High-risk nodules detected in the hepatobiliary phase of Gd-EOB-DTPA-enhanced mr imaging in cirrhosis or chronic hepatitis: Incidence and predictive factors for hypervascular transformation, preliminary results

Liver Lesions at Risk of Transformation into Hepatocellular Carcinoma in Cirrhotic Patients: Hepatobiliary Phase Hypointense Nodules without Arterial Phase Hyperenhancement

Recent technical advances in liver imaging and surveillance for patients at high risk for developing hepatocellular carcinoma (HCC) have led to an increase in the detection of borderline hepatic nodules in the gray area of multistep carcinogenesis, particularly in those that are hypointense at the hepatobiliary phase (HBP) and do not show arterial phase hyperenhancement. Given their potential to transform and advance into hypervascular HCC, these nodules have progressively attracted the interest of the scientific community. To date, however, no shared guidelines have been established for the decision management of these borderline hepatic nodules. It is therefore extremely important to identify features that indicate the malignant potential of these nodules and the likelihood of vascularization. In fact, a more complete knowledge of their history and evolution would allow outlining shared guidelines for their clinical-surgical management, to implement early treatment programs and decide between a preventive curative treatment or a watchful follow-up. This review aims to summarize the current knowledge on hepatic borderline nodules, particularly focusing on those imaging features which are hypothetically correlated with their malignant evolution, and to discuss current guidelines and ongoing management in clinical practice.

Risk Factors for Hypervascularization in Hepatobiliary Phase Hypointense Nodules without Arterial Phase Hyperenhancement: A Systematic Review and Meta-analysis

RATIONALE AND OBJECTIVES

To perform a systematic review and meta-analysis to determine risk factors for hypervascularization in hepatobiliary phase (HBP) hypointense nodules without arterial phase hyperenhancement (APHE) in patients with hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Pubmed and EMBASE databases were searched up to May 7, 2020. Studies which evaluated radiologic and clinical risk factors for hypervascularization in HBP hypointense nodules without APHE were included. Hazard ratios were meta-analytically pooled using random-effects model. Methodological quality of included studies was assessed using Quality in Prognostic Studies (QUIPS) tool.

RESULTS

Sixteen studies with 934 patients were included. HBP hypointense nodules without APHE with baseline size greater than 10 mm, T2 hyperintensity, and restricted diffusion showed risk for hypervascularization with pooled HRs of 2.95 (95% confidence interval [CI], 1.94-4.20), 4.21 (95% CI, 1.15-15.40), 5.83 (95% CI, 1.42-23.95), respectively. Previous HCC history contributed to hypervascularization of the nodules with hazard ratio of 2.06 (95% CI, 1.23-3.44). T1 hyperintensity, intralesional fat, Child-Pugh Class B, sex, alfa-fetoprotein, hepatitis B or C infection were not significant risk factors for hypervascularization (p ≥0.05). Study quality was generally moderate.

CONCLUSION

HBP hypointense nodules without APHE on gadoxetic acid-enhanced MRI with baseline size greater than 10 mm, T2 hyperintensity, restricted diffusion and previous hepatocellular carcinoma history pose higher risk for hypervascularization. Proper patient management in patients with HBP hypointense nodules without APHE on gadoxetic acid-enhanced MRI may need to be tailored according to these risk factors.

The value of hepatobiliary phase in EOB-MRI in predicting hypervascularization outcome of non-hypervascular hypointense lesions in high-risk patients for hepatocellular carcinoma

PURPOSE

To estimate the role of gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid-enhanced MRI (EOB-MRI) in predicting hypervascularization outcome of non-hypervascular hypointense hepatic lesions in high-risk patients for hepatocellular carcinoma (HCC).

METHODS

Under the premise of non-hyperenhance in arterial phase (AP) and hypointensity in hepatobiliary phase (HBP) of EOB-MRI, 29 fresh lesions from 22 patients with chronic viral hepatitis (median (range) age: 69(57-82) years) were prospectively enrolled. During continuously followed-up by EOB-MRI, lesional vascularity in AP, the signal intensity (SI) ratios of lesions-to-parenchyma in HBP images (post-contrast ratio) and adjusted enhancement with reference of unenhanced images (EOB enhancement ratio) were examined.

RESULTS

After 644 (220-2912) days of follow-up, 20 lesions changed into hyperenhancement in AP of EOB-MRI (hypervascularized group), while nine remained non-hyperenhanced (maintained non-hypervascular group). There is no statistical difference of post-contrast ratio at the initial detection. The post-contrast ratios in hypervascularized group were different between each follow-up time point when followed-up ≥ three (P < 0.01) and four (P < 0.05) times, and exposed a linear downward trend with time. Between the hypervascularized and maintained non-hypervascular groups, there were significant differences in the post-contrast ratio at endpoint for three-times' follow-up (P < 0.001); and at the second (P = 0.037), third follow-up time points (P = 0.005), endpoint (P = 0.005) for four-times' follow-up. EOB enhancement ratio showed inter-group difference only at endpoint for three-times' follow-up (P = 0.008).

CONCLUSION

For non-hypervascular, HBP hypointense hepatic lesions, decreasing trend of SI in HBP may early predict unfavorable hypervascularized outcome.

Feasibility of high-resolution magnetic resonance imaging of the liver using deep learning reconstruction based on the deep learning denoising technique

PURPOSE

To evaluate the feasibility of High-resolution (HR) magnetic resonance imaging (MRI) of the liver using deep learning reconstruction (DLR) based on a deep learning denoising technique compared with standard-resolution (SR) imaging.

MATERIALS AND METHODS

This retrospective study included patients who underwent abdominal MRI including both HR imaging using DLR and SR imaging between April 1 and August 31, 2019. DLR was applied to all HR images using 12 different strength levels of noise reduction to determine the optimal denoised level for HR images. The mean signal-to-noise ratio (SNR) was then compared between the original HR images without DLR and the optimal denoised HR images with DLR and SR images. The mean image noise, sharpness and overall image quality were also compared. Statistical analyses were performed with the Friedman and Dunn-Bonferroni post-hoc test.

RESULTS

In total, 49 patients were analyzed (median age, 71 years; 25 women). In quantitative analysis, the mean SNRs on the original HR images without DLR were significantly lower than those on the SR images in all sequences (p < 0.01). Conversely, the mean SNRs on optimal denoised HR images were significantly higher than those on the SR images in all sequences (p < 0.01). In the qualitative analysis, the mean scores for the image noise and overall image quality were significantly higher on optimal denoised HR images than on the SR images in all sequences (p < 0.01) except for the mean image noise score in in-phase (IP) images.

CONCLUSIONS

The use of a deep learning-based noise reduction technique substantially and successfully improved the SNR and image quality in HR imaging of the liver. Denoised HR imaging using the DLR technique appears feasible for use in liver MR examinations compared with SR imaging.

MRI-based risk factors of hepatocellular carcinoma in patients with chronic liver disease: A prospective observational study

BACKGROUND

MR-based metrics, including hepatobiliary phase (HBP) hypointense nodules without arterial phase hyperenhancement (APHE), and liver stiffness as measured by MR elastography are useful markers to stratify the risk of hepatocellular carcinoma (HCC) development in chronic liver disease patients. However, prospective studies are needed to clarify their utility.

PURPOSE

To perform a risk analysis of HCC development in chronic liver disease patients, with a focus on MR-based biomarkers.

STUDY TYPE

Prospective.

SUBJECTS

Consecutive 110 cirrhotic patients (61 males, 49 females) without a history of HCC who matched the inclusion criteria.

FIELD STRENGTH/SEQUENCE

3T/3D gradient-echo T₁ -weighted images and MR elastography.

ASSESSMENT

Patients underwent MRI for HCC screening and attended follow-up appointments every 3 months. The primary endpoint was the development of hypervascular HCC. Patients were classified according to the presence of an HBP hypointense nodule without APHE (if present in the liver, the patient was classified in nonclean liver group; if absent, clean liver group), and stiffness value on MR elastography (soft liver, <4.0 kPa; stiff liver, ≥4.0 kPa) at the initial examination.

STATISTICAL TESTS

Risk factors were identified in univariate and multivariate Cox regression models. Incidence rates of HCC development were evaluated using the Kaplan-Meier method.

RESULTS

Patients were classified into clean-liver (n = 76) and nonclean-liver groups (n = 34), and into soft-liver (n = 53) and stiff-liver groups (n = 45). During the follow-up period (median, 21.0 months), 16 patients developed hypervascular HCC. Patients in the nonclean-liver group showed a higher incidence of hypervascular HCC than those in the clean-liver group (3-year HCC incidence rates: 50.4% and 5.7%, respectively; P < 0.05). A nonclean liver was independently associated with hypervascular HCC development (hazard ratio, 18.75; 95% confidence interval, 4.83-128.63; P < 0.0001), but stiff liver was not (1.91; 0.66-6.23; P = 0.23).

DATA CONCLUSION

An HBP hypointense nodule without APHE observed on a gadoxetic acid-enhanced MR image is a strong indicator of subsequent development of hypervascular HCC in patients with chronic liver disease.

LEVEL OF EVIDENCE

2 Technical Efficacy Stage: 5 J. Magn. Reson. Imaging 2020;51:389-396.

Staging of liver fibrosis using Gd-EOB-DTPA and Gd-BOPTA enhanced magnetic resonance imaging

The severity of cirrhosis is closely related to its clinical treatment. Therefore, it is important to stage liver fibrosis accurately. Although liver biopsy can accurately stage the degree of cirrhosis, it has certain limitations in clinical application because of its invasive nature. Magnetic resonance imaging (MRI) has been used in the diagnosis of liver diseases. In recent years, two new contrast agents, gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) and gadobenate dimeglumine (Gd-BOPTA), have been successfully used for noninvasive liver imaging. They can be used for liver fibrosis staging and assessment of liver function. Cirrhotic patients with different liver function levels have a statistical difference in the liver parenchyma enhancement after giving contrast agents. This article briefly summarizes the progress of Gd-EOB-DTPA and Gd-BOPTA enhanced MRI in staging liver fibrosis stage.

Progression of Hepatic Hypovascular Nodules with Hypointensity in the Hepatobiliary Phase of Gd-EOB-DTPA-enhanced MRI in Hepatocellular Carcinoma Cases

Objective We investigated the possible factors for predicting the future progression to hepatocellular carcinoma (HCC) from hypovascular nodules detected in the hepatobiliary phase of gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging (Gd-EOB-DTPA-MRI). Methods A total of 91 hypovascular nodules detected by Gd-EOB-DTPA-MRI in 28 patients without any past history of treatment for HCC were retrospectively examined. The nodules were categorized into those with and without HCC progression, then comparisons were made to identify any factors possibly related to a progression to HCC in each case. In addition, we performed a receiver operating characteristics (ROC) analysis to determine the cut-off value for the initial nodule size for predicting HCC progression within 12 months. Results The observation period of the 28 patients was 1,172.6±95.6 (mean±standard error) days. The number of hypovascular nodules that changed to hypervascular ones was 15 (16.5%), and the cumulative incidence of hypervascular transformation was 7.1% at 12 months and 12.7% at 24 months. Of all 91 hypovascular nodules, 33 in 18 patients were diagnosed as HCC based on hypervascular transformation and/or size enlargement, while the remaining 58 did not progress to HCC. There was no significant difference regarding the background characteristics between the HCC progressed and non-progressed groups according to a multivariate analysis, or between the patients who had nodules that progressed to HCC and those with nodules that did not progress to HCC. Regarding HCC progression at 12 months, the area under the ROC (AUROC) had a level of 0.745 and showed that an initial nodule cut-off size of 9.5 mm (sensitivity, 57.9%; specificity, 87.3%) was predictive. Conclusion In patients without a past HCC treatment history, it is difficult to determine whether hypovascular nodules have a high risk of progression to HCC based on background factors alone.

Superparamagnetic iron oxide-enhanced magnetic resonance imaging is useful in predicting malignant potential of vascular transformation of hypointense hypovascular nodules on gadoxetic acid-enhanced magnetic resonance imaging

AIM

To examine whether superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance imaging (MRI) can be used to assess the malignant potential of hepatic hypovascular nodules showing hypointensity during the hepatobiliary phase (HBP) on gadoxetic acid (Gd-EOB-DTPA)-enhanced MRI.

METHODS

The study included 42 patients with chronic liver disease who had small hypovascular nodules (5-15 mm) showing hypointensity during the HBP on Gd-EOB-DTPA-enhanced MRI. The SPIO-enhanced T2-weighted MRI analyzed whether the signal intensity of each nodule was high. Nodules were prospectively followed up until hypervascularization by periodic Gd-EOB-DTPA-enhanced MRI. Initial MRI findings and clinical variables were used to analyze predictive factors for hypervascularization.

RESULTS

We analyzed 77 nodules, of which 19 (25%) showed hypervascularization during the observation period. The cumulative rates for hypervascularization were 11% and 22% at 1 and 2 years, respectively. Hyperintensity was observed in 12 nodules (16%) on SPIO-enhanced T2-weighted MRI; among these, 7 (58%) showed hypervascularization, whereas 12 (18%) of the remaining 65 nodules without hyperintensity showed hypervascularization (P = 0.007). A Cox model revealed that independent predictors of hypervascularization included hyperintense nodules on SPIO-enhanced MRI (P < 0.001). The cumulative rates for hypervascularization in hyperintense nodules on SPIO-enhanced MRI were 52% at 1 year, whereas these rates were 3% for non-hyperintense nodules.

CONCLUSION

Superparamagnetic iron oxide-enhanced MRI is useful for predicting the malignant potential of vascular transformation of hypovascular nodules with hypointensity observed in the HBP on Gd-EOB-DTPA-enhanced MRI.

Rate of local tumor progression following radiofrequency ablation of pathologically early hepatocellular carcinoma

AIM

To evaluate whether pathologically early hepatocellular carcinoma (HCC) exhibited local tumor progression after radiofrequency ablation (RFA) less often than typical HCC.

METHODS

Fifty pathologically early HCCs [tumor diameter (mm): mean, 15.8; range, 10-23; follow-up days after RFA: median, 1213; range, 216-2137] and 187 typical HCCs [tumor diameter (mm): mean, 15.6; range, 6-30; follow-up days after RFA: median, 1116; range, 190-2328] were enrolled in this retrospective study. The presence of stromal invasion (namely, tumor cell invasion into the intratumoral portal tracts) was considered to be the most important pathologic finding for the diagnosis of early HCCs. Typical HCC was defined as the presence of a hyper-vascular lesion accompanied by delayed washout using contrast-enhanced computed tomography or contrast-enhanced magnetic resonance imaging. Follow-up examinations were performed at 3-mo intervals to monitor for signs of local tumor progression. The local tumor progression rates of pathologically early HCCs and typical HCCs were then determined using the Kaplan-Meier method.

RESULTS

During the follow-up period for the 50 pathologically early HCCs, 49 (98%) of the nodules did not exhibit local tumor progression. However, 1 nodule (2%) was associated with a local tumor progression found 636 d after RFA. For the 187 typical HCCs, 46 (24.6%) of the nodules exhibited local recurrence after RFA. The follow-up period until the local tumor progression of typical HCC was a median of 605 d, ranging from 181 to 1741 d. Among the cases with typical HCCs, local tumor progression had occurred in 7.0% (7/187), 16.0% (30/187), 21.9% (41/187) and 24.6% (46/187) of the cases at 1, 2, 3 and 4 years, respectively. Pathologically early HCC was statistically associated with a lower rate of local tumor progression, compared with typical HCC, when evaluated using a log-rank test (P = 0.002).

CONCLUSION

The rate of local tumor progression for pathologically early HCCs after RFA was significantly lower than that for typical HCCs.

Assessment of clinical and magnetic resonance imaging features of de novo hypervascular hepatocellular carcinoma using gadoxetic acid-enhanced magnetic resonance imaging

AIM

To clarify the clinical and magnetic resonance imaging (MRI) features of de novo hypervascular hepatocellular carcinoma (HCC) using serial gadoxetic acid-enhanced MRI.

METHODS

The institutional review board approved this retrospective study. After review of 1007 MRI examinations in 240 patients with chronic liver disease, 17 newly developed hypervascular HCCs in 16 patients detected by follow-up from initial MRI examination without hepatocellular nodules were evaluated. The clinical and MRI findings such as previous treatment history for HCC, period to hypervascular HCC onset, presence or absence of hypovascular hypointense nodules on hepatobiliary phase before hypervascularization, and intralesional fat component were recorded or evaluated. Statistical evaluations included Fisher's exact test, χ² -test, and Mann-Whitney U-test.

RESULTS

In 17 HCCs, 12 (71%) were de novo hypervascular HCC without showing hypovascular hypointense nodule on hepatobiliary phase before hypervascularization (de novo group) and 5 (29%) were hypervascularized HCC developed during multistep hepatocarcinogenesis (multistep group). The incidence of previous treatment history for HCC in the de novo group (91%) was significantly higher than that in the multistep group (20%) (P = 0.013). The duration to hypervascular HCC onset from initial examination was shorter in the de novo group (mean, 291 days) than in the multistep group (mean, 509 days) (P = 0.035). The incidence of fat-containing lesion in the de novo group (0%) was lower than that in the multistep group (40%) (P = 0.074).

CONCLUSION

De novo hypervascular HCC is characterized by rapid growth, patients with previous treatment history for HCC, and lack of intralesional fat, compared to hypervascular HCC with multistep progression.

Recent Advances in the Imaging Diagnosis of Hepatocellular Carcinoma: Value of Gadoxetic Acid-Enhanced MRI

Magnetic resonance imaging (MRI) using gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DPTA), or gadoxetic acid for short, is a hepatocyte-specific contrast agent which is now increasingly used for the detection and characterization of focal hepatic lesions, particularly in patients at high-risk of developing hepatocellular carcinomas (HCC). In fact, several recent guidelines now recognize gadoxetic acid-enhanced MRI (Gd-EOB-MRI) as the primary diagnostic imaging modality for the noninvasive diagnosis of HCC, although it must be noted that several major guidelines still include only extracellular contrast media-enhanced computed tomography and MRI. The primary merits of Gd-EOB-MRI lie in the fact that it can provide not only dynamic imaging, but also hepatobiliary phase (HBP) imaging which can lead to high lesion-to-liver contrast and give additional information regarding hepatocyte uptake via organic anion transporting polypeptides. This, in turn, allows higher sensitivity in detecting small HCCs and helps provide additional information regarding the multistep process of hepatocarcinogenesis. Indeed, many recent studies have investigated the diagnostic value of Gd-EOB-MRI for early HCCs as well as its role as a potential imaging biomarker in predicting outcome. We herein review the recent advances in the imaging diagnosis of HCCs focusing on the applications of Gd-EOB-MRI and the challenging issues that remain.

Kupffer phase image of Sonazoid-enhanced US is useful in predicting a hypervascularization of non-hypervascular hypointense hepatic lesions detected on Gd-EOB-DTPA-enhanced MRI: a multicenter retrospective study

BACKGROUND

It remains unknown whether Kupffer-phase images in Sonazoid-enhanced ultrasonography (US) can be used to predict hypervascularization of borderline lesions. Therefore, we aimed to clarify whether Kupffer-phase images in Sonazoid-enhanced ultrasonography can predict subsequent hypervascularization in hypovascular borderline lesions detected on hepatobiliary-phase gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging.

METHODS

From January 2008 to March 2012, 616 low-intensity hypovascular nodules were detected in hepatobiliary-phase images of Gd-EOB-DTPA-enhanced MRI at nine institutions. Among these, 167 nodules, which were confirmed as hypovascular by Gd-EOB-DTPA-enhanced MRI and Sonazoid-enhanced US, were evaluated in this study. Potential hypervascularization factors were selected based on their clinical significance and the results of previous reports. The Kaplan-Meier model and log-rank test were used for univariate analysis and the Cox regression model was used for multivariate analysis.

RESULTS

The cumulative incidence of hypervascularization of borderline lesions was 18, 37, and 43 % at 1, 2, and 3 years, respectively. Univariate analyses showed that tumor size (p = 0.0012) and hypoperfusion on Kupffer-phase images in Sonazoid-enhanced US (p = 0.004) were associated with hypervascularization of the tumor. Multivariate analysis showed that tumor size [HR: 1.086, 95 % confidence interval = 1.027-1.148, p = 0.004] and hypo perfusion on Kupffer-phase images [HR: 3.684, 95 % confidence interval = 1.798-7.546, p = 0.0004] were significantly different.

CONCLUSIONS

Kupffer-phase images in Sonazoid-enhanced US and tumor diameter can predict hypervascularization of hypointense borderline lesions detected on hepatobiliary-phase Gd-EOB-DTPA-enhanced MRI.

Recent advances in the imaging of hepatocellular carcinoma

The role of imaging is crucial for the surveillance, diagnosis, staging and treatment monitoring of hepatocellular carcinoma (HCC). Over the past few years, considerable technical advances were made in imaging of HCCs. New imaging technology, however, has introduced new challenges in our clinical practice. In this article, the current status of clinical imaging techniques for HCC is addressed. The diagnostic performance of imaging techniques in the context of recent clinical guidelines is also presented.

Clinical value of gadoxetic acid-enhanced magnetic resonance imaging in surgery for hepatocellular carcinoma - with a special emphasis on early hepatocellular carcinoma

Gadoxetic acid- or gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging (EOB-MRI) achieves excellent lesion detection and characterization for both hypervascular hepatocellular carcinoma (HCC) in arterial phase imaging and hypovascular early HCC (small well-differentiated HCC of the vaguely nodular type) in hepatobiliary phase imaging, and has become an indispensable imaging modality in the treatment of HCC. Early HCCs have been detected more frequently since the introduction of EOB-MRI into daily clinical practice. Early HCC is known to progress to conventional hypervascular HCC, and many risk factors have been identified for the hypervascularization of early HCC including the diameter of the tumor, presence of fat, and imaging findings of EOB-MRI. The rate of the development of hypervascular HCC was previously reported to be high in patients with chronic liver disease and early HCC. The presence of early HCC is regarded as a predictor for the recurrence of HCC following hepatic resection. On the other hand, although early HCC itself is currently not regarded as a target lesion for hepatic resection, early HCC at high risk of hypervascularity needs to be treated by local ablation therapy. If concomitant early HCC with progressed HCC is at high risk of hypervascularization and the functional liver reserve of a patient is sufficient, its simultaneous treatment at the time of hepatic resection for progressed HCC is recommended. Further studies on larger numbers of patients are needed before this strategy is adopted.

Hypovascular hypointense nodules on hepatobiliary phase without T2 hyperintensity on gadoxetic acid-enhanced MR images in patients with chronic liver disease: long-term outcomes and risk factors for hypervascular transformation

PURPOSE

To evaluate the long-term outcomes and imaging features associated with hypervascularization of hypovascular nodules that show T2 iso-/hypointensity and hypointensity on hepatobiliary phase (HBP) of gadoxetic acid-enhanced magnetic resonance (MR) images in patients with chronic liver disease.

MATERIALS AND METHODS

Sixty patients and 114 nodules, which were hypovascular and iso-/hypointense on T2-weighted images and hypointense on HBP of gadoxetic acid-enhanced MRI, were included. We evaluated the effect of baseline clinical features, baseline MR features and growth rate on subsequent hypervascularization.

RESULTS

Twenty-seven nodules in 21 patients transformed to hypervascular hepatocellular carcinoma (HCC). Using multivariate Cox analysis, T1 hyperintensity (hazard ratio [HR] = 2.69, P = 0.021), previous history of HCC (HR = 2.64, P = 0.021), and initial nodule size (HR = 1.09, P = 0.046) were identified to be associated with hypervascularization. The growth rate of nodules was a more powerful determinant of subsequent hypervascularization than baseline clinical and MR features. At long-term follow-up after >3 years, only one nodule with T1 isointensity showed hypervascularization.

CONCLUSION

Careful follow-up or diagnostic procedures, such as biopsy, should be considered for up to 3 years after detection of hypointense nodules on HBP with T1 hyperintensity or a higher growth rate.

KEY POINTS

• T1 hyperintensity is a baseline MR predictive factor for subsequent hypervascularization. • A higher growth rate is a more powerful determinant of subsequent hypervascularization. • Management of patients with these predictive factors requires more attention.

Nonhypervascular Hypointense Nodules at Gadoxetic Acid-enhanced MR Imaging in Chronic Liver Disease: Diffusion-weighted Imaging for Characterization

PURPOSE

To compare the diagnostic performance of magnetic resonance (MR) imaging features, including those on diffusion-weighted (DW) and T2-weighted images, in differentiating between hypovascular hepatocellular carcinoma (HCC) and dysplastic nodules seen as hypointense nodules at hepatobiliary phase gadoxetic acid-enhanced MR imaging.

MATERIALS AND METHODS

The institutional review board approved this retrospective study and waived the need to obtain informed patient consent. There were 53 patients (39 men and 14 women; age range, 32-75 years) with histologically proven hypovascular HCCs (n = 25) and/or dysplastic nodules (n = 31) who underwent gadoxetic acid-enhanced MR imaging at 3.0-T between March 2011 and January 2014. Images of 25 HCCs and 31 dysplastic nodules were analyzed for nodule size; signal intensity on T1- and T2-weighted, portal venous phase, and DW (b value = 800 sec/mm(2)) images; and intralesional fat. Correlations between the hyperintensity grade of lesions and the liver-to-lesion signal intensity ratio at T2-weighted and DW imaging were determined by means of analysis with generalized estimating equations.

RESULTS

Hyperintensity at T2-weighted and DW imaging and hypointensity in the portal venous phase were significant features for differentiating hypovascular HCCs from dysplastic nodules (P < .05). The sensitivity of DW imaging tended to be higher than that of T2-weighted imaging (72.0% [18 of 25] vs 40.0% [10 of 25]; P = .008 for grade 2 and 3 hyperintensity). Use of the parameter of hyperintensity similar to or slightly lower than the signal intensity of the spleen on DW images (b value = 800 sec/mm(2)) yielded a specificity of 100% (31 of 31) for the diagnosis of hypovascular HCC by differentiating it from a dysplastic nodule.

CONCLUSION

Hyperintensity at DW imaging could be a useful MR imaging feature for differentiating hypovascular HCCs from dysplastic nodules seen as hypointense nodules at gadoxetic acid-enhanced MR imaging.

Focal lesions in the cirrhotic liver: their pivotal role in gadoxetic acid-enhanced MRI and recognition by the Western guidelines

Hepatocellular carcinoma (HCC) is a major health concern, and early HCC diagnosis is a primary radiological concern. The goal of imaging liver cirrhosis is the early identification of high-grade dysplastic nodules/early HCC since their treatment is associated with a higher chance of radical cure and lower recurrence rates. The newly introduced MRI contrast agent gadoxetic acid (gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid, Gd-EOB-DTPA) has enabled the concurrent assessment of tumor vascularity and hepatocyte-specific contrast enhancement during the hepatobiliary phase (HBP), which can help to detect and characterize smaller HCCs and their precursors. HBP-EOB-MRI identifies hypovascular HCC nodules that are difficult to detect using ultrasonography or computed tomography, which do not show the diagnostic HCC hallmarks of arterial washin and portal/delayed washout. During the HBP, typical HCC and early HCC appear hypointense on EOB-MRI, whereas low-grade dysplastic or regenerative nodules appear as iso- or hyperintense lesions. The diagnostic accuracy of EOB-MRI for the diagnosis of early HCC is approximately 95-100%. One third of hypovascular hypointense nodules in HBP become hypervascular 'progressed' HCC, with a 1- and 3-year cumulative incidence of 25 and 41%, respectively. Therefore, these hypovascular nodules should be strictly followed up or definitely treated as typical HCC. Due to this capability of identifying the precursors and biological behavior of HCC, EOB-MRI has rapidly become a key imaging tool for the diagnosis of HCC and its precursors, despite the scarce MRI availability throughout Europe. With increasing experience, EOB-MRI may eventually be established as the diagnostic imaging modality of choice in this setting. Full recognition by the Western EASL-AASLD guidelines is expected.

Hepatobiliary MR contrast agents in hypovascular hepatocellular carcinoma

Hepatocellular carcinoma (HCC) develops via multistep hepatocarcinogenesis, during which hypovascular/early HCC precedes the typical hypervascular HCC. The hypovascular HCC lacks the typical hallmark imaging features of HCC, such as late arterial phase enhancement and portal venous washout, limiting early detection using conventional extracellular contrast agents for dynamic magnetic resonance imaging (MRI) or computed tomography (CT) imaging. In recent years, gadolinium-based contrast agents with hepatobiliary uptake have garnered interest from radiologists and hepatologists due to their potential for improved detection of HCC during hepatobiliary phase MRI. Lesions with reduced or absent hepatocyte function appear hypointense in the hepatobiliary phase of gadoxetic acid-enhanced MRI. This behavior can be exploited for earlier detection of hypovascular HCC. This review describes the general characteristics and advantages of gadoxetic acid for the diagnosis of HCC with a particular focus on hypovascular/early HCC.

Prognosis of small hepatocellular nodules detected only at the hepatobiliary phase of Gd-EOB-DTPA-enhanced MR imaging as hypointensity in cirrhosis or chronic hepatitis

PURPOSE

To evaluate the prognosis of "strict" high-risk nodules (small hepatocellular nodules detected only in the hepatobiliary phase of initial Gd-EOB-DTPA-enhanced MR examination) in patients with cirrhosis or chronic hepatitis.

METHODS AND MATERIALS

The study included thirty-three patients with 60 "strict" high-risk nodules showing hypointensity at the hepatobiliary phase that was undetectable at the vascular phase and other conventional sequences of initial Gd-EOB-DTPA-enhanced MR imaging. These nodules were observed on follow-up MR examinations until hypervascularity was detected. The potential predictive factors for hypervascular transformation were compared between two groups (group A showing hypervascular transformation, group B not showing hypervascularization).

RESULTS

Ten (16.7 %) of 60 "strict" high-risk nodules showed hypervascular transformation during follow-up periods (group A). The growth rates of the nodules in group A (6.3 ± 4.5 mm/year) were significantly higher than those in group B (3.4 ± 7.2 mm/year) (p = 0.003). Additionally, the median observation period in group A (177.5 ± 189.5 day) was significantly shorter than in group B (419 ± 372.2 day) (p = 0.045). The other predictive factors were not significantly correlated with hypervascularization.

CONCLUSIONS

Subsets of "strict" high-risk nodules showed hypervascular transformation during follow-up periods in association with increased growth rates, indicating that nodule growth rate is an important predictive factor for hypervascularization.

KEY POINTS

• "Strict" high-risk nodules are defined as hepatocellular nodules detected only in the hepatobiliary-phase. • Subsets of "strict" high-risk nodules showed hypervascular transformation during follow-up periods. • Increased growth rate is an important predictive factor for hypervascular transformation. • Management of patients with "strict" high-risk nodules becomes more appropriate.

Prognostic performance of preoperative gadoxetic acid-enhanced MRI in resectable hepatocellular carcinoma

PURPOSE

To assess the impact of preoperative evaluation by gadoxetic acid-enhanced magnetic resonance imaging (MRI) on early recurrence outcomes after hepatocellular carcinoma (HCC) resection.

MATERIALS AND METHODS

The retrospective study included two groups of Child-Pugh class A patients who underwent curative liver resection for a single HCC; in one group the HCC was identified by dynamic computed tomography (CT) and gadoxetic acid-enhanced MRI (n = 174; MRI group); in the other by dynamic CT only (n = 416; non-MRI group). We compared the two groups with respect to recurrence-free survival after propensity score matching (162 pairs).

RESULTS

In the matched cohorts, disease-free survival rates for overall and intrahepatic recurrence were 92.6% and 91.9% at 1 year and 78.3% and 79.4% at 2 years, respectively, for the MRI group versus 82.7% and 82.7% at 1 year and 67.2% and 70.4% at 2 years, respectively, for the non-MRI group (P < 0.05). Multivariate Cox analyses revealed that the MRI group was independently superior to the non-MRI group in terms of risk of overall and intrahepatic recurrence at 1 and 2 years in the pooled cohort (P < 0.05).

CONCLUSION

Gadoxetic acid-enhanced MRI evaluation is more useful than dynamic CT for identifying good surgical candidates at low risk of early recurrence following hepatic resection for HCC. J. Magn. Reson. Imaging 2015;41:1115-1123. © 2014 Wiley Periodicals, Inc.

Magnetic resonance imaging in cirrhosis: what's new?

Cirrhosis is the main risk factor for the development of hepatocellular carcinoma (HCC). The major causative factors of cirrhosis in the United States and Europe are chronic hepatitis C infection and excessive alcohol consumption with nonalcoholic steatohepatitis emerging as another important risk factor. Magnetic resonance imaging is the most sensitive imaging technique for the diagnosis of HCC, and the sensitivity can be further improved with the use of diffusion-weighted imaging and hepatocyte-specific contrast agents. The combination of arterial phase hyperenhancement, venous or delayed phase hypointensity "washout feature," and capsular enhancement are features highly specific for HCC with reported specificities of 96% and higher. When these features are present in a mass in the cirrhotic liver, confirmatory biopsy to establish the diagnosis of HCC is not necessary. Other tumors, such as cholangiocarcinoma, sometimes occur in the cirrhotic at a much lower rate than HCC and can mimic HCC, as do other benign lesions such as perfusion abnormalities. In this article, we discuss the imaging features of cirrhosis and HCC, the role of magnetic resonance imaging in the diagnosis of HCC and other benign and malignant lesions that occur in the cirrhotic liver, and the issue of nonspecific arterially hyperenhancing nodules often seen in cirrhosis.

Preoperative gadoxetic Acid-enhanced MRI and simultaneous treatment of early hepatocellular carcinoma prolonged recurrence-free survival of progressed hepatocellular carcinoma patients after hepatic resection

Background/Purpose. The purpose of this study was to clarify whether preoperative gadoxetic acid-enhanced magnetic resonance imaging (EOB-MRI) and simultaneous treatment of suspected early hepatocellular carcinoma (eHCC) at the time of resection for progressed HCC affected patient prognosis following hepatic resection. Methods. A total of 147 consecutive patients who underwent their first curative hepatic resection for progressed HCC were enrolled. Of these, 77 patients underwent EOB-MRI (EOB-MRI (+)) before hepatic resection and the remaining 70 patients did not (EOB-MRI (-)). Suspected eHCCs detected by preoperative imaging were resected or ablated at the time of resection for progressed HCC. Results. The number of patients who underwent treatment for eHCCs was significantly higher in the EOB-MRI (+) than in the EOB-MRI (-) (17 versus 6; P = 0.04). Recurrence-free survival (1-, 3-, and 5-year; 81.4, 62.6, 48.7% versus 82.1, 41.5, 25.5%, resp., P < 0.01), but not overall survival (1-, 3-, and 5-year; 98.7, 90.7, 80.8% versus 97.0, 86.3, 72.4%, resp., P = 0.38), was significantly better in the EOB-MRI (+). Univariate and multivariate analyses showed that preoperative EOB-MRI was one of the independent factors significantly correlated with better recurrence-free survival. Conclusions. Preoperative EOB-MRI and simultaneous treatment of eHCC prolonged recurrence-free survival after hepatic resection.

Insight into hepatocellular carcinoma biology with gadoxetate disodium-enhanced MRI

The current algorithm for the imaging diagnosis of hepatocellular carcinoma accurately detects large, progressed tumors displaying the classical imaging features of arterial hyperenhancement with 'washout' and/or 'capsule' appearance. Liver MRI with the relatively newer hepatobiliary agent, gadoxetate disodium, provides information on hepatocellular function in addition to vascularity, facilitates detection of small progressed tumors, as well as early/vaguely nodular tumors, and shows promise for characterizing hepatocellular carcinoma biology. Prediction of tumor grade, presence of biliary and stem cell markers, microvascular invasion, future hypervascularization and post-treatment recurrence have all been studied with gadoxetate disodium-enhanced MRI with encouraging results. Incorporation of gadoxetate disodium-enhanced MRI into standard diagnostic and management algorithms will likely unfold in the future.

Hypovascular hepatic nodules showing hypointense on the hepatobiliary-phase image of Gd-EOB-DTPA-enhanced MRI to develop a hypervascular hepatocellular carcinoma: a nationwide retrospective study on their natural course and risk factors

OBJECTIVE

We aimed to investigate the natural outcome of nonhypervascular lesions detected in the hepatobiliary phase of gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MRI by performing a longitudinal study retrospectively enrolled in a nationwide manner.

METHODS

Between February 2008 and March 2011, 224 patients with 504 nodules that were diagnosed as nonhypervascular by imaging were recruited from institutions that participated in the present study. We examined the natural outcome of nonhypervascular lesions and evaluated the risk factors.

RESULTS

Of the 504 nodules, 173 (34.3%) showed hypervascular transformation. The overall cumulative incidence of hypervascular transformation was 14.9% at 12 months and 45.8% at 24 months. Multivariate analysis using the Cox regression model revealed previous treatment history for hepatocellular carcinoma (HCC; relative risk = 1.498; p = 0.036, 95% CI 1.03-2.19) and hyperintensity on T2-weighted images (relative risk = 1.724; p = 0.015, 95% CI 1.11-2.67) were identified as independent factors for hypervascular transformation.

CONCLUSIONS

Patients who have a previous treatment history for HCC and with hypointense nodules showing hyperintensity on T2-weighted images need careful follow-up because of the high incidence of hypervascular transformation.