Accelerated Stack-of-Spirals Free-Breathing Three-Dimensional Ultrashort Echo Time Lung Magnetic Resonance Imaging: A Feasibility Study in Patients With Breast Cancer.

Min Jae Cha,Hyewon Choi,Thomas Benkert,Josef Pfeuffer,Mun Young Paek,Hye Shin Ahn,Hyun Jeong Park

doi:10.3389/fonc.2021.746059

Min Jae Cha, Hyewon Choi + Show 5 more

Open Access

https://doi.org/10.3389/fonc.2021.746059

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Abstract

PurposeTo investigate the clinical feasibility of accelerated free-breathing stack-of-spirals (spiral) three-dimensional (3D) ultrashort echo time (UTE) lung magnetic resonance imaging (MRI) using iterative self‐consistent parallel imaging reconstruction from arbitrary k‐space (SPIRiT) algorithm in patients with breast cancer.MethodsThe institutional review board approved this prospective study and patients’ informed consents were obtained. Between June and August 2018, 29 female patients with breast cancer underwent 3-T MRI including accelerated free-breathing spiral 3D UTE (0.98-mm isotropic spatial resolution; echo time, 0.05 msec) of the lungs and thin-section chest computed tomography (CT). Two radiologists evaluated the image quality and pulmonary nodules on MRI were assessed and compared, CT as a reference.ResultsThe pulmonary vessels and bronchi were visible consistently up to the sub-sub-segmental and sub-segmental branch levels, respectively, on accelerated spiral 3D UTE. The overall image quality was evaluated as good and excellent for 70.7% of accelerated spiral 3D UTE images (reviewer [R]1, 72.4% [21/29]; R2, 69.0% [20/29]) and acceptable for 20.7% (both R1 and R2, 20.7% [6/29]). Five patients on CT revealed 141 pulmonary metastatic nodules (5.3 ± 2.6 mm); the overall nodule detection rate of accelerated spiral 3D UTE was sensitivity of 90.8% (128/141), accuracy of 87.7%, and positive predictive value of 96.2%. In the Bland-Altman plot analysis comparing nodule size between CT and MRI, 132/141 nodules (93.6%) were inside the limits of agreement.ConclusionAccelerated free-breathing spiral 3D UTE using the SPIRiT algorithm could be a potential alternative to CT for oncology patients.

Highlights

With advances in magnetic resonance imaging (MRI), it has become possible to capture rapidly decaying signals of lung tissue, which have very short T2 and T2* values [1]
Accelerated free-breathing spiral 3D Ultrashort echo time (UTE) using the self‐consistent parallel imaging reconstruction from arbitrary k‐space (SPIRiT) algorithm could be a potential alternative to computed tomography (CT) for oncology patients
Accelerated spiral 3D UTE lung MR examinations were successfully performed without any adverse events in the entire study population (29 female patients with pathologically confirmed breast cancer; median age, 53 years; range, 30–79 years)

Summary

Introduction

With advances in magnetic resonance imaging (MRI), it has become possible to capture rapidly decaying signals of lung tissue, which have very short T2 and T2* values [1]. Ultrashort echo time (UTE) imaging, offering an echo time (TE) < 1 ms, has emerged as a promising technique for lung MRI, enabling early acquisition of free induction decay at the end of the radiofrequency (RF) pulse [2, 3]. The benefit of pulmonary MRI over CT as a radiation-free modality is desirable. Achieving lung MRI with comparable diagnostic value to CT is challenging because of intrinsic short T2 and T2* properties of the lung and cardiac pulsation and respiratory motion artifacts. The acquisition time for pulmonary MRI is far longer than that for chest CT, accentuating the inefficacy of lung MRI

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