Hepatocellular carcinoma in cirrhosis: enhancement patterns at dynamic gadolinium- and superparamagnetic iron oxide-enhanced T1-weighted MR imaging

How to stop using gadolinium chelates for magnetic resonance imaging: clinical-translational experiences with ferumoxytol

Gadolinium chelates have been used as standard contrast agents for clinical MRI for several decades. However, several investigators recently reported that rare Earth metals such as gadolinium are deposited in the brain for months or years. This is particularly concerning for children, whose developing brain is more vulnerable to exogenous toxins compared to adults. Therefore, a search is under way for alternative MR imaging biomarkers. The United States Food and Drug Administration (FDA)-approved iron supplement ferumoxytol can solve this unmet clinical need: ferumoxytol consists of iron oxide nanoparticles that can be detected with MRI and provide significant T1- and T2-signal enhancement of vessels and soft tissues. Several investigators including our research group have started to use ferumoxytol off-label as a new contrast agent for MRI. This article reviews the existing literature on the biodistribution of ferumoxytol in children and compares the diagnostic accuracy of ferumoxytol- and gadolinium-chelate-enhanced MRI. Iron oxide nanoparticles represent a promising new class of contrast agents for pediatric MRI that can be metabolized and are not deposited in the brain.

Evaluation of quantitative parameters of dynamic contrast-enhanced magnetic resonance imaging in qualitative diagnosis of hepatic masses

BACKGROUND

To explore the value of parameters of multiphase dynamic contrast-enhanced magnetic resonance imaging (MDCE-MRI) in the qualitative diagnosis of hepatic masses.

METHODS

Eighty patients with hepatic masses were retrospectively analyzed. All the patients underwent MDCE-MRI at 3.0 T MR before treatment. Mean enhancement time (MET), positive enhancement integral (PEI), a maximum slope of increase (MSI), and a maximum slope of decrease (MSD) were measured.

RESULTS

There were significant differences between benign and malignant hepatic masses with respect to MET, PEI, and MSI values. The PEI and MSI values between hemangiomas, hepatocellular carcinomas (HCCs), cholangiocarcinomas, and metastatic tumors had significant differences. The MSD value between metastatic tumors, HCCs, and hemangiomas were significantly different. The area under the curve (AUC) values of the receiver operator characteristic curves for MET, PEI, and MSI were 0.70, 0.72, and 0.80, respectively. The specificity of MET, PEI, and MSI were all 77%, and the sensitivities of MSI was the highest, of which was 82.40%. Logistic regression analysis showed the regression equation to be P = 1/[1 + e^{0.008 × 1 + 0.007 × 2-6.707}], and taking the Youden index maximum points as a diagnostic point was 0.2946.

CONCLUSION

Some parameters of MDCE-MRI have significant roles in differentiating hepatic masses.

Imaging Features of Gadoxetic Acid-enhanced and Diffusion-weighted MR Imaging for Identifying Cytokeratin 19-positive Hepatocellular Carcinoma: A Retrospective Observational Study

Purpose To determine the preoperative magnetic resonance (MR) imaging findings potentially most useful for predicting cytokeratin 19 (CK19)-positive hepatocellular carcinoma (HCC) and to evaluate the prognosis after curative resection in patients with a single HCC lesion positive for CK19 compared with patients with HCC who are negative for CK19. Materials and Methods The institutional review board approved this study and waived the requirement for informed consent. Two hundred four patients with CK19-negative HCC and 38 with CK19-positive HCC who underwent curative resection after gadoxetic acid-enhanced and diffusion-weighted MR imaging were retrospectively evaluated in a single institution. Two radiologists evaluated preoperative findings at MR imaging. Significant findings for differentiating the two groups were identified at univariate and multivariate analyses. By using receiver operating characteristic analysis, the optimal cut-off values for quantitative variables were determined. Recurrence-free survival rates after surgery were also compared between groups. Results At multivariate analysis, irregular tumor margin (P = .024), arterial rim enhancement (P < .001), lower tumor-to-liver signal intensity (SI) ratio on hepatobiliary phase (HBP) images (≤0.522; P = .01), and lower tumor-to-liver apparent diffusion coefficient (ADC) ratio (≤0.820; P < .001) were independent significant factors to predict CK19-positive HCC. When three of these four criteria were combined, 63.2% (24 of 38; 95% confidence interval: 46.0%, 78.2%) of CK19-positive HCCs were identified with a specificity of 90.7% (185 of 204; 95% confidence interval: 46.0%, 78.2%). When all four criteria were satisfied, specificity was 99.5% (203 of 204; 95% confidence interval: 97.3%, 100%). Recurrence-free survival rates were significantly lower in patients with CK19-positive HCCs compared with those with CK19-negative HCCs after curative resection (63.9% vs 90.0% at 1 year, 63.9% vs 79.9% at 2 years, and 54.8% vs 70.2% at 3 years, P = .001 by log-rank test). Conclusion At gadoxetic acid-enhanced and diffusion-weighted MR imaging, irregular margin, arterial phase rim enhancement, lower tumor-to-liver ADC ratio, and lower tumor-to-liver SI ratio at HBP imaging may be helpful to predict CK19-positive HCC with early recurrence (<2 years) after curative resection. ^© RSNA, 2017 Online supplemental material is available for this article.

Diagnosis of Hepatocellular Carcinoma with Gadoxetic Acid-Enhanced MRI: 2016 Consensus Recommendations of the Korean Society of Abdominal Radiology

Diagnosis of hepatocellular carcinoma (HCC) with gadoxetic acid-enhanced liver magnetic resonance imaging (MRI) poses certain unique challenges beyond the scope of current guidelines. The regional heterogeneity of HCC in demographic characteristics, prevalence, surveillance, and socioeconomic status necessitates different treatment approaches, leading to variations in survival outcomes. Considering the medical practices in Korea, the Korean Society of Abdominal Radiology (KSAR) study group for liver diseases has developed expert consensus recommendations for diagnosis of HCC by gadoxetic acid-enhanced MRI with updated perspectives, using a modified Delphi method. During the 39th Scientific Assembly and Annual Meeting of KSAR (2016), consensus was reached on 12 of 16 statements. These recommendations might serve to ensure a more standardized diagnosis of HCC by gadoxetic acid-enhanced MRI.

Description of focal liver lesions with Gd-EOB-DTPA enhanced MRI

Imaging procedures play a fundamental role in the therapeutic management of focal liver lesions. The goals of imaging are to detect and correctly characterize focal liver lesions. This review highlights the performances of newer, liver-specific, contrast media in the diagnosis of focal liver lesions, particularly Gd-EOB-DTPA (Primovist), the most frequently used liver specific contrast media. It has been shown, in different papers, that Gd-EOB-DTPA has better performances compared to either triphasic contrast enhanced computed tomography or dynamic MRI in both detection and characterization of hepatocellular carcinoma on the cirrhotic liver. Therefore liver MRI with Primovist is considered, in many centers, the "state-of-the-art" imaging examination of the liver before surgery or liver transplantation. Gd-EOB-DTPA is also useful in the differential diagnosis of benign hypervascular focal liver lesions such as adenomas or focal nodular hyperplasias.

Hepatocellular carcinoma in Budd-Chiari syndrome: enhancement patterns at dynamic gadolinium-enhanced T1-weighted MR imaging

The objective of this study was to analyze the enhancement patterns at dynamic gadolinium-enhanced T1-weighted MR imaging in patients of Hepatocellular Carcinoma (HCC) with associated Budd-Chiari syndrome (BCS). The MR imaging findings in 10 patients of HCC with associated BCS were compared to those of 32 other patients of HCC without BCS. During the arterial phase, significantly more lesions with BCS were hyperintense than lesions without BCS; during the equilibrium phase, significantly more lesions with BCS were slightly hyperintense or isointense than lesions without BCS (P < 0.05 for both). For HCC, contrast enhancement on MRI shows different enhancement patterns between patients of HCC with associated BCS and those without BCS.

Radiological diagnosis of hepatocellular carcinoma

Diagnosis of hepatocellular carcinoma (HCC) still remains a challenging issue. In the setting of liver cirrhosis, international guidelines have set the noninvasive criteria for HCC diagnosis, represented by the detection of contrast hyperenhancement in the arterial phase (wash-in) and hypoenhancement in the portal or delayed phase (wash-out) with dynamic multi-detector computer tomography or magnetic resonance (MR) imaging. Although highly specific, this typical enhancement pattern has relatively low sensitivity, since approximately one-third of HCC nodules are characterized by atypical enhancement patterns. In atypical HCC nodules larger than 1 cm, the majority of international guidelines recommend liver biopsy. However, there is an increasing interest in exploiting new noninvasive diagnostic tools, to increase the sensitivity of radiological diagnosis of HCC. Diffusion-weighted MR imaging and MR hepatobiliary contrast agents may represent useful tools for the detection and characterization of borderline hypovascular lesions by providing functional information such as water molecule motion in diffusion-weighted imaging and residual hepatobiliary function, which can be impaired early during the course of hepatocarcinogenesis. Also, dual-energy computed tomography (CT) represents an interesting new CT technology that could increase detectability and conspicuity of hypervascular lesions, thus possibly improving CT sensitivity in small HCCs. However, more data and further developments are needed to verify the usefulness of these new technologies in the diagnosis of HCC and to translate these recent advances into clinical practice.

The effects of iron oxide incorporation on the chondrogenic potential of three human cell types

Non-invasive monitoring of living cells in vivo provides an important tool in the development of cell-based therapies in cartilage tissue engineering. High-resolution magnetic resonance imaging (MRI) has been used to monitor target cell populations in vivo. However, the side-effects on cell function of the labelling reagents, such as superparamagnetic iron oxide (SPIO), are still unclear. This study investigated the effect of SPIO particles on the chondrogenic differentiation of human bone marrow stromal cells (HBMSCs), neonatal and adult chondrocytes in vitro. Cells were labelled with SPIO for 24 h and chondrogenesis induced in serum-free medium including TGFβ3. For labelled/unlabelled cells, viability, morphology and proliferation were determined using CellTracker™ Green and PicoGreen dsDNA assays. The expression of SOX9, COL2A1 and ACAN was investigated using qRT-PCR after 2, 7 and 14 days. The results showed that viability was unaffected in all of the cells but cell morphology changed towards a 'stretched' phenotype following SPIO uptake. Cell proliferation was reduced only for labelled neonatal chondrocytes. SOX9 and COL2A1 expression decreased at day 2 but not at days 7 and 14 for labelled HBMSCs and adult chondrocytes; ACAN expression was unaffected. In contrast, SOX9 and COL2A1 expression were unaffected in labelled neonatal chondrocytes but a decrease in ACAN expression was seen at day 14. The results suggest that downregulation of chondrogenic genes associated with SPIO labelling is temporary and target cell-dependent. Resovist® can be used to label HBMSCs or mature chondrocytes for MR imaging of cells for cartilage tissue engineering.

The usefulness of diffusion-weighted imaging in the characterization of liver lesions in patients with cirrhosis

AIM

To evaluate if diffusion-weighted imaging (DWI) is useful in characterizing liver lesions in patients with cirrhosis.

MATERIALS AND METHODS

A retrospective review revealed 37 patients with cirrhosis who had 41 histologically proven hepatocellular carcinoma (HCC) lesions. Another 20 patents with cirrhosis had 29 solid nodules that remained stable for at least 12 months and were deemed to be benign hepatic nodules (BHN). Of the HCC lesions, 14 were well-differentiated (WD HCC), 20 were moderately differentiated, and seven were poorly differentiated histology. For all lesions, two reviewers analysed signal characteristics and made apparent diffusion coefficient value (ADC) measurements.

RESULTS

Visual analysis of DWI was useful in that no HCC was hypointense and no BHN was hyperintense to liver. Visual analysis of DWI was not useful in separating WD HCC from higher grades. There was substantial overlap in ADC values of the HCC and BHN. Among HCC lesions, ADC values of more than 0.99 × 10(-3) mm(2)/s had sensitivity and specificity of 85% and 86% for reviewer 1, and 63% and 64% for reviewer 2 in diagnosing WD HCC.

CONCLUSIONS

ADC measurements of BHN were higher than that of HCC, and the ADC values of WD HCC were higher than that of more aggressive grades of HCC. However, quantitative measurements may not help in determining the histological grade of individual cases of HCC.

Added value of subtraction imaging in detecting arterial enhancement in small (<3 cm) hepatic nodules on dynamic contrast-enhanced MRI in patients at high risk of hepatocellular carcinoma

OBJECTIVES

To determine the importance of arterial enhancement in diagnosing small (<3 cm) hepatocellular carcinomas (HCCs) and to evaluate the added value of dynamic subtraction magnetic resonance imaging (MRI) in detecting arterial enhancement in small (<3 cm) hepatic nodules in high-risk patients.

METHODS

Eighty-six patients with 135 pathologically confirmed small (<3 cm) hepatic nodules (104 HCCs, 31 benign nodules) underwent MRI before curative surgery. Arterial enhancement was determined by three methods: (1) visual assessment of the arterial phase alone, (2) visual comparison of the arterial phase with the unenhanced phase and (3) additional review of subtraction images. The diagnostic performance of each method was calculated and compared using generalised estimating equations analysis.

RESULTS

Arterial enhancement demonstrated high positive predictive value (PPV) (96.5-98.9 %) and specificity (90.3-96.8 %), but low negative predictive value (NPV) (54.6-62.5 %) and intermediate sensitivity (76-79.8 %) for diagnosing small HCCs. Diagnostic performance was highest for subtraction imaging. There were significant differences among the three methods in sensitivity (P = 0.04), accuracy (P = 0.044), PPV (P < 0.001) and NPV (P = 0.024), but not in specificity (P = 0.167).

CONCLUSION

The accurate detection of arterial enhancement in small hepatic nodules is important for diagnosing HCC and may be enhanced by subtraction imaging.

Liver MRI and histological correlates in chronic liver disease on multiphase gadolinium-enhanced 3D gradient echo imaging

PURPOSE

To evaluate intrinsic hepatic enhancement patterns on multiphase, gadolinium-enhanced, fat-suppressed, 3D T1-weighted, gradient echo magnetic resonance imaging (MRI) as a quantitative correlate for severity of pathological changes in chronic liver disease (CLD).

MATERIALS AND METHODS

This study was HIPAA-compliant and Institutional Review Board-approved. In all, 75 patients were studied by contrast-enhanced multiphase abdominal MRI. CLD patients had liver histology correlation derived from right lobe liver biopsies. Contrast-enhanced arterial- and delayed-phase 3D gradient recalled echo (GRE) liver MRI were scored using feature categorization templates to quantify enhancement patterns by three independent readers. Liver histopathology was staged/graded for fibrosis/inflammation using the Scheuer system. Statistical testing for MRI histology correlates used a Pearson's product moment correlation and a Wilcoxon-Mann-Whitney two-sample rank-sum test. Reader agreement was analyzed by a modified Fleiss' kappa test.

RESULTS

MRI histology correlation was high for delayed-phase MRI versus fibrosis stage (95% confidence interval [CI] 0.941 < r < 0.976, P = 5 × 10(-7)), but lower for all other comparisons (delayed-phase vs. inflammation and arterial-phase vs. inflammation or fibrosis all showed a CI no greater than 0.64). Paired testing between delayed-phase MRI score and histology fibrosis staging incremental levels was significant (from P < 10(-2) to P < 10(-5)).

CONCLUSION

A standard gadolinium-enhanced liver MRI may provide a correlate measure of hepatic fibrosis over a spectrum of severity.

Feasibility of semiquantitative liver perfusion assessment by ferucarbotran bolus injection in double-contrast hepatic MRI

PURPOSE

To evaluate the feasibility of semiquantitative measurement of liver perfusion from analysis of ferucarbotran induced signal-dynamics in double-contrast liver MR-imaging (DC-MRI).

MATERIALS AND METHODS

In total 31 patients (21 men; 58 ± 10 years) including 18 patients with biopsy proven liver cirrhosis prospectively underwent clinically indicated DC-MRI at 1.5 Tesla (T) with dynamic T2-weighted gradient-echo imaging after ferucarbotran bolus injection. Breathing artefacts in tissue and input time curves were reduced by Savitzky-Golay-filtering and semiquantitative perfusion maps were calculated using a model free approach. Hepatic blood flow index (HBFI) and splenic blood flow index (SBFI) were determined by normalization of arbitrary perfusion values to the perfusion of the erector spinae muscle resulting in a semiquantitative perfusion measure.

RESULTS

In 30 of 31 patients the evaluated protocol could successfully be applied. Mean HBF was 7.7 ± 2.46 (range, 4.6-12.8) and mean SBF was 13.20 ± 2.57 (range, 8.5-17.8). A significantly lower total HBF was seen in patients with cirrhotic livers as compared to patients with noncirrhotic livers (P < 0.05). In contrast, similar SBF was observed in cirrhotic and noncirrhotic patients (P = 0.11).

CONCLUSION

Capturing the signal dynamics during bolus injection of ferucarbotran in DC-MRI of the liver allows for semiquantitative assessment of hepatic perfusion that may be helpful for a more precise characterisation of liver cirrhosis and focal liver lesions.

Different signal intensity at Gd-EOB-DTPA compared with Gd-DTPA-enhanced MRI in hepatocellular carcinoma transgenic mouse model in delayed phase hepatobiliary imaging

PURPOSE

To evaluate hyperintense Gd-DTPA- compared with hyper- and hypointense Gd-EOB-DTPA-enhanced magnet resonance imaging (MRI) in c-myc/TGFα transgenic mice for detecting hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Twenty HCC-bearing transgenic mice with overexpression of the protooncogene c-myc and transforming growth factor-alpha (TGF-α) were analyzed. MRI was performed using a 3-T MRI scanner and an MRI coil. The imaging protocol included Gd-DTPA- and Gd-EOB-DTPA-enhanced T1-weighted images. The statistically evaluated parameters are signal intensity (SI), signal intensity ratio (SIR), contrast-to-noise ratio (CNR), percentage enhancement (PE), and signal-to-noise ratio (SNR).

RESULTS

On Gd-DTPA-enhanced MRI compared with Gd-EOB-DTPA-enhanced MRI, the SI of liver was 265.02 to 573.02 and of HCC 350.84 to either hyperintense with 757.1 or hypointense with 372.55 enhancement. Evaluated parameters were SNR of HCC 50.1 to 56.5/111.5 and SNR of liver parenchyma 37.8 to 85.8, SIR 1.32 to 1.31/0.64, CNR 12.2 to 26.1/-30.08 and PE 42.08% to 80.5/-98.2%, (P < 0.05).

CONCLUSION

Gd-EOB-DTPA is superior to Gd-DTPA for detecting HCC in contrast agent-enhanced MRI in the c-myc/TGFα transgenic mouse model and there was no difference between the hyperintense or hypointense appearance of HCC. Either way, HCCs can easily be distinguished from liver parenchyma in mice.

Hepatocellular carcinoma: management of an increasingly common problem

Hepatocellular carcinoma (HCC) is a common cancer that typically occurs in the setting of cirrhosis and chronic hepatitis virus infections. Hepatitis B and C account for approximately 80% of cases worldwide. HCC is currently the fifth most common malignancy in men and the eighth in women worldwide; its incidence is increasing dramatically in many parts of the world. Recognition of those at risk and early diagnosis by surveillance with imaging, with or without serologic testing, are extremely important. Many highly effective and even curative therapies are now available and include resection, liver transplantation, and local ablation. Appropriate application of these interventions offers hope of prolonged survival to many patients with this otherwise lethal complication of liver disease.

Does the hepatocellular phase of gadobenate dimeglumine help to differentiate hepatocellular carcinoma in cirrhotic patients according to histological grade?

AIM

To assess the role of the hepatocellular phase on magnetic resonance imaging (MRI) following gadobenate in characterizing the grade of hepatocellular carcinoma (HCC) in cirrhotic patients.

MATERIALS AND METHODS

A retrospective review of the MRI database from October 2004 to February 2009, performed for this Institutional Review Board-approved and Health Insurance Portability and Accountability Act (HIPAA)-complaint study, revealed 237 cirrhotic patients with focal liver lesions. Patients who had both a hepatocellular phase after gadobenate and pathological confirmation of HCC were included. Forty-six patients with 73 HCC were analysed independently by two reviewers for signal characteristics. Absolute contrast-to-noise ratio (CNR) and enhancement ratio (ER) were calculated. Univariate analysis, stepwise logistic regression analysis, and receiver operating characteristic curves (ROC) were performed.

RESULTS

The mean age was 61.3 years (range 45 to 78 years). There were 11 females and 35 males, who had 22 well-differentiated (WD HCC), 35 moderately-differentiated (MD HCC), and 16 poorly-differentiated (PD HCC) hepatocellular carcinomas. On visual analysis of the hepatocellular phase, a hyperintense or isointense lesion had a sensitivity and specificity of 45% and 76%, respectively, for WD HCC. On quantitative analysis, the only significant predictor of the grade of HCC was the ER on the hepatocellular phase (p=0.019 and 0.001 for the two reviewers in logistic regression model). On ROC analysis, an ER of >13% was 47% sensitive and 89% specific in predicting WD HCC histology.

CONCLUSION

Although the hepatocellular phase of gadobenate may help to differentiate some cases of WD HCC from the more aggressive grades, there is overlap between the different grades on qualitative and quantitative analysis.

Superparamagnectic iron oxide-enhanced magnetic resonance for tumor surveillance in cirrhotic liver before liver transplantation with explanted liver correlation

OBJECTIVE

The aim of this study was to determine the accuracy of superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance imaging (MRI) in the detection of liver tumors in patients with liver cirrhosis before liver transplantation (LT).

PATIENTS AND METHODS

Twenty-one patients with moderate to severe liver cirrhoses (Child-Pugh score B or C) underwent SPIO-enhanced MRI before LT. SPIO-enhanced MRI was composed of SPIO-enhanced T1-weighted images, T2-weighted turbo spin-echo, and T2*-weighted sequences. The detection of malignant liver tumor was based on hepatic lesions that remain with hyper-signal intensity on SPIO-enhanced delayed T2 and T2*-weighted images. The imaging was compared with findings during histopathologic evaluation of the explanted liver.

RESULTS

Forty-two liver nodules were found in 16 of the 21 patients. Thirty-six malignant hepatic neoplasms were detected at histopathologic evaluation. SPIO-enhanced MRI depicted 30 of 36 malignant hepatic neoplasms. Patient-based analysis showed that the sensitivity, specificity, and accuracy of MRI were 93.75%, 100%, and 95.2%, respectively. For lesion-based analysis, the sensitivity, specificity, and the area under the receiver operating characteristic (ROC) curve were 90%, 100%, and 0.95, respectively, for lesions >2 cm.

CONCLUSIONS

SPIO-enhanced MRI can be used as an additional diagnostic tool for the detection and characterization of malignant tumors in cirrhotic livers. This diagnostic evaluation is accurate to triage patients for LT.

MR imaging of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a common malignancy typically associated with chronic liver disease and is a leading cause of mortality among these patients. Prognosis is improved when detected early. MRI is the best imaging examination for accurate diagnosis. Although arterial enhancement with delayed washout, increased T2-weighted signal intensity, delayed capsular enhancement, restricted diffusion, and tumor thrombus are typical features, not all lesions demonstrate these findings. The radiologist must be familiar with these typical imaging characteristics, and less common appearances and associated findings of HCC, and must be able to differentiate them from those of lesions that mimic HCC. Knowledge of therapeutic options and how those are related to imaging findings is imperative to assist clinicians in managing these patients.

Vascular invasion in hepatocellular carcinoma: is there a correlation with MRI?

OBJECTIVE

Hepatocellular carcinoma (HCC) is one of the commonest malignancies worldwide. Prognosis is predicted by size at diagnosis, vascular invasion and tumour proliferation markers. This study investigates if MRI features of histologically proven HCCs correlate with vascular invasion.

METHODS

Between 2006 and 2008, 18 consecutive patients, with a total of 27 HCCs, had comprehensive MRI studies performed at our institution within a median of 36 days of histology sampling. Each lesion was evaluated independently on MRI by 3 radiologists (blinded to both the radiology and histopathology reports) using a 5-point confidence scale for 23 specific imaging features. The mean of the rating scores across readers was calculated to determine interobserver consistency. The most consistent features were then used to examine the value of features in predicting vascular invasion, using a χ(2 )test for trend, having eliminated those features without sufficient variability.

RESULTS

22 of the 23 imaging features showed sufficient variability across lesions. None of these significantly correlated with the presence of vascular invasion, although a trend was identified with the presence of washout in the portal venous phase on MRI and the median size of lesions, which was greater with vascular invasion.

CONCLUSION

This study suggests that no single MRI feature accurately predicts the presence of vascular invasion in HCCs, although a trend was seen with the presence of washout in the portal venous phase post gadolinium. Larger prospective studies are required to investigate this further.

Comparison of portal venous and delayed phases of gadolinium-enhanced magnetic resonance imaging study of cirrhotic liver for the detection of contrast washout of hypervascular hepatocellular carcinoma

OBJECTIVE

To retrospectively compare portal venous phase (PVP) and delayed phase (DP) for the detection of tumor washout at gadobenate dimeglumine-enhanced liver magnetic resonance imaging (MRI) in cirrhotic patients with hypervascular hepatocellular carcinoma (HCC).

METHODS

Thirty-three patients with 55 HCCs underwent 1.5-T MRI by means of fat-suppressed T1-weighted sequence obtained before and after gadobenate dimeglumine administration, during early and late arterial phases, PVP (70 seconds), and DP (180 seconds). Detection rates of contrast washout of hypervascular HCCs and tumor-to-liver contrast on PVP and DP were measured and compared.

RESULTS

Among 54 hypervascular HCCs, washout was present in 24 (44%) of 54 tumors on PVP and in 44 (82%) of 54 on DP (P < 0.001). In 20 (37%) of 54 tumors, washout was deemed present only on DP. Delayed phase images yielded significantly higher mean tumor-to-liver contrast absolute values compared with PVP images (-24.5 [56.1] vs -9.3 [52.6], P = 0.001).

CONCLUSIONS

Delayed phase is superior to PVP for the washout detection of hypervascular HCC at gadobenate dimeglumine-enhanced MRI of cirrhotic liver.

Characterization of liver metastases: the efficacy of biphasic magnetic resonance imaging with ferucarbotran-enhancement

AIM

To retrospectively evaluate the efficacy of biphasic magnetic resonance imaging (MRI) of the liver with ferucarbotran-enhancement for the characterization of hepatic metastases.

MATERIALS AND METHODS

Thirty-six patients underwent MRI of the liver with separate acquisition of double-contrast enhancement consisting of gadolinium and ferucarbotran. A total of 106 focal hepatic lesions (51 metastases, 31 cysts, 23 haemangiomas, and one eosinophilic abscess) were included. Two sets of MRI were analysed: (1) ferucarbotran set: ferucarbotran-enhanced T1-weighted (T1W) dynamic imaging combined with ferucarbotran-enhanced T2*-weighted (T2*W) delayed imaging and (2) double set: gadolinium-enhanced T1W dynamic imaging combined with ferucarbotran-enhanced T2*W delayed imaging. The diagnostic accuracy of the two sets was evaluated using alternative free-response receiver operating characteristic curve analysis. Sensitivity and specificity were compared using the McNemar test. The enhancement pattern of focal hepatic lesions was analysed on gadolinium and ferucarbotran-enhanced T1W dynamic imaging.

RESULTS

There was no significant difference in the accuracy of characterizing hepatic metastases between the two sets. Sensitivity and specificity were not significantly different between the sets (p>0.05). Peripheral rim enhancement was exhibited in 57% of metastatic lesions on ferucarbotran-enhanced T1W dynamic imaging. The majority (96%) of hepatic haemangiomas demonstrated typical peripheral nodular enhancement with progression on ferucarbotran-enhanced T1W dynamic imaging and were easily differentiated from metastases.

CONCLUSION

Biphasic MRI of the liver with ferucarbotran-enhancement alone provided comparable diagnostic efficacy to double-contrast MRI for the characterization of hepatic metastases.

MRI findings of rapidly progressive hepatocellular carcinoma

PURPOSE

The purpose of this study is to determine the magnetic resonance imaging (MRI) and patient characteristics in subjects with hepatocellular carcinoma (HCC) that exhibit rapid progression.

MATERIALS AND METHODS

In this unblinded retrospective study, initial and follow up MR images were reviewed, before and after rapid progression of HCC, respectively. Rapid progression was defined as a lesion <3 cm which exhibited >3 cm increase in one year or 2 cm increase in 6 months. Patient characteristics and MRI findings were determined using clinical information from the institution clinical information system and records from the Radiology and Pathology Departments, Hepatology Division and Liver Transplant Service of the Department of Medicine.

RESULTS

Seven individuals were identified with HCC that showed rapid progression. Five of the patients had underlying hepatitis C, one had alcoholic hepatitis, and one had immunosuppression due to liver transplantation. On initial MRI, six patients had early intense ring enhancing lesions, which rapidly progressed in size. Five patients died within 6 months, one within 1 year after progression despite treatment. Six of the seven patients also had multiple other liver nodules on initial MRI; those that showed ring enhancement rapidly progressed but those without, did not show rapid progression.

CONCLUSION

Patients with rapidly progressive HCC had underlying hepatitis C and intense ring enhancement on initial MRI. This group of patients should be evaluated further to determine if they might benefit from early intervention.

Functional investigations on human mesenchymal stem cells exposed to magnetic fields and labeled with clinically approved iron nanoparticles

Background

For clinical applications of mesenchymal stem cells (MSCs), labeling and tracking is crucial to evaluate cell distribution and homing. Magnetic resonance imaging (MRI) has been successfully established detecting MSCs labeled with superparamagnetic particles of iron oxide (SPIO). Despite initial reports that labeling of MSCs with SPIO is safe without affecting the MSC's biology, recent studies report on influences of SPIO-labeling on metabolism and function of MSCs. Exposition of cells and tissues to high magnetic fields is the functional principle of MRI. In this study we established innovative labeling protocols for human MSCs using clinically established SPIO in combination with magnetic fields and investigated on functional effects (migration assays, quantification of colony forming units, analyses of gene and protein expression and analyses on the proliferation capacity, the viability and the differentiation potential) of magnetic fields on unlabeled and labeled human MSCs. To evaluate the imaging properties, quantification of the total iron load per cell (TIL), electron microscopy, and MRI at 3.0 T were performed.

Results

Human MSCs labeled with SPIO permanently exposed to magnetic fields arranged and grew according to the magnetic flux lines. Exposure of MSCs to magnetic fields after labeling with SPIO significantly enhanced the TIL compared to SPIO labeled MSCs without exposure to magnetic fields resulting in optimized imaging properties (detection limit: 1,000 MSCs). Concerning the TIL and the imaging properties, immediate exposition to magnetic fields after labeling was superior to exposition after 24 h. On functional level, exposition to magnetic fields inhibited the ability of colony formation of labeled MSCs and led to an enhanced expression of lipoprotein lipase and peroxisome proliferator-activated receptor-γ in labeled MSCs under adipogenic differentiation, and to a reduced expression of alkaline phosphatase in unlabeled MSCs under osteogenic differentiation as detected by qRT-PCR. Moreover, microarray analyses revealed that exposition of labeled MSCs to magnetic fields led to an up regulation of CD93 mRNA and cadherin 7 mRNA and to a down regulation of Zinc finger FYVE domain mRNA. Exposition of unlabeled MSCs to magnetic fields led to an up regulation of CD93 mRNA, lipocalin 6 mRNA, sialic acid acetylesterase mRNA, and olfactory receptor mRNA and to a down regulation of ubiquilin 1 mRNA. No influence of the exposition to magnetic fields could be observed on the migration capacity, the viability, the proliferation rate and the chondrogenic differentiation capacity of labeled or unlabeled MSCs.

Conclusions

In our study an innovative labeling protocol for tracking MSCs by MRI using SPIO in combination with magnetic fields was established. Both, SPIO and the static magnetic field were identified as independent factors which affect the functional biology of human MSCs. Further in vivo investigations are needed to elucidate the molecular mechanisms of the interaction of magnetic fields with stem cell biology.

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.

Magnetic resonance imaging findings of hepatocellular carcinoma: typical and atypical findings

Background: Hepatocellular carcinoma (HCC) is the most common primary liver malignancy. Magnetic resonance imaging has been widely used for detection and characterization of HCC. Objective: Describe MRI findings of HCC and to define the typical and atypical appearances of HCC on magnetic resonance images. Methods: We retrospectively reviewed MRI findings of 100 HCC in 78 patients. Diagnosis was confirmed by angiography, pathology or follow up imaging. The signal intensity, size, margins, enhancement pattern, and other features were evaluated. Imaging findings between small HCC (< 2 cm) and large HCC (>2 cm) were compared. Results: The most common signal intensity of HCC on unenhanced T1- and T2-weighted images was hypointense on T1-weighted images and hyperintense on T2-weighted images (65%). Most HCC (91%) were hyperintense on T2-weighted images. Isointensity on T2-weighted images were found in 9% of HCC. The typical enhancement pattern of HCC was enhancement on the arterial phase and washout on the portovenous phase (84%). Atypical enhancement pattern of HCC were enhancement on the portovenous phase in 5%, rim enhancement on the arterial phase or portovenous phase were demonstrated in 2%. Hyperintensity of the tumor on delayed phase was found in 19%. There was no statistically significant difference in signal intensity, enhancement, and washout pattern between small and large HCC. Fatty metamorphosis, mosaic pattern, necrosis, capsule and vascular involvement were found in 18%, 42%, 5%, 62%, and 6%, respectively. Mosaic pattern, necrosis, capsule, and vascular involvement were observed more frequently in large HCC. Conclusion: The typical appearance of HCC was hypointense on T1-weighted, hyperintense on T2-weighted images, arterial enhancement and portovenous washout. Atypical appearances of HCC were rim enhancement on the arterial phase or portovenous phase and persistent enhancement on the delayed phase

Focal liver lesions: detection and characterization at double-contrast liver MR Imaging with ferucarbotran and gadobutrol versus single-contrast liver MR imaging

PURPOSE

To retrospectively compare, in a multiobserver study, double-contrast-material (sequential administration of ferucarbotran and gadobutrol) magnetic resonance (MR) imaging with single-contrast-material ferucarbotran-enhanced and dynamic postferucarbotran gadobutrol-enhanced MR imaging for the detection and characterization of benign and malignant focal liver lesions.

MATERIALS AND METHODS

This study was institutional review board approved, and the requirement for informed patient consent was waived. Eighty-nine patients with a total of 128 focal liver lesions underwent double-contrast liver MR imaging (nonenhanced, ferucarbotran-enhanced, and dynamic postferucarbotran gadobutrol-enhanced MR imaging performed during one session). Four readers independently reviewed the data sets during three reading sessions focused on focal liver lesion detection and characterization: In session 1, the nonenhanced and dynamic postferucarbotran gadobutrol-enhanced images obtained at double-contrast MR imaging were analyzed. In session 2, the nonenhanced and ferucarbotran-enhanced images were analyzed. In session 3, all MR images were analyzed together. The diagnostic performance of each MR technique and each reader was evaluated by using receiver operating characteristic (ROC) analysis; differences between postferucarbotran gadobutrol-enhanced, ferucarbotran-enhanced, and double-contrast MR imaging were assessed at Wilcoxon signed rank testing; and interreader agreement was assessed at Cohen kappa analysis. Histopathologic confirmation or an unchanged clinical course or MR finding was the reference standard.

RESULTS

The four readers' detection of the benign and malignant lesions was not significantly different (P > or = .11) between the three MR techniques. The benign and malignant focal liver lesions were differentiated with significantly higher confidence (P < or = .01) on the double-contrast (area under ROC curve [A(z)] = 0.988) and ferucarbotran-enhanced (A(z) = 0.985) MR images than on the dynamic gadobutrol-enhanced images (A(z) = 0.963). Accuracy in the diagnosis of hepatocellular carcinoma (HCC) was highest (P = .02) and confidence in the final diagnosis of HCC (P = .001) or metastasis (P = .049) was significantly higher with double-contrast imaging.

CONCLUSION

In select cases, double-contrast MR imaging can improve diagnostic accuracy and increase confidence in characterizing focal liver lesions as HCC or metastasis.

Small (Radiol Med 2009;114:1239-66. [PMID: 19697104 DOI: 10.1007/s11547-009-0439-x]

PURPOSE

We prospectively compared gadoliniumenhanced magnetic resonance imaging (dynamic MRI), superparamagnetic iron oxide (SPIO) (ferucarbotran) MRI and multidetector-row computed tomography (MDCT) and the combination of dynamic MRI plus MDCT vs. dynamic MRI plus SPIO-MRI (double-contrast MRI: DC-MRI) for the detection of small (

MATERIALS AND METHODS

Sixty-three patients with liver cirrhosis and suspicious nodules detected during ultrasound (US) surveillance underwent DC-MRI in the same imaging session and MDCT within 15 days. The final diagnosis was established at pathology on the explanted liver (n=10), resection (n=6) and biopsy (n=38) specimens or at 2-years' follow-up (n=9).

RESULTS

One hundred and twenty-three nodules were detected: 87 were confirmed HCCs in 54 patients. The accuracy of SPIO-MRI and dynamic MRI were similar, both being superior to MDCT. Dynamic MRI demonstrated the highest sensitivity (83.9%; p<0.001). especially for lesions <1 cm (90.6%) - coupled with a lower specificity (36.1%) than SPIO-MRI, particularly in subcentimeter lesions (28.6%). SPIO-MRI demonstrated the highest sensitivity for nodules >1 cm and the highest specificity (83.3%) superior to dynamic MRI (p<0.0001). In the per-lesion analysis, SPIO-MRI demonstrated a positive predictive value higher than dynamic MRI (p=0.0059) and than both the combinations dynamic MRI/MDCT and DC-MRI (p=0.0021 and p=0.0087, respectively). DC-MRI showed the highest sensitivity (97.7%) and accuracy (78.9%), detecting hypovascular and atypical HCCs >1 cm. Furthermore its per-patient negative predictive value was the highest (100%), and significantly higher than all the other methods.

CONCLUSIONS

DC-MRI is the most sensitive and accurate method and can be confidently used as a single-step procedure for the detection of small HCCs, with the exception of lesions <1 cm.

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MESH Headings

• Adult
• Aged
• Aged, 80 and over
• Carcinoma, Hepatocellular/diagnosis
• Carcinoma, Hepatocellular/diagnostic imaging
• Contrast Media
• Dextrans
• Female
• Ferrosoferric Oxide
• Follow-Up Studies
• Gadolinium DTPA
• Humans
• Liver Cirrhosis/diagnosis
• Liver Cirrhosis/diagnostic imaging
• Liver Neoplasms/diagnosis
• Liver Neoplasms/diagnostic imaging
• Magnetic Resonance Imaging
• Magnetite Nanoparticles
• Male
• Middle Aged
• Predictive Value of Tests
• Prospective Studies
• Sensitivity and Specificity
• Tomography, X-Ray Computed

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Affiliation(s)

R Golfieri Radiologia Malpighi, Azienda Ospedaliero-Universitaria di Bologna, Policlinico S. Orsola-Malpighi, Università di Bologna, Via Albertoni 15, 40138, Bologna, Italy.
E Marini
A Bazzocchi
F Fusco
F Trevisani
C Sama
G Mazzella
S Cavuto
F Piscaglia
L Bolondi

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Detection of small hepatocellular carcinoma: comparison of conventional gadolinium-enhanced MRI with gadolinium-enhanced MRI after the administration of ferucarbotran

We compared the diagnostic efficacy of gadolinium (Gd)-enhanced MRI with that of Gd-enhanced MRI after administration of ferucarbotran for revealing small hypervascular hepatocellular carcinomas (HCCs). 24 patients with 34 HCCs (ranging in size from 0.6-2.0 cm) underwent Gd-enhanced three-dimensional dynamic MRI followed, after an interval of 5-11 days (mean, 7 days), by Gd-enhanced three-dimensional dynamic MRI after administration of ferucarbotran. The two Gd-enhanced arterial-phase MRI scans were compared quantitatively by measuring the tumour-liver contrast-to-noise ratio (CNR) and qualitatively by evaluating the tumour-liver contrast using matched-pairs analysis. The tumour-liver CNR with Gd-enhanced arterial-phase imaging after ferucarbotran (250.3 +/- 103.7) was higher than that with Gd-enhanced arterial-phase imaging (221.1 +/- 96.1) (p < 0.001). Matched-pairs analysis indicated that, for three lesions, the relative tumour-liver contrast was slightly better with Gd-enhanced arterial-phase imaging after ferucarbotran than with conventional Gd-enhanced arterial-phase imaging; however, in the case of the remaining 31 lesions, the two images were equivalent. We concluded that, although Gd-enhanced arterial-phase imaging after ferucarbotran results in better tumour-liver CNR than Gd-enhanced arterial-phase imaging, the ability of the two techniques to reveal small hypervascular HCCs is the same.

Detection of liver metastases: Gadoxetic acid-enhanced three-dimensional MR imaging versus ferucarbotran-enhanced MR imaging

PURPOSE

To compare the diagnostic performance of gadoxetic acid-enhanced MRI with ferucarbotran-enhanced MRI for the detection of liver metastases.

MATERIALS AND METHODS

Thirty-six patients with 80 liver metastases who underwent gadoxetic acid-enhanced MRI using a three-dimensional volumetric interpolated technique and ferucarbotran-enhanced MRI with a mean interval of 7 days (range, 5-10 days) were included in this study. Two observers independently interpreted the two sets of images - the gadoxetic acid set (unenhanced, early dynamic and 20min delayed phase images) and the ferucarbotran set (unenhanced and ferucarbotran-enhanced T2*-weighted-gradient echo and T2-weighted turbo spin echo images). Diagnostic accuracy was evaluated using the alternative-free response receiver operator characteristic (ROC) method. Sensitivity and positive predictive value were also evaluated.

RESULTS

There was a trend toward increased areas under the ROC curve (Az values) for the gadoxetic acid set (0.950, 0.948) as compared with the ferucarbotran set (0.941 and 0.939) of images, but no significant difference was found for both observers (p<0.05). Sensitivities of the gadoxetic acid set (93.8% and 92.5%) were also slightly better than those of the ferucarbotran set (88.8% and 87.5%) with no significant difference (p=0.13). The two image sets showed similar positive predictive values (98.7% and 98.6%, respectively).

CONCLUSIONS

Gadoxetic acid-enhanced MRI showed comparable diagnostic performance to ferucarbotran-enhanced MRI for the detection of liver metastases.

Combined SPIO-gadolinium magnetic resonance imaging in cirrhotic patients: negative predictive value and role in screening for hepatocellular carcinoma

BACKGROUND

The objective of our study was to assess the negative predictive value (NPV) of double-contrast MRI (DC-MRI) with SPIO and gadolinium, and to determine the role of DC-MRI in screening for hepatocellular carcinoma (HCC) in cirrhotic patients.

METHODS

We retrospectively included 160 DC-MRI scans done as second-line investigations in 119 patients with cirrhosis over a 25-month period. Two radiologists independently classified the MRI scans as strongly suggesting HCC (HCC Group), showing benign nodules (benign nodules Group), showing no nodules (no-nodules Group) or indeterminate; they assigned a diagnostic confidence score (DCS) using a 0-10 scale. The reference standard was histology or results of follow-up investigations. Mean follow-up was 16.9 months (12-28 months).

RESULTS

The radiologists disagreed for two scans (kappa = 0.98). Of 112 scans [benign nodules Group (n = 32) and no-nodules Group (n = 80)], 11 were excluded (3 patients lost to follow-up and 8 who died with no known cancer) while a HCC was detected during follow-up in 8 patients, yielding a NPV of 92% (93/101) (95% confidence interval, 85%-97%). The DCS was in the 4-6 range (indicating uncertainty) for only 6 (3.75%) scans.

CONCLUSIONS

DC-MRI is reliable and reproducible. Its high NPV suggests a role as a second-line investigation after ultrasonography, for HCC screening.

The Use of Clinically Approved Small Particles of Iron Oxide (SPIO) for Labeling of Mesenchymal Stem Cells Aggravates Clinical Symptoms in Experimental Autoimmune Encephalomyelitis and Influences Their In Vivo Distribution

Multiple sclerosis (MS) is an inflammatory and demyelinating disease of the central nervous system (CNS). Mesenchymal stem cells (MSC) have been shown to ameliorate symptoms in experimental autoimmune encephalomyelitis (EAE), a model of MS. Using cloned MSC labeled with clinically approved small particles of iron oxide (SPIO) for treatment of EAE we analyzed the tissue localization of transferred cells. Treatment with unlabeled MSC led to disease amelioration compared to controls. In contrast, treatment with SPIO-labeled MSC lead to increase in disease severity. Treatment with SPIO alone did not alter disease course. After transplantation labeled and nonlabeled MSC were detected in the CNS and the liver with significantly more SPIO-labeled cells present in the CNS. Iron deposition was present in the group treated with SPIO-labeled MSC, indicating that in vivo the initially cell surface-bound iron detached from the MSC. These results could be of great importance for imaging of patients in the clinical setting, indicating that in vivo application of SPIO-labeled MSC needs to be performed with caution because the cell-derived exposure of iron can lead to disease aggravation.

Detection of hypervascular malignant foci in borderline lesions of hepatocellular carcinoma: comparison of dynamic multi-detector row CT, dynamic MR imaging and superparamagnetic iron oxide-enhanced MR imaging

The study object was to retrospectively compare the detection rate of hypervascular foci visualized by CT during hepatic arteriography (CTHA) in borderline nodules, which was observed upon cirrhotic livers, on dynamic MDCT, dynamic gadolinium-enhanced MR (dynamic MR), and SPIO-enhanced MR imaging. Eighty-five nodules in 49 patients with cirrhosis were evaluated. When a part of the nodule showed hyperdensity relative to the surrounding areas of the nodule on CTHA, it was defined as "hypervascular focus." The relationships between the dynamic MDCT and dynamic MR and SPIO-enhanced MR imaging findings of these foci were analyzed using X(2) test. Hypervascular foci were detected in 17 (53%) of 32 on the arterial dominant phase of dynamic MDCT, in 19 (37%) of 51 on the arterial dominant phase of dynamic MR and in 6 (26%) of 23 on SPIO-enhanced MR imaging. Arterial dominant phase of dynamic MDCT demonstrated a significantly higher detection rate of hypervascular foci less than 5 mm in diameter than did dynamic and SPIO MR imaging (p<0.05). Hypervascular foci in borderline nodules could be better visualized by dynamic MDCT than by gadolinium- and SPIO-enhanced MR imaging. Dynamic MDCT is recommended for the follow-up examination of hypovascular borderline lesions.

Double-contrast MRI for accurate staging of hepatocellular carcinoma in patients with cirrhosis

OBJECTIVE

The aim of this study was to evaluate the accuracy of a double-contrast MRI protocol in staging of hepatocellular carcinoma (HCC) in patients with cirrhosis.

MATERIALS AND METHODS

This cross-sectional study was performed at a tertiary liver care center. Forty-eight patients with cirrhosis underwent double-contrast MRI for clinical care and liver transplantation. For each MRI examination, superparamagnetic iron oxide was infused, and 2D T2*-weighted spoiled gradient-recalled echo and T2-weighted echo-train spin-echo MR images were obtained for assessment of phagocytic function. Immediately afterward, a low-molecular-weight gadolinium compound was injected, and 3D T1-weighted spoiled gradient-recalled echo images were acquired dynamically for assessment of vascularity. Two blinded radiologists independently reviewed all MR images and assigned per-lesion and per-patient cancer confidence scores to determine the American Liver Tumor Study Group tumor stage. The imaging-based cancer scores and tumor stages were correlated with pathology reports. Performance parameters were computed for imaging-based measurements.

RESULTS

Of the 48 study subjects, 25 had HCC (three, T1; 18, T2; one, T3; one, T4a; two, T4b). In total, there were 37 HCC nodules. The accuracy of MRI in prediction of pathologic tumor stage was 81-85% depending on the radiologist. Per-patient and per-lesion sensitivity in the diagnosis of HCC were 96% and 81% for one radiologist and 96% and 89% for the other.

CONCLUSION

A double-contrast MRI protocol has high accuracy in staging of HCC in patients with cirrhosis.

Focal nodular hyperplasia: typical and atypical MRI findings with emphasis on the use of contrast media

Focal nodular hyperplasia is a benign hypervascular hepatic tumour, frequently detected in asymptomatic patients undergoing imaging studies for unrelated reasons. Magnetic resonance imaging (MRI) generally allows a confident differential diagnosis with other hypervascular liver lesions, either benign or malignant. In addition, due to the recent development of hepatospecific MRI contrast agents, MRI concomitantly enables functional and morphological information to be obtained, thus providing important clues for the detection and characterization of focal nodular hyperplasia lesions.

Ferucarbotran versus Gd-DTPA-enhanced MR imaging in the detection of focal hepatic lesions

AIM: To evaluate the efficacy of ferucarbotran-enhanced MR imaging in the detection of focal hepatic lesions compared to plain and Gd-DTPA-enhanced MR imaging.

METHODS: Fifty-nine patients with suspected focal hepatic lesions were admitted to the study. Plain MR imaging (FSE T₂WI with fat suppression and GRE T₁WI sequences) and Gd-DTPA dynamic enhanced MR of the liver were initially performed followed by ferucarbotran-enhanced MR imaging 48 h later (including GRE T₁WI, FSE T₂WI with fat suppression, and GRE T₂*WI sequences). Images were reviewed independently by three observers. Results were correlated with surgery and pathologic examination or reference examination, and sensitivity was statistically calculated for the different MR imaging sequences.

RESULTS: Among all confirmed lesions (n = 133), ferucarbotran-enhanced MR imaging revealed 130 lesions on FSE T₂WI with fat suppression, 115 lesions on dynamic T₁WI GRE, and 127 lesions on GRE T₂*WI. Pre-contrast MR imaging revealed only 84 lesions on GRE T₁WI and 106 lesions on FSE T₂WI with fat suppression, while Gd-DTPA dynamic enhanced GRE T₁WI revealed 123 lesions. For 44 micro-lesions (< 1.0 cm) in all patients the detection rates were as follows: ferucarbotran-enhanced FSE T₂WI with fat suppression, 93.2% (41/44); ferucarbotran-enhanced GRE T₂*WI, 88.6% (39/44); Gd-DTPA dynamic-enhanced GRE T₁WI, 79.5% (35/44); pre-contrast FSE T₂WI with fat suppression, 54.5% (24/44); and pre-contrast GRE T₁WI, 34.1% (15/44). In detecting micro-lesions, statistically significant difference was found for Ferucarbotran-enhanced FSE T₂WI with fat suppression and GRE T₂*WI sequences compared to the other sequences (P < 0.05).

CONCLUSION: Ferucarbotran-enhanced FSE T₂WI with fat suppression and GRE T₂*WI sequences are superior in detecting micro-lesions (< 1 cm) in comparison with plain and Gd-DTPA dynamic-enhanced MR imaging.

Transferrin Receptor Upregulation: In Vitro Labeling of Rat Mesenchymal Stem Cells with Superparamagnetic Iron Oxide

PURPOSE

To prospectively evaluate the influence of superparamagnetic iron oxide (SPIO) or ultrasmall SPIO (USPIO) particles on the surface epitope pattern of adult mesenchymal stem cells (MSCs) by regulating the expression of transferrin receptor and to prospectively evaluate the influence of transfection agents (TAs) on the uptake of SPIO or USPIO particles in MSCs.

MATERIALS AND METHODS

The study was approved by the institutional animal care committee of the University of Tübingen. MSCs were isolated from the bone marrow of four rats. To obtain highly homogeneous MSC populations, MSCs from one rat were single-cell cloned. One MSC clone was characterized and selected for the labeling experiments. The MSCs, which were characterized with flow cytometry and in vitro differentiation, were labeled with 200 microg/mL SPIO or USPIO or with 60 microg/mL SPIO or USPIO in combination with TAs. Aggregations of labeled cells were accommodated inside a defined volume in an agar gel matrix. Magnetic resonance (MR) imaging was performed to measure SPIO- or USPIO-induced signal voids. Quantification of cellular total iron load (TIL) (intracellular iron plus iron coating the cellular surface), determination of cellular viability, and electron microscopy were also performed.

RESULTS

Labeling of MSCs with SPIO or USPIO was feasible without affecting cell viability (91.1%-94.7%) or differentiation potential. For MR imaging, SPIO plus a TA was most effective, depicting 5000 cells with an average TIL of 76.5 pg per cell. SPIO or USPIO particles in combination with TAs coated the cellular surface but were not incorporated into cells. In nontransfected cells, SPIO or USPIO was taken up. MSCs labeled with SPIO or USPIO but without a TA showed enhanced expression of transferrin receptor, in contrary to both MSCs labeled with SPIO or USPIO and a TA and control cells.

CONCLUSION

SPIO or USPIO labeling without TAs has an influence on gene expression of MSCs upregulating transferrin receptor. Furthermore, SPIO labeling with a TA will coat the cellular surface.

Abdominal MRI advances in the detection of liver tumours and characterisation

With recent technical advances in hardware, software, and intravenous contrast agents, MRI has evolved into a clinically useful procedure to detect and characterise liver tumours. The combination of MRI systems with larger gradients, improved surface coils, and parallel imaging techniques have produced substantial improvements in MRI quality and speed of image acquisition. Images that previously needed several minutes to acquire can now be obtained in several seconds. The notably faster imaging capabilities of new MRI scanners are ideally suited for dynamic contrast-enhanced liver imaging in which early arterial-phase imaging is best for detecting hepatocellular carcinomas and hypervascular liver metastases. The inherent excellent soft-tissue contrast of MRI can be further improved by non-specific extracellular contrast agents and by liver-specific contrast agents. These contrast agents are now routinely used for liver imaging and improve the sensitivity and specificity of hepatobiliary MRI.

Small hyperintense hepatic lesions on T1-weighted images in patients with cirrhosis: evaluation with serial MRI and imaging features for clinical benignity

PURPOSE

The aim of this study was to evaluate the frequency and magnetic resonance imaging (MRI) features of clinically benign, small (<2 cm) hyperintense hepatic lesions in the cirrhotic liver on T1-weighted MR images seen at serial MRI.

MATERIALS AND METHODS

This study included 189 patients with cirrhosis, who underwent hepatic MRI more than twice with an interval of at least 12 months. The initial MR images were reviewed for the presence of small hyperintense lesions on T1-weighted images. The size, location and signal intensity on T2-weighted images as well as enhancement patterns of the corresponding lesions were recorded.

RESULTS

On the initial T1-weighted MR images, 43 small hyperintense hepatic lesions were detected in 23 (12%) of 189 patients. Twelve (28%) of 43 lesions showed early enhancement and were pathologically diagnosed as hepatocellular carcinoma (HCC) during the follow-up period. Thirty-one (72%) of 43 lesions showed no early enhancement with various signal intensity on T2-weighted images (hyperintensity=4, isointensity=20, hypointensity=7). Among these 31 lesions, 12 showed no interval change, while 11 disappeared (n=10) or decreased in size (n=1). In the remaining eight lesions, seven were diagnosed as HCC on the basis of pathologic confirmation or the interval growth.

CONCLUSION

Small hyperintense hepatic lesions on T1-weighted magnetic resonance (MR) images without early enhancement on the arterial-phase contrast-enhanced dynamic studies in patients with cirrhosis usually showed no interval growth or disappeared during the serial MRI. These lesions with additional findings of iso- or hypointensity on the T2-weighted MR images without "washout effect" on the contrast-enhanced equilibrium-phase images may more frequently be clinically benign or hyperplastic nodules than HCCs.

Promise and Progress for Functional and Molecular Imaging of Response to Targeted Therapies

Biomarkers to predict or monitor therapy response are becoming essential components of drug developer's armamentaria. Molecular and functional imaging has particular promise as a biomarker for anticancer therapies because it is non-invasive, can be used longitudinally and provides information on the whole patient or tumor. Despite this promise, molecular or functional imaging endpoints are not routinely incorporated into clinical trial design. As the costs of clinical trials and drug development become prohibitively more expensive, the need for improved biomarkers has become imperative and thus, the relatively high cost of imaging is justified. Imaging endpoints, such as Diffusion-Weighted MRI, DCE-MRI and FDG-PET have the potential to make drug development more efficient at all phases, from discovery screening with in vivo pharmacodynamics in animal models through the phase III enrichment of the patient population for potential responders. This review focuses on the progress of imaging responses to new classes of anti-cancer therapies targeted against PI3 kinase/AKT, HIF-1alpha and VEGF. The ultimate promise of molecular and functional imaging is to theragnostically predict response prior to commencement of targeted therapy.

Focal nodular hyperplasia: Intraindividual comparison of dynamic gadobenate dimeglumine- and ferucarbotran-enhanced magnetic resonance imaging

PURPOSE

To intraindividually compare the enhancement pattern of focal nodular hyperplasia (FNH) after dynamic administration of two bolus-injectable liver-specific MR contrast agents, ferucarbotran and gadobenate dimeglumine.

MATERIALS AND METHODS

A total of 19 patients with 24 FNHs underwent gadobenate dimeglumine- and ferucarbotran-enhanced MRI during the hepatic arterial-dominant phase (HAP; 25 seconds), the portal-venous phase (PVP; 60 seconds), and the equilibrium phase (EP; 180 seconds). Hepatospecific phases were acquired on T1-weighted images 120 minutes after gadobenate dimeglumine administration, and on T2-weighted images 10 minutes after ferucarbotran administration. Lesion enhancement was independently analyzed by two observers. The kappa statistic was determined to evaluate the agreement between the enhancement patterns of the lesions.

RESULTS

On gadobenate dimeglumine-enhanced MR images during HAP, PVP, and EP, FNHs were: hyperintense (24/20/13); isointense (0/4/11); and hypointense (0/0/0). On ferucarbotran-enhanced MR images during HAP, PVP, and EP, FNHs were: hyperintense (2/0/0); isointense (16/9/14); and hypointense (6/15/10). Overall, poor agreement between both contrast agents was observed. During the hepatospecific phases, most (20/24; 83%) FNHs showed a typical enhancement pattern during the delayed hepatospecific phase.

CONCLUSION

The dynamic enhancement pattern of FNHs is significantly different between gadobenate dimeglumine- and ferucarbotran-enhanced MRI. With respect to hepatospecific phase, the majority of FNHs showed a typical behavior on both contrast agents.

Changes in signal-to-noise ratios and contrast-to-noise ratios of hypervascular hepatocellular carcinomas on ferucarbotran-enhanced dynamic MR imaging

PURPOSE

To verify changes in the signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs) of hypervascular hepatocellular carcinomas (HCCs) on ferucarbotran-enhanced dynamic T1-weighted MR imaging.

MATERIALS AND METHODS

Fifty-two patients with 61 hypervascular HCCs underwent ferucarbotran-enhanced dynamic MR imaging, and then hepatic resection. Hypervascular HCCs were identified when definite enhancement was noted during the arterial dominant phase of three-phase MDCT. Dynamic MR Images with T1-weighted fast multiplanar spoiled gradient-recalled echo sequence (TR200/TE4.2) were obtained before and 20 s, and 1, 3, 5, and 10 min, after bolus injection of ferucarbotran. We estimated the signal intensities of tumors and livers, and calculated the SNRs and CNRs of the tumors.

RESULTS

On ferucarbotran-enhanced dynamic MR imaging, SNR measurements showed a fluctuating pattern, namely, an increase in SNR followed by a decrease and a subsequent increase (or a decrease in SNR followed by a increase and a subsequent decrease) in 50 (82.0%) of 61 tumors, a single-peak SNR pattern (highest SNR on 20 s, 1, 3, or 5 min delayed images followed by a decrease) in seven (11.5%), and a decrease in SNR followed by an increase in four (6.6%). Maximum absolute CNRs with positive value were noted on 10 min delayed images in 41 (67.2%) tumors, and maximum absolute CNRs with negative value were observed on 20 s delayed images in 12 (19.7%) and on 1 min delayed images in eight (13.1%).

CONCLUSION

Despite showing various SNR and CNR changes, the majority of hypervascular HCCs demonstrated a fluctuating SNR pattern on ferucarbotran-enhanced dynamic MR imaging and a highest CNR on 10 min delayed image, which differed from the classic enhancement pattern on multiphasic CT.