Sentinel node in breast cancer procedural guidelines

Survival and inferential analysis in patients with locally advanced breast cancer treated with neoadjuvant chemotherapy and subsequent sentinel lymph node biopsy: prospective single-center study

BACKGROUND

The lymph node staging is the major prognostic factor in breast cancer patients. Sentinel lymph node biopsy (SLNB) allows an exactly axillar staging in patients with early disease, but not in locally advance breast cancer (LABC). Our aim was to study, the feasibility and accuracy of the SLNB technique with and without axillar lymphadenectomy (LDN) and with lymph node clipping after neoadjuvant chemotherapy (NAC), in patients with LABC.

PATIENTS AND METHODS

Patients diagnosed with LABC, scheduled for NAC and subsequent surgery and SLNB. Subsequently the patients were scheduled for adjuvant chemotherapy/hormonotherapy and radiotherapy according with the postsurgical results. Main end points were overall survival (OS) disease-free survival (DFS), mortality, SLNB identification rate (IR), sensitivity, false negative rate (FNR) of SLNB versus LDN, negative predictive value (NPV) and overall accuracy.

RESULTS

Our IR with different techniques was between 89.9 and 100%. OS was between 89 and 97%. DFS was between 89.8 and 96.8%. Sensitivity was between 75 and 100%. NPV was between 89.6 and 100%. FNR was between 0 and 25%; and accuracy was between 66 and 72%. We found that survival was lower (p < 0.05) in patients with triple negative and Luminal B/HER2 intrinsic subtype; with progression or major partial response in Magnetic Resonance Imaging (MRI) results at the end of NAC and in patients with BRCA1/2 mutation.

CONCLUSIONS

Our study presents excellent results of SLNB alone in patients with LABC with complete nodal response with an OS and DFS > 95%. The FNR is very high in partial responders, so we cannot recommend the SLNB alone in LABC. We recommend, in cN+ patients, axillar clipping, SLNB and LDN because in more than 50% of the patients with axillar clipping, this was not found, and because in 36% of the patients with negative LDN, the SLN (Sentinel Lymph Node) obtained was the only positive node, so these techniques together decrease the FNR and improve the node staging, OS and DFS. This study is the first prospective study that assess OS and DFS in patients with LABC, all submitted to SLNB.

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.

Role of methylene blue dye in sentinel node biopsy in N0 oral cavity squamous cell carcinoma

BACKGROUND

Presence of neck nodes in cases of head neck squamous cell cancers is an adverse prognostic factor. Elective neck dissection is traditionally recommended along with primary disease resection. Sentinel lymph node (SLN) is the first draining node. Sentinel lymph node biopsy (SNB) is a minimally invasive technique to identify occult nodal metastasis in early HNSCC.

METHODS

The objective of this study is to determine the identification rate of SNB using methylene blue dye (MBD) in N0 neck of Oral Squamous cell carcinoma (OSCC) and estimating specificity, sensitivity, negative predictive value and positive predictive value of SNB with frozen section (FS) analysis and in comparison to post-operative histopathological examination (HPE). It is a cross-sectional study conducted at a tertiary care centre, Lucknow, India. 21 patients of N0 OSCC from January 2019 to May 2020, were included. All patients underwent peritumoral injection with MBD. Sentinel nodes were harvested and sent for FS. Depending on FS findings, appropriate neck dissection was performed.

RESULTS

SLN was identified at level Ib and II in 19 patients (90.47%). The sensitivity, specificity, PPV and NPV in identifying SLN using MBD versus FS were 100.00%, 11.11%, 15.79% and 100.00% respectively. Whereas, SLN using MBD versus HPE specimens were 100.00%, 10.52%, 10.52% and 100.00% respectively.

CONCLUSION

Despite having 100% sensitivity, MBD alone has poor specificity. With this poor discriminatory power, it is unlikely to be employed as a diagnostic test alone. It is recommended to rely on per-operative FS for taking decision as far as extent of neck dissection in N0 neck is concerned.

Preclinical Identification Of Tumor-Draining Lymph Nodes Using a Multimodal Non-invasive In vivo Imaging Approach

PURPOSE

Resection of the tumor-draining lymph -node (TDLN) represents a standard method to identify metastasis for several malignancies. Interestingly, recent preclinical studies indicate that TDLN resection diminishes the efficacy of immune checkpoint inhibitor-based cancer immunotherapies. Thus, accurate preclinical identification of TDLNs is pivotal to uncovering the underlying immunological mechanisms. Therefore, we validated preclinically, and clinically available non-invasive in vivo imaging approaches for precise TDLN identification.

PROCEDURES

For visualization of the lymphatic drainage into the TDLNs by non-invasive in vivo optical imaging, we injected the optical imaging contrast agents Patent Blue V (582.7 g mol^-1) and IRDye® 800CW polyethylene glycol (PEG; 25,000-60,000 g mol^-1), subcutaneously (s.c.) in close proximity to MC38 adenocarcinomas at the right flank of experimental mice. For determination of the lymphatic drainage and the glucose metabolism in TDLNs by non-invasive in vivo PET/magnetic resonance imaging (PET/MRI), we injected the positron emission tomography (PET) tracer (2-deoxy-2[¹⁸F]fluoro-D-glucose (¹⁸F-FDG) [181.1 g mol^-1]) in a similar manner. For ex vivo cross-correlation, we isolated TDLNs and contralateral nontumor-draining lymph nodes (NTDLNs) and performed optical imaging, biodistribution, and autoradiography analysis.

RESULTS

The clinically well-established Patent Blue V was superior for intraoperative macroscopic identification of the TDLNs compared with IRDye® 800CW PEG but was not sensitive enough for non-invasive in vivo detection by optical imaging. Ex vivo Patent Blue V biodistribution analysis clearly identified the right accessory axillary and the proper axillary lymph node (LN) as TDLNs, whereas ex vivo IRDye® 800CW PEG completely failed. In contrast, functional non-invasive in vivo ¹⁸F-FDG PET/MRI identified a significantly elevated uptake exclusively within the ipsilateral accessory axillary TDLN of experimental mice and was able to differentiate between the accessory axillary and the proper LN. Ex vivo biodistribution and autoradiography confirmed our in vivo ¹⁸F-FDG PET/MRI results.

CONCLUSIONS

When taken together, our results demonstrate the feasibility of ¹⁸F-FDG-PET/MRI as a valid method for non-invasive in vivo, intraoperative, and ex vivo identification of the lymphatic drainage and glucose metabolism within the TDLNs. In addition, using Patent Blue V provides additive value for the macroscopic localization of the lymphatic drainage both visually and by ex vivo optical imaging analysis. Thus, both methods are valuable, easy to implement, and cost-effective for preclinical identification of the TDLN.

Sentinel Lymph Node Methods in Breast Cancer

Breast cancer is the most frequent cancer diagnosed in women worldwide. Accurate lymph node staging is essential for both prognosis (of early-stage disease) and treatment (for regional control of disease) in patients with breast cancer. The sentinel lymph nodes are the regional nodes that directly drain lymph from the primary tumor. No imaging modality is accurate enough to detect lymph node metastases when a primary breast cancer is at an early stage (I or II), but sentinel lymph node biopsy is a highly reliable method for screening axillary nodes and for identifying metastatic (including micro-metastatic) disease in regional lymph nodes. Despite the widespread use of sentinel lymph node biopsy for early-stage breast cancer, relevant variations have been described regarding practical aspects of the procedure, and some variability has initially been reported regarding the rates of intraoperative sentinel lymph node identification and of false-negative findings, most likely because of differences in the size of the populations being investigated and in lymphatic mapping techniques. Nevertheless, using adequate learning curves and once a multidisciplinary team is experienced with the procedure, improved levels of accuracy are achieved.

Sentinel lymph node biopsy for high-thickness cutaneous squamous cell carcinoma

Squamous cell carcinomas are among the most common skin tumors and show a risk of metastasis depending on various factors such as tumor thickness, localization, histological subtype and immune status of the patient. Sentinel lymph node biopsy (SLNB) SLNB represents a possibility for assessing the locoregional lymph node status. In this study, the role of the SLNB in lymph node status and survival was analyzed. Retrospectively, 720 patients with high-risk squamous cell carcinoma (tumor thickness > 5 mm) were examined. 150 patients agreed to SLNB, 570 patients did not undergo histologic confirmation of lymph node status and were included directly in follow-up. In 101 patients, a sentinel lymph node was successfully marked and extirpated, followed by regular follow-up examinations.A total of 11.11% of the patients showed lymph node metastasis in the course of their treatment, with no difference in the proportion of patients in the SLNB group (11.9%) and the observation group (11.4%) (p = 0.873). The proportion of distant metastasis also did not differ between the groups (p = 0.898). In 3.96% of the patients in the SLNB group, a metastasis was found in the sentinel lymph node. Tumor-specific death was observed in 7.14% of the patients in the SLNB group and 4.74% in the observation group (p = 0.269). Although SLNB is a principally suitable method for determining lymph node status, the available data do not provide any benefit regarding further metastasis or tumor-specific survival.

New Frontiers in Molecular Imaging with Superparamagnetic Iron Oxide Nanoparticles (SPIONs): Efficacy, Toxicity, and Future Applications

Supermagnetic Iron Oxide Nanoparticles (SPIONs) are nanoparticles that have an iron oxide core and a functionalized shell. SPIONs have recently raised much interest in the scientific community, given their exciting potential diagnostic and theragnostic applications. The possibility to modify their surface and the characteristics of their core make SPIONs a specific contrast agent for magnetic resonance imaging but also an intriguing family of tracer for nuclear medicine. An example is 68Ga-radiolabeled bombesin-conjugated to superparamagnetic nanoparticles coated with trimethyl chitosan that is selective for the gastrin-releasing peptide receptors. These receptors are expressed by several human cancer cells such as breast and prostate neoplasia. Since the coating does not interfere with the properties of the molecules bounded to the shell, it has been proposed to link SPIONs with antibodies. SPIONs can be used also to monitor the biodistribution of mesenchymal stromal cells and take place in various applications. The aim of this review of literature is to analyze the diagnostic aspect of SPIONs in magnetic resonance imaging and in nuclear medicine, with a particular focus on sentinel lymph node applications. Moreover, it is taken into account the possible toxicity and the effects on human physiology to determine the SPIONs' safety.

Lymphoscintigraphy for Sentinel Lymph Node Biopsy in Breast Cancer: Do We Need a Delayed Image?

Background

Sentinel lymph node biopsy has become a standard of care in the treatment of patients with early breast cancer, but clinical guidelines continue to be vague on details of the procedure. We were interested in the results of our 2-day protocol, which includes delayed lymphoscintigraphy at 18 h.

Methods

We reviewed the results of preoperative lymphoscintigrams in patients undergoing surgery for breast cancer. Lymphoscintigraphy was performed 2 h after periareolar injection of 4 × 37 MBq ^99mTc nanocolloid (early lymphoscintigraphy) and 18 h following injection (delayed lymphoscintigraphy). The early results were compared with the late results.

Results

A total of 238 lymphoscintigraphies were performed in 232 patients (6 bilateral). At 2 h, ≥1 sentinel nodes were visualized in 154/238 (65%) cases; in 84 (35%), no sentinel node was visualized. Delayed lymphoscintigraphy visualized a sentinel node in 40 of 76 (53%) cases with no visualization at 2 h and failed to show a sentinel node in 36 (47%) of these cases (in 8 cases, no delayed lymphoscintigram was obtained).

Conclusions

Delayed lymphoscintigraphy was useful in about 50% of the breast cancer patients in whom immediate scintigraphy failed to demonstrate a sentinel lymph node.

Local-Regional Metastases and Mortality After Sentinel Biopsy and Complete Dissection of Axillary Lymph Nodes in Patients with Early Invasive Breast Cancer

INTRODUCTION

Current, standard procedure for evaluation of axillary lymph node pathological (PH) status has been sentinel lymph node biopsy (SLNB). To demonstrate the long-term validity of sentinel lymph node biopsy (SLNB) using the radioactive isotope only Technetium 99m albumin-colloid (Tc99m) we compared the loco-regional recurrence and mortality of breast cancer patients with negative SLNB without axillary lymph node dissection (ALND) (SLNB group) to that of lymph node-positive patients undergoing ALND (ALND group).

AIM

The aim of our study is to evaluate the results of long-term monitoring of patients with early invasive breast cancer in which the radio-actively guided axillary SLN biopsy and complete ALND were studied, with special emphasis on local-regional recurrence and mortality.

PATIENTS AND METHODS

We studied a total of 63 patients with T1-2early invasive breast cancer diagnosed at Clinic for general and abdominal surgery, Clinical Center University of Sarajevo (CCUS) between 2004 and 2007, with follow-up till 2013, retrospectively, who met the criteria for inclusion. Preoperative peritumorous injection of radioactive isotope (Tc99m albumin-colloid) is done on the Clinic for Endocrine and Nuclear Medicine-CCUS. Intra and postoperative pathohistological (PH)examination of SLN node (or nodes) and PH examination of lymph nodes after complete ALND was done at the Clinic for Clinical Pathology and Cytology-CCUS. Statistical evaluation was done by statistical program MedCalc Statistical Software, version 18.10. Depending on the given variables were used: mean, standard deviation, median values, 95% CI for median value, Chi-square test, D'Agostino-Pearson test, Kaplan-Maier curve of survival. Defined level of significance was p<0,05.

RESULTS

The SLNB group consisted of 33 SLN-negative women and ALND group consisted of 30 axillary lymph node-positive women. The sentinel node identification rate was 100%. In the SLNB group no patients has developed axillary recurrence during the follow-up. The mortality rate in the SLNB group was equivalent to that in the ALND group.

CONCLUSIONS

The SLN biopsy conducted with only a radioactive isotope TC 99m have the same results as loco-regional recurrence and mortality as well as the complete ALND method and may be the method of choice for the treatment of axillary in breast cancer patients and the clinically negative axillary lymph node (or nodules) with the notion that patients should be micro metastases given special attention during long-term monitoring.

The influence of breast cancer subtypes on axillary ultrasound accuracy: A retrospective single center analysis of 583 women

INTRODUCTION

Axillary ultrasound staging (AUS) is an important tool to guide clinical decisions in breast cancer therapy, especially regarding axillary surgery but also radiation therapy. It is unknown whether biological subtypes influence axillary staging using ultrasound (AUS).

METHOD

This is a retrospective single center analysis. All patients with breast cancer, a preoperative axillary ultrasound and a complete surgical axillary staging were included between 1999 and 2014, except patients with neoadjuvant chemotherapy (NACT). The results of the AUS were compared with final pathological results. Biological subtypes were identified by immunohistochemistry.

RESULTS

583 women were included in the study. Sensitivity, Specificity, positive and negative predictive value for AUS were 39%, 96%, 91% and 83%. While sensitivity was significantly lower in Luminal A and B patients (25.0%; 39.8%) as compared to non Luminal breast cancer patients (TN 68.8%; Her2+ 71.4%; p = 0.0032), there were no significant differences between the groups with respect to specificity, PPV and NPV.

CONCLUSION

Solely regarding sensitivity of AUS, our study could show significant differences between biological subtypes of breast cancer with lower sensitivity in Luminal patients. While PPV was excellent, standing for a low overtreatment rate using AUS for clinical decision making, sensitivity was poor overall, comparable to the results of other studies.

Design and Synthesis of 99mTcN-Labeled Dextran-Mannose Derivatives for Sentinel Lymph Node Detection

Background: New approaches based on the receptor-targeted molecular interaction have been recently developed with the aim to investigate specific probes for sentinel lymph nodes. In particular, the mannose receptors expressed by lymph node macrophages became an attractive target and different multifunctional mannose derivate ligands for the labeling with ^99mTc have been developed. In this study, we report the synthesis of a specific class of dextran-based, macromolecular, multifunctional ligands specially designed for labeling with the highly stable [^99mTc≡N]²⁺ core. Methods: The ligands have been obtained by appending to a macromolecular dextran scaffold pendant arms bearing a chelating moiety for the metallic group and a mannosyl residue for allowing the interaction of the resulting macromolecular ^99mTc conjugate with specific receptors on the external membrane of macrophages. Two different chelating systems have been selected, S-methyl dithiocarbazate [H₂N‒NH‒C(=S)SCH₃=HDTCZ] and a sequence of two cysteine residues, that in combination with a monophosphine coligand, are able to bind the [^99mTc≡N]²⁺ core. Conclusions: High-specific-activity labeling has been obtained by simple mixing and heating of the [^99mTc≡N]²⁺ group with the new mannose-dextran derivatives.

Lymphatic Drainage of the Splenic Flexure Defined by Intraoperative Scintigraphic Mapping

BACKGROUND

The optimal surgical management of splenic flexure cancer is debated, partly because of an incomplete understanding of the lymphatic drainage of this region.

OBJECTIVE

This study aimed to evaluate the normal lymphatic drainage of the human splenic flexure using laparoscopic scintigraphic mapping.

DESIGN

This was a clinical trial.

SETTINGS

The study was conducted at a single tertiary care center.

PATIENTS

Thirty consecutive patients undergoing elective colorectal resections without splenic flexure pathology were recruited.

INTERVENTION

Technetium-99m was injected subserosally at the splenic flexure.

MAIN OUTCOME MEASURES

Lymphatic scintigraphic mapping was undertaken at 15, 30, and 60 minutes using a laparoscopic gamma probe at the left branch of the middle colic, left colic, inferior mesenteric, and ileocolic (control) lymphovascular pedicles.

RESULTS

Lymphatic drainage at 60 minutes was strongly dominant in the direction of the left colic pedicle (96% of patients), with a median gamma count of 284 (interquartile range, 113-413), versus the left branch of the middle colic count of 31 (interquartile range, 15-49; p < 0.0001). This equated to a median 9.2-times greater flow to the left colic versus the middle colic. Counts at the left colic were greater than all of the other mapped sites at 15, 30, and 60 minutes (p < 0.001), whereas middle colic and inferior mesenteric artery counts were equivalent. The protocol increased operative duration by 20 to 30 minutes without complications.

LIMITATIONS

These results report lymphatic drainage from patients with normal splenic flexures, and caution is necessary when extrapolating to patients with splenic flexure cancers.

CONCLUSIONS

The lymphatic drainage of the normal splenic flexure is preferentially directed toward the left colic in the high majority of cases. Retrieving these nodes should be prioritized in splenic flexure cancer resections, with important secondary emphasis on left middle colic nodes, supporting segmental (left hemicolectomy) resection as the procedure of choice. Additional development of colonic sentinel node mapping using these techniques may contribute to individualized surgical therapy morbidity. See Video Abstract at http://links.lww.com/DCR/A495.

Combined Magnetomotive ultrasound, PET/CT, and MR imaging of 68Ga-labelled superparamagnetic iron oxide nanoparticles in rat sentinel lymph nodes in vivo

Current methods for intra-surgical guidance to localize metastases at cancer surgery are based on radioactive tracers that cause logistical challenges. We propose the use of a novel ultrasound-based method, magnetomotive ultrasound (MMUS) imaging that employ a nanoparticle-based contrast agent that also may be used for pre-operative PET/MRI imaging. Since MMUS is radiation free, this eliminates the dependence between pre- and intra-operative imaging and the radiation exposure for the surgical staff. This study investigates a hypothetical clinical scenario of pre-operative PET imaging, combined with intra-operative MMUS imaging, implemented in a sentinel lymph node (SLN) rat model. At one-hour post injection of ⁶⁸Ga-labelled magnetic nanoparticles, six animals were imaged with combined PET/CT. After two or four days, the same animals were imaged with MMUS. In addition, ex-vivo MRI was used to evaluate the amount of nanoparticles in each single SLN. All SLNs were detectable by PET. Four out of six SLNs could be detected with MMUS, and for these MMUS and MRI measurements were in close agreement. The MRI measurements revealed that the two SLNs undetectable with MMUS contained the lowest nanoparticle concentrations. This study shows that MMUS can complement standard pre-operative imaging by providing bedside real-time images with high spatial resolution.

Development of sentinel node biopsy, ROLL and IART in early breast cancer at the European Institute of Oncology, Milan (IEO)

The problem of unnecessary axillary clearance in many patients with early breast cancer was certainly a major issue at IEO when we started working with Prof. Umberto Veronesi in 1994. At that time, axillary dissection in EBC was offered to all patients and this procedure was often hotly debated during our multidisciplinary breast cancer meetings. The question as to whether we could avoid axillary dissection by using PET scans or other nuclear medicine methods was frequently asked by Veronesi. This eventually prompted us to investigate whether, as for melanoma patients, the sentinel node biopsy (SNB) approach could reliably be applied to breast cancer. In December 1995, we proposed a new lymphoscintigraphy protocol to detect the SN in early breast cancer patients to our Ethic Committee, and it was approved. The pilot study was published in 1997 and after only 6 years, the first randomised trial comparing SNB and axillary clearance in breast cancer patients was published. During the pilot study, we optimised the lymphoscintigraphy technique by comparing different radiotracers and different injection modalities. Following the observation that the majority of the radiocolloids injected into the tumour did not migrate to lymph nodes, a new method called ROLL or Radio-guided Occult Lesion Localisation was developed for the localisation of non-palpable breast lesions. This technique was introduced into clinical practice at the European Institute of Oncology in 1996. Several studies showed that the ROLL procedure enabled the surgeon to remove non-palpable breast lesions easily and accurately, overcoming some disadvantages of other methods such as wire-guided localisation (WGL). In addition to SNB and ROLL, other protocols such as the IART (intraoperative avidination for radionuclide therapy)-ARTHE (avidinated radiotherapy) procedure were developed at the IEO Nuclear Medicine Division during the period 1994–2013. I remember that time as the most professionally productive of my career and it would not have been possible without the help, suggestions and encouragement given to me by Umberto Veronesi.

Contribution of SPECT/CT for sentinel node localization in patients with ipsilateral breast cancer relapse

Background

In recent years repeat sentinel node (SN) biopsy has been proven to be feasible in local breast cancer recurrence (LBCR). However, in these patients SNs outside the ipsilateral axilla are frequently observed. This study evaluates the contribution of SPECT/CT for SN localization and surgical adjustment in LBCR patients.

Methods

SN biopsy was performed in 122 LBCR patients (median age 60.5 years, range 24–87), enrolled from August 2006 to July 2015. Median disease-free time lapse was 109.5 months (range 9–365). Axillary lymph node dissection (ALND) had previously been performed in 55 patients, SN biopsy in 44, both techniques in 13 and fine-needle aspiration in 10. Primary breast cancer treatment included radiotherapy in 104 patients (85.3 %) and chemotherapy in 40 (32.8 %). Preoperative lymphatic mapping, using planar scintigraphy (PS) and SPECT/CT included report of SN location according to lymph node territory. In case of a territorial PS-SPECT/CT mismatch, surgery was adjusted according to SPECT/CT findings.

Results

SPECT/CT SN visualization rate was higher than PS (53.3 % vs. 43.4 %, p n.s.) with, in total, 19 additional SN (118 vs. 99, p n.s.). PS-SPECT/CT territory mismatch, found in 60 % (39/65) of patients with SN visualization, led to surgical adjustment in 21.3 % (26/122) of patients. The SN procedure was finally performed in 104 patients resulting in a 65.7 % surgical retrieval rate with a total of 132 removed SNs (1.86/patient). SN metastases were found in 17/71 patients (23.9 %), in 16 of them (94 %) in ipsilateral basins outside the axilla or in the contralateral axilla.

Conclusion

Using SPECT/CT there is a trend to visualize more SNs in LBCR, providing at the same time important anatomical information to adjust intraoperative SN procedures. The addition of SPECT/CT to the standard imaging protocol may lead to better staging mainly in patients presenting drainage outside the ipsilateral axilla.

A study on the value of computer-assisted assessment for SPECT/CT-scans in sentinel lymph node diagnostics of penile cancer as well as clinical reliability and morbidity of this procedure

BACKGROUND

Because of the increasing importance of computer-assisted post processing of image data in modern medical diagnostic we studied the value of an algorithm for assessment of single photon emission computed tomography/computed tomography (SPECT/CT)-data, which has been used for the first time for lymph node staging in penile cancer with non-palpable inguinal lymph nodes. In the guidelines of the relevant international expert societies, sentinel lymph node-biopsy (SLNB) is recommended as a diagnostic method of choice. The aim of this study is to evaluate the value of the afore-mentioned algorithm and in the clinical context the reliability and the associated morbidity of this procedure.

METHODS

Between 2008 and 2015, 25 patients with invasive penile cancer and inconspicuous inguinal lymph node status underwent SLNB after application of the radiotracer Tc-99m labelled nanocolloid. We recorded in a prospective approach the reliability and the complication rate of the procedure. In addition, we evaluated the results of an algorithm for SPECT/CT-data assessment of these patients.

RESULTS

SLNB was carried out in 44 groins of 25 patients. In three patients, inguinal lymph node metastases were detected via SLNB. In one patient, bilateral lymph node recurrence of the groins occurred after negative SLNB. There was a false-negative rate of 4 % in relation to the number of patients (1/25), resp. 4.5 % in relation to the number of groins (2/44). Morbidity was 4 % in relation to the number of patients (1/25), resp. 2.3 % in relation to the number of groins (1/44). The results of computer-assisted assessment of SPECT/CT data for sentinel lymph node (SLN)-diagnostics demonstrated high sensitivity of 88.8 % and specificity of 86.7 %.

CONCLUSIONS

SLNB is a very reliable method, associated with low morbidity. Computer-assisted assessment of SPECT/CT data of the SLN-diagnostics shows high sensitivity and specificity. While it cannot replace the assessment by medical experts, it can still provide substantial supplement and assistance.

Preoperative Sentinel Node Mapping in Sentinel Node Biopsy in Early Breast Cancers - Is It Cost-Effective?

INTRODUCTION

Sentinel lymph node (SLN) biopsy is currently the gold standard of treatment in early breast cancers. Identification of SLNs by preoperative scintigraphy has been carried out to improve the detection of SLNs intraoperatively, but the evidence of its cost-effectiveness is lacking. Here, we analyze the cost-effectiveness of the utilization of scintigraphy in detection of SLNs.

PATIENTS AND METHODS

Clinical and operative details were retrieved from a prospectively maintained database. The resources and cost data from each patient who had undergone SLN biopsy with preoperative scintigraphy were retrieved.

RESULTS

From January 2008 to December 2012, 400 patients underwent SLN biopsy for breast cancer. A total of 329 had preoperative SLN mapping with scintigraphy, Baseline patient demographic data for both arms were comparable. The relapse and recurrence rate of both arms were not statistically different. The detection rate of SLNs of both arms was the same (100%), and there were no grade 2 or above lymphedema in both groups of patients. However, the cost of each patient undergoing SLN mapping was USD $345.8.

CONCLUSION

Preoperative SLN mapping does not improve the SLN detection rate. In addition, it does not affect the surgical outcomes in terms of complication, local relapse, and recurrence. The use of preoperative SLN mapping is no longer cost-effective.

Assessment of the performance of small field of view gamma cameras for sentinel node imaging

OBJECTIVE

To develop a method for the assessment of small field of view (SFOV) gamma cameras using a novel phantom designed to simulate the localization of sentinel nodes in the presence of a high-activity injection site.

MATERIALS AND METHODS

The phantom consisted of a cube-shaped acrylic glass support frame. Sixteen acrylic glass plates and nine bars were stacked within the frame to allow a variable configuration of the simulated node depth and node-to-injection site separation. Syringes filled with Tc were used to simulate activity at the injection site and node. Scintigraphic imaging was carried out and the images were assessed subjectively and quantitatively through calculation of the contrast-to-noise ratio. The detection performance of an SFOV gamma camera was then compared with that of a large field of view gamma camera.

RESULTS

The detectability studies showed that the SFOV gamma camera could detect low activity in nodes by visual examination of images and with contrast-to-noise ratios ranging from 3 to 62. In particular, the phantom showed the limits of node detection using an SFOV gamma camera over activity ratios less than 1 : 100 and at depths below 45 mm with 25 mm of node-to-injection site separation. Visual subjective assessment of images acquired under the same conditions showed that the SFOV gamma camera was superior to a large field of view camera for the detection of nodes at a node-to-injection site separation of 25 mm.

CONCLUSION

A low-cost phantom has been designed and fabricated that provides a versatile method for the assessment of SFOV gamma cameras intended for sentinel node imaging.

The role of ultrasound and lymphoscintigraphy in the assessment of axillary lymph nodes in patients with breast cancer

Breast cancer is the most common malignancy and the leading cause of death due to cancer in European women. Mammography screening programs aimed to increase the detection of early cancer stages were implemented in numerous European countries. Recent data show a decrease in mortality due to breast cancer in many countries, particularly among young women. At the same time, the number of sentinel node biopsy procedures and breast-conserving surgeries has increased. Intraoperative sentinel lymph node biopsy preceded by lymphoscintigraphy is used in breast cancer patients with no clinical signs of lymph node metastasis. Due to the limited sensitivity and specificity of physical examination in detecting metastatic lesions, developing an appropriate diagnostic algorithm for the preoperative assessment of axillary lymph nodes seems to be a challenge. The importance of ultrasound in patient qualification for sentinel lymph-node biopsy has been discussed in a number of works. Furthermore, different lymphoscintigraphy protocols have been compared in the literature. The usefulness of novel radiopharmaceuticals as well as the methods of image acquisition in sentinel lymph node diagnostics have also been assessed. The aim of this article is to present, basing on current guidelines, literature data as well as our own experience, the diagnostic possibilities of axillary lymph node ultrasound in patient qualification for an appropriate treatment as well as the role of lymphoscintigraphy in sentinel lymph node biopsy.

Preoperative Scintigrams to Identify the Sentinel Lymph Node in Breast Cancer: a Waste of Time?

Sentinel lymph node biopsy (SLNB) remains the gold standard for assessing axillary node status in breast cancer. Preoperative scintigrams have been used to identify the sentinel lymph node (SLN); however, their use is controversial. Studies suggest they add little to successful SLN detection in theatre, immediately prior to node excision. They have been associated with high false negatives, time expense, patient dissatisfaction, and unnecessary costs. The aim of the present study was to evaluate the diagnostic accuracy of scintigrams in comparison to intraoperative SLN identification techniques. This study included all patients undergoing a SLNB for breast cancer from April 2010 to 2011. Scintigram reports, operation notes, and histology results were analyzed. Mann-Whitney U and chi-squared tests were used for statistical analysis of data. Two hundred nineteen female patients with a median age of 59.6 years (24.0-89.9 years) were included in this study. Scintigram was performed in 185 and not in 34 patients due to time constraints. Combined γ-probe and Isosulfan blue dye for SLN detection (intraoperative methods) have an identification rate of 98.2 % (p = 0.005), compared to 92.4 % (p = 0.088) from scintigrams alone. Scintigrams confer no additional advantage to the operating surgeon for successful SLN detection and excision in theatre. Intraoperative SLN identification is more accurate and reliable. Routine scintigram use is unjustified and should be withdrawn from current practice.

The Added Value of a Single-photon Emission Computed Tomography-Computed Tomography in Sentinel Lymph Node Mapping in Patients with Breast Cancer and Malignant Melanoma

Single-photon emission computed tomography-computed tomography (SPECT-CT) allows for physiological and anatomical co-registration in sentinel lymph node (SLN) mapping and offers additional benefits over conventional planar imaging. However, the clinical relevance when considering added costs and radiation burden of these reported benefits remains somewhat uncertain. This study aimed to evaluate the possible added value of SPECT-CT and intra-operative gamma-probe use over planar imaging alone in the South African setting. 80 patients with breast cancer or malignant melanoma underwent both planar and SPECT-CT imaging for SLN mapping. We assessed and compared the number of nodes detected on each study, false positive and negative findings, changes in surgical approach and or patient management. In all cases where a sentinel node was identified, SPECT-CT was more accurate anatomically. There was a significant change in surgical approach in 30 cases - breast cancer (n = 13; P 0.001) and malignant melanoma (n = 17; P 0.0002). In 4 cases a node not identified on planar imaging was seen on SPECT-CT. In 16 cases additional echelon nodes were identified. False positives were excluded by SPECT-CT in 12 cases. The addition of SPECT-CT and use of intra-operative gamma-probe to planar imaging offers important benefits in patients who present with breast cancer and melanoma. These benefits include increased nodal detection, elimination of false positives and negatives and improved anatomical localization that ultimately aids and expedites surgical management. This has been demonstrated in the context of industrialized country previously and has now also been confirmed in the setting of a emerging-market nation.

[Sentinel node in melanoma and breast cancer. Current considerations]

The main objectives of sentinel node (SN) biopsy is to avoid unnecessary lymphadenectomies and to identify the 20-25% of patients with occult regional metastatic involvement. This technique reduces the associated morbidity from lymphadenectomy and increases the occult lymphatic metastases identification rate by offering the pathologist the or 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 localize unpredictable lymphatic drainage patterns. The SPECT/CT advantages include a better SN detection rate than planar images, the ability to detect SNs in difficult to interpret studies, better SN depiction, especially in sites closer to the injection site and better anatomic localization. These advantages may result in a change in the patient's clinical management both in melanoma and breast cancer. The correct SN evaluation by pathology implies a tumoral load stratification and further prognostic implication. The use of intraoperative imaging devices allows the surgeon a better surgical approach and precise SN localization. Several studies reports the added value of such devices for more sentinel nodes excision and a complete monitoring of the whole procedure. New techniques, by using fluorescent or hybrid tracers, are currently being developed.

Multimodal detection of iron oxide nanoparticles in rat lymph nodes using magnetomotive ultrasound imaging and magnetic resonance imaging

Detection and removal of sentinel lymph nodes (SLN) is important in the diagnosis and treatment of cancer. The SLN is the first regional lymph node draining the primary tumor, and if the cancer has spread, it is most likely to find metastases in the SLN. In this study, we have for the first time been able to image the very same contrast agent, superparamagnetic iron oxide nanoparticles (SPIO-NPs), in rat SLNs by using both our frequency- and phase-gated magnetomotive ultrasound (MMUS) algorithm and conventional magnetic resonance imaging (MRI); MMUS post mortem, MRI in vivo. For both higher NP-concentration and smaller NPs, we found that the MMUS data showed a larger magnetomotive displacement (1.56 ± 0.43 and 1.94 ± 0.54 times larger, respectively) and that the MR-images were affected to a higher degree. The MMUS displacement also increased with lower excitation frequency (1.95 ± 0.64 times larger for 5 Hz compared with 15 Hz) and higher excitation voltage (2.95 ± 1.44 times larger for 30 V compared with 10 V). The results show that MMUS has potential to be used as bedside guidance during SLN surgery, imaging the same particles that were used in prior staging with other imaging techniques.

Development of a Hybrid Nanoprobe for Triple-Modality MR/SPECT/Optical Fluorescence Imaging

Hybrid clinical imaging is an emerging technology, which improves disease diagnosis by combining already existing technologies. With the combination of high-resolution morphological imaging, i.e., MRI/CT, and high-sensitive molecular detection offered by SPECT/PET/Optical, physicians can detect disease progression at an early stage and design patient-specific treatments. To fully exploit the possibilities of hybrid imaging a hybrid probe compatible with each imaging technology is required. Here, we present a hybrid nanoprobe for triple modality MR/SPECT/Fluorescence imaging. Our imaging agent is comprised of superparamagnetic iron oxide nanoparticles (SPIONs), labeled with ^99mTc and an Alexa fluorophore (AF), together forming ^99mTc-AF-SPIONs. The agent was stable in human serum, and, after subcutaneous injection in the hind paw of Wistar rats, showed to be highly specific by accumulating in the sentinel lymph node. All three modalities clearly visualized the imaging agent. Our results show that a single imaging agent can be used for hybrid imaging. The use of a single hybrid contrast agent permits simultaneous hybrid imaging and, more conventionally, allow for single modality imaging at different time points. For example, a hybrid contrast agent enables pre-operative planning, intra-operative guidance, and post-operative evaluation with the same contrast agent.

Treatment of Anemia Progression via Magnetite and Folate NanoparticlesIn Vivo

Iron deficiency anemia is a major global public health problem. Food fortification with iron (Fe) can be an effective strategy to control iron deficiency. An iron oxide nanoparticle (NP) is a new physical and chemical property form. These properties (small particle size, unique physical properties) make nanoiron a great scientific interest especially in the treatment of anemia. The study aimed to reduce anemia by nanoparticles (NPs). Forty-eight adult female Sprague-Dewily rats were divided into four groups (12 rats each). Group A represented a negative control. Other groups were fed standard diet iron free and three time of require zinc to reach anemic. Group B fed standard diet with ferrous sulfate until the improvement of the situation of anemia or for 8 weeks. Groups C and D were divided into three subgroups; each subgroup was fed a dose from magnetite or folate coated magnetite NPs. Results showed that symptoms of loss of appetite and severe lethargy demonstrate that magnetite and folate-coated magnetite nanoparticles have serious toxicological effectsin vivo. Some doses from NPs improve blood picture during 2 weeks but change in histopathology examinations were occur in some groups within 2 weeks. Nanoparticles were considered the toxicological hazards especially the size of less than 54 nm.

[Radiation exposure of surgical staff during sentinel node surgery. Is there a risk for the surgeon and his team?]

OBJECTIVE

Assess the radiation exposure of surgical staff during sentinel node surgery in gynecology using a radiotracer, the (99m)Tc-microalbumin.

MATERIALS AND METHODS

A monocentric, prospective study was conducted during 3 months representing 40 sentinel node surgical procedures with different dosimetric measurements. Dosimeters were used to evaluate the whole body and the fingers radiation exposure for all exposed workers (surgeon, nurse and surgical assistant). Another dosimeter was used to estimate the atmospheric radiation level. The activity of (99m)Tc-microalbumin was 50.1±2.4MBq when the surgery was performed the same day and 90.4±3.2MBq when the surgery was performed the day after.

RESULTS

Radioactive doses received during each procedure by the surgeon, surgical assistant and nurse are 5, 3.75 and 0μSv for whole body exposure and 17.5, 15.6 and 16.2μSv for extremities respectively. Atmosphere dosimeter does not detect any radiation over this period. On average, 200 procedures are performed each year in our hospital by 7 surgeons. Surgeon's radiation exposure remains below the threshold of 1mSv annual for whole body and 50mSv annual for fingers set for public by the International Commission on Radiological Protection.

DISCUSSION AND CONCLUSIONS

During sentinel node surgery radiation exposure of surgical staff is weak. Everyone, including the surgeon, receives a dose below the limits of the public radiation exposure. There is no need for special dosimetric monitoring or use radiation protective devices during the sentinel node surgery using (99m)Tc-microalbumin injection.

SPECT/CT and tumour imaging

Scintigraphic techniques are sensitive imaging modalities in the diagnosis and follow-up of cancer patients providing the functional and metabolic activity characteristics of the tumour. Hybrid SPECT/CT improves the diagnostic accuracy of these well-established imaging techniques by precise anatomical localization and characterization of morphological findings, differentiation between foci of physiological and pathological tracer uptake, resulting in a significant impact on patient management and more definitive interpretations. The use of SPECT/CT has been studied in a variety of applications in tumour imaging which are reviewed in this article. By combining functional and anatomical information in a single imaging session, SPECT/CT has become a one-stop cancer imaging modality.

SPECT/CT in sentinel node imaging

Sentinel node lymphoscintigraphy and biopsy has become standard practice for lymphatic staging in early-stage breast cancer and melanoma. More recently, sentinel node lymphoscintigraphy has also been used in head and neck squamous cell cancers and other solid tumours. Single photon emission computed tomography/computed tomography (SPECT/CT) is a new tool and this article reviews its potential application in sentinel node imaging. SPECT/CT provides complementary functional and anatomical information and has been shown to be superior to planar imaging in a number of indications. The advantages include more accurate anatomical localization, identification of false positives (due to contamination or spillover from the injection site), reduction in the number of false negatives (visualization of nodes not seen on planar imaging) and alteration of the surgical approach. We thus believe that sentinel lymph node SPECT/CT can provide valuable information before sentinel lymph node biopsy and advocate its use in a range of tumours such as truncal and head and neck melanomas.

Foot skin depots of 18F-fluorodeoxyglucose do not enable PET/CT lymphography of the lower extremity lymphatic system in man

BACKGROUND

In mice, 18F-fluorodeoxyglucose (18F-FDG) positron-emission tomography/computed tomography (PET/CT) lymphography enables detailed imaging of the lymphatic system and quantification of lymph node function. If this applies to humans, it may improve staging of several malignancies. The aim of this study was to elucidate whether foot skin depots of 18F-FDG make PET/CT imaging of the lower extremity lymphatic system possible in man.

FINDINGS

In four healthy volunteers, 18F-FDG depots (5 MBq in 0.1-mL isotonic saline) were injected intradermally in one foot and subcutaneously in the other. Activity was measured in blood samples drawn simultaneously from the great saphenous veins about 5 cm proximal to the ankle joints and a medial cubital vein before and every minute for 15 min after depot injection. Immediately thereafter, a low-dose CT was performed from the ankles to the pelvis followed by two consecutive PET scans of the same region.Blood activity increased faster and to a greater extent in the great saphenous veins compared to the medial cubital vein. PET/CT images showed activity in the superficial and deep veins of the lower extremities. No lymphatic collectors or nodes were visualized.

CONCLUSION

Neither subcutaneous nor intradermal injection of 18F-FDG allows imaging of the lower extremity lymphatic system in man.

[Incidence of axillary recurrence after a negative sentinel lymph node result in early stages of breast cancer: a 5-year follow-up]

The sentinel lymph node (SLN) biopsy is currently the procedure of choice for axillary node staging in initial stages of breast cancer. The purpose of this study is to establish our false negative rate within a 5-year follow-up period in 258 patients with breast cancer staged with this procedure.

METHODS

A retrospective study on 258 consecutive T1-T2<3 cm pN0 staged breast carcinomas treated from January 1, 2001 to December 31, 2005 was performed. The combined technique of isotope plus blue dye was used for detection. The subjects underwent a minimum follow-up of 5 years, mean 81 months, with an end of follow-up at December 31, 2010. Evidence of axillary recurrence, tumor recurrence in the breast and signs of disease progression or death were the events collected and analyzed.

RESULTS

Of the 258 patients, 3 false negatives (1.1%) with axillary recurrence were detected at 10, 11 and 29 months of the surgery. This did not have a significant repercussion in the survival analysis on the contrary to the existence of breast recurrence or the appearance of distant metastasis in 4.7% and 6.2% patients, respectively. Global survival related with the cancer was 93.0 (240/258) and disease free survival was 89.1% (230/258).

CONCLUSION

The risk of developing axillary recurrence after a negative SLN without axillary node dissection is low enough to consider the SLN procedure to be the best approach for axilla staging in early breast cancer. This staging technique also makes it possible to achieve local disease control without diminishing the survival of the patients.

Breast cancer sentinel node scintigraphy: differences between imaging results 1 and 2 h after injection

INTRODUCTION

Timing of image acquisition in breast cancer sentinel node scintigraphy remains a subject of debate. Therefore, the performance of our protocol in which images are acquired 1 and 2 h after injection was evaluated. The results of sentinel node scintigraphy 1 and 2 h after injection were compared with regard to the sentinel lymph nodes visualized.

METHODS

We studied 132 patients who were consecutively referred for sentinel lymph node biopsy. 99mTc-albumine nanocolloid (120 MBq) was injected peritumourally into patients with palpable tumours and intratumourally into patients with nonpalpable tumours. All scintigraphic images taken for the sentinel node procedure were evaluated. The number of sentinel nodes per anatomic localization and the interpretability of the images were scored.

RESULTS

A total of 132 patients underwent sentinel node scintigraphy 1 h after injection. Of these, 117 patients also underwent sentinel node scintigraphy 2 h after injection. An axillary sentinel node was visualized in 79.5 and 95.7% of patients, respectively, 1 and 2 h after injection. In 20.5% of the patients the images acquired 1 h after injection did not show a sentinel node. Furthermore, in all procedures, the images 1 h after injection were of no added value to those acquired 2 h after injection.

CONCLUSION

Scintigraphic imaging 2 h after a single peritumoural or intratumoural administration of about 120 MBq 99mTc-albumine nanocolloid yields an axillary sentinel node in over 95% of cases. Imaging 1 h after injection is of no additional value and can be omitted.

Ultrasound-guided sentinel node procedure for nonpalpable breast carcinoma

PURPOSE

Peritumoral and periareolar tracer injection techniques lead to different lymphatic drainage in sentinel lymph node biopsy procedures. In a prospective study, the visualization and identification rates of the ultrasound (US)-guided tracer injection technique for palpable and nonpalpable breast tumors were evaluated.

METHODS

In 1262 consecutive patients with cT₁₋₂N0 breast cancer, sentinel lymph node biopsy was performed following peritumoral tracer injection. In the case of nonpalpable breast lesions, Tc-99m nanocolloid injections were given using a 7.5 MHz US probe. In the case of ultrasonographically nonvisible microcalcifications, the US-guided injection technique was wire guided.

RESULTS

In 331 patients with nonpalpable breast lesions (26.2%), the lymphoscintigraphic visualization and surgical retrieval rates of axillary sentinel lymph nodes (SLNs) were 98.5 and 99.4%, respectively. For internal mammary (IM) SLNs, these rates were 21.1 and 17.8%, respectively. These rates were similar in patients with palpable and nonpalpable tumors. Axillary metastases were detected in 38.7% of the patients with palpable tumors versus 16.5% of those with nonpalpable tumors (P<0.001), whereas IM metastases were found in 4.8 and 3.0% of patients, respectively (P=0.165).

CONCLUSION

In nonpalpable breast lesions, the US-guided injection technique is an accurate technique for SLN identification and retrieval. The substantial rates of IM metastases in both palpable and nonpalpable lesions favor a peritumoral tracer injection technique.

Efficacy of high-energy collimator for sentinel node lymphoscintigraphy of early breast cancer patients

INTRODUCTION

Lymphoscintigraphy is an important part of sentinel node mapping in breast cancer patients. Sometimes star shaped artefacts due to septal penetration can be problematic during imaging. In the current study, we evaluated the possibility of high energy (HE) collimators use for lymphoscintigraphy.

PATIENTS AND METHODS

Twenty patients with early breast carcinoma were included. Thirty minutes after radiotracer injection (99mTc-antimony sulphide colloid), anterior and lateral images were acquired using a dual head gamma camera equipped with a parallel hole low energy high resolution (LEHR) collimator on one head and HE collimator on another head. All images were reviewed by two nuclear medicine specialists regarding detectability and number of axillary sentinel nodes and presence of star artefact.

RESULTS

All images taken by LEHR collimators showed star artefact of the injection site. No image taken by HE collimator showed this effect. In two patients the sentinel node was visible only by HE collimator. Tumour location in both of these patients was in the upper lateral quadrant and both had history of excisional biopsy. In two patients additional sentinel node was visible adjacent to the first one only on the LEHR images.

CONCLUSIONS

HE collimators can be used for sentinel lymph node mapping and lymphoscintigraphy of the breast cancer patients. This collimator can almost eliminate star-shaped artefacts due to septal penetration which can be advantageous in some cases. However, to separate two adjacent sentinel nodes from each other LEHR collimators perform better.

99mTc-labeled superparamagnetic iron oxide nanoparticles for multimodality SPECT/MRI of sentinel lymph nodes

The purpose of this study was to develop multimodality SPECT/MRI contrast agents for sentinel lymph node (SLN) mapping in vivo.

METHODS

Nanoparticles with a solid iron oxide core and a polyethylene glycol coating were labeled with (99m)Tc. The labeling efficiency was determined with instant thin-layer chromatography and magnetic separation. The stability of the radiolabeled superparamagnetic iron oxide nanoparticles (SPIONs) was verified in both sterile water and human serum at room temperature 6 and 24 h after labeling. Five Wistar rats were injected subcutaneously in the right hind paw with (99m)Tc-SPIONs (25-50 MBq, ∼0.2 mg of Fe) and sacrificed 4 h after injection. Two animals were imaged with SPECT/MRI. All 5 rats were dissected; the lymph nodes, liver, kidneys, spleen, and hind paw containing the injection site were removed and weighed; and activity in the samples was measured. The microdistribution within the lymph nodes was studied with digital autoradiography.

RESULTS

The efficiency of labeling of the SPIONs was 99% 6 h after labeling in both water and human serum. The labeling yield was 98% in water and 97% in human serum 24 h after labeling. The SLN could be identified in vivo with SPECT/MRI. The accumulation of (99m)Tc-SPIONs (as the percentage injected dose/g [%ID/g]) in the SLN was 100 %ID/g, whereas in the liver and spleen it was less than 2 %ID/g. Digital autoradiography images revealed a nonhomogeneous distribution of (99m)Tc-SPIONs within the lymph nodes; nanoparticles were found in the cortical, subcapsular, and medullary sinuses.

CONCLUSION

This study revealed the feasibility of labeling SPIONs with (99m)Tc. The accumulation of (99m)Tc-SPIONs in lymph nodes after subcutaneous injection in animals, verified by SPECT/MRI, is encouraging for applications in breast cancer and malignant melanoma.