This year, some 78,000 primary brain and other central nervous system (CNS) cancers will be diagnosed in the US alone. Researchers are actively developing new therapies for glioma, the most common type of primary brain tumor, but challenges remain in assessing whether patients are responding to treatment with the therapies.
To address these challenges, a team of Martinos Center researchers and colleagues have devised a deep learning algorithm that automatically measures tumor volume based on MR images, providing more rapid and more consistent treatment monitoring for patients. The researchers are now working to integrate the algorithm into the neuroradiology and neuro-oncology clinical workflows at Mass General.
“We are excited to develop new algorithms that can increase the reliability of challenging clinical workflows,” said Ken Chang, a graduate student in the Martinos Center and first author of a paper published in the journal Neuro-Oncology describing the algorithm. “Without accurate methods of treatment response assessment, it is difficult to know if a therapy for a given patient is effective or whether an alternative therapy should be considered. We believe the utilization of machine learning-based tools can help physicians provide the best care possible to patients.”
Using Deep Learning, Developers Address Limitations in Current Gold Standard Measurements of Treatment Response
In current practice, assessing a glioma patient’s response to treatment is based on manual measurements of tumor burden guided by Response Assessment in Neuro-Oncology (RANO) criteria. Using these criteria, clinicians can identify the response as “complete response,” “partial response,” “stable disease” or “progression,” based on specific imaging and clinical features. The RANO-based method offers a beneficial approach to treatment monitoring but is time-intensive and can vary depending on who performs the measurement. Also, to facilitate ease of use for the clinicians doing the reading, the approach relies on bi-directional diameter measures. Such measures, however, are unlikely to provide an accurate representation of the size of the tumor since gliomas are often irregular in shape. Volumetric measures would be more valuable for treatment monitoring purposes, but such measures would be impracticable for manual assessments of tumor burden because of the time and effort required.
The Martinos Center researchers therefore developed an algorithm for automatic measurement of tumor volumes as well as bi-directional measurement (an approach they call AutoRANO). This work grew out of recent advances in the field of deep learning, a type of artificial intelligence capable of performing complex tasks by using layers to learn progressively higher-level features from an image. The researchers built the algorithm using DeepNeuro, an open-source deep learning software package for neuroimaging developed by the Quantitative Translational Imaging in Medicine (QTIM) laboratory at the Martinos Center. In doing so, they worked closely with physicians from both Mass General and Brigham and Women’s Hospital to fully optimize it for clinical use.
In the Neuro-Oncology study, reported in June, the team validated the algorithm’s performance by comparing the automated measurements in two patient cohorts with manual measurements by experts. They first demonstrated the algorithm’s superiority in learning and performing brain extraction, a challenging preprocessing step often giving rise to difficulties downstream. Its strength in this area enabled robust tumor segmentation based on both FLAIR hyperintensity and contrast enhancement. The tool also performed well in automatically calculating RANO measurements from the contrast enhancement segmentations, showing high agreement with the manually generated tumor volumes. With these results and other findings, the study underscored the possible clinical utility of the algorithm in patients with glioma.
Clinical Workflows in Neuroradiology and Neuro-oncology to Benefit from Artificial Intelligence
The research team is now actively working with information technology engineers to add the algorithm into clinical workflows at Mass General for neuroradiology and neuro-oncology by the end of 2020. The goal is a tool with a user-friendly interface that seamlessly incorporates into the radiology picture archiving and communication system (PACS).
Once integrated into workflows, the algorithm has the potential to offer a host of benefits for physicians and patients. In addition to providing more reliable quantitative metrics to aid with clinical decision-making in treatment monitoring, it could also foster development of new treatments for patients with glioma within clinical trials. It could also work well with other automated tools currently under development in the QTIM laboratory, including an algorithm that can predict particular mutations in patients with glioma using MRI data. These mutations are associated with longer survival and could help guide treatment decisions.
All of which is good news for the field, and for the healthcare arena generally. “Deep learning will transform all aspects of radiology,” Chang says, “from image acquisition, to reconstruction, to diagnosis and clinical decision-making. Algorithms will automate many difficult tasks that are prone to human error, with clinicians and scientists in the driver’s seat. The integration of machine and human intelligence will improve the technical components of diagnosis and treatment. At the same time, integration will allow the physicians more flexibility to focus on the human aspects of care.”
In the photo above: QTIM lab directors Elizabeth Gerstner (left) and Jayashree Kalpathy-Cramer (center) and graduate student Ken Chang (right).