Radiosensitivity of Rat Mammary Tumors Correlates With Early Vessel Changes Assessed by Power Doppler Sonography

Abstract

Objective. To investigate the changes occurring in the vascularization of tumors during irradiation, we used a model of autochthonous mammary tumors in rats and assessed early vascular changes after irradiation by power Doppler sonography. Methods. Mammary tumors were induced in 24 female Sprague Dawley rats by a single subcutaneous injection of N-nitroso N-methyl urea. After tumor areas reached 1 cm 2 , the animals received a single fraction of 18-Gy radiation or intraperitoneal saline injection. Power Doppler sonographic quantification of detected vessels was performed 1 day before irradiation and 7 days after the use of a power Doppler index of 5 different tumor imaging planes. Final tumor shrinkage was compared with early changes in the power Doppler index. Not all tumors regressed in a similar fashion. Radiosensitive tumors were defined as tumors with a greater than 50% decrease in baseline area 28 days after irradiation, whereas radioresistant tumors were tumors with a less than 50% decrease in baseline area. Statistical analysis was performed by the Mann-Whitney U test. Results. Tumor area changes were similar in radioresistant and radiosensitive tumors 7 days after irradiation (-41% and -35%, respectively; P > .05, not significant), whereas reduction in the power Doppler index was significantly greater in radiosensitive tumors (mean value, -63%) than in radioresistant tumors (mean value, -12%) (P = .001). Late tumor regrowth was correlated with day 7 power Doppler index changes (P = .009). A 40% reduction in the power Doppler index at day 7 distinguished 8 of 9 radiosensitive tumors and 8 of 9 radioresistant tumors (P = .003). Conclusions. This study suggests that early changes in tumor perfusion as assessed by power Doppler sonography after tumor irradiation may precede the longterm tumor regression. Key words: angiogenesis; Doppler sonography; radiotherapy.

Evaluation of quantified contrast-enhanced color and power Doppler ultrasonography for the assessment of vascularity and perfusion of naturally occurring tumors in dogs

“…Vertebral column Squamous cell carcinoma (4) Rostral portion of oral cavity (4) Miscellaneous (6) Melanoma (2) Oral cavity (2) Adenocarcinoma, grade 3 (1) Nasal cavity and skull Histiocytoma (1) Skull Acanthomatous epulis (1) Oral cavity Oral lymphosarcoma (1) Oral cavity *For tumor diagnosis and grading, routine histologic evaluation of tumor specimens was performed; tumor staging was based on the World Health Organization system. †To be included in the study, each dog's tumor had to be superficial and accessible for ultrasonographic evaluation; all tumors were either localized in the oral cavity, on the skull, or on a limb.…”

“…The likelihood of recurrence, metastasis, and patient survival may also depend on tumor perfusion. In studies 4,5 in tumor-bearing mice and rats, Doppler ultrasonography has provided a valuable noninvasive method for serial examinations of tumor vascularity and perfusion during antiangiogenic treatment and radiation therapy. 1 For example, results of a recent experimental study 2 involving radiation therapy have suggested that both tumor and endothelial cells of the tumor microvasculature are damaged by radiation.…”

Changes in vascularity and blood volume as a result of photodynamic therapy can be assessed with power Doppler ultrasonography

“…Power Doppler ultrasound is an in vivo method that has been used successfully to non-invasively assess tumor vasculature in various human and experimental animal tumors [32][33][34][35]. It also offers the advantage of serial examinations during a treatment regimen, for example, during radiation therapy [6] and antiangiogenic therapy [7]. However, the spatial resolution of power Doppler ultrasound is limited to detect vessels not smaller than approximately 100 mm.…”

“…Power Doppler ultrasonography has been described as a useful noninvasive technique for assessment of tumor vascularity and blood volume [5]. Moreover, it was used successfully to monitor the effects of different therapeutic approaches targeting the tumor's vasculature, for example, radiation therapy [6] and antiangiogenic therapy [7]. Whereas color Doppler ultrasonography detects the frequency shift from moving blood cells to estimate the velocity, power Doppler ultrasonography displays the amplitude of the reflected Doppler signal from moving blood cells by a color map.…”

Plasmonic photothermal therapy: Approaches to advanced strategy

“…These differences may be associated with very diverse degree of tumor vascularization and therefore with the tumor progression status. The power Doppler ultrasound technique can be more sensitive than the color Doppler ultrasound in the depiction of tumor vascularity and flow [28]. However, cholangiocarcinoma belongs to tumors with low vascularization [29].…”