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

A reconstru����o tomogr��fica em SPECT com utiliza����o dos novos m��todos iterativos ���WBR���: compara����o com m��todos anal��ticos

Os m��todos utilizados pela Medicina moderna no ��mbito da Imagem Molecular e na sua capacidade de diagnosticar a partir da ���Fun����o do Org��o��� em vez da ���Morfologia do Org��o���, vieram trazer �� componente fundamental desta modalidade da Imagiologia M��dica ��� A Medicina Nuclear ��� uma import��ncia acrescida, que se tem traduzido num aumento significativo no recurso �� sua utiliza����o nas diferentes formas das suas aplica����es cl��nicas. Para al��m dos aspectos meramente cl��nicos, que s�� por si seriam suficientes para ocupar v��rias disserta����es como a presente; a pr��pria natureza desta t��cnica de imagem, com a sua inerente baixa resolu����o e tempos longos de aquisi����o, vieram trazer preocupa����es acrescidas quanto ��s quest��es relacionadas com a produtividade (n�� de estudos a realizar por unidade de tempo); com a qualidade (aumento da resolu����o da imagem obtida) e, com os n��veis de actividade radioactiva injectada nos pacientes (dose de radia����o efectiva sobre as popula����es). Conhecidas que s��o ent��o as limita����es tecnol��gicas associadas ao desenho dos equipamentos destinados �� aquisi����o de dados em Medicina Nuclear, que apesar dos avan��os introduzidos, mant��m mais ou menos inalter��veis os conceitos base de funcionamento de uma C��mara Gama, imaginou-se a altera����o significativa dos par��metros de aquisi����o (tempo, resolu����o, actividade), actuando n��o ao n��vel das condi����es t��cnico-mec��nicas dessa aquisi����o, mas essencialmente ao n��vel do p��s-processamento dos dados adquiridos segundo os m��todos tradicionais e que ainda constituem o estado da arte desta modalidade. Este trabalho tem ent��o como objectivo explicar por um lado, com algum pormenor, as bases tecnol��gicas que desde sempre t��m suportado o funcionamento dos sistemas destinados �� realiza����o de exames de Medicina Nuclear, mas sobretudo, apresentar as diferen��as com os inovadores m��todos, que aplicando essencialmente conhecimento (software), permitiram responder ��s quest��es acima levantadas.

Sensitivity correction of images obtained with the prototype Clear-PEM in pre-clinical environment

Dissertation presented at Faculdade de Ci��ncias e Tecnologia Universidade Nova de Lisboa to obtain a Master Degree in Biomedical Engineering

Projeto para a aquisi����o de um equipamento PET-CT: an��lise da viabilidade financeira

Projeto de mestrado em Gest��o de Unidades de Sa��de

Applicability of the Appropriate use Criteria for Myocardial Perfusion Scintigraphy

Background: Appropriateness Criteria for nuclear imaging exams were created by American College of Cardiology (ACC) e American Society of Nuclear Cardiology (ASNC) to allow the rational use of tests. Little is known whether these criteria have been followed in clinical practice. Objective: To evaluate whether the medical applications of myocardial perfusion scintigraphy (MPS) in a private nuclear medicine service of a tertiary cardiology hospital were suitable to the criteria of indications proposed by the American medical societies in 2005 and 2009 and compare the level of indication of both. Methods: We included records of 383 patients that underwent MPS, November 2008 up to February 2009. Demographic characteristics, patient's origin, coronary risk factors, time of medical graduation and appropriateness criteria of medical applications were studied. The criteria were evaluated by two independent physicians and, in doubtful cases, defined by a medical expert in MPS. Results: Mean age was 65 &#177; 12 years. Of the 367 records reviewed, 236 (64.3%) studies were performed in men and 75 (20.4%) were internee. To ACC 2005, 255 (69.5%) were considered appropriate indication and 13 (3.5%) inappropriate. With ACC 2009, 249 (67.8%) were considered appropriate indications and 13 (5.2%) inappropriate. Conclusions: We observed a high rate of adequacy of medical indications for MPS. Compared to the 2005 version, 2009 did not change the results.

Conjunctival MALT lymphoma: utility of FDG PET/CT for diagnosis, staging, and evaluation of treatment response.

A 67-year-old woman was referred for staging of a mucosa-associated lymphoid tumor lymphoma involving the left conjunctiva. CT scan had shown paravertebral and pelvic masses, and a breast nodule. FDG PET/CT demonstrated moderately increased uptake in the left ocular conjunctiva and confirmed the paravertebral and pelvic masses and the breast nodule. Moreover, abnormal FDG uptake was shown in 2 breast nodules, the flank, the gluteus maximus, and the gastric cardia. The patient received 6 cycles of rituximab-bendamustine chemotherapy with a complete clinical and metabolic response at the 6-month follow-up PET/CT and remained relapse-free without visual acuity problem after a 36-month follow-up.

Brain Glucose Transport and Phosphorylation Under Acute Insulin-Induced Hypoglycemia in Mice: An 18F-FDG PET Study.

We addressed the questions of how cerebral glucose transport and phosphorylation change under acute hypoglycemia and what the underlying mechanisms of adaptation are. METHODS: Quantitative (18)F-FDG PET combined with the acquisition of real-time arterial input function was performed on mice. Hypoglycemia was induced and maintained by insulin infusion. PET data were analyzed with the 2-tissue-compartment model for (18)F-FDG, and the results were evaluated with Michaelis-Menten saturation kinetics. RESULTS: Glucose clearance from plasma to brain (K1,glc) and the phosphorylation rate constant increased with decreasing plasma glucose (Gp), in particular at a Gp of less than 2.5 mmol/L. Estimated cerebral glucose extraction ratios taking into account an increased cerebral blood flow (CBF) at a Gp of less than 2 mmol/L were between 0.14 and 0.79. CBF-normalized K1,glc values were in agreement with saturation kinetics. Phosphorylation rate constants indicated intracellular glucose depletion at a Gp of less than 2-3 mmol/L. When brain regions were compared, glucose transport under hypoglycemia was lowest in the hypothalamus. CONCLUSION: Alterations in glucose transport and phosphorylation, as well as intracellular glucose depletion, under acute hypoglycemia can be modeled by saturation kinetics taking into account an increase in CBF. Distinct transport kinetics in the hypothalamus may be involved in its glucose-sensing function.

99mTc-sestamibi imaging and bone marrow karyotyping in the assessment of multiple myeloma and MGUS

AIM: The first pathogenetic step in multiple myeloma is the emergence of a limited number of clonal plasma cells, clinically known as monoclonal gammopathy of undetermined significance (MGUS). Patients with MGUS do not have symptoms or end-organ damage but they do have a 1% annual risk of progression to multiple myeloma or related malignant disorders. With progression of MGUS to multiple myeloma, complex genetic events occur in the neoplastic plasma cell. Karyotyping and fluorescence in-situ hybridization (FISH) were shown to be of prognostic value in patients with multiple myeloma. Tc-sestamibi imaging reflects myeloma disease activity in bone marrow with very high sensitivity and specificity predicting disease evolution. This study was undertaken to evaluate the role of Tc-sestamibi imaging and cytogenetic analysis in prognosis prediction of MGUS and multiple myeloma. METHODS: We enrolled 30 consecutive patients with a confirmed diagnosis of multiple myeloma or MGUS. Bone marrow biopsy and biochemical staging according to the International Staging System (ISS) were performed in all cases. Karyotype analysis and FISH were performed in 11 of 12 patients with MGUS and in 17 of 18 patients with multiple myeloma having adequate metaphases. RESULTS: The karyotype was abnormal in four of 11 MGUS and in six of 17 multiple myeloma. Abnormalities of chromosome 13 were present in one case of MGUS and in six cases of multiple myeloma whereas the involvement of immunoglobulin was observed in one case of multiple myeloma. An abnormal FISH panel was found in four MGUS and nine multiple myeloma patients. All patients with MGUS showed a normal MIBI scan (score 0). Among patients with multiple myeloma only three, all with ISS stage I, showed a normal scan while a positive scan was obtained in others (score range, 1-7). The MIBI uptake was strongly related to the bone marrow plasma cell infiltration and to cytogenetic abnormalities. Particularly, a MIBI uptake score above 5 identified patients with poor prognosis encompassing all stage III multiple myeloma and three of seven stage II multiple myeloma. On the other hand all stage I and II patients having a MIBI score less than 5 showed a good prognosis. CONCLUSION: Both cytogenetic analysis and a MIBI scan add no relevant prognostic information to the ISS in patients with stage I and III multiple myeloma. The MIBI scan was of prognostic value in stage II multiple myeloma patients. Additionally, MIBI imaging may be useful to guide bone marrow biopsy in order to obtain adequate samples for cytogenetic analysis.

Sentinel lymph node involvement and a high Breslow index are independent factors of risk for early relapse of melanoma.

AIM: The clinical relevance of sentinel lymph node (SLN) analysis was evaluated prospectively and compared with other known risk factors of relapse in early stage melanoma. METHODS: Surgery was guided by lymphoscintigraphy, blue dye and gamma probe detection. SLN were analysed by haematoxylin eosin (HE) histochemistry and multimarker immunohistochemistry (IHC). Disease free survival (DFS) was evaluated with Kaplan-Meier plots according to different parameters and Cox analyses of variance. RESULTS: From 210 patients a total of 381 SLN were excised. Lymphoscintigraphy identified all excised SLN with only 2 false positive lymphatic lakes. Fifty patients (24%) had tumour positive SLN. With a mean follow-up of 31.3 months, 29 tumour recurrences were observed, 19 (38%) in 50 SLN positive and 10 (6%) in 160 SLN negative patients. Strong predictive factors for early relapse (p &lt; 0.0005) were SLN positivity and a high Breslow index. CONCLUSION: SLN tumour positivity is an independent factor of high risk for early relapse with a higher power of discrimination than the Breslow index.

Benign Intrapulmonary Schwannoma: Aspect on F-18 Fluorodeoxyglucose PET/CT.

A 75-year-old man, with no significant symptoms, was referred after the incidental finding of a left hilar pulmonary mass of 30 �� 30 �� 50 mm on a chest CT. F-18 fluorodeoxyglucose (FDG) PET/CT demonstrated a heterogeneous, moderate radiotracer uptake in the mass (SUV 3.5 g/mL). Bronchoscopy revealed a discrete extrinsic compression of the superior bronchus without endobronchial lesion. Endobronchial fine-needle biopsies could not deliver a final diagnosis. The patient underwent upper lobectomy by thoracotomy. Histopathology revealed a benign intrapulmonary schwannoma. Although rare, intermediate FDG uptake in the settings of a pulmonary mass should include schwannoma in the differential diagnosis.