Quantitative evaluation of liver function using gadoxetic acid-enhanced MRI

Before liver resection, a reliable and accurate assessment of the liver function is essential to ensure a safe surgery and avoid unfavorable complications such as post-hepatectomy liver failure (PHLF). Gadoxetic acid enhanced magnetic resonance imaging (MRI) is a routinely used imaging modality for tumor detection and characterization. In recent years, research has shown that gadoxetic acid enhanced MRI can be a reliable and promising tool in evaluation of liver function, supplying liver function information at both global and regional levels. Accurate assessment of liver function also makes it possible to predict PHLF preoperatively. In Study I, the three categories of parameters derived from gadoxetic acid enhanced MRI (signal intensity-based, T1 relaxometry-based and dynamic hepatic contrast enhanced MRI-based) were evaluated for the consistency between them and the correlation with Child-Pugh score and Model for End-stage Liver Disease score. It was shown that the simple signal intensity based parameters had a similar capacity as the complex ones in evaluation of liver function. Among them, liver-to-muscle ratio (LMR) showed a good performance and could be selected for clinical usage. Study II was a prospective pilot study, which compared the efficacy of gadoxetic acid enhanced MRI with two gold standard tests (indocyanine green retention test at 15 min (ICG-R15) and hepatobiliary scintigraphy) in evaluation of liver function during the perioperative period. It was shown that 1) the consistency between the three modalities was good, 2) LMR and hepatic uptake index were reliable for liver function assessment and predictive for liver growth after liver resection, and 3) liver function and volume changed in parallel within one month after liver resection. The systematic review of Study III was performed to summarize currently available evidence for the value of preoperative gadoxetic acid enhanced MRI in prediction of PHLF. It included 15 original studies and the results demonstrated that gadoxetic acid enhanced MRI had a high predictive value in estimation of PHLF risk, with an area under the curve ranging from 0.67 to 0.96. In Study IV, a clinical model using radiomics and machine learning approaches based on hepatobiliary phase of gadoxetic acid enhanced MRI for PHLF prediction in patients with hepatocellular carcinoma was developed and validated. The prediction model yielded an AUC of 0.84 and 0.82 in the training and test cohorts respectively, showing a promising ability to stratify patients into different risk levels for PHLF. In summary, preoperative gadoxetic acid enhanced MRI seems to be an effective and reliable imaging biomarker for quantitative evaluation of liver function and for prediction of post-hepatectomy liver failure

Contrast-Enhanced Magnetic Resonance Cholangiography: Practical Tips and Clinical Indications for Biliary Disease Management

Since its introduction, MRCP has been improved over the years due to the introduction of several technical advances and innovations. It consists of a noninvasive method for biliary tree representation, based on heavily T2-weighted images. Conventionally, its protocol includes two-dimensional single-shot fast spin-echo images, acquired with thin sections or with multiple thick slabs. In recent years, three-dimensional T2-weighted fast-recovery fast spin-echo images have been added to the conventional protocol, increasing the possibility of biliary anatomy demonstration and leading to a significant benefit over conventional 2D imaging. A significant innovation has been reached with the introduction of hepatobiliary contrasts, represented by gadoxetic acid and gadobenate dimeglumine: they are excreted into the bile canaliculi, allowing the opacification of the biliary tree. Recently, 3D interpolated T1-weighted spoiled gradient echo images have been proposed for the evaluation of the biliary tree, obtaining images after hepatobiliary contrast agent administration. Thus, the acquisition of these excretory phases improves the diagnostic capability of conventional MRCP—based on T2 acquisitions. In this paper, technical features of contrast-enhanced magnetic resonance cholangiography are briefly discussed; main diagnostic tips of hepatobiliary phase are showed, emphasizing the benefit of enhanced cholangiography in comparison with conventional MRCP

Post hepatectomy liver failure (PHLF) – Recent advances in prevention and clinical management

Under embargo until: 2021-09-10Background Posthepatectomy liver failure (PHLF) is a relatively rare but feared complication following liver surgery, and associated with high morbidity, mortality and cost implications. Significant advances have been made in detailed preoperative assessment, particularly of the liver function in an attempt to predict and mitigate this complication. Methods A detailed search of PubMed and Medline was performed using keywords “liver failure”, “liver insufficiency”, “liver resection”, “postoperative”, and “post-hepatectomy”. Only full texts published in English were considered. Particular emphasis was placed on literature published after 2015. A formal systematic review was not found feasible hence a pragmatic review was performed. Results The reported incidence of PHLF varies widely in reported literature due to a historical absence of a universal definition. Incorporation of the now accepted definition and grading of PHLF would suggest the incidence to be between 8 and 12%. Major risk factors include background liver disease, extent of resection and intraoperative course. The vast majority of mortality associated with PHLF is related to sepsis, organ failure and cerebral events. Despite multiple attempts, there has been little progress in the definitive and specific management of liver failure. This review article discusses recent advances made in detailed preoperative evaluation of liver function and evidence-based targeted approach to managing PHLF. Conclusion PHLF remains a major cause of mortality following liver resection. In absence of a specific remedy, the best approach is mitigating the risk of it happening by detailed assessment of liver function, patient selection and general care of a critically ill patient.acceptedVersio

Consensus report from the 6th International forum for liver MRI using gadoxetic acid

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/108276/1/jmri24419.pd

BestFLR. Randomized controlled clinical trial comparing preoperative portal embolization with polyvinyl alcohol particles (PVA) and coils versus N-butyl cyanoacrylate (NBCA)

Liver surgery offers the most effective long-term oncological outcome for the treatment of metastatic liver disease (e.g. colorectal liver metastasis) and primary liver cancer (e.g. Hepatocarcinoma, Cholangiocarcinoma). Furthermore, advancements in surgical techniques combined with better postoperative care have decreased hepatectomy mortality rates to around 4 to 3% in high-volume centres. Unfortunately, approximately less than 25% of liver cancer patients are suited for surgical treatment, being the small size of the non-tumoral part of the liver - the future liver remnant (FLR) – the main limiting factor. Techniques to increase the FLR, known as liver regenerative strategies such as portal vein embolization (PVE), will increase the FLR volume and consequently allow otherwise non-operable patients to undergo this potentially curative treatment. PVE was introduced decades ago by Japanese groups and is currently accepted as the standard of care for liver regenerative techniques due to its benefit in preventing postoperative liver failure and improving overall survival. The rationale of PVE is related to the occlusion of the portal vein branches that irrigate the tumoral liver and redirecting all portal flow to the contralateral side, the FLR. This process succumbs in the increase of the FLR after two to six weeks. Technically PVE is commonly accomplished by a liver percutaneous approach. First an ultrasound guided transhepatic access to the portal vein is obtained, followed by a vascular sheath being placed in the main portal vein. Through the catheterization of the portal vein using angiographic catheters and microcatheters the target portal vein branches are embolized. Nearly all types of embolic materials have been tested and reported for PVE with no real consensus on which one would induce the greatest degree of liver regeneration. No randomized controlled trial had been performed to directly compare different embolic materials to perform PVE. The need for a well-designed, prospective, and controlled study to address this gap in the oncological literature seemed necessary and defiant. N-Butyl Cyanoacrylate (NBCA), a liquid embolic material, first used for PVE by French groups, has robust liver regenerative results reported in animal and retrospective human studies. Besides that, this liquid embolic has other potential advantages such as fast administration, low cost, and wide availability. At our own clinical practice there was an increasing perception of the distinct potential role of NBCA-Lipiodol for PVE, as to push us to look at our own results. This resulted in our first publication which reported a cohort of 50 consecutive patients submitted to PVE with NBCA-lipiodol published in the journal Cancer Imaging. The FLR increase (e.g., absolute liver hypertrophy) obtained at this retrospective analysis was 52% at an average 4 weeks after PVE, which was similar to previous published results for PVE when adopting this liquid embolic agent. Beside NBCA-lipiodol, the other most frequent embolic material reported for PVE is a combination of polyvinyl alcohol (PVA) particles plus coils. For this PVE approach PVA particles are injected first for distal embolization in the portal vein branches followed by the deposition of proximal coils for definitive obstruction. This approach has been the standard procedure for PVE in Curry Cabral hospital´s interventional radiology unit for more than a decade. Although an established technique, PVE with PVA particles plus coils seemed to promote less liver regeneration and associated with more contrast usage, more fluoroscopy time and at a higher cost than PVE with NBCA plus Lipiodo. To change not only our practice but also to make scientific work useful to other centers our group decided to embrace an original, prospective project comparing NBCA-lipiodol and PVA particles plus coils for PVE before major hepatectomies, the BestFLR trial. It also seemed reasonable and necessary to review and publish Curry Cabral interventional radiology unit experience with PVE using PVA particles plus coils. This retrospective analysis of data was published in the Journal of Oncology. Once again, results from our own retrospective cohort were similar to previously reported FLR absolute hypertrophy results for PVE with PVA particles plus coils, ranging from 25 to 40%. We also noticed the necessity of performing an extensive review about PVE, more specifically the embolic materials reported for this procedure, their technical specifications, efficacy, complications, and clinical outcomes. This work was gathered as a detailed literature review of related publications up to August 2019 focusing on the results of each embolic agent and mixtures used for PVE, their handling, safety profiles, and liver hypertrophy regenerative results, also exemplifying with clinical cases from our own experience. This review article was published in the journal Radiology Research and Practice. As mentioned, to build up higher levels of evidence a randomized controlled trial (RCT) was necessary to address the difference between the two most commonly used embolic materials for PVE: NBCA-Lipiodol versus PVA particles plus coils. This RCT was carried out in Curry Cabral hospital and published in Radiology in April 2021. This trial showed that PVE with NBCA-Lipiodol produced greater absolute liver hypertrophy compared to PVA particles plus coils (46% versus 30% at 14 days, p < .001 and 57% versus 37% at 28 days, p < .001, respectively). Also, more participants in the NBCA plus Lipiodol group presented sufficient liver hypertrophy for surgery 2 weeks after PVE compared to the PVA particles plus coils group (87% vs 53%, respectively; p = .008). This latter finding meant that patients in the NBCA Lipiodol group were ready for the planned hepatectomy earlier, which might reduce tumor progression while patients are waiting for the liver to regenerate. Concurrently, in the beginning of the year of 2021, with the publication of the results from the BestFLR, two systematic reviews with meta-analysis regarding liver regeneration predictive factors for PVE were also reported. Ali et al investigated PVE accomplished with different embolic materials for effectiveness in inducing future FLR hypertrophy and other outcomes. This review included 2896 patients from 51 different studies. Liver regeneration results and growth success rate were statistically superior for NBCA-Lipiodol when compared to PVA particles plus coils. Also, PVE with NBCA-Lipiodol promoted shorter procedures and reduced fluoroscopy time (p < .001), lower radiation exposure (p = .01), and lower material costs (p < .001) than PVA plus coils. The second systematic review with meta-analysis identified two predictive factors for accomplishing higher FLR hypertrophy results, and, once again, NBCA-Lipiodol was found to be superior to PVA plus coils in promoting liver regeneration (significant difference of degree of hypertrophy - DH in favor of NBCA-lipiodol). Our own group was invited to write a commentary about this relevant publication. Pointing out to future perspectives, new regenerative techniques need to be addressed. With PVE, although highly effective, up to 20% of patients will not undergo the planned hepatectomy, due mainly to liver tumor progression during the regeneration waiting period after PVE or insufficient FLR hypertrophy. To accelerate liver regeneration and overcome insufficient FLR hypertrophy after PVE different strategies, such as biembolization, liver venous deprivation (LVD) and associating liver partition and portal vein ligation (ALPPS) have been reported. Biembolization refers to concomitantly performing PVE and proximal hepatic vein embolization. LVD, reported as proximal hepatic vein embolization, as in biembolization, and distal hepatic vein embolization with concomitantly PVE, has encouraging liver hypertrophy results, superior to PVE. ALPPS, which stands for associating liver partition with portal vein ligation in staged hepatectomy, promotes robust and rapid liver regeneration but is associated with high morbidity and mortality. Our own group commented upon two recent publications regarding these future perspectives

Surgical resection of localized hepatocellular carcinoma: patient selection and special consideration

published_or_final_versio

Treatment options for PNET liver metastases. a systematic review

Pancreatic neuroendocrine tumors (PNETs) are rare pancreatic neoplasms. About 40-80% of patients with PNET are metastatic at presentation, usually involving the liver (40-93%). Liver metastasis represents the most significant prognostic factor. The aim of this study is to present an up-to-date review of treatment options for patients with liver metastases from PNETs