Indocyanine green versus technetium-99m with blue dye for sentinel lymph node detection in early-stage cervical cancer: A systematic review and meta-analysis.

BACKGROUND: The fluorescent dye indocyanine green (ICG) has emerged as a promising tracer for intraoperative detection of sentinel lymph nodes (SLNs) in early-stage cervical cancer. Although researchers suggest the SLN detection of ICG is equal to the more conventional combined approach of a radiotracer and blue dye, no consensus has been reached. AIMS: We aimed to assess the differences in overall and bilateral SLN detection rates with ICG versus the combined approach, the radiotracer technetium-99m (99m Tc) with blue dye. METHODS AND RESULTS: We searched MEDLINE, Embase, and the Cochrane Library from inception to January 1, 2020 and included studies reporting on a comparison of SLN detection with ICG versus 99m Tc with blue dye in early-stage cervical cancer. The overall and bilateral detection rates were pooled with random-effects meta-analyses. From 118 studies retrieved seven studies (one cross-sectional; six retrospective cohorts) were included, encompassing 589 patients. No significant differences were found in the pooled overall SLN detection rate of ICG versus 99m Tc with blue dye. Meta-analyses of all studies showed ICG to result in a higher bilateral SLN detection rate than 99m Tc with blue dye; 90.3% (95%CI, 79.8-100.0%) with ICG versus 73.5% (95%CI, 66.4-80.6%) with 99mTc with blue dye. This resulted in a significant and clinically relevant risk difference of 16.6% (95%CI, 5.3-28.0%). With sensitivity analysis, the risk difference of the bilateral detection rate maintained in favor of ICG but was no longer significant (13.2%, 95%CI -0.8-27.3%). CONCLUSION: ICG appears to provide higher bilateral SLN detection rates compared to 99m Tc with blue dye in patients with early-stage cervical cancer. However, in adherence with the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) guidelines, the quality of evidence is too low to provide strong recommendations and directly omit the combined approach of 99m Tc with blue dye.

One-step, kit-based radiopharmaceuticals for molecular SPECT imaging: a versatile diphosphine chelator for 99mTc radiolabelling of peptides.

Radiotracers labelled with technetium-99m (99mTc) enable accessible diagnostic imaging of disease, provided that radiotracer preparation is simple. Whilst 99mTc radiopharmaceuticals for imaging perfusion are routinely prepared from kits, and regularly used in healthcare, there are no 99mTc-labelled receptor-targeted radiopharmaceuticals in widespread clinical use. This is in part due to the multistep radiosyntheses required for the latter. We demonstrate that the diphosphine, 2,3-bis(diphenylphosphino)maleic anhydride (BMA), is an excellent platform for preparation of kit-based, receptor-targeted 99mTc-labelled radiotracers: its conjugates are simple to prepare and can be easily labelled with 99mTc using one-step, kit-based protocols. Here, reaction of BMA with the αvß3-integrin receptor targeted cyclic peptide, Arg-Gly-Asp-DPhe-Lys (RGD), provided the first diphosphine-peptide conjugate, DP-RGD. DP-RGD was incorporated into a "kit", and addition of a saline solution containing 99mTcO4- to this kit, followed by heating, furnished the radiotracer [99mTcO2(DP-RGD)2]+ in consistently high radiochemical yields (>90%). The analogous [ReO2(DP-RGD)2]+ compound was prepared and characterised, revealing that both [99mTcO2(DP-RGD)2]+ and [ReO2(DP-RGD)2]+ consist of a mixture of cis and trans geometric isomers. Finally, [99mTcO2(DP-RGD)2]+ exhibited high metabolic stability, and selectively targeted αvß3-integrin receptors, enabling in vivo SPECT imaging of αvß3-integrin receptor expression in mice.

99mTc Stearyl 6-(benzylidenehydrazinyl) nicotinamide Liposomes as Tumor Permeability Evaluation Tracer.

Nanomedicine is a highly demanded discipline. Liposomes have seen an increased attention due to their physicochemical properties that allow them to act as nanocarriers of drugs and also of radioisotopes that can be used to diagnose and treat cancer. In order to obtain a novel permeability cancer imaging agent based on 99mTc-labeled liposomes, we describe microwave-assisted synthesis of stearyl 6-(benzylidenehydrazinyl) nicotinamide lipid, which was included in two formulations: nanometric hydrazinonicotinic acid (HYNIC) liposome and its PEGylated coated analogue, HYNIC-PEG liposome. Radiolabeling with 99mTc via stearyl 6-(benzylidenehydrazinyl) nicotinamide was found to be easy, reproducible, and stable, revealing high radiochemical purity (94 ± 1.7%) for both liposomal formulations. Biodistribution at 4 h and 24 h and scintigraphic images at 4 h were performed in normal and melanoma-bearing C57BL/6 mice. Biodistribution studies at 4 h showed tumor uptake of 99mTc-HYNIC liposome and 99mTc-HYNIC-PEG liposome (1.1 ± 0.6 and 2.5 ± 0.4, respectively) and also at 24 h p.i. (1.8 ± 0.5 and 3.0 ± 1.1, respectively). Scintigraphic images showed appreciable tumor uptake in melanoma tumor-bearing mice with both liposomal formulations. Our results show that 99mTc stearyl 6-(benzylidenehydrazinyl) nicotinamide liposomes can be used as diagnostic noninvasive in vivo tumor-targeting agents capable of evaluating tumor permeability and development who can be used in personalized chemotherapy planning.

Reverse Lymph Node Mapping Using Indocyanine Green Lymphography: A Step Forward in Minimizing Donor-Site Morbidity in Vascularized Lymph Node Transfer.

BACKGROUND: Reverse lymphatic mapping before harvesting a lymph node flap is crucial to avoid donor-site lymphedema; however, the technique is complex and unavailable in many centers. The authors introduce radioisotope-free reverse lymphatic mapping using indocyanine green and Patent Blue dye. METHODS: The authors conducted a prospective study in patients undergoing free vascularized groin lymph node transfer for postmastectomy upper extremity lymphedema. The day before surgery, 0.2 ml of technetium-99 was injected into the first and second web spaces of the ipsilateral foot. The following day, once the patient was anesthetized, indocyanine green was injected into the same web spaces of the same foot and Patent Blue dye was injected just proximal to the upper margin of the skin paddle of the lymph node flap. The main lymph nodes draining the limb were localized using indocyanine green lymphography and gamma probe. RESULTS: Thirty-nine patients underwent vascularized groin lymph node transfer with or without deep inferior epigastric artery perforator flap breast reconstruction. Navigation of the main lower extremity draining inguinal lymph nodes using the gamma probe and indocyanine green lymphography was identical in all patients. The blue-stained lymphatics in the skin paddle drained to the superficial proximal inguinal lymph node and were targeted for transfer. No donor-site lymphedema was reported, and lymphatic drainage of the lower extremity was preserved in all cases. CONCLUSIONS: Reverse lymphatic mapping using indocyanine green lymphography provides identical results to those using technetium-99 isotope scanning. However, indocyanine green is preferable in terms of safety and reproducibility and also avoids the complexity and hazards of radioisotope mapping. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Bioconjugated technetium carbonyls by transmetalation reaction with zinc derivatives.

The transmetalation reaction between zinc dithiocarbamates functionalized with organic groups and the cation fac-[99mTc(H2O)3(CO)3]+ has been studied as a new strategy to bind biomolecules to this radionuclide for preparing radiopharmaceuticals with high molar activity. All complexes were obtained in high yields by heating at moderate temperatures and without subsequent purification. The chemical identity was ascertained by HPLC comparison with the homologous rhenium complexes. Stability studies in cysteine solution and serum have shown a good stability of the coordination set fac-[99mTc(CO)3(SS)(P)]. Preliminary biological studies of the radiocomplex functionalized with D-(+)-glucosamine with carcinoma cells have been performed.

Analysis of failed therapy evaluations in radioembolization of primary and secondary liver cancers.

PURPOSE: To analyze patients' characteristics and reasons for not performing planned transarterial radioembolization (TARE) in liver cancer after 99mTc-labeled macroaggregated albumin (99mTc-MAA) evaluation. METHODS: In this retrospective single-center cohort, all patients undergoing 99mTc-MAA evaluation prior to planned TARE for primary or secondary liver cancer between 2009 and 2018 were analyzed. Patients were assigned to either "TARE" or "no TARE" group. Patients' characteristics, arising reasons for not performing the planned TARE treatment as well as predictive factors for occurrence of these causes were analyzed. RESULTS: 436 patients [male = 248, female = 188, median age 62 (23-88) years] with 99mTc-MAA evaluation prior to planned TARE of primary or secondary liver cancer were included in this study. 148 patients (33.9%) did not receive planned TARE. Patients with a hepatic tumor burden > 50%, no liver cirrhosis, no previous therapies and a higher bilirubin were significantly more frequent in "no TARE" compared to "TARE" group. Main reasons for not performing TARE were extrahepatic tracer accumulation (n = 70, 40.5%), non-target accumulation of 99mTc-MAA (n = 27, 15.6%) or a hepatopulmonary shunt fraction of more than 20% (n = 23, 13.3%). Independent preprocedural parameters for not performing planned TARE were elevated bilirubin (p = 0.021) and creatinine (p = 0.018) and lower MELD score (p = 0.031). CONCLUSION: A substantial number of patients are precluded from TARE following 99mTc-MAA evaluation, which is, therefore, implicitly needed to determine contraindications to TARE and should not be refrained from in pretreatment process. However, a preceding careful patient selection is needed especially in patients with high hepatic tumor burden and alteration in lab parameters.

Update on new imaging technologies in sentinel node detection.

In most cancers, lymph node status is the most critical factor impacting the evolution of the disease and the overall survival. Identifying potential nodal metastasis allows the oncologist to adjust the stage and, consequently, the patient's treatment. For this reason, a precise evaluation of the regional nodes is mandatory. In gynecological cancers, pelvic, paraaortic, and inguinal nodes are the region most frequently interested by metastasis. In the past years, comprehensive lymphadenectomy was the standard of care for endometrial, cervical, ovarian, and vulvar cancers. However, after introducing the sentinel lymph node (SNL) biopsy in breast cancers, this technique has gained much more interest in gynecology oncology. Several studies have shown that SLN allows an evaluation of the node status without the complications related to the lymphadenectomy that impacts the patient's quality of life. In this review, we discuss the role of SNL biopsy in gynecological cancers and the technique's evolution over the years. Moreover, we debate the OSNA method for SLN analysis that is recently introduced for uterine cancer.

The role of sentinel-node biopsy in ovarian cancer.

Lymph node involvement is an important prognostic factor in early and advanced epithelial ovarian cancer (EOC). However, to date there is no reliable method of detecting lymph node involvement, apart from surgical staging. Thus, pelvic and paraaortic lymphadenectomy (LNE) are still part of standard surgery of early ovarian cancer. There is conflicting evidence about the therapeutic value of systematic LNE in early EOC. Thus, the developmemt of a method to predict nodal status accurately, without extensive LNE, is the subject of ongoing research. Sentinel lymphadenectomy (SLN) has become a standard procedure in oncological surgery. However, SLN is not yet an established and widely accepted procedure for EOC. This review aimed at summarizing available evidence on its feasibility and reliability in EOC. Overall, evidence of SLN in early EOC is still scarce. So far, only small series of patients with a variety of tracers and injection sites were published. From the available literature, the most promising technique seems to be injection into the infundibulopelvic, as well as the proper ovarian ligament. Indocyanine green seems to be an excellent tracer for successful SLN of ovarian tumors, which can be used during laparoscopic or robotic surgery. The detection rates and true positive rates of studies support further investigation of the technique. Results from prospective studies, e.g. the ongoing SELLY trial, are necesssary to implement SLN into the standard treatment of early EOC.

Capabilities of multi-pinhole SPECT with two stationary detectors for in vivo rat imaging.

We aimed to investigate the image quality of the U-SPECT5/CT E-Class a micro single-photon emission computed tomography (SPECT) system with two large stationary detectors for visualization of rat hearts and bones using clinically available 99mTc-labelled tracers. Sensitivity, spatial resolution, uniformity and contrast-to-noise ratio (CNR) of the small-animal SPECT scanner were investigated in phantom studies using an ultra-high-resolution rat and mouse multi-pinhole collimator (UHR-RM). Point source, hot-rod, and uniform phantoms with 99mTc-solution were scanned for high-count performance assessment and count levels equal to animal scans, respectively. Reconstruction was performed using the similarity-regulated ordered-subsets expectation maximization (SROSEM) algorithm with Gaussian smoothing. Rats were injected with ~ 100 MBq [99mTc]Tc-MIBI or ~ 150 MBq [99mTc]Tc-HMDP and received multi-frame micro-SPECT imaging after tracer distribution. Animal scans were reconstructed for three different acquisition times and post-processed with different sized Gaussian filters. Following reconstruction, CNR was calculated and image quality evaluated by three independent readers on a five-point scale from 1 = "very poor" to 5 = "very good". Point source sensitivity was 567 cps/MBq and radioactive rods as small as 1.2 mm were resolved with the UHR-RM collimator. Collimator-dependent uniformity was 55.5%. Phantom CNR improved with increasing rod size, filter size and activity concentration. Left ventricle and bone structures were successfully visualized in rat experiments. Image quality was strongly affected by the extent of post-filtering, whereas scan time did not have substantial influence on visual assessment. Good image quality was achieved for resolution range greater than 1.8 mm in bone and 2.8 mm in heart. The recently introduced small animal SPECT system with two stationary detectors and UHR-RM collimator is capable to provide excellent image quality in heart and bone scans in a rat using standardized reconstruction parameters and appropriate post-filtering. However, there are still challenges in achieving maximum system resolution in the sub-millimeter range with in vivo settings under limited injection dose and acquisition time.

Visualización de divertículo de Killian-Jamieson bilateral en gammagrafía para el estudio del reflujo gastroesofágico con [99mTc]Tc-nanocoloide / Visualization of Killian-Jamieson bilateral diverticulum in gastro-esophageal reflux scintigraphy with [99mTc]Tc-nanocolloid

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The role of sentinel lymph node mapping in lower genital tract melanoma.

INTRODUCTION: Vulvar and vaginal melanomas are rare cancers of the female genital tract and account for 1% to 3% of all melanomas diagnosed in women. Due to the rarity of the disease, few data are available on the clinical and pathologic features of these cancers. Furthermore, treatment options are generally based on extrapolations of the information available for the more common cutaneous counterparts. Surgery represents the mainstay of treatment for lower genital tract melanoma. Moreover, the role of sentinel lymph node (SLN) assessment is controversial because no prospective data are available. EVIDENCE ACQUISITION: Data were collected from Medline, Embase, Web of Sciences and Scopus databases. On July 10, 2020, we used the search comprising the terms "vulvar melanoma," "genital melanoma" and "vulvovaginal melanoma" including only studies in which SLN biopsy was performed. EVIDENCE SYNTHESIS: Ten retrospective studies have been found. No randomized trials have been reported. The studies included 132 patients while only 63 (47%) undergone SLN. 99mTC with or without blue dye followed by ultrastaging was highly accurate and is currently the gold standard. Mean detection rate was 98.3%. No clear evidence supported the execution of back lymphadenectomy (after SLN mapping), in fact, extrapolating data from cutaneous melanomas of other sites, completion of lymphadenectomy does not confer a melanoma-specific survival advantage. CONCLUSIONS: Although the small amount of available data, sentinel lymph node procedure is feasible and capable of identifying patients who have occult lymph node metastases. However, the potential role of the sentinel lymph node procedure as an alternative method of lymph node staging in patients with vulvar or vaginal melanoma needs further investigation.

Preparación, radiomarcaje con 99mTc y 67Ga y estudios de biodistribución de nanopartículas de albúmina con recubrimientos poliméricos / Preparation, radiolabeling with 99mTc and 67Ga and biodistribution studies of albumin nanoparticles covered with polymers

OBJETIVO: Optimizar el radiomarcaje con 99mTc y 67Ga de nanopartículas de albúmina recubiertas con 4 polímeros sintéticos distintos y evaluar su estabilidad in vivo e in vitro, así como su biodistribución in vivo tras su administración intravenosa. MATERIAL Y MÉTODOS: Las nanopartículas se prepararon empleando albúmina y albúmina modificada con NOTA mediante el método de desolvatación y se recubrieron con 4 polímeros distintos; HPMC, GMN2, GPM2 y GTM2. Se purificaron, liofilizaron y caracterizaron. El marcaje con 99mTc se realizó con 74MBq de pertecnetato [99mTc] sódico previamente reducido con una disolución ácida de cloruro de estaño a diferentes concentraciones (0,003; 0,005; 0,007; 0,01; 0,05 y 0,1mg/ml), a distintos tiempos (5, 10, 15, 30 y 60min) y temperaturas (temperatura ambiente, 40°C y 60°C). El marcaje con 67Ga se llevó a cabo mediante incubación de las nanopartículas con 37MBq de cloruro de 67Ga (obtenido a partir de citrato de 67Ga comercial) a distintos tiempos (10 y 30min) y temperaturas (temperatura ambiente, 30°C y 60°C) y posterior purificación con microconcentradores. La pureza radioquímica de ambos marcajes se evaluó mediante TLC. Se llevaron a cabo estudios de estabilidad de las nanopartículas marcadas en suero fisiológico y plasma sanguíneo. Los estudios de biodistribución de las nanopartículas recubiertas con el polímero GPM2 se llevaron a cabo en ratas Wistar tras la administración intravenosa de las nanopartículas. Se realizaron animales control con pertecnetato [99mTc] sódico y cloruro de 67Ga. Posteriormente, los animales fueron sacrificados y se midió la actividad de los órganos en un contador gamma. RESULTADOS: El marcaje con 99mTc se llevó a cabo de forma óptima con una concentración de estaño de 0,007mg/ml para las nanopartículas GPM2 y de 0,005mg/ml para el resto de formulaciones, con un tiempo de marcaje de 10min y a temperatura ambiente. En el caso del 67Ga el marcaje se optimizó a 30°C de temperatura y 30min de incubación. En ambos casos, la pureza radioquímica obtenida fue superior al 97%. Las nanopartículas presentaron una elevada estabilidad in vitro pasadas las 48h del marcaje (70% las nanopartículas marcadas con 99mTc y 90% las marcadas con 67Ga). Los estudios de biodistribución de las nanopartículas [99mTc]-GPM2 y [67Ga]-NOTA-GPM2 mostraron una elevada acumulación de actividad en el hígado tanto a las 2h como a las 24h de la administración intravenosa. CONCLUSIÓN: El procedimiento de marcaje con 99mTc y 67Ga de nanopartículas de albúmina y albúmina modificada con NOTA permite la obtención de nanopartículas con elevados rendimientos de marcaje y una adecuada estabilidad in vitro, permitiendo su utilización para la realización de estudios in vivo

OBJECTIVE: To optimize radiolabeling with 99mTc and 67Ga of albumin nanoparticles coated with 4 differents synthetic polymers and to evaluate their stability in vivo and in vitro, as well as their biodistribution in vivo after intravenous administration. MATERIAL AND METHODS: The nanoparticles were prepared using albumin and NOTA-modified albumin by the desolvation method and coated with 4 different polymers; HPMC, GMN2, GPM2 and GTM2. They were purified, lyophilized and characterized. Radiolabelling with 99mTc was perfomed with 74 MBq of 99mTc sodium pertechnetate, previously reduced with and acid solution of tin chloride at different concentrations (0.003, 0.005, 0.007, 0.01, 0.05 and 0.1mg/ml) and at different times (5, 10, 15, 30 and 60minutes) and temperatures (room temperature, 40°C and 60°C). Radiolabelling with 67Ga was perfomed by incubation of the nanoparticles with 37 MBq of 67Gallium chloride (obtained from commercial gallium-67 citrate) at different times (10 and 30minutes) and temperatures (room temperature, 30°C and 60°C), and posterior purification with microconcentrators. The radiochemical purity was evaluated by TLC. Stability studies of radiolabeled nanoparticles in physiological serum and blood plasma were perfomed. Biodistribution studies of nanoparticles coated with GPM2 polymer were carried out in Wistar rats after intravenous administration of the nanoparticles. Control animals were carried out with 99mTc sodium pertechnetate and 67Ga chloride. To do so, the animals were killed and activity in organs was measured in a gamma counter. RESULTS: 99mTc labeling was carried out optimally with a tin concentration of 0.007mg/ ml for the GPM2 nanoparticles and 0.005mg / ml for the rest of the formulations, with a radiolabelling time of 10minutes at room temperature. In the case of 67Ga the label was optimized at 30° C temperature and 30minutes of incubation. In both cases the radiochemical purity obtained was greater than 97%. The nanoparticles showed high stability in vitro after 48hours of labeling (70% nanoparticles labeled with 99mTc and 90% those labeled with 67Ga). Biodistribution studies of nanoparticles 99mTc -GPM2 and 67Ga -NOTA-GPM2 showed a high accumulation of activity in the liver at 2 and 24hours after intravenous administration. CONCLUSION: The labeling procedure with 99mTc and 67Ga of albumin and albumin modified with NOTA nanoparticles allows obtaining nanoparticles with high labeling yields and adequate in vitro stability, allowing their use for in vivo studies

Gammagrafía cardíaca con 99mTc-difosfonatos en la amiloidosis cardíaca / Cardiac scintigraphy with 99mTc-diphosphonates in cardiac amyloidosis

La amiloidosis cardíaca relacionada con el depósito de transtirretina (ATTR) ha sido tradicionalmente considerada como una enfermedad rara, de difícil diagnóstico y sin tratamiento. Sin embargo, en la actualidad sabemos que su prevalencia es mayor de la considerada, disponemos de métodos diagnósticos no invasivos y están apareciendo tratamientos eficaces. En este contexto, la gammagrafía cardíaca (GC) con difosfonatos marcados con 99mTc ha alcanzado un inusitado interés al mostrar alta sensibilidad y especificidad para el diagnóstico no invasivo y fiable de la ATTR. Este artículo, a modo de guía, pretende identificar los componentes críticos en la realización de la GC que resulten de utilidad en la práctica clínica diaria y, así, ayudar a los especialistas a utilizar los radiofármacos idóneos, obtener las imágenes más adecuadas, interpretar los resultados de estas y conocer los escenarios clínicos en los que resulta apropiado realizar la GC

Transthyretin cardiac amyloidosis (ATTR) has traditionally been considered a rare, difficult-to-diagnose and untreatable disease. However, its prevalence is known to be greater than what was previously thought, non-invasive diagnostic methods are available, and that effective treatments are emerging. In this context, cardiac scintigraphy (CS) with 99mTc-labelled diphosphonates has aroused a noticeable surge in interest by demonstrating high sensitivity and specificity for the reliable, non-invasive diagnosis of ATTR. By way of a guide, this article aims to identify the critical components in the performance of CS that are useful in everyday clinical practice and, thus, help specialists use optimal radiopharmaceuticals, obtain the most appropriate images, interpret the results thereof, and acquaint themselves with those clinical scenarios in which it is convenient to perform CS

Effect of the CXCR4 antagonist plerixafor on endogenous neutrophil dynamics in the bone marrow, lung and spleen.

Treatment with the CXCR4 antagonist, plerixafor (AMD3100), has been proposed for clinical use in patients with WHIM (warts, hypogammaglobulinemia, infections, and myelokathexis) syndrome and in pulmonary fibrosis. However, there is controversy with respect to the impact of plerixafor on neutrophil dynamics in the lung, which may affect its safety profile. In this study, we investigated the kinetics of endogenous neutrophils by direct imaging, using confocal intravital microscopy in mouse bone marrow, spleen, and lungs. Neutrophils are observed increasing their velocity and exiting the bone marrow following plerixafor administration, with a concomitant increase in neutrophil numbers in the blood and spleen, while the marginated pool of neutrophils in the lung microvasculature remained unchanged in terms of numbers and cell velocity. Use of autologous radiolabeled neutrophils and SPECT/CT imaging in healthy volunteers showed that plerixafor did not affect GM-CSF-primed neutrophil entrapment or release in the lungs. Taken together, these data suggest that plerixafor causes neutrophil mobilization from the bone marrow but does not impact on lung marginated neutrophil dynamics and thus is unlikely to compromise respiratory host defense both in humans and mice.

A novel peptide targeting gastrin releasing peptide receptor for pancreatic neoplasm detection.

Pancreatic cancer has a high mortality rate and efforts towards diagnosis and therapy at an early stage are particularly appealing. Recently, a small peptide, BBN7-14, has attracted much attention for its specific binding ability to gastrin releasing peptide receptor (GRPR), which is highly overexpressed in various types of cancer, including pancreatic cancer. However, its poor stability in vivo restricts its direct clinical application. Herein, by rational design and transformation of BBN7-14, a novel six-amino acid peptide, GB-6, which maintains a specific GRPR-binding feature and exhibits enhanced stability in vitro and in vivo, was designed. Competitive binding with BBN7-14 and cellular uptake related to GRPR expression levels verified the specific affinity of GB-6 to GRPR. Additionally, this novel peptide was conjugated with near-infrared dye and the radionuclide 99mTc for pancreatic cancer diagnosis in cells and in vivo. Surprisingly, despite having the same cellular affinity as BBN7-14, GB-6 showed much higher pancreatic cancer-targeting ability than BBN7-14 by both fluorescence imaging and radionuclide imaging. It was proven that this strange phenomenon was attributed to the distinct in vivo stability of GB-6 and its more favorable pharmacokinetic properties and metabolic stability relative to BBN7-14. Altogether, this novel peptide GB-6, with GRPR-targeting ability and enhanced stability, is a more promising candidate for the clinical diagnosis of pancreatic cancer.

Preparation, radiolabeling with 99mTc and 67Ga and biodistribution studies of albumin nanoparticles covered with polymers. / Preparación, radiomarcaje con 99mTc y 67Ga y estudios de biodistribución de nanopartículas de albúmina con recubrimientos poliméricos.

OBJECTIVE: To optimize radiolabeling with 99mTc and 67Ga of albumin nanoparticles coated with 4 differents synthetic polymers and to evaluate their stability in vivo and in vitro, as well as their biodistribution in vivo after intravenous administration. MATERIAL AND METHODS: The nanoparticles were prepared using albumin and NOTA-modified albumin by the desolvation method and coated with 4 different polymers; HPMC, GMN2, GPM2 and GTM2. They were purified, lyophilized and characterized. Radiolabelling with 99mTc was perfomed with 74 MBq of 99mTc sodium pertechnetate, previously reduced with and acid solution of tin chloride at different concentrations (0.003, 0.005, 0.007, 0.01, 0.05 and 0.1mg/ml) and at different times (5, 10, 15, 30 and 60minutes) and temperatures (room temperature, 40°C and 60°C). Radiolabelling with 67Ga was perfomed by incubation of the nanoparticles with 37 MBq of 67Gallium chloride (obtained from commercial gallium-67 citrate) at different times (10 and 30minutes) and temperatures (room temperature, 30°C and 60°C), and posterior purification with microconcentrators. The radiochemical purity was evaluated by TLC. Stability studies of radiolabeled nanoparticles in physiological serum and blood plasma were perfomed. Biodistribution studies of nanoparticles coated with GPM2 polymer were carried out in Wistar rats after intravenous administration of the nanoparticles. Control animals were carried out with 99mTc sodium pertechnetate and 67Ga chloride. To do so, the animals were killed and activity in organs was measured in a gamma counter. RESULTS: 99mTc labeling was carried out optimally with a tin concentration of 0.007mg/ ml for the GPM2 nanoparticles and 0.005mg / ml for the rest of the formulations, with a radiolabelling time of 10minutes at room temperature. In the case of 67Ga the label was optimized at 30° C temperature and 30minutes of incubation. In both cases the radiochemical purity obtained was greater than 97%. The nanoparticles showed high stability in vitro after 48hours of labeling (70% nanoparticles labeled with 99mTc and 90% those labeled with 67Ga). Biodistribution studies of nanoparticles 99mTc -GPM2 and 67Ga -NOTA-GPM2 showed a high accumulation of activity in the liver at 2 and 24hours after intravenous administration. CONCLUSION: The labeling procedure with 99mTc and 67Ga of albumin and albumin modified with NOTA nanoparticles allows obtaining nanoparticles with high labeling yields and adequate in vitro stability, allowing their use for in vivo studies.

Sentinel lymph node mapping in endometrial cancer: performance of hysteroscopic injection of tracers.

OBJECTIVE: To report on the performance of hysteroscopic injection of tracers (indocyanine green (ICG) and technetium-99m (Tc-99m)) for sentinel lymph node (SLN) mapping in endometrial cancer. METHODS: Single-center retrospective evaluation of consecutive patients who underwent SLN mapping following hysteroscopic peritumoral injection of tracer. Detection rate (overall/bilateral/aortic) diagnostic accuracy, and oncologic outcomes were evaluated. RESULTS: A total of 221 procedures met the inclusion criteria. Mean patient age was 60 (range 28-84) years and mean body mass index was 26.9 (range 15-47) kg/m2 . In 164 cases (70.9%) mapping was performed laparoscopically. The overall detection rate of the technique was 94.1% (208/221 patients). Bilateral pelvic mapping was found in 62.5% of cases with at least one SLN detected and was more frequent using ICG than with Tc-99m (73.8% vs 53.3%; p<0.001). In 47.6% of cases SLNs mapped in both pelvic and aortic nodes, and in five cases (2.4%) only in the aortic area. In eight patients (3.8%) SLNs were found in aberrant (parametrial/presacral) areas. Mean number of detected SLNs was 3.7 (range 1-8). In 51.9% of cases at least one node other than SLNs was removed. Twenty-six patients (12.5%) had nodal involvement: 12 (46.2%) macrometastases, six (23.1%) micrometastases, and eight (30.7%) isolated tumor cells. In 12 cases (46.8%) the aortic area was involved. Overall, 6/221 (2.7%) patients had isolated para-aortic nodes. Three false-negative results were found, all in the Tc-99m group. All had isolated aortic metastases. Overall sensitivity was 88.5% (95% CI 71.7 to 100.0) and overall negative predictive value was 96.5% (95% CI 86.8 to 100.0). There were 10 (4.8%) recurrences: five abdominal/distant, four vaginal, and one nodal (in the aortic area following a unilateral mapping plus side-specific pelvic lymphadenectomy). Most recurrences (9/10 cases) were patients in whom a completion lymphadenectomy was performed. No deaths were reported after a mean follow-up of 47.7 months. CONCLUSIONS: Hysteroscopic injection of tracers for SLN mapping in endometrial cancer is as accurate as cervical injection with a higher detection rate in the aortic area. ICG improves the bilateral detection rate. Adding lymphadenectomy to SLN mapping does not reduce the risk of relapse.

Development and characterization of a 99m Tc-labeled Neuropeptide Y short analog with potential application in breast cancer imaging.

The aim of this work was to develop and evaluate a 99m Tc-labeled neuropeptide Y derivative with affinity toward Y1-receptor. The selected amino acid sequence included nine amino acids derived from the C-terminal portion of the NPY complemented with the addition of one cysteine-mercaptoacetic acid moiety to bind the radiometal. Labeling was achieved through the preparation of a 3 + 1 nitrido complex. Physicochemical evaluation, cell uptake, internalization and externalization studies, and competitive assays were performed. Biodistribution experiments were carried out in normal and tumor-bearing mice. A single product with radiochemical purity >90% and high stability was obtained. In vitro analysis showed specific cellular uptake, IC50 of 73.2 nM, and a high internalization rate (80%). Biodistribution studies showed low blood and renal uptake and combined hepatobiliary and urinary elimination. Preliminary studies in mice bearing induced breast tumors rendered promising uptake values.