An automated algorithm for the detection of cortical interruptions and its underlying loss of trabecular bone; a reproducibility study

M Peters,R Weijers,S K Boyd,C Barnabe,A Scharmga,P Geusens,J De Jong,K S Stok,J Van Den Bergh,B Van Rietbergen,D Loeffen,A Van Tubergen

doi:10.1186/s12880-018-0255-7

Abstract

BackgroundWe developed a semi-automated algorithm that detects cortical interruptions in finger joints using high-resolution peripheral quantitative computed tomography (HR-pQCT), and extended it with trabecular void volume measurement. In this study we tested the reproducibility of the algorithm using scan/re-scan data.MethodsSecond and third metacarpophalangeal joints of 21 subjects (mean age 49 (SD 11) years, 17 early rheumatoid arthritis and 4 undifferentiated arthritis, all diagnosed < 1 year ago) were imaged twice by HR-pQCT on the same day with repositioning between scans. The images were analyzed twice by one operator (OP1) and once by an additional operator (OP2), who independently corrected the bone contours when necessary. The number, surface and volume of interruptions per joint were obtained. Intra- and inter-operator reliability and intra-operator reproducibility were determined by intra-class correlation coefficients (ICC). Intra-operator reproducibility errors were determined as the least significant change (LSCSD).ResultsPer joint, the mean number of interruptions was 3.1 (SD 3.6), mean interruption surface 4.2 (SD 7.2) mm2, and mean interruption volume 3.5 (SD 10.6) mm3 for OP1. Intra- and inter-operator reliability was excellent for the cortical interruption parameters (ICC ≥0.91), except good for the inter-operator reliability of the interruption surface (ICC = 0.70). The LSCSD per joint was 4.2 for the number of interruptions, 5.8 mm2 for interruption surface, and 3.2 mm3 for interruption volume.ConclusionsThe algorithm was highly reproducible in the detection of cortical interruptions and their volume. Based on the LSC findings, the potential value of this algorithm for monitoring structural damage in the joints in early arthritis patients needs to be tested in clinical studies.

Highlights

We developed a semi-automated algorithm that detects cortical interruptions in finger joints using high-resolution peripheral quantitative computed tomography (HR-pQCT), and extended it with trabecular void volume measurement
Visual assessment Cortical interruptions detected by the algorithm based on the corrected contours of Operator 1 (OP1) and Operator 2 (OP2) on the first scan and corrected contours of OP1 on the second scan are visualized in 3D, and visualized on corresponding 2D grayscale images (Fig. 4)
The extended algorithm for detection of cortical interruptions and their volume, and the assessment of the bone density and micro-structure parameters on High-resolution peripheral quantitative CT (HRpQCT) is highly reproducible in finger joints of early arthritis patients

Summary

Introduction

We developed a semi-automated algorithm that detects cortical interruptions in finger joints using high-resolution peripheral quantitative computed tomography (HR-pQCT), and extended it with trabecular void volume measurement. Multiple studies have reported results on the visual inspection of the presence, number and size of interruptions with underlying trabecular bone voids in finger joints of patients with RA using HR-pQCT [12,13,14,15,16,17,18,19,20,21,22]. We showed that the inter-operator reliability is fair when visually scoring smaller cortical interruptions [25]

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