The influence of technical factors on sonoelastographic assessment of solid breast nodules

The aim of the study was to assess the influence of technical factors and/or lesion characteristics on the final elastographic score in solid breast nodules.

Patients with solid breast masses examined between May 2007 and May 2008 in the Radiology Department of Cluj District University Hospital were included in the study. All lesions were examined with conventional ultrasound, Doppler ultrasound and sonoelastography, according to a preset protocol. The influence of the following factors on the elastographic score was evaluated: type of section (sagittal versus transverse); size of region of interest (small versus large); amplitude and frequency of movement; initial compression (light versus strong); angulation (perpendicular versus angulated transducer); characteristics of the lesion (size and location). The reference diagnosis was the histopathology diagnosis and, in twenty cases, short-term follow-up.

Ninety-two patients with a mean age of 48.11 years and 101 breast nodules were included in the study. The overall sensitivity and specificity for elastography were 79 % [68-88 %] and 79 % [65 - 89 %], respectively, with a negative predictive value of 74 % [60-85 %] and a positive predictive value of 84 % [72-91 %]. The following factors did not influence the elastographic score: type of section (scores on transverse and longitudinal section, Z = -0.641, p = 0.552); the amplitude and frequency of movements during the elastographic examination (Cochran's Q concordance = 0.706, p = 0.872); strong initial compression in the case of benign nodules (Z = 0.000, p = 1.000); size of the lesions. Of the elastographically benign nodules, 9 were false negative and of the 46 elastographically malignant nodules, 12 were false positive. The following factors influenced the elastographic scores: size of the region of interest (the scores were significantly different when small or large region of interest was used, Z = -0.671, p < 0.0001); transducer angulation (Z = -5.42, p < 0.0001); strong initial compression in the case of malignant nodules (Z = -6.044, p < 0.0001) and the location of the mass in the vicinity of the chest wall.

The most important factors that influence the final elastographic score, leading to false negative results, are the size of the region of interest, the initial compression and angulation of the transducer, while the frequency and amplitude of movement during the examination proved to be of no importance as long as the images were obtained within a range of assessment usefulness. Changing the scanning parameters never led to false positive results in the case of malignant breast masses.