Quantitative and qualitative evaluation of high-quality hepatobiliary phase imaging with shortened timing and utility in patients with compromised liver function

PURPOSE

To compare high flip angle (FA) hepatobiliary-phase (hHBP) imaging with variable time intervals to conventional HBP (cHBP) to assess the impact of increased FA on image quality in shortened HBP imaging.

METHODS

Data from 218 patients, divided into normal liver group (n = 184) and decompensated liver group (n = 34), who underwent liver magnetic resonance imaging (MRI) including 10-min, 15-min, 20-min hHBP, and cHBP were analyzed. Signal-to-noise ratio (SNR), contrast-ratio (CR), contrast-to-noise ratio (CNR), signal intensity ratios (SIRs), and relative enhancement (RE) of the liver were calculated for quantitative analysis. Sharpness, noise, and artifacts of the image, contrast media visibility, overall image quality, and lesion conspicuity were evaluated by two abdominal radiologists.

RESULTS

Quantitative analysis showed that SNR, RE, SIR for liver/muscle, liver/spleen, and CR of all hHBP images demonstrated a significantly higher value compared to cHBP images in the normal liver group (p < 0.001). These values were also superior in the normal liver group compared to the decompensated liver group (p < 0.01). In qualitative analysis, both normal and decompensated liver groups exhibited significantly superior image sharpness in all hHBP images compared to cHBP images and the overall image quality of the 15-min and 20-min hHBP did not show significant difference compared to cHBP. All values tended to be better in the normal liver group than the decompensated liver group with statistical significance except for lesion conspicuity (p < 0.01).

CONCLUSION

High-FA HBP has proven to be a valuable image acquisition method, potentially shortening liver MR imaging time while maintaining acceptable image quality.

Imaging cholangiocarcinoma: CT and MRI techniques

Cross-sectional imaging plays a crucial role in the detection, diagnosis, staging, and resectability assessment of intra- and extrahepatic cholangiocarcinoma. Despite this vital function, there is a lack of standardized CT and MRI protocol recommendations for imaging cholangiocarcinoma, with substantial differences in image acquisition across institutions and vendor platforms. In this review, we present standardized strategies for the optimal imaging assessment of cholangiocarcinoma including contrast media considerations, patient preparation recommendations, optimal contrast timing, and representative CT and MRI protocols with individual sequence optimization recommendations. Our recommendations are supported by expert opinion from members of the Society of Abdominal Radiology's Disease-Focused Panel (DFP) on Cholangiocarcinoma, encompassing a broad array of institutions and practice patterns.

Imaging Evaluation of the Living Liver Donor: A Systems-Based Approach

Liver transplant is the definitive treatment of end-stage liver disease and early hepatocellular carcinoma. The number of liver transplant surgeries done is highly affected by the number and availability of deceased donor organs. Living donor liver transplantation has emerged as an alternative source of donors, increasing the availability of organs for transplant. Many factors must be considered when choosing living donor candidates to maintain a high level of donor safety and organ survival. To that end, potential donors undergo a rigorous pre-donation workup.

Compressed sensing for breath-hold high-resolution hepatobiliary phase imaging: image noise, artifact, biliary anatomy evaluation, and focal lesion detection in comparison with parallel imaging

PURPOSE

To assess image quality, performance for biliary anatomy diagnosis, and focal lesion detection rate of breath-hold high-resolution 3D T1-weighted hepatobiliary phase imaging using compressed sensing (CS HBP) compared to standard HBP using conventional parallel imaging.

METHODS

This retrospective study assessed consecutive 125 patients who underwent CS HBP and standard HBP between November 2019 and July 2020. Optimized resolution and scan time for CS HBP were 1 × 1.4 × 1 mm³ and 15 s, while those for standard HBP were 1.3 × 1.8 × 3 mm³ and 16 s. Two independent radiologists evaluated qualitative indices on the clarity of liver margin, visibility of the hepatic vessel and bile duct, image noise, and artifact on a 5-point scale. Biliary anatomy, confidence for biliary anatomy diagnosis, expected number of bile duct openings, and number of focal lesions were assessed. Wilcoxon signed-rank test, Pearson chi-square test, and sensitivity for focal lesion were used for statistical analysis. Intraclass correlation coefficient (ICC) and Cohen's kappa (κ) were used to determine inter-observer agreement.

RESULTS

CS HBP showed significantly better liver edge sharpness and bile duct visualization, but greater subjective image noise and non-respiratory artifacts compared to standard HBP. CS HBP showed higher number of concordantly assigned biliary anatomy across readers (86 vs. 80), indicating greater inter-observer agreement for biliary anatomy (κ, 0.67 vs. 0.45) and the number of bile duct openings (ICC, 0.860 vs. 0.579) with significantly higher diagnostic confidence (4.70-4.74 vs. 3.96-4.55; p = 0.002). Both readers identified more focal lesions in CS HBP than in standard HBP (88.2% and 84.5% vs. 66.3% and 73.4%).

CONCLUSION

Breath-hold high-resolution CS HBP was a feasible clinical sequence providing superior liver edge sharpness, bile duct visualization, and focal lesion detection rate compared to standard HBP despite higher noise and artifact. Due to improved spatial resolution, CS HBP yielded a higher inter-observer agreement and confidence for the biliary anatomy diagnosis.

Imaging Evaluation of Living Liver Donor Candidates: Techniques, Protocols, and Anatomy

The need for liver transplants is increasing because the prevalence of liver diseases and the indications for transplants are growing. In response to the shortage of grafts from deceased donors, more transplants are being performed worldwide with grafts from living donors. Radiologic evaluation is an integral component in the assessment of donor candidates to ensure their eligibility and to choose the most appropriate surgical approach. MRI is the preferred modality for evaluation of the liver parenchyma and biliary tree. In most centers, a combination of MRI and CT is used to take advantage of the higher spatial resolution of CT for evaluation of arteries. However, MRI-only assessment is feasible. In addition to assessment of the liver parenchyma for abnormalities such as steatosis, a detailed evaluation of the hepatic vascular and biliary system for pertinent anatomic variants is crucial, because these variants can affect surgical techniques and outcomes in both recipients and donors. In this pictorial article, after a brief review of the most common surgical techniques and postsurgical liver anatomy, the biliary and vascular anatomy are discussed, with specific attention paid to the variants that are pertinent to this surgical procedure. The roles of liver segmentation and volumetric assessment and current imaging techniques and protocols are also discussed. Online supplemental material is available for this article. ©RSNA, 2021.

Assessment of biliary anatomy in potential living liver donors: Added value of gadoxetic acid-enhanced T1 MR Cholangiography (MRC) including utilization of controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA) technique in comparison to T2W-MRC

OBJECTIVES

To assess the added value of gadoxetic-acid-enhanced T1-weighted magnetic resonance Cholangiography (T1W-MRC) including controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA)-Volumetric Interpolated Breathhold (VIBE) technique compared to T2-weighted MR Cholangiography (T2W-MRC) in depicting biliary anatomy in potential living liver donors.

METHODS

Eighty-five potential donors including 34 men with a mean age of 35.6 years (range, 18-55 years) and 51 women with a mean age of 36.7 years (range, 23-57 years), were enrolled in this ethics-approved retrospective study. Image quality for depiction of bile ducts was evaluated by two readers in consensus in 3 separate reading sessions: 1) T2W-MRC alone, 2) T1W-MRC alone (including CAIPI-VIBE and generalized autocalibrating partially parallel acquisitions (GRAPPA)-VIBE techniques, and 3) combined T1W/T2W-MRC. Accuracy of T2W-MRC, T1W-MRC, and combined T1W/T2W-MRC for the identification/classification of the biliary variants was calculated using intraoperative cholangiogram (IOC) as the reference standard. Image quality and reader diagnostic confidence provided by CAIPI-VIBE technique was compared with GRAPPA-VIBE technique. Datasets were compared using the Wilcoxon signed-rank test.

RESULTS

Image quality for depiction of the bile ducts was significantly superior in the combined T1W/T2W-MRC group, when compared to each of T2W-MRC and T1W-MRC groups independently (P value = 0.001-0.034). The combination of CAIPI-VIBE and GRAPPA-VIBE was superior compared to each of the sequences individually. The accuracy of T2W-MRC and T1W-MRC was 93% and 91%, respectively. T1W-MRC depicted four biliary variants better than T2W-MRC. Two variants not well seen in T2W-MRC were clearly shown on T1W-MRC.

CONCLUSION

Gadoxetic-acid-enhanced T1W-MRC and conventional T2W-MRC techniques are complementary for depiction of biliary variants in potential liver donors and the combination of the two improves the results. The combination of CAIPI-VIBE and GRAPPA-VIBE techniques appear to be complementary for optimal diagnostic yield of T1W-MRC.

High spatial resolution navigated 3D T1-weighted hepatobiliary MR cholangiography using Gd-EOB-DTPA for evaluation of biliary anatomy in living liver donors

PURPOSE

To determine the feasibility of high-resolution navigated three-dimensional (3D) T1-weighted hepatobiliary MR cholangiography (Nav T1 MRC) using Gd-EOB-DTPA for biliary visualization in living liver donors and to assess added value of 3D T1-weighted hepatobiliary MRCs in improving the confidence and diagnostic accuracy of biliary anatomy in complementary to T2-weighted MRCs.

METHODS

Twenty-nine right liver donors underwent 3D T2 MRC, 2D T2 MRC, breath-hold T1-weighted hepatobiliary MRC (BH T1 MRC), and Nav T1 MRC. Two readers independently reviewed and compared 3D/2D MRC set, added BH T1 MRC set, and added Nav T1 MRC set for biliary diagnostic accuracy and confidence. For each MRC, biliary segments visualization and image quality were scored.

RESULTS

Both BH T1 MRC and Nav T1 MRC improved accuracy and specificity in biliary diagnosis when added to 3D/2D T2 MRC-alone set, though without statistical significance (R1, 82.8% to 93.1%; R2, 82.8% to 89.7%). The added Nav T1 MRC set showed the highest diagnostic confidence with both readers. Both readers scored Nav T1 MRC with the highest visualization scores for branching ducts and overall ducts.

CONCLUSION

Combining T1-weighted hepatobiliary MRCs to 3D/2D T2 MRC set improved accuracy for biliary anatomy diagnosis; time-efficient BH T1 MRC in axial and coronal planes should be considered as a key MRC sequence complementary to T2 MRCs. Given excellent biliary visualization and superior diagnostic confidence, Nav T1 MRC in selected subjects with breath-hold difficulties and inconclusive or complex biliary variations may assist in reaching a correct biliary diagnosis.

Change in Liver Imaging Reporting and Data System Characterization of Focal Liver Lesions Using Gadoxetate Disodium Magnetic Resonance Imaging Compared With Contrast-Enhanced Computed Tomography

PURPOSE

The aim of this study was to determine whether gadoxetate-enhanced magnetic resonance imaging (MRI) improves lesion characterization in patients at risk for hepatocellular carcinoma compared with computed tomography (CT).

MATERIALS AND METHODS

Forty-nine patients with indeterminate lesions found at contrast-enhanced CT were prospectively enrolled and imaged using gadoxetate-enhanced hepatobiliary phase (HBP) MRI within 30 days of their initial CT. Three readers graded each lesion at CT and MRI using the Liver Imaging Reporting and Data System (LI-RADS) v2014 major criteria and HBP characterization as an ancillary feature. Patients were followed for an average of 1.8 years to document growth or stability of each lesion.

RESULTS

The Liver Imaging Reporting and Data System categorization changed for 71% (52/73) of lesions based on HBP MRI compared with CT, with 30% (22/73) of lesions upgraded and 41% (30/73) of lesions downgraded. There was almost perfect agreement between readers for arterial phase hyperintensity and HBP hypointensity, with lower interreader agreement for washout and capsule appearance. On the basis of composite clinical follow-up, lesions that were subsequently classified as hepatocellular carcinoma were assigned a higher LI-RADS category on HBP MRI when compared with CT.

CONCLUSIONS

For patients with indeterminate lesions seen on contrast-enhanced CT, HBP MRI using gadoxetate improves lesion characterization when using LI-RADS v2014 criteria.

Multiple arterial phase MRI of arterial hypervascular hepatic lesions: improved arterial phase capture and lesion enhancement

PURPOSE

To establish if triple-phase arterial imaging improves the detection of arterial phase hyperintense lesions based on arterial phase capture, motion artifact degradation, and lesion enhancement when compared to single-phase imaging.

MATERIALS AND METHODS

Patients at risk for hepatocellular carcinoma were imaged at 3.0T. Seventy-three consecutive patients with a standard single-phase MRI and eighty-five consecutive patients were imaged using extracellular contrast with triple arterial phase MRI using three sequential accelerated acquisitions of 8 s. Arterial phase capture and image quality were qualitatively categorized. Forty single-phase and forty-four triple-phase studies contained arterially enhancing lesions > 1 cm with washout appearance. The contrast-to-noise ratio (CNR) of the lesions was calculated. We compared the differences in means with Student t-tests and those in arterial phase capture with a Chi squared test with Yates correction.

RESULTS

The triple-phase acquisitions captured the early or late arterial phases more frequently than did the single-phase acquisition (99% vs 86%; P value = 0.006). Triple-phase also provided greater number of patients with early or late arterial phase imaging without motion artifact (92% vs 79%, P-value = 0.05). The lesion analysis revealed increased maximum CNR in the triple-phase imaging (704.4) vs. single-phase imaging (517.2), P-value < 0.001.

CONCLUSION

Triple-phase acquisition provides more robust arterial phase imaging for hepatic lesions, with increased lesion CNR, compared to standard single-phase arterial phase imaging.

Feasibility of 10-Minute Delayed Hepatocyte Phase Imaging Using a 30° Flip Angle in Gd-EOB-DTPA-Enhanced Liver MRI for the Detection of Hepatocellular Carcinoma in Patients with Chronic Hepatitis or Cirrhosis

Objectives

To compare 10-minute (min) delayed hepatocyte phase imaging (HPI) using a 30° flip angle (FA) (10m-FA30) and 20-min delayed HPI using a 10° FA (20m-FA10) or 30° FA (20m-FA30) in Gd-EOB-DTPA-enhanced MRI in patients with chronic hepatitis or cirrhosis, in terms of lesion-to-liver contrast-to-noise ratio (CNR) for hepatocellular carcinoma (HCC) and detection sensitivity for focal hepatic lesions (FHLs).

Materials and Methods

One hundred and four patients with 168 HCCs and 55 benign FHLs who underwent Gd-EOB-DTPA-enhanced MRI with 10m-FA30, 20m-FA10, and 20m-FA30 were enrolled. Patients were divided into two groups according to the Child-Pugh classification: group A with chronic hepatitis or Child-Pugh A cirrhosis and group B with Child-Pugh B or C cirrhosis. Lesion-to-liver CNR for HCCs was compared between 10m-FA30 and 20m-FA10 or 20m-FA30 for each group. The presence of FHLs was evaluated using a four-point scale by two independent reviewers, and the detection sensitivity was analyzed.

Results

In group A, the CNR for HCCs (n = 86) on 10m-FA30 (165.8 ± 99.7) was significantly higher than that on 20m-FA10 (113.4 ± 71.4) and lower than that of 20m-FA30 (210.2 ± 129.3). However, there was no significant difference in the sensitivity of FHL detection between 10m-FA30 (mean 95.0% for two reviewers) and 20m-FA10 (94.7%) or 20m-FA30 (94.7%). In group B, the CNR (54.0 ± 36.4) for HCCs (n = 57) and the sensitivity (94.2%) of FHL detection for 10m-FA30 were significantly higher than those for 20m-FA10 (41.8 ± 36.4 and 80.8%, respectively) and were not different from those for 20m-FA30 (62.7 ± 44.4 and 93.3%, respectively).

Conclusion

The diagnostic performance of 10m-FA30 was similar to or higher than 20m-FA10 or 20m-FA30 in both groups A and B. This finding indicates that 10m-FA30 could replace 20-min delayed HPI regardless of patient liver function and reduce the delay time by 10 minutes.

Gadoxetic acid: pearls and pitfalls

Gadoxetic acid is a hepatocyte-specific magnetic resonance imaging contrast agent with the ability to detect and characterize focal liver lesions and provide structural and functional information about the hepatobiliary system. Knowledge of the pharmacokinetics of gadoxetic acid is paramount to understanding imaging protocol and lesion appearance and facilitates identification and avoidance of undesired effects with use of this intravenous contrast agent. This article reviews the utility of gadoxetic acid in liver and biliary imaging, with emphasis on the hepatobiliary phase.

Contrast-enhanced MR cholangiography with Gd-EOB-DTPA for preoperative biliary mapping: correlation with intraoperative cholangiography

BACKGROUND

Gd-EOB-DTPA-enhanced magnetic resonance (MR) could be used for preoperative evaluation of bile duct anatomy in addition to conventional information of focal hepatic lesions.

PURPOSE

To evaluate accuracy of contrast-enhanced MR cholangiography (CE MRC) reconstructed from Gd-EOB-DTPA-enhanced MR images for depicting biliary anatomy with intraoperative cholangiography.

MATERIAL AND METHODS

We retrospectively identified 71 patients who underwent both preoperative Gd-EOB-DTPA-enhanced MR imaging (MRI) and intraoperative cholangiography for hepatic resections. Two readers independently analyzed biliary anatomy using CE MRC reconstructed from transverse and coronal images separately in 4 weeks. The accuracy and diagnostic confidence were evaluated in correlation with intraoperative cholangiography. The accuracy and confidence score (3-point scale) were compared on CE MRCs from transverse versus coronal images.

RESULTS

CE MRCs correctly depicted biliary anatomy in 91.5% and 88.7% with coronal images and in 81.7% and 73.2% with transverse images for readers 1 and 2, respectively. CE MRCs from coronal images tended to show greater accuracy (P = 0.12 and 0.01, for readers 1 and 2) and higher confidence score (P = 0.11 and P = 0.04, for readers 1 and 2) than those from transverse images.

CONCLUSION

Accurate preoperative biliary mapping can be achieved on CE MRC reconstructed from Gd-EOB-DTPA-enhanced MR images. The diagnostic performance was better on CE MRC reconstructed from coronal than those from transverse images.

Improved parenchymal liver enhancement with extended delay on Gd-EOB-DTPA-enhanced MRI in patients with parenchymal liver disease: associated clinical and imaging factors

AIM

To establish the effect of prolonged hepatobiliary phase (HBP) delay time on hepatic enhancement in patients with parenchymal liver disease (PLD).

MATERIALS AND METHODS

Gadoxetate disodium (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) examinations with HBP were obtained after 20- (HBP-20) and 30-minute (HBP-30) delays in patients with PLD. For each patient, the Model for End-Stage Liver Disease (MELD) score, total and direct bilirubin, aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), prothrombin time (PT), and partial thromboplastin time (PTT) were recorded. Signal intensities of the liver, main portal vein, and spleen on pre-contrast, HBP-20, and HBP-30 were documented. Signal intensities were used to calculate liver relative enhancement (LRE), liver-spleen index (LSI), and liver-portal vein index (LPI) for HBP-20 and HBP-30. Improved hepatic enhancement was considered if two or more indices were higher on HBP-30 than HBP-20. A logistic regression model was constructed with improved hepatic enhancement as the outcome.

RESULTS

One hundred and twenty-nine patients underwent 142 MRIs. Mean LRE, LSI, and LPI each increased from HBP-20 to HBP-30 (p = 0.004, p < 0.001, and p < 0.001, respectively). Seventy-two point five percent of cases demonstrated improved hepatic enhancement. The odds ratios for improved hepatic enhancement were 0.85 for MELD score (p = 0.02) and 3.2 for the 3 T scanner (p = 0.02), adjusted for age and sex.

CONCLUSION

Increasing HBP delay to 30 minutes improves hepatic enhancement in patients with PLD, particularly if using a 3 T scanner. This effect is attenuated with higher MELD scores.

Hepatobiliary contrast agents: differential diagnosis of focal hepatic lesions, pitfalls and other indications

The characterization of focal liver lesions is very important. Magnetic resonance imaging is considered the best imaging method for evaluating such lesions, but does not allow for the diagnosis in all cases. The use of hepatobiliary contrast agents increases the diagnostic accuracy of magnetic resonance imaging and reduces the number of non-specific liver lesions. The main indications for the method include: differentiation between focal nodular hyperplasia and adenoma; characterization of hepatocellular carcinomas in cirrhotic patients; detection of small liver metastases; evaluation of biliary anatomy; and characterization of postoperative biliary fistulas. The use of hepatobiliary contrast agents may reduce the need for invasive diagnostic procedures and further investigations with other imaging methods, besides the need for imaging follow-up.

Feasibility of gadoxetate disodium-enhanced MR cholangiography in chronic cholestatic biliary disease

AIM

To investigate the feasibility of gadoxetate disodium-enhanced magnetic resonance (MR) cholangiography in chronic obstructive cholestatic biliary disease in the clinical setting.

MATERIALS AND METHODS

Twenty-three patients with dilated bile duct trees and ten volunteers underwent gadoxetate disodium-enhanced liver MR cholangiography and were enrolled in the present retrospective study. Gadoxetate disodium was given in a standardized manner as a bolus injection at a dose of 0.25 mmol/kg of body weight (0.1 ml/kg). Region of interest-based measurement of mean enhancement of the dilated bile ducts was performed in series before gadoxetate disodium administration and during hepatobiliary phases.

RESULTS

Direct comparison of mean bile duct enhancement during hepatobiliary phases in the clinical imaging window between healthy volunteers [4.7 ± 2.2 arbitrary units (au)] and patients with dilated bile ducts (0.1 ± 0.3 au) revealed significantly lower or absent enhancement in dilated bile ducts (p = 0.001).

CONCLUSION

Standard clinical gadoxetate disodium-enhanced MR cholangiography is not a reliable technique for the evaluation of the biliary trees, because of altered biliary gadoxetate disodium elimination in patients with chronic obstructive biliary diseases.

An increased flip angle in late phase Gd-EOB-DTPA MRI shows improved performance in bile duct visualization compared to T2w-MRCP

OBJECTIVES

To estimate the additional value of an increased flip angle of 35° in late phase Gd-EOB-DTPA-enhanced magnetic resonance cholangiography, as compared to T2w-MRCP.

METHODS

40 adult patients underwent Gd-EOB-DTPA enhanced MRI of the liver including a T2-weighted 3D TSE MRCP (T2w-MRCP) as well as a late phase T1-weighted THRIVE sequences applying a flip angle of 35° (fa35). Two experienced observers evaluated the images regarding the delineation of the different biliary regions using a three-point grading system. A five-point scale was applied to determine the readers' confidence in identifying anatomical variations of the biliary tree. ROI analysis was performed to compare the signal-to-noise (SNR) and contrast-to-noise (CNR) ratios.

RESULTS

The quality for visualizing the biliary tree differed between T2w-MRCP and fa35 (p=<0.001). Late phase EOB-MRC was rated as good for delineating the entire biliary system, whereas T2w-MRCP received an overall poor rating. Especially the depiction of the intrahepatic bile ducts was estimated as problematic in T2w-MRCP. T2w-MRCP and fa35 revealed a discordant assessment of anatomical variations in 12.5% of the cases, comprising a generally higher confidence level for fa35 (4.0 ± 1.1 vs. 2.2 ± 1.2, p=<0.001). SNR proofed to be significantly higher in fa35 (p=<0.001), whereas T2w-MRCP revealed a significantly higher CNR (<0.001).

CONCLUSIONS

Gd-EOB-DTPA enhanced magnetic resonance cholangiography acquired with a flip angle of 35° revealed a better diagnostic performance compared to T2w-MRCP and might be a valuable adjunct in assessing functional bile duct abnormalities.

Combination of increased flip angle, radial k-space trajectory, and free breathing acquisition for improved detection of a biliary variant at living donor liver transplant evaluation using gadoxetic acid-enhanced MRCP

Gadoxetic acid-enhanced magnetic resonance cholangiopancreatography (MRCP) was performed for evaluation of living donor liver transplantation. T2-weighted MRCP and hepatobiliary-phase postcontrast MRCP showed an aberrant right posterior bile duct, although the precise variant was uncertain. Optimized hepatobiliary-phase MRCP was obtained using 3 sequence modifications: increased flip angle to improve contrast between the biliary tree and surrounding tissues; radial k-space sampling to minimize motion artifact; and free-breathing acquisition to improve signal-to-noise ratio and, in turn, spatial resolution (resolution of 1.28 × 1.28 × 1.5 mm). The optimized sequence demonstrated that the right posterior bile duct drained into the cystic duct, consistent with type 3C biliary variant, thus modifying surgical planning.

Gadolinium contrast agent selection and optimal use for body MR imaging

Proper selection of a gadolinium-based contrast agent (GBCA) for body magnetic resonance imaging (MRI) cases requires understanding the indication for the MRI exam, the key features of the different GBCAs, and the effect that the GBCA has on the selected imaging protocol. The different categories of GBCAs require timing optimization on postcontrast sequences and adjusting imaging parameters to obtain the highest T1 contrast. Gadoxetate disodium has many advantages when evaluating liver lesions, although there are caveats and limitations that need to be understood. Gadobenate dimeglumine, a high-relaxivity GBCA, can be used for indications when stronger T1 relaxivity is needed.

Liver-specific agents for contrast-enhanced MRI: role in oncological imaging

Liver-specific magnetic resonance (MR) contrast agents are increasingly used in evaluation of the liver. They are effective in detection and morphological characterization of lesions, and can be useful for evaluation of biliary tree anatomy and liver function. The typical appearances and imaging pitfalls of various tumours at MR imaging performed with these agents can be understood by the interplay of pharmacokinetics of these contrast agents and transporter expression of the tumour. This review focuses on the applications of these agents in oncological imaging.

Diagnosis of biliary stone disease: T1-weighted magnetic resonance cholangiography with Gd-EOB-DTPA versus T2-weighted magnetic resonance cholangiography

OBJECTIVE

We aimed to compare diagnostic performance of gadoxetic-acid-enhanced-T1-weighted-MR cholangiography (MRC) with that of conventional T2-weighted-MRC in diagnosing biliary stone disease.

MATERIALS AND METHODS

Ninety patients who underwent MRC for evaluation of biliary disease were included. Presence of stones in extrahepatic duct, gallbladder and intrahepatic duct, and presence of acute cholecystitis were evaluated. Sensitivity, specificity, and accuracy of biliary stone disease diagnosis in each biliary duct location according to each image sets were measured.

RESULTS

There was no significant difference in diagnostic performance between two sets of MRC in diagnosing biliary stone disease.

CONCLUSIONS

Diagnostic performance of T1-MRC with gadoxetic-acid in diagnosing biliary stone disease is comparable to that of T2-MRC.