Outcome of hypovascular hepatic nodules revealing no gadoxetic acid uptake in patients with chronic liver disease

Purpose:

To elucidate the natural history of hypovascular nodules that appear hypointense on hepatocyte‐phase gadoxetic acid‐enhanced MR images by focusing on hypervascularization over time.

Materials and Methods:

In this study, 135 hypovascular nodules revealing no gadoxetic acid uptake in 53 patients were examined. All nodules were retrospectively examined using serial follow‐up computed tomography (CT) and MRI examinations until hypervascularity was observed on arterial‐phase dynamic CT or gadoxetic acid‐enhanced MR images, or on CT during hepatic arteriography. Logistic regression analysis was used to investigate the association between hypervascularization and MR findings including a presence of fat assessed by a signal drop on opposed‐phase T1‐weighted images.

Results:

Of the 135 nodules, 16 underwent hypervascularization. The size of the nodules and the presence of fat in the nodules were independent indicators of hypervascularization. The 1‐year cumulative risk of hypervascularization was 15.6%. This risk was significantly increased in the case of nodules >10 mm (37.6%, P < 0.01) and fat‐containing nodules (26.5%, P < 0.01).

Conclusion:

Hypovascular nodules that appear hypointense on hepatocyte‐phase gadoxetic acid‐enhanced MR images may progress to conventional hypervascular hepatocellular carcinoma. Nodules more than 10 mm in diameter and containing fat are at high risk for developing hypervascularization. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.     

Detection of hepatocellular carcinoma by Gd-EOB-DTPA-enhanced liver MRI: Comparison with triple phase 64 detector row helical CT

Purpose

To compare the diagnostic performance of Gd-EOB-DTPA-enhanced MRI with that of triple phase 64-MDCT in the detection of hepatocellular carcinoma (HCC).

Patients and methods

Thirty-four patients with 52 surgically proven lesions underwent Gd-EOB-DTPA-enhanced MRI and triple phase 64-MDCT. Two observers independently evaluated MR and CT imaging on a lesion-by-lesion basis. Sensitivity, positive and negative predictive values and reproducibility were evaluated. The diagnostic accuracy of each modality was assessed with alternative-free response receiver operating characteristic (ROC) analysis.

Results

Both observers showed higher sensitivity in detecting lesions with MRI compared to CT, however, only the difference between the two imaging techniques for observer 2 was significant (P = 0.034). For lesions 1 cm or smaller, MRI and CT showed equal sensitivity (both 62.5%) with one observer, and MRI proved superior to CT with the other observer (MRI 75% vs. CT 56.3%), but the latter difference was not significant (P = 0.083). The difference in positive and negative predictive value between the two imaging techniques for each observer was not significant (P > 0.05). The areas under the ROC curve for each observer were 0.843 and 0.861 for MRI vs. 0.800 and 0.833 for CT and the differences were not significant. Reproducibility was higher using MRI for both observers, but the result was not significant (MRI 32/33 vs. CT 29/33, P = 0.083).

Conclusion

Gd-EOB-DTPA-enhanced MRI tended to show higher diagnostic accuracy, sensitivity and reproducibility compared to triple phase 64-MDCT in the detection of hepatocellular carcinoma, however statistical significance was not achieved.     

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.     

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.     

Consensus report from the 6th International forum for liver MRI using gadoxetic acid

As the utility of liver‐specific magnetic resonance imaging (MRI) increases, it is pertinent to optimize and expand protocols to improve accuracy and foster evolution of techniques; in turn, positive impacts should be seen in patient management. This article reports on the latest expert thinking and current evidence in the field of liver‐specific MRI, as discussed at the 6^th International Forum for Liver MRI, which was held in Vancouver, Canada in September 2012. Topics discussed at this forum described the use of gadoxetic acid‐enhanced MRI for the assessment of liver function at the segmental level; to increase accuracy in the diagnosis of liver metastases; to overcome current challenges in patients with cirrhosis, including management of arterial hypo‐/isovascular, hepatobiliary phase hypointense nodules; and the data which would be required in order to recommend the use of this modality in hepatocellular carcinoma management guidelines. Growing evidence suggests that gadoxetic acid‐enhanced MRI can help to improve the management of patients with a number of different liver disorders; however, more data are needed in some areas, and there may be a case for developing an interpretation guideline for gadoxetic acid‐enhanced MRI findings to aid standardization. J. Magn. Reson. Imaging 2014;40:516–529 . © 2013 Wiley Periodicals, Inc .     

Feasibility of semiquantitative liver perfusion assessment by ferucarbotran bolus injection in double-contrast hepatic MRI

Purpose:

To evaluate the feasibility of semiquantitative measurement of liver perfusion from analysis of ferucarbotran induced signal‐dynamics in double‐contrast liver MR‐imaging (DC‐MRI).

Materials and Methods:

In total 31 patients (21 men; 58 ± 10 years) including 18 patients with biopsy proven liver cirrhosis prospectively underwent clinically indicated DC‐MRI at 1.5 Tesla (T) with dynamic T2*‐weighted gradient‐echo imaging after ferucarbotran bolus injection. Breathing artefacts in tissue and input time curves were reduced by Savitzky‐Golay‐filtering and semiquantitative perfusion maps were calculated using a model free approach. Hepatic blood flow index (HBFI) and splenic blood flow index (SBFI) were determined by normalization of arbitrary perfusion values to the perfusion of the erector spinae muscle resulting in a semiquantitative perfusion measure.

Results:

In 30 of 31 patients the evaluated protocol could successfully be applied. Mean HBF was 7.7 ± 2.46 (range, 4.6–12.8) and mean SBF was 13.20 ± 2.57 (range, 8.5–17.8). A significantly lower total HBF was seen in patients with cirrhotic livers as compared to patients with noncirrhotic livers (P < 0.05). In contrast, similar SBF was observed in cirrhotic and noncirrhotic patients (P = 0.11).

Conclusion:

Capturing the signal dynamics during bolus injection of ferucarbotran in DC‐MRI of the liver allows for semiquantitative assessment of hepatic perfusion that may be helpful for a more precise characterisation of liver cirrhosis and focal liver lesions. J. Magn. Reson. Imaging 2012;36:168–176. © 2012 Wiley Periodicals, Inc.     

Comparison of three different injection methods for arterial phase of Gd-EOB-DTPA enhanced MR imaging of the liver

Objective

To compare three different injection methods for optimizing hepatic arterial phase of gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB-DTPA) enhanced MR imaging.

Methods

Arterial phase images were obtained after the injection of contrast agent at a rate of 3 mL/s with diluted Gd-EOB-DTPA (dilution method) in 27 patients, 3 mL/s with undiluted Gd-EOB-DTPA (3 mL method) in 26 patients and 1 mL/s with undiluted Gd-EOB-DTPA (1 mL method) in 28 patients. In the quantitative evaluation, signal-to-phantom ratios (SPR) of the liver parenchyma, pancreas, renal cortex, portal vein and aorta were evaluated. In the qualitative evaluation, the seven items for image quality of hepatic arterial phase were assessed, and the total score of all items in each subject was calculated.

Results

The score of enhancement of abdominal aorta and total score of seven items in 1 mL method were significantly higher than those in 3 mL method. The SPR of the liver parenchyma in 3 mL method was significantly higher than that in 1 mL method, suggesting substantial hepatic inflow from portal venous return.

Conclusion

For the optimal arterial phase imaging, injection rate of 1 mL/s with undiluted Gd-EOB-DTPA is convenient and preferable, compared with other two methods, based on our qualitative analysis.     

Enhancement of liver parenchyma after injection of hepatocyte‐specific MRI contrast media: A comparison of gadoxetic acid and gadobenate dimeglumine

Purpose:

To compare enhancement of liver parenchyma in MR imaging after injection of hepatocyte‐specific contrast media.

Materials and Methods:

Patients (n = 295) with known/suspected focal liver lesions randomly received 0.025 mmol gadoxetic acid/kg body weight or 0.05 mmol gadobenate dimeglumine/kg body weight by means of bolus injection. MR imaging was performed before and immediately after injection, and in the delayed phase at approved time points (20 min after injection of gadoxetic acid and 40 min after injection of gadobenate dimeglumine). The relative liver enhancement for the overall population and a cirrhotic subgroup was compared in T1‐weighted GRE sequences. An independent radiologist performed signal intensity measurements. Enhancement ratios were compared using confidence intervals (CIs).

Results:

The relative liver enhancement in the overall population was superior with gadoxetic acid (57.24%) versus gadobenate dimeglumine (32.77%) in the delayed‐imaging phase. The enhancement ratio between the contrast media was statistically significant at 1.75 (95% CI: 1.46–2.13). In the delayed phase, the enhancement of cirrhotic liver with gadoxetic acid (57.00%) was comparable to that in the overall population. Enhancement with gadobenate dimeglumine was inferior in cirrhotic liver parenchyma (26.85%).

Conclusion:

In the delayed, hepatocyte‐specific phase, liver enhancement after injection of gadoxetic acid was superior to that obtained with gadobenate dimeglumine. J. Magn. Reson. Imaging 2010; 31: 356–364. © 2010 Wiley‐Liss, Inc.

     

Enhancement of the liver and pancreas in the hepatic arterial dominant phase: Comparison of hepatocyte‐specific MRI contrast agents,gadoxetic acid and gadobenate dimeglumine,on 3 and 1.5 tesla MRI in the same patient

Purpose:

To evaluate the relative enhancement of liver, pancreas, focal nodular hyperplasia (FNH), pancreas‐to‐liver index, and FNH‐to‐liver index in the hepatic arterial dominant phase (HADP) after injection of hepatocyte‐specific MRI contrast agents, gadoxetic acid and gadobenate dimeglumine, on 3 and 1.5 Tesla (T) MRI in the same patient.

Materials and Methods:

The MRI database was retrospectively searched to identify consecutive patients who underwent abdominal MRI at 3T and 1.5T systems, using both 0.025 mmol/kg gadoxetic acid‐enhanced and 0.05 mmol/kg gadobenate dimeglumine‐enhanced MRI at the same magnetic strength field system. 22 patients were identified, 10 were scanned at 3T system and 12 at 1.5T system. The enhancement of liver, pancreas, and FNH was evaluated quantitatively on MR images.

Results:

The relative enhancement of liver in HADP in the gadobenate dimeglumine‐enhanced group in all subjects was significantly higher than that in gadoxetic acid‐enhanced group (P = 0.023). The gadobenate dimeglumine‐enhanced group in HADP had better relative enhancement of pancreas and FNH, pancreas‐to‐liver index, and FNH‐to‐liver index than gadoxetic acid‐enhanced group, but the difference was not statistically significant.

Conclusion:

The 0.05 mmol/kg gadobenate dimeglumine‐enhanced abdominal MRI studies at 3T and 1.5T MR systems are superior in relative enhancement of the liver in HADP to 0.025 mmol/kg gadoxetic acid‐enhanced MRI. This type of assessment may provide comparative effectiveness data. J. Magn. Reson. Imaging 2013;37:903–908. © 2012 Wiley Periodicals, Inc.     

Dynamic and delayed contrast enhancement in upper abdominal MRI studies: comparison of gadoxetic acid and gadobutrol

OBJECTIVE: To prospectively compare contrast properties of extracelullar (gadobutrol) and hepatospecific (gadoxetic acid) contrast agents in upper abdominal MRI studies. MATERIALS AND METHODS: Standardized (0.1 ml/kg) dose of gadobutrol (56 subjects) and gadoxetic acid (51 subjects) was administered intravenously by MRI-compatible injector at 2 ml/s, followed by 20 ml saline flush. MR signal intensity changes (SIC) between precontrast scans and arterial phase, portal venous phase, equilibrium, and delayed scans at 10 and 20 min were measured in abdominal aorta, portal vein, common bile duct, liver, and spleen. Mean SIC values for gadobutrol and gadoxetic acid were compared by a two-sample t-test with p-value <0.05 considered significant. RESULTS: In abdominal aorta, the mean SIC in the arterial phase did not significantly differ between gadobutrol (330%) and gadoxetic acid (295%). In portal vein, the mean SIC in the portal venous phase significantly differed between gadobutrol (267%) and gadoxetic acid (176%). Liver parenchyma enhancement was significantly higher for gadobutrol than for gadoxetic acid in both arterial phase (28 versus 13%) and portal venous phase (81 versus 46%). On the contrary, gadobutrol reached significantly lower mean SIC in the liver on delayed scans at 10 min (47 versus 59%) and 20 min (40 versus 67%), as well as in common bile duct at 10 min (54 versus 133%) and 20 min (57 versus 457%), respectively. In the spleen, mean SIC for gadobutrol was significantly higher at all phases. CONCLUSION: Gadobutrol showed superior enhancement of upper abdominal structures in the dynamic phases whereas gadoxetic acid showed better enhancement of the hepatobiliary structures on delayed scans.     

Characterization of hyperintense nodules on precontrast T1-weighted MRI: utility of gadoxetic acid-enhanced hepatocyte-phase imaging

Purpose:

To evaluate the utility of gadoxetic acid‐enhanced hepatocyte‐phase magnetic resonance imaging (MRI) in characterization of T1‐weighted hyperintense nodules within cirrhotic liver.

Materials and Methods:

This retrospective study was approved by our Institutional Review Board. Thirty‐four nodules hyperintense in unenhanced T1‐weighted MRI with histopathological confirmation from a collection of 19 patients were included. Tumor size, signal intensity on T1‐weighted, and T2‐weighted imaging as well as enhancement patterns on contrast‐enhanced dynamic/hepatocyte‐phase imaging were recorded. Receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic performance of hepatocyte‐phase imaging.

Results:

Evaluation of the nodules with standard of reference revealed 15 dysplastic nodules (DN), seven well‐differentiated hepatocellular carcinomas (wHCC), and 12 moderately differentiated HCCs (mHCC). The mean size of dysplastic nodules was smaller than that of HCCs (P < 0.001). Using the HCC criteria (T2W or arterial enhancement followed with portal venous washout), 11/19 HCC were correctly characterized. Using solely hypointensity (compared to the surrounding liver parenchyma) during the hepatocyte phase as the criterion, 18/19 HCC were correctly characterized. There were seven additional HCCs diagnosed with hepatocyte‐phase imaging (P = 0.02).

Conclusion:

Gadoxetic acid‐enhanced MRI with hepatocyte‐phase imaging is superior to gadoxetic acid‐enhanced MRI with conventional criteria alone in characterization of T1W hyperintense nodules. J. Magn. Reson. Imaging 2011;33:625–632. © 2011 Wiley‐Liss, Inc.     

Changes in the signal- and contrast-to-noise ratios of hepatocellular carcinomas on gadoxetic acid-enhanced dynamic MR imaging

Objective

Our objective was to evaluate whether the enhancement pattern, measured by changes in the signal- (SNRs) and contrast-to-noise ratios (CNRs), of hepatocellular carcinomas (HCCs) on gadoxetic acid-enhanced MRI reflects tumor differentiation.

Subjects and methods

Two hundred eighty-five patients with 286 surgically-confirmed HCCs who underwent gadoxetic acid-enhanced MRI were included (11 grade I, 267 grade II, 7 grade III, and 1 grade IV tumor). Unenhanced and dynamic images with a T1-weighted 3D turbo-field-echo sequence were obtained. Relative signal intensities of the tumors with respect to surrounding liver were evaluated and the SNRs and CNRs were calculated.

Results

SNR measurements demonstrated a fluctuating pattern (an increase in the SNR, followed by a decrease and a subsequent increase [or a decrease in the SNR followed by an increase and a subsequent decrease]) in 282 of 286 (98.6%) tumors. The SNR measurements also showed a single-peak SNR in the arterial phase (1.0% [3/286]) and 3 min delayed images (0.3% [1/286]) followed by a decrease in 4 (1.4% [4/286]) grade II tumors. Nearly all tumors (88.1% [252/286]), 9 (81.8% [9/11]) grade I, 236 (88.4% [236/267]) grade II, 6 (85.7% [6/7]) grade III, and 1 (100% [1/1]) grade IV tumor showed maximum absolute CNRs with negative values, which were most commonly found in 20 min delayed images (67.5% [170/252]). The remaining 34 of 286 (11.9%) tumors showed maximum absolute CNRs with positive values.

Conclusion

Regardless of the tumor grades, the most common manifestation was a SNR with a fluctuating pattern with time and maximum absolute CNRs with negative values, which were most commonly noted in the hepatobiliary phase.     

Hepatocellular MR contrast agents: enhancement characteristics of liver parenchyma and portal vein after administration of gadoxetic acid in comparison to gadobenate dimeglumine

Purpose

To investigate the enhancement characteristics of liver parenchyma and portal vein as well as the portal vein-to liver contrast in Gd-EOB-DTPA- and Gd-BOPTA-enhanced abdominal MRI.

Materials and methods

The local institutional review board approved this retrospective study. A total of 70 patients (30 female, 40 male) without relevant liver disease underwent either Gd-EOB-DTPA-enhanced (35 patients, dose 0.025 mmol/kg) or Gd-BOPTA-enhanced (35 patients, dose 0.1 mmol/kg) abdominal MRI. Signal-to-noise ratios (SNR) for the portal vein and the liver as well as portal vein-to-liver contrast-to-noise ratios (CNR) were calculated for three consecutive arterial phases, one portal venous phase and one delayed imaging phase.

Results

The liver SNR showed higher values for the Gd-BOPTA group in the arterial and portal venous phases (statistically significant for the second and third arterial phase), while the liver SNR in the delayed phase was higher for the Gd-EOB-DTPA group. The portal venous SNR as well as the portal vein-to-liver CNR was higher in the Gd-BOPTA group in all imaging phases (statistically significant in all phases except for the first arterial phase).

Conclusion

The enhancement of liver parenchyma and portal vein as well as the portal vein-to-liver contrast in the arterial and portal venous imaging phases were higher for patients receiving Gd-BOPTA compared with Gd-EOB-DTPA at the respective recommended doses. Gd-BOPTA might therefore enable better evaluation of the portal vein.     

弥散加权成像联合普美显磁共振成像在肝癌TACE术后疗效评估中的应用

目的 探讨弥散加权成像(DWI)联合普美显(Gd-EOB-DTPA)MR成像在肝癌TACE后疗效评估中的应用价值.方法 20例确诊肝癌患者于TACE术前、术后行上腹部DWI及Gd-EOB-DTPA动态增强扫描,定性分析TACE术前、术后肝癌活性成分,坏死和复发转移情况.测量TACE术前、术后病灶的表观弥散系数(ADC)值和信号值(signal intensity,SI),并计算术前、术后病灶的动脉期对比增强比(CER)和动脉期的信号比(SIR),对定量参数ADC、CER和SIR值进行配对样本t检验.结果 本组20例患者共检出肝癌病灶45个.TACE术后瘤灶内残存及复发部分在DWI图像上呈高信号,ADC图上信号低于正常肝组织,动脉期可见明显强化,门脉期及平衡期强化减退,肝胆特异期呈明显低信号;瘤灶内坏死部分DWI序列呈低信号,ADC图上为高信号,增强扫描后无强化,肝胆特异期亦呈明显低信号.肝癌病灶术前、术后ADC值分别为(1.52±0.16)×10-3 mm2/s和(1.70±0.28)×10-3 mm2/s,术后肝癌病灶的ADC值普遍升高,两者的差异有统计学意义.肝癌TACE术后的CER动脉期和SIR动脉期值减小,与术前相比,两者的差异有统计学意义.有效组肝癌病灶的术后ADC值大于无效组,而其CER动脉期和SIR动脉期值均小于无效组,两者术后的ADC、CER动脉期和SIR动脉期值的差异均有统计学意义.结论 联合应用DWI和Gd-EOB-DTPA增强MR成像能有效评估肝癌TACE术后病灶存活及坏死情况,检出早期复发、新发灶及转移灶,对制定下一步治疗方案具有重要意义.     

CT引导下经皮乙酸注射联合肝动脉化疗栓塞治疗原发性肝癌

目的 研究经导管肝动脉化疗栓塞(TACE)联合经皮乙酸注射(PAI)治疗原发性肝癌的疗效.方法 选择52例肝癌患者,分为TACE联合PAI治疗组(26例)和单纯TACE组(26例),比较两组治疗效果.结果 联合组与单纯TACE组AFP下降率为78.3%和50.0%,肿瘤体积缩小有效率分别为65.4%(17/26)和38.5%(10/26),1、2年生存率分别为73.1%(19/26)、38.5%(10/20)和57.7%(15/26)、19.2%(5/26),差异有统计学意义(P＜0.05).结论 TACE联合PAI治疗原发性肝癌效果明显优于单纯TACE组.     

Comparison of gadoxetic acid-enhanced dynamic imaging and diffusion-weighted imaging for the preoperative evaluation of colorectal liver metastases

Purpose:

To retrospectively compare the diagnostic accuracy for the detection of colorectal liver metastases between gadoxetic acid‐enhanced MRI (EOB‐MRI) and diffusion‐weighted imaging (DWI) on 3.0 Tesla (T) system, and then to determine whether a combination of the two techniques may improve the diagnostic performance.

Materials and Methods:

Forty‐seven patients underwent MR imaging at 3.0T, including DWI (DWI set) and dynamic and hepatobiliary phase EOB‐MRI (EOB set) for the preoperative evaluation of colorectal liver metastases. All suspicious metastases were confirmed by hepatic surgery. Two blinded readers independently reviewed three different image sets, which consisted of DWI set, EOB set, and combined set. The accuracy was assessed by the area (Az) under the alternative‐free response receiver operating characteristic curve, and the sensitivity and positive predictive value (PPV) were calculated.

Results:

We found a total of 78 confirmed colorectal liver metastases in 42 of 47 patients. Each reader noted higher diagnostic accuracy of combined set of EOB‐MRI and DWI than DWI set and EOB set, without statistical significance. Regardless of the size of colorectal liver metastasis, each reader detected significantly more metastases on combined set than on DWI set, and PPV was significantly higher with DWI set than with EOB set or with combined set for one reader.

Conclusion:

EOB‐MRI was more useful for the detection of colorectal liver metastases, while DWI was more useful for their characterization. The combination of EOB‐MRI and DWI showed significantly higher accuracy and sensitivity for the preoperative detection of small colorectal liver metastases than DWI. J. Magn. Reson. Imaging 2011;. © 2011 Wiley‐Liss, Inc.     

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.     

Differentiation of hypointense nodules on gadoxetic acid-enhanced hepatobiliary-phase MRI using T2 enhanced spin-echo imaging with the time-reversed gradient echo sequence: An initial experience

PurposeTo optimize the flip angle (FA) of the T₂ enhanced spin-echo imaging using the time reversed gradient echo (T2FFE) and evaluate its utility for differentiating hypointensity nodules in the hepatobiliary phase (HBP) of gadoxetic acid-enhanced (Gd-EOB) MRI.Materials and methodsFirst, FA optimization of the T2FFE in the HBP was investigated by comparing signal-to-noise ratio (SNR) among different FAs using phantoms. The liver-to-muscle contrast ratios (CR_Liver-Muscle) and image quality among three FAs (20°, 50° and 80°) were compared using images of 10 patients. Next, the utility of the T2FFE with an optimized FA for differentiating hypointensity nodules in the HBP was assessed by comparing the lesion-to-liver contrast ratio (CR_Lesion-Liver) among cysts, hemangiomas, hepatocellular carcinomas, and metastatic tumors in 32 patients.ResultsSNR increased as FA increased, but leveled off at FAs of 50° and greater. The FA of 50° showed significantly better image quality scores than that of 80° (p < 0.05). After employing an FA of 50°, the CR_Lesion-Liver value indicated that the T2FFE depicted benign lesions as hyperintense and most malignant lesions as hypointense in relation with the liver parenchyma (p < 0.05).ConclusionThe T2FFE in the HBP of Gd-EOB-MRI is useful for differentiating benign and malignant liver lesions.     

Simple Method for evaluating the degree of liver parenchymal enhancement in the hepatobiliary phase of gadoxetic acid‐enhanced magnetic resonance imaging

Purpose:

To establish a simple method to evaluate the degree of liver parenchymal enhancement in the hepatobiliary phase (HP) of gadoxetic acid‐enhanced magnetic resonance imaging (MRI).

Materials and Methods:

Subjects comprised 75 patients with or without chronic liver disease who underwent gadoxetic acid‐enhanced MRI and indocyanine green retention at 15 minutes (ICG‐R15). HP images were used for data analysis. In the quantitative evaluation, liver‐to‐phantom signal intensity (SI) ratio (LPR), liver‐to‐portal vein SI ratio (LPVR), and liver‐to‐kidney SI ratio (LKR) were calculated. In qualitative visual assessment, liver‐to‐portal vein contrast (LPVC) and liver‐to‐kidney contrast (LKC) were assessed using a 5‐point scale (1, hyperintense; 2, slightly hyperintense; 3, isointense; 4, slightly hypointense; 5, hypointense). Statistical evaluations included the Spearman's rank correlation test.

Results:

LPVC and LKC correlated significantly with LPR (ρ = ?0.445, P < 0.001; ρ = ?0.576, P < 0.001, respectively). LPVC and LKC showed significant correlations with LPVR and LKR (ρ = ?0.659, P < 0.001; ρ = ?0.674, P < 0.001, respectively). In addition, LPVC and LKC correlated significantly with ICG‐R15 (ρ = 0.696, P < 0.001; ρ = 0.795, P < 0.001, respectively).

Conclusion:

LPVC and LKC can be used as simple visual indicators to objectively assess the degree of liver parenchymal enhancement on HP of gadoxetic acid‐enhanced MRI. J. Magn. Reson. Imaging 2013;37:1115–1121. © 2012 Wiley Periodicals, Inc.

     

Movement correction of the kidney in dynamic MRI scans using FFT phase difference movement detection.

To measure cortical and medullary MR renograms, regions of interest (ROIs) are placed on the kidney in images acquired using dynamic MRI. Since native kidneys move with breathing, and breath-holding techniques are not feasible, movement correction is necessary. In this contribution we compare three correction methods, based on image matching, phase difference movement detection (PDMD), and cross-correlation, respectively. The PDMD-based method showed the best performance and was able to determine kidney movement in our test series in 68% of the scans with no visible deviation, and in 88% of the scans if a one-pixel deviation is considered acceptable.