RESUMO
BACKGROUND: Several methods including water displacement, casting, the Grossman-Roudner measuring device, photographs, mammograms, ultrasound, and magnetic resonance imaging (MRI) have been proposed for the measurement of breast volume. The most cost-effective method has not been determined. METHODS: This study compared breast volume measurements using the Grossman-Roudner measuring device (a piece of circular plastic with a cut along a radius line), plaster casting, and MRI. The Grossman-Roudner measuring device was formed into a cone around the breast, and the volume was read from a graduated scale on the overlapping edges. The volume of the cast was measured using a butter-sand mixture and water displacement. The volume from the MRI slices was calculated using the ANALYZE bioimaging software. For five women with breast sizes AA, A, B, C, and D, the three volume measures were repeated three times. For a single volume measurement, the cost of the time and materials was 1 US dollar for the Grossman-Roudner cone, 20 US dollars for the cast, and 1,400 US dollars for the MRI. Using the mean and standard deviations of the measurements, a power analysis determined the number of subjects needed to detect a 5% change in volume. The number of subjects was multiplied by the price per test to determine relative cost. RESULTS: As compared with the cost for the Grossman-Roudner cone method, the cost for the volume measurements was 64 to 189 times more using the cast and 373 to 33,500 more using MRI. CONCLUSIONS: The Grossman-Roudner cone was clearly the most cost-effective method for determining breast volume changes in studies testing topical therapies to alter breast size.