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

Peritumoral Imaging Manifestations on Gd-EOB-DTPA-Enhanced MRI for Preoperative Prediction of Microvascular Invasion in Hepatocellular Carcinoma: A Systematic Review and Meta-Analysis

Purpose

The aim was to investigate the association between microvascular invasion (MVI) and the peritumoral imaging features of gadolinium ethoxybenzyl DTPA-enhanced magnetic resonance imaging (Gd-EOB-DTPA-enhanced MRI) in hepatocellular carcinoma (HCC).

Methods

Up until Feb 24, 2022, the PubMed, Embase, and Cochrane Library databases were carefully searched for relevant material. The software packages utilized for this meta-analysis were Review Manager 5.4.1, Meta-DiSc 1.4, and Stata16.0. Summary results are presented as sensitivity (SEN), specificity (SPE), diagnostic odds ratios (DORs), area under the receiver operating characteristic curve (AUC), and 95% confidence interval (CI). The sources of heterogeneity were investigated using subgroup analysis.

Results

An aggregate of nineteen articles were remembered for this meta-analysis: peritumoral enhancement on the arterial phase (AP) was described in 13 of these studies and peritumoral hypointensity on the hepatobiliary phase (HBP) in all 19 studies. The SEN, SPE, DOR, and AUC of the 13 investigations on peritumoral enhancement on AP were 0.59 (95% CI, 0.41−0.58), 0.80 (95% CI, 0.75−0.85), 4 (95% CI, 3−6), and 0.73 (95% CI, 0.69−0.77), respectively. The SEN, SPE, DOR, and AUC of 19 studies on peritumoral hypointensity on HBP were 0.55 (95% CI, 0.45−0.64), 0.87 (95% CI, 0.81−0.91), 8 (95% CI, 5−12), and 0.80 (95% CI, 0.76−0.83), respectively. The subgroup analysis of two imaging features identified ten and seven potential factors for heterogeneity, respectively.

Conclusion

The results of peritumoral enhancement on the AP and peritumoral hypointensity on HBP showed high SPE but low SEN. This indicates that the peritumoral imaging features on Gd-EOB-DTPA-enhanced MRI can be used as a noninvasive, excluded diagnosis for predicting hepatic MVI in HCC preoperatively. Moreover, the results of this analysis should be updated when additional data become available. Additionally, in the future, how to improve its SEN will be a new research direction.

Hepatocellular Carcinoma: Retrospective Evaluation of the Correlation Between Gadobenate Dimeglumine-Enhanced Magnetic Resonance Imaging and Pathologic Grade

OBJECTIVE

The aim of this study was to evaluate the usefulness of gadobenate dimeglumine-enhanced magnetic resonance imaging in characterizing the grade of hepatocellular carcinoma (HCC) using the signal intensity (SI) of the erector spinae as internal reference.

MATERIALS AND METHODS

Clinical data of 40 patients (a total of 44 lesions) confirmed by pathology for HCC were retrospectively reviewed. Gadobenate dimeglumine-enhanced magnetic resonance imaging was performed in all patients, and SI of lesions (SIles), liver parenchyma around the lesions (SIhep), erector spinae (SImus) and standard deviation of SI of the surrounding noise (SDnoi) on nonenhanced T2WI, nonenhanced T1WI, and contrast-enhanced T1WI (in both arterial and hepatobiliary phase [AP and HBP]) were measured, respectively. Contrast-to-noise ratio (CNR) were separately defined as CNR1 ([SIles - SIhep]/SDnoi) and CNR2 ([SIles - SImus]/SDnoi). Statistical analyses were performed using one-way analysis of variance, least significant difference test, logistic regression analysis, Spearman rank correlation, and receiver operating characteristic curves analysis.

RESULTS

Forty-four HCCs, including 3 well-differentiated HCCs, 26 moderately differentiated HCCs, and 15 poorly differentiated (PD) HCCs, were confirmed. On logistic regression analysis, only CNR2 in the HBP was predictor of PD HCCs (P = 0.015, odds ratio = 1.040). The size of lesions, CNR1 in the AP, CNR2 in the AP, and CNR2 in the HBP, showed significant correlations with the degree of differentiation (correlation coefficients = -0.371, 0.435, 0.503, and 0.512, respectively; P = 0.013, 0.003, 0.001, and 0.000, respectively). Contrast-to-noise ratio 2 in the HBP with the cutoff of less than 4.56 could distinguish moderately differentiated HCCs from PD HCC with the sensitivity and specificity of 84.6% and 60.0%, respectively.

CONCLUSIONS

Relatively low arterial enhancement and low CNR2 value in the HBP are predictive for poor histological grade of HCCs.

Investigations on the Ga(III) Complex of EOB-DTPA and Its 68Ga Radiolabeled Analogue

We demonstrate a method for the isolation of EOB-DTPA (3,6,9-triaza-3,6,9-tris(carboxymethyl)-4-(ethoxybenzyl)-undecanedioic acid) from its Gd(III) complex and protocols for the preparation of its novel non-radioactive, i.e., natural Ga(III) as well as radioactive (68)Ga complex. The ligand as well as the Ga(III) complex were characterized by nuclear magnetic resonance (NMR) spectroscopy, mass spectrometry and elemental analysis. (68)Ga was obtained by a standard elution method from a (68)Ge/(68)Ga generator. Experiments to evaluate the (68)Ga-labeling efficiency of EOB-DTPA at pH 3.8-4.0 were performed. Established analysis techniques radio TLC (thin layer chromatography) and radio HPLC (high performance liquid chromatography) were used to determine the radiochemical purity of the tracer. As a first investigation of the (68)Ga tracers' lipophilicity the n-octanol/water distribution coefficient of (68)Ga species present in a pH 7.4 solution was determined by an extraction method. In vitro stability measurements of the tracer in various media at physiological pH were performed, revealing different rates of decomposition.

[Contrast-enhanced magnetic resonance cholangiography using gadolinium-EOB-DTPA. Preliminary experience and clinical applications]

Magnetic resonance cholangiopancreaticography (MRCP) with heavily T2-weighted RARE and HASTE sequences has become an important imaging modality for the morphologic evaluation of intra- and extrahepatic bile ducts. However, for the diagnosis of functional biliary disorders, cholangiopancreaticography (ERCP) and endoscopic manometry, two invasive techniques with considerable morbidity and mortality, remain the standard. Biliary scintigraphy, secretin-stimulated MRCP, and secretin-stimulated endoscopic ultrasound have not proven to be sufficient to replace these techniques as they lack diagnostic accuracy and correlate poorly with manometry results. Contrast-enhanced magnetic resonance cholangiography (CE-MRC) uses hepatocyte-selective contrast agents that are eliminated by the biliary system. Therefore, these substances can serve as biliary contrast agents in T1-weighted MR imaging. This method makes a noninvasive functional evaluation of the hepatobiliary system possible. In the present article, our preliminary experience with Gd-EOB-DTPA-enhanced MRC is summarized and potential clinical applications of this method are discussed. Additionally, the article reviews publications evaluating a possible benefit of CE-MRC with other hepatobiliary contrast agents such as mangafodipir trisodium.

Magnetic resonance imaging of liver malignancies

The histological structure of the liver is complex, consisting of hepatocytes, biliary epithelium, and mesenchymal cells. From this large variety of cells, a broad spectrum of benign and malignant liver lesions in originate. An accurate diagnosis of these lesions is mandatory for choosing an appropriate therapeutic approach. With the recent developments in hardware and software, magnetic resonance imaging (MRI) has emerged as the method of choice in the diagnostic workup of focal liver lesions, in particular in the pretherapeutic stage. The introduction of high-field MRI at 3.0 T in the routine workup and the selective use of liver-specific contrast agents, including hepatobiliary and reticuloendothelial agents, have also strengthened the role of MRI in liver imaging. In this overview article, we will review the recent developments in 3.0-T MRI and MRI contrast agents in the diagnostic workup of the most common malignant liver tumors.

[Diagnostic radiology of liver tumors. Part 1: General disease aspects and radiological procedures]

Besides malignant disease, focal liver lesions can also represent benign changes. Among the malignant lesions, in addition to hepatocellular carcinoma, liver metastases should be mentioned. In contrast, benign lesions such as focal nodular hyperplasia and hepatocellular adenoma are rarely encountered. Various radiological procedures are employed for the (differential) diagnosis. The transabdominal ultrasound examination is supplemented by color Doppler procedures, contrast-enhanced or intraoperative ultrasound. Computed tomography (CT) should be performed with native images as well as after using modern nonionic, iodine-containing water-soluble contrast agents; multidetector spiral CT is today's standard. If comparable optimal technology is available on-site, (contrast-enhanced) MRI is preferable. Intra-arterial selective angiography has become less important for detecting and characterizing focal liver changes with the advent of tomographic procedures. The question of whether sonography- or CT-guided biopsy of the liver is needed for further diagnostic work-up, whether a wait-and-see approach is justified, or whether surgery is required to clarify the diagnosis should always be answered on a case-by-case basis.

Technology Insight: advances in liver imaging

The role of diagnostic imaging in the assessment of liver disease continues to gain in importance. The classic techniques used for liver imaging are ultrasonography, CT and MRI. In the past decade, there have been significant advances in all three techniques. In this article, we discuss the advances in ultrasonography, CT and MRI that have improved assessment of focal and diffuse liver disease, including the development of hardware, software, processing algorithms and procedural innovations.

Dynamic and delayed contrast enhancement in upper abdominal MRI studies: comparison of gadoxetic acid and gadobutrol

OBJECTIVE

To prospectively compare contrast properties of extracelullar (gadobutrol) and hepatospecific (gadoxetic acid) contrast agents in upper abdominal MRI studies.

MATERIALS AND METHODS

Standardized (0.1 ml/kg) dose of gadobutrol (56 subjects) and gadoxetic acid (51 subjects) was administered intravenously by MRI-compatible injector at 2 ml/s, followed by 20 ml saline flush. MR signal intensity changes (SIC) between precontrast scans and arterial phase, portal venous phase, equilibrium, and delayed scans at 10 and 20 min were measured in abdominal aorta, portal vein, common bile duct, liver, and spleen. Mean SIC values for gadobutrol and gadoxetic acid were compared by a two-sample t-test with p-value <0.05 considered significant.

RESULTS

In abdominal aorta, the mean SIC in the arterial phase did not significantly differ between gadobutrol (330%) and gadoxetic acid (295%). In portal vein, the mean SIC in the portal venous phase significantly differed between gadobutrol (267%) and gadoxetic acid (176%). Liver parenchyma enhancement was significantly higher for gadobutrol than for gadoxetic acid in both arterial phase (28 versus 13%) and portal venous phase (81 versus 46%). On the contrary, gadobutrol reached significantly lower mean SIC in the liver on delayed scans at 10 min (47 versus 59%) and 20 min (40 versus 67%), as well as in common bile duct at 10 min (54 versus 133%) and 20 min (57 versus 457%), respectively. In the spleen, mean SIC for gadobutrol was significantly higher at all phases.

CONCLUSION

Gadobutrol showed superior enhancement of upper abdominal structures in the dynamic phases whereas gadoxetic acid showed better enhancement of the hepatobiliary structures on delayed scans.

Contrast agents in abdominal imaging: current and future directions

Magnetic resonance imaging is an established imaging method for the evaluation of the abdomen. Accurate assessment of the liver, spleen, pancreas, bile ducts, vascular structures, and retroperitoneal organs (eg, the kidneys, the collecting system, and the adrenals) are possible on MR imaging. The intravenous administration of MR contrast agents can frequently improve the examination and provide more specific diagnoses. The advent of more specific, "hepatobiliary" contrast agents has further improved the differential diagnostic process, particularly for MR imaging of the liver. The availability of orally administered MR contrast agents has further extended the range of abdominal applications, making MR imaging of the small bowel and the colon established imaging procedures.