Correlation between high field MR images and histopathological findings of rat transplanted cancer immediately after partial microwave coagulation

Relating Doses of Contrast Agent Administered to TIC and Semi-Quantitative Parameters on DCE-MRI: Based on a Murine Breast Tumor Model

Objective

To explore the changes in the time-signal intensity curve(TIC) type and semi-quantitative parameters of dynamic contrast-enhanced(DCE)imaging in relation to variations in the contrast agent(CA) dosage in the Walker 256 murine breast tumor model, and to determine the appropriate parameters for the evaluation ofneoadjuvantchemotherapy(NAC)response.

Materials and Methods

Walker 256 breast tumor models were established in 21 rats, which were randomly divided into three groups of7rats each. Routine scanning and DCE-magnetic resonance imaging (MRI) of the rats were performed using a 7T MR scanner. The three groups of rats were administered different dosages of the CA0.2mmol/kg, 0.3mmol/kg, and 0.5mmol/kg, respectively; and the corresponding TICs the semi-quantitative parameters were calculated and compared among the three groups.

Results

The TICs were not influenced by the CA dosage and presented a washout pattern in all of the tumors evaluated and weren’t influenced by the CA dose. The values of the initial enhancement percentage(E_first), initial enhancement velocity(V_first), maximum signal(S_max), maximum enhancement percentage(E_max), washout percentage(E_wash), and signal enhancement ratio(SER) showed statistically significant differences among the three groups (F = 16.952, p = 0.001; F = 69.483, p<0.001; F = 54.838, p<0.001; F = 12.510, p = 0.003; F = 5.248, p = 0.031; F = 9.733, p = 0.006, respectively). However, the values of the time to peak(T_peak), maximum enhancement velocity(V_max), and washout velocity(V_wash)did not differ significantly among the three dosage groups (F = 0.065, p = 0.937; F = 1.505, p = 0.273; χ2 = 1.423, p = 0.319, respectively); the washout slope(Slope_wash), too, was uninfluenced by the dosage(F = 1.654, p = 0.244).

Conclusion

The CA dosage didn’t affect the TIC type, T_peak, V_max, V_wash or Slope_wash. These dose-independent parameters as well as the TIC type might be more useful for monitoring the NAC response because they allow the comparisons of the DCE data obtained using different CA dosages.

A micro-imaging study linking bone cancer pain with tumor growth and bone resorption in a rat model

Bone metastases represent a frequent complication of advanced breast cancer. As tumor growth-induced bone remodeling progresses, episodes of severe pain and fractures of weight-bearing limbs increase. All of these skeletal-related events influence the patient's quality of life and survival. In the present study, we sought to determine whether some of these pain-related behaviors could be directly correlated to tumor progression and bone remodeling. For this purpose, we used a rat model of bone cancer pain based on the implantation of mammary carcinoma cells in the medullary cavity of the femur. The bone content and tumor growth were monitored over time by magnetic resonance imaging (MRI) and micro X-ray computed tomography (μCT). The same animals were evaluated for changes in their reflexive withdrawal responses to mechanical stimuli (allodynia) and weight-bearing deficits. As assessed by MRI, we found a negative correlation between tumor volume and allodynia or postural deficits throughout the experiment. Using μCT, we found that the bone volume/total volume (BV/TV) ratios for trabecular and cortical bone correlated with both mechanical hypersensitivity and weight-bearing impairment. However, whereas trabecular BV/TV stabilized between days 7 and 10 post-tumor detection, the cortical bone loss reached its maximum at that time. Our imaging approach also allowed us to consistently detect the tumor before the onset of pain, paving the way for the preemptive identification of at-risk patients. Altogether, these results improve our understanding of the events leading to tumor-induced bone pain and could eventually help in the design of novel strategies for the management of bone diseases.

Therapeutic effect of microwave ablation combined with injection of 5-fluorouracil in mice bearing CT26 colon carcinoma xenografts

AIM: To evaluate the therapeutic effect of microwave ablation (MA) combined with injection of 5-fluorouracil (5-FU) in mice bearing CT26 colon carcinoma xenografts.

METHODS: Balb/c mice were subcutaneously inoculated with CT26 cells to establish a xenograft mouse model of colon carcinoma. Model mice were divided into four groups: PBS group, MA group, 5-FU group, and MA plus 5-FU group. After treatment, the changes in tumor volume were measured; tumor recurrence, mouse survival and living status were observed; and peripheral serum levels of TNF-α, IL-2, IL-12 and IFN-γ were determined by ELISA.

RESULTS: The life span of mice treated by MA, 5-FU injection, MA plus 5-FU was significantly longer than that of mice treated with PBS (47 d ± 1.7 d, 36 d ± 2.1 d, 56 d ± 2.5 d vs 33 d ± 1.4 d, all P < 0.05). Tumor size significantly decreased in the MA plus 5-FU group compared to the other three groups (all P < 0.05). Peripheral serum levels of TNF-α, IL-2, IL-12, and IFN-γ in the combination therapy group were significantly higher than those in the other three groups (180.3 ± 35.9 vs 62.8 ± 12.7, 96.3 ± 25.1, 136.9 ± 49.4; 72.5 ± 6.8 vs 20.6 ± 7.3, 27.9 ± 10.5, 46.4 ± 9.3; 302.3 ± 69.6 vs 123.4 ± 13.1, 153.8 ± 35.4, 278.9 ± 57.0; 68.4 ± 8.2 vs 29.9 ± 4.3, 36.8 ± 4.6, 59.1 ± 9.0; all P < 0.01).

CONCLUSION: MA combined with 5-FU injection can improve anti-tumor effect by strengthening immunological function and reducing local recurrences as compared to that of either treatment alone.