Variations in the management of diffuse low-grade gliomas-A Scandinavian multicenter study.

BACKGROUND: Early extensive surgery is a cornerstone in treatment of diffuse low-grade gliomas (DLGGs), and an additional survival benefit has been demonstrated from early radiochemotherapy in selected "high-risk" patients. Still, there are a number of controversies related to DLGG management. The objective of this multicenter population-based cohort study was to explore potential variations in diagnostic work-up and treatment between treating centers in 2 Scandinavian countries with similar public health care systems. METHODS: Patients screened for inclusion underwent primary surgery of a histopathologically verified diffuse WHO grade II glioma in the time period 2012 through 2017. Clinical and radiological data were collected from medical records and locally conducted research projects, whereupon differences between countries and inter-hospital variations were explored. RESULTS: A total of 642 patients were included (male:female ratio 1:4), and annual age-standardized incidence rates were 0.9 and 0.8 per 100 000 in Norway and Sweden, respectively. Considerable inter-hospital variations were observed in preoperative work-up, tumor diagnostics, surgical strategies, techniques for intraoperative guidance, as well as choice and timing of adjuvant therapy. CONCLUSIONS: Despite geographical population-based case selection, similar health care organizations, and existing guidelines, there were considerable variations in DLGG management. While some can be attributed to differences in clinical implementation of current scientific knowledge, some of the observed inter-hospital variations reflect controversies related to diagnostics and treatment. Quantification of these disparities renders possible identification of treatment patterns associated with better or worse outcomes and may thus represent a step toward more uniform evidence-based care.

The Diagnostic Properties of Intraoperative Ultrasound in Glioma Surgery and Factors Associated with Gross Total Tumor Resection.

OBJECTIVE: In glioma operations, we sought to analyze sensitivity, specificity, and predictive values of intraoperative 3-dimensional ultrasound (US) for detecting residual tumor compared with early postoperative magnetic resonance imaging (MRI). Factors possibly associated with radiologic complete resection were also explored. METHODS: One hundred forty-four operations for diffuse supratentorial gliomas were included prospectively in an unselected, population-based, single-institution series. Operating surgeons answered a questionnaire immediately after surgery, stating whether residual tumor was seen with US at the end of resection and rated US image quality (e.g., good, medium, poor). Extent of surgical resection was estimated from preoperative and postoperative MRI. RESULTS: Overall specificity was 85% for "no tumor remnant" seen in US images at the end of resection compared with postoperative MRI findings. Sensitivity was 46%, but tumor remnants seen on MRI were usually small (median, 1.05 mL) in operations with false-negative US findings. Specificity was highest in low-grade glioma operations (94%) and lowest in patients who had undergone prior radiotherapy (50%). Smaller tumor volume and superficial location were factors significantly associated with gross total resection in a multivariable logistic regression analysis, whereas good ultrasound image quality did not reach statistical significance (P = 0.061). CONCLUSIONS: The specificity of intraoperative US is good, but sensitivity for detecting the last milliliter is low compared with postoperative MRI. Tumor volume and tumor depth are the predictors of achieving gross total resection, although ultrasound image quality was not.

Tumor Volume Assessment in Low-Grade Gliomas: A Comparison of Preoperative Magnetic Resonance Imaging to Coregistered Intraoperative 3-Dimensional Ultrasound Recordings.

BACKGROUND: Image guidance based on magnetic resonance imaging (MRI) and/or ultrasound (US) is widely used to aid decision making in glioma surgery, but tumor delineation based on these 2 modalities does not always correspond. OBJECTIVE: To analyze volumes of diffuse low-grade gliomas (LGGs) based on preoperative 3-D FLAIR MRIs compared to intraoperative 3-D US image recordings to quantitatively assess potential discrepancies between the 2 imaging modalities. METHODS: Twenty-three patients with supratentorial WHO grade II gliomas undergoing primary surgery guided by neuronavigation based on preoperative FLAIR MRI and navigated 3-D US were included. Manual volume segmentation was performed twice in 3-D Slicer version 4.0.0 to assess intrarater variabilities and compare modalities with regard to tumor volume. Factors possibly related to correspondence between MRI and US were also explored. RESULTS: In 20 out of 23 patients (87%), the LGG tumor volume segmented from intraoperative US data was smaller than the tumor volume segmented from the preoperative 3-D FLAIR MRI. The median difference between MRI and US volumes was 7.4 mL (range: -4.9-58.7 mL, P < .001) with US LGG volumes corresponding to a median of 74% (range: 42%-183%) of the MRI LGG volumes. However, there was considerable intraobserver variability for US volumes. The correspondence between MRI and US data was higher for astrocytomas (92%). CONCLUSION: The tumor volumes of LGGs segmented from intraoperative US images were most often smaller than the tumor volumes segmented from preoperative MRIs. There was a much better match between the 2 modalities in astrocytomas.