| [Objective ]1. To quantitatively study the ADC values of normal white matter with advancing age on diffusion and establish reference values of ADC for further studies of radiation-induced injury.2. To elucidate the manifestations and significance on MR DWI in diagnosis of radiation-induced injury and further evaluate the clinical value of quantitative measurement of mild structure changes on MR DWI.[Materials and Methods]1. The correlative study of ADC changes with advancing age: The study included 50 patients with normal appearing white matter. The subjects were divided into four group by age; age groups were first group(16~30years, n=13), second group(31~45years, n=12), third group(46~60years, n=14), fourth group(>60years, n=11). The ADCav of white matter and thalamus were measured and compared in various age groups.2. The study of normal reference values of temporal lobe: The study included 30 age-matched control subjects compared with normal appearing group following radiotheraphy, defined as control group with normal white matter. ADC and CV values were calculated to provide normal reference values for comparison analysis between control group and normal appearing group following radiotheraphy.3. The quantitative study of normal appearing group following radiotherapy for nasopharyngeal carcinoma on diffusion weighted-imaging: The study included 30 patients with normal appearing MRI following radiotherapy, defined as normal appearing group following radiotherapy. ADC and CV values were measured and compared with the control group.4. The study of clinical application on DWI for radiation-induced temporal lobe injury: 51 patients with ratiation-induced injury in nasopharyngeal carcinoma (NPC) were review. All patients were diagnosed by clinical manifestations and MR imaging. The disease was divided into white matter type and gray matter type by described criterion, and the white matter type included white matter type I phase and white matter type II phase. The ADC and CV values were analyzed and compared between lesion and control region.5. All these data were analyzed with statistical methods of one-way ANOVA, t-test, least-significant difference, correlative ang regression analysis.[Results]1. The correlative study of ADC changes with advancing age: In white matter, the ADCav among all patients was (0.71± 0.08)×10-3mm2/s; the ADCav of white matter in the first to fourth group were (0.69±0.06)× 10-3mm2/s, (0.71±0.07) ×10-3mm2/s, (0.71±0.09)× 10'3mm2/s, (0.73 ± 0.10)×10-3mm2/s. ADCav in the first group was significantly different from ADCav for patients in the fourth( P=0.014); patients older than 60 years had an ADCav for white matter of (0.73 ± 0.10) × 10-3mm2/s , which is significantly higher than the ADCav among all patients 60 years or younger(0.70±0.07)× 10-3mm2/s ( P=0.026) .For the thalamus, the ADCav among the entire study population was (0.83±0.07)× 10-3mm2/s, which was significantly different from the ADCav in white matter(P<0.001). The thalamic ADCav was not significantly different each other in various age groups. Comparison of the thalamic ADCav in patients older than 60 years[(0.84±0.06) × 10-3 mm2/s] with those 60 years or younger[(0.83 ± 0.08) × 10-3mm2/s] also showed not significantly different( P=0.376).2. The study of normal reference values of temporal lobe: In white matter, the ADCav among all patients was (0.71± 0.08)× 10"3mm2/s; ADCT was (0.82±0.10) × 10-3mm2/s; ADCav and ADCT was not significantly different each other (t= -0.34, P=0.734) . In gray matter, the ADCH among the entire study population was (0.91±0.12) × 10-3mm2/s, which was significantlydifferent from the ADCT in white matter(P<0.001) (t= 4.32, P=0.000) . In the white matter of temporal lobe , diffusion was anisotropic, and the coefficient of variation in anisotropic diffusion was (17.68 ± 6.69)%.3. The quantitative study of normal appearing group following radiotherapy for nasopharyngeal carcinoma on diffusion weighted-im...
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