Study design, materials and methods
Female biological individuals aged 18 years or older were eligible for this study. Women who were pregnant, with difficulty understanding the proposed procedures, with a metallic implant and / or who had bariatric surgery were excluded. The study sample was made up of 21 participants.
It was performed a whole body scan for total body composition in a DXA device. The exam took place according to the following procedures: 1 - The participants were instructed to not perform any physical exercise in the 24 hours preceding the exam and to be at least 4 hours before the exam time; 2 – For the examination, the participants had to be wearing clothes that did not contain any type of metallic material (zipper or accessories); 3 - During the exam, the participants remained positioned supine and motionless on the equipment table according to the manufacturer's recommendations of DXA [1].
After collecting the images, an examiner, with 20 hours of practical training, performed the clipping and analysis of the pelvic region, region of interest (ROI) in this study (Figure 1). The ROI cut was performed in a polygon format as shown in Figure 1, so that it covered the entire pelvic region, following parameters:
I. Select the participant's exam.
II. Adjust the contrast of the image to highlighting the bone structures.
III. Boundary cutout edges:
1. Upper border superimposed on the iliac crests.
2. Edge juxtaposed to the right and left acetabulum.
3. Edge between the right and left ischial tuberosity and the coccyx.
At the end of the selected ROI analysis, the software of the DXA device provided data on bone mass (g), lean mass (g), fat mass (g) and% of pelvic region fat.
To determine intra-examiner reliability, the examiner performed the image analysis on 2 different days (day 1 and day 2) with an interval of 1 week. The variability of the measures was assessed using the coefficient of variation (CV), as requested by the International Society for Clinical Densitometry-ISCD (1). To analyze the intra-examiner intraclass correlations (ICC), the classification was used, in which an excellent ICC the values are ≥ 0.75, 0.40 ≤ ICC <0.75 a satisfactory result and ICC < 0.40 being weak. For all evaluations, a significance level of 5% was adopted [2].
Interpretation of results
The results of this study demonstrate that the measures of intra-reproducibility of the composition of the pelvis in DXA images, in women with different body mass index (BMI), were classified as excellent. The ICC values obtained in this study were high, which demonstrates proximity to the values measured at different times, indicating a great confidence in the method adopted [2].
In addition, we assessed the variability of intra-examiner measurements using the CV, as requested by the International Society for Clinical Densitometry-ISCD [1], to ensure that the measurements had a low error of low precision [1]. We obtained values in our study of less than 3% as recommended by the International Society for Clinical Densitometry [1].
The preliminary results presented in this study shows that images from DXA body composition scan can be used to specific evaluation from the pelvic region. It is known that symptoms of the lower urinary tract are related with great amount of adipose tissue in the pelvic region may develop [3]. This method, to measure the body composition of the pelvic region, may contribute to future research to analyze the consequences from increased fat mass in the pelvic region of women.