rADC Values Research Articles

Apparent diffusion coefficient characteristics of parenchymal neuro-Behçet's disease.

To evaluate apparent diffusion coefficient (ADC) characteristic of parenchymal neuro-Behçet's disease (NBD). We retrospectively reviewed cranial magnetic resonance imaging (MRI) examinations of NBD patients with acute or chronic parenchymal lesions. ADC measurements of the lesions and contralateral normal brain parenchyma were performed by a consensus of two radiologists. To compare the ADC value of the chronic and acute lesions, relative ADC values (rADC) were calculated. The ratio of the lesions' ADC to contralateral normal brain parenchyma ADC yielded a rADC value of the lesions. Contrast enhancement patterns and the locations of the lesions were also noted. A total of 24 NBD patients with 45 parenchymal lesions, 25 acute, and 20 chronic, were enrolled in the study. A significant difference was observed between the mean ADC value of the acute lesions (1074.48±138.31m/s) and the mean ADC value of the contralateral normal brain parenchyma (841.20±142.96m/s; P<0.0001). A significant difference was observed between the mean ADC value of the chronic lesions (1069.95±143.95m/s) and the mean ADC value of the contralateral normal brain parenchyma (793.90±96.71m/s; P<0.0001). No significant difference was observed between the mean rADC (1.35±0.20) and the mean rADC value of the chronic lesions (1.29±0.15; P=0.22). ADC measurements might provide substantial information about the histopathological aspect of parenchymal NBD lesions.

Utility of the relative apparent diffusion coefficient for preoperative assessment of low risk endometrial carcinoma

ObjectivesLymphadenectomy is not recommended for low risk stage I endometrial carcinoma (EC) patients. This study was to investigate the predictive value of apparent diffusion coefficient (ADC) values in predicting patients with low risk EC, and to identify an optimum ADC measurement for preoperative assessment. Materials and methodsEighty-one patients with stage I EC who underwent diffusion-weighted imaging (DWI) at 1.5T were included and divided into low group and intermediate-high risk group based on the ESMO-ESGO-ESTRO classification. Clinical indexes, conventional MRI parameters, minimum ADC values (minADC), mean ADC values (meanADC) and relative ADC values (rADC) were compared between those two groups. rADC was calculated using the equation ADC (cancer)/ADC (reference) with the obturator internus muscle as reference. The optimal ADC measurement and cut-off ADC value for low risk EC were calculated using the receiver operating characteristic (ROC) curve. ResultsThe low risk group had significantly higher meanADC, minADC, and rADC values than did the intermediate-high risk group (1.095 vs. 0.902 × 10−3 mm2/s, 0.755 vs. 0.657 × 10−3 mm2/s, 0.754 vs. 0.603, respectively). In assessments of low risk EC patients, the area under the curve (AUC) values for meanADC, minADC, and rADC were 0.840 (95%CI, 0.749,0.931), 0.681 (95% CI: 0.561,0.800), and 0.876(95% CI: 0.798,0.954), respectively. The optimal cut-off rADC value for prediction was 0.669, the maximum Youden index, sensitivity, specificity, and accuracy values were 0.683, 81.8%, 86.5%, and 84.0%, respectively. ConclusionsrADC is superior to minADC and meanADC for predicting patients with low risk EC, and could potentially aid to the surgical management of these patients in avoiding unnecessary lymphadenectomy.

Does the Apparent Diffusion Coefficient Value Predict Permanent Cerebral Ischemia/Reperfusion Injury in Rats?

Variation in tissue damage after cerebral ischemia/reperfusion (I/R) can cause uncertainty in stroke-related studies, which can be reduced if the damage can be predicted early after ischemia by measuring the apparent diffusion coefficient (ADC). We investigated whether ADC measurement in the acute phase can predict permanent cerebral I/R injury. The middle cerebral artery occlusion model was established using the intraluminal suture method to induce 60 minutes of ischemia followed by reperfusion in rats. T2-weighted images and diffusion-weighted images were obtained at 30 minutes and 24 hours after ischemia. Neuronal cell survival was assessed by neuronal nuclei (NeuN) immunofluorescence staining. The correlation between relative ADC (rADC) values at 30 minutes and I/R injury at 24 hours after ischemia was analyzed. Magnetic resonance imaging results were confirmed by histologic analysis. The correlation between rADC values at 30 minutes and 24 hours was strong in the ischemic core and peri-infarct region but moderate in the anterior choroidal and hypothalamic region. Histologic analysis revealed that the correlation between rADC values at 30 minutes and the number of NeuN-positive cells at 24 hours was strong in the ischemic core and peri-infarct region but moderate in the anterior choroidal and hypothalamic region. Furthermore, there was a strong positive correlation between the sum of rADC values of three regions at 30 minutes and the infarct volume at 24 hours. ADC measurement in the acute phase can predict permanent cerebral I/R injury and provide important information for the evaluation of ischemic stroke.

Value of Diffusion-weighted Imaging in Evaluating the Activity of Sacroiliitis in Ankylosing Spondylitis

Objective To investigate the clinical value of diffusion-weighted imaging (DWI) for evaluating the activity of sacroiliitis in ankylosing spondylitis (AS).Methods Totally 73 AS patients were prospectively enrolled and divided into active group (n=43) and chronic group (n=30) according to Bath ankylosing spondylitis disease activity index (BASDAI) scores and laboratory findings. Conventional magnetic resonance imaging (MRI) and DWI were performed in all subjects. Apparent diffusion coefficient (ADC) values of subchondral lesions in sacroiliac joint were independently measured by two radiologists,and the relative ADC (rADC) values were calculated. ADC and rADC values were compared between active and chronic groups. The efficiencies of ADC and rADC values for differentiating the activity of sacroiliitis were analyzed. In addition,the correlation coefficients of ADC values,rADC values,and BASDAI scores were calculated.Results The ADC and rADC values in the active group were (0.667±0.122)×10 -3 mm 2/s and (1.715±0.343)×10 -3 mm 2/s,respectively,which were significantly higher than those of the chronic group [(0.492±0.0651)×10 -3 mm 2/s and (1.289±0.209)×10 -3 mm 2/s,respectively)] (P<0.0001). The agreement of measurement results between two radiologists was good,and all the interclass correlation coefficients were >0.81. The correlation coefficients of ADC value and rADC value with BASDAI scores were 0.82 and 0.80,respectively (P<0.0001). The optimal cutoff values of ADC value and rADC value for differentiating AS activity were 0.545×10 -3 mm 2/s and 1.467×10 -3 mm 2/s,respectively,The specificity was 81.8% for both indicators,and the sensitivity was 92.0% and 88.0%,respectively.Conclusion DWI is helpful in the quantitative assessment of the activity of sacroiliitis in AS patients.

Tirofiban combined with rt-PA intraarterial thrombolysis improves the recanalization rate of acute middle cerebral artery occlusion in rabbits.

To investigate the curative effect of tirofiban combined with recombinant tissue-plasminogen activator (rt-PA) selective intra-arterial thrombolysis on acute middle cerebral artery occlusion (MCAO). A total of 60 adult male Japanese white rabbits weighing 2.5-3.0 kg were selected, and the acute cerebral infarction model was established via autologous thromboembolism of middle cerebral artery. Rabbits were randomly divided into 4 groups: tirofiban group (Ti group, 5 μg/kg, n=15), rt-PA group (rt-PA group, 2 mg/kg, n=15), tirofiban + rt-PA group (Ti + rt-PA group, 3 μg/kg Ti + 1 mg/kg rt-PA, n=15), and control group (Co group, n=15). The vascular recanalization rate of intra-arterial thrombolysis was observed via digital subtraction angiography (DSA), relative apparent diffusion coefficient (rADC) was observed via diffusion-weighted imaging (DWI), and neurologic impairment was observed via modified Bederson's scoring method. Rabbits were executed after 24 h, then the volume of cerebral infarction was measured via triphenyl tetrazolium chloride (TTC) staining, pathological examinations were performed using the optical microscope and electron microscope, and immunohistochemical examination was performed for brain-derived neurotrophic factor (BDNF). In Ti + rt-PA group, the vascular recanalization rate was 91.7%, and there was no significant bleeding in pathological examination. The rADC value, neurologic impairment score and cerebral infarction area in Ti + rt-PA group were superior to those in Co group, Ti group and rt-PA group. Immunohistochemical results of BDNF showed that the expression of BDNF in Ti + rt-PA group was increased compared with those in Co group, Ti group and rt-PA group. In Ti group and rt-PA group, there were neuronal degeneration, moderate organelle swelling, moderate mitochondrial swelling, enlarged volume and decreased number of cristae, and rupture and disappearance of some mitochondrial cristae. In Co group, neuronal karyopyknosis, nuclear chromatolysis and disappearance of cellular structure could be seen. Results of electron microscopy showed that the shape of neuronal nuclei in Ti + rt-PA group was basically normal, and there were mild mitochondrial swelling and enlarged volume of cristae. Early application of tirofiban combined with rt-PA in intra-arterial thrombolysis for ultra-early cerebral ischemia can improve the recanalization rate of cerebral artery. The time of cerebral ischemia and hypoxia is short, and the neuronal ischemia-reperfusion injury is mild, whose thrombolysis effect is better than the single application of tirofiban or rt-PA.

Apparent Diffusion Coefficient of the Placenta in Twin versus Singleton Pregnancies

Previous studies in singleton pregnancies reported conflicting trends in apparent diffusion coefficient (ADC) values with gestational age (GA) and stable relative ADC (rADC; ADC placenta divided by ADC globe) throughout pregnancy. The purpose of our study was to compare the ADC and rADC of placentas of twin and singleton pregnancies. Materials and Methods: Fetal MRI of 11 twin and 23 singleton pregnancies were retrospectively analyzed. Each group was further divided by GA (≤24 and >24 weeks). On ADC, 3 regions of interest were selected in the placenta and 1 in the globe. ADC and rADC measurements were compared between different GA and between singleton and twin placentas. Results: No significant difference was shown between ADC and rADC values of singleton and twin placentas as well as between ADC and rADC values of singleton and twin placentas at different GA. No significant difference was shown when accounting for both GA and number of fetuses. Conclusion: The diffusion characteristics of twin placentas are similar to those of singleton placentas. ADC and rADC remain stable throughout pregnancy in twin and singleton placentas, reflecting stable extracellular water diffusion, despite changes associated with placental maturation.

Diffusion-Weighted Imaging for the Discrimination of Benign and Malignant Breast Masses; Utility of ADC and Relative ADC

Purpose:To determine the contribution of apparent diffusion coefficient (ADC), and relative ADC (rADC) values to differentiate between benign and malignant breast masses.Materials and Methods:Magnetic resonance imaging (MRI) of the breast with diffusion-weighted imaging (DWI) of patients with benign or malignant breast masses diagnosed either by histopathological findings or by follow-up imaging were evaluated retrospectively. Histopathological analyses were performed for 71 lesions (80.7%) while the remaining were followed up every six months for one year. DWI was performed using b-values of 0 and 1000 sec/mm2, and ADC and rADC were calculated and compared. A receiver operating characteristic (ROC) curve and Youden index were used to evaluate the parameter’s optimal threshold and diagnostic value. Statistical significance was set as p < 0.05.Results:Eighty-eight lesions from a total of 81 patients, aged between 16 and 73 (mean age 42 ± 11.3) years were obtained and evaluated. Pathological results of 34 (38.6%) out of 71 lesions were malignant and 37 lesions (42%) were benign. Seventeen (19.3%) lesions remained stable at one-year follow-up and were accepted as benign breast masses. Mean ADC values of benign and malignant lesions were 1.584 × 10–3mm2/sec and 0.884 × 10–3mm2/sec (p < 0.05), respectively. Sensitivity and specificity of ADC were 88% and 87%, respectively at a cut-off value of 1.04 × 10–3mm2/sec. Mean rADC was 0.931 for benign lesions and 0.557 for malignant lesions (p < 0.05). Sensitivity and specificity were 82% and 83% at a cut-off value of 0.639. No prominent superiority of rADC over ADC is identified in the differentiation of breast masses.Conclusion:ADC and rADC values derived from DWI can be equally useful in clinical setting to differentiate benign from malignant breast masses.

Abstract WP60: Evaluation of Tissue Reversibility by Relative Apparent Diffusion Coefficient Value in Acute Ischemic Stroke Patients Treated With Successful Thrombectomy

Background: By recent advance of endovascular thrombectomy, we have often experienced acute ischemic patients who have diffusion weighted imaging (DWI) reversal lesions after earlier successful recanalization. We retrospectively investigated the relationship between apparent diffusion coefficient (ADC) thresholds of tissue infarction and time from onset to recanalization in acute ischemic stroke patients. Methods: We assessed 24 patients who have occlusion of internal carotid artery (n=11) and the main trunk of middle cerebral artery (n=13) and obtained recanalization of TICI2b (n=12) and TICI3 (n=12) by thrombectomy and performed MRI before and after treatment. Relative ADC (rADC) value were calculated for initial DWI lesions and around hypoperfused regions. We evaluated rADC values in infarcted and non-infarcted area and analyzed the relationship between rADC thresholds of tissue infarction and time. Results: The mean time from onset to recanalization was 209 minutes and mean initial NIHSS was 15.4. The mean rADC value was 0.633 in infarcted lesions and 0.905 in non-infarcted area (p&lt;0.001). The thresholds for rADC value for infarction by the area under the curve derived from receiver operating characteristic curve analysis were 0.769 in the area which recanalized under 180 minutes form the onset, 0.792 in that from 180 to 240 minutes, and 0.798 in that over 240 minutes. Conclusion: The estimation of rADC value may be useful in predicting the likelihood of DWI lesion reversal. Marked decreasing of rADC value which is under thresholds of infarction indicated irreversible damage of ischemic tissue regardless of early successful recanalization.

Cerebral schistosomiasis: diffusion-weighted imaging helps to differentiate from brain glioma and metastasis.

Background Diffusion-weighted imaging (DWI) was introduced into clinical use some years ago. However, its use in the diagnosis of cerebral schistosomiasis has not been reported. Purpose To investigate the ability of the apparent diffusion coefficient (ADC) value of DWI in the diagnosis of cerebral schistosomiasis, and to differentiate it from brain high-grade gliomas and metastasis. Material and Methods Conventional brain MRI with pre-contrast, post-contrast, and DWI was performed on 50 cases of cerebral schistosomiasis, high-grade glioma, and brain metastasis. The ADC values of the three lesions, the proximal and the distal perifocal edema were measured. In order to remove the individual difference effect of ADC values, relative ADC (rADC) values were calculated through dividing the ADC value of the lesion area by that of the contralateral normal white matter. rADC values were used to evaluate the differences among cerebral schistosomiasis, brain high-grade gliomas, and metastasis. Results rADC of cerebral schistosomiasis was significantly lower than rADC of brain metastasis ( P < 0.05), without any significant differences when compared with high-grade gliomas. rADC of proximal perifocal edema in cerebral schistosomiasis was significantly higher than in high-grade gliomas ( P < 0.010), but not different compared with brain metastasis. Conclusion DWI examination with ADC values of lesions and proximal perifocal edema might be helpful in the exact diagnosis of cerebral schistosomiasis.

Prognostic Value of Diffusion-Weighted Imaging (DWI) Apparent Diffusion Coefficient (ADC) in Patients with Hyperacute Cerebral Infarction Receiving rt-PA Intravenous Thrombolytic Therapy.

BackgroundThe aim of this study was to investigate the potential value of apparent diffusion coefficient (ADC) of diffusion-weighted imaging (DWI) in the prognosis of patients with hyperacute cerebral infarction (HCI) receiving intravenous thrombolytic therapy with recombinant tissue plasminogen activator (rt-PA).Material/MethodsFrom June 2012 to June 2015, 58 cases of HCI (<6 h) undergoing rt-PA intravenous thrombolytic therapy (thrombolysis group) and 70 cases of HCI (<6 h) undergoing conventional antiplatelet and anticoagulant therapy (control group) in the same period were collected. DWI was conducted on all the subjects, and ADC maps were generated with Functool software to quantify ADC value. The clinical outcomes of HCI patients were observed for 3 months, and prognostic factors were analyzed.ResultsBefore thrombolysis treatment, the lesion area presented high signal intensity on DWI map and low signal intensity on ADC map, and gradually weakened signal intensity on DWI map and gradually enhanced signal intensity on ADC map were observed after thrombolysis. The ADC values of the thrombolysis group were significantly higher than those of the control group after treatment (24 h, 7 d, 30 d, and 90 d) (all P<0.05), and the ADC and rADC values in the thrombolysis group gradually increased over time (all P<0.05). Multiple logistic regression analysis showed that baseline National Institutes of Health Stroke Scale (NIHSS) score, baseline rADC value, and stroke history were the independent factors for the prognosis of HIC patients with thrombolysis (all P<0.05).ConclusionsThe values of ADC and rADC may provide guidance in the prognosis of HCI patients receiving rt-PA, and the baseline rADC value is the protective factor for the prognosis of HCI patients receiving rt-PA.

Diffusion-weighted MRI in liver fibrosis staging: Added value of normalized ADC using spleen and renal cortex as reference organs

AimTo evaluate the potential value of the spleen and renal cortex as a reference organ to improve the performance of DWI in the assessment of liver fibrosis. Material and methods44 subjects were included: 30 patients with chronic viral hepatitis and 14 age matched volunteers. They were subjected to diffusion weighted MRI (DWI). Liver ADC, normalized ADC (ratio between ADC of liver to spleen (S-ADC) and renal cortex (R-ADC)) was calculated. Data was analyzed and ROC was used to evaluate the performance of ADC, S-ADC and R-ADC. ResultsNo significant difference between spleen ADC and renal ADC values between patient group and control group or in-betweens different fibrosis stages. The mean liver ADC was significantly lower in cirrhotic patients than control group (1.59±0.024 versus 1.55±0.036×10−3mm2/s, P=0.009) with some overlap in different fibrosis grades.With exception to stage 1 fibrosis, the mean S-ADC value was significantly lower in patients with different hepatic fibrosis stages in comparison to control group (P 0.02–<0.001). Significant negative correlation was noted between S-ADC value and fibrosis stage (r=−0.75, p<0.001). It had significant difference between stage 0 compared to stage 2, 3, and 4 as well as between stage 4 in comparison to stage 1, 2 and 3. S-ADC had a significant ability to differentiate between stages 0–1 Vs stage 2–4, stage 0–2 Vs stage 3–4 as well as stage 0–3 Vs stage 4.Significant negative correlation was noted between R-ADC value and fibrosis stage (r=−0.68, p<0.001). The mean R-ADC value was lower in patients with liver fibrosis compared to volunteers with significant difference between stage 0 and 3 and between stage 0 and 4 (P<0.001). It had significant difference between stage 0 compared to stage 3, and 4 as well as in stage 4 in comparison to stage 1 and 2. R-ADC has a significant ability to differentiate between stages 0–1 Vs stage 2–4, stage 0–2 Vs stage 3–4 as well as stage 0–3 Vs stage 4.ROC analysis showed higher performance using S-ADC in comparison to liver ADC and R-ADC while R-ADC had higher performance in comparison to liver ADC. The AUC, sensitivity, specificity, PPV, NPV and k-value for detection of fibrotic stages ⩾2 (0.85, 95.8%, 60%, 74%, 92% and 0.85 for S-ADC Vs 0.68, 66.7%, 60%, 66%, 60% and 0.28 for ADC and 0.85, 95.8%, 50%, 69%, 91% and 0.47 for R-ADC). and in detection of fibrotic stages ⩾3 was (0.86, 100%, 52%, 61%, 100% and 0.48 for S-ADC Vs 0.63, 63%, 52%, 50%, 65% and 0.14 for ADC and 0.88, 100%, 44%, 57%, 100% and 0.40 for R-ADC) while for fibrosis stage 4, the corresponding values was (1, 100%, 100%, 100%, 100% and 1 for S-ADC Vs 0.7, 81%, 54%, 37%, 90% and 0.26 for ADC and 0.65, 100%, 65%, 45%, 100% and 0.43 for R-ADC) respectively. ConclusionNormalized liver ADC using the spleen and kidney increases the performance of ADC in the evaluation of liver fibrosis which is highest in spleen normalized ADC.

Prediction of Infarct Lesion Volumes by Processing Magnetic Resonance Apparent Diffusion Coefficient Maps in Patients with Acute Ischemic Stroke

We aimed to investigate the diagnostic value of apparent diffusion coefficient (ADC) maps in magnetic resonance imaging (MRI) in the volume of acute cerebral infarction (ACI). A total of 207 ACI patients were selected in our study. The cerebral infarction (CI) volume in the initial diffusion-weighted imaging examination, minimum ADC value, relative apparent diffusion coefficient (rADC) value, and mean ADC value were measured. The correlations between age, smoking, drinking, hypertension, diabetes, coronary heart disease, clinical stage, the lowest ADC value, the mean ADC value, and the mean rADC value with CI volume were analyzed by logistic regression analysis. A receiver operating characteristic (ROC) curve was used to analyze the diagnostic value of the ADC value in the ACI volume. There was a significant difference in the distribution of the CI volume in ACI patients (P <.05). A significant difference was found in the signal intensity and percentage distribution of ADC map in patients of different CI groups with different CI volumes (P <.05). The signal of the ADC map was positively correlated with the CI volume. The mean ADC and rADC values had significant differences between different CI volumes (all P <.05). Logistic regression analysis revealed that the mean ADC value was significantly correlated with the CI volume (P <.05). Analysis of the ROC curve showed that the quantitative value of ADC has a diagnostic value for the ACI volume. This study has shown that the signal intensity change on the ADC map in MRI and quantitative analysis of the ADC value can be used as a reference for predicting the ACI volume.

Prognostic and predictive values of diffusion and perfusion MRI in paediatric intracranial ependymomas in a large national study.

To assess the relative cerebral blood volume (rCBV) and apparent diffusion coefficient (ADC) derived, respectively, from perfusion and diffusion pre-operative MRI of intracranial ependymomas and their predictive and prognostic values. Pre-operative MRI and clinical data for intracranial ependymomas diagnosed between January 2000 and December 2013 were retrospectively retrieved from a web-based national database. MRI data included diffusion (62 patients) and perfusion (20 patients) MRI. Patient age, histopathological diagnosis, tumour location, ADC, relative ADC (rADC) and rCBV were considered as potential factors in a survival analysis. Survival rates were estimated using the Kaplan-Meier method. Univariate analyses were performed using the log-rank test to compare groups. We also performed a multivariate analysis, applying the Cox proportional hazards model. ADC and rADC values within hypointense regions differed significantly between grades II and III (p = 0.01). The 75th percentile of ADC within hypointense regions and the 25th percentile of rCBV within non-enhancing lesions were prognostic of disease-free survival (p = 0.004, p = 0.05). A significant correlation was found between the 75th percentile of rCBV and the 25th percentile of rADC (p = 0.01) in enhancing regions of grade-III tumours. Pre-operative rADC and rCBV could be used as prognostic factors for clinical outcome and to predict histological grade in paediatric ependymomas. Prognostic value of diffusion and perfusion MRI in paediatric ependymoma was found and may play a role in the prognostic classification of patients in order to design more tailored treatment strategies.

Application of Diffusion-Weighted Imaging in the Detection of Active Sacroiliitis and the Comparison of Apparent Diffusion Coefficient and Relative Apparent Diffusion Coefficient Values.

This study aims to evaluate the role of diffusion-weighted imaging in detection of active sacroiliitis and compare the apparent diffusion coefficient (ADC) and normalized relative ADC (r-ADC) values by using vertebra and iliac wings as reference organs. The study included 56 patients (26 males, 30 females; mean age 37.7±10.1 years; range 18 to 66 years) with chronic back pain and without history of sacroiliitis who underwent magnetic resonance imaging. T2-weighted spectral presaturation with inversion recovery, contrast-enhanced T1-weighted spectral presaturation with inversion recovery, and diffusion-weighted (b values: 0 and 600 s/mm2) images were obtained. All images were evaluated by two different radiologists for interobserver variability. All individuals were grouped in either mechanical low back pain (control group) or active sacroilitis (disease group) groups according to the presence or absence of MRI findings of active sacroilitis. ADC values of both surfaces were measured from normal and affected areas of joints. Also, ADC values of L5 vertebra and iliac wings were measured as reference organs to calculate r-ADC values. Mean ADC and r-ADC values measured from lesions were significantly higher than that of normal appearing bone marrow areas in both patients with mechanical low back pain (n=17) and active sacroiliitis (n=39). Both ADC values and r-ADC values could differentiate active lesions from normal appearing bone marrow areas as well as contrast-enhanced T1-weighted images. According to r-ADC values calculated with the L5 vertebra, unaffected portions of bone marrow areas in patients with sacroiliitis were normalized whereas r-ADC remained higher than normal in affected portions of the bones. Diffusion-weighted imaging is a fast, sensitive magnetic resonance imaging sequence in detection of active sacroiliitis. It does not require contrast agent and can be safely used as an adjunct to conventional magnetic resonance images. r-ADC is also highly sensitive in detecting active sacroiliitis and may be used as an alternative to standard ADC measurements for the demonstration of inflammation. It helps eliminate individual bone marrow differences by using patients' own normal bone marrow measurements and increases diagnostic accuracy.

High b value DWI in evaluation of the hyperacute cerebral ischemia at 3T: A comparative study in an embolic canine stroke model.

Previous studies have indicated that the temporal change of relative diffusion weighted imaging (rDWI) signal intensity may help to determine the onset time of a stroke. Furthermore, several studies have indicated that high b value DWI offered improved detection rates for hyper-acute ischemic lesions compared with standard b value DWI. However, the temporal changes of the rDWI on high b value DWI remain unclear. Therefore, based on our embolic canine stroke model, we evaluated the temporal evolution of rDWI on high b value DWI, and further compared its diagnostic value in predicting the onset time of ischemic stroke with rDWI on standard b value DWI. Twelve canine MCAO models were established, and DWI was performed at 1, 2, 3, 4, 5 and 6 h after MCAO, with 3 b values of 1,000, 2,000 and 3,000. High b value DWI detected all ischemic lesions after 1 h, while standard b value did not detect the ischemic lesions in one dog at 1 h. With all three of the tested b values, rDWIs increased continuously within 6 h, while relative apparent diffusion coefficient (rADC) values rapidly decreased in 1 h, then became relatively stable. The area under the curve values for rDWI with b value of 1,000, 2,000 and 3,000, in predicting ischemic lesions within 3 h were 0.897, 0.929 and 0.938, while for rADC were 0.645, 0.583 and 0.599, respectively. Therefore, the results indicated that the rDWI was helpful in aging hyper-acute ischemic stroke, while rADC appeared not to be. High b value DWI had a higher detection rate for ischemic lesions and better predictive efficacy in determining the onset time of hyper-acute stroke.

The usefulness of diffusion-weighted imaging for differentiating portal vein thrombus from tumour embolus

To investigate the usefulness of diffusion-weighted imaging (DWI) for differentiating bland portal vein thrombus from tumour thrombus. Fifteen patients with clinical comprehensive diagnoses of portal vein thrombus were analysed retrospectively. The thrombus signal intensity on 21 DWI slices and apparent diffusion coefficient (ADC) values were analysed quantitatively. The portal vein thrombus was divided into four types (low/low, high/low, low/high, and high/high) based on the DWI/ADC ratios between the thrombus and liver parenchyma (rDWI and rADC, respectively). Twenty patients with portal vein tumour thrombi were used for comparison as controls. The average ADC value for the bland thrombus was 1.84 ± 0.70 × 10−3 mm2 s−1 (range: 0.46–2.77 × 10−3 mm2 s−1), and was 2.18 ± 0.51 × 10−3 mm2 s−1 (range: 1.39–2.82 × 10−3 mm2 s−1) for the liver parenchyma; the rADC was therefore 0.90 ± 0.45 (range: 0.26–1.86). The tumour thrombi were high/low and high/high type. The average ADC for the tumour thrombus was 1.25 ± 0.26 × 10−3 mm2 s−1 (range: 0.68–1.67 × 10−3 mm2 s−1), and 1.56 ± 0.33 × 10−3 mm2 s−1 (range: 1.11–2.34 × 10−3 mm2 s−1) for the liver parenchyma; the rADC was therefore 0.82 ± 0.16 (range: 0.39–1.08). There was no statistical difference in rADC values and rDWI/rADC classification performance between the bland and tumour thrombi. The ADC difference between portal vein bland and tumour thrombi was statistically significant, but the ADC values of bland thrombi have a wider range, which contains the ADC values of tumour thrombi with a narrower range. The elevated ADC values of the liver parenchyma adjacent to portal vein emboli may be helpful for the diagnosis of bland thrombi.

Tirofiban combined with urokinase selective intra-arterial thrombolysis for the treatment of middle cerebral artery occlusion.

The aims of the present study were to establish a model of embolic stroke in rabbits and to evaluate the efficacy and safety of intra-arterially administered tirofiban combined with urokinase thrombolysis. The middle cerebral artery occlusion model (MCAO) of embolic stroke was established in New Zealand rabbits via an autologous clot. The model rabbits were allocated at random into four groups: Tirofiban group (T group), urokinase group (UK group), tirofiban and urokinase group (T + UK group) and the control group (C group). The recanalization rate, relative-apparent diffusion coefficient (rADC) and neurological function deficit score (NFDS) values were compared among the four groups. The recanalization rate, rADC and NFDS values were improved in the T + UK group compared with the other groups. In summary, the intra-arterial administration of tirofiban combined with urokinase thrombolysis was a more effective intervention in an MCAO model compared with intra-arterial urokinase alone, and may promote reperfusion and reduce infarct volume.

Pathological and radiological-control study of brain tissue radiation injury in normal rats: a comparative study

Objective To study the imaging findings and pathologic changes of early radiation injury of normal brain tissue in rats with gamma ray irradiation. Methods Seventy adult SD rats were randomly divided into either a radiation group or a control group. Using the self-made rat stereotactic head frame, the right side of rat brain tissue was irradiated by 100 Gy doses. Each observation time point received 7.0 T head MRI and diffusion tensor imaging (DTI) at 1, 2, 3, 4, 5, 6, and 7 weeks after radiation. The values of apparent diffusion coefficient (ADC) and fractional anisotropy (FA) were statistically analyzed. Brain tissue samples were obtained for pathological observation at the same time. Results (1) The findings of DTI: There were significant differences in rADC values and rFA values from the 4th week between the radiation group and the control group (the ratios at the 4th, 5th, 6th, and 7th weeks were 1.27±0.06 vs. 0.98±0.04 and 0.75±0.05 vs. 1.04±0.05, 1.52±0.08 vs. 0.98±0.03 and 0.64±0.08 vs.1.04±0.05, 1.35±0.09 vs. 1.00±0.02 and 0.63±0.03 vs. 1.04±0.05, and 1.37±0.10 vs. 0.99±0.05 and 0.58±0.04 vs. 1.04±0.03, respectively; all P<0.01). (2) The pathological changes of brain tissue after radiation included two stages: Early microvascular peripheral edema and the structural integrity of blood-brain barrier structure; late target lesions changed significantly, including the decreased number of neurons and glial cells, vasodilatation and deformation, obviously damaged blood-brain barrier structure, and myelin disintegration. Conclusions Early change of rat brain tissue radioactivity is mainly vasogenic edema. The changes of neurons, glial cells, microvascular damage, and demyelination appear in late stage, and these significant changes are consistent with the findings of DTI, indicating the value of DTI in the studies of radiation damage. Key words: Radiosurgery; Gamm knife; Brain injuries; Radioactivity; Diffusion tensor imaging; Rats

Simple quantitative measurement based on DWI to objectively judge DWI-FLAIR mismatch in a canine stroke model.

Diffusion-weighted imaging (DWI) - fluid attenuated inversion recovery (FLAIR) mismatch was proven useful to time the onset of wake-up stroke; however, identifying the status of FLAIR imaging has been mostly subjective. We aimed to evaluate the value of relative DWI signal intensity (rDWI), and relative apparent diffusion coefficient (rADC) in identifying the FLAIR status in the acute period. Autologous clot was used to embolize left middle cerebral artery in 20 dogs. Magnetic resonance imaging was performed 3-6 hours and 24 hours after embolization. DWI-FLAIR mismatch was defined as hyperintense signal detected on DWI, but not on FLAIR. The mean values of rDWI or rADC of FLAIR- and FLAIR+ lesions were compared and the critical cutoff values of rDWI and rADC for identifying the FLAIR status were determined. Stroke models were successfully established in all animals. DWI+ lesions were found in all 20 dogs from three hours, while FLAIR+ lesions were found in three, 11, 16, 19, and 20 dogs at five time points after embolization, respectively. The mean rDWI values were significantly different between FLAIR- and FLAIR+ lesions (P < 0.001), but rADC values were not (P = 0.73). Using rDWI=1.90 as the threshold value, excellent diagnostic efficacy was achieved (AUC, 0.88; sensitivity, 0.77; specificity, 0.88). However, rADC appeared not useful (AUC, 0.48; sensitivity, 0.52; specificity, 0.58) in identifying the FLAIR status. In our embolic canine stroke model, rDWI was useful to identify FLAIR imaging status in the acute period, while rADC was not.

Value of diffusion weighted imaging in the differential diagnosis of benign and malignant breast lesions at 3.0T MRI.

The aim of this study was to investigate the correlation between apparent diffusion coefficients (ADCs), the relative apparent diffusion coefficient (rADC), and the pathological prognostic factor human epidermal growth factor receptor 2 (HER-2) in patients with breast cancer. A total of 64 women with breast cancer underwent breast diffusion-weighted imaging. HER-2 expression was detected in histological specimens. The ADC value, rADC value, and HER-2 level were determined. The ADC and rADC values of the breast cancer group were 1.1495 ± 0.1499 x 10(-3) and 0.6602 ± 0.0853, respectively. The differences in the ADC and rADC values between the two groups were statistically significant. There was no correlation between the ADC value and HER-2 expression in patients with breast cancer (r = -0.508, P = 0.043). However, the rADC value eliminated the individual differences to some extent. Therefore, compared to the ADC value, the rADC value had a better correlation with HER-2 expression.