Breast Cancer Diagnosis: First Clinical Results with ClearPEM-Sonic, the Multimodal Positron Emission Mammograph and Ultrasound Scanner

Introduction: Breast cancer is the most frequent cancer amongst women. X‐ray mammography and ultrasound (US) exam are used for screening and routine diagnosis. However, breast cancer diagnosis can be difficult in patients with dense breasts, breast implants or prior surgery. Breast MRI is the most sensitive modality, h owever, its low specificity could lead to unnecessary biopsies. A new nuclear medical technique dedicated to breast imaging emerged, positron emission mammography (PEM). Goals: We therefore design a multimodal system that provides co‐registered metabolic, anatomical and structural information: ClearPEM‐Sonic . It combines the ClearPEM, a high‐resolution PEM developed by the Crystal Clear Collaboration, with the SuperSonic Aixplorer, a 3D ultrasound (US) and elastography system. ClearPEM‐Sonic is installed at Hopital Nord, Marseille, FR, and coordinated by CERIMED, the European Center for Research in Medical Imaging . Methods and Materials: ClearPEM  ‐  ClearPEM is a positron emission tomograph dedicated to mammography, based on LYSO:Ce crystals grouped into two planar detector plates of 16.2 x 14.1 cm2, allowing measurement of the depth of interaction . SuperSonic Imagine Aixplorer The SuperSonic Imagine Aixplorer ultrasound system combines classic B‐mode ultrasound with shearwave elastography The probe used in ClearPEM‐Sonic acquires a 3D B‐mode and elastography volume. Multimodality: A position tracking system records the exact location and inclination of the US transducer and allows image co‐registration with PEM. Phantoms: We used Ultra Micro Hotspot Phantom to obtain ClearPEM image resolution. We made breast fantoms by means of gelatin and Agar mimicking breast tissue and cancerous lesions that can be visualized by US and PEM. Clinical evaluation: We report preliminary results about an ongoing phase one clinical trial with patients who have a proven breast cancer and were injected with 18F‐ Fluorodeoxyglucose for a whole‐body PET/CT exam. Gold standard was histology. Results: The spatial resolution is about 1,7mm. ClearPEM‐Sonic produced co‐ registered US/ClearPEM and elastography/ClearPEM images with a precision of 2mm in all three dimensions. We confirm that the machine can be used in clinical routine. We show that lesions detected with whole‐body PET/CT can be seen more precisely with ClearPEM‐Sonic. A limit exists for lesions close to the thoracic wall which could not be imaged if they are out of the field of view. Conclusion: We installed and commissioned the first innovating multimodal PEM and ultrasound scanner that performs well in its clinical environment. It is ready for further larger clinical trials where it will be compared to other modalities, including breast MRI.