Usefulness of Arterial Subtraction in Applying Liver Imaging Reporting and Data System (LI-RADS) Treatment Response Algorithm to Gadoxetic Acid-Enhanced MRI

ObjectiveWe aimed to evaluate the usefulness of arterial subtraction images for predicting the viability of hepatocellular carcinoma (HCC) after locoregional therapy (LRT) using gadoxetic acid-enhanced MRI and the Liver Imaging Reporting and Data System treatment response (LR-TR) algorithm.Materials and MethodsThis study included 90 patients (mean age ± standard deviation, 57 ± 9 years) who underwent liver transplantation or resection after LRT and had 73 viable and 32 nonviable HCCs. All patients underwent gadoxetic acid-enhanced MRI before surgery. Two radiologists assessed the presence of LR-TR features, including arterial phase hyperenhancement (APHE) and LR-TR categories (viable, nonviable, or equivocal), using ordinary arterial-phase and arterial subtraction images. The reference standard for tumor viability was surgical pathology. The sensitivity of APHE for diagnosing viable HCC was compared between ordinary arterial-phase and arterial subtraction images. The sensitivity and specificity of the LR-TR algorithm for diagnosing viable HCC was compared between the use of ordinary arterial-phase and the use of arterial subtraction images. Subgroup analysis was performed on lesions treated with transarterial chemoembolization (TACE) only.ResultsThe sensitivity of APHE for viable HCCs was higher for arterial subtraction images than ordinary arterial-phase images (71.2% vs. 47.9%; p < 0.001). LR-TR viable category with the use of arterial subtraction images compared with ordinary arterial-phase images showed a significant increase in sensitivity (76.7% [56/73] vs. 63.0% [46/73]; p = 0.002) without significant decrease in specificity (90.6% [29/32] vs. 93.8% [30/32]; p > 0.999). In a subgroup of 63 lesions treated with TACE only, the use of arterial subtraction images showed a significant increase in sensitivity (81.4% [35/43] vs. 67.4% [29/43]; p = 0.031) without significant decrease in specificity (85.0% [17/20] vs. 90.0% [18/20]; p > 0.999).ConclusionUse of arterial subtraction images compared with ordinary arterial-phase images improved the sensitivity while maintaining specificity for diagnosing viable HCC after LRT using gadoxetic acid-enhanced MRI and the LR-TR algorithm.     

Deep Learning-Based Assessment of Functional Liver Capacity Using Gadoxetic Acid-Enhanced Hepatobiliary Phase MRI

ObjectiveWe aimed to develop and test a deep learning algorithm (DLA) for fully automated measurement of the volume and signal intensity (SI) of the liver and spleen using gadoxetic acid-enhanced hepatobiliary phase (HBP)-magnetic resonance imaging (MRI) and to evaluate the clinical utility of DLA-assisted assessment of functional liver capacity.Materials and MethodsThe DLA was developed using HBP-MRI data from 1014 patients. Using an independent test dataset (110 internal and 90 external MRI data), the segmentation performance of the DLA was measured using the Dice similarity score (DSS), and the agreement between the DLA and the ground truth for the volume and SI measurements was assessed with a Bland-Altman 95% limit of agreement (LOA). In 276 separate patients (male:female, 191:85; mean age ± standard deviation, 40 ± 15 years) who underwent hepatic resection, we evaluated the correlations between various DLA-based MRI indices, including liver volume normalized by body surface area (LV_BSA), liver-to-spleen SI ratio (LSSR), MRI parameter-adjusted LSSR (aLSSR), LSSR × LV_BSA, and aLSSR × LV_BSA, and the indocyanine green retention rate at 15 minutes (ICG-R15), and determined the diagnostic performance of the DLA-based MRI indices to detect ICG-R15 ≥ 20%.ResultsIn the test dataset, the mean DSS was 0.977 for liver segmentation and 0.946 for spleen segmentation. The Bland-Altman 95% LOAs were 0.08% ± 3.70% for the liver volume, 0.20% ± 7.89% for the spleen volume, -0.02% ± 1.28% for the liver SI, and -0.01% ± 1.70% for the spleen SI. Among DLA-based MRI indices, aLSSR × LV_BSA showed the strongest correlation with ICG-R15 (r = -0.54, p < 0.001), with area under receiver operating characteristic curve of 0.932 (95% confidence interval, 0.895–0.959) to diagnose ICG-R15 ≥ 20%.ConclusionOur DLA can accurately measure the volume and SI of the liver and spleen and may be useful for assessing functional liver capacity using gadoxetic acid-enhanced HBP-MRI.     

Diagnostic Performance of 2018 KLCA-NCC Practice Guideline for Hepatocellular Carcinoma on Gadoxetic Acid-Enhanced MRI in Patients with Chronic Hepatitis B or Cirrhosis: Comparison with LI-RADS Version 2018

ObjectiveTo evaluate the performance of the 2018 Korean Liver Cancer Association-National Cancer Center (KLCA-NCC) Practice Guidelines (hereafter, PG) for the diagnosis of hepatocellular carcinoma (HCC) using gadoxetic acid-enhanced MRI, compared to the Liver Imaging-Reporting and Data System (LI-RADS) version 2018 (hereafter, v2018).Materials and MethodsFrom January 2013 to October 2015, treatment-naïve hepatic lesions (≥ 1 cm) on gadoxetic acid-enhanced MRI in consecutive patients with chronic hepatitis B or cirrhosis were retrospectively evaluated. For each lesion, three radiologists independently analyzed the imaging features and classified the lesions into categories according to the 2018 KLCA-NCC PG and LI-RADS v2018. The imaging features and categories were determined by consensus. Generalized estimating equation (GEE) models were used to compare the per-lesion diagnostic performance of the 2018 KLCA-NCC PG and LI-RADS v2018 using the consensus data.ResultsIn total, 422 lesions (234 HCCs, 45 non-HCC malignancies, and 143 benign lesions) from 387 patients (79% male; mean age, 59 years) were included. In all lesions, the definite HCC (2018 KLCA-NCC PG) had a higher sensitivity and lower specificity than LR-5 (LI-RADS v2018) (87.2% [204/234] vs. 80.8% [189/234], p < 0.001; 86.2% [162/188] vs. 91.0% [171/188], p = 0.002). However, in lesions of size ≥ 2 cm, the definite HCC had a higher sensitivity than the LR-5 (86.8% [164/189] vs. 82.0 (155/189), p = 0.002) without a reduction in the specificity (80.0% [48/60] vs. 83.3% [50/60], p = 0.15). In all lesions, the sensitivity and specificity of the definite/probable HCC (2018 KLCA-NCC PG) and LR-5/4 did not differ significantly (89.7% [210/234] vs. 91.5% [214/234], p = 0.204; 83.5% [157/188] vs. 79.3% [149/188], p = 0.071).ConclusionFor the diagnosis of HCC of size ≥ 2 cm, the definite HCC (2018 KLCA-NCC PG) had a higher sensitivity than LR-5, without a reduction in specificity. The definite/probable HCC (2018 KLCA-NCC PG) had a similar sensitivity and specificity to that those of the LR-5/4.     

MR Imaging in Patients with Suspected Liver Metastases: Value of Liver-Specific Contrast Agent Gadoxetic Acid

Objective

To compare the diagnostic performance of gadoxetic acid-enhanced magnetic resonance (MR) imaging with that of triple-phase multidetector-row computed tomography (MDCT) in the detection of liver metastasis.

Materials and Methods

Our institutional review board approved this retrospective study and waived informed consent. The study population consisted of 51 patients with hepatic metastases and 62 patients with benign hepatic lesions, who underwent triple-phase MDCT and gadoxetic acid-enhanced MRI within one month. Two radiologists independently and randomly reviewed MDCT and MRI images regarding the presence and probability of liver metastasis. In order to determine additional value of hepatobiliary-phase (HBP), the dynamic-MRI set alone and combined dynamic-and-HBP set were evaluated, respectively. The standard of reference was a combination of pathology diagnosis and follow-up imaging. For each reader, diagnostic accuracy was compared using the jackknife alternative free-response receiver-operating-characteristic (JAFROC).

Results

For both readers, average JAFROC figure-of-merit (FOM) was significantly higher on the MR image sets than on the MDCT images: average FOM was 0.582 on the MDCT, 0.788 on the dynamic-MRI set and 0.847 on the combined HBP set, respectively (p < 0.0001). The differences were more prominent for small (≤ 1 cm) lesions: average FOM values were 0.433 on MDCT, 0.711 on the dynamic-MRI set and 0.828 on the combined HBP set, respectively (p < 0.0001). Sensitivity increased significantly with the addition of HBP in gadoxetic acid-enhanced MR imaging (p < 0.0001).

Conclusion

Gadoxetic acid-enhanced MRI shows a better performance than triple-phase MDCT for the detection of hepatic metastasis, especially for small (≤ 1 cm) lesions.     

Imaging features of small hepatocellular carcinomas with microvascular invasion on gadoxetic acid-enhanced MR imaging

Objectives

Detection of hepatocellular carcinomas (HCCs) before microvascular invasion (MVI) occurs is important due to the poor outcomes associated with MVI. We retrospectively investigated the imaging features of small HCCs with MVI on gadoxetic acid-enhanced MR imaging.

Methods

Fifty patients (40 men and 10 women; mean age, 54 years) with 58 surgically proven small (2 cm or less) HCCs were evaluated by gadoxetic acid-enhanced MRI. Signal intensities on imaging sequences and the presence of the typical dynamic enhancement pattern (arterial enhancement and washout) were assessed. Fisher's exact tests were performed to evaluate the relationships between the presence of MVI, tumor size, and imaging findings.

Results

None of the 12 small HCCs with diameters of 1 cm or less had MVI, while 15 (33%) of the 46 small HCCs with diameters of 1.1–2.0 cm had MVI (p = 0.025, Fisher's exact test). Among the small HCCs with diameters of 1.1–2.0 cm, all HCCs with MVI showed the typical dynamic pattern and hyperintensity on T2- and diffusion-weighted images. Most HCCs (54 lesions, 93%) were hypointense on hepatobiliary phase images regardless of the presence of MVI.

Conclusions

All small HCCs with MVI showed typical dynamic pattern and hyperintensity on T2-weighted and diffusion-weighted images, while atypical dynamic pattern and size of less than 1 cm in diameter may suggest absence of MVI.     

Triple Arterial Phase MR Imaging with Gadoxetic Acid Using a Combination of Contrast Enhanced Time Robust Angiography,Keyhole, and Viewsharing Techniques and Two-Dimensional Parallel Imaging in Comparison with Conventional Single Arterial Phase

ObjectiveTo determine whether triple arterial phase acquisition via a combination of Contrast Enhanced Time Robust Angiography, keyhole, temporal viewsharing and parallel imaging can improve arterial phase acquisition with higher spatial resolution than single arterial phase gadoxetic-acid enhanced magnetic resonance imaging (MRI).ResultsThe late arterial phase was captured at least once in 96.4% (159/165) of the triple arterial phase group and in 84.2% (494/587) of the single arterial phase group (p < 0.001). Significant motion artifacts (score ≤ 2) were observed in 13.3% (22/165), 1.2% (2/165), 4.8% (8/165) on 1st, 2nd, and 3rd scans of triple arterial phase acquisitions and 6.0% (35/587) of single phase acquisitions. Thus, the late arterial phase without significant motion artifacts was captured in 96.4% (159/165) of the triple arterial phase group and in 79.9% (469/587) of the single arterial phase group (p < 0.001).ConclusionTriple arterial phase imaging may reliably provide adequate arterial phase imaging for gadoxetic acid-enhanced liver MRI.     

Intraindividual Comparison of Hepatocellular Carcinoma Washout between MRIs with Hepatobiliary and Extracellular Contrast Agents

ObjectiveTo intraindividually compare hepatocellular carcinoma (HCC) washout between MRIs using hepatobiliary agent (HBA) and extracellular agent (ECA).Materials and MethodsThis study included 114 prospectively enrolled patients with chronic liver disease (mean age, 55 ± 9 years; 94 men) who underwent both HBA-MRI and ECA-MRI before surgical resection for HCC between November 2016 and May 2019. For 114 HCCs, the lesion-to-liver visual signal intensity ratio (SIR) using a 5-point scale (−2 to +2) was evaluated in each phase. Washout was defined as negative visual SIR with temporal reduction of visual SIR from the arterial phase. Illusional washout (IW) was defined as a visual SIR of 0 with an enhancing capsule. The frequency of washout and MRI sensitivity for HCC using LR-5 or its modifications were compared between HBA-MRI and ECA-MRI. Subgroup analysis was performed according to lesion size (< 20 mm or ≥ 20 mm).ResultsThe frequency of portal venous phase (PP) washout with HBA-MRI was comparable to that of delayed phase (DP) washout with ECA-MRI (77.2% [88/114] vs. 68.4% [78/114]; p = 0.134). The frequencies were also comparable when IW was allowed (79.8% [91/114] for HBA-MRI vs. 81.6% [93/114] for ECA-MRI; p = 0.845). The sensitivities for HCC of LR-5 (using PP or DP washout) were comparable between HBA-MRI and ECA-MRI (78.1% [89/114] vs. 73.7% [84/114]; p = 0.458). In HCCs < 20 mm, the sensitivity of LR-5 was higher on HBA-MRI than on ECA-MRI (70.8% [34/48] vs. 50.0% [24/48]; p = 0.034). The sensitivity was similar to each other if IW was added to LR-5 (72.9% [35/48] for HBA-MRI vs. 70.8% [34/48] for ECA-MRI; p > 0.999).ConclusionExtracellular phase washout for HCC diagnosis was comparable between MRIs with both contrast agents, except for tumors < 20 mm. Adding IW could improve the sensitivity for HCC on ECA-MRI in tumors < 20 mm.     

肝脏占位性病变的磁共振成像研究：超顺磁性氧化铁与钆喷替酸葡甲胺的比较

通过与常用造影剂钆喷替酸葡甲胺（Gd-DTPA）的配对实验来评价新型造影剂超磁性氧化铁（SPIO）对有肝占位的检出率和定性诊断能力。材料和方法：53个病例132个肝占位首日行平扫及Gd-DTPA的动态增强扫描,次日行SPIO增强扫描,对照病理及临床随访证实结果,探讨各种占位SPIO增强扫描的强化特点,比较平扫联合Gd-DTPA动态增强扫描与平扫联合SPIO增强扫描的病灶检出率和定性诊断率。结果：SPIO增强扫描良性肝占位的信号随肝实质降低,而恶性肝占位的信号保持不变。平扫联合SPIO增强扫描的病灶检出率和定性诊断率较平扫联合Gd-DTPA增强扫描的略高,但统计学上相差不显著。结论：SPIO强化的原理、强化方式直至临床应用方法、特点与Gd-DTPA均完全不同,两者可相互补充和印证,当Gd-DTPA动态增强扫描定性诊断困难时应积极行SPIO增强扫描。     

Prediction of Decompensation and Death in Advanced Chronic Liver Disease Using Deep Learning Analysis of Gadoxetic Acid-Enhanced MRI

ObjectiveThis study aimed to evaluate the usefulness of quantitative indices obtained from deep learning analysis of gadoxetic acid-enhanced hepatobiliary phase (HBP) MRI and their longitudinal changes in predicting decompensation and death in patients with advanced chronic liver disease (ACLD).Materials and MethodsWe included patients who underwent baseline and 1-year follow-up MRI from a prospective cohort that underwent gadoxetic acid-enhanced MRI for hepatocellular carcinoma surveillance between November 2011 and August 2012 at a tertiary medical center. Baseline liver condition was categorized as non-ACLD, compensated ACLD, and decompensated ACLD. The liver-to-spleen signal intensity ratio (LS-SIR) and liver-to-spleen volume ratio (LS-VR) were automatically measured on the HBP images using a deep learning algorithm, and their percentage changes at the 1-year follow-up (ΔLS-SIR and ΔLS-VR) were calculated. The associations of the MRI indices with hepatic decompensation and a composite endpoint of liver-related death or transplantation were evaluated using a competing risk analysis with multivariable Fine and Gray regression models, including baseline parameters alone and both baseline and follow-up parameters.ResultsOur study included 280 patients (153 male; mean age ± standard deviation, 57 ± 7.95 years) with non-ACLD, compensated ACLD, and decompensated ACLD in 32, 186, and 62 patients, respectively. Patients were followed for 11–117 months (median, 104 months). In patients with compensated ACLD, baseline LS-SIR (sub-distribution hazard ratio [sHR], 0.81; p = 0.034) and LS-VR (sHR, 0.71; p = 0.01) were independently associated with hepatic decompensation. The ΔLS-VR (sHR, 0.54; p = 0.002) was predictive of hepatic decompensation after adjusting for baseline variables. ΔLS-VR was an independent predictor of liver-related death or transplantation in patients with compensated ACLD (sHR, 0.46; p = 0.026) and decompensated ACLD (sHR, 0.61; p = 0.023).ConclusionMRI indices automatically derived from the deep learning analysis of gadoxetic acid-enhanced HBP MRI can be used as prognostic markers in patients with ACLD.     

MR T_1WI梯度回波同、反相位序列肝癌信号强度变化规律的研究

目的:分析肝细胞肝癌(HCC)与正常肝组织在同、反相位序列上信号强度相对变化的规律,以及肝癌信号变化与肿瘤大小的相关性。方法:收集病理证实、未经治疗的HCC共113例(女15例,男98例,年龄34～85岁,平均57.55岁)。在MRI同、反相位图像上分别测量正常肝组织和HCC的信号强度。统计分析①计算正常肝组织、HCC在同、反相位上的信号强度,及信号变化指数(SI);②比较正常肝组织、HCC在同、反相位上的信号强度绝对值变化的差异;③分析正常肝组织、HCC在同、反相位上的信号强度正向和负向变化病例数的差异;④计算经肝组织校正后HCC的SI(SI校正),分析SI校正与肿瘤体积的相关性。结果:①113例HCC同相位平均信号强度为739.54±187.95,反相位平均信号强度为724.19±194.58,同、反相位平均信号强度减低15.35±92.66,SIHCC为2.0%。113例正常肝组织同相位平均信号强度为840.58±184.98,反相位平均信号强度为854.63±204.65,同、反相位平均信号强度升高14.05±85.36,SI为-1.7%。两者信号强度变化具有统计学的差异(P=0.002);②HCC同、反相位信号升高(正向)53例、降低(负向)59例;正常肝组织信号升高66例、信号降低47例,差异没有显著性(P=0.425);③SI校正为0.2%～31.6%,平均3.41%。SI校正与肿瘤大小之间没有显著相关性(P=0.997)。结论:正常肝脏组织和HCC在同、反相位信号强度存在正向、负向的变化和程度上的差异;在反相位图像上,HCC和肝组织的对比度要好于同相位图像。HCC的信号变化与肿瘤大小没有相关性。     

原发性肝癌MnDPDP增强MRI两种T1W成像序列的比较研究

目的 :比较研究原发性肝癌MnDPDP增强MRI两种T1W成像序列的价值。材料和方法 :对36例原发性肝细胞癌(HCC)进行MnDPDP增强MRI前瞻性研究。平扫序列为SET1WI、FSET2W和FMPSPGRT1WI。静脉滴注MnDPDP后5min开始行FMPSPGRT1WI和SET1WI ,每隔5min成像一次直至40min ;并进行延迟24h成像。三位资深MRI诊断医师以盲法分别比较两种T1W图像(SET1WI和FMPSPGRT1WI)的信噪比(S/N)、对比度噪声比(C/N)、病灶的显示率和定性诊断率 ,以及两种T1W图像上HCC的信号强度差异。结果 :(1)MnDPDP增强后不同延迟时间的两种T1W图像之间的S/N±SD均无显著差异(p>0.05) ,而C/N±SD于延迟5min至40minFMPSPGRT1W图像优于SET1W(p<0.01) ;但延迟24hSET1W图像的C/N±SD优于FMPSPGRT1W(p<0.01)。(2)SET1W图像上HCC呈高信号的概率明显高于FMPSPGRT1W(5～40min :58.8 %对21.6 % ;24h :80.4 %对43.3 %)(p<0.005)。(3)SET1W和FMPSPGRT1W的HCC检出率均为92.7 % ;两者的定性率分别为92.7 %(SE)和87.3 %(FMPSPGR)。结论 :MnDPDP增强两种T1WMR图像对HCC的检出率相当 ,定性以SET1W稍优。作者推荐的HCC检查方案为 :(1)10～40min之间成像一次 ,序列为SET1W或(和)FMPSPGRT1W ;(2)延迟24h成像一次 ,序列为SET1W。     

不同注射流率及动脉期期相选择对肝脏普美显增强MRI图像质量的影响

目的 探讨肝脏普美显增强MRI中,不同对比剂注射流率及动脉期期相的选择对动脉期伪影及整体图像质量的影响.方法 随机选取300例患者分为3组,每组100例,扫描中分别采用1.0 ml/s、1.5 mL/s和2.0ml/s的对比剂注射流率.对所得图像质量进行评估,计算图像整体得分、动脉期伪影得分,对所得图像按照动脉期期相分组标准分为动脉早期组及晚期组,并比较各组无伪影率.结果 实际入组进行扫描的患者281例,1.0 ml/s组、1.5 ml/s组、2.0 ml/s组图像质量总体得分为16.79±1.9275、16.64±1.90、10.64±3.32,经统计分析,1.0ml/s组与1.5 ml/s组间图像质量总体得分差异有显著性意义,P＞0.05(P =0.601);1.0 ml/s组、1.5 ml/s组与2.0ml/s组间差异有显著性意义,P＜0.05(P =0.000、0.000),即2.0 ml/s组图像得分低于其他2组.1.0 ml/s组、1.5ml/s组与2.0 ml/s组动脉期伪影得分情况为2.543±0.669、2.277 ±0.781、1.526±0.861,经两两比较分析3组间差异有显著性意义,即动脉期图像质量1.0 ml/s组优于其他2组.281例受检者中属于动脉早期118例,属动脉晚期163例,动脉早、晚期的无伪影率分别为50.8％、73％,差异有统计学意义(P=0.00),即动脉晚期伪影发生率低于动脉早期.动脉期晚期中无伪影者119例中1.0 ml/s、1.5 ml/s及2.0 ml/s组中所占比率分别为61.3％、34.5％、4.2％例,3组间差异显著,即在动脉晚期组中1.0 ml/s组伪影发生率明显低于其他2组.结论 在肝脏普美显增强MRI中,以1.0 ml/s、1.5 ml/s流率注射对比剂,所得整体图像质量优于2.0 ml/s流率注射.动脉期伪影情况1.0 ml/s组明显优于其他2组,在动脉晚期组中1.0 ml/s组的伪影发生率最低.故以1.0 ml/s流率注射对比剂并于肝动脉晚期采集图像,能明显改善图像质量.     

The value of paradoxical uptake of hepatocellular carcinoma on the hepatobiliary phase of gadoxetic acid-enhanced liver magnetic resonance imaging for the prediction of lipiodol uptake after transcatheter arterial chemoembolization

PurposeTo compare the response to transcatheter arterial chemoembolization (TACE) between hepatocellular carcinoma (HCC) with paradoxical uptake on the hepatobiliary phase (HBP) (HCC_para) and HCC with defect on the HBP (HCC_def), and to identify some imaging features that can differentiate between two groups.Materials and methodsNinety-three HCCs from 54 patients who underwent gadoxetic acid-enhanced liver magnetic resonance imaging (MRI) prior to TACE were included. HCCs were classified into two groups according to the signal intensity (SI) on the HBP: HCC_para and HCC_def. Using post-TACE computed tomography (CT) as a reference standard, initial compact lipiodol uptake was assessed and compared between groups. The arterial enhancement ratio (AER), SI ratios of the arterial phase and HBP, and presence of the capsule appearance were compared between groups. After initial response, local tumor recurrence within 6 and 18 months was evaluated based on follow-up CT or MRI.ResultsFifteen HCC_para and 78 HCC_def were included. Compared to HCC_def, HCC_para showed more frequent initial compact lipiodol uptake (p = 0.009), larger mean size (p = 0.019), lower AER (p = 0.005), higher SI ratio of the HBP (p < 0.0001), and more frequent capsule appearance (p < 0.0001). Local tumor recurrence rate within 6 months was also significantly lower in HCC_para than in HCC_def (p = 0.008).ConclusionDespite larger size and lower AER, HCC_para showed more frequent initial compact lipiodol uptake and lower early local recurrence rate after TACE than did HCC_def.     

晚期肝硬化肝脏MR灌注成像的灌注量化分析

目的:使用动态增强MR成像技术获得的肝灌注系数(HPI),评价其在反映肝移植前晚期肝硬化患者肝脏血供特点中的价值。方法:使用1.5T MR扫描仪对100例正常肝脏组和57例晚期肝硬化患者移植前的受体肝脏进行快速团注对比剂(Gd-DTPA)后的斜冠状断面单层2D SPGR序列的MR灌注成像检查,比较对照组和肝硬化组门静脉和肝实质的时间-信号强度变化曲线(TIC)特点及峰值时间。根据腹腔干水平腹主动脉和门静脉主干的TIC为参照设置时间参数,计算受检者肝脏实质动脉期和静脉期的正增强系数(PEI)。设定肝灌注系数(HPI)=动脉期PEI/(动脉期PEI 门脉期PEI)×100%。对两组受检者HPI进行统计分析,根据HPI的受试者工作特性曲线(receiver operator characteristiccurve,ROCcurve)选择诊断肝硬化的HPI参考标准。结果:对照组及肝硬化组门静脉曲线峰值时间分别为(38.66±4.14)s和(55.51±5.31)s,P<0.01;肝实质TIC峰值时间分别为(56.24±4.47)s和(81.39±7.02)s,P<0.01;对照组及肝硬化组肝实质的HPI分别为(18.9±3.5)%和(26.4±5.5)%,P<0.01;应用HPI>21.6%为诊断肝硬化的标准,敏感度为86%,特异度为85%,阳性预测值为77%,阴性预测值为91%,诊断符合率为85%。结论:MR灌注成像技术可以在活体状态下无创分析肝内血供,此技术可用于评估晚期肝硬化患者肝移植前肝脏内的血流灌注。     

Hypovascular hepatic nodule showing hypointensity in the hepatobiliary phase of gadoxetic acid-enhanced MRI in patients with chronic liver disease: prediction of malignant transformation

Purpose

To investigate the predictive factors of malignant transformation of hypovascular hepatic nodule showing hypointensity in the hepatobiliary phase images of gadoxetic acid-enhanced MRI (HHN).

Materials and Methods

The clinical data and imaging findings of dynamic contrast-enhanced computed tomography (DCE-CT) and gadoxetic acid-enhanced MRI for a total of 103 HHNs in 24 patients with chronic liver disease were retrospectively investigated. After the results of follow-up examinations were investigated, HHNs were categorized into the three groups for each comparison: (1) nodules with enlargement and/or vascularization and others, (2) nodules with only enlargement and others, (3) nodules with only vascularization and others. Enlargement and/or vascularization during the follow-up period were defined as malignant transformation of HHN. The frequency of each clinical datum and imaging finding in each group was compared to identify the predictive factors for malignant transformation in HHN.

Results

Multivariate analysis showed that a nodule size of 9 mm or more on the initial gadoxetic acid-enhanced MRI was a significant predictive factor for the enlargement and/or vascularization of HHN (P < 0.05). On the other hand, the hypoattenuation on the delayed phase imaging of the initial DCE-CT was a significant predictive factor for the enlargement or vascularization of HHN (P < 0.05).

Conclusion

A nodule size of 9 mm or more on the initial gadoxetic acid-enhanced MRI and hypoattenuation on the delayed phase imaging of initial DCE-CT would be helpful for predicting the outcome of HHN in patients with a risk of hepatocellular carcinoma.     

MR扩散加权成像在氟尿嘧啶治疗小鼠皮下移植肝癌疗效评价中的价值

目的:探讨磁共振DWI成像技术在氟尿嘧啶治疗小鼠皮下移植肝癌疗效评价中的作用.方法:将小鼠随机分为两组,制备小鼠H22皮下种植肝癌模型.种植成功第5天后,A组隔天给予氟尿嘧啶腹腔注射,B组给予蒸馏水灌胃.第15天进行MR检查,测量肿瘤组织的表观扩散系数(ADC).检查完毕后处死小鼠,测量血清中血管生成因子(VEGF)水平;取瘤体及脾脏分别称重,计算肿瘤指数及脾脏指数;检测新鲜肿瘤组织肝癌细胞凋亡的DNA百分比.将两组小鼠的ADC值及实验室数据行t检验,分析两组小鼠ADC值与各实验室结果的相关性.结果:在扩散敏感因子(b)=600s/mm~2及1200s/mm~2的DWI图像中,肝癌多表现为高信号,其内的坏死部分为低信号.A组、B组肿瘤实质部分的ADC值分别为:780±122mm~2/s、596.50±80.17mm~2/s;1421 ±160mm~2/s、1232.804-85.02mm~2/s,两者具有统计学差异(P<0.05).肿瘤实质成分的ADC值与血清中VEGF水平、肝癌细胞凋亡的DNA百分比、处死后称得的瘤体及脾脏重量存在相关性.结论:ADC值可以反映氟尿嘧啶对肿瘤生长抑制的情况,MR DWI技术及ADC值在氟尿嘧啶治疗小鼠皮下移植肝癌疗效评价方面具有可行性.     

影响脂肪肝MR波谱分析结果因素的研究

目的:探讨影响脂肪肝1H-MRS成像的相关技术因素。方法:对13例脂肪肝病例及7例健康志愿者行常规MR扫描及MR波谱成像。分析自动预扫描、感兴区的选择、饱和带的使用、高阶匀场等技术因素对脂肪肝MR波谱分析结果的影响。结果:做自动预扫描、使用饱和带和高阶匀场、调节定位、使感兴趣区远离骨质和气体,有19例(95%)波谱正常,呈左高右低的原始波谱曲线,曲线通过校准和后处理,呈现代表水峰和脂肪峰的波谱线。未做自动预扫描、未使用饱和带和高阶匀场,有2例(10%)出现化学物质的峰线过宽;其余18例中,3例(15%)出现波谱曲线的基线呈明显的锯齿状;12例(60%)出现整个波谱曲线呈锯齿状,没有任何化学物质的尖峰,3例(15%)扫描失败,18例均无法进行图像校准和后处理。结论:自动预扫描、使用饱和带和高阶匀场,同时调节定位,使感兴区远离骨质和气体是决定波谱采集成功与否的重要因素。     

基于体素内不相干运动扩散加权成像在肝细胞癌术前分级中的应用分析

目的 探讨基于体素内不相干运动(IVIM)扩散加权成像(DWI)在肝细胞癌(HCC)术前分级中的可行性. 方法 回顾性分析35例HCC患者的影像学及病理资料.以Edmondson-Steiner分级法为依据分为低、高级别组,应用双指数函数分别计算两组的真实扩散系数(D值)、灌注相关扩散系数(D*值)及灌注分数(f值).组间比较采用非参数检验Mann-WhitneyU,3个参数间的预测效能比较用受试者工作特征曲线(ROC)分析,当P＜0.05认为差异有统计学意义.结果 低级别组15例,高级别组20例.低级别组D、D*及f值的均值分别为(1.20±0.32) ×10-3 mm2/s、(42.57±11.07) ×10-3 mm2/s、(23.19±10.02)％,高级别组D、D*及f值的均值分别为(0.76±0.18)×10-3 mm2/s、(53.89±12.74)×10-3mm2/s、(30.07±12.42)％,与高级别组的HCC相比较,低级别组的D值增大,D *值减小,组间均存在统计学差异(U=22.5、62.0,P＜0.05);f值减小,组间不存在统计学差异(U=82.0,P＞0.05).D值、D*值的ROC曲线下面积(AUC)为0.92、0.77,根据最大约登指数确定两者的最佳诊断阈值分别为0.91×10-3mm2/s、53.1×10-3mm2/s.结论 IVIM DWI对术前预测HCC的低、高级别有一定帮助,其中D值的诊断效能最大.