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

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.

Up-to-Date Role of Liver Imaging Reporting and Data System in Hepatocellular Carcinoma

This article overviews Liver Imaging Reporting and Data System (LI-RADS), a system that standardizes techniques, interpretation and reporting of imaging studies done for hepatocellular carcinoma surveillance, diagnosis, and locoregional treatment response assessment. LI-RADS includes 4 algorithms, each of which defines ordinal categories reflecting probability of the assessed outcome. The categories, in turn, guide patient management. The LI-RADS diagnostic algorithms provide diagnostic criteria for the entire spectrum of lesions found in at-risk patients. In addition, the use of LI-RADS in clinical care improves clarity of communication between radiologists and clinicians and may improve the performance of inexperienced users to the levels of expert liver imagers.

Hepatobiliary-Phase Hypointense Nodules Without Arterial-Phase Hyperenhancement: Developing a Risk Stratification for Hypervascular Transformation Based on a Real-World Observational Cohort Study

PURPOSE

To develop a risk stratification based on MRI features to predict hypervascular transformation for hepatobiliary-phase (HBP) hypointense nodules without arterial-phase hyperenhancement (APHE).

MATERIALS AND METHODS

This retrospective observational cohort study included 55 HBP hypointense nodules without APHE in 35 patients with chronic liver disease, cirrhosis, or current hepatocellular carcinoma (HCC) who underwent gadoxetic acid-enhanced MRI. The hypervascular transformation during the follow-up MRI(s) was the primary endpoint analyzed for the nodules. Univariable and multivariable Cox proportional hazard regression analyses were performed to identify risk features predicting transformation and assess their predictive value.

RESULTS

Among the 55 nodules, 27 developed hypervascular transformation, while 28 did not. Diffusion-weighted imaging (DWI) hyperintensity (hazard ratio [HR], 4.98; 95% confidence interval [CI]: 1.60, 15.54; p = 0.006) and portal venous phase (PVP) hypointensity (HR, 4.08; 95% CI: 1.43, 11.64; p = 0.009) were associated with hypervascular transformation. DWI hyperintensity and PVP hypointensity had 44.4% (95% CI: 26.0%, 64.4%) and 81.9% (95% CI: 61.3%, 93.0%) sensitivity, while their specificity was 78.2% (95% CI: 64.6%, 87.8%) and 67.9 (95% CI: 47.6%, 83.4%), respectively. The specificity of the combination of two features was 100% (95% CI: 85.0%, 100%). The hypervascular transformation rates for nodules with both, either and neither of the risk MRI findings were 100% (10/10), 60.9% (14/23), and 13.6% (3/22), respectively; the median intervals for transformation were 312 (range: 73-838), 409 (range: 50-1643) and 555 (range: 423-968) days, respectively.

CONCLUSION

The combination of DWI hyperintensity and PVP hypointensity may be used as a high-risk indicator for the hypervascular transformation of HBP hypointense nodules without APHE; nodules without either feature may be treated as low-risk nodules and could adopt an extended interval follow-up schedule.

Long-term evolution of LR-2, LR-3 and LR-4 observations in HBV-related cirrhosis based on LI-RADS v2018 using gadoxetic acid-enhanced MRI

PURPOSE

To investigate the long-term evolution of LR-2, LR-3 and LR-4 observations in patients with hepatitis B virus (HBV)-related cirrhosis based on LI-RADS v2018 and identify predictors of progression to a malignant category on serial gadoxetic acid-enhanced magnetic resonance imaging (Gd-EOB-MRI).

METHODS

This retrospective study included 179 cirrhosis patients with untreated indeterminate observations who underwent Gd-EOB-MRI exams at baseline and during the follow-up period between June 2016 and December 2021. Two radiologists independently assessed the major features, ancillary features, and LI-RADS category of each observation at baseline and follow-up. In cases of disagreement, a third radiologist was consulted for consensus. Cumulative incidences for progression to a malignant category (LR-5 or LR-M) and to LR-4 or higher were analyzed for each index category using Kaplan‒Meier methods and compared using log-rank tests. The risk factors for malignant progression were evaluated using a Cox proportional hazard model.

RESULTS

A total of 213 observations, including 74 (34.7%) LR-2, 95 (44.6%) LR-3, and 44 (20.7%) LR-4, were evaluated. The overall cumulative incidence of progression to a malignant category was significantly higher for LR-4 observations than for LR-3 or LR-2 observations (each P < 0.001), and significantly higher for LR-3 observations than for LR-2 observations (P < 0.001); at 3-, 6-, and 12-month follow-ups, the cumulative incidence of progression to a malignant category was 11.4%, 29.5%, and 39.3% for LR-4 observations, 0.0%, 8.5%, and 19.6% for LR-3 observations, and 0.0%, 0.0%, and 0.0% for LR-2 observations, respectively. The cumulative incidence of progression to LR-4 or higher was higher for LR-3 observations than for LR-2 observations (P < 0.001); at 3-, 6-, and 12-month follow-ups, the cumulative incidence of progression to LR-4 or higher was 0.0%, 8.5%, and 24.6% for LR-3 observations, and 0.0%, 0.0%, and 0.0% for LR-2 observations, respectively. In multivariable analysis, nonrim arterial phase hyperenhancement (APHE) [hazard ratio (HR) = 2.13, 95% CI 1.04-4.36; P = 0.038], threshold growth (HR = 6.50, 95% CI 2.88-14.65; P <0.001), and HBP hypointensity (HR = 16.83, 95% CI 3.97-71.34; P <0.001) were significant independent predictors of malignant progression.

CONCLUSION

The higher LI-RADS v2018 categories had an increasing risk of progression to a malignant category during long-term evolution. Nonrim APHE, threshold growth, and HBP hypointensity were the imaging features that were significantly predictive of malignant progression.

LI-RADS: Looking Back, Looking Forward

Since its initial release in 2011, the Liver Imaging Reporting and Data System (LI-RADS) has evolved and expanded in scope. It started as a single algorithm for hepatocellular carcinoma (HCC) diagnosis with CT or MRI with extracellular contrast agents and has grown into a multialgorithm network covering all major liver imaging modalities and contexts of use. Furthermore, it has developed its own lexicon, report templates, and supplementary materials. This article highlights the major achievements of LI-RADS in the past 11 years, including adoption in clinical care and research across the globe, and complete unification of HCC diagnostic systems in the United States. Additionally, the authors discuss current gaps in knowledge, which include challenges in surveillance, diagnostic population definition, perceived complexity, limited sensitivity of LR-5 (definite HCC) category, management implications of indeterminate observations, challenges in reporting, and treatment response assessment following radiation-based therapies and systemic treatments. Finally, the authors discuss future directions, which will focus on mitigating the current challenges and incorporating advanced technologies. Tha authors envision that LI-RADS will ultimately transform into a probability-based system for diagnosis and prognostication of liver cancers that will integrate patient characteristics and quantitative imaging features, while accounting for imaging modality and contrast agent.

Free-breathing and instantaneous abdominal T2 mapping via single-shot multiple overlapping-echo acquisition and deep learning reconstruction

OBJECTIVES

To develop a real-time abdominal T₂ mapping method without requiring breath-holding or respiratory-gating.

METHODS

The single-shot multiple overlapping-echo detachment (MOLED) pulse sequence was employed to achieve free-breathing T₂ mapping of the abdomen. Deep learning was used to untangle the non-linear relationship between the MOLED signal and T₂ mapping. A synthetic data generation flow based on Bloch simulation, modality synthesis, and randomization was proposed to overcome the inadequacy of real-world training set.

RESULTS

The results from simulation and in vivo experiments demonstrated that our method could deliver high-quality T₂ mapping. The average NMSE and R² values of linear regression in the digital phantom experiments were 0.0178 and 0.9751. Pearson's correlation coefficient between our predicted T₂ and reference T₂ in the phantom experiments was 0.9996. In the measurements for the patients, real-time capture of the T₂ value changes of various abdominal organs before and after contrast agent injection was realized. A total of 33 focal liver lesions were detected in the group, and the mean and standard deviation of T₂ values were 141.1 ± 50.0 ms for benign and 63.3 ± 16.0 ms for malignant lesions. The coefficients of variance in a test-retest experiment were 2.9%, 1.2%, 0.9%, 3.1%, and 1.8% for the liver, kidney, gallbladder, spleen, and skeletal muscle, respectively.

CONCLUSIONS

Free-breathing abdominal T₂ mapping is achieved in about 100 ms on a clinical MRI scanner. The work paved the way for the development of real-time dynamic T₂ mapping in the abdomen.

KEY POINTS

• MOLED achieves free-breathing abdominal T₂ mapping in about 100 ms, enabling real-time capture of T₂ value changes due to CA injection in abdominal organs. • Synthetic data generation flow mitigates the issue of lack of sizable abdominal training datasets.

Gadoxetate-Enhanced MRI as a Diagnostic Tool in the Management of Hepatocellular Carcinoma: Report from a 2020 Asia-Pacific Multidisciplinary Expert Meeting

Gadoxetate magnetic resonance imaging (MRI) is widely used in clinical practice for liver imaging. For optimal use, we must understand both its advantages and limitations. This article is the outcome of an online advisory board meeting and subsequent discussions by a multidisciplinary group of experts on liver diseases across the Asia-Pacific region, first held on September 28, 2020. Here, we review the technical considerations for the use of gadoxetate, its current role in the management of patients with hepatocellular carcinoma (HCC), and its relevance in consensus guidelines for HCC imaging diagnosis. In the latter part of this review, we examine recent evidence evaluating the impact of gadoxetate on clinical outcomes on a continuum from diagnosis to treatment decision-making and follow-up. In conclusion, we outline the potential future roles of gadoxetate MRI based on an evolving understanding of the clinical utility of this contrast agent in the management of patients at risk of, or with, HCC.

Hypervascular transformation of hepatobiliary phase hypointense nodules without arterial phase hyperenhancement on gadoxetic acid-enhanced MRI: long-term follow-up in a surveillance cohort

OBJECTIVES

With the increasing use of gadoxetic acid-enhanced MRI for HCC surveillance, hepatobiliary phase (HBP) hypointense nodules without arterial phase hyperenhancement (APHE) are frequently encountered. We investigated the rate of these nodules with hypervascular transformation, which suggests hepatocarcinogenesis, by using a prospectively collected longitudinal surveillance cohort data.

METHODS

This study included 382 prospectively enrolled patients at high risk for developing HCC who underwent 1-3 rounds of bi-annual surveillance gadoxetic acid-enhanced MRI. MRI was analyzed to detect HBP hypointense nodules without APHE. Follow-up dynamic CTs and MRIs were evaluated to detect hypervascular transformation of the nodules. Cox proportional hazards regression analyses were used to find predictors for hypervascular transformation.

RESULTS

A total of 76 HBP hypointense nodules without APHE were found in 48 patients, giving a prevalence of 12.6% (48/382). The mean nodule size was 10.8 mm, with 43.4% (33/76) being ≥ 10 mm. Over a median follow-up of 78.6 months, 19 nodules (25.0%) showed hypervascular transformation, all of which demonstrated typical imaging features of HCC. On multivariable Cox-regression analysis, size (≥ 10 mm) was the only independent predictor of hypervascular transformation (hazard ratio, 3.31; 95% confidence interval, 1.21-9.05). The cumulative incidence of hypervascular transformation at 12 and 60 months of nodules ≥ 10 mm was 12.3% and 50.4%, respectively, while that of nodules < 10 mm was 2.5% and 13.9%, respectively.

CONCLUSIONS

About half of the HBP hypointense nodules ≥ 10 mm without APHE transformed to HCC at 5 years of follow-up, indicating the necessity for cautious monitoring with an augmented and extended follow-up schedule for these nodules.

KEY POINTS

• The prevalence of HBP hypointense nodules without APHE was 12.6% in a prospectively recruited population at high risk of developing HCC. • Nodule size ≥ 10 mm was significantly associated with hypervascular transformation, and approximately half of the HBP hypointense nodules ≥ 10 mm without APHE transformed to HCC during 5 years of follow-up. • Given the risk of malignant transformation, HBP hypointense nodules ≥ 10 mm without APHE should be closely monitored.

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.

MR Imaging Contrast Agents: Role in Imaging of Chronic Liver Diseases

Contrast-enhanced MR imaging plays an important role in the evaluation of patients with chronic liver disease, particularly for detection and characterization of liver lesions. The two most commonly used contrast agents for liver MR imaging are extracellular agents (ECAs) and hepatobiliary agents (HBAs). In patients with liver disease, the main advantage of ECA-enhanced MR imaging is its high specificity for the diagnosis of progressed HCCs. Conversely, HBAs have an additional contrast mechanism, which results in high liver-to-lesion contrast and highest sensitivity for lesion detection in the hepatobiliary phase. Emerging data suggest that features depicted on contrast-enhanced MR imaging scans are related to tumor biology and are predictive of patients' prognosis, likely to further expand the role of contrast-enhanced MR imaging in the clinical care of patients with chronic liver disease.

Hepatobiliary phase hypointensity predicts progression to hepatocellular carcinoma for intermediate-high risk observations, but not time to progression

PURPOSE

To determine whether hepatobiliary phase hypointensity, enhancing "capsule" and size provide prognostic information regarding the risk of progression to hepatocellular carcinoma (HCC), as well as the time to progression, of intermediate to high risk observations ≥ 10 mm with arterial phase hyperenhancement (APHE).

METHOD

This retrospective dual-institution study included 160 LR-3 and 26 LR-4 observations measuring more than 10 mm and having APHE in 136 patients (mean age [SD], 57 [11] years old). A composite reference standard of pathologic analysis and imaging follow-up was used. The prognostic performance of hepatobiliary phase hypointensity, enhancing "capsule" and size (cut-off: 20 mm) for the prediction of probability of progression to HCC and median time to progression to HCC was assessed and compared by means of Log-rank test, Cox-regression and Kaplan-Meier curves.

RESULTS

110 (59%) of 186 of observations progressed to HCC, 29.1% (32) progressed within 6 months, 60% (66) within 1 year and 84.5% (93) within 2 years. Hepatobiliary phase hypointensity was a significant predictor of progression to HCC (p < 0.0001, odds ratio: 20.62) but not of time to progression (p = 0.17). Median time to progression to HCC was 284 days [IQR: 266-363] and was shorter - though not significantly - for observations with enhancing "capsule" (118 days vs 301 days; p = 0.19).

CONCLUSIONS

Hepatobiliary phase hypointensity is an independent predictor of progression to HCC in intermediate to high risk APHE observations ≥ 10 mm.

Cirrhotic Nodule Transformation to Hepatocellular Carcinoma: Natural History and Predictive Biomarkers on Contrast-Enhanced Ultrasound

OBJECTIVE. The objective of our study was to identify sonographic biomarkers predicting or indicating eventual malignant transformation of pathologically confirmed cirrhotic nodules. MATERIALS AND METHODS. Thirty-nine consecutive patients with 44 pathologically confirmed cirrhotic nodules (mean size, 17.5 ± 8.5 [SD] mm) who initially underwent contrast-enhanced ultrasound examination at detection and then underwent follow-up conventional ultrasound every 3-4 months thereafter were retrospectively included. Malignant transformation was identified on the basis of noninvasive diagnostic criteria for hepatocellular carcinoma or rebiopsy. Malignant transformation biomarkers were identified from clinical and sonographic variables and the performance thereof was evaluated using ROC curves. RESULTS. Fourteen nodules (31.8%) had eventual malignant transformation after a median follow-up time of 26.7 months. At initial detection, nodule size (hazard ratio [HR], 1.07; p = 0.019) and a contrast arrival time difference between the nodule and liver of more than 0.5 second (HR, 4.35; p = 0.011) were independent predictors for malignant transformation. The area under the ROC curve (A_z) of initial nodule size (A_z = 0.64, p = 0.131) and contrast arrival time difference between the nodule and liver (A_z = 0.66, p = 0.029) improved after combining the two (A_z = 0.75, p = 0.002). During follow-up, echogenicity change (p = 0.044), absolute growth rate (p < 0.001), and relative growth rate (p < 0.001) correlated with malignant transformation. Sensitivity analysis revealed that an absolute growth rate of 5 mm or greater in 6 months or a relative growth rate of 30% or greater in 6 months could be considered as threshold growth for identifying malignant transformation (specificity, 100.0%; positive predictive value, 100.0%). The absence of both echogenicity change and threshold growth was highly accurate in excluding malignant transformation (sensitivity, 100.0%; negative predictive value, 100.0%). CONCLUSION. The contrast arrival time difference between the nodule and liver at initial detection was useful in stratifying eventual malignant transformation risk for cirrhotic nodules. During follow-up, growth rate and echogenicity change correlated with malignant transformation; threshold growth on ultrasound may be considered a potential major feature in noninvasive diagnostic criteria of hepatocellular carcinoma.

Pathobiological and Radiological Approach For Hepatocellular Carcinoma Subclassification

Many advances have been made in the imaging diagnosis and in the histopathological evaluation of HCC. However, the classic imaging and histopathological features of HCC are still inadequate to define patient’s prognosis. We aimed to find the link between new proposed morphovascular patterns of hepatocellular carcinoma (HCC) and magnetic resonance imaging (MRI) features to identify pre-operatory markers of biologically aggressive HCC. Thirty-nine liver nodules in 22 patients were consecutively identified. Histopathological analysis and immunohistochemistry for CD34 and Nestin were performed to identify the four different HCC morphovascular patterns. MRI was performed using gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid. Three out of four morphovascular HCC patterns showed peculiar MRI features: in particular Pattern D (solid aggressive HCCs with CD34+/Nestin+ new-formed arteries) were isointense on T1-WI in 83% of cases and hyperintense on T2-WI in 50%. Five histologically-diagnosed HCC were diagnosed as non-malignant nodules on MRI due to their early vascularization and low aggressiveness (Pattern A). The comparison between histology and MRI confirms that a subclassification of HCC is possible in a pre-operatory setting. MRI seems to reinforce once more the identity of the different morphovascular HCC patterns and the possibility to pre-operatively identify HCCs with features of biological aggressiveness.

Hepatobiliary versus Extracellular MRI Contrast Agents in Hepatocellular Carcinoma Detection: Hepatobiliary Phase Features in Relation to Disease-free Survival

Background MRI with hepatobiliary contrast material is more sensitive than MRI with extracellular contrast material in the detection of hepatocellular carcinoma (HCC). Purpose To determine whether postsurgical outcomes differ between patients who undergo MRI with hepatobiliary contrast material and those who undergo MRI with extracellular contrast material by analyzing disease-free survival (DFS) rates after curative resection of HCC. Materials and Methods From January 2014 to December 2015, 170 treatment-naïve patients who underwent contrast-enhanced preoperative liver MRI and curative hepatic resection for HCC were retrospectively included and observed until September 2018. DFS rates were compared between the two groups, which were classified based on the type of MRI contrast agent used. The MRI with hepatobiliary contrast material group was further divided into a hypointense nodule-positive group and a hypointense nodule-negative group according to the presence of residual hepatobiliary phase (HBP) hypointense nodules without arterial phase hyperenhancement (APHE) after surgery. DFS rates were calculated by using the Kaplan-Meier method and were compared among the three groups by using a log-rank test. Results Patients were included in either the MRI with extracellular contrast material group (n = 53; mean age, 60 years ± 9 [standard deviation]) or the hepatobiliary contrast material group (n = 117; mean age, 60 years ± 8; 26 patients were in the hypointense nodule-positive group). Over a median follow-up period of 34.1 months, median DFS rates did not differ between the extracellular contrast material group (35.8 months) and the hepatobiliary contrast material group (43.5 months) (P = .46). However, median DFS in the extracellular contrast material group was longer than that in the hypointense nodule-positive group (35.8 months vs 25.8 months, P < .001) and shorter than that in the hypointense nodule-negative group (35.8 months vs 48.6 months, P = .02). Conclusion Patients who undergo preoperative MRI with hepatobiliary contrast material and resection of hepatobiliary phase hypointense nodules without arterial phase hyperenhancement may show better disease-free survival. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Motosugi in this issue.

Use of gadoxetate disodium in patients with chronic liver disease and its implications for liver imaging reporting and data system (LI-RADS)

Use of gadoxetate disodium, a hepatobiliary gadolinium-based agent, in patients with chronic parenchymal liver disease offers the advantage of improved sensitivity for detecting hepatocellular carcinoma (HCC). Imaging features of liver observations on gadoxetate-enhanced MRI may also serve as biomarkers of recurrence-free and overall survival following definitive treatment of HCC. A number of technical and interpretative pitfalls specific to gadoxetate exist, however, and needs to be recognized when protocoling and interpreting MRI exams with this agent. This article reviews the advantages and pitfalls of gadoxetate use in patients at risk for HCC, and the potential impact on Liver Imaging Reporting and Data System (LI-RADS) imaging feature assessment and categorization. Level of Evidence: 5 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2019;49:1236-1252.

Hypervascular Transformation of Hypovascular Hypointense Nodules in the Hepatobiliary Phase of Gadoxetic Acid-Enhanced MRI: A Systematic Review and Meta-Analysis

OBJECTIVE

The purpose of this study is to evaluate the outcomes of hypovascular hypointense nodules in the hepatobiliary phase of gadoxetic acid-enhanced MRI and the risk factors for the hypervascular transformation of the nodules through a systematic review and meta-analysis.

MATERIALS AND METHODS

We searched the Ovid-MEDLINE and EMBASE databases for published studies of hypovascular hypointense nodules in patients with chronic liver disease. The pooled proportions of the overall and cumulative incidence rates at 1, 2, and 3 years for the transformation of hypovascular hypointense nodules into hypervascular hepatocellular carcinomas (HCCs) were assessed by using random-effects modeling. Metaregression analysis was performed.

RESULTS

Sixteen eligible studies with 944 patients and 1819 hypovascular hypointense nodules in total were included. The pooled overall rate of hypervascular transformation was 28.2% (95% CI, 22.7-33.6%; I² = 87.46%). The pooled 1-, 2-, and 3-year cumulative incidence rates were 18.3% (95% CI, 9.2-27.4%), 25.2% (95% CI, 12.2-38.2%), and 30.3% (95% CI, 18.8-41.9%), respectively. The metaregression analysis revealed that the mean initial nodule size (cutoff value, 9 mm) was a significant factor affecting the heterogeneity of malignant transformation.

CONCLUSION

Hypovascular hypointense nodules detected in the hepatobiliary phase of gadoxetic acid-enhanced MRI carry a significant potential of transforming into hypervascular HCCs. The size of nodules is a significant risk factor for hypervascular transformation.

Interval to vascularization development in cirrhotic precursor nodules in patients with hepatitis B and C virus co-infections

With the widespread use of gadoxetic acid-enhanced magnetic resonance imaging, liver nodules appearing as hypovascular in the arterial phase and hypointense in the hepatobiliary phase, defined as hypovascular hypointense nodules, are increasingly detected in patients with cirrhosis and are considered precursor nodules. We sought to evaluate the interval to vascularization development in hepatitis C virus/hepatitis B virus co-infected-associated precursor nodules (BC-HHN group) compared with that in hepatitis C virus mono-infected-associated precursor nodules (C-HHN group) in the hepatobiliary phase of gadoxetic acid-enhanced magnetic resonance imaging. The interval to vascularization development was estimated by the Kaplan-Meier method and compared using the Cox proportional hazards model. The mean intervals to vascularization development in the BC-HHN and C-HHN groups were 272.9±31.1 and 603.8±47.6 days, respectively (p<0.001). The cumulative vascularization development incidence at 6, 12, and 18 months was 44.9%, 73.5%, and 91.8%, respectively, in the BC-HHN group and 16.9%, 39.0%, and 55.8%, respectively, in the C-HHN group (p<0.001). The multivariate analysis showed that the presence of hepatitis B virus co-infection (hazard ratio: 1.819; 95% confidence interval: 1.222–2.707; p = 0.003) and male sex (hazard ratio: 1.753; 95% confidence interval: 1.029–2.985; p = 0.039) were predictors of vascularization development. More than half of the hypovascular hypointense nodules showed high-signal changes on T2-weighted imaging, and almost half of them showed restricted diffusion on diffusion-weighted images, but these did not predict vascularization development. In a hepatitis C virus- and hepatitis B virus-endemic area, such as Taiwan, precursor nodules in the BC-HHN group tended to have shorter intervals to vascularization development, especially in male patients.

Dynamic contrast enhanced MR imaging for evaluation of angiogenesis of hepatocellular nodules in liver cirrhosis in N-nitrosodiethylamine induced rat model

PURPOSE

To investigate whether dynamic contrast -enhanced MRI (DCE-MRI) can distinguish the type of liver nodules in a rat model with N-nitrosodiethylamine- induced cirrhosis.

METHODS

Liver nodules in cirrhosis were induced in 60 male Wistar rats via 0.01 % N-nitrosodiethylamine in the drinking water for 35-100 days. The nodules were divided into three groups: regenerative nodule (RN), dysplastic nodule (DN), and hepatocellular carcinoma (HCC). DCE-MRI was performed, and parameters including transfer constant (K^trans), rate constant (K_ep), extravascular extracellular space volume fraction (V_e), and initial area under the contrast concentration versus time curve (iAUC) were measured and compared.

RESULTS

The highest K^trans and iAUC values were seen in HCC, followed by DN and RN (all P < 0.05). The area under the receiver operating characteristic curve (AUROC) for DN and HCC were 0.738 and 0.728 for K^trans and iAUC, respectively. The AUROC for HCC were 0.850 and 0.840 for K^trans and iAUC, respectively. Ordinal logistic regression analysis showed that K^trans had a high goodness of fit (0.970, 95 % confidence interval, 13.751-24.958).

CONCLUSION

DCE-MRI is a promising method to differentiate of liver nodules. Elevated K^trans suggested that the nodules may be transformed into HCC.

KEY POINTS

• DCE-MRI is promising for differentiating among RN, DN, and HCC • K ^trans and iAUC positively correlated with malignancy degree of liver nodules • Elevated K ^trans suggests that the nodules may be transformed into HCC.

Outcome of hypovascular hepatic nodules with positive uptake of gadoxetic acid in patients with cirrhosis

OBJECTIVES

To evaluate the longitudinal risk to patients with cirrhosis of hypervascular hepatocellular carcinoma (HCC) developing from hypovascular hepatic nodules that show positive uptake of gadoxetic acid (hyperintensity) on hepatocyte phase images.

METHODS

In 69 patients, we evaluated findings from serial follow-up examinations of 633 hepatic nodules that appeared hypovascular and hyperintense on initial gadoxetic acid-enhanced magnetic resonance imaging (EOB-MRI) until the nodules demonstrated hypervascularity and were diagnosed as hypervascular HCC. Cox analyses were performed to identify risk factors for the development of hypervascular HCCs from the nodules.

RESULTS

The median follow-up was 663 days (range, 110 to 1215 days). Hypervascular HCCs developed in six of the 633 nodules (0.9 %) in five of the 69 patients. The only independent risk factor, the nodule's initial maximum diameter of 10 mm or larger, demonstrated a hazard ratio of 1.25. The one-year risk of hypervascular HCC developing from a nodule was 0.44 %. The risk was significantly higher for nodules of larger diameter (1.31 %) than those smaller than 10 mm (0.10 %, p < 0.01).

CONCLUSIONS

Hypervascular HCC rarely develops from hypovascular, hyperintense hepatic nodules. We observed low risk even for nodules of 10 mm and larger diameter at initial examination.

KEY POINTS

• Hypervascularization was rare on follow-up examination of hypovascular, hyperintense nodules • The risk of hypervascularization in a nodule increased with large size • Hypovascular, hyperintense nodules require neither treatment nor more intense follow-up.