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Radiosensitivity of Rat Mammary Tumors Correlates With Early Vessel Changes Assessed by Power Doppler Sonography
Author(s) -
Denis Fabrice,
Bougnoux Philippe,
Paon Lénaïc,
le Floch Olivier,
Tranquart François
Publication year - 2003
Publication title -
journal of ultrasound in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 91
eISSN - 1550-9613
pISSN - 0278-4297
DOI - 10.7863/jum.2003.22.9.921
Subject(s) - medicine , radioresistance , radiosensitivity , power doppler , nuclear medicine , mammary tumor , pathology , radiology , radiation therapy , cancer , breast cancer , ultrasonography
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 long‐term tumor regression.