Shao-Chieh Lin1, Chun-Jung Juan2, Yi-Jui Liu3, Chun-Wen Chen4, Chien-Yuan Wang5, Wu-Chung Shen6, Der-Yang Cho7, and Kai-Yuan Cheng8
1Ph.D. program in Electrical and Communication Engineering, Feng Chia University, Taichung, Taiwan, 2Department of Medical Imaging, China Medical University Hsinchu Hospital, Hsinchu, Taiwan, 3Department of Automatic Control Engineering, Feng Chia University, Taichung, Taiwan, 4Department of Radiology, Taichung Armed Forces General Hospital, Taichung, Taiwan, 5Department of Orthopedics, China Medical University Hsinchu Hospital, Hsinchu, Taiwan, 6Department of Medical Imaging, China Medical University Hospital, Taichung, Taiwan, 7Department of Neurosurgery, China Medical University Hospital, Taichung, Taiwan, 8Department of Medical Imaging and Radiological Sciences, Central Taiwan University of Science and Technology, Taichung, Taiwan
Synopsis
Lumbar vertebral osteoporosis (LvOPO) in
women is clinically important. It is affected by mixed causes, including but
not limited to the aging, lumbar vertebral fat fraction (LvFF), and estrogen. In
the current study, the LvOPO in women was diagnosed by a newly proposed hybrid
scoring system, i.e., the LvOPO score (LvOPOS). By integrating the independent
predictors including age, LvFF, and menopause-MR interval (MMI), the LvOPOS
achieved an AUC higher than the LvFF (0.802), age (0.794), and MMI (0.788). Our
results provide a new insight in diagnosing the LvOPO specific to women with
relevant to both clinical and MR features.
Introduction:
Lumbar
vertebral osteoporosis (LvOPO) is a disease characterized by reduced bone mass
and deteriorated bony micro-architecture of the lumbar vertebrae. LvOPO is defined
as lumbar vertebral bone mineral density (BMD) of 2.5 standard deviations lower
than the young adult reference mean [1]. A hybrid scoring system integrating clinical information and imaging
features for diagnosing a certain disease is rapidly emerging. The increased of
marrow fat deposition in the lumbar vertebrae was usually observed in the patients
with reduced BMD [2]. Based on this observation, evaluation of lumbar vertebral
fat fraction (LvFF) might play a role in better understanding LvOPO conceptually.
Fat fraction has been successfully quantified using MRI in vivo, including but
not limited to liver [3], parotid gland [4], and spine [5]. A hybrid scoring
system integrating clinical information and imaging features for diagnosing a
certain disease is rapidly emerging. For example, the Warthin tumor score been
shown to outperform any independent predictors in diagnosing parotid Warthin
tumors [6]. Such concept has not yet been applied to diagnose LvOPO. We
hypothesized that hybrid scores integrating clinical and imaging features might
also improve the diagnosis of LvOPO. The aim of our study was to propose a LvOPO
score (LvOPOS) to diagnose LvOPO in postmenopausal women.Materials and Methods:
MRI
study was performed using a 1.5T clinical scanner (Signa HDxt, GE Healthcare,
Milwaukee, WI). Lumbar vertebral fat fraction (LvFF) was measured by
quantitative magnetic resonance imaging using the iterative decomposition of
water and fat with echo asymmetry and least-squares estimation (IDEAL) method
for fat-water quantification. Sagittal T2WI IDEAL fast spin echo (FSE-XL)
imaging parameters included repetition time/echo time, 3000 ms/115.1 ms;
receiver bandwidth, 63.86 kHz; echo train length, 20; field of view (FOV), 240
x 240 mm; slice thickness, 10 mm; matrix size, 320 x 192; number of
excitations, 3; slice number, 3; flip angle, 90; . A total of 3 slices covered
the lumbar spine from the T12 vertebra to the sacrum. Bone mineral density
(BMD) of the lumbar spine, including L1 to L4 vertebrae, was measured by
dual-energy X-ray absorptiometry (DeXA) using a Hologic QDR-4500W (S/N 47125)
model (Hologic Inc., Bedford, MA, USA). BMD data were acquired, processed, and
calculated based on the International Society for Clinical Densitometry (ISCD)
guidelines [7].To represent the overall status of the BMD and fat fraction of
each participant, the averaged BMD and LvFF was calculated by the L1 to L4
vertebrae. Statistical analyses were performed using MATLAB, SPSS Version 16.0
software (SPSS Inc, Chicago, III), and MedCalc Version 13.0 (MedCalc Software
Inc, Ostend Belgium). The nonparametric receiver operating characteristics
(ROC) curves were plotted and areas under curve (AUC) were calculated for
distinguishing the LvOPO group from the normal group. Sensitivity, specificity, positive predictive value,
negative predictive value, and overall accuracy of each predictor were
calculated. A P value less
than 0.05 was considered as statistically significant.Result:
101 subjects after menopause were collected in this study. The LvOPO cases were 15 and normal subjects were 86. All
participants received BMD measures using DXA as well as LvFF quantifications of
using the IDEAL method. Clinical information including age, MMI, body height,
body weight, body mass index (BMI) were recorded. Box and Whisker plots
of the
patient characteristics classified by the BMD were shown in Fig. 1. First,
ROC
curves of
the clinical and imaging predictors in diagnosing the LvOPO were plotted in
Fig. 2. The AUC of the age, LvFF, MMI, body
height, body weight, and BMI in diagnosing the LvOPO was 0.794, 0.802, 0.788, 0.687, 0.617, and 0.545, respectively. Second, a parameter was selected as a
predictor for the LvOPOS based on the criteria of an AUC no less than 0.7. Finally, the criteria allowing a
sensitivity no less than 79%, together with highest specificity were selected for
each predictor in the LvOPOS as listed in Table 1. The LvOPOS achieved the highest AUC (0.822), followed by the
LvFF (0.802), age (0.794), and MMI (0.788) in diagnosing LvOPO.Discussion:
The
difference of BMD can be attributed to the aging, which has an effect on bone
loss via suppressing osteogenic programs in the bone marrow [8]. It can also be
ascribed to the depletion of estrogen, which reduces bone resorption by
inhibiting osteoclast formation and enhancing osteoclast apoptosis [9], in
post-menopausal women. Our study showed a general trend of an inverse
association between the BMD and LvFF as well as an inverse association between
the BMD and age in the women. In addition, the LvOPOS is a good index with high
AUC for diagnosing LvOPO in women.Acknowledgements
No acknowledgement found.References
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