SIZE QUANTIFICATION OF LIVER METASTASES IN PATIENTS UNDERGOING CANCER-TREATMENT - REPRODUCIBILITY OF ONE-, 2-DIMENSIONAL, AND 3-DIMENSIONALMEASUREMENTS DETERMINED WITH SPIRAL CT

PURPOSE: To assess the reproducibility of one-, two-, and three-dimens ional measurements of the size of liver metastases. MATERIALS AND METH ODS: The sizes of 10 liver metastases were determined 200 times: Ten o bservers measured each lesion by using images obtained at two differen t CT studies and with five different measurement techniques (maximum d iameter, product of diameters, area, volume, and product of three diam eters). They repeated each measurement in a separate session. The infl uence of measurement technique and lesion type (size and morphologic a ppearance) on measurement reproducibility was assessed. RESULTS: Three -dimensional measurements proved to be as reproducible as one- and two -dimensional measurements. Measurement reproducibility was influenced mainly by the size (P < .0001) and morphologic appearance (P < .01) of the lesions. CONCLUSION: Three-dimensional size measurements obtained with spiral CT are reproducible and could therefore replace the two-d imensional measurements of tumor size currently obtained with follow-u p CT studies.