Hepatic steatosis assessment with CT or MRI in patients with colorectal liver metastases after neoadjuvant chemotherapy

Potential of MR histogram analyses for prediction of response to chemotherapy in patients with colorectal hepatic metastases

PURPOSE

To determine if magnetic resonance imaging (MRI) histogram analyses can help predict response to chemotherapy in patients with colorectal hepatic metastases by using response evaluation criteria in solid tumours (RECIST1.1) as the reference standard.

MATERIALS AND METHODS

Standard MRI including diffusion-weighted imaging (b=0, 500 s/mm(2)) was performed before chemotherapy in 53 patients with colorectal hepatic metastases. Histograms were performed for apparent diffusion coefficient (ADC) maps, arterial, and portal venous phase images; thereafter, mean, percentiles (1st, 10th, 50th, 90th, 99th), skewness, kurtosis, and variance were generated. Quantitative histogram parameters were compared between responders (partial and complete response, n=15) and non-responders (progressive and stable disease, n=38). Receiver operator characteristics (ROC) analyses were further analyzed for the significant parameters.

RESULTS

The mean, 1st percentile, 10th percentile, 50th percentile, 90th percentile, 99th percentile of the ADC maps were significantly lower in responding group than that in non-responding group (p=0.000-0.002) with area under the ROC curve (AUCs) of 0.76-0.82. The histogram parameters of arterial and portal venous phase showed no significant difference (p>0.05) between the two groups.

CONCLUSION

Histogram-derived parameters for ADC maps seem to be a promising tool for predicting response to chemotherapy in patients with colorectal hepatic metastases.

KEY POINTS

• ADC histogram analyses can potentially predict chemotherapy response in colorectal liver metastases. • Lower histogram-derived parameters (mean, percentiles) for ADC tend to have good response. • MR enhancement histogram analyses are not reliable to predict response.

Predictors of early recurrence after resection of colorectal liver metastases

Background

Early recurrence after resection of colorectal liver metastases (CLM) is common. Patients at risk of early recurrence may be candidates for enhanced preoperative staging and/or earlier postoperative imaging. The aim of this study was to determine if there are any risk factors that specifically predict early liver-only and systemic recurrence.

Methods

Retrospective analysis of prospective database of patients undergoing liver resection (LR) for CLM from 2004 to 2006 was undertaken. Early recurrence was defined as occurring within 18 months of LR. Patients were classified into three groups: early liver-only recurrence, early systemic recurrence and recurrence-free. Preoperative factors were compared between patients with and without early recurrence.

Results

Two hundred and forty-three consecutive patients underwent LR for CLM. Twenty-seven patients (11%) developed early liver-only recurrence. Dukes C stage and male sex were significantly associated with early liver-only recurrence (P < 0.05). Sixty-six patients (27%) developed early systemic recurrence. Tumour size ≥3.6 cm and tumour number (>2) were significantly associated with early systemic recurrence (P < 0.001).

Conclusions

It is possible to stratify patients according to the risk of early liver-only or systemic recurrence after resection of CLM. High-risk patients may be candidates for preoperative MRI and/or computed tomography-positron emission tomography (CT-PET) scan and should receive intensive postoperative surveillance.

Texture analysis of preoperative CT images for prediction of postoperative hepatic insufficiency: a preliminary study

BACKGROUND

Texture analysis is a promising method of analyzing imaging data to potentially enhance diagnostic capability. This approach involves automated measurement of pixel intensity variation that may offer further insight into disease progression than do standard imaging techniques alone. We postulated that postoperative liver insufficiency, a major source of morbidity and mortality, correlates with preoperative heterogeneous parenchymal enhancement that can be quantified with texture analysis of cross-sectional imaging.

STUDY DESIGN

A retrospective case-matched study (waiver of informed consent and HIPAA authorization, approved by the Institutional Review Board) was performed comparing patients who underwent major hepatic resection and developed liver insufficiency (n = 12) with a matched group of patients with no postoperative liver insufficiency (n = 24) by procedure, remnant volume, and year of procedure. Texture analysis (with gray-level co-occurrence matrices) was used to quantify the heterogeneity of liver parenchyma on preoperative CT scans. Statistical significance was evaluated using Wilcoxon's signed rank and Pearson's chi-square tests.

RESULTS

No statistically significant differences were found between study groups for preoperative patient demographics and clinical characteristics, with the exception of sex (p < 0.05). Two texture features differed significantly between the groups: correlation (linear dependency of gray levels on neighboring pixels) and entropy (randomness of brightness variation) (p < 0.05).

CONCLUSIONS

In this preliminary study, the texture of liver parenchyma on preoperative CT was significantly more varied, less symmetric, and less homogeneous in patients with postoperative liver insufficiency. Therefore, texture analysis has the potential to provide an additional means of preoperative risk stratification.

New perspectives in the assessment of future remnant liver

In order to achieve microscopic radical resection margins and thus better survival, surgical treatment of hepatic tumors has become more aggressive in the last decades, resulting in an increased rate of complex and extended liver resections. Postoperative outcomes mainly depend on the size and quality of the future remnant liver (FRL). Liver resection, when performed in the absence of sufficient FRL, inevitably leads to postresection liver failure. The current gold standard in the preoperative assessment of the FRL is computed tomography volumetry. In addition to the volume of the liver remnant after resection, postoperative function of the liver remnant is directly related to the quality of liver parenchyma. The latter is mainly influenced by underlying diseases such as cirrhosis and steatosis, which are often inaccurately defined until microscopic examination after the resection. Postresection liver failure remains a point of major concern that calls for accurate methods of preoperative FRL assessment. A wide spectrum of tests has become available in the past years, attesting to the fact that the ideal methodology has yet to be defined. The aim of this review is to discuss the current modalities available and new perspectives in the assessment of FRL in patients scheduled for major liver resection.

Colorectal liver metastases: state of the art imaging

Colorectal cancer is a leading cause of death with mortality determined predominately by metastatic involvement of the liver. Treatment of liver metastases continues to evolve and imaging plays an essential role in initial staging, preoperative planning, and treatment monitoring. This review article discusses the current role of imaging in the management of patients with colorectal liver metastases. Particular challenges such as hepatic steatosis, disappearing metastases, and following treated lesions are addressed.

Treatment decisions after diagnosis of metastatic colorectal cancer

Treatment of metastatic colorectal cancer (mCRC) involves the use of active cytotoxic drugs (irinotecan, oxaliplatin, 5-fluorouracil [5-FU], and capecitabine) and biological agents (bevacizumab, cetuximab, and panitumumab) either in combination or as single agents. Until recently, the only biological agent with proven first-line efficacy was bevacizumab, but options have expanded from the data generated with anti-endothelial growth factor (EGFR) monoclonal antibodies. Anti-EGFR agents can be added to first-line FOLFIRI (5-fluorouracil, leucovorin [folinic acid], irinotecan) or FOLFOX (5-fluorouracil, leucovorin [folinic acid], oxaliplatin) in patients whose tumors express wild-type KRAS. These agents may improve outcomes when added to chemotherapy, particularly progression-free survival (PFS), and in the case of cetuximab, overall survival (OS) and response rates. The selection of first-line therapy should be based on the individual treatment goals after considering the efficacy and tolerability of each regimen. For patients with metastases confined to the liver, surgical resection offers a potentially curative approach. For initially unresectable lesions, treatment regimens offering high response rates may produce sufficient tumor shrinkage to permit complete resection. Regimens with high response rates are also preferable for patients requiring symptom relief or for those with large tumor burdens. The choice between intensive vs. nonintensive management also depends on other factors, including the patient's functional status, comorbidities, and desires. A sequential single-agent strategy or an intermittent approach (combination therapy followed by maintenance) may minimize toxicity and be appropriate for patients who are not surgical candidates, irrespective of treatment response. Guidelines, such as those of the National Comprehensive Cancer Network (NCCN), recommend that KRAS mutational status should be determined at mCRC diagnosis to identify candidates for anti-EGFR therapy whether they are used in first or subsequent lines of treatment.

Colorectal chemotherapy-associated liver injury

The increasing use of more effective chemotherapy in patients with colorectal cancer has raised awareness of the potential liver injuries induced by systemic drugs, such as fluorouracil, oxaliplatin and irinotecan. Chemotherapy-associated liver injuries can be revealed by histopathologic examination of nontumoral liver tissue. There are two broad categories of chemotherapy-induced liver injury: non-alcoholic fatty liver disease and sinusoidal injury. Many reports suggest that liver injuries may increase morbidity and mortality in patients who undergo hepatic resection for colorectal liver metastases, while some researchers have opposing views. This review describes the main types of chemotherapy-related liver injury and current controversy over this topic.

Culture and characterization of thymic epithelium from autoimmune NZB and NZB/W mice

Autoimmune NZB and NZB/W mice display early abnormalities in thymus histology, T cell development, and mature T cell function. Abnormalities in the subcapsular/medullary thymic epithelium (TE) can also be inferred from the early disappearance of thymulin from NZB. It has also been reported that NZB thymic epithelial cells do not grow in culture conditions that support the growth of these cells from other strains of mice. In order to study the contribution of TE to the abnormal T cell development and function in NZB and NZB/W mice, we have devised a culture system which supports the growth of TE cells from these mice. The method involves the use of culture vessels coated with extracellular matrix produced by a rat thymic epithelial cell line. TEA3A1, and selective low-calcium, low-serum medium. In addition TEA3A1 cells have been used as an antigen to generate monoclonal antibodies specific for subcapsular/medullary TE. These antibodies, as well as others already available, have been used to show that the culture conditions described here select for cells displaying subcapsular/medullary TE markers, whereas markers for cortical TE and macrophages are absent.