本文關(guān)鍵詞：使用MR DIXON成像觀察模擬微重力狀態(tài)下人體下肢脂肪體積的變化　出處：《安徽醫(yī)科大學(xué)》2013年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 微重力 脂肪體積 磁共振成像 水脂分離

【摘要】：背景:航天員在太空飛行時，由于失重時作用在運動器官上的重力負(fù)荷消失，人在太空中維持姿勢和進(jìn)行運動不再需要對抗重力的作用，這對機(jī)體各生理系統(tǒng)會產(chǎn)生較大影響，包括體液丟失、體重下降、立位耐力下降、肌肉萎縮、骨質(zhì)進(jìn)行性流失等。以往關(guān)于模擬微重力時人體脂肪體積變化的研究較少，并且研究結(jié)果并不一致，脂肪體積增加[1,2]與不變[3]的報道皆有。 脂肪作為人體重要儲能組織，在維持人體生理功能中起到十分重要作用，因此要深入地研究微重力對脂肪代謝的影響，必須首先了解微重力對人體內(nèi)脂肪體積及其分布的影響。以往實驗中測量方法大多是用雙能X線吸收法，此檢查雖然能較準(zhǔn)確的測量人體各部位的脂肪體積，但有放射性，對人體有害。 磁共振成像(magnetic resonance imaging MRI)技術(shù)的不斷進(jìn)步為準(zhǔn)確測量人體脂肪體積提供了新的技術(shù)手段。磁共振成像技術(shù)無創(chuàng)、無放射、易重復(fù)、多參數(shù)成像、具有良好的空間和時間分辨率，可定量地測量人體脂肪體積的變化。磁共振水脂分離(Dixon)技術(shù)就是其中一種特殊的成像方法，，它利用水和脂肪兩種物質(zhì)的質(zhì)子共振頻率上的差異，一次掃描能分別得到純脂和純水的質(zhì)子圖像，已在臨床工作中得到廣泛運用。Dixon的水與脂的分別成像技術(shù)能減少肌肉與脂肪間的相互影響從而提高圖像質(zhì)量，能更準(zhǔn)確的反映失重狀態(tài)下人體下肢脂肪體積的變化，減小測量結(jié)果的誤差。還可以用來分別測量肌肉和脂肪的體積，為研究微重力對人體的影響提供高質(zhì)量的影像數(shù)據(jù)。 目的：使用無放射性的先進(jìn)MR成像技術(shù)，觀察微重力環(huán)境時人體下肢脂肪體積的變化，為微重力環(huán)境中脂肪代謝的研究和航天員康復(fù)計劃的制定提供科學(xué)依據(jù)。 方法:由航天員科研訓(xùn)練中心招募18名健康志愿者，進(jìn)行為期30天的-6°頭低位模擬微重力的臥床實驗，所有志愿者于臥床實驗開始前一天和實驗結(jié)束當(dāng)日均接受下肢磁共振掃描。使用儀器為Siemens Verio3.0T磁共振掃描儀，掃描所用線圈為體表線圈。采用GRE T1WI水脂分離成像技術(shù)進(jìn)行下肢無間隔橫軸位掃描，掃描范圍自雙側(cè)股骨頭下緣至踝關(guān)節(jié)上緣。使用北京師范大學(xué)信息科學(xué)與技術(shù)學(xué)院編寫的專用體積測量軟件分別測量臥床前后下肢總脂肪體積、大腿段及小腿段脂肪體積。用SPSS16.0軟件中配對t檢驗方法進(jìn)行統(tǒng)計學(xué)分析，檢驗志愿者臥床實驗前后的下肢脂肪體積變化的顯著性。 結(jié)果：與臥床實驗前相比，臥床實驗后所有志愿者下肢總脂肪體積及大腿段脂肪體積明顯增加，分別增加15.67±11.19%(P 0.001)和20.05±13.61%(P0.001)；小腿段脂肪體積呈增加趨勢，增加7.91±10.30%，統(tǒng)計學(xué)檢驗無顯著性(P0.05)。 結(jié)論：本實驗組數(shù)據(jù)提示： (1)30天頭低位臥床可以引起人體下肢總脂肪體積和大腿段總脂肪體積的增加；小腿段脂肪體積有增加趨勢，但與臥床前相比，差異無顯著性。 (2) MRI水脂分離技術(shù)可以用于測量人體下肢的脂肪體積，圖像對比度高，無放射，操作簡單易重復(fù)，有良好的應(yīng)用前景，是動態(tài)觀察脂肪體積變化的理想工具。
[Abstract]:Background: the astronauts in space flight, due to gravity load loss in motion organs disappear, maintain posture and motion in space is no longer needed against gravity, this will have a greater impact on the body of the physiological systems, including the loss of body fluid, body weight loss, orthostatic intolerance, muscle atrophy. Bone loss. Previous studies on the changes of the human body fat volume of simulated microgravity when less, and the results are not consistent, fat volume increased [1,2] [3] and constant both are reported.
As an important body fat storage tissue, plays an important role in maintaining the physiological function of human body, thus thoroughly study the effects of microgravity on fat metabolism, we must first understand the effects of microgravity on the human body fat volume and distribution. The method is mostly in the previous experimental measurement by dual energy X-ray absorptiometry, although this check each part can accurately measure body fat volume, but radioactive, harmful to the human body.
Magnetic resonance imaging (magnetic resonance imaging MRI) technology advances for the accurate measurement of human body fat volume provides a new technical means. Magnetic resonance imaging is non-invasive, no radiation, easy to repeat, multi parameter imaging, with good spatial and temporal resolution, can quantitatively measure the human body fat volume magnetic resonance. Water fat separation (Dixon) technology is one kind of special imaging method, it uses different proton resonance frequency of the water and fat two substances on the scanning of a proton image of pure lipids and pure water respectively, has been widely used in water and lipid.Dixon respectively imaging technology can reduce the mutual influence of muscle and the fat so as to improve the image quality in clinical work, we can more accurately reflect the changes of the lower limb of the human body fat volume loss condition, reduce the error of the measurement result. Also can be measured respectively by The volume of muscle and fat provides high quality image data for the study of the impact of microgravity on the human body.
Objective: To observe the changes of human lower extremity fat volume in the microgravity environment by using advanced radioactivity free MR imaging technology, and provide a scientific basis for the research of fat metabolism and the rehabilitation plan of astronauts in microgravity environment.
Methods: the astronaut research and training center recruited 18 healthy volunteers, bed rest for 30 days -6 degrees head down tilt simulated microgravity, all the volunteers began in bed one day before the end of the experiment and experimental day received lower extremity MRI. The instrument was Siemens Verio3.0T magnetic resonance scanner, scanning the surface coil using GRE. T1WI water fat separation of lower extremity nonseptate axial scanning imaging, scanning from the lower margin of bilateral femoral head to ankle joint on the edge. The special volume measurement software using the College of information science and technology Beijing Normal University prepared were measured before and after the total fat volume in lower limbs, thigh and leg fat volume were statistically analyzed. Using SPSS16.0 software paired t test, significant lower limb fat volume changes before and after the test bed volunteer experiments.
Results: compared with the bed before the experiment, all the total fat and thigh fat volume of volunteers lower limb segment volume increased significantly in the experiment, increased 15.67 + 11.19% respectively (P 0.001) and 20.05 + 13.61% (P0.001); lower leg fat volume increased, increased by 7.91 + 10.30%, statistically no significant (P0.05).
Conclusion: the data of the experimental group suggest that:
(1) 30 days of head down bed can cause total body fat and thigh fat volume lower extremity total volume increased; lower leg fat volume increased, but compared with before bed, there was no significant difference.
(2) MRI water fat separation technology can be used to measure the fat volume of human lower extremities, with high image contrast, no radiation, simple operation and easy repetition. It has good application prospects and is an ideal tool for dynamically observing fat volume changes.

【學(xué)位授予單位】：安徽醫(yī)科大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2013
【分類號】：R85

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