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以磁振影像探討單粒稻穀之水份分佈

Assessment of Moisture Distribution in Single Rice Kernels Using Magnetic Resonance Imaging

摘要


本研究以磁振影像探討單粒稻穀內部水份分佈情形,建立適用的磁振造影條件,以暸解不同條件下稻穀內部水份的空間分佈,進而提供分析稻穀乾燥時均化時間調控與稻穀胴裂現象成因之基本資訊。由於單粒稻穀爲體積小、水份低的固態樣本,其磁振成像具有挑戰性,以Bruker S-300磁振造影儀,在3 Tesla靜磁場下,以一般脈衝序列無法獲得適用之影像,因此本研究採用SPI脈衝序列進行稻穀的磁振造影。爲了取得較佳品質的影像,藉由一系列的參數調整來進行試驗,並且以所得之磁振影像訊雜比做爲判斷影像品質的指標,尋找最佳的成像條件。經試驗結果以視野FOV設定在1.6×1.6平方公分,影像矩陣Matrix 設定在32×32×16,掃描次數NEX在2次以上,迴訊時間TE爲200μs,重複時間TR爲10 ms,脈衝角度爲10度,脈衝長度爲10 ms等條件下,可得到較佳之影像訊雜比,以此做爲後續進行磁振影像掃描時參數設定之依據。依此成像條件,我們得以比較新收穫稻穀與經過乾燥儲藏後稻穀內部水份分佈之差異,新收穫的稻穀影像其訊號明顯較強、水份梯度較大,尤其在胚芽部份有較高之訊號。實驗結果亦顯示,稻穀磁振影像訊號強度與稻穀胚乳部份的平均含水率呈線性關係,因此可據以建立檢量線,從磁振影像推估稻穀的含水率。

關鍵字

磁振影像 稻穀 含水率 SPI

並列摘要


In this study, we used magnetic resonance imaging to assess the moisture distribution within single rice kernels. Feasible parameters of SPI pulse sequence were established to acquire magnetic resonance images of rice kernels which reveal the spatial distribution of moisture content within single rice kernels under various conditions. This information is important in understanding the effect of tempering time on the rice fissuring in a drying process. Since rice kernel is a small solid sample with low moisture content, it is challenging to acquire its magnetic resonance images using ordinary pulse sequence for a 3 Tesla Bruker S-300 Biospec/Medspec MRI. Therefore, we applied SPI sequence for image acquisition. In order to determine a pertinent set of SPI sequence parameters, a series of experiments was performed and the signal-to-noise ratio, SNR, of magnetic resonance images of rice kernels was used as the criterion for image quality evaluation. The optimum set of SPI sequence parameters was determine d to be: FOV=1.6×1.6 cm^2, Matrix=32×32×16, NEX≥2, TE=200μs, TR=10ms, flip angle=10, pulse length=10ms, and was used in subsequent experiments to acquire rice kernel images with good quality. Experiments were carried out to compare the moisture distribution within newly harvested rice kernel and dried rice kernels. The newly harvested rice kernel in general exhibited brighter image intensity than the dried kernel. The newly harvested rice kernel also has stronger signal intensity at its embryo part. Separate experiments were also conducted to investigate the relationship between the magnetic resonance signal intensity and the moisture content of rice kernels. Experimental results revealed that there is a linear relationship between the signal intensity and the moisture content. This implies that, by establishing a calibration line, magnetic resonance imaging can be applied in quantitative estimation of moisture content within a rice kernel.

並列關鍵字

MRI Rice kernel Moisture content SPI

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