Influence of attenuation correction in the MPI image reconstructed by the ���Evolution for Cardiac������

The acquisition of a Myocardial Perfusion image (MPI) is of great importance for the diagnosis of the coronary artery disease, since it allows to evaluate which areas of the heart aren���t being properly perfused, in rest and stress situations. This exam is greatly influenced by photon attenuation which creates image artifacts and affects quantification. The acquisition of a Computerized Tomography (CT) image makes it possible to get an atomic images which can be used to perform high-quality attenuation corrections of the radiopharmaceutical distribution, in the MPI image. Studies show that by using hybrid imaging to perform diagnosis of the coronary artery disease, there is an increase on the specificity when evaluating the perfusion of the right coronary artery (RCA). Using an iterative algorithm with a resolution recovery software for the reconstruction, which balances the image quality, the administered activity and the scanning time, we aim to evaluate the influence of attenuation correction on the MPI image and the outcome in perfusion quantification and imaging quality.

Performing PET/CT studies: do they create anxiety?

Introduction: Anxiety is a common problem in primary care and specialty medical settings. Treating an anxious patient takes more time and adds stress to staff. Unrecognised anxiety may lead to exam repetition, image artifacts and hinder the scan performance. Reducing patient anxiety at the onset is probably the most useful means of minimizing artifactual FDG uptake, both fat brown and skeletal muscle uptake, as well patient movement and claustrophobia. The aim of the study was to examine the effects of information giving on the anxiety levels of patients who are to undergo a PET/CT and whether the patient experience is enhanced with the creation of a guideline. Methodology: Two hundred and thirty two patients were given two questionnaires before and after the procedure to determine their prior knowledge, concerns, expectations and experiences about the study. Verbal information was given by one of the technologists after the completion of the first questionnaire. Results: Our results show that the main causes of anxiety in patients who are having a PET/CT is the fear of the procedure itself, and fear of the results. The patients who suffered from greater anxiety were those who were scanned during the initial stage of a disease. No significant differences were found between the anxiety levels pre procedural and post procedural. Findings with regard to satisfaction show us that the amount of information given before the procedure does not change the anxiety levels and therefore, does not influence patient satisfaction. Conclusions: The performance of a PET/CT scan is an important and statistically generator of anxiety. PET/CT patients are often poorly informed and present with a range of anxieties that may ultimately affect examination quality. The creation of a guideline may reduce the stress of not knowing what will happen, the anxiety created and may increase their satisfaction in the experience of having a PET/CT scan.

18F-FDG measurement in primary lung cancer: SUV normalization to different distribution volumes

Introduction: Standard Uptake Value (SUV) is a measurement of the uptake in a tumour normalized on the basis of a distribution volume and is used to quantify 18F-Fluorodeoxiglucose (FDG) uptake in tumors, such as primary lung tumor. Several sources of error can affect its accuracy. Normalization can be based on body weight, body surface area (BSA) and lean body mass (LBM). The aim of this study is to compare the influence of 3 normalization volumes in the calculation of SUV: body weight (SUVW), BSA (SUVBSA) and LBM (SUVLBM), with and without glucose correction, in patients with known primary lung tumor. The correlation between SUV and weight, height, blood glucose level, injected activity and time between injection and image acquisition is evaluated. Methods: Sample included 30 subjects (8 female and 22 male) with primary lung tumor, with clinical indication for 18F-FDG Positron Emission Tomography (PET). Images were acquired on a Siemens Biography according to the department���s protocol. Maximum pixel SUVW was obtained for abnormal uptake focus through semiautomatic VOI with Quantification 3D isocontour (threshold 2.5). The concentration of radioactivity (kBq/ml) was obtained from SUVW, SUVBSA, SUVLBM and the glucose corrected SUV were mathematically obtained. Results: Statistically significant differences between SUVW, SUVBSA and SUVLBM and between SUVWgluc, SUVBSAgluc and SUVLBMgluc were observed (p=0.000<0.05). The blood glucose level showed significant positive correlations with SUVW (r=0.371; p=0.043) and SUVLBM (r=0.389; p=0.034). SUVBSA showed independence of variations with the blood glucose level. Conclusion: The measurement of a radiopharmaceutical tumor uptake normalized on the basis of different distribution volumes is still variable. Further investigation on this subject is recommended.

Influ��ncia da experi��ncia profissional e da fun����o visual do operador no processamento semiautom��tico da cintigrafia de perfus��o do mioc��rdio: variabilidade intra e interoperador na determina����o dos par��metros quantitativos

Introdu����o ��� A cintigrafia de perfus��o do mioc��rdio (CPM) desempenha um importante papel no diagn��stico, avalia����o e seguimento de pacientes com doen��a arterial coron��ria, sendo o seu processamento realizado maioritariamente de forma semiautom��tica. Uma vez que o desempenho dos t��cnicos de medicina nuclear (TMN) pode ser afetado por fatores individuais e ambientais, diferentes profissionais que processem os mesmos dados poder��o obter diferentes estimativas dos par��metros quantitativos (PQ). Objetivo ��� Avaliar a influ��ncia da experi��ncia profissional e da fun����o visual no processamento semiautom��tico da CPM. Analisar a variabilidade intra e interoperador na determina����o dos PQ funcionais e de perfus��o. Metodologia ��� Selecionou-se uma amostra de 20 TMN divididos em dois grupos, de acordo com a sua experi��ncia no software Quantitative Gated SPECTTM: Grupo A (GA) ��� TMN ���600h de experi��ncia e Grupo B (GB) ��� TMN sem experi��ncia. Submeteram-se os TMN a uma avalia����o ort��ptica e ao processamento de 21 CPM, cinco vezes, n��o consecutivas. Considerou-se uma vis��o alterada quando pelo menos um par��metro da fun����o visual se encontrava anormal. Para avaliar a repetibilidade e a reprodutibilidade recorreu-se �� determina����o dos coeficientes de varia����o, %. Na compara����o dos PQ entre operadores, e para a an��lise do desempenho entre o GA e GB, aplicou-se o Teste de Friedman e de Wilcoxon, respetivamente, considerando o processamento das mesmas CPM. Para a compara����o de TMN com vis��o normal e alterada na determina����o dos PQ utilizou-se o Teste Mann-Whitney e para avaliar a influ��ncia da vis��o para cada PQ recorreu-se ao coeficiente de associa����o ETA. Diferen��as estatisticamente significativas foram assumidas ao n��vel de signific��ncia de 5%. Resultados e Discuss��o ��� Verificou-se uma reduzida variabilidade intra (<6,59%) e inter (<5,07%) operador. O GB demonstrou ser o mais discrepante na determina����o dos PQ, sendo a parede septal (PS) o ��nico PQ que apresentou diferen��as estatisticamente significativas (zw=-2,051, p=0,040), em detrimento do GA. No que se refere �� influ��ncia da fun����o visual foram detetadas diferen��as estatisticamente significativas apenas na fra����o de eje����o do ventr��culo esquerdo (FEVE) (U=11,5, p=0,012) entre TMN com vis��o normal e alterada, contribuindo a vis��o em 33,99% para a sua varia����o. Denotaram-se mais diferen��as nos PQ obtidos em TMN que apresentam uma maior incid��ncia de sintomatologia ocular e uma vis��o binocular diminu��da. A FEVE demonstrou ser o par��metro mais consistente entre operadores (1,86%). Conclus��o ��� A CPM apresenta-se como uma t��cnica repet��vel e reprodut��vel, independente do operador. Verificou-se influ��ncia da experi��ncia profissional e da fun����o visual no processamento semiautom��tico da CPM, nos PQ PS e FEVE, respetivamente.

Tomografia por emiss��o de positr��es: constru����o de uma guideline de atendimento

Mestrado em Medicina Nuclear - ��rea de especializa����o: Tomografia por emiss��o de positr��es

Oncological patient anxiety in imaging studies: the PET/CT example

The purpose of this study was to investigate the subjective perception of anxiety pre- and post-procedure, and explore the relationship between demographic, clinical variables and cancer patients' anxiety during a positron emission tomography/computed tomography (PET/CT) scan. Two hundred and thirty-two oncological out patients, with clinical indication for performing an (18)F-2-fluoro-2-deoxy-D-glucose ((18)F-FDG) PET/CT scan and attending a nuclear medicine (NM) department, participated in the study. Patients' anxiety and subjective experience of PET/CT were examined using two self-report questionnaires. The pre-procedure questionnaire focused on demographic information, level of knowledge regarding the scan and subjective perception of anxiety before the procedure. The post-procedure questionnaire included the subjective perception anxiety after the procedure, information adequacy and satisfaction with the NM department. The self-reported data indicate that patients were anxious during PET/CT. Furthermore, our data revealed a significant difference between the anxiety pre-procedure and post-procedure (z��=��-3909, p��<��0.05), in which the anxiety pre-procedure has significantly higher values. No significant correlation was found between anxiety and age of the patients, education levels, adequacy of information or satisfaction with the NM Department. Perception of anxiety post-procedure differs between gender (U��=��5641, p��=��0.033). In conclusion, PET/CT generated anxiety levels in oncological patients, especially before the procedure. Although patients seemed to be satisfied with information delivered by staff and with the NM Department, attention has to be focused on effective interventions strategies that help patients to reduce anxiety.

PET e PET/CT com FDG: compara����o de duas bases de dados de refer��ncia do normal com SUV

Mestrado em Medicina Nuclear - ��rea de especializa����o: Tomografia por Emiss��o de Positr��es

Fracionamento de kits de HMDP para marca����o com 99mTc: influ��ncia da temperatura e da idade das fra����es

Mestrado em Medicina Nuclear - ��rea de especializa����o: Radiofarm��cia

Lesion detection performance: comparative analysis of low-dose CT data of the chest on two hybrid imaging systems

Incidental findings on low-dose CT images obtained during hybrid imaging are an increasing phenomenon as CT technology advances. Understanding the diagnostic value of incidental findings along with the technical limitations is important when reporting image results and recommending follow-up, which may result in an additional radiation dose from further diagnostic imaging and an increase in patient anxiety. This study assessed lesions incidentally detected on CT images acquired for attenuation correction on two SPECT/CT systems. Methods: An anthropomorphic chest phantom containing simulated lesions of varying size and density was imaged on an Infinia Hawkeye 4 and a Symbia T6 using the low-dose CT settings applied for attenuation correction acquisitions in myocardial perfusion imaging. Twenty-two interpreters assessed 46 images from each SPECT/CT system (15 normal images and 31 abnormal images; 41 lesions). Data were evaluated using a jackknife alternative free-response receiver-operating-characteristic analysis (JAFROC). Results: JAFROC analysis showed a significant difference (P < 0.0001) in lesion detection, with the figures of merit being 0.599 (95% confidence interval, 0.568, 0.631) and 0.810 (95% confidence interval, 0.781, 0.839) for the Infinia Hawkeye 4 and Symbia T6, respectively. Lesion detection on the Infinia Hawkeye 4 was generally limited to larger, higher-density lesions. The Symbia T6 allowed improved detection rates for midsized lesions and some lower-density lesions. However, interpreters struggled to detect small (5 mm) lesions on both image sets, irrespective of density. Conclusion: Lesion detection is more reliable on low-dose CT images from the Symbia T6 than from the Infinia Hawkeye 4. This phantom-based study gives an indication of potential lesion detection in the clinical context as shown by two commonly used SPECT/CT systems, which may assist the clinician in determining whether further diagnostic imaging is justified.

Influ��ncia da escala de cores na avalia����o qualitativa das imagens de cintigrafia de perfus��o do mioc��rdio

Introdu����o ��� A cintigrafia de perfus��o do mioc��rdio (CPM) �� utilizada no diagn��stico e seguimento de pacientes com doen��a arterial coron��ria, sendo a sua avalia����o frequentemente realizada atrav��s da an��lise visual dos cortes tomogr��ficos. A escala de cores selecionada �� essencial na interpreta����o cl��nica das imagens de perfus��o do mioc��rdio. Objetivo ��� Avaliar a influ��ncia de diferentes escalas de cores na avalia����o qualitativa das imagens de CPM e estudar quais as mais adequadas para an��lise visual. M��todos ��� Trinta e cinco estudos de CPM foram avaliados visualmente por 16 estudantes da licenciatura em medicina nuclear nas escalas de cores Cool, Gray, Gray Invert, Thermal e Warm. Para a escala de cores Cool, a an��lise das imagens de CPM foi realizada atrav��s de um sistema de classifica����o semiquantitativo por scores. As restantes escalas de cores foram avaliadas por compara����o com a an��lise das imagens efetuada com escala de cores Cool. Resultados/Discuss��o ��� Para a escala de cores Cool, a variabilidade interoperador revelou a exist��ncia de diferen��as estatisticamente significativas entre todos os participantes (p<0,05), o que se pode atribuir �� subjetividade da avalia����o visual. Os resultados relativos ��s escalas de cores Gray e Gray Invert foram os mais pr��ximos da perfus��o do mioc��rdio observada com a escala Cool, considerando-se escalas de cores alternativas na an��lise visual dos estudos de CPM. Para as escalas de cores Thermal e Warm os resultados foram mais divergentes, n��o se considerando adequadas para a avalia����o visual dos estudos de CPM. Conclus��o ��� A escala de cores influencia a avalia����o qualitativa da perfus��o na CPM.

Digital radiology and Picture Archiving and Communication System (PACS)

Plain radiography still accounts for the vast majority of imaging studies that are performed at multiple clinical instances. Digital detectors are now prominent in many imaging facilities and they are the main driving force towards filmless environments. There has been a working paradigm shift due to the functional separation of acquisition, visualization, and storage with deep impact in the imaging workflows. Moreover with direct digital detectors images are made available almost immediately. Digital radiology is now completely integrated in Picture Archiving and Communication System (PACS) environments governed by the Digital Imaging and Communications in Medicine (DICOM) standard. In this chapter a brief overview of PACS architectures and components is presented together with a necessarily brief account of the DICOM standard. Special focus is given to the DICOM digital radiology objects and how specific attributes may now be used to improve and increase the metadata repository associated with image data. Regular scrutiny of the metadata repository may serve as a valuable tool for improved, cost-effective, and multidimensional quality control procedures.