Imaging Approach to Hepatocellular Carcinoma, Cholangiocarcinoma, and Metastatic Colorectal Cancer

Molecular targeted and systemic therapy for intrahepatic cholangiocarcinoma: a multi-disciplinary approach

Most patients with intrahepatic cholangiocarcinoma (ICC) are diagnosed with advanced disease. For individuals with resectable tumors, R0 resection with lymphadenectomy is the best potentially curative-intent treatment. After resection, adjuvant therapy with capecitabine is the current standard of care. For patients with unresectable or distant metastatic disease, doublet chemotherapy with gemcitabine and cisplatin is the most utilized first-line regimen, but recent studies using triplet regimens and even the addition of immunotherapy have begun to shift the paradigm of systemic therapy. Molecular therapies have recently received US FDA approval for second-line treatment for patients harboring actionable genomic alterations. This review focuses on the multidisciplinary approach to the treatment of ICC with an emphasis on molecular targeted and systemic therapy.

Surgical Treatment of Intrahepatic Cholangiocarcinoma: Current and Emerging Principles

Intrahepatic cholangiocarcinoma (ICC) is a rare, aggressive cancer of the biliary tract. It often presents with locally advanced or metastatic disease, but for patients with early-stage disease, surgical resection with negative margins and portahepatis lymphadenectomy is the standard of care. Recent advancements in ICC include refinement of staging, improvement in liver-directed therapies, clarification of the role of adjuvant therapy based on new randomized controlled trials, and advances in minimally invasive liver surgery. In addition, improvements in neoadjuvant strategies and surgical techniques have enabled expanded surgical indications and reduced surgical morbidity and mortality. However, recurrence rates remain high and more effective systemic therapies are still necessary to improve recurrence-free and overall survival. In this review, we focus on current and emerging surgical principals for the management of ICC including preoperative evaluation, current indications for surgery, strategies for future liver remnant augmentation, technical principles, and the role of neoadjuvant and adjuvant therapies.

Cholangiocarcinoma Evaluation via Imaging and Artificial Intelligence

BACKGROUND

Cholangiocarcinoma (CCA) is a relatively rare malignant biliary system tumor, and yet it represents the second most common primary hepatic neoplasm, following hepatocellular carcinoma. Regardless of the type, location, or etiology, the survival prognosis of these tumors remains poor. The only method of cure for CCA is complete surgical resection, but part of patients with complete resection are still subject to local recurrence or distant metastasis.

SUMMARY

Over the last several decades, our understanding of the molecular biology of CCA has increased tremendously, diagnostic and evaluative techniques have evolved, and novel therapeutic approaches have been established. Key Messages: This review provides an overview of preoperative imaging evaluations of CCA. Furthermore, relevant information about artificial intelligence (AI) in medical imaging is discussed, as well as the development of AI in CCA treatment.

The rate of false-positive diagnosis of colorectal liver metastases in patients undergoing resection with the development of a novel, externally validated risk score

BACKGROUND

Diagnostic error in patients undergoing resection of colorectal liver metastases (CRLM) is unusual but exposes patients to unnecessary risks associated with treatment. The primary aim of this study was to determine the rate of and risk factors for a false-positive diagnosis of colorectal liver metastases in patients undergoing hepatic resection. The secondary aim was to develop and validate a risk score to predict a false-positive diagnosis.

METHODS

Patients were identified from prospectively maintained databases. Patients who underwent a first liver resection for presumed colorectal liver metastases were divided into 2 groups: CRLM_POS (colorectal liver metastases present on histology or appearance of complete pathologic response to preoperative chemotherapy) and CRLM_NEG (all others). Univariable analysis and multivariable binary logistic regression were used to identify risk factors for CRLM_NEG. Risk scores were developed for CRLM_NEG both with and without the use of preoperative carcinoembryonic antigen and were validated on an external cohort.

RESULTS

3.1% of patients in both test and validation cohorts were CRLM_NEG (39/1,252 and 59/1,900, respectively). CRLM_NEG patients had fewer (P = .006) and smaller lesions (P < .001) with lower serum levels of carcinoembryonic antigen (P < .001), T (P = .031) and N (P < .001) and a lower Dukes' stage of the primary (P < .001). The risk score performed well (area under the receiver operating characteristic curve 0.869; standard error = 0.030; P < .001) with reasonable performance on validation (area under receiver operating characteristic curve 0.743; standard error = 0.058; P < .001]).

CONCLUSION

A false-positive diagnosis of colorectal liver metastases affected the same proportion of patients in 2 unrelated cohorts. This study identified risk factors for false-positive diagnosis with development of a novel risk score supported by external validation.

Multimodality imaging of intrahepatic cholangiocarcinoma

Intrahepatic cholangiocarcinomas account for approximately 20% of cases of cholangiocarcinomas. Three growth patterns or morphologic subtypes exist, including mass-forming, periductal-infiltrating, and intraductal-growth subtypes. Knowledge of these morphologic subtypes and their radiologic appearance aids in timely diagnosis, a key to optimizing patient outcomes. The morphologic variability of intrahepatic cholangiocarcinomas has a direct impact on the diagnostic sensitivity and specificity of various diagnostic imaging modalities, including ultrasound (US), computed tomography (CT), magnetic resonance imaging (MRI)/magnetic resonance cholangiopancreatography (MRCP), and positron emission tomography (PET). The following review emphasizes optimal imaging technique for each of these modalities and reviews the imaging appearance of each morphologic subtype of intrahepatic cholangiocarcinoma.

Efficacy and safety of endoscopic ultrasonography-guided interventional treatment for refractory malignant left-sided liver tumors: a case series of 26 patients

This study aimed to compare the efficacy and safety of EUS-guided ethanol injection and ¹²⁵I seed brachytherapy for malignant left-sided liver tumors which were difficult for trans-abdominal intervention. The study protocol was registered at Clinicaltrials.gov (NCT02816944). Twenty-six patients were consecutively and prospectively hospitalized for EUS-guided interventional treatment of refractory malignant left-sided liver tumors between June 2014 and June 2016. Liver masses were detected using EUS in 25 of 26 (96.2%) patients. EUS-guided interventional treatment was completed uneventfully in 23 of 26 (88.5%) patients using anhydrous ethanol injection (n = 10) or iodine-125 seed implantation (n = 13). Six months later, complete response was achieved in 15 of 23 (65.2%) patients and partial response in 8 of 23 (34.8%) patients. Patients with tumor residual have second-look EUS-guided interventional treatment (n = 5), radiotherapy (n = 2) or surgical resection (n = 1). Complete response was achieved after repeated interventional treatment in 3 of 5 patients who underwent second EUS-guided intervention; 2 patients required additional surgical resection but one succeed. No significant complications occurred. Therefore EUS-guided ¹²⁵I seed brachytherapy is an effective and safe treatment modality for radical operation or promising palliative control of malignant left-sided liver tumors refractory to trans-abdominal intervention.

Magnetic Resonance Imaging of Liver Metastasis

Liver magnetic resonance imaging (MRI) is becoming the gold standard in liver metastasis detection and treatment response assessment. The most sensitive magnetic resonance sequences are diffusion-weighted images and hepatobiliary phase images after Gd-EOB-DTPA. Peripheral ring enhancement, diffusion restriction, and hypointensity on hepatobiliary phase images are hallmarks of liver metastases. In patients with normal ultrasonography, computed tomography (CT), and positron emission tomography (PET)-CT findings and high clinical suspicion of metastasis, MRI should be performed for diagnosis of unseen metastasis. In melanoma, colon cancer, and neuroendocrine tumor metastases, MRI allows confident diagnosis of treatment-related changes in liver and enables differential diagnosis from primary liver tumors. Focal nodular hyperplasia-like nodules in patients who received platinum-based chemotherapy, hypersteatosis, and focal fat can mimic metastasis. In cancer patients with fatty liver, MRI should be preferred to CT. Although the first-line imaging for metastases is CT, MRI can be used as a problem-solving method. MRI may be used as the first-line method in patients who would undergo curative surgery or metastatectomy. Current limitation of MRI is low sensitivity for metastasis smaller than 3mm. MRI fingerprinting, glucoCEST MRI, and PET-MRI may allow simpler and more sensitive diagnosis of liver metastasis.

Quantification of liver fat: A comprehensive review

Fat accumulation in the liver causes metabolic diseases such as obesity, hypertension, diabetes or dyslipidemia by affecting insulin resistance, and increasing the risk of cardiac complications and cardiovascular disease mortality. Fatty liver diseases are often reversible in their early stage; therefore, there is a recognized need to detect their presence and to assess its severity to recognize fat-related functional abnormalities in the liver. This is crucial in evaluating living liver donors prior to transplantation because fat content in the liver can change liver regeneration in the recipient and donor. There are several methods to diagnose fatty liver, measure the amount of fat, and to classify and stage liver diseases (e.g. hepatic steatosis, steatohepatitis, fibrosis and cirrhosis): biopsy (the gold-standard procedure), clinical (medical physics based) and image analysis (semi or fully automated approaches). Liver biopsy has many drawbacks: it is invasive, inappropriate for monitoring (i.e., repeated evaluation), and assessment of steatosis is somewhat subjective. Qualitative biomarkers are mostly insufficient for accurate detection since fat has to be quantified by a varying threshold to measure disease severity. Therefore, a quantitative biomarker is required for detection of steatosis, accurate measurement of severity of diseases, clinical decision-making, prognosis and longitudinal monitoring of therapy. This study presents a comprehensive review of both clinical and automated image analysis based approaches to quantify liver fat and evaluate fatty liver diseases from different medical imaging modalities.