Fast 3D dynamic MR imaging of the liver with MR SmartPrep: comparison with helical CT in detecting hypervascular hepatocellular carcinoma

The diagnostic performance of contrast-enhanced CT versus extracellular contrast agent-enhanced MRI in detecting hepatocellular carcinoma: direct comparison and a meta-analysis

To compare the diagnostic value of contrast-enhanced computed tomography (CT) with extracellular contrast agent-enhanced magnetic resonance imaging (ECA-MRI) for the detection of hepatocellular carcinoma (HCC). Pubmed, Embase, Web of Science and Cochrane Library were searched (1/5/2021) for studies comparing contrast-enhanced CT with ECA-MRI in patients suspected of HCC. Studies without head-to-head comparison were excluded. The pooled sensitivity, specificity and summary area under the curve (sAUC) of contrast-enhanced CT and ECA-MRI in detecting HCC was calculated based on bivariate random effects model. Heterogeneity test included threshold effect analysis and meta-regression. Subgroup analyses were conducted according to lesion size (< 20 mm or ≥ 20 mm). Overall, 10 articles containing 1333 patients were deemed suitable for inclusion in this meta-analysis. ECA-MRI displayed increased sensitivity to contrast-enhanced CT in detecting HCC (0.77 vs. 0.63, P < 0.01). The difference in specificity between ECA-MRI and contrast-enhanced CT was not statistically significant (0.93 vs. 0.94, P = 0.25). ECA-MRI yielded higher diagnostic accuracy (sAUCs = 0.88 vs. 0.80, P < 0.01). In the subgroup analysis with a lesion size < 20 mm, ECA-MRI allowed significant gains of accuracy compared to contrast-enhanced CT (0.79 vs. 0.72, P = 0.02). ECA-MRI also outperformed contrast-enhanced CT in patients with lesion size ≥ 20 mm (sAUCs = 0.96 vs. 0.93, P = 0.04). ECA-MRI provided higher sensitivity and accuracy than contrast-enhanced CT in detecting HCC, especially lesions size < 20 mm.

Differences in Liver Imaging and Reporting Data System Categorization Between MRI and CT

OBJECTIVE

The purpose of this study is to determine whether focal liver observations are categorized differently by CT and MRI using the Liver Imaging and Reporting Data System (LI-RADS).

MATERIALS AND METHODS

We performed a retrospective review of 58 patients at risk for hepatocellular carcinoma who underwent liver protocol CT and MRI within 1 month of each other. Two readers assigned a LI-RADS category for all focal liver observations in consensus. A significant category upgrade was defined as a change from LI-RADS categories 1 and 2 or nonvisualization to LI-RADS categories 3-5, from LI-RADS category 3 to category 4 or 5, from LI-RADS category 4 to category 5, or from any category to LI-RADS category 5V. A significant downgrade was defined as a change from LI-RADS category 5 to categories 1-4, from LI-RADS category 4 to categories 1-3, or from LI-RADS category 3 to categories 1 or 2.

RESULTS

The LI-RADS category was different between CT and MRI for 77.2% (176/228) of observations. A significant upgrade occurred on MRI for 42.5% (97/228) of observations because of nonvisualization by CT (n = 78), capsule (n = 8), arterial hyperenhancement (n = 4), intratumoral fat (n = 2), larger size (n = 2), tumor in portal vein (n = 2), and wash-out (n = 1). Of these 97 upgraded observations, two were upgraded to LI-RADS category 5V, 15 were upgraded to category 5, and 13 were upgraded to category 4. A significant downgrade occurred on MRI for 8.8% (20/228) of observations because of marked T2 hyperintensity (n = 14), smaller size (n = 2), wedge shape (n = 2), and marked T2 hypointensity (n = 2).

CONCLUSION

LI-RADS categorization of focal liver observations is dependent on imaging modality. MRI results in both upgraded and downgraded categorization compared with CT in an important proportion of observations.

Recent advances in the imaging of hepatocellular carcinoma

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

Magnetic resonance imaging in cirrhosis: what's new?

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

The efficacy of contrast protocol in hepatic dynamic computed tomography: multicenter prospective study in community hospitals

Purpose

To investigate four different contrast protocols to detect hypervascular hepatocellular carcinoma (HCC) most adaptable for patients at any body weight (BW) in clinical practice.

Materials and methods

A post-marketing surveillance of liver dynamic CT was prospectively performed by four different protocols in 415 patients: Protocol-A, BW-tailored dose of contrast media (CM: iohexol 300 mgI/mL), fixed injection duration (30s), fixed scan timing at arterial phase (AP); Protocol-B, BW-tailored dose of CM, fixed injection duration (30s), by bolus tracking; Protocol-C, BW-tailored dose of CM, fixed injection flow rate, by bolus tracking; Protocol-D, 100 mL constant of CM at any BW, fixed scan timing. Scan timing and tumor conspicuity at AP was scored qualitatively. The quantitative CT values of aorta and tumor liver contrast (TLC) were obtained.

Results

The qualitative rate assessed “good” as scan timing of AP in Protocol-C was significantly lower than those in Protocols A and D (difference:16.6%, 17.4%, P = 0.0069, P = 0.0140, respectively). Scatter plot of Protocol-D (R² = 0.1283) at AP showed significant inverse relationship between TLC and BW (P =0.0053), although not significant in Protocols A, B, C.

Conclusion

In patients with higher BW, protocols of BW-tailored dose of CM and/or fixed injection duration have no dependence on BW to diagnose hypervascular HCCs.

Electronic supplementary material

The online version of this article (doi:10.1186/2193-1801-2-367) contains supplementary material, which is available to authorized users.

Hepatocellular carcinoma presenting as an incidental isolated malignant portal vein thrombosis

INTRODUCTION

Portal vein thrombosis is frequently associated with hepatocellular carcinoma (HCC). Tumor invasion into the portal vein by direct venous extension or metastasis occurs in up to 70% of HCC patients (Cedrone et al., Liver 16:94-8, 1996). However, presentation as an isolated malignant portal vein thrombosis without any evidence of obvious hepatoma-like lesions in the liver by imaging studies is extremely uncommon. We present an unusual case of HCC presenting as a malignant portal vein thrombus, proven on biopsy of the thrombus without any evidence of primary liver lesion. This, to our knowledge, is the first case of HCC presenting as an incidental isolated malignant portal vein thrombosis. The importance of doing delayed enhancement imaging studies to rule out malignant portal vein thrombosis is emphasized.

CASE REPORT

A 60-year-old man presented with acute substernal chest pain. Physical examination revealed icterus. Examination of the abdomen did not reveal any organomegaly. Liver function test revealed a predominantly conjugated bilirubinemia. Abdominal sonogram revealed thrombosis and occlusion of the posterior right portal vein. Liver parenchyma was homogenous with no intrahepatic mass. Computed tomography (CT) of the abdomen and pelvis after administration of oral and intravenous contrast with delayed views revealed arterial enhancement of the right portal vein thrombus with delayed washout. MRI of the abdomen with gadolinium confirmed the right portal vein thrombus without focal hepatic mass. Aspiration of the right portal vein thrombus under CT guidance revealed hepatocellular carcinoma which was confirmed by immunohistochemistry. Serum alpha-fetoprotein level was very high. Patient was started on sorafenib with subsequent decrease in alpha-fetoprotein level. He was doing well till the date of this report.

DISCUSSION

This unusual case of hepatocellular carcinoma presenting as an incidental malignant portal vein thrombosis without any primary liver lesion is extremely rare. Other reported cases of malignant portal vein thrombosis have been in patients with underlying hepatoma, cirrhosis, or with intrabiliary hepatocelluar carcinoma. In the clinical setting of portal vein thrombosis, imaging studies showing enhancement of the thrombus in the arterial phase are important in leading to the diagnosis of malignancy.

Optimization of the dynamic, Gd-EOB-DTPA-enhanced MRI of the liver: the effect of the injection rate

BACKGROUND

Tissue-specific gadolinium-based contrast agents such as Gd-BOPTA, Gd-EOB-DTPA are increasingly used for liver imaging. Despite the added value of the hepatobiliary phase a proper arterial phase is still critical, especially in patients with chronic liver diseases. So far, there are limited data in the literature about the effect of the injection speed of Gd-EOB-DTPA in liver and vessel enhancement.

PURPOSE

To evaluate the effect of injection rate on the enhancement of liver parenchyma and vasculature in Gd-EOB-DTPA-enhanced liver MRI.

MATERIAL AND METHODS

Eighty patients who underwent Gd-EOB-DTPA-enhanced liver MRI (1.5T multi-channel MR-system) were retrospectively evaluated. We used a Care Bolus technique with an injection rate of 2 mL/s in group 1 (n = 40) and a Care Bolus technique with an injection rate of 1 mL/s in group 2 (n = 40) to determine the start of the arterial-dominant phase. Signal intensities were measured in vascular structures and liver parenchyma. Signal-to-noise-ratio (SNR), SNR increase (SNRi), and percentage enhancement (PE) were calculated and compared by a students t-test.

RESULTS

The SNR, SNRi, and PE of the aorta in the arterial phase were significantly higher in group 2 in comparison to group 1 (P = 0.007, P = 0.0043, and P < 0.001, respectively). There were no significant differences concerning the SNR, SNRi, or PE of the portal vein and the normal liver parenchyma between both groups at all time points.

CONCLUSION

The study shows that a lower injection rate of 1 mL/s enables a higher enhancement in the aorta in the arterial phase compared with Gd-EOB-DTPA-enhanced MRI with the more commonly used injection rate of 2 mL/s.

Hepatocellular carcinoma in a North American population: does hepatobiliary MR imaging with Gd-EOB-DTPA improve sensitivity and confidence for diagnosis?

PURPOSE

To evaluate the value of hepatobiliary phase imaging for detection and characterization of hepatocellular carcinoma (HCC) in liver MRI with Gd-EOB-DTPA, in a North American population.

MATERIALS AND METHODS

One hundred MRI examinations performed with the intravenous injection of Gd-EOB-DTPA in patients with cirrhosis were reviewed retrospectively. Nodules were classified as HCC (n = 70), indeterminate (n = 33), or benign (n = 22). Five readers independently reviewed each examination with and without hepatobiliary phase images (HBP). Lesion conspicuity scores were compared between the two readings. Lesion detection, confidence scores, and receiver operating characteristic (ROC) analysis were compared.

RESULTS

Lesion detection was slightly improved for all lesion types with the inclusion of the HBP, and was substantially higher for small HCCs (96.0% versus 85.3%). Mean confidence scores for the diagnosis of HCC increased for HCCs overall and each size category (P < 0.001). Diagnostic performance improved with the addition of the HBP (aggregate AROC 87.7% versus 80.0%, P < 0.01), and sensitivity for characterization improved (90.9% versus 78.3%, P < 0.01) while specificity was unchanged.

CONCLUSION

Hepatobiliary phase imaging may improve small lesion detection (<1 cm) and characterization of lesions in general, in MRI of the cirrhotic liver with Gd-EOB-DTPA.

MR imaging of hypervascular lesions in the cirrhotic liver: a diagnostic dilemma

Cirrhosis is characterized by a spectrum of hepatocellular nodules that mark the progression from regenerative nodules to low- and high-grade dysplastic nodules, followed by small and large hepatocellular carcinomas (HCCs). Characterization of small nodules on the basis of imaging and histopathologic findings is complicated by an overlap in findings associated with each type of nodule, a reflection of their multistep transitions. Vascularity patterns change gradually as the nodules evolve, with an increasing shift from predominantly venous to predominantly arterial perfusion. Regenerative and low-grade dysplastic nodules demonstrate predominantly portal perfusion and contrast enhancement similar to that of surrounding parenchyma. Differentiation of high-grade dysplastic nodules and well-differentiated HCCs on the basis of dynamic imaging and histologic findings is challenging, with a high rate of false-negative results. Some small nodules that lack hypervascularity may be early HCCs. Progressed small and large HCCs usually present no diagnostic difficulty because of their characteristic findings. Although characterization of hypervascular lesions in the cirrhotic liver is difficult, it is a key step in disease management and is the radiologist's responsibility.

Validation of an extension of the international non-invasive criteria for the diagnosis of hepatocellular carcinoma to the characterization of macroscopic portal vein thrombosis

BACKGROUND AND AIM

We aimed to validate the non-invasive criteria for the characterization of portal vein thrombosis (PVT) in patients with cirrhosis and hepatocellular carcinoma (HCC). In a prospective study, we examined the impact of arterial hypervascularity, as established by the European Association for the Study of the Liver and the American Association for the Study of Liver Diseases recommendations for the non-invasive diagnosis of HCC, as a criterion for characterizing macroscopic PVT (EASL/AASLD extension criteria).

METHODS

A total of 96 cases of PVT detected using ultrasonography in patients with cirrhosis and HCC were included in the study. When coincidental arterial hypervascularity was detected by contrast perfusional ultrasonography and helical computed tomography, the thrombus was considered malignant according to our EASL/AASLD extension criteria. In all cases, an ultrasound-guided biopsy examination of the thrombus was performed.

RESULTS

Coincidental hypervascularity was found in 54 of 96 nodules (56.2%), and all were malignant upon biopsy (100% positive predictive value). Twenty-four (25%) had negative results with both techniques (non-vascular thrombus). Biopsies showed HCC in five non-vascular thrombi (5.3% of all thrombi) and in 13 of 18 thrombi with a hypervascularity result from only one technique.

CONCLUSIONS

The EASL/AASLD extension criteria for non-invasive diagnosis of malignant thrombosis were satisfied in 75.2% of malignant thrombi; thus, a biopsy is frequently required in this setting. However, in the presence of coincidental hypervascularity of a thrombus with both techniques, a biopsy is not required (absolute positive predictive value for malignancy). Relying on imaging techniques in thrombi could miss the diagnosis of malignant portal invasion in up to 24.9% of cases.

[Radiological diagnosis of hepatocellular carcinoma in 2010]

The aim of diagnosis imaging is to detect hepatocellular carcinoma at an early stage, when a curative treatment is available. Biopsy is no longer required prior to treatment, and diagnosis of hepatocellular carcinoma is heavily dependent of imaging characteristics. Therefore, the purpose of this article is to describe the typical features of small (<20mm) and larger hepatocellular carcinomas with noninvasive diagnostic criteria, including ultrasound, computed tomography and MRI. Advances in these imaging modalities have greatly improved the detection of small hepatic nodules on liver cirrhosis, including the different steps of carcinogenesis, from regenerative to dysplastic nodules, and we emphasize the difficulties of radiological differentiation of precancerous lesions and small hepatocellular carcinomas.

Cost analysis of recall strategies for non-invasive diagnosis of small hepatocellular carcinoma

BACKGROUND

Which is the least expensive recall policy for nodules in the cirrhotic liver remains unclear.

AIM

Aim of the study was to analyze the costs of different recall diagnostic strategies of hepatocellular carcinoma (HCC) on cirrhosis on a real series of patients.

METHODS

75 consecutive small liver nodules (10-30 mm) detected at conventional ultrasonography in 60 patients with cirrhosis were submitted to contrast-enhanced ultrasound, computed tomography and gadolinium-magnetic resonance imaging with a final diagnosis established according to the latest guidelines which include different strategies for nodules 10-19 mm or > or =20mm. The actual costs required to fully characterise any nodule and staging HCC in every patient, if one or the other imaging modality had been used as the first diagnostic step, were calculated. The theoretical hypothesis that each nodule was present in each patient was also investigated from an economical point of view.

RESULTS

The recall strategy starting with contrast-enhanced ultrasound plus computed tomography is the least expensive strategy for patients with at least one nodule 10-19 mm in size, in nearly all combinations (single or double nodules). In patients with single 20-30 mm nodules the least expensive strategy is to start with computed tomography and to use contrast-enhanced ultrasound as a second step technique.

CONCLUSIONS

wider use of contrast-enhanced ultrasound has the potential to save healthcare costs after first ultrasound detection of a single small nodule in cirrhosis.

The impact of vascular and nonvascular findings on the noninvasive diagnosis of small hepatocellular carcinoma based on the EASL and AASLD criteria

OBJECTIVES

Noninvasive criteria for the diagnosis of hepatocellular carcinoma (HCC) in cirrhosis, recommended by the European Association for the Study of Liver (EASL) in 2001 and by the American Association for the Study of Liver Diseases (AASLD) in 2005, have left a number of small liver neoplastic nodules undefined. We designed this prospective study in 2003 with the aims of assessing the diagnostic contribution of vascular contrast-enhanced techniques and investigating the possible additional contribution of superparamagnetic iron oxide magnetic resonance (SPIO-MR) in this setting.

METHODS

Between 2003 and 2005, 75 consecutive small (10-30 mm) liver nodules detected at ultrasonography in 60 patients with cirrhosis were prospectively submitted to contrast-enhanced ultrasound (CEUS), helical-computed tomography (helical-CT), and gadolinium magnetic resonance (gad-MR), each blinded to the other. A total of 68 nodules were also studied with SPIO-MR at the same time as gad-MR.

RESULTS

Using the EASL noninvasive criteria, the diagnosis of HCC was established in 44 of 55 (80%) nodules with a final diagnosis of HCC. Gad-MR was the most sensitive technique for detecting the typical vascular pattern. SPIO-MR showed a pattern consistent with HCC in 5 of 10 HCCs, not satisfying the EASL noninvasive criteria, and was negative in 17 of 18 (94.4%) nonmalignant nodules. The review of the present case series according to the AASLD criteria for the noninvasive diagnosis of HCC yielded a sensitivity rate of 81.8%.

DISCUSSION

This study shows that both EASL and AASLD noninvasive recall strategies for nodules of 10-30 mm in the cirrhotic liver, based on the vascular pattern of nodules, have a false-negative rate of approximately 20%. SPIO-MR may increase the diagnostic potential of noninvasive techniques, contributing to the diagnosis of HCC lacking a typical vascular pattern.

MRI versus 64-row MDCT for diagnosis of hepatocellular carcinoma

AIM: To compare the diagnostic capability of multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) for the detection of hepatocellular carcinoma (HCC) tumour nodules and their effect on patient management.

METHODS: A total of 28 patients (25 male, 3 female, mean age 67 ± 10.8 years) with biopsy-proven HCC were investigated with 64-row MDCT (slice 3 mm native, arterial and portal-venous phase, 120 mL Iomeprol, 4 mL/s, delay by bolus trigger) and MRI (T1fs fl2d TE/TR 2.72/129 ms, T2tse TE/TR 102/4000 ms, 5-phase dynamic contrast-enhanced T1fs fl3d TE/TR 1.56/4.6, Gadolinium-DTPA, slice 4 mm). Consensus reading of both modalities was used as reference. Tumour nodules were analyzed with respect to number, size, and location.

RESULTS: In total, 162 tumour nodules were detected by consensus reading. MRI detected significantly more tumour nodules (159 vs 123, P < 0.001) compared to MDCT, with the best sensitivity for early arterial phase MRI. False-negative CT findings included nodules ≤ 5 mm ( n = 5), ≤ 10 mm ( n = 17), ≤ 15 mm ( n = 12 ), ≤ 20 mm ( n = 4 ), and 1 nodule > 20 mm. MRI missed 2 nodules ≤ 10 mm and 1 nodule ≤ 15 mm. On MRI, nodule diameters were greater than on CT (29.2 ± 25.1 mm, range 5-140 mm vs 24.1 ± 22.7 mm, range 4-129 mm, P < 0.005). In 2 patients, MDCT showed only unilobar tumour spread, whereas MRI revealed additional nodules in the contralateral lobe. Detection of these nodules could have changed the therapeutic strategy.

CONCLUSION: Contrast-enhanced MRI is superior to 64-row MDCT for the detection of HCC nodules. Patients should be allocated to interventional or operative treatment according to a dedicated MRI-protocol.

Receiver operating characteristic analysis of diffusion-weighted magnetic resonance imaging in differentiating hepatic hemangioma from other hypervascular liver lesions

PURPOSE

To evaluate the role of diffusion-weighted imaging in differentiating between hepatic hemangiomas, both typical and atypical, and other hypervascular liver lesions.

METHODS

Retrospective review of 182 hypervascular liver lesions in 117 patients was performed. Diffusion and contrast-enhanced magnetic resonance imaging were performed using a 1.5-T unit. Imaging protocol consisted of T2-weighted fast spin-echo images, breath-hold diffusion-weighted echo-planar images, and breath-hold unenhanced and contrast-enhanced T1-weighted 3-dimensional fat-suppressed spoiled gradient-echo images in the arterial phase (20 seconds) and portal venous phase (60 seconds). Signal intensity changes and apparent diffusion coefficient (ADC) values were evaluated for all lesions. Unpaired t test was used to compare the mean ADC values for different lesions, and statistical significance was set at P < 0.01. Receiver operating characteristic analysis was used to determine the accuracy of diffusion-weighted imaging in differentiating hemangiomas from other hypervascular liver lesions.

RESULTS

Lesions included typical and atypical hemangioma (n = 38), hepatocellular carcinoma (HCC; n = 58), focal nodular hyperplasia (FNH; n = 22), and neuroendocrine tumor metastasis (NET; n = 64) with a mean tumor size of 5.3 cm. Mean ADC value for hemangioma, HCC, FNH, and NET was 2.29 x 10(-3), 1.55 x 10(-3), 1.65 x 10(-3), and 1.43 x 10(-3) mm2/s, respectively. There was a statistically significant difference in the ADC value of hemangioma compared with that of FNH (P < 0.001), HCC (P < 0.001), and NET (P < 0.001), respectively. The area under the receiver operating characteristic curve was 0.91.

CONCLUSIONS

Diffusion-weighted magnetic resonance imaging and ADC maps can provide rapid quantifiable information to differentiate typical and atypical hemangiomas from other hypervascular liver lesions.

MR Imaging of hepatocellular carcinoma in the cirrhotic liver: challenges and controversies

The incidence of hepatocellular carcinoma (HCC) is expected to increase in the next 2 decades, largely due to hepatitis C infection and secondary cirrhosis. HCC is being detected at an earlier stage owing to the implementation of screening programs. Biopsy is no longer required prior to treatment, and diagnosis of HCC is heavily dependent on imaging characteristics. The most recent recommendations by the American Association for the Study of Liver Diseases (AASLD) state that a diagnosis of HCC can be made if a mass larger than 2 cm shows typical features of HCC (hypervascularity in the arterial phase and washout in the venous phase) at contrast material-enhanced computed tomography or magnetic resonance (MR) imaging or if a mass measuring 1-2 cm shows these features at both modalities. There is an ever-increasing demand on radiologists to detect smaller tumors, when curative therapies are most effective. However, the major difficulty in imaging cirrhosis is the characterization of hypervascular nodules smaller than 2 cm, which often have nonspecific imaging characteristics. The authors present a review of the MR imaging and pathologic features of regenerative nodules and dysplastic nodules and focus on HCC in the cirrhotic liver, with particular reference to small tumors and lesions that may mimic HCC. The authors also review the sensitivity of MR imaging for the detection of these tumors and discuss the staging of HCC and the treatment options in the context of the guidelines of the AASLD and the imaging criteria required by the United Network for Organ Sharing for transplantation. MR findings following ablation and chemoembolization are also reviewed.

Optimizing staging for hepatocellular carcinoma before liver transplantation: A retrospective analysis of the UNOS/OPTN database

Assignment of liver allocation priority for hepatocellular carcinoma is predicated on accurate imaging staging. We analyzed radiographically defined stage (radiologic stage [RS]) at listing and most recent extension and pathologic stage (PS) data from 789 liver transplant recipients for whom no pretransplant ablative treatment was given. There were no predetermined imaging or pathological protocols in this retrospective analysis of wait list data. Seventy-two (9.1%), 690 (87.5%), and 27 (3.4%) were listed as stage 1, 2 and >2, respectively. Computed tomography (CT) scan alone (46.4%), magnetic resonance image scan alone (37.1%), ultrasound alone (1.3%), and multiple imaging studies (15.2%) were used with no difference in time to transplant for listing or most recent scan among the recipient groups. Overall accuracy (RS = PS) was 44.1% and was not different if original listing RS or most recent RS was used for comparison with PS. No one type of imaging technique had superior accuracy (P = 0.13); however, CT scan used alone or in combination compared to not being used at all, had higher odds of being accurate (odds ratio [OR] 1.38 [1.03-1.84], P = 0.031). In addition, imaging done less than 90 days before transplant had higher odds of being accurate (OR 1.49 [1.06-2.08], P = 0.019) as did RS = 2 or 3 (OR 5.56 [2.70-11.11], P < 0.0001). We observed considerable variation in RS accuracy among the United Network for Organ Sharing and Organ Procurement and Transplantation Network regions that is unexplained. In conclusion, current imaging requirements for RS prior to liver transplantation are unacceptably inaccurate. Future policy should require more accurate modalities or combinations of techniques.

Magnetic Resonance Imaging Appearance of Well-differentiated Hepatocellular Carcinoma

OBJECTIVE

To investigate the magnetic resonance imaging (MRI) features of well-differentiated hepatocellular carcinoma (HCC).

METHODS

We reviewed the MRI of 32 patients with 33 pathologically confirmed well-differentiated HCC. The MRI protocol included T2-weighted imaging with and without fat saturation, dual-phase T1-weighted imaging, and gadolinium-enhanced dynamic study. The signal intensity of each lesion was categorized as hyperintense, isointense, and hypointense with reference to the surrounding liver parenchyma.

RESULTS

Thirty-one (93.9%) of 33 well-differentiated HCC were demonstrated on the MRI. The remaining 2 were isointense in all magnetic resonance sequences and, therefore, could not be identified. Most of them were hyperintense (n = 15 [45.4%]) or isointense (n = 16 [48.5%]) on T1-weighted imaging, and hyperintense (n = 12 [36.4%]) or isointense (n = 17 [51.5%]) on T2-weighted imaging. On the dynamic study, 17 lesions (51.5%) were enhanced.

CONCLUSIONS

MRI may identify most well-differentiated HCC; however, the imaging appearance is diverse. Biopsy should be performed if magnetic resonance study is inconclusive.

Higher lesion conspicuity for SENSE dynamic MRI in detecting hypervascular hepatocellular carcinoma: analysis through the measurements of liver SNR and lesion-liver CNR comparison with conventional dynamic MRI

The aim of our study was to compare the signal-to-noise ratio (SNR) of liver parenchyma and the contrast-to-noise ratio (CNR) of hypervascular hepatocellular carcinoma (HCC) between conventional and SENSE dynamic MRI. Thirty-one consecutive patients who were strongly suspected of having HCC were enrolled in our study. The subjects consisted of 20 men and 11 women aged 52 years to 79 years (mean 66.8 years). Dynamic MRI was performed for each patient, with SENSE (SENSE MRI) and without SENSE (conventional MRI) on separate days. For the quantitative analysis, the liver SNR and the lesion-liver CNR of 25 hypervascular HCCs detected on both conventional and SENSE dynamic MRI were measured. The liver SNR of the arterial phase and the portal venous phase was 84.1+/-24.7 and 104.7+/-34.3, respectively, in conventional MRI, while it was 62.9+/-19.5 and 44.5+/-18.2, respectively, in SENSE MRI. SENSE MRI showed a statistically significantly lower SNR than conventional MRI (P<0.01). The lesion-liver CNR was 26.3+/-15.9 in conventional MRI and 39.0+/-19.6 in SENSE MRI. The lesion-liver CNR in SENSE MRI was significantly higher than in conventional MRI (P<0.01). The SNR in SENSE MRI is significantly lower than in conventional MRI, although the lesion CNR is significantly higher than in conventional MRI.

Characterization of small nodules in cirrhosis by assessment of vascularity: the problem of hypovascular hepatocellular carcinoma

In a prospective study, we examined the impact of arterial hypervascularity, as established by the European Association for the Study of the Liver (EASL) recommendations, as a criterion for characterizing small (1-3 cm) nodules in cirrhosis. A total of 72 nodules (1-2 cm, n = 41; 2.1-3 cm, n = 31) detected by ultrasonography in 59 patients with cirrhosis were included in the study. When coincidental arterial hypervascularity was detected at contrast perfusional ultrasonography and helical computed tomography, the lesion was considered to be hepatocellular carcinoma (HCC) according to EASL criteria. When one or both techniques showed negative results, ultrasound-guided biopsy was performed. In cases with negative results for malignancy or high-grade dysplasia, biopsy was repeated when an increase in size was detected at the 3-month follow-up examination. Coincidental hypervascularity was found in 44 of 72 nodules (61%; 44% of 1-2-cm nodules and 84% of 2-3-cm nodules). Fourteen nodules (19.4%) had negative results with both techniques (hypovascular nodules). Biopsy showed HCC in 5 hypovascular nodules and in 11 of 14 nodules with hypervascularity using only one technique. All nodules larger than 2 cm finally resulted to be HCC. Not satisfying the EASL imaging criteria for diagnosis were 38% of HCCs 1 to 2 cm (17% hypovascular) and 16% of those 2 to 3 cm (none hypovascular). In conclusion, the noninvasive EASL criteria for diagnosis of HCC are satisfied in only 61% of small nodules in cirrhosis; thus, biopsy frequently is required in this setting. Relying on imaging techniques in nodules of 1 to 2 cm would miss the diagnosis of HCC in up to 38% of cases. Any nodule larger than 2 cm should be regarded as highly suspicious for HCC.

Imaging the liver

Imaging of the liver is undertaken for the detection and characterization of suspected primary or secondary neoplasms, prior to planning a surgery or chemotherapy pump placement, for assessing treatment response, for evaluating biliary pathology, and for screening for liver neoplasms in high-risk groups. In this article, we review the advantages and disadvantages of various imaging modalities in the evaluation of the liver and formulate guidelines for the imaging of common clinical indications. A brief review of imaging findings in focal and diffuse liver disease is also presented.

Microvessel density of malignant and benign hepatic lesions and MRI evaluation

AIM: To study the difference of microvessel density (MVD) between malignant and benign hepatic lesions and study the relationship between MVD and dynamic enhanced magnetic resonance imaging (MRI) for evaluation of microvessels within malignant and benign hepatic lesions.

METHODS: A total of 265 specimens of hepatocellular carcinoma (HCC), 122 cirrhosis tissues and 22 hepatic benign lesions were enrolled for MVD by immunohistochemistry on tissue microarray, of which 49 underwent MRI examination before surgery, then contrast-to-noise ratios (CNR) and enhancement index (EI) in all the phases were calculated. Pearson correlation was performed for correlation analysis between CNR, EI and MVD.

RESULTS: MVD of HCC was 22.7 ± 15.8 (mean ± SD), which was obviously higher than that of cirrhosis tissue (8.3 ± 7.6, P < 0.01), but was not statistically different from that of benign lesions (31.3 ± 22.7, P>0.05). Among HCC, MVD of gradesI-II was 29.9 ± 18.6, which was much higher than those of grade III (22.2 ± 18.2, P < 0.01) and gradeIV (22.9 ± 19.0, P < 0.01). MVD of HCC (P = 0.018) and of benign lesions (P = 0.014) were both correlative with CNR in arterial phase.

CONCLUSION: Neoangiogenesis is an important feature for malignant tumor, and MVD may act as a biological marker in differentiating malignant from benign hepatic lesions. Dynamic enhanced MRI, especially image in arterial phase, may act as an MVD evaluation criterion for malignant and benign hepatic lesions.

MRI angiography is superior to helical CT for detection of HCC prior to liver transplantation: an explant correlation

Helical computerized tomography (CT) and magnetic resonance imaging (MRI) are used for staging of hepatocellular carcinoma (HCC) prior to curative treatments but underestimate tumor extension in 30% to 50% of cases when compared with pathologic explants. This study compares a new technology, MRI angiography (MRA), with triphasic helical CT in detection of HCC. Fifty cirrhotic patients, 29 with HCC, undergoing liver transplantation were analyzed. MRA was performed with a 3-D breath-hold fast spoiled gradient-echo sequence by using an effective section thickness of 2 to 2.5 mm. The gold standard was the pathologic examination (liver cut into 5-mm slices). One hundred twenty-seven lesions were identified at the explant: 76 HCC, 13 high-grade dysplastic nodules, 31 macroregenerative nodules, 7 hemangiomas. Diameter of the main HCC nodules was 29 +/- 14 mm and 11 +/- 7 mm for the 47 additional nodules. On a per nodule basis, sensitivity of MRA was superior to CT (58/76 [76%] vs. 43/70 [61%], respectively, P =.001). Sensitivity of MRA for detection of additional nodules decreased with size (>20 mm: 6/6 [100%]; 10-20 mm: 16/19 [84%]; <10 mm: 7/22 [32%]) and was superior to CT for nodules 10 to 20 mm (84% vs. 47%, P =.016). Nonspecific hypervascular nodules >5 mm at MRA were HCC in two thirds of the cases. In conclusion, MRA has a high diagnostic accuracy for HCC > or =10 mm and is more sensitive than triphasic helical CT in nodules sized 10 to 20 mm. MRA is the optimal technique for HCC staging prior to curative therapies.

Developing a prediction rule to assess hepatic malignancy in patients with cirrhosis

OBJECTIVE

The objectives of our study were to identify independent clinical, demographic, and MR imaging correlates of malignancy in patients with cirrhosis and to develop a predictive model based on identified correlates of malignancy.

MATERIALS AND METHODS

Sixty examinations of 58 patients with biopsy proof of lesions suggestive of hepatocellular carcinoma on MR imaging were retrospectively reviewed. The signal intensity of the lesion on T2-weighted imaging and dynamic gadolinium-enhanced imaging, the size of the lesion, and the number of suspicious lesions were recorded; in addition, patient age and sex, alpha-fetoprotein level, and hepatitis C viral genotype were noted. The association between malignancy and each predictor variable was evaluated using the chi-square test or the two-group t test. The final logistic regression model included the variables that were shown to have a significant association with malignancy and the clinically relevant predictors. We used the adjusted odds ratios to measure the strength of each association. The discriminant ability of the model for detecting hepatic malignancy was assessed using receiver operating characteristic curve analysis.

RESULTS

The prevalence of hepatic malignancy in our study population was 64%. The area under the receiver operating characteristic curve for the logistic regression model was 0.82. Venous washout (odds ratio = 9.2), alpha-fetoprotein level (odds ratio = 3.2), and number of lesions (odds ratio = 1.5) were significant predictors for malignancy (p < 0.05). When arterial enhancement and venous washout were either both present or both absent, alpha-fetoprotein level contributed little to the prediction of malignancy.

CONCLUSION

The MR characteristics of hepatic lesions during the dynamic venous phase in conjunction with the serum alpha-fetoprotein level and number of lesions are predictors of hepatic malignancy. The use of these predictors can facilitate explicit estimation of malignancy in individuals with underlying cirrhosis, potentially improving clinical decision-making.