Sentinel Node Lymphoscintigraphy Research Articles

99mTc-Rituximab sentinel lymph node mapping and biopsy, the effective technique avoids axillary dissection and predicts prognosis in 533 cutaneous melanoma

To evaluate the efficiency of a novel lymph node radiotracer 99mTc-rituximab in sentinel lymph node (SLN) lymphoscintigraphy and SLN biopsy (SLNB), and the influence of SLNB results on the prognosis of cutaneous malignant melanoma (CMM) patients. A retrospective study was performed on 533 patients with CMM who underwent lymphoscintigraphy and SLNB. All patients received a preoperative peritumoral injection of 11.1-18.5MBq of 99mTc-rituximab 0.5 to 1h before lymphoscintigraphy and SLNB. The detection rate of lymphoscintigraphy and SLNB was both 99.81% (532/533), and the average number of detected SLNs was 2.1 (range 1 to 8) and 2.7 (range 1 to 11) per patient, respectively. 12.1% SLNs and 22.2% patients were found metastatic, with an average of 1.5 (range 1 to 5) metastatic SLNs per patient. The SLN metastatic rates were different in patients with different Breslow thickness, Clark levels, ulceration, mitotic counts, and HMB45 expression (p < 0.05). Ninety patients were proceeded with the regional lymph node dissection (RLND) after SLNB, and the sensitivity, specificity and accuracy of SLNB in metastatic diagnosis is 97.4, 100 and 96.7%, respectively. And SLNs with metastases was an independent prognostic factor for OS and PFS by multivariate prognostic analyses (HR was 5.9 and 4.3, p < 0.001). For patients with metastatic SLNs, the non-SLNs with metastasis and non-SLNs without metastasis in RLND, and observation groups showed different mean PFS as 14.9, 24.8 and 25.5months (p = 0.018), but no statistically significant difference existed in the OS. The novel radiotracer 99mTc-rituximab could identify SLNs specifically in SLN lymphoscintigraphy and SLNB in CMM patients, and the pathology obtained from SLNB rather than from RLND better indicated the staging and long-term prognosis.

Sentinel Lymph Node Mapping in Breast Cancer: Initial Experience of a Multidisciplinary Team.

Introduction: Breast cancer is one of the leading causes of cancer-related deaths in women; it is the most frequently diagnosed cancer in women in the United States with a lifetime risk of dying of about 3.4%. Regional lymph node involvement is quite early in breast carcinoma and axillary lymph node metastasis is an important predictor of recurrence and survival, particularly in invasive ductal histology of breast carcinoma. Localization of sentinel lymph node/nodes followed by frozen section and histopathological evaluation helps to prevent unnecessary axillary nodal dissection and, hence, reduces associated post-surgical morbidity. Sentinel nodes are the first ones to receive lymph-borne metastatic cells and, hence, lymphoscintigraphy followed by biopsy is quite reliable to detect nodal metastasis, particularly at an early stage (I, II) of breast cancer.Methods: Here we will share our experience of introducing procedure, personnel training, and workflow of sentinel lymph node lymphoscintigraphy in breast cancer patients at our cancer institute to help other centers establish programs for this study.Results: Initially, 10 procedures were performed, all of which were successful in the localization of sentinel nodes and played a substantial part in the surgical planning of breast cancer. Planar lymphoscintigraphy and single-photon emission computerized tomography (SPECT)-CT images of our first patient revealed radiotracer avidity in the lymph node in the ipsilateral axilla, which was later on diagnosed as metastatic resulting in axillary nodal clearance.Conclusions: In multidisciplinary/closely-placed surgical, pathological, and hybrid imaging facility settings, lymphoscintigraphy provides a quick, accurate, and better way of nodal localization leading to correct surgical decision-making. In addition to planar imaging, SPECT-CT acquisition significantly improves the specificity of the lymphoscintigraphy procedure, which is beneficial for patients to avoid false-positive results, thus saving breast cancer patients from potential adverse effects of surgery.

Sentinel Node Biopsy Imaging in Breast Cancer: Scatter Reduction Using 3-Dimensionally Printed Lead Shields.

BackgroundPoint of injection scatter (SPI) confounds breast cancer sentinel lymph node detection. Round flat lead shields (FLSs) incompletely reduce SPI, requiring repositioning. We designed lead shields that reduce SPI and acquisition time.MethodsTwo concave lead shields, a semioval lead shield (OLS) and a semispherical lead alloy shield (SLS), were created with a SICNOVA JCR 1000 3D printer to cover the point of injection (patent no. ES1219895U). Twenty breast cancer patients had anterior and anterior oblique imaging, 5 minutes and 2 hours after a single 111 MBq nanocolloid in 0.2 mL intratumoral or periareolar injection. Each acquisition was 2 minutes. Absolute and normalized background corrected scatter counts (CSCs) and scatter reduction percentage (%SR) related to the FLS were calculated. Repositionings were recorded. Differences between means of %SR (t test) and between means of CSC (analysis of variance) with Holm multiple comparison tests were determined.ResultsMean %SR was 91.8% with OLS and 92% using SLS in early images (P = 0.91) and 87.2%SR in OLS and 88.5% in late images (P = 0.66). There were significant differences between CSC using FLS and OLS (P < 0.001) and between FLS and SLS (P < 0.001), but not between OLS and SLS (P = 0.17) in early images, with the same results observed in delayed studies (P < 0.001 in relation to FLS and P = 0.1 between both curved lead shields). Repositioning was required 14/20 times with FLS, 4/20 times with OLS, and 2/20 times with SLS.ConclusionsWe designed 2 concave lead shields that significantly reduce the SPI and repositioning with sentinel lymph node lymphoscintigraphy.

An investigation of aspects of radiochemical purity of 99mTc-labelled human serum albumin nanocolloid

BackgroundNanocolloidal human serum albumin radiolabelled with 99mTc provides a diagnostic radiopharmaceutical for sentinel node lymphoscintigraphy. NanoHSA (Nanotop), a commercially available kit, enables the simple preparation of this radiopharmaceutical via reconstitution with pertechnetate eluted from a generator. Thin-layer chromatography is widely used for determining radiochemical purity in clinical nuclear medicine. Quality control methods recommended by the manufacturer were sometimes reported to yield variable results. Therefore, we proposed and evaluated three alternative thin-layer chromatography methods for the quality control of [99mTc]Tc-NanoHSA from a commercially available kit.ResultsThe radiochemical purity of [99mTc]Tc-NanoHSA determined with all methods was reproducible and met the requirements of the SPC and the European Pharmacopoeia (≥ 95%). Our quality control using iTLC-SG chromatographic paper in methyl ethyl ketone mobile phase identified only free pertechnetate as impurity, resulting in > 99% RCP. The quality control using iTLC-SG in 85% methanol or iTLC-SA in 0.9% NaCl identified an additional small fraction of a hydrophilic impurity, resulting in 95–97% RCP. Glucose was identified as a potential 99mTc-carrying hydrophilic species contributing to hydrophilic impurities.ConclusionOur quality control of [99mTc]Tc-NanoHSA with non-polar mobile phase tended to underestimate the amount of hydrophilic impurities, although without compromising the final quality of the radiopharmaceutical. Alternative TLC methods using aqueous mobile phases enabled a more accurate determination of hydrophilic impurities.

Risk factors for nonvisualization of the sentinel lymph node on lymphoscintigraphy in breast cancer patients

BackgroundAccurate sentinel lymph node (SLN) staging is essential for both prognosis and treatment in patients with breast cancer. However, the preoperative lymphoscintigraphy may fail to visualize the SLN in some patients. The purpose of this retrospective study was to identify risk factors associated with SLN nonvisualization on lymphoscintigraphy. For this single-center retrospective study, all data of lymphoscintigraphy of SLN procedures from March 2011 to April 2021 were collected and reviewed from the Amsterdam UMC database.ResultsA total of 1886 SLN procedures were included in this study. The SLN nonvisualization rate was 25.1% on lymphoscintigraphy at 4 h post-injection. The SLN nonvisualization rate decreased to 9.4% after reinjection. Multivariable analysis showed that age ≥ 70 years (P < 0.001; OR: 2.27; 95% CI: 1.46–3.53), BMI ≥ 30 kg/m2 (P = 0.031; OR: 1.48; 95% CI: 1.04–2.12) and nonpalpable tumors (P = 0.004; OR: 1.54; 95% CI: 1.15–2.07) were independent predictors of SLN nonvisualization. Tumor location, brand of radiopharmaceutical, injected dose and volume, experience of preparer and administrator were not associated with SLN nonvisualization. None of the patient, tumor or tracer characteristics were associated with SLN nonvisualization after radiotracer reinjection.ConclusionsThis study shows that risk factors for SLN nonvisualization in breast cancer patients during preoperative lymphoscintigraphy are age ≥ 70 years, BMI ≥ 30 kg/m2 and nonpalpable tumors. Our results support the notion that SLN lymphoscintigraphy is a very robust technique that does not depend on the experience of the preparer or administrator of the radiotracer.

The Use of Periareolar Topical Lidocaine Jelly After Needle Localization May Reduce Pain of Subsequent Lymphoscintigraphy.

PurposeTechnetium Tc-99m sulfur colloid (99mTc-SC) breast lymphoscintigraphy is commonly performed to identify the sentinel lymph node (SLN) in patients diagnosed with breast carcinoma undergoing lumpectomy. The purpose of this report is to describe how the use of 2% topical lidocaine jelly immediately after the completion of needle localization and prior to scintigraphy may substantially reduce pain associated with the injection of 99mTc-SC.Materials and methodsThis was a quality improvement project. Patients were asked to score the severity of pain associated with the periareolar 99mTc-SC injections for sentinel node lymphoscintigraphy. In order to decrease the discomfort, topical lidocaine was applied to the periareolar skin after the completion of the needle localization, but prior to transferring the patient from the mammography room to the nuclear medicine department for the 99mTc-SC injections. At the time of 99mTc-SC injection, patients were asked to score the pain of injection from 0 (none) to 10 (worst).ResultsThe average pain score of the women who did not receive topical lidocaine jelly was 8 (range: 5-9). In the 10 women who received topical lidocaine jelly after needle localization, the average pain score was 2.5 (range: 1-5). Interestingly, the pain score for women who discussed the possible use of lidocaine jelly with the radiologists but still did not receive topical lidocaine jelly was also low at 6.5. For patients who received the lidocaine jelly only five minutes prior to injection, the average pain score was 6.ConclusionThe application of lidocaine jelly after the conclusion of needle localization, with a 15-40-minute delay prior to periareolar injections with 99mTc-SC for sentinel node lymphoscintigraphy, appears to substantially reduce the pain associated with the injection of 99mTc-SC.

Akwizycja planarna a SPECT/CT w detekcji węzłów wartowniczych w raku sutka

Sentinel lymph node biopsy is an increasingly popular method of breast cancer treatment. In order to determine the number and location of potentially positive nodes, it is necessary to perform sentinel node lymphoscintigraphy. The quality of the image depends on the use of the appropriate method of radionuclide imaging. The aim of this study was to compare the sensitivity of SPECT, SPECT/CT and classical planar acquisitions in the detection of sentinel lymph nodes for sentinel node lymphoscintigraphy in breast cancer. In addition, we tried to verify the usefulness of the morphological image obtained by SPECT/CT to specify their location. We studied 62 women (mean age = 58, SD = 10.28) with histologically confirmed breast cancer (T0-2N0M0). Planar, SPECT and SPECT/CT images were interpreted separately in terms of the number and location of sentinel lymph nodes and lymphatic drainage direction. Planar images detected 93 sentinel lymph nodes, while SPECT and SPECT/CT showed 114 nodes (about 22% more). In 15 (24%) patients SPECT imaging detected more sentinel lymph nodes than planar. Planar imaging was negative for the identification of sentinel lymph nodes in 6 (10%) patients. SPECT/CT images showed sentinel lymph nodes in all patients. The node to background ratio on the planar images was 11.6, on the SPECT 134.9, and on the SPECT/CT 147.5. The direction of lymphatic drainage and location of axillary lymph nodes were established only on SPECT/CT images. The use of SPECT imaging for sentinel node lymphoscintigraphy in breast cancer increases the sensitivity of sentinel lymph nodes detection. The use of low-dose CT as attenuation correction for SPECT images improves their contrast without a significant effect on the number of detected sentinel lymph nodes. It also brings important anatomical information, which is difficult or even impossible to determine by planar and SPECT images.

Utility of hybrid SPECT/CT in primary melanoma lymphoscintigraphy: A retrospective case series.

Sentinel lymph node (SLN) biopsy is widely accepted as an important part of staging cutaneous malignant melanoma. Hybrid single photon emission computed tomography and computed tomography (SPECT/CT) may identify additional SLN and provide important information to the surgeon performing SLN biopsy. We report our experience at a major referral centre for melanoma surgery. Retrospective case series of pre-operative sentinel node lymphoscintigraphy for primary melanoma over a consecutive 12-month period. All patients had planar imaging and hybrid SPECT/CT. At least 1 SLN was successfully identified in 82 of 86 eligible patients (95.3%). These 82 patients had 144 SLNs (mean 1.8). There were no patients where the SLN was seen only with SPECT/CT. Additional information was provided by SPECT/CT in 32 patients (39.0%). Histology reports were available for 52 patients, 9 (17.3%) had at least 1 SLN positive for metastatic disease. We achieved a high rate of SLN identification. SPECT/CT was most frequently helpful when the primary melanoma was located in the head, neck and trunk. Routine use of SPECT/CT during lymphoscintigraphy provides important anatomical information and may reduce the false-negative rate.

Sentinel Node Lymphoscintigraphy in High-risk Cutaneous Squamous Cell Carcinoma

BackgroundHigh-risk cutaneous squamous cell carcinoma includes recurrent disease, a tumor diameter > 2 cm, T4 stage, perineural or lymphovascular invasion, tumor depth of ≥ 4 mm, and high-grade histologic features. All have been implicated in an increased risk of occult regional lymph node involvement. Patients and MethodsAmong a large group of patients with nonmucosal, cutaneous squamous cell carcinoma seen at our center, 30 patients with high-risk inclusion criteria were prospectively evaluated to undergo wide local excision and sentinel lymph node mapping. ResultsWith a median follow-up period of 56 months, 4 patients (13%) had regional lymph nodal involvement. The patients identified with lymph node-positive disease underwent adjuvant therapy. Five patients (17%), none of whom had nodal disease at diagnosis, developed locally recurrent disease requiring additional therapy. On multivariate analysis, a statistically significant correlation was found between the depth of tumor invasion and occult sentinel lymph node involvement. ConclusionIn the present prospective analysis, sentinel lymph node mapping resulted in upstaging in 13% of the patients. The tumor depth was independently associated with an increased risk of nodal involvement. Given the association between a depth of tumor invasion of ≥ 4 mm and occult nodal disease in cutaneous squamous cell carcinoma, sentinel lymph node mapping could be considered an integral part of surgical staging for patients with high-risk features.

Multimodal imaging techniques in the diagnosis of metastatic lesions

Imaging has a crucial role in the treatment of head and neck cancers as it discloses hidden foci of metastases, especially when it is located outside of the planned treatment field. Metastasis to oral cavity is a rare chance and may involve either soft tissue or jaw bones. Their early and accurate detection is critical and also a real challenge for the clinician. Therefore, pre-, per- and post-treatment imaging in diagnosis is critical. Radiography, computerized tomography, magnetic resonance imaging, followed by positron emission tomography, advancements in ultrasonography, and nuclear medicine along with sentinel node lymphoscintigraphy has greatly added to the diagnostic accuracy of metastases.

SPECT/CT in imaging sentinel nodes

Sentinel lymph node lymphoscintigraphy and biopsy (SLNB) has become standard practice for lymphatic staging in early stage breast cancer and melanoma. SLNB has also been used in head and neck squamous cell cancers and other solid tumours. Although SPECT/CT imaging in SLNB is not currently standard practice, there is growing evidence for its use. This article reviews the role of SPECT/CT in SLNB and describes its potential advantages over planar imaging. The hybrid SPECT/CT imaging modality fuses functional and anatomical information and has advantages over SPECT/CT in certain scenarios. We did a PUBMED (MeSH) search with the following keywords: SPECT/CT, sentinel lymph node, breast cancer, melanoma, oral cavity, gynaecological, prostate, single photon tomography and reviewed relevant articles. In breast cancer, SPECT/CT may contribute to more adequate patient management in the following indications: in overweight and obese patients, in patients with non-visualisation of the lymph node on planar images and in patients with unusual drainage pattern or difficult to interpret images. The advantages of SPECT/CT in melanoma include a higher overall rate of SLN detection, the ability to detect SLNs in difficult to interpret planar studies, better detection of SLNs near an injection site and better anatomical localisation. These advantages can result in change in patient management, by altering the surgical approach. Precise localisation may also result in reduced overall cost of the sentinel node procedure. SPECT/CT also provides valuable information in head and neck cancer. SPECT/CT provides improved anatomical localisation, and increases accuracy by locating additional SLNs, identifying false negatives (close to the injection site) and false positive (skin contamination) with subsequent impact on patient management.

Possibility to Use the Radiopharmaceutical Based on the Gamma-Aluminum Oxide Labeled with &lt;sup&gt;99m&lt;/sup&gt;Tc to Identify Sentinel Lymph Nodes in the Experiment

Studying the possibility of using the radiopharmaceutical to identify sentinel lymph nodes were carried out on male rats. The preparation was injected subcutaneously in the I interfinger space of the right forelimb. Radiometry of rats’ organs showed that the studied preparation was actively accumulated in the axillary lymph node after subcutaneous injection. The experimental study of the pharmacokinetics of radiopharmaceutical based on gamma-oxide aluminum labeled with 99mTc showed that the analyzed RPP can be successfully used for lymphoscintigraphy and visualization of sentinel node starting with the 15th minute and up to the 24th hour after subcutaneous injection.

SPECT/CT and sentinel node lymphoscintigraphy

The use of single-photon emission computed tomography/computed tomography (SPECT/CT) for sentinel node (SN) detection has been evaluated in the majority of malignancies with predominantly superficial lymphatic drainage. In breast cancer and melanoma, important initial contributions of SPECT/CT were based on the anatomical localisation of SNs already visualised on planar images, the detection of additional SNs in aberrant basins, and the depiction of SNs in cases with no visualisation on planar images. However, more recently, the finding that SPECT/CT use is associated with a higher rate of SN detection, more metastatic SNs, and a higher rate of disease-free survival in large series of patients is leading SPECT/CT to be routinely performed in melanoma. The incorporation of SPECT/CT into the SN procedure in melanoma also appears to be cost effective and was significantly related to shorter operative times, shorter hospital stays, and fewer complications. In penile and vulvar cancer, the use of SPECT/CT has led to the detection of additional SNs. In oral cavity cancer and thyroid cancer, SPECT/CT not only appears to be useful for planar image interpretation but is also becoming an essential component of the SN procedure, providing surgeons with additional anatomical information. As regards malignancies with deep lymphatic drainage, SPECT/CT has been extensively validated in urological and gynaecological cancers. In these malignancies, SPECT/CT was able to localise SNs not only in the basins included in the area of extended pelvic lymph node dissection but also in aberrant locations. In gastrointestinal and lung malignancies, SPECT/CT has been used only incidentally. SPECT/CT must be considered complementary to planar lymphoscintigraphy for SN identification, and a combined interpretation of both modalities is necessary. With the improvement of the CT component, nuclear physicians today can also identify lymph nodes corresponding to radioactive SNs. This visual information is helpful for the intraoperative procedure and for post-excision assessment using portable devices.

Cysteine Rhenium Colloid: A Novel Radiocolloid for Identifying Sentinel Lymph Nodes in Breast Cancer Surgery

BackgroundMedical isotopes are required for sentinel node lymphoscintigraphy in breast cancer, but are in critical shortage. Our center uses a modification of the standard SC, called CRC, that has been shown to require less medical isotope for the same procedure. Our objective was to determine if there was a significant difference between SC and CRC in successful lymph node identification in breast cancer patients. Patients and MethodsThis was a retrospective cohort study using prospectively-collected data on 1205 consecutive early, clinically node-negative breast cancer patients who underwent a SNB between 2002 and 2008 at 2 tertiary hospitals in Canada. ResultsThere was no difference in successful lymph node identification rate (P = .50) or in the mean number of positive nodes identified between the 2 colloids (P = .88). The CRC group had a significantly lower rate of delayed adverse events (4.91% vs. 0.59%, P < .0001) even after adjusting for whether axillary dissection occurred on the same day as the biopsy (adjusted odds ratio, 0.12; 95% confidence interval, 0.04-0.40; P = .001). ConclusionOur findings suggest that there is no significant difference between CRC and SC in detecting sentinel nodes; however, CRC uses less medical isotopes. In the current climate of critical shortages of medical radioisotopes, radiocolloids should be selected for use based on amount of radioisotope required.

Particle-size and radiochemical purity evaluations of filtered 99mTc-sulfur colloid prepared with different heating times.

Sentinel node lymphoscintigraphy using colloidal particles has become common practice at many institutions. The ideal particle size for colloids such as filtered (99m)Tc-sulfur colloid ((99m)Tc-FSC) in sentinel node studies is 15-100 nm. It is reported that the use of a reduced heating time during the reconstitution process results in an increased number of smaller particles (<30 nm). However, it is unclear whether these smaller particles (>15 nm) would be of benefit in sentinel node studies. This study sought to better define particle size by using electron microscopy, as well as to evaluate the radiochemical purity (RCP) of (99m)Tc-FSC at various time points after filtration. One group of (99m)Tc-sulfur colloid ((99m)Tc-SC) preparations was reconstituted using the standard heating time of 5 min, and another group was prepared using a reduced heating time of 3 min. The (99m)Tc-SC preparations were passed through a 0.2-μm filter, and retained filter activity was measured. RCP values were collected at 0, 1, 3, and 6 h after filtration, and the particle sizes were measured at 0 and 6 h after filtration. Average RCP values (± SD) for (99m)Tc-FSC with 5-min heating were 98.4% ± 3.0% and 98.3% ± 1.8% for 0 h and 6 h, respectively (n = 6). Average RCP values for (99m)Tc-FSC with 3-min heating were 98.4% ± 4.1% and 96.9% ± 3.1% for 0 h and 6 h, respectively (n = 6). Electron microscopy data showed that median particle sizes for the 3-min heating at 0 and 6 h were 24 and 35 nm, respectively. Median particle sizes for the 5-min heating at 0 and 6 h were 29 and 27 nm, respectively. The proportion of particles within the ideal range for sentinel node lymphoscintigraphy was similar between the heating methods (91.1% for 3-min heating at 0 h and 88.8% for 5-min heating at 0 h, P = 0.1851). Our results indicate that although there are slight significant differences in RCP value, particle size, and particle number for (99m)Tc-FSC prepared using either a standard or a reduced heating time, both methods produce particles within the optimum range for sentinel node studies.

Predictive parameters for internal mammary node drainage in patients with early breast cancer.

Breast cancer treatment currently represents one of the biggest challenges in clinical oncology. The gold standard for axillary lymph node management is to perform sentinel node biopsy to avoid axillary dissection and its sequelae. The detection of radiocolloid flow outside the axillary nodes is a diagnostic and therapeutic challenge. A database search at the Department of Oncology of Palacky University, Olomouc, Czech Republic, identified 127 patients who underwent breast cancer resection with a sentinel node procedure and had radiocolloid flow into the internal mammary nodes. Sentinel node lymphoscintigraphy was performed after intraparenchymal injection. Clinical and pathological data were collected to identify possible risk factors. Ten clinical and pathological parameters including age, tumor histology, axillary lymph node status, estrogen receptor expression, progesterone receptor expression, tumor grade, Ki-67 expression, Her-2 status, tumor size and tumor location were analyzed with regard to internal mammary node drainage. A cohort of 127 patients with detected drainage into the internal mammary nodes was compared with 135 patients without such drainage. Six significant risk factors, including age <50 years ( P <0.0313), tumor location in central and inner quadrants (P <0.012), larger tumor size (P <0.017), positive Her-2 status (P <0.025), progesterone receptor expression (P <10-4) and axillary lymph node involvement (P <0.01) were found to predict radiocolloid flow into the internal mammary nodes. Six parameters (patient age, tumor location, hormone receptor status, tumor size, Her-2 status and axillary lymph node status) should be considered in the management of breast cancer patients and help in the selection of patients for locoregional procedures encompassing the internal mammary nodes.

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.

Evaluation of patient effective dose from sentinel lymph node lymphoscintigraphy in breast cancer: A phantom study with SPECT/CT and ICRP-103 recommendations

To evaluate the effective dose delivered to patients undergoing sentinel lymph node (SLN) lymphoscintigraphy by taking into account both the transmission dose using the CT component of a SPECT/CT system and the (99m)Tc internal emission dose. An adult female humanoid phantom and a set of thermoluminescent dosimeters were used in dose measurement from the CT transmission irradiation. The choice of measurement organs in the humanoid was guided by the recommendations described in the International Commission on Radiological Protection report number 103 (ICRP-103). The effective doses due to (99m)Tc internal emission source were re-calculated from measurement data reported in our previous study on the same subject with the use of tissue weighting factors of ICRP-103. CT transmission dose is the main contribution to the patient total effective dose for both 1-day and 2-day lymphoscintigraphy protocols and for different surgical procedures. Patients undergoing SLN lymphoscintigraphy receive about the same amount of total effective dose of about 3mSv for both 1-day and 2-day protocol, regardless of whether the tissues containing radioactivity would be excised at surgery or not. Although the total effective dose from using SPECT/CT is equivalent to the annual natural background radiation of about 3mSv, nuclear medicine physicians should be aware of the increase in effective dose for SLN lymphoscintigraphy using hybrid imaging technique of SPECT/CT when compared to conventional planar (57)Co flood source for transmission scan. Results from the current study provide update information in radiation exposure to patients undergoing SLN lymphoscintigraphy with the use of SPECT/CT.

Imaging modalities in head-and-neck cancer patients

Accurate staging and timely assessment is critical in head-and-neck cancer patients for formulating the appropriate treatment strategy. Therefore, optimizing pretreatment imaging for diagnosis is of great importance. Computerized tomography (CT), introduced in the early 70s, followed by magnetic resonance imaging (MRI) and positron emission tomography (PET), refinements in ultrasonography (USG), advances in nuclear medicine, and applications such as sentinel node lymphoscintigraphy have greatly added to diagnostic accuracy. Post-treatment CT or MRI is of value when a recurrent tumor is suspected. It can confirm the presence of such a lesion and determine its extent. This is important information for determining the possibility of salvage therapy.

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

IntroductionLymphoscintigraphy 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 methodsTwenty 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.ResultsAll 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.ConclusionsHE 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.