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The feasibility of ZTE MR lung imaging in the assessment of pulmonary nodules or masses: a prospective head-to-head comparison with CT
Qianyun LIU1, Zhichao Feng2, Wenming Zhou1, and Weiyin Vivian LIU3
1Medical Imaging, Yueyang Central Hospital, Medical Imaging, Yueyang Central Hospital, Yueyang, Hunan, China, China, 2Department of Radiology, The Third Xiangya Hospital, Central South University, Changsha, Hunan, China, Department of Radiology, The Third Xiangya Hospital, Central South University, Changsha, Hunan, China, Changsha, Hunan, China, China, 3GE Healthcare, MR Research China, Beijing, Beijing, China, China
1Medical Imaging, Yueyang Central Hospital, Medical Imaging, Yueyang Central Hospital, Yueyang, Hunan, China, China, 2Department of Radiology, The Third Xiangya Hospital, Central South University, Changsha, Hunan, China, Department of Radiology, The Third Xiangya Hospital, Central South University, Changsha, Hunan, China, Changsha, Hunan, China, China, 3GE Healthcare, MR Research China, Beijing, Beijing, China, China
Synopsis
The feasibility of zero echo time MR lung imaging in the assessment of pulmonary nodules or masses: a prospective head-to-head comparison with CT.
Introduction
Pulmonary nodules or masses are commonly detected by chest CT in routine clinical practice. Most patients with pulmonary nodules need regular imaging surveillance for individual treatment decisions and care management. Patients with lung malignancies frequently received follow-up imaging for the evaluation of clinical response and disease recurrence. Lung MRI is desirably utilized for frequent follow-up imaging examinations with the feature of non-ionizing radiation. However, conventional MR imaging was hindered by the intrinsic physical properties of the lung (e.g. air and scarce proton signals). Zero echo time magnetic resonance imaging (ZTE-MRI) is a newly introduced gradient echo-based MRI sequence with a minimum susceptibility effect that can overcome the abovementioned challenges [1-3] and offer better signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). However, the performance of lung ZTE-MRI on the detecting pulmonary nodules or masses in comparison with conventional CT in routine practice is still not fully illustrated.Material and Methods
This prospective study was approved by our Institutional Review Board . 71 patients were confirmed for the existence of solid pulmonary nodules or masses by CT images and were enrolled and underwent lung ZTE-MRI scans within 3 days. ZTE-MRI and CT images were compared in terms of subjective image quality and imaging features. Unidimensional diameter and 3-dimensional volume of nodules or masses on both methods were manually measured and compared through statistical analysis.Results
54/71 (76.1%) patients were diagnosed with lung cancer. Subjective image quality was superior in CT compared with ZTE-MRI (p < 0.001). Inter-modality agreement for the imaging features was moderate for emphysema (Kappa = 0.50), substantial for fibrosis (Kappa = 0.76), and excellent (kappa = 0.87-1.00) for all the other features. The diameter and volume between ZTE-MRI and CT showed no significant difference (both p > 0.05) and revealed nearly excellent inter-observer agreement (intraclass correlation coefficient [ICC] = 0.975~0.980, p = 0.36 for diameter and p = 0.60 for volume). Multivariable analysis showed that non-smooth margin (odds ratio [OR] = 6.008, p = 0.015) was an independent predictor for significant inter-modality variation of volume between ZTE-MRI and CT.Discussion and Conclusion
ZTE imaging is a 3D slab excitated fast spin echo-based sequence with k space of center-out filling technique [5, 6]. SNR and CNR of intrapulmonary structures to nodule or mass on ZTE-MR images were consistent with one previous report [4]. In our study, ZTE-MRI images were acquired in a quiet and free-breath mode. Long-time scanning may induce respiratory motion artifacts in some patients, especially for those with severe emphysema or poor lung function. Notably, the lesion-pleura interface margin can be more clearly depicted by ZTE-MRI. MRI offers superior contrast between pleura and adjacent tissues compared to CT. Our results indicated that ZTE-MRI sequence may be served as an important approach for the assessment of pleural invasion of pulmonary lesions. The clinical utility of ZTE-MRI for the detection of pleural invasion in patients with lung malignancies is deserved being verified. The lesion size varying with time during the follow-up period is the cornerstone for treatment response of lung tumor in the conventional Response Evaluation Criteria in Solid Tumors (RECIST). Furthermore, volumetric measurement may provide more complete information of treatment response and predicting survival rate of lung cancer patients particularly with large, irregular lesions, thus allowing for faster assessment of new treatments. Tsim et al reported that MRI volumetry gained superiority and potential over CT for malignant pleural mesothelioma in terms of the association with patient survival [7]. High-resolution ZTE-MRI should be useful for the size evaluation including diameter and volume measurements of pulmonary nodules or masses, which has the potential to obviate frequent chest CT scans, especially in patients who are vulnerable to radiation exposure. Besides, the possible factors for significant inter-modality variations of lesion volume between ZTE-MRI and CT was non-smooth margin, an independent predictor. This may be explained by the significant differences of image display between the peripheral part of the irregular lesions and the adjacent lung tissue on the two imaging modalities. Several limitations including relatively small sample size，only solid pulmonary nodules or masses.ZTE lung imaging is feasible as a part of routine chest MRI in the assessment and surveillance of pulmonary nodules or masses, presenting perfect agreement with CT in terms of imaging features and size measurement.Acknowledgements
No acknowledgement found.References
1.Gibiino F, Sacolick L, Menini A, Landini L, Wiesinger F (2015) Free-breathing, zero-TE MR lung imaging. Magma 28:207-215.
2.Breighner RE, Endo Y, Konin GP, Gulotta LV, Koff MF, Potter HG (2018) Technical Developments: Zero Echo Time Imaging of the Shoulder: Enhanced Osseous Detail by Using MR Imaging. Radiology 286:960-966.
3.Weiger M, Pruessmann KP (2019) Short-T(2) MRI: Principles and recent advances. Prog Nucl Magn Reson Spectrosc 114-115:237-270.
4.Bae K, Jeon KN, Hwang MJ et al (2020) Respiratory motion-resolved fourdimensional zero echo time (4D ZTE) lung MRI using retrospective soft gating: feasibility and image quality compared with 3D ZTE. Eur Radiol 30:5130-5138.
5.Weiger M, Brunner DO, Dietrich BE, Müller CF, Pruessmann KP (2013) ZTE imaging in humans. Magn Reson Med 70:328-332.
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Figures
Fig. 1 Subjective
scores of image quality for lung ZTE-MRI and CT.
Fig. 2 Violin
plots represent (a) SNR of all structures and (b) CNR of intrapulmonary
structures on lung ZTE-MRI.
A 48y man with lung adenocarcinoma (a)and
(b) mediastinal section on CT and (c) ZTE. (d) ADC map superimposing on ZTE
showed the lesion extent. A 59y man with lung adenocarcinoma(e) and (f)
mediastinal section on CT and (g) ZTE. ADC map (h) superimposing on ZTE . A 51y
man with lung adenocarcinoma on CT (i) and ZTE(j). A 69y man with lung squamous
carcinoma in the left lower lobe on CT (k) and ZTE(l). A 73y man with lung
adenocarcinoma carcinoma on CT (m) and ZTE(n). A 57y man with lung abscess on
CT (o) and ZTE(p).
Manual
segmentation of pulmonary masses (red or blue) using volume rendering. CT (a)
and ZTE-MRI (b) in axial view showed that the measured volumes of a lung tumor
in the right upper lobe were 40.7 mm3 and 46.6 mm3, respectively.
CT (c) and ZTE-MRI (d) in axial view showed that the measured volumes of
another lung tumor in the left upper lobe were 138.8 mm3 and 145.8
mm3, respectively. ZTE = zero echo time.
Fig. 5 Inter-modality
correlations and agreements in lesion measurements. Scatter plots demonstrated
the correlation between ZTE-MRI and CT in diameter (a) and volume (b).
Bland-Altman plots showed the inter-modality agreement between ZTE-MRI and CT
in diameter (c) and volume (d). ZTE = zero echo time.
Fig. 6 Inter-observer
agreement of lesion measurements on lung ZTE-MRI and CT. Bland-Altman plots showed the agreement of
diameter on ZTE-MRI (a) and CT (b), and the agreement of volume on ZTE-MRI (c)
and CT (d). ZTE = zero echo time.
Table 1 Patient characteristics of the study population
Table 2
SNR and CNR of thoracic/intrapulmonary structures on lung ZTE-MRI images
Table
3 Analysis of agreement between lung
ZTE-MRI and CT for imaging features
Table 4 Comparison between
lung ZTE-MRI and CT in lesion measurements
Table 5 Inter-observer
agreement of lesion measurements for lung ZTE-MRI and CT
Table 6 Factors associated
with the significant variation (> 10%) between lung ZTE-MRI and CT-derived
lesion volumes
DOI: https://doi.org/10.58530/2022/4247