臺灣博碩士論文加值系統

本研究目的為比較肝臟良性及惡性病灶在擴散權重影像(Diffusion-weighted imaging，DWI)中的訊號強度(Signal intensity，SI)、在七組不同b值組合所得到表觀擴散係數圖 (Apparent diffusion coefficient，ADC map)中的ADC值與ADC ratio比，並提出用來鑑別診斷肝臟病灶最佳化的b值組合。
我們以回溯性方式自2012年1月至2012年6月期間，連續收錄198名接受過腹部磁振造影含打顯影劑檢查之病患，共212個肝臟病灶，並將病灶分為良性及惡性兩大類，其中良性病灶包含了36個囊腫、73個血管瘤、9個局部結節增生、17個再生不良結節、2個膿瘍及1個血管肌肉脂肪瘤，惡性病灶包含67個肝細胞癌及7個肝轉移性腫瘤。本研究中磁振造影檢查為使用Philips 1.5T磁振造影儀；在擴散權重影像中設定使用四個b值(0, 100, 500, 1000 s/mm²)，及經由四個b值做不同的組合(分別為b= 0、100，b= 0、500，b= 0、1000，b= 0、500、1000，b= 0、100、500，b= 0、100、1000，b= 0、100、500、1000)，在所得到的七組表觀擴散係數圖中以ROI(Region of interest)方式圈選病灶，量測病灶在DWI影像中每一個b值(0, 100, 500, 1000 s/mm²)的訊號強度及在ADC map中量測病灶及肝實質的ADC值，並將病灶ADC值除以肝實質ADC值以求得ADC ratio比值。
由兩位有臨床判讀MRI影像經驗之放射科醫師分別獨立判讀本研究所收錄之肝臟結節病灶在擴散權重影像中的亮度差異，並將判讀結果分為H3(High 3)、H2(High 2)、H1(High 1) 、I(Iso)、L(Low)五級。
以t-Test及Mann-Whitney U Test分析比較不同組合間的差異，並以ROC analysis去評估七組ADC map的Sensitivity、Specificity及Accuracy，評估出哪一組設定最適合用於診斷肝臟病灶，及分析用來鑑別區分出肝臟良性病灶及惡性病灶之ADC Cut-off value(閾值)；再以Kappa Test去分析觀測者間在目測DWI影像中病灶亮度的差異性。
經由結果分析可發現DWI中的訊號強度及ADC map中量測到的ADC值及ADC ratio比值可區分出肝臟良性及惡性病灶(p值分別為< 0.001、< 0.001、< 0.001)，且肝臟良性病灶的ADC值高於惡性病灶, ADC閾值為1.454。良性病灶中的囊腫有著最高的ADC值，血管瘤的ADC值為次高；而惡性病灶中的肝細胞癌及肝臟轉移性腫瘤的平均ADC值和其他四種良性病灶(包含局部結節增生、再生不良結節、肝膿瘍及血管肌肉脂肪瘤)的平均ADC值則十分接近。由放射科醫師判讀擴散權重影像中的亮度，發現不同肝臟結節病灶是有差異的，Kappa值為0.65~0.76屬高度吻合 (Good)。經由統計,最適合用來診斷肝臟病灶的b值組合為b=0、1000, 其診斷肝臟病灶的Sensitivity、Specificity及Accuracy為89.2%、79%及82.6%。
最後本研究結論為建議最適合用來診斷肝臟病灶的b值組合為b=0、1000；而用來區分肝臟良性及惡性病灶的ADC Cut-off value(閾值)為1.454。

關鍵字:擴散權重影像、表觀擴散係數、肝臟結節病灶

Purpose:
To compare the signal intensity(SI) in diffusion-weighted imaging(DWI) and the apparent diffusion coefficient(ADC) values in ADC map between benign and malignant hepatic nodules, and to determined the optimal b-value for differentiation of the liver lesions.

Materials and Methods:
Between 2012 January and 2012 June, a total of 198 consecutive patients with 212 hepatic nodules were including in our study, and all patients underwent the contrast enhancement abdomen MRI examination. The 212 lesions were classified into benign and malignant groups: the benign groups including 36 cysts, 73 hemangiomas, 9 focal nodular hyperplasia (FNH), 17 dysplastic nodule(DN), 2 abscesses and 1 angiomyolipoma ; the malignant groups including 67 hepatocellular carcinomas(HCC) and 7 metastases. MRI examinations were performed using a Philips 1.5T MR system. In DWI, four b-value (0, 100, 500, and 1000 s/mm²) were used, and there were seven different ADC maps created by using different b-values combination, including b=0,100; 0, 500; 0, 1000; 0, 100, 500; 0, 100, 1000; 0, 500, 1000; 0, 100, 500, and 1000.
The signal intensities were measured by placing regions of interest in the lesions on the DWI for each b-value (0, 100, 500, and 1000 s/mm²), and we then measured the ADC value of the lesion and liver parenchyma. The ADC ratio (ADC value of lesion/ADC value of liver parenchyma) was also calculated. Two radiologists visually evaluated the brightness of all the lesions in b=0,100,500, and 1000, separately.
Comparisons between groups were performed by t-test and Mann-Whitney U test. Kappa test was used to evaluate the difference between the two radiologists. ROC analysis was used to evaluate the diagnostic performance of the quantitative ADC values for differentiating between benign and malignant lesions. A p value of < 0.05 was deemed to indicate statistical significance.

Results:
The SI on DWI, ADC value and ADC ratio were significantly different between benign and malignant liver lesions (p value were <0.001, <0.001, <0.001, separately). The ADC values of benign lesions were significantly higher than those of malignant lesions, the ADC cut-of value is 1.454. The brightness recorded by the radiologist was significant different among the lesions. The inter-observers’ agreement is good (0.65-0.76). The b-value combination ( b=0,1000 s/mm²) is best for the differentiation of benign and malignant liver lesions, the sensitive, specificity, accuracy was 89.2%、79% and 82.6% .

Conclusion:
In DWI, we suggest the use of the b-value combination ( b=0,1000 s/mm²) for the differentiation of benign and malignant hepatic nodules, and the ADC cut-off value of choice was 1.454.

Key words: Diffusion-weighted imaging (DWI)、Apparent diffusion coefficient (ADC )、hepatic nodules

致謝……………………………………………………………………………………i
中文摘要……………………………………………………………………….ii
Abstract………………………………………………………………………iii
目錄……………………………………………………………………………...v
圖目錄…………………………………………………………………………......ix
表目錄…………………………………………………………………………….….....xi
第一章 緒論…………………………………………………………………..…..…1
1.1 研究背景與動機…………………………………………………………….....1
1.2 研究目的………………………………………………………………..……...2
1.3 研究架構…………………………………………………………………...…..3
第二章 肝臟解剖構造與肝臟結節特性…………………………………….…..….4
2.1 肝臟結構…………………………………………………………………….....4
2.2 肝臟結節病灶……………………………………………………………….....5
2.2.1 肝臟囊腫………………..…………………………..……………………6
2.2.2 肝臟血管瘤………………..………………………………..……………7
2.2.3 肝臟局部結節增生……………..…………..…………………….……...8
2.2.4 再生不良結節…..……………………………..………………………....9
2.2.5 肝臟膿瘍…………………………………………..………..…………..10
2.2.6 血管肌肉脂肪瘤……………………..……………..…………………..11
2.2.7 肝細胞癌……………………..………………………………..………..12
2.2.8 肝臟轉移性腫瘤………..……………………………………..………..13
第三章 磁振造影各參數原理……………………………………………………....14
3.1 磁振造影原理………………………………………………………………...14
3.2 擴散權重影像(Diffusion-weighted imaging，DWI)與b值(b factor)….....17
3.3 表觀擴散係數(Apparent diffusion coefficient，ADC)之原理…….……......20
第四章 材料與方法………………………………………………………………....21
4.1 研究對象……………………………………………………………………...21
4.2 磁振造影方法與流程…………………………………………………….…..23
4.2.1 MRI參數設定…………………………………………………..…...…23
4.2.2 Data量測及ROI圈選………………………………………………....25
4.2.3 目測法判別病灶DWI亮度……………………………………………27
4.3 統計分析……………………………………………………………….……..27
4.4 八種肝臟結節病灶在DWI及ADC的圖像………………………………….28
4.4.1 肝臟囊腫……………………..…………………………………………28
4.4.2 肝臟血管瘤………………..……………………………………………30
4.4.3 肝臟局部結節增生………………………..…………………………....32
4.4.4 肝臟再生不良結節…………..………………………….……………...34
4.4.5 肝臟膿瘍……………………..…………………………………………36
4.4.6 肝臟血管脂肪肌肉瘤…………………………..………………….…...38
4.4.7 肝細胞癌………………………………..…....…………………….…...40
4.4.8 肝臟轉移性腫瘤…………………………………..……………….…...42
第五章 結果與討論……………………………………………………….…….…..44
5.1 統計分析結果……………………………………………………….…………44
5.1.1 肝臟良性及惡性病灶在DWI中之SI差異…………………………..44
5.1.2 八種肝臟結節病灶在DWI中之SI差異……………………………..46
5.1.3 肝臟良性及惡性病灶在ADC map中之ADC值差異……………….48
5.1.4 八種肝臟結節病灶在ADC map中之ADC值差異………………….50
5.1.5 肝臟良性及惡性病灶之ADC ratio比值差異……………….…….…52
5.1.6 八種肝臟結節病灶之ADC ratio比值差異………..…..……….……54
5.1.7 以ROC分析八種肝臟病灶在ADC圖中差異之結果..........56
5.1.8 八種肝臟病灶在b=0、1000組合中之ADC值範圍及平均ADC值.57
5.1.9 以ADC值1.454區別八種肝臟病灶之結果…………………………59
5.1.10 以目測法分析病灶在DWI中亮度及以Kappa Test分析觀測者
間差異………………………………………………………………....61
5.2 討論……………………………………………………………………….…..65
第六章 結論與未來展望………………………………………………………...….70
6.1 結論…………………………………………………………….………….….70
6.2 未來展望………………………………………………………………….…..70
參考文獻………………………………………………………………………….….72



圖目錄
圖3-1 RF pulse開啟及關閉時氫核方向之變化………………………………...14
圖3-2 T1及T2遲緩時間之圖示………………………………………………...15
圖4-1 形狀規則之病灶ROI圈選圖示……………………………………….….26
圖4-2 不規則形狀之病灶ROI圈選圖示……………………………………..…26
圖4-3 Cyst在T2WI中的成像及在注射顯影劑後的成像.....28
圖4-4 Cyst在DWI中四個b值的成像...................29
圖4-5 Cyst在七組ADC圖中的成像..................29
圖4-6 Hemangioma在T2WI中的成像及在注射顯影劑後的動脈相..30
圖4-7 Hemangioma在DWI中四個b值的成像...........31
圖4-8 Hemangioma在七組ADC圖中的成像.............31
圖4-9 FNH在T2WI中的成像及在注射顯影劑後的動脈相....32
圖4-10 FNH在DWI中四個b值的成像..................33
圖4-11 FNH在七組ADC圖中的成像...................33
圖4-12 DN在Dual T1中的成像及在注射顯影劑後的動脈相..34
圖4-13 DN在DWI中四個b值的成像....................35
圖4-14 DN在七組ADC圖中的成像.....................35
圖4-15 Abscess在T2中的成像及在注射顯影劑後的動脈相..36
圖4-16 Abscess在DWI中四個b值的成像...............37
圖4-17 Abscess在七組ADC圖中的成像................37
圖4-18 AML在T2中的成像及在注射顯影劑後的動脈相......38
圖4-19 AML在DWI中四個b值的成像...................39
圖4-20 AML在七組ADC圖中的成像....................39
圖4-21 HCC在T2中的成像及在注射顯影劑後的動脈相......40
圖4-22 HCC在DWI中四個b值的成像...................41
圖4-32 HCC在七組ADC圖中的成像....................41
圖4-24 Metastasis在T2中的成像及在注射顯影劑後的動脈相..42
圖4-25 Metastasis在DWI中四個b值的成像............43
圖4-26 Metastasis在七組ADC圖中的成像.............43
圖5-1 肝臟良性病灶及惡性病灶在DWI中各b值之SI之曲線圖……………45
圖5-2 八種肝臟病灶在DWI中各b值之SI曲線圖……………………………47
圖5-3 肝臟良性及惡性病灶在七組ADC圖中的ADC值曲線圖……………...49
圖5-4 八種肝臟病灶在七組ADC圖中的ADC值曲線圖……………………...51
圖5-5 肝臟良性及惡性病灶的ADC ratio比值之曲線圖……………………....53
圖5-6 八種肝臟病灶的ADC ratio比值之曲線圖...........55



表目錄
表4-1 本研究收錄病患及病灶之相關數據……………………………………..22
表4-2 MR相關參數………………………………………………………………........24
表5-1 肝臟良性病灶及惡性病灶在DWI中各b值之訊號強度………………..45
表5-2 八種肝臟病灶在DWI中各b值之訊號強度……………………………..47
表5-3 肝臟良性及惡性病灶在七組ADC圖中的ADC值……………………..49
表5-4 八種肝臟病灶在七組ADC圖中的ADC值…………………………….51
表5-5 肝臟良性及惡性病灶的ADC ratio比值…………………………………53
表5-6 八種肝臟病灶的ADC ratio比值.................55
表5-7 以ROC分析八種肝臟病灶在七組ADC圖中差異之結果……56
表5-8 八種肝臟病灶之ADC值範圍及平均ADC值..........58
表5-9 以ADC Cut-off value:1.454來區分212個肝臟結節病灶之結果…60
表5-10 肝臟病灶在DWI中成像亮度之分級…………………………………….62
表5-11 肝臟病灶在DWI中b=0時亮度差異…………………………………..63
表5-12 肝臟病灶在DWI中b=100時亮度差異…………………………………63
表5-13 肝臟病灶在DWI中b=500時亮度差異………………………………….63
表5-14 肝臟病灶在DWI中b=1000時亮度差異……………………………….64

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