Yoshiharu Ohno1,2, Masao Yui3, Daisuke Takenaka4, Yoshimori Kassai3, Kazuhiro Murayama1, and Takeshi Yoshikawa2
1Radiology, Fujita Health University School of Medicine, Toyoake, Japan, 2Radiology, Kobe University Graduate School of Medicine, Kobe, Japan, 3Canon Medical Systems Corporation, Otawara, Japan, 4Diagnostic Radiology, Hyogo Cancer Center, Akashi, Japan
Synopsis
No
major papers that determined the utility of cDWI for diagnosis of lymph node
metastasis have been reported. We
hypothesize that cDWI has a potential for improving diagnostic performance of
N-stage in NSCLC patients as compared with aDWI and FDG-PET/CT, when set
appropriate b value. The purpose of this
study is to determine the utility of cDWI for differentiating metastatic from
non-metastatic lymph nodes in NSCLC patients as compared with aDWI and
FDG-PET/CT.
Introduction
Accurate
TNM staging in non-small cell lung cancer (NSCLC) is fundamental clinical
question from clinicians to determine appropriate therapeutic strategy. Since 1990's, positron emission tomography (PET) or PET fused with
CT (PET/CT) combined with [18F] fluoro-2-D-glucose (FDG) has been applied to answer this question, although the diagnostic
accuracy of PET or PET/CT is recently suggested as having some limitations. Since 2000's, magnetic resonance imaging (MRI)
has also been suggested as another promising modality in this setting by means
of short TI inversion recovery (STIR) turbo spin-echo (SE) imaging as well as
diffusion-weighted imaging (DWI) (1-3). In
addition, DWI has been widely applied for N-stage assessment in non-small cell
lung cancer (NSCLC) patients (2-4).
However, image quality of DWI at 3T MR system is relatively lower than
that at 1.5T MR system (3). Recently,
computed DWI (cDWI) generated from actually obtained DWI (aDWI) at two
different b values has been reported as useful for improving image quality and improving
diagnostic performance in prostatic cancer (5).
However, there are no major papers that determined the utility of cDWI
for diagnosis of lymph node metastasis. We
hypothesize that cDWI has a potential for improving diagnostic performance of
N-stage in NSCLC patients as compared with aDWI and FDG-PET/CT, when set
appropriate b value. The purpose of this
study is to determine the utility of cDWI for differentiating metastatic from
non-metastatic lymph nodes in NSCLC patients as compared with aDWI and
FDG-PET/CT.Materials and Methods
245 consecutive
operable NSCLC patients (127 men, 118 women; mean age 75 years) prospectively
underwent actual DWI (aDWI) on a 3T system (Vantage Titan 3T, Canon Medical Systems Corporation,
Otawara, Japan) with b value at 0 and 1000 s/mm2, FDG-PET/CT, surgical
treatment and pathological and follow-up examinations. In each subject, computed DWIs were generated
at 400 (cDWI400), 600 (cDWI600) and 800 (cDWI800)
s/mm2. According to
pathological examination results, 114 metastatic nodes and 114 out of 2581
non-metastatic nodes were measured contrast ratio (CR) on each computed DWI
between each lymph node and chest wall muscle, ADC on aDWI and SUVmax
by ROI measurements. To compare
differentiation capability on a per node basis, ROC analysis was
performed. Then, diagnostic performance
were compared among all methods by McNemar’s test. On a per patient basis, agreement of N-stage
classification between each index and pathological examination result was
evaluated by kappa statistics. Finally,
accuracy of N-stage classification was also compared among all methods by
McNemar’s test. Results
Representative
case is shown in Figure 1. All CR, ADC
and SUVmax had significant differences between metastatic and
non-metastatic lymph nodes (p<0.05).
Figure 2 shows the results of ROC analysis for differentiating
metastatic from non-metastatic lymph nodes.
Area under the curve (AUC) of CR600 (AUC=0.87) was
significantly larger than that of SUVmax (AUC=0.81, p=0.02), CR400
(AUC=0.80, p<0.0001) and CR800 (AUC=0.83, p<0.0001). AUC of CR800 was also
significantly larger than that of CR400 (p=0.0004). Figure 3 shows the results of compared
differentiation capability for metastatic from non-metastatic lymph nodes on a
per node basis. Sensitivity of each CR
was significantly higher than that of SUVmax (p<0.05). Specificity of SUVmax was
significantly higher than that of CR400 and CR800
(p<0.05). Accuracy of CR600
was significantly higher than that of other CRs, ADC and SUVmax
(p<0.05). Figure 4 demonstrates
agreement of N-stage between evaluated and final N-stage and compared
diagnostic accuracy for N-stage on a per patient basis. Agreement with final diagnosis by each index
was significant and substantial (0.71<κ<0.79, p<0.0001). Accuracy of CR600 was
significantly higher than that of CR400 and CR800
(p<0.05). Conclusion
cDWI
is considered as the new promising method for improving diagnostic performance
of lymph node metastasis and N-stage evaluation as compared with aDWI and
FDG-PET/CT in NSCLC patients. In this
setting, cDWI at b value as 600s/mm2 would be better to be generated
rather than that at other b values in routine clinical practice. Acknowledgements
Authors wish to thank Mr. Katsusuke Kyotani and
Prof. Takamichi Murakami in Kobe University Hospital for their valuable
contributions to this study. References
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231(3): 872-879.
- Ohno Y, Koyama H, Yoshikawa T, et al. Radiology. 2011 ;
261(2): 605-615.
- Ohno Y, Koyama H, Yoshikawa T, et al. Eur J Radiol. 2015 ;
84(11): 2321-2331.
- Peerlings J, Troost EG, Nelemans PJ, et al. Radiology.
2016 ; 281(1): 86-98.
- Ueno Y, Takahashi S, Kitajima K, et al. Eur. Radiol.,
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