Keywords: Hepatobiliary, Biliary

Motivation: Explore surveillance of Intraductal Papillary Mucinous Neoplasms (IPMN) at 0.55T, as an alternative to high field strength systems.

Goal(s): To assess the image quality at 0.55T and its impact on radiologists' confidence in evaluating IPMN versus 1.5T/3T

Approach: Images from 39 patients with IPMN who underwent 0.55T and 1.5/3T MRI were rated by 7 blinded radiologists for image quality and diagnostic certainty. Pearson correlation analysis performed

Results: A strong positive correlation existed between image quality and rater’s confidence. Negligible differences in confidence observed between 0.55T and 1.5T/3T for images with quality scores≥5. 

Impact: 0.55T can be used for IPMN surveillance without compromising diagnostic effectiveness

Keywords: Liver, Low-Field MRI, Spiral, Dixon, abdomen

Motivation: Breath-held abdominal fat-suppressed imaging is challenging at mid- and low-field strengths (<1.5T). Fat saturation often fails due to the short T1 of lipid; and Cartesian Dixon imaging provides poor spatial resolution due to the need for long ∆TE, due to the smaller ∆f between water and lipid.

Goal(s): Breath-held fat-suppressed high-resolution volumetric abdominal imaging with T1 contrast.

Approach: Stack-of-Spirals Dixon imaging, with estimation and compensation for phase due to concomitant fields

Results: We demonstrate that spiral Dixon imaging at 0.55T makes excellent use of the required ∆TE, improving SNR efficiency and spatial resolution (1.7x1.7x5.0mm³) compared Cartesian Dixon (3.5x3.5x5.0mm³), within a 17-second breath-hold.

Impact: We demonstrate that spiral Dixon single breath-hold volumetric imaging is an attractive alternative to existing Cartesian-based methods for volumetric single breath-hold fat-suppressed imaging at 0.55T, as it simultaneously provides high-resolution and excellent fat-suppression.

Keywords: Liver, Motion Correction, T1-weighted imaging, abdomen

Motivation: Respiratory motion creates blurring artifacts in abdominal MRIs for the liver and kidneys, preventing identification of tumors and blood vessels and optimal treatment administration.

Goal(s): We aimed to increase respiratory data density, decrease motion, and maximize data utilization in each motion-state.

Approach: We proposed a motion-correction method to remove respiratory irregularities and sort data into overlapping motion-states. We compared signal density and conspicuity of artifacts and organ structures for images reconstructed from the proposed and traditional methods.

Results: Compared with the traditional method, the proposed method consistently increased data density by over 50% and produced more motion-robust images for inhale-states of irregular-breathing patients.

Impact: Our proposed motion-correction method for T1-weighted abdominal MRIs increases respiratory data density to improve visibility of liver and kidney vessels and boundaries, supporting treatment for irregular-breathing and pediatric patients. This method may enhance dynamic contrast-enhanced MRI with temporal resolution constraints.

Keywords: Liver, Liver

Motivation: Many patients cannot hold their breath as required on standard protocols for abdominal imaging

Goal(s): We develop a new new free-breathing Look-Locker T1-mapping method with whole liver coverage.

Approach: The new free-breathing Look-Locker T1-mapping method employs a pilot tone signal for detecting the respiratory state. This signal is used to reconstruct motion-corrected T1-weighted images, which are used to calculate T1-maps.

Results: Robust T1-maps are obtained covering the whole liver obtained from 6 min free-breathing scan.

Impact: A new free-breathing Look-Locker T1-mapping method with whole liver coverage has been developed for patients who are not able to hold their breath as required in standard protocols.

Keywords: Liver, Fat

Motivation: Liver T1 estimation depends on the echo time when fat signal is not eliminated, implying that traditional T1 mapping techniques without considering the presence of fat may lack accuracy and reliability.

Goal(s): This study investigated the correlation between liver T1 and fat fraction in 3D free-breathing Fat/Water-Separated T1 mapping and the repeatability of water-specific T1 measurement.

Approach: Fifty subjects were recruited and four of them were scanned multiple times to assess the repeatability.

Results: Difference between the first echo T1 and water-specific T1 shows strong correlation with the fat fraction, while water-specific T1 shows little correlation. Water-specific T1 mapping is repeatable.

Impact: This study aims to investigate the influence of fat on liver T1 in 3D free-breathing T1 mapping. This can help understand how the fat affects liver T1 mapping and facilitate the development new techniques for estimating water-specific liver T1.

Keywords: Liver, Elastography, HCV, loss modulus, damping ratio

Motivation: While DAAs have significantly improved the treatment of HCV patients, some individuals still face relapse or progression. There is currently a deficiency in non-invasive and simple methods for effectively monitoring the longitudinal treatment effects.

Goal(s): To develop a reliable biomarker for detecting inflammatory response to DAA treatment in the early stages of HCV infection.

Approach: Longitudinal monitoring of changes in early-stage HCV patients after DAA treatment using multiparametric MRE.

Results: Multi-parameter MRE can detect HCV at the early stage and can monitor both short-term inflammatory response and long-term treatment effect of the liver in HCV patients after DAA treatment.

Impact: Developed a non-invasive biomarker for monitoring the efficacy of DAA treatment in early-stage HCV patients.

Keywords: Liver, Liver

Motivation: Gadolinium dose reduction while maintaining MRI diagnostic efficacy is crucial.

Goal(s): Compare gadopiclenol (0.05 mmol/kg) and gadobutrol (0.1 mmol/kg) in liver MRI.

Approach: Post-hoc analysis on patients with liver lesions from the PROMISE phase III study (N=66).
Lesion visualization was qualitatively (border delineation, internal morphology, contrast enhancement) and quantitatively (enhancement percentage, lesion-to-background ratio) evaluated by three blinded readers. Three additional readers assessed diagnostic preference. 

Results: Gadopiclenol was non-inferior to gadobutrol for all qualitative visualization parameters and all readers.
Quantitative parameters did not differ between the two GBCAs.
Readers had in most cases no preference between images with the two GBCAs.

Impact: The reduction in the injected gadolinium dose achieved with gadopiclenol may be particularly important in patients undergoing multiple contrast-enhanced MRI examinations. This will also reduce the amount of gadolinium released into wastewater systems, limiting any potential ecological impact.

Keywords: Liver, Body, 4D Flow MRI; portal hypertension; Esophagogastric Varices

Motivation: The pursuit of less invasive diagnostic methods to gauge portal hypertension and the associated risk of variceal bleeding in cirrhosis patients.

Goal(s): To determine the effectiveness of hemodynamic parameters derived from 4D flow MRI for the non-invasive assessment of portal hypertension and to stratify the risk of variceal bleeding in patients with cirrhosis.

Approach: Utilizing hemodynamic parameters from 4D flow MRI to profile portal circulation.

Results: Results showed significant differences in FFC and maximum splenic blood flow between low-risk and high-risk patients. Moreover, the combination of FFC and maximum splenic blood yielded high diagnostic accuracy.

Impact: Demonstrating the utility of 4D flow MRI in evaluating portal hypertension and variceal bleeding risk.

Keywords: Cancer, Perfusion, Dynamic Contrast Enhanced MRI; Liver; Validation; Deep Learning; Phantoms

Motivation: To validate deep learning based Quantitative Transport Mapping (QTMnet) on a perfused tissue phantom.

Goal(s): Evaluate the accuracy of QTMnet derived flow and compare to traditional tracer-kinetic flow estimation.

Approach: We developed a workflow to prepare porcine liver as a perfusion phantom¹. We perfused n=8 porcine livers with a controllable pump and acquired DCE-MRI. We then estimated the liver flow with QTMnet and traditional tracer-kinetics.

Results: QTMnet accurately estimates our phantom flow (mean error: -2.82%, mean absolute error: 10.0%). Furthermore, QTMnet flow estimation was more accurate than traditional tracer-kinetics flow estimation (mean error: -43.29%, mean absolute error: 58.9%, P<0.00001).

Impact: Our liver phantom workflow allows demonstrating accuracy of estimated flows. Superior accuracy was observed using QTMnet compared to traditional tracer-kinetics. Accurate estimation of liver blood flow allows better diagnosis and follow-up in the imaging of primary and secondary liver cancer.

Keywords: Preclinical Image Analysis, Quantitative Imaging, Biliary

Motivation: To evaluate the 5 T MRI’s effectiveness for MRCP imaging.

Goal(s): To demonstrate 5 T imaging's comparability in visualization, SNR, and image quality to 3 T.

Approach: MRCP was performed on subjects using both 3 T and 5 T MRI, assessing the bile duct tree visualization and SNR, with radiologists evaluating image quality and artifacts.

Results: 5 T revealed superior bile duct tree visualization, with comparable SNR, image quality, and artifact management to 3 T.

Impact: The study highlights 5 T MRI's potential in MRCP, suggesting improved biliary visualization which could lead to better clinical outcomes and guide further technological advancements in non-invasive diagnostics.