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Objective: To evaluate the ADC value in the early diagnosis of children with viral encephalitis in rats. Explore the ADC value and DWI, T1WI, T2WI, FLAIR sequence CNR each chapter of viral encephalitis in children in the variation. Methods: June 2005-December 2007 clinical diagnosis of viral encephalitis in parallel MRI, 34 cases as encephalitis group. Ages 2 months to 168 months (14 years old), with an average 51.6 months. From MRI, neurological symptoms to the time interval (time of onset) earliest eight hours, at the latest 33 days, including 7 days of treatment, 19 cases (55.9%). Choose lesions consistent and uniform signal measured at a large range and avoid the attention of the cerebrospinal fluid located. Of which eight cases magnetic resonance enhanced MRI, magnetic resonance angiography (MRA) examination in 5 cases, MRI review of four cases. In the age difference is not more than one month, brain MRI was normal, without any neurological symptoms and signs of other reasons to our hospital 34 cases of children as control group, the ADC values ??of the measured position of encephalitis similar age group consistent lesion location: unilateral onset encephalitis group simultaneously measure the corresponding parts of the brain tissue contralateral ADC value as a control. Encephalitis group and the control group underwent conventional T1WI (T1-weighted imaging), T2WI (T2-weighted imaging), FLAIR (fluid-attenuated inversion recovery sequences) and DWI (DWI) axial scanning. ADC maps automatically generated by a computer software. To b = 1000s/mm 2 when DWI and conventional MRI, T1WI, T2WI, FLAIR image comparison. By the two experienced physicians go further according to the display of the number of lesions, lesion size and scope of the level of the signal strength cases are grouped: Ⅰ group DWI is superior to conventional MRI; Ⅱ group of DWI and conventional MRI consistent; Ⅲ group conventional MRI better than DWI. Statistics in each group respectively corresponding time of onset, lesions in each group were calculated and compared with the control group, the corresponding parts of the apparent diffusion coefficient (ADC value), comparing each lesion DWI, T1WI, T2WI and FLAIR sequences various checks contrast to noise ratio (CNR ). The data obtained by SPSS11.5 statistical software to P <0.05 was considered statistically significant. Results: ① results showed lesions grouped according to: Ⅰ group (n = 10) DWI is superior to conventional MRI, the average time of onset (3.1 ± 1.4) days; Ⅱ group (n = 9) DWI and conventional MRI basically the same, the average time of onset ( 5.6 ± 1.9) days; Ⅲ group (n = 15) than conventional MRI DWI, the average time of onset (15.3 ± 7.7) days. Encephalitis group Ⅰ group and control group mean ADC values ??were (61.8 ± 15.6 × 10 -5 ) mm 2 / s, (89.7 ± 11.6 × 10 -5 ) mm 2 / s; Ⅱ group encephalitis group, the control group mean ADC values ??were (85.2 ± 11.5 × 10 -5 ) mm < sup> 2 / s, (84.6 ± 5.8 × 10 -5 ) mm 2 / s; Ⅲ group encephalitis group, the control group, the average ADC value was (119.9 ± 11.3 × 10 -5 ) mm 2 / s, (85.6 ± 5.2 × 10 -5 ) mm 2 / s. Statistically, the encephalitis group ADC values ??between any two groups there was a significant difference (P <0.05). Control group without any significant difference between the two groups (P> 0.05). ADC values ??encephalitis group Ⅰ group was significantly lower than the control group (t = -5.273, P = 0.001 <0.01), Ⅱ group encephalitis ADC values ??with the control group no significant difference (t = 0.154, P = 0.882> 0.05), ADC values ??encephalitis group Ⅲ group was significantly higher (t = 11.737, P = 0.000 <0.01). CNR each sequence group Ⅰ were DWI (64.10 ± 21.54), T1WI (13.51 ± 13.60), T2WI (24.75 ± 21.94), FLAIR (4.78 ± 3.03), DWI were significantly higher than the CNR T1WI, T2WI, FLAIR (t = 6.491, P = 0.000; t = 3.992, P = 0.003; t = 8.321, P = 0.000); Ⅱ group CNR various sequences were DWI (35.18 ± 39.33), T1WI (21.64 ± 16.92), T2WI (56.54 ± 25.71) , FLAIR (20.67 ± 8.66), DWI CNR of sequence with the other three were not significantly different (t = 0.862, P = 0.414; t = -1.515, P = 0.168; t = 1.141, p = 0.287); Ⅲ each group CNR sequences were DWI (25.23 ± 22.27), T1WI (15.28 ± 15.34), T2WI (78.24 85.45), FLAIR (23.84 ± 11.87), DWI CNR of significantly lower T2WI (t = -2.577, P = 0.022), and T1WI, FLAIR CNR of no significant difference (t = 1.408, p = 0.181; t = 0.328, P = 0.748). The three groups of patients showed lesions were positive: Ⅰ group, DWI, 100% (10/10), conventional MRI, 60% (6/10); Ⅱ group, DWI, 100% (9/9), conventional MRI , 100% (9/9); Ⅲ group, DWI, 53% (8/15), conventional MRI, 100% (15/15). Chapter viral encephalitis in children early lesions showed high signal on DWI, ADC map showed low signal, the ADC value decreased, DWI showed lesions was significantly higher than that of conventional MR sequences; Progress with the disease, DWI showed high signal ADC maps close to other signals, ADC values ??close to normal, DWI showed lesions, the positive rate is equal to conventional MR sequences; After DWI showed equal or low signal, ADC map showed high signal, ADC value increased, DWI showed lesions, the positive rate was significantly lower on conventional MR sequences. ② encephalitis group ADC values, encephalitis and control groups ADC value ratio (ADCR) and encephalitis group and the control group the difference between ADC values ??were (93.61 ± 28.14 × 10 -6 ) mm 2 / s, (1.09 ± 0.34), (7.07 ± 29.59 × 10 -6 ) mm 2 / s, the statistical treatment, were associated with onset time was a significant positive correlation (r s = 0.820, P = 0.000; r s = 0.840, P = 0.000: r s = 0.837, P = 0.000). ③ age of children (9.15 ± 7.67) months with encephalitis group ADC values ??(93.61 ± 28.14 × 10 -5 ) mm 2 / s no correlation (r = - 0.069, P = 0.698> 0.05), age of children (9.15 ± 7.67) months and the control group ADC values ??(86.54 ± 7.78 × 10 -6 ) mm 2 / s was significantly negatively correlated, and closely related (r = -0.464, P = 0.006 <0.05), ie, normal children parenchymal ADC values ??decreased with increasing age. ④ encephalitis group enhanced MRI of the 8 patients, 2 patients had a little small punctate enhancement; MRA examined five cases were normal. Conclusions: In children with viral encephalitis earlier, ADC value decreased, DWI CNR of higher T1WI, T2WI, FLAIR: Progress with the disease, ADC value increased, DWI CNR of less than T2WI. DWI showed lesions early positive rate was significantly higher than conventional MR sequences, with the lesions progress, significantly lower than conventional MR sequences. ADC value and diffusion weighted imaging in children with viral encephalitis has an important role in early diagnosis. Highly suspected viral encephalitis in children should be routinely performed early diffusion-weighted imaging, ADC value measurements to improve early diagnosis.
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