Liver metastases of colorectal cancer: US, CT or MR?

A CT-based radiomics tumor quality and quantity model to predict early recurrence after radical surgery for colorectal liver metastases

PURPOSE

This study aimed to develop a tumor radiomics quality and quantity model (RQQM) based on preoperative enhanced CT to predict early recurrence after radical surgery for colorectal liver metastases (CRLM).

METHODS

A retrospective analysis was conducted on 282 cases from 3 centers. Clinical risk factors were examined using univariate and multivariate logistic regression (LR) to construct the clinical model. Radiomics features were extracted using the least absolute shrinkage and selection operator (LASSO) for dimensionality reduction. The LR learning algorithm was employed to construct the radiomics model, RQQM (radiomics-TBS), combined model (radiomics-clinical), clinical risk score (CRS) model and tumor burden score (TBS) model. Inter-model comparisons were made using area under the curve (AUC), decision curve analysis (DCA) and calibration curve. Log-rank tests assessed differences in disease-free survival (DFS) and overall survival (OS).

RESULTS

Clinical features screening identified CRS, KRAS/NRAS/BRAF and liver lobe distribution as risk factors. Radiomics model, RQQM, combined model demonstrated higher AUC values compared to CRS and TBS model in training, internal and external validation cohorts (Delong-test P < 0.05). RQQM outperformed the radiomics model, but was slightly inferior to the combined model. Survival curves revealed statistically significant differences in 1-year DFS and 3-year OS for the RQQM (P < 0.001).

CONCLUSIONS

RQQM integrates both "quality" (radiomics) and "quantity" (TBS). The radiomics model is superior to the TBS model and has a greater impact on patient prognosis. In the absence of clinical data, RQQM, relying solely on imaging data, shows an advantage in predicting early recurrence after radical surgery for CRLM.

Diagnostic Performance of Contrast Enhanced CT Alone or in Combination with (Non-)Enhanced MRI for Colorectal Liver Metastasis

RATIONALE AND OBJECTIVES

To compare the diagnostic performance of contrast enhanced CT (CE-CT), CE-CT combined with non-enhanced MRI (NE-MRI) or contrast enhanced MRI (CE-MRI) for colorectal liver metastasis (CRLM).

MATERIALS AND METHODS

Sixty-six colorectal cancer patients with 198 focal liver lesions who underwent preoperative abdominal CE-CT and MRI examinations were included respectively. The images were assessed independently by two readers in three protocols (1: CE-CT, 2: CE-CT+NE-MRI, 3: CE-CT+CE-MRI). The diagnostic performance of each protocol was analyzed by receiver operating characteristic (ROC) curve and the areas under ROC (AUCs) were calculated and compared.

RESULTS

The detection rates of protocol 2 were 90.9%-92.9% for liver lesions and 86.4%-89.6% for CRLM, and both significantly higher than protocol 1 of 82.8%-85.4% and 76.8%-80.8% (p<0.001-0.001), whereas similar to protocol 3 of 91.9%-94.4% and 87.2%-91.2% (p 0.250-1.000). The AUCs of protocol 2 were greater than protocol 1 for all lesions (0.914-0.934 vs. 0.779-0.799, p<0.001) and lesions < 10mm (0.726-0.776 vs. 0.528-0.561, p<0.001), and were not inferior to that of protocol 3 (0.929-0.949 in all lesions and 0.754-0.821 in lesion < 10mm, p 0.053-0.162).

CONCLUSION

CE-CT combined with NE-MRI offered superior diagnostic performance for CRLM compared to CE-CT alone and showed comparable performance to CE-CT combined with CE-MRI.

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, but its contrast resolution is limited. Investigating methods to improve detection of liver lesions is important. OBJECTIVE. The purpose of this study was to evaluate the effect of frequency-selective nonlinear blending on the detectability of liver lesions on CT. METHODS. A retrospective search yielded 109 patients with 356 malignant and benign liver lesions (191 principally diagnosed, 165 incidental findings) who underwent contrast-enhanced CT (CECT) in the portal venous phase and liver MRI between January 2012 and December 2017. Nonlinear blending was applied to CECT examinations, and three blinded readers independently rated the quality (5-point Likert scale) of randomly presented images. Focal lesions (n = 356) were evaluated for lesion identification and categorization to assess sensitivity. For 191 lesions (primary diagnosis), two readers evaluated CECT and nonlinear blending CT to compare lesion size and the accuracy of subjective measurements. A fourth reader performed ROI measurements for calculation of contrast-to-noise ratio (CNR), and a fifth reader reviewed MRI as the standard of reference. Statistics included interobserver agreement, quantitative comparisons of CNR, lesion size, and subjective image analyses of image quality and sensitivity for detecting liver lesions. RESULTS. Three readers rated the image quality of nonlinear blending CT (rating, 4; 10th-90th percentiles, 4-5) higher than that of CECT (rating, 2; 10th-90th percentiles, 1-3) (p < .001). CECT had good interreader agreement (interclass correlation coefficient [ICC], 0.81; 95% CI, 0.76-0.85), as did nonlinear blending CT (ICC, 0.75; 95% CI, 0.69-0.79). The median CNR of liver lesions increased with nonlinear blending (CECT, 4.18 [10th-90th percentiles, 1.67-9.06]; nonlinear blending CT, 12.49 [10th-90th percentiles, 6.18-23.39]; p < .001). Bland-Altman analysis of lesion size showed a reduction in underestimation from 2.5 (SD, 9.2) mm (95% CI, 1.2-3.9 mm) with CECT to 0.1 (SD, 3.9) mm (95% CI, -0.68 to 0.46 mm) for nonlinear blending CT (concordance correlation coefficient, 0.99). Sensitivity for detecting liver lesions increased to 86% for nonlinear blending CT. The sensitivity of CECT was 76%. CONCLUSION. Frequency-selective nonlinear blending in CECT increases image quality and CNR, increases the precision of size measurement, and increases sensitivity for detecting liver lesions. CLINICAL IMPACT. Use of nonlinear blending CT improves liver lesion detection and increases the accuracy of lesion size measurement, which is important when local ablation or liver transplant is being considered.

Detection of tumour boundary in metastatic liver disease with 2D multibreath-hold susceptibility-weighted imaging

PURPOSE

To investigate the feasibility of susceptibility weighted imaging (SWI) in detecting tumour boundaries in metastatic liver disease (MLD) without contrast agent, and whether SWI can provide pathophysiologic information for preoperative evaluation.

METHODS

Thirty patients with MLD underwent tumour resection. All patients underwent conventional MRI (T1-weighted and T2-weighted imaging), contrast-enhanced (CE) MRI and multibreath-hold 2D SWI. The conspicuity of the tumour boundary was assessed using a 4-grade scale. The detection rate of tumour boundaries and areas were reviewed and measured. The longest dimension was used to estimate the tumour size from the MR image. The conspicuity of the tumour boundary and area were compared using a nonparametric multi-group comparison (Friedman M). The McNemar test was applied to examine differences in the detection rate of tumour boundaries.

RESULTS

Among four different MRI sequences, SWI exhibited increased conspicuity of the tumour boundary than the conventional MRI (P < 0.001). SWI (91.8%) and CE-MRI (64.4%) exhibited higher detection rates of the tumour boundary than T1WI and T2WI (6.8% and 12.3% respectively). Longer tumour maximum diameters were measured with SWI (29.1 ± 17.2 mm) and CE-MRI (28.2 ± 16.8) compared to conventional MRI (P < 0.05).

CONCLUSION

2D multibreath-hold SWI enables enhanced noninvasive detection of tumour boundaries in patients with MLD compared with conventional MRI and CE-MRI without using an exogenous contrast agent. SWI has the potential to become a preoperative assessment standard that complements conventional MRI.

Deep learning-based image reconstruction of 40-keV virtual monoenergetic images of dual-energy CT for the assessment of hypoenhancing hepatic metastasis

OBJECTIVES

To evaluate the diagnostic value of deep learning model (DLM) reconstructed dual-energy CT (DECT) low-keV virtual monoenergetic imaging (VMI) for assessing hypoenhancing hepatic metastases.

METHODS

This retrospective study included 131 patients who underwent contrast-enhanced DECT (80-kVp and 150-kVp with a tin filter) in the portal venous phase for hepatic metastasis surveillance. Linearly blended images simulating 100-kVp images (100-kVp), standard 40-keV VMI images (40-keV VMI), and post-processed 40-keV VMI using a vendor-agnostic DLM (i.e., DLM 40-keV VMI) were reconstructed. Lesion conspicuity and diagnostic acceptability were assessed by three independent reviewers and compared using the Wilcoxon signed-rank test. The contrast-to-noise ratios (CNRs) were also measured placing ROIs in metastatic lesions and liver parenchyma. The detection performance of hepatic metastases was assessed by using a jackknife alternative free-response ROC method. The consensus by two independent radiologists was used as the reference standard.

RESULTS

DLM 40-keV VMI, compared to 40-keV VMI and 100-kVp, showed a higher lesion-to-liver CNR (8.25 ± 3.23 vs. 6.05 ± 2.38 vs. 5.99 ± 2.00), better lesion conspicuity (4.3 (4.0-4.7) vs. 3.7 (3.7-4.0) vs. 3.7 (3.3-4.0)), and better diagnostic acceptability (4.3 (4.0-4.3) vs. 3.0 (2.7-3.3) vs. 4.0 (4.0-4.3)) (p < 0.001 for all). For lesion detection (246 hepatic metastases in 68 patients), the figure of merit was significantly higher with DLM 40-keV VMI than with 40-keV VMI (0.852 vs. 0.822, p = 0.012), whereas no significant difference existed between DLM 40-keV VMI and 100-kVp (0.852 vs. 0.842, p = 0.31).

CONCLUSIONS

DLM 40-keV VMI provided better image quality and comparable diagnostic performance for detecting hypoenhancing hepatic metastases compared to linearly blended images.

KEY POINTS

• DLM 40-keV VMI provides a superior image quality compared with 40-keV or 100-kVp for assessing hypoenhancing hepatic metastasis. • DLM 40-keV VMI has the highest CNR and lesion conspicuity score for hypoenhancing hepatic metastasis due to noise reduction and structural preservation. • DLM 40-keV VMI provides higher lesion detectability than standard 40-keV VMI (p = 0.012).

Artificial intelligence in the diagnosis and management of colorectal cancer liver metastases

Colorectal cancer (CRC) is the third most common malignancy worldwide, with approximately 50% of patients developing colorectal cancer liver metastasis (CRLM) during the follow-up period. Management of CRLM is best achieved via a multidisciplinary approach and the diagnostic and therapeutic decision-making process is complex. In order to optimize patients' survival and quality of life, there are several unsolved challenges which must be overcome. These primarily include a timely diagnosis and the identification of reliable prognostic factors. Furthermore, to allow optimal treatment options, a precision-medicine, personalized approach is required. The widespread digitalization of healthcare generates a vast amount of data and together with accessible high-performance computing, artificial intelligence (AI) technologies can be applied. By increasing diagnostic accuracy, reducing timings and costs, the application of AI could help mitigate the current shortcomings in CRLM management. In this review we explore the available evidence of the possible role of AI in all phases of the CRLM natural history. Radiomics analysis and convolutional neural networks (CNN) which combine computed tomography (CT) images with clinical data have been developed to predict CRLM development in CRC patients. AI models have also proven themselves to perform similarly or better than expert radiologists in detecting CRLM on CT and magnetic resonance scans or identifying them from the noninvasive analysis of patients' exhaled air. The application of AI and machine learning (ML) in diagnosing CRLM has also been extended to histopathological examination in order to rapidly and accurately identify CRLM tissue and its different histopathological growth patterns. ML and CNN have shown good accuracy in predicting response to chemotherapy, early local tumor progression after ablation treatment, and patient survival after surgical treatment or chemotherapy. Despite the initial enthusiasm and the accumulating evidence, AI technologies' role in healthcare and CRLM management is not yet fully established. Its limitations mainly concern safety and the lack of regulation and ethical considerations. AI is unlikely to fully replace any human role but could be actively integrated to facilitate physicians in their everyday practice. Moving towards a personalized and evidence-based patient approach and management, further larger, prospective and rigorous studies evaluating AI technologies in patients at risk or affected by CRLM are needed.

Imaging of Colorectal Liver Metastasis

Colorectal cancer (CRC) is one of the most common cancers in the world. The most important determinant of survival and prognosis is the stage and presence of metastasis. The liver is the most common location for CRC metastasis. The only curative treatment for CRC liver metastasis (CRLM) is resection; however, many patients are ineligible for surgical resection of CRLM. Locoregional treatments such as ablation and intra-arterial therapy are also available for patients with CRLM. Assessment of response after chemotherapy is challenging due to anatomical and functional changes. Antiangiogenic agents such as bevacizumab that are used in the treatment of CRLM may show atypical patterns of response on imaging. It is vital to distinguish patterns of response in addition to toxicities to various treatments. Imaging plays a critical role in evaluating the characteristics of CRLM and the approach to treatment. CT is the modality of choice in the diagnosis and management of CRLM. MRI is best used for indeterminate lesions and to assess response to intra-arterial therapy. PET-CT is often utilized to detect extrahepatic metastasis. State-of-the-art imaging is critical to characterize patterns of response to various treatments. We herein review the imaging characteristics of CRLM with an emphasis on imaging changes following the most common CRLM treatments.

Antireflux catheter improves tumor targeting in liver radioembolization with resin microspheres

PURPOSE

We aimed to determine whether antireflux (ARC) catheter may result in better tumor targeting in liver radioembolization using 90Y-resin microspheres.

METHODS

Patients treated with resin microspheres for hepatocellular carcinoma (HCC) and secondary liver malignancies were retrospectively analyzed. All patients underwent a 99mTc-macroaggregated albumin (99mTc-MAA) single photon emission computed tomography (SPECT) following the planning arteriography with a conventional end-hole catheter. For 90Y-microspheres injection, two groups were defined depending on the type of catheter used: an ARC group (n=38) and a control group treated with a conventional end-hole catheter (n=23). 90Y positron emission tomography computed tomography (PET/CT) was performed after the therapeutic arteriography. The choice of the catheter was not randomized, but left to the choice of the interventional radiologist. 99mTc-MAA SPECT and 90Y PET/CT were co-registered with the baseline imaging to determine a tumor to normal liver ratio (T/NL[MAA or 90Y]) and tumor dose (TD[MAA or 90Y]) for the planning and therapy.

RESULTS

Overall, 38 patients (115 lesions) and 23 patients (75 lesions) were analyzed in the ARC and control groups, respectively. In the ARC group, T/NL90Y and TD90Y were significantly higher than T/NLMAA and TDMAA. Median (IQR) T/NL90Y was 2.16 (2.15) versus 1.74 (1.43) for T/NLMAA (p < 0.001). Median (IQR) TD90Y was 90.96 Gy (98.31 Gy) versus 73.72 Gy (63.82 Gy) for TDMAA (p < 0.001). In this group, the differences were highly significant for neuroendocrine metastases (NEM) and HCC and less significant for colorectal metastases (CRM). In the control group, no significant differences were demonstrated.

CONCLUSION

The use of an ARC significantly improves tumor deposition in liver radioembolization with resin microspheres.

All-Trans Retinoic Acid and Doxorubicin Delivery by Folic Acid Modified Polymeric Micelles for the Modulation of Pin1-Mediated DOX-Induced Breast Cancer Stemness and Metastasis

Stemness and metastasis are the two main challenges in cancer therapy and are related to disease relapse post-treatment. They both have a strong correlation with chemoresistance and poor prognosis, ultimately leading to treatment failure. It has been reported that chemotherapy can induce stemness and metastasis in many cancer types, especially treatment with the chemotherapeutic agent doxorubicin (DOX) in breast cancer. A combination treatment is an efficient and elegant approach in cancer therapy through simultaneous delivery of two or more drugs with a delivery system for its synergistic effect, which is not an additive of two individual drugs. Herein, we report a combinatorial system with DOX and all-trans retinoic acid (ATRA) to address both of the above issues. As a common critical regulatory factor for oncogenic signal transduction pathways, Pin1 is a specific isomerase highly expressed within various tumor cells. ATRA, a newly identified Pin1 inhibitor, can abolish several oncogenic pathways by effectively inhibiting and degrading overexpressed Pin1. We successfully developed a folic acid (FA)-modified chitosan (CSO)-derived polymer (FA-CSOSA) and obtained FA-CSOSA/DOX and FA-CSOSA/ATRA drug-loaded micelles. FA modification can improve the uptake of the nanoparticles in tumor cells and tumor sites via folate receptor-mediated cell internalization. Compared to treatment with DOX alone, the combined treatment induced 4T1 cell apoptosis in a synergistic manner. Reduced stemness-related protein expression and inhibited metastasis were observed during treatment with FA-CSOSA/DOX and FA-CSOSA/ATRA and were found to be associated with Pin1. Further in vivo experiments showed that treatment with FA-CSOSA/DOX and FA-CSOSA/ATRA resulted in 85.5% tumor inhibition, which was 2.5-fold greater than that of cells treated with DOX·HCl alone. This work presents a new paradigm for addressing chemotherapy-induced side effects via degradation of Pin1 induced by tumor-targeted delivery of DOX and ATRA.

Current state of the art imaging approaches for colorectal liver metastasis

One of the most common cancers worldwide, colorectal cancer (CRC) has been associated with significant morbidity and mortality and therefore represents an enormous burden to the health care system. Recent advances in CRC treatments have provided patients with primary and metastatic CRC a better long-term prognosis. The presence of synchronous or metachronous metastasis has been associated, however, with worse survival. The most common site of metastatic disease is the liver. A variety of treatment modalities aimed at targeting colorectal liver metastases (CRLM) has been demonstrated to improve the prognosis of these patients. Loco-regional approaches such as surgical resection and tumor ablation (operative and percutaneous) can provide patients with a chance at long-term disease control and even cure in select populations. Patient selection is important in defining the most suitable treatment option for CRLM in order to provide the best possible survival benefit while avoiding unnecessary interventions and adverse events. Medical imaging plays a crucial role in evaluating the characteristics of CRLMs and disease resectability. Size of tumors, proximity to adjacent anatomical structures, and volume of the unaffected liver are among the most important imaging parameters to determine the suitability of patients for surgical management or other appropriate treatment approaches. We herein provide a comprehensive overview of current-state-of-the-art imaging in the management of CRLM, including staging, treatment planning, response and survival assessment, and post-treatment surveillance. Computed tomography (CT) scan and magnetic resonance imaging (MRI) are two most commonly used techniques, which can be used solely or in combination with functional imaging modalities such as positron emission tomography (PET) and diffusion weighted imaging (DWI). Providing up-to-date evidence on advantages and disadvantages of imaging modalities and tumor assessment criteria, the current review offers a practice guide to assist providers in choosing the most suitable imaging approach for patients with CRLM.

Prognostic Factors for Event-Free Survival in Pediatric Patients with Hepatoblastoma Based on the 2017 PRETEXT and CHIC-HS Systems

This study aimed to evaluate the prognostic value of variables used in the 2017 PRE-Treatment EXTent of tumor (PRETEXT) system and the Children's Hepatic tumors International Collaboration-Hepatoblastoma Stratification (CHIC-HS) system in pediatric patients with hepatoblastoma. A retrospective analysis of data from the pediatric hepatoblastoma registry of a tertiary referral center was conducted to evaluate the clinical and imaging variables (annotation factors) of the PRETEXT staging system. The primary outcome was event-free survival (EFS). Data from 84 patients (mean age: 2.9 ± 3.5 years) identified between 1998 and 2017 were included. Univariable Cox proportional hazards analysis revealed that PRETEXT annotation factors P (portal vein involvement), F (multifocality of tumor), and M (distant metastasis) showed a significant negative association with EFS. Multivariable Cox proportional hazard analysis showed that factor F was the strongest predictor (HR (hazard ratio), 2.908; 95% CI (confidence interval), 1.061-7.972; p = 0.038), whereas factor M showed borderline significance (HR, 2.416; 95% CI, 0.918-6.354; p = 0.074). The prediction model based on F and M (F + M) showed good performance to predict EFS (C-statistic, 0.734; 95% CI, 0.612-0.854). In conclusion, the PRETEXT annotation factor F was the strongest predictor of EFS, and the F + M model showed good performance to predict EFS in pediatric patients with hepatoblastoma.

Impact of primary cancer features on behaviour of colorectal liver metastases and survival after hepatectomy

Background

Markers of tumour biology may be valuable prognostic indicators after hepatic resection of colorectal cancer liver metastases (CRLMs). Identification of the aggressiveness of these metastases might inform the appropriateness of hepatic surgery.

Methods

Patients undergoing liver resection for CRLMs between January 2001 and July 2013 in four tertiary hospitals were reviewed. A mathematical model to estimate CRLM doubling times was constructed for patients with metachronous metastases. Tumour doubling time was investigated in relation to the features of colorectal cancer, including KRAS status. The hazard rate for recurrence and death following hepatectomy was explored through the Kernel‐smoothed estimator.

Results

Of 1063 patients undergoing liver resection for CRLMs, 361 with metachronous metastases undergoing single‐stage hepatectomy were analysed. The mean doubling time in patients not receiving chemotherapy between surgery for colorectal cancer and CRLM was 71·4 days. Tumour doubling time was shorter in patients with more advanced primary tumour stages, with mutant KRAS and in those who did not receive chemotherapy. For fast‐growing CRLMs (doubling time less than 48 days), the risk of recurrence was highest within the first postoperative year, and was about 7 per cent per month.

Conclusion

Primary features of colorectal cancer were linked to aggressiveness of CRLMs as measured by doubling time.

Targeting High Expressed α5β1 Integrin in Liver Metastatic Lesions To Resist Metastasis of Colorectal Cancer by RPM Peptide-Modified Chitosan-Stearic Micelles

Liver metastasis is a leading death cause in colorectal cancer. The pathological differences between orthotopic tumors and metastatic lesions increased the therapeutic difficulty of metastasis. Herein, the α₅β₁ integrin receptor expression on metastatic cells was first measured, the result showed that metastatic cells expressed the α₅β₁ integrin higher than that of the original cells from orthotopic tumors. Afterward, RPM peptide-modified chitosan-stearic (RPM-CSOSA) was designed based on α₅β₁ integrin expression. The cytotoxicity and resistance to migration and the invasion ability of the targeting drug delivery system loading doxorubicin (DOX) and curcumin (CUR) were evaluated in vitro. The metastatic inhibition of the targeting drug delivery system was also investigated in HT29 liver metastatic models. The modified RPM peptide could increase the cellular internalization of CSOSA micelles in metastatic tumor cells and endothelial cells mediated by α₅β₁ integrin. The synergistic effects of RPM-CSOSA/DOX and RPM-CSOSA/CUR could obviously inhibit migratory and invasive abilities of HT29 cells and endothelial cells. Moreover, the RPM-CSOSA/DOX&RPM-CSOSA/CUR could obviously decrease the number of metastatic sites by 86.96%, while CSOSA/DOX&CSOSA/CUR decreased liver metastasis by 66.58% compared with that in the saline group. In conclusion, the RPM peptide-modified drug delivery system may provide insights into targeting the metastatic cells overexpressing the α₅β₁ integrin, and it has the potential to inhibit liver metastasis of colorectal cancer.

Local and transient gene expression primes the liver to resist cancer metastasis

The liver is the primary site of metastasis for gastrointestinal cancers and is a location highly susceptible to the establishment of metastasis in numerous other primary cancers, including breast, lung, and pancreatic cancers. The current standard of care typically consists of primary tumor resection and systemic administration of potent but toxic chemotherapeutics, yielding a minimal improvement in the median survival rate. CXCL12, a chemokine, is a key factor for activating the migration/survival pathways of CXCR4⁺ cancer cells and for recruiting immunosuppressive cells to areas of inflammation. Therefore, reducing CXCL12 concentrations within the liver has the potential to decrease tumor and immunosuppressive cell activation/migration within the liver. However, because of off-target toxicities associated with systemic administration of anti-CXCL12 therapies, transient and liver-specific expression of a CXCL12 trap is necessary. To address this challenge, we developed a lipid calcium phosphate nanoparticle optimized for delivering plasmid DNA, encoding an engineered CXCL12 protein trap, to the nucleus of liver hepatocytes. This pCXCL12-trap formulation yielded transient (4 days) liver-specific expression, which greatly decreased the occurrence of liver metastasis in two aggressive liver metastasis models, including colorectal [CT-26(FL3)] and breast (4T1) cancers. Subsequent studies in an aggressive human colorectal liver metastasis model (HT-29) decreased the establishment of liver metastasis more effectively than did systemic administration of the CXCL12 protein trap and to a level comparable to a high-dose regimen of a potent CXCR4 antagonist (AMD3100).

Clinical Application of Contrast-Enhanced Ultrasound Using High-Frequency Linear Probe in the Detection of Small Colorectal Liver Metastases

To compare the performance of contrast-enhanced ultrasound (CEUS) using high-frequency linear and convex probes in the detection of small colorectal liver metastases (CRLMs). A total of 85 patients with 143 small CRLMs were evaluated. High-frequency ultrasound (US) and CEUS detected significantly more superficial lesions within 60 mm below the skin than a convex probe (p <0.05). The detection rate decreased in the chemotherapy group, especially when using a convex probe for US (p <0.05). By combining convex and linear probes, detection rates of US and CEUS were significantly higher than that of a convex or a linear probe alone (p <0.05). High-frequency US and CEUS helped to improve detection of small CRLMs and reduce the influence of chemotherapy. For patients with a high risk of CRLMs and those after chemotherapy, we recommend first scanning the liver by using a convex probe and subsequently screening the surface area of the liver and suspicious small lesions by using a linear probe.

Comparison of Model-Based Iterative Reconstruction, Adaptive Statistical Iterative Reconstruction, and Filtered Back Projection for Detecting Hepatic Metastases on Submillisievert Low-Dose Computed Tomography

OBJECTIVE

The aim of the study was to compare the diagnostic performance of model-based iterative reconstruction (MBIR), adaptive statistical iterative reconstruction (ASIR), and filtered back projection (FBP) on submillisievert low-dose computed tomography (LDCT) for detecting hepatic metastases.

METHODS

Thirty-eight patients having hepatic metastases underwent abdomen CT. Computed tomography protocol consisted of routine standard-dose portal venous phase scan (120 kVp) and 90-second delayed low-dose scan (80 kVp). The LDCT images were reconstructed with FBP, ASIR, and MBIR, respectively. Two readers recorded the number of hepatic metastases on each image set.

RESULTS

A total of 105 metastatic lesions were analyzed. For reader 1, sensitivity for detecting metastases was stationary between FBP (49%) and ASIR (52%, P = 0.0697); however, sensitivity increased in MBIR (66%, P = 0.0035). For reader 2, it was stationary for all the following sets: FBP (65%), ASIR (68%), and MBIR (67%, P > 0.05).

CONCLUSIONS

The MBIR and ASIR showed a limited sensitivity for detecting hepatic metastases in submillisievert LDCT.

Detection of liver metastases in cancer patients with geographic fatty infiltration of the liver: the added value of contrast-enhanced sonography

Purpose

The aim of this study is to assess the role of contrast-enhanced ultrasonography (CEUS) in the detection of liver metastases in cancer patients with geographic liver fatty deposition on greyscale ultrasonography (US).

Methods

Thirty-seven consecutive cancer patients (24 women and 13 men; age, 33 to 80 years; mean, 58.1 years) with geographic liver fatty deposition, but without any detectable focal liver lesion on greyscale US, underwent sulphur hexafluoride-enhanced US. Two readers reported by consensus the presence, size, and location of any detected lesion. All patients underwent magnetic resonance imaging (MRI) as a confirmatory study. Sensitivity, specificity, positive and negative predictive values (PPV and NPV), and accuracy were calculated.

Results

Seven focal liver lesions (size, 4 to 10 mm; mean, 6.1 mm) were detected in 4/37 patients (10.8%): four metastases (size, 5 to 10 mm; mean, 6.7 mm) were detected both by CEUS and MRI, with one hemangioma and two cysts (size range, 4 to 6 mm; mean, 5.3 mm) detected by MRI only. In 1/37 patients (2.7%), CEUS misdiagnosed geographic fatty change as three metastases. In 32/37 patients (86.5%), no lesions were detected. Sensitivity, specificity, PPV, NPV, and accuracy of CEUS were 100% (95% confidence Interval [CI], 1.000 to 1.000), 97.1% (95% CI, 0.914 to 1.027), 75%, 100%, and 97.3%, respectively. No statistically significant differences were found between CEUS and MRI in the detection of focal liver lesions (P=0.480), whereas both of them performed better than baseline US (P<0.001).

Conclusion

CEUS improves the detection of liver metastases in cancer patients with geographic liver fatty deposition on greyscale US.

Six1 promotes colorectal cancer growth and metastasis by stimulating angiogenesis and recruiting tumor-associated macrophages

The homeoprotein Six1 is overexpressed in many human cancers and is associated with increased tumor progression and metastasis. Recent studies have shown that Six1 is associated with poorer overall survival in advanced-stage colorectal cancer (CRC). In the current study, we explored the functional changes and molecular events associated with Six1 overexpression in a mouse model of CRC. An orthotopic model and a splenic injection metastasis model were used to investigate the role of Six1 in CRC tumor growth and metastasis using mouse colon adenocarcinoma MC38 cells overexpressing Six1. We found that overexpression of Six1 dramatically promotes CRC tumor growth and metastasis in vivo. Six1 overexpression in MC38 increased protein levels of aldehyde dehydrogenase-1 and expanded CD44+/CD166+ populations, indicating Six1 increased features of cancer stem cells. In addition, Six1 overexpression stimulated angiogenesis by upregulating the expression of vascular endothelial growth factor (VEGF). Six1-overexpressing tumor cells recruited tumor-associated macrophages (TAM) by increasing the expression of macrophage-specific colony stimulating factor, chemokine (C-C motif) ligand 2/5 and VEGF, further facilitating CRC tumor growth and metastasis. Furthermore, we determined that Six1 activated mitogen-activated protein kinase (MAPK) signaling in CRC cells. In summary, our studies strongly suggest that Six1 overexpression promotes CRC growth and metastasis and remodels tumor stroma by stimulating angiogenesis and recruiting TAM. MAPK activation may be a pivotal event in Six1-associated tumor progression, which may provide opportunities for pharmacologic intervention.

An overview of imaging techniques for liver metastases management

Evaluation of liver metastases is one of the most common indications for liver imaging. Imaging plays a key role in the of assessment liver metastases. A variety of imaging techniques, including ultrasonography, computed tomography, MRI and PET combined with CT scan are available for diagnosis, planning treatment, and follow-up treatment response. In this paper, the authors present the role of imaging for the assessment of liver metastases and the contribution of each of the different imaging techniques for their evaluation and management. Following recent developments in the field of oncology, the authors also present the importance of imaging for the assessment of liver metastases response to therapy. Finally, future perspectives on imaging of liver metastases are presented.

Feasibility of Routine Application of Gadoxetic Acid-Enhanced MRI in Combination with Diffusion-Weighted MRI for the Preoperative Evaluation of Colorectal Liver Metastases

BACKGROUND

Gadoxetic acid-enhanced magnetic resonance imaging (MRI) in combination with diffusion-weighted MRI (Gd-EOB-MRI/DWI) has become popular for evaluating colorectal liver metastases (CRLM). This retrospective observational study aimed to determine whether this procedure should be indicated prior to hepatectomy in all patients with CRLM.

METHODS

A retrospective survey of relevant data of patients who had undergone hepatectomy for CRLM from 2008 to 2014 was performed. The rates of detection by contrast-enhanced computed tomography (CE-CT) and Gd-EOB-MRI/DWI were evaluated. In addition, relapse-free and overall survivals after primary hepatectomy were compared between patients who had undergone only CE-CT versus those who had undergone both CE-CT and Gd-EOB-MRI/DWI.

RESULTS

In all, 419 pathologically confirmed CRLM were resected in 202 hepatectomies in 177 patients. The sensitivity of detection of CRLM was 77 % for CE-CT and 93 % for Gd-EOB-MRI/DWI (P < 0.01). The sensitivity of detection of 1-5, 6-10, and 11-15 mm CRLM by CE-CT was 9.6 % (5/52), 47 % (26/55), and 76 % (57/75), respectively, whereas that by Gd-EOB-MRI/DWI was 54 % (28/52), 91 % (50/55), and 99 % (74/75), respectively; these differences are significant (P < 0.01 for all three groups). Relapse-free (P = 0.99) and overall survival (P = 0.79) did not differ significantly between 37 patients evaluated preoperatively by only CE-CT and 168 patients evaluated by both CE-CT and Gd-EOB-MRI/DWI.

CONCLUSION

Gd-EOB-MRI/DWI detects small CRLM (≤15 mm) with higher sensitivity than CE-CT. However, whether Gd-EOB-MRI/DWI should be a routine component of preoperative evaluation remains unclear in terms of survival benefit.

Identification of O-Linked Glycoproteins Binding to the Lectin Helix pomatia Agglutinin as Markers of Metastatic Colorectal Cancer

BACKGROUND

Protein glycosylation is an important post-translational modification shown to be altered in all tumour types studied to date. Mucin glycoproteins have been established as important carriers of O-linked glycans but other glycoproteins exhibiting altered glycosylation repertoires have yet to be identified but offer potential as biomarkers for metastatic cancer.

METHODOLOGY

In this study a glycoproteomic approach was used to identify glycoproteins exhibiting alterations in glycosylation in colorectal cancer and to evaluate the changes in O-linked glycosylation in the context of the p53 and KRAS (codon 12/13) mutation status. Affinity purification with the carbohydrate binding protein from Helix pomatia agglutinin (HPA) was coupled to 2-dimensional gel electrophoresis with mass spectrometry to enable the identification of low abundance O-linked glycoproteins from human colorectal cancer specimens.

RESULTS

Aberrant O-linked glycosylation was observed to be an early event that occurred irrespective of the p53 and KRAS status and correlating with metastatic colorectal cancer. Affinity purification using the lectin HPA followed by proteomic analysis revealed annexin 4, annexin 5 and CLCA1 to be increased in the metastatic colorectal cancer specimens. The results were validated using a further independent set of specimens and this showed a significant association between the staining score for annexin 4 and HPA and the time to metastasis; independently (annexin A4: Chi square 11.45, P = 0.0007; HPA: Chi square 9.065, P = 0.0026) and in combination (annexin 4 and HPA combined: Chi square 13.47; P = 0.0002).

CONCLUSION

Glycoproteins showing changes in O-linked glycosylation in metastatic colorectal cancer have been identified. The glycosylation changes were independent of p53 and KRAS status. These proteins offer potential for further exploration as biomarkers and potential targets for metastatic colorectal cancer.

Mathematical framework for activity-based cancer biomarkers

Advances in nanomedicine are providing sophisticated functions to precisely control the behavior of nanoscale drugs and diagnostics. Strategies that coopt protease activity as molecular triggers are increasingly important in nanoparticle design, yet the pharmacokinetics of these systems are challenging to understand without a quantitative framework to reveal nonintuitive associations. We describe a multicompartment mathematical model to predict strategies for ultrasensitive detection of cancer using synthetic biomarkers, a class of activity-based probes that amplify cancer-derived signals into urine as a noninvasive diagnostic. Using a model formulation made of a PEG core conjugated with protease-cleavable peptides, we explore a vast design space and identify guidelines for increasing sensitivity that depend on critical parameters such as enzyme kinetics, dosage, and probe stability. According to this model, synthetic biomarkers that circulate in stealth but then activate at sites of disease have the theoretical capacity to discriminate tumors as small as 5 mm in diameter-a threshold sensitivity that is otherwise challenging for medical imaging and blood biomarkers to achieve. This model may be adapted to describe the behavior of additional activity-based approaches to allow cross-platform comparisons, and to predict allometric scaling across species.

Role of PET/Computed Tomography in Radiofrequency Ablation for Malignant Pulmonary Tumors

Radiofrequency ablation (RFA) is a useful tool for local control of unresectable pulmonary neoplastic lesions. However, RFA is limited to tumors smaller than 4 cm and peripheral lesions. The sensitivity and specificity of FDG-PET are higher than those of computed tomography. FDG-PET at 3 to 6 months after RFA is important for predicting recurrence. Complications associated with RFA, such as infection and abscess formation, which concentrate glucose in the ablation area, can cause false-positive findings in PET examination. Knowledge of the morphologic imaging features of these complications is important in avoiding these potential pitfalls.

Is Non-Contrast CT Adequate for the Evaluation of Hepatic Metastasis in Patients Who Cannot Receive Iodinated Contrast Media?

Objective

To evaluate the appropriateness of follow-up with only non-enhanced CT (NECT) in patients with gastrointestinal cancer.

Subjects and Methods

This retrospective study included 323 patients with colorectal and gastric cancer who underwent two consecutive CT examinations (CT1 and CT2), including non-contrast and portal venous phase CT images, with an interval of 1 year. Patients were divided into 2 groups: Group A included patients with no hepatic metastasis on CT1 and with or without newly developed metastasis on CT2 to evaluate the diagnostic performance of NECT for detecting newly developed hepatic metastasis; Group B included patients with known hepatic metastasis both on CT1 and CT2 to evaluate the accuracy of NECT for the assessment of hepatic metastasis based on RECIST criteria (version 1.1). Contrast-enhanced CT (CECT) images were considered as reference standards.

Results

Group A included 172 patients (M:F = 107:65; mean age, 62.6 years). Among them, 57 patients had 95 metastases (mean size, 2.2 ± 1.3 cm). Per patient and per lesion sensitivity for diagnosing newly developed hepatic metastasis was 56.1–66.7% and 52.6–56.8%, respectively. In terms of small metastases (<1.5 cm), per lesion sensitivity was significantly decreased to 28.1–34.4% (P < 0.05). Metastasis size measurements were significantly smaller on NECT (P < 0.001) compared with reference standards. In Group B, the accuracy of response evaluation based on RECIST criteria was 65.6–72.2%.

Conclusions

NECT showed inadequate diagnostic performances in both detecting newly developed hepatic metastasis and evaluating the response of hepatic metastasis based on RECIST criteria.

Advances in understanding of colorectal liver metastasis and implications for the clinic

Colorectal cancer is one of the most common cancers in both the USA and Europe. Over the course of diagnosis, treatment and surveillance, up to 50% of these patients will develop metastases to their liver. In the past 20 years alone, there have been multiple advances in the management of these colorectal metastases to the liver. These advances have been made in characterization of these tumors, diagnosis and in treatment, both locally and systemically. Because of this progress, there are subsets of patients with this stage IV disease who are cured of their disease. While significant progress has been made, there still exist limitations in the management of metastatic colorectal cancer to the liver. This review outlines current strategies and highlights recent advances in the management of colorectal liver metastases.

Contrast-enhanced ultrasound in liver cancer

Contrast-enhanced ultrasound (CEUS) is a sure, noninvasive, repeatable imaging technique widely used in the characterization of benign and malignant liver lesions. The European Federation of Societies for Ultrasound in Medicine and Biology guidelines suggest the typical CEUS features of liver lesions as criteria for the noninvasive diagnosis in cirrhotic and not-cirrhotic patients. The clinical application of CEUS in the liver study is summarized in this review; the contrast-enhanced patterns of the most frequent liver lesions are described (hepatocellular and cholangiocellular carcinoma, liver metastases, hemangioma, focal nodular hyperplasia, adenoma). The role of this imaging technique in the diagnostic algorithm of liver malignancy is illustrated and the CEUS application in hepatologic and oncological settings is depicted.

Update on the role of imaging in management of metastatic colorectal cancer

Evolution in the treatment of metastatic colorectal cancer (mCRC) has led to significant improvement in the survival of these patients. Surgery is useful in patients with resectable disease. Liver-directed therapies such as hepatic arterial infusion, transarterial radio- and chemoembolization, and percutaneous ablation are sometimes used by oncologists when the liver is the only site of metastatic disease. Unresectable mCRC is typically treated with systemic chemotherapy. First-line systemic chemotherapeutic regimens for mCRC are FOLFOX (combination of 5-fluorouracil/leucovorin [5-FU/LV] and oxaliplatin) and FOLFIRI (combination of 5-FU/LV and irinotecan) combined with molecular targeted drugs. Molecular targeted therapies that are effective in treating mCRC include antiangiogenic agents such as bevacizumab-an antibody against vascular endothelial growth factor-and antibodies directed against epidermal growth factor receptor (EGFR). EGFR-directed antibodies such as cetuximab and panitumumab have been shown to produce activity only in wild-type KRAS tumors. Imaging modalities such as multidetector computed tomography (CT), magnetic resonance imaging, and positron emission tomography/CT play a major role in the selection of appropriate treatment strategies. Assessment of treatment response in patients who undergo liver-directed and systemic therapy requires imaging at regular intervals. Recent studies have shown that alternative treatment response criteria may be more predictive of pathologic response in mCRC than conventional criteria such as Response Evaluation Criteria in Solid Tumors. Awareness of unusual response patterns, as well as of complications and toxicities, is helpful in guiding patient management.

Liver metastases: Contrast-enhanced ultrasound compared with computed tomography and magnetic resonance

The development of ultrasound contrast agents with excellent tolerance and safety profiles has notably improved liver evaluation with ultrasound (US) for several applications, especially for the detection of metastases. In particular, contrast enhanced ultrasonography (CEUS) allows the display of the parenchymal microvasculature, enabling the study and visualization of the enhancement patterns of liver lesions in real time and in a continuous manner in all vascular phases, which is similar to contrast-enhanced computed tomography (CT) and contrast-enhanced magnetic resonance imaging. Clinical studies have reported that the use of a contrast agent enables the visualization of more metastases with significantly improved sensitivity and specificity compared to baseline-US. Furthermore, studies have shown that CEUS yields sensitivities comparable to CT. In this review, we describe the state of the art of CEUS for detecting colorectal liver metastases, the imaging features, the literature reports of metastases in CEUS as well as its technique, its clinical role and its potential applications. Additionally, the updated international consensus panel guidelines are reported in this review with the inherent limitations of this technique and best practice experiences.

Hepatocellular carcinoma and other hepatic malignancies: MR imaging

Magnetic resonance (MR) imaging surpasses all other imaging modalities in characterizing liver lesions by virtue of the exquisite tissue contrast, specificity for various tissue types, and extreme sensitivity to contrast enhancement. In addition to differentiating benign from malignant lesions, MR imaging generally discriminates between the various malignant liver lesions. Hepatocellular carcinoma constitutes most primary malignant liver lesions and usually arises in the setting of cirrhosis. Intrahepatic cholangiocarcinoma is a distant second and features distinctly different imaging features. Overall, metastases are the most common malignant liver lesions and arise from several primary neoplasms; most commonly gastrointestinal, lung, breast, and genitourinary.

The Preoperative Assessment of Hepatic Tumours: Evaluation of UK Regional Multidisciplinary Team Performance

Introduction. In the UK, patients where liver resection is contemplated are discussed at hepatobiliary multidisciplinary team (MDT) meetings. The aim was to assess MDT performance by identification of patients where radiological and pathological diagnoses differed. Materials and Methods. A retrospective review of a prospectively maintained database of all cases undergoing liver resection from March 2006 to January 2012 was performed. The presumed diagnosis as a result of radiological investigation and MDT discussion is recorded at the time of surgery. Imaging was reviewed by specialist gastrointestinal radiologists, and resultswereagreedonby consensus. Results. Four hundred and thirty-eight patients were studied. There was a significant increase in the use of preoperative imaging modalities (P ≤ 0.01) but no change in the rate of discrepant diagnosis over time. Forty-two individuals were identified whose final histological diagnosis was different to that following MDT discussion (9.6%). These included 30% of patients diagnosed preoperatively with hepatocellular carcinoma and 25% with cholangiocarcinoma of a major duct. Discussion. MDT assessment of patients preoperatively is accurate in terms of diagnosis. The highest rate of discrepancies occurred in patients with focal lesions without chronic liver disease or primary cancer, where hepatocellular carcinoma was overdiagnosed and peripheral cholangiocarcinoma underdiagnosed, where particular care should be taken. Additional care should be taken in these groups and preoperative multimodality imaging considered.

Development and characterization of a reliable mouse model of colorectal cancer metastasis to the liver

Colorectal cancer (CRC) is the third most frequent cancer and the third leading cause of cancer deaths in the United States (American Cancer Society, Cancer facts and figures 2012, 20121). The major cause of death is metastasis and frequently, the target organ is the liver. Successful metastasis depends on acquired properties in cancer cells that promote invasion and migration, and on multiple interactions between tumors and host-derived cells in the microenvironment. These processes, however, occur asymptomatically, thus, metastasis remains poorly understood and often diagnosed only at the final stage. To facilitate the elucidation of the mechanisms underlying these processes and to identify the molecular regulators, particularly at the early stages, we developed a mouse model of hepatic metastasis of CRC by cecal implantation of a mouse adenocarcinoma cell line in an immune competent host that reliably recapitulates all steps of tumor growth and metastasis within a defined period. By in vivo selection, we isolated cells of varying metastatic potential. The most highly metastatic CT26-FL3 cells produced liver metastasis as early as 10 days after implantation in 90 % of host mice. These cells expressed elevated levels of genes whose products promote invasion, migration, and mobilization of bone marrow derived cells (BMDCs). Mice bearing tumors from CT26-FL3 had elevated serum levels of OPN, MMP9, S100A8, S100A9, SAA3, and VEGFA that promote invasion and BMDC mobilization, and showed enhanced BMDC recruitment to the liver where they established a pre-metastatic niche. This model provides an important platform to characterize metastatic cells and elucidate tumor-host interactions and mechanisms that drive liver metastasis of CRC.

Non-invasive diagnosis of focal liver lesions: an individualized approach

Modern cross-sectional imaging with multidetector computed tomography (MDCT) or magnetic resonance imaging (MRI) often reveals small focal liver lesions, which puts pressure on the reporting radiologist to characterize these tiny lesions. On the other hand, in patients with underlying diffuse liver disease, such as cirrhosis or severe steatosis, the detection of focal liver lesions can be quite difficult. Strategies for optimal detection and characterization of focal liver lesions should be developed according to the clinical situation, the likelihood of malignant disease and the presence of underlying diffuse liver disease. The presence or absence of a clinical history of cancer determines the algorithm for further characterization: work-up with contrast-enhanced MRI, biopsy or follow-up. In patients with chronic liver disease, recent guidelines on the detection of hepatocellular carcinoma (HCC) favour the use of multiphasic MRI or MDCT, which allows confident diagnoses of HCC >1 cm. For lesions <1 cm in chronic liver disease, follow-up is recommended. In patients with moderate to severe steatosis, contrast-enhanced MDCT has low diagnostic yield for the detection of liver lesions; contrast-enhanced MRI is far superior. This review describes successful strategies for the detection and characterization of focal liver lesions in different clinical scenarios.

Gadoxetic acid-enhanced 3.0 T MR imaging versus multidetector-row CT in the detection of colorectal metastases in fatty liver using intraoperative ultrasound and histopathology as a standard of reference

OBJECTIVE

To compare the diagnostic value of gadoxetic acid-enhanced MRI at 3.0 T with 64-row MDCT in the detection of colorectal liver metastases in diffuse fatty infiltration of the liver after neoadjuvant chemotherapy.

METHODS

Twenty-three patients with colorectal liver metastases and at moderate to severe steatosis (25-90%) underwent prospectively preoperative tri-phasic MDCT (Somatom Sensation 64, Siemens) and gadoxetic acid-enhanced MRI (3-T Magnetom Trio, Siemens). All patients underwent surgical resection of liver metastases. Intraoperative ultrasound (IOUS) was carried out, which served as the standard of reference, together with histopathology.

RESULTS

Overall, 68 metastases (range, 0.4-6 cm; 31/68 metastases [46%] ≤ 1 cm) were found at histology. MDCT detected 49/68 lesions (72%), and MRI 66/68 (97%, p < 0.001). For lesions ≤ 1 cm, MDCT detected only 13/31 (41.9%) and MRI 29/31 (93%, p < 0.001). Eight false-positive lesions were detected by MDCT, seven small lesions by MRI. There was no statistically significant difference between the two modalities in the detection of lesions > 1 cm (p = 0.250). IOUS detected all metastases and revealed two false-positive diagnoses.

CONCLUSION

Gadoxetic acid-enhanced 3.0 T MRI is superior to 64-row MDCT in detecting colorectal liver metastases ≤ 1 cm during preoperative staging in patients with liver steatosis. A combination of MRI and IOUS may further improve the outcome of surgical treatment.

Hepatic tumors: region-of-interest versus volumetric analysis for quantification of attenuation at CT

PURPOSE

To evaluate the reproducibility of liver tumor attenuation measurement performed by using the routinely used manual region-of-interest (ROI) method and that of measurement performed by using a semiautomated volumetric approach at computed tomography (CT).

MATERIALS AND METHODS

This HIPAA-compliant retrospective study had institutional review board approval. The requirement for patient informed consent was waived. Attenuation of colon cancer liver metastases in 208 patients was measured on portal venous phase multidetector CT images by using a single ROI, the average measurement in three ROIs on a single section, and with semiautomated segmentation of the entire tumor volume (volumetric attenuation) to evaluate intermethod agreement. Intraobserver and interobserver reproducibility were evaluated in the first 70 patients. Measurements were repeated after 30 days to assess intraobserver reproducibility. Differences between methods were tested by using repeated-measures analysis of variance. Intermethod, intraobserver, and interobserver agreements were tested by using Bland-Altman analysis and the Lin concordance correlation coefficient (ρc). P < .05 was considered to indicate a significant difference.

RESULTS

A total of 208 pathologically proven colon cancer hepatic metastases larger than 20 mm in diameter in 100 women and 108 men (mean age, 61.6 years ± 11.6 [standard deviation]; range, 28-87 years) were evaluated. Attenuation was significantly different between the three methods of measurement (P < .001 for all). Volumetric measurements had better intraobserver agreement (precision = 3.3%, ρc = 0.996, P < .001) than single-ROI measurements (precision = 12.0%, ρc = 0.947, P < .001) and measurements averaged over three ROIs (precision = 9.3%, ρc = 0.965, P < .001). Volumetric measurements also had better interobserver agreement (precision = 3.6%, ρc = 0.993, P < .001) than single-ROI measurements (precision = 11.3%, ρc = 0.957, P < .001) and the average measurement in three ROIs (precision = 8.5%, ρc = 0.976, P < .001).

CONCLUSION

Measurements of hepatic tumor attenuation at multidetector CT are reproducible. An approach based on the evaluation of whole-lesion attenuation demonstrated better reproducibility than ROI measurements.

Imaging diagnosis of colorectal liver metastases

Rapid advances in imaging technology have improved the detection, characterization and staging of colorectal liver metastases. Multi-modality imaging approach is usually the more useful in diagnosis colorectal liver metastases. It is well established that hepatic resection improves the long-term prognosis of many patients with liver metastases. However, incomplete resection does not prolong survival, so knowledge of the exact extent of intra-hepatic disease is crucially important in determining patient management and outcome. The diagnosis of liver metastases relies first and totally on imaging to decide which patients may be surgical candidates. This review will discuss the imaging options and their appropriate indications. Imaging and evaluating of colorectal liver metastases (CRLM) have been performed with contrast-enhanced ultrasound, multi-detector computed tomography, magnetic resonance imaging (MRI) with extra-cellular contrast media and liver-specific contrast media MRI, and positron emission tomography/computed tomography. This review will concentrate on the imaging approach of CRLM, and also discuss certain characteristics of some liver lesions. We aim to highlight the advantages of each imaging technique, as well as underscoring potential pitfalls and limitations.

MRI of colorectal cancer liver metastases: comparison of orally administered manganese with intravenously administered gadobenate dimeglumine

OBJECTIVES

To compare the sensitivity of MRI to detect colorectal cancer liver metastases (CRLM) after ingestion of manganese-based contrast agent (CMC-001) with that of a comprehensive intravenous gadobenate dimeglumine protocol, and to assess the safety and acceptability of oral manganese.

METHODS

20 patients suspected of having 1-6 CRLM were included prospectively in this randomised cross-over study. Liver MRI was performed with a one-week interval at 1.5 T and included T1-w VIBE and T2-HASTE, before and after administration of 1.6 g CMC-001 or 0.1 mmol/kg gadobenate dimeglumine. The metastasis-to-liver signal intensity (SI) ratio was calculated. Standard of reference was histopathology after surgery, or combination of other imaging studies and/or follow up. Adverse events (AE) and clinicolaboratory tests were monitored.

RESULTS

Of 44 metastases, 41 were detected after CMC-001 (93%) and 42 after gadobenate dimeglumine (95%). Fifteen false-positive lesions were found after CMC-001 and 2 after gadobenate dimeglumine. The metastasis-to-liver SI ratio was significantly higher after CMC-001 than after gadobenate dimeglumine (0.51 and 0.21 respectively, P < 0.0001). More AE occurred after manganese compared to gadobenate dimeglumine.

CONCLUSIONS

CMC-001 is as sensitive as an extensive intravenous gadobenate dimeglumine protocol in detecting CRLM. It was relatively well tolerated but had higher rates of gastrointestinal AE.

KEY POINTS

• Liver MRI after ingestion of manganese is highly sensitive for detecting metastases • High false-positive rate necessitates further evaluation, in some cases • The MR examination time is short • Oral ingestion of manganese seems safe and relatively well tolerated by patients • Manganese compounds may be useful for liver metastasis surveillance after colorectal cancer.

[Malignant focal liver lesions]

Focal liver lesions are a very common occurrence. The detection and differentiation of such lesions is particularly important for the management of oncology patients and is a core task for radiology. The early and conclusive detection of malignant liver processes in a cost-efficient manner and with a low radiation dose for the patient requires systematic and skillful use of the various radiological methods. This review explains the application of current radiological methods for the detection and differentiation of malignant liver lesions and the typical appearance of the most commonly found liver malignancies.

Therapeutic response to radiofrequency ablation of neoplastic lesions: FDG PET/CT findings

Ablation of neoplastic lesions by using radiofrequency energy is gaining popularity in clinical practice because of the minimally invasive nature of radiofrequency ablation (RFA). Primary and secondary tumors of the liver and lung are treated with RFA when surgery is precluded because of comorbidity. Benign bone tumors are also treated with RFA to relieve pain and prevent further tumor growth. Differentiation between postablation tissue changes and residual disease is difficult with morphologic imaging modalities such as ultrasonography, computed tomography (CT), and magnetic resonance (MR) imaging, thus limiting the use of these modalities to detection of residual disease early after RFA. Fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) is a functional imaging modality that can be used to study the effects and efficacy of RFA. Lesions that show increased FDG uptake at PET become completely photopenic immediately after RFA, a finding that is suggestive of the completeness of ablation. Focal areas of increased FDG uptake within the ablated zone are suggestive of residual disease. Reactive tissue changes such as inflammation are depicted in the periphery of the ablated lesion and show a uniform low-grade FDG uptake, which can be differentiated from the focal, nodular intense uptake in areas of residual disease. Use of combined FDG PET/CT to detect residual disease early after RFA allows ablation to be repeated, if necessary, to obtain the maximum therapeutic benefit. Note that FDG uptake in the complications sometimes associated with RFA can be a cause of potential false-positive PET results.

Assessment of liver metastases from colorectal adenocarcinoma following chemotherapy: SPIO-MRI versus FDG-PET/CT

PURPOSE

This study compared superparamagnetic iron-oxide-enhanced magnetic resonance imaging (SPIO-MRI) and combined fluorodeoxyglucose positron emission tomography and computed tomography (FDG-PET/CT) in evaluating liver metastases from colorectal adenocarcinoma following chemotherapy.

MATERIALS AND METHODS

Nineteen patients were included in this retrospective study. SPIO-MRI and PET/CT results were compared with surgery, intraoperative ultrasound and pathology results in 11 patients and with the follow-up in eight patients.

RESULTS

SPIO-MRI and PET/CT identified 125 and 71 metastases, respectively. False negative lesions were 11 for SPIO-MRI and 65 for PET/CT. In the whole study population, the per-lesion analysis of SPIO-MRI and PET/CT showed a sensitivity of 92% and 52% (p<0.001) and the per-segment analysis a sensitivity of 99% and 79% (p<0.001), respectively. In patients who underwent surgery, the per-lesion analysis of SPIO-MRI and PET/CT showed a sensitivity of 85% and 58% (p<0.05) and the per-segment analysis a sensitivity of 97% and 63% (p<0.05), respectively. In patients who underwent follow-up, the per-lesion analysis of SPIO-MRI and PET/CT showed a sensitivity of 97% and 47% (p<0.001) and the per-segment analysis a sensitivity of 100% and 63% (p<0.007), respectively. For lesions ≥15 and <30 mm and for lesions <15 mm, SPIO-MRI demonstrated a higher sensitivity than PET/CT (p<0.001).

CONCLUSIONS

SPIO-MRI appears superior to PET/CT in evaluating liver metastases from colorectal adenocarcinoma following chemotherapy.

Preoperative detection of colorectal liver metastases in fatty liver: MDCT or MRI?

OBJECTIVE

To compare the diagnostic value of multidetector computed tomography (MDCT) and magnetic resonance imaging (MRI) in the preoperative detection of colorectal liver metastases in diffuse fatty infiltration of the liver, associated with neoadjuvant chemotherapy.

MATERIALS AND METHODS

Twenty preoperative tri-phasic MDCT (4-64-row, Siemens) and dynamic contrast-enhanced MRI (1.5T or 3.0T, Siemens) examinations of patients with colorectal cancer and liver metastases in diffuse steatosis were retrospectively evaluated. All patients underwent surgical resection for liver metastases (time interval 1-60 days). The amount of fatty infiltration of the liver was determined histopathologically by semi-quantitative percent-wise estimation and ranged from 25 to 75%.

RESULTS

Overall, 51 metastases were found by histopathology of the resected liver segments/lobes. The size of the metastases ranged from 0.4 to 13 cm, with 18 (35%) being up to 1cm in diameter. In the overall rating, MDCT detected 33/51 lesions (65%), and MRI 45/51 (88%). For lesions up to 1cm, MDCT detected only 2/18 (11%) and MRI 12/18 (66%). One false positive lesion was detected by MDCT. Statistical analysis showed that MRI is markedly superior to MDCT, with a statistically significant difference (p<.001), particularly for the detection of small lesions (≤ 1 cm; p<.004). There was no significant difference between the two modalities in the detection of lesions>1cm.

CONCLUSION

For the detection of colorectal liver metastases after neoadjuvant chemotherapy and consecutive diffuse fatty infiltration of the liver, MRI is superior to MDCT, especially for the detection of small lesions.