In this preliminary study, we could demonstrate that 3-D localization of SLNs is feasible using freehand SPECT technology. Prerequisites for acquisition of a good scan quality, most likely allowing precise SLN mapping, have been defined. This approach has high potential to allow image-guided biopsy and further standardization of SLN dissection, thus bringing 3-D nuclear imaging into the operating room.

Hybrid tracers that are both radioactive and fluorescent help extend the use of fluorescence-guided surgery to deeper structures. Such hybrid tracers facilitate preoperative surgical planning using (3D) scintigraphic images and enable synchronous intraoperative radio- and fluorescence guidance. Nevertheless, we previously found that improved orientation during laparoscopic surgery remains desirable. Here we illustrate how intraoperative navigation based on optical tracking of a fluorescence endoscope may help further improve the accuracy of hybrid surgical guidance. After feeding SPECT/CT images with an optical fiducial as a reference target to the navigation system, optical tracking could be used to position the tip of the fluorescence endoscope relative to the preoperative 3D imaging data. This hybrid navigation approach allowed us to accurately identify marker seeds in a phantom setup. The multispectral nature of the fluorescence endoscope enabled stepwise visualization of the two clinically approved fluorescent dyes, fluorescein and indocyanine green. In addition, the approach was used to navigate toward the prostate in a patient undergoing robot-assisted prostatectomy. Navigation of the tracked fluorescence endoscope toward the target identified on SPECT/CT resulted in real-time gradual visualization of the fluorescent signal in the prostate, thus providing an intraoperative confirmation of the navigation accuracy.

No abstract

With the introduction of the hybrid tracer indocyanine green (ICG)-99m Tc-nanocolloid, a direct relation between preoperative imaging and intraoperative fluorescence guidance was established. However, fluorescence guidance remains limited by its superficial nature. This study evaluated the feasibility of a nuclear medicinebased navigation concept that allowed intraoperative positioning of a fluorescence camera (FC) in the vicinity of preoperatively defined ICG-99m Tc-nanocolloid containing sentinel nodes (SNs). Methods: Five patients with penile cancer scheduled for SN biopsy were injected with ICG-99m Tc-nanocolloid followed by preoperative SPECT/CT imaging. The navigation device was used to provide a real-time augmented reality overlay of the SPECT/CT images and video output of the FC. This overlay was then used for FC navigation.

Abstract. Nuclear medicine imaging modalities assist commonly in surgical guidance given their functional nature. However, when used in the operating room they present limitations. Pre-operative tomographic 3D imaging can only serve as a vague guidance intra-operatively, due to movement, deformation and changes in anatomy since the time of imaging, while standard intra-operative nuclear measurements are limited to 1D or (in some cases) 2D images with no depth information. To resolve this problem we propose the synchronized acquisition of position, orientation and readings of gamma probes intra-operatively to reconstruct a 3D activity volume. In contrast to conventional emission tomography, here, in a first proof-of-concept, the reconstruction succeeds without requiring symmetry in the positions and angles of acquisition, which allows greater flexibility. We present our results in phantom experiments for sentinel node lymph node localization. The results indicate that 3D intra-operative nuclear images can be generated in such a setup up to an accuracy equivalent to conventional SPECT systems. This technology has the potential to advance standard procedures towards intra-operative 3D nuclear imaging and offers a novel approach for robust and precise localization of functional information to facilitate less invasive, image-guided surgery.

Objectives: This study aimed to provide long-term clinical data about an innovative epidermal radioisotope therapy called Rhenium-SCT V R (Skin Cancer Therapy) for non-melanoma skin cancer (NMSC), based on the use of the non-sealed beta emitter rhenium-188. Material and methods: 52 NMSC patients with a mean age of 71.7 years were treated with rhenium-188 skin cancer therapy between the years 2005 and 2014. An acryl matrix containing rhenium-188 was applied on a plastic foil covering the tumor. The treatment time for reaching a radiation dose of 50 Gy was calculated by a software program. Patients' characteristics and clinical follow-up data were collected and retrospectively analyzed. Results: Overall 55 lesions (32 BCC, 19 SCC, 2 M. Bowen and 2 extramammary Paget's disease (EMPD)) mainly in the head and neck region (72.3%) were treated. The average size of the irradiation area was 9.79 cm 2 and the mean treatment time 46.35 min. All lesions showed a complete remission after a follow-up period between 3 and more than 12 months. No complications or other post-interventional problems were reported. Conclusions: Rhenium-SCT V R is considered as an effective, rapid, safe, painless treatment mostly performed in a single therapeutic session, regardless of the shape complexity, anatomical site and number of lesions.

In this paper we present the usage of a drop-in gamma probe for intra-operative Single-Photon Emission Computed Tomography (SPECT) imaging in the scope of minimally invasive robot-assisted interventions. The probe is designed to be inserted and reside inside the abdominal cavity during the intervention. It is grasped during the procedure using a robotic laparoscopic gripper enabling full six degrees of freedom handling by the surgeon. We demonstrate the first deployment of the tracked probe for intra-operative in-patient robotic SPECT enabling augmented-reality image guidance. The hybrid mechanical- and image-based in-patient probe tracking is shown to have an accuracy of 0.2 mm. The overall system performance is evaluated and tested with a phantom for gynecological sentinel lymph node interventions and compared to ground-truth data yielding a mean reconstruction accuracy of 0.67 mm.

To our knowledge this is the first study demonstrating the feasibility of intraoperative navigation based on preoperatively acquired 3-dimensional single photon emission computerized tomography/computerized tomography images. Although confirmation of successful target localization (eg using γ tracing or fluorescence imaging) remains indispensable, this opens the way to translate 3-dimensional functional imaging data to the operating room.