ABSTRACT
Objective To evaluate the biodistribution and radiation-absorbed doses of main organs in healthy people with 13 N-ammonia.Methods Five healthy volunteers underwent whole-body PET and CT scans after injection of 666-814 MBq of 13 N-ammonia.The serial dynamic emission images of each healthy volunteer were acquired.ROI were drawn manually based on the transverse CT images and transferred to the corresponding PET slices.Radiation-absorbed doses were calculated using the medical internal radiation dosimetry (MIRD) method.Results The highest concentrations of 13 N-ammonia were found in the heart,liver and kidneys,followed by pancreas,brain,spleen and stomach.The organ of highest absorbed dose was heart with (7.14±3.63) × 10-3 mGy/MBq.The whole-body absorbed dose was (2.11±0.44) × 10 3 mGy/MBq.The whole-body effective dose was (6.58± 1.23) × 10-3 mSv/MBq.Conclusion As one of the most important myocardial perfusion tracers,the whole-body 13 N-NH3 · H2 O PET appears to be safe for humans.
ABSTRACT
Objetivou-se avaliar o efeito de períodos de pré-emurchecimento das gramíneas Estrela- Africana-Branca [Cynodon plectostachyus (K. Schum.) Pilg.] e Tifton 85 (Cynodon sp.) sobre algumas características de suas silagens. Utilizou-se delineamento inteiramente casualizado com dez tratamentos e três repetições. Os tratamentos foram dispostos em esquema fatorial 2x5, sendo duas gramíneas (Estrela-Africana-Branca e Tifton 85) e cinco períodos de pré-emurchecimento da forragem (0, 1, 2, 3 e 4 h). As gramíneas foram cortadas aos 50 dias de rebrotação e permaneceram ensiladas por 55 dias em silos experimentais. O pré-emurchecimento promoveu aumento no teor de matéria seca da forragem cortada e da silagem das gramíneas Tifton 85 e Estrela Africana Branca. Houve diminuição nos teores de N-amoniacal (N-NH3/N-total) da silagem do capim-estrela-africana-branca, a uma taxa de 1,66 unidade percentual por hora de pré-emurchecimento, mas não houve alteração nessa variável da silagem do capim-tifton 85. A silagem do capim-tifton 85 apresentou maior recuperação de matéria seca, maior teor de FDN e menor teor de proteína bruta do que a silagem do capim-estrela-africana-branca. O pH e o teor de FDA das silagens não foram influenciados pelo pré-emurchecimento.
The objective of this work was to evaluate the effect of periods of pre-wilting of stargrass [Cynodon plectostachyus (K. Schum.) Pilg.] and Tifton 85 bermudagrass (Cynodon sp.) on some characteristics of their silage. Arandomized design with ten treatments and three replications was used. The treatments were arranged in a 2x5 factorial, two grasses (stargrass and Tifton 85) and five periods of pre-wilting of forage (0, 1, 2, 3 and 4 h). The grasses were harvested at 50 days regrowth and stored for 55 days in experimental silos. The pre-wilting caused an increase in dry matter content of forage and silage of both, Tifton 85 and stargrass. There was a decrease in the levels of ammonia-N (N-NH3/N-total) of the stargrass silage at a rate of 1.66 percentage unit per hour of pre-wilting, but there was no change in this variable of Tifton 85 silage. The Tifton 85 silage presented higher dry matter recovery and content of NDF and lower protein content than the silage stargrass. The pH and ADF content of the silage were not affected by pre-wilting.
ABSTRACT
PURPOSE: 13N-ammonia is a well known radiopharmaceutical for the measurement of a myocardial blood flow (MBF) non-invasively using PET-CT. In this study, we investigated a correlation between MBF obtained from dynamic imaging and myocardial perfusion score (MPS) obtained from static imaging for usefulness of cardiac PET study. METHODS: Twelve patients (11 males, 1 female, 57.9+/-8.6 years old) with suspicious coronary artery disease underwent PET-CT scan. Dynamic scans (6 min: 5 sec X 12, 10 sec X 6, 20 sec X 3, and 30 sec X 6) were initiated simultaneously with bolus injection of 11 MBq/kg 13N-ammonia to acquire rest and stress image. Gating image was acquired during 13 minutes continuously. Nine-segment model (4 basal walls, 4 mid walls, and apex) was used for a measurement of MBF. Time activity curve of input function and myocardium was extracted from ROI methods in 9 regions for quantification. The MPS were evaluated using quantitative analysis software. To compare between 20-segment model and 9-segment model, 6 basal segments were excluded and averaged segmental scores were used. RESULTS: There are weak correlation between MBF (rest, 0.18-2.38 ml/min/g; stress, 0.40-4.95 ml/min/g) and MPS (rest 22-91%, stress, 14-90%), however the correlation coefficient between corrected MBF and MPS in rest state was higher than stress state (rest r=0.59; stress r=0.80). As a thickening increased, correlation between MBF and MPS also showed good correlation at each segments. CONCLUSIONS: Corrected and translated MPS as its characteristics using 13N-ammonia showed good correlation with absolute MBF measured by dynamic image in this study. Therefore, we showed MPS is one of good indices which reflect MBF. We anticipate PET-CT could be used as useful tool for evaluation of myocardial function in nuclear cardiac study.