Study First Step to Virtual Breast Cancer Localization
Study First Step to Virtual Breast Cancer Localization
Radioisotopic and wire localizations suffer from several limitations. These techniques add
 another procedure prior to surgery, can be uncomfortable and entail additional cost.

 The aim is to develop a novel technique of breast tumor localization using preoperative
 magnetic resonance imaging (MRI) and breast optical scanning.

 Patients with diagnosis of breast cancer who have had a preoperative MRI and 3D optical scans
 are included.

 Optical scanning is done preoperatively and intraoperatively after tumor localization was
 marked on the breast using radioisotopic technique.

 The MRI is then adjusted with the intraoperative optical scan to match the breast position at
 the time of surgery.

 The investigators evaluate the efficiency for localization of breast lesion of the novel
 technique by comparison with radiosiotopic technique.
Breast cancer is the most commonly cancer diagnosed among women, with approximately 42000
 women diagnosed with breast cancer annually in France. Incidence rates of breast cancer rose
 steadily from 1980 to 2005 due to the increasing use of screening mammography and longer life
 expectancy.

 With advances in breast cancer screening techniques, many women now have malignant tumors
 detected before they become clinically palpable. For these women, breast conserving surgery
 (BCS) has become the preferred treatment option, comprising more than 75 % of surgeries in
 most breast cancer centers. The goal of BCS is to resect the tumor with a surrounding margin
 of tissue free of cancer while simultaneously preserving the overall shape and appearance of
 the breast. For non palpable lesions, localization of the tumor prior to surgery is needed.
 The standard technique for such patients is wire localization. Wire localization suffers from
 several limitations. It adds another procedure prior to surgery, complicating and lengthening
 the process. It can be uncomfortable for the patient and entails additional cost. This
 technique requires the surgeon to estimate the 3-dimensional (3D) position of the cancer from
 2-dimensional mammography images. Wire localized excision results in positive margins
 approximately 30-50 % of the time. These cases require additional surgery to remove the
 remaining cancer, which is both costly and emotionally difficult for patients.

 Alternatives to wire localization have been tested. Radioguided occult lesion localization
 (ROLL) has been shown to be superior to wire localization with shorter risk having positive
 resection margins and shorter duration of localization and surgical excision.

 Magnetic resonance imaging of the breast has been shown to be more sensitive than ultrasound
 or mammography for the detection of cancer. Despite this evidence, the use of MRI has not
 been demonstrated to produce better short-term outcomes: the prospective randomized COMICE
 trial failed to demonstrate a decrease in the positive margin rate and need for re-excision
 with the use of preoperative prone MRI. The COMICE study authors recognized that the
 inability of prone MRI to result in decreased positive margin rates might be due to the way
 the imaging data is presented to the surgeon, stating that ''techniques to ensure surgical
 precision is at an optimum need further examination.'' The shape of the breast during prone
 MR imaging (with the breast pendant in a bilateral imaging coil) is radically different from
 the supine, arm-extended position in the operating room (OR). Supine MRI more accurately
 replicates the surgical position. Indeed, a study by Sakakibara et al. randomized patients
 with DCIS to undergo wire localized or supine MRI- guided BCS and found the positive margin
 rate and resected tissue volume were lower in patients undergoing supine MRI-guided excision.

 The aim is to develop a novel technique of MRI- guided breast tumor localization that
 incorporates preoperative prone MRI and uses a preoperative and intraoperative 3D optical
 scans to adjust the MRI image to the exact position in the operating room. This novel
 technique will provide the surgeons with 3D views and measurements of tumor shape and
 position within the breast as it appears during surgery.

 METHODS

 1. Data collection Data are obtained from the database of the gynecologic department of the
 Montpellier University Hospital, using the Medicalization Program of the Information
 Systems. The patient who have had a BCS for breast cancer between 2016 and 2017 are
 selected. The investigator then include consecutively 10 patients who have had a
 preoperative MRI and a preoperative and intraoperative 3D optical scan of the chest and
 who meet eligibility criteria. A subject identification code is assigned by the
 investigator to each subject to anonymized the data. A subject identification code list
 allows the investigator to keep a confidential list of names of all the patients
 included in the study on the protected central computer server of Montpellier University
 Hospital.

 1.1.Clinical data The source of clinical medical data is the patient's electronic
 medical record. The data recorded by the investigator include name, surname and date of
 birth of the patient, cup size, date of MRI, breast cancer localization, date of
 preoperative 3D optical scan, date of date of surgical procedure.

 1.2.Optical scans Since 2016, in the gynecology department of Montpellier University
 Hospital, photographs of the chest are taken for each patient who undergoes a BCS.
 Preoperative, intraoperative and postoperative 3D optical scans are also done. Optical
 scanning are obtained with the sensor structure 3D scanning. Acquisitions take few
 minutes. Preoperatively and postoperatively, patients are on standing position, arms
 abducted 45° with anatomical landmarks marked on the surface of the skin (manubrium of
 sternum, xiphoid process, top edge of the mammary gland, submammary fold).
 Intraoperatively, the tumor is localized by radioguided occult lesion localization and
 is marked on the surface of the breast. Two acquisitions are taken, before and after the
 tumor has been localized, with patients placed on the supine position, arms abducted
 90°.

 1.3.Preoperative breast MRI The standard breast MRI protocol includes T2 sequences
 (anatomy and signal analysis), T1 gradient-echo sequences and injected dynamic 3D
 sequences (gadolinium-containing contrast agent). Patients are placed on the prone
 position, arms above the head, with both breasts hanging in the coil loops. MRI data are
 collected from the computer server of radiology department, anonymized with the subject
 identification code and then burned to CD. Digital Imaging and Communication in Medicine
 (DICOM) data are converted into MHD format.

 2. different steps to create a 3D personalized breast model 2.1. 3D reconstruction of MRI
 data The 3D reconstruction requires the segmentation of the anatomical elements within
 the 2D images. Segmentation is done using a computer software called Medical Image
 Segmentation Tool (MIST) which allows semi-automatic and manual segmentation of the
 following elements: tumor, mammary gland, sternum, skin, pectoralis major and minor
 muscles. The 3D reconstruction is then performed by an indirect volume rendering method,
 the marching cubes. Instant Mesh software is then used for post-processing.

 2.2.Registration of 3D reconstruction to optical scans Image registration is the process
 of transforming different sets of data into one coordinate system. The registration
 problem is to find the optimal spatial transformation that matches the images. The
 benefits of using multimodal data have created a need for the development of highly
 accurate and robust multimodal image registration.

 Anatoreg, a software designed by Anatoscope, allows registration of a reference model to
 a target. In our study, the reference model is the 3D reconstruction obtained from
 breast MRI. 3D reconstruction data are included in a Sofa Modelling Language (SML) file
 to be read by the registration software. The target is the optical scan, previously
 processed thanks to Blender (artefacts removal, axis correction, correction of unit of
 measurement).

 The first step of registration is the Interaction Closest Point algorithm (ICP). The ICP
 algorithm searches for the closest point in the reference surface for each point in the
 target surface without any restrictions. The second step is the use of landmarks to
 improve the registration.

 3. Evaluation of the 3D breast model Tumor localization by this 3D breast model is then
 compared to the localization by ROLL. The intraoperative 3D optical scan gives us the
 tumor localization obtained by radioguided occult lesion localization thanks to pen
 marking left by the surgeon. The novel technique gives us a 3D model and the
 localization of the tumor visible by transparency. Comparison is done by superimposing
 both acquisitions.
Inclusion criteria:

 -  diagnosis of breast cancer by core needle bipsy

 -  aged 18 years or more

 -  who had a preoperative magnetic resonance imaging

 -  who had a preoperative 3D optical scan

 -  who had two intraoperative optical scans (with and without pen marking for tumor
 localisation

 -  who had a preoperative radioguided occult lesion localization

 -  who had a breast conservation surgery

 -  not opposed to the use of their personal health data.

 Exclusion criteria:

 -  patients aged under 18

 -  requiring tutorship or guardianship

 -  who had neoadjuvant therapy.