Sonographic depiction of changes of tumor vascularity in response to various therapies
Kenneth J Niermann1, Arthur C Fleischer, Edwin F Donnelly
1Cancer Imaging Research Fellow, Vanderbilt University Medical Center, Department of Radiology and Radiological Sciences, Nashville, Tennessee 37232, USA. ken.niermann@vanderbilt.edu
Purpose:
To evaluate the diagnostic accuracy of power Doppler sonography for the depiction of changes in tumor vascularity with various therapeutic regimens.
Materials And Methods:
Tumor cells were implanted subcutaneously in thirty-two mice and assigned to four treatment groups: control, radiation therapy, antiangiogenesis therapy (VEGF [vascular endothelial growth factor] receptor antagonist, SU11248), or combined antiangiogenesis and radiation therapy. Twenty of these mice were scanned with power Doppler sonography at two time points over the course of treatment, and power-weighted pixel densities were assessed. The other twelve mice each underwent subcutaneous placement of a dorsal skin-fold window over the tumor site, allowing for daily angiogenesis assessment of vascular length density. All tumor specimens had correlative histologic analyses performed, including immunohistochemical stains for microvasculature.
Results:
Sonographic measurements revealed significant longitudinal differences in tumor vascularity among the four treatment groups: control mice receiving no treatment demonstrated a doubling in intra-tumor color pixel density (P < 0.02); those receiving radiation alone increased by 68% (P < 0.04); those receiving oral therapy alone increased by 44% (P = 0.016); and those receiving combination therapy decreased by 38% (P < 0.02). Tumor vascularity independently measured in the twelve mice with the skin-fold windows revealed a similar response to each type of treatment. Post-mortem tumor histology was consistent with both sonographic and skin-fold window measurements.
Conclusion:
Power Doppler sonography was accurate and reliable in measuring tumor vascularity changes in this model. These results were independently confirmed by a quantitative method relying on direct visualization of the microvasculature. Because it is rapid and non-invasive, sonographic quantification is beneficial in assessing the anti-angiogenic effects of various treatment strategies for cancer.
Insights
Power Doppler sonography accurately measures tumor vascularity changes during cancer treatment. This non-invasive imaging technique reliably assesses anti-angiogenic therapy effects, confirmed by histology.
Area of Science:
- Oncology
- Medical Imaging
- Vascular Biology
Background:
- Tumor vascularity is a key factor in cancer progression and treatment response.
- Assessing changes in tumor vascularity non-invasively is crucial for evaluating therapeutic efficacy.
Purpose of the Study:
- To evaluate the diagnostic accuracy of power Doppler sonography in depicting tumor vascularity changes.
- To assess the utility of power Doppler sonography in response to various cancer therapeutic regimens.
Main Methods:
- Subcutaneous tumors were established in mice and divided into control, radiation, antiangiogenesis (VEGF receptor antagonist), and combination therapy groups.
- Power Doppler sonography was used to measure tumor vascularity (power-weighted pixel densities) in vivo.
- Correlative assessments included dorsal skin-fold window angiogenesis and post-mortem histological analysis of tumor microvasculature.
Main Results:
- Significant longitudinal differences in tumor vascularity were observed across treatment groups using power Doppler sonography.
- Combination therapy led to a decrease in tumor vascularity (-38%), while other treatments showed increases.
- Sonographic findings were consistent with direct microvessel visualization and histological analyses.
Conclusions:
- Power Doppler sonography is an accurate and reliable method for quantifying tumor vascularity changes in response to therapy.
- Sonographic quantification offers a rapid, non-invasive approach to assess anti-angiogenic treatment strategies.
- This technique aids in monitoring treatment effectiveness and guiding cancer therapy decisions.
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