Comparison of gadoxetic acid-enhanced dynamic MR imaging and contrast-enhanced computed tomography for preoperative evaluation of colorectal liver metastases

Colon cancer: the 2023 Korean clinical practice guidelines for diagnosis and treatment

Colorectal cancer is the third most common cancer in Korea and the third leading cause of death from cancer. Treatment outcomes for colon cancer are steadily improving due to national health screening programs with advances in diagnostic methods, surgical techniques, and therapeutic agents.. The Korea Colon Cancer Multidisciplinary (KCCM) Committee intends to provide professionals who treat colon cancer with the most up-to-date, evidence-based practice guidelines to improve outcomes and help them make decisions that reflect their patients' values and preferences. These guidelines have been established by consensus reached by the KCCM Guideline Committee based on a systematic literature review and evidence synthesis and by considering the national health insurance system in real clinical practice settings. Each recommendation is presented with a recommendation strength and level of evidence based on the consensus of the committee.

Exploring the Outcome of Disappearance or Small Remnants of Colorectal Liver Metastases during First-Line Chemotherapy on Hepatobiliary Contrast-Enhanced and Diffusion-Weighted MR Imaging

We aimed to evaluate the outcome of the disappearance or small remnants of colorectal liver metastases during first-line chemotherapy assessed by hepatobiliary contrast-enhanced and diffusion-weighted MR imaging (DW-MRI). Consecutive patients with at least one disappearing liver metastasis (DLM) or small residual liver metastases (≤10 mm) assessed by hepatobiliary contrast-enhanced and DW-MRI during first-line chemotherapy were included. Liver lesions were categorized into three groups: DLM; residual tiny liver metastases (RTLM) when ≤5 mm; small residual liver metastases (SRLM) when >5mm and ≤10 mm. The outcome of resected liver metastases was assessed in terms of pathological response, whereas lesions left in situ were evaluated in terms of local relapse or progression. Fifty-two outpatients with 265 liver lesions were radiologically reviewed; 185 metastases fulfilled the inclusion criteria: 40 DLM, 82 RTLM and 60 SRLM. We observed a pCR rate of 75% (3/4) in resected DLM and 33% (12/36) of local relapse for DLM left in situ. We observed a risk of relapse of 29% and 57% for RTLM and SRLM left in situ, respectively, and a pCR rate of about 40% overall for resected lesions. DLM assessed via hepatobiliary contrast-enhanced and DW-MRI very probably indicates a complete response. The surgical removal of small remnants of liver metastases should always be advocated whenever technically possible.

Evaluation of health economic impact of initial diagnostic modality selection for colorectal cancer liver metastases in suspected patients in China, Japan and the USA

AIMS

To compare cost offsets and contributing factors (false-negative rates and confirmatory imaging requirements, potentially leading to longer waiting times for diagnosis) as well as long-term cost effectiveness associated with the diagnostic and treatment pathways for colorectal cancer liver metastases (CRCLM) in the US, Japan, and China according to initial imaging modality used. Gadoxetate disodium (ethoxylbenzyl-diethylenetriaminepentaacetic acid)-enhanced magnetic resonance imaging (EOB-MRI) was compared to multidetector computed tomography (MDCT), extracellular contrast media enhanced-MRI (ECCM-MRI) (the US and China only) and contrast-enhanced ultrasound (CEUS).

MATERIALS AND METHODS

Decision tree models were developed to simulate the clinical pathway, from first diagnostic test to initial treatment decision, based on local clinical guidelines and validated by experts. Input data were derived from the literature (up to 31st December 2020) as well as from interviews with local experts. A Markov model extension was built to evaluate the number of false-negative patients and associated costs, over a lifetime horizon.

RESULTS

The decision-tree models showed that, increasing proportionate use of initial EOB-MRI resulted in a cost-offset per patient (excluding false-negative patients) in all countries (USD 201 for the US, JPY 6,284 for Japan and CNY 446 for China) driven by reductions in follow-on diagnostic procedures and unnecessary treatment. The use of EOB-MRI was also associated with a shorter average waiting time to a final diagnosis and treatment decision compared to MDCT, ECCM-MRI and CEUS. The Markov model showed that with an increase in EOB-MRI use, there are fewer false-negative diagnoses over a lifetime horizon. In all three countries, the incremental cost-effectivenes ratio (ICER) was below standard willingness-to-pay thresholds.

CONCLUSION

The findings of these models demonstrate that use of EOB-MRI early in the diagnostic pathway for CRCLM results in short-term cost savings, as well as being cost effective in the long term.

Minimum standards of pelvic exenterative practice: PelvEx Collaborative guideline

This document outlines the important aspects of caring for patients who have been diagnosed with advanced pelvic cancer. It is primarily aimed at those who are establishing a service that adequately caters to this patient group. The relevant literature has been summarized and an attempt made to simplify the approach to management of these complex cases.

Whole-liver enhanced CT radiomics analysis to predict metachronous liver metastases after rectal cancer surgery

Background

To develop a radiomics model based on pretreatment whole-liver portal venous phase (PVP) contrast-enhanced CT (CE-CT) images for predicting metachronous liver metastases (MLM) within 24 months after rectal cancer (RC) surgery.

Methods

This study retrospectively analyzed 112 RC patients without preoperative liver metastases who underwent rectal surgery between January 2015 and December 2017 at our institution. Volume of interest (VOI) segmentation of the whole-liver was performed on the PVP CE-CT images. All 1316 radiomics features were extracted automatically. The maximum-relevance and minimum-redundancy and least absolute shrinkage and selection operator methods were used for features selection and radiomics signature constructing. Three models based on radiomics features (radiomics model), clinical features (clinical model), and radiomics combined with clinical features (combined model) were built by multivariable logistic regression analysis. Receiver operating characteristic (ROC) curves were used to assess the diagnostic performance of models, and calibration curve and the decision curve analysis were performed to evaluate the clinical application value.

Results

In total, 52 patients in the MLM group and 60 patients in the non-MLM group were enrolled in this study. The radscore was built using 16 selected features and the corresponding coefficients. Both the radiomics model and the combined model showed higher diagnostic performance than clinical model (AUCs of training set: radiomics model 0.84 (95% CI, 0.76–0.93), clinical model 0.65 (95% CI, 0.55–0.75), combined model 0.85 (95% CI, 0.77–0.94); AUCs of validation set: radiomics model 0.84 (95% CI, 0.70–0.98), clinical model 0.58 (95% CI, 0.40–0.76), combined model 0.85 (95% CI, 0.71–0.99)). The calibration curves showed great consistency between the predicted value and actual event probability. The DCA showed that both the radiomics and combined models could add a net benefit on a large scale.

Conclusions

The radiomics model based on preoperative whole-liver PVP CE-CT could predict MLM within 24 months after RC surgery. Clinical features could not significantly improve the prediction efficiency of the radiomics model.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40644-022-00485-z.

Predictive Efficacy of Circulating Tumor Cells in First Drainage Vein Blood from Patients with Colorectal Cancer liver Metastasis

Circulating tumor cells (CTCs) are associated with metastasis. However, the low rate of detection of CTCs in peripheral vein blood (PVB) limits their clinical application. In this study, we observed higher positive rates of CTC in first drainage vein blood (FDVB) relative to peripheral venous blood (P < 0.001). Moreover, the CTC content was related to liver metastasis, T stage and CA19-9 levels. Our collective data suggest that CTCs in FDVB have good predictive utility for risk of liver metastasis of colorectal cancer (CRC), in particular, metachronous liver metastasis.

Comparison of contrast-enhanced transabdominal ultrasonography following endoscopic ultrasonography with GD-EOB-DTPA-enhanced MRI for the sequential diagnosis of liver metastasis in patients with pancreatic cancer

PURPOSE

To compare contrast-enhanced transabdominal ultrasonography (CE-US) following contrast-enhanced harmonic endoscopic ultrasonography (CH-EUS) with enhanced magnetic resonance imaging using gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (EOB-MRI) in the diagnosis of liver metastases in patients with pancreatic cancer.

METHODS

Patients who underwent contrast-enhanced computed tomography for possible pancreatic cancer and required further evaluation with CH-EUS were enrolled in this study, and the diagnostic performance of CE-US following CH-EUS for liver metastasis was compared with that of EOB-MRI.

RESULTS

A total of 228 patients were included in the final analysis. Two hundred thirty-four hepatic lesions were found in 81 patients, and 178 lesions were finally diagnosed as metastases. EOB-MRI had a higher sensitivity (0.837 vs 0.949), while CE-US had a higher specificity and positive predictive value (PPV) (0.982 and 0.993 vs 0.911 and 0.971, respectively) in the diagnosis of liver metastasis. CE-US with defect reperfusion imaging had a higher diagnostic performance than EOB-MRI (0.866 vs 0.667) in the differentiation between liver metastasis and abscess.

CONCLUSION

EOB-MRI had a higher sensitivity than CE-US for diagnosing liver metastasis in patients with pancreatic cancer, but CE-US following CH-EUS demonstrated a higher specificity and PPV than EOB-MRI and was especially useful in the differentiation between liver metastasis and abscess.

The Value of 18F-FDG-PET-CT Imaging in Treatment Evaluation of Colorectal Liver Metastases: A Systematic Review

(1) Background: Up to 50% of patients with colorectal cancer either have synchronous colorectal liver metastases (CRLM) or develop CRLM over the course of their disease. Surgery and thermal ablation are the most common local treatment options of choice. Despite development and improvement in local treatment options, (local) recurrence remains a significant clinical problem. Many different imaging modalities can be used in the follow-up after treatment of CRLM, lacking evidence-based international consensus on the modality of choice. In this systematic review, we evaluated ¹⁸F-FDG-PET-CT performance after surgical resection, thermal ablation, radioembolization, and neoadjuvant and palliative chemotherapy based on current published literature. (2) Methods: A systematic literature search was performed on the PubMed database. (3) Results: A total of 31 original articles were included in the analysis. Only one suitable study was found describing the role of ¹⁸F-FDG-PET-CT after surgery, which makes it hard to draw a firm conclusion. ¹⁸F-FDG-PET-CT showed to be of additional value in the follow-up after thermal ablation, palliative chemotherapy, and radioembolization. ¹⁸F-FDG-PET-CT was found to be a poor to moderate predictor of pathologic response after neoadjuvant chemotherapy. (4) Conclusions: ¹⁸F-FDG-PET-CT is superior to conventional morphological imaging modalities in the early detection of residual disease after thermal ablation and in the treatment evaluation and prediction of prognosis during palliative chemotherapy and after radioembolization, and ¹⁸F-FDG-PET-CT could be considered in selected cases after neoadjuvant chemotherapy and surgical resection.

Characteristics of false-positive lesions in evaluating colorectal liver metastases on gadoxetic acid-enhanced magnetic resonance imaging

PURPOSE

Gadoxetic acid-enhanced MRI (Gd-EOB-MRI) shows higher sensitivity for colorectal liver metastases (CRLM) than contrast-enhanced computed tomography (CECT). However, the details of false-positive lesions for each imaging modality are unknown.

METHODS

Cases undergoing hepatectomy for CRLM following a preoperative evaluation with both CECT and Gd-EOB-MRI between July 2008 and December 2016 were reviewed. The false-positive and false-negative rates were assessed for each modality, and the characteristics of false-positive lesions were evaluated.

RESULTS

We evaluated 275 partial hepatectomies in 242 patients without preoperative chemotherapy. Among the 275 hepatectomies, 546 lesions were recognized by CECT and/or Gd-EOB-MRI. The false-positive rates for CECT and Gd-EOB-MRI were 4% (18/422) and 7% (37/536), respectively. The size of false-positive lesions was significantly smaller than that of correctly diagnosed lesions (median: 28 mm [3-120 mm] vs 7.6 mm [320 mm], P  < 0.001). Compared with the 233 correctly diagnosed lesions ≤ 20 mm in diameter, false-positive lesions were more frequently located near the liver surface or vasculobiliary structures than true lesions (33/37 [89%] vs 149/233 [64%], respectively; P  = 0.0021).

CONCLUSION

Gd-EOB-MRI had a 7% false-positive rate. A small size and tumor location near the surface or near vasculobiliary structures were associated with false positivity.

Interindividual Comparison of Frequency-Selective Nonlinear Blending to Conventional CT for Detection of Focal Liver Lesions Using MRI as the Reference Standard

Background: Diagnosing liver lesions is challenging. CT is used for primary diagnosis; however, its contrast resolution is limited. Investigating methods for better detection of liver lesions is important. Objective: To evaluate the effect of frequency-selective nonlinear blending (NLB) on the detectability of liver lesions on CT. Methods: Retrospective search yielded 109 patients with malignant and benign liver lesions (n = 356; 191 principally diagnosed, 165 incidental findings) underwent contrast-enhanced CT (CECT) in portal venous phase and liver MRI between January 2012 and December 2017. Nonlinear blending (NLB) was applied to CECTs, and three readers rated image quality (5-point Likert scale) in blinded, independent, and randomized fashion. Focal lesions (n = 356) were evaluated for lesion identification and categorization to assess sensitivity. For 191 lesions (primary diagnosis) two readers evaluated CECT and NLB CT to compare size and subjective measurement accuracy. A fourth reader conducted ROI measurements for calculation of contrast-to-noise ratio (CNR), and a fifth reader reviewed MRI as standard of reference. Statistics included interobserver agreement, quantitative comparisons of CNR, lesion size, and subjective image analyses of image quality and sensitivity of detecting liver lesions. Results: Three readers rated image quality of NLB CT higher than for CECT (NLB CT, 4 [10% and 90% percentile: 4, 5]; CECT, 2 [1, 3]; p < .001). CECT showed good interreader agreement (interclass coefficient [ICC], 0.81 [95% CI, 0.76¬-0.85]); NLB CT also (ICC, 0.75 [95% CI, 0.69-0.79]). Mean CNR of liver lesions was increased using NLB (CECT, 4.18 [range, 1.67-9.06]; NLB CT, 12.49 [range, 6.18-23.39]; p < .001). Bland-Altman analysis of lesion size showed reduced underestimation from 2.5 mm (SD, 9.2 [95% CI, 1.2-3.9]) in CECT to 0.1 mm (SD, 3.9 [95% CI, -0.68 to 0.46) for NLB CT (concordance correlation coefficient, 0.99). Sensitivity for detecting liver lesions was increased to 86% for NLB CT (CECT, 76%). Conclusion: Frequency-selective NLB of CECT allows increased image quality and CNR, more precise size measurement, and higher sensitivity for detecting liver lesions. Clinical Impact: NLB CT improves liver lesion detection and increases the accuracy of lesion size measurement, which is important when considering local ablation or liver transplant.

Diagnostic Value of Delayed PET/MR in Liver Metastasis in Comparison With PET/CT

Objectives

The aim of this study was to evaluate the value of a delayed positron emission tomography/magnetic resonance (PET/MR) scan relative to a single positron emission tomography/computed tomography (PET/CT) scan for liver metastasis detection.

Methods

In this study, 70 patients with solid malignancies and suspicious liver lesions undergoing 2-deoxy-2-[¹⁸F]fluoro-D-glucose [(¹⁸F)FDG] PET/CT and subsequent delayed liver PET/MR scans were analyzed. The histopathological analysis and/or imaging follow-up were performed as the standard of reference. Lesion maximum standardized uptake value (SUVmax), diameter, and tumor to nontumor ratio (T/N) were measured. Lesion detection sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for both examinations.

Results

(1) The standard of reference revealed 208 liver lesions in 70 patients (metastasis in 56 patients with 196 lesions; benign in 14 patients with 12 lesions). Compared with PET/CT, PET/MR had higher accuracy (98.6% vs. 78.6%), sensitivity (98.2% vs. 76.8%), and specificity (100.0% vs. 85.7%) (2). The therapeutic strategies of 29 patients (41.4%) needed reconsideration after the additional PET/MR, including new metastases detected (13/70), new affected lobes identified (14/70), and false-positive corrected (2/70) (3). PET/MR detected significantly more metastases than PET/CT did, especially with small lesions. The SUVmax of the same lesion correlated well between the two acquisitions, while the delayed PET showed a higher T/N ratio.

Conclusions

In liver metastasis detection, the diagnostic value of the delayed PET/MR is validated to be superior to that of PET/CT, which may aid the clinical decision-making.

Imaging of colorectal cancer liver metastases using contrast-enhanced US, multidetector CT, MRI, and FDG PET/CT: a meta-analysis

BACKGROUND

Imaging of colorectal cancer liver metastases (CRCLMs) has improved in recent years. Therefore, the role of current imaging techniques needs to be defined.

PURPOSE

To assess the diagnostic performance of contrast-enhanced ultrasound (CEUS), multidetector computed tomography (MDCT), magnetic resonance imaging (MRI), and fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT in the detection of CRCLMs.

MATERIAL AND METHODS

PubMed database was searched for articles published during 2000-2019. Inclusion criteria were as follows: diagnosis/suspicion of CRCLMs; CEUS, MDCT, MRI, or FDG PET/CT performed for the detection of CRCLMs; prospective study design; histopathologic examination, intraoperative findings and/or follow-up used as reference standard; and data for calculating sensitivity and specificity reported.

RESULTS

Twelve prospective studies were assessed, including 536 patients with CRCLMs (n = 1335). On a per-lesion basis, the sensitivity of CEUS, MDCT, MRI, and FDG PET/CT was 86%, 84%, 89%, and 62%, respectively. MRI had the highest sensitivity on a per-lesion analysis. CEUS and MDCT had comparable sensitivities. On a per-patient basis, the sensitivity and specificity of CEUS, MDCT, MRI, and FDG PET/CT was 80% and 97%, 87% and 95%, 87% and 94%, and 96% and 97%, respectively. The per-patient sensitivities for MRI and MDCT were similar. The sensitivity for MRI was higher than that for CEUS, MDCT, and FDG PET/CT for lesions <10 mm and lesions at least 10 mm in size. Hepatospecific contrast agent did not improve diagnostic performances.

CONCLUSION

MRI is the preferred imaging modality for evaluating CRCLMs. Both MDCT and CEUS can be used as alternatives.

Imaging features of hepatic inflammatory pseudotumor: distinction from colorectal liver metastasis using gadoxetate disodium-enhanced magnetic resonance imaging

PURPOSE

To identify gadoxetate disodium-enhanced MRI features distinguishing hepatic IPT from CLM.

METHODS

From February 2008 to December 2019, 162 lesions (IPT, n = 31 and CLM, n = 131) from 94 patients (mean age 65.1 ± 12.2 years; 65 men and 29 women) were retrospectively assessed for the presence or absence of obscure boundary, rim enhancement on arterial phase (AP), persistent rim enhancement during AP to transitional phase (TP), blood vessel penetration, peritumoral parenchymal enhancement on AP, peritumoral parenchymal hypointensity on hepatobiliary phase (HBP), peritumoral parenchymal hyperintensity on T2-weighted imaging (T2WI), biliary dilatation, central hypointensity with a relatively hyperintense periphery on HBP, peripheral hyperintensity on diffusion-weighted imaging (DWI) and T2WI, and lesion to liver signal intensity ratio (SIR_lesion/liver) on HBP and DWI. Relevant features for differentiating between ITP and CLM were identified by univariate and multivariate analyses.

RESULTS

Univariate analysis revealed significantly higher frequencies of the following features in IPT than CLM: younger age, obscure boundary, blood vessel penetration, central hypointensity with a relatively hyperintense periphery on HBP, higher SIR_lesion/liver on HBP, and lower SIR_lesion/liver on DWI (P < 0.001‒0.035). Rim enhancement on AP and persistent rim enhancement during AP to TP were significantly more common in CLM than in IPT (P ≤ 0.001). Multivariate analysis revealed that a central hypointensity with a relatively peripheral hyperintensity on HBP, higher SIR_lesion/liver on HBP, and lower SIR_lesion/liver on DWI were predictive of IPT (P = 0.003‒0.039).

CONCLUSION

Central hypointensity with a relatively peripheral hyperintensity on HBP and SIR_lesion/liver on HBP and DWI may be reliable gadoxetate disodium-enhanced MRI features for distinguishing IPT from CLM.

Distinguishing intrahepatic mass-forming biliary carcinomas from hepatocellular carcinoma by computed tomography and magnetic resonance imaging using the Bayesian method: a bi-center study

OBJECTIVES

To determine imaging hallmarks for distinguishing intrahepatic mass-forming biliary carcinomas (IMBCs) from hepatocellular carcinoma (HCC) and to validate their diagnostic ability using Bayesian statistics.

METHODS

Study 1 retrospectively identified clinical and imaging hallmarks that distinguish IMBCs (n = 41) from HCC (n = 247) using computed tomography (CT) and magnetic resonance imaging (MRI). Study 2 retrospectively assessed the diagnostic ability of these hallmarks to distinguish IMBCs (n = 37) from HCC (n = 111) using Bayesian statistics with images obtained from a different institution. We also assessed the diagnostic ability of the hallmarks in the patient subgroup with high diagnostic confidence (≥ 80% of post-test probability). Two radiologists independently evaluated the imaging findings in studies 1 and 2.

RESULTS

In study 1, arterial phase peritumoral parenchymal enhancement on CT/MRI, delayed enhancement on CT/MRI, diffusion-weighted imaging peripheral hyperintensity, and bile duct dilatation were hallmarks indicating IMBCs, whereas chronic liver disease, non-rim arterial phase hyperenhancement on CT/MRI, enhancing capsule on CT/MRI, and opposed-phase signal drop were hallmarks indicating HCC (p = 0.001-0.04). In study 2, Bayesian statistics-based post-test probability combining all hallmark features had a diagnostic accuracy of 89.2% (132/148) in distinguishing IMBCs from HCC for both readers. In the high diagnostic confidence subgroup (n = 120 and n = 124 for readers 1 and 2, respectively), the accuracy improved (95.0% (114/120) and 93.5% (116/124) for readers 1 and 2, respectively).

CONCLUSIONS

Combined interpretation of CT and MRI to identify hallmark features is useful in discriminating IMBCs from HCCs. High post-test probability by Bayesian statistics allows for a more reliable non-invasive diagnosis.

KEY POINTS

• Combined interpretation of CT and MRI to identify hallmark features was useful in discriminating intrahepatic mass-forming biliary carcinomas from hepatocellular carcinoma. • Bayesian method-based post-test probability combining all hallmark features determined in study 1 showed high (> 90%) sensitivity and specificity for distinguishing intrahepatic mass-forming biliary carcinomas from hepatocellular carcinoma. • If the post-test probability or the confidence was ≥ 80% when combining the imaging features of CT and MRI, the high specificity of > 95% was achieved without any loss of sensitivity to distinguish hepatocellular carcinoma from intrahepatic mass-forming biliary carcinomas.

Surgical management of recurrent colon cancer

There have been significant developments in the management of advanced and recurrent colorectal cancer in recent decades. 70% of primary colorectal tumours arise in the colon and for patients with stage I-III disease, the standard of care is surgical resection followed by adjuvant therapy where appropriate. Locoregional recurrence (LR) occurs in 4-11.5% of patients following treatment of primary colon cancer with curative intent, and can be categorised as peri-anastomotic, mesenteric/paracolic (nodal), retroperitoneal and peritoneal. Of these, peritoneal recurrence is usually recognised as the most challenging type of recurrence to manage. Patients with isolated peri-anastomotic or limited nodal recurrence in the mesentery or retroperitoneum may be curable by radical salvage surgery, which often requires en bloc multi-visceral resection, while patients with low volume peritoneal metastases may be candidates for cytoreductive surgery with hyperthermic intraperitoneal chemotherapy. Ensuring complete resection along embryonic mesocolic planes or en bloc resection of contiguously involved structures are best strategies to reduce the likelihood of local recurrence through a R1 resection margin. The role of complete mesocolic excision (CME) with high vascular ligation has been demonstrated to increase nodal yield and improve overall survival although this is more contentious. In patients with T4a disease and serosal surface involvement, peritoneal recurrence represents the greatest threat. Efforts for early diagnosis of peritoneal recurrence in these patients or prophylactic treatment, while intuitive have not demonstrated the survival benefit that would be expected. Other than locoregional recurrence (LR), systemic recurrence may occur in up to 50% of patients who have undergone curative resection for colorectal cancer. In keeping with portal venous outflow, the most common site of systemic recurrence is the liver. Although previously thought to be a fatal condition, liver resection is now the standard of care where liver metastases can be completely resected with clear margins plus leaving an adequate liver remnant with intact vascular inflow, outflow and biliary drainage. This can usually be achieved in 26-45% of patients presenting with liver metastases. Liver surgeons at the forefront of liver resection have also developed techniques to induce liver hypertrophy so as to improve likelihood of resectability. Even where patients have non-resectable disease, ablative techniques have become increasingly common. Naturally, none of these would be possible without the advent of improved chemotherapeutic and biological options in the field of medical oncology. Pulmonary metastasectomy with curative intent may be possible in a small number (10%) of patients with lung metastases, which is associated with an overall survival of up to 40%. Unlike liver metastases, proportionally less patients with pulmonary metastases will be resectable. For these patients, several ablative options are available. For all patients with recurrent colon cancer, patient selection for radical salvage surgery and decisions surrounding treatment strategy (including use of systemic therapy or ablative procedures) should take place in a multidisciplinary team setting.

Gastric Cancer Staging: Is It Time for Magnetic Resonance Imaging?

Gastric cancer (GC) is a common cancer worldwide. Its incidence and mortality vary depending on geographic area, with the highest rates in Asian countries, particularly in China, Japan, and South Korea. Accurate imaging staging has become crucial for the application of various treatment strategies, especially for curative treatments in early stages. Unfortunately, most GCs are still diagnosed at an advanced stage, with the peritoneum (61-80%), distant lymph nodes (44-50%), and liver (26-38%) as the most common metastatic locations. Metastatic disease is limited to the peritoneum in 58% of cases; in nonperitoneal distant metastases, the most involved GC metastasization site is the liver (82%). The eighth edition of the tumor-node-metastasis staging system is the most commonly used system for determining GC prognosis. Endoscopic ultrasonography, computed tomography, and 18-fluorideoxyglucose positron emission tomography are historically the most accurate imaging techniques for GC staging. However, studies have recently shown renewed interest in magnetic resonance imaging (MRI) as a useful tool in GC staging, especially for distant metastasis assessment. The technical improvement of diffusion-weighted imaging and the increasing use of hepatobiliary contrast agents have been shown to increase the diagnostic performance of MRI, particularly for detecting peritoneal and liver metastasis. However, no principal oncological guidelines have included the use of MRI as a first-line technique for distant metastasis evaluation during the GC staging process, such as the National Comprehensive Cancer Network Guidelines. This review analyzed the role of the principal imaging techniques in GC diagnosis and staging, focusing on the potential role of MRI, especially for assessing peritoneal and liver metastases.

Optimal Combination of Features on Gadoxetate Disodium-enhanced MR Imaging for Non-invasive Differential Diagnosis of Hepatocellular Carcinoma: The JAMP-HCC Study

Purpose:

To determine the optimal combination of gadoxetate disodium-enhanced magnetic resonance imaging (MRI) findings for the diagnosis of hepatocellular carcinoma (HCC) and to compare its diagnostic ability to that of dynamic computed tomography (CT) in patients with chronic liver disease.

Methods:

This multi-institutional study consisted of two parts: Study 1, a retrospective study to determine the optimal combination of gadoxetate disodium-enhanced MRI findings (decision tree and logistic model) to distinguish HCC (n = 199) from benign (n = 81) or other malignant lesions (n = 95) (375 nodules in 269 patients) and Study 2, a prospective study to compare the diagnostic ability of gadoxetate disodium-enhanced MRI to distinguish HCC (n = 73) from benign (n = 15) or other malignant lesions (n = 12) with that of dynamic CT (100 nodules in 83 patients). Two radiologists independently evaluated the imaging findings (Study 1 and 2) and made a practical diagnosis (Study 2).

Results:

In Study 1, rim or whole enhancement on arterial phase images, signal intensities on T₂-weighted/diffusion-weighted/portal venous/transitional/hepatobiliary phase images, and signal drop on opposed-phase images were independently useful for differential diagnosis. In Study 2, the accuracy, sensitivity, negative predictive value, and negative likelihood ratio of the CT decision tree (reader 2) were higher than those of MRI Model 2 (P = 0.015–0.033). There were no other significant differences in diagnostic ability (P = 0.059–1.000) and radiologist-made practical diagnosis (P = 0.059–1.000) between gadoxetate disodium-enhanced MRI and CT.

Conclusion:

We identified the optimal combination of gadoxetate disodium-enhanced MRI findings for HCC diagnosis. However, its diagnostic ability was not superior to that of dynamic CT.

Imaging of Colorectal Liver Metastases: New Developments and Pending Issues

Computed tomography (CT), magnetic resonance imaging (MRI), and 18-fluorideoxyglucose positron emission tomography (¹⁸FDG-PET) are historically the most accurate imaging techniques for diagnosing liver metastases. Recently, the combination of diffusion-weighted imaging and hepatospecific contrast media, such as gadoxetic acid in MRI, have been demonstrated to have the highest diagnostic accuracy, sensitivity, and specificity for detecting liver metastases. Various recent meta-analyses have confirmed the diagnostic superiority of this combination (diffusion-weighted imaging and gadoxetic acid-enhanced MRI), especially in terms of per lesion sensitivity, as compared with CT and ¹⁸FDG-PET, even for smaller lesions (≤1 cm). However, none of the oncological guidelines have suggested the use of MRI as a first-line technique for liver metastasis detection during the staging process of oncological patients. This review analyzes the history of the principal imaging techniques for the diagnosis of liver metastases, in particular of colorectal liver metastases, focusing on the most accurate method (diffusion-weighted imaging combined with gadoxetic acid-enhanced MRI), possible reasons for the lack of its diffusion in the guidelines, and possible future scenarios.

Machine Learning-based Analysis of Rectal Cancer MRI Radiomics for Prediction of Metachronous Liver Metastasis

RATIONALE AND OBJECTIVES

To use machine learning-based magnetic resonance imaging radiomics to predict metachronous liver metastases (MLM) in patients with rectal cancer.

MATERIALS AND METHODS

This study retrospectively analyzed 108 patients with rectal cancer (54 in MLM group and 54 in nonmetastases group). Feature selection were performed in the radiomic feature sets extracted from images of T2-weighted image (T2WI) and venous phase (VP) sequence respectively, and the combining feature set with 2058 radiomic features incorporating two sequences with the least absolute shrinkage and selection operator method. Five-fold cross-validation and two machine learning algorithms (support vector machine [SVM]; logistic regression [LR]) were utilized for predictive model constructing. The diagnostic performance of the models was evaluated by receiver operating characteristic curves with indicators of accuracy, sensitivity, specificity and area under the curve, and compared by DeLong test.

RESULTS

Five, 8, and 22 optimal features were selected from 1029 T2WI, 1029 VP, and 2058 combining features, respectively. Four-group models were constructed using the five T2WI features (Model_T2), the 8 VP features (Model_VP), the combined 13 optimal features (Model_combined), and the 22 optimal features selected from 2058 features (Model_optimal). In Model_VP, the LR was superior to the SVM algorithm (P = 0.0303). The Model_optimal using LR algorithm showed the best prediction performance (P = 0.0019-0.0081) with accuracy, sensitivity, specificity, and area under the curve of 0.80, 0.83, 0.76, and 0.87, respectively.

CONCLUSION

Radiomics models based on baseline rectal magnetic resonance imaging has high potential for MLM prediction, especially the Model_optimal using LR algorithm. Moreover, except for Model_VP, the LR was not superior to the SVM algorithm for model construction.

Utility of Stack-of-stars Acquisition for Hepatobiliary Phase Imaging without Breath-holding

Purpose:

Post-contrast liver magnetic resonance imaging is typically performed with breath-hold 3D gradient echo sequences. However, breath-holding for >10 s is difficult for some patients. In this study, we compared the quality of hepatobiliary phase (HBP) imaging without breath-holding using the prototype pulse sequences stack-of-stars liver acquisition with volume acceleration (LAVA) (LAVA Star) with or without navigator echoes (LAVA Star_navi+ and LAVA Star_navi−) and Cartesian LAVA with navigator echoes (Cartesian LAVA_navi+).

Methods:

Seventy-two patients were included in this single-center, retrospective, cross-sectional study. HBP imaging using the three LAVA sequences (Cartesian LAVA_navi+, LAVA Star_navi−, and LAVA Star_navi+) without breath-holding was performed for all patients using a 3T magnetic resonance system. Two independent radiologists qualitatively analyzed (overall image quality, liver edge sharpness, hepatic vein clarity, streak artifacts, and respiratory motion/pulsation artifacts) HBP images taken by the three sequences using a five-point scale. Quantitative evaluations were also performed by calculating the liver-to-spleen, -lesion, and -portal vein (PV) signal intensity ratios. The results were compared between the three sequences using the Friedman test.

Results:

LAVA Star_navi+ showed the best image quality and hepatic vein clarity (P < 0.0001). LAVA Star_navi− showed the lowest image quality (P < 0.0001–0.0106). LAVA Star_navi+ images showed fewer streak artifacts than LAVA Star_navi− images (P < 0.0001), while Cartesian LAVA_navi+ images showed no streak artifacts. Cartesian LAVA_navi+ images showed stronger respiratory motion/pulsation artifacts than the others (P < 0.0001). LAVA Star_navi− images showed the highest liver-to-spleen ratios (P < 0.0001–0.0005). Cartesian LAVA_navi+ images showed the lowest liver-to-lesion and -PV ratios (P < 0.0001–0.0108).

Conclusion:

In terms of image quality, the combination of stack-of-stars acquisition and navigator echoes is the best for HBP imaging without breath-holding.

Predicting Patients With Insufficient Liver Enhancement in the Hepatobiliary Phase Before the Injection of Gadoxetic Acid: A Practical Approach Using the Bayesian Method

BACKGROUND

Gadoxetic acid-enhanced hepatobiliary phase (HBP) is useful in liver MRI, but sometimes shows insufficient liver enhancement. There is no established method to predict insufficient liver enhancement before the contrast injection.

PURPOSE

To reveal the utility of the Bayesian method for predicting patients with insufficient liver enhancement in the gadoxetic acid-enhanced HBP.

STUDY TYPE

Retrospective.

SUBJECTS

In all, 576 patients with chronic liver disease.

FIELD STRENGTH/SEQUENCE

3T/3D gradient-echo T₁ -weighted imaging and MR elastography (MRE).

ASSESSMENT

The patients were divided into two groups: insufficient and sufficient liver enhancement in HBP according to the liver-to-portal vein signal intensity ratio. Various parameters, including liver function tests and liver stiffness by MRE, were evaluated as predictors of insufficient liver enhancement.

STATISTICAL TESTS

We used Chi-square/Student's t-test/logistic regression analysis to determine independent associates, and Bayes' theorem to estimate the probability of insufficient (or sufficient) liver enhancement. The feasibility of Bayesian prediction of insufficient liver enhancement was tested by leave-one-out cross-validation to calculate sensitivity and specificity for single variables and combinations of some variables in all patients and in a subpopulation showing a confidence level of >80%.

RESULTS

Independent associates of insufficient liver enhancement in HBP included: serum albumin (odds ratio [OR] = 4.82, P < 0.001), total bilirubin (OR = 0.30, P < 0.00), platelet count (OR = 1.54, P < 0.00), and liver stiffness by MRE (OR = 0.59, P < 0.00). The accuracy of Bayesian prediction of insufficient liver enhancement was 80.9% (466/576) for the single parameter of albumin and 79.0% (455/576) for total bilirubin, and was increased to 85.2% (487/576) for a combination of albumin, total bilirubin, and liver stiffness. In patients who showed a confidence level of >80%, the accuracy was 89.0% (439/493) for the above combination.

DATA CONCLUSION

Bayesian prediction was useful to predict patients with insufficient enhancement by combining serum liver function tests and liver stiffness by MRE.

LEVEL OF EVIDENCE

3 Technical Efficacy Stage: 5 J. Magn. Reson. Imaging 2020;51:62-69.

Detection of liver metastases on gadobenate dimeglumine-enhanced MRI: systematic review, meta-analysis, and similarities with gadoxetate-enhanced MRI

OBJECTIVES

To determine the sensitivity and positive predictive value (PPV) of gadobenate-enhanced MR imaging for the detection of liver metastases.

METHODS

This systematic review and meta-analysis was conducted according to PRISMA guidelines. A comprehensive search (EMBASE, PubMed) was performed to identify relevant articles up to December 2017. Studies eligible for inclusion were performed using appropriate methodology with complete verification by means of histopathology, intraoperative observation and/or follow-up, and sufficient information to permit determination of true-positive (TP), false-negative (FN), and false-positive (FP) values. Sources of bias were assessed using the QUADAS-2 tool. An inverse variance-weighted random-effects model was used to obtain sensitivity and PPV estimates. Information was analyzed and presented using Cochran's Q statistic, funnel plots, and modified Deeks' analysis.

RESULTS

Ten articles (256 patients, 562 metastases) were included. Sensitivity estimates for pre-contrast (unenhanced) imaging, gadobenate-enhanced dynamic imaging, and combined unenhanced, dynamic, and delayed hepatobiliary phase imaging for detecting liver metastases on a per-lesion basis were 77.8% (95% CI 71.4-84.3%, 7 assessments), 88.1% (95% CI, 84.0-92.2%, 13 assessments), and 95.1% (95% CI 93.1-97.1%, 15 assessments), respectively. The addition of hepatobiliary phase images significantly improved the detection of liver metastases. The overall PPV was 90.9% (95% CI 86.6-95.1%, 11 assessments). Deeks' funnel analysis revealed no association between sample size and sensitivity (β = 0.02, p = 0.814) indicating no significant publication bias.

CONCLUSIONS

Gadobenate-enhanced MR imaging has high sensitivity and PPV for the detection of liver metastases on a per-lesion basis. The sensitivity and PPV for detection is comparable to reported values for the pure liver-specific agent gadoxetate.

KEY POINTS

• Gadobenate dimeglumine is a hepatobiliary MR contrast agent that permits acquisition of contrast-enhanced liver images during the immediate post-injection dynamic phase, like any extracellular agent, and in the delayed hepatobiliary phase, after specific uptake by the hepatocytes. • The hepatobiliary phase improves detection of liver metastases when compared either to pre-contrast unenhanced images alone or to pre-contrast + gadobenate-enhanced dynamic phase images. • The meta-analysis showed an overall sensitivity of 95.1% and PPV of 90.9% of gadobenate-enhanced MRI for the detection of metastases, when based on the evaluation of all available acquisitions.

Diagnostic accuracy of CE-CT, MRI and FDG PET/CT for detecting colorectal cancer liver metastases in patients considered eligible for hepatic resection and/or local ablation

PURPOSE

To compare the diagnostic performance of contrast-enhanced computed tomography (CE-CT), magnetic resonance imaging (MRI) and combined fluorodeoxyglucose/positron emission tomography/computed tomography (FDG-PET/CT) for detection of colorectal liver metastases (CRLM) in patients eligible for local treatment.

MATERIALS AND METHODS

This health-research ethics-committee-approved prospective consecutive diagnostic accuracy study, with written informed consent, included 80 cases (76 patients, four participating twice) between 29 June 2015 and 7 February 2017. Prior chemotherapy or local treatment did not exclude participation. Combined FDG-PET/CT including CE-CT and MRI was performed within 0-3 days shortly before local treatment. CE-CT and MRI images were read independently by two readers for each modality. The combined FDG-PET/CT images were read independently by two pairs of readers. A composite reference standard was used. Sensitivities, specificities and area under the receiver operating characteristic curves (AUC_ROC) were calculated and compared.

RESULTS

In total, 260 CRLMs were confirmed. The MRI readers had significantly higher per-lesion sensitivity (85.9% and 83.8%) than both CE-CT readers (69.1% and 62.3%) and both PET/CT reader pairs (72.0% and 72.1%) (p<0.001). There were no significant differences in per-lesion specificity. MRI readers had significantly higher AUC_ROC (0.92 and 0.88) than both CE-CT readers (0.80 and 0.82) (p≤0.001). AUC_ROC for MR reader 1 was higher than that of both PET/CT reader pairs (0.83 and 0.84) (p≤0.0001).

CONCLUSION

MRI performed significantly better than both CE-CT and combined FDG-PET/CT for detection of CRLM in consecutive patients eligible for local treatment irrespective of prior chemotherapy or local treatment.

KEY POINTS

• Patients eligible for local treatment of colorectal liver-metastases require optimal imaging. • In 80 consecutive patients, MRI had superior per lesion diagnostic performance. • Findings were independent of prior treatment and type of planned local treatment. • Equally, MRI had superior diagnostic performance on per segment basis.