The Diagnostic Performance of Liver MRI without Intravenous Contrast for Detecting Hepatocellular Carcinoma: A Case-Controlled Feasibility Study

Abbreviated magnetic resonance imaging in hepatocellular carcinoma surveillance: A review

Hepatocellular carcinoma (HCC) is one of the most common primary malignancies of the liver and a leading cause for cancer-related deaths worldwide. HCC surveillance aims at early detection. The recommended strategy for screening HCC is biannual ultrasound with or without alpha-fetoprotein. However, this strategy is associated with sub-optimal sensitivity. Abbreviated magnetic resonance imaging (AMRI) is a promising alternative to ultrasound (US) for surveillance of HCC. The data regarding the role of AMRI in HCC screening is evolving. There are different AMRI protocols, each having its merits and disadvantages. In this review, we discuss the need for AMRI, protocols of AMRI and hindrances to widespread adoption of AMRI.

Abbreviated MRI for Hepatocellular Carcinoma Surveillance - A Systematic Review and Meta-analysis

BACKGROUND

Given the limited sensitivity of ultrasound in hepatocellular carcinoma (HCC) surveillance, this systematic review and meta-analysis were aimed to assess the diagnostic performance of non-contrast abbreviated MRI (NC-aMRI) compared to contrast-enhanced abbreviated MRI (CE-aMRI) for HCC surveillance, offering evidence-based guidance for clinical decision-making.

METHODS

A comprehensive search was conducted across five databases, identifying studies on aMRI for HCC surveillance. The pooled sensitivity and specificity were estimated using a random effects model. Subgroup analyses and meta-regression were performed by study location, proportion of patients with cirrhosis and HCC, and underlying liver diseases.

RESULTS

The meta-analysis included 27 studies (2009-2023), distributed between Western (n = 14) and Eastern (n = 13) countries. The pooled sensitivity and specificity (95%CI, I2) were 86% (83-88%, 63%) and 92% (90%-94%, 74%). The NC-aMRI protocols reported in 21 studies exhibited 83% (79-87%, 63%) sensitivity and 91% (88-93%, 67%) specificity, while the 15 studies on CE-aMRI protocols displayed 88% (84-91%, 64%) sensitivity and 94% (90-96%, 78%) specificity, with no statistically significant differences in sensitivity (p = 0.078) or specificity (p = 0.157). Subgroup analysis in NC-aMRI studies showed significant differences in sensitivity for high-prevalent chronic hepatitis B (87% vs. 78%, p = 0.003) and studies done in eastern countries (86% vs. 76%, p = 0.018). Additionally, specificity showed significant differences for high-prevalent chronic hepatitis C (94% vs. 90%, p = 0.009), with meta-regression identifying major sources of study heterogeneity as the inclusion of a majority of patients with chronic hepatitis B (p = 0.008) and the geographic regions where studies were conducted (p = 0.030).

CONCLUSION

Surveillance aMRI protocols exhibit satisfactory performance for detecting HCC. NC-aMRI may be used effectively for HCC surveillance, especially in chronic hepatitis B prevalent settings.

Screening of liver cancer with abbreviated MRI

Current recommendations for the surveillance of HCC are based on the semiannual liver ultrasound (with or without serum alpha-fetoprotein) in patients with cirrhosis and in subgroups with chronic hepatitis B infection. However, the sensitivity of this strategy is suboptimal for the detection of early-stage tumors, especially in obese patients, due to interoperator variability and poor adherence. The detection rate of focal liver lesions is excellent with MRI, making it the best alternative candidate for surveillance. However, performing a full contrast-enhanced MRI is unrealistic because of limited availability and health economics. Abbreviated MRI (AMRI) corresponds to the acquisition of a limited number of sequences with a high detection rate. The theoretical benefits of AMRI are a reduced acquisition time (≤10 min) with improved time-effectiveness and cost-effectiveness compared with conventional MRI, and greater accuracy than ultrasound. Numerous protocols may be performed, including T1-weighted, T2-weighted, and DWI sequences, with or without contrast administration. Although published studies report promising per-patient results, they should be interpreted with caution. Indeed, most studies were simulated, retrospectively reviewing a subset of sequences in relatively small populations who underwent a full MRI. They also included groups that were not representative of screening populations. In addition, most were published by Asian groups, with at-risk populations that were different from Western populations. There are no existing longitudinal studies that directly compare the different AMRI approaches or AMRI to ultrasound. Finally, it is possible that 1 approach will not fit all patients and that strategies should be tailored to the risk of HCC, in particular in relation to the cost and availability of AMRI. Several trials are ongoing to evaluate these questions.

Estimating postsurgical outcomes of patients with a single hepatocellular carcinoma using gadoxetic acid-enhanced MRI: risk scoring system development and validation

OBJECTIVES

To develop and validate risk scoring systems using gadoxetic acid-enhanced liver MRI features and clinical factors that predict recurrence-free survival (RFS) of a single hepatocellular carcinoma (HCC).

METHODS

Consecutive 295 patients with treatment-naïve single HCC who underwent curative surgery were retrospectively enrolled from two centers. Cox proportional hazard models developed risk scoring systems whose discriminatory powers were validated using external data and compared to the Barcelona Clinic Liver Cancer (BCLC) or American Joint Committee on Cancer (AJCC) staging systems using Harrell's C-index.

RESULTS

Independent variables-tumor size (per cm; hazard ratio [HR], 1.07; 95% confidence interval [CI]: 1.02-1.13; p = 0.005), targetoid appearance (HR, 1.74; 95% CI: 1.07-2.83; p = 0.025), radiologic tumor in vein or tumor vascular invasion (HR, 2.59; 95% CI: 1.69-3.97; p < 0.001), the presence of a nonhypervascular hypointense nodule on the hepatobiliary phase (HR, 4.65; 95% CI: 3.03-7.14; p < 0.001), and pathologic macrovascular invasion (HR, 2.60; 95% CI: 1.51-4.48; p = 0.001)-with tumor markers (AFP ≥ 206 ng/mL or PIVKA-II ≥ 419 mAU/mL) derived pre- and postoperative risk scoring systems. The risk scores showed comparably good discriminatory powers in the validation set (C-index, 0.75-0.82) and outperformed the BCLC (C-index, 0.61) and AJCC staging systems (C-index, 0.58; ps < 0.05). The preoperative scoring system stratified the patients into low-, intermediate-, and high-risk for recurrence, whose 2-year recurrence rate was 3.3%, 31.8%, and 85.7%, respectively.

CONCLUSION

The developed and validated pre- and postoperative risk scoring systems can estimate RFS after surgery for a single HCC.

KEY POINTS

• The risk scoring systems predicted RFS better than the BCLC and AJCC staging systems (C-index, 0.75-0.82 vs. 0.58-0.61; ps < 0.05). • Five variables-tumor size, targetoid appearance, radiologic tumor in vein or vascular invasion, the presence of a nonhypervascular hypointense nodule on the hepatobiliary phase, and pathologic macrovascular invasion-combined with tumor markers derived risk scoring systems predicting postsurgical RFS for a single HCC. • In the risk scoring system using preoperatively-available factors, patients were classified into three distinct risk groups, with 2-year recurrence rates in the low-, intermediate-, and high-risk groups being 3.3%, 31.8%, and 85.7% in the validation set.

Inter-reader agreement of abbreviated magnetic resonance imaging for hepatocellular carcinoma detection: a systematic review and meta-analysis

PURPOSE

To determine the inter-reader agreement of abbreviated magnetic resonance imaging (AMRI) for the detection of hepatocellular carcinoma (HCC) and explore the causes of heterogeneity between the reported results.

METHODS

Original studies reporting the inter-reader agreement of AMRI for detecting HCC were identified in MEDLINE, EMBASE, and Cochrane databases. The pooled kappa coefficient (κ) was calculated using the DerSimonian-Laird random-effects model. Subgroup analyses were performed according to the AMRI protocol (non-contrast [NC]-AMRI, dynamic contrast-enhanced [DCE]-AMRI, and hepatobiliary phase [HBP]-AMRI). Meta-regression analyses were performed to further explore study heterogeneity.

RESULTS

In the eight included studies (1182 patients), the overall pooled κ was 0.76 (95% confidence interval [CI], 0.70-0.82; I² = 74.4%). The κ of NC-AMRI, DCE-AMRI, and HBP-AMRI were 0.72 (95% CI, 0.62-0.82), 0.80 (95% CI, 0.78-0.82), and 0.98 (95% CI, 0.95-1.00), respectively. In the NC-AMRI, the pooled κ of NC-AMRI using only diffusion-weighted imaging (DWI) was 0.64, which was lower than the values using two or more imaging sequences (κ = 0.74-0.77). In subgroup analysis, no study heterogeneity was noted in studies using DCE-AMRI (I² = 0%), whereas high heterogeneity was noted with NC-AMRI (I² = 80.5%). Especially, NC-AMRI including more than two imaging sequences showed high residual heterogeneity (I² = 87.6%). Meta-regression analysis found that difference in reader experience was significantly associated with study heterogeneity (p = .02).

CONCLUSION

AMRI for detecting HCC showed substantial inter-reader agreement across all examined protocols. NC-AMRI, notably NC-AMRI using only DWI, had relatively low inter-reader agreement. Therefore, DCE-AMRI or HBP-AMRI may be more reliable than NC-AMRI using only DWI.

Noncontrast MRI for Hepatocellular Carcinoma Detection: A Systematic Review and Meta-analysis - A Potential Surveillance Tool?

BACKGROUND AND AIMS

This meta-analysis investigates the diagnostic performance of non-contrast magnetic resonance imaging (MRI) for the detection of hepatocellular carcinoma (HCC).

METHODS

A systematic review was performed to May 2020 for studies which examined the diagnostic performance of non-contrast MRI (multi-sequence or diffusion-weighted imaging (DWI)- alone) for HCC detection in high risk patients. The primary outcome was accuracy for the detection of HCC. Random effects models were used to pool outcomes for sensitivity, specificity, positive likelihood ratio (LR) and negative LR. Subgroup analyses for cirrhosis and size of the lesion were performed.

RESULTS

Twenty-two studies were included involving 1685 patients for per-patient analysis and 2128 lesions for per-lesion analysis. Multi-sequence non-contrast MRI (NC-MRI) using T2+DWI±T1 sequences had a pooled per-patient sensitivity of 86.8% (95%CI:83.9-89.4%), specificity of 90.3% (95%CI:87.3-92.7%), and negative LR of 0.17 (95%CI:0.14-0.20). DWI-only MRI (DW-MRI) had a pooled sensitivity of 79.2% (95%CI:71.8-85.4%), specificity of 96.5% (95%CI:94.3-98.1%) and negative LR of 0.24 (95%CI:1.62-0.34). In patients with cirrhosis, NC-MRI had a pooled per-patient sensitivity of 87.3% (95%CI:82.7-91.0%) and specificity of 81.6% (95%CI:75.3-86.8%), whilst DWI-MRI had a pooled sensitivity of 71.4% (95%CI:60.5-80.8%) and specificity of 97.1% (95%CI:91.9-99.4%). For lesions <2 cm, the pooled per-lesion sensitivity was 77.1% (95%CI:73.8-80.2%). For lesions >2 cm, pooled per-lesion sensitivity was 88.5% (95%CI:85.0-91.5%).

CONCLUSION

Non-contrast MRI has a moderate negative LR and high specificity with acceptable sensitivity for the detection of HCC, even in patients with cirrhosis and with lesions <2 cm. Prospective trials to validate if non-contrast MRI can be used for HCC surveillance is warranted.

Imaging Diagnosis of HCC: Future directions with special emphasis on hepatobiliary MRI and contrast-enhanced ultrasound

Hepatocellular carcinoma (HCC) is a unique cancer entity that can be noninvasively diagnosed using imaging modalities without pathologic confirmation. In 2018, several major guidelines for HCC were updated to include hepatobiliary contrast agent magnetic resonance imaging (HBA-MRI) and contrast-enhanced ultrasound (CEUS) as major imaging modalities for HCC diagnosis. HBA-MRI enables the achievement of high sensitivity in HCC detection using the hepatobiliary phase (HBP). CEUS is another imaging modality with real-time imaging capability, and it is reported to be useful as a second-line modality to increase sensitivity without losing specificity for HCC diagnosis. However, until now, there is an unsolved discrepancy among guidelines on whether to accept “HBP hypointensity” as a definite diagnostic criterion for HCC or include CEUS in the diagnostic algorithm for HCC diagnosis. Furthermore, there is variability in terminology and inconsistencies in the definition of imaging findings among guidelines; therefore, there is an unmet need for the development of a standardized lexicon. In this article, we review the performance and limitations of HBA-MRI and CEUS after guideline updates in 2018 and briefly introduce some future aspects of imaging-based HCC diagnosis.

Abbreviated MR Protocols for Chronic Liver Disease and Liver Cancer

MR imaging has become a powerful tool for assessing liver disease and liver cancer; however, it entails complex, time-consuming, and costly protocols. Abbreviated MR imaging (AMRI) is emerging as a simpler, faster, and low-cost alternative to full-abdominal MR imaging protocols. Different AMRI approaches have been tested successfully in hepatocellular carcinoma detection and for assessment of diffuse liver disease. The most accurate, time-effective, and cost-effective protocol as well as the target population need to be defined. Prospective and multicentric studies, exploring different AMRI protocols versus the current standard of reference, should be performed.

Abbreviated MRI for hepatocellular carcinoma screening: A systematic review and meta-analysis

BACKGROUND & AIMS

Biannual ultrasound has poor sensitivity for hepatocellular carcinoma (HCC) screening. MRI is accurate for the detection of HCC, but a complete MRI is not feasible as a screening tool. Abbreviated MRI (AMRI) is an acceptable alternative. The diagnostic performance of different AMRI protocols is not known. We performed a systematic review to determine the diagnostic accuracy of AMRI for HCC screening.

METHODS

We searched the MEDLINE and EMBASE databases for studies reporting the diagnostic accuracy of AMRI for HCC screening. The pooled sensitivity and specificity of different AMRI protocols were calculated based on a random intercept logistic regression model. The diagnostic performance of AMRI was compared with ultrasound. Study quality was assessed using the QUADAS-2 tool.

RESULTS

Of the 11,327 studies screened by titles, 15 studies (3 prospective and 12 retrospective: 2,807 patients, 917 with HCC) were included in the final analysis. The pooled per-patient sensitivity and specificity were 86% (95% CI 84-88%, I² 0%) and 94% (95% CI 91-96%, I² 83%), respectively. Pooled per-lesion sensitivity was 77% (95% CI 74-81%, I² 8%). There was no influence of study type, screening setting, reference standard, and presence and etiology of cirrhosis on the performance of AMRI. The sensitivity of AMRI for detection of HCC <2 cm was lower than that for HCC ≥2 cm (69% vs. 86%). The sensitivity and specificity of non-contrast AMRI were comparable to contrast-enhanced AMRI (86% and 94% vs. 87% and 94%, respectively). The diagnostic performance of different non-contrast AMRI and contrast-enhanced AMRI protocols was comparable. The sensitivity of ultrasound was lower than AMRI (53% vs. 82%).

CONCLUSIONS

AMRI has high sensitivity and specificity for HCC screening. Different AMRI protocols have comparable diagnostic performance.

LAY SUMMARY

Abbreviated MRI (AMRI) has been suggested as an alternative to ultrasound and complete MRI for hepatocellular carcinoma (HCC) screening. Our study results showed that AMRI has a high per-patient and per-lesion sensitivity for HCC. Although the sensitivity of AMRI for detection of HCC <2 cm is considerably lower than for HCC ≥2 cm, it is substantially higher than ultrasound, making it a potential alternative for HCC screening in high-risk populations.

United adversarial learning for liver tumor segmentation and detection of multi-modality non-contrast MRI

Simultaneous segmentation and detection of liver tumors (hemangioma and hepatocellular carcinoma (HCC)) by using multi-modality non-contrast magnetic resonance imaging (NCMRI) are crucial for the clinical diagnosis. However, it is still a challenging task due to: (1) the HCC information on NCMRI is insufficient makes extraction of liver tumors feature difficult; (2) diverse imaging characteristics in multi-modality NCMRI causes feature fusion and selection difficult; (3) no specific information between hemangioma and HCC on NCMRI cause liver tumors detection difficult. In this study, we propose a united adversarial learning framework (UAL) for simultaneous liver tumors segmentation and detection using multi-modality NCMRI. The UAL first utilizes a multi-view aware encoder to extract multi-modality NCMRI information for liver tumor segmentation and detection. In this encoder, a novel edge dissimilarity feature pyramid module is designed to facilitate the complementary multi-modality feature extraction. Secondly, the newly designed fusion and selection channel is used to fuse the multi-modality feature and make the decision of the feature selection. Then, the proposed mechanism of coordinate sharing with padding integrates the multi-task of segmentation and detection so that it enables multi-task to perform united adversarial learning in one discriminator. Lastly, an innovative multi-phase radiomics guided discriminator exploits the clear and specific tumor information to improve the multi-task performance via the adversarial learning strategy. The UAL is validated in corresponding multi-modality NCMRI (i.e. T1FS pre-contrast MRI, T2FS MRI, and DWI) and three phases contrast-enhanced MRI of 255 clinical subjects. The experiments show that UAL gains high performance with the dice similarity coefficient of 83.63%, the pixel accuracy of 97.75%, the intersection-over-union of 81.30%, the sensitivity of 92.13%, the specificity of 93.75%, and the detection accuracy of 92.94%, which demonstrate that UAL has great potential in the clinical diagnosis of liver tumors.

Meta-Analysis of the Accuracy of Abbreviated Magnetic Resonance Imaging for Hepatocellular Carcinoma Surveillance: Non-Contrast versus Hepatobiliary Phase-Abbreviated Magnetic Resonance Imaging

Simple Summary

Ultrasonography is recommended as a standard surveillance modality, but the performance of surveillance ultrasound for detecting early-stage hepatocellular carcinoma (HCC) is limited. Motivated to provide a more sensitive method, abbreviated magnetic resonance imaging (AMRI) protocols have been introduced for HCC surveillance. We aimed to systematically determine the diagnostic performance of surveillance AMRI for detecting HCC. This meta-analysis of 10 studies comprising 1547 patients found that the pooled sensitivity and specificity of surveillance AMRI for detecting HCC were 86% and 96%, respectively. Hepatobiliary phase contrast-enhanced AMRI showed significantly higher sensitivities for detecting HCC than non-contrast AMRI (87% vs. 82%), but significantly lower specificities (93% vs. 98%). Therefore, surveillance AMRI had overall good diagnostic performance for detecting HCC and might be clinically useful for HCC surveillance. In addition, AMRI protocol should be selected with consideration of the advantages and disadvantages of each protocol.

Abstract

We aimed to determine the performance of surveillance abbreviated magnetic resonance imaging (AMRI) for detecting hepatocellular carcinoma (HCC), and to compare the performance of surveillance AMRI according to different protocols. Original research studies reporting the performance of surveillance AMRI for the detection of HCC were identified in MEDLINE, EMBASE, and Cochrane databases. The pooled sensitivity and specificity of surveillance AMRI were calculated using a hierarchical model. The pooled sensitivity and specificity of contrast-enhanced hepatobiliary phase (HBP)-AMRI and non-contrast (NC)-AMRI were calculated and compared using bivariate meta-regression. Ten studies, including 1547 patients, reported the accuracy of surveillance AMRI. The pooled sensitivity and specificity of surveillance AMRI for detecting any-stage HCC were 86% (95% confidence interval (CI), 80–90%; I² = 0%) and 96% (95% CI, 93–98%; I² = 80.5%), respectively. HBP-AMRI showed a significantly higher sensitivity for detecting HCC than NC-AMRI (87% vs. 82%), but significantly lower specificity (93% vs. 98%) (p = 0.03). Study quality and MRI magnet field strength were factors significantly associated with study heterogeneity (p ≤ 0.01). In conclusion, surveillance AMRI showed good overall diagnostic performance for detecting HCC. HBP-AMRI had significantly higher sensitivity for detecting HCC than NC-AMRI, but lower specificity.

Assessment of SE-MRE-derived shear stiffness at 3.0 Tesla for solid liver tumors characterization

OBJECTIVES

To evaluate the feasibility and diagnostic value of using a 2D spin-echo MR elastography (SE-MRE) sequence at 3.0 Tesla for solid focal liver lesions (FLL) characterization.

METHODS

This prospective study included 55 patients with solid FLL (size > 20 mm), who underwent liver SE-MRE at 3 Tesla between 2016 and 2019. Stiffness measurements were performed by two independent readers blinded to the complete MRI exam or patient information. Histological confirmation or typical behavior on the complete MRI exam evaluated in consensus by expert abdominal radiologists was used as reference standard. FLLs were grouped and compared (malignant vs. benign) using the Mann-Whitney and Kruskal-Wallis tests. MRE diagnostic performance was assessed, and stiffness cutoffs were obtained by analysis of ROC curves from accuracy maximization. A linear regression plot was used to evaluate inter-rater agreement for FLLs stiffness measurements. p values < 0.05 were considered statistically significant.

RESULTS

The final study group comprised 57 FLLs (34 malignant, 23 benign). Stiffness measurements were technically successful in 91.23% of lesions. To both readers, the median stiffness of the lesions categorized as benign was 4.5 ± 1.5 kPa and in the malignant group 6.8 ± 1.7 and 7.5 ± 1.5 kPa depending on the reader. A cutoff of 5.8 kPa distinguished malignant and benign lesions with 88% specificity and 75-85% accuracy depending on the reader. The inter-rater agreement was 0.90 ± 0.04 with a correlation coefficient of 0.94.

CONCLUSION

2D-SE-MRE at 3.0 T provides high specificity and PPV to differentiate benign from malignant liver lesions. Trial registration 18FFUA-A02.

Abbreviated MRI Protocol for the Assessment of Ablated Area in HCC Patients

Background: Liver Imaging Reporting and Data Systems (LI-RADS) Treatment Response Algorithm (TRA) was created to provide a standardized assessment of hepatocellular carcinoma (HCC) following loco regional therapy. The aim of this study was to compare sensitivity of standard MRI protocol versus abbreviated protocol (only T1-Weigthed fat suppressed (FS) sequences pre- and post-contrast phase) in the detection of ablated area according to LI-RADS Treatment Response (LR-TR) categories. Methods: From January 2015 to June 2020, we selected 64 patients with HCC, who underwent Radiofrequency ablation (RFA) or Microwave ablation (MWA) treatment. According to inclusion criteria, 136 pathologically proven treated HCC (median 2, range 1–3 per patient; mean size 20.0 mm; range 15–30 mm) in 58 patients (26 women, 32 men; median age, 74 years; range, 62–83 years) comprised our study population. For each ablated area, abbreviated protocol, and standard Magnetic Resonance Imaging (MRI) studies were independently and blindly assessed in random order within and between three expert radiologists. Each radiologist assessed the ablated area by using the following categories: “LR-TR Non-viable” = 1; “LR-TR Equivocal” = 2 and “LR-TR Viable” = 0. Results: According to the concordance between MRI and Contrast enhancement ultrasound (CEUS) among 136 treated HCCs, 115 lesions were assessed as non-viable or totally ablate and 21 as viable or partially ablate. The accuracy for standard MRI protocol and abbreviated MRI protocol for predicting pathologic tumor viability of a consensus reading was 98.6% (sensitivity = 100%; specificity = 98.3%; positive predictive value = 91.3% and negative predictive value = 100%). No differences were found in sensitivity or specificity between standard MRI LR-TR viable and abbreviated MRI LR-TR viable categories (p value > 0.05 at McNemar test). Conclusion: The abbreviated dynamic protocol showed similar diagnostic accuracy to conventional MRI study in the assessment of treated HCCs, with a reduction of the acquisition study time of 30% respect to conventional MRI.

[Recent Updates of Abbreviated MRI for Hepatocellular Carcinoma Screening]

International guidelines recommended screening with ultrasonography (US) every 6 months for patients at risk for hepatocellular carcinoma (HCC). However, US demonstrates low sensitivity for the early detection of HCC. Magnetic resonance imaging (MRI) plays an important role in the noninvasive diagnosis of HCC, but it is not suitable for surveillance due to its lengthy examination and high cost. Therefore, several studies have been using various abbreviated MRI strategies, including noncontrast abbreviated MRI, dynamic contrast-enhanced abbreviated MRI, and abbreviated MRI using hepatobiliary phase image for HCC surveillance. In this article, we aim to review these various strategies and explore the future direction of HCC surveillance considering the cost-effectiveness aspect.

Current status of image-based surveillance in hepatocellular carcinoma

Although the overall prognosis of patients with hepatocellular carcinoma (HCC) remains poor, curative treatment may improve the survival of patients diagnosed at an early stage through surveillance. Accordingly, ultrasonography (US)-based HCC surveillance programs proposed in international society guidelines are now being implemented and regularly updated based on the latest evidence to improve their efficacy. Recently, other imaging modalities such as magnetic resonance imaging have shown potential as alternative surveillance tools based on individualized risk stratification. In this review article, we describe the current status of US-based surveillance for HCC and summarize the supporting evidence. We also discuss alternative surveillance imaging modalities that are currently being studied to validate their diagnostic performance and cost-effectiveness.

Diagnostic Performance of Simulated Abbreviated MRI for Early-Stage Hepatocellular Carcinoma Screening: A Comparison to Conventional Dynamic Contrast-Enhanced MRI

Purpose

To compare the per-patient diagnostic performance of simulated abbreviated MRI (AMRI) to that of conventional MRI (CMRI) with full-sequence dynamic gadoxetic acid (GA) enhancement for early-stage hepatocellular carcinoma (HCC) screening in high-risk patients.

Materials and Methods

A total of 201 consecutive patients at high-risk for HCC, who underwent 3T liver MRI, were included in this retrospective study. The AMRI protocol comprised T2-weighted imaging, hepatobiliary phase imaging after GA injection, and diffusion-weighted imaging. For each patient, two AMRI and CMRI image sets were independently reviewed by two radiologists. Inter-reader agreement was assessed using Cohen's kappa value. A composite reference standard was used to determine the diagnostic performance of each image set for each reader.

Results

A total of 93 HCCs were detected in 79 patients. The inter-reader agreement was almost perfect for both image sets (κ = 0.839, 0.948). In AMRI, the per-patient sensitivity and negative predictive values (NPV) were 94.9% and 96.4%, respectively. In CMRI, the per-patient sensitivity and NPV were 96.2% and 97.5%, respectively.

Conclusion

AMRI, using only three sequences, had a comparable diagnostic performance to CMRI in screening early-stage HCC. AMRI could be an alternative HCC screening tool for high-risk HCC patients.

Abbreviated MRI protocol for colorectal liver metastases: How the radiologist could work in pre surgical setting

Background

MRI is the most reliable imaging modality that allows to assess liver metastases. Our purpose is to compare the per-lesion and per-patient detection rate of gadoxetic acid-(Gd-EOB) enhanced liver MRI and fast MR protocol including Diffusion Weighted Imaging (DWI) and T2-W Fat Suppression sequence in the detection of liver metastasis in pre surgical setting.

Methods

One hundred and eight patients with pathologically proven liver metastases (756 liver metastases) underwent Gd-EOBMRI were enrolled in this study. Three radiologist independently graded the presence of liver lesions on a five-point confidence scale assessed only abbreviated protocol (DWI and sampling perfection with application-optimized contrasts using different flip angle evolution (SPACE) fat suppressed sequence) and after an interval of more than 2 weeks the conventional study (all acquired sequences). Per-lesion and per-patient detection rate of metastases were calculated. Weighted к values were used to evaluate inter-reader agreement of the confidence scale regarding the presence of the lesion.

Results

MRI detected 732 liver metastases. All lesions were identified both by conventional study as by abbreviated protocol. In terms of per-lesion detection rate of liver metastasis, all three readers had higher detection rate both with abbreviated protocol and with standard protocol with Gd-EOB (96.8% [732 of 756] vs. 96.5% [730 of 756] for reader 1; 95.8% [725 of 756] vs. 95.2% [720 of 756] for reader 2; 96.5% [730 of 756] vs. 96.5% [730 of 756] for reader 3). Inter-reader agreement of lesions detection rate between the three radiologists was excellent (k range, 0.86–0.98) both for Gd-EOB MRI and for Fast protocol (k range, 0.89–0.99).

Conclusion

Abbreviated protocol showed the same detection rate than conventional study in detection of liver metastases.

Abbreviated MRI for Hepatocellular Carcinoma Screening and Surveillance

To detect potentially curable hepatocellular carcinoma (HCC), clinical practice guidelines recommend semiannual surveillance US of the liver in adult patients at risk for developing this malignancy, such as those with cirrhosis and some patients with chronic hepatitis B infection. However, cirrhosis and a large body habitus, both of which are increasingly prevalent in the United States and the rest of the world, may impair US visualization of liver lesions and reduce the sensitivity of surveillance with this modality. The low sensitivity of US for detection of early-stage HCC contributes to delayed diagnosis and increased mortality. Abbreviated MRI, a shortened MRI protocol tailored for early-stage detection of HCC, has been proposed as an alternative surveillance option that provides high sensitivity and specificity. Abbreviated MRI protocols include fewer sequences than a complete multiphase MRI examination and are specifically designed to identify small potentially curable HCCs that may be missed at US. Three abbreviated MRI strategies have been studied: (a) nonenhanced, (b) dynamic contrast material-enhanced, and (c) hepatobiliary phase contrast-enhanced abbreviated MRI. Retrospective studies have shown that simulated abbreviated MRI provides high sensitivity and specificity for early-stage HCC, mostly in nonsurveillance cohorts. If it is supported by scientific evidence in surveillance populations, adoption of abbreviated MRI could advance clinical practice by increasing early detection of HCC, allowing effective treatment and potentially prolonging life in the growing number of individuals with this cancer. Online supplemental material is available for this article. ©RSNA, 2020.

Alternative approach of hepatocellular carcinoma surveillance: abbreviated MRI

This review focuses on emerging abbreviated magnetic resonance imaging (AMRI) surveillance of patients with chronic liver disease for hepatocellular carcinoma (HCC). This surveillance strategy has been proposed as a high-sensitivity alternative to ultrasound for identification of patients with early-stage HCC, particularly in patients with cirrhosis or obesity, in whom sonographic visualization of small tumors may be compromised. Three general AMRI approaches have been developed and studied in the literature - non-contrast AMRI, dynamic contrast-enhanced AMRI, and hepatobiliary phase contrast-enhanced AMRI - each comprising a small number of selected sequences specifically tailored for HCC detection. The rationale, general technique, advantages and disadvantages, and diagnostic performance of each AMRI approach is explained. Additionally, current gaps in knowledge and future directions are discussed. Based on emerging evidence, we cautiously recommend the use of AMRI for HCC surveillance in situations where ultrasound is compromised.

Imaging Modalities for Hepatocellular Carcinoma Surveillance: Expanding Horizons beyond Ultrasound

In Asian countries favoring loco-regional treatment such as surgical resection or ablation, very early-stage hepatocellular carcinoma (HCC) should be the main target for surveillance. Even though ultrasound (US) has been accepted as a primary imaging modality for HCC surveillance, its performance in detecting very early-stage HCCs is insufficient. Moreover, in more than 20% of patients at high risk for HCC, visualization of the liver on US may be limited owing to the advanced distortion and heterogeneity of the liver parenchyma. Recently revised HCC clinical guidelines allow the use of alternative surveillance tools including computed tomography or magnetic resonance imaging in patients with inadequate US exams. This paper summarizes the findings of recent studies using imaging modalities other than US as surveillance tools for HCC as well as strengths and limitations of these modalities.

Evaluation of non-contrast magnetic resonance imaging as an imaging surveillance tool for hepatocellular carcinoma in at-risk patients

INTRODUCTION

This study aimed to evaluate the potential of non-contrast enhanced magnetic resonance (MR) imaging as an imaging surveillance tool for hepatocellular carcinoma (HCC) detection in at-risk patients and to compare the performance of non-contrast MR imaging with ultrasonography (US) as a screening modality for the same.

METHODS

In this retrospective study, patients diagnosed with HCC between 1 January 2010 and 31 December 2015 were selected from our institution's cancer registry. Patients with MR imaging and US scanning performed within three months of the MR imaging were included. For each MR imaging, two non-contrast MR imaging sequences - T2-weighted fat-saturated sequence (T2w-FS) and diffusion-weighted imaging (DWI) - were reviewed for the presence of suspicious lesions. A non-contrast MR image was considered positive if the lesion was seen on both sequences. The performance of non-contrast MR imaging was compared to that of hepatobiliary US for the detection of HCC.

RESULTS

A total of 73 patients with 108 HCCs were evaluated. Sensitivity of non-contrast MR imaging for the detection of HCC using T2w-FS and DWI was 93.2%, which was significantly higher than that of US, at 79.5% (p = 0.02). In a subgroup of 55 patients with imaging features of liver cirrhosis, the sensitivity of non-contrast MR imaging was 90.9%, which was also significantly higher than US, at 74.5% (p = 0.02).

CONCLUSION

Our pilot study showed that non-contrast MR imaging, using a combination of T2w-FS and DWI, is a potential alternative to US as a screening tool for the surveillance of patients at risk for HCC.

Intraindividual Comparison between Gadoxetate-Enhanced Magnetic Resonance Imaging and Dynamic Computed Tomography for Characterizing Focal Hepatic Lesions: A Multicenter, Multireader Study

OBJECTIVE

To compare the diagnostic accuracy of dynamic computed tomography (CT) and gadoxetate-enhanced magnetic resonance imaging (MRI) for characterization of hepatic lesions by using the Liver Imaging Reporting and Data System (LI-RADS) in a multicenter, off-site evaluation.

MATERIALS AND METHODS

In this retrospective multicenter study, we evaluated 231 hepatic lesions (114 hepatocellular carcinomas [HCCs], 58 non-HCC malignancies, and 59 benign lesions) confirmed histologically in 217 patients with chronic liver disease who underwent both gadoxetate-enhanced MRI and dynamic CT at one of five tertiary hospitals. Four radiologists at different institutes independently reviewed all MR images first and the CT images 4 weeks later. They evaluated the major and ancillary imaging features and categorized each hepatic lesion according to the LI-RADS v2014. Diagnostic performance was calculated and compared using generalized estimating equations.

RESULTS

MRI showed higher sensitivity and accuracy than CT for diagnosing hepatic malignancies; the pooled sensitivities, specificities, and accuracies for categorizing LR-5/5V/M were 59.0% vs. 72.4% (CT vs. MRI; p < 0.001), 83.5% vs. 83.9% (p = 0.906), and 65.3% vs. 75.3% (p < 0.001), respectively. CT and MRI showed comparable capabilities for differentiating between HCC and other malignancies, with pooled accuracies of 79.9% and 82.4% for categorizing LR-M, respectively (p = 0.139).

CONCLUSION

Gadoxetate-enhanced MRI showed superior accuracy for categorizing LR-5/5V/M in hepatic malignancies in comparison with dynamic CT. Both modalities had comparable accuracies for distinguishing other malignancies from HCC.

Non-enhanced magnetic resonance imaging as a surveillance tool for hepatocellular carcinoma: Comparison with ultrasound

BACKGROUND & AIMS

Recently revised international guidelines for hepatocellular carcinoma (HCC) suggest that patients with inadequate ultrasonography be assessed by alternative imaging modalities. Non-enhanced MRI has potential as a surveillance tool based on the short scan times required and the absence of contrast agent-associated risks. This study compared the performance of non-enhanced MRI and ultrasonography for HCC surveillance in high-risk patients.

METHODS

We included 382 high-risk patients in a prospective cohort who underwent 1 to 3 rounds of paired gadoxetic acid-enhanced MRI and ultrasonography. Non-enhanced MRI, consisting of diffusion-weighted imaging (DWI) and T2-weighted imaging, was simulated and retrospectively analyzed, with results considered positive when lesion(s) ≥1 cm showed diffusion restriction or mild-moderate T2 hyperintensity. Ultrasonography results were retrieved from patient records. HCC was diagnosed histologically and/or radiologically. Sensitivity, positive predictive value (PPV), specificity, and negative predictive value (NPV) were evaluated using generalized estimating equations.

RESULTS

Forty-eight HCCs were diagnosed in 43 patients. Per-lesion and per-exam sensitivities of non-enhanced MRI were 77.1% and 79.1%, respectively, which were higher than those achieved with ultrasonography (25.0% and 27.9%, respectively, p <0.001). Specificities of non-enhanced MRI (97.9%) and ultrasonography (94.5%) differed significantly (p <0.001). NPV was higher for non-enhanced MRI (99.1%) than ultrasonography (96.9%). Per-lesion and per-exam PPVs were higher for non-enhanced MRI (56.9% and 61.8%, respectively) than for ultrasonography (16.7% and 17.7%, respectively). The estimated scan time of non-enhanced MRI was <6 min.

CONCLUSION

Based on its good performance, short scan times, and the lack of contrast agent-associated risks, non-enhanced MRI is a promising option for HCC surveillance in high-risk patients.

LAY SUMMARY

Recently revised international guidelines for hepatocellular carcinoma (HCC) suggest that selected patients with inadequate surveillance on ultrasonography be assessed by alternative imaging modalities such as computed tomography or magnetic resonance imaging (MRI). Herein, we show that MRI without contrast agents performed significantly better than ultrasonography for HCC surveillance in high-risk patients. Given this good performance, as well as short scan times and the lack of contrast agent-associated risks, non-enhanced MRI is a promising option for HCC surveillance in high-risk patients.

Comparison of diagnostic performance of non-contrast MRI and abbreviated MRI using gadoxetic acid in initially diagnosed hepatocellular carcinoma patients: a simulation study of surveillance for hepatocellular carcinomas

OBJECTIVE

This study was conducted in order to compare the diagnostic performance of noncontrast and abbreviated MRI using gadoxetic acid for detecting hepatocellular carcinoma (HCC) in initially diagnosed HCC patients.

METHODS

We identified 140 consecutive patients with newly diagnosed HCC (173 HCCs) within the Milan criteria, who underwent liver MRI using gadoxetic acid between 2015 and 2016. One hundred twenty-three consecutive patients without HCC who underwent liver MRI in the same period for HCC surveillance were enrolled for the control group. Two radiologists independently reviewed two MRI sets: a noncontrast set and an abbreviated set. The noncontrast set consists of T2 FSE/ssFSE, T1 in- and out-of-phase image, DWI, and the ADC map. The abbreviated set consists of T2 FSE/ssFSE, hepatobiliary phase image 20 min after gadoxetic acid injection, DWI, and the ADC map.

RESULTS

In a per-patient analysis, sensitivity of reviewer 1 for noncontrast and abbreviated sets was 85.7 and 90.0%, respectively. The specificity for both noncontrast and abbreviated sets was 92.7%. For reviewer 2, sensitivity of noncontrast and abbreviated sets was 86.4 and 89.3%, respectively. Per-patient specificity of reviewer 2 was 92.7% for both noncontrast and abbreviated sets. The sensitivity and specificity of two image sets were not significantly different for both reviewers. The per-tumor sensitivity of noncontrast and abbreviated sets was 81.5 and 84.4% for reviewer 1, respectively, and 79.8 and 84.4% for reviewer 2, respectively. There was no significant difference.

CONCLUSION

Noncontrast and abbreviated MRI using gadoxetic acid showed comparable diagnostic performance for detecting patients with HCCs in the early stage.

KEY POINTS

• Diagnostic performance of noncontrast MRI and abbreviated MRI using gadoxetic acid for detecting HCCs is comparable in patients with HCCs in the early stage. • Noncontrast MRI and abbreviated MRI showed high sensitivity and specificity for detecting HCCs in the early stage. • Outcomes of surveillance for HCC in high-risk patients can be improved by adopting these simplified and focused MRI protocols.

Diagnostic performance of a minimized protocol of non-contrast MRI for hepatocellular carcinoma surveillance

PURPOSE

To evaluate the per-patient diagnostic performance of a minimized non-contrast MRI protocol for hepatocellular carcinoma (HCC) surveillance in cirrhotic liver, as well as factors affecting diagnostic sensitivity.

METHODS

A total of 226 patients who underwent MRI for HCC surveillance over an 8 year period were included in this retrospective study. Set1 consisted of diffusion-weighted imaging and respiratory-triggered, fast-spin echo T2-weighted imaging with fat suppression. Set2 included T1-weighted in/opposed-phase images added to the images from Set1. Image sets were scored as positive or negative for HCC according to predetermined criteria by two readers independently. The diagnostic performance of the two sets in conjunction with α-fetoprotein (AFP) was assessed and compared using the McNemar test. Logistic regression was used to determine factors that affected sensitivity.

RESULTS

The sensitivity, specificity, and accuracy of Set1 of readers 1 and 2 were 84.4%/87.3%, 86.8%/86.8%, and 85.0%/87.2%, respectively; and those for Set2 were 87.3%/89.6%, 81.1%/79.2%, and 85.8/87.2%, respectively. The sensitivities of the sets were not significantly different (p = 0.063). Sensitivities of both sets in conjunction with AFP were higher than those of MRI alone without statistical significance (87.3%/89.6%, p = 0.063/> 0.99; 89.6%/89.6%, p = 0.125/> 0.99). In very early-stage HCC, the sensitivities of Sets1 and 2 were 73.1%/76.9% and 76.9%/82.7%, respectively. Perihepatic ascites and size less than 2 cm were associated with sensitivity (p < 0.05).

CONCLUSIONS

A minimized non-contrast MRI protocol consisting of Fat-sat T2WI and DWI is highly sensitive and may be a viable method for HCC surveillance of the cirrhotic liver. The inclusion of T1-weighted in/opposed-phase and AFP may increase this sensitivity.

Abbreviated MRI with optional multiphasic CT as an alternative to full-sequence MRI: LI-RADS validation in a HCC-screening cohort

OBJECTIVE

To compare the diagnostic performance of abbreviated MRI (AMRI) combined with multiphasic CT (mCT) with that of full-sequence gadoxetic acid-enhanced MRI (EOB-MRI) in a hepatocellular carcinoma (HCC)-screening cohort METHODS: Consecutive patients at risk of HCC who underwent EOB-MRI and mCT within 3 months for evaluation of new 0.5-3-cm hepatic observations were retrospectively recruited from 3 centers. An AMRI protocol comprising hepatobiliary phase, T2- and diffusion-weighted imaging, and dual-echo sequence was reconstituted from EOB-MRI. Two radiologists independently reviewed each observation in AMRI plus mCT (set 1) and EOB-MRI (set 2) per LI-RADS v2018. Per-lesion sensitivity, accuracy, and positive predictive value (PPV) for HCC were calculated and compared between image sets.

RESULTS

In 267 patients, 306 histologically confirmed observations (280 HCCs, 20 combined hepatocellular-cholangiocarcinomas, 1 cholangiocarcinoma, and 5 benignities) were assessed. Set 1 yielded higher sensitivity (96.4% vs. 92.9%, p = 0.013) and comparable accuracy (91.2% vs. 87.6%) and PPV (94.1% vs. 93.5%) to set 2 using LI-RADS category (LR)-4/5 criteria. The sets showed comparable sensitivity (66.4% vs. 70.4%), accuracy (67.7% vs. 70.6%), and PPV (97.4% vs. 96.6%) using LR-5 criteria. A similar substantial number of non-HCC malignancies were categorized as LR-4 or LR-5, as was the number of HCCs categorized as LR-M in both sets.

CONCLUSIONS

AMRI combined with mCT showed diagnostic performance similar or superior to that of EOB-MRI for HCC diagnosis using LI-RADS. Therefore, mCT holds potential as a sequential examination for HCC diagnosis in AMRI-detected hepatic observation in patients at risk of HCC.

KEY POINTS

• AMRI plus multiphasic CT showed comparable accuracy (91.2%) and PPV (94.1%) to full-sequence gadoxetic acid-enhanced MRI using LR-4/5 criteria. • AMRI plus multiphasic CT was significantly more sensitive than full-sequence gadoxetic acid-enhanced MRI (96.4% vs. 92.9%) using LR-4/5 criteria. • Multiphasic CT is a potential sequential modality for HCC diagnosis after AMRI.