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
2、特征，可将皮质 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
3、 stain) of a normal adrenal gland specimen shows an outer capsule (C) and the cortical 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、-4 cm长。 On axial and coronal MR 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 kidn
5、ey and posterior to the pancreas; it has a triangular, inverted Y, or V configuration. Normal adrenal glands range from 2 to 6 mm in thickness and from 2 to 4 cm in length.,Figure 3. Coronal T1-weighted, threedimensional, GRE MR image obtained with VIBE shows the normal inverted Y shape of the right
6、 adrenal gland (arrow,三 MRI检查技术： 肾上腺成像最重要的是化学位移成像，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 Masses Fat-containing
7、adrenal masses can be classified into two main types: those 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-pha
8、se images owing to the presence of intracellular lipid. Adrenal lesions 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
9、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
10、 out-of-phase MR images show an adrenal adenoma (arrow), which exhibits the typical 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
11、，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，T1WI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 image shows an adrenal adenoma (black arrow) with a focal area 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
12、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：T1WI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 supp
13、ression and with fat suppression show typical MR imaging features of right adrenal myelolipoma. The fatty 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
14、 appearance of myelolipoma. There is fat and a maturing marrow element on the right side and an otherwise normal 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
15、，没有强化。,Figure 7. (a, b) Coronal T1-weighted in-phase and T2-weighted half-Fourier RARE MR images show an oval, well-circumscribed, right adrenal cyst (arrow in b) with a thin wall (arrowhead in b). The cyst has a typical appearance, showing low signal intensity at T1-weighted imaging and high signal
16、 intensity at T2-weighted imaging. Photomicrograph (original magnification, 100; H-E stain) shows a cystic lesion with a simple cuboidal 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
17、with inversion recovery shows a left adrenal pseudocyst. Note the soft-tissue component in the wall and the posteriorly located calcification (arrow). Photograph of the specimen shows a well-circumscribed cystic mass with abundant gummous tan material compressing the nearby kidney (arrowhead) withou
18、t infiltrating it or the surrounding soft tissue.,Figure 9. (a, b) Coronal T2-weighted MR image obtained with half-Fourier RARE and axial contrast- enhanced VIBE image show a left adrenal mass with areas of signal intensity similar to that of blood. Photograph of the specimen shows a hemorrhagic com
19、plicated adrenal cyst with hyalinized material.,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-weighted, three-dimensional, GRE MR image obtained with VIBE shows a lymphangioma, which has the typical appearance of a well-circumscribed are
20、a of low signal intensity. Photograph of the 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.
21、(ac) Axial T1-weighted in-phase MR image , out-of-phase MR image , and three-dimensional GRE contrast-enhanced MR image with VIBE show a pheochromocytoma (arrow). The pheochromocytoma shows the typical features of no loss of signal intensity on the out-of-phase image and intense enhancement on the c
22、ontrast-enhanced image. Photograph of sections of the resected specimen shows a typical, homogeneous, wellcircumscribed, tan-pink lesion, an appearance typical of pheochromocytoma.,七: Adreniform Adrenal Masses 1，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
23、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, adreniform masses (arrows), which represent adrenal 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
24、。 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 threedimensional GRE MR image obtained with VIBE demonstrates a right adrenal gland with a high-signal-intensity rim (arrows), a finding that is consistent with subacute hematoma.,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
25、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-e
26、nhanced 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 on the T1-weighted image and high signal intensity with a heterogeneous pattern of contra
27、st enhancement and areas of necrosis (arrow in b) on the T2-weighted image. Photograph of the specimen shows a yellow and red tumor with large areas of necrosis, findingstypical of adrenocortical carcinoma.,2， 肾上腺淋巴瘤 淋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.
28、 (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-phase 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。
29、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 from renal cell carcinoma, which has a central area of necrosis.,九，儿科肿瘤
30、 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。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
31、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-signal-intensity hemorrhage (arrow in a). The tumor is hyperi
32、ntense 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,
