Artificial intelligence for segmentation and classification in lumbar spinal stenosis: an overview of current methods

European Spine Journal, vol. 34, pp. 1146–1155

Abstract

PURPOSE: Lumbar spinal stenosis (LSS) is a frequently occurring condition defined by narrowing of the spinal or nerve root canal due to degenerative changes. Physicians use MRI scans to determine the severity of stenosis, occasionally complementing it with X-ray or CT scans during the diagnostic work-up. However, manual grading of stenosis is time-consuming and induces inter-reader variability as a standardized grading system is lacking. Machine Learning (ML) has the potential to aid physicians in this process by automating segmentation and classification of LSS. However, it is unclear what models currently exist to perform these tasks. METHODS: A systematic review of literature was performed by searching the Cochrane Library, Embase, Emcare, PubMed, and Web of Science databases for studies describing an ML-based algorithm to perform segmentation or classification of the lumbar spine for LSS. Risk of bias was assessed through an adjusted version of the Newcastle-Ottawa Quality Assessment Scale that was more applicable to ML studies. Qualitative analyses were performed based on type of algorithm (conventional ML or Deep Learning (DL)) and task (segmentation or classification). RESULTS: A total of 27 articles were included of which nine on segmentation, 16 on classification and 2 on both tasks. The majority of studies focused on algorithms for MRI analysis. There was wide variety among the outcome measures used to express model performance. Overall, ML algorithms are able to perform segmentation and classification tasks excellently. DL methods tend to demonstrate better performance than conventional ML models. For segmentation the best performing DL models were U-Net based. For classification U-Net and unspecified CNNs powered the models that performed the best for the majority of outcome metrics. The number of models with external validation was limited. CONCLUSION: DL models achieve excellent performance for segmentation and classification tasks for LSS, outperforming conventional ML algorithms. However, comparisons between studies are challenging due to the variety in outcome measures and test datasets. Future studies should focus on the segmentation task using DL models and utilize a standardized set of outcome measures and publicly available test dataset to express model performance. In addition, these models need to be externally validated to assess generalizability.

Authors 7

1. Eduard J.A. Verheijen corresponding Aachen Department of Neurosurgery, Leiden University Medical Center

   Brigham and Women's Hospital · Harvard University · Leiden University Medical Center

   Affiliation as printed

   Computational Neuroscience Outcomes Center, Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, USA. e.j.a.verheijen@lumc.nl

   Department of Neurosurgery, Leiden University Medical Center, Albinusdreef 2, 2333ZA, Leiden, The Netherlands. e.j.a.verheijen@lumc.nl

   Computational Neuroscience Outcomes Center, Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, USA

2. T. Kapogiannis

   Brigham and Women's Hospital · Harvard University

   Affiliation as printed

   Computational Neuroscience Outcomes Center, Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, USA

3. D. Munteh

   Brigham and Women's Hospital · Harvard University

   Affiliation as printed

   Computational Neuroscience Outcomes Center, Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, USA

4. Jeremi Chabros

   Brigham and Women's Hospital · Harvard University

   Affiliation as printed

   Computational Neuroscience Outcomes Center, Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, USA

5. Marius Staring Aachen Department of Radiology, Leiden University Medical Center

   Leiden University Medical Center

   Affiliation as printed

   Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands

6. Timothy Richard Smith

   Brigham and Women's Hospital · Harvard University

   Affiliation as printed

   Computational Neuroscience Outcomes Center, Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, USA

7. Carmen L. A. Vleggeert-Lankamp Aachen Department of Neurosurgery, Leiden University Medical Center

   Leiden University Medical Center

   Affiliation as printed

   Department of Neurosurgery, Leiden University Medical Center, Albinusdreef 2, 2333ZA, Leiden, The Netherlands