Actualización de protocolos de cardiología nuclear para evaluación y manejo de enfermedad coronaria: Sociedad Chilena de Cardiología y Cirugía Cardiovascular / Update in protocols of nuclear cardiology for the evaluation and management of coronary heart disease

Se revisan los protocolos de cardiología nuclear actuales, con énfasis en los estudios tomográficos de fotón único (“SPECT”) de perfusión miocárdica principalmente en evaluación de enfermedad coronaria (EC). Las indicaciones y protocolos más utilizados son detallados, así como la actualización bibliográfica pertinente, tanto al uso clínico como al control de calidad e interpretación de los estudios.

Importância da complementação com SPECT e 99mTc na cintilografia das paratiroides e da correlação clínica, laboratorial, ultrassonográfica e citológica na localização pré-operatória do adenoma de paratiroide - ensaio pictórico / Importance of parathyroid SPECT and 99mTc scintigraphy, and of clinical, laboratorial, ultrasonographic and citologic correlation in the pre-operative localization of the parathyroid adenoma - pictorial assay

OBJETIVO: Diante de um paciente portador de hiperparatiroidismo primário com indicação de tratamento cirúrgico, a localização pré-operatória da paratiroide é de fundamental importância para definir a melhor abordagem cirúrgica. MATERIAIS E MÉTODOS: A realização adicional de imagens SPECT e da cintilografia com 99mTc durante a cintilografia das paratiroides com Setamibi não é rotina em nosso meio, sendo comum a aquisição apenas das imagens planas − precoce (15 minutos) e tardia (2 horas). RESULTADOS: Na nossa experiência, tem-se percebido que a realização do protocolo completo contribui de maneira decisiva na sensibilidade da localização pré-operatória da paratiroide. CONCLUSÃO: A aplicação completa de todos os métodos cintilográficos disponíveis (SPECT e 99mTc) e a análise cuidadosa das imagens em um contexto multidisciplinar podem aumentar a acurácia da cintilografia das paratiroides.

OBJECTIVE: In patients with primary hyperparathyroidism, candidates for surgical intervention, the parathyroid pre-operative localization is of fundamental importance in planning the appropriate surgical approach. MATERIALS AND METHODS: The additional acquisition of SPECT and Technetium-99m images, during parathyroid scintigraphy with Sestamibi, is not common practice. Usually, only planar image acquisition, 15 minutes prior and 2 hours after radiopharmaceutical administration, is performed. RESULTS: In our experience, the complete protocol in parathyroid scintigraphy increases the accuracy of pre-operative parathyroid localization. CONCLUSION: The complete utilization of all available nuclear medicine methods (SPECT e 99mTc) and image interpretation in a multidisciplinary context can improve the accuracy of parathyroid scintigraphy.

New approach for attenuation correction in SPECT images, using linear optimization

Photon attenuation as an inevitable physical phenomenon influences on the diagnostic information of SPECT images and results to errors in accuracy of quantitative measurements. This can be corrected via different physical or mathematical approaches. As the correction equation in mathematical approaches is nonlinear, in this study a new method of linearization called 'Piece Wise Linearization' [PWL] is introduced and to substantiate its validity for SPECT image reconstructions, a phantom study is performed. A SPECT scan of a homemade heart phantom filled with 2 mCi 99mTc was acquired by dual head Siemens E.Cam gamma camera equipped with LEHR collimator. Row data of the scan were transferred in DICOM format to a pc computer for reconstruction of the images using MLEM iterative algorithm in Matlab software. Attenuation map of the phantom micro [chi] were derived using PWL with linear optimization approach. Based on that, the attenuation corrected SPECT image of the phantom were reconstructed and compared with non-corrected image, using MLEM iterative algorithm. Comparison of the corrected and non-corrected images confirmed with CT attenuation correction method. Attenuation correction in SPECT image can be achieved successfully, using emission data and piecewise linearization with linear optimization approach. The corrected image of f[chi] and attenuation map micro[chi] of the heart phantom using this approach promise acceptable image quality for diagnostic clinical use

Utilidad de la tomografía computarizada de emisión de fotón único sincronizada con el electrocardiograma para la detección de isquemia miocárdica silente en diabéticos tipo 2 / Gated single photon emission computer tomography for the detection of silent myocardial ischemia

Background: Asymptomatic patients with severe coronary atherosclerosis may have a normal resting electrocardiogram and stress test. Aim: To assess the yield of Gated Single Photon Emission Computer Tomography (SPECT) for the screening of silent myocardial ischemia in type 2 diabetic patients. Material and methods: Electrocardiogram, stress test and gated-SPECT were performed on 102 type 2 diabetic patients aged 60 ± 8 years without cardiovascular symptoms. AH subjects were also subjected to a coronary angiography whose results were used as gold standard. Results: Gated-SPECT showed myocardial ischemia on 26.5 percent of studied patients. The sensibility, specifity accuracy, positive predictive value and negative predictive value were 92.3 percent, 96 percent, 95 percent, 88.8 percent, 97.3 percent, respectively. In four and six patients ischemia was detected on resting electrocardiogram and stress test, respectively. Eighty percent of patients with doubtful resting electrocardiogram results and 70 percent with a doubtful stress test had a silent myocardial ischemia detected by gated-SPECT There was a good agreement between the results of gated-SPECT and coronary angiography (k =0.873). Conclusions: Gated-SPECT was an useful tool for the screening of silent myocardial ischemia.

Avaliação da prescrição de exercícios pela cintilografia miocárdica na reabilitação de coronariopatas / Evaluation of prescription of exercise, for rehabilitation of coronary artery disease patients by myocardial scintigraphy

FUNDAMENTO: Recomenda-se que a intensidade dos exercícios na reabilitação de coronariopatas não deva produzir isquemia miocárdica. OBJETIVO: Comparar a capacidade da cintilografia tomográfica do miocárdio com a do eletrocardiograma na detecção de isquemia durante sessão de reabilitação. MÉTODOS: Vinte e seis pacientes coronariopatas, em programa de reabilitação e com cintilografia prévia com hipocaptação transitória, receberam nova injeção de MIBI-Tc-99m durante uma sessão de treinamento, quando também foram monitorizados pela eletrocardiografia dinâmica. As cintilografias de repouso, após teste ergométrico em esteira e após sessão de reabilitação, foram analisadas de forma semiquantitativa utilizando-se um escore, de 0 a 4, classificando cada um dos segmentos escolhidos (0 = normal; 1 = hipocaptação discreta; 2 = moderada; 3 = intensa; 4 = ausência da captação). RESULTADOS: As médias dos somatórios dos escores encontrados foram: repouso = 12,9; após teste em esteira = 19,3; após sessão de reabilitação = 15,1. Houve diferenças estatisticamente significativas entre elas. Uma análise individual mostrou que em 14 casos (53,8 por cento) foi identificado algum grau de hipocaptação durante a reabilitação, e em 12 (46,6 por cento), não. Monitorização com sistema Holter não revelou, em nenhum caso, depressão do segmento ST, igual ou maior do que 1 mm. CONCLUSÃO: Exercícios prescritos em doentes coronariopatas, conforme recomendações da literatura, podem desencadear isquemia miocárdica, avaliada pela cintilografia, durante sessão de reabilitação.

BACKGROUND: It is advisable that the intensity of the exercises for rehabilitation of patients with coronary artery disease does not cause myocardial ischemia. OBJECTIVE: Compare the capacity of myocardial tomographic scintigraphy with the electrocardiogram capacity in ischemia detection during rehabilitation session. METHODS: Twenty six patients with coronary artery disease, undergoing the rehabilitation program and with previous scintigraphy, with transient hypo-uptake have been administered a new injection of MIBI-Tc-99m during a training session when they were also monitored with dynamic electrocardiography. The rest scintigraphies, after ergometric treadmill test and rehabilitation session, were assessed in a semi-quantitative way using scores from 0 to 4 to classify each one of the chosen segments (0 = normal; 1 = discrete hypo-uptake; 2 = moderate; 3 = intense; 4 = lack of uptake). RESULTS: The means of the total scores found were: at rest = 12.9; after treadmill test = 19.3; after rehabilitation session = 15.1. There were statistically significant differences among them. An individual assessment showed that in 14 cases (53.8 percent) hypo-uptake to some degree was identified during rehabilitation and in 12 cases (46.6 percent) it was not. Monitoring with the Holter system didn't show in any of the cases a ST segment depression equal or greater than 1mm. CONCLUSION: The exercises prescribed for patients with coronary artery disease, according to recommendations found in the literature, may trigger myocardial ischemia, assessed by scintigraphy during a rehabilitation session.

Parkinsons disease and dopamine transporter neuroimaging: a critical review / Doença de Parkinson e neuroimagem do transportador de dopamina: uma revisão crítica

Parkinsons disease (PD) is a common neurodegenerative disorder that is mainly caused by dopaminergic neuron loss in the substantia nigra. Several nuclear medicine radiotracers have been developed to evaluate PD diagnoses and disease evolution in vivo in PD patients. Positron emission tomography (PET) and single photon computerized emission tomography (SPECT) radiotracers for the dopamine transporter (DAT) provide good markers for the integrity of the presynaptic dopaminergic system affected in PD. Over the last decade, radiotracers suitable for imaging the DAT have been the subject of most efforts. In this review, we provide a critical discussion on the utility of DAT imaging for ParkinsonÆs disease diagnosis (sensitivity and specificity).

A doença de Parkinson (DP) é uma desordem neurodegenerativa causada por perda de neurônios dopaminérgicos na substância negra. Vários traçadores da medicina nuclear têm sido desenvolvidos para avaliar o diagnóstico e acompanhamento da DP. Traçadores para o transportador de dopamina (TDA) utilizados na tomografia por emissão de pósitrons (PET) e tomografia por emissão de fóton único (SPECT) demonstram boa marcação na integridade de sistema dopaminergico pré-sináptico, afetada na DP. Na última década, radiotraçadores apropriados para imagens de TDA têm sido mais estudados. Nesta revisão, provemos uma discussão crítica sobre a utilidade dessas imagens de TDA para o diagnóstico de DP (sensibilidade e especificidade).