Preoperative evaluation of colorectal liver metastases: comparison of gadopentetate dimeglumine and gadoxetic-acid-enhanced 1.5-T MRI

Assessment of the percentage of apparent diffusion coefficient value changes as an early indicator of the response of colorectal hepatic metastases to chemotherapy

Background

Colorectal cancer is considered one of the most common causes of cancer-related deaths worldwide. We aim to evaluate the efficacy of DWI-MRI in predicting response to chemotherapy in this cohort.

The study included 30 lesions in 20 biopsy proven-colorectal cancer patients with hepatic metastasis larger than 1 cm. All patients underwent both triphasic CT with intravenous contrast, pre-chemotherapy MRI (axial T2 and DW sequences) which was repeated 21 days following chemotherapy. A follow-up CT was done 2 months later. The response of the lesions was evaluated using the RESCIST criteria. On MRI, the lesions corresponding to the ones chosen on CT were identified and the apparent diffusion coefficient (ADC) values of pre- and post-chemotherapy images were recorded and correlated with the CT results.

Results

In the study, 17 (56.7%) of the lesions showed response to chemotherapy while 13 (43.3%) were non-responding. There was no significant difference in pretreatment ADC values between responding and non-responding lesions (p = 0.14). The mean percentage increase in ADC values in responding lesions was 42% compared to 18% in non-responding lesions (p < 0.001). Lesions that showed less than 18% increase were all found to be non-responsive

Conclusion

DWI-MRI has an emerging role in early assessment of early treatment response that can be detected before morphological response for patients with hepatic metastasis from colorectal cancer. Based on our study, the use of 25 % as the cutoff point of percent difference in ADC for detection of non-responding lesions proved to be successful only 21 days after the 1st chemotherapy cycle.

Diagnostic performance of contrast-enhanced ultrasound and magnetic resonance imaging for detecting colorectal liver metastases: A systematic review and meta-analysis

OBJECTIVES

To determine the diagnostic performance of contrast-enhanced ultrasound, diffusion-weighted magnetic resonance imaging and contrast-enhanced magnetic resonance imaging for detecting colorectal liver metastases.

METHODS

We performed comprehensive searches of the MEDLINE, EMBASE, and Cochrane Library databases to identify studies reporting the per-lesion diagnostic accuracy of contrast-enhanced ultrasound, diffusion-weighted magnetic resonance imaging, and contrast-enhanced magnetic resonance imaging for detecting colorectal liver metastases. Studies published between January 2003 and December 2018 with reference standards, including histopathology and intraoperative observation, and/or follow-up, were included. Sources of bias were assessed using the QUADAS-2 tool. A linear mixed-effects regression model was used to determine sensitivity estimates.

RESULTS

Overall, 47 articles were included. The sensitivity estimates for contrast-enhanced ultrasound, diffusion-weighted magnetic resonance imaging, and contrast-enhanced magnetic resonance imaging for detecting colorectal liver metastases were 85.3%, 83.0%, and 90.1%, respectively. For lesions ≥10 mm in diameter, the sensitivities were 93.1%, 92.9%, and 94.5%, respectively. In 21 articles using histopathology as the only reference standard, the sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio for contrast-enhanced ultrasound/contrast-enhanced magnetic resonance imaging were 86%/91%, 91%/95%, 9.2/16.6, 0.15/0.10, and 61/170, respectively.

CONCLUSIONS

CEUS showed a diagnostic ability comparable to that of DWI and CEMRI, particularly for lesions ≥10 mm in diameter.

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.

Does the Gadoxetic Acid-Enhanced Liver MRI Impact on the Treatment of Patients with Colorectal Cancer? Comparison Study with ¹⁸F-FDG PET/CT

Objectives. We evaluated the value of Gadoxetic acid-enhanced liver MRI in the preoperative staging of colorectal cancer and estimated the clinical impact of liver MRI in the management plan of liver metastasis. Methods. We identified 108 patients who underwent PET/CT and liver MRI as preoperative evaluation of colorectal cancer, between January 2011 and December 2013. We evaluated the per nodule sensitivity of PET/CT and liver MRI for liver metastasis. Management plan changes were estimated for patients with metastatic nodules newly detected on liver MRI, to assess the clinical impact. Results. We enrolled 131 metastatic nodules (mean size 1.6 cm) in 41 patients (mean age 65 years). The per nodule sensitivities of PET/CT and liver MRI were both 100% for nodules measuring 2 cm or larger but were significantly different for nodules measuring less than 2 cm (59.8% and 95.1%, resp., P = 0.0001). At least one more metastatic nodule was detected on MRI in 16 patients. Among these, 7 patients indicated changes of management plan after performing MRI. Conclusions. Gadoxetic acid-enhanced liver MRI detected more metastatic nodules compared with PET/CT, especially for small (<2 cm) nodules. The newly detected nodules induced management plan change in 43.8% (7/16) of patients.

Gadoxetic acid: pearls and pitfalls

Gadoxetic acid is a hepatocyte-specific magnetic resonance imaging contrast agent with the ability to detect and characterize focal liver lesions and provide structural and functional information about the hepatobiliary system. Knowledge of the pharmacokinetics of gadoxetic acid is paramount to understanding imaging protocol and lesion appearance and facilitates identification and avoidance of undesired effects with use of this intravenous contrast agent. This article reviews the utility of gadoxetic acid in liver and biliary imaging, with emphasis on the hepatobiliary phase.

A meta-analysis of diffusion-weighted and gadoxetic acid-enhanced MR imaging for the detection of liver metastases

OBJECTIVES

To obtain the diagnostic performance of diffusion-weighted (DW) and gadoxetic-enhanced magnetic resonance (MR) imaging in the detection of liver metastases.

METHODS

A comprehensive search (EMBASE, PubMed, Cochrane) was performed to identify relevant articles up to June 2015. Inclusion criteria were: liver metastases, DW-MR imaging and/or gadoxetic acid-enhanced MR imaging, and per-lesion statistics. The reference standard was histopathology, intraoperative observation and/or follow-up. Sources of bias were assessed using the QUADAS-2 tool. A linear mixed-effect regression model was used to obtain sensitivity estimates.

RESULTS

Thirty-nine articles were included (1,989 patients, 3,854 metastases). Sensitivity estimates for DW-MR imaging, gadoxetic acid-enhanced MR imaging and the combined sequence for detecting liver metastases on a per-lesion basis was 87.1 %, 90.6 % and 95.5 %, respectively. Sensitivity estimates by gadoxetic acid-enhanced MR imaging and the combined sequence were significantly better than DW-MR imaging (p = 0.0001 and p < 0.0001, respectively), and the combined MR sequence was significantly more sensitive than gadoxetic acid-enhanced MR imaging (p < 0.0001). Similar results were observed in articles that compared the three techniques simultaneously, with only colorectal liver metastases and in liver metastases smaller than 1 cm.

CONCLUSIONS

In patients with liver metastases, combined DW-MR and gadoxetic acid-enhanced MR imaging has the highest sensitivity for detecting liver metastases on a per-lesion basis.

KEY POINTS

• DW-MRI is less sensitive than gadoxetic acid-enhanced MRI for detecting liver metastases • DW-MRI and gadoxetic acid-enhanced MRI is the best combination • Same results are observed in colorectal liver metastases • Same results are observed in liver metastases smaller than 1 cm • Same results are observed when histopathology alone is the reference standard.