Dual-Energy CT, Virtual Non-Calcium Bone Marrow Imaging of the Spine: An AI-Assisted, Volumetric Evaluation of a Reference Cohort with 500 CT Scans.

Philipp Fervers,Simon Lennartz,Gregor Pahn,Thorsten Persigehl,Florian Fervers,Robert Peter Reimer,David Zopfs,Jonathan Kottlors,Miriam Rinneburger,Nils Große Hokamp,Mathilda Weisthoff,David Maintz

doi:10.3390/diagnostics12030671

Abstract

Virtual non-calcium (VNCa) images from dual-energy computed tomography (DECT) have shown high potential to diagnose bone marrow disease of the spine, which is frequently disguised by dense trabecular bone on conventional CT. In this study, we aimed to define reference values for VNCa bone marrow images of the spine in a large-scale cohort of healthy individuals. DECT was performed after resection of a malignant skin tumor without evidence of metastatic disease. Image analysis was fully automated and did not require specific user interaction. The thoracolumbar spine was segmented by a pretrained convolutional neuronal network. Volumetric VNCa data of the spine’s bone marrow space were processed using the maximum, medium, and low calcium suppression indices. Histograms of VNCa attenuation were created for each exam and suppression setting. We included 500 exams of 168 individuals (88 female, patient age 61.0 ± 15.9). A total of 8298 vertebrae were segmented. The attenuation histograms’ overlap of two consecutive exams, as a measure for intraindividual consistency, yielded a median of 0.93 (IQR: 0.88–0.96). As our main result, we provide the age- and sex-specific bone marrow attenuation profiles of a large-scale cohort of individuals with healthy trabecular bone structure as a reference for future studies. We conclude that artificial-intelligence-supported, fully automated volumetric assessment is an intraindividually robust method to image the spine’s bone marrow using VNCa data from DECT.

Highlights

Introduction iationsComputed tomography (CT) of the chest and abdomen is the recommended and most frequently conducted imaging procedure for the staging of malignant disease [1–5]
Virtual non-calcium (VNCa) images postprocessed from dual-energy computed tomography (DECT) data have shown the potential to close the diagnostic gap and suggested similar capabilities to magnetic resonance imaging (MRI) and positron emission tomography CT (PET/CT) for detection of spinal metastasis [12]
To facilitate the clinical transition of reports on VNCa performance in diagnosing occult malignant disease of the spine by conventional CT, this study sought to provide reference values for VNCa attenuation of the spine’s bone marrow among healthy individuals across different age groups and sexes, which are missing in literature to date

Summary

Introduction

Computed tomography (CT) of the chest and abdomen is the recommended and most frequently conducted imaging procedure for the staging of malignant disease [1–5]. Due to rapid scanning times, good patient acceptance, and few contraindications, it is among the most commonly performed imaging procedures in the Western world, with ever-rising numbers [6–8]. A well-known limitation of contrast-enhanced CT, compared with, for instance, magnetic resonance imaging (MRI), positron emission tomography CT (PET/CT), or bone scintigraphy, is its limited capacity to accurately diagnose metastatic disease of the spine. The dense trabecular structure of vertebral bodies impedes the assessment of underlying, malignant tumors without dominant osteolytic or osteoblastic components. In a recent meta-analysis, conventional CT yielded a pooled sensitivity and specificity of. 0.77 and 0.83 for only the detection of spine metastasis [9].

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