肾上腺肿块MR的特征及诊断.ppt
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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
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
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