Is correction for metallic artefacts mandatory in cardiac SPECT/CT imaging in the presence of pacemaker and implantable cardioverter defibrillator leads?

Introduction: Metallic artifacts due to pacemaker/ implantable cardioverter defibrillator (ICD) leads in CT images can produce artifactual uptake in cardiac SPECT/CT images. The aim of this study was to determine the influence of the metallic artifacts due to pacemaker and ICD leads on myocardial SPECT/CT imaging. Methods: The study included 9 patients who underwent myocardial perfusion imaging (MPI). A cardiac phantom with an inserted solid defect was used. The SPECT images were corrected for attenuation using both artifactual CT and CT corrected using metal artifact reduction (MAR). VOI-based analysis was performed in artifactual regions. Results: In phantom studies, mean-of-relative-difference in white-region, between artifact-free attenuation-map without/with MAR were changed from 9.2 and 2.1 to 3.7 and 1.2 for ICD and pacemaker lead, respectively. However, these values for typical patient were 9.7±7.0 and 3.8±2.4 for ICD and pacemaker leads respectively, in white-region. MAR effectively reduces the artifacts in white-regions while this reduction is not significant in black-regions. Conclusion: Following application of MAR, visual and quantification analyses revealed that while quality of CT images were significantly improved, the improvements in the SPECT/CT images were not as pronounced or significant. Therefore cardiac SPECT images corrected for attenuation using CT in the presence of metallic-leads can be interpreted without correction for metal artefacts. © 2018 Tehran University of Medical Sciences. All rights reserved

Effects of filtration on right ventricular function by the gated blood pool SPECT

Objective: Gated blood pool single photon emission computed tomography (GBPS) offers the possibility of obtaining additional functional information from blood pool studies, including evaluation of left and right ventricular function simultaneously. The calculation of ventricular volumes based on the identification of the endocardial surface would be influenced by the spatial resolution in the reconstructed images. This study was performed to evaluate the effect of different filters on the right ventricular function. Methods: The normal four-dimensional (4-D) NURBS-based cardiac-torso (NCAT) phantom with known right ventricular volume and ejection fraction was generated. The SIMIND Monte Carlo program was used to create projections. The studies were reconstructed by FBP and post-processing filtration such as Butterworth, Hanning, Shepp-Logan, Metz and Wiener in different statuses (cutoff and order). Using the Cedars�Sinai QBS (quantitative blood pool SPECT) package, the ventricular functional parameters were computed. The calculated values were analyzed and compared with the normal NCAT results. Results: The results implied that the calculated right ventricular end diastolic volume (RVEDV) by Butterworth filtration (cutoff frequency = 0.3) agreed more with the NCAT Phantom characteristics relative difference percentage (RDP) = 1.2 %, while the maximum accordance in the calculation of the RV ejection fraction (EF) (RDP = 3 %) was observed by Metz filter (FWHM 20 pixel). Also, the results of this study demonstrate that the Butterworth filter provided the most stable values (cutoff frequency = 0.4�0.5) in the estimation of RVEDV (RDP = 7.5 %). The Hanning and Shepp-Logan filters produced a much larger RDP, particularly in low frequency (41.1 and 21.5 %, respectively) compared to other filters. Conclusions: This study demonstrated that the operation of different filters has a severe effect in computing right ventricular volume. The resolution recovery and Butterworth filters tend to give more comparable ventricular volumes with the actual normal NCAT value. Further evaluation using a large clinical database is underway to evaluate the optimum protocol in a clinical setting. © 2015, The Japanese Society of Nuclear Medicine

Effects of Quinine on the Glycaemic Response to, and Gastric Emptying of, a Mixed-Nutrient Drink in Females and Males

Intraduodenal quinine, in the dose of 600 mg, stimulates glucagon-like peptide-1 (GLP-1), cholecystokinin and insulin; slows gastric emptying (GE); and lowers post-meal glucose in men. Oral sensitivity to bitter substances may be greater in women than men. We, accordingly, evaluated the dose-related effects of quinine on GE, and the glycaemic responses to, a mixed-nutrient drink in females, and compared the effects of the higher dose with those in males. A total of 13 female and 13 male healthy volunteers received quinine-hydrochloride (600 mg (‘QHCl-600’) or 300 mg (‘QHCl300’, females only) or control (‘C’), intraduodenally (10 mL bolus) 30 min before a drink (500 kcal, 74 g carbohydrates). Plasma glucose, insulin, C-peptide, GLP-1, glucose-dependent insulinotropic polypeptide (GIP) and cholecystokinin were measured at baseline, for 30 min after quinine alone, and then for 2 h post-drink. GE was measured by 13C-acetate breath-test. QHCl-600 alone stimulated insulin, C-peptide and GLP-1 secretion compared to C. Post-drink, QHCl-600 reduced plasma glucose, stimulated C-peptide and GLP-1, and increased the C-peptide/glucose ratio and oral disposition index, while cholecystokinin and GIP were less, in females and males. QHCl-600 also slowed GE compared to C in males and compared to QHCl-300 in females (p < 0.05). QHCl-300 reduced postmeal glucose concentrations and increased the C-peptide/glucose ratio, compared to C (p < 0.05). Magnitudes of glucose lowering and increase in C-peptide/glucose ratio by QHCl-600 were greater in females than males (p < 0.05). We conclude that quinine modulates glucoregulatory functions, associated with glucose lowering in healthy males and females. However, glucose lowering appears to be greater in females than males, without apparent differential effects on GI functions.Peyman Rezaie, Vida Bitarafan, Braden David Rose, Kylie Lange, Zinat Mohammadpour, Jens Frederik Rehfeld, Michael Horowitz, and Christine Feinle-Bisse

Predictive quantitative sonographic features on classification of hot and cold thyroid nodules

Purpose: This study investigated the potentiality of ultrasound imaging to classify hot and cold thyroid nodules on the basis of textural and morphological analysis. Methods: In this research, 42 hypo (hot) and 42 hyper-function (cold) thyroid nodules were evaluated through the proposed method of computer aided diagnosis (CAD) system. To discover the difference between hot and cold nodules, 49 sonographic features (9 morphological, 40 textural) were extracted. A support vector machine classifier was utilized for the classification of LNs based on their extracted features. Results: In the training set data, a combination of morphological and textural features represented the best performance with area under the receiver operating characteristic curve (AUC) of 0.992. Upon testing the data set, the proposed model could classify the hot and cold thyroid nodules with an AUC of 0.948. Conclusions: CAD method based on textural and morphological features is capable of distinguishing between hot from cold nodules via 2-Dimensional sonography. Therefore, it can be used as a supplementary technique in daily clinical practices to improve the radiologists� understanding of conventional ultrasound imaging for nodules characterization. © 2018 Elsevier B.V

Predictive quantitative sonographic features on classification of hot and cold thyroid nodules

Purpose: This study investigated the potentiality of ultrasound imaging to classify hot and cold thyroid nodules on the basis of textural and morphological analysis. Methods: In this research, 42 hypo (hot) and 42 hyper-function (cold) thyroid nodules were evaluated through the proposed method of computer aided diagnosis (CAD) system. To discover the difference between hot and cold nodules, 49 sonographic features (9 morphological, 40 textural) were extracted. A support vector machine classifier was utilized for the classification of LNs based on their extracted features. Results: In the training set data, a combination of morphological and textural features represented the best performance with area under the receiver operating characteristic curve (AUC) of 0.992. Upon testing the data set, the proposed model could classify the hot and cold thyroid nodules with an AUC of 0.948. Conclusions: CAD method based on textural and morphological features is capable of distinguishing between hot from cold nodules via 2-Dimensional sonography. Therefore, it can be used as a supplementary technique in daily clinical practices to improve the radiologists� understanding of conventional ultrasound imaging for nodules characterization. © 2018 Elsevier B.V

Radioimmunoscintigraphy of Breast Tumor Xenografts in Mouse Model by 99mTc Direct Radiolabeling of a Monoclonal Antibody PR81

Introduction: The radioimmunoscintigraphy (RIS) has found widespread clinical applications in  tumor  diagnosis.  Human  epithelial  mucin,  MUC1,  is  commonly  over  expressed  in  adenocarcinoma including 80% of breast cancers and represents a useful target for RIS. The PR81  is  a  new  murine  anti-MUC1  monoclonal  antibody  that  was  found  to  react  with  the  membrane  extracts of several human breast cancerous tissues and the cell surface of some MUC1 positive  cell lines. In this study, a direct method which is very simple, rapid and efficient for the labeling  of this MAb with  99m Tc, particularly suitable for the development of a ‘kit’, was developed. The  quality  control  of  new  radiopharmaceutical  and  immunoscintigraphy  studies  in  BALB/c  mice  bearing breast tumor xenografts were also performed.  Materials and Methods: The Ab reduction was performed with 2-mercaptoethanol (2-ME) at a  molar  ratio  of  2000:1  (2-ME:MAb)  and  reduced  Ab  was  labeled  with  99m Tc  via  methylene  diphosphonate (MDP) as a transchelator. The labeling efficiency was determined by ITLC. The  amount  of  radiocolloids  was  measured  by  cellulose  nitrate  electrophoresis.  The  stability  of  the  labeled product was checked in fresh human serum by gel filtration chromatography (FPLC) over  24 hrs. The integrity of the labeled MAb was checked by the means of SDS-PAGE. Cell-binding  assay  was  used  to  test  the  binding  ability  of  99m Tc-PR81  to  MCF7  cells.  Biodistribution  was  studied in normal BALB/c mice at 4 and 24 hrs post-injection. The tumor imaging was performed  in female BALB/c mice with breast tumor xenografts 24 hrs after the new complex injection.  Results:  The  labeling  efficiency  was  94.2%±2.3  and  radiocolloids  were  2.5%±1.7.  In  vitro  stability  was  70%±5.7  in  fresh  human  serum  over  24  hrs.  There  was  no  significant  Ab  fragmentation due to the labeling procedure. Both the labeled and unlabeled PR81 were able to  compete for binding to MCF7 cells. The biodistribution studies in normal BALB/c mice showed  that  there  was  no  important  accumulation  in  any  organ.  The  immunoscintigraphy  studies  demonstrated definite localization of the preparation at the site of tumors with high sensitivity.  Discussion and Conclusion: The results show that by using the Schwarz method of radiolabeling  MAb PR81, a labeling yield higher than 90% with high stability of the complex in human serum  can be obtained. These findings demonstrated that the new radiopharmaceutical can be considered  as a promising candidate for imaging of human breast cancer