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- MUGA processing: intra and interoperator variability impact using manual and automated methodsPublication . Belo, Rita; Alves, Cláudia; Carvalhal, Cristiana; Figueiredo, Sérgio; Carolino, Elisabete; Vieira, Lina OliveiraIntroduction – Multigated acquisition (MUGA) scan is mainly used for the assessment of left ventricular ejection fraction (LVEF) in patients who undergo cardiotoxic chemotherapy drugs. When applying automatic (A) or manual (M) processing methods, some biases in the quantitative metrics can be obtained. The aim of this study is to evaluate the influence of A and M methods, specifically, the inter and intraoperative variability in accordance with the professional experience. Methods – A retrospective study was performed with 14 MUGA exams available in ESTeSL’s Xeleris™ Functional Imaging Workstation v. 1.0628 database. Three operators (OP) with no professional experience and two with more than 10 years of experience, processed every study five times for each method, using the EF Analysis™ and the Peak Filling Rate™. To perform the multiple comparisons, the Repeated Measures ANOVA, Friedman, t-test and Wilcoxon tests were used, considering α=0.05. Results – Four of the OP presented statistically significant differences between methods in one or more parameters; similar values between experienced OP and between the non-experienced were observed when the A method was applied, and higher discrepancies were present for all parameters obtained by the M mode; higher LVEF, peak filling rate, and peak empying rate values were observed for the M method. Conclusion – Variability was found when comparing M and A processing methods, as well as interoperator variability associated with their level of experience. Despite that, there was a trend of less variability between the two experienced OP and in the A method.
- Quantitative estimation of the renal tubular function with 99mTc- MAG3: comparative software approach using two methods in a pediatric populationPublication . Raminhas Carapinha, Maria João; Silva, R.; Silva, F.; Figueiredo, Sérgio; Vieira, Lina OliveiraIntroduction - The ability to quantify function by Effective Renal Plasma Flow (ERPF) using camera-based Technetium-99m mercaptoacetyltriglycine (99mTc-MAG3) clearance methods is an accurate and time-saving technique as compared with the standard laboratory tests. Often providing information not possible with the conventional radiological modalities, this quantitative assessment can be determined by a linear formula - Modified Gates Method (MGat) - or a quadratic approach - Modified Schlegel Method (MSch). The aim of this work was to evaluate the effect of the MGat and MSch methods on the absolute value of ERPF in 99mTc-MAG3 dynamic renography.
- Influence of adipose tissue in myocardial counts using attenuation correction in SPECT/CT imaging: study in phantomPublication . Galvão, Tiago; Roberto, João; Figueiredo, Sérgio; Carolino, Elisabete; Marques, Andreia; Pintão, Sophia; Vieira, Lina OliveiraMyocardial perfusion imaging (MIP) with single photon emission computed tomography is one of the most accurate procedures for the detection of coronary artery disease. Tissue attenuation artifacts are a significant limitation of MIP, especially in obese patients. CT-based attenuation correction (AC) is widely used to undermine these artifacts. The objective of this study was to evaluate the influence of an adipose tissue equivalent in the total myocardial counts after AC in SPECT/CT imaging. To accomplish this a Heart Thorax Phantom was filled with 99m TcO4-(simulating the uptake of 99m Tc-tetrofosmin in the cardiac walls and liver) for SPECT/CT imaging using an additional layer of 100% lipid fat and a torso phantom. The acquired data were reconstructed with Filtered Back Projection (FBP), iterative algorithms without AC (IRNC) and iterative algorithms with AC (IRAC) for posterior evaluation of total cardiac wall count (Anterior, Inferior, Lateral and Septal). There was a significant reduction in total mean counts of the lateral and septal walls, with the addition of a layer of fat and the torso phantom, when FBP and IRNC reconstructions were applied (p ≤ 0,05) which may have been caused by tissue attenuation artifacts. The addition of a layer of fat and of the torso phantom, directly increased the total mean counts of the septal, lateral and inferior walls, when IRAC reconstruction was used (p ≤ 0,05) suggesting a benefit in the use of AC in larger body habitus. In conclusion, the adipose tissue equivalent directly influenced the total myocardium counts when AC methods were applied, and further research is advised.