RESUMO
Dynamic contrast-enhanced (DCE) methods are widely used with magnetic resonance imaging and computed tomography to assess the vascular characteristics of tumours since these properties can affect the response to radiotherapy and chemotherapy. In contrast, there have been far fewer studies using optical-based applications despite the advantages of low cost and safety. This study investigated an appropriate kinetic model for optical applications to characterize tumour haemodynamics (blood flow, F, blood volume, V(b), and vascular heterogeneity) and vascular leakage (permeability surface-area product, PS). DCE data were acquired with two dyes, indocyanine green (ICG) and 800 CW carboxylate (IRD(cbx)), from a human colon tumour xenograph model in rats. Due to the smaller molecular weight of IRD(cbx) (1166 Da) compared to albumin-bound ICG (67 kDa), PS of IRD(cbx) was significantly larger; however, no significant differences in F and V(b) were found between the dyes as expected. Error analysis demonstrated that all parameters could be estimated with an uncertainty less than 5% due to the high temporal resolution and signal-to-noise ratio of the optical measurements. The next step is to adapt this approach to optical imaging to generate haemodynamics and permeability maps, which should enhance the clinical interest in optics for treatment monitoring.
Assuntos
Meios de Contraste , Modelos Biológicos , Neoplasias/metabolismo , Espectroscopia de Luz Próxima ao Infravermelho , Animais , Benzenossulfonatos/química , Capilares/metabolismo , Linhagem Celular Tumoral , Transformação Celular Neoplásica , Neoplasias do Colo/metabolismo , Neoplasias do Colo/patologia , Neoplasias do Colo/fisiopatologia , Meios de Contraste/química , Hemodinâmica , Humanos , Indóis/química , Cinética , Masculino , Peso Molecular , Neoplasias/irrigação sanguínea , Neoplasias/fisiopatologia , Permeabilidade , RatosRESUMO
Uranium is ubiquitously found in drinking water and food. The gastrointestinal tract absorption fraction (f(1)) is an important parameter in risk assessment of uranium burdens from ingestion. Although absorption of uranium from ingestion has been studied extensively in the past, human data concerning children and adults are still limited. In a previous study based on measurements of uranium concentration in 73 bone-ash samples collected by Health Canada, the absorption fractions for uranium ingestion were determined to be 0.093 ± 0.113 for infants, and 0.050 ± 0.032 for young children ranging from 1 to 7 y of age. To extend the study, a total of 69 bone-ash samples were selected for children and adults ranging from 7 to 25 y of age and residing in the same Canadian community that is known to have an elevated level of uranium in its drinking water supply. For each bone-ash sample, the total uranium concentration was measured by inductively coupled plasma mass spectrometry. To solve uranium transfer in the biokinetic model for uranium given in International Commission of Radiological Protection (ICRP) Publication 69 with estimated daily uranium intake, the program WinSAAM v3.0.1 was used. The absorption fractions were determined to be 0.030 ± 0.022 for children (7-18 y) and 0.021 ± 0.015 for adults (18-25 y). For anyone more than 18 y of age, the estimated f(1) value for uranium agree well with the ICRP recommended value of 0.02.
