How much time is enough? Sentinel lymph node mapping time depends on the radiotracer agent.

BACKGROUND: In 2014, technetium-99m tilmanocept (TcTM) replaced technetium-99m sulfur colloid (TcSC) as the standard lymphoscintigraphy (LS) mapping agent in melanoma patients undergoing sentinel lymph node biopsy (SLNB). The aim of this study was to examine differences in mapping time, intra-operative identification of sentinel lymph node (SLN), and false negative rate (FNR) between patients who underwent SLNB with TcTM compared to TcSC. METHODS: Patients who underwent SLNB between 2010 and 2018 were retrospectively identified. Patient demographic, tumor, and imaging data was stratified by receipt of TcSC (n = 258) or TcTM (n = 133). Student's t test and χ2 test were used to compare characteristics and outcomes. RESULTS: Both cohorts were similar in demographic, primary tumor characteristics, and total number of SLN identified (TcTM 3.56 vs. TcSC 3.28, p = 0.244). TcTM was associated with significantly shorter LS mapping times (51.8 vs. 195.1 min, p < 0.01). There was no significant difference in the number of patients with positive SLN (TcTM 11.3 vs. TcSC 17.4%, p = 0.109) and the FNR was similar between both groups (TcTM 25% vs. TcSC 22%). CONCLUSION: TcTM was associated with significantly shorter LS mapping time while identifying similar numbers of SLN. Our results support further study to ensure similar FNR and oncologic outcomes between agents.

Contribution of Lymphoscintigraphy for Sentinel Lymph Node Biopsy in Women with Early Stage Endometrial Cancer: Results of the SENTI-ENDO Study.

BACKGROUND: This study was designed to evaluate detection rate and anatomical location of sentinel lymph node (SLN) at lymphoscintigraphy, to compare short and long lymphoscintigraphy protocols, and to correlate lymphoscintigraphic and surgical mapping of SLN in patients with early-stage endometrial cancer (EC). METHODS: Subanalysis of the prospective multicenter study Senti-endo performed from July 2007 to August 2009. Patients with stage I and II EC received four cervical injections of 0-2 mL of unfiltered technetium sulphur colloid the day before (long protocol) or the morning (short protocol) before surgery. SLN detection used a combined technetium/patent blue labeling technique, and all patients had a systematic bilateral pelvic lymphadenectomy. RESULTS: A total of 133 patients were enrolled in the study and 118 (94.5 %) underwent a lymphoscintigraphy. Of these 118 patients, 44 (37 %) underwent a short protocol and 66 (56 %) a long protocol (data on lymphoscintigraphy were not available in eight patients). Lymphoscintigraphic detection rate was 74.6 % (34 % for short protocol and 60.2 % for long protocol). No difference in the detection rate was observed according to lymphoscintigraphy protocol (p = 0.22), but a higher number of SLN was noted for the long protocol (p = 0.02). Aberrant drainage was noted on lymphoscintigraphy in 30.5 % of the patients. Paraaortic SLNs were exclusively detected using the long protocol. A poor correlation was noted between short (κ test = 0.24) or long lymphoscintigraphy (κ test = 0.3) protocol and SLN surgical mapping. CONCLUSIONS: Our study demonstrates that preoperative lymphoscintigraphy allowed a high SLN detection rate and that long lymphoscintigraphy protocol was associated with a higher detection of aberrant drainage especially in the paraaortic area.

Slow gastric emptying in type I diabetes: relation to autonomic and peripheral neuropathy, blood glucose, and glycemic control.

OBJECTIVE: To investigate whether autonomic neuropathy or hyperglycemia plays a crucial etiological role in gastric retention of ingesta frequently found in type I diabetic patients. RESEARCH DESIGN AND METHODS: We investigated the gastric emptying of a radiolabeled semisolid 1,168 kJ meal in 38 female and 45 male patients (age 18-75 years; illness duration 3-46 years). None took drugs affecting gastrointestinal motility. Fasted patients underwent tests of cardiovascular autonomic and peripheral nerve function. Blood glucose levels were determined before and after the scintigraphic recording of gastric emptying. RESULTS: The percentage of meal remaining in the stomach at the end of the 50-min recording time was related significantly to the patients' degree of cardiovascular autonomic neuropathy [r (81) = 0.235, P < 0.028] but not to their degree of peripheral neuropathy, preprandial blood glucose level, HbA1c indicative of glycemic control, diabetes duration, and age. The patients' mean residual percentage of meal was significantly greater than that of 48 healthy subjects, that is, 71.1 +/- 15.1 vs. 53.5 +/- 13.1% [means +/- SD; t (129) = 6.48, P < 0.0001]. The healthy individuals' mean residual percentage + 2 SD was exceeded in 22 patients. CONCLUSIONS: Slow gastric emptying in patients with type I diabetes seems related to the degree of autonomic neuropathy but not to peripheral neuropathy, actual blood glucose, and glycemic control.

Hepatocellular adenoma case report with Tc-99m SC uptake and radiologic correlation.

An uncommon case of hepatocellular adenoma is presented. In this case, the tumor was Tc-99m SC avid rather than the typical pattern of no uptake. Liver scintigraphy was able to demonstrate that the tumor originated from the liver correlating with ultrasound and computed tomography. Background information on hepatocellular adenomas, a differential diagnosis, and a logical approach to similar liver lesions is discussed.

Inactivation of Kupffer cells after prolonged donor fasting improves viability of transplanted hepatic allografts.

Data from recent studies suggest that donor fasting imparts a beneficial effect on the viability of transplanted hepatic allografts. Because starvation may temporarily inactivate Kupffer cells, and because these cells are the likely mediators of liver injury after prolonged preservation-reperfusion, the purpose of this study is to establish a link between improved organ viability and Kupffer cell inactivation caused by donor allograft fasting. In an in vivo rat liver transplant model, 48 hours of donor fasting (1) improved allograft viability, (2) significantly decreased Kupffer cell phagocytosis, and (3) significantly decreased cytokine (tumor necrosis factor [TNF]) production postrevascularization. These data validate work from previous studies demonstrating that donor fasting improves allograft viability and furthermore support our previous research implicating activation of Kupffer cells as a causative agent of cold ischemia-preservation injury.

Effect of acute burn trauma on reticuloendothelial system phagocytic activity in rats. II: Comparison of uptake of radiolabelled colloid and bacteria.

The uptake of radiolabelled colloid or bacteria was compared in normal rats and animals subjected to acute burn trauma. The uptake of colloid by the liver was unaffected by burn trauma, but uptake of the labelled bacteria was reduced. Spleen uptake of both colloid and bacteria was reduced by burn trauma while lung uptake was increased. These data are consistent with the hypothesis that acute burn trauma alters reticuloendothelial system phagocytic activity in the rat towards both inert particles and live bacteria.

The "critical colloid dose" in studies of reticuloendothelial function.

The [99mTc]sulfur colloid distribution in rat organs was investigated after the administration of different amounts of colloid particles. Saturation of the liver and spleen was not observed. Blood clearance was significantly reduced 15 min after injection above approximately 3 X 10(9) particles per kg body weight. With an increasing number of injected particles, lung uptake increased and bone marrow uptake decreased. Microfiltration studies showed that the colloid is unaffected by dilution with saline but may be affected after incubation in normal rat plasma. We conclude that the distribution of [99Tc]sulfur colloid in organs varies with the number of injected particles and therefore, is not dependent upon the blood flow to the reticuloendothelial organs alone. The "critical colloid dose" may differ among the reticuloendothelial organs and cannot, therefore, be evaluated by blood clearance measurements alone. The considerable influence of the number of injected colloid particles on bone marrow uptake should also be recognized when carrying out dosimetric calculations.

Accumulation of technetium-99m sulfur colloid by hepatocellular adenoma: scintigraphic-pathologic correlation.

It is currently believed that hepatocellular adenoma is photon deficient on technetium-99m sulfur colloid scintigraphy because these tumors lack Kupffer cells. In a retrospective review of 13 pathologically proven cases of hepatocellular adenoma with technetium-99m sulfur colloid scintigrams, Kupffer cells were present in all 13 cases. We observed uptake of the radiocolloid by the hepatocellular adenoma in three cases (23%), and there were no histologic differences between the tumors with uptake and the ones without it. We conclude that the currently accepted reason for the lack of technetium-99m sulfur colloid uptake within hepatocellular adenoma is incorrect, and an explanation other than a lack of Kupffer cells is responsible for the photon-deficient appearance in the majority of cases of hepatocellular adenoma. Further, because hepatocellular adenoma may have technetium-99m sulfur colloid uptake in a significant percentage of cases, it should be added to focal nodular hyperplasia in the differential diagnosis of a hepatic mass with uptake by technetium-99m sulfur colloid.

Diffuse lung uptake of technetium-99m sulfur colloid associated with fatty liver disease of pregnancy.

Diffuse pulmonary uptake of sulfur colloid was seen in a 35-year-old postpartum white female with the presumptive diagnosis of fatty liver disease of pregnancy. As the disease process resolved, the pulmonary uptake of sulfur colloid disappeared. To the authors' knowledge, this scan association has not been previously reported.

Formation of labelled colloid in 99Tcm-DMSA due to the presence of bactericidal fluid.

The possibility that traces of bactericidal fluid in 99Tcm-DMSA could lead to the formation of labelled colloid, was explored. In vitro investigations were undertaken using ultracentrifugation techniques and photon correlation spectroscopy. The latter showed that both contaminated and uncontaminated DMSA contained colloidal (or particulate) material. However the presence of 10 microliters bactericidal fluid as contaminant was shown by ultracentrifugation to result in labelling of this colloidal material when 99Tcm was added to DMSA. Studies in a normal volunteer confirmed the results of the in vitro studies, in that significant liver and spleen uptake was observed after the administration of contaminated 99Tcm-DMSA.

Compartment modelling in nuclear medicine: a new program for the determination of transfer coefficients.

In many investigations concerning transport/exchange of matter in a natural system, e.g. functional studies in nuclear medicine, it is advantageous to relate experimental results to a model of the system. This paper presents a new computer program for the determination of linear transfer coefficients in a compartment model from experimentally observed time-compartment content curves. The program performs a least-square fit with the specified precision of the observed values as weight factors. The resulting uncertainty in the calculated transfer coefficients may also be assessed. The application of the program in nuclear medicine is demonstrated and discussed.

Internal dosimetry evaluations: a computerized approach.

A computerized approach to the average absorbed dose calculations in the standard human body is reported. For each selected radionuclide, a matrix S of the order n X n is constructed and stored in the computer. The matrix elements consist of the absorbed dose coefficients per unit cumulated activity (rad microCi-1 hr-1) for n different organs. Each element Sij of the matrix S represents the average dose contribution from a particular radionuclide uniformly distributed in the source organ j to the target organ i. Therefore, the diagonal elements of S represent the average absorbed dose contribution from each organ to itself (target to target). The different organ uptake coefficients and the biological half-lives of several elements and compounds gathered from the literature were organized and stored on the computer disk. During dosimetry evaluations, the system retrieves the physical half-life of the involved radionuclide, searches for the appropriate biophysical factors, computes the cumulated activities Ai of the n organs and then constructs the cumulated activity vector A. The estimates of the average dose absorbed in the various targets are presented by the organ dose vector D. Hence, the dosimetry evaluations of all organs may be obtained by simply multiplying the matrix S by the column vector A.

Comparison of three RE agents-99mTc-phytate, 99mTc-sulfur colloid and 99mTc-Sb2S3 colloid in the rodent species.

99mTc-phytate, 99mTc-sulfur colloid and 99mTc-antimony sulfide colloid are recognised as RE agents in clinical nuclear medicine. Since these three agents exist in vitro in different forms of particulate aggregation it was of interest to compare their properties and to evaluate the merits and limitations of each of these agents. A comparison was carried out in rats and rabbits as a prelude to a systematic study in human subjects. Quality tested radiopharmaceuticals were prepared and their pharmacokinetics studied in rats. The blood clearance, tissue distribution and scinti-imaging patterns of the RE system were also compared in rabbits. All the agents have excellent localizing properties in the liver but differ in varying extents in their disposition in other tissues. 99mTc-sulfur colloid has some predisposition for the lungs while 99mTc-phytate has a little propensity for the kidney and gut at late time periods. 99mTc-Sb2S3 colloid shows a more pronounced concentration in the bone-marrow, and displays intermediate properties between 99mTc-phytate and 99mTc-sulfur colloid, besides being the most stable (in vitro) radiopharmaceutical in this series of RE agents.

Effect of atropine on oral clearance of a radiolabeled sulfur colloid.

Physical clearance is an important oral defense mechanism against gram-negative rods. We describe a simple technique that uses commercially available technetium-99m sulfur colloid to measure oral clearance. Technetium-99m sulfur colloid was sprayed into the mouth, and clearance was measured as the percent decrease in radiolabel counts over 2 hours using a radioisotope camera. Results using this technique compared favorably with clearance data using Tc-99m radiolabeled Escherichia coli. Atropine significantly decreased oral clearance rates of the colloid. Decreased clearance may be an important risk factor in the development of gram-negative rod colonization in hospitalized patients.