1、Characterizing solid renal neoplasms with MRI in adults,成人实性肾肿瘤的MRI特征,Introduction,In order to accurately classify a solid renal neoplasm, a systematic approach is recommended, including attention to clinical and laboratory data, lesion location and number, lesion signal intensity and composition, e
2、nhancement pattern, and diffusivity. Because no single feature in isolation is definitively diagnostic of a particular type of neoplasm, the individual characteristics of a renal mass must then be combined to narrow the differential diagnosis or suggest a most likely histology. 为了准确的鉴别实性肾肿瘤，在此推荐一种系统
3、的方法，包括临床和实验室数据、病变位置和数量、病变信号强度和成分、强化类型及弥散情况。由于没有某个单独的特称可用于诊断某一类型的肿瘤，因此肾脏肿瘤的多种特征必须结合起来缩小鉴别诊断的范围或者推断出最为可能的组织学类型。,Imaging protocol 成像序列,MR imaging is generally performed with a phased-array body coil with the patient supine. A typical renal MRI protocol begins with a coronal localizer using a fast seque
4、nce such as single-shot turbo/fast spin echo. This provides an anatomic overview of the abdomen and allows depiction of contour abnormalities at the renal poles. Axial dual gradient-echo T1-weighted (in-phase and opposed-phase) imaging is performed with the longer echo time (TE) assigned to the in-p
5、hase echo. In-phase and opposed-phase imaging allows detection of fat and intracytoplasmic lipid/glycogen or hemosiderin within renal masses. MRI扫描通常体线圈，病人仰卧位。扫描序列包括首先扫描的冠状位，提供了腹部的解剖概况并发现肾脏外形的异常。T1WI（正、反相位）可监测肿块内的脂肪、胞浆内的脂类/糖原或含铁血黄素。,These components can provide clues regarding the benign or malignan
6、t nature of a solid renal mass or provide a hint as to the subtype of RCC. Subtle changes in signal intensity between in- and opposed-phase images can often be better appreciated with subtraction imaging. If a Dixon method is used, fat-only and water-only images will be automatically generated and c
7、an also be helpful in identifying regions of microscopic and macroscopic fat. 这些信息可以提供良恶性肿块的线索或者肾细胞癌亚型的提示。正反相位中信号强度的微小变化可以在减影图中更好的显示。如果使用的是“Dixon”成像，“脂像”和“水像”可以自动生成，这也有助于确定局部微观和宏观的脂肪成分。,50岁男性，透明细胞癌患者，肿瘤内含有少量脂肪,A 轴位T2压脂序列示右肾可见一信号混杂肿块，与肾实质比主要为低信号；B 轴位T1正相位示肿块内可见模糊高信号影；C T1反相位示肿块与肾实质呈等信号难以鉴别，说明在正反相位间肿块
8、内存在信号差异；D减影图确认信号差异是由于脂肪成分；E增强压脂T1（动脉期）示肿块与肾实质呈等样强化。血管平滑肌脂肪瘤和透明细胞癌都可在考虑之内，但病变信号混杂性加上相对高的发病率，透明细胞癌的可能性更大一些。,72岁女性，血管平滑肌脂肪瘤患者,A 轴位T1反相位示右肾外伸性肿块，注意箭头所示细长环形低信号影（由于脂肪软组织界面存在），其上为出血；B Dixon序列脂像肿块内小范围脂肪组织；C增强压脂T1示（肾实质期）肿块呈蘑菇型伴部分突入肾实质内，肿块前方非增强区域为出血。,Fat-suppressed T2-weighted images in the axial plane are he
9、lpful for detecting and characterizing cystic lesions and revealing perinephric edema and fluid collections. Complex cysts containing hemorrhagic or proteinaceous fluid are variable in signal intensity on T2-weighted images and can be confused with solid masses unless pre-and post-contrast T1-weight
10、ed images are reviewed. 轴位T2压脂序列有助于检测和定性囊性病变以及显示肾周水肿和积液。包含出血或蛋白的复杂成分囊肿在T2WI上信号复杂，有时会误认为实性肿块，此时需在增强前后的T1WI上鉴别。,The signal intensity of a solid renal mass on T2-weighted imaging can assist in narrowing the differential diagnosis; however, when developing a renal MRI protocol, keep in mind that gadolin
11、ium-based contrast agents (GBCAs) can alter the relative signal intensity of a mass compared to normal renal parenchyma on a T2-weighted image. Therefore, it can be helpful to perform at least one T2-weighted sequence prior to intravenous contrast administration. 实性肿块的T2WI信号强度可有助于缩小鉴别诊断。然而，造影剂可以改变肿块
12、的T2信号强度，因此，在注射造影剂前应至少扫描一个T2序列。,We include diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) maps in our renal mass protocol, as certain solid neoplasms, such as papillary RCC (pRCC), urothelial carcinoma, and lymphoma often demonstrate relatively low ADC values compared with
13、 normal renal parenchyma. Because renal parenchyma can appear relatively bright on a diffusion-weighted image performed with a low to intermediate b-value, we routinely include at least one acquisition with a b-value of 8001000 s/mm2 to enhance the conspicuity of potential renal neoplasms. DWI和ADC图也
14、需要加入肾脏肿块的扫描序列中，例如乳头状肾癌、尿路上皮癌和淋巴瘤与正常肾实质相比常表现为相对低的ADC值。由于肾实质在低到中b值的DWI上呈较高信号，因此常规应包括一个8001000 s/mm2 b值的扫描，来强化潜在肾肿瘤的对比度。,70岁男性，肾门处淋巴瘤,A压脂T2示肾窦中心可见一较大均匀侵润性低信号肿块影；B T1示病变内未见脂肪或出血信号；C DWI（b= 1000 s/mm2）示肿块明显弥散受限呈高信号；D ADC图肿块呈低信号影；E增强压脂T1（皮髓质期）示肿块轻度均匀强化，箭头示肿块包绕肾动脉。,Multiphase contrast enhanced imaging can
15、be performed in the axial or coronal plane, depending on personal preference, using a 3-dimensional, fat-suppressed T1-weighted gradient echo sequence. Enhancement pattern on multiphase MRI is a potential discriminator between renal neoplasms. Precontrast imaging helps to identify T1 hyperintense he
16、morrhagic or proteinaceous material within or around a renal mass. Intrinsically bright material on a T1-weighted image can interfere with identifying contrast enhancement and may necessitate subtraction imaging. Therefore, careful breath-holding instructions are critical to ensure that pre- and pos
17、t-contrast enhanced images are identically registered. 多期增强可运用压脂T1WI序列行轴位或冠位成像。强化类型可用于鉴别不同的肾肿瘤。蒙片有助于确认病变内或周围的出血或蛋白成分。T1WI上固有的高信号成分可以对确认强化程度造成干扰，因此也许需要减影图。认真的闭气指令对于确保增强前后的图像定位一致也十分重要。,Clinical and laboratory data 临床和实验检查数据,Clinical data can sometimes narrow or alter the differential diagnosis of a re
18、nal mass, or when combined with imaging features, suggest a most likely diagnosis. A variety of genetic syndromes are associated with renal neoplasms of a particular histopathology, and preexisting knowledge of such a disorder alerts the radiologist to consider specific types of renal neoplasms in t
19、he differential diagnosis. In addition to those listed in Table1, other associations exist between a clinical condition and a specific type of renal neoplasm. 临床数据有助于缩短或者改变一个肾脏肿块的鉴别诊断，有时结合影像学特征，可以得出最可能的诊断。多种遗传综合征会与某个特定病理类型的肾肿瘤相关，如果一个影像科医生事先知道这一障碍会提醒其在鉴别诊断时考虑某种类型的肿瘤。除了在下表中所列出的，还存在有其他临床病症与肿瘤类型的相关性。,Fo
20、r example, the possibility of post-transplant lymphoproliferative disorder should be considered in an immunosuppressed transplant patient with a renal mass, and metastatic disease should be considered in a patient with multiple or atypical appearing lesions and a history of advanced extrarenal malig
21、nancy. 例如，移植后淋巴组织增生的可能性应在一个接受免疫抑制治疗的移植患者中考虑，而多发或非典型表现的病变伴有肾外恶性肿瘤病史者应考虑转移性疾病。,62岁女性，肾脏转移癌,A 周围T2示左上肾极可见一与肾实质信号相近的小肿块影；B DWI高b值（b=500）上显示更明显；C 压脂增强T1（皮髓质期）示肿块呈边缘强化；D 压脂增强T1（肾实质期）示肿块呈中心强化。由于临床上怀疑转移性疾病，对此肿块进行了活检,Occasionally, laboratory abnormalities can point to a specific diagnosis. Renal cell carcino
22、ma can be associated with a variety of paraneoplastic syndromes, some of which induce laboratory abnormalities such as elevated liver enzymes and polycythemia. Polycythemia has also been linked to some cases of metanephric adenoma. Some mesenchymal tumors, such as solitary fibrous tumor, can produce
23、 an insulin-like growth factor that can result in hypoglycemia. 有时实验室检查异常也可以指向某一特定诊断。肾细胞癌可与各种副肿瘤综合征有关，其中的一些可以导致实验室检查异常诸如肝酶升高和红细胞增多症。红细胞增多症某些情况下与后肾腺瘤也有关。一些间质肿瘤，如孤立性纤维性肿瘤，可产生胰岛素样生长因子，可能导致低血糖症。,Discriminatory imaging features on MRI MRI影像学特征,The ability to accurately characterize solid renal neoplasms
24、with MRI in part depends on ones ability to identify key imaging features and combine those features to generate a most likely diagnosis or a short list of differential considerations. In this section, we review MR imaging features that can help guide the interpreting physician to a most likely diag
25、nosis (Table2). Of course, there are exceptions to every rule, and many tumors will defy definitive imaging characterization due to apparently discordant findings or a paucity of discriminatory features. 运用MRI准确的定性实性肾脏肿瘤部分需要找到关键的图像特征并且结合这些特征来做出最为相近的诊断或者缩小鉴别诊断的范围。在这个部分将总结这些表现特征。当然，也会出现一些例外，很多肿瘤会表现出不典型特征。,
