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1、肾上腺占位可根据细胞内脂质，肉眼可见的脂肪，出血和囊变，血供情况和肿瘤形态进行分类。这些特征可用于大部分肾上腺占位：腺瘤，增生，单纯或复杂囊肿，淋巴管瘤，髓样脂肪瘤，嗜铬细胞瘤,肾上腺出血，皮质腺癌，神经母细胞瘤，淋巴瘤和转移瘤。,一，组织学及解剖学肾上腺位于肾的上方，右侧肾上腺呈人字形，左侧呈半月形，右侧较左侧稍高。成人的每侧肾上腺重45g。肾上腺表面包以结缔组织被膜，少量结缔组织伴随血管和神经伸入腺实质内。肾上腺实质由周边的皮质和中央的髓质两部分构成，两者在发生、结构和功能上均不相同，皮质来自中胚层，髓质来自外胚层。皮质约占肾上腺体积的80%90%，根据皮质细胞的形态结构和排列等特征，可将
2、皮质分为三个带，即球状带、束状带和网状带。髓质主要由排列成索或团的髓质细胞组成，髓质细胞又称为嗜铬细胞(chromaffin cell)。另外，髓质内还有少量交感神经节细胞。肾上腺的血管分布：肾上腺上面有膈下动脉的终末分支，经肾上腺静脉出肾上腺。内侧面依次为肾上腺上中下动脉，分别起源于膈下动脉，腹主动脉，肾动脉。髓质内的小静脉汇合成一条中央静脉，最后汇入肾上腺静脉，右侧直接引入下腔静脉，左侧先与膈下静脉会合，尔后引入左肾静脉。,Figure 2.Photomicrograph(original magnification,40;hematoxylin-eosin H-E stain)of a
3、normal adrenalgland specimen shows an outer capsule(C)and thecortical layers:zona glomerulosa(G),fasciculata(F),and reticularis(R).The medulla(M)is present centrally.,二，正常肾上腺MRI表现：在轴位及冠状位MRI图像上，右侧肾上腺直接位于下腔静脉后方，右肾上极上方，呈线状，倒V或Y形。左侧肾上腺位于左肾上极前中部，胰腺后方，呈三角形，倒V或Y形。正常肾上腺2-6mm厚，2-4 cm长。On axial and coronal M
4、R images,the right adrenal gland is located immediately posterior to the inferior vena cava and superior to the upper pole of the right kidney.It has a linear,inverted V,or Y configuration(Fig 3).The left adrenal gland is anteromedial to the upper pole of the kidney and posterior to the pancreas;it
5、has a triangular,inverted Y,or V configuration.Normal adrenal glands range from 2 to 6 mm in thickness andfrom 2 to 4 cm in length.,Figure 3.Coronal T1-weighted,threedimensional,GRE MR image obtainedwith VIBE shows the normal inverted Yshape of the right adrenal gland(arrow,三 MRI检查技术：肾上腺成像最重要的是化学位移成
6、像，可以通过扰相GRE的inphase and out-of-phase来完成。常用序列如下：冠状位T2WI（应用半付利叶RARE技术，一次屏气）轴位TSE或FSE T2WI，一次屏气 冠状位和轴位GRE T1WI in-phase and out-of-phase 成像，一次屏气 在gadolinium增强前及后使用冠状位和轴位3-D GRE 序列(如：VIBE),屏气。,四：含脂肪肾上腺肿块Fat-containing Adrenal MassesFat-containing adrenal masses can be classified into two main types:thos
7、e that contain intracellular fat(eg,adenoma)and those with macroscopic fat(eg,myelolipoma).Adrenal masses that contain intracellular fat have been shown to lose signal intensity on chemical shift out-of-phase images compared with in-phase images owing to thepresence of intracellular lipid.Adrenal le
8、sions that contain macroscopic fat demonstrate a loss of signal intensity on fat-saturated images.A loss of signal intensity at chemical shift imaging can be seen at fat-water interfaces,typically at the borders of such lesions含脂肪肾上腺肿块分为两类：细胞内脂质（如腺瘤），肉眼可见脂肪（如髓样脂肪瘤）。含细胞内脂肪的肾上腺肿块在化学位移成像out-of-phase上信号
9、减低，含肉眼可见脂肪的肾上腺肿块在脂肪饱和成像序列上信号减低。在化学位移成像上信号减低能够 在脂水交界处发现，肿块边缘具有代表性。,1，肾上腺腺瘤肾上腺腺瘤是最常见肾上腺肿块，尸检发病率约3%。肾上腺腺瘤最重要的特征是细胞内脂质，化学位移成像是肾上腺腺瘤最可靠的检查手段。大部分肾上腺腺瘤在化学位移成像out-of-phase上信号减低，信号强度减低20%就可以诊断肾上腺腺瘤。,Figure 4.(a,b)Axial in-phase and out-of-phase MR images show an adrenal adenoma(arrow),which exhibits the typi
10、cal decrease in signal intensity on the out-of phase image.Photograph of the specimen shows a well-circumscribed bright yellow nodule,an appearance that is typical of adrenocortical adenoma.,增强时均匀一致强化也是肾上腺腺瘤的特征，肾上腺腺瘤小的，圆点状信号强度改变可能是由于囊变，出血或血供的差异。肾上腺腺瘤出血少见，出血不同时期有不同MRI表现，急性期T1WI和肌肉信号相近，T2WI低信号。亚急性期，T1
11、WI高信号，T2WI开始低信号，随后呈高信号。慢性出血均为低信号。,Figure 5.Axial T1-weighted out-of-phase MR imageshows an adrenal adenoma(black arrow)with a focalarea of high-signal-intensity hemorrhage(white arrow).,2，髓样脂肪瘤髓样脂肪瘤是不常见的良性肿瘤。由成熟脂肪组织和造血组织构成。大部分是在偶然时发现。在非压脂T1WI上脂肪成分为高信号，压脂脂肪成信号减低能够帮助诊断。髓样脂肪瘤根据MR信号特征分为三类：1)以脂肪成分为主型：T1W
12、I均匀高信号，T2WI中等信号。2)脂肪和髓样成分混合型：T2WI和T1WI增强上脂肪信号混杂高信号区域。3)髓样成分为主型：相对于肝脏，T1WI低信号，T2WI高信号，增强有强化。髓样脂肪瘤可以很大，并有症状，可以继发出血。巨大髓样脂肪瘤要和腹膜后像脂肪肉瘤鉴别。,Figure 6.(a,b)Axial T1-weighted MR images obtained without fat suppression and with fat suppression show typical MR imaging features of right adrenalmyelolipoma.The f
13、atty component of the myelolipoma(arrow in a)shows a decrease in signal intensity on the fat-suppressed image.Photomicrograph(original magnification,100;H-E stain)shows the typical microscopic appearance of myelolipoma.There is fat and a maturing marrow element on the right side and an otherwise nor
14、mal adrenal cortex on the left.,五，囊性肿块肾上腺囊肿罕见，经常是偶然发现或尸检发现，尸检发病率约0.064%0.18%。大部分情况下无症状，但是囊肿巨大时，可出现疼痛，并可触及肿块。囊肿出血，破裂或感染时出现急性症状。,1，单纯囊肿内皮囊肿是肾上腺囊肿最常见的亚型。占肾上腺囊肿约40%。单纯囊肿T1WI低信号T2WI高信号，没有软组织成分，没有强化。,Figure 7.(a,b)Coronal T1-weighted in-phase and T2-weighted half-Fourier RARE MR imagesshow an oval,well-ci
15、rcumscribed,right adrenal cyst(arrow in b)with a thin wall(arrowhead in b).The cysthas a typical appearance,showing low signal intensityat T1-weighted imaging and high signal intensity atT2-weighted imaging.Photomicrograph(originalmagnification,100;H-E stain)shows a cystic lesionwith a simple cuboid
16、al mesothelial lining.,2，假性囊肿假性囊肿是肾上腺囊性肿块中第二多见。占肾上腺囊肿约39%。假性囊肿没有上皮，MRI表现复杂，有分隔，血液成分和软组织，可继发出血和透明样变，外周可有线样钙化，但MRI难以显示。,Figure 8.Axial T2-weighted MR image obtained with inversion recovery shows a left adrenal pseudocyst.Notethe soft-tissue component in the wall and the posteriorly located calcificati
17、on(arrow).Photograph of the specimenshows a well-circumscribed cystic mass with abundant gummous tan material compressing the nearby kidney(arrowhead)without infiltrating it or the surrounding soft tissue.,Figure 9.(a,b)Coronal T2-weighted MR imageobtained with half-Fourier RARE and axial contrast-e
18、nhanced VIBE image show a left adrenalmass with areas of signal intensity similar to that ofblood.Photograph of the specimen shows a hemorrhagiccomplicated adrenal cyst with hyalinizedmaterial.,3，淋巴管瘤肾上腺囊性的淋巴管瘤罕见，没有症状。MRI图像特征与身体其他部位淋巴管瘤表现一样。表现为具有薄壁的T1WI低信号T2WI高信号，没有软组织成分，没有强化。,Figure 10.Coronal T1-w
19、eighted,three-dimensional,GRE MR image obtained with VIBE shows a lymphangioma,which has the typical appearance of a well-circumscribed area of low signal intensity.Photograph ofthe specimen shows the thin-walled lymphangioma.,六，富血供病变嗜铬细胞瘤，起源于肾上腺髓质嗜铬细胞，没有胞浆内脂质成分，所以在GRE化学位移成像out-of-phase上信号不减低，大部分嗜铬细
20、胞瘤在T2WI上呈 高信号（“灯泡征”），但是不能作为诊断或排除嗜铬细胞瘤的特征。因为一部分嗜铬细胞瘤也表现出中等信号。大部分嗜铬细胞瘤增强时明显强化。嗜铬细胞瘤也被称为“10%肿瘤”。10%双侧，10%肾上腺外，10%发生于小孩，10%为恶性。,Figure 11.(ac)Axial T1-weighted in-phase MR image,out-of-phase MR image,and three-dimensionalGRE contrast-enhanced MR image with VIBE show a pheochromocytoma(arrow).The pheochr
21、omocytomashows the typical features of no loss of signal intensity on the out-of-phase image and intense enhancement on thecontrast-enhanced image.Photograph of sections of the resected specimen shows a typical,homogeneous,wellcircumscribed,tan-pink lesion,an appearance typical of pheochromocytoma.,
22、七:Adreniform Adrenal Masses1，肾上腺皮质增生肾上腺皮质增生常见于Cushing综合症。肾上腺皮质增生可以是弥漫性和结节性，常发生于两侧。肾上腺皮质增生信号和正常肾上腺相近，在out-of-phase上信号减低（尤其是在呈腺瘤样结节患者上）。两侧肾上腺皮质增生占Cushing综合症的45%，结节性肾上腺皮质增生仅占3%。,Figure 12.(a,b)Coronal in-phase and out-ofphase MR images show bilateral large,adreniformmasses(arrows),which represent adren
23、al cortical hyperplasia.,2，肾上腺出血肾上腺出血可出现于创伤，肾上腺静脉血拴，应激，低血压及其他各种出血因素，肾上腺机能不全(Addison disease)是双侧肾上腺出血的继发因素。MRI是肾上腺出血最敏感和最有效的检查手段，根据不同的出血时期有不同的表现。,Figure 13.Axial unenhanced T1-weighted threedimensionalGRE MR image obtained with VIBE demonstratesa right adrenal gland with a high-signal-intensityrim(ar
24、rows),a finding that is consistent with subacutehematoma.,八，恶性肿瘤1，肾上腺皮质腺癌原发肾上腺皮质腺癌十分罕见，发病率约百万分之二。高峰年龄为30-70岁，一般诊断时肿瘤比较大，约6-20cm。肾上腺皮质腺癌可以表现机能亢进，引起Cushing综合症或Conn综合症（又称原发醛固酮增多症），其他表现为腹痛和腹部肿块。由于出血和坏死肾上腺皮质腺癌在T1WI和T2WI上有不同表现，出血后演化产物，主要是正铁血红蛋白，能够引起T1WI高信号。坏死能够引起T2WI高信号。肾上腺皮质腺癌可以有点状细胞内脂肪，在out-of-phase上信号减
25、低。较大肾上腺皮质腺癌能够侵犯肾上腺静脉和下腔静脉。,Figure 14.(a,b)Sagittal T1-weighted threedimensional contrast-enhanced GRE MR image obtained with VIBE and coronal T2-weighted MR image obtained with half-Fourier RARE show a large mass involving the right adrenal gland.The mass exhibits heterogeneous low signal intensity
26、on the T1-weighted image and high signal intensity with a heterogeneous pattern of contrast enhancement and areas of necrosis(arrow in b)on the T2-weighted image.Photograph of the specimen shows a yellowand red tumor with large areas of necrosis,findingstypical of adrenocortical carcinoma.,2，肾上腺淋巴瘤淋
27、巴瘤偶尔也可累及肾上腺，以非何杰金淋巴瘤多见，通常双侧受累，占50%。肾上腺淋巴瘤T1WI上低信号和T2WI上不均匀高信号。增强后轻微强化。,Figure 15.(a,b)Axial T1-weighted in-phase and out-of-phase MR images show bilateral lymphomatous deposits.The deposits have low signal intensity,and the signal intensity does not decrease on the out-ofphase compared with the in-p
28、hase image.,3，转移转移病变是肾上腺最常见的恶性肿瘤，尸检发现27%患恶性上皮肿瘤有肾上腺转移。原发部位一般有：肺，肠道，乳腺，胰腺。一般为双侧，也可单侧。MRI T1WI上低信号和T2WI上高信号。增强后逐渐强化。没有在out-of-phase上信号减低的特性（和腺瘤鉴别）。,Figure 16.(a,b)Axial T2-weighted MR image obtained with inversion recovery and contrast-enhanced T1-weighted MR image obtained with VIBE show metastasis f
29、rom renal cell carcinoma,which has a central area of necrosis.,九，儿科肿瘤神经母细胞瘤是小儿最常见的颅外实性肿瘤，其他肾上腺肿瘤，如：嗜铬细胞瘤,皮质腺癌，淋巴瘤十分罕见。1，神经母细胞瘤神经母细胞瘤是第二常见腹部肿瘤（在Wilms tumor之后）。占小儿恶性肿瘤的5%-15%。起源于肾上腺髓质的神经脊或沿交感神经连。神经母细胞瘤临床一般无症状，除非侵犯或压迫临近组织，转移或其他。神经母细胞瘤T1WI上不均匀低信号和T2WI上不均匀高信号。增强后强化。神经母细胞瘤80-90%有钙化，但MRI难以显示。出血区域引起T1WI高信号。
30、坏死区域能够引起T2WI高信号。MRI在显示肿块上臂CT有优势，在于MRI高软组织分辨率，多方位成像，以及能清楚显示肿瘤成分。,Figure 17.(a,b)Coronal unenhanced T1-weighted MR image and axial T2-weighted MR image obtained with inversion recovery show a right adrenal tumor.The tumor is predominantly hypointense on the T1-weighted image and has areas of high-sign
31、al-intensity hemorrhage(arrow in a).The tumor is hyperintense on the T2-weighted image.,，节细胞神经母细胞瘤 其潜在恶性度介于神经母细胞瘤和节细胞神经瘤之间。和神经母细胞瘤一样，起源于神经脊。节细胞神经母细胞瘤T1WI上中等信号和T2WI上不均匀高信号。增强后不均匀强化。,Figure 18.Axial in-phase T1-weighted MR image shows a heterogeneous mass with intermediate signal intensity involving the right adrenal gland.Photograph of the specimen shows a dark brown to tan lobulated ganglioneuroblastoma with areas of necrosis and compression of the adjacent kidney.There is a rim of residual yellow cortex,
