Apparent diffusion coefficient of hyperpolarized 3He with minimal influence of the residual gas in small animals

Imaging Of Lung Micromechanics With Hyperpolarized Gas Diffusion MRI: Regional Compliance

Introduction: Hyperpolarised (HP) gas MRI is sensitive to early lung ventilation heterogeneity in cystic fibrosis (CF) children. However, little is known if changes in lung microstructure accompany the disease progression. HP gas diffusion-weighted (DW) MRI has been shown to be a technique sensitive to changes in lung microstructure at the acinar level. Aims: Compare 3 He DW-MRI metrics of lung microstructure in children with mild CF and healthy controls (HC) at baseline, and to reassess the CF cohort after 2-years. Methods: 19 children with CF and normal spirometry (FEV 1 z-score> -2), and 10 HC were assessed with HP 3 He DW-MRI. 14 of the CF cohort were reassessed after 2-years. Apparent diffusion coefficient (ADC) and estimates of alveolar dimension (Lm D ) were calculated at each visit, and compared to previously reported ventilation defect percentage (VD%) values in the same cohort [Smith, L., et al. (2016). ERJ 48]. Results: No significant difference in mean ADC and Lm­ D ­ was observed between HC and CF children. In contrast, VD% was significantly larger (p D ; despite a significant increase in VD% (p=0.002) (Figure 1b). Conclusion: 3 He DW-MRI suggests that no acinar microstructural changes occur in the ventilated regions of early CF lung disease despite increases in ventilation heterogeneity.

Delineation of Spatially-Varied High-Risk GTV in Pancreatic Adenocarcinoma Using MRI-ADC Maps

To prospectively determine apparent diffusion coefficient (ADC) values of normally developing fetal lungs over gestation, as obtained by diffusion-weighted (DW) magnetic resonance imaging (MRI) and to investigate its potential application in fetuses with congenital diaphragmatic hernia (CDH). Informed consent was obtained for this cross-sectional study of 93 fetuses with normal lungs and 14 with isolated left-sided CDH, assessed between 18 and 40 weeks of gestation. MRI delineation of left and right lungs was performed on the native DW image, b0, and three values of ADC, corresponding to the overall value (ADC(avg)), and values for low and high values of b (ADC(low) and ADC(high), respectively) were calculated. Regression analysis was used to assess the relationship between gestational age and b0-values as well as calculated ADC values. The b0 and ADC values of normal and CDH fetuses were compared with normal ranges using the Mann-Whitney U-test. In fetuses with normal lungs, there was a negative correlation between gestational age and b0 values as well as with ADC(high), a positive correlation with ADC(low) but no correlation with ADC(avg). When measurable, ADC(high) values were lower in CDH as compared to fetuses with normal lungs and ADC(low) values were higher. ADC(low) was unrelated to lung volume. There is a significant relationship between ADC(low) and ADC(high) values and gestational age in normal fetal lungs. This relationship is most probably explained by developmental changes during the last three stages of lung development, which involve intense peripheral growth of airways and vessels as well as maturation. In CDH, measurement of ADC(low) might be useful as a predictor of postnatal outcome that is independent of lung volume.

To investigate the clinical application of diffusion weighted imaging (DWI) in uterine cervical cancer and the apparent diffusion coefficient (ADC) value in diagnosis and predicting treatment response. Twenty-eight patients with advanced primary cervical cancer confirmed by pathology and 10 cases of normal uterine cervix as control were recruited in this prospective clinical trial. To analyze the correlation between tumor volume measured in DWI and tumor maximum diameter measured according to the RECIST criteria. To compare the ADC value differences among the uterine cervical cancer, uterine myometrium, and normal uterine cervix. To compare the ADC values in 17 cancer patients before and after treatment. The illustration of tumor boundary in DWI was superior to conventional T2WI and post-enhancement T1WI. The DWI with higher b value (2000 s/mm(2)) had a better signal-to-noise ratio. The tumor volume measured in DWI has good correlation with tumor maximum diameter according to RECIST criteria (r = 0.759, P < 0.01). When b = 800 s/mm(2), the ADC values of the uterine cervical cancer, uterine myometrium, and normal uterine cervix were (9.85 ± 1.55)×10(-3) mm(2)/s, (14.20 ± 2.80)×10(-3) mm(2)/s, and (14.14 ± 0.45) ×10(-3) mm(2)/s. When b = 2000 s/mm(2), the ADC values of the uterine cervical cancer, uterine myometrium and normal uterine cervix were (7.38 ± 0.98)×10(-3) mm(2)/s, (8.52 ± 2.38)×10(-3) mm(2)/s, and (8.60 ± 0.63)×10(-3) mm(2)/s, respectively. There were significant differences between the cervical cancer and normal cervix or uterine myometrium (P < 0.001 for both). When b = 800 s/mm(2), the ADC value was (9.85 ± 1.55)×110(-3) mm(2)/s before and (13.41 ± 2.93)×10(-3) mm(2)/s after treatment (P < 0.001). When b = 2000 s/mm(2), the ADC value was (7.38 ± 0.98)×10(-3) mm(2)/s before and (8.93 ± 1.92)×10(-3) mm(2)/s after treatment (P = 0.008). Univariate logistic regression analysis showed that 25% ADC, 50%ADC, and 75%ADC in the tumor ADC value histogram before treatment were significantly correlated to the treatment outcome of cervical cancer (P < 0.05 for all). Multivariate regression analysis showed that 25%ADC, 50%ADC, and 75%ADC in the tumor ADC value histogram before treatment were not significantly correlated to the treatment outcome of cervical cancer (P > 0.05 for all). The values of ROC curves were 25%ADC = 0.818, 50%ADC = 0.775, and 75%ADC = 0.716 (P > 0.05), however, the 25% ADC showed a relatively stronger statistical power. DWI helps to confirm the morphology and exact target zone of the tumor for radiotherapy. DWI volume measurement is well correlated with RECIST criteria, particularly in volume measurement of irregular tumors. ADC value has a potential in quantitatively monitoring treatment response and predicting outcome of cervical cancers.

Introduction: Magnetic resonance (MR) imaging of hyperpolarised (HP) 3 He enables evaluation of gas diffusion in alveoli and quantification of alveolar geometry. In addition, dissolved 129 Xe MR is promising for assessment of pulmonary gas-exchange and measurement of alveolar septal thickness (ST). Objective: To evaluate lung microstructural changes in interstitial lung disease (ILD) with HP 3 He and 129 Xe MR. Methods: 129 Xe MR spectroscopy was performed on ten normals (23-74 yrs), four subjects with systemic sclerosis (SSc) and four with idiopathic pulmonary fibrosis (IPF). From this cohort, six normals and seven patients underwent 3 He apparent diffusion coefficient (ADC) mapping MRI. Full pulmonary function tests including DL CO and FVC were completed by all subjects. Results: Both 129 Xe ST and 3 He ADC values were elevated in subjects with SSc, and to a larger degree in those with IPF, compared with normals. The two MR metrics correlated significantly, suggesting that fibrotic remodelling of lung tissue both degrades gas-exchange efficiency and alters the underlying alveolar geometry. 129 Xe ST values correlated well with DL CO and FVC metrics (P 3 He ADC correlated significantly with DL- CO (P < 0.05) but not FVC. Conclusions: HP 129 Xe and 3 He MR methods are sensitive to concurrent microstructural changes in ILD affecting alveolar septal thickness and alveolar geometry.

Objective To determine the magnetic resonance diffusion weighted imaging (DWI) images of patients with endometrial stromal sarcoma (ESS) and to evaluate the related biological behavior. Methods Eighty ESS patients admitted to our hospital (January 2016 to December 2018) were included as the ESS group, and a contemporary cohort of 75 patients with uterine fibroids (UM) was included as the UM group. Conventional magnetic resonance imaging and DWI examination were performed in both groups, and the DWI apparent diffusion coefficient (ADC) values were calculated. According to ADC values, 80 ESS patients were divided into two subgroups: high ADC value group (n=40) and low ADC value group (n=40) . After the relevant examinations were completed, all patients received surgical treatment. The pathological specimens were taken to examine the expression levels of proliferating genes (Survivin, CyclinD1, Sp1 and Rb) and estrogen and progesterone receptors (SULT1E1, PRA, PRB, ERα and ERβ) . The ADC values in the ESS group and UM group were compared. The expression levels of proliferating genes and estrogen and progesterone receptors in the ESS group and UM group, and high ADC group and low ADC group were compared. Results (1) ADC value: The ADC value in the ESS group was lower than that in the UM group (P<0.05) . (2) Proliferating genes: The expression levels of Survivin, CyclinD1, Sp1 and Rb genes in the ESS group were higher than those in the UM group (P<0.05) . The expression levels of Survivin, CyclinD1, Sp1 and Rb genes in the high ADC group were lower than those in the low ADC group (P<0.05) . (3) Estrogen and progesterone receptors: The expression level of SULT1E1 receptor in the ESS group was lower than that in the UM group, whereas the expression levels of PRA, PRB, ERα and ERβ receptors were higher than those in the UM group (P<0.05) . The expression level of SULT1E1 receptor in the high ADC group was higher than that in the low ADC group, whereas the expression levels of PRA, PRB, ERα and ERβ receptors were lower than those in the low ADC group (P<0.05) . Conclusion DWI may differentiate benign and malignant lesions of uterus by ADC value. With the increase of malignant ESS malignancy, the ADC value shows a downward trend. Therefore, DWI examination favors accurate evaluation of the degree of ESS malignancy before surgery, so as to guide and develop individualized treatment and intervention protocol in the clinical settings. Key words: Endometrial stromal sarcoma; Magnetic resonance diffusion weighted imaging; Biological behavior; Proliferation gene expression; Estrogen and progesterone receptor expression

Objective Using single direction dispersion breathless DWI, to analyze the value of DWI for vertebral bone marrow infiltration in patients with acute leukemia (AL). Methods Forty-two patients with AL and 15 healthy volunteers received vertebral sagittal DWI with single shot spin-echo echoplan imaging (SS-SE-EPI) sequence( b value ＝ 0,650 s/mm2) at a GE Signa Excite 1. 5 T scanner with 8 channels body coil. DWI for all patients were performed from three directions, including from superior to inferior (S/I), from anterior to posterior (A/P) and from right to left (R/L). The apparent diffusion coefficient (ADC) value was measured on ADC map from each direction using GE-Function tool DWI software. Forty two patients consisted of 13 onset with untreated patients and 29 treated patients (7 nonremission,8 complete remission and 14 consolidation therapy). The ADC values among the three diffusion directions were compared. Analysis of variance and t test were used to compare the ADC values in different AL stages, Pearson correlation analysis was used to analyze the correlation between ADC values and the percentage of bone marrow progenitor cells. Results The ADC values from S/I, A/P and R/L of 362 vertebras in the 57 subjects are (0. 758 ±0. 009) × 10-3 mm2/s, (0. 732 ±0. 009) × 10 -3 mm2/s and (0. 758 ±0. 009) × 10 -3 mm2/s, respectively. There is no statistical significance( F ＝ 2. 958, P ＞ 0. 05 ).The ADC values from S/I of 94 vertebras in 15 healthy volunteers is (0. 697 ± 0. 122) × 10 -3 mm2/s, of 85 vertebras in 13 untreated AL patients is (0. 592 ±0. 071 ) × 10-3mm2/s. There is statistical significance between them ( t ＝ 2. 568, P ＜ 0. 05 ) ; The ADC value of 183 vertebras in 29 treated AL patients [ ( 0. 796 ±0. 225 ) × 10-3mm2/s]is higher than that in untreated patients with statistical significance (t ＝ -1. 332,P ＜0. 05). One hundred and forty vertebras in patients with complete remission and consolidation therapy were [ (0. 786 ±0. 184) × 10-3 mm2/s],and 43 vertebras in patients with non-remission(NR) [ (0. 804 ±0. 327 ) × 10 - 3 mm2/s], there was not statistical significance between them ( t ＝ - 0. 160, P ＞ 0. 05 ). The ADC values from S/I direction of untreated patients showed significant negative correlation with the proportion of the blast cell in the bone marrow ( median value 26. 4％. Min 7.9％, Max 48. 2％ ) ( r ＝- 0. 524, P ＜ 0. 05 ). Conclusions DWI of vertebral bone marrow is isotropy. ADC value is a non-invasive and quantitative index for evaluating the pathogenetic condition of AL. Key words: Leukemia infiltration; Bone marrow; Diffusion magnetic resonance imaging; Spinal diseases

To quantify apparent diffusion coefficient (ADC) changes in fetuses with normal lungs and to determine whether ADC can be used in the assessment of fetal lung development. In 53 pregnancies (20-37th weeks of gestation), we measured ADC on diffusion-weighted imaging (DWI) in the apical, middle, and basal thirds of the right lung. ADCs were correlated with gestational age. Differences between the ADCs were assessed. Fetal lung volumes were measured on T2-weighted sequences and correlated with ADCs and with age. ADCs were 2.13 +/- 0.44 microm(2)/ms (mean +/- SD) in the apex, 1.99 +/- 0.42 microm(2)/ms (mean +/- SD) in the middle third, and 1.91 +/- 0.41 microm(2)/ms (mean +/- SD) in the lung base. Neither the individual ADC values nor average ADC values showed a significant correlation with gestational age or with lung volumes. Average ADCs decreased significantly from the lung apex toward the base. Individual ADCs showed little absolute change and heterogeneity. Lung volumes increased significantly during gestation. We have not been able to identify a pattern of changes in the ADC values that correlate with lung maturation. Furthermore, the individual, gravity-related ADC changes are subject to substantial variability and show nonuniform behavior. ADC can therefore not be used as an indicator of lung maturity.

Although it is recognized that pulmonary hysteresis can influence the effects of positive end-expiratory pressure (PEEP), the extent to which expansion of previously opened (vs. newly opening) peripheral airspaces contribute to increased lung volume is unknown. Following a recruitment maneuver, rats were ventilated with constant tidal volumes and imaged during ascending and descending ramps of PEEP. The authors estimated peripheral airspace dimensions by measuring the apparent diffusion coefficient of He in 10 rats. In a separate group (n = 5) undergoing a similar protocol, the authors used computerized tomography to quantify lung volume. Hysteresis was confirmed by larger end-inspiratory lung volume (mean ± SD; all PEEP levels included): 8.4 ± 2.8 versus 6.8 ± 2.0 ml (P < 0.001) and dynamic compliance: 0.52 ± 0.12 versus 0.42 ± 0.09 ml/cm H2O (P < 0.001) during descending versus ascending PEEP ramps. Apparent diffusion coefficient increased with PEEP, but it was smaller during the descending versus ascending ramps for corresponding levels of PEEP: 0.168 ± 0.019 versus 0.183 ± 0.019 cm/s (P < 0.001). Apparent diffusion coefficient was smaller in the posterior versus anterior lung regions, but the effect of PEEP and hysteresis on apparent diffusion coefficient was greater in the posterior regions. The authors' study results suggest that in healthy lungs, larger lung volumes due to hysteresis are associated with smaller individual airspaces. This may be explained by opening of previously nonaerated peripheral airspaces rather than expansion of those already aerated. Setting PEEP on a descending ramp may minimize distension of individual airspaces.

Objective To evaluate preoperative apparent diffusion coefficient (ADC) and exponential apparent diffusion coefficient (eADC) in diffusion weighted imaging (DWI) on microvascular invasion (MVI) of hepatocellular carcinoma (HCC). Methods We retrospectively reviewed 43 HCC patients with DWI data confirmed by surgery and pathology. ADC and eADC values were measured both in neoplasm and hepatic tissue, the ratio of tumor to liver (T/L) on ADC and eADC was calculated. The correlation between MVI and ADC value, T/L of ADC value, eADC value and T/L of eADC value was analysed, the best cut-off value of variables was analysed by ROC curve, multi factor analysis was carried out by Logistic regression model. Results The ADC value, T/L of ADC, eADC value and T/L of eADC were (1.458±0.444)×10-3mm2/s, 0.787±0.186, 0.289±0.144 and 1.383(1.179, 1.655), respectively. Among them, the positive MVI group were(1.232±0.480)×10-3mm2/s, 0.683±0.229, 0.323±0.123 and 1.630(1.387, 2.066), respectively. The negative MVI group were(1.545±0.404)×10-3mm2/s, 0.844±0.149, 0.277±0.152 and 1.303(1.176, 1.545), respectively. There was significant difference in ADC value, T/L of ADC value and T/L of eADC value (t=2.164, 2.654, z=-2.058, all P<0.05), the area under the ROC curve were (1.085×10-3) mm2/s, 0.685 and 1.475 using MVI as a diagnostic standard. Multivariate analysis showed that T/L of ADC value was an independent factor affecting MVI of HCC (OR=0.002, 95%CI: 1.380E-5-0.311, P<0.05). Conclusions The ADC value in HCC patients with positive MVI is lower than in HCC patients with negative MVI, T/L of eADC value is higher than in HCC patients with negative MVI, and T/L of ADC value is an independent factor predicticing MVI of HCC. Key words: Carcinoma, hepatocellular; Microvessels; Diffusion magnetic resonance imaging

Objective To explore the feasibility of diffusion weighted imaging(DWI) based on intravoxel incoherent motion(IVIM) in the diagnosis of compressed lumbosacral nerve roots. Methods The prospective study was conducted. A total of 60 images were collected and analyzed in this study, 30 of which were from the observation group. Routine lumbar MR sequences, 3D-fiesta sequences and IVIM-DWI sequences of patients with lumbar disc herniation caused nerve root compression in Affiliated Hospital of Taishan Medical College from April 2017 to October 2017. Thirty healthy volunteers were selected as the control group, their ages and sexes matched with those of observation group. At GE ADW 4.6 workstation, MADC software package was used to measure the slow diffusion coefficient(D), fast diffusion coefficient(D*), apparent diffusion coefficient(ADC), fraction of fast ADC(f) values of bilateral L4, L5 and S1 ganglia of control group, and the D, D*, f and ADC values of compressed side and opposite nerve roots of observation group were measured. The measured values of left and right ganglion and different ganglion of the same segment in control group were compared. The measured values of the compressed side nerve roots in the observation group were compared with the measured values of the normal nerve roots in the opposite side, to see whether the differences between the values were statistically significant. Results The D values of nerve roots of L4, L5 and S1 in control group were (0.603±0.064)×10-3 mm2/s, (0.624±0.079)×10-3 mm2/s, (0.628±0.088) ×10-3 mm2/s, respectively. The D* values were (3.815±0.541) ×10-3, (3.862±0.414) ×10-3, (3.915±0.611) ×10-3, respectively, in mm2/s. The f values were 0.454%±0.076%, 0.484%±0.101% and 0.445%±0.094%, respectively. The ADC values were (0.934±0.085) ×10-3, (0.945±0.051) ×10-3, (0.953±0.064) ×10-3, respectively, in mm2/s.The values of D, D*, f and ADC on the compression side of nerve root in observation group were (0.669±0.081) ×10-3 mm2/s, (3.852±0.776)×10-3 mm2/s, 0.528%±0.115%, (1.096±0.087) ×10-3 mm2/s, and the values of D, D*, f and ADC on the healthy side were (0.617±0.080) ×10-3 mm2/s, (3.961±0.684) ×10-3 mm2/s, 0.479%±0.083%, (0.938±0.074)×10-3 mm2/s, respectively. The values of D, D*, f and ADC measured by the left and right ganglion of the same segment and the ganglion of different segments were not statistically significant(all P values>0.05). Compared with the normal nerve roots on the opposite side, the values of D and ADC were both increased, the difference was statistically significant(all P values 0.05). ROC curve was drawn and analyzed, and D value was highly effective in diagnosing nerve root compression, followed by ADC value, The AUC of D value was 0.923(95%CI 0.803-0.987), and the AUC of ADC value was 0.895 (95%CI 0.865-0.999). Conclusions The diffusion-weighted imaging technique of IVIM model can be used for lumbosacral nerve root examination.Compared with the diffusion-weighted imaging technique of single exponential model, it can reflect the pathological changes after nerve root compression in more details and accurately. Key words: Magnetic resonance imaging; Radiculopathy; Lumbosacral nerve root; Intravoxel incoherent motion; Diffusion weighted imaging

To evaluate the role and the performance of diffusion weighted imaging (DWI) for predicting the early response to neoadjuvant chemotherapy (NAC) in local advanced breast cancer (LABC) and to assess the accuracy of DWI in evaluating residual lesion after NAC. 88 women with LABC (89 lesions) underwent DWI before and after the first and final cycle of NAC. For each patient, the apparent diffusion coefficient (ADC) values were compared between the baseline and follow-up to predict the early response to NAC. The residual tumor volumes were obtained using 3D maximum intensity projections (MIP) of DWI map, and were compared with pathological findings to assess the accuracy of DWI in detecting and measuring residual tumor. All results were proved or analyzed comparing with the data from histopathology. There were 68 lesions responding to NAC, while 21 non-responders. The baseline ADC values of responders and non-responders were (1.049 +/- 0.135) x 10(-3) mm(2)/s and (1.171 +/- 0.134) x 10(-3)mm(2)/s, respectively, with a significant difference (t = -2.731, P = 0.009 < 0.01). The ADC value measured prior to treatment was (1.087 +/- 0.146) x 10(-3)mm(2)/s, and the degree of the changes in tumor volume after NAC was (70.4% +/- 55.1)%. A negative correlation was observed (r = -0.430, P = 0.025 < 0.05). In the response group, there was a significant difference in ADC value between prior to NAC and 1st cycle of NAC, the final cycle of NAC, respectively (P < 0.001). While no significant differences were found in non-responders during NAC (P > 0.05). The tumor volume correlation coefficient between DWI and pathology measurements was very high (r = 0.749, P < 0.01). DWI appears to provide functional information regarding changes in ADC value of tumors due to NAC. DWI may be useful in monitoring the early pathological response of tumor after the initiation of treatment and in evaluating the residual tumor after NAC.

Objective To investigate the relationship between apparent diffusion coefficient (ADC) values and histopathological grading of cerebral gliomas. Methods A retrospective analysis was performed to investigate the clinical data of 76 patients with cerebral gliomas, admitted to our hospital from April 2013 to December 2016. According to Classification Criteria of Central Nervous System Tumors by WHO in 2016, these 76 patients were divided into low grade cerebral glioma group (grading I-II, n=21), moderate grade cerebral glioma group (grading III, n=23) and high grade cerebral glioma group (grading IV, n=32). MR imaging, enhanced MR imaging and diffusion weighted imaging (3.0T, b value: 1000 s/mm2) were performed to detect the ADC values. One-way ANOVA was used to compare ADC values between the 3 different histopathological groups. Spearman correlation analysis was used to analyze the correlation between histopathological grading of cerebral gliomas and ADC values. A receiver operating characteristic curve (ROC) analysis was performed to evaluate the diagnostic efficiency of ADC values. Results The ADC values of low grade, moderate grade and high grade cerebral gliomas were (1.37±0.26)×10-3 mm2/s, (0.97±0.11)×10-3 mm2/s, (0.75±0.13)×10-3 mm2/s, respectively; statistically significant differences were observed between each two groups (P<0.05). There was a negative correlation between ADC values and histopathological grading of cerebral gliomas (r=-0.868, P=0.000). ROC analysis showed that the optimal cutoff point of ADC values was 1.11×10-3 mm2/s in diagnosing low grade cerebral gliomas, enjoying sensitivity and specificity of differential diagnosis of 95.2% and 96.4%; ROC curve showed that the optimal cutoff point of ADC values was 0.93×10-3 mm2/s in diagnosing high cerebral gliomas, enjoying sensitivity and specificity of differential diagnosis of 81.8% and 93.7%. Conclusion ADC values are important for predicting histopathological grading of cerebral gliomas. Key words: Cerebral glioma; Apparent diffusion coefficient; Magnetic resonance imaging; Diffusion magnetic resonance imaging; Pathology

To analyze the relationship between gestational age and apparent diffusion coefficient (ADC) values in different regions of fetal brain from middle to late trimester. DW images performed in 70 singleton non-sedated fetuses with questionably abnormal results on sonography and normal fetal MR imaging results were retrospectively reviewed. The median gestational age was 32.4 weeks (range, 24-38).With the formula of ADC = ln (S600/S0)/(B0-B600), the mean ADC values were obtained for fetal parietal white matter (WM), frontal WM, temporal WM, occipital WM, pons, cerebellum, basal ganglia and thalamus. The relationship of mean ADC values in different regions with gestational age was analyzed with linear regression. The mean ADC values were 1.77 ± 0.32 mm(2)/s (SD) in fetal parietal white matter (WM), 1.71 ± 0.32 mm(2)/s in occipital WM, 1.31 ± 0.18 mm(2)/s in thalamus, 1.34 ± 0.15 mm(2)/s in basal ganglia. And the mean ADC values in cerebellum, pons, frontal WM and temporal WM were 1.17 ± 0.16, 1.41 ± 0.18, 1.87 ± 0.18 and 1.74 ± 0.19 mm(2)/s respectively. A significant negative correlation between ADC values and gestational age was found for parietal WM, occipital WM, pons, cerebellum, basal ganglia and thalamus (P < 0.05). Frontal WM ADC (P > 0.05) and temporal WM ADC (P = 0.05) did not significantly change with gestational age whereas only a downward trend was present. The correlation coefficient (r) and coefficient of regression (b) were 0.420 and -0.045 in parietal WM; 0.470 and -0.052 in occipital WM; 0.370 and -0.027 in cerebellum; 0.027 and -0.020 in pons; 0.320 and -0.027 in thalamus; 0.300 and -0.021 in basal ganglia. The mean ADC values peaked in frontal WM and lowest in pons. The mean ADC values in white matter were higher than those in deep gray nuclei, cerebellum and pons.With the development of fetal brain,ADC values declined the fastest in cerebellum and occipital WM, followed by basal ganglia and thalamus. Regional differences in non-sedated fetal brain ADC values and their evolutions with gestational age are likely to reflect variations in brain maturation.