Detection and characterization of focal liver lesions: a Japanese phase III, multicenter comparison between gadoxetic acid disodium-enhanced magnetic resonance imaging and contrast-enhanced computed tomography predominantly in patients with hepatocellular carcinoma and chronic liver disease. Invest Radiol. 2010;45:133-141. [PMID: 20098330 DOI: 10.1097/rli.0b013e3181caea5b]

Diagnostic Imaging of the Hepatobiliary System: An Update

Recent advances in diagnostic imaging of the hepatobiliary system include MRI, computed tomography (CT), contrast-enhanced ultrasound, and ultrasound elastography. With the advent of multislice CT scanners, sedated examinations in veterinary patients are feasible, increasing the utility of this imaging modality. CT and MRI provide additional information for dogs and cats with hepatobiliary diseases due to lack of superimposition of structures, operator dependence, and through intravenous contrast administration. Advanced ultrasound methods can offer complementary information to standard ultrasound imaging. These newer imaging modalities assist clinicians by aiding diagnosis, prognostication, and surgical planning.

Added Value of Contrast-Enhanced Ultrasound on Biopsies of Focal Hepatic Lesions Invisible on Fusion Imaging Guidance

Objective

To assess whether contrast-enhanced ultrasonography (CEUS) with Sonazoid can improve the lesion conspicuity and feasibility of percutaneous biopsies for focal hepatic lesions invisible on fusion imaging of real-time ultrasonography (US) with computed tomography/magnetic resonance images, and evaluate its impact on clinical decision making.

Materials and Methods

The Institutional Review Board approved this retrospective study. Between June 2013 and January 2015, 711 US-guided percutaneous biopsies were performed for focal hepatic lesions. Biopsies were performed using CEUS for guidance if lesions were invisible on fusion imaging. We retrospectively evaluated the number of target lesions initially invisible on fusion imaging that became visible after applying CEUS, using a 4-point scale. Technical success rates of biopsies were evaluated based on histopathological results. In addition, the occurrence of changes in clinical decision making was assessed.

Results

Among 711 patients, 16 patients (2.3%) were included in the study. The median size of target lesions was 1.1 cm (range, 0.5–1.9 cm) in pre-procedural imaging. After CEUS, 15 of 16 (93.8%) focal hepatic lesions were visualized. The conspicuity score was significantly increased after adding CEUS, as compared to that on fusion imaging (p < 0.001). The technical success rate of biopsy was 87.6% (14/16). After biopsy, there were changes in clinical decision making for 11 of 16 patients (68.8%).

Conclusion

The addition of CEUS could improve the conspicuity of focal hepatic lesions invisible on fusion imaging. This dual guidance using CEUS and fusion imaging may affect patient management via changes in clinical decision-making.

Performance of Gadoxetic Acid-Enhanced Liver Magnetic Resonance Imaging for Predicting Patient Eligibility for Liver Transplantation Based on the Milan Criteria

PURPOSE

This study aimed to evaluate the accuracy of gadoxetic acid-enhanced magnetic resonance imaging (Gd-EOB-MRI) in predicting eligibility for liver transplantation in patients with hepatocellular carcinoma (HCC) based on Milan criteria (MC).

MATERIALS AND METHODS

We reviewed Gd-EOB-MRI of 44 patients who underwent liver transplantation for HCC with cirrhosis for the presence/size of HCCs, vascular invasion, and transplant eligibility based on MC. Hepatocellular carcinoma was diagnosed based on conventional radiological hallmarks (arterial enhancement and washout) or the modified criteria.

RESULTS

Among 44 patients, 16 was beyond MC. Sensitivity, specificity, and accuracy of conventional radiological hallmark and the modified criteria for predicting eligibility by MC were 31.3%, 96.3%, and 72.7%, and 68.8%, 96.3%, and 86.4%, respectively.

CONCLUSIONS

Gd-EOB-MRI showed high specificity but poor sensitivity for assessing transplant eligibility based on MC when adopting the conventional radiological hallmarks of HCC. Our modified criteria showed significantly better sensitivity and accuracy than the conventional radiological hallmarks.

Fusion imaging of contrast-enhanced ultrasound and contrast-enhanced CT or MRI before radiofrequency ablation for liver cancers

OBJECTIVE

To investigate the usefulness of fusion imaging of contrast-enhanced ultrasound (CEUS) and CECT/CEMRI before percutaneous ultrasound-guided radiofrequency ablation (RFA) for liver cancers.

METHODS

45 consecutive patients with 70 liver lesions were included between March 2013 and October 2015, and all the lesions were identified on CEMRI/CECT prior to inclusion in the study. Planning ultrasound for percutaneous RFA was performed using conventional ultrasound, ultrasound-CECT/CEMRI and CEUS and CECT/CEMRI fusion imaging during the same session. The numbers of the conspicuous lesions on ultrasound and fusion imaging were recorded. RFA was performed according to the results of fusion imaging. Complete response (CR) rate was calculated and the complications were recorded.

RESULTS

On conventional ultrasound, 25 (35.7%) of the 70 lesions were conspicuous, whereas 45 (64.3%) were inconspicuous. Ultrasound-CECT/CEMRI fusion imaging detected additional 24 lesions thus increased the number of the conspicuous lesions to 49 (70.0%) (70.0% vs 35.7%; p < 0.001 in comparison with conventional ultrasound). With the use of CEUS and CECT/CEMRI fusion imaging, the number of the conspicuous lesions further increased to 67 (95.7%, 67/70) (95.7% vs 70.0%, 95.7% vs 35.7%; both p < 0.001 in comparison with ultrasound and ultrasound-CECT/CEMRI fusion imaging, respectively). With the assistance of CEUS and CECT/CEMRI fusion imaging, the confidence level of the operator for performing RFA improved significantly with regard to visualization of the target lesions (p = 0.001). The CR rate for RFA was 97.0% (64/66) in accordance to the CECT/CEMRI results 1 month later. No procedure-related deaths and major complications occurred during and after RFA.

CONCLUSION

Fusion of CEUS and CECT/CEMRI improves the visualization of those inconspicuous lesions on conventional ultrasound. It also facilitates improvement in the RFA operators' confidence and CR of RFA. Advances in knowledge: CEUS and CECT/CEMRI fusion imaging is better than both conventional ultrasound and ultrasound-CECT/CEMRI fusion imaging for lesion visualization and improves the operator confidence, thus it should be recommended to be used as a routine in ultrasound-guided percutaneous RFA procedures for liver cancer.

Biliary tract enhancement in gadoxetic acid-enhanced MRI correlates with liver function biomarkers

PURPOSE

To evaluate the association between gadoxetic-acid-enhanced magnetic resonance (MR) imaging measurements and laboratory and clinical biomarkers of liver function and fibrosis.

MATERIALS AND METHODS

One hundred thirty nine consecutive patients with suspected liver disease or liver tumor underwent gadoxetic-acid-enhanced MR imaging. MR imaging measurements during the hepatobiliary phase included biliary tract structure-to-muscle signal intensity ratio (SIR). These measurements were compared with Child-Pugh classification, end-stage liver disease (MELD) score, and aspartate aminotransferase-to-platelet ratio index (APRI).

RESULTS

The SIRs of cystic duct and common bile duct were significantly correlated with Child-Pugh classification (P=0.012 for cystic duct and P<0.0001 for common bile duct), MELD score (P=0.0016 and P=0.0033), and APRI (P=0.0022 and P=0.0015). The sensitivity, specificity, and area under the receiver-operating-characteristic curve were: (74%, 88%, 0.86) with the SIR of common bile duct for the detection of patients with Child-Pugh class B or C; (100%, 87%, 0.94) with the SIR of cystic duct for MELD score (>10); (65%, 76%, 0.70) with the SIR of common bile duct for APRI (>1.5).

CONCLUSION

Gadoxetic-acid contrast enhancement of cystic duct and common bile duct could be used as biomarkers to assess liver function.

Diagnostic performance of gadoxetic acid (Primovist)-enhanced MR imaging versus CT during hepatic arteriography and portography for small hypervascular hepatocellular carcinoma

To compare the diagnostic performance of gadoxetic acid-enhanced magnetic resonance imaging (MRI) with that of computed tomography (CT) during hepatic arteriography and arterial portography (CT HA/AP) for detecting hepatocellular carcinoma (HCC) from small hypervascular nodules.This retrospective study included 38 patients with 131 hypervascular nodules (≤2 cm) who had underwent MRI and CT HA/AP within a 2-week interval. Two observers analyzed MRI while other 2 observers analyzed CT HA/AP. Thereafter, MRI observers reviewed the CT HA/AP and magnetic resonance (MR) images again using both modalities. HCC was diagnosed by pathologic or imaging studies according to American Association for the Study of Liver Diseases (AASLD) criteria. Alternative free-response receiver operating characteristic (ROC) analysis was performed on a lesion-by-lesion basis. Diagnostic accuracy (area under the ROC curve [Az]), sensitivity, specificity, and positive and negative predictive values were calculated.The pooled Az was significantly higher for the combined modalities (0.946) than for MRI alone (0.9, P = 0.004), and for MRI than for CT HA/AP alone (0.827, P = 0.0154). Subgroup analysis for HCC ≤1 cm showed the sensitivity of the combined modalities (79.4%) was significantly higher than for MRI (52.9%) and CT HA/AP alone (50%) (both, P < 0.005). The specificity of the combined modalities was not different from MRI alone (98.8% vs. 97.3%, P = 0.5), but was significantly higher than for CT HA/AP alone (98.8% vs. 92.5%, P = 0.022).Hypervascular HCCs >1 to 2 cm can be diagnosed sufficiently by MRI. The combined modalities increased the diagnostic accuracy of HCCs ≤1 cm, compared with MRI or CT HA/AP alone.

Gadoxetic acid-enhanced magnetic resonance imaging for the detection of small hepatocellular carcinoma (≤ 2.0 cm) in patients with chronic liver disease: A meta-analysis

AIM

To perform a meta-analysis assessing the value of gadoxetic acid-enhanced magnetic resonance imaging (Gd-EOB-MRI) in detecting small hepatocellular carcinoma (HCC) (≤ 2.0 cm) in patients with chronic liver disease.

METHODS

Databases, including MEDLINE and EMBASE, were searched for relevant original articles published from January 2008 to February 2015. Data were extracted, and summary estimates of diagnostic accuracy indexes such as sensitivity, specificity, diagnostic odds ratio, predictive value, and areas under summary receiver operating characteristic curve were obtained using a random-effects model, with further exploration employing meta-regression and subgroup analyses.

RESULTS

In 10 studies evaluating 768 patients, pooled per-lesion sensitivity of Gd-EOB-DTPA was 91% (95%CI: 83%-95%), with a specificity of 95% (95%CI: 87%-98%). Overall positive likelihood ratio was 18.1 (95%CI: 6.6-49.4), for negative likelihood ratio (NLR) of 0.10 (95%CI: 0.05-0.19) and diagnostic odds ratio of 182 (95%CI: 57-581). Subgroup analysis suggested that diagnostic performance of Gd-EOB-MRI for sub-centimeter HCC (≤ 1.0 cm) detection was low, with a sensitivity of 69% (95%CI: 59%-78%). In studies with both Gd-EOB-MRI and diffusion-weighted imaging (DWI) performed, Gd-EOB-MRI/DWI combination was more sensitive than Gd-EOB-DTPA alone, whether for small lesions (86% vs 77%) or sub-centimeter ones (80% vs 56%).

CONCLUSION

A limited number of small studies suggested that Gd-EOB-MRI has good diagnostic performance in the detection of small HCC (≤ 2.0 cm) among patients with chronic liver disease, but relatively lower performance for detection of sub-centimeter HCC (≤ 1.0 cm). Combination of Gd-EOB-MRI and DWI can improve the diagnostic sensitivity of MRI.

Magnetic Resonance Imaging of Liver Metastasis

Liver magnetic resonance imaging (MRI) is becoming the gold standard in liver metastasis detection and treatment response assessment. The most sensitive magnetic resonance sequences are diffusion-weighted images and hepatobiliary phase images after Gd-EOB-DTPA. Peripheral ring enhancement, diffusion restriction, and hypointensity on hepatobiliary phase images are hallmarks of liver metastases. In patients with normal ultrasonography, computed tomography (CT), and positron emission tomography (PET)-CT findings and high clinical suspicion of metastasis, MRI should be performed for diagnosis of unseen metastasis. In melanoma, colon cancer, and neuroendocrine tumor metastases, MRI allows confident diagnosis of treatment-related changes in liver and enables differential diagnosis from primary liver tumors. Focal nodular hyperplasia-like nodules in patients who received platinum-based chemotherapy, hypersteatosis, and focal fat can mimic metastasis. In cancer patients with fatty liver, MRI should be preferred to CT. Although the first-line imaging for metastases is CT, MRI can be used as a problem-solving method. MRI may be used as the first-line method in patients who would undergo curative surgery or metastatectomy. Current limitation of MRI is low sensitivity for metastasis smaller than 3mm. MRI fingerprinting, glucoCEST MRI, and PET-MRI may allow simpler and more sensitive diagnosis of liver metastasis.

A pH-activatable nanoparticle with signal-amplification capabilities for non-invasive imaging of tumour malignancy

Engineered nanoparticles that respond to pathophysiological parameters, such as pH or redox potential, have been developed as contrast agents for the magnetic resonance imaging (MRI) of tumours. However, beyond anatomic assessment, contrast agents that can sense these pathological parameters and rapidly amplify their magnetic resonance signals are desirable because they could potentially be used to monitor the biological processes of tumours and improve cancer diagnosis. Here, we report an MRI contrast agent that rapidly amplifies magnetic resonance signals in response to pH. We confined Mn(2+) within pH-sensitive calcium phosphate (CaP) nanoparticles comprising a poly(ethylene glycol) shell. At a low pH, such as in solid tumours, the CaP disintegrates and releases Mn(2+) ions. Binding to proteins increases the relaxivity of Mn(2+) and enhances the contrast. We show that these nanoparticles could rapidly and selectively brighten solid tumours, identify hypoxic regions within the tumour mass and detect invisible millimetre-sized metastatic tumours in the liver.

Evaluation of combined Gd-EOB-DTPA and gadobutrol magnetic resonance imaging for the prediction of hepatocellular carcinoma grading

BACKGROUND

Tumor biopsy is not essential for the diagnosis of hepatocellular carcinoma (HCC); however, grading remains important for the prognosis.

PURPOSE

To investigate whether combined Gd-EOB-DTPA and gadobutrol liver magnetic resonance imaging (MRI) can predict HCC grading.

MATERIAL AND METHODS

Thirty patients (66.6 ± 7.3 years) with histologically confirmed HCC (grade 1, n = 5; grade 1-2, n = 6; grade 2, n = 13; grade 2-3, n = 2; grade 3, n = 4) underwent two liver MRIs, one with gadobutrol and one with Gd-EOB-DTPA, on consecutive days. Blinded to grading, two radiologists reviewed the gadobutrol and Gd-EOB-DTPA images in consensus with respect to: (i) HCC hyper-/iso-/hypointensity in the arterial, portal-venous/delayed, and Gd-EOB-DTPA hepatocellular phase; and (ii) morphologic tumor features (encapsulated growth, vessel invasion, heterogeneity, liver capsule infiltration, satellite metastases).

RESULTS

A significant correlation with grading was not found for either the combined dynamic information of all gadobutrol phases (r = -0.187, P = 0.331) or all the Gd-EOB-DTPA phases (r = 0.052, P = 0.802). No correlation with grading was found for a combination of arterial and hepatocellular phase in Gd-EOB-DTPA MRI (r = 0.209, P = 0.305), a combination of both arterial phases (gadobutrol and Gd-EOB-DTPA) with the Gd-EOB-DTPA hepatocellular phase (r = 0.240, P = 0.248), or a combination of all available gadobutrol and Gd-EOB-DTPA phases (r = 0.086, P = 0.691). For all gadobutrol information (dynamic phases and morphology; r = 0.049, P = 0.801) and for all Gd-EOB-DTPA information (r = 0.040, P = 0.845), no correlation with grading was found. Hepatocellular Gd-EOB-DTPA phase iso-/hyperintensity never occurred in grade 3 HCCs.

CONCLUSION

Histological HCC grading cannot be predicted by combined Gd-EOB-DTPA/gadobutrol MRI. However, Gd-EOB-DTPA hepatocellular phase iso-/hyperintensity was never detected in grade 3 HCCs.

Correlation of magnetic resonance signal characteristics and perfusion parameters assessed by volume perfusion computed tomography in hepatocellular carcinoma: Impact on lesion characterization

AIM: To find out if magnetic resonance (MR)-signal characteristics of hepatocellular carcinomas (HCC) correlate with perfusion parameters assessed by volume perfusion computed tomography (VPCT).

METHODS: From October 2009 to January 2014, 26 (mean age, 69.3 years) patients with 36 HCC lesions who underwent both VPCT and MR liver imaging were analysed. We compared signal intensity in the T1w- and T2w-images and wash-in/wash-out kinetics on post-contrast MR images with mean values of blood flow (BF, mL/100 mL per minute), blood volume (BV, mL/100 mL), k-trans (mL/100 mL per minute), arterial liver perfusion (mL/100 mL per minute), portal venous perfusion and hepatic perfusion index (HPI, %) obtained by VPCT. Signal intensity on magnetic resonance imaging (MRI) was classified hyper/iso/hypointense compared with surrounding liver parenchyma.

RESULTS: Signal intensity on native T1w- and T2w-images was hyper/iso/hypo in 4/16/16 and 21/14/1 lesions, respectively. Wash-in and wash-out contrast kinetics were found on MRI in 33 of 36 lesions (91.7%) and 25 of 36 lesions (69.4%), respectively. The latter was observed significantly more often in higher graded lesions (P < 0.005). HPI was 94.7% ± 6.5%. There was no significant relationship between lesion’s MR-signal intensity, MR signal combinations, size and any of the VPCT-perfusion parameters. However HPI was constantly high in all HCC lesions.

CONCLUSION: VPCT parameters add limited value to MR-lesion characterization. However in HCC lesions with atypical MR signal characteristics HPI can add a parameter to ensure HCC diagnosis.

Mathematical Models of Contrast Transport Kinetics for Cancer Diagnostic Imaging: A Review

Angiogenesis plays a fundamental role in cancer growth and the formation of metastasis. Novel cancer therapies aimed at inhibiting angiogenic processes and/or disrupting angiogenic tumor vasculature are currently being developed and clinically tested. The need for earlier and improved cancer diagnosis, and for early evaluation and monitoring of therapeutic response to angiogenic treatment, have led to the development of several imaging methods for in vivo noninvasive assessment of angiogenesis. The combination of dynamic contrast-enhanced imaging with mathematical modeling of the contrast agent kinetics enables quantitative assessment of the structural and functional changes in the microvasculature that are associated with tumor angiogenesis. In this paper, we review quantitative imaging of angiogenesis with dynamic contrast-enhanced magnetic resonance imaging, computed tomography, and ultrasound.

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.

Diagnostic criteria for hepatocellular carcinoma ⩽3 cm with hepatocyte-specific contrast-enhanced magnetic resonance imaging

BACKGROUND & AIMS

Current diagnostic imaging criteria for hepatocellular carcinoma (HCC) are dedicated to imaging with nonspecific extracellular contrast agents. This study aimed to evaluate diagnostic criteria for HCC ⩽3 cm on magnetic resonance imaging (MRI) with a hepatocyte-specific contrast agent through an inception cohort study.

METHODS

Of 291 patients with chronic liver disease and new nodules of 1-3 cm in diameter at surveillance ultrasonography, 295 solid nodules (194 HCCs, 98 benign nodules, and three other malignancies) in 198 patients with a confirmed final diagnosis or ⩾24 months follow-up were evaluated on gadoxetic acid-enhanced MRI. Through univariate and multivariate logistic regression analyses, various diagnostic criteria were developed by combining significant MRI findings for diagnosing HCC. The diagnostic performance of each criterion was compared with that of the European Association for the Study of the Liver (EASL) criteria.

RESULTS

Four MRI findings (arterial-phase hyperintensity, transitional-phase hypointensity, hepatobiliary-phase hypointensity, and rim enhancement) were independently significant for diagnosis of HCC ⩽3 cm. For whole nodules, EASL criteria showed the best performance for diagnosing HCC (sensitivity, 83.5%; specificity, 81.2%). For nodules ⩽2 cm in diameter, a new criterion (arterial-phase hyperintensity and hepatobiliary-phase hypointensity) showed a significantly higher sensitivity than that of the EASL criteria (83.0% vs. 74.5%, p=0.008), without a significantly different specificity (76.7% vs. 81.1%, p=0.125).

CONCLUSIONS

EASL criteria exhibit the best diagnostic performance for HCC ⩽3 cm on hepatocyte-specific contrast-enhanced MRI. A newly identified criterion (arterial-phase hyperintensity and hepatobiliary-phase hypointensity) may increase the diagnostic sensitivity of small (⩽2 cm) HCC.

Usefulness of early vascular phase images from contrast-enhanced ultrasonography using Sonazoid for the diagnosis of hypovascular hepatocellular carcinoma

AIM

This study aimed to evaluate the usefulness of early vascular phase images produced by contrast-enhanced ultrasonography (CE-US) with Sonazoid for the diagnosis of hypovascular hepatocellular carcinoma (HCC).

METHODS

Four hundred and seventeen patients with 674 hepatic nodules were evaluated using CE-US with Sonazoid between January 2007 and March 2010. Retrospective analysis was conducted on 49 histologically confirmed nodules showing hypovascularity relative to the surrounding liver tissue in the early vascular phase and no enhancement defect in the Kupffer phase of CE-US with Sonazoid. These nodules were classified according to early vascular phase image enhancement patterns as types I (largest avascular; avascular as a whole), II (second avascular; partially avascular), III (smallest avascular; not avascular, but faintly hypovascular relative to the surrounding liver) and IV (hypovascular as a whole with vessel-like structures passing inside nodules).

RESULTS

Among the 49 nodules, types I, II, III and IV were identified in 19 (38.8%), nine (18.4%), 15 (30.6%) and six (12.2%) cases, respectively. The proportion of tumorous nodules (well-differentiated HCC and high-grade dysplastic nodules) significantly decreased with a reduction of the avascular area (68.4% in the type I, 55.6% in the type II and 33.3% in the type III nodules; P < 0.05). All nodules demonstrating the type IV enhancement pattern were non-tumorous.

CONCLUSION

Based on the size of avascular area in the early vascular phase of CE-US with Sonazoid, we can predict the malignant potential of the nodules. CE-US with Sonazoid is very useful for evaluation of hypovascular hepatic nodules.

Functional imaging of hepatocellular carcinoma

Imaging plays a key role in the clinical management of hepatocellular carcinoma (HCC), but conventional imaging techniques have limited sensitivity in visualizing small tumors and assessing response to locoregional treatments and sorafenib. Functional imaging techniques allow visualization of organ and tumor physiology. Assessment of functional characteristics of tissue, such as metabolism, proliferation and stiffness, may overcome some of the limitations of structural imaging. In particular, novel molecular imaging agents offer a potential tool for early diagnosis of HCC, and radiomics may aid in response assessment and generate prognostic models. Further prospective research is warranted to evaluate emerging techniques and their cost-effectiveness in the context of HCC in order to improve detection and response assessment.

Computed Tomography and MRI of the Hepatobiliary System and Pancreas

MRI and computed tomographic (CT) imaging are becoming more common in the diagnosis of hepatobiliary and pancreatic disorders in small animals. With the advent of multislice CT scanners, sedated examinations in veterinary patients are feasible increasing the use of this imaging modality. CT and MRI provide additional information for dogs and cats with hepatobiliary and pancreatic diseases because of lack of superimposition of structures, operator dependence, and through intravenous contrast administration. This added value provides more information for diagnosis, prognosis, and surgical planning.

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

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

MR liver imaging with Gd-EOB-DTPA: The need for different delay times of the hepatobiliary phase in patients with different liver function

PURPOSE

To determine the optimal hepatobiliary delay time after Gd-EOB-DTPA injection for lesion characterization in cirrhosis patients with different liver function.

MATERIALS AND METHODS

Ninety consecutive patients with liver cirrhosis who underwent Gd-EOB-DTPA-enhanced MRI for the evaluation of known or suspected focal liver lesions were enrolled in this retrospective study. The patients were divided into Child-Pugh A, B and C groups depending on their liver function through the Child-Pugh classification. Hepatobiliary phase images obtained at 5, 10, 15, and 20min were assessed in each group by the following items: parenchymal enhancement, contrast agent excretion into the bile ducts and ureter, and contrast- and signal-to-noise ratios for lesions.

RESULTS

In the Child-Pugh A group, parenchymal enhancement increased significantly from 5min to 15min (P<0.05), and stabilized at 20min (P=0.22). However, there was no significant difference in parenchymal enhancement among all of the hepatobiliary phases in the Child-Pugh B and C groups. The biliary contrast agent excretion was first observed before 20min in all of the patients in the Child-Pugh A group, at 20min in 4 patients (25%) in the Child-Pugh B group, and after 20min in 11 patients (78.6%) in the Child-Pugh C group. The numbers of patients whose urethral contrast agent excretion was first observed at 5min in the Child-Pugh A, B and C groups were 38 (63.3%), 12 (75.0%) and 11 (78.6%), respectively. The CNR of the lesions increased significantly (P<0.05), up to 15min after enhancement without a further increase at 20min in the Child-Pugh A group; however, no significant change was found from 5min to 20min in the Child-Pugh B and C groups. For the SNR of lesions, there was no significant difference at 5, 10, 15 and 20min in all of the groups.

CONCLUSIONS

A delay time of 15min for the hepatobiliary phase was sufficient for patients with mild liver dysfunction who were classified as Child-Pugh A. Nevertheless, for the patients with moderate or severe liver dysfunction who were classified as Child-Pugh B or C, a delay time longer than 5min is meaningless for lesion characterization.

MR Prediction of Liver Function and Pathology Using Gd-EOB-DTPA: Effect of Liver Volume Consideration

Purpose. To evaluate whether the diagnostic performance of Gd-EOB-DTPA-enhanced MRI in evaluating liver function and pathology is improved by considering liver volume (LV). Methods. This retrospective study included 104 patients who underwent Gd-EOB-DTPA-enhanced MRI before liver surgery. For each patient, using the precontrast and hepatobiliary phase images, we calculated the increase rate of the liver-to-spleen signal intensity ratio (LSR), that is, the “ΔLSR,” and the increase rate of the liver-to-muscle signal intensity ratio (LMR), that is, the “ΔLMR.” ΔLSR × LV and ΔLMR × LV were also calculated. The correlation of each MR parameter with liver function data or liver pathology was assessed. The correlation coefficients were compared between ΔLSR (ΔLMR) and ΔLSR (ΔLMR) × LV. Results. The correlation coefficient between ΔLSR (ΔLMR) × LV and cholinesterase was significantly higher than that between ΔLSR (ΔLMR) and cholinesterase. The correlation coefficient between ΔLSR (ΔLMR) × LV and the degree of fibrosis or necroinflammatory activity was significantly lower than that between ΔLSR (ΔLMR) and the degree of fibrosis or necroinflammatory activity. Conclusion. The inclusion of liver volume may improve Gd-EOB-DTPA-based predictions of liver function, but not in predictions of liver pathology.

Clinical utility of gadoxetate disodium-enhanced hepatic MRI for stereotactic body radiotherapy of hepatocellular carcinoma

PURPOSE

To investigate the utility of gadoxetate disodium-enhanced hepatic MRI (EOB-MRI) for stereotactic body radiotherapy (SBRT) to treat hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

We divided 30 HCC patients who underwent SBRT into group A (no change in their Child-Pugh score 6 months post-SBRT) and group B (increased score 6 months post-SBRT). EOB-MRI was performed before and 6 months after SBRT. We calculated the liver-spleen contrast (LSC) ratio for each radiation dose area on hepatobiliary phase scans (LSCbefore using images obtained before SBRT and LSCafter using images acquired after SBRT) and the weighted LSC (W-LSC) as: [(mean LSCbefore (0-30 Gy) × liver volume (0-30 Gy) + mean LSCbefore (30 Gy-) × liver volume (30 Gy-))/total liver volume]. Then we compared the W-LSC, percentage of the liver volume exposed to >20 Gy (V20), and mean liver dose in the two groups.

RESULTS

The LSCafter at 48, 40, and 30 Gy to the liver was statistically lower than the unirradiated area of the liver (p < 0.01). Univariate analysis showed that only W-LSC was significantly associated with group B (p = 0.02).

CONCLUSION

W-LSC was a useful parameter for predicting changes in hepatic function after SBRT.

Gadolinium Ethoxybenzyl Diethylenetriamine Pentaacetic Acid (Gd-EOB-DTPA)-Enhanced Magnetic Resonance Imaging and Multidetector-Row Computed Tomography for the Diagnosis of Hepatocellular Carcinoma: A Systematic Review and Meta-analysis

The purpose of this meta-analysis was to compare the diagnostic accuracy of gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) and multidetector-row computed tomography (MDCT) for hepatocellular carcinoma (HCC).Medline, Cochrane, EMBASE, and Google Scholar databases were searched until July 4, 2014, using combinations of the following terms: gadoxetic acid disodium, Gd-EOB-DTPA, multidetector CT, contrast-enhanced computed tomography, and magnetic resonance imaging. Inclusion criteria were as follows: confirmed diagnosis of primary HCC by histopathological examination of a biopsy specimen; comparative study of MRI using Gd-EOB-DTPA and MDCT for diagnosis of HCC; and studies that provided quantitative outcome data. The pooled sensitivity and specificity of the 2 methods were compared, and diagnostic accuracy was assessed with alternative-free response receiver-operating characteristic analysis.Nine studies were included in the meta-analysis, and a total of 1439 lesions were examined. The pooled sensitivity and specificity for 1.5T MRI were 0.95 and 0.96, respectively, for 3.0T MRI were 0.91 and 0.96, respectively, and for MDCT were 0.74 and 0.93, respectively. The pooled diagnostic odds ratio for 1.5T and 3.0T MRI was 242.96, respectively, and that of MDCT was 33.47. To summarize, Gd-EOB-DTPA-enhanced MRI (1.5T and 3.0T) has better diagnostic accuracy for HCC than MDCT.

The Diagnostic Performance of Dynamic Contrast-enhanced MR Imaging for Detection of Small Hepatocellular Carcinoma Measuring Up to 2 cm: A Meta-Analysis

PURPOSE

To determine the performance of dynamic contrast material-enhanced magnetic resonance (MR) imaging in the diagnosis of small (≤2-cm) hepatocellular carcinoma (HCC) and to identify factors that influence this performance.

MATERIALS AND METHODS

Medline and Embase databases were searched for studies performed from January 2000 to March 2014 in which the performance of MR imaging was reported for the detection of HCC up to 2 cm on either a lesion- or patient-based level, with sufficient data to construct 2 × 2 contingency tables. Diagnostic performance was quantitatively pooled for all studies by using a bivariate random-effects model with exploration involving subgroup analysis, meta-regression, and determination of study heterogeneity.

RESULTS

Twenty-two studies with 1387 small HCC lesions in 1908 patients met inclusion criteria. Heterogeneity was higher for sensitivity (range, 30%-99%) than specificity (range, 61%-100%). Overall sensitivity was 78% (95% confidence interval [CI]: 68%, 85%; I(2) = 89%), and overall specificity was 92% (95% CI: 88%, 95%; I(2) = 69%). The primary potential source of bias was use of explant as the reference standard in only 13% of studies, although lower sensitivity in such studies was not significant (59% vs 80%, P = .165). Sensitivities were significantly higher for studies that originated from Asia compared with those that originated elsewhere (89% vs 71%, P = .028), those performed with hepatobiliary phase imaging compared with those without (87% vs 65%, respectively; P = .004), and those in which gadoxetate disodium was used versus an extracellular agent (92% vs 67%, P ≤ .001). Specificity was not significantly different between subgroups (P ≥ .122). At pairwise meta-regression analysis with either study origin from Asia or performance of hepatobiliary phase imaging, only gadoxetate disodium contrast agent showed significant independent association with higher sensitivity (P = .002-.007).

CONCLUSION

Results of this meta-analysis suggest that dynamic contrast-enhanced MR imaging has moderate sensitivity and excellent specificity in the detection of HCC up to 2 cm. Gadoxetate disodium contrast agent showed the strongest association with increased sensitivity.

Evaluation of early-stage hepatocellular carcinoma by magnetic resonance imaging with gadoxetic acid detects additional lesions and increases overall survival

BACKGROUND & AIMS

Hepatocellular carcinoma (HCC) has a high rate of intrahepatic recurrence after curative treatment, possibly because metastases are not always identified before treatment. Magnetic resonance (MR) imaging with a liver-specific contrast agent, gadoxetic acid, can detect small HCCs with high levels of sensitivity. We investigated whether MR imaging with gadoxetic acid increases overall and recurrence-free survival of patients initially assessed by computed tomography (CT).

METHODS

We performed a retrospective study of data from 700 patients diagnosed with a single-nodular HCC by dynamic 4-phase CT in Seoul, Korea, from January 2009 through December 2010. Of these patients, 323 underwent additional evaluation with gadoxetic acid-enhanced MR imaging (CT+MR group). The 377 patients who did not undergo MR imaging analysis are referred to as the CT group.

RESULTS

The CT and CT+MR groups were comparable in most baseline characteristics (Child-Pugh class A, 93.1% vs 94.7%; and median size of the primary HCCs, 2.8 vs 2.6 cm, respectively). Seventy-four additional HCC nodules were detected in 53 (16.4%) of the patients who underwent MR evaluation after CT (CT+MR group). These detections increased the Barcelona Clinic Liver Cancer stages for 43 patients (13.3%) and modified their treatment plans. On multivariable analyses, the CT+MR group had a significantly lower rate of HCC recurrence (hazard ratio [HR], 0.72; 95% confidence interval [CI], 0.54-0.96) and lower overall mortality (HR, 0.65; 95% CI, 0.44-0.96) than the CT group. In an analysis of 285 pairs of patients matched on the basis of the propensity score, the CT+MR group had significantly lower overall mortality (HR, 0.66; 95% CI, 0.44-0.99).

CONCLUSIONS

Among patients who underwent dynamic CT analysis of a single-nodular HCC, additional evaluation by MR imaging with gadoxetic acid led to the detection of additional HCC nodules in 16% of patients, reduced the risk of disease recurrence, and decreased overall mortality.

Imaging Techniques for the Diagnosis of Hepatocellular Carcinoma: A Systematic Review and Meta-analysis

BACKGROUND

Several imaging modalities are available for diagnosis of hepatocellular carcinoma (HCC).

PURPOSE

To evaluate the test performance of imaging modalities for HCC.

DATA SOURCES

MEDLINE (1998 to December 2014), the Cochrane Library Database, Scopus, and reference lists.

STUDY SELECTION

Studies on test performance of ultrasonography, computed tomography (CT), or magnetic resonance imaging (MRI).

DATA EXTRACTION

One investigator abstracted data, and a second investigator confirmed them; 2 investigators independently assessed study quality and strength of evidence.

DATA SYNTHESIS

Few studies have evaluated imaging for HCC in surveillance settings. In nonsurveillance settings, sensitivity for detection of HCC lesions was lower for ultrasonography without contrast than for CT or MRI (pooled difference based on direct comparisons, 0.11 to 0.22), and MRI was associated with higher sensitivity than CT (pooled difference, 0.09 [95% CI, 0.07 to 12]). For evaluation of focal liver lesions, there were no clear differences in sensitivity among ultrasonography with contrast, CT, and MRI. Specificity was generally 0.85 or higher across imaging modalities, but this item was not reported in many studies. Factors associated with lower sensitivity included use of an explanted liver reference standard, and smaller or more well-differentiated HCC lesions. For MRI, sensitivity was slightly higher for hepatic-specific than nonspecific contrast agents.

LIMITATIONS

Only English-language articles were included, there was statistical heterogeneity in pooled analyses, and costs were not assessed. Most studies were conducted in Asia and had methodological limitations.

CONCLUSION

CT and MRI are associated with higher sensitivity than ultrasonography without contrast for detection of HCC; sensitivity was higher for MRI than CT. For evaluation of focal liver lesions, the sensitivities of ultrasonography with contrast, CT, and MRI for HCC are similar.

PRIMARY FUNDING SOURCE

Agency for Healthcare Research and Quality. (

PROSPERO

CRD42014007016).

Factors predicting aggressiveness of non-hypervascular hepatic nodules detected on hepatobiliary phase of gadolinium ethoxybenzyl diethylene-triamine-pentaacetic-acid magnetic resonance imaging

AIM: To establish a prognostic formula that distinguishes non-hypervascular hepatic nodules (NHNs) with higher aggressiveness from less hazardous one.

METHODS: Seventy-three NHNs were detected in gadolinium ethoxybenzyl diethylene-triamine-pentaacetic-acid magnetic resonance imaging (Gd-EOB-DTPA-MRI) study and confirmed to change 2 mm or more in size and/or to gain hypervascularity. All images were interpreted independently by an experienced, board-certified abdominal radiologist and hepatologist; both knew that the patients were at risk for hepatocellular carcinoma development but were blinded to the clinical information. A formula predicting NHN destiny was developed using a generalized estimating equation model with thirteen explanatory variables: age, gender, background liver diseases, Child-Pugh class, NHN diameter, T1-weighted imaging/T2-weighted imaging detectability, fat deposition, lower signal intensity in arterial phase, lower signal intensity in equilibrium phase, α-fetoprotein, des-γ-carboxy prothrombin, α-fetoprotein-L3, and coexistence of classical hepatocellular carcinoma. The accuracy of the formula was validated in bootstrap samples that were created by resampling of 1000 iterations.

RESULTS: During a median follow-up period of 504 d, 73 NHNs with a median diameter of 9 mm (interquartile range: 8-12 mm) grew or shrank by 68.5% (fifty nodules) or 20.5% (fifteen nodules), respectively, whereas hypervascularity developed in 38.4% (twenty eight nodules). In the fifteen shrank nodules, twelve nodules disappeared, while 11.0% (eight nodules) were stable in size but acquired vascularity. A generalized estimating equation analysis selected five explanatories from the thirteen variables as significant factors to predict NHN progression. The estimated regression coefficients were 0.36 for age, 6.51 for lower signal intensity in arterial phase, 8.70 or 6.03 for positivity of hepatitis B virus or hepatitis C virus, 9.37 for des-γ-carboxy prothrombin, and -4.05 for fat deposition. A formula incorporating the five coefficients revealed sensitivity, specificity, and accuracy of 88.0%, 86.7%, and 87.7% in the formulating cohort, whereas these of 87.2% ± 5.7%, 83.8% ± 13.6%, and 87.3% ± 4.5% in the bootstrap samples.

CONCLUSION: These data suggest that the formula helps Gd-EOB-DTPA-MRI detect a trend toward hepatocyte transformation by predicting NHN destiny.

Comparison of gadoxetic acid and gadopentetate dimeglumine-enhanced MRI for HCC detection: prospective crossover study at 3 T

Background

Gadoxetic acid and gadopentetate dimeglumine are gadolinium-based contrast agents (GBCAs) with an established role in HCC detection and characterization.

Purpose

To compare gadopentetate dimeglumine and gadoxetic acid-enhanced magnetic resonance imaging (MRI) for image quality and hepatocellular carcinoma (HCC) detection/conspicuity.

Material and Methods

In this IRB approved cross-over pilot prospective study, 12 patients (all men; mean age, 56 years) with chronic liver disease at risk of HCC underwent two repeat MRI examinations using gadopentetate dimeglumine and gadoxetic acid (mean interval between studies, 5 days). Two independent observers analyzed images for image quality and HCC detection/conspicuity. Per-lesion sensitivity, positive predictive value, quantitative enhancement, and lesion-to-liver contrast ratio were calculated for both contrast agents.

Results

There was no significant difference in image quality scores between both GBCAs (P = 0.3). A total of 20 HCCs were identified with reference standard in 12 patients (mean size 2.6 cm, range, 1.0–5.0 cm). Higher sensitivity was seen for observer 1 for gadoxetic acid-set in comparison with gadopentetate dimeglumine-set (sensitivity increased from 85.7% to 92.8%), while no difference was noted for observer 2 (sensitivity of 78.5%). Lesion conspicuity was significantly higher on hepatobiliary phase (HBP) images compared to arterial phase images with both GBCAs for both observers (P < 0.05). Lesion-to-liver contrast ratios were significantly higher for HBP compared to all dynamic phases for both agents (P < 0.05).

Conclusion

Our initial experience suggests that gadoxetic acid-set was superior to gadopentetate dimeglumine-set in terms of HCC detection for one observer, with improved lesion conspicuity and liver-to-lesion contrast on HBP images.

MRI with gadoxetate disodium for colorectal liver metastasis: is it the new "imaging modality of choice"?

BACKGROUND

Accurate detection of colorectal liver metastasis is paramount in the role of management. This study aims to compare magnetic resonance imaging (MRI) with gadoxetate disodium (a hepatocyte-specific agent-Eovist®) to triple-phase enhanced computed tomography in detecting colorectal liver metastases.

METHODS

A retrospective chart analysis of 30 patients from 2011 to 2013 with colorectal liver metastases was performed. Patients with more than 6 weeks or two cycles of chemotherapy between the two imaging modalities were excluded. The number of lesions identified on triple-phase enhanced computed tomography vs. MRI with Eovist® was compared.

RESULTS

Of the 30 patients that met the inclusion criteria, 12 (40 %) patients had more lesions identified on MRI with Eovist® compared to triple-phase enhanced computed tomography. Eighteen (60 %) had no change in the number of lesions identified. When MRI with Eovist® detected more lesions, the mean number of additional lesions detected was 1.5. Eovist® MRI changed the surgical management in 36.7 % of patients.

CONCLUSION

MRI with Eovist® is superior to enhanced computed tomography in identifying colorectal liver metastases. The increased number of lesion identified on MRI with Eovist® can profoundly change the surgeon's management. It should be considered the "imaging modality of choice" in preoperative imaging for liver metastases in these patients.

Hepatocellular carcinoma risk assessment using gadoxetic acid-enhanced hepatocyte phase magnetic resonance imaging

AIM

To investigate whether the patients with hypovascular liver nodules determined on the arterial phase and hypointensity on the hepatocyte phase gadoxetic acid-enhanced magnetic resonance imaging (hypovascular hypointense nodules) are at increased risk of hepatocarcinogenesis, we assessed subsequent typical hepatocellular carcinoma (HCC) development at any sites of the liver with and without such nodules.

METHODS

One hundred and twenty-seven patients with chronic hepatitis B or C and without a history of HCC, including 68 with liver cirrhosis, were divided into those with (non-clean liver group, n = 18) and without (clean liver group, n = 109) hypovascular hypointense nodules. All the patients were followed up for 3 years, and HCC development rates and risk factors were analyzed with the Kaplan-Meier method and the Cox proportional hazard model, respectively.

RESULTS

A total of 17 patients (10 in the non-clean liver group and seven in the clean liver group) developed typical HCC. Cumulative 3-year rates of HCC development were 55.5% in the non-clean liver group and 6.4% in the clean liver group (P < 0.001), and those at the different sites from the initial nodules was also higher in the non-clean liver group (22.2%) than the clean liver group (6.4%) (P = 0.003). Multivariate analysis identified older age (P = 0.024), low platelet counts (P = 0.017) and a non-clean liver (P < 0.001) as independent risk factors for subsequent HCC development.

CONCLUSION

Patients with hypovascular hypointense liver nodules are at a higher risk for HCC development at any sites of the liver than those without such nodules.

Real-time image fusion for successful percutaneous radiofrequency ablation of hepatocellular carcinoma

Percutaneous radiofrequency ablation (RFA) is an established nonsurgical curative treatment for hepatocellular carcinoma (HCC). Because of its efficiency and safety, sonography is the most commonly used imaging modality when performing RFA. However, the presence of HCC nodules that are inconspicuous when using conventional sonography is a major drawback of RFA and limits its feasibility as a treatment for HCC. However, a new technology has been developed that synthesizes high-resolution multiplanar reconstruction images using 3-dimensional data and is combined with a position-tracking system using magnetic navigation. With this technology, real-time sonograms can be fused with corresponding computed tomographic, magnetic resonance imaging, or even sonographic volume data; this process is known as real-time image fusion. In this article, we describe this novel imaging method as a useful tool for successful RFA treatment of HCC.

Incremental value of liver MR imaging in patients with potentially curable colorectal hepatic metastasis detected at CT: a prospective comparison of diffusion-weighted imaging, gadoxetic acid-enhanced MR imaging, and a combination of both MR techniques

PURPOSE

To prospectively compare diagnostic performance of diffusion-weighted (DW) imaging, gadoxetic acid-enhanced magnetic resonance (MR) imaging, both techniques combined (combined MR imaging), and computed tomography (CT) for detecting colorectal hepatic metastases and evaluate incremental value of MR for patients with potentially curable colorectal hepatic metastases detected with CT.

MATERIALS AND METHODS

In this institutional review board-approved prospective study, with informed consent, 51 patients (39 men, 12 women; mean age, 62 years) with potentially resectable hepatic metastases detected with CT underwent liver MR, including DW imaging and gadoxetic acid-enhanced MR. Two independent readers reviewed DW, gadoxetic acid-enhanced, combined MR, and CT image sets to detect hepatic metastases. The figure-of-merit (FOM) value representing overall diagnostic performance, sensitivity, and positive predictive value (PPV) for each image set were analyzed by using free-response receiver operating characteristic analysis and generalized estimating equations.

RESULTS

There were 104 hepatic metastases in 47 patients. The pooled FOM values, sensitivities, and PPVs of combined MR (FOM value, 0.93; sensitivity, 98%; and PPV, 88%) and gadoxetic acid-enhanced MR (FOM value, 0.92; sensitivity, 95%; and PPV, 90%) were significantly higher than those of CT (FOM value, 0.82; sensitivity, 85%; and PPV, 73%) (P < .006). The pooled FOM value and sensitivity of combined MR (FOM value, 0.92; sensitivity, 95%) was also significantly higher than that of DW imaging (FOM value, 0.82; sensitivity, 79%) for metastases (≤1-cm diameter) (P ≤ .003). DW imaging showed significantly higher pooled sensitivity (79%) and PPV (60%) than CT (sensitivity, 50%; PPV, 33%) for the metastases (≤1-cm diameter) (P ≤ .004). In 47 patients with hepatic metastases, combined MR depicted more metastases than CT in 10 and 14 patients, respectively, according to both readers.

CONCLUSION

Gadoxetic acid-enhanced MR and combined MR are more accurate than CT in detecting colorectal hepatic metastases, have an incremental value when added to CT alone for detecting additional metastases, and can be routinely performed in patients with potentially curable hepatic metastases detected with CT.

Diagnostic performance of gadoxetic acid-enhanced liver MR imaging in the detection of HCCs and allocation of transplant recipients on the basis of the Milan criteria and UNOS guidelines: correlation with histopathologic findings

PURPOSE

To determine whether hepatobiliary phase ( HBP hepatobiliary phase ) imaging can improve the diagnostic performance of gadoxetic acid-enhanced liver magnetic resonance (MR) imaging in the detection of hepatocellular carcinomas ( HCC hepatocellular carcinoma s) and to investigate the accuracy of gadoxetic acid-enhanced MR imaging in the allocation of transplant recipients on the basis of the Milan criteria and United Network for Organ Sharing ( UNOS United Network for Organ Sharing ) guidelines.

MATERIALS AND METHODS

This retrospective study had institutional review board approval; the requirement for informed consent was waived. Between June 2008 and June 2011, 63 patients who underwent liver transplantation (LT) were included. All patients underwent a gadoxetic acid-enhanced 3.0-T MR imaging examination of the liver that included HBP hepatobiliary phase images obtained 20 minutes after contrast material administration. Two abdominal radiologists independently assessed two MR imaging data sets to detect HCC hepatocellular carcinoma s: Set 1 included unenhanced and gadoxetic acid-enhanced dynamic images, and set 2 also included HBP hepatobiliary phase images. Patients were allocated into three groups: Those who did not meet the Milan criteria, those who did meet the Milan criteria with additional priority according to UNOS United Network for Organ Sharing guidelines, and those who did meet the Milan criteria without additional priority. Diagnostic performance of each data set in depicting HCC hepatocellular carcinoma s was compared by using jackknife alternative free-response receiver operating characteristics ( JAFROC jackknife alternative free-response receiver operating characteristic s). Sensitivity and accuracy of patient allocation were compared by using generalized estimating equations.

RESULTS

Sixty-three HCC hepatocellular carcinoma s were found in 36 of 63 patients. Eight patients were classified as not meeting Milan criteria, 12 as meeting Milan criteria with additional priority, and 43 as meeting Milan criteria without additional priority. For the detection of HCC hepatocellular carcinoma s, reader-averaged figures of merit estimated with JAFROC jackknife alternative free-response receiver operating characteristic s were 0.761 for set 1 and 0.791 for set 2 (P < .001). Addition of HBP hepatobiliary phase images significantly improved sensitivity for the detection of HCC hepatocellular carcinoma s, particularly 1-2-cm HCC hepatocellular carcinoma s (six [20.7%] vs 13 [44.8%] of 29 [P = .008] for reader 1 and eight [27.6%] vs 12 [41.4%] of 29 [P = .041] for reader 2). Accuracy of patient allocation was 88.9% for set 1 and 92.1% for set 2 (P = .151).

CONCLUSION

Addition of HBP hepatobiliary phase images can significantly improve the diagnostic performance of gadoxetic acid-enhanced liver MR imaging in the detection of 1-2-cm HCC hepatocellular carcinoma s in liver transplantation candidates. In addition, gadoxetic acid-enhanced MR imaging showed 92.1% accuracy in patient allocation on the basis of the Milan criteria and UNOS United Network for Organ Sharing guidelines.

Presurgical planning for hepatobiliary malignancies: clinical and imaging considerations

There are many considerations in the evaluation of liver malignancy before planned surgical treatment. This article focuses on interpretation of MR imaging of the liver for surgical treatment planning of hepatocellular carcinoma, colorectal cancer metastases, and hilar cholangiocarcinoma. Clinical status, anatomic variants, future liver remnant, and underlying liver disease are all important factors in the decision to proceed with liver resection. The primary objective of preoperative imaging is to correctly identify patients who are candidates for curative intervention and to accurately stage their disease. Treatment planning for these complex patients is best done with a multidisciplinary team approach.

Hepatocellular carcinoma: clinical significance of signal heterogeneity in the hepatobiliary phase of gadoxetic acid-enhanced MR imaging

OBJECTIVES

To clarify the relationship between the biological behaviour of hepatocellular carcinomas (HCCs) and their signal intensity in the hepatobiliary phase of gadoxetic acid-enhanced MR imaging with a special focus on the signal heterogeneity.

METHODS

A total of 68 patients with 70 pathologically proven HCCs were enrolled. On the basis of the signal intensity in the hepatobiliary phase, the lesions were classified into three groups: group 1, homogeneous hypointensity (n = 44); group 2, heterogeneous hyperintensity (n = 20); and group 3, homogeneous hyperintensity (n = 6). The clinicopathological findings were compared among the three groups.

RESULTS

The tumour size and the serum level of protein induced by vitamin K absence or antagonist-II (PIVKA-II) were significantly higher in group 2 compared to group 1 (p = 0.0155, p = 0.0215, respectively) and compared to group 3 (p = 0.0330, p = 0.0220, respectively). The organic anion transporting polypeptide 8 (OATP8) expression in group 2 and group 3 was significantly higher than in group 1 (p < 0.0001, p < 0.0001, respectively). Group 2 showed a significantly lower disease-free survival rate compared to group 1 (p = 0.0125), and group 2 was an independent prognostic factor for disease-free survival (p = 0.0308).

CONCLUSIONS

HCCs in the hepatobiliary phase that are heterogeneously hyperintense on gadoxetic acid-enhanced MR imaging have more malignant potential than other types of HCCs.

KEY POINTS

• Heterogeneous uptake of gadoxetic acid suggests more malignant potential in HCC • Uptake of gadoxetic acid does not suggest less malignancy in HCC • Evaluation of signal heterogeneity on gadoxetic acid-enhanced MR imaging is useful.

Hepatobiliary magnetic resonance imaging in patients with liver disease: correlation of liver enhancement with biochemical liver function tests

OBJECTIVES

To evaluate hepatobiliary magnetic resonance imaging (MRI) using Gd-EOB-DTPA in relation to various liver function tests in patients with liver disorders.

METHODS

Fifty-one patients with liver disease underwent Gd-EOB-DTPA-enhanced liver MRI. Based on region-of-interest (ROI) analysis, liver signal intensity was calculated using the spleen as reference tissue. Liver-spleen contrast ratio (LSCR) and relative liver enhancement (RLE) were calculated. Serum levels of total bilirubin, gamma glutamyl transpeptidase (GGT), aspartate aminotransferase (AST), alanine aminotransferase (ALT), glutamate dehydrogenase (GLDH), lactate dehydrogenase (LDH), serum albumin level (AL), prothrombin time (PT), creatinine (CR) as well as international normalised ratio (INR) and model for end-stage liver disease (MELD) score were tested for correlation with LSCR and RLE.

RESULTS

Pre-contrast LSCR values correlated with total bilirubin (r = -0.39; p = 0.005), GGT (r = -0.37; p = 0.009), AST (r = -0.38; p = 0.013), ALT (r = -0.29; p = 0.046), PT (r = 0.52; p < 0.001), GLDH (r = -0.55; p = 0.044), INR (r = -0.42; p = 0.003), and MELD Score (r = -0.53; p < 0.001). After administration of Gd-EOB-DTPA bilirubin (r = -0.45; p = 0.001), GGT (r = -0.40; p = 0.004), PT (r = 0.54; p < 0.001), AST (r = -0.46; p = 0.002), ALT (r = -0.31; p = 0.030), INR (r = -0.45; p = 0.001) and MELD Score (r = -0.56; p < 0.001) significantly correlated with LSCR. RLE correlated with bilirubin (r = -0.40; p = 0.004), AST (r = -0.38; p = 0.013), PT (r = 0.42; p = 0.003), GGT (r = -0.33; p = 0.020), INR (r = -0.36; p = 0.011) and MELD Score (r = -0.43; p = 0.003).

CONCLUSIONS

Liver-spleen contrast ratio and relative liver enhancement using Gd-EOB-DTPA correlate with a number of routinely used biochemical liver function tests, suggesting that hepatobiliary MRI may serve as a valuable biomarker for liver function. The strongest correlation with liver enhancement was found for the MELD Score.

KEY POINTS

• Relative enhancement (RLE) of Gd-EOB-DTPA is related to biochemical liver function tests. • Correlation of RLE with bilirubin, ALT, AST, GGT, INR and MELD Score is reverse. • The correlation of relative liver enhancement with prothrombin time is positive. • AST, ALT, GLDH, prothrombin time, INR and MELD Score correlate with pre-contrast liver-spleen contrast ratio. • Such biomarkers may help to evaluate liver function.

Quantitative evaluation of enhancement patterns in focal solid liver lesions with Gd-EOB-DTPA-enhanced MRI

Purpose

The objective was to investigate the dynamic enhancement patterns in focal solid liver lesions after the administration of gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) by means of dynamic magnetic resonance imaging (MRI) including hepatobiliary phase (HP) images 20 min after Gd-EOB-DTPA administration.

Materials and Methods

Non-enhanced T1/T2-weighted as well as dynamic magnetic resonance (MR) images during the arterial phase (AP), the portal venous phase (PVP), the late phase (LP), and the HP (20 min) were obtained from 83 patients (54 male, 29 female, mean age 62.01 years) with focal solid liver lesions. MRI was conducted by means of a 1.5-T system for 63 patients with malignant liver lesions (HCCs: n = 34, metastases: n = 29) and for 20 patients with benign liver lesions (FNH lesions: n = 14, hemangiomas: n = 3, adenomas: n = 3). For quantitative analysis, signal-to-noise ratios (SNR), contrast enhancement ratios (CER), lesion-to-liver contrast ratios (LLC), and signal intensity (SI) ratios were measured.

Results

The SNR of liver parenchyma significantly increased in each dynamic phase after Gd-EOB-DTPA administration compared to the SNR of non-enhanced images (p<0.001). The CER of HCCs and metastases significantly decreased between LP and HP images (p = 0.0011, p<0.0001). However, FNH lesions did not show any significant difference, whereas an increased CER was found in hemangiomas. The mean LLCs of FNH lesions were significantly higher than those of HCCs and metastases. The LLC values of hemangiomas remained negative during the entire time course, whereas the LLC of adenomas indicated hyperintensity from the AP to the LP. Furthermore, adenomas showed hypointensity in HP images.

Conclusion

Gd-EOB-DTPA-enhanced MRI may help diagnose focal solid liver lesions by evaluating their enhancement patterns.

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

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Diagnosis of Pathologically Early HCC with EOB-MRI: Experiences and Current Consensus

OBJECTIVE

After much debate, the International Consensus Group for Hepatocellular Neoplasia (ICGHN) has recently arrived at a conclusion regarding the pathological criteria for early hepatocellular carcinoma (HCC). They have stated that stromal invasion should be recognized as the most important pathological finding for precisely diagnosing and differentiating early HCC from dysplastic nodules (DN).

METHODS

We conducted a review of the imaging findings from multi-imaging modalities of early HCC cases diagnosed according to the pathological criteria of the ICGHN. The multi-imaging modalities included gadoxetic acid (Gd-EOB-DTPA) enhanced magnetic resonance imaging (MRI), abbreviated as EOB-MRI, contrast-enhanced CT (CE-CT), CT during arterioportography (CTAP), and CT during hepatic arteriography (CTHA). It has been shown that EOB-MRI is the only imaging modality that has sufficient resolution for the detection and classification of early HCC.

RESULTS

The most significant imaging feature for diagnosing early HCC was hypointensity on hepatobiliary-phase (HP) images of EOB-MRI; all of the cases of early HCC that were detected on HP images of EOB-MRI showed hypointensity, while all of the images of DN showed isointensity or hyperintensity compared with the liver parenchyma. The results of the diagnostic performance analysis showed that EOB-MRI had excellent sensitivity (97%) for detecting early HCC and outstanding specificity (100%) for distinguishing early HCC from DN.

CONCLUSIONS

Considering the results from imaging-pathologic correlations and follow-up studies indicating that many early-stage hepatocellular nodules showing hypointensity on HP images of EOB-MRI tend to develop hypervascularization during a relatively short follow-up period, it is beginning to be accepted that such nodules may be treated as early HCC. However, hepatologists and radiologists should also recognize that some cases of early HCC may show isointensity or hyperintensity on HP images of EOB-MRI, making it impossible to differentiate early HCC from DN, although the low prevalence of such nodules may be unlikely to affect the generally accepted follow-up protocols for cirrhotic patients. Our results and other recent reports have indicated that signal-intensity patterns on HP images of EOB-MRI for DN and early HCC directly correlate with the degree of expression of the organic anion transporting polypeptide (OATP) 1B3 in the nodules. Thus, the diagnostic performance of pathological analyses for early HCC cases may be dramatically improved, nearly up to that of EOB-MRI, by incorporating an OATP1B3 staining method.