Contribución de la medicina nuclear en la cirugía de precisión en el cáncer de mama / Nuclear medicine contribution to precision surgery in breast cancer

La medicina nuclear ha contribuido significativamente en la cirugía de precisión en el cáncer de mama en las últimas décadas. La cirugía radioguiada (CRG) ha permitido la biopsia del ganglio centinela (GC) en la evaluación de la infiltración ganglionar regional modificando el manejo de pacientes con cáncer de mama precoz. Para la axila, el procedimiento de la biopsia del GC ha significado un decremento de complicaciones y una mejor calidad de vida en comparación con la disección de los ganglios linfáticos axilares. Originalmente, la biopsia del GC se indicó principalmente en tumores cT1-2, sin evidencia de metástasis en los ganglios linfáticos axilares. Sin embargo, en los últimos años la biopsia del GC también se está ofreciendo a pacientes con tumores grandes o multifocales, carcinoma ductal in situ, recidiva del cáncer de mama ipsilateral y a pacientes que reciben tratamiento sistémico neoadyuvante (TSN) para cirugía conservadora de mama. Paralelamente a esta evolución, varias asociaciones científicas están tratando de homogeneizar cuestiones como la elección del radiotrazador, el lugar de inyección de la mama, la estandarización de las imágenes preoperatorias y el momento de la biopsia del GC en relación con el TSN, así como el manejo de las metástasis no axilares del GC (p. ej., cadena mamaria interna). Además, la CRG se usa actualmente para lograr la extirpación de tumores de mama primarios mediante inyección intralesional de radiocoloides o mediante implantación de semillas de yodo radiactivo que también se emplean para marcar los ganglios linfáticos axilares metastásicos. Este último procedimiento contribuye a manejar la axila con ganglios positivos en combinación con la PET/TC con [18F]FDG en un esfuerzo por adaptar el tratamiento sistémico y locorregional (AU)

Nuclear medicine has significantly contributed to precision surgery in breast cancer in the past decades. Radioguided surgery (RGS) has enabled sentinel node (SN) biopsy in assessing regional nodal involvement modifying the management of patients with early breast cancer. For the axilla the SN procedure has resulted in fewer complications and better quality of life when compared with axillary lymph node dissection. Originally, SN biopsy principally concerned cT1-2 tumors without evidence of axillary lymph node metastases. However, in last years SN biopsy is also being offered to patients with large or multifocal tumors, ductal carcinoma in situ, ipsilateral breast cancer relapse, and to patients receiving neoadjuvant systemic treatment (NST) for breast sparing surgery. Parallel to this evolution various scientific associations are trying to homogenise issues such as radiotracer choice, breast injection site, preoperative imaging standardisation and SN biopsy timing in relation to NST as well as management of non-axillary SN metastasis (e.g. internal mammary chain). Additionally, RGS is currently used to accomplish primary breast tumour excision either by intralesional radiocolloid injection or by radioactive iodine seed implantation which is also employed to target metastatic axillary lymph nodes. This latter procedure contributes to manage the node-positive axilla in combination with 18F-FDG PET/CT in an effort to tailor systemic and loco regional treatment (AU)

Does 99mTc-tilmanocept, as next generation radiotracer, meet with the requirements for improved sentinel node imaging?

INTRODUCTION AND OBJECTIVES: To evaluate the migration of 99mTc-tilmanocept from the injection site (IS) as well as the uptake in sentinel nodes (SNs) and non-SNs for lymphatic mapping in patients with breast cancer and melanoma, scheduled for SN biopsy after interstitial tracer administration. MATERIALS AND METHODS: For 29 primary tumours in 28 patients (mean age: 62y, range: 45-81y) scheduled for SN biopsy planar images were acquired 10 and 120min after administration of 74MBq 99mTc-tilmanocept, in order to evaluate lymphatic drainage as well as uptake ratios between injection site (IS), SN and non-SN. SPECT-CT was performed immediately after delayed planar images to enable anatomical lymph node localization. RESULTS: SNs were visualized in all patients (100%) with drainage to 34 basins. Uptake in non-SNs was perceived in 16 basins (47%). Number of SNs was concordant between early and delayed images in all basins excepting five (86%). In 24 patients tracer migrated to one lymph node basin (LNB), in three to 2 and in one to 4. When IS was included (N=29) on image, IS/SN ratio could be measured per LNB. The IS/SN ratio at 2h compared to 15min decreased with an average of 66% (range: 15-96%). SN/non-SN 2h ratio in LNBs with visible non-SNs averaged 6.6 (range: 2.3-15.6). In 9 patients with two SNs SN1/SN2 ratio averaged 1.9 on delayed images. At histopathology, SNs were found to be tumour positive in 7 basins (20%). CONCLUSION: 99mTc-tilmanocept appears to meet the requirements for improved SN imaging in breast cancer and melanoma on the basis of early and persistent SN visualization frequently accompanied by no or markedly less non-SN uptake. This is associated to rapid migration from the injection site together with increasing SN uptake and retention as expressed by decreasing IS/SN and persistently high SN/non-SN ratios. Further head-to-head comparison of 99mTc-tilmanocept with standard SN radiotracers in larger series of patients is necessary.

Anatomical localization of radiocolloid tracer deposition affects outcome of sentinel node procedures in prostate cancer.

PURPOSE: Diagnostic imaging modalities have moderate sensitivity for the identification of lymph node (LN) metastases in prostate cancer (PCa) patients. Mapping the lymphatic drainage from the prostate can help to identify the LNs directly draining from the tumour (sentinel nodes (SNs)); the LNs stated to have the highest chance of containing metastatic cancer cells. Although the lymphatic drainage may differ between segments within the prostate, the location of the primary tumour is not routinely taken into account during peripheral zone-aimed tracer administration. This study evaluates whether linking the SN procedure to the primary cancer deposits increases the identification accuracy of lymphatic metastases. METHODS: Sixty-seven PCa patients, scheduled for robot-assisted laparoscopic prostatectomy (RALP) and extended lymph node dissection (ePLND) with subsequent SN biopsy, were included in this retrospective study. After injection of the hybrid tracer ICG-99mTc-nanocolloid in the prostate, SN mapping was performed based on lymphoscintigraphy and SPECT/CT. SNs were resected using a combination of radio- and fluorescence guidance. Pathology was used to determine the primary tumour location and metastatic spread. Fluorescence imaging of paraffin-embedded prostate tissue was used to determine the location of the tracer deposits in the prostate. This deposition was related to the primary tumour location, the lymphatic drainage pattern of the injected tracer, and the metastatic spread. RESULTS: In total 265 radioactive LNs (211 SNs and 54 higher-echelon nodes in 64 patients; 4.3 LNs per patient; IQR: 2-6) were identified. In three patients (4%) preoperative imaging did not allow identification of SNs. Tumour-positive SN visualization within the pelvis was shown to be influenced by intraprostatic location of tracer administration. This could be concluded from (1) a clear correlation between lymphatic drainage to the right or left side of the body and tracer deposition on the right or left side of the prostate, (2) visualization of a higher number of LNs after dorsal tracer deposition compared with ventral tracer deposition, (3) different drainage patterns observed for tracer deposition into the base or apex of the prostate, and (4) the indication that intratumoural tracer deposition increases the chance of visualizing nodal metastases compared with extratumoural tracer deposition. CONCLUSIONS: The correlation between the location of the tracer deposits, the location of the primary tumour, and the visualization of the (tumour-positive) SNs indicated that placement of tracer deposits is of influence on the visualized lymphatic drainage pattern. This suggests that tracer injection near or into the primary tumour site is beneficial for the identification of metastatic spread.

Freehand-SPECT with 99mTc-HDP as tool to guide percutaneous biopsy of skeletal lesions detected on bone scintigraphy. / Freehand-SPECT con 99mTc-HDP como herramienta para guiar la biopsia percutánea de lesiones esqueléticas detectadas en la gammagrafía ósea.

PURPOSE: To assess the feasibility of using freehand Single Photon Emission Computed Tomography (freehandSPECT) for the identification of technetium-99m-hydroxydiphosphonate (99mTc-HDP) positive bone lesions and to evaluate the possibility of using these imaging data-sets for augmented- and virtual-reality based navigation approaches. MATERIAL AND METHODS: In 20 consecutive patients referred for scintigraphy with 99mTc-HDP, 21 three-dimensional freehandSPECT-images were generated using a handheld gamma camera. Concordance of the two different data sets was ranked. Furthermore, feasibility of segmenting the hotspot of tracer accumulation for navigation purposes was assessed. RESULTS: In 86% of the cases freehandSPECT images showed good concordance with the corresponding part of the scintigraphic images. In lesions with a signal to background ratio (SBR) >1.36, freehandSPECT provided an automatically segmented reference point for navigation purposes. In 14% of the cases (average SBR 1.82, range 1.0-3.4) freehandSPECT images showed intermediate concordance due to difficult anatomical area or negative bone scintigraphy and could not be used as navigation targets. CONCLUSION: In this pilot study, in 86% of the cases freehandSPECT demonstrated good concordance with traditional scintigraphy. A lesion with a SBR of 1.36 or more was suitable for navigation. These high-quality freehandSPECT images supported the future exploration navigation strategies, e.g. guided needle biopsies.

Next generation of radiotracers for sentinel lymph node biopsy: What is still necessary to establish new imaging paradigms? / Nueva generación de radiotrazadores para la biopsia del ganglio centinela: ¿qué es necesario para establecer nuevos paradigmas de imagen?

Sentinel lymph node (SLN) biopsy is now the standard of care for regional staging in several solid tumors. The interstitial administration of a radiotracer around the primary tumor provide the possibility to sequentially obtain images with a gamma camera and visualize lymphatic mapping and the SLN. There is, however, a large geographical variability in those radiotracers and nanocolloids ranging from 15-100nm which are most widely employed in Europe, while filtered and unfiltered 99mTc-sulfur colloid (range 20-1000nm) is usually used in the USA with different drawbacks in its use. The new radiotracer 99mTc-Tilmanocept, designed specifically for the identification of SLNs and recently becoming commercially available in USA and Europe, appears to have the potency to overcome the shortcomings described for the conventional radiotracers used until now for SLN biopsy and at the same time to transform current imaging paradigms. After delineating the challenges for the next generation of radiotracers, this paper discusses the properties of 99mTc-Tilmanocept, its validation process for SLN biopsy and its emerging clinical applications in various malignancies.

The best of both worlds: a hybrid approach for optimal pre- and intraoperative identification of sentinel lymph nodes.

PURPOSE: Hybrid image-guided surgery technologies such as combined radio- and fluorescence-guidance are increasingly gaining interest, but their added value still needs to be proven. In order to evaluate if and how fluorescence-guidance can help realize improvements beyond the current state-of-the-art in sentinel node (SN) biopsy procedures, use of the hybrid tracer indocyanine green (ICG)-99mTc-nancolloid was evaluated in a large cohort of patients. PATIENTS AND METHODS: A prospective trial was conducted (n = 501 procedures) in a heterogeneous cohort of 495 patients with different malignancies (skin malignancies, oral cavity cancer, penile cancer, prostate cancer and vulva cancer). After injection of ICG-99mTc-nanocolloid, SNs were preoperatively identified based on lymphoscintigraphy and SPECT/CT. Intraoperatively, SNs were pursued via gamma tracing, visual identification (blue dye) and/or near-infrared fluorescence imaging during either open surgical procedures (head and neck, penile, vulvar cancer and melanoma) or robot assisted laparoscopic surgery (prostate cancer). As the patients acted as their own control, use of hybrid guidance could be compared to conventional radioguidance and the use of blue dye (n = 300). This was based on reported surgical complications, overall survival, LN recurrence free survival, and false negative rates (FNR). RESULTS: A total of 1,327 SN-related hotspots were identified on 501 preoperative SPECT/CT scans. Intraoperatively, a total number of 1,643 SNs were identified based on the combination of gamma-tracing (>98%) and fluorescence-guidance (>95%). In patients wherein blue dye was used (n = 300) fluorescence-based SN detection was superior over visual blue dye-based detection (22-78%). No adverse effects related to the use of the hybrid tracer or the fluorescence-guidance procedure were found and outcome values were not negatively influenced. CONCLUSION: With ICG-99mTc-nanocolloid, the SN biopsy procedure has become more accurate and independent of the use of blue dye. With that, the procedure has evolved to be universal for different malignancies and anatomical locations.

Combined PET-CT and axillary lymph node marking with radioactive iodine seeds (MARI procedure) for tailored axillary treatment in node-positive breast cancer after neoadjuvant therapy.

BACKGROUND: The treatment of axillary lymph node metastases after neoadjuvant systemic therapy (NST) remains debatable and axillary lymph node dissection (ALND) is still the standard of care. Marking axillary lymph nodes with radioactive iodine seeds (MARI procedure) is accurate in restaging the axilla after NST (false-negative rate 7 per cent). Here, the potential of tailored axillary treatment, determined by combining the results of PET-CT before NST with those of the MARI procedure after NST, was analysed. METHODS: A cohort of axillary node-positive patients was used to construct a hypothetical treatment algorithm based on a combination of PET-CT and the MARI procedure. In the algorithm, the number of fluorodeoxyglucose (FDG)-avid axillary lymph nodes (1-3 versus 4 or more) before NST and the tumour status of the MARI node (positive versus negative) after NST were used to tailor axillary treatment. All patients in the cohort underwent ALND, allowing estimation of potential overtreatment and undertreatment. RESULTS: A total of 93 patients were included in the study. Between one and three FDG-avid axillary lymph nodes were observed in 59 patients, and four or more in 34 patients. The MARI node was tumour-negative in 32 patients and showed residual disease in 61. Treatment according to the constructed algorithm would have resulted in 74 per cent of patients avoiding an ALND, with potential undertreatment in three patients (3 per cent) and overtreatment in 16 (17 per cent). CONCLUSION: Tailored axillary treatment after NST in node-positive patients, by combining PET-CT before NST and the MARI procedure after NST, has the potential for ALND to be avoided in 74 per cent of patients.

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.

PET/CT with 18F-FDG predicts short-term outcome in stage II/III breast cancer patients upstaged to N2/3 nodal disease.

INTRODUCTION: 18F-FDG PET/CT has high positive predictive value for the detection of avid lymph node metastases in breast cancer patients. We analysed the effect of upstaging lymph nodes by PET/CT on short-term outcome in stage II/III breast cancer patients. PATIENTS AND METHODS: A total of 278 stage II/III primary breast cancer patients (mean age 48.9 years, range 19-75 years) were re-staged with 18F-FDG PET/CT before start of pre-operative systemic treatment (PST). Patients were divided in three groups based on risk for local recurrence: a low - (T2N0), intermediate - (T0-2N1 and T3N0) and a high-risk group (T0-3N2-3, T3N1 and T4). Within these groups we looked at local recurrence-free survival (LRFS), recurrence-free survival (RFS) and overall survival (OS) within the first 3 years of follow-up. RESULTS: With a median follow-up (FU) of 50 months the RFS, LRFS and OS were 87%, 88% and 92% respectively for the whole group. PET/CT upstaged 43 patients from the low- and intermediate risk group to the high-risk group, based on detection of ≥4 avid axillary nodes or occult N2/3-disease. Patients upstaged with PET/CT had more events for all three analyses compared to the original risk groups, which resulted in a significantly worse RFS (69.8%; p = 0.03) a nearly significantly worse LRFS (p = 0.052) and no effect in OS (p = 0.433). DISCUSSION: Additional PET/CT staging allows breast cancer patients to be treated according to the true stage, still stage II/III breast cancer patients upstaged to N2/3 by PET/CT have worse short-term outcome, despite adjustment of treatment, than patients staged high-risk with conventional imaging.

Radioguided surgery and the GOSTT concept: From pre-operative image and intraoperative navigation to image-assisted excision.

Radio-guided surgery has been developed for application in those disease scheduled for surgical management, particularly in areas of complex anatomy. This is based on the use of pre-operative scintigraphic planar, tomographic and fused SPECT/CT images, and the possibility of 3D reconstruction for the subsequent intraoperative locating of active lesions using handheld devices (detection probes, gamma cameras, etc.). New tracers and technologies have also been incorporated into these surgical procedures. The combination of visual and acoustic signals during the intraoperative procedure has become possible with new portable imaging modalities. In daily practice, the images offered by these techniques and devices combine perioperative nuclear medicine imaging with the superior resolution of additional optical guidance in the operating room. In many ways they provide real-time images, allowing accurate guidance during surgery, a reduction in the time required for tissue location and an anatomical environment for surgical recognition. All these approaches have been included in the concept known as (radio) Guided intraOperative Scintigraphic Tumour Targeting (GOSTT). This article offers a general view of different nuclear medicine and allied technologies used for several GOSTT procedures, and illustrates the crossing of technological frontiers in radio-guided surgery.

Methodological aspects of 99mTc-sestamibi guided biopsy in breast cancer.

PURPOSE: This review aims to discuss the methodological aspects of dedicated molecular breast imaging (MBI) using 99mTc-sestamibi as radiotracer to guide biopsy of occult or unclear breast lesions on mammography (MG) and ultrasound (US) that are suspicious on MBI (BI-RADS criteria 4 and 5), including its advantages, limitations and future clinical applications. METHODS: Literature search was performed using the PubMed/MEDLINE database and "99mTc-sestamibi", "biopsy" and "breast cancer" as keywords. The search was restricted to English language. RESULTS: There are few studies on 99mTc-sestamibi guided biopsy methods; to our knowledge, no full studies have yet been reported on clinical validation of this new biopsy procedure. This review describes technical aspects of 99mTc-sestamibi guided biopsy and discusses the advantages and limitations of this procedure in comparison with MG, US and MRI-guided biopsy. CONCLUSIONS: MBI-guided biopsy appears to be a complementary modality and is principally indicated in the case of occult or unclear breast lesions on MG/US, that are suspicious on MBI. The future indication is in targeted biopsies in patients with large heterogeneous tumours. Further studies are needed to define the accuracy of this biopsy procedure.

Hybrid radioguided occult lesion localization (hybrid ROLL) of (18)F-FDG-avid lesions using the hybrid tracer indocyanine green-(99m)Tc-nanocolloid.

PURPOSE: To assess if combined fluorescence- and radio-guided occult lesion localization (hybrid ROLL) is feasible in patients scheduled for surgical resection of non-palpable (18)F-FDG-avid lesions on PET/CT. METHODS: Four patients with (18)F-FDG-avid lesions on follow-up PET/CT that were not palpable during physical examination but were suspected to harbor metastasis were enrolled. Guided by ultrasound, the hybrid tracer indocyanine green (ICG)-(99m)Tc-nanocolloid was injected centrally in the target lesion. SPECT/CT imaging was used to confirm tracer deposition. Intraoperatively, lesions were localized using a hand-held gamma ray detection probe, a portable gamma camera, and a fluorescence camera. After excision, the gamma camera was used to check the wound bed for residual activity. RESULTS: A total of six (18)F-FDG-avid lymph nodes were identified and scheduled for hybrid ROLL. Comparison of the PET/CT images with the acquired SPECT/CT after hybrid tracer injection confirmed accurate tracer deposition. No side effects were observed. Combined radio- and fluorescence-guidance enabled localization and excision of the target lesion in all patients. Five of the six excised lesions proved tumor-positive at histopathology. CONCLUSION: The hybrid ROLL approach appears to be feasible and can facilitate the intraoperative localization and excision of non-palpable lesions suspected to harbor tumor metastases. In addition to the initial radioguided detection, the fluorescence component of the hybrid tracer enables high-resolution intraoperative visualization of the target lesion. The procedure needs further evaluation in a larger cohort and wider range of malignancies to substantiate these preliminary findings.

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.

Sentinel node approach in prostate cancer.

In general terms, one of the main objectives of sentinel lymph node (SLN) biopsy is to identify the 20-25% of patients with occult regional metastatic involvement. This technique reduces the associated morbidity from lymphadenectomy, as well as increasing the identification rate of occult lymphatic metastases by offering the pathologist those lymph nodes with the highest probability of containing metastatic cells. Pre-surgical lymphoscintigraphy is considered a "road map" to guide the surgeon towards the sentinel nodes and to ascertain unpredictable lymphatic drainages. In prostate cancer this aspect is essential due to the multidirectional character of the lymphatic drainage in the pelvis. In this context the inclusion of SPECT/CT should be mandatory in order to improve the SLN detection rate, to clarify the location when SLNs are difficult to interpret on planar images, to achieve a better definition of them in locations close to injection site, and to provide anatomical landmarks to be recognized during operation to locate SLNs. Conventional and laparoscopic hand-held gamma probes allow the SLN technique to be applied in any kind of surgery. The introduction and combination of new tracers and devices refines this technique, and the use of intraoperative images. These aspects become of vital importance due to the recent incorporation of robot-assisted procedures for SLN biopsy. In spite of these advances various aspects of SLN biopsy in prostate cancer patients still need to be discussed, and therefore their clinical application is not widely used.

Simultaneous use of an (125)I-seed to guide tumour excision and (99m)Tc-nanocolloid for sentinel node biopsy in non-palpable breast-conserving surgery.

PURPOSE: In the present study we describe patients with non-palpable breast lesions, in which an Iodine-125 ((125)I)-marker (or "seed") for excision of the primary tumour and Technetium-99m nanocolloid ((99m)Tc-nanocolloid) for sentinel node biopsy (SNB) are used simultaneously. The purpose was to investigate any interference between (125)I-seeds and (99m)Tc-nanocolloid by an in vitro and in vivo analysis. METHODS: Contrast/interference-ratios between (125)I and (99m)Tc count-rates were determined in vitro using a realistic simulation model. Measurements were performed with 3 gamma-probes with different crystal materials. In 25 consecutive patients (99m)Tc-nanocolloid was intratumourally administered at the site of a previously implanted (125)I-seed. Respectively, the (125)I-setting and (99m)Tc-setting of the gamma-probe guided the wide local excision and SNB and maximum counts-per-second (cps) were measured. RESULTS: In vitro the different probes varied in (125)I- and (99m)Tc-sensitivity. The contrast-ratio between (125)I and (99m)Tc in the (125)I-channel was 4.6 for a 3-month-old (125)I-seed using the most appropriate gamma-probe. In vivo the gamma-probe in the (125)I-setting measured a median of 16,300 cps at the tumour site compared to 4820 cps using the (99m)Tc-setting. The (125)I-seed could be well distinguished from the (99m)Tc-nanocolloid in 92% of the patients and 96% required a single operation. The SNB was successful in all patients. CONCLUSIONS: Simultaneous use of (125)I-seeds and (99m)Tc-nanocolloid is possible under well-standardised conditions. Non-palpable breast lesions can be safely excised using the (125)I-seed in combination with a SN procedure. Use of (125)I-seeds is a next step within fine-tuning breast-conserving surgery that should lead to further investigation to confirm its value.

[Utility of SPECT/CT scan for anatomical localization of pararectal and presacral sentinel nodes in prostate cancer]. / Utilidad de la SPECT-TC para la localización anatómica de los ganglios centinelas presacrales y pararrectales en el cáncer de próstata.

AIM: This study has aimed to evaluate the added value of SPECT-CT scan in the preoperative assessment of sentinel nodes of the presacral and pararectal regions localized outside the standard area of extended pelvic lymphadenectomy for the staging of the pelvis in prostate cancer. SPECT-CT scan can serve as a guide for the excision of these nodes by lymphadenectomy by open surgery or laparoscopy. MATERIAL AND METHODS: We evaluated 4 patients with prostate cancer presenting sentinel nodes in the pararectal and presacral regions on SPECT-CT scan performed in addition to lymphoscintigraphy. These patients underwent lymphadenectomy with robot-assisted laparoscopy together with prostatectomy. All of the excised lymph nodes were sent for histopathology study. RESULTS: An average of 6 sentinel nodes per patient were found on SPECT-CT scan with a mean of 2 sentinel nodes in presacral/pararectal región. Lymphadenectomy including these areas was performed. Pararectal/presacral sentinel nodes of all patients depicted by SPECT-CT scan were tumor free on histopathology study. Sentinel nodes (no pararectal/presacral) were positive for malignancy in only one patient. CONCLUSION: Preoperative SPECT-CT scan is a useful tool to localize the sentinel nodes in pararectal/presacral regions. It can be an anatomic guide for new modalities of laparoscopic surgery such as robot-assisted procedures that can access the pelvic areas visualized with SPECT-CT scan, making excision of these nodes possible.

Contribution of SPECT/CT imaging to radioguided sentinel lymph node biopsy in breast cancer, melanoma, and other solid cancers: from "open and see" to "see and open".

A few years ago SPECT/CT was successfully incorporated into the sentinel node (SN) procedure for breast cancer and melanoma. Important contributions of SPECT/CT in these two malignancies were the anatomical localization of SNs already visualized on planar images, the detection of additional SNs in aberrant basins, and the depiction of SNs in cases with no visualization on planar images. Recently, in a large series of melanoma patients the use of SPECT/CT was associated with the detection of more metastatic SNs and a higher rate of disease-free survival. Following the experiences in breast cancer and melanoma, SPECT/CT has been applied in oral cavity cancer as well as in urological and gynaecological malignancies. In the areas of lymphatic drainage of these malignancies (head and neck, pelvis, and upper abdomen) SPECT/CT appears to be essential to localize SNs, providing surgeons with helpful anatomical landmarks to plan SN biopsies. In gastrointestinal and lung malignancies SPECT/CT has only incidentally been used. With the improvement of the CT component in the second generation of SPECT/CT gamma cameras, nuclear physicians today can identify lymph nodes corresponding with the radioactive SNs. This is possible using a display of SPECT/CT similar to that of conventional tomography. Multiplanar reconstruction enables to correlate radioactive sentinel nodes seen on fused SPECT/CT with lymph nodes seen on CT, and the use of cross-reference lines allows the navigation between axial, coronal and sagittal views. This visual information is helpful for the intraoperative procedure and for post-excision assessment using portable devices. Fused SPECT/CT images may also be three-dimensionally displayed, improving anatomical SN localisation and recognition. This recent imaging improvement is leading to a new paradigm of "see and open" in contraposition to the former "open and see" in the SN procedure. The new mixed reality protocols which are able to transfer SPECT/CT to the operating room for surgical navigation will reinforce this "see and open" concept. However, a comprehensive interpretation of SPECT/CT together with lymphoscintigraphy is necessary to identify radioactive lymph nodes as sentinel nodes and classify them into different categories that are important for the intraoperative procedure.