Evaluation of the FUSION-X-US-II prototype for combined performance of 3D automated breast ultrasound and tomosynthesis

Mammography is the only globally established pillar of breast cancer screening. Various options have been developed to improve the sensitivity and specificity of mammography. Tomosynthesis offers a way to reduce both the masking effect and the visualisation of pseudolesions due to overlapping tissue, thus improving sensitivity and specificity. The sensitivity of mammography is particularly reduced in women with dense breast tissue. Here, in addition to tomosynthesis, an additionally performed ultrasound can detect additional carcinomas. However, hand-held ultrasound (HHUS) has disadvantages that make its implementation in screening difficult. In addition to the increase in the false-positive rate, the disadvantages include in particular the dependence on the examiner, high duration and thus economic burden. Automated breast ultrasound (ABUS) offers a time-saving and automated way to record a 3D volume of the breast, which enables processing, reconstruction and reporting afterwards. ABUS can be performed by trained non-medical staff and is characterised here by its examiner independence. Similar results regarding carcinoma detection of HHUS and ABUS are described in the literature. Thus, the ABUS could be more suitable as a screening tool than the HHUS. First attempts to perform X-ray examinations and ABUS in one examination were already made in 1997. The current Fusion-X-US-II prototype (Siemens Healthcare GmbH, Forchheim, Germany) allows tomosynthesis and ABUS to be performed without changing the patient's position. It consists of the mammography unit Mammomat Inspiration and the ultrasound unit ACUSON S2000. The breast is compressed as usual and tomosynthesis is taken. Immediately afterwards, an ultrasound probe is inserted without changing the patient's position and the ABUS is performed. A compression paddle, which is suitable for both methods, makes it possible to perform both examinations directly afterwards. The aim of this study is to evaluate the clinical utility of the prototype, in particular the ability to detect malignant findings in the study population. In addition, the technical developments with regard to coverage, quality and examination duration are to be investigated. For this purpose, a preliminary study with 30 healthy female volunteers will be conducted in which only the ABUS unit of the prototype will be tested. In particular, the feasibility of the examination and the further development with regard to coverage and image quality will be examined. In the subsequent main study, the Fusion-X-US-II prototype will be examined in a carcinoma-enriched group of 101 patients. All patients will be included if they have an indication for tomosynthesis as part of a clarification of or second opinion on suspicious findings, provided that personnel and technical resources are available. All patients who have been pre-treated and in particular pre-operated on the corresponding breast will be excluded. The primary endpoint is the ability of the prototype to detect all malignant findings in the study population. The gold standard is the result of the overall diagnostic workup in the breast clinic of Heidelberg University Women's Hospital. Secondary endpoints are the coverage and quality of the ABUS as well as the examination and reporting time.