Fusion of freehand SPECT and ultrasound: First experience in preoperative localization of sentinel lymph nodes.

PURPOSE: Radioguided sentinel lymph node biopsy (SLNB) is the standard of care in breast cancer and melanoma. Additional preoperative Single-photon emission computed tomography (SPECT/CT) for improved anatomical co-registration of the SLNs causes additional radiation exposure and is time-consuming and expensive. The aim of this prospective study was to evaluate a novel approach involving real-time fusion of freehand SPECT (fhSPECT) and ultrasound (US) for anatomical co-registration of SLNs. METHODS: From February 2015 to February 2016, 153 patients were included in this prospective study. All patients underwent lymphoscintigraphy according to practical guidelines and 151 (118 cases of breast cancer, 30 cutaneous malignancies, and three cases of vulvar cancer) of the 153 patients were additionally investigated with fhSPECT-US. FhSPECT connected to a hand-held gamma detector generates three-dimensional images of the radioactivity distribution in the scanned area. For co-registration and real-time fusion of fhSPECT and subsequently performed US, an infrared stereo tracking system was used. RESULTS: In all patients an SLN was found on lymphoscintigraphy, and the fhSPECT detected corresponding hotspots in all but one patient. In 72 % of patients and 73 % of lymph node basins, real-time anatomical co-registration with US was feasible. The rate of success in achieving good co-registration increased from 60 to 75 % after training by a radiologist specialized in breast imaging. A higher co-registration rate (78 %) was observed in patients with only one SLN than in those with two SLNs (68 %) or three or more SLNs (0 %). CONCLUSIONS: Real-time fusion of fhSPECT and US for preoperative anatomical co-registration of SLNs is feasible. However, before this approach can completely replace preoperative lymphatic imaging, further technical developments are needed.

Intraoperative radio-guided localization of parathyroid adenomas using 3D freehand SPECT technology.

Parathyroidectomy for primary hyperparathyroidism (PHPT) could have poor outcomes, even with accurate preoperative localization of the adenomas, because their intraoperative localization can be challenging. Freehand single photon emission computed tomography (fhSPECT) is a new technique for radio-guided intraoperative navigation. Its use during parathyroidectomy could be useful and such data are limited. We herein present our experience on the feasibility of fhSPECT for intraoperative detection of abnormal parathyroid glands. We retrospectively reviewed the clinical data of 55 patients (30-77 years old) with PHPT due to parathyroid adenomas, that were subjected to parathyroidectomy from 12/2017 to 7/2022. In average, 111 ± 74 MBq of Tc-99 m Sestamibi were injected intravenously, approximately 2 h before the operation and fhSPECT was used to generate 3D images during parathyroidectomy. Measurements of PTH and calcium levels were performed preoperatively, postoperatively and 4-6 months after the procedure. FhSPECT successfully identified the parathyroid adenoma in all the patients. It took 3 min (median time) for fhSPECT to detect at least one radioactive spot in all patients. The mean duration of the operation was 66.6 ± 7.3 min. Forty-nine patients out of 55 had solitary and 6/55 had multiple adenomas, whereas 6/55 had ectopic abnormal parathyroid glands. None of the patients had persistent hyperparathyroidism during follow-up. To the best of our knowledge, this is the largest series of patients with PHPT that underwent fhSPECT assisted parathyroidectomy. Our data suggest that this navigation system is helpful in identifying parathyroid adenomas intraoperatively.

Concordance between freehand SPECT and conventional scintigraphy for sentinel lymph node detection in breast cancer.

INTRODUCTION: Freehand SPECT can be a useful imaging technique for preoperative planning of sentinel lymph node biopsy (SLNB) as it allows localization of the sentinel node by 3D and real-time tomographic imaging and determines its depth after a few minutes of scanning. The aim of the study was to evaluate the correlation between the number of detected SNs between freehand SPECT images and lymphoscintigraphy (LS). MATERIALS AND METHODS: 100 patients with a diagnosis of invasive breast cancer and no clinical evidence of lymph node involvement prospectively underwent SLNB. The preoperative study included freehand SPECT imaging at 15min after injection and LS imaging at 25 and 60-90min after injection (early and late). The observed agreement was analyzed and a concordance study was performed between the number of SNs detected with freehand SPECT and LS. RESULTS: The observed agreement in the detection of SNs between freehand SPECT and early LS was 72%; between freehand SPECT and late LS was 85%; and between early and late LS was 87%. In the concordance study, there was moderate concordance between freehand SPECT and early LS (kappa coefficient: 0.42); moderate-high concordance between freehand SPECT and late LS (kappa coefficient: 0.60); and moderate-high concordance between early and late LS (kappa coefficient: 0.70), with no significant differences between them (p-value=0.16). CONCLUSION: Freehand SPECT showed a moderate-high concordance with conventional imaging studies and could be a valid alternative for the presurgical study of SLNB in breast cancer.

Intraoperative freehand SPECT as an alternative imaging technique for use in radioguided parathyroidectomy.

Freehand single photon emission computed tomography (fhSPECT) is a technique that is used to monitor body's radioactivity intraoperatively. Accordingly, in this study, the feasibility of using fhSPECT for intraoperative 3D mapping in radioguided parathyroidectomy has been assessed. Patients, who were diagnosed with primary hyperparathyroidism consecutively, were scanned intraoperatively using fhSPECT to locate parathyroid adenomas before surgical procedure. The fhSPECT images were acquired intraoperatively using a declipse®SPECT device (SurgicEyeTM). The fhSPECT protocol could not be completed due to the technical problems in one patient. Parathyroid adenoma was located in the first patient with no lateral deviation. Nevertheless, a deviation of 8 mm was detected in the depth of the parathyroid adenoma, which is the distance of parathyroid adenoma from the skin. A 20 mm lateral deviation and a 10 mm deviation in depth were detected in the second patient. In the third patient, as was the case in the first patient, parathyroid adenoma was located with no lateral deviation. However, there was a 15 mm deviation in the depth of the parathyroid adenoma. A 5 mm lateral deviation was detected in the fourth patient yet with no deviation in the depth of parathyroid adenoma. Finally, neither lateral nor vertical deviation was detected in fifth patient. Based on the findings of this study, it was concluded that the fhSPECT technology can be helpful to a certain degree in locating the parathyroid adenoma. However, further studies are needed to support the findings of this preliminary study.

Study on intraoperative localization of sentinel lymph nodes using freehand SPECT in breast cancer patients.

Introduction: The diagnostic and therapeutic approach to axillary lymph nodes is considered indispensable in the treatment of breast cancer patients. Aim: To investigate the effectiveness of 3D freehand SPECT (fhSPECT) in sentinel lymph node (SLN) mapping in breast cancer, compared with the use of a conventional gamma probe. Material and methods: We retrospectively compared the fhSPECT lymph node mapping modality, with gamma probe detection in early-stage, clinically node-negative breast cancer patients, with biopsy-confirmed malignancy. The two techniques were compared based on the average number of LNs excised per axilla. The duration of SLN mapping was also compared between the two groups. The performance of the two methods on obese and post-systemic therapy patients was evaluated. FhSPECT was used in 150 cases, while the gamma probe was employed in 50 cases. Results: FhSPECT detected at least 3 nodes in 83.3% of the patients vs. 72.0% with the γ-probe (p = 0.107). The mean number of SLNs excised per axilla was 3.66 using the γ-probe and 4.18 with fhSPECT (p = 0.03). The average surgical time was 39 ±7 min with the γ-probe and 37.54 ±17 min with fhSPECT (p = 0.228). Sentinel lymph node biopsy (SLNB) mean surgical time evolved from 40.2 ±20.77 min to 32.35 ±10.46 min (p = 0.033). In obese patients, a reduction in surgical times was noted from 45.5 ±3.09 min to 44.04 ±20.9 (p = 0.27), in addition to a significant increase in average LN detection in the fhSPECT group (4.26 ±1.44) compared to the γ-probe group (3.2 ±1.65) (p = 0.043). Conclusions: The use of the fhSPECT modality is effective and safe, and, when compared to the γ-probe, has significant advantages in SLN mapping.

Evaluation of camera-based freehand SPECT in preoperative sentinel lymph node mapping for melanoma patients.

BACKGROUND: Assessment of lymphatic status via sentinel lymph node (SLN) biopsy is an integral and crucial part of melanoma surgical oncology. The most common technique for sentinel node mapping is preoperative planar scintigraphy of an injected gamma-emitting lymphatic tracer followed by intraoperative node localization using a non-imaging gamma probe with auditory feedback. In recent years, intraoperative visualization of SLNs in 3D has become possible by coupling the probe to an external system capable of tracking its location and orientation as it is read out, thereby enabling computation of the 3D distribution of the tracer (freehand SPECT). In this project, the non-imaging probe of the fhSPECT system was replaced by a unique handheld gamma camera containing an array of sodium iodide crystals optically coupled to an array of silicon photomultipliers (SiPMs). A feasibility study was performed in which preoperative SLN mapping was performed using camera fhSPECT and the number of detected nodes was compared to that visualized by lymphoscintigraphy, probe fhSPECT, and to the number ultimately excised under non-imaging probe guidance. RESULTS: Among five subjects, SLNs were detected in nine lymphatic basins, with one to five SLNs detected per basin. A basin-by-basin comparison showed that the number of SLNs detected using camera fhSPECT exceeded that using lymphoscintigraphy and probe fhSPECT in seven of nine basins and five of five basins, respectively. (Probe fhSPECT scans were not performed for four basins.) It exceeded the number excised under non-imaging probe guidance for seven of nine basins and equaled the number excised for the other two basins. CONCLUSIONS: Freehand SPECT using a prototype SiPM-based gamma camera demonstrates high sensitivity for detection of SLNs in a preoperative setting. Camera fhSPECT is a potential means for efficiently obtaining real-time 3D activity distribution maps in applications such as image-guided percutaneous biopsy, and surgical SLN biopsy or radioguided tumor excision.

Multimodal approach in radioguided surgery in a case of multiple paraganglioma. / Abordaje multimodal en la cirugía radioguiada de un caso de paraganglioma múltiple.

The case involves a 34-year-old woman who underwent surgical removal of a retroperitoneal paraganglioma adjacent to the left kidney's lower pole, previously visualized by CT and MRI. The 123I-MIBG scan was positive for this lesion and, in addition, another uptake was observed located caudally at the level of L5 and of smaller size and less intensity. The second lesion was not considered for surgical removal, due to its lack of morphological definition. One week after surgical intervention, the patient presented difficult-to-control high blood pressure. A second 123I-MIBG scan was performed. The previously described second image was more intense in this study, and surgery was planned to remove it. A combination of techniques including freehand-SPECT and a portable hybrid gamma camera (with optical camera) were used pre-operatively to identify the location of the lesion. The combination of intra-operative laparoscopic gamma probe and portable hybrid gamma camera enabled the tumor to be located, excised, and its complete removal to be monitored. The histopathology analysis confirmed a second paraganglioma.

Intraoperative sentinel node imaging versus SPECT/CT in oral cancer - A blinded comparison.

INTRODUCTION: Sentinel node biopsy (SNB) is gaining popularity as a staging tool in oral cancer. Protocol mandates radiotracer injection and pre-operative imaging (LSG ±â€¯SPECT/CT) in the nuclear medicine department. This approach limits application to accessible tumours and to centres with nuclear medicine. New technology, freehand single photon emission computed tomography (fhSPECT), has proved a useful adjunct in intraoperative imaging and localisation of sentinel nodes. This study investigates fhSPECT as an alternative to traditional imaging, an approach that would widen the remit of SNB. METHODS: Fifty consecutive cT1-T2 N0 oral cancer patients received radiotracer followed by lymphoscintigraphy and SPECT/CT. Surgery was undertaken using fhSPECT by a surgeon blinded to pre-operative imaging. Prior to biopsy completion, results of pre-operative imaging were reviewed and any additional nodes removed. The accuracy of LSG, SPECT/CT and fhSPECT were compared. RESULTS: Nineteen patients had positive sentinel nodes. Disease free survival for sentinel node positive versus negative was significant (p < 0.005). All modalities missed positive nodes in at least one patient. The false negative rate for lymphoscintigraphy, SPECT/CT and fhSPECT was 26.3%, 15.8% and 5.3% respectively. DISCUSSION: These data show a surgeon naïve to the results of traditional pre-operative sentinel node imaging can use fhSPECT in the operating theatre to accurately locate sentinel nodes in oral cancer. Freehand SPECT showed excellent sensitivity and a low false negative rate offering the possibility of a streamlined intraoperative sentinel node protocol.

Surgical guidance by freehand SPECT for sentinel lymph node biopsy in early stage breast cancer: A preliminary study.

OBJECTIVE: Sentinel lymph node biopsy (SLNB) is a standard for patients with early breast cancer. Using a gamma-detecting probe connected to an infrared camera, the Declipse freehand SPECT (FhSPECT) system (Surgiceye(®)) is able to detect and locate any radioactive source in 3D. The objective of this study was to evaluate the potential interest of FhSPECT imaging for real-time guidance SLNB in breast cancer. METHODS: A prospective single-center clinical study assessed sensitivity and usability of FhSPECT for SLN detection and surgical guidance in breast cancer patients. SLN detection rate with FhSPECT was compared with lymphoscintigraphy (LS) and colorimetric method. Durations of FhSPECT acquisitions and of the SLNB procedure were measured in order to evaluate the practicability of the device. RESULTS: Between May and September 2014, 20 patients with early stage invasive breast cancer (cT0-2N0) underwent SLNB using FhSPECT and blue dye detection. Preoperative LS revealed 41 radioactive axillary SLNs (median=2 SLN per patient; range 0-4) in 20 patients. Preoperative FhSPECT detected 40 axillary SLNs (median=2; range: 1-4) in 20 patients. The corresponding sensitivity of FhSPECT was 97.5%. For 4 patients (20%), FhSPECT detected more axillary SLNs than LS. The colorimetric method identified only 24 axillary SLNs (2 patients had no blue dye injection on account of a history of allergy), leading to a sensitivity of 67% (24 blue SLNs/36 resected SLNs after blue dye injection). Median duration of FhSPECT acquisitions was 5minutes (range: 1-26min). Median duration of SLNB procedure was 11.5minutes (range: 3-55min). Duration of acquisitions analysis based on the number of use of the device showed decreasing values suggesting the existence of a short learning curve. CONCLUSION: This study demonstrated that FhSPECT is feasible and facilitates SLN identification.

3D scintigraphic imaging and navigation in radioguided surgery: freehand SPECT technology and its clinical applications.

Freehand SPECT (fhSPECT) is a technology platform for providing 3-dimensional (3D) navigation for radioguided surgical procedures, such as sentinel lymph node (SLN) biopsy (SLNB). In addition to the information provided by conventional handheld gamma detection probes, fhSPECT allows for direct visualization of the distribution of radioactivity in any given region of interest, allowing for improved navigation to radioactive target lesions and providing accurate lesion depth measurements. Herein, we will review the currently available clinical data on the use of fhSPECT: (i) for SLNB of various malignancies, including difficult-to-detect SLNs, and (ii) for radioguided localization of solid tumors. Moreover, the combination of fhSPECT with other technologies (e.g., small field-of-view gamma cameras, and diagnostic ultrasound) is discussed. These technical advances have the potential to greatly expand the clinical application of radioguided surgery in the future.

Evaluation of the use of freehand SPECT for sentinel node biopsy in early stage oral carcinoma.

RATIONALE: Inadequate intraoperative visualization of the sentinel node can hamper its harvest. Freehand SPECT is a 3D tomographic imaging modality based on the concepts of SPECT, which can be used for intraoperative visualization and navigation towards the sentinel node in order to improve its localization and removal during surgery. PATIENTS AND METHODS: The use of freehand SPECT was evaluated during 66 sentinel node biopsy procedures in early stage oral cancer patients. Intraoperative detection of sentinel nodes was compared with preoperative identified sentinel nodes on lymphoscinitigraphic examination. Additional value of freehand SPECT was subjectively scored by the surgeon directly following the biopsy procedure. RESULTS: Freehand SPECT was able to detect 94% of sentinel nodes intraoperatively. Most sentinel nodes not detected (7 out of 9) were located in level I of the neck. Freehand SPECT appeared to be of additional value for facilitating the intraoperative detection of the sentinel node in 24% of procedures. CONCLUSION: The use of the freehand SPECT system is feasible in the intraoperative detection of sentinel nodes in early stage oral cancer. Freehand SPECT provides helpful information facilitating the SN biopsy procedure in a quarter of cases. However, freehand SPECT cannot detect all SNs which are located in the vicinity of the injection site.

[Freehand SPECT for navigation and sentinel node detection in breast cancer]. / Intérêt du repérage per-opératoire 3D des ganglions sentinelles dans le cancer du sein.

The sentinel lymph node (SLN) is a standard for the surgical treatment of axillary localized breast cancer N0. It is based on a double isotopic and color detection. With a gamma detecting probe connected to an infrared camera, Déclipse SPECT system (Surgiceye(®)) is able to detect and locate any radioactive source in 3D. Mobile character for use in the operating room is particularly interesting for the intraoperative detection of SLN. We illustrate its usefulness in a clinical case where the preoperative identification of SLN by lymphoscintigraphy was not informative.

[Initial experience in intraoperative radiolocalization of the parathyroid adenoma with freehand SPECT and comparative assessment with portable gamma-camera]. / Experiencia inicial en la radiolocalización intraoperatoria del adenoma paratiroideo con freehand SPECT y valoración comparativa con gammacámara portátil.

Initial experience is presented by using freehand SPECT in the intraoperative radiolocalization of a parathyroid adenoma in 2 patients, one which was mediastinal. There is only one previous publication including 3 patients with parathyroid adenomas in usual parathyroid localizations. We also report for the first time a comparative assessment of results with portable gammacamera during the same surgery. In the operating room, we obtained images with portable gamma-camera and 3 D reconstruction with freehand SPECT from 15 min after iv injection of 5 mCi of (99m)Tc-MIBI. Both devices enabled the 2 adenomas to be detected intraoperatively, as well as checking activity of the excised gland and absence of significant uptake in surgical bed, with confirmation by intraoperative pre-postsurgical PTH levels, pathology and clinical follow-up for 10 months. Both devices accurately located the parathyroid adenomas intraoperatively, as well as confirmation of their extirpation, but freehand SPECT provided additional information of adenoma depth (mm) from the skin border, very useful for minimally invasive radio-guided surgery.

Real-time ultrasound and freehand-SPECT. Experiences with sentinel lymph node mapping.

UNLABELLED: Aim of this work is to report first experiences of the feasibility and applicability of a hybrid freehandSPECT/ultrasound (fh-SPECT/US) imaging concept, with regard to SLN imaging, in patients with breast cancer and malignant melanoma. PATIENTS, METHODS: 18 patients with breast cancer or malignant melanoma received standard SLN scintigraphy. Following this, fh-SPECT using declipse®SPECT (SurgicEye, Munich, Germany) was performed, a handheld-gamma camera-based method to visualize activity distribution within a region of interest as a cross-sectional data set. These data were transferred to an ultrasound device and sensor-navigated ultrasound was performed combining fh-SPECT data with ultrasound images, displaying superimposed images. Quality of fh-SPECT and co-registration accuracy was assigned to one of four categories and occurrence of artefacts was assessed. RESULTS: In 4/18 examinations, there was a no deviation regarding co-registration of both data sets. For 9/18 patients, there was a deviation of <1 cm (mean 0.7±0.3 cm, range 0.3-1.0 cm). For 3/18 patients, a deviation >1 cm was present (mean 1.7±0.3 cm, range 1.5-2.0 cm). In 2/18 examinations no lymph node was found in the region of highest activity. Fh-SPECT reconstruction artifacts occurred in 6/18 examinations. CONCLUSION: The fusion imaging concept combining SLN information with ultrasound images presented here proves to be feasible and technically successful. However, significant technical limitations were shown in fh-SPECT quality and fusion precision. Subject to technical optimisation of SPECT quality and co-registration, a meaningful contribution to the preoperative planning of lymph node therapy is imaginable. Thus, fundamentally a preoperative histological examination by fh-SPECT/US-guided biopsy is possible.

Feasibility of preoperative (125)I seed-guided tumoural tracer injection using freehand SPECT for sentinel lymph node mapping in non-palpable breast cancer.

BACKGROUND: This study was designed to explore the feasibility of replacing the conventional peri-/intratumoural ultrasound (US)-guided technetium-99m albumin nanocolloid ((99m)Tc-nanocolloid) administration by an injection of the same tracer guided by a freehand single-photon emission computed tomography (SPECT) device in patients with non-palpable breast cancer with an iodine-125 ((125)I) seed as tumour marker, who are scheduled for a sentinel lymph node biopsy (SLNB). This approach aimed to decrease the workload of the radiology department, avoiding a second US-guided procedure. METHODS: In ten patients, the implanted (125)I seed was primarily localised using freehand SPECT and subsequently verified by conventional US in order to inject the (99m)Tc-nanocolloid. The following 34 patients were injected using only freehand SPECT localisation. In these patients, additional SPECT/CT was acquired to measure the distance between the (99m)Tc-nanocolloid injection depot and the (125)I seed. In retrospect, a group of 21 patients with US-guided (99m)Tc-nanocolloid administrations was included as a control group. RESULTS: The depth difference measured by US and freehand SPECT in ten patients was 1.6 ± 1.6 mm. In the following 36 (125)I seeds (34 patients), the average difference between the (125)I seed and the centre of the (99m)Tc-nanocolloid injection depot was 10.9 ± 6.8 mm. In the retrospective study, the average distance between the (125)I seed and the centre of the (99m)Tc-nanocolloid injection depot as measured in SPECT/CT was 9.7 ± 6.5 mm and was not significantly different compared to the freehand SPECT-guided group (two-sample Student's t test, p = 0.52). CONCLUSION: We conclude that using freehand SPECT for (99m)Tc-nanocolloid administration in patients with non-palpable breast cancer with previously implanted (125)I seed is feasible. This technique may improve daily clinical logistics, reducing the workload of the radiology department.

Concordancia entre SPECT portátil y la gammagrafía convencional para detección de ganglio centinela en cáncer de mama / Concordance between freehand SPECT and conventional scintigraphy for sentinel lymph node detection in breast cancer

Introducción: La SPECT portátil puede ser una técnica de imagen útil para la planificación preoperatoria de la biopsia selectiva del ganglio centinela (BSGC) ya que permite la localización del ganglio centinela (GC) mediante imágenes tomográficas en 3D y en tiempo real y determina su profundidad, después de unos minutos de exploración. El objetivo del estudio fue evaluar la correlación entre el número de GC detectados entre las imágenes de la SPECT portátil y la linfogammagrafía (LG). Materiales y métodos: Cien pacientes con diagnóstico de cáncer de mama infiltrante y sin evidencia clínica de afectación ganglionar, se sometieron prospectivamente a una BSGC. El estudio preoperatorio incluyó imágenes de SPECT portátil a los 15 min tras la inyección y de LG a los 25 y 60-90 min (precoz y tardía). Se analizó el acuerdo observado y se realizó un estudio de concordancia entre el número de GC detectados con SPECT portátil y LG. Resultados: El acuerdo observado en la detección de GC entre SPECT portátil y LG precoz fue del 72%; entre SPECT portátil y LG tardía del 85%, y entre la LG precoz y la tardía de un 87%. En el estudio de concordancia se registró una concordancia moderada entre la SPECT portátil y la LG precoz (coeficiente kappa: 0,42); una concordancia moderada-alta entre la SPECT portátil y la LG tardía (coeficiente kappa: 0,60), y una concordancia de moderada-alta entre la LG precoz y la tardía (coeficiente kappa: 0,70), sin diferencias significativas entre ellos (valor p=0,16). Conclusión: La SPECT portátil presentó una concordancia moderada-alta con los estudios de imagen convencional y podría ser una alternativa válida para el estudio prequirúrgico de la BSGC en el cáncer de mama.(AU)

Introduction: Freehand SPECT can be a useful imaging technique for preoperative planning of sentinel lymph node biopsy (SLNB) as it allows localization of the sentinel node by 3D and real-time tomographic imaging and determines its depth after a few minutes of scanning. The aim of the study was to evaluate the correlation between the number of detected SNs between freehand SPECT images and lymphoscintigraphy (LS). Materials and methods: One hundred patients with a diagnosis of invasive breast cancer and no clinical evidence of lymph node involvement prospectively underwent SLNB. The preoperative study included freehand SPECT imaging at 15min after injection and LS imaging at 25 and 60–90min after injection (early and late). The observed agreement was analyzed and a concordance study was performed between the number of SNs detected with freehand SPECT and LS. Results: The observed agreement in the detection of SNs between freehand SPECT and early LS was 72%; between freehand SPECT and late LS was 85%; and between early and late LS was 87%. In the concordance study, there was moderate concordance between freehand SPECT and early LS (kappa coefficient: 0.42); moderate-high concordance between freehand SPECT and late LS (kappa coefficient: 0.60); and moderate-high concordance between early and late LS (kappa coefficient: 0.70), with no significant differences between them (p-value=0.16). Conclusion: Freehand SPECT showed a moderate-high concordance with conventional imaging studies and could be a valid alternative for the presurgical study of SLNB in breast cancer.(AU)

First Experiences with Navigated Radio-Guided Surgery Using Freehand SPECT.

BACKGROUND: Sentinel lymph node biopsy (SLNB) in melanoma using one-dimensional gamma probes is a standard of care worldwide. Reports on the performance are claimed by most groups to successfully detect the SLNs during the surgical procedure in almost 100% of the patients. In clinical practice, however, several issues remain which are usually not addressed: the difficulty of intraoperative detection of deeply located nodes, SLN detection in obese patients or in the groin and the impossibility to make a scan of the entire wound after SLN resection to avoid false negative testing for eventually remaining SLNs. MATERIALS AND METHODS: The concept behind freehand SPECT is to combine a gamma probe as used for conventional radio-guided surgery with a tracking system as used in neurosurgical navigation. From this combination and a proper algorithm framework the 3D reconstruction of radioactivity distributions and displaying these intraoperatively is possible. CONCLUSION: In summary, the feasibility of freehand SPECT could be shown and provides an image-guided SLNB and a truly minimally invasive and optimized surgical procedure.