A novel semi-robotized device for high-precision 18F-FDG-guided breast cancer biopsy.

PURPOSE: To assess the 3D geometric sampling accuracy of a new PET-guided system for breast cancer biopsy (BCB) from areas within the tumour with high 18F-FDG uptake. MATERIALS AND METHODS: In the context of the European Union project MammoCare, a prototype semi-robotic stereotactic prototype BCB-device was incorporated into a dedicated high resolution PET-detector for breast imaging. The system consists of 2 stacked rings, each containing 12 plane detectors, forming a dodecagon with a 186mm aperture for 3D reconstruction (1mm3 voxel). A vacuum-assisted biopsy needle attached to a robot-controlled arm was used. To test the accuracy of needle placement, the needle tip was labelled with 18F-FDG and positioned at 78 target coordinates distributed over a 35mm×24mm×28mm volume within the PET-detector field-of-view. At each position images were acquired from which the needle positioning accuracy was calculated. Additionally, phantom-based biopsy proofs, as well as MammoCare images of 5 breast cancer patients, were evaluated for the 3D automated locating of 18F-FDG uptake areas within the tumour. RESULTS: Needle positioning tests revealed an average accuracy of 0.5mm (range 0-1mm), 0.6mm (range 0-2mm), and 0.4mm (range 0-2mm) for the x/y/z-axes, respectively. Furthermore, the MammoCare system was able to visualize and locate small (<10mm) regions with high 18F-FDG uptake within the tumour suitable for PET-guided biopsy after being located by the 3D automated application. CONCLUSIONS: Accuracy testing demonstrated high-precision of this semi-automatic 3D PET-guided system for breast cancer core needle biopsy. Its clinical feasibility evaluation in breast cancer patients scheduled for neo-adjuvant chemotherapy will follow.

The hidden sentinel node in breast cancer: Reevaluating the role of SPECT/CT and tracer reinjection.

INTRODUCTION: Lymphoscintigraphy with planar imaging is considered a helpful tool to depict lymph node drainage in patients with invasive breast cancer. Single Photon Emission Computed Tomography with integrated CT (SPECT/CT) is usually performed to detect sentinel nodes (SN)s in breast cancer patients showing non-visualisation on lymphoscintigraphy. Incorporation of new SN indications (recurrent surgery, previous radiotherapy, or neo-adjuvant chemotherapy) has led to an increase of non-visualisation rates. The present study evaluates the contribution of SPECT/CT and tracer reinjection for SN-visualisation in breast cancer patients without drainage on lymphoscintigraphy. METHODS: Between 1st of July 2008 and 6th of November 2014 in total 1968 patients underwent a SN breast procedure, using intra-tumoural tracer administration. SPECT/CT was performed in 284 breast cancer patients with non-visualisation of SNs on lymphoscintigraphy. If SN non-visualisation persisted, a second radiotracer injection with repeated imaging was performed when logistics allowed this. Univariate analysis was applied to evaluate SPECT/CT visualisation rates in specific subgroups. RESULTS: The SPECT/CT visualisation rate was 23.2% (66/284). Univariate analysis revealed no significant subgroups influencing SPECT/CT visualisation. In patients receiving reinjection after persistent SPECT/CT non-visualisation the SN-visualisation rate reached 62.1% (36/58). Intraoperatively, the SN-identification rate using a gamma probe and blue dye was 87.9% (175/199) and 32.9% (28/85) for, respectively, primary and recurrent surgery after non-visualisation on lymphoscintigraphy. CONCLUSION: In this evaluation including new breast cancer SN indications, SPECT/CT scored lower than reinjection to visualise SNs in patients with non-visualisation on lymphoscintigraphy. Consequently, our institutional protocol has been readjusted.