Effect of b value on monitoring therapeutic response by diffusion-weighted imaging.
World J Gastroenterol
; 14(38): 5893-9, 2008 Oct 14.
Article
em En
| MEDLINE
| ID: mdl-18855990
ABSTRACT
AIM:
To explore the diffusion gradient b-factor that optimizes both apparent diffusion coefficient (ADC) measurement and contrast-to-noise (CNR) for assessing tumor response to transarterial chemoembolization (TACE) in a rabbit model.METHODS:
Twelve New Zealand white rabbits bearing VX2 tumors in the liver were treated with TACE. Diffusion-weighted imaging (DWI) with various b values was performed using the same protocol before and 3 d after treatment with TACE. ADC values and CNR of each tumor pre- and post-treatment with different b factors were analyzed. Correlation between ADC values and extent of necrosis in histological specimens was analyzed by a Pearson's correlation test.RESULTS:
The quality of diffusion-weighted images diminished as the b value increased. A substantial decrease in the mean lesion-to-liver CNR was observed on both pre- and post-treatment DW images, the largest difference in CNR pre- and post-treatment was manifested at a b value of 1000 s/mm(2) (P = 0.036 ). The effect of therapy on diffusion early after treatment was shown by a significant increase in ADCs (P = 0.007), especially with large b factors (>= 600 s/mm(2)). The mean percentage of necrotic cells present within the tumor was 76.3%-97.5%. A significant positive correlation was found between ADC values and the extent of necrosis with all b values except for b200, a higher relative coefficient between ADC values and percentage of necrosis was found on DWI with b1000 and b2000 (P = 0.002 and 0.006, respectively).CONCLUSION:
An increasing b value of up to 600 s/mm(2) would increase ADC contrast pre- and post-treatment, but decrease image quality. Taking into account both CNR and ADC measurement, diffusion-weighted imaging obtained with a b value of 1000 s/mm(2) is recommended for monitoring early hepatic tumor response to TACE.
Texto completo:
1
Bases de dados:
MEDLINE
Assunto principal:
Quimioembolização Terapêutica
/
Imagem de Difusão por Ressonância Magnética
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Neoplasias Hepáticas Experimentais
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Modelos Biológicos
Tipo de estudo:
Guideline
/
Prognostic_studies
Limite:
Animals
Idioma:
En
Revista:
World J Gastroenterol
Assunto da revista:
GASTROENTEROLOGIA
Ano de publicação:
2008
Tipo de documento:
Article
País de afiliação:
China