EVALUATION OF CIRRHOTIC LIVER WITH PERFUSION-WEIGHTED MAGNETIC RESONANCE IMAGING:A PRELIMINARY EXPERIMENTAL STUDY IN ANIMAL MODELS WITH HALF-LIVER CIRRHOSIS

Objective To investigate the role of peffusion-weighted magnetic resonance imaging （MRI） in evaluation of cirrhotic fiver. Methods With a 4F catheter, 1% diluted carbon tetrachloride （ 1 ml/kg） was selectively injected into fight or left hepatic artery of 12 dogs fortnightly. The half fiver into which carbon tetrachloride was injected was called as study side （SS）, while the other half fiver without carbon tetrachloride injection was called as study control side （SCS）. Conventional and peffusion-weighted MRI were performed in every 4 weeks. Via a 4F catheter, 5ml gadolinium diethylentriamine pentaaceti acid （Gd-DTPA） dilution was injected into superior mesenteric artery at the 5th scan. The signal intensity-thne curves of SS, SCS, and portal vein were completed in MR workstation. The maximal relative signal increase （ MRSI）, peak time （ tp）, and slope of the curves were measured. Results On conventional MR images, no abnormalities of externality and signal intensity were observed in both SS and SCS of fiver at each stage. The mean tp, MP, SI, and slope of intensity-time curves in normal fiver were 10. 56 seconds, 1.01, and 10. 23 arbitrary unit （au）/s, respectively. Three parameters of curves didn＇t show obvious change in SCS of fiver at every stage. Abnormal perfusion curves occurred in SS of fiver at the 12th week after the 1st injection. The abnormality of perfusion curve in SS was more and more serious as the times of injection increased. The mean tp, IVlRSI, and slope intensity-time curves in SS of fiver were 19.45 seconds, 0. 43, and 3. 60 au/s respectively at the 24th week. Conclusion Perfusion-weighted imaging can potentially provide information about portal peffusion of hepatic parenchyma, and to some degree, reflect the severity of cirrhosis.

Functional magnetic resonance imaging in an animal model of pancreatic cancer

AIM: To test the hypotheses that diffusion weighed (DW)and transcatheter intraarterial perfusion (TRIP)magnetic resonance imaging (MRI) can each be used to assess regional differences in tumor function in an animal pancreatic cancer model.METHODS: VX2 tumors were implanted in pancreata of 6 rabbits. MRI and digital subtraction angiography (DSA) were performed 3 wk following implantation. With a 2-French catheter secured in the rabbit's gastroduodenal artery, each rabbit was transferred to an adjacent 1.5T MRI scanner. DWand TRIP-MRI were performed to determine if necrotic tumor core could be differentiated from viable tumor periphery. For each, we compared mean differences between tumor core/ periphery using a 2-tailed paired t-test (α = 0.05). Imaging was correlated with histopathology. RESULTS: Tumors were successfully grown in all rabbits, confirmed by necropsy. On DW-MRI, mean apparent diffusion coeffi cient (ADC) value was higher in necrotic tumor core (2.1 ± 0.3 mm2/s) than in viable tumor periphery (1.4 ± 0.5 mm2/s) (P < 0.05). On TRIP-MRI, mean perfusion values was higher in tumor periphery (110 ± 47 relative units) than in tumor core (66 ± 31 relative units) (P < 0.001). CONCLUSION: Functional MRI can be used to differentiate necrotic from viable tumor cells in an animal pancreatic cancer model using ADC (DW-MRI) and perfusion (TRIP-MRI) values.

Evaluation of a rabbit rectal VX2 carcinoma model using computed tomography and magnetic resonance imaging

AIM： To establish a rabbit rectal VX2 carcinoma model for the study of rectal carcinoma.METHODS： A suspension of VX2 cells was injected into the rectum wall under the guidance of X-ray fluoroscopy. Computed tomography （CT） and magnetic resonance imaging （MRI） were used to observe tumorgrowth and metastasis at different phases. Pathological changes and spontaneous survival time of the rabbits were recorded.RESULTS： Two weeks after VX2 cell implantation, the tumor diameter ranged 4.1-5.8 mm and the success implantation rate was 81.8%. CT scanning showed low-density loci of the tumor in the rectum wail, while enhanced CT scanning demonstrated a symmetrical intensification in tumor loci. MRI scanning showed alow signal of the tumor on T1-weighted imaging anda high signal of the tumor on T2-weighted imaging.Both types of signals were intensified with enhanced MRI. Metastases to the liver and lung could beobserved 6 wk after VX2 cell implantation, and a largearea of necrosis appeared in the primary tumor. The spontaneous survival time of rabbits with cachexia and multiple organ failure was about 7 wk after VX2 cell implantation.CONCLUSION： The rabbit rectal VX2 carcinoma model we established has a high stability, and can be used in the study of rectal carcinoma.

Multiparameter magnetic resonance imaging of liver fibrosis in a bile duct ligation mouse model

BACKGROUND Bile duct ligation(BDL)in animals is a classical method for mimicking cholestatic fibrosis.Although different surgical techniques have been described in rats and rabbits,mouse models can be more cost-effective and reproducible for investigating cholestatic fibrosis.Magnetic resonance imaging(MRI)has made great advances for noninvasive assessment of liver fibrosis.More comprehensive liver fibrotic features of BDL on MRI are important.However,the utility of multiparameter MRI to detect liver fibrosis in a BDL mouse model has not been assessed.AIM To evaluate the correlation between the pathological changes and multiparameter MRI characteristics of liver fibrosis in a BDL mouse model.METHODS Twenty-eight healthy adult male balb/c mice were randomly divided into four groups:sham,week 2 BDL,week 4 BDL,and week 6 BDL.Multiparameter MRI sequences,included magnetic resonance cholangiopancreatography,T1-weighted,T2-weighted,T2 mapping,and pre-and post-enhanced T1 mapping,were performed after sham and BDL surgery.Peripheral blood and liver tissue were collected after MRI.For statistical analysis,Student’s t-test and Pearson’s correlation coefficient were used.RESULTS Four mice died after BDL surgery;seven,six,five and six mice were included separately from the four groups.Signal intensities of liver parenchyma showed no difference on TI-and T2-weighted images.Bile duct volume,ΔT1 value,T2 value,and the rate of liver fibrosis increased steadily in week 2 BDL,week 4 BDL and week 6 BDL groups compared with those in the sham group(P<0.01).Alanine aminotransferase and aspartate transaminase levels initially surged after surgery,followed by a gradual decline over time.Strong correlations were found between bile duct volume(r=0.84),T2 value(r=0.78),ΔT1 value(r=0.62),and hepatic fibrosis rate(all P<0.01)in the BDL groups.CONCLUSION The BDL mouse model induces changes that can be observed on MRI.The MRI parameters correlate with the hepatic fibrosis rate and allow for detection of cholestatic fibrosis.

Large animal ischemic stroke models: replicating human stroke pathophysiology

The high morbidity and mortality rate of ischemic stroke in humans has led to the development of numerous animal models that replicate human stroke to further understand the underlying pathophysiology and to explore potential therapeutic interventions.Although promising therapeutics have been identified using these animal models,with most undergoing significant testing in rodent models,the vast majority of these interventions have failed in human clinical trials.This failure of preclinical translation highlights the critical need for better therapeutic assessment in more clinically relevant ischemic stroke animal models.Large animal models such as non-human primates,sheep,pigs,and dogs are likely more predictive of human responses and outcomes due to brain anatomy and physiology that are more similar to humans-potentially making large animal testing a key step in the stroke therapy translational pipeline.The objective of this review is to highlight key characteristics that potentially make these gyrencephalic,large animal ischemic stroke models more predictive by comparing pathophysiological responses,tissue-level changes,and model limitations.

Magnetic resonance imaging:A new tool for diagnosis of acute ischemic colitis?

AIM： To define the evolution of ischemic lesions with 7T magnetic resonance imaging （7T-MRI） in an animal model of acute colonic ischemia. METHODS： Adult Sprague-Dawley rats were divided into two groups. Group I underwent inferior mesenteric artery （IMA） ligation followed by macroscopic observa- tions and histological analysis. In group H, 7T-MRI was performed before and after IMA ligation and followed by histological analysis. RESULTS： Morphological alterations started to develop 1 h after IMA ligation, when pale areas became evident in the splenic flexure mesentery and progressively wors-ened up to 8 h thereafter, when the mesentery was less pale, and the splenic flexure loop appeared very dark. The 7T-MRI results reflected these alterations, showing a hyperintense signal in both the intraperitoneal space and the colonic loop wall 1 h after IMA ligation; the lat- ter progressively increased to demonstrate a reduction in the colonic loop lumen at 6 h. Eight hours after IMA ligation, MRI showed a persistent colonic mural hyper- intensity associated with a reduction in peritoneal free fluid. The 7T-MRI findings were correlated with histolog- ical alterations, varying from an attenuated epithelium with glandular apex lesions at 1 h to coagulative necro- sis and loss of the surface epithelium detected 8 h after IMA ligation. CONCLUSION： MRI may be used as a substitute for invasive procedures in diagnosing and grading acute ischemic colitis, allowing for the early identification of pathological findings.

Magnetic resonance imaging of hepatocellular carcinoma induced by diethylnitrosamine in Sprague-Dawley rats

Diethylnitrosamine (DENA) is able to induce various benign and malignant liver lesions in rats with a high success rate and a low mortality rate. It provides a more appropriate model that better simulates the various lesions occurring in humans than the usual model of tumor implantations. The aim of the present study was to evaluate MRI liver examination in Sprague-Dawley(SD) rats as a routine method to detect hepatocellular carcinoma (HCC) nodules induced by DENA and to follow up their growth. METHODS:Hepatic carcinogenesis was induced in 80 male SD rats using oral DENA solution. All animals were imaged for liver tumor detection with a 1.5 Tesla magnet (Siemens Sonata,Erlangen, Germany) using correspondence scan parameters and a radio-frequency knee coil. Macroscopic examinations were performed along the axial MRI sections to evaluate magnetic resonance imaging (MRI) findings, and histopathological assessment was also performed. RESULTS:No false negative results were obtained on MR images. Hepatic tumors in 72 rats were confirmed macro-scopically and 68 rats were detected by MRI till the 20th week. The smallest and the largest nodules detected by MRI were 2 mm and 37 mm in diameter respectively. The agreement rate of MRI with macroscopic observation was 39. 1% and 97. 4% respectively for 2 mm to 5 mm and more than 5 mm nodules. CONCLUSIONS:The hepatic tumor induced by DENA provides a more representative range of tumors for imaging diagnosis and interventional treatment. MRI is the best approach for scrutinizing pathological changes of rat livers in the period of observation.

基于多模态影像学的轻度创伤性脑损伤脑功能评估的研究进展

轻度创伤性脑损伤(mild traumatic brain injury,mTBI)具有病理生理复杂、早期诊断难、伴有不同程度脑功能障碍等特点,需早期干预才能有效恢复如注意力不集中、记忆力减退等脑功能障碍。上述功能障碍与大脑默认网络、海马、基底节等脑区功能异常密切关联,而影像学可以准确量化评估这些脑功能区的改变。高场强磁共振成像技术的出现,使得影像学成为mTBI临床早期诊断与临床治疗评估的关键技术。基于mTBI动物模型及临床患者,本文从磁共振成像中反映工作记忆的动脉自旋回波、反映认知缺陷的弥散张量成像、反映淋巴转运异常的超高场强磁共振增强成像以及反映颅脑冲击伤损伤程度的正电子发射计算机断层扫描术与脑电图等方面作一综述,旨在为mTBI军事医学研究提供参考。

The pig as a preclinical traumatic brain injury model:current models,functional outcome measures,and translational detection strategies

Traumatic brain injury(TBI) is a major contributor of long-term disability and a leading cause of death worldwide. A series of secondary injury cascades can contribute to cell death, tissue loss, and ultimately to the development of functional impairments. However, there are currently no effective therapeutic interventions that improve brain outcomes following TBI. As a result, a number of experimental TBI models have been developed to recapitulate TBI injury mechanisms and to test the efficacy of potential therapeutics. The pig model has recently come to the forefront as the pig brain is closer in size, structure, and composition to the human brain compared to traditional rodent models, making it an ideal large animal model to study TBI pathophysiology and functional outcomes. This review will focus on the shared characteristics between humans and pigs that make them ideal for modeling TBI and will review the three most common pig TBI models–the diffuse axonal injury, the controlled cortical impact, and the fluid percussion models. It will also review current advances in functional outcome assessment measures and other non-invasive, translational TBI detection and measurement tools like biomarker analysis and magnetic resonance imaging. The use of pigs as TBI models and the continued development and improvement of translational assessment modalities have made significant contributions to unraveling the complex cascade of TBI sequela and provide an important means to study potential clinically relevant therapeutic interventions.

Establishment of orthotopic transplantation model of human bladder cancer and detection by MRI

Objective: To establish an orthotopic bladder cancer model bearing human bladder cancer for experimental research, and monitor tumor progression by magnetic resonance imaging (MRI). Methods: The mucosa was mechanically damaged transurethrally under direct vision, and then human bladder cancer cell line T24 was inoculated into the bladders of BALB/c nude mice to establish orthotopic bladder cancer model. To find a suitable concentration of Gd-DTPA for this re- search. MRI was performed weekly to assess tumor growth, using Gd-DTPA as contrast agent. The pathologic morphology of the bladders and other specimens were observed with HE stain. Results: All the 25 mice developed bladder cancer after inoculation. The best concentration of Gd-DTPA was 1.408 mg/mL. On MRI, no change in the bladders was observed on day 7 after inoculation, filling defect in the bladders, accordant to actual tumor size, was detected on days 14, 21 and 28. Pathologic examination showed that tumor grew in the mucosa or superficial muscle of bladder on day 7, confined in muscle layer on days 14–28, and invaded serosa on day 35. Conclusion: Transurethrally damaged bladder mucosa under direct vision and instilled bladder cancer cell T24, we successfully established an orthotopic bladder cancer model. Tumor growth simulated the progression of human bladder cancer approximately. MRI was a reliable way for dynamic detection of murine orthotopic bladder tumor.

胃癌组织肾筋膜下NOD/SCID小鼠移植瘤模型的建立及其MRI表现

目的采用内镜下活检胃癌组织块肾筋膜下移植法建立NOD/SCID小鼠胃癌异位移植瘤模型,观察其MRI表现,为研究胃癌个体化治疗临床前实验提供适宜的动物模型。材料与方法将2020年12月—2021年2月在兰州大学第二医院经病理及影像确诊的9例晚期胃癌患者内镜下活检的约1 cm3新鲜肿瘤组织种植到NOD/SCID小鼠右侧肾筋膜下。种植后每周行1次MRI检查至发现肾筋膜下成瘤,继续观察4周,采用T2WI序列测量并计算肿瘤体积,然后处死小鼠,取出瘤组织,将游标卡尺测量的肿瘤体积与最后一次MRI测量结果进行对比,并对移植瘤进行病理学检查。结果异位移植瘤T1WI呈等低混杂信号,T2WI呈等高信号,增强后明显不均匀强化,肿瘤向前挤压肾脏变形。MRI与游标卡尺测量肿瘤体积分别为(512.12±25.52)mm^(3)、(506.95±29.24)mm^(3),差异无统计学意义(t=0.808,P=0.436)。病理结果显示移植前后肿瘤组织学保持一致性。结论本研究建立的胃癌异位移植瘤模型保持了原发肿瘤的组织学特性,可活体“再现”人类疾病;MRI能够敏感地发现肾筋膜下是否成瘤,且准确量化肿瘤大小,本模型可作为观察人类胃癌个体化治疗临床前实验的动物模型。

AEG-1对裸鼠肝癌模型中肝癌细胞生长及肺转移的影响

目的研究过表达和沉默AEG-1基因对肝癌细胞生长的影响,以及AEG-1基因在调节肝癌细胞定向肺转移中的作用。方法分别以携带过表达AEG-1序列及对照基因序列的慢病毒(lentivirus)转染SMMC-7721肝癌细胞株(SMMC-7721-AEG-1-L;SMMC-7721-control-L);以携带shRNA AEG-1及对照shRNA质粒(plasmid)转染SMMC-7721细胞株(SMMC-7721-shAEG-1-P;SMMC-7721-control-P);使用实时定量PCR和Westen blot检测AEG-1的表达;随后使用荧光素酶基因慢病毒包装颗粒转染上述4种稳定转染细胞株。使用上述细胞株分别建立3种裸鼠肝癌模型:皮下移植瘤模型,原位移植瘤模型和血行播散模型;每种细胞株每一模型5只Balb-c裸鼠,共60只。建立皮下移植瘤模型,观测肿瘤的生长情况并绘制肝细胞肿瘤生长曲线;建立肝癌原位移植瘤和血行播散模型,采用生物发光活体成像技术及组织病理学方法监测造模成功率及肿瘤在肝内、肝外转移情况。结果通过肝癌皮下移植瘤模型可观察到AEG-1过表达组肿瘤体积显著高于对照组,且裸鼠肝脏组织出现弥漫性侵袭转移灶;在肝癌原位移植瘤和血行播散模型中可观察到AEG-1过表达/沉默可以导致肝癌细胞肝内转移、肺转移率和转移灶数量显著增高/降低。结论过表达AEG-1基因可促进肝癌细胞生长以及定向肺转移,沉默AEG-1基因抑制肝癌细胞生长及定向肺转移。

Multimodal magnetic resonance imaging for assessing lacunar infarction after proximal middle cerebral artery occlusion in a canine model

Background A new lacunar infarction model was recently established in beagle dogs through proximal middle cerebral artery （MCA） occlusion by thrombus. This study aimed to characterize the model by multimodal magnetic resonance imaging （MRI） and to investigate its potential role for the future stroke research. Methods The left proximal MCA was embolized with an autologous thrombus in six beagles. Diffusion-weighted imaging （DWI） and T2-weighted imaging （T2Wl） were performed every half hour during the first six hours after occlusion, followed by three time points at 12 hours, 24 hours, and one week. Perfusion-weighted imaging （PWI） and magnetic resonance angiography （MRA） were carried out at six hours, 24 hours and one week. The PWI-DWI mismatch ratio was defined as （PWI-DWl）/DWl ischemic volume. Results Lacunar infarcts induced by MCA occlusion were located in the left caudate nucleus and internal capsule. All the lesions could be detected within two hours by DWI. Lesion volume on DWl increased in a time dependent manner, from （87.19±67.16） mm3 at one hour up to （368.98±217.05） mm3 at 24 hours （P=0.009）, while that on PWl gradually decreased from （7315.00±2054.38） mm3at six hours to （4900.33±1319.71） mm3 at 24 hours and （3334.33±1195.11） mm3 at one week （P=0.002）. The mismatch ratio was 41.93±22.75 at six hours after ischemia, showing ＂extensive mismatch＂, and decreased to 18.10±13.74 at 24 hours （P=0.002）. No MCA recanalization was observed within 24 hours after MCA occlusion. Conclusions Lacunar infarction induced by proximal MCA occlusion could be detected early by DWl and was characterized by extensive PWI-DWl mismatch. Multimodal MRI is useful to demonstrate the natural evolution of PWI-DWl mismatch. This ischemic model could be further used for investigating early thrombolysis in lacunar stroke showing extensive mismatch.

关节镜下半月板部分切除制备骨关节炎动物模型

目的探讨经关节镜建立猪双膝骨关节炎动物模型及用磁共振成像(magnetic resonance imaging,MRI)监测骨关节炎骨软骨损害的有效性和可行性。方法4只小型猪经关节镜切除双膝外侧部分半月板,术后12周,行大体、组织学和MRI观察与切除半月板相对股骨髁的骨软骨变化。结果大体观察结果显示,局限性软骨表面纤维化,股骨髁间切迹骨赘形成;组织学检测结果显示,软骨细胞数量和蛋白多糖含量减少、成簇排列细胞数量增加;MRI检查结果显示,软骨厚度变薄和骨软骨信号强度改变。结论经关节镜半月板部分切除能有效建立猪双膝关节骨关节炎动物模型,MRI能灵敏地监测到骨关节炎动物模型的骨软骨变化。

SD大鼠肝癌模型的MRI征象与病理对照研究

目的：通过ＳＤ大鼠肝癌模型的ＭＲＩ征象与病理对照研究，进一步验证人类肝癌的ＭＲＩ征象的病理基础。材料和方法：经腹腔种植Ｗａｌｋｅｒ－２５６癌肉瘤成功地建立ＳＤ大鼠肝癌模型２２只，共２８个病灶。使用１．５超导ＭＲ机扫描，观察ＭＲＩ图像，留取肿瘤标本行光镜及电镜观察，病理结果与ＭＲＩ征象对比，并与人类肝癌的ＭＲＩ征象和病理改变相对照。结果：ＳＤ大鼠肝癌模型的ＭＲＩ表现及病理改变与人类肝癌相似。结论：ＳＤ大鼠移植型肝癌模型是一种容易复制、实验周期短的肝癌模型。

原位膀胱癌动物模型的建立及应用

背景与目的:表浅性膀胱癌术后膀胱灌注丝裂霉素等药物进行化疗,肿瘤仍有较高的复发率。有研究报道往膀胱内灌注小型干扰RNA(siRNA)可抑制裸鼠膀胱肿瘤生长。本研究目的是建立荷人膀胱癌的原位动物模型,通过磁共振成像(magnetic resonance imaging,MRI)监测肿瘤生长过程,并利用此模型评价靶向Survivin的干扰质粒对丝裂霉素的增效作用。方法:直视下经尿道机械损伤BALB/c裸鼠膀胱粘膜,将人膀胱癌细胞T24经尿道种植于25只裸鼠膀胱,建立荷人膀胱癌原位动物模型。以钆-二乙三胺五乙酸作为膀胱造影剂,用MRI监测肿瘤的生长,同时取裸鼠膀胱组织标本行HE染色进行病理学检查。同法建立膀胱癌裸鼠动物模型18只,分为对照组、丝裂霉素组和联合组3组,每周两次膀胱灌注,联合组为靶向Survivin的干扰质粒和丝裂霉素交替用药;膀胱灌注6次后荷瘤膀胱称重。结果:25只裸鼠在种植T24细胞后均形成膀胱肿瘤。种植后7天裸鼠膀胱MRI检查无明显变化,l4、21、28天MRI检查均可发现膀胱不同程度的充盈缺损,MRI图像与肿瘤实际大小吻合。病理检查显示:种植后7天,肿瘤生长于裸鼠膀胱粘膜或浅层肌肉;14～28天局限于肌层;35天时侵及浆膜层。丝裂霉素组和联合组的抑瘤率分别为33.45%、56.34%,联合组优于丝裂霉素组(P<0.05)。结论:成功建立了裸鼠原位膀胱癌动物模型,肿瘤生长基本模拟了人膀胱癌的发生、发展过程;MRI检查可作为对裸鼠膀胱原位肿瘤动态观察的可靠方法。靶向Survivin的干扰质粒增加了丝裂霉素的抗肿瘤作用。

T2 mapping动态定量监测兔腰椎间盘退变模型

目的提高T2 mapping技术动态定量监测兔腰椎间盘退变模型的认识。材料与方法 18只新西兰大白兔,从脊柱侧后方手术入路暴露腰椎间盘,18 G穿刺针抽吸12只L2~3、L3~4、L4~5髓核,各约5 mg,正常L1~2、L5~6和另6只L2~5间椎间盘分别为组内和组间对照。术后第4、8、12周行MR矢状面T2WI和T2-mapping序列检查,取正中矢状面观察各椎间盘的信号,测量T2弛豫时间并与正常组比较。相应各时间点取2只L1~6间椎间盘行HE和Masson染色,观察纤维环形态、髓核细胞及基质的变化并与正常组比较。结果 18 G穿刺针经脊柱旁路于横突根部可成功穿刺抽吸髓核。6只正常兔及12只实验兔组内对照椎间盘T2WI序列为均匀高信号,12只实验兔椎间盘随术后时间延长信号逐渐降低,第4周呈稍低信号,第8周明显降低,第12周完全呈低信号。正常对照组及术后第4、8、12周组T2弛豫时间的单因素方差分析结果（F=38.82,P〈0.05）,造模术后第8周T2弛豫时间有显著差异（P〈0.05）。术后随时间进展,HE和Masson染色示椎间盘细胞和胶原逐渐减少,纤维环和髓核分界不清;第8周髓核基质退变纤维化,几乎被纤维组织取代;第12周椎间盘纤维软骨化,局部形成软骨。结论 T2mapping技术可实时定量监测腰椎间盘的退变进程。

兔肝VX2瘤模型MR灌注成像与MVD及VEGF的相关性研究

目的研究肝脏肿瘤MR灌注成像(PWI)表现与微血管密度(MVD)、血管内皮生长因子(VEGF)的相关性,并优选灌注评价指标。材料与方法建立15只新西兰兔肝VX2瘤模型,随机分为A、B、C3组,每组5只,分别在肿瘤种植成功后的16、28、45天进行T2*WI的PWI和MVD、VEGF检测,PWI采用信号强度-时间曲线中的几个指标包括达峰时间(TTP)、最大信号下降百分率(SRRmax)、最大信号下降斜率(SRSmax)、平均通过时间(MTT)作为参数用于肿瘤灌注的定量研究,并分别与肿瘤的MVD计数、VEGF表达强度作直线相关分析。结果SRRmax、SRSmax与MVD呈正相关(r=0.584,P=0.022;r=0.731,P=0.002),其中SRSmax与MVD的相关性更高;3组之间SRSmax和MVD的总体差异均有统计学意义(F=6.352,P=0.013;χ2=9.260,P=0.010),A组的SRSmax、MVD明显高于C组(P<0.05);各项灌注指标与VEGF表达强度不相关。结论MR-PWI与MVD密切相关,SRSmax可作为优化的灌注评价指标。

兔VX2肝癌模型制备的改进及其磁共振影像学表现

目的改进兔VX2肝癌模型的制作方法,使之更为简便、省时,同时探讨瘤灶的MRI表现及MRI在动态检测瘤灶中的作用。方法新西兰大白兔16只,随机分成4组(每组4只),在螺旋CT引导下,采用瘤块组织接种于兔肝脏左、右叶,接种后14、18、22、26d分别行MRI平扫、增强扫描及病理分析。结果16只实验兔发现瘤灶,成瘤率100%;瘤灶以种植后18￣22dMRI显示最清楚和典型,直径1￣2cm,平扫呈低或等信号,增强扫描瘤灶边缘明显强化,种植后超过22d的肿瘤中央坏死明显。结论螺旋CT引导下进行兔VX2肝癌模型的制作,使制作过程更为简便、省时;采用磁共振平扫及增强扫描对瘤灶进行动态检测、评价,可更为准确、及时地观察瘤灶的发生、发展等影像学改变。

大鼠C6脑胶质瘤生长规律的影像学与病理学观察

目的建立Wistar大鼠c6胶质瘤模型，采用MRI、CT灌注（CT perfusion，CTP）成像观测肿瘤体积的动态变化，探讨大鼠C6脑胶质瘤的生长规律。方法成年Wistar大鼠40只，采用立体定向仪进行C6细胞脑内接种，建立大鼠C6脑胶质瘤模型。每次随机抽取10只接种鼠分别对应于5～9d、10～14d、15～19d3个时间段行CTP、MRI及病理学检查，观测大鼠C6脑胶质瘤的生长规律，并评价影像学与病理学结果之间的相关性。结果15～19d时间段CTP、MRI观测结果分别与病理学结果比较均有显著性差异（t=3．131，P〈0．01；t=2．566，P〈0．05），但CTP与MRI观测结果差异无统计学意义（P〉0．05）。5～9d和10～14d时间段3种技术观测结果比较差异均无统计学意义（P〉0．05）。Pearson线性相关分析表明CTP、MRI与病理学三者测量结果间均有显著正相关，病理学与CTP、病理学与MRI、CTP与MRI的r=0．998，0．998，1．000（P〈0．01）。同归分析表明，肿瘤体积随时间呈指数规律增长（rpatho=0．990，rCTP=0．987，rMRI=0．990，P〈0．01）。结论影像学活体观测的准确性高，更真实反映肿瘤的实际大小，适于对肿瘤动物模型的生长观测和试验性治疗的疗效评价。