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.

Imaging findings of inflammatory pseudotumor-like follicular dendritic cell tumors of the liver:Two case reports and literature review

BACKGROUND Inflammatory pseudotumor-like follicular dendritic cell(IPT-like FDC)tumors of the liver is an uncommon tumor with extremely low incidence.To date,the radiologic findings of this tumor in multiphase computed tomography(CT)and magnetic resonance imaging(MRI)imaging have not been described.CASE SUMMARY Patient 1 is a 31-year-old Chinese female,whose complaining incidentally coincided with the finding of multiple liver masses.In the local hospital,an abdominal enhanced CT found two hypo-dense solid lesions,with heterogeneous sustained hypoenhancement,in the upper segment of the liver’s right posterior lobe.In our hospital,enhanced magnetic resonance imaging(MRI)with hepatocyte-specific contrast agents showed a similar enhanced pattern of lesions with patchy hyperintensity in the hepatobiliary phase(HBP).The patient underwent surgery and recovered well.The final pathology confirmed an IPTlike FDC tumor.No recurrence was found on the regular re-examination.Patient 2 is a 48-year-old Chinese male admitted to our hospital for a huge unexpected hepatic lesion.A dynamic enhanced abdominal CT revealed a huge heterogeneous enhanced solid tumor in the right lobe of the liver with a size of 100 mm×80 mm,which showed a heterogeneous sustained hypoenhancement.In addition,enlarged lymph nodes were found in the hilum of the liver.This patient underwent a hepatic lobectomy and lymph node dissection.The final pathology confirmed an IPT-like FDC tumor.No recurrence was found upon regular re-examination.CONCLUSION When a hepatic tumor shows heterogeneous sustained hypoenhancement with a patchy enhancement during HBP,an IPT-like FDC tumor should be considered in the differential diagnosis.

Separate calculation of DW-MRI in assessing therapeutic effect in liver tumors in rats

AIM:To explore whether the antitumor effect of a vascular disrupting agent(VDA)would be enhanced by combining with an antiangiogenic agent,and whether such synergistic effects can be effectively evaluated with separate calculation of diffusion weighted magnetic resonance imaging(DW-MRI).METHODS:Thirty-seven rats with implanted liver tumors were randomized into the following three groups:(1)ZD6126,a kind of VDA;(2)ZDTHA,ZD6126 in combination with an antiangiogenic,thalidomide;and(3)control.Morphological DW-MRI were performed and quantified before,4 h and 2 d after treatment.The apparent diffusion coefficient(ADC)values were calculated separately for low b values(ADC low),high b values(ADC high)and all b values(ADC all).The tissue perfusion contribution,ADC perf,was calculated as ADC low-ADC high.Imaging findings were finally verified by histopathology.RESULTS:The combination therapy with ZDTHA significantly delayed tumor growth due to synergistic effects by inducing cumulative tumor necrosis.In addition to delaying tumor growth,ZDTHA caused tumor necrosis in an additive manner,which was verified by HE staining.Although both ADC high and ADC all in the ZD6126and ZDTHA groups were significantly higher compared to those in the control group on day 2,the entire tumor ADC high of ZDTHA was even higher than that of ZD6126,but the significant difference was not observed for ADCall between ZDTHA and ZD6126.This indicated that the perfusion insensitive ADC high values calculated from high b value images performed significantly better than ADC all for the monitoring of tumor necrosis on day 2.The perfusion sensitive ADC perf derived from ADC low by excluding high b value effects could better reflect the reduction of blood flow due to the vessel shutdown induced by ZD6126,compared to the ADC low at 4 h.The ADC perf could provide valuable perfusion information from DW-MRI data.CONCLUSION:The separate calculation of ADC is more useful than conventional averaged ADC in evaluating the efficacy of combination therapy with ZD6126and thalidomide for solid tumors.

Neurite Orientation Dispersion and Density Imaging of Rat Brain Microstructural Changes due to Middle Cerebral Artery Occlusion at a 3T MRI

The purpose of this work was to demonstrate the feasibility of neurite orientation dispersion and density imaging(NODDI)in characterizing the brain tissue microstructural changes of middle cerebral artery occlusion(MCAO)in rats at 3T MRI,and to validate NODDI metrics with histology.A multi-shell diffusion MRI protocol was performed on 11 MCAO rats and 10 control rats at different post-operation time points of 0.5,2,6,12,24 and 72 h.NODDI orientation dispersion index(ODI)and intracellular volume fraction(V_(ic))metrics were compared between MCAO group and control group.The evolution of NODDI metrics was characterized and validated by histology.Infarction was consistent with significantly increased ODI and V_(ic)in comparison to control tissues at all time points(P<0.001).Lesion ODI increased gradually from 0.5 to 72 h,while its V_(ic)showed a more complicated and fluctuated evolution.ODI and V_(ic)were significantly different between hyperacute and acute stroke periods(P<0.001).The NODDI metrics were found to be consistent with the histological findings.In conclusion,NODDI can reflect microstructural changes of brain tissues in MCAO rats at 3T MRI and the metrics are consistent with histology.This study helps to prepare NODDI for the diagnosis and management of ischemic stroke in translational research and clinical practice.

Magnetic resonance diffusion-weighted imaging in the diagnosis of diffuse liver diseases in rats

Background The diagnosis of diffuse hepatic lesions in early stage is a tough task at any time for clinical conventional imaging. Magnetic resonance diffusion-weighted imaging (MR DWI) can detect the changes of tissue structure at molecular level. This study was designed to determine the value of DWI in the diagnosis of diffuse liver lesions in early stage. Methods Diffuse liver lesions were induced by diethylnitrosamine in 42 rats of test group. Fourteen rats in control group were fed with pure water. Dynamic changes of MR DWI were observed every week in both groups during the early stage of diffuse liver lesions (1 to 12 weeks after drug administration in the test group). Apparent diffusion coefficient (ADC) values of liver parenchyma in different stages and pathologic changes were analyzed. Results The process of diffuse hepatic lesions in the test group was classified into three stages according to pathological changes, namely hepatitis, hepatic fibrosis and cirrhosis. No obvious morphological changes were shown by conventional imaging in both groups during this stage. But MR DWI demonstrated heterogeneous signal changes in early stage of hepatic cirrhosis in the test group. No significant change of ADC values was found in the control group between different weeks ( P >0.05). The ADC values of the test group declined from the fifth week, and after the tenth week the ADC values were significantly different between the test and control groups at gradient factor (b) value 300 sec/mm 2 ( P <0.05). At b value 600 and 1000 sec/mm 2, significant difference was seen between the two groups from the sixth week onward. The range of ADC value of the groups was (1.7-0.9)±(0.40-0.04) mm 2/sec (b=600) and (1.38-0.75)±(0.07-0.35) mm 2/sec (b=1000), respectively. Dominant pathological changes included swelled hepatocytes within 1 to 4 weeks after the administration of diethylnitrosamine in the test group, hyperplasia of fibrous tissues in 5-8 weeks and formation of cirrhotic nodules in 9-12 weeks. Conclusions MR functional DWI could detect diffuse liver lesions earlier than conventional morphological imaging. ADC value as a marker for early diagnosis of diffuse liver lesions could also be used to inspect changes of the lesions

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.

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.

Development of a rat C6 brain tumor model

OBJECTIVE: To establish rat C6 brain-tumor models and find a simple reliable index to judge tumor volume. METHODS: C6 cell suspension (10 microl) containing 10 g/L agarose and 1 x 10(6) cells was injected into the right caudate nucleus of the rat brain by a stereotaxic method. After implantation, rats were observed and given MRI scans. Rats were perfused with paraformaldehyde trans-aorta at the 10th, 15th, 20th and 25th day and before natural death. All brains, lungs, spinal cords and tumors were sectioned and inspected. Tumor-containing samples were prepared histologically by hematoxylin and eosin (HE) stains. RESULTS: Fifty implanted rats had 100% yield of intracerebral growth, with distant metastasis of 0% to 4%. CONCLUSION: A rat C6 brain-tumor model was successfully established. Rat survival time is correlated with tumor volume and may be useful as an index of tumor size.

Perfusion magnetic resonance imaging of the liver

Perfusion magnetic resonance imaging (MRI) studies quantify the microcirculatory status of liver parenchyma and liver lesions, and can be used for the detection of liver metastases, assessing the effectiveness of antiangiogenic therapy, evaluating tumor viability after anticancer therapy or ablation, and diagnosis of liver cirrhosis and its severity. In this review, we discuss the basic concepts of perfusion MRI using tracer kinetic modeling, the common kinetic models applied for analyses, the MR scanning techniques, methods of data processing, and evidence that supports its use from published clinical and research studies. Technical standardization and further studies will help to establish and validate perfusion MRI as a clinical imaging modality.

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.

MR diffusion-weighted imaging of rabbit liver VX-2 tumor

AIM: To investigate the implanting method of rabbit liver VX-2 tumor and its MR diffusion-weighted imaging (DWI) characteristics. METHODS: Thirty-five New Zealand rabbits were included in the study. VX-2 tumor was implanted subcutaneously in 14 rabbits and intrahepatically in 6 for pre-experiments. VX-2 tumor was implanted intrahepatically in 12 rabbits for experiment and three were used as the control group. DWI, T1- and T2-weighted of MRI were performed periodically in 15 rabbits for experiment before and after implantation. The distinction of VX-2 tumors on DWI was assessed by their apparent diffusion coefficient (ADC) values. The statistical significance was calculated by analysis of variance (ANOVA) of the randomized block design using SPSS10.0 software. RESULTS: The successful rate of subcutaneous implantation of VX-2 tumor was 29% (4/14) while that of intrahepatic implantation of it was 33% (2/6) in the preexperiment. The successful rate of intrahepatic implantation of VX-2 tumor in the experiment was 83% (10/12) and 15 tumors grew in 10 successfully implanted rabbits. The DWI signal of VX-2 tumor was high and became lower when the b value increased step by step. The signal of VX-2 tumor on the map of ADC was low. When the b value was 100 or 300 s/mm2, the ADC value of normal group and VX-2 tumor group was respectively 2.57±0.26, 1.73±0.31, 1.87±0.25 and 1.57±0.23 mm2/s. Their distinction was significant (F= 43.26, P<0.01), the tumor ADC value between b values 100 and 300 s/mm2 was significant (Tukey HSP,P<0.05) and the ADC value between VX-2 tumor and normal liver was also significant (Tukey HSP, P<0.01). VX-2 tumor developed quickly and metastasized early to all body, especially to the lung, liver, lymph nodes of mediastinum, etc. CONCLUSION: The DWI signal of rabbit VX-2 tumor has its characteristics on MR DWI and DWI plays an important role in diagnosing and discovering VX-2 tumor.

Predicting liver metastasis of gastrointestinal tract cancer by diffusion-weighted imaging of apparent diffusion coefficient values

AIM: To determine if efficacy of chemotherapy on liver metastasis of gastrointestinal tract cancer can be predicted by apparent diffusion coefficient(ADC) values of diffusion-weighted imaging(DWI). METHODS: In total, 86 patients with liver metastasis of gastrointestinal tract cancer(156 metastatic lesions) diagnosed in our hospital were included in this study. The maximum diameters of these tumors were compared with each other before treatment, 2 wk after treatment, and 12 wk after treatment. Selected patients were classified as the effective group and the ineffective group, depending on the maximum diameter of the tumor after 12 wk of treatment; and the ADC values at different treatment times between the two groups were compared. Spearman rank correlation was used to analyze the relationship between ADC value and tumor diameter. Receiver operating characteristic curve(ROC curve) was used to analyze the ADC values before treatment to predict the patient's sensitivity and specificity degree of efficacy to the chemotherapy. RESULTS: There was no difference in age between the two groups and in maximum tumor diameter before treatment and 2 wk after treatment. However, after 12 wk of treatment, maximum tumor diameter in the effective group was significantly lower than that in the ineffective group(P < 0.05). Before treatment, ADC values in the ineffective group were significantly higher than those in the effective group(P < 0.05). There was no difference in ADC values between the effective and ineffective groups after 2 and 12 wk of treatment. However, ADC values were significantly higher after 2 and 12 wk of treatment compared to before treatment in the effective group(P < 0.05). Spearman rank correlation analysis showed that ADC value before treatment and the reduced percentage of the maximum tumor diameter after 12 wk of treatment were negatively correlated, while the increase in the percentage of the ADC value 12 wk after treatment and the decrease in the percentage of the maximum tumor diameter were significantly positively correlated. The results of the ROC curve showed that ADC value with a chemotherapy ineffective threshold value of 1.14 × 10-3 mm2/s before treatment had a sensitivity and specificity of 94.3% and 76.7%, respectively. CONCLUSION: DWI ADC values can be used to predict the response of patients with liver metastasis of gastrointestinal tract cancer to chemotherapy with high sensitivity and relatively high specificity.

Characteristics of common solid liver lesions and recommendations for diagnostic workup

Due to the widespread clinical use of imaging modalities such as ultrasonography,computed tomography and magnetic resonance imaging (MRI),previously unsuspected liver masses are increasingly being found in asymptomatic patients.This review discusses the various characteristics of the most common solid liver lesions and recommends a practical approach for diagnostic workup.Likely diagnoses include hepatocellular carcinoma (the most likely;a solid liver lesion in a cirrhotic liver) and hemangioma (generally presenting as a mass in a non-cirrhotic liver).Focal nodular hyperplasia and hepatic adenoma should be ruled out in young women.In 70% of cases,MRI with gadolinium differentiates between these lesions.Fine needle core biopsy or aspiration,or both,might be required in doubtful cases.If uncertainty persists as to the nature of the lesion,surgical resection is recommended.If the patient is known to have a primary malignancy and the lesion was found at tumor staging or follow up,histology is required only when the nature of the liver lesion is doubtful.

Initial study of biexponential model of intravoxel incoherent motion magnetic resonance imaging in evaluation of the liver fibrosis

Background The diagnosis of liver fibrosis is a difficult task at any time using conventional clinical imaging.Intravoxel incoherent motion （IVIM） can be used to investigate both diffusion and perfusion changes in tissues.This study was designed to determine the value of IVIM in the diagnosis and staging of liver fibrosis.Methods IVIM examinations were performed on a GE 3.0T MR scanner in 25 patients with liver fibrosis and 25 healthy volunteers as the control group.Patients with liver fibrosis diagnosis were confirmed by pathology and staged on a scale of F0-4.The standard ADC values and the values of a biexponential model （slow ADC （Dslow）,fast ADC （Dfast） and fraction of fast ADC （FF）） were measured in three liver regions per person.The mean standard ADC values,Dslow values,Dfast values and FF values from the study group were compared among the right posterior hepatic lobe,right anterior hepatic lobe and medial segment of the left lobe.Receiver Operating Characteristic （ROC） curves and independent-samples t-tests were used to calculate the mean standard ADC values,Dslow values,Dfast values and FF values from the study group and the control group.Spearman rho correlation analysis was used for the stage of liver fibrosis.The liver fibrosis stages between the groups F0-1 and F2-4,the groups F0-2 and F3-4 were compared.Results Among the liver fibrosis,there was no significant difference in the mean standard ADC values,Dslow values,Dfast values,and FF values obtained from the right posterior hepatic lobe,right anterior hepatic lobe and medial segment of the left lobe.Using ROC analysis,the Area Under the Curve （AUC） values of standard ADC,Dslow,Dfast,FF were all between 0.7 to 0.9.The mean standard ADC values,Dslow values,Dfast values and FF values of the liver in the study group were significantly lower than the values in the control group （P ＜0.05）.As the stage of the fibrosis increased,the values decreased by Spearman rho correlation analysis.The mean values （standard ADC,Dslow,Dfast,and FF） of liver fibrosis stages between the groups F0-1 and F2-4,the groups F0-2 and F3-4 showed significant differences （P＜0.05）.Conclusions IVIM can reflect the conditions of perfusion and diffusion in liver fibrosis and thus distinguish between normal liver and liver fibrosis.The IVIM technique may serve as a valuable tool for detecting and characterizing liver fibrosis,and monitoring its progression in a noninvasive manner.

Complementary comments on metastatic liver lesions with exceptional and rare cases

Liver metastases can appear in different forms in magnetic resonance imaging.Contrary to popular belief,while radiologists report hypovascular or hypervascular metastatic lesions,exceptional examples may be detected in various tumors.The aim of this article is to improve this review by presenting rare and atypical examples of liver metastasis,as well as cases that might potentially be misdiagnosed as metastases during the process of differential diagnosis.

Extended Tofts双室模型在肝硬化DCE-MRI定量分析中的研究

目的:探讨Extended Tofts双室模型在肝硬化动态对比增强磁共振(DCE-MRI)定量研究中的应用价值。方法:对符合入组标准和排除标准的20例肝硬化代偿期患者、15例失代偿期患者和15例正常对照者行肝脏DCE-MRI扫描,由2名高年资MRI诊断医师分别使用Extended Tofts模型计算各组的定量参数,包括对比剂容积转运常数(Ktrans)、速率常数(Kep)、血管外细胞外间隙容积分数(Ve)、血管(血浆)间隙容积分数(Vp)、肝动脉灌注指数(HPI)、血容量(BV)、血流量(BF)、对比剂平均通过时间(MTT)。2名医师所测数值分别记录为测量1和测量2两组。代偿期肝硬化组、失代偿期肝硬化组和正常对照组间定量参数的比较采用单因素方差分析,两两间的比较采用LSD检验。筛选出三组间具有统计学差异、且测量1和测量2的组内相关系数(ICC)较高的定量参数。绘制受试者工作特征(ROC)曲线评价Ktrans、Ve、HPI、MTT对肝硬化的诊断效能。应用ICC比较测量1和测量2两组结果的一致性。结果:测量1和测量2两组结果显示,肝硬化组Ktrans和Ve低于正常组,HPI和MTT高于正常组,BF低于正常组,差异均具有统计学意义(P均<0.05),HPI和MTT在三组间两两比较,均具有统计学差异(P均<0.05)。测量1和测量2两组的Ktrans、Ve、HPI、MTT的ICC值分别为0.707、0.673、0.869,0.838。ROC曲线分析显示:Ktrans和Ve对失代偿期肝硬化诊断效能较高(敏感度均为90%,特异度均为80%);HPI和MTT对代偿期和失代偿期肝硬化均有较高的诊断效能(敏感度、特异度均≥75%)。结论:Extended Tofts模型在肝硬化的DCE-MRI定量分析中复测性良好,能够评价肝硬化的严重程度。

Assessment of hemodynamics in precancerous lesion of hepatocellular carcinoma:Evaluation with MR perfusion

AIM: To investigate the hemodynamic changes in a precancerous lesion model of hepatocellular carcinoma (HCC). METHODS: Hemodynamic changes in 18 Wistar rats were studied with non-invasive magnetic resonance (MR) perfusion. The changes induced by diethylnitrosamine (DEN) developed into liver nodular lesions due to hepatic cirrhosis during the progression of carcinogenesis. The MR perfusion data [positive enhancement integral (PEI)] were compared between the nodular lesions corresponding well with MR images and pathology and their surrounding hepatic parenchyma. RESULTS: A total of 46 nodules were located by MR imaging and autopsy, including 22 dysplastic nodules (DN), 9 regenerative nodules (RN), 10 early HCCs and 5 overt HCCs. Among the 22 DNs, 6 were low-grade DN (lGDN) and 16 were high-grade DN (HGDN). The average PEI of RN, DN, early and overt HCC was 205.67 ± 31.17, 161.94 ± 20.74, 226.09 ± 34.83, 491.86 ± 44.61 respectively, and their liver parenchyma nearby was 204.84 ± 70.19. Comparison of the blood perfusion index between each RN and its surrounding hepatic parenchyma showed no statistically significant difference (P = 0.06). There were significant differences in DN (P = 0.02). During the late hepatic arterial phase, the perfusion curve in DN declined. DN had an iso-signal intensity at the early hepatic arterial phase and a low signal intensity at the portal venous phase. Of the 10early HCCs, 4 demonstrated less blood perfusion and 6 displayed minimally increased blood flow compared to the surrounding parenchyma. Five HCCs showed significantly increased blood supply compared to the surrounding parenchyma (P = 0.02). CONCLUSION: Non-invasive MR perfusion can detect changes in blood supply of precancerous lesions.

磁共振脂肪定量技术在肝脏肿瘤中的应用

体内器官的脂肪堆积会增加包括肝良性病变在内的多种疾病癌变的风险。近年来,脂肪性肝病越来越被认为是肝细胞癌的危险因素,与代谢相关脂肪性肝病相关的肝细胞癌已是全球日益增加的医疗负担。肝肿瘤瘤内及瘤周脂肪含量在肿瘤的诊断、鉴别、分级及预后等方面有一定价值。肝移植作为肝肿瘤治疗手段之一越来越受到重视,肝脏脂肪变性与肝移植术前评估及术后监测密切相关。除此之外,肿瘤治疗过程中所致肝损伤也与肝脏脂肪含量直接相关。因此,肝脏脂肪定量在肝脏肿瘤的发生发展、诊断治疗及预后评估中具有重要意义。本文综述了磁共振波谱成像(magnetic resonance spectroscopy,MRS)、化学位移成像(chemical shift imaging,CSI)以及多回波Dixon(包括IDEAL-IQ和mDixon-Quant)等MRI脂肪定量技术在肝脏肿瘤中的应用,旨在提供更精准定量肝脏脂肪的影像标志物,为肿瘤治疗方式的选择和疗效评估提供客观和科学的依据,用以帮助临床对肝脏肿瘤进行无创诊断及治疗评估。

基于LI-RADS v2018及MRI特征对肝细胞癌CK19表达的风险预测及预后评估

目的 探讨2018版肝脏影像报告和数据系统(Liver Imaging Reporting and Data System version 2018,LI-RADS v2018)对肝细胞癌(hepatocellular carcinoma,HCC)细胞角蛋白19(cytokeratin 19,CK19)表达的术前预测及预后评估的价值。材料与方法 回顾性分析220例术前接受MRI检查并经病理证实为HCC患者的临床、病理及影像资料,包括CK19阳性组59例,CK19阴性组161例。将患者按7∶3比例分为训练集和验证集。通过单因素与多因素logistic回归分析确定CK19阳性表达HCC的独立预测因素并构建列线图评分模型。采用受试者工作特征(receiver operating characteristic,ROC)曲线分析模型诊断效能,绘制校准曲线、决策曲线评价模型的校准性能和临床适用性。计算患者的列线图得分并进行高低风险分组,采用Kaplan-Meier生存曲线分析比较不同亚组患者的总体、早期及晚期无复发生存率。结果 晕状强化(OR=3.432,P=0.045)、环形动脉期高强化(OR=32.073,P=0.017)、靶样扩散受限(OR=12.941,P=0.006)、不光滑肿瘤边缘(OR=4.590,P=0.014)及肝胆期肿瘤-肝实质相对增强比(the relative enhancement ratio,RER)(OR=0.014,P=0.023)是CK19阳性表达HCC的独立预测因素。预测模型在训练集和验证集的曲线下面积(area under the curve,AUC)分别为0.884(95%CI:0.823~0.930)、0.748(95%CI:0.625~0.846),校准曲线、决策曲线显示模型的校准性能和临床适用性较好。CK19阳性与阴性组的总体无复发生存率、高与低风险组的总体、早期及晚期无复发生存率之间均存在显著差异(P<0.05)。结论 晕状强化、环形动脉期高强化、靶样扩散受限结合不光滑肿瘤边缘、肝胆期增强定量参数可对HCC的CK19表达进行术前风险预测,并有助于评估HCC术后复发。

磁共振弥散成像参数预测肝细胞癌微血管模式的价值

目的:评估术前磁共振检查中使用两种非高斯弥散模型衍生的定量参数以及常规的表观弥散系数(ADC)预测肝细胞癌(HCC)肿瘤包绕型血管(VETC)及微血管侵犯(MVI)联合表型方面的潜力。方法:前瞻性搜集105例HCC患者,所有患者均在术前两周内进行常规序列及多个b值(0~3000 s/mm^(2))的DWI检查。通过弥散后处理技术获得体素内非相干运动(IVIM)模型、弥散峰度成像(DKI)模型的衍生定量参数及常规的ADC值,分别由2位放射科医生测量整个病灶的所有弥散参数的平均值。由2位病理科医师联合VETC和MVI结果对HCC组织的微血管模式进行分类,将其分为3个不同的VETC/MVI(VM)组。比较不同VM分组间各个定量参数的差异,采用受试者工作特征(ROC)曲线评估差异具有统计学意义的定量参数的诊断效能,并采用DeLong检验比较各组AUC值的差异。结果:IVIM-Dstar值、DKI-K值在不同VM分组之间差异均有统计学意义(P<0.001)。VM-组的IVIM-Dstar值、DKI-K值低于VM±和VM+组,差异均有统计学意义(P<0.05)。两两比较结果显示,不同VM分组间的DKI-K值差异均有统计学意义(P均<0.05)。ROC曲线分析结果显示,IVIM-Dstar及DKI-K值鉴别不同VM分组的AUC值分别为0.756、0.863、0.630及0.653、0.802、0.673;IVIM-Dstar值及DKI-K值组成的联合模型鉴别不同VM分组的AUC值分别为0.769、0.896和0.702(P<0.05)。Delong检验结果表明,IVIM-Dstar、DKI-K以及两者组成的联合模型在鉴别不同VM分组的效能方面差异无统计学意义(P>0.05)。结论:磁共振非高斯弥散模型定量参数在术前预测HCC的VETC及MVI联合表型方面具有较好的应用价值。