14 vs. 19 months; p = 0.423). These findings support the rationale that analysis of the postsurgical remaining tumor-volume for prognostic stratification should be carried out on immediate postoperative MRI (<72 h), as unspecific changes are common. However, tumor regrowth including distant foci may occur in a subset of IDH-wildtype glioblastoma patients diagnosed per WHO 2021 classification. Thus, MRI imaging prior to radiotherapy should be obtained to adjust radiotherapy planning accordingly.

How to evaluate extent of resection in diffuse gliomas: from standards to new methods

“…The use of digital contrast-enhanced T1 subtraction maps may further facilitate detailed quantification of CE-tumor volumes but needs to be validated in the setting of extent of resection assessment after glioma surgery [19]. For gliomas presenting with CE on preoperative imaging, MRI is recommended to be obtained within 72 h following resection to ameliorate the risk of mistakenly interpret surgically induced CE as residual tumor [12,23 ▪ ]. DWI sequences are needed to be reviewed in this setting to distinguish between nonspecific areas of contrast-enhancement due to ischemia and CE tumor portions on postcontrast T1-weighted sequences (Fig.…”

“…DWI sequences are needed to be reviewed in this setting to distinguish between nonspecific areas of contrast-enhancement due to ischemia and CE tumor portions on postcontrast T1-weighted sequences (Fig. 1a) [12,23 ▪ ].…”

Preclinical evaluation of Mito-LND, a targeting mitochondrial metabolism inhibitor, for glioblastoma treatment

“…Glioblastoma (GBM) is the most common primary intracranial malignant brain tumor [ 1 ]. Currently, the standard therapy of GBM is still operation for maximum resection of the tumor, accompanied by postoperative adjuvant radiotherapy and chemotherapy [ 2 ]. However, due to invasion, the postoperative recurrence rate is high, and the prognosis of patients is poor [ 3 ].…”