Diffusion-weighted MRI of hepatocellular carcinoma in cirrhosis. Clin Radiol. 2014;69:1-10. [PMID: 24034549 DOI: 10.1016/j.crad.2013.07.022]

Abdominal Diffusion-Weighted MRI With Simultaneous Multi-Slice Acquisition: Agreement and Reproducibility of Apparent Diffusion Coefficients Measurements

BACKGROUND

Simultaneous multi-slice diffusion-weighted imaging (SMS-DWI) can shorten acquisition time in abdominal imaging.

PURPOSE

To investigate the agreement and reproducibility of apparent diffusion coefficient (ADC) from abdominal SMS-DWI acquired with different vendors and different breathing schemes.

STUDY TYPE

Prospective.

SUBJECTS

Twenty volunteers and 10 patients.

FIELD STRENGTH/SEQUENCE

3.0 T, SMS-DWI with a diffusion-weighted echo-planar imaging sequence.

ASSESSMENT

SMS-DWI was acquired using breath-hold and free-breathing techniques in scanners from two vendors, yielding four scans in each participant. Average ADC values were measured in the liver, pancreas, spleen, and both kidneys. Non-normalized ADC and ADCs normalized to the spleen were compared between vendors and breathing schemes.

STATISTICAL TESTS

Paired t-test or Wilcoxon signed rank test; intraclass correlation coefficient (ICC); Bland-Altman method; coefficient of variation (CV) analysis; significance level: P < 0.05.

RESULTS

Non-normalized ADCs from the four SMS-DWI scans did not differ significantly in the spleen (P = 0.262, 0.330, 0.166, 0.122), right kidney (P = 0.167, 0.538, 0.957, 0.086), and left kidney (P = 0.182, 0.281, 0.504, 0.405), but there were significant differences in the liver and pancreas. For normalized ADCs, there were no significant differences in the liver (P = 0.315, 0.915, 0.198, 0.799), spleen (P = 0.815, 0.689, 0.347, 0.423), pancreas (P = 0.165, 0.336, 0.304, 0.584), right kidney (P = 0.165, 0.336, 0.304, 0.584), and left kidney (P = 0.496, 0.304, 0.443, 0.371). Inter-reader agreements of non-normalized ADCs were good to excellent (ICCs ranged from 0.861 to 0.983), and agreement and reproducibility were good to excellent depending on anatomic location (CVs ranged from 3.55% to 13.98%). Overall CVs for abdominal ADCs from the four scans were 6.25%, 7.62%, 7.08, and 7.60%.

DATA CONCLUSION

The normalized ADCs from abdominal SMS-DWI may be comparable between different vendors and breathing schemes, showing good agreement and reproducibility. ADC changes above approximately 8% may potentially be considered as a reliable quantitative biomarker to assess disease or treatment-related changes.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY: Stage 2.

Quantitative diffusion weighted imaging in patients with hepatocellular carcinoma: effects of simultaneous multi-slice acceleration and gadoxetic acid administration

PURPOSE

To investigate whether simultaneous multi-slice (SMS) acceleration and gadoxetic acid administration affect the quantitative apparent diffusion coefficient (ADC) and signal-to-noise ratio (SNR) measurement of DWI in patients with HCC.

METHODS

This prospective study initially enrolled 208 patients with clinically suspected HCC. Free breathing SMS-DWI and conventional DWI (CON-DWI) were performed before and after gadoxetic acid administration. Lesion conspicuity, ADCs and SNRs of the HCC lesion and normal liver parenchyma were independently measured by two radiologists. The paired t test or Wilcoxon signed rank test was used to evaluate the differences of lesion conspicuity, ADCs and SNRs between SMS-DWI and CON-DWI, as well as those before and after gadoxetic acid administration.

RESULTS

A total of 102 HCC patients (90 men and 12 women; mean age, 54.6 ± 11.7 years) were finally included for analysis. SMS-DWI and CON-DWI demonstrated comparable lesion conspicuity (P = 0.081-0.566). For the influence of SMS acceleration, the SNRs of liver parenchyma on enhanced SMS-DWI were significantly higher than enhanced CON-DWI (P = 0.015). For the influence of gadoxetic acid administration, the mean ADCs were significantly higher on enhanced SMS-DWI than unenhanced SMS-DWI (HCC, P = 0.013; liver parenchyma, P = 0.032).

CONCLUSION

Quantitative ADC measurements of HCC and liver parenchyma were not affected by SMS acceleration, and SMS-DWI can provide higher SNR than CON-DWI. However, the ADC measurements can be affected by gadoxetic acid administration on SMS-DWI, so it is recommended to perform SMS-DWI before gadoxetic acid administration.

Diagnostic Accuracy of the Apparent Diffusion Coefficient for Microvascular Invasion in Hepatocellular Carcinoma: A Meta-analysis

BACKGROUND AND AIMS

Microvascular invasion (MVI) is a major risk factor for the early recurrence of hepatocellular carcinoma (HCC) and it seriously worsens the prognosis. Accurate preoperative evaluation of the presence of MVI could greatly benefit the treatment management and prognosis prediction of HCC patients. The study aim was to evaluate the diagnostic performance of the apparent diffusion coefficient (ADC), a quantitative parameter for the preoperative diagnosis MVI in HCC patients.

METHODS

Original articles about diffusion-weighted imaging (DWI) and/or intravoxel incoherent motion (IVIM) conducted on a 3.0 or 1.5 Tesla magnetic resonance imaging (MRI) system indexed through January 17, 2021were collected from MEDLINE/PubMed, Web of Science, EMBASE, and the Cochrane Library. Methodological quality was evaluated using Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2). The pooled sensitivity, specificity, and summary area under the receiver operating characteristic curve (AUROC) were calculated, and meta-regression analysis was performed using a bivariate random effects model through a meta-analysis.

RESULTS

Nine original articles with a total of 988 HCCs were included. Most studies had low bias risk and minimal applicability concerns. The pooled sensitivity, specificity and AUROC of the ADC value were 73%, 70%, and 0.78, respectively. The time interval between the index test and the reference standard was identified as a possible source of heterogeneity by subgroup meta-regression analysis.

CONCLUSIONS

Meta-analysis showed that the ADC value had moderate accuracy for predicting MVI in HCC. The time interval accounted for the heterogeneity.

Current Imaging Diagnosis of Hepatocellular Carcinoma

Simple Summary

The role of imaging in the management of hepatocellular carcinoma (HCC) has significantly evolved and expanded beyond the plain radiological confirmation of the tumor based on the typical appearance in a multiphase contrast-enhanced CT or MRI examination. The introduction of hepatobiliary contrast agents has enabled the diagnosis of hepatocarcinogenesis at earlier stages, while the application of ultrasound contrast agents has drastically upgraded the role of ultrasound in the diagnostic algorithms. Newer quantitative techniques assessing blood perfusion on CT and MRI not only allow earlier diagnosis and confident differentiation from other lesions, but they also provide biomarkers for the evaluation of treatment response. As distinct HCC subtypes are identified, their correlation with specific imaging features holds great promise for estimating tumor aggressiveness and prognosis. This review presents the current role of imaging and underlines its critical role in the successful management of patients with HCC.

Abstract

Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer related death worldwide. Radiology has traditionally played a central role in HCC management, ranging from screening of high-risk patients to non-invasive diagnosis, as well as the evaluation of treatment response and post-treatment follow-up. From liver ultrasonography with or without contrast to dynamic multiple phased CT and dynamic MRI with diffusion protocols, great progress has been achieved in the last decade. Throughout the last few years, pathological, biological, genetic, and immune-chemical analyses have revealed several tumoral subtypes with diverse biological behavior, highlighting the need for the re-evaluation of established radiological methods. Considering these changes, novel methods that provide functional and quantitative parameters in addition to morphological information are increasingly incorporated into modern diagnostic protocols for HCC. In this way, differential diagnosis became even more challenging throughout the last few years. Use of liver specific contrast agents, as well as CT/MRI perfusion techniques, seem to not only allow earlier detection and more accurate characterization of HCC lesions, but also make it possible to predict response to treatment and survival. Nevertheless, several limitations and technical considerations still exist. This review will describe and discuss all these imaging modalities and their advances in the imaging of HCC lesions in cirrhotic and non-cirrhotic livers. Sensitivity and specificity rates, method limitations, and technical considerations will be discussed.

Differentiation of small (≤ 3 cm) hepatocellular carcinomas from benign nodules in cirrhotic liver: the added additive value of MRI-based radiomics analysis to LI-RADS version 2018 algorithm

Background

Accurate characterization of small nodules in a cirrhotic liver is challenging. We aimed to determine the additive value of MRI-based radiomics analysis to Liver Imaging Reporting and Data System version 2018 (LI-RADS v 2018) algorithm in differentiating small (≤ 3 cm) hepatocellular carcinomas (HCCs) from benign nodules in cirrhotic liver.

Methods

In this retrospective study, 150 cirrhosis patients with histopathologically confirmed small liver nodules (HCC, 112; benign nodules, 44) were evaluated from January 2013 to October 2018. Based on the LI-RADS algorithm, a LI-RADS category was assigned for each lesion. A radiomics signature was generated based on texture features extracted from T1-weighted, T2W, and apparent diffusion coefficient (ADC) images by using the least absolute shrinkage and selection operator regression model. A nomogram model was developed for the combined diagnosis. Diagnostic performance was assessed using receiver operating characteristic curve (ROC) analysis.

Results

A radiomics signature consisting of eight features was significantly associated with the differentiation of HCCs from benign nodules. Both LI-RADS algorithm (area under ROC [A_z] = 0.898) and the MRI-Based radiomics signature (A_z = 0.917) demonstrated good discrimination, and the nomogram model showed a superior classification performance (A_z = 0.975). Compared with LI-RADS alone, the combined approach significantly improved the specificity (97.7% vs 81.8%, p = 0.030) and positive predictive value (99.1% vs 92.9%, p = 0.031) and afforded comparable sensitivity (97.3% vs 93.8%, p = 0.215) and negative predictive value (93.5% vs 83.7%, p = 0.188).

Conclusions

MRI-based radiomics analysis showed additive value to the LI-RADS v 2018 algorithm for differentiating small HCCs from benign nodules in the cirrhotic liver.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12876-021-01710-y.

Diffusion-Weighted Magnetic Resonance Imaging in Hepatocellular Carcinoma as a Predictor of a Response to Cisplatin-Based Hepatic Arterial Infusion Chemotherapy

This study aimed to identify the utility of diffusion-weighted magnetic resonance (MR) imaging with an apparent diffusion coefficient (ADC) map as a predictor of the response of hepatocellular carcinoma (HCC) to cisplatin-based hepatic arterial infusion chemotherapy (HAIC). We retrospectively evaluated 113 consecutive patients with Barcelona Clinical Liver Cancer (BCLC) stage B or C HCC, who underwent gadoxetic acid-enhanced and diffusion-weighted MR imaging. The appropriate cutoff for the pretreatment tumor-to-liver ADC ratio was determined to be 0.741. Of the 113 patients, 50 (44%) presented with a pretreatment tumor-to-liver ADC ratio < 0.741 (low group). Evaluation of the treatment response after 2-3 cycles of HAIC in these 50 patients revealed that 21 patients (42%) experienced an objective response to HAIC. On the other hand, only 11 of the 63 patients (17%) with a pretreatment tumor-to-liver ADC ratio ≥ 0.741 (high group) showed an objective response. Thus, the objective response rate was significantly higher in the low group than in the high group (P = 0.006). Multivariate logistic regression analysis using parameters including perfusion alteration, percentage of non-enhancing portions, and pretreatment tumor-to-liver ADC ratio revealed that a pretreatment tumor-to-liver ADC ratio < 0.741 (odds ratio 3.217; P = 0.014) was the sole predictor of an objective response to HAIC. Overall survival rates were significantly higher in patients with objective responses to HAIC than in those without objective responses (P = 0.001 by log-rank test). In conclusion, patients with BCLC stage C or C HCC with a pretreatment tumor-to-liver ADC ratio < 0.741 showed a favorable intrahepatic response to cisplatin-based HAIC. Therefore, diffusion-weighted MR imaging can play a critical role as a predictor of response to cisplatin-based HAIC in unresectable HCC.

Advances in the early diagnosis of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most prevalent cancers globally. In contrast to the declining death rates observed for all other common cancers such as breast, lung, and prostate cancers, the death rates for HCC continue to increase by ~2–3% per year because HCC is frequently diagnosed late and there is no curative therapy for an advanced HCC. The early diagnosis of HCC is truly a big challenge. Over the past years, the early diagnosis of HCC has relied on surveillance with ultrasonography (US) and serological assessments of alpha-fetoprotein (AFP). However, the specificity and sensitivity of US/AFP is not satisfactory enough to detect early onset HCC. Recent technological advancements offer hope for early HCC diagnosis. Herein, we review the progress made in HCC diagnostics, with a focus on emerging imaging techniques and biomarkers for early disease diagnosis.

A proposal for a useful algorithm to diagnose small hepatocellular carcinoma on MRI

OBJECTIVE

To assess MRI features for the diagnosis of small hepatocellular carcinomas (HCCs) and especially for nodules not showing both of the typical hallmarks.

PATIENTS AND METHODS

Three hundred and sixty-four cirrhotic patients underwent liver MRI for 10-30 mm nodules suggestive of HCC. The diagnostic performances of MRI features [T1, T2; diffusion-weighted (DW) imaging signal, enhancement, capsule, fat content] were tested, both individually and in association with both typical hallmarks and as substitutions for one hallmark. The diagnostic reference was obtained using a multifactorial algorithm ensuring high specificity (Sp).

RESULTS

Four hundred and ninety-three nodules were analyzed. No alternative features, associations or substitutions outperformed the typical hallmarks for the diagnosis of HCC. For 10-20 mm nodules not displaying one of the typical hallmarks, hyperintensity on DW images was the most accurate substitutive sign, providing a sensitivity of 71.4% and Sp of 75% for nodules without arterial enhancement and sensitivity = 65.2% and Sp = 66% for nodules without washout on the portal or delayed phases. A new diagnostic algorithm, including typical hallmarks as a first step then the best-performing substitutive signs (capsule presence or DW hyperintensity) in combination with the nonmissing typical hallmark as a second step, enabled the correct classification of 77.7% of all nodules, regardless of size.

CONCLUSION

Using MRI, the typical hallmarks remain the best criteria for the diagnosis of small HCCs. However, by incorporating other MRI features, it is possible to build a simple algorithm enabling the noninvasive diagnosis of HCCs displaying both or only one of the typical hallmarks.

Recent advances in non-invasive magnetic resonance imaging assessment of hepatocellular carcinoma

Magnetic resonance (MR) imaging of the liver is an important tool for the detection and characterization of focal liver lesions and for assessment of diffuse liver disease, having several intrinsic characteristics, represented by high soft tissue contrast, avoidance of ionizing radiation or iodinated contrast media, and more recently, by application of several functional imaging techniques (i.e., diffusion-weighted sequences, hepatobiliary contrast agents, perfusion imaging, magnetic resonance (MR)-elastography, and radiomics analysis). MR functional imaging techniques are extensively used both in routine practice and in the field of clinical and pre-clinical research because, through a qualitative rather than quantitative approach, they can offer valuable information about tumor tissue and tissue architecture, cellular biomarkers related to the hepatocellular functions, or tissue vascularization profiles related to tumor and tissue biology. This kind of approach offers in vivo physiological parameters, capable of evaluating physiological and pathological modifications of tissues, by the analysis of quantitative data that could be used in tumor detection, characterization, treatment selection, and follow-up, in addition to those obtained from standard morphological imaging. In this review we provide an overview of recent advanced techniques in MR for the diagnosis and staging of hepatocellular carcinoma, and their role in the assessment of response treatment evaluation.

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

Objective

To preliminarily evaluate the diagnostic performance of an unenhanced MRI for detecting hepatocellular carcinoma (HCC) with a case-control study design.

Materials and Methods

The case group consisted of 175 patients with initially-diagnosed HCC, who underwent a 3T liver MRI. A total of 237 HCCs were identified. The number of HCCs that were smaller than 1 cm, 1 cm ≤ and < 2 cm, and ≥ 2 cm were 19, 105, and 113, respectively. For the control group, 72 patients with chronic liver disease, who did not have HCC, were enrolled. Two radiologists independently reviewed the T2 half-Fourier acquisition single-shot turbo spin echo, T2 fast spin echos with fat saturation, T1 gradient in- and out-of-phase images, and diffusion-weighted images/apparent diffusion coefficient maps to detect HCC. Per-patient analyses were performed to evaluate the sensitivity and specificity of the non-contrast MRI for diagnosing HCC. Furthermore, the per-lesion sensitivity was also calculated according to tumor size.

Results

In the per-patient analyses, the sensitivity and specificity of reader 1 were 86.3% (151/175) and 87.5% (63/72), respectively; while those of reader 2 were 82.9% (145/175) and 76.4% (55/72), respectively. When excluding HCCs smaller than 1 cm, the sensitivity of reader 1 and 2 were 88.0% (147/167) and 86.2% (144/167), respectively. In the per-lesion analyses, the sensitivities of reader 1 and reader 2 were 75.9% (180/237) and 70.5% (167/237), respectively.

Conclusion

The per-patient sensitivity and specificity of non-contrast MRIs were within a reasonable range for the initial diagnosis of HCC. Non-contrast MRIs may have a potential for surveillance of HCC. Further confirmatory diagnostic test accuracy studies are needed.

Magnetic resonance imaging ancillary features used in Liver Imaging Reporting and Data System: An illustrative review

Hepatocellular carcinoma (HCC) usually develops in the setting of chronic liver disease. In the adequate clinical context, both multiphasic contrast-enhanced CT and magnetic resonance imaging are non-invasive modalities that allow accurate diagnosis and staging of HCC, although the latter demonstrates greater sensitivity and specificity. Imaging criteria for HCC diagnosis rely on hemodynamic features such as hyperenhancement in the arterial phase and washout in the portal or equilibrium phase. However, imaging performance drops considerably for small (< 20 mm) nodules because their tendency to exhibit atypical enhancement patterns. In order to improve accuracy in the diagnosis and staging of HCC, particularly in cases of atypical nodules, ancillary features, i.e., imaging characteristics that modify the likelihood of HCC, have been described and incorporated into clinical reports, especially in Liver Imaging Reporting and Data System. In this paper, ancillary imaging features will be reviewed and illustrated.

LI-RADS technical requirements for CT, MRI, and contrast-enhanced ultrasound

Accurate detection and characterization of liver observations to enable HCC diagnosis and staging using LI-RADS requires a technically adequate imaging exam. To help achieve this objective, LI-RADS has proposed technical requirements for CT, MR, and contrast-enhanced ultrasound of liver. This article reviews the technical requirements for liver imaging, including the description of minimum acceptable technical standards, such as the scanner hardware requirements, recommended dynamic imaging phases, and common technical challenges of liver imaging.

Comparison of biannual ultrasonography and annual non-contrast liver magnetic resonance imaging as surveillance tools for hepatocellular carcinoma in patients with liver cirrhosis (MAGNUS-HCC): a study protocol

Background

Ultrasonography (US) is recommended as a standard surveillance tool for patients with a high risk of developing hepatocellular carcinoma (HCC). However, the low sensitivity of US for small HCC can lead to surveillance failure, resulting in advanced stage tumor presentations. For the early detection of HCC in high-risk patients and to improve survival and prognosis, a new efficient imaging tool with a high sensitivity for HCC detection is needed. The purpose of this study is to evaluate and compare the feasibility and efficacy of non-contrast magnetic resonance imaging (MRI) with US as a surveillance tool for HCC in patients with liver cirrhosis.

Methods

MAGNUS-HCC is a prospective, multicenter clinical trial with a crossover design for a single arm of patients. This study was approved by six Institutional Review Boards, and informed consent was obtained from all participants. All patients will undergo liver US every 6 months and non-contrast liver MRI every 12 months during a follow-up period of 3 years. If a focal liver lesion suspected of harboring HCC is detected, dynamic liver computed tomography (CT) will be performed to confirm the diagnosis. After the last surveillance round, patients without suspicion of HCC or who are not diagnosed with HCC will be evaluated with a dynamic liver CT to exclude false-negative findings. The primary endpoint is to compare the rate of detection of HCC by US examinations performed at 6-month intervals with that of yearly non-contrast liver MRI studies during a 3-year follow-up. The secondary endpoint is the survival of the patients who developed HCC within the 3-year follow-up period.

Discussion

MAGNUS-HCC is the first study to compare the feasibility of non-contrast MRI with US as a surveillance tool for the detection of HCC in high-risk patients. We anticipate that the evidence presented in this study will establish the efficacy of non-contrast MRI as a surveillance tool for HCC in high-risk patients.

Trial registration

The date of trial registration (NCT02551250) in this study was September 15, 2015, and follow-up is still ongoing.

Diffusion Quantification in Body Imaging

Diffusion-weighted imaging (DWI) is increasingly incorporated into routine body magnetic resonance imaging protocols. DWI can assist with lesion detection and even in characterization. Quantitative DWI has exhibited promise in the discrimination between benign and malignant pathology, in the evaluation of the biologic aggressiveness, and in the assessment of the response to treatment. Unfortunately, inconsistencies in DWI acquisition parameters and analysis have hampered widespread clinical utilization. Focusing primarily on liver applications, this article will review the basic principles of quantitative DWI. In addition to standard mono-exponential fitting, the authors will discuss intravoxel incoherent motion and diffusion kurtosis imaging that involve more sophisticated approaches to diffusion quantification.

Prediction of microvascular invasion of hepatocellular carcinoma with preoperative diffusion-weighted imaging: A comparison of mean and minimum apparent diffusion coefficient values

The aim of the study was to investigate the value of preoperative diffusion-weighted imaging (DWI) in predicting microvascular invasion (MVI) of hepatocellular carcinoma (HCC), using and comparing mean and minimum apparent diffusion coefficient (ADC) values.Preoperative MR images of 318 patients with HCC confirmed by surgical pathology were retrospectively analyzed. All patients underwent preoperative DWI on a 1.5 Tesla MRI scanner. The mean and minimum ADC values of the tumors were measured. Interobserver agreements were assessed by the intraclass correlation coefficient (ICC). The ADC values were compared in HCCs between with and without MVI. ROC curves of ADC values were obtained and then compared in distinguishing HCCs with MVI from those without MVI.There were 211 HCCs with MVI and 107 HCCs without MVI. ICC for the measurements of the mean and minimum ADC values between both observers was 0.88 (95% CI 0.85 - 0.90) and 0.88 (95% CI 0.85 - 0.90), respectively. The mean and minimum ADC values of HCCs with MVI were lower than those of HCCs without MVI (P = .00, .00, respectively). With a cut-off value of 0.98 × 10 mm/s, the minimum ADC (MinADC) showed a sensitivity of 62.56% and a specificity of 65.42% in predicting MVI, whereas the mean ADC provided a sensitivity of 79.15% and a specificity of 50.47% with a cut-off value of 1.19 × 10 mm/s. No significant difference existed between MinADC and mean ADC for their diagnostic performances in the prediction of MVI (P = .48).DWI could preoperatively provide quantitative parameters for predicting MVI of HCC.

Small hepatocellular carcinomas displayed as a ring enhancing mass on arterial phase MRI in the chronically diseased liver

AIM

To assess the prevalence of arterial phase (AP) ring-enhancing small hepatocellular carcinomas (HCC) on magnetic resonance imaging (MRI); detail additional MRI features that enable HCC diagnosis; and examine arterial timing as one possible cause of this appearance.

MATERIALS AND METHODS

Patients undergoing HCC screening with both computed tomography (CT) and MRI within 40 days were examined at a single institution over a 7- year time period ending in 2013. From this initial group, small (1-3 cm), (AP) ring-enhancing HCC on MRI were studied.

RESULTS

From the initial group of 64 patients with 129 HCC, 20 patients with 78 HCCs had a small diameter with 32 (41%) having an AP ring at MRI. The mean age of this latter group was 63-years old, with the average tumour diameter of 1.9 cm. Histopathology and secondary imaging supported a diagnosis of HCC in 20 (100%) patients and 31 (97%) lesions. Most of the ringed lesions had early AP timing.

CONCLUSION

This study revealed a high prevalence (41%) of small, AP ring HCC with MRI. The use of other MRI sequences adds support in making the proper diagnosis with this appearance. Early AP timing may help create this pattern.

Comparison of diffusion-weighted imaging and T2-weighted single shot fast spin-echo: Implications for LI-RADS characterization of hepatocellular carcinoma

PURPOSE

To evaluate the performance of diffusion-weighted imaging (DWI) and T2-weighted single shot fast spin-echo (SSFSE) imaging of the liver in the detection of hepatocellular carcinoma (HCC) in reference to the LI-RADS classification system.

METHODS

MR images of 40 patients with 68 LI-RADS grade 3-5 lesions were analyzed. Two readers independently reviewed sequences and characterized lesion signal intensity, followed by consensus evaluation. CE-MRI served as reference standard. Sensitivities were compared across sequences. Lesion-to-liver contrast-to-noise ratios (CNRs) and apparent diffusion coefficients (ADCs) were measured and compared using the Wilcoxon signed-rank test across sequences and the Mann-Whitney U or Kruskal-Wallis test between LI-RADS categories. Inter-reader variability was assessed using Cohen's kappa statistic.

RESULTS

Consensus sensitivities of LI-RADS 3-5 lesions using SSFSE images versus DWI were similar (0.53-0.63, p=0.089), however, the sensitivity with DWI b=700 was higher (0.63) than DWI b=0 (0.53, p=0.039). Lesion-to-liver CNRs were larger for all DWI sequences compared to SSFSE images (p<0.001 for all). ADCs of large (>2cm) LIRADS 3-5 lesions were lower than those of small lesions (1.09±0.33 vs. 1.31±0.26, p=0.02), however lesion ADCs were not different from those of adjacent hepatic parenchyma for any LI-RADS lesion.

CONCLUSIONS

DWI has a similar sensitivity compared to SSFSE, but intensity on DWI likely represents intrinsic T2 signal hyper-intensity rather than restricted diffusion as the ADC values were not lower than adjacent parenchyma. Therefore it may not be appropriate to consider hyper-intensity on high b-value as a separate ancillary criteria to T2 hyper-intensity in LI-RADS.

Comparison of MRI features of pathologically proven hepatocellular carcinoma between patients with hepatitis B and hepatitis C infection

PURPOSE

To compare MRI features of pathologically-proven hepatocellular carcinoma (HCC) between patients with hepatitis B (HBV) and hepatitis C (HCV) infection.

METHODS

Two radiologists assessed 51 confirmed HCCs on MRI in HBV (n=18) or HCV (n=33) patients; a third, more experienced, radiologist resolved discrepancies.

RESULTS

Arterial hyperenhancement occurred more frequently in HCV (90.9% vs. 66.7%; P=.032), DWI/T2WI hyperintensity more frequently in HBV [(DWI: 78.6% vs. 45.8%, T2WI: 77.8% vs. 48.5%; P=.073-0.088)]. Tumors were larger in HBV (P≤.016). Washout, pseudocapsule, homogeneity, circumscribed margins, lipid, iron, and visually low ADC were not different.

CONCLUSION

Larger studies are required to confirm these preliminary findings.

Effect of MRI Versus MDCT on Milan Criteria Scores and Liver Transplantation Eligibility

OBJECTIVE

The Milan criteria for the selection of patients with hepatocellular carcinoma (HCC) for liver transplantation were originally based on the findings of contrast-enhanced CT examinations. Studies have shown improvement in HCC detection of using contrast-enhanced MRI instead of CT, but they have provided little information on the potential downstream effect on patient management that might result from discrepant imaging findings. We sought to assess the effect of discrepant imaging findings on patient eligibility to undergo liver transplantation.

MATERIALS AND METHODS

From 2006 to 2013, patients with a diagnosis of HCC who underwent both MDCT and MRI examinations within a 40-day period were studied retrospectively. All examinations were independently reviewed by two abdominal radiologists who recorded the number, diameter, and location of each lesion. Secondary confirmation of the lesions was made on the basis of histopathologic findings, diffusion restriction on DWI, increased T2 signal intensity, lesion growth, presence of fat, uptake of ethiodized oil, or a combination of these findings.

RESULTS

Sixty-four patients (48 men and 16 women; mean age, 62 years) met the criteria for inclusion in the study. Of the 129 lesions identified by MRI, only 102 of these lesions (79%) were identified by MDCT. This discrepancy led to a difference in the Milan criteria scoring for nine patients (14%). There was no statistically significant difference in the mean (± SD) greatest lesion diameter measured using the two modalities, with measurements of 3.52 ± 2.8 cm and 3.46 ± 2.8 cm noted on MDCT and MRI, respectively (p = 0.8). Lesions missed on MDCT studies tended to be smaller, with a mean diameter of 2.7 cm. Of the 129 lesions identified by MRI, 112 (87%) had available histopathologic findings or other confirmatory diagnostic evidence.

CONCLUSION

MDCT missed one-fifth of the HCC lesions detected by MRI. Had MDCT been the only imaging examination performed, failure to identify these lesions would have led to a different management plan for 14% of patients.

Imaging of HCC-Current State of the Art

Early diagnosis of hepatocellular carcinoma (HCC) is crucial for optimizing treatment outcome. Ongoing advances are being made in imaging of HCC regarding detection, grading, staging, and also treatment monitoring. This review gives an overview of the current international guidelines for diagnosing HCC and their discrepancies as well as critically summarizes the role of magnetic resonance imaging (MRI) and computed tomography (CT) techniques for imaging in HCC. The diagnostic performance of MRI with nonspecific and hepatobililiary contrast agents and the role of functional imaging with diffusion-weighted imaging will be discussed. On the other hand, CT as a fast, cheap and easily accessible imaging modality plays a major role in the clinical routine work-up of HCC. Technical advances in CT, such as dual energy CT and volume perfusion CT, are currently being explored for improving detection, characterization and staging of HCC with promising results. Cone beam CT can provide a three-dimensional analysis of the liver with tumor and vessel characterization comparable to cross-sectional imaging so that this technique is gaining an increasing role in the peri-procedural imaging of HCC treated with interventional techniques.

The Fontan circulation and the liver: A magnetic resonance diffusion-weighted imaging study

BACKGROUND

Patients with a Fontan circulation tend to develop liver fibrosis, liver cirrhosis and even hepatocellular carcinoma. The aim of this study is to use the magnetic resonance technique diffusing-weighted imaging (DWI) for detecting liver fibrosis/cirrhosis in Fontan patients and to establish whether DWI results are associated with functional aspects of the Fontan circulation.

METHODS

In a cross-sectional study, 59 Fontan patients were evaluated by liver DWI. The association between apparent diffusion coefficients (ADC) and patient characteristics, laboratory measurements and functional aspects of the Fontan circulation (NYHA class, maximum oxygen uptake during exercise and cardiac index) was assessed.

RESULTS

Liver ADC values were low (0.82×10(-3)±0.11×10(-3) mm2/s) compared with literature values for healthy volunteers and correlated negatively with calculated liver fibrosis/cirrhosis scores (Fib-4 score, p=0.019; AST/ALT ratio, p=0.009) and gamma-glutamyl transferase (p=0.001). Furthermore, ADC values correlated negatively with follow-up duration (p<0.001) and positively with cardiac index (p=0.019). No correlation between ADC values and exercise tests was found. In multivariable analysis, the ADC values were independently correlated with follow-up duration after Fontan completion.

CONCLUSIONS

The results of the current study suggest that progressive liver damage due to chronic congestion and potential hypoperfusion is reflected in the liver ADC values in Fontan patients. This study highlights that liver damage in the context of the Fontan circulation might be far more common than previously thought, and that the implementation of liver assessment in the routine follow-up of Fontan patients is recommendable.

Contrast Enhanced MRI in the Diagnosis of HCC

Hepatocellular carcinoma (HCC) is the 6th most common cancer worldwide. Imaging plays a critical role in HCC screening and diagnosis. Initial screening of patients at risk for HCC is performed with ultrasound. Confirmation of HCC can then be obtained by Computed Tomography (CT) or Magnetic Resonance Imaging (MRI), due to the relatively high specificity of both techniques. This article will focus on reviewing MRI techniques for imaging HCC, felt by many to be the exam of choice for HCC diagnosis. MRI relies heavily upon the use of gadolinium-based contrast agents and while primarily extracellular gadolinium-based contrast agents are used, there is an emerging role of hepatobiliary contrast agents in HCC imaging. The use of other non-contrast enhanced MRI techniques for assessing HCC will also be discussed and these MRI strategies will be reviewed in the context of the pathophysiology of HCC to help understand the MR imaging appearance of HCC.

Prognostication and response assessment in liver and pancreatic tumors: The new imaging

Diffusion-weighted imaging (DWI), dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and perfusion computed tomography (CT) are technical improvements of morphologic imaging that can evaluate functional properties of hepato-bilio-pancreatic tumors during conventional MRI or CT examinations. Nevertheless, the term “functional imaging” is commonly used to describe molecular imaging techniques, as positron emission tomography (PET) CT/MRI, which still represent the most widely used methods for the evaluation of functional properties of solid neoplasms; unlike PET or single photon emission computed tomography, functional imaging techniques applied to conventional MRI/CT examinations do not require the administration of radiolabeled drugs or specific equipments. Moreover, DWI and DCE-MRI can be performed during the same session, thus providing a comprehensive “one-step” morphological and functional evaluation of hepato-bilio-pancreatic tumors. Literature data reveal that functional imaging techniques could be proposed for the evaluation of these tumors before treatment, given that they may improve staging and predict prognosis or clinical outcome. Microscopic changes within neoplastic tissues induced by treatments can be detected and quantified with functional imaging, therefore these techniques could be used also for post-treatment assessment, even at an early stage. The aim of this editorial is to describe possible applications of new functional imaging techniques apart from molecular imaging to hepatic and pancreatic tumors through a review of up-to-date literature data, with a particular emphasis on pathological correlations, prognostic stratification and post-treatment monitoring.

Role of diffusion-weighted imaging, apparent diffusion coefficient and correlation with hepatobiliary phase findings in the differentiation of hepatocellular carcinoma from dysplastic nodules in cirrhotic liver

OBJECTIVES

To investigate the utility of diffusion-weighted imaging (DWI), apparent diffusion coefficient (ADC) and the correlation with hepatobiliary phase (delayed phase imaging, DPI) findings in the differentiation of cirrhotic hepatocellular nodules.

METHODS

Forty-three patients with 53 pathology-proven nodules (29 hepatocellular carcinomas (HCCs), 13 high-grade (HGDNs) and 11 low-grade dysplastic nodules (LGDNs); mean size 2.17 cm, range 1-4 cm), who underwent liver MRI with DWI and DPI sequences, were retrospectively reviewed. Lesions were classified as hypointense, isointense, or hyperintense relative to the adjacent liver parenchyma. ADC of each nodule, of the surrounding parenchyma, and lesion-to-liver ratio were calculated.

RESULTS

Hyperintensity versus iso/hypointensity on DWI, hypointensity versus iso/hyperintensity on DPI, and the mean lesion-to-liver ratio showed a statistically significant difference both between HCCs versus DNs and between "HCCs + HGDNs" versus LGDNs (p < 0.05); sensitivity, specificity, and accuracy for the diagnosis of "HCCs + HGDNs" were 96.8 %, 100 %, 97.4 % respectively when combining hyperintensity on DWI and hypointensity on DPI, and 90.9 %, 81.0 %, 83.6 % respectively when lesion-to-liver ratio was <0.95.

CONCLUSIONS

Hyperintensity on DWI, especially in association with hypointensity on DPI, and low lesion-to-liver ratios should raise the suspicion of HCC, or at least of HGDN, thus helping the characterization of atypically enhancing lesions.

KEY POINTS

• Usefulness of DWI and ADC is shown in differential diagnosis of cirrhotic nodules. • Correlation of DWI with DPI improves differential diagnosis of cirrhotic nodules. • Characterization of atypically enhancing lesions becomes more confident.

Preoperative evaluation of the histological grade of hepatocellular carcinoma with diffusion-weighted imaging: a meta-analysis

OBJECTIVE

To evaluate the diagnostic performance of diffusion-weighted imaging (DWI) in the preoperative prediction of the histological grade of hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

A comprehensive literature search was performed in several authoritative databases to identify relevant articles. QUADAS-2 was used to assess the quality of included studies. Data were extracted to calculate the pooled sensitivity, specificity, positive likelihood ratio (PLR) and negative likelihood ratio (NLR). Summary receiver operating characteristic (SROC) curves were derived and areas under the SROC curve (AUC) were computed to indicate the diagnostic accuracy. Heterogeneity test, meta-regression analysis and sensitivity analysis were performed to identify factors and studies contributed to the heterogeneity.

RESULTS

A total of 11 studies with 912 HCCs were included in this meta-analysis. The pooled sensitivity, specificity, PLR and NLR with corresponding 95% confidence intervals (CI) were 0.54(0.47-0.61), 0.90(0.87-0.93), 4.88(2.99-7.97) and 0.46(0.27-0.77) for the prediction of well-differentiated HCC (w-HCC), 0.84(0.78-0.89), 0.48(0.43-0.52), 2.29(1.43-3.69) and 0.30(0.22-0.41) for the prediction of poorly-differentiated HCC (p-HCC). The AUC were 0.9311 and 0.8513 in predicting w-HCC and p-HCC, respectively. Results were further evaluated according to the method of image interpretation. Significant heterogeneity was observed.

CONCLUSION

DWI had excellent and moderately high diagnostic accuracy for the detection of w-HCC and p-HCC, respectively. Nonetheless, further studies in larger populations and an optimized image acquisition and interpretation are required before DWI-derived parameters can be used as a useful image biomarker for the prediction of the histological grade of HCC.

Diffusion-weighted imaging of the liver: techniques and applications

Diffusion-weighted imaging (DWI) is a technique that assesses the cellularity, tortuosity of the extracellular/extravascular space, and cell membrane density based on differences in water proton mobility in tissues. The strength of the diffusion weighting is reflected by the b value. DWI using several b values enables the quantification of the apparent diffusion coefficient. DWI is increasingly used in liver imaging for multiple reasons: it can add useful qualitative and quantitative information to conventional imaging sequences; it is acquired relatively quickly; it is easily incorporated into existing clinical protocols; and it is a noncontrast technique.