Tc-99m Sulfur Colloid Research Articles

Spectrum of Heterotopic and Ectopic Splenic Conditions.

A spectrum of heterotopic and ectopic splenic conditions may be encountered in clinical practice as incidental asymptomatic detection or symptomatic diagnosis. The radiologist needs to be aware of these conditions and their imaging characteristics to provide a prompt correct diagnosis and avoid misdiagnosis as neoplasm or lymphadenopathy. Having a strong knowledge base of the embryologic development of the spleen improves understanding of the pathophysiologic basis of these conditions. Spleen-specific imaging techniques-such as technetium 99m (99mTc)-labeled denatured erythrocyte scintigraphy, 99mTc-sulfur colloid liver-spleen scintigraphy, and MRI with ferumoxytol intravenous contrast material-can also be used to confirm the presence or absence of splenic tissue. Heterotopic splenic conditions include splenules and splenogonadal fusion (discontinuous or continuous forms). These heterotopic conditions are caused by incomplete fusion of the splenic primordia (splenule) and abnormal fusion of the gonadal and splenic tissue (splenogonadal fusion). Ectopic splenic conditions arise in patients with a prior splenic injury (splenosis), laxity or maldevelopment of the splenic ligaments (wandering spleen), or heterotaxy syndromes (polysplenia and asplenia). Importantly, these heterotopic and ectopic splenic conditions can also manifest with complications, including vascular torsion and rupture. ©RSNA, 2024.

Calculation of the absorbed dose to 99mTc-HMPAO, 99mTc-DMSA, and 99mTc-sulfur colloid injected patients by using Monte Carlo and MIRD methods

Calculation of the absorbed dose to 99mTc-HMPAO, 99mTc-DMSA, and 99mTc-sulfur colloid injected patients by using Monte Carlo and MIRD methods

Liver injury and recovery following radiation therapy for hepatocellular carcinoma: insights from functional liver imaging

Aim: A critical need for hepatocellular carcinoma (HCC) management is understanding how the liver recovers following radiotherapy (RT). We hypothesized that functional liver imaging with 99mTc-sulfur colloid (SC) SPECT/CT provides additional information on liver injury and recovery after RT compared to conventional imaging. Methods: The liver function of patients with HCC was assessed using 99mTc-SC SPECT/CT imaging before and after definitive RT. The anatomical liver volume (ALV) was segmented on CT imaging. Liver function was measured as the total liver function (TLF) encompassing 30% of maximum SC uptake. Changes in ALV and TLF were compared to clinical characteristics. Results: Of 31 patients with evaluable post-RT SC SPECT/CT scans (total of 32), 23 had pre-treatment Child-Pugh (CP)-A and 9 had CP-B/C scores. The median follow-up post-RT was 57 days. The median change in ALV was -1.7% with no significant difference between CP-A and CP-B/C patients (P = 0.26) or between short- (32-99 days) and long-term (271-1120 days) follow-up imaging groups (P = 0.28). The median change in TLF post-RT was -24% and was significantly different between short- and long-term groups (-39% vs. 2%, P = 0.001) and between CP-A and CP-B/C patients (-19% vs. -57%, P = 0.002). TLF significantly decreased following treatment at all radiation dose levels, with the decline correlating with the dose (P < 0.001). Conclusion: Functional imaging provides additional information regarding liver injury and recovery following RT that conventional imaging cannot reveal. Patients with CP-A liver status showed less decline following RT and most had liver function near or above pre-treatment levels.

Characterizing Normal Upper Extremity Lymphatic Flow with 99mTc In-House Dextran: A Retrospective Study.

Lymphoscintigraphy evaluates the lymphatic system using radiocolloid compounds like 99mTc-sulfur colloid and 99mTc-nanocolloid, which vary in particle size and distribution timing. A local in-house Dextran kit (15-40 nm) was developed in 2005 and began clinical use in 2008 to localize sentinel lymph nodes; diagnose lymphedema; and detect lymphatic leakage. The normal drainage pattern remains unexplored. We retrospectively analyzed 84 upper extremity lymphoscintigraphies from 2008 to 2021. 99mTc in-house Dextran was intradermally injected into both hands, followed by whole-body imaging at specified intervals (≤15 min; 16-30 min; 31-45 min; 46-60 min), with some receiving delayed imaging. Visual and quantitative analyses recorded axillary and forearm lymph nodes and liver, kidney, and urinary bladder activity. Results showed 92% (77/84) upper extremity lymphatic tract visualization within 45 min. Axillary node detection rates increased from 46% (≤15 min) to 86% (46-60 min). Delayed imaging further revealed nodes. Epitrochlear or brachial node visualization was rare (4%, 3/84). Hepatic, renal, and urinary bladder activity was noted in 54%, 71%, and 93% at 1 h, respectively. The axillary node uptake ratio was minimal (<2.5% of injection site activity; median 0.33%). This study characterizes normal upper extremity lymphatic drainage using 99mTc in-house Dextran, offering insights into its clinical application.

TAAR1 agonist ulotaront delays gastric emptying of solids in patients with schizophrenia and concurrent metabolic syndrome with prediabetes.

Metabolic syndrome (MetS), which can be induced or exacerbated by the current class of antipsychotic drugs, is highly prevalent in patients with schizophrenia and presents significant challenges to lifetime disease management. Supported by initial clinical results, trace amine-associated receptor 1 (TAAR1) agonists have emerged as potential novel treatments for schizophrenia. Notably, non-clinical studies have also shown weight-lowering and glucoregulatory effects of TAAR1 agonists, including the investigational agent ulotaront. However, the translatability of these findings to humans has not been adequately assessed. Given that delayed gastric emptying (GE) was identified as a potential mechanism contributing to the metabolic benefits of TAAR1 agonists in rodents, the aim of this study was to evaluate the effect of ulotaront on GE in patients with schizophrenia and concurrent MetS with prediabetes. Patients with schizophrenia were randomized to receive a single oral dose of ulotaront (150 mg) and their previous antipsychotic (PA) in an open-label, crossover, two-sequence design (NCT05402111). Eligible participants fulfilled at least three of five MetS criteria and had prediabetes defined by elevated glycated haemoglobin (5.7-6.4%) and/or fasting homeostatic model assessment of insulin resistance (i.e. ≥2.22). Following an overnight fast and 4 h post-dose, participants ingested a 99mTc-sulphur colloid radiolabelled egg meal (320 kcal, 30% fat). GE was measured by scintigraphy over 4 h. Endpoints included GE of solids half-time (T1/2) and percentage gastric retention at 1, 2 and 4 h. Thirty-one adults were randomized and 27 completed the study. Ulotaront significantly delayed GE of solids [median GE T1/2 ulotaront at 139 min (119, 182) vs. the participant's PA of 124 min (109, 132), p = .006]. A significant increase in gastric retention was seen in the ulotaront versus the PA group at 1 h (80% vs. 75%, p = .015), 2 h (61% vs. 50%, p = .023) and 4 h (17% vs. 7%, p = .002) post-meal. Ulotaront delayed the GE of solids in patients with schizophrenia and concurrentMetS with prediabetes. Additional studies are needed to assess whether treatment with TAAR1 agonists is associated with weight loss and glucoregulatory improvement.

An Evaluation of Gastric Emptying Scintigraphy Protocols in Health Care Institutions When Compared with the Society of Nuclear Medicine and Molecular Imaging Procedure Guidelines.

This study aimed to analyze the compliance of health care institutions with the Society of Nuclear Medicine and Molecular Imaging (SNMMI) procedure guidelines for gastric emptying scintigraphy (GES). Methods: A 19-question survey on demographics and the GES protocol was conducted using a Google form. The demographic questions covered position, number of technologists in the department, location, type of health care institution, and number of GES studies per month. The protocol questions included patient preparation, meal preparation, withholding of scheduled medications, radiopharmaceutical type, and radiopharmaceutical dose. The survey was sent to 7 nuclear medicine Facebook groups and a list of clinical affiliates provided by the Indiana University School of Medicine Nuclear Medicine Program. Descriptive statistics were compiled for most questions. A Fisher exact test with a significance level of 0.05 was used to compare the type of health care institution with compliance with the SNMMI GES protocol regarding radiolabeling time, meal preparation, and meal components, as well as to compare the type of health care institution with the number of GES studies performed per institution. Results: In total, 240 people responded to the survey. Most were nonsupervisory nuclear medicine technologists (72%) in nonacademic institutions (72%) and groups with 4 or more technologists (62%). Of the respondents, 72% followed the SNMMI guideline of adding the radiopharmaceutical before cooking, but only 37% followed the meal component guideline. There was no significant association between the type of institution or the number of GES studies and compliance with radiolabeling time or with meal preparation or components. Most respondents asked patients to withhold medications per SNMMI guidelines and used the recommended radiopharmaceutical (99mTc-sulfur colloid, 95%) at the recommended dose (18.5-37 MBq, 84%). Conclusion: Although most respondents followed most aspects of the SNMMI guidelines for GES, more than half did not use the recommended meal of liquid egg whites. Compliance did not vary between academic and nonacademic institutions or between groups performing a large or a small number of GES studies.

The Efficacy of Radiolabeling the Albumin in Egg Whites with 99mTc-Sulfur Colloid.

In 2009, the Society of Nuclear Medicine and Molecular Imaging published a standardized protocol guideline for gastric emptying scintigraphy that contains specific instructions on the exact meal and preparation procedure. Previous research has shown that the standardized meal and proper preparation of the meal for gastric emptying scintigraphy are not being adopted by some facilities. This research explores the differences of radiolabeling in the method of preparation of 99mTc-sulfur colloid (SC)-radiolabeled eggs. Methods: Liquid egg whites were mixed with 99mTc-SC before cooking in conjunction with the standardized protocol. A second sample set was prepared by adding the 99mTc-SC to eggs after they were cooked. Each sample set was placed in a solution of HCl and pepsin to simulate gestation. Radiolabeling efficacy was tested on each sample set at 2 and 4 h after gestating in HCl and pepsin. Results: 99mTc-SC added to the liquid egg whites before microwave cooking yielded radiolabeling efficacy of 70% 99mTc-SC after 2 and 4 h of simulated gastric fluid gestation. In contrast, radiolabeling after cooking the egg whites yielded 50% radiolabeling after simulated gestation. Conclusion: The results from this experiment showed that the method of mixing the 99mTc-SC with liquid egg whites before microwave cooking has higher binding efficacy than when adding 99mTc-SC onto already cooked egg whites. These results highlight the importance of following the standardized protocol for the meal preparation of a gastric emptying study.

Focal hepatic hot spot sign: Clinical image

A 51‐year‐old women was hospitalized to start chemotherapy for small cell lung cancer diagnosed one months earlier. She underwent Computed Tomography (CT) of the chest and abdomen to re‐evaluate the progression of the lung tumour. Contrast-enhanced CT of the chest indicated an invasive anterior left lung tumour that caused an obstruction of the Superior Vena Cava (SVC) (Figure 1). Contrast-enhanced CT of the abdomen revealed an intense focal wedge-shaped homogeneous enhancement area in the quadrate lobe of the liver, which is known as the hot spot sign (Figure 2). Focal hepatic hot spot sign was first described by Ishikawa in 1983. The sign can be observed on technetium 99m (99mTc) Sulphur colloid scans or on contrast, material enhanced CT scans [1]. Hot spot sign is caused by portosystemic venous shunting between the superior vena cava and the left portal vein via the internal mammary and paraumbilical veins along the ligamentum teres, secondary to superior vena cava obstruction. The hot spot is created by areas of focally increased blood flow that result from this shunting [2]. Stanford and colleagues classified SVC syndrome into four types - type I and type II referred as supra-azygous partial and near complete obstruction of SVC with antegrade flow in azygous vein. Type III is defined as complete obstruction of SVC with reversal of azygous blood flow and type IV as complete obstruction of SVC and azygous system with development of chest wall collaterals [3]. This sign has been reported in Budd-Chiari syndrome, the causes of SVC syndrome (neoplasms of the thorax as lung carcinoma and lymphoma, Vasculo‐Behcet’s disease, fibrosing mediastinitis, and luetic aneurysm), and masses of the liver (abscess, haemangioma, focal nodular hyperplasia, and hepatocellular carcinoma) [4].

A SPECT/NIR Fluorescence Dual-Modality Imaging Agent Composed of Drugs and Hospital Available Isotope for Preoperative Sentinel Lymph Node Mapping and Intraoperative Biopsy.

Sentinel lymph node (SLN) mapping-guided biopsy is crucial for cancer staging and treatment. Optical/nuclide dual-modality imaging agents for mapping SLN are ideal for preoperative planning and intraoperative biopsy, which are enabled by penetration-depth unlimited nuclide imaging and dynamic real-time optical imaging, respectively. However, commonly reported dual-modality imaging agents are composed of novel but safety-unproven materials, making their quick clinical translation challenging. Herein, we report a novel nanoparticle composed of facile hospital-available drugs and isotope for single-photon emission computed tomography (SPECT)/near-infrared (NIR) fluorescence imaging to detect SLNs. Indocyanine green-human serum albumin (ICG-HSA) nanoparticles (NPs) were synthesized by ICG-induced HSA self-assembly and further 99mTc-labeling via a one-step, facile hospital-available method. After injecting 99mTc-ICG-HSA into the rats' forepaw pads, the rats' draining axillary lymph nodes were visualized by preoperative mapping with SPECT/CT and intraoperative biopsy with NIR fluorescence. The axillary lymph nodes of rats were identified by pathology and fluorescent staining after execution. Additionally, its toxicity testing and comparison with 99mTc-sulfur colloid imaging were also explored. The study reported a self-assembled 99mTc-ICG-HSA with a high radiochemical yield (85.6 ± 3.8%). Compared with conventional 99mTc-sulfur colloid, 99mTc-ICG-HSA NPs showed faster SLN identification, higher renal clearance, and lower hepatic retention. Furthermore, NIRF imaging allowed for the accurate visualization of the SLN and guided SLN biopsy intraoperatively. Notably, the 99mTc-ICG-HSA NPs were composed of hospital-available drugs and isotope, which are safe for acute toxicity evaluation by a certified institute. The proposed 99mTc-ICG-HSA NPs are safe and capable of noninvasive SLN identification and biopsy guidance with multi-modal imaging strategies and could be a promising tool for clinically assisted SLN biopsy.

99mTc-Tilmanocept vs. Sulfur Colloid for Sentinel Node Biopsy for Melanoma in the Head and Neck.

The objective of the study is to compare sentinel lymph node (SLN) identification rates and performance characteristics of lymphoscintigraphy using 99mTc-sulfur colloid (SC) and 99mTc-tilmanocept (TL) for head and neck cutaneous melanoma.This study is a retrospective study, conducted at a single, tertiary care cancer center.Patients underwent sentinel lymph node biopsy (SLNB) for head and neck cutaneous melanoma, using SC or TL, between October 2014 and February 2019. Differences in SLN identification rates and performance characteristics between the groups were examined using the Mann-Whitney, or Fisher's exact test. Sixty patients underwent SLNB, of which 19 employed TL. There were no significant differences between SC vs. TL in operative duration (116 vs. 127min, P = 0.97), radiation dose (530 vs. 547μCi, P = 0.27), median number of SLNs removed (3 vs. 2, P = 0.32), or median follow-up (46.3 vs. 38.4months, P = 0.11). The rates of positive SLNs (17% vs. 37%, P = 0.11), intraoperative non-localization (12% vs. 16%, P = 0.70), and false-negative SLNB (5% each, P = 1.00) were not significantly different between groups. In patients with head and neck melanoma undergoing SLNB, 99mTc-tilmanocept may not differ from 99mTc-sulfur colloid in identifying SLNs or other performance characteristics. The added expense related to 99mTc-tilmanocept and lack of favorable performance data should urge caution in its adoption and promote further examination of its value in similar patient cohorts.

Phase 1 Trial of SPECT-Guided Liver-Directed Ablative Radiotherapy for Patients with Low Functional Liver Volume

Traditional liver dose constraints specify that a critical volume of 700 cc of non-tumor liver should be spared from receiving a hepatotoxic dose. We evaluated the safety of liver-directed ablative radiotherapy for patients with hepatocellular carcinoma (HCC), intrahepatic cholangiocarcinoma (iCCA), or liver metastases (LM) with Child-Pugh (CP) A5 liver function at baseline and with low functional liver volume as estimated by Tc-99m sulfur colloid single photon emission computed tomography (SPECT). We hypothesized that functional liver image guidance with SPECT would allow safe delivery of ablative radiotherapy in patients with limited liver volume. A phase 1 trial with a 3+3 design was conducted to evaluate the safety of comprehensive ablative radiotherapy to the liver disease using escalating functional non-target liver radiation dose constraints. Eligibility criteria included (1) a diagnosis of HCC, iCCA, or LM, (2) prior treatment with irinotecan or oxaliplatin chemotherapy or liver resection, and (3) a minimum functional liver volume of 400 cc as estimated by SPECT using a threshold of 40% maximum intensity. Patients with CP >A5 liver function, prior liver-directed radiotherapy, or prior Yttrium-90 therapy were excluded. The prescription dose was 67.5-75 Gy in 15 fractions or 75-100 Gy in 25 fractions. The volumetric dose constraint for functional non-target liver receiving <24 Gy for 15 fractions or <27 Gy for 25 fractions was determined by the dose level of trial enrollment: level 0 was ≥400 cc and level +1 was ≥300 cc. A level -1 was included if needed. We used standard 15 and 25 fraction dose constraints for other organs at risk. The following dose limiting toxicities (DLTs) were assessed within 6-8 weeks of completing radiotherapy: Grade 3 hypoalbuminemia, increase in INR, increase in bilirubin, or ascites, or Grade 4 hepatic failure or any radiation-related toxicity. Twelve patients enrolled between February 2016 and June 2022. The median (range) GTV was 36 (2-651) cc. The median CT anatomical non-tumor liver volume was 1584 (764-2699) cc, and the median SPECT functional liver volume was 1117 (570-1928) cc, with a Pearson correlation coefficient of 0.98 (p<0.001). The median non-target SPECT functional liver volume below the volumetric dose constraint was 684 (429-1244) cc. None of the 3 patients treated in dose level 0, and none of the 9 patients treated in dose level +1 experienced any DLTs. The 1-year in-treatment-field control rate was 55%, and 1-year overall survival was 71%. Ablative radiotherapy can be safely delivered using functional SPECT image guidance, which enables sparing lower volumes of functional liver than traditionally accepted in patients with CP A5 liver function. Further evaluation with a phase 2 study is warranted.

Liver Regeneration Following Radiation Therapy in Hepatocellular Carcinoma Patients: Insights from Functional Liver Imaging

A critical need for hepatocellular carcinoma (HCC) patients is understanding how the liver recovers following radiation therapy (RT). While liver regeneration after hepatic resection has been well-studied, liver recovery following RT is less understood. We have previously studied 99mTc-sulphur colloid (SC) single photon emission tomography (SPECT)/CT to spatially and quantitatively analyze liver function. The purpose of this study was to assess both volumetric and functional liver changes following RT. Patients with HCC had liver function assessed with SC SPECT/CT before and after definitive RT. Patients received 30-67.5 Gy in 4-15 fractions. Anatomic and functional liver metrics were assessed before and after treatment. The anatomic liver volume (ALV) was drawn on CT imaging. Liver function was measured as the functional volume encompassing 30% of maximum uptake (FLV) and mean liver-to-spleen uptake ratio (L/S). Changes in liver size and function were compared to clinical characteristics, including Child-Pugh (CP) score. Parametric t-tests were used to analyze the data. Of 23 evaluable patients (proton RT, n = 16 or photon RT, n = 7), 15 patients had CP-A5/6, 7 had CP-B7/8, and 1 had CP-C10 scores. The mean interval of SC SPECT was 67 days following RT (range, 44 to 113 days). The mean PTV was 272 cc (range 22-802 cc). Regarding baseline liver status, mean pre-treatment ALV was 1584 cc (range 810-2749 cc) with no significant difference in ALV between CP-A and B/C patients (p = 0.285). Pre-treatment mean liver function as assessed with L/S was 1.06 ± 0.43 with significantly greater function in CP-A compared to CP-B/C patients (1.27 vs 0.66, respectively, p<0.001). Mean pre-treatment FLV was 1351 ± 430.8 cc with no significant difference in FLV between CP-A and B/C patients (1422 ± 441 cc vs 1220 ± 436 cc, respectively, p = 0.31). When evaluating change following RT, the mean change in ALV was 0.9% (range, -29% to 23%) with no significant difference between CP-A and CP-B/C patients (-1.5% vs 5.4%, respectively, p = 0.19). In contrast, change in liver function following RT was larger; mean change in FLV was -20% (range, -55% to 33%) and mean change in L/S was -16% (range, -66% to 105%). While change in FLV was not significantly different between CP-A and CP-B/C patients, CP-B/C patients had significantly greater decline in mean liver function (L/S) than CP-A patients (-40 ± 18% vs -3.6 ± 36%, respectively, p = 0.018). There was no association between change in liver volume and change in L/S, p = 0.543. Functional liver imaging metrics reveal different information about the potential functional reserve of irradiated livers compared to anatomic measurements. These data imply that functional liver imaging may more accurately assess the regenerative potential of irradiated and non-irradiated volumes of liver, which may be useful in clinical scenarios where assessment of the function of future liver remnants become critical.

La linfogammagrafía in vivo de los tumores del seno nasal identifica el ganglio retrofaríngeo y el nivel I como ganglios centinela predominantes

ObjectiveTo evaluate by in vivo lymphoscintigraphy and SPECT-CT imaging, the lymphatic drainage patterns of para-nasal sinus (PNS) tumours. To confirm or refute the belief of the retropharyngeal lymph node (RPLN) being the significant draining lymph node for such tumours. MethodsProspective cohort study conducted on previously untreated PNS tumours with no clinico-radiological evidence of lymph node metastasis. Lymphoscintigraphy undertaken by nasal endoscopic assisted peritumoral injection of 99mTc sulphur colloid. Injections were classified as anterior or posterior as per a vertical line along the maxillary sinus ostium. ResultsSeventeen patients were included. Lymphoscintigraphy successfully identified 17 sentinel nodes in 15 patients and was unsuccessful (lymphoscintigraphy failure) in 2 patients. Predominant sites of sentinel lymphatic drainage were noted to be the RPLN (n=8; 47%) and level I (n=7; 42%). Occasional drainage was identified at the peri-parotid node (n=1) and at level II (n=1). Contralateral drainage was noted in 2 patients (level I-1 and RPLN-1).Anterior injections drained predominantly to level I (6/8) and RPLN (2/8), while posterior injections drained predominantly to the RPLN (6/7). The relative risk of RPLN being identified as the sentinel node was significantly higher for posteriorly placed injections than for anteriorly placed injections (RR: 3.43; 95% CI: 1.0-11.8; P=.05). ConclusionThe RPLN is noted as a frequent draining node for sino-nasal tumours and merits routine attention in all sino-nasal tumours. The radio-colloid SPECT-CT technique described here offers an excellent in vivo technique to further explore and validate the lymphatic drainage pathways of these tumours.

Utility of 99mTc-Sulfur Colloid Lymphoscintigraphy and SPECT/CT in Chylothorax and Chylous Ascites.

To assess the diagnostic efficacy of 99mTc-sulfur colloid lymphoscintigraphy in chylothorax and chylous ascites, and the utility of single-photon emission computed tomography-computed tomography (SPECT/CT) in localizing the sites of leaks. Data from patients who underwent lymphoscintigraphy for clinical suspicion of chylothorax or chylous ascites were retrospectively analyzed. Biochemical fluid analysis was taken as the reference standard. Pleural fluid triglyceride level > 110mg/dL (with pleural fluid/serum ratio > 1) and a cholesterol level < 200mg/dL (with pleural fluid/serum ratio < 1) were considered confirmatory for chylothorax. Ascitic fluid triglyceride level > 200mg/dL with a low cholesterol level (ascites fluid/serum ratio < 1) was considered confirmatory for chylous ascites. 26 patients (15 males, 57.7%) aged 9months to 68years were enrolled in the study. Based on the reference standard, 17 had chylothorax or chylous ascites (9 with surgical history). Lymphoscintigraphy was positive in 16 (with 1 false positive) and negative in 10 (with 2 false negatives). The sensitivity, specificity, negative predictive value, positive predictive value, and accuracy of lymphoscintigraphy were 88.2% (63.6-98.5%), 88.9% (51.8-99.7%), 80.0% (51.6-93.8%), 93.8% (70.1-99.0%), and 88.5% (69.9-97.6%), respectively. SPECT/CT could localize sites of leaks in 61.5% (8/13) with a localization rate of 77.8% (7/9) and 25.0% (1/4) in patients with surgical and nonsurgical causes, respectively. 99mTc-sulfur colloid lymphoscintigraphy is a highly efficacious noninvasive modality to diagnose chylothorax or chylous ascites with a high positive predictive value. SPECT/CT could localize the sites of leaks more frequently in patients with surgical causes.

In-vivo lymphoscintigraphy of sinonasal tumors identifies retropharyngeal node and level I as predominant sentinel nodes

ObjectiveTo evaluate by in- vivo lymphoscintigraphy and SPECT-CT imaging, the lymphatic drainage patterns of para-nasal sinus(PNS) tumors. To confirm or refute the belief of the retropharyngeal lymph node (RPLN) being the significant draining lymph node for such tumors. MethodsProspective cohort study conducted on previously untreated PNS tumors with no clinico-radiological evidence of lymph node metastasis. Lymphoscintigraphy undertaken by nasal endoscopic assisted peritumoral injection of 99mTc Sulfur colloid. Injections were classified as anterior or posterior as per a vertical line along the maxillary sinus ostium. Results17 patients were included. Lymphoscintigraphy successfully identified 17 sentinel nodes in 15 patients and was unsuccessful (lymphoscintigraphy failure) in 2 patients. Predominant sites of sentinel lymphatic drainage were noted to be the RPLN (n = 8; 47%), and Level I (n = 7; 42%). Occasional drainage was identified at the peri-parotid node(n = 1) and at Level II (n = 1). Contralateral drainage was noted in 2 patients (level I-1 and RPLN-1).Anterior injections drained predominantly to Level I (6/8) and RPLN (2/8), while posterior injections drained predominantly to the RPLN ( 6/7). The relative risk of RPLN being identified as the sentinel node was significantly higher for posteriorly placed injections than for anteriorly placed injections (RR- 3.43; 95% CI-1.0-11.8, p = 0.05). ConclusionThe RPLN is noted as a frequent draining node for sino-nasal tumours and merits routine attention in all sino-nasal tumors. The radio-colloid SPECT-CT technique described here offers an excellent in-vivo technique to further explore and validate the lymphatic drainage pathways of these tumours.

Evaluation of three different 99mTc-based mock-venom agents for lymphoscintigraphy studies in preclinical models of peripheral snakebite envenomation

Snakebite envenomation is one of the major public health concerns across many countries; with the WHO designating it as a ‘priority neglected tropical disease’ and stressing for a need to develop novel therapeutic strategies to reduce death and disability rate by end of 2030. Since a major component of venom; the high molecular weight (HMw) toxins enter the bloodstream through lymphatic system, research is focusing on modulating the lymphatic flow rate after topical application of suitable drug candidates. Present study compared the suitability of three radiopharmaceutical agents, namely 99mTc-Sulfur colloid (SC), 99mTc-Phytate (Phy) and 99mTc-Human serum albumin (HSA), to be used as mock-venom agent in studying modulation in lymphatic flow rate in preclinical models of peripheral snakebite envenomation using lymphoscintigraphy studies. The study was performed in 72 Sprague Dawley rats; divided into six groups of 12 rats each. Control groups were given intradermal injection (1.29–1.48 MBq in 100 μl normal saline) of either 99mTc-Phy/ 99mTc-SC/ 99mTc-HSA into the tail as ‘mock-venom’. In respective test groups, commercially available topical formulation (Anobliss® Cream) containing Nifedipine (Nif; 0.3% w/w) and Lidocaine (Lid; 1.5% w/w) was applied topically over the animals' lower body (tail and hind limbs) immediately within 20s of administering intradermal injection of the radiopharmaceutical. Any modulation in lymph transit time from periphery to systemic circulation was assessed using lymphoscintigraphy by taking dynamic gamma-scintigraphy images of 60s each till 1 h post-injection of the test radiopharmaceuticals. Significant difference in movement of the three radiopharmaceuticals was noted in terms of their lymphatic movement. 99mTc-Phy did not show significant travel through the lymphatics and the liver was faintly visualized in control as well as test intervention groups. In case of 99mTc-SC, significant changes in movement of the radiotracer after topical application of Nif/Lid in the test intervention groups were clearly noted in comparison to control (P < 0.05). Multiple numbers of lymph nodes (LNs) could be clearly visualized in control (5 ± 1 LNs) and test intervention groups (3 ± 1 LNs). Liver uptake was more prominent in control animals and it reduced significantly in test intervention groups. On the other hand, 99mTc-HSA showed lesser number of lymph nodes and higher accumulation in liver as compared to 99mTc-SC, suggesting very fast movement of this radiopharmaceutical. Results indicates that 99mTc-SC could be used as a suitable agent to mimic lymphatic transit behavior of HMw toxin components of snake venom and could therefore be used as a model in studying the effect of any test pharmacological intervention in modulating lymphatic transit rate. Additional advantage could be a significant reduction in the need for sacrificing large number of animals, particularly during initial screening phase of drug development cycle.

Active bone marrow-sparing to reduce the incidence of grade 3+ acute hematologic toxicity in patients with locally advanced cervical cancer who receive chemoradiotherapy: A single-center prospective randomized controlled trial.

5524 Background: Acute haematologic toxicity is the most common side effect of chemoradiotherapy in patients with locally advanced cervical cancer .We aim to test the efficacy of single-photon emission computed tomography-defined active bone marrow-sparing volumetric-modulated arc therapy in reducing grade 3+ acute hematologic toxicity (HT) in locally advanced cervical cancer patients treated with chemoradiotherapy. Methods: This was a prospective, single-center, open label, randomized clinical trial that enrolled locally advanced cervical cancer patients. Participants were randomized to the 99mTc sulfur colloid SPECT-defined ABMS VMAT (ABMS group) or control group, who received weekly cisplatin concurrently with volumetric-modulated arc therapy followed by high-dose-rate intracavitary brachytherapy. The ABMS group additionally received SPECT-defined ABM dose constraints. The primary endpoint was the incidence of grade 3+ acute hematologic toxicity.Secondary objectives included acute gastrointestinal toxicity, planning Target Volume (PTV) coverage, dosimetric parameters of organs at risk (OARs), progression-free survival (PFS), overall survival (OS). Results: A total of 192 FIGO stage IB-IIIB patients were randomized treated (96 each in the ABMS control groups). The median follow-up was 24.0 months. The incidence of grade 3+ acute hematologic toxicity in the ABMS group was significantly lower than that in the control group (32.3% vs 53.1%, p&lt;0.01). The number of patients completing five cycles of cisplatin was 88.5% in the ABMS group and 75% in the control group, and the difference was significant (p=0.02). There were no significant differences in the mean dose to 95%, 97% and 99%of the PTV between the ABMS group (45.1 Gy, 44.6 Gy, and 43.3 Gy, respectively) and the control group (45.4 Gy, 44.8 Gy, and 43.6 Gy). There were no differences in dosimetric parameters of OARs ,acute gastrointestinal toxicity, 2-year PFS or 2-year OS between the two groups. Patients in the control group had nonsignificantly worse 2-year distant metastasis than patients in the ABMS group (17.8% vs. 11.1%, p=0.19). Conclusions: ABMS VMAT significantly reduced grade 3+ acute HT and improved chemotherapy delivery compared with the control treatment. We found weak evidence of the effect of ABMS VMAT on distant metastasis. Clinical trial information: ChiCTR-IOR-16010214 .

Pneumatic compression therapy using the EQ Press accelerates lymphatic flow in healthy equine forelimbs as determined by lymphoscintigraphy.

Limb lymphedema in horses can be debilitating and painful. Pneumatic compression therapy has shown significant benefits for people suffering from lymphedema. The objective of this study was to determine the effect of a novel, equine-specific pneumatic compression device on the lymphatic flow of healthy horse forelimbs as determined by Tc-99m sulfur colloid lymphoscintigraphy. 6 healthy Thoroughbreds. In a randomized crossover design, horses underwent bilateral forelimb lymphoscintigraphy following subcutaneous injection of Tc-99m sulfur colloid at the coronary band as untreated control or with pneumatic compression therapy using the EQ Press. Lateral, static images were obtained of the distal limb (time 0 to 60 minutes) and proximal limb (time 30 to 60 minutes) using a standard gamma camera. Lymphatic flow was determined by assigning a score to the time point at which Tc-99m sulfur colloid was first visualized at the level of the accessory carpal bone (1 to 7) in the distal limb and the cubital lymph node (1 to 4) in the proximal limb. EQ Press treatment led to a significantly faster lymphatic flow of Tc-99m sulfur colloid to the predetermined anatomic locations of the accessory carpal bone (P = .002) in the distal limb and the cubital lymph node (P = .001) in the proximal limb. Pneumatic compression therapy as provided by an equine-specific device encouraged lymphatic flow in healthy, nonedematous equine forelimbs. These data support further study of the EQ Press for pneumatic compression therapy in horses clinically affected by lymphedema and lymphatic drainage disorders.

Determining the Best First-line Modality for Identifying and Localizing Skull Base CSF Leaks

Background: Patients with skull base cerebrospinal fluid (CSF) leaks present with headaches, fluid in the ear(s), and/or rhinorrhea, which are vague symptoms. Beta-2-transferrin protein assays are the gold standard for identifying CSF leaks, but adequate samples cannot always be collected, and the results give no specific localizing information. Medical imaging, including Computed Tomography (CT), Magnetic Resonance (MR), and Nuclear Medicine (NM) cisternography can be utilized to identify and localize CSF leaks, but are imperfect tests. This study aims to determine the best imaging modality for identifying and localizing skull base CSF leaks by comparing CT, MR, and NM Cisternogram results to beta-2-transferrin assay and intraoperative visualization as criterion standards.&#x0D; Methods: In this ongoing study, patient cisternogram and pre-cisternogram imaging and results were acquired from the electronic medical record, radiology information system, and picture archiving and communication system. Inclusion criteria include age greater than 18, suspected skull base CSF leak, and CT, MR, and/or NM cisternogram performed. MR cisternogram procedure included intrathecal gadolinium and NM SPECT-CT cisternogram procedure included intrathecal Tc-99m Sulfur Colloid. These data will be analyzed for positive and negative predictive values, sensitivity, specificity, and ROC Curve comparing to beta-2-transferrin assay results and surgical findings.&#x0D; Results: From 2018-2022, 30 patients with suspected skull base CSF leaks were evaluated. In this limited preliminary data set, MR was more sensitive than CT, CT was more sensitive than NM, there were three false negatives, and there were no false positives. Performing two types of cisternogram increased the chance of identifying leaks. More data is needed to draw stronger conclusions in this ongoing study.&#x0D; Conclusion/Potential Impact: The initial data suggests that MR cisternogram with intrathecal gadolinium is superior to CT and SPECT-CT cisternogram for detecting skull base CSF leaks. Localizing skull base CSF leaks helps enable surgeons to perform less invasive corrective procedures.

Evaluation of Preoperative and Intraoperative Mobile Gamma Camera Imaging in Sentinel Lymph Node Biopsy for Melanoma Independent of Preoperative Lymphoscintigraphy

IntroductionSentinel lymph node biopsy (SLNB) is a standard practice for staging cutaneous melanoma. High false-negative rates have an increased interest in adjunctive techniques for localizing SLNs. Mobile gamma cameras (MGCs) represent potential tools to enhance SLNB performance. MethodsAn institutional review board approval was obtained for this study (ClinicalTrials.gov ID NCT01531608). After obtaining informed consent, 20 eligible melanoma patients underwent 99mTc sulfur colloid injection and standard lymphoscintigraphy with a fixed gamma camera (FGC). A survey using a 20 cm square MGC, performed immediately preoperatively by the study surgeon, was used to establish an operative plan while blinded to the FGC results. Subsequently, SLNB was performed using a gamma probe and a novel 6 cm diameter handheld MGC. ResultsA total of 24 SLN basins were detected by FGC. Prior to unblinding, all 24 basins were identified with the preoperative MGC and the operative plan established by preoperative MGC imaging was confirmed accurate by review of the FGC images. All individual sentinel lymph nodes were identified during intraoperative MGC imaging, and in 5/24 (21%) cases, surgeon-reported additional clinically useful information was obtained from the MGC. ConclusionsPreoperative MGC images provide information consistent with FGC images for planning SLNB and in some cases provide additional information that aided in surgical decision-making.