Evidence map›Paper›PMID 41668049›Full record

ArticleBMC medical imaging2026

Automated deep learning pipeline for measuring lumbar thecal sac AP diameter on mid-sagittal MR images.

Akash Nixon, Victor Rakesh Lazar, Saikiran Pendem, Karan Sekar, Senthil Kumar Aiyappan, Sundara Raja Perumal

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Article in BMC medical imaging, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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5 · Who and what money

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6 authors.

Akash NixonDepartment of Radio-Diagnosis, SRM Medical College Hospital and Research Centre, Faculty of Medicine and Health Sciences, SRM Institute of Science and Technology, Kattankulathur, Chengalpattu, Tamil Nadu, India.
Victor Rakesh LazarDepartment of Radio-Diagnosis, SRM Medical College Hospital and Research Centre, Faculty of Medicine and Health Sciences, SRM Institute of Science and Technology, Kattankulathur, Chengalpattu, Tamil Nadu, India. victorl@srmist.edu.in.
Saikiran PendemDepartment of Medical Imaging Technology, Manipal College of Health Professions, Manipal Academy of Higher Education, Manipal, India.
Karan SekarDepartment of Radio-Diagnosis, SRM Medical College Hospital and Research Centre, Faculty of Medicine and Health Sciences, SRM Institute of Science and Technology, Kattankulathur, Chengalpattu, Tamil Nadu, India.
Senthil Kumar AiyappanDepartment of Radio-Diagnosis, SRM Medical College Hospital and Research Centre, Faculty of Medicine and Health Sciences, SRM Institute of Science and Technology, Kattankulathur, Chengalpattu, Tamil Nadu, India.
Sundara Raja PerumalDepartment of Radio-Diagnosis, SRM Medical College Hospital and Research Centre, Faculty of Medicine and Health Sciences, SRM Institute of Science and Technology, Kattankulathur, Chengalpattu, Tamil Nadu, India.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

objectiveTo develop and validate an automated, disc-level deep learning pipeline for quantitative measurement of anteroposterior (AP) thecal sac diameter on mid-sagittal lumbar T2-weighted MRI. MATERIALS AND

methodsIn this retrospective study, 511 mid-sagittal lumbar T2 MRI examinations were included after screening 758 cases and applying predefined exclusions. The workflow combined YOLOv8 oriented bounding boxes (OBB) for disc-level localization and orientation estimation, homography-based ROI warping, Attention U-Net segmentation, and skeleton-based AP diameter computation in millimeters using DICOM pixel spacing. Validation was performed on internal (50) and external (50; RSNA 2024 lumbar dataset) cohorts with two radiologists providing the reference standard.

resultInter-reader agreement was excellent (ICC (2, 1) = 0.967; 711 paired measurements). Against the reader-mean reference, the pipeline achieved an overall MAE of 0.994 mm (711 disc-level measurements). Internal validation showed MAE 0.909 mm (357 measurements) and external validation MAE 1.079 mm (354 measurements). Severity-wise MAE remained ~ 1 mm (mild 0.930 mm; moderate 1.234 mm; severe 1.038 mm). Automatic disc-level labeling was performed, and OBB-derived orientation significantly improved AP measurement-line validity versus axis-aligned detection (acceptable lines 99.02% vs. 77.64%).

conclusionAn orientation-aware YOLOv8-OBB + Attention U-Net pipeline enables automated, disc-level AP thecal sac diameter quantification on mid-sagittal lumbar MRI with ~ 1 mm error relative to expert reference, supporting standardized morphometric reporting and measurement-driven assessment of lumbar stenosis.

Indexed as

Deep LearningLumbar VertebraeMagnetic Resonance ImagingHumansReproducibility of ResultsRetrospective StudiesAttention U-NetAutomated measurementDeep learningLumbar spinal stenosisMorphometricsMRIThecal sacYOLOv8-OBB

Identifiers

PMID41668049
PMCPMC12990583

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