Equivalent cross-relaxation rate imaging and diffusion weighted imaging for early prediction of response to bevacizumab-containing treatment in colorectal liver metastases-preliminary study

PURPOSE

To evaluate and compare the usefulness of equivalent cross-relaxation rate (ECR) imaging (ECRI) and diffusion-weighted imaging (DWI) in the early prediction of the response of bevacizumab-containing treatments of colorectal liver metastases.

METHODS AND MATERIAL

Seven patients received bevacizumab-containing treatments for colorectal liver metastases. Serial magnetic resonance imaging was performed to evaluate responses before and 2 weeks after starting chemotherapy. In the ECRI, we adopted the off-resonance technique for preferential saturation of immobile protons to evaluate the ECR values. A single saturation transfer pulse frequency was used at a frequency of 3.5 ppm downfield from the water resonance. In the DWI, the apparent diffusion coefficient (ADC) value commonly used with two b-values was acquired by using diffusion weightings of 0 and 800 s/mm². The region of interest of the metastatic lesions in the liver was separately measured by ECRI and DWI. Tumor response was assessed by response evaluation criteria in solid tumors criteria 8 weeks after starting chemotherapy.

RESULTS

In this study, we had four responders and three nonresponders. There was a significant difference in the pretreatment ECR values between the responders and nonresponders (P=.01); there was no significant difference in the ADC values between the two groups. Analysis of the percentage difference between the pretreatment and post-treatment values, termed as percentage change, showed that there were no significant differences in the percentage change of the ADC values between both groups; however, the percentage change in the ECR value was significantly greater for the responders than for the nonresponders (-41.6%±17.1% vs. -12.9%±6.9%, respectively; P=.04).

CONCLUSION

The pretreatment ECR value and percentage change of the ECR value 2 weeks after starting chemotherapy were useful parameters in the early prediction of response to bevacizumab-containing treatment in colorectal liver metastases.

Equivalent cross-relaxation rate imaging positively correlates with pathological grade and cell density of adipocytic tumors

OBJECTIVE

Equivalent cross-relaxation rate imaging (ECRI) is an MRI technique used to evaluate qualitative changes in protein-water interactions. We aimed to prospectively evaluate the utility of ECRI for classification of adipocytic tumors.

MATERIALS AND METHODS

Institutional Review Board approval was obtained and all patients provided informed consent. Study participants included 40 patients with adipocytic tumors who were diagnosed with lipomas (n=22), atypical lipomatous tissue/well-differentiated liposarcoma (ALT/WDL; n=9), myxoid/round cell liposarcoma (MyL; n=6), and dedifferentiated liposarcoma (DDL; n=3), and 20 control patients for whom subcutaneous fat in the buttock or thigh was analyzed.

RESULTS

Mean ECR values of lipomas, ALT/WDL, and subcutaneous fat were low, and those of MyL and DDL were high. Mean ECR values of MyL and DDL were significantly higher than those of ALT/WDL. The cut-off value was 5.1%. There was a positive correlation between ECR value, pathological grade, and cell density in adipocytic tumors.

CONCLUSION

The ECR value positively correlates with pathological grade and cell density of adipocytic tumors. Our findings suggest that ECRI is a useful method for preoperative evaluation of adipocytic tumors.

Cellular density evaluation for malignant lymphoma using equivalent cross-relaxation rate imaging - initial experience

Objective

Equivalent cross-relaxation rate (ECR) imaging is an MRI technique used to evaluate quantitatively a change in the protein-water interaction. We aimed to evaluate retrospectively the usefulness of ECR imaging for the histologic classification of malignant lymphoma (ML).

Materials and Methods

Institutional Review Board approval was obtained and all patients provided informed consent. The study subjects included 15 patients with untreated ML who were histologically diagnosed with follicular lymphoma (FL; n = 8) or diffuse large B-cell lymphoma (DLBCL; n = 7). All patients underwent ECR imaging and the offset frequency was set at 7 ppm.

Results

The median ECR values were 71% (range; 60.7 to 75.5) in FL and 54% (50.8 to 59.4) in DLBCL (p = 0.001). The median cellular density was 1.5 ± 0.17 × 10⁶ / mm² in FL and 1.0 ± 0.70 × 10⁶ / mm² in DLBCL (p = 0.001). The correlation coefficient between the ECR values and cellular density in ML was 0.88 (p = 0.001). In FL and DLBCL, assuming ECR value cut-off points of 60%, both sensitivity and specificity were 100%.

Conclusion

A strong correlation between ECR and cellular density in ML is demonstrated and the ECR may be a useful technique to differentiate between FL and DLBCL.