Objective Treatment response assessment in high-grade gliomas uses contrast enhanced T1-weighted MRI, but is unreliable. Novel advanced MRI techniques have been studied, but the accuracy is not well known. Therefore, we performed a systematic meta-analysis to assess the diagnostic accuracy of anatomical and advanced MRI for treatment response in high-grade gliomas. Methods Databases were searched systematically. Study selection and data extraction were done by two authors independently. Meta-analysis was performed using a bivariate random effects model when ≥5 studies were included. Results Anatomical MRI (five studies, 166 patients) showed a pooled sensitivity and specificity of 68% (95%CI 51–81) and 77% (45–93), respectively. Pooled apparent diffusion coefficients (seven studies, 204 patients) demonstrated a sensitivity of 71% (60–80) and specificity of 87% (77–93). DSC-perfusion (18 studies, 708 patients) sensitivity was 87% (82–91) with a specificity of 86% (77–91). DCE-perfusion (five studies, 207 patients) sensitivity was 92% (73–98) and specificity was 85% (76–92). The sensitivity of spectroscopy (nine studies, 203 patients) was 91% (79–97) and specificity was 95% (65–99). Conclusion Advanced techniques showed higher diagnostic accuracy than anatomical MRI, the highest for spectroscopy, supporting the use in treatment response assessment in high-grade gliomas. Key points • Treatment response assessment in high-grade gliomas with anatomical MRI is unreliable • Novel advanced MRI techniques have been studied, but diagnostic accuracy is unknown • Meta-analysis demonstrates that advanced MRI showed higher diagnostic accuracy than anatomical MRI • Highest diagnostic accuracy for spectroscopy and perfusion MRI • Supports the incorporation of advanced MRI in high-grade glioma treatment response assessment

Background High-grade gliomas are the most common primary brain tumours. Pseudoprogression describes the false appearance of radiation-induced progression on MRI. A distinction should be made from true tumour progression to correctly plan treatment. However, there is wide variation of reported pseudoprogression. We thus aimed to establish the incidence of pseudoprogression and tumour progression in high-grade glioma patients with a systematic review and meta-analysis. Methods We searched PubMed, Embase and Web of Science on the incidence of pseudoprogression and tumour progression in adult high-grade glioma patients from 2005, the latest on 8 October 2014. Histology or imaging follow-up was used as reference standard. Extracted data included number of patients with worsening of imaging findings on T1 postcontrast or T2/FLAIR, pseudoprogression and tumour progression. Study quality was assessed. Heterogeneity was tested with I ². Pooling of the results was done with random models using Metaprop in STATA (StataCorp. Stata Statistical Software. College Station, TX: StataCorp LP). Results We identified 73 studies. MRI progression occurred in 2603 patients. Of these, 36% (95% confidence interval [CI] 33–40%) demonstrated pseudoprogression, 60% (95%CI 56–64%) tumour progression and unknown outcome was present in the remaining 4% of the patients (range 1–37%). Conclusion This meta-analysis demonstrated for the first time a notably high pooled incidence of pseudoprogression in patients with a form of progression across the available literature. This highlighted the full extent of the problem of the currently conventional MRI-based Response Assessment in Neuro-Oncology (RANO) criteria for treatment evaluation in high-grade gliomas. This underscores the need for more accurate treatment evaluation using advanced imaging to improve diagnostic accuracy and therapeutic approach.

Background: Sarcopenia might function as an indicator for frailty, and as such as a risk factor for the development of postoperative complications. The aim of this study was to meta‐analyse the relation between preoperative sarcopenia and the development of severe postoperative complications in patients undergoing oncological surgery.Methods: PubMed and Embase databases were systematically searched from inception until May 2018. Included were studies reporting on the incidence of severe postoperative complications and radiologically determined preoperative sarcopenia. Studies reporting the skeletal muscle as a continuous variable only were excluded. Data were extracted independently by two reviewers. Random effect meta‐analyses were applied to estimate the pooled odds ratio (OR) with 95% confidence intervals (95% CI) for severe postoperative complications, defined as Clavien‐Dindo grade ≥3, including 30‐day mortality. Heterogeneity was evaluated with I² testing. Analyses were performed overall and stratified by measurement method, tumour location and publication date.Results: A total of 1924 citations were identified, and 53 studies (14 295 patients) were included in the meta‐analysis. When measuring the total skeletal muscle area, 43% of the patients were sarcopenic, versus 33% when measuring the psoas area. Severe postoperative complications were present in 20%, and 30‐day mortality was 3%. Preoperative sarcopenia was associated with an increased risk of severe postoperative complications (OR_pooled: 1.44, 95% CI: 1.24–16.8, P<0.001, I²=55%) and 30‐day mortality (OR_pooled: 2.15, 95% CI: 1.46–3.17, P<0.001, I²=14%). A low psoas mass was a stronger predictor for severe postoperative complications compared with a low total skeletal muscle mass (OR_pooled: 2.06, 95% CI: 1.37–3.09, OR_pooled: 1.32, 95% CI: 1.14–1.53, respectively) and 30‐day mortality [OR_pooled: 6.17 (95% CI: 2.71–14.08, OR_pooled: 1.80 (95% CI: 1.24–2.62), respectively]. The effect was independent of tumour location and publication date.Conclusions: The presence of low psoas mass prior to surgery, as an indicator for sarcopenia, is a common phenomenon and is a strong predictor for the development of postoperative complications. The presence of low total skeletal muscle mass, which is even more frequent, is a less informative predictor for postoperative complications and 30‐day mortality. The low heterogeneity indicates that the finding is consistent over studies. Nevertheless, the value of sarcopenia relative to other assessments such as frailty screening is not clear. Research is needed in order to determine the place of sarcopenia in future preoperative risk stratification.

Treatment evaluation of patients with glioblastomas is important to aid in clinical decisions. Conventional MRI with contrast is currently the standard method, but unable to differentiate tumor progression from treatment‐related effects. Pseudoprogression appears as new enhancement, and thus mimics tumor progression on conventional MRI. Contrarily, a decrease in enhancement or edema on conventional MRI during antiangiogenic treatment can be due to pseudoresponse and is not necessarily reflective of a favorable outcome. Neovascularization is a hallmark of tumor progression but not for posttherapeutic effects. Perfusion‐weighted MRI provides a plethora of additional parameters that can help to identify this neovascularization. This review shows that perfusion MRI aids to identify tumor progression, pseudoprogression, and pseudoresponse. The review provides an overview of the most applicable perfusion MRI methods and their limitations. Finally, future developments and remaining challenges of perfusion MRI in treatment evaluation in neuro‐oncology are discussed.Level of Evidence: 3Technical Efficacy: Stage 4J. Magn. Reson. Imaging 2019;49:11–22.

Background: Post-treatment high-grade gliomas are usually monitored with contrast-enhanced MRI, but its diagnostic accuracy is limited as it cannot adequately distinguish between true tumor progression and treatment-related changes. According to recent response assessment in neuro-oncology (RANO) recommendations PET overcomes this limitation. However, it is currently unknown which tracer yields the best results. Therefore, a systematic review and meta-analysis were performed to compare the diagnostic accuracy of the different PET tracers in differentiating tumor progression from treatment-related changes in high-grade glioma patients. Methods: Pubmed, Web of Science and Embase were searched systematically. Study selection, data extraction and quality assessment were performed independently by two authors. Meta-analysis was performed using a bivariate random effects model when ≥ 5 studies were included. Results: 39 studies (11 tracers) were included in the systematic review. ¹⁸F-FDG (12 studies, 171 lesions) showed a pooled sensitivity and specificity of 84% (95%CI 72-92) and 84% (69-93), respectively. ¹⁸F-FET (7 studies, 172 lesions) demonstrated a sensitivity of 90% (81-95) and specificity of 85% (71-93). ¹¹C-MET (8 studies, 151 lesions) sensitivity was 93% (80-98) and specificity was 82% (68-91). The number of included studies for the other tracers were too low to combine, but sensitivity and specificity ranged between 93-100% and 0-100% for ¹⁸F-FLT, 85-100% and 72-100% for ¹⁸F-FDOPA and 100% and 70-88% for ¹¹C-CHO, respectively. Conclusion: ¹⁸F-FET and ¹¹C-MET, both amino-acid tracers, showed a comparable higher sensitivity than ¹⁸F-FDG in the differentiation between tumor progression and treatment-related changes in high-grade glioma patients. The evidence for other tracers is limited, thus ¹⁸F-FET and ¹¹C-MET are preferred when available. Our results support the incorporation of amino-acid PET tracers for the treatment evaluation of high-grade gliomas.