Diffusion-weighted MR imaging using FASE sequence for 3T MR system: Preliminary comparison of capability for N-stage assessment by means of diffusion-weighted MR imaging using EPI sequence, STIR FASE imaging and FDG PET/CT for non-small cell lung cancer patients
Introduction
Lung cancer is the leading cause of cancer death for both men and women worldwide, and non-small cell lung cancer (NSCLC) accounts for 80% of all lung cancers and can be cured surgically if detected at an early stage. Therefore, clinicians are frequently asked to perform accurate tumor, lymph node, metastasis (TNM) staging in routine clinical practice. Since the early 1990's, positron emission tomography with 2-[fluorine-18] fluoro-2-deoxy-D-glucose (FDG-PET) and FDG-PET combined with computed tomography (FDG-PET/CT) has been found to yield more accurate evaluation of the N-stage in NSCLC than computed tomography (CT) only [1], [2], [3], [4]. In addition, short inversion time (TI) inversion recovery (STIR) turbo spin-echo (SE) imaging of magnetic resonance (MR) imaging has been recommended since 2001 as effective for distinguishing metastatic from non-metastatic lymph nodes of NSCLC patients with higher sensitivity and accuracy than is possible with CT, conventional T1-weighted images, FDG-PET and FDG-PET/CT [5], [6], [7], [8].
During the last decade, diffusion-weighted MR imaging (DWI) has proven to be a valuable method for tracing of microscopic tissue structure. This technique is based on tissue-dependent signal attenuation caused by incoherent thermal motion of water molecules (Brownian motion). Since changes in the mobility of water molecules in biological tissue can be detected under various pathologic conditions [9], DWI has also been tested as another technique for differentiation of metastatic from non-metastatic lymph nodes in NSCLC patients [8], [10], [11]. However, it has been suggested the diagnostic performance of DWI is no more effective than that of PET or PET/CT [7], [11], and significantly inferior to that of STIR turbo (or fast) SE imaging in this setting [7]. Because DWI is currently obtained with the echo-planar imaging (EPI) sequence without any motion correction, this may result in relatively lower spatial resolution and less anatomical information than can be obtained with STIR turbo (or fast) SE imaging and to higher false-negative or false-positive rates. For this reason, we developed a novel DWI sequence based on the fast advanced SE (FASE) sequence, which is almost identical to single-shot turbo or fast SE sequences, to overcome the aforementioned limitation of DWI obtained with EPI sequence in this setting [12]. To date, however, no direct comparison has been performed of the diagnostic capability for N-stage assessment of DWI obtained with FASE (FASE-DWI) and EPI (EPI-DWI) sequences, STIR FASE imaging and FDG-PET/CT for NSCLC patients.
We hypothesized that FASE-DWI may yield a superior image quality and have a better lymph node detection capability than EPI-DWI, and be more sensitive and accurate for assessment of mediastinal and hilar lymph node metastases of NSCLC patients than EPI-DWI or FDG-PET/CT and can be considered at least as effective as STIR FASE imaging. The purpose of the study presented here was thus to prospectively compare the diagnostic capability of FASE-DWI, EPI-DWI, STIR FSE imaging and FDG-PET/CT for N-stage assessment of NSCLC patients.
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Protocol, support, and funding
This prospective study was approved by the institutional review board of Kobe University Hospital and written informed consent was obtained from all patients. This study was financially and/or technically supported by Toshiba Medical Systems Corporation. Two of the authors (Y.K. and M.Y.) are employees of Toshiba, but did not have control over any of the data and information submitted for publication or which data and information were to be included in this study.
Subjects
During the period September
Results
Representative cases are shown in Fig. 2, Fig. 3.
Discussion
Our results demonstrate that FASE-DWI can provide significantly better image quality, differentiation capability of mediastinal structure, artifact reduction, and lymph node detection capability than EPI-DWI on a 3T MR system. In addition, this study provides preliminary evidence that the capability for differentiation capability of lymph node metastases from non-metastatic lymph nodes, diagnostic accuracy of N-stage assessment and capability to distinguish inoperable from operable cases of
Conflicts of interest
This work was supported by Toshiba Medical Systems Corporation.
Acknowledgments
The authors wish to thank Shuntaro Tokunaga, MD, Syuya Hori, MD, PhD, Daisuke Tamura, MD, Motoko Tachihara, MD, Hiroshi Ohtera, MD, Yasuhiro Funada, MD, PhD, Kazuyuki Kobayashi, MD, PhD, Yoshihiro Nishimura, MD, PhD (all from Division of Respiratory Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine), Syunsuke Tane, MD, PhD, Daisuke Hokka, MD, PhD, Yugo Tanaka, MD, PhD, Yoshimasa Maniwa, MD, PhD (all from Division of Thoracic Surgery, Kobe University Graduate
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