Radiology reporting of low-grade glioma growth underestimates tumor expansion
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An important aspect in the management of patients with diffuse low-grade gliomas (LGGs) involves monitoring the lesions via serial magnetic resonance imaging (MRI). However, radiological interpretations of LGG interval scans are often qualitative and thus difficult to use clinically.
To contextualize these assessments, we retrospectively compared radiological interpretations of LGG growth or stability to volume change measured by manual segmentation. Tumor diameter was also measured in one, two, and three dimensions to evaluate reported methods for assessment of glioma progression, including RECIST criteria, Macdonald/RANO criteria, and mean tumor diameter/ellipsoid method.
Tumors evaluated as stable by radiologists grew a median volume of 5.1 mL (11.1%) relative to the comparison scan, and those evaluated as having grown had a median volume increase of 13.3 mL (23.7%). Diameter-based measurements corresponded well but tended to overestimate gold standard segmented volumes. In addition, agreement with segmented volume measurements improved from 17.6 ± 8.0 to 4.5 ± 5.8 to 3.9 ± 3.6 mm for diameter and from 104.0 ± 96.6 to 25.3 ± 36.8 to 15.9 ± 21.3 mL for volume with radiological measurements in one, two, and three dimensions, respectively. Measurement overestimation increased with tumor size.
Given accumulating evidence that LGG volume and growth are prognostic factors, there is a need for objective lesion measurement. Current radiological reporting workflows fail to appreciate and communicate the true expansion of LGGs. While volumetric analysis remains the gold standard for assessment of growth, careful diametric measurements in three dimensions may be an acceptable alternative.
KeywordsLow-grade glioma Neuro-oncology MRI Longitudinal growth quantification
We thank Dr. David R. Macdonald, a neuro-oncologist, for his expertise and insight during the course of this study.
C.G. and S.E.K. received research scholarships from the Summer Research Training Program at the Schulich School of Medicine and Dentistry at Western University and the Mach-Gaensslen Foundation of Canada. J.C.L. is funded through the Western University Clinical Investigator Program accredited by the Royal College of Physicians and Surgeons of Canada and a Canadian Institutes of Health Research Frederick Banting and Charles Best Canada Graduate Doctoral Award Scholarship.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All procedures performed in studies involving human participants were conducted in accordance with the ethical standards of the institutional research committee, Western University’s Research Ethics Board, and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. For this type of study, formal consent is not required.
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