Purpose: to investigate whether water diffusion is anisotropic in livers affected by cirrhosis. Methods and Materials: Ten cirrhotic patients and 10 controls underwent DW-MRI on a 3.0T-system. A respiratory-triggered Echo-Planar sequence was acquired, using sequential, independent and unidirectional motion-probing gradients along slice, read and phase directions, respectively. Liver Apparent Diffusion Coefficient (ADC) and true Diffusion coefficient (D) were calculated for each direction as average of multiple signal measurements, based on two sets of b-values (0-400 and 0-800 sec/mm2). Volume fraction (f), corresponding to the fraction of the diffusion linked to microcirculation, was calculated too. Results: No significant difference among slice-, read- and phase-liver values of ADC, D and f was found within controls and cirrhotic patients (p<0.01;Kruskal-Wallis test). Irrespective of the gradient direction, the difference between ADC and D was significantly large (0.55-0.74 x10-3 mm2/sec) within the healthy liver group (p<0.01;Mann-Whitney test), and small and not significant (0.13.-0.21 x10-3 mm2/sec) within the cirrhotic liver group (p>0.01). Mean hepatic ADC and D resulted significantly lower (p<0.01;Mann-Whitney test) in cirrhotic subjects as compared to controls (1.13-1.31 x10-3 mm2/sec vs. 1.6-2.1 x10-3 mm2/sec, respectively), together with f (5-7% vs. 19-24%, respectively). Conclusion: Despite the presence of advanced fibrosis, water diffusion in the cirrhotic liver is isotropic, like occurs in the healthy liver group. As suggested by differences in D, alterations in perfusion (f) rather than in diffusive motion should be considered responsible for the ADC decrease between cirrhotic and healthy liver groups.
Diffusion-weighted magnetic resonance imaging (DW-MRI) at 3.0 Tesla in evaluating water diffusion pattern in cirrhotic livers: preliminary results.
GIROMETTI, Rossano;ESPOSITO, Gennaro;Cereser L;BAZZOCCHI, Massimo;ZUIANI, Chiara
2011-01-01
Abstract
Purpose: to investigate whether water diffusion is anisotropic in livers affected by cirrhosis. Methods and Materials: Ten cirrhotic patients and 10 controls underwent DW-MRI on a 3.0T-system. A respiratory-triggered Echo-Planar sequence was acquired, using sequential, independent and unidirectional motion-probing gradients along slice, read and phase directions, respectively. Liver Apparent Diffusion Coefficient (ADC) and true Diffusion coefficient (D) were calculated for each direction as average of multiple signal measurements, based on two sets of b-values (0-400 and 0-800 sec/mm2). Volume fraction (f), corresponding to the fraction of the diffusion linked to microcirculation, was calculated too. Results: No significant difference among slice-, read- and phase-liver values of ADC, D and f was found within controls and cirrhotic patients (p<0.01;Kruskal-Wallis test). Irrespective of the gradient direction, the difference between ADC and D was significantly large (0.55-0.74 x10-3 mm2/sec) within the healthy liver group (p<0.01;Mann-Whitney test), and small and not significant (0.13.-0.21 x10-3 mm2/sec) within the cirrhotic liver group (p>0.01). Mean hepatic ADC and D resulted significantly lower (p<0.01;Mann-Whitney test) in cirrhotic subjects as compared to controls (1.13-1.31 x10-3 mm2/sec vs. 1.6-2.1 x10-3 mm2/sec, respectively), together with f (5-7% vs. 19-24%, respectively). Conclusion: Despite the presence of advanced fibrosis, water diffusion in the cirrhotic liver is isotropic, like occurs in the healthy liver group. As suggested by differences in D, alterations in perfusion (f) rather than in diffusive motion should be considered responsible for the ADC decrease between cirrhotic and healthy liver groups.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
