Technical Developments: Zero Echo Time Imaging of the Shoulder: Enhanced Osseous Detail by Using MR Imaging

Abstract

Purpose To determine the intermodality agreement of morphologic grading and clinically relevant quantitative measurements between computed tomography (CT) and zero echo time (ZTE) magnetic resonance (MR) imaging of the shoulder. The primary objective was to demonstrate the clinical applicability of ZTE in osseous shoulder imaging. Materials and Methods Thirty-four patients undergoing standard-of-care (SOC) MR imaging with concomitant CT were enrolled in this institutional review board-approved study. ZTE images were acquired after SOC MR imaging. Glenoid morphology (version, vault depth, erosion), injury or disease (osteoarthritis, Bankart and Hill-Sachs lesions, subchondral cysts), and evidence of prior surgery were graded or measured. κ Values, intraclass correlation coefficients (ICCs), and Bland-Altman limits of agreement were used to establish agreement. Qualitative comparison of osseous findings was performed between ZTE and SOC MR imaging. Results Binary classification and nominal/ordinal grades showed substantial or better agreement between raters and modalities (κ or ICC > 0.6). Continuous measurements exhibited strong correlation between raters and modalities, although not universally. Bankart ICCs were not significant, owing to low prevalence. ZTE exhibited greater conspicuity of enthesopathic cysts and marrow edema. In 21 of 34 cases, ZTE imaging of osseous features exceeded SOC MR imaging. Conclusion ZTE MR imaging provides "CT-like" contrast for bone. The results of this study demonstrate strong intermodality agreement between measurements and grades from CT and ZTE images in a cohort of patients undergoing imaging with both modalities. A majority of ZTE image sets provided superior visualization of osseous features when compared with SOC MR image sets. This superiority coupled with strong quantitative agreement with CT suggests that ZTE may be used clinically in lieu of CT in some cases. RSNA, 2017 Online supplemental material is available for this article.

In‐phase zero TE musculoskeletal imaging

“…The main application of this method is expected to be in the area of musculoskeletal bone imaging and pseudo CT conversion. An earlier presented ZTE‐based bone imaging method has gained significant attention for musculoskeletal applications, PET/MR‐attenuation correction, and MR‐guided radiation therapy planning . However, fat–water out‐of‐phase disturbances and destructive signal interferences at fat–water tissue interfaces, make soft tissue appear less uniform thereby challenging bone depiction and segmentation (Figure ).…”

“…An earlier presented ZTE-based bone imaging method 5 has gained significant attention for musculoskeletal applications, PET/MR-attenuation correction, and MR-guided radiation therapy planning. [7][8][9][10][11] However, fat-water out-of-phase disturbances and destructive signal interferences at fat-water tissue interfaces, make soft tissue appear less uniform thereby challenging bone depiction and segmentation (Figure 1). In comparison, the presented ipZTE method provides ipZTE images with uniform soft tissue response free from out-of-phase artifacts and, hence, suited for the purpose of musculoskeletal bone imaging and pseudo CT conversion.…”

“…Simply inverting the gray scale of PD‐weighted ZTE images results in CT type image appearance (Figure ). The method has found widespread applications including musculoskeletal imaging, PET/MR attenuation correction, and MR‐guided radiation therapy planning …”

“…The method has found widespread applications including musculoskeletal imaging, PET/ MR attenuation correction, and MR-guided radiation therapy planning. [7][8][9][10][11][12] ZTE bone versus soft-tissue discrimination and depiction critically depends on soft-tissue to appear uniform. Using very low FAs (e.g., FA ~ 1°) results in PD-weighting with minimal T 1 saturation, while ZTE with a nominal TE of TE = 0 diminishes T * 2 contrast.…”

Clinical Feasibility of Zero TE Skull MRI in Patients with Head Trauma in Comparison with CT: A Single-Center Study

“…[13][14][15] To date, MR bone imaging using ultrashort TE or ZTE sequences has been studied for PET/MR imaging attenuation correction from the perspective of the technical approach in the literature. 9,[16][17][18][19][20] Recently, ZTE bone MR imaging was applied to osseous shoulder imaging, which showed strong intermodality agreement between measurements and grades of the lesions from ZTE bone MR imaging and CT. 21 However, to the best of our knowledge, there is no study of the clinical application of MR bone imaging of the skull for diagnostic use. Therefore, this study aimed to investigate the clinical feasibility of using ZTE skull MR imaging for evaluating skull lesions in patients with head trauma by assessing its diagnostic image quality and quantitative measurement compared with CT images.…”