From October 2017 to March 2018, consecutive patients referring to our academic medical centre for breast HHUS were asked to participate in this study. All consecutive females undergoing breast ultrasound were invited to undergo ABUS as an optional examination, regardless of the clinical indication for examination: adjunct screening tool in women with dense breast, follow-up of known benign breast lesions or preoperative assessment of histologically proven lesions.
The Ethics Committee of our hospital approved the research plan of the study on June 29, 2017. Informed written consent was obtained from all participants included in the study.
On the same day, patients who agreed to participate in the study underwent HHUS (iU22, Philips, Eindhoven, Netherlands or MyLab70 XVG, Esaote, Genoa, Italy) followed by ABUS examination (Invenia ABUS, GE Healthcare, Milwaukee, WI, USA). HHUS examinations were performed by one of the three breast dedicated radiologists with over 10 years of experience in breast ultrasound. HHUS includes the evaluation of the whole breast parenchyma bilaterally.
ABUS was performed by a trained radiographer and reviewed by one of the three breast dedicated radiologists that performed the HHUS.
ABUS examination was carried out with the patient lying in a supine position, with the breast flattened by the compression of a reverse curve transducer. Immediately before the acquisition, the probe was positioned on the breast (preparation phase) and then the probe moved to collect the images (acquisition phase). At least three views were acquired for each breast (anteroposterior, lateral, and medial), with an acquisition time of about 60 s each, with a total examination time of about 15 min.
Immediately after the execution of each examination (HHUS or ABUS), the patient’s experience was assessed using the modified testing morbidities index (TMI) for both techniques, with a self-administered questionnaire. TMI was obtained before giving the results to patients to avoid biases related to the results of the examinations. According to previous works [10,11,12], TMI is a validated instrument for the assessment of short-term life quality related to diagnostic testing. It was slightly modified for the purpose of our study. Nine attributes were assessed for both techniques: (a) pain or discomfort immediately before the test, (b) pain or discomfort during the test, (c) pain or discomfort after the test, (d) fear or anxiety immediately before the test, (e) fear or anxiety during the test, (f) physical function after testing, (g) mental function after testing, (h) embarrassment during the test, and (i) overall satisfaction.
The first seven attributes (a–g) were directly related to the examination, while the remaining two (h and i) were only indirectly related (or not necessarily related) to the examination, as already hypothesised by Tagliafico et al.  for the attribute (h).
Patients used a 5-point scale assessment for the seven attributes related to the examination (a–g) and to describe the level of embarrassment during the test, where 1, none; 2, mild; 3, moderate; 4, severe; and 5, extreme. Regarding physical and mental function after testing, the following scale was used: 1, no problems; 2, mild problems; 3, moderate problems; 4, severe problems; and 5, extreme problems. The questionnaire also included questions about the patient’s overall satisfaction, such as ‘the doctor explained what to expect during the exam’ and ‘the staff showed concern for my worries’. Patients assessed their overall satisfaction (i) by means of the following 4-point scale: 1, strongly agree; 2, somewhat agree; 3, somewhat disagree; and 4, strongly disagree. The lower is the given score, the better is the patient’s experience with the ultrasound examination.
The last question we asked the patients was to choose between ABUS and HHUS for a potential next breast examination.
Collected demographic and clinical data included age, personal history of breast pathology or previous breast biopsies and family history of breast cancer. Familiarity history and personal history were assessed as follows: 0, none, and 1, yes.
In order to compare the acceptance rate of these two ultrasound examinations, we considered the seven attributes strictly related to the examination (a–g); therefore, the TMI score of these seven items, for each patient, ranged from 7 (best possible experience) to 35 (worst possible experience).
Wilcoxon signed ranks test was used to compare categorical variables of ABUS and HHUS. Univariate and multivariate linear regression analyses were conducted to identify whether age, personal history or family history was an independent predictor of the TMI score. Age was reported as mean ± standard deviation, taking into consideration normal distribution, confirmed by D’Agostino-Pearson test (p = 0.881).
Statistical analysis was performed with SPSS software (IBM Corp., New York, NY; formerly SPSS Inc., Chicago, IL, United States). We considered p values lower than 0.050 as statistically significant to avoid the introduction of type I errors. Bonferroni’s correction was applied for multiple comparisons to the preset level of significance; the significance level was therefore p < 0.006 (0.050/9).