Image-based versus atlas-based patient-specific S-value assessment for Samarium-153 EDTMP cancer palliative care: A short study

Introduction: Use of SPECT/CT data is the most accurate method for patient-specific internal dosimetry when isotopes emit single gamma rays. The manual or semi-automatic segmentation of organs is a major obstacle that slows down and limits the patient-specific dosimetry. Using digital phantoms that mimic patient�s anatomy can bypass the segmentation step and facilitate the dosimetry process. In this study, the results of a patient-specific dosimetry based on CT data and XCAT phantom, a flexible phantom with predefined organs, are compared. Methods: The dosimetry results (S-value and SAF) were calculated for a patient with breast cancer who received Samarium-153 ethylenediamine-N,N,N�,N�-tetrakis(methylenephosphonic acid (153Sm-EDTMP). Biodistribution of activity was obtained from the SPECT scan. The anatomical data and attenuation map were extracted from CT as well as the XCAT phantom with different BMIs. GATE Monte-Carlo simulator was used to calculate the dose to different organs based on the activity distribution and segmented anatomy. Results: The whole body dosimetry results are the same for both calculations based on the CT and XCAT with different BMIs; however for target organs, the differences between SAFs and S-values are high. In the spine, the clinically important target organ for Samarium therapy, the dosimetry results obtained from phantoms with unmatched BMIs between XCAT phantom and CT are substantially different. Conclusion: We showed that atlas-based dosimetry using XCAT phantom even with matched BMI may lead to considerable errors as compared to calculations based on patient�s own CT. For accurate dosimetry results, calculations should be done using CT data. © 2018 Iranian Journal of Nuclear Medicine. All Rights Reserved

99mTc-anionic linear globular dendrimer-G2-phenylalanine conjugate: Novel brain tumor SPECT imaging

The purpose of this study was the investigation of the targeting potential of99mTc-Labeled dendrimer-phenylalanine conjugate for brain tumor SPECT imaging. L-Type amino acid transporters (LAT1) are highly expressed in the blood-brain barrier as well as in brain cancer cells; thus, targeting LAT1 using phenylalanine could improve the sensitivity and specificity of radiosynthesis nanocarrier. In this study, the dendrimer G2�phenylalanine conjugate was synthesized and characterized by Fourier transform infrared spectroscopy, atomic force microscopy, particle size, and zeta potential. MTT assay was done for cell viability measurement in different concentrations of nanoparticles (0.125, 0.25, 0.5 mg/ml) on C6 glioma cell lines; the uptake study was evaluated using fluorescence-activated cell sorter (FACS) instrument; finally, SPECT scintigraphy in glioma tumor-bearing Wistar rats was done. The dendrimer-phenylalanine conjugate particle size was found in the range of 74.14±2.2 to 109±3.1 nm, with a slightly negative surface charge. Also, phenylalanine present on the dendrimer's surface� phenylalanine conjugate enhanced the dendrimer's cellular uptake�phenylalanine conjugate on the C6 glioma cell line. Results of SPECT imaging and fluorescence studies revealed that dendrimer� phenylalanine conjugate accumulated into the brain tumor cells, and it can be suggested as a promising brain-targeting probe with no toxicity in brain tumor imaging. © 2020 by the authors

Impact of metoclopramide on image quality in myocardial perfusion imaging

Background: The effectiveness of metoclopramide in reducing gastrointestinal-induced artifacts in myocardial perfusion imaging (MPI) is a subject of debate. We examined the significance of this pharmacological intervention in the quality of images obtained from MPI studies. Patients and Methods: A total of 211 suspected or known cases with coronary artery disease routinely referred to our nuclear medicine department for MPI were randomly assigned to group A and group B. Group A (N=125) comprised patients who received 10 mg of metoclopramide orally after the injection of the radiotracer technetium-99m-labeled methoxyisobutyl isonitril (Tc-MIBI) 1 h before image acquisition, and group B (N=86) comprised patients who did not receive any pharmacological intervention and were considered the control group. All the scans in each group were assessed in the rest phase of a routine 2-day protocol. The single-photon emission computerized tomography (SPECT) images were visually evaluated in terms of extracardiac activities and their effects on image quality by three nuclear medicine physicians, who were blinded to the details of the protocol. Results: Of the 125 patients who had received metoclopramide, 16 (13%) had nonacceptable, 72 (57.6%) had acceptable (interpretable), and 37 (29.6%) had good image quality. The image quality in group B was nonacceptable in 10 (11.23%), acceptable in 48 (50.23%), and good in 28 (33.56%) patients. The overall interobserver agreement was good (κ: 0.6-0.9, P<0.05) among the three readers. Conclusion: There was no statistically significant difference in terms of MPI-SPECT image quality between patients who received metoclopramide and those in the control group. Metoclopramide, therefore, did not exert a remarkable effect on the quality of our MPI scans. © 2012 Wolters Kluwer Health | Lippincott Williams & Wilkins

Comparing the cardiac MRI and thallium-201 SPECT findings in assessing myocardial viability in patients with ST elevation myocardial infarction

Background and purpose: Viable tissue detection after STEMI can lead to successful revascularization for reversing myocardial dysfunction. The purpose of this study was to compare the Thallium-201 SPECT and MRI findings in viability assessment. Materials and methods: A cross-sectional study was performed on 17 patients with STEMI. In addition to Thallium SPECT, contrast enhanced MRI imaging was done. Viability was determined as more than 50 percent thallium uptake after 4 hours in SPECT and lower than 50 percent gadolinium enhancement after 10 minutes in each segments in CMRI. Results: Two hundred eighty nine segments were studied using both methods. TL SPECT showed 15.6 of the segments as non-viable tissue while MRI showed 35 non-viable tissue. There was a substantial agreement between these methods in apical septal and apical segments (k: 0.653, k: 0.757, respectively). Conclusion: The percentage of non-viable myocardium in MRI was found to be higher than that of Thallium SPECT and also considerable agreement was seen between MRI and Thallium SPECT in determination of myocard viability in apical septal and apex segments. © 2016, Mazandaran University of Medical Sciences. All rights reserved

First measurement of the polarization observable E and helicity-dependent cross sections in single π0 photoproduction from quasi-free nucleons

The double-polarization observable E and the helicity-dependent cross sections σ1/2 and σ3/2 have been measured for the first time for single π0 photoproduction from protons and neutrons bound in the deuteron at the electron accelerator facility MAMI in Mainz, Germany. The experiment used a circularly polarized photon beam and a longitudinally polarized deuterated butanol target. The reaction products, recoil nucleons and decay photons from the π0 meson were detected with the Crystal Ball and TAPS electromagnetic calorimeters. Effects from nuclear Fermi motion were removed by a kinematic reconstruction of the π0N final state. A comparison to data measured with a free proton target showed that the absolute scale of the cross sections is significantly modified by nuclear final-state interaction (FSI) effects. However, there is no significant effect on the asymmetry E since the σ1/2 and σ3/2 components appear to be influenced in a similar way. Thus, the best approximation of the two helicity-dependent cross sections for the free neutron is obtained by combining the asymmetry E measured with quasi-free neutrons and the unpolarized cross section corrected for FSI effects under the assumption that the FSI effects are similar for neutrons and protons

Synthesis and characterization of Bombesin-superparamagnetic iron oxide nanoparticles as a targeted contrast agent for imaging of breast cancer using MRI

The targeted delivery of superparamagnetic iron oxide nanoparticles (SPIONs) as a contrast agent may facilitate their accumulation in cancer cells and enhance the sensitivity of MR imaging. In this study, SPIONs coated with dextran (DSPIONs) were conjugated with bombesin (BBN) to produce a targeting contrast agent for detection of breast cancer using MRI. X-ray diffraction, transmission electron microscopy, and vibrating sample magnetometer analyses indicated the formation of dextran-coated superparamagnetic iron oxide nanoparticles with an average size of 6.0�0.5 nm. Fourier transform infrared spectroscopy confirmed the conjugation of the BBN with the DSPIONs. A stability study proved the high optical stability of DSPION-BBN in human blood serum. DSPION-BBN biocompatibility was confirmed by cytotoxicity evaluation. A binding study showed the targeting ability of DSPION-BBN to bind to T47D breast cancer cells overexpressing gastrin-releasing peptide (GRP) receptors. T2-weighted and T2�-weighted color map MR images were acquired. The MRI study indicated that the DSPION-BBN possessed good diagnostic ability as a GRP-specific contrast agent, with appropriate signal reduction in T2�-weighted color map MR images in mice with breast tumors. � 2015 IOP Publishing Ltd

Evaluation of sternal wound infection after median sternotomy using 99mTc-labeled Ubiquicidin 29-41

Aims- Previous studies have demonstrated that 99mTc-labeled Ubiquicidin 29-41 (99mTc-UBI) can be used for the detection of bacterial infections as an accurate method.1 This study was conducted to evaluate the clinical use of 99mTc-UBI for the evaluation of sternal wound infection (SWI) after cardiac surgery. Materials and Methods - Twenty-one patients with suspected SWI after median sternotomy were included. Qualitative and quantitative voxel-based analyses of 99mTc-UBI images were performed by two experienced nuclear physicians and the images were reported as negative, positive for superficial, or positive for deep SWI on the basis of the uptake patterns. SWI was defined according to the Centres for Disease Control and Classifications' guideline. Results- Among the cases, only one subject with a final diagnosis of non-infectious inflammation was reported as superficial SWI in 99mTc-UBI scintigraphy. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for distinguishing SWI from sterile inflammation were equal to 100, 83.3, 93.8, and 100. After implicating a threshold of 3.08 for the target-to-background ratio, the specificity and PPV reached 100. The sensitivity, specificity, positive, and negative predictive values for the detection of superficial and deep SWI were 100, 92.9, 87.5, and 100 and 100, 100, 100, and 100, respectively. There was also a high interobserver agreement with all the kappa values exceeding 0.8. Conclusions- The results of the present study suggest that 99mTc-UBI could be of great use as an accurate method for the evaluation of suspected postoperative SWI and could help in the selection of appropriate treatment strategies for these patients