MR characterization of brain and brain tumor response to radiotherapy.

This paper describes our experience in using the T1 and T2 relaxation times for quantitative evaluation of brain and brain tumor response to radiation therapy. Twenty-two computed T1 and 22 computed T2 images were obtained from 66 routine inversion-recovery and spin-echo magnetic resonance (MR) brain scans. The relaxation times of the brain tissues, determined from the computed images, were examined as a function of the absorbed dose. Statistical evaluation of the results showed no significant difference between the relaxation times of irradiated and not irradiated tissues, including tumor and normal white matter. Influence of the magnetic field strength and imaging techniques on the computed T1 and T2 values was confirmed. We conclude that the relaxation time values, as obtained today using conventional MR scanner and standard software, are not specific enough to warrant a correct assessment of the acute radiation effect on the brain tissues.

Physical and electrocardiographic evaluation of horses used for wagon traction / Avaliação física e eletrocardiográfica de cavalos utilizados para tração de carroças

The objective of this research was to evaluate the electrocardiogram (ECG) of horses used for wagon traction and to compare the results with the parameters obtained from inactive horses or horses submitted to a training routine. Fifty-six 3-15-year-old healthy horses (22 females and 34 males) were divided into three groups: control (without a work routine; N=21), wagon traction (N=25) and athlete (N=10) and submitted to physical examination and ECG (at rest). The rhythm, heart rate (HR), amplitude and duration of ECG waveforms and intervals were obtained from the frontal plane and base-apex leads. Heart score (HS) was calculated using the arithmetic mean of QRS duration in LI, LII and LIII. Measurements of ECG waves were smaller in control group, in comparison with wagon traction and athlete groups, suggesting that exercise can change ECG. Similar results were observed in the wagon traction and athlete groups, but the electrophysiological adjustments to exercise were not the same for these groups.(AU)

O objetivo deste trabalho foi avaliar o eletrocardiograma (ECG) de cavalos que tracionavam carroças (carroceiros; N=25), comparando os resultados com os parâmetros de cavalos que não realizavam essa atividade (controles; N=21), ou que apresentavam uma rotina de treinamento (atletas; N=10). O ECG foi precedido pelo exame físico do animal e, a partir das derivações no plano frontal e na base-ápice, determinou-se o ritmo, a frequência cardíaca, a amplitude e a duração das ondas e dos intervalos, em repouso. O escore cardíaco foi calculado pela média aritmética da duração do complexo QRS em DI, DII e DIII. O grupo controle apresentou menores valores de amplitude e duração das ondas do ECG, em comparação aos grupos carroceiro e atleta, sugerindo que o exercício pode alterar o ECG. Resultados semelhantes foram observados nos grupos carroceiro e atleta; contudo, os ajustes eletrofisiológicos ao exercício não foram os mesmos para esses dois grupos.(AU)