MONITORING TREATMENT RESPONSE WITH COLOR AND POWER DOPPLER

Color and power Doppler are now widely used to monitor treatment respo nse because of the latest technologic advances and of the increasing u se of echo-enhancing agents. The assessment of treatment response is b ased on the amount of necrosis obtained and changes in local vasculari zation indicate a successful treatment. To date, clinical experiences have mainly concerned the treatment of hepatocellular carcinomas, hype rfunctioning nodules of the thyroid and parathyroid glands and the neo adjuvant chemotherapy of breast cancer. Aim of this review is to descr ibe the role and potentials of color and power Doppler in this field. Hepatocellular carcinomas are currently treated with surgery or percut aneous ethanol injection and/or chemoembolization. Treatment response can be monitored with color Doppler: after a successful treatment, col or signals are no longer detectable on color Doppler images. Conversel y, the presence of arterial signals indicates persistent viable tumor. Unfortunately, color Doppler is limited when the hepatocellular carci noma is hypovascular, small or deep. Echo-enhancing agents may help ov ercome these limitations, although spiral computed tomography or dynam ic magnetic resonance imaging cannot be replaced yet in the definitive assessment of tumor necrosis. Color and power Doppler are well-establ ished tools in the study of functioning thyroid and parathyroid adenom as after percutaneous ethanol injection. Echo-enhancing agents may imp rove Doppler sensitivity in the detection of residual viable tissue. O ther interesting applications of color and power Doppler in this field are secondary hyperparathyroidism and hyperfunctioning thyreopathies (Graves' disease) treated with mercaptoimidazole. The evaluation of sy stolic flow velocity in the inferior thyroid artery is more reliable t han the quantitative analysis of color signals in monitoring treatment response in Graves' disease. In our experience, systolic velocity in the inferior thyroid artery decreased from 150-250 to 60-80 cm/s after medical therapy. Finally, Doppler studies have provided good results in the follow-up of breast cancers after neoadjuvant therapy. In our e xperience on 18 patients treated with local parenteral repeated admini stration of antiblastic drugs, sonography showed no more signals withi n the lesion in 16 patients at the end of therapy. In the remaining tw o cases with persistent tumor at ultrasound, some color spots were sti ll present and histopathology confirmed residual tumor cells. In concl usion, the results of color and power Doppler are encouraging. Thus, w e believe that Doppler will be increasingly used in monitoring treatme nt response. (C) 1998 Elsevier Science Ireland Ltd. All rights reserve d.