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Narrowing of the lumbar spinal canal, or lumbar stenosis (LS), may cause debilitating radicular pain or muscle weakness. It is the most frequent indication for spinal surgery in the elderly population. Modern diagnosis relies on magnetic resonance imaging and its inherently subjective interpretation. Diagnostic rigor, accuracy, and speed may be improved by automation. In this work, we aimed to determine whether a deep-U-Net ensemble trained to segment spinal canals on a heterogeneous mix of clinical data is comparable to radiologists' segmentation of these canals in patients with LS. The deep U-nets were trained on spinal canals segmented by physicians on 100 axial T2 lumbar magnetic resonance imaging selected randomly from our institutional database. Test data included a total of 279 elderly patients with LS that were separate from the training set. Machine-generated segmentations (MA) were qualitatively similar to expert-generated segmentations (M E1 , M E2). Machine- and expert-generated segmentations were quantitatively similar, as evidenced by Dice scores (MA vs. M E1 : 0.88 ± 0.04, MA vs. M E2 : 0.89 ± 0.04), the Hausdorff distance (MA vs. M E1 : 11.7 mm ± 13.8, MA vs. M E2 : 13.1 mm ± 16.3), and average surface distance (MAvs. M E1 : 0.18 mm ± 0.13, MA vs. M E2 0.18 mm ± 0.16) metrics. These metrics are comparable to inter-rater variation (M E1 vs. M E2 Dice scores: 0.94 ± 0.02, the Hausdorff distances: 9.3 mm ± 15.6, average surface distances: 0.08 mm ± 0.09). We conclude that machine learning algorithms can segment lumbar spinal canals in LS patients, and automatic delineations are both qualitatively and quantitatively comparable to expert-generated segmentations. [ABSTRACT FROM AUTHOR]

To assess volumetric changes in the spinal cord at the cervicomedullary junction, diameter of the cervicomedullary cord, and width of the brainstem following posterior fossa decompression (PFD). A retrospective analysis of adult patients with Chiari malformation who underwent PFD was performed. Segmentations were done on clinical quality T2-weighted cervical magnetic resonance images obtained before and after decompression using ITK-SNAP. Volumes of neural tissue within the cervicomedullary junction were evaluated from 10 mm cranial to the medullary beak to the cervical spinal cord at the level of the caudal endplate of the second cervical vertebra. The diameter of the cervicomedullary cord was calculated perpendicular to the spinal cord. The width of the brainstem was measured perpendicular to the clivus at the level of the basion. Twenty adult patients, a mean age of 49.55 years, were included. The cervical cord increased in volume by 13 mm3 to 338 mm3, with an average increase of 155 mm3 (P -value of 0.00002). The diameter of the cervicomedullary cord increased 10.30% 7 mm superior to the beak (P -value of 0.00074), 11.49% at the apex of the beak (P -value of 0.00082), 8.29% 7 mm inferior to the beak (P -value of 0.00075), and the brainstem increased 14.46% perpendicular to the clivus (P -value of 0.00109). The spinal cord at the inferior aspect of the C3 vertebra changed insignificantly (P -value of 0.10580). The volume of the cervical cord at the cervical-medullary junction, width of the cervicomedullary cord, and diameter of the brainstem increase following PFD. [ABSTRACT FROM AUTHOR]