Chronic hepatitis: role of diffusion-weighted imaging and diffusion tensor imaging for the diagnosis of liver fibrosis and inflammation

PURPOSE: To determine the diagnostic performance of liver apparent diffusion coefficient (ADC) measured with conventional diffusion-weighted imaging (CDI) and diffusion tensor imaging (DTI) for the diagnosis of liver fibrosis and inflammation. MATERIALS AND METHODS: Breathhold single-shot echo-planar imaging CDI and DTI with b-values of 0 and 500 second/mm(2) was performed in 31 patients with chronic liver disease and 13 normal volunteers. Liver biopsy was performed in all patients with liver disease with a median delay of two days from MRI. Fibrosis and inflammation were scored on a 5-point scale (0-4). Liver ADCs obtained with CDI and DTI were compared between patients stratified by fibrosis stage and inflammation grade. Receiver operating characteristic (ROC) curve analyses were conducted to evaluate the utility of the ADC measures for prediction of fibrosis and inflammation. RESULTS: Patients with liver fibrosis and inflammation had significantly lower liver ADC than subjects without fibrosis or inflammation with CDI and DTI. For prediction of fibrosis stage > or = 1 and stage > or = 2, area under the ROC curve (AUC) of 0.848 and 0.783, sensitivity of 88.5% to 73.7%, and specificity of 73.3% to 72.7% were obtained, for ADC < or =1.40 x 10(-3) mm(2)/second and < or =1.30 x 10(-3) mm(2)/second (using CDI), respectively. For prediction of inflammation grade > or = 1, AUC of 0.825, sensitivity of 75.0%, and specificity of 78.6% were obtained using ADC < or = 1.30 x 10(-3) mm(2)/second (using CDI). CDI performed better than DTI for diagnosis of fibrosis and inflammation. CONCLUSION: Liver ADC can be used to predict liver fibrosis and inflammation with acceptable sensitivity and specificity.     

Comparison of the diagnostic performances of diffusion parameters in diffusion weighted imaging and diffusion tensor imaging of breast lesions

Purpose

To evaluate the diagnostic efficiency of the diffusion parameters measured by conventional diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) for discrimination of malignant breast lesions from benign lesions and the normal breast.

Materials and methods

The study included 52 women with 55 breast lesions (30 malignant, 25 benign). DTI and DWI were performed complementary to dynamic contrast MRI at 3T. Apparent diffusion coefficient (ADC) of DWI, mean diffusivity (MD) and fractional anisotropy (FA) values of DTI were measured for lesions and contralateral breast parenchyma in each patient. We used b factors of 0, 50, 850, 1000 and 1500 s/mm² for DWI and b 0 and 1000 s/mm² for DTI. ADC, MD and FA values were compared between malignant and benign lesions, and the normal parenchyma by univariate and multivariate analyses.

Results

Diffusion parameters showed no difference according to menopausal status in the normal breast. ADC and MD values of the malignant lesions were significantly lower than benign lesions and normal parenchyma (p = 0.001). The FA showed no statistical significance. With the cut-off values of ≤1.23 × 10⁻³ mm²/s (b 0–1000 s/mm²) and ≤1.12 × 10⁻³ mm²/s (b 0–1500 s/mm²), ADC showed 92.85% and 96.15% sensitivity; 72.22% and 73.52% PPV, respectively. With a cut-off value of ≤1.27 × 10⁻³ mm²/s (b 1000 s/mm²), MD was 100% sensitive with a PPV of 65.90%. Comparing the diagnostic performance of the parameters in DTI with DWI, we obtained similar efficiency of ADC with b values of 0,1000 and 0,1500 s/mm² and MD with a b value of 0, 1000 s/mm² (AUC = 0.82 ± 0.07).

Conclusion

ADC of DWI and MD of DTI values provide significant discriminative factors for benign and malignant breast lesions. FA measurement was not discriminative. Supported with clinical and dynamic contrast MRI findings, DWI and DTI findings provide significant contribution to the final radiologic decision.     

High-resolution diffusion tensor imaging of prostate cancer using a reduced FOV technique

Objective

Diffusion tensor imaging (DTI) offers the promise of improved tumor localization in prostate cancer but the technique suffers from susceptibility-induced artifacts that limit the achievable resolution. The present work employs a reduced field-of-view technique that enables high-resolution DTI of the prostate at 3 T. Feasibility of the approach is demonstrated in a clinical study including 26 patients and 14 controls.

Materials and methods

Reduced field-of-view acquisition was established by non-coplanar application of the excitation and the refocusing pulse in conjunction with outer volume suppression. Accuracy for cancer detection of apparent diffusion coefficient (ADC) mapping and T₂-weighted imaging was calculated and compared with reference to the findings of trans-rectal ultrasound-guided octant biopsy. Mean ADCs and fractional anisotropy (FA) values in the patients with positive and negative biopsies were compared to each other and to the controls.

Results

Fine anatomical details were successfully depicted on the ADC maps with sub-millimeter resolution. Accuracy for prostate cancer detection was 73.5% for ADC maps and 71% for T₂-weighted images, respectively. Cohen's kappa (κ = 0.48) indicated moderate agreement of the two methods. The mean ADCs were significantly lower, the FA values higher, in the patients with positive biopsy than in the patients with negative biopsy and the controls. Monte Carlo simulations showed that the FA values, but not the ADCs, were slightly overestimated. Bootstrap analysis revealed that the ADC, but not the FA value, is a highly repeatable marker.

Conclusion

In conclusion, the present work introduces a new approach for high-resolution DTI of the prostate enabling a more accurate detection of focal tumors especially useful in screening populations or as a potential navigator for image-guided biopsy.     

Diagnosis and quantification of hepatic fibrosis in children with diffusion weighted MR imaging

Purpose

To evaluate the accuracy of diffusion weighted MR imaging in diagnosis and quantification of hepatic fibrosis in children with chronic hepatitis.

Materials and methods

Sixty-three consecutive children (40 boys, 23 girls, median age 9.3 years), with chronic hepatitis and thirty age matched volunteers underwent diffusion weighted MR imaging of the liver using a single shot echoplanar imaging with b-value = 0, 250, and 500 s/mm². Liver biopsy was obtained with calculation of METAVIR score. The ADC value of the liver was correlated with METAVIR score. Receiver operating characteristic curve was done for diagnosis and grading of hepatic fibrosis.

Results

There was statistical difference in the mean ADC value between volunteers and patients with hepatic fibrosis (P = 0.001) and in patients with different grades of METAVIR scores (P = 0.002). There was correlation between the mean ADC value and METAVIR score (r = 0.807, P = 0.001). The cut off point to predict fibrosis (1.7 × 10⁻³ mm²/s) revealed 83% accuracy, 85% sensitivity, 82% specificity, 83% PPV, and 85% NPV. The area under the curve was 0.91 for F1, 0.85 for F2, 0.86 for F3 and 0.90 for F4.

Conclusion

The apparent diffusion coefficient value is a promising quantitative parameter used for diagnosis and quantification of hepatic fibrosis in children with chronic hepatitis.     

Apparent diffusion coefficient (ADC) in liver fibrosis: Usefulness of normalized ADC using the spleen as reference organ

Objective

The purpose of the current study was to determine the usefulness of the usage of the spleen as a reference organ to normalize liver ADC to improve the diagnostic performance of diffusion weighted imaging (DWI) for assessing liver fibrosis.

Materials and methods

Forty-nine subjects, 34 patients with liver disease and 15 control subjects were assessed with diffusion-weighted imaging. Liver ADC and normalized liver ADC (defined as the ratio of liver ADC to spleen ADC) were compared between patients and the control groups as well as among patients with different stages of fibrosis. Receiver operating characteristic (ROC) analysis was used to determine the performance of ADC and normalized liver ADC for prediction of liver fibrosis and cirrhosis.

Results

There was no significant difference between spleen ADC values among patients in comparison to control (1.107 ± 0.07 × 10⁻³mm²/s vs. 1.12 ± 0.068 × 10⁻³mm²/s, p = 0.998) or among patients with different stages of fibrosis (p = 0.59–0.89). The mean liver ADC and mean normalized liver ADC values were significantly lower in patients with hepatic fibrosis compared to volunteers (P = 0.01,<0.001 respectively), however liver ADC could not significantly differentiate different stages of fibrosis except between stages 0 and 4. The mean normalized liver ADC was significantly different between stage 0 and stages 2, 3, and 4 as well as between stage 1 and stage 4. In addition, it had a trend toward significance between stage 0 and 1, stage 2 and 4 as well as stage 3 and 4. Both liver ADC and normalized liver ADC had a significant negative correlation with the grade of fibrosis, however it was more powerful for normalized liver ADC in comparison to liver ADC (r = −0.694 vs. −0.361, p = 0.01 vs. 0.05). ROC analysis showed higher performance using normalized liver ADC in comparison to liver ADC, with higher AUC, sensitivity, and specificity for detection of fibrotic stages ?2 (0.88, 92.5% and 76.2% Vs 0.72, 82.1%, and 57.1% respectively). The corresponding values for stages ?3 were 0.83, 100%, and 55% vs. 0.69, 77.3%, and 44.4% respectively), while the corresponding values for cirrhosis (stage 4) were 0.87, 81.8%, and 81.8% for normalized liver ADC vs. 0.74, 69.2%, 72.2%.for ADC liver.

Conclusion

The utility of using the spleen as a reference organ could improve the diagnostic performance of ADC measurement for the diagnosis of liver fibrosis. The application of this technique for the evaluation of liver fibrosis is promising.     

Diffusion weighted MRI and transient elastography assessment of liver fibrosis in hepatitis C patients: Validity of non invasive imaging techniques

Objective

Treatment for hepatitis C infection and monitoring of progression were based on degree of fibrosis, which were traditionally diagnosed by liver biopsy but it has many limitations. We aim to evaluate noninvasive imaging methods, so-called diffusion-weighted MRI (DW MRI) and transient elastography [(TE), fibroscan] in diagnosing liver fibrosis in hepatitis C (HCV) patients.

Patients

The Study included 102 hepatitis C patients (62 male) with mean age of 38 ± 5. For all patients liver biopsy was done followed by DW MRI and TE. METAVIR classification system was used for staging liver fibrosis. Data obtained were collected and results of DW MRI and TE were compared with those of histopathology. The diagnostic performance of ADC and TE was determined using areas under receiver operating characteristic (AUROC) curves for significant fibrosis ?F3.

Results

Measuring ADC at different b-values had a significant negative correlation with stage of fibrosis P = 0.001, the best negative correlation at b-value of 700 mm²/s. TE had a significant positive correlation with stage of fibrosis P = 0.005. Both examination showed a significant difference between fibrosis stage <F3 and stages ?F3 with P < 0.00 for ADC measure at each b-value and TE respectively.

Conclusion

This study suggests that DW MRI and TE had favorable comparable results with liver biopsy for the diagnosis of significant liver fibrosis.     

Diffusion-weighted MRI for evaluating perianal fistula activity: Feasibility study

Purpose

To assess the feasibility of using diffusion-weighted magnetic resonance (MR) imaging (DWI) for evaluating perianal fistula activity.

Materials and methods

This study retrospectively assessed 24 patients with clinically suspected perianal fistula who underwent a total of 28 MR examinations after conservative treatment with antibiotics. DWI was performed at 1.5 T, using b-values of 0 and 1000s/mm². Apparent diffusion coefficient (ADC) maps were created and ADCs of the lesions were measured. Lesions were classified into two groups based on the need for surgery and surgical findings: positive inflammation activity (PIA) and negative inflammation activity (NIA). ADCs of both groups were compared using an unpaired t-test, and Receiver Operating Characteristic (ROC) analysis was performed.

Results

The ADC (in 10⁻³ mm²/s) of the PIA group (0.908 ± 0.171) was significantly lower (P = 0.0019) than that of the NIA group (1.124 ± 0.244). The area under the ROC curve was 0.749. An optimal cut-off ADC of 1.109 yielded a sensitivity of 95.7%, a specificity of 50%, a positive predictive value of 71%, and a negative predictive value of 90%.

Conclusion

DWI is a feasible method for evaluating perianal fistula activity. The diagnostic performance of this technique should be established in future, larger prospective studies.     

Diffusion tensor imaging of the median nerve at 3.0 T using different MR scanners: Agreement of FA and ADC measurements

Objective

To assess the agreement of fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values of the median nerve on 3.0 T MR scanners from different vendors.

Materials and methods

IRB approved study including 16 healthy volunteers (9 women; mean age 30.6 ± 5.3 years). Diffusion tensor imaging (DTI) of the dominant wrist was performed on three 3.0 T MR scanners (GE, Siemens, Philips) using similar imaging protocols and vendor-proprietary hard- and software. Intra-, inter-reader and inter-vendor agreements were assessed.

Results

ICCs for intra-/inter-reader agreements ranged from 0.843–0.970/0.846–0.956 for FA, and 0.840–0.940/0.726–0.929 for ADC, respectively.ANOVA analysis identified significant differences for FA/ADC measurements among vendors (p < 0.001/p < 0.01, respectively). Overall mean values for FA were 0.63 (SD ± 0.1) and 0.999 × 10⁻³ mm²/s (SD ± 0.134 × 10⁻³) for ADC. A significant negative measurement bias was found for FA values from the GE scanner (−0.05 and −0.07) and for ADC values from the Siemens scanner (−0.053 and −0.063 × 10⁻³ mm²/s) as compared to the remainder vendors

Conclusion

FA and ADC values of the median nerve obtained on different 3.0 T MR scanners differ significantly, but are in comparison to the standard deviation of absolute values small enough to not have an impact on larger group studies or when substantial diffusion changes can be expected. However, caution is warranted in an individual patient when interpreting diffusion values from different scanner acquisitions     

Diffusion weighted MRI in chronic viral hepatitis C: Correlation between apparent diffusion coefficient values and histopathological scores

Aim of the work

To assess the utility of hepatic ADC of diffusion weighted MRI in the diagnosis of liver fibrosis in chronic hepatitis C patients and to evaluate its relationship with both the stage of liver fibrosis and grade of necro-inflammation.

Subjects and methods

Forty patients with chronic viral hepatitis C and 30 healthy control group were examined by 1.5 T MRI scanner using DWI at b-values of 100, 400 and 800 s/mm². The mean ADC values of both patients and the control group were correlated to biopsy findings and graded according to METAVIR scoring system.

Results

The mean ADC values of the liver at all b-values were statistically significantly lower in the study group than those of the control group. A strong negative correlation was found between the mean ADC value and the stage of fibrosis. No significant correlation was found between the mean ADC value and the grade of necroinflammation.

Conclusion

The ADC value of diffusion weighted MRI can be used to distinguish between liver parenchyma of patients with chronic viral hepatitis C and healthy subjects and it is useful for estimation of the stage of liver fibrosis but not valuable in estimation of the grade of necro-inflammation.     

The role of MR diffusion in differentiation of malignant and benign hepatic focal lesions

Aim

To determine if focal liver masses could be differentiated as benign or malignant by DWI and ADC maps.

Methods and materials

Sixty focal liver lesions were scanned using 1.5 T MRI. DWI was performed with b 0, b 500 and b 1000 gradients with ADC measurements. Comparison of mean ADC values between each benign and malignant lesion was done. Reference standard of diagnosis was obtained by correlating DWI with histopathologic findings and imaging follow-up. The accuracies of DWI and ADC values were assessed with the Student’s t test, and cut-off values were determined with receiver operating characteristic curve analysis.

Results

When ADC value of 1.0 × 10⁻³ mm²/s was used as a threshold value for differentiation of malignant tumors from benign lesions, sensitivity was 90.3%, specificity 78.57% and accuracy 86.7%. The best result was obtained with the use of ADC cut off value (at b 500) of 1.5 × 10⁻³ mm²/s and ADC cut off value (at b 1000) of 1.0 × 10⁻³ mm²/s, with 90.3% sensitivity, 92.86% specificity, 91.1% accuracy, 96.6% positive predictive value and 81.3% negative predictive value.

Conclusion

DWI and ADC map is a useful tool in differential diagnosis of malignant from benign liver lesions.     

Magnetic resonance perfusion and diffusion imaging characteristics of transient bone marrow edema,avascular necrosis and subchondral insufficiency fractures of the proximal femur

Purpose

To evaluate magnetic resonance (MR) perfusion and diffusion imaging characteristics in patients with transient bone marrow edema (TBME), avascular necrosis (AVN), or subchondral insufficiency fractures (SIF) of the proximal femur.

Materials and methods

29 patients with painful hip and bone marrow edema pattern of the proximal femur on non-contrast MR imaging were examined using diffusion-weighted and dynamic gadolinium-enhanced sequences. Apparent diffusion coefficients (ADCs) and perfusion parameters were calculated for different regions of the proximal femur. Regional distribution and differences in ADC values and perfusion parameters were evaluated.

Results

Seven patients presented with TBME, 15 with AVN and seven with SIF of the proximal femur. Perfusion imaging showed significant differences for maximum enhancement values (E_max), slope (E_slope) and time to peak (TTP) between the three patient groups (p < 0.05). In contrast, no significant differences for ADC values were calculated when comparing TBME, AVN, and SIF patients.

Conclusion

Diffusion weighted imaging of bone marrow of the proximal femur did not show significant differences between patients with TBME, AVN or SIF. In contrast, MR perfusion imaging demonstrated significant differences for the different patient groups and may as a complementary imaging technique add information to the understanding of the pathophysiology of diseases associated with bone marrow edema.     

Glaucoma severity affects diffusion tensor imaging (DTI) parameters of the optic nerve and optic radiation

Objectives

To evaluate whether MR diffusion tensor imaging (DTI) of the optic nerve and optic radiation in glaucoma patients provides parameters to discriminate between mild and severe glaucoma and to determine whether DTI derived indices correlate with retinal nerve fibre layer (RNFL) thickness.

Methods

3-Tesla DTI was performed on 90 subjects (30 normal, 30 mild glaucoma and 30 severe glaucoma subjects) and the FA and MD of the optic nerve and optic radiation were measured. The categorisation into mild and severe glaucoma was done using the Hodapp–Parrish–Anderson (HPA) classification. RNFL thickness was also assessed on all subjects using OCT. Receiver operating characteristic (ROC) analysis and Spearman's correlation coefficient was carried out.

Results

FA and MD values in the optic nerve and optic radiation decreased and increased respectively as the disease progressed. FA at the optic nerve had the highest sensitivity (87%) and specificity (80%). FA values displayed the strongest correlation with RNFL thickness in the optic nerve (r = 0.684, p ≤ 0.001) while MD at the optic radiation showed the weakest correlation with RNFL thickness (r = −0.360, p ≤ 0.001).

Conclusions

The high sensitivity and specificity of DTI-derived FA values in the optic nerve and the strong correlation between DTI-FA and RNFL thickness suggest that these parameters could serve as indicators of disease severity.     

Role of diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) in differentiating between benign and malignant breast lesions

Objective

To assess the role of DWI and ADC in differentiating between benign and malignant breast lesions.

Materials and methods

51 patients (age range 24–66 years; mean age 48 years) were included in our study. MRI was done using bilateral fat-suppressed T2- weighted fast spin-echo, STIR, axial T1-weighted fast spin-echo. DWI series were acquired using echo planar imaging pulse sequences incorporated with diffusion gradients and finally dynamic contrast enhancement study was done.

Results

Sixty three lesions were detected in 51 patients included in our study. Twenty one lesions were malignant, three lesions were intermediate and twenty two lesions were fibroadenoma according to the final histopathological study and seventeen lesions were breast cysts. A total of 21 lesions showed lower ADC values than benign lesions and were in the range of 0.76–1.29 × 10⁻³ mm²/s and were diagnosed as malignant breast lesions. The sensitivity and specificity for DWI in the differentiating malignant from benign breast lesions were calculated and showed 95.4% and 97.5%, respectively.

Conclusion

DWI is easy to obtain in short scan time and easy to evaluate, and ADC values can differentiate between benign and malignant breast lesions with high sensitivity and specificity.     

Assessment of liver tumor response by high-field (3T) MRI after radiofrequency ablation: Short- and mid-term evolution of diffusion parameters within the ablation zone

Purpose

To compare the apparent diffusion coefficient (ADC) values of malignant liver lesions on diffusion-weighted MRI (DWI) before and after successful radiofrequency ablation (RF ablation).

Materials and methods

Thirty-two patients with 43 malignant liver lesions (23/20: metastases/hepatocellular carcinomas (HCC)) underwent liver MRI (3.0 T) before (<1 month) and after RF ablation (at 1, 3 and 6 months) using T2-, gadolinium-enhanced T1- and DWI-weighted MR sequences. Jointly, two radiologists prospectively measured ADCs for each lesion by means of two different regions of interest (ROIs), first including the whole lesion and secondly the area with the visibly most restricted diffusion (MRDA) on ADC map. Changes of ADCs were evaluated with ANOVA and Dunnett tests.

Results

Thirty-one patients were successfully treated, while one patient was excluded due to focal recurrence. In metastases (n = 22), the ADC in the whole lesion and in MRDA showed an up-and-down evolution. In HCC (n = 20), the evolution of ADC was more complex, but with significantly higher values (p = 0.013) at 1 and 6 months after RF ablation.

Conclusion

The ADC values of malignant liver lesions successfully treated by RF ablation show a predictable evolution and may help radiologists to monitor tumor response after treatment.     

Cerebral diffusion tensor imaging in tuberous sclerosis

Purpose

The purpose of this study was to investigate the features of the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) in cortical tubers and white-matter lesions in patients with tuberous sclerosis (TS) using diffusion tensor imaging (DTI).

Materials and methods

Conventional magnetic resonance imaging (MRI) and DTI were performed in 14 patients with clinically established TS. Based on these DT images, ADC and FA maps were generated. The ADC values in 32 cortical tubers, and the ADC and FA values in 18 white-matter lesions were measured and compared with those of the corresponding contralateral regions.

Results

Compared with the corresponding contralateral regions, cortical tubers of TS patients had significantly higher ADC values (P < 0.001); white-matter lesions had significantly higher ADC values (P < 0.001) and significantly lower FA values (P < 0.001).

Conclusion

DTI is a useful tool for demonstrating changes in cortical tubers and white-matter lesions resulting from TS.     

Apparent diffusion coefficient of renal parenchyma and color Doppler ultrasound of intrarenal arteries in patients with cirrhosis related renal dysfunction

Objectives

The aim of this work was to study the renal hemodynamic changes which occur with liver cirrhosis using diffusion weighted magnetic resonance imaging (DW-MRI) and renal color duplex Doppler ultrasound.

Patients and methods

Patients were divided into four groups: Group A: 15 cirrhotic patients with compensated liver cirrhosis, Group B: 15 cirrhotic patients with refractory ascites, Group C: 15 cirrhotic patients with hepatorenal syndrome, Group D: 10 healthy persons as a control. The apparent diffusion coefficient (ADCs) of the kidneys was calculated using low b values (ADC_low) and high b values (ADC_high). Color Doppler ultrasound was performed in interlobar and arcuate arteries to calculate resistive index (RI) and pulsatility index (PI) in all patients.

Results

ADC_low showed a statistically significant difference between patients with hepatorenal syndrome and other groups. Using ADC_high no significant difference between different groups was noted. RI and PI of both interlobar and arcuate arteries were significantly higher in all the patient groups than the control group (P < 0.0001). RI and PI of both interlobar and arcuate arteries were significantly higher in patients with hepatorenal syndrome.

Conclusion

Liver cirrhosis, even in the presence of refractory ascites, did not affect the ADC value of renal parenchyma, however ADC value is affected in renal parenchyma of patients with hepato-renal syndrome. Duplex-Doppler ultrasound of intrarenal arteries enables the early detection of renal hemodynamic disturbances in patients with liver cirrhosis.     

Diffusion-weighted imaging in assessing renal pathology of chronic kidney disease: A preliminary clinical study

Objective

To investigate the clinical potential of diffusion-weighted imaging (DWI) in assessing renal pathology of chronic kidney disease (CKD).

Methods

Seventy-one CKD patients and twelve healthy volunteers were examined using DWI with prospective acquisition correction. Renal biopsy specimens from the CKD patients were scored based on the severity of renal pathology and to confirm pathology type. CKD patients were divided into three groups according to pathology scores: mild, moderate, or severe. The association between renal apparent diffusion coefficient (ADC) values and pathology scores was investigated using Pearson's correlation and single factor analysis of variance. Multiple linear regression analysis was performed to explore associations between renal ADC values and pathology score, glomerular filtration rate, serum creatinine, and age. The Kruskal–Wallis H test was conducted to compare ADC values and pathology type.

Results

Renal ADC values correlated negatively with pathology scores (r = −0.633, P < 0.001). The ADC values among the four groups (mild, moderate, severe impairment, and controls) were significantly different (F = 19.512, P < 0.001). However, when patients were stratified by pathology type, no significant differences were found in ADC values among these groups (χ² = 9.929, P = 0.270). Further multiple linear regression analysis showed that only the pathology score and ADC values were related (t = −4.586, P = 0.000).

Conclusions

DWI has clinical potential in assessing the severity of renal pathology in CKD and shows promise as a non-invasive and effective technique to guide therapy and follow-up.     

Potential of diffusion tensor MR imaging in the assessment of cognitive impairments in children with periventricular leukomalacia born preterm

Purpose

To investigate MR diffusion tensor imaging (DTI) and fiber tractography (FT) in the assessment of altered major white matter fibers correlated with cognitive functions in preterm infants with periventricular leukomalacia (PVL), to explore the neural foundation for PVL children's cognitive impairments.

Materials and methods

Forty six preterm infants (16 ± 4.7 months) suffered from PVL and 16 age-matched normal controls were recruited. Developmental quotient (DQ) was recorded to evaluate PVL children's cognitive functions. According to the DQ scores, patients were divided into three groups: mild, moderate and severe cognitive impairment groups. DTI scan was performed. Fractional anisotropy (FA) values of major white matter fibers were measured and their correlation with cognitive levels was evaluated.

Results

Compared with the control group, the PVL group showed a significant mean FA reduction in bilateral corticospinal tract (CST), anterior/posterior limb of internal capsule (ICAL/ICPL), arcuate fasciculus (AF), corona radiate (CR), superior longitudinal fasciculus (SLF), splenium of corpus callosum (SCC) (p < 0.05) and bilateral posterior thalamic radiation (PTR) (p < 0.01). The FA values of left CST, bilateral AF, anterior cingulum (ACG), SLF, ICAL, ICPL, PTR, CR, genu of corpus callosum (GCC), SCC and middle cerebellar peduncle showed significant negative correlations with the cognitive levels.

Conclusions

DTI can provide more information for understanding the pathophysiology of cognitive impairment in preterm infants with PVL.     

Differentiation of intracranial tuberculomas and high grade gliomas using proton MR spectroscopy and diffusion MR imaging

Objective

The purpose of this study was to determine whether proton MR spectroscopy (¹H MRS) and diffusion-weighted (DW) imaging can be used to differentiate intracranial tuberculomas from high grade gliomas (HGGs).

Materials and methods

A total of 41 patients (19 with intracranial tuberculomas and 22 with HGGs) were examined in our study. ¹H MRS and DW imaging were performed at a 1.5T MR scanner before operation or treatment. Concentrations of N-acetylaspartate (NAA), creatine (Cr), choline (Cho), and lipid and lactate (LL) in the contrast-enhancing rim of each lesion were expressed as metabolite ratios and were normalized to the contralateral hemisphere. The apparent diffusion coefficient (ADC) was also calculated. The metabolite ratios and ADC values in the enhancing rim of intracranial tuberculomas and HGGs were compared using the Wilcoxon rank sum test. Diagnostic accuracy was compared using receiver operating characteristic (ROC) analysis.

Results

Significant differences were found in the maximum Cho/Cr (P = 0.015), Cho/NAA (P = 0.001) and Cho/Cho-n ratios (P = 0.002), and minimum ADC value (P < 0.001) between the intracranial tuberculomas and HGGs. Diagnostic accuracy was higher by minimum ADC value than maximum Cho/Cr, Cho/NAA and Cho/Cho-n ratios (93.8% versus 75.7%, 80.8% and 78.1%).

Conclusion

These results suggest a promising role for ¹H MRS and DW imaging in the differentiation between the intracranial tuberculomas and HGGs.     

Evaluation of liver hemangiomas using three different b values on diffusion MR

Purpose

To determine which diffusion-weighted MR technique (i.e., b-100, b-600, b-1000 s/mm²) is most useful in depicting liver hemangiomas. We also aimed to assess the effect of lesion size on apparent diffusion coefficient (ADC) values.

Materials and methods

Diffusion-weighed MR (DWMR) was performed for 61 hemangiomas in 32 patients. DWMR images were obtained before contrast administration using three different b values of 100, 600, and 1000 s/mm². ADCs were measured for each lesions and compared with normal liver parenchymal ADCs on different b values. Hemangiomas were subdivided according to lesion size (less than 3 cm and 3 cm or greater). Data were analyzed using SPSS software by analysis of variances (ANOVA) and post hoc values were tested using HSD Tukey test.

Results

There was no significant relation between lesion size and ADC values on different b values. Lower ADC values were obtained for higher b values in normal liver tissue and hemangiomas. Although there is significant difference between normal liver tissue and hemangiomas; this is more apparent on b-1000 images (p = 0.022 on b-100, p = 0.003 on b-600, and p = 0.000 on b-1000 images). Variance analysis revealed hemangiomas had higher ADC values than normal liver tissue on b-1000 images.

Conclusion

Mean values for ADCs of hemangiomas were lower than ADCs of the normal liver except for b-1000 value. Higher b values are useful for the differentiation between normal liver tissue and hemangiomas. Lesion size does not affect ADC measurement on different b values.