Single shot zonal oblique multislice SE-EPI diffusion-weighted imaging with low to ultra-high b-values for the differentiation of benign and malignant vertebral spinal fractures

Andreas Gutzeit,David Czell,Sabine Sartoretti-Schefer,Elisabeth Sartoretti,Árpád Schwenk,Christoph A Binkert,Luuk Van Smoorenburg,Manoj Mannil,Alex Alfieri,Thomas Sartoretti,Barbara Eichenberger,Michael Wyss

doi:10.1016/j.ejro.2021.100377

Abstract

PurposeTo investigate the diagnostic yield of low to ultra-high b-values for the differentiation of benign from malignant vertebral fractures using a state-of-the-art single-shot zonal-oblique-multislice spin-echo echo-planar diffusion-weighted imaging sequence (SShot ZOOM SE-EPI DWI). Materials and Methods66 patients (34 malignant, 32 benign) were examined on 1.5 T MR scanners. ADC maps were generated from b-values of 0,400; 0,1000 and 0,2000s/mm2. ROIs were placed into the fracture of interest on ADC maps and trace images and into adjacent normal vertebral bodies on trace images. The ADC of fractures and the Signal-Intensity-Ratio (SIR) of fractures relative to normal vertebral bodies on trace images were considered quantitative metrics. The appearance of the fracture of interest was graded qualitatively as iso-, hypo-, or hyperintense relative to normal vertebrae. ResultsADC achieved an area under the curve (AUC) of 0.785/0.698/0.592 for b = 0,400/0,1000/0,2000s/mm2 ADC maps respectively. SIR achieved an AUC of 0.841/0.919/0.917 for b = 400/1000/2000s/mm2 trace images respectively. In qualitative analyses, only b = 2000s/mm2 trace images were diagnostically valuable (sensitivity:1, specificity:0.794). Machine learning models incorporating all qualitative and quantitative metrics achieved an AUC of 0.95/0.98/0.98 for b-values of 400/1000/2000s/mm2 respectively. The model incorporating only qualitative metrics from b = 2000s/mm2 achieved an AUC of 0.97. ConclusionBy using quantitative and qualitative metrics from SShot ZOOM SE-EPI DWI, benign and malignant vertebral fractures can be differentiated with high diagnostic accuracy. Importantly qualitative analysis of ultra-high b-value images may suffice for differentiation as well.

Highlights

Both benign osteoporotic compression fractures as well as pathologic metastatic vertebral fractures due to vertebral metastases are common conditions, especially in elderly patients.In clinical routine, radiologists have to differentiate these two Abbreviations: MRI, Magnetic Resonance Imaging; diffusionweighted imaging (DWI), Diffusion Weighted Imaging; apparent diffusion coefficient (ADC), Apparent Diffusion Coefficient; single shot (SShot), Single Shot; multi shot (MShot), Multi Shot; spin-echo echo-planar-imaging (SE-EPI), Spin Echo – Echo Planar Imaging; field of view (FOV), Field of View; zonal oblique multislice (ZOOM), Zonal Oblique Multislice; STIR, Short Tau Inversion Recovery; PET-CT, Positron Emission Tomography – Computed Tomography; dual energy x-ray absorp tiometry (DXA), Dual Energy X-Ray Absorptiometry; T1w, T1-weighted; T2w, T2-weighted; TSE, Turbo Spin Echo; SI, Signal Intensity; SIR, Signal Intensity Ratio; area under the curve (AUC), Area Under the Curve; receiver operating charac teristics (ROC), Receiver Operating Characteristics.European Journal of Radiology Open 8 (2021) 100377 entities as this paves the subsequent therapeutic process
We showed that when considering metrics individually, quantitative and qualitative metrics derived from DWI trace images exhibit an improved discriminative performance compared to metrics derived from ADC maps
The SIRs as derived from b = 1000 and b = 2000 s/mm2 DWI trace images individually allowed for an excellent separa tion of these two entities with the AUC reaching 0.92

Summary

Introduction

Both benign osteoporotic compression fractures as well as pathologic metastatic vertebral fractures due to vertebral metastases are common conditions, especially in elderly patients.In clinical routine, radiologists have to differentiate these two Abbreviations: MRI, Magnetic Resonance Imaging; DWI, Diffusion Weighted Imaging; ADC, Apparent Diffusion Coefficient; SShot, Single Shot; MShot, Multi Shot; SE-EPI, Spin Echo – Echo Planar Imaging; FOV, Field of View; ZOOM, Zonal Oblique Multislice; STIR, Short Tau Inversion Recovery; PET-CT, Positron Emission Tomography – Computed Tomography; DXA, Dual Energy X-Ray Absorptiometry; T1w, T1-weighted; T2w, T2-weighted; TSE, Turbo Spin Echo; SI, Signal Intensity; SIR, Signal Intensity Ratio; AUC, Area Under the Curve; ROC, Receiver Operating Characteristics.European Journal of Radiology Open 8 (2021) 100377 entities as this paves the subsequent therapeutic process. Radiologists have to differentiate these two Abbreviations: MRI, Magnetic Resonance Imaging; DWI, Diffusion Weighted Imaging; ADC, Apparent Diffusion Coefficient; SShot, Single Shot; MShot, Multi Shot; SE-EPI, Spin Echo – Echo Planar Imaging; FOV, Field of View; ZOOM, Zonal Oblique Multislice; STIR, Short Tau Inversion Recovery; PET-CT, Positron Emission Tomography – Computed Tomography; DXA, Dual Energy X-Ray Absorptiometry; T1w, T1-weighted; T2w, T2-weighted; TSE, Turbo Spin Echo; SI, Signal Intensity; SIR, Signal Intensity Ratio; AUC, Area Under the Curve; ROC, Receiver Operating Characteristics. Recent endeavors in improving the differentiation of benign and malignant vertebral fractures with MRI have focused on diffusionweighted imaging (DWI). Investigators have thereby proposed both qualitative and quantitative approaches based on trace images and apparent diffusion coefficient (ADC) maps in an effort to improve the differentiation of these entities [5,7]

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