Comparison of Superparamagnetic Iron Oxide–Enhanced and Gadobenate Dimeglumine–Enhanced Dynamic MRI for Detection of Small Hepatocellular Carcinomas

Imaging of Liver Tumors Using Surface-Enhanced Raman Scattering Nanoparticles

Complete surgical resection is the ideal first-line treatment for most liver malignancies. This goal would be facilitated by an intraoperative imaging method that enables more precise visualization of tumor margins and detection of otherwise invisible microscopic lesions. To this end, we synthesized silica-encapsulated surface-enhanced Raman scattering (SERS) nanoparticles (NPs) that act as a molecular imaging agent for liver malignancies. We hypothesized that, after intravenous administration, SERS NPs would avidly home to healthy liver tissue but not to intrahepatic malignancies. We tested these SERS NPs in genetically engineered mouse models of hepatocellular carcinoma and histiocytic sarcoma. After intravenous injection, liver tumors in both models were readily identifiable with Raman imaging. In addition, Raman imaging using SERS NPs enabled detection of microscopic lesions in liver and spleen. We compared the performance of SERS NPs to fluorescence imaging using indocyanine green (ICG). We found that SERS NPs delineate tumors more accurately and are less susceptible to photobleaching. Given the known advantages of SERS imaging, namely, high sensitivity and specific spectroscopic detection, these findings hold promise for improved resection of liver cancer.

Detection of small (≤2 cm) HCC in cirrhotic patients: added value of diffusion MR-imaging

OBJECTIVES

To evaluate the usefulness of the diffusion-weighted sequence in the detection of small (≤2 cm) hepatocellular carcinoma (HCC) in patients with cirrhosis.

METHODS

Seventy cirrhotic patients with 93 HCCs underwent MR-Imaging at 1.5 T. MR acquisitions comprised unenhanced T1- and T2-weighted images and post-contrast Gd-BOPTA-enhanced T1W GRE-3D images acquired after approximately 25, 60, 180 s (dynamic phases) and 90 min (hepatobiliary phase). DWI was performed by a SSEPI sequence (b values 0, 50, 400, 800 s/mm(2)). Quantitative analysis was performed to establish significant difference of ADC values of benign lesions compared with that of HCC. Sensitivity, specificity, positive and negative predictive values and diagnostic accuracy of two different protocols with and without diffusion MRI sequence were also calculated and compared each other.

RESULTS

A good inverse correlation was found between reference standard and ADC values (ρ = -0.688). The mean ADC value of HCC was significantly lower than the mean value of benign focal liver lesions (p < 0.0001). No significant difference was reported in term of sensitivity, specificity, PPV, NPV and diagnostic accuracy between the two datasets. A trend to a better sensitivity was found when DWI images were considered.

CONCLUSIONS

The adjunction of DWI does not significantly improve the diagnostic accuracy in the detection of small HCC.

Diagnostic accuracy of MR imaging to identify and characterize focal liver lesions: comparison between gadolinium and superparamagnetic iron oxide contrast media

To compare the diagnostic value of gadolinium (Gd) and ultrasmall superparamagnetic iron oxide (SPIO) contrast media for characterization of focal liver lesions (FLL), we retrospectively evaluated the results of magnetic resonance (MR) imaging in 68 patients (40 M, 28 F, age from 22 to 81 yrs) of which 36 with diagnosis of colo-rectal cancer, 26 with hepatic cirrhosis and 6 with incidental imaging detection of FLL. MR (Gyroscan Intera 1.5 T, Philips Medical Systems) study was performed using T1 and T2 fast-field-echo (FFE) and T2 turbo-spin-echo (TSE) sequences in axial and coronal views. Dynamic multi-phases gadolinium Gd-enhanced T1-FFE-Bh images were obtained in arterial, portal and equilibrium phases, followed by SPIO-enhanced T2-FFE scans. A qualitative analysis of pre- and post-contrast MR images to classify FLL as benign or malignant was performed using a 3-point scoring system: 0= benign; 1= suspicious for malignancy; 2= malignant. A total of 118 lesions were evaluated. In particular, histology (n=18), cytology (n=14) or clinical-imaging follow-up data (n=86) demonstrated 4 adenomas, 29 cysts, 3 focal steatosis, 25 hemangiomas, 1 focal vascular abnormality, 5 fibrotic lesions as well as 13 regenerative nodules, 6 dysplastic, 14 hepatocellular carcinomas (HCC), 17 metastasis and 1 cholangiocarcinoma. For MR imaging, diagnostic accuracy, sensitivity, specificity, positive (PPV) and negative (NPV) predictive values of Gd vs. SPIO images were respectively 83% vs. 92%, 79% vs. 74%, 85% vs. 99% (P=0.002), 68% vs. 96% (P=0.005) and 91% vs. 90%, respectively. The results suggest that SPIO-MR provides a diagnostic incremental value, as specificity and PPV, particularly to characterize FLL compared to Gd-MR; thus, we strongly recommend the use of SPIO when liver lesion characterization is requested and Gd images are uncertain.

Pharmacokinetics of gadobenate dimeglumine in children 2 to 5 years of age undergoing MRI of the central nervous system

PURPOSE

To determine the pharmacokinetic profile of gadobenate dimeglumine in children aged between 2 and 5 years.

MATERIALS AND METHODS

Fifteen children scheduled to undergo contrast-enhanced MRI for suspected disease of the central nervous system received a single intravenous injection of 0.1 mmol/kg gadobenate dimeglumine. Children were stratified into three age groups: 2 to <3 years, 3 to <4 years, and 4 to 5 (i.e., <6 years). Serial blood and urine samples collected at prespecified time-points before and after contrast administration were analyzed for gadolinium concentrations. Pharmacokinetic parameters were calculated using noncompartmental and compartmental techniques.

RESULTS

Mean values of 65.7 μg/mL for highest blood gadolinium concentration, 0.2 L/h/kg for blood clearance, 0.32 L/kg for steady-state volume of distribution, and 1.2 h for terminal elimination half-life were determined across all age groups combined. On average, more than 80% of the dose was eliminated in the urine during the first 24 h after administration. All pharmacokinetic parameters were similar between age groups and no effects of gender were noted. No adverse events considered related to gadobenate dimeglumine administration were reported.

CONCLUSION

In terms of pharmacokinetic profile no dosage adjustment from the approved adult gadobenate dimeglumine dose of 0.1 mmol/kg bodyweight is necessary in children aged between 2 and 5 years.

Malignant focal liver lesions at contrast-enhanced ultrasonography and magnetic resonance with hepatospecific contrast agent

The aim of this study was to compare the diagnostic accuracy of the late phase of CEUS and the hepatobiliary phase of CE-MR with Gd-BOPTA in the characterization of focal liver lesions in terms of benignity and malignancy. A total of 147 solid focal liver lesions (38 focal nodular hyperplasias, 1 area of focal steatosis, 3 regenerative nodules, 8 adenomas, 11 cholangiocarcinomas, 36 hepatocellular carcinomas and 49 metastases) were retrospectively evaluated in a multicentre study, both with CEUS, using sulphur hexafluoride microbubbles (SonoVue, Bracco, Milan, Italy) and CE-MR, performed with Gd-BOPTA (Multihance, Bracco, Milan, Italy). All lesions thought to be malignant were cytohistologically proven, while all lesions thought to be benign were followed up. Sensitivity, specificity, positive (PPV) and negative (NPV) predictive values and accuracy were calculated for the late phase of CEUS and the hepatobiliary phase of CE-MRI, respectively, and in combination. Analysis of data revealed 42 benign and 105 malignant focal liver lesions. We postulated that all hypoechoic/hypointense lesions on the two phases were malignant. The diagnostic errors were 13/147 (8.8%) by CEUS and 12/147 (8.2%) by CE-MR. Sensitivity, specificity, PPV, NPV and accuracy of the late phase of CEUS were 90%, 93%, 97%, 80% and 91%, 93%, 97%, 81% and 92% for the hepatobiliary phase of CE-MRI, respectively. If we considered both techniques, the misdiagnosis diminished to 3/147 (2%) and sensitivity, specificity, PPV, NPV and accuracy were 98%, 98%, 99%, 95% and 98%. The combination of the late phase of CEUS and the hepatobiliary phase of CE-MR in the characterization of solid focal liver lesions in terms of benignity and malignancy is more accurate than the two techniques used separately.

Superparamagnetic iron oxide based MRI contrast agents: Current status of clinical application

Superparamagnetic iron oxide (SPIO) MR contrast agents are composed of nano-sized iron oxide crystals coated with dextran or carboxydextran. Two SPIO agents are clinically approved, namely: ferumoxides (Feridex in the USA, Endorem in Europe) with a particle size of 120 to 180 nm, and ferucarbotran (Resovist) with a particle size of about 60 nm. The principal effect of the SPIO particles is on T2* relaxation and thus MR imaging is usually performed using T2/T2*-weighted sequences in which the tissue signal loss is due to the susceptibility effects of the iron oxide core. Enhancement on T1-weighted images can also be seen with the smaller Resovist. Both Feridex and Resovist are approved specifically for MRI of the liver. The difference being that Resovist can be administered as a rapid bolus (and thus can be used with both dynamic and delayed imaging), whereas Feridex needs to be administered as a slow infusion and is used solely in delayed phase imaging. In the liver, these particles are sequestered by phagocytic Kupffer cells in normal reticuloendothelial system (RES), but are not retained in lesions lacking Kupffer cells. Consequently, there are significant differences in T2/T2* relaxation between normal tissue and lesions, resulting in increased lesion conspicuity and detectability. SPIO substantially increase the detectability of hepatic metastases. For focal hepatocellular lesions, SPIO-enhanced MR imaging exhibits slightly better diagnostic performance than dynamic CT. A combination of dynamic and static MR imaging technique using T1- and T2 imaging criteria appears to provide clinically more useful patterns of enhancement. Feridex and Resovist are also used for evaluating macrophage activities in some inflammatory lesions, but their clinical values remain to be further confirmed. The clinical development of Ferumoxtran (Combidex in the USA, Sinerem in Europe), designed for lymph node metastasis evaluation, is currently stopped.

Hepatocellular carcinoma in cirrhotic patients: prospective comparison of US, CT and MR imaging

OBJECTIVES

To prospectively compare the diagnostic performance of ultrasound (US), multidetector computed tomography (MDCT) and contrast-enhanced magnetic resonance imaging (MRI) in cirrhotic patients who were candidates for liver transplantation.

METHODS

One hundred and forty consecutive patients with 163 hepatocellular carcinoma (HCC) nodules underwent US, MRI and MDCT. Diagnosis of HCC was based on pathological findings or substantial growth at 12-month follow-up. Four different image datasets were evaluated: US, MDCT, MRI unenhanced and dynamic phases, MRI unenhanced dynamic and hepatobiliary phase. Diagnostic accuracy, sensitivity, specificity, PPV and NPV, with corresponding 95 % confidence intervals, were determined. Statistical analysis was performed for all lesions and for three lesion subgroups (<1 cm, 1-2 cm, >2 cm).

RESULTS

Significantly higher diagnostic accuracy, sensitivity and NPV was achieved on dynamic + hepatobiliary phase MRI compared with US, MDCT and dynamic phase MRI alone. The specificity and PPV of US was significantly lower than that of MDCT, dynamic phase MRI and dynamic + hepatobiliary phase MRI. Similar results were obtained for all sub-group analyses, with particular benefit for the diagnosis of smaller lesions between 1 and 2 cm.

CONCLUSIONS

Dynamic + hepatobiliary phase MRI improved detection and characterisation of HCC in cirrhotic patients. The greatest benefit is for diagnosing lesions between 1 and 2 cm.

Solid hypervascular liver lesions: accurate identification of true benign lesions on enhanced dynamic and hepatobiliary phase magnetic resonance imaging after gadobenate dimeglumine administration

PURPOSE

To evaluate hepatobiliary phase magnetic resonance imaging with gadobenate dimeglumine for differentiation of benign hypervascular liver lesions from malignant or high-risk lesions.

METHODS AND MATERIALS

Retrospective assessment was performed of 550 patients with 910 hypervascular lesions (302 focal nodular hyperplasia [FNH], 82 nodular regenerative hyperplasia [NRH], 59 hepatic adenoma or liver adenomatosis [HA/LA], 329 hepatocellular carcinomas [HCC], 12 fibrolamellar-HCC [FL-HCC], 21 peripheral cholangiocarcinomas [PCC], 105 metastases). Imaging was performed before and during the arterial, portal-venous, equilibrium, and hepatobiliary phases after gadobenate dimeglumine administration (0.05 mmol/kg). Histologic confirmation was available for ≥1 lesion per patient, except for patients with suspected FNH (diagnosis based on characteristic enhancement/follow-up). Lesion differentiation (benign/malignant) on the basis of contrast washout and lesion enhancement (hypo-/iso-/hyperintensity) was assessed (sensitivity, specificity, accuracy, PPV, and NPV) relative to histology or final diagnosis.

RESULTS

On portal-venous or equilibrium phase images, washout was not seen for 208 of 526 (39.5%) malignant (HCC, FL-HCC, PCC, metastases) and high-risk (HA/LA) lesions. Conversely, only 5 of 384 (1.3%) true benign lesions (FNH/NRH) showed washout. Taking washout as indicating malignancy, the sensitivity, specificity, and accuracy for malignant lesion identification during these phases was 61.8%, 98.7%, and 77.4%. On hepatobiliary phase images, 289 of 302 FNH, 82 of 82 NRH, 1 of 59 HA or LA, 62 of 341 HCC or FL-HCC, and 2 of 105 metastases were hyperintense or isointense. Taking iso- or hyperintensity as an indication for lesion benignity, the sensitivity, specificity, accuracy, PPV, and NPV for benign lesion identification was 96.6%, 87.6%, 91.4%, 85.1%, and 97.3%, respectively.

CONCLUSIONS

Hepatobiliary phase imaging with gadobenate dimeglumine is accurate for distinguishing benign lesions from malignant or high-risk lesions. Biopsy should be considered for hypointense lesions on hepatobiliary phase images after gadobenate dimeglumine.

Solid focal liver lesions: dynamic and late enhancement patterns with the dual phase contrast agent gadobenate dimeglumine

INTRODUCTION

The purpose of this paper is to illustrate contrast enhancement patterns of solid focal liver lesions on dynamic and late phase imaging with gadobenate dimeglumine (Gd-BOPTA).

IMAGING FINDINGS

Unenhanced T2- and T1-weighted, dynamic T1-weighted (arterial, portal-venous, and equilibrium) and late phase (1-3 h) Gd-BOPTA-enhanced MR imaging of different focal liver lesions (nodular regenerative hyperplasia, hepatic adenoma, liver adenomatosis, hepatocellular carcinoma, peripheral cholangiocarcinoma, hypervascular metastases, and hypovascular metastases) are shown. Dynamic imaging was performed using GRE T1-w sequences after the bolus injection of 0.1 mmol/kg Gd-BOPTA; late-phase imaging was obtained at 1-3 h after contrast injection.

CONCLUSIONS

Dynamic imaging with Gd-BOPTA provides the same information as with conventional gadolinium-based extracellular contrast agents, while late-phase imaging gives additional information for lesion identification and characterization.

CT and MRI of hepatocellular carcinoma: an update

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide and one of the few malignancies with an increasing incidence in the USA. Imaging plays a crucial role in early detection, accurate staging and planning management strategies. Contrast material-enhanced MRI or computed tomography (CT) are the best imaging techniques currently available for the noninvasive diagnosis of HCC. The diagnosis of HCC is strongly dependent on hemodynamic features (arterial hypervascularity and washout in the venous phase) on dynamic imaging, and biopsy is no longer recommended for tumors with classical imaging features prior to treatment. The major challenge for radiologists in imaging cirrhosis is the characterization of hypervascular nodules smaller than 2 cm, which often have nonspecific imaging characteristics. In this review, we discuss the role of CT and MRI in the diagnosis and staging of HCC. The strengths and current limitations of these imaging modalities are highlighted.

Gadoxetic acid (Gd-EOB-DTPA)-enhanced MRI versus gadobenate dimeglumine (Gd-BOPTA)-enhanced MRI for preoperatively detecting hepatocellular carcinoma: an initial experience

OBJECTIVE

This study was designed to compare the diagnostic performance of gadoxetic acid-enhanced magnetic resonance imaging (MRI) with gadobenate dimeglumine-enhanced MRI for preoperatively detecting hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Eighteen consecutive patients (17 men and one woman, age range: 31-73 years) with 22 HCCs underwent examinations with gadoxetic acid enhanced MRI and gadobenate dimeglumine-enhanced MRI on a 3.0-Tesla unit. The diagnosis of HCC was established after surgical resection and pathological conformation. Three observers independently reviewed each MR image in a random order on a tumor-by-tumor basis. The diagnostic accuracy of these techniques for the detection of HCC was assessed by performing an alternative free-response receiver operating characteristic (ROC) analysis. The sensitivity and positive predictive values were evaluated.

RESULTS

The average value of the area under the ROC curve (Az) for gadoxetic acid enhanced MRI (0.887) was not significantly different from the Az (0.899) for gadobenate dimeglumine-enhanced MRI (p > 0.05). The overall sensitivities of gadoxetic acid enhanced MRI and gadobenate dimeglumine-enhanced MRI were 80% and 83%, respectively, with no significant difference (p > 0.05). The differences of the positive predictive values for the two contrast agents for each observer were not statistically significant (p > 0.05).

CONCLUSION

The diagnostic performance of gadoxetic acid-enhanced MRI and gadobenate dimeglumine-enhanced MRI for preoperatively detecting HCC is quite similar.

Diffuse liver disease: strategies for hepatic CT and MR imaging

The liver plays several complex but essential roles in the metabolism of amino acids, carbohydrates, and lipids, as well as synthesis of proteins. The basic pathophysiology of diffuse parenchymal hepatic diseases usually represents a failure in one of these metabolic pathways. Specific parenchymal diseases can be categorized as storage, vascular, and inflammatory diseases. Cross-sectional hepatic imaging techniques, specifically multidetector computed tomography (CT) and magnetic resonance (MR) imaging, have roles in evaluation of diffuse liver disease. The prominent role of multidetector CT is primarily defined by its excellent morphologic visualization capabilities, in particular of diffuse or focal intrahepatic lesions as well as of anatomic relationships between the liver and adjacent organs. The variety of available multidetector CT scanners covers a huge spectrum of detector configurations ranging from equally sized and equally spaced detector arrays to asymmetric detector configurations, resulting in imaging protocols with unique parameters for almost each multidetector CT system. In addition to 64-detector row imaging, hepatic multidetector CT can be performed with emerging techniques such as dual-energy CT. Hepatic MR imaging has been proved to be a comprehensive modality for assessing the morphology and functional characteristics of the liver. Concurrent technical improvements as well as implementation of advanced imaging sequence designs permit high-quality examination of the liver with T1-, T2-, and diffusion-weighted pulse sequences. Three basic demands remain if MR imaging is chosen for hepatic imaging: to improve parenchymal contrast, to suppress respiratory motion, and to ensure complete anatomic coverage. Supplemental material available at http://radiographics.rsna.org/content/29/6/1591/suppl/DC1.

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.

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.

Hepatocellular carcinoma in liver transplantation candidates: detection with gadobenate dimeglumine-enhanced MRI

OBJECTIVE

The purpose of this study was to retrospectively evaluate the diagnostic performance of dynamic gadobenate dimeglumine-enhanced MRI with explant pathologic correlation in the detection of hepatocellular carcinoma (HCC) in patients undergoing liver transplantation.

MATERIALS AND METHODS

Forty-seven patients (28 men, 19 women; mean age, 49 years) underwent dynamic gadobenate dimeglumine-enhanced MRI within 3 months before primary liver transplantation. Dynamic imaging was performed before (unenhanced) and after (hepatic arterial, portal venous, equilibrium, and 1-hour delayed phases) IV bolus administration of gadobenate dimeglumine at 0.1 mmol/kg body weight. Retrospective image analysis to detect HCC nodules was performed independently by two abdominal radiologists who had no pathologic information. On a per-nodule basis, the sensitivity and positive predictive value were calculated for the two observers. Sensitivity and specificity in the diagnosis of HCC also were evaluated. Fisher's exact test was performed to determine whether there was a detection difference between HCC nodules 1 cm in diameter or larger and nodules smaller than 1 cm and to evaluate the differences in causes of false-positive MRI findings based on lesion size (>or= 1 cm vs < 1 cm).

RESULTS

Twenty-seven patients had 41 HCCs. In HCC detection, gadobenate dimeglumine-enhanced MRI had a sensitivity of 85% (35 of 41 HCCs) and a positive predictive value of 66% (35 of 53 readings) for observer 1 and a sensitivity of 80% (33 of 41 HCCs) and a positive predictive value of 65% (34 of 52 readings) for observer 2. For both observers, sensitivity in the detection of HCCs 1 cm in diameter and larger (91-94%) was significantly different (p < 0.05) from that in detection of HCCs smaller than 1 cm (29-43%). Nonneoplastic arterial hypervascular lesions more often caused false-positive diagnoses of lesions smaller than 1 cm in diameter (80-86%) on MR images than of those 1 cm in diameter and larger (0-25%). The difference was statistically significant (p < 0.05) for both observers. In diagnosis, gadobenate dimeglumine-enhanced MRI had a sensitivity of 87% (20 of 23 patients) and a specificity of 79% (19 of 24 patients) for both observers.

CONCLUSION

Dynamic gadobenate dimeglumine-enhanced MRI has a sensitivity of 80-85% and a positive predictive value of 65-66% in the detection of HCC. The technique, however, is of limited value for detecting and characterizing lesions smaller than 1 cm in diameter.

Focal liver lesions: Whether a standard dose (0.05mmol/kg) gadobenate dimeglumine can provide the same diagnostic data as the 0.1mmol/kg dose

OBJECTIVE

Gadobenate dimeglumine (Gd-BOPTA) is a liver-specific contrast agent also showing a distribution in the extracellular compartment which is recommended to be used at standard dose (0.05 mmol/kg) in magnetic resonance imaging (MRI) of liver lesions. However, its use at 0. 1mmol/kg is gradually increasing in recent clinical practice. Which dose should we use in routine MRI of liver lesions from now on? This study investigated the efficacy of Gd-BOPTA at a standard dose versus 0.1 mmol/kg dose in demonstrating diagnostic data in MRI of focal liver lesions.

MATERIALS AND METHODS

The study included 47 patients with focal liver lesions. Twenty-two patients received standard dose and 25 patients received 0.1 mmol/kg dose Gd-BOPTA intravenously. MRI of both groups was carried out with T1-A FLASH-2D and T2-A TURBO spin echo before contrast injection and T1-A FLASH-2D sequences in dynamic and late phase (90th minute) after the contrast injection. The lesion conspicuity for each image was evaluated qualitatively. Liver signal to noise ratio (SNR), absolute lesion-liver contrast to noise ratio (CNR), mean lesion-liver CNR and contrast enhancement rate of the liver obtained from both groups were compared quantitatively.

RESULTS

While liver contrast enhancement rate in the group receiving standard dose Gd-BOPTA were 41%+/-42 in the arterial phase, 66%+/-58 in the portal phase, 45%+/-45 in the venous phase and 42%+/-88 in the late phase, these values were 43%+/-59, 86%+/-73, 63%+/-75 and 61%+/-105, respectively, in the group receiving the dose of 0.1 mmol/kg. There were no statistically significant differences between the means of both groups. While the absolute lesion-liver CNR values were 18+/-15 precontrast, 22+/-18 in the arterial phase, 19+/-17 in the portal phase, 15+/-10 in the venous phase and 24+/-26 in the late phase in the group receiving the standard dose Gd-BOPTA, these values were 13+/-11, 18+/-15, 15+/-15, 13+/-13 and 19+/-21, respectively, in the group receiving the 0.1 mmol/kg dose. There were no statistically significant differences between the means of both groups (p>0.05). However, when the mean lesion-liver CNR values were compared, there was statistically significant difference between each arterial and portal phases of metastases in both groups (p<0.05). There was no statistical difference found in other lesions. When lesion conspicuity scores were compared, there were no significant differences between the two groups.

CONCLUSION

In liver lesions, similar diagnostic data are obtained in dynamic and late phase MRI with either standard dose Gd-BOPTA or with a dose of 0.1 mmol/kg. Because there was a difference in only metastases in both groups, in oncological patients who are being investigated for liver metastasis, it is expedient to use a dose of 0.1 mmol/kg.

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.

[Radiological diagnosis of hepatic tumors. Part II: Identification and differential diagnosis]

Focal hepatic lesions occur in 5% of the population. The clarification of such common occurrences is of major significance because oncological diseases play an important role with respect to morbidity and mortality of the population. The first part of this review article dealt with the most important aspects of classification, epidemiology and pathology of hepatic tumors for radiologists and the current technical situation with regards to the diagnostic procedure. This second part of the review deals with the significance of radiological procedures for identification and differential diagnosis of hepatic tumors.

Gadolinium-enhanced MRI for tumor surveillance before liver transplantation: center-based experience

OBJECTIVE

The purpose of this study was to evaluate prospectively acquired institutional results to determine the accuracy of gadolinium-enhanced MRI in liver tumor surveillance before transplantation.

SUBJECTS AND METHODS

One hundred fifteen patients underwent MRI of the abdomen within 90 days before liver transplantation. Images were acquired with gadolinium-enhanced 3D gradient-echo sequences in the arterial, venous, and delayed phases. Detection of hepatocellular carcinoma (HCC) was based on the imaging criteria arterial phase enhancement, delayed phase hypointensity, and development of an enhancing outer margin capsule. Imaging findings were compared with findings at histopathologic evaluation of the explanted liver.

RESULTS

Thirty-six HCCs in 27 patients were detected at histopathologic evaluation. Patient-based analysis showed the sensitivity of MRI was 88.9% (24/27); specificity, 97.7% (false-positive findings in two patients); and accuracy, 95.7%. MRI depicted 28 of 36 HCCs, resulting in a lesion-based sensitivity of 77.8%. Although all 18 HCCs 2 cm or larger were depicted with MRI, only 10 of 18 HCCs smaller than 2 cm were correctly diagnosed. However, two HCCs measuring smaller than 2 cm at pathologic examination were rated as dysplastic nodules on MRI.

CONCLUSION

Contrast-enhanced MRI can be used as a primary diagnostic method for accurate detection and characterization of HCC 2 cm or larger as required by the criteria of the Model for End-Stage Liver Disease used by the United Network for Organ Sharing. MRI can be considered a standard tool for surveillance before liver transplantation. Reduction in cost and risk may be derived from the diminished need for other diagnostic imaging studies and biopsy and the avoidance of use of iodinated contrast agents in imaging of patients with cirrhosis, many of whom have impaired renal function.

Usefulness of Combining Sequentially Acquired Gadobenate Dimeglumine-Enhanced Magnetic Resonance Imaging and Resovist-Enhanced Magnetic Resonance Imaging for the Detection of Hepatocellular Carcinoma

OBJECTIVE

To investigate the diagnostic efficacy of sequentially acquired gadobenete dimeglumine-enhanced 3-dimensional dynamic magnetic resonance imaging (MRI) and Resovist-enhanced MRI for detecting hepatocellular carcinoma (HCC) by comparing with combined computed tomography (CT) hepatic arteriography (CTHA) and CT arterioportography (CTAP) using 16-slice multidetector CT.

MATERIALS

Twenty-nine patients with 50 HCCs underwent sequentially acquired double-contrast MRI--gadobenate dimeglumine-enhanced dynamic MRI and Resovist-enhanced MRI--and combined CTHA and CTAP using 16-slice multidetector CT. Dynamic MRI was obtained using volumetric interpolated technique and sensitivity encoding on a 1.5-T unit. Resovist-enhanced MRI was composed of T2-weighted turbo spin-echo and T2*-weighted gradient echo sequences. Sensitivity, positive predictive value, and diagnostic accuracy for double-contrast MRI, gadolinium-enhanced MRI, and combined CTHA and CTAP were calculated by 2 observers using an alternative-free response receiver operating characteristic analysis.

RESULTS

For all observers, the Az values of double-contrast MRI (mean, 0.96) and combined CTHA and CTAP (mean, 0.93) were similar, which tended to be better than that of gadolinium-enhanced MRI (mean, 0.91). The sensitivity of double-contrast MRI (mean, 93%) and combined CTHA and CTAP (mean, 92%) was equivalent for all observers, which was better than that of gadolinium-enhanced MRI (mean, 85%; P < 0.05). The positive predictive value of double-contrast MRI was better than that of combined CTHA and CTAP (P < 0.05).

CONCLUSION

The sequentially acquired double-contrast MRI and combined CTHA and CTAP showed a similar diagnostic accuracy and sensitivity for detecting HCC.

Double-dose 1.0-M gadobutrol versus standard-dose 0.5-M gadopentetate dimeglumine in revealing small hypervascular hepatocellular carcinomas

The purpose of this study was to compare the diagnostic efficacy of double-dose 1.0-M gadobutrol with that of standard-dose 0.5-M gadopentetate dimeglumine for revealing small hypervascular hepatocellular carcinomas (HCCs). Twenty-three patients with 37 HCCs (mean size: 1.2 cm) that were diagnosed by histology (n = 13) or imaging findings (n = 10) underwent two separate 3D dynamic MRIs with 0.2 mmol/kg of gadobutrol and 0.1 mmol/kg of gadopentetate dimeglumine. Three observers interpreted both MRIs in terms of lesion detection using the alternative-free response receiver operating characteristic method and lesion-to-liver contrast using matched pairs analysis. The two MRIs were also compared quantitatively by measuring the signal-to-noise ratio (SNR) of the liver and lesion as well as the lesion-liver contrast-to-noise ratio (CNR). The SNR of the liver and lesion and lesion-liver CNR with gadobutrol were better than those with gadopentetate dimeglumine (p < 0.01). However, in terms of the diagnostic accuracy (mean Az for gadobutrol: 0.878, and mean Az for gadopentate dimeglumine: 0.873), the sensitivity (92.8%), positive predictive value (92.8% vs. 93.7%) and lesion-liver contrast, the two dynamic MRIs were equivalent. Gadobutrol showed a superior degree of enhancement for hypervascular HCC than did gadopentetate dimeglumine, but the diagnostic capabilities of the two agents for revealing HCCs were equivalent.

Evaluation of a Novel Time-Efficient Protocol for Gadobenate Dimeglumine (Gd-BOPTA)-Enhanced Liver Magnetic Resonance Imaging

OBJECTIVE

We sought to evaluate gadobenate dimeglumine for the detection and characterization of focal liver lesions in the unenhanced and already pre-enhanced liver.

MATERIALS AND METHODS

Sixty patients were evaluated prospectively. Unenhanced T1-weighted gradient echo (T1wGRE) and T2-weighted turbo spin echo (T2wTSE) images were acquired followed by contrast-enhanced T1wGRE images during the dynamic, equilibrium, and delayed phases after the bolus injection of 0.05 mmol/kg gadobenate dimeglumine. An identical series of dynamic images was then acquired after the delayed scan following a second 0.05 mmol/kg bolus of gadobenate dimeglumine. Images were evaluated randomly in 2 sessions by 3 independent blinded readers. Evaluated images in the first session comprised the unenhanced images, the first or second set of dynamic images, and the delayed images. The second session included the unenhanced images, the dynamic images not yet evaluated in the first session, and the delayed images. The 2 reading sessions were compared for lesion characterization and diagnosis, and kappa (kappa) values for interobserver agreement were determined. Quantitative evaluation of lesion contrast enhancement was also performed.

RESULTS

The enhancement behavior in the second dynamic series was similar to that in the first series, although pre-enhancement of the normal liver resulted in reduced lesion-liver contrast-to-noise ratios and the visualization of some lesions only on arterial phase images. Typical imaging features for the lesions included in the study were visualized clearly in both series. Strong agreement (kappa=0.56-0.89; all evaluations) between the 2 images sets was noted by all readers for differentiation of benign from malignant lesions and for definition of specific diagnosis, and between readers for diagnoses established based on images acquired in the unenhanced and pre-enhanced liver.

CONCLUSION

Dynamic imaging in the hepatobiliary phase gives similar information as dynamic imaging of the unenhanced liver. This might prove advantageous for screening protocols involving same session imaging of primary extrahepatic tumors and liver.

Radioembolization with 90Yttrium microspheres: a state-of-the-art brachytherapy treatment for primary and secondary liver malignancies. Part 1: Technical and methodologic considerations

Microsphere and particle technology represent the next-generation agents that have formed the basis of interventional oncology, an evolving subspecialty of interventional radiology. One of these platforms, yttrium-90 microspheres, is rapidly being adopted in the medical community as an adjunctive therapeutic tool in the management of primary and secondary liver malignancies. Given the complexity of the treatment algorithm of patients who may be candidates for this therapy and the need for clinical guidance, a comprehensive review of the methodologic and technical considerations was undertaken. This experience is based on more than 900 (90)Y infusions performed over a 5-year period.

Application of superparamagnetic iron oxide to imaging of hepatocellular carcinoma

Superparamagnetic iron oxide (SPIO) particles are as MR contrast media composed of iron oxide crystals coated with dextran or carboxydextran. These particles are sequestered by phagocytic Kupffer cells in normal reticuloendothelial system (RES), but are not retained in tumor tissue. Consequently, there are significant differences in T2/T2* relaxation between normal RES tissue and tumors, which result in increased lesion conspicuity and detectability. The introduction of SPIO has been expected to substantially increase the detectability of hepatic metastases. For focal hepatocellular lesions, it has been documented that SPIO-enhanced MR imaging exhibits slightly better diagnostic performance than dynamic helical CT in the detection of hypervascular hepatocellular carcinoma (HCC). A combination of dynamic and static MR imaging technique using T1- and T2 imaging criteria appears to provide clinically more useful patterns of enhancement. SPIO-enhanced MR imaging also provides information useful for differential diagnosis, via enhancement of RES-containing tumors. With the exploitation of rapid T2*-sensitive sequences, SPIO-enhanced dynamic MR imaging may become comparable to gadolinium-enhanced dynamic MR imaging and dynamic studies with multidetector-row CT. SPIO-enhanced MR imaging plays an important role in therapeutic decision-making for patients with HCC.

Liver masses

In summary, MR imaging is superior to other imaging modalities, including CT, for the work-up of liver masses. The current challenge is whether the superior performance of MR imaging translates into a beneficial effect on patient management, disease outcome, and health care costs. New MR sequences, phased-array surface coils, and tissue-specific MR contrast agents suggest that MR imaging may exceed further the diagnostic ability of CT.

[Current status of MRI diagnostics with liver-specific contrast agents. Gd-EOB-DTPA and Gd-BOPTA]

The contrast agents Gd-EOB-DTPA and Gd-BOPTA can be administered by bolus injection and are appropriate for use in MRI both as vascularization markers and markers of hepatobiliary excretion. This contribution presents an overview of the specific characteristics of contrast media and the status of clinical development. In comparison to CT and to MRI with unspecific extracellular Gd-chelates, liver-specific contrast agents offer advantages in differentiating unclear liver lesions, increasing the detection rate, and examining the bile duct system.

Gradient echo acquisition for superparamagnetic particles with positive contrast (GRASP): Sequence characterization in membrane and glass superparamagnetic iron oxide phantoms at 1.5T and 3T

Iron oxides are used for cell trafficking and identification of macrophages in plaque using MRI. Due to the negative contrast, differentiation between signal loss caused by iron and native low signal in tissue may be problematic. It is, therefore, preferable to achieve positive contrast. The purpose of this study was to test the efficacy of a new MRI sequence GRASP (GRe Acquisition for Superparamagnetic Particles) to generate a positive signal in phantoms containing iron. Membrane phantoms were constructed containing Ferumoxide at 7 concentrations. Standard GRE sequences were modified with user controlled z-gradient rephasing (+/- 100%). CNR values were determined as a function of echo time (TE) and % rephasing at 1.5T and 3T. T(2)* values were determined using multiple double-echo GRE. The GRASP sequence generated positive signal enhancement in phantoms containing iron. For all rephasing values <or=30%, positive contrast was observed. The CNR generated at 1.5T was greater than the values at 3T for all concentrations tested. Correlation between CNR at 0% and 100% rephasing was observed at 1.5T(R = 0.84). Additionally, correlation between field change across the volume and CNR was observed. In conclusion, GRASP sequences may be used to generate positive signal enhancement in the presence of iron using MRI.