Introduction: The calculation and presentation of activity in a given volume of tissue or lesion, expressed by selected unit of measure (eg Bq/ml) is named data quantification. With the advent of more advanced and modern devices and techniques, it is possible to calculate the quantification by planar scintigrams as well as tomographic (SPECT/CT) data acquisition. Beacuse a fully accurate quantification can not be reliably determined, the question is do these two methods of data quantification are comparable to each other. Purpose: Main purpose of the research was to compare the results of the planar scan based and SPECT/CT based technique of activity quantification. In addition, purpose was to determine the potential impact of different patient based or acquisition dependent variables. Methods: The retrospective study included analysis of 89 osteoblastic skeletal lesions in 65 patients who had planar whole body bone scintigraphy and regional SPECT/CT performed. The activity in lesions on planar images was calculated according to the standard procedure used at the Department of Nuclear Medicine in Institute of Oncology Ljubljana. The commercially available SPECT/CT Q.Metrix quantification software (GE Healthcare inc.) was used to calculate quantification in SPECT/CT data. Several variables were analyzed too: patient's gender, age, body mass index, injected activity, time between application of radiopharmaceutical and the beginning of data acquisition, time between planar and SPECT data acquisition. All obtained data were adequately statistically analyzed. Results: The difference between two quantification methods was statistically significant (p⡤0,001). There was a strong linear correlation between both quantification methods (the Pearson correlation value was 0,937). Based on linear regression analysis, we defined the model (R2=0,88) to predict the result of one method of quantification using the result of the second method. Tested variables didn't have statistically significant impact on each of the quantification methods. Discussion and conclusion: The results from this study show that the two methods of data quantification are comparable to each other. The results of our research are a good starting point for further researches and reflections.
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