99mTc Research Articles

Myocardial perfusion/metabolism mismatch and ventricular arrhythmias in the chronic post infarction state.

Ventricular arrhythmias have been shown to originate in the myocardial peri-infarct region due to irregular heterotopic conduction. Hypoperfused but viable myocardium is often localised in those areas and may be involved in the pathogenesis of arrhythmias. We tested the hypothesis that these myocardial perfusion/metabolism mismatches (MM) are significantly associated with ventricular arrhythmias in the chronic post infarction state. 47 post infarction patients were included in the study. 33 suffered from ventricular arrhythmia whereas 14 did not. All patients underwent (99m)Tc tetrofosmin SPECT and (18)F-FDG PET. A region-of-interest(ROI)-analysis was used to assess viable myocardium based on predefined MM-criteria. Univariate analyses as well as a logistic regression model for the multivariate analysis were carried out. 94% of the arrhythmic patients displayed at least one MM-segment as compared to 64% of the non-arrhythmic patients. MM-segments and arrhythmia showed a statistically significant relation (p = 0.018). The logistic regression model predicted the occurrence or absence of arrhythmia in 85% of all cases. Multivariate analysis gave consistent results, after adjusting for symptomatic chronic heart failure (CHF), aneurysms and age. Our results support the hypothesis that hypoperfused but viable myocardium represents an arrhythmogenic substrate and is a relevant risk factor for developing ventricular arrhythmias following myocardial infarction. Therefore, the detection of MM-segments allows the identification of patients with a higher risk for future cardiac events.

Comparison of diagnostic accuracy of 18F-FDG PET, 123I-IMT- and 99mTc-MIBI SPECT Evaluation of tumour progression in irradiated low grade astrocytomas

To evaluates the diagnostic accuracy of the SPECT-tracers 3-(123)I-alpha-methyl-L-tyrosine (IMT) and (99m)Tc(I)- hexakis(2-methoxyisobutylisonitrile) (MIBI) as well as the PET-tracer 2-(18)F-2-deoxyglucose (FDG) for detecting tumour progression in irradiated low grade astrocytomas (LGA). We examined 91 patients (56 males; 35 females; 44.7 +/- 11.5 years), initially suffering from histologically proven LGAs (mean WHO grade II) and treated by stereotactic radiotherapy (59.0 +/- 4.6 Gy). On average 21.9 +/- 11.2 months after radiotherapy, patients presented new Gd-DTPA enhancing lesions on MRI, which did not allow a differentiation between progressive tumour (PT) and non-PT (nPT) at this point of time. PET scans (n = 82) were acquired 45 min after injection of 208 +/- 32 MBq FDG. SPECT scans started 10 min after injection of 269 +/- 73 MBq IMT (n = 68) and 15 min after injection of 706 +/- 63 MBq MIBI (n = 34). Lesions were classified as PT and nPT based on prospective follow-up (clinically, MRI) for 17.2 +/- 9.9 months after PET/SPECT. Lesion-to-normal ratios (L/N) were calculated using contra lateraly mirrored reference regions for the SPECT examinations and reference regions in the contra lateral grey (GM) and white matter (WM) for FDG PET. Ratios were evaluated by Receiver Operating Characteristic (ROC) analysis. In the patient groups nPT and PT, L/N ratios for FDG (GS) were 0.6 +/- 0.3 vs. 1.2 +/- 0.5 (p = 0.003), for FDG (WS) 1.2 +/- 0.4 vs. 2.6 +/- 0.4 (p < 0.001), for IMT 1.1 +/- 0.1 vs. 1.8 +/- 0.4 (p < 0.001) and for MIBI 1.6 +/- 0.7 vs. 2.6 +/- 2.2 (p = 0.554). Areas under the non-parametric ROC-curves were: 0.738 +/- 0.059 for FDG (GS), 0.790 +/- 0.057 for FDG (WS), 0.937 +/- 0.037 for IMT and 0.564 +/- 0.105 for MIBI. MIBI-SPECT examinations resulted in a low accuracy and especially in a poor sensitivity even at modest specificity values. A satisfying diagnostic accuracy was reached with FDG PET. Using WM as reference region for FDG PET, a slightly higher AUC as compared to GM was calculated. IMT yielded the best ROC characteristics and the highest diagnostic accuracy for differentiating between PT and nPT in irradiated LGA.

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.

USVAH Study Demonstrates Statistically Significant Improvement in Diagnosis and Care of U.S Veterans Using FMTVDM – FHRWW©℗ “Quantitative” Nuclear Imaging. The Era of Truly Quantitative Stress- First, Stress-Only Imaging has begun!

Background: Myocardial perfusion imaging (MPI) has evolved over the last several decades with improvements in equipment and isotopes. Despite these limitations sensitivity and specificity of this study remains 65%-85% principally due to “qualitative” interpretation of the results. Numerous investigators have recommended changes in protocols and quantification of data to increase the diagnostic accuracy of this non-invasive physiologic test. Initial investigations have demonstrated the ability to “quantitatively” measure isotope redistribution with planar, SPECT and PET using FMTVDM©℗. This study was designed to compare the diagnostic and treatment outcomes of U.S. Veterans undergoing conventional “stress-rest” “qualitative” imaging using Technetium 99m isotopes (Sestamibi and Myoview) compared with FMTVDM©℗ “quantification” isotope redistribution using a single dose of the isotope.Methods: Forty-one U.S. Veterans were studied using pharmacologic and exercise stress approaches with either Sestamibi or Myoview following routine MPI Imaging protocols compared with FMTVDM©℗. The results were compared with coronary angiography.Result: Angiographic coronary artery disease (CAD) was defined using both 50% and 70% diameter narrowing/ stenosis (%DS). Accuracy of a “qualitative” (yes/no) test in the determination of the presence or absence of CAD is measured by the ability of the test to find CAD when present (sensitivity) and to show that CAD is not present (specificity) when absent, based upon the arbitrarily assigned value for %DS. The sensitivity, specificity and accuracy of “qualitative” MPI assessment of 50% DS CAD was 50.0%, 88.2% and 70.7% for the left coronary artery system and 29.2%, 64.7% and 43.9% respectively for the right coronary artery system. These values improved to 59.1%, 89.5% and 73.2% for the left coronary artery system and 64.3%, 85.2% and 78.0% respectively for the right coronary artery system when 70%DS was used as the cutoff for CAD. No differences noted between either of the technetium 99m isotopes or cameras used for either the “qualitative” or “quantitative” (FMTVDM©℗) methods. FMTVDM©℗ provides the First Ever “quantitative” Nuclear Cardiology MPI test, which consequently defines CAD not on a yes/no basis, but “quantitatively.” As such, the accuracy of FMTVDM©℗ must be compared first to a “quantitative” measure which is known; viz. isotope decay using TFM. Results of FMTVDM©℗ is then not simply a yes/no result, but rather a “quantitative” value which places the “extent” of CAD on a measured continuum much as a coronary angiogram would, specifically a quantitative coronary angiogram (QCA). FMTVDM©℗ demonstrated a statistically significant relationship between CAD and %DS (r=0.75, p < 0.001).Conclusion: Modern Nuclear Cameras have relied completely upon “quality” control methods, which do exactly that; they provide for “qualitative” control but not “quantitative” control. The accuracy of the cameras ability to correctly count the resulting scintillations from which “quantitative” analysis and even “qualitative” images are displayed for clinician interpretation are dependent, has never been established or used in either the experimental or clinical areas of Medicine. This study demonstrated the importance of first using TFM from the FMTVDM©℗ for “quantitative” camera calibration and correction prior to conducting MPI. Even with the correction of the “quantitative” errors in the Nuclear Cameras, errors in “qualitative” MPI resulted in a conservative estimate of misdiagnosis of CAD 35% of the time. These errors result in potential life threatening CAD being missed as demonstrated here. This same CAD is accurately measured using the new “quantitative” MPI test (FMTVDM©℗), which accurately “quantify” the extent of CAD. FMTVDM©℗ provides the first “quantitative” Nuclear Cardiology and Medicine test, ushering in the era of “machine learning” and “quantitative” Nuclear Cardiology and Medicine providing accurate, reproducible measurement of CAD in less time and with less radiation than the prior “qualitatively” applied method of “physician interpretation” of CAD, reducing healthcare costs and improving patient throughput and clinical management.

Unmasking a Meckelʼs Diverticulum: Using Capsule Endoscopy and Ranitidine!

Introduction: Meckel's Diverticulum, a remnant of the omphalomesenteric duct, is a congenital malformation of the GI tract with ectopic tissue. Diverticulum containing gastric mucosa have increased rates of bleeding. A Meckel's Scan is often used for diagnosis but, as this case shows, is not always reliable.Figure: Capsule endoscopy.Figure: Meckel's Scan.Figure: Intraoperative picture.Case Description: A healthy 20-year-old male presents with hematochezia. He denied symptoms of abdominal pain, or systemic signs such as iritis, oral ulcers, perianal fistula or joint pains. There was no infectious exposure or recent antibiotic use. He was hemodynamically stable with a hemoglobin drop to 7.0 gm/dL from a normal baseline. Workup involved upper and lower endoscopy without a bleeding source identified. Bleeding ultimately self-resolved and hemoglobin stabilized prior to discharge. The patient underwent Meckel's scan, and CT angiography without identifiable source. One year later he represented to the hospital with worsening hematochezia. He was in hemorrhagic shock requiring ICU admission and multiple transfusions. Repeat upper and lower endoscopy were again negative, as was MRI enterogram. Capsule endoscopy was suspicious for a diverticulum in distal small bowel. Meckel's scan, was repeated with pre-procedural administration of ranitidine for 3 days. Scan revealed increased metabolic activity in the right lower quadrant, consistent with Meckel's diverticulum. The patient underwent small bowel resection of the involved segment without return of symptoms at follow up. Discussion: The incidence of gastric mucosa in Meckel's diverticulum is estimated to be between 30-60%, but prevalence is almost 100% when bleeding is present due to ulceration risk. 99m technetium pertechnetate, used in a Meckel's scan, is an isotope taken up by gastric mucosa aiding identification of ectopic sites. Sensitivity of a Meckel's scan ranges from 60-97% with a specificity of 95%. Ranitidine increases nuclear tracer retention and reduces washout via slowing of its release from gastric mucosal cells, increasing test sensitivity. Pre-administration of ranitidine should be used as an adjunct maneuver for identification of Meckel's diverticulum if clinical suspicion is high. In our patient capsule endoscopy findings prompted us to revisit the diagnosis and repeat the scan with ranitidine confirming the diagnosis.

Anti-inflammatory/infection PLA nanoparticles labeled with technetium 99m for in vivo imaging

Despite advancements in treatment of infectious diseases, opportunistic pathogens continue to pose a worldwide threat. Identifying a source of infection/inflammation is often challenging which highlights the need of improved diagnostic agents. Using a model of local S. aureus infection, here we evaluated the potential of betamethasone or dexamethasone loaded in poly (lactic acid) nanoparticles and radiolabeled with 99mTc to detect an infection/inflammation site in vivo. A betamethasone and dexamethasone nanoparticles (NPs) with 200 and 220 nm in size, respectively, were created with a 98% 99mTc radiolabeling efficiency. When injected in infected mice, betamethasone NPs presented a higher accumulation in the infected hind paw in comparison with dexamethasone NPs. Our results suggest that this nanosystem may be a valid nanoradiopharmaceutical for the detection of inflammation/infection foci in vivo.

Thyrotoxicosis induced by excessive 3,5,3′-triiodothyronine in a dog

CASE DESCRIPTION A 7-year-old castrated male Havanese was evaluated at a veterinary teaching hospital because of a 12-week history of hyperactivity, aggression, and progressive weight loss despite a healthy appetite. CLINICAL FINDINGS Tachycardia was the only remarkable finding during physical examination. Serum 3,5,3'-triiodothyronine (T3) and free T3 concentrations were markedly increased, and thyroxine (T4), free T4, and thyroid-stimulating hormone concentrations were at or decreased from the respective reference ranges. Thyroid scintigraphy revealed suppressed uptake of sodium pertechnetate Tc 99m by the thyroid gland but no ectopic thyroid tissue, which was indicative of thyrotoxicosis induced by an exogenous source of T3. TREATMENT AND OUTCOME The dog was hospitalized for 24 hours, and its diet was changed, after which the clinical signs rapidly resolved and serum T3 and free T3 concentrations returned to within the respective reference ranges. This raised suspicion of an exogenous source of T3 in the dog's home environment. Analysis of the commercial beef-based canned food the dog was being fed revealed a high concentration of T3 (1.39 μg/g) and an iodine (82.44 μg/g) concentration that exceeded industry recommendations. No other source of T3 was identified in the dog's environment. CLINICAL RELEVANCE To our knowledge, this is the first report of clinical thyrotoxicosis in a dog induced by exogenous T3, although the source of exogenous T3 was not identified. This case highlights the importance of measuring serum T3 and thyroid-stimulating hormone concentrations in addition to T4 and free T4 concentrations when there is incongruity between clinical findings and thyroid function test results.

Optimization of Electrodeposition Parameters to Increase &lt;sup&gt;99m&lt;/sup&gt;Tc Radioactive Concentration

The use of low activity concentration 99m Tc would result in low-quality labeled compound for diagnostic purpose. The low activity concentration of labeled compound will alter biodistribution and lead to false imaging in diagnostic applications. Electrodeposition could be an alternative method for increasing the activity concentration of 99m Tc solution. The influence of electrodeposition parameters such as electrolytes, concentration of electrolyte, and voltage and time of deposition were examined to find the optimum condition for electrodeposition. Electrolytes to be evaluated were NaNO 2 , Na-oxalate, NaOH, and NaCl. Concentration factor is defined by ratio of final against initial concentration of 99m Tc. The quality assessment of 99m Tc after electrodeposition was conducted by labeling test of methylene diphosphonate (MDP) and 1,4,8,11-tetraaza cyclotetradecyl-1,4,8,11-tetramethylene phosphonic acid (CTMP). The results showed that the addition of NaNO 2 electrolyte gave the highest electrodeposition yield in comparison with Na-oxalate, NaOH, and NaCl, while the optimum concentration of electrolytes was 0.67 M. The optimum depostion voltage and duration were 7 V and 90 minutes, respectively. The electrodeposition yield was 96 % under optimized condition with a concentration factor of up to 7.96. In the quality assessment, MDP and CTMP were successfully labeled by concentrated 99m Tc to give 99m Tc-MDP and 99m Tc-CTMP labeled compounds with radiochemical purities of more than 95 %. Received: 2 November 2015 ; Revised: 14 July 2016 ; Accepted: 3 October 2016

Tumor Microenvironment-Triggered Aggregation of Antiphagocytosis 99m Tc-Labeled Fe3 O4 Nanoprobes for Enhanced Tumor Imaging In Vivo.

A tumor microenvironment responsive nanoprobe is developed for enhanced tumor imaging through in situ crosslinking of the Fe3 O4 nanoparticles modified with a responsive peptide sequence in which a tumor-specific Arg-Gly-Asp peptide for tumor targeting and a self-peptide as a "mark of self" are linked through a disulfide bond. Positioning the self-peptide at the outmost layer is aimed at delaying the clearance of the nanoparticles from the bloodstream. After the self-peptide is cleaved by glutathione within tumor microenvironment, the exposed thiol groups react with the remaining maleimide moieties from adjacent particles to crosslink the particles in situ. Both in vitro and in vivo experiments demonstrate that the aggregation substantially improves the magnetic resonance imaging (MRI) contrast enhancement performance of Fe3 O4 particles. By labeling the responsive particle probe with 99m Tc, single-photon emission computed tomography is enabled not only for verifying the enhanced imaging capacity of the crosslinked Fe3 O4 particles, but also for achieving sensitive dual modality imaging of tumors in vivo. The novelty of the current probe lies in the combination of tumor microenvironment-triggered aggregation of Fe3 O4 nanoparticles for boosting the T2 MRI effect, with antiphagocytosis surface coating, active targeting, and dual-modality imaging, which is never reported before.

Addressing Technetium-99m Shortage

Addressing Technetium-99m Shortage

Lymphoscintigraphic abnormalities in the contralateral lower limbs of patients with unilateral lymphedema.

The contralateral limbs of patients with unilateral lymphedema in the lower limbs (LLs) can exhibit abnormal lymphatic circulation, even in the absence of lymphedema. This idea is based on a number of reports that have studied isolated cases using lymphoscintigraphy. It is likely that these patients previously had some form of lymphopathy, and the lymphedema arose after the action of some external factor. However, there are no studies in the literature that adequately assess the asymptomatic contralateral limbs of these patients or address the prevalence and characteristics of the abnormal lymphatic circulation in these limbs. The aim of this study was to assess the prevalence of abnormal lymphatic circulation in the asymptomatic contralateral limbs of patients with unilateral lymphedema of the LL. Forty-three patients from the angiology and vascular surgery ward of the Hospital das Clínicas da Universidade Federal de Pernambuco with unilateral lymphedema of the LL underwent lymphoscintigraphy. All patients received a subcutaneous injection of 0.2 mL (74 MBq) of a solution of dextran 70 labeled with technetium Tc 99m in the first interdigital space of each foot. Images were obtained on two occasions: 10 minutes and 1 hour after the injection. The study design was transversal prospective. Among the 43 asymptomatic LLs, 30 (70%) showed abnormal lymphatic circulation. The lymphoscintigraphic abnormalities found were the following: reduced visualization of the lymphatic vessels and lymph nodes during 1 hour (83%), collateral circulation (30%), visualization of the inguinal and pelvic lymph nodes after at least 1 hour (30%), visualization of the popliteal lymph nodes (20%), dilation and lymphatic tortuosity (20%), and dermal backflow (10%). In this study,70% of the patients with unilateral lymphedema of the LL had some form of lymphopathy in the contralateral limb during the lymphoscintigraphic examination. These findings could favor the early treatment of these patients to prevent the disease from progressing to its most severe stage.

Feasibility and safety of minimally invasive radioguided parathyroidectomy using very low intraoperative dose of Tc-99m MIBI

BackgroundSurgical resection of the abnormal parathyroid glands is the only curative treatment for primary hyperparathyroidism (PHPT). Radioguided parathyroidectomy with technetium-99m (TC-99m) sestamibi has been successfully used in patients with PHPT.This study was designed to evaluate the results of a series of patients with PHPT who underwent minimally invasive radioguided parathyroidectomy (MIRP) using very low dose (1 mCi) of TC-99m sestamibi (MIBI) without application of intraoperative parathyroid hormone (PTH) assay or frozen section analysis. MethodsEighty-seven patients with PHPT were prospectively studied from November 2012 to January 2015. Following neck ultrasound (US) and MIBI scan concordant for single gland disease, patients underwent MIRP using a handheld gamma probe. The technique involved injecting of 1 mCi MIBI in the operative room before the beginning of the intervention. All patients were followed up for a minimum of 6 months postoperatively. ResultsMIRP was successfully performed in 86 out of 87 patients (98.85%). The Gamma probe was particularly useful in detection of ectopic parathyroid adenomas in upper mediastinum. Mean operative time was 23.95 ± 7.982 min and mean hospital stay was 1.44 ± 0.604 days. No major surgical complications were recorded. ConclusionsThe MIRP technique using very low dose (1 mCi) of Tc-99m MIBI without intraoperative PTH assay and frozen section analysis resulted in excellent cure rate for PHPT. This technique involves a radiation exposure to patients and surgical staffs 20 times lower than conventional MIRP using 20 mCi Tc-99m MIBI. Besides, patients with PHPT due to ectopic parathyroid adenoma may especially benefit from MIRP.

Residual Radioisotopes Generated from Neutron Irradiated Aluminum Capsules

Aluminum (Al) is often used to house a molybdenum oxide (MoO 3 ) target for neutron or proton-produced technetium-99m ( 99m Tc) radioisotope. During neutron or proton bombardment of an Al body, residual radioisotopes could be generated following nuclear reactions between the incoming particles and the Al body. In this research, residual radioisotopes produced following nuclear reactor based-neutron irradiation of Al body were experimentally measured using a portable gamma ray spectroscopy system; whereas TALYS 2015 calculated data were used to evaluate various nuclear reactions for the by-product identification. As a comparison, Al body used in a cyclotron-based 99m Tc production was also analyzed. Experimental data indicated that relatively long-lived radioisotopes such as 26 Al, 22 Na and 24 Na were identified in the Al body following nuclear reactor-based 99m Tc production, whereas the presence of 27 Mg radioisotope was, for the first time, experimentally detected in both the Al bodies for nuclear reactor-based and cyclotron-based 99m Tc production. A special safety attention should be paid to the radiation workers when producing 99m Tc using a nuclear reactor since it generates 26 Al (half life = 716,600 years).

A feasibility study of an integrated NIR/gamma/visible imaging system for endoscopic sentinel lymph node mapping.

The aim of this study is to integrate NIR, gamma, and visible imaging tools into a single endoscopic system to overcome the limitation of NIR using gamma imaging and to demonstrate the feasibility of endoscopic NIR/gamma/visible fusion imaging for sentinel lymph node (SLN) mapping with a small animal. The endoscopic NIR/gamma/visible imaging system consists of a tungsten pinhole collimator, a plastic focusing lens, a BGO crystal (11×11×2mm3 ), a fiber-optic taper (front=11×11mm2 , end=4×4mm2 ), a 122-cm long endoscopic fiber bundle, an NIR emission filter, a relay lens, and a CCD camera. A custom-made Derenzo-like phantom filled with a mixture of 99m Tc and indocyanine green (ICG) was used to assess the spatial resolution of the NIR and gamma images. The ICG fluorophore was excited using a light-emitting diode (LED) with an excitation filter (723-758nm), and the emitted fluorescence photons were detected with an emission filter (780-820nm) for a duration of 100ms. Subsequently, the 99m Tc distribution in the phantom was imaged for 3min. The feasibility of invivo SLN mapping with a mouse was investigated by injecting a mixture of 99m Tc-antimony sulfur colloid (12 MBq) and ICG (0.1 mL) into the right paw of the mouse (C57/B6) subcutaneously. After one hour, NIR, gamma, and visible images were acquired sequentially. Subsequently, the dissected SLN was imaged in the same way as the invivo SLN mapping. The NIR, gamma, and visible images of the Derenzo-like phantom can be obtained with the proposed endoscopic imaging system. The NIR/gamma/visible fusion image of the SLN showed a good correlation among the NIR, gamma, and visible images both for the invivo and exvivo imaging. We demonstrated the feasibility of the integrated NIR/gamma/visible imaging system using a single endoscopic fiber bundle. In future, we plan to investigate miniaturization of the endoscope head and simultaneous NIR/gamma/visible imaging with dichroic mirrors and three CCD cameras.

The detection of sentinel lymph nodes in laparoscopic surgery for uterine cervical cancer using 99m-technetium-tin colloid, indocyanine green, and blue dye.

ObjectiveOur objective was to determine the feasibility and detection rates and clarify the most effective combination of injected tracer types for sentinel lymph node (SLN) mapping in uterine cervical cancer in patients who have undergone laparoscopic surgery or neoadjuvant chemotherapy (NAC).MethodsA total of 119 patients with cervical cancer underwent SLN biopsy at radical hysterectomy using three types of tracers. The various factors related to side-specific detection rate, sensitivity, and false negative (FN) rate were analyzed.ResultsThe SLN detection rates using 99m-technetium (99mTc)-tin colloid, indigo carmine, and indocyanine green (ICG) were 85.8%, 20.2%, and 61.6%, respectively. The patients with ≥2-cm-diameter tumors and those who received NAC had lower detection rates than those with <2-cm-diameter tumors (75.7% vs. 91.5%, p<0.01) and those who did not receive NAC (67.9% vs. 86.3%, p<0.01), respectively. Laparoscopic procedures had a higher detection rate than laparotomy (100.0% vs. 77.1%, p<0.01). No factors significantly affected the sensitivity; however, the patients with ≥2-cm-diameter tumors (86.0% vs. 1.4%, p<0.01), NAC (19.4% vs. 2.2%, p<0.01), and those who underwent laparotomy (7.4% vs. 0%, p<0.01) had an unfavorable FN rate.ConclusionAmong the examined tracers, 99mTc had the highest detection of SLN mapping in patients with uterine cervical cancer. Patients with local advanced cervical cancer with/without NAC treatment might be unsuited for SLN mapping. SLN mapping is feasible and results in an excellent detection rate in patients with <2-cm-diameter cervical cancer. Laparoscopic surgery is the best procedure for SLN detection in patients with early-stage disease.

Experimental study of the rigidity and transparency to ionizing radiation of composite materials used in the enclosure under pressure of the Micromegas detector

Innovation in the field of nuclear imaging is necessarily followed by a radical change in the detection principle. The gas detector Micromegas (Mesh Micro Structure Gaseous) could be an interesting option, thanks to the stability and robustness of such a detector. Thus, it was necessary to study the implementation of the detector enclosure in composite materials. The focus of the present study was the robustness and gamma rays transparency of a set of composites. The studied composites were reinforced with vegetable fibers (alfa), and synthetic fibers. The mechanical properties of all composites specimen were evaluated by three-point bending test, whereas, gamma ray transparency was evaluated by the exposition of composites specimen to a mono-energetic gamma ray beam emitted by a Technetium 99-m source. Findings revealed that the biocomposite materials using alfa fiber and Polymethyl Methacrylate matrix are very promising as long as they present good robustness and high gamma ray transparency in diagnostic range.

Production of medical 99m Tc isotope via photonuclear reaction

99mTc with a 6 hour half-life is one of the most important medical isotopes used for the Single-Photon Emission Computed Tomography (SPECT) inspection in hospitals of US, Canada, Europe and Japan. 99mTc isotopes are extracted by the milking method from parent 99Mo isotopes with a 66 hour half-life. The supply of 99Mo isotopes now encounters a serious crisis. Hospitals may not suitably receive 99Mo medical isotopes in near future, due to difficulties in production by research nuclear reactors. Many countries are now looking for alternative ways to generate 99Mo isotopes other than those with research reactors. We discuss a sustained availability of 99mTc isotopes via the natMo(γ, n) photonuclear reaction, and discuss to solve technical problems for extracting pure 99mTc isotopes from other output materials of photonuclear reactions.

Management of non-visualization following dynamic sentinel lymph node biopsy for squamous cell carcinoma of the penis.

To review the management and clinical outcomes of uni- or bilateral non-visualization of inguinal lymph nodes during dynamic sentinel lymph node biopsy (DSNB) in patients diagnosed with penile cancer and clinically impalpable inguinal lymph nodes (cN0), and to develop an algorithm for the management of patients in which non-visualization occurs. This is a retrospective observational study over a period of 4 years, comprising 166 patients with penile squamous cell carcinoma undergoing DSNB and followed up for a minimum of 6 months. All cases diagnosed with uni- or bilateral non-visualization of sentinel nodes in this cohort were identified from a penile cancer database. The management of the inguinal lymph nodes after non-visualization and the oncological outcomes including local and regional recurrence rates were documented. Out of 166 consecutive patients undergoing DSNB, 20 patients (12%) had unilateral non-visualization after injection of intradermal 99m Tc. Of these 20 patients, seven underwent repeat DSNB at a later date, with six having successful visualization. One patient had persistent non-visualization and proceeded to a superficial modified inguinal lymphadenectomy (SML). None of these patients experienced recurrence at follow-up. A further seven patients underwent modified SML with on-table frozen-section analysis of the lymph node packet; none of these patients were found to have micrometastatic disease in the inguinal lymph nodes, although one patient developed metastatic inguinal node disease at a later date. Six patients elected to undergo clinical surveillance and have remained disease-free. Patients with impalpable inguinal lymph nodes undergoing DSNB with ≥G2 T1 disease should ideally have bilateral visualization of the sentinel lymph nodes, reflecting the drainage pattern from the primary tumour. In the present series, 12% of patients were found to have unilateral non-visualization after DSNB. Among patients offered a repeat DSNB at a later date, localizing the sentinel node was successful in 86% of cases. Patients with favourable histological characteristics can be placed on clinical surveillance. Those with high-risk disease can be offered a repeat DSNB procedure on the proviso that SML may be carried out if there is repeated non-visualization. Larger cohorts are required to validate this proposed algorithm.

99m Tc-anti-epidermal growth factor receptor nanobody for tumor imaging.

Nanobodies are important biomolecules for tumor targeting. In this study, we synthesized and labeled anti-epidermal growth factor receptor (EGFR) nanobody OA-cb6 with 99m Tc(CO)3+ and evaluated its characteristics for targeting the EGFR in the A431 human epidermal carcinoma cell line. Nanobody radiolabeling was achieved with high yield and radiochemical purity, and the radioconjugate was stable. Biodistribution results in nude mice exhibited a favorable tumor-to-muscle ratio at 4-hr postinjection, and tumor location was visualized at 4hr after injection of radiolabeled nanobody. Our result showed that the OA-cb6-99m Tc-tricarbonyl radiolabeled nanobody is a promising radiolabeled biomolecule for tumor imaging in cancers with high EGFR overexpression.

Accuracy of 99mTechnetium-labeled RBC Scintigraphy and MDCT With Gastrointestinal Bleed Protocol for Detection and Localization of Source of Acute Lower Gastrointestinal Bleeding

Acute lower gastrointestinal bleeding (LGIB) is a major cause of morbidity and mortality. Multidetector row computed tomography (CT) with gastrointestinal (GI) bleed protocol is a novel diagnostic technique for detecting and localizing LGIB. Being rapid and noninvasive, it may be useful as a first-line modality to investigate cases of acute LGIB. To assess and compare diagnostic accuracy of (99M)Technetium (Tc)-labeled red blood cell (RBC) scintigraphy and multidetector row CT with GI bleed protocol for detection and localization of source of acute LGIB. Requirement of informed consent was waived for this retrospective study. Seventy-six patients had undergone either RBC scintigraphy, CT with GI bleed protocol, or both, followed by conventional angiography for evaluation of acute persistent LGIB between January 2010 and February 2014 at our institution. Accuracy of both modalities was assessed using conventional angiography as reference standard and compared using the 2-tailed, Fisher exact test. A P-value of <0.05 was considered statistically significant. Fifty-one, 20, and 5 patients had undergone RBC scintigraphy only, CT with GI bleed protocol only, and both modalities, respectively. Fourteen of 25 patients in the CT group had angiographic evidence of active bleeding as compared with 32 of 56 patients in the scintigraphy group. CT with GI bleed protocol had higher accuracy (96%) than (99M)Tc-labeled RBC scintigraphy (55.4%, P<0.001). CT with GI bleed protocol was more accurate in detecting and localizing the source of acute LGIB as compared with (99M)Tc-labeled RBC scintigraphy.