Evaluation of Glycosaminoglycan in the Lumbar Disc Using Chemical Exchange Saturation Transfer MR at 3.0 Tesla: Reproducibility and Correlation with Disc Degeneration / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>This study aims to explore the clinical applicability and relevance of glycosaminoglycan Chemical Exchange Saturation Transfer (gagCEST) for intervertebral disc.</p><p><b>METHODS</b>25 subjects ranging in age from 24 yrs to 74 yrs were enrolled. gagCEST was acquired using a single-slice TSE sequence on a 3T. Saturation used a continuous rectangular RF pulse with B1=0.8 µT and a fixed duration time=1100 ms. Sagittal image was obtained firstly without saturation pulse, and then saturated images were acquired at 52 offsets ranging from ±0.125 to ±7 parts per million (ppm). MR T2 relaxivity map was acquired at the identical location. Six subjects were scanned twice to assess scan-rescan reproducibility.</p><p><b>RESULTS</b>GagCEST intraclass correlation coefficient (ICC) of six subjects was 0.759 for nucleus pulposus (NP) and 0.508 for annulus fibrosus (AF). Bland-Altman plots showed NP had a mean difference of 0.10% (95% limits of agreement: -3.02% to 3.22%); while that of AF was 0.34% (95% limits of agreement: -2.28% to 2.95%). For the 25 subjects, gag CEST in NP decreased as disc degeneration increased, with a similar trend to T2 relaxivity. Gag CEST of AF showed a better correlation with disc degeneration than T2 relaxivity.</p><p><b>CONCLUSION</b>GagCEST in NP and AF decreased as disc degeneration increased, while gagCEST in AF showed a better correlation than T2 relaxivity.</p>

Rapid Increase in Marrow Fat Content and Decrease in Marrow Perfusion in Lumbar Vertebra Following Bilateral Oophorectomy: An MR Imaging-Based Prospective Longitudinal Study

OBJECTIVE: Bilateral oophorectomy leads to reduced bone mineral density (BMD), and reduced BMD is associated with increased marrow fat and reduced marrow perfusion. Purpose of this study was to investigate how soon these changes occur following surgical oophorectomy. MATERIALS AND METHODS: Six patients who underwent hysterectomy and bilateral salpingo-oophorectomy were studied. At baseline, mean patient age was 49.5 years (range: 45-54 years). Third lumbar vertebral body BMD measurement using quantitative CT, marrow fat fraction (FF) using MR spectroscopy and marrow perfusion using dynamic contrast enhanced MRI were conducted immediately prior to surgery and at 3, 9, and 21 months after surgery. RESULTS: Reduced BMD, increased marrow FF, and reduced marrow perfusion occurred synchronously post-oophorectomy. There was a sharp decrease of 12.5 +/- 7.2% in BMD (n = 6), a sharp increase of 92.2 +/- 46.3% (n = 6) in FF, a sharp decrease of 23.6 +/- 3.9% in maximum contrast enhancement (n = 5), and of 45.4 +/- 7.7% for enhancement slope (n = 5) during the initial 3 months post surgery. BMD and marrow perfusion continued to decrease, and marrow FF continued to increase at a slower rate during the following 18 months. Friedman test showed a significant trend for these changes (p < 0.05). CONCLUSION: Bilateral oophorectomy leads to a rapid decrease in lumbar BMD, an increase in marrow fat content, and a decrease in marrow blood perfusion.

Characteristics of rat lumbar vertebral body bone mineral density and differential segmental responses to sex hormone deficiency: a clinical multidetector computed tomography study / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To investigate sex hormone deficiency related osteoporosis and efficacy of different therapies.</p><p><b>METHODS</b>Orchiectomized and ovariectomized rat models are used to investigate sex hormone deficiency related osteoporosis and efficacy of different therapies. A rat vertebral body can be longitudinally divided into central portion, which contain more trabecular bone, and para-endplate portions which contain more compact bone. In matured male and female Wistar and Sprague-Dawley rat lumbar spines, we investigated baseline bone mineral density (BMD) characteristics and the differential segmental responses in bone loss within the lumbar vertebral body post gonadal surgery with clinical multidetector computed tomography.</p><p><b>RESULTS</b>Para-endplate sections had a higher BMD than central sections. The cephalad para-endplate sections had a higher BMD than the caudad para-endplate sections. Eight weeks after gonadal removal, there was more bone loss in central sections than para-endplate sections. The relative difference of bone loss between para-endplate and central sections was more apparent in male rats than in female rats. There was more bone loss in caudad sections than cephalad sections; this lead to a further increase of BMD difference between caudad para-endplate sections and cephalad para-endplate sections post gonadal surgery.</p><p><b>CONCLUSION</b>The approach described in this study provided a consistent way to study BMD change within predominantly compact bone portion and trabecular bone portion of the vertebral body.</p>