8 female patients,
in two different sites (Ospedale Valduce,
Como,
Italy; Istituto Clinico S.
Anna,
Brescia,
Italy) underwent Mammography (5 patients),
Breast MRI (2 patients),
Breast MRI (1 patient) and US examination of breast and axilla (all the patients),
using a novel electromagnetically tracked technology for 2D Navigation,
that combines real-time US with pre-acquired DICOM images (BodyMap,
Esaote S.p.A.,
Genova,
Italy).
BodyMap technology was used to show the real-time position of the US probe with respect to any reference image tested: Mammography (axial and sagittal views),
MRI,
Breast Bodymark.
Breast phantom tests (both considering in vitro and ex vivo phantoms) were performed to assess technology accuracy and to evaluate and manage organ deformation.
Ex vivo phantom was obtained with a chicken breast wrapped in plastic film with some inclusions obtained by two olives with pit,
simulating lesions.
In vitro phantom was a CIRSE Model 073 Multi-modality breast biopsy and sonographic trainer phantom.
External markers were placed on in vitro and ex vivo phantoms,
in order to increase the number of geometrical landmarks needed for BodyMap registration (in vivo tests such markers were not needed due to the presence of natural reference points on the patient’s body).
For all the examinations an Esaote MyLabTwice US system (Esaote S.p.A.,
Genova Italy),
equipped with Virtual Navigation option,
allowing BodyMap real-time image fusion of Mammography (axial and sagittal views),
MRI and Breast Bodymark with 2D US scans,
was employed.
Moreover,
Esaote LA332 and LA533 Linear Array Probes (LA332 - Operating Bandwidth: 3-11 MHz; LA533 – Operating Bandwidth: 3-13 MHz; ) with different reusable tracking brackets with sensor mounted (CIVCO 639-031for LA332 and CIVCO 639-042 for LA533 - CIVCO Medical Solutions,
Kalona,
Iowa,
USA) were used.
LA332 probe has an array width of 40 mm and it was mainly used for deep scanning (useful for large breasts).
LA533,
53 mm array width was mainly used for small breast volumes acquisition and 2D US examination.
LA533 and LA332 probe have a dual possibility hand grip,
pinch grip and palmar grip (appleprobe design),
in order to provide a neutral wrist position while scanning.
This resource represented an additional operator’s comfort option during long examinations.
BodyMap real-time fusion imaging between Mammography (axial and sagittal views),
MRI and Breast Bodymark and 2D US data on the US system was possible thanks to an electromagnetic tracking system,
consisting of a transmitter on a fixed position and a small receiver mounted on the US probe through a dedicated support.
The transmitter,
whose position is considered the origin of the reference space system,
was kept steady by a proper support,
while the position and the orientation of the US probe in the created 3D
space is provided by the receiver unit.
The electromagnetic field source tip was oriented to point the target,
the subject’s breast,
in order to address the highest intensity and the most homogeneous area of the created electromagnetic field on the US scanning area.
The magnetic field produced by Virtual Navigator electromagnetic tracking system is stronger at the transmitter site and it fades with distance from the transmitter: the magnetic field is lower than the Earth’s magnetic field at a distance of 78 cm from the transmitter.
A non-metallic table was used to reduce as much as possible the interferences with the created electromagnetic field.