Value Of Susceptibility-weighted Imaging Research Articles

Value of susceptibility-weighted imaging in differentiating benign from malignant portal vein thrombosis.

Many diseases are accompanied by portal vein thrombosis (PVT), and its nature is closely related to its prognosis and treatment. It is important to evaluate magnetic resonance imaging (MRI) parameters, including susceptibility-weighted imaging (SWI) and qualitative diffusion-weighted imaging (DWI), in the differentiation between benign and malignant PVT. In this retrospective study, we collected clinical imaging data from 140 patients with PVTs characterized as benign or malignant based on enhanced MRI between January 2011 and April 2016 and retrospectively analyzed PVTs using SWI and DWI. There were 37 benign and 103 malignant PVTs. Image review was performed by 2 radiologists blinded to clinical information. The signal intensity (SI) of PVTs was recorded on SWI. The apparent diffusion coefficient (ADC) and the ratio of signal intensity (SIR) on SWI (SIRSWI) and ADC (SIRADC) between the PVTs and the spinal cord were calculated. Finally, we generated receiver operating characteristic (ROC) curves to evaluate the efficacy of SIRSWI and SIRADC for distinguishing benign and malignant PVTs. On SWI and DWI, 100.0% (36/36) and 80.5% (29/36) of benign PVTs were hypointense, respectively. For malignant PVTs on SWI and DWI, 99.0% (103/104) and 89.4% (93/104) were hyperintense, respectively. The SIRSWI values of benign and malignant PVTs were 0.58±0.13 and 0.88±0.06, respectively, representing a significant difference (P<0.001). The SIRADC values of benign and malignant PVTs were 0.72±0.32 and 0.62±0.17, respectively, representing a significant difference (P=0.034). The area under the ROC curve (AUROC) for SIRSWI [0.990; 95% confidence interval (CI): 0.971-1.000] was significantly higher than that for SIRADC (0.619; 95% CI: 0.500-0.737; P<0.001). The SIRSWI had a sensitivity of 100.0% and a specificity of 97.3% with a cutoff value of 0.749, while the SIRADC had a sensitivity of 45.9% and specificity of 83.3% with a cutoff value of 0.791. The diagnostic performance of SWI is superior to that of DWI in the differentiation of benign and malignant PVTs.

Differentiation between aggressive and benign intracranial non-cavernous dural arteriovenous fistulas using cortical venous reflux on susceptibility weighted images

PurposeThis study aimed to evaluate the ability of susceptibility-weighted imaging (SWI) to detect cortical venous reflux (CVR) in patients with intracranial non-cavernous dural arteriovenous fistulas (DAVFs), which can be helpful to differentiate benign and aggressive DAVFs. Material and MethodsTwenty-seven patients (8 women and 19 men) with 33 non-cavernous DAVFs were divided into benign and aggressive groups. Presence of CVR and pseudophlebitic pattern (PPP) and location of fistula on SWI were determined. Digital subtraction angiography was used as the reference standard. Interobserver agreement for the presence of CVR and PPP and location of DAVF on SWI was evaluated using the kappa statistic. Statistical comparisons between the benign and aggressive DAVFs were performed. ResultsSensitivity, specificity, positive predictive value, and negative predictive value of SWI for detecting CVR was 73.7%, 85.7%, 87.5%, and 70.6%, respectively. Corresponding values for detecting PPP were 95.2%, 83.3%, 95.2%, and 83.3%, respectively. SWI correctly identified DAVF location in 78.9%. Prevalence rates of CVR and PPP on SWI were significantly higher in aggressive DAVFs than benign ones. ConclusionSWI exhibited high sensitivity and specificity for detection of CVR, a characteristic used to differentiate benign and aggressive lesions. CVR and PPP on SWI are signs of aggressive DAVFs that guide to perform angiography confirmation and prompt treatment to avoid serious complication.

Susceptibility artifact morphology is more conspicuous on susceptibility-weighted imaging compared to T2* gradient echo sequences in the brains of dogs and cats with suspected intracranial disease.

Susceptibility-weighted imaging (SWI) has been found to be more reliable in the detection of vessels and blood products than T2*-weighted gradient echo (GE) in several human brain diseases. In veterinary medicine, published information on the diagnostic usefulness of SWI is lacking. The aim of this retrospective observational study was to investigate the value of SWI compared to T2*-weighted GE images in a population of dogs and cats with presumed, MRI-based diagnoses grouped as neoplastic (27), cerebrovascular (14), inflammatory (14), head trauma (5), other pathologies (4), or that were normal (36). Areas of signal void (ASV) were assessed based on shape, distribution, number, and conspicuity. Presence of ASV was found in 31 T2*-weighted GE and 40 SWI sequences; the conspicuity of lesions increased in 92.5% of cases with SWI. A 44.7% increase in the number of cerebral microbleeds (CMBs) was identified within the population using SWI (110) compared to T2*-weighted GE (76). Linear ASV presumed to be abnormal vascular structures, as are reported in humans, were identified in 12 T2*-weighted GE and 19 SWI sequences. In presumed brain tumors, abnormal vascular structures were detected in 11 of 27 (40.7%) cases on T2*-weighted GE and in 16 of 27 (59.3%) cases on SWI, likely representing tumor neovascularization; amorphous ASV interpreted as presumed hemorrhages on T2*-weighted GE were diagnosed as vessels on SWI in five of 27 (18.5%) cases. Since SWI shows ASV more conspicuously than T2*-weighted GE, the authors advocate the use of SWI in veterinary patients.

Collateral estimation by susceptibility-weighted imaging and prediction of functional outcomes after acute anterior circulation ischemic stroke

To determine the value of susceptibility-weighted imaging (SWI) for collateral estimation and for predicting functional outcomes after acute ischemic stroke. To identify independent predictors of favorable functional outcomes, age, sex, risk factors, baseline National Institutes of Health Stroke Scale (NIHSS) score, baseline diffusion-weighted imaging (DWI) lesion volume, site of steno-occlusion, SWI collateral grade, mode of treatment, and successful reperfusion were evaluated by multiple logistic regression analyses. A total of 152 participants were evaluated. A younger age (adjusted odds ratio (aOR), 0.42; 95% confidence interval (CI) 0.34 to 0.77; P < 0.001), a lower baseline NIHSS score (aOR 0.90; 95% CI 0.82 to 0.98; P = 0.02), a smaller baseline DWI lesion volume (aOR 0.83; 95% CI 0.73 to 0.96; P = 0.01), an intermediate collateral grade (aOR 9.49; 95% CI 1.36 to 66.38; P = 0.02), a good collateral grade (aOR 6.22; 95% CI 1.16 to 33.24; P = 0.03), and successful reperfusion (aOR 5.84; 95% CI 2.08 to 16.42; P = 0.001) were independently associated with a favorable functional outcome. There was a linear association between the SWI collateral grades and functional outcome (P = 0.008). Collateral estimation using the prominent vessel sign on SWI is clinically reliable, as it has prognostic value.

Demyelination and remyelination detected in an alternative cuprizone mouse model of multiple sclerosis with 7.0\xa0T multiparameter magnetic resonance imaging

The aim of this study was to investigate the mechanisms underlying demyelination and remyelination with 7.0 T multiparameter magnetic resonance imaging (MRI) in an alternative cuprizone (CPZ) mouse model of multiple sclerosis (MS). Sixty mice were divided into six groups (n = 10, each), and these groups were imaged with 7.0 T multiparameter MRI and treated with an alternative CPZ administration schedule. T2-weighted imaging (T2WI), susceptibility-weighted imaging (SWI), and diffusion tensor imaging (DTI) were used to compare the splenium of the corpus callosum (sCC) among the groups. Prussian blue and Luxol fast blue staining were performed to assess pathology. The correlations of the mean grayscale value (mGSV) of the pathology results and the MRI metrics were analyzed to evaluate the multiparameter MRI results. One-way ANOVA and post hoc comparison showed that the normalized T2WI (T2-nor), fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD) values were significantly different among the six groups, while the mean phase (Φ) value of SWI was not significantly different among the groups. Correlation analysis showed that the correlation between the T2-nor and mGSV was higher than that among the other values. The correlations among the FA, RD, MD, and mGSV remained instructive. In conclusion, ultrahigh-field multiparameter MRI can reflect the pathological changes associated with and the underlying mechanisms of demyelination and remyelination in MS after the successful establishment of an acute CPZ-induced model.

Value of susceptibility-weighted imaging for the assessment of angle measurements reflecting hip morphology

Radiographs are the clinical first line imaging modality for evaluating hip morphology and pathology. MRI offers additional information and is the method of choice to evaluate soft tissue, bone marrow and preradiographic signs of osteoarthritis. Radiographs are used to measure the most morphometric parameters. The aim of this study was to compare susceptibility weighted MRI (SWMR) with radiographs to evaluate hip morphology. 40 Patients were examined with standard MR-sequences, coronal SWMR and radiographs in anteroposterior pelvic view. Coronal maximum intensity projection (MIP) images of both hips were automatically reconstructed on SWMR and T1weighted images. Sharp´s angle, Tönnis angle, lateral center–edge angle of Wiberg and caput-collum-diaphyseal angle were measured on coronal SWMR MIP-images, T1weighted MIP-images and radiographs. Measurements were compared by linear regression analysis and Bland-Altmann Plots, using radiographs as reference standard. Additionally, a ratio between the signal intensity of muscles and bone on SWMR and T1weighted MIP-images was calculated and compared between these two sequences. SWMR enables the reliable assessment of Sharp´s angle (SWMR: R2 = 0.80; T1weighted: R2 = 0.37), Tönnis angle (SWMR: R2 = 0.86; T1weighted: not measurable), lateral center–edge angle of Wiberg (SWMR: R2 = 0.88; T1weighted: R2 = 0.40) and caput-collum-diaphyseal angle (SWMR: R2 = 0.38; T1weighted: R2 = 0.18) compared to radiographs with a higher accuracy than conventional MR imaging. The ratio between the intensity of muscles and bone was significant higher on SWMR (2.00 and 2.02) than on T1weighted MIP-images (1.6 and 1.42; p < 0.001).

Are Simple Magnetic Resonance Imaging Biomarkers Predictive of Neurodevelopmental Outcome at Two Years in Very Preterm Infants?

Background: Preterm infants are at increased risk of neurodevelopmental impairment due to the vulnerability of the immature brain. Early risk stratification is necessary for predicting outcome in the period of highest neuroplasticity. Several biomarkers in magnetic resonance imaging (MRI) at term equivalent age (TEA) have therefore been suggested. Objective: To assess the predictive value of simple brain metrics and the total abnormality score (TAS) – a modified score for brain injury and growth – in relation to neurodevelopmental outcome of very preterm infants in MRI at TEA. Methods: Single-centre cohort study including preterm infants with gestational age (GA) ≤32 weeks and birth weight ≤1,500 g. Biparietal width (BPW), interhemispheric distance, transcerebellar diameter (TCD) and TAS were assessed. To detect subtle haemorrhages, additional susceptibility-weighted imaging (SWI) was used in addition to conventional MRI to evaluate its clinical relevance. Neurodevelopment was tested by the Mental and Psychomotor Developmental Index (MDI/PDI) of the Bayley Scales of Infant Development II at a corrected age of 24 months. Results: One hundred twenty-nine children with median GA of 28.1 weeks and median birth weight of 980 g were included. BPW significantly correlated with PDI (p= 0.01, R² = 0.06) and TCD with MDI (p < 0.01, R² = 0.05) and PDI (p < 0.01, R² = 0.06) but explained variances were low. TAS was not predictive of neurodevelopmental outcome. By using SWI, additional 4 cases of low grade haemorrhages were identified compared to conventional sequences. In one case this additional information was clinically relevant (MDI/PDI below average). Conclusion: Simple brain metrics and TAS did not reliably predict neurodevelopmental outcome in a cohort with low prevalence of high grade brain injury. The additional value of SWI is yet to be determined in larger cohorts. The combination of imaging and functional biomarkers may be advisable for the prediction of neurodevelopmental outcome.

Comparative experiment study of susceptibility weighted imaging with T1ρ imaging in staging of hepatic fibrosis in rabbits

Objective To investigate the value of susceptibility weighted imaging (SWI) with T1ρ imaging in staging of hepatic fibrosis(HF) in rabbits. Methods Eighty selected white rabbits from New Zealand were randomly divided into the HF group (n=60) and the control group (n=20). Rabbits in the HF group were injected subcutaneously with 50% CCl4 oil solution to establish HF model,and the normal control rabbits were injected with saline solution subcutaneously.The HF group(n=15) and control group(n=5) were randomly selected at the 4th, 5th, 6th and 10th week after injection, to undergo liver MR scan. The liver signal intensity (SI liver), the muscle signal intensity (SI muscle),liver-to-muscle SI ratios (SIR) and liver T1ρ values were measured. Scheuer was adopted to stage the rabbits in HF.One-way analysis of variance was used to compare the differences between SIR and T1ρ values in different stages of HF pathological. Spearman correlation was used to analyze the correlation between SIR and T1ρ values in the different stage of HF pathological.The ROC were used to compare the efficacy between SIR and T1ρ values in the diagnosis of HF pathological stage. Results Among the final qualified 68 rabbits in the study, 17 in F0 phase, 11 in F1 phase, 16 in F2 phase, 11 in F3 phase, and 13 in F4 phase. The SIR were (0.977±0.013), (0.960±0.015), (0.802±0.026), (0.786±0.022), (0.541±0.116); T1ρ values were (22.301±1.849), (24.034±0.867), (25.374±1.309),(25.364±1.945),(30.948±2.925) ms.There were statistically significant in SIR between F0 and F2,F0 and F3,F0 and F4,F1 and F2,F1 and F3,F1 and F4,F2 and F4,F3 and F4 (P 0.966) ,and the AUC of the SIR was greater than T1ρ values in the other groups. Conclusion SWI and T1ρ values can provide an important objective basis in staging of HF. Both of them have great clinical application prospects but SIR diagnostic efficiency is slightly better than that of T1ρ values. Key words: Magnetic resonance imaging; Hepatic fibrosis; Magnetic susceptibility weighted imaging; T1ρrelaxation

Susceptibility-weighted Imaging in Thrombolytic Therapy of Acute Ischemic Stroke.

Objective:To provide a comprehensive and latest overview of susceptibility-weighted imaging (SWI) in the application of thrombolysis in acute ischemic stroke, and to update the decision-making effect and clinical value of SWI on identifying stroke patients suitable for thrombolytic therapy and possible benefits and risks followed.Data Sources:Literatures referred to this review were collected from PubMed, Medline, and EMBASE published till May 2017, using the search terms including susceptibility-weighted imaging, gradient-echo, T2*, thrombolysis, recombinant tissue plasminogen activator (rt-PA), thrombolytic therapy, and stroke.Study Selection:Papers in English or with available English abstracts were considered, with no limitation of study design. References were also identified from the bibliographies of identified articles and the authors’ files.Results:SWI is of guiding significance for thrombolytic therapy in stroke patients, it can predict the location and length of thrombus and ischemic penumbra. It is worthy of noting that susceptibility vessel sign (SVS) on SWI can be used to predict recanalization after thrombolytic therapy and whether it is better to implement endovascular thrombolectomy in combination or alone. SWI is sensitive in detecting cerebral microbleed (CMB), and CMB might not be a contraindication for thrombolytic therapy, yet CMBs in multiple foci could possibly be related to intracranial hemorrhage (ICH) after thrombolysis. SVS and CMB on SWI sequence are of instructive value in performing antiplatelet therapy after thrombolytic therapy. Cerebral venous change on SWI is related to lower recanalization rate and poor outcome after thrombolysis.Conclusions:It seems that SWI can be applied to guide individualized thrombolytic therapies and assist clinicians in making better decisions by weighing benefits and risks. However, there still exist controversies about the relationship between signs on SWI and thrombolytic therapy.

Susceptibility-weighted imaging for the assessment of chronic renal injury

Objective To explore the value of susceptibility-weighted imaging (SWI) for the assessment of chronic renal injury. Methods Thirty-nine patients with clinical diagnosis of chronic renal injury (RI group) who underwent routine renal MRI and SWI examination were retrospectively analyzed. They were divided into mild injured group (15 cases) and moderate to severe injured group (24 cases) by estimated glomerular filtration rate (eGFR). At the same time, 17 volunteers without chronic renal injury who had normal serum creatinine (Scr) and blood urea nitrogen were recruited as control group. All subjects underwent routine renal MRI and SWI examination. The ratios of cortex to medulla were measured and calculated in both kidneys' magnitude image and susceptibility weighted image, which were indicated as C/MMAG and C/MSWI. Independent sample t test was used to compare the differences of C/MMAG and C/MSWI between control group and RI group, and paired sample t test was used to compare the differences between C/MMAG and C/MSWI in each group. One-way ANOVA was used to compare the difference of C/MMAG and C/MSWI between the control group and the different RI groups. ROC was employed to assess the diagnostic efficacy of C/MMAG and C/MSWI in renal injury. Pearson linear correlation analysis was used to evaluate the correlation between C/MMAG, C/MSWI and eGFR, Scr in patients with renal injury. Results The C/MMAG and C/MSWI in the RI group were 1.101±0.039 and 1.071±0.046, respectively. C/MSWI was obviously lower than C/MMAG, and the difference was statistically significant (t=5.056, P 0.05). The C/MMAG and C/MSWI in the RI group were obviously lower than those in the control group, and the difference was statistically significant (t=4.564, 6.122;P 0.05). The area under ROC of C/MMAG and C/MSWI in diagnosis of renal injury were 0.853 and 0.952, respectively. C/MMAG was positively correlated with eGFR (r=0.460,P<0.01). Conclusions Susceptibility-weighted imaging can be used to assess chronic renal injury. Although it cannot reflect the degree of renal function damage, it has some value in the early diagnosis of mild renal injury. Key words: Kidney failure,chronic; Anoxia; Magnetic resonance imaging

The value of susceptibility weighted imaging in evaluating ischemia-reperfusion injury of the rabbit kidney

Objective To explore the value of susceptibility weighted imaging (SWI) in the quantitative analysis of ischemia- reperfusion injury (IRI) of the rabbit kidneys. Methods Thirty New Zealand white rabbits were randomly assigned to IRI group (n=24, operation with clamping) and Sham group (n=6, operation without clamping). Left renal ischemia-reperfusion was performed by occlusion (calmping) of the left renal arterial for 60 minutes, followed by reperfusion. All the rabbits underwent MRI including T2WI and SWI before and 0.5 h, 12 h, 24 h and 48 h after the establishments of models. Three rabbits in IRI group were randomly sacrificed 0.5 h, 12 h, and 24 h after the establishment of model. The rest of the rabbits in IRI group and 6 rabbits in sham group were sacrificed for pathological examination 48 h after the establishment of model All specimen were cut into slices and stained with hematoxylin-eosin (HE). Region of interest (ROI) was manually created by outlining the inner medulla, inner stripe of outer medulla, outer stripe of outer medulla, and cortex, then relative signal-to-noise ratio of the kidney (rSNR) to muscle in SWI sequence was recorded. and compared with histopathologic features. One- way ANOVA was performed to compare difference of rSNR to muscle in respective location at 5 time-points between Sham group and IRI group, and the differences between groups were tested using repetitive measure analysis of variance, repetitive measure analysis of variance was performed to compare difference of rSNR to muscle in respective location at respective time- points between Sham group and IRI group. Results rSNR value in the inner medulla 0.5 h, 12 h, 24 h and 48 h after the establishments of models were 0.28±0.04, 0.98±0.14, 0.69±0.07, 0.57±0.06, 0.43±0.03, respectively (F=69.82,P<0.01), the inner stripe of outer medulla at the five timepoints 0.08±0.03, 0.57±0.05, 0.32±0.07, 0.16±0.02, 0.04±0.01, respectively (F=16.59,P<0.01), the outer stripe of outer medulla were 0.31±0.04, 0.86±0.09, 0.65±0.07, 0.55±0.06 0.43±0.04 (F=67.52,P<0.01), respectively,the cortex 0.05±0.01, 0.80±0.04, 0.68±0.07, 0.47±0.07, 0.36±0.08, respectively (F=118.96, P< 0.01). The difference of the rSNR was statistically significant in the inner medulla, inner stripe of outer medulla, outer stripe of outer medulla, and cortex at the five different time-points. The differences between two groups were significant (F=206.29, 14.25, 42.8, 39.12,P all<0.05). The pathological findings in Sham group included normalglomerular structure l, clear cavity of tubular, no interstitial hyperemia and edema. The pathological findings in IRI group demonstated, at 0.5 h after IRI, Bowman's capsule cavity expansion, glomerular shrinkage, swelling of renal tubular epithelial cells, vacuoles degeneration, the tube cavity expansion, interstitial edema and congestion ecta became slender, andat 12 h after IR, Bowman's capsule expansion became more obvious, foam degeneration of renal tubular epithelial cells, apoptosis, partial loss of the brush border of the proximal convoluted tubule, formation of protein cast, and a small amount of inflammatory cells appeared in the renal interstitium, swelling of endothelial cells of the vasa recta, congestion of small vessels, and at 24 and 48 h after IRI, more serious injury of renal tubular in the outer stripe of outer medulla , massive necrosis of renal tubular epithelial cells, apoptosis, parts of the renal tubular had the contour lines, and renal tubular outline, increment in inflammatory cells, red cell and protein cast. Conclusion rSNR of SWI in the inner medulla, inner stripe of outer medulla, outer stripe of outer medulla, and cortex of the kidney varies with the degree of IRI over time, and is consistent with corresponding pathological feature, suggesting SWI is useful imaging tool to detect early damage of renal IRI quantitatively. Key words: Reperfusion injury; Magnetic resonance imaging; Pathology

Susceptibility-weighted magnetic resonance imaging for the evaluation of deep infiltrating endometriosis: preliminary results.

Knowledge of the precise sites of deep infiltrating endometriosis (DIE) lesions is essential for preoperative workup and treatment. Susceptibility-weighted imaging (SWI) has high sensitivity for blood products and have recently been applied in abdominal imaging. To determine the value of SWI in the diagnosis of DIE. Forty-three clinically suspected DIE patients with sonographically diagnosed ovarian endometriomas who had tenderness or palpable nodule(s) on rectovaginal examination were referred to pelvic magnetic resonance imaging (MRI) including SWI. Two patients were excluded from the study because of low quality of SWI series. Twenty-eight patients who were offered laparoscopic endometriosis surgery (LES) preferred medical treatment over surgical approach. Thirteen out of 41 participants had LES. Lesions were evaluated for their locations, signal intensities on T1-weighted (T1W) and T2-weighted (T2W) images, and presence of signal voids on SWI using 3T MRI and correlated with LES findings. A total of 18 endometriosis foci were laparoscopically removed from 13 patients. DIE lesions removed at laparoscopy were located at the uterosacral ligament (9/18), rectovaginal region (4/18), retrocervical region (2/18), and fallopian tubes (3/18). Eleven out of 18 (61%) DIE foci were detected by their high-signal intensities on T1W images whereas 16 out of 18 (89%) DIE foci were detected by signal voids on SWI. SWI imaging with its high sensitivity to blood products, contributes to the diagnosis of DIE by depicting different phases of hemorrhage not seen by conventional MRI sequences.

MR susceptibility-weighted imaging in staging hepatic fibrosis of rabbits

Objective To assess the value of susceptibility-weighted imaging (SWI) in staging hepatic fibrosis (HF) in rabbits. Methods Sixty healthy rabbits were randomly divided into HF group (n=44), control group (n=16). Rabbits in the HF group and supplementary group were injected subcutaneously with 50% CCl4 oily solution to establish hepatic fibrosis model. On the basis of preliminary test, 8 rabbits in the HF group and 4 rabbits in the control group were selected randomly at the 4th, 5th, 6th, 10th week after CCL4 injection ,respectively , to undergo liver MR scan, including conventional axial T1WI, T2WI and axial SWI, DWI scan. All rabbits were sacrificed after MR scan and the tissue of liver were sampled for pathological test and hepatic fibrosis staging. Rabbits were classified into group F0, F1-2 and F3-4 based on pathological results. Liver signal intensity (SI), and liver-to-muscle SI ratio were measured on SWI images and ADC values were measured on DWI images correspondently. One-way ANOVA analysis was performed to compare difference in liver SI, liver-to-muscle SI ratio and ADC values among group F0 (no fibrosis), F1-2 (mild-moderate fibrosis) and F3-4 (severe fibrosis) . Spearman correlation analysis was performed to correlate pathological staging and liver SI, liver-to-muscle SI ratio and ADC values. Receiver operating characteristic (ROC) curve analysis was performed to compare the diagnostic performance of SWI and DWI for staging HF. Results Two and 5 rabbits in the HF group died at the 5th and the 6th week after CCL4 injection , respectively due to acute hepatic necrosis, hepatorrhexis and systemic failure. Seven rabbits in supplementary group were used as supplement. Of the 16 rabbits in the control group, 1 was excluded from the study due to liver fibrosis. Fifteen rabbits in group F0, sixteen rabbits in group F1-2 and sixteen rabbits in group F3-4 underwent MRI and were included into this study. Liver-to-muscle SI ratio in group F0, F1-2 and F3-4 were 0.973±0.020, 0.880±0.090 and 0.649±0.140, respectively. Liver SI were 378±45, 374±19 and 317±34. ADC values were (1.473±0.320) ×10-3, (1.311±0.310) ×10-3 and (0.942±0.180) ×10-3mm2/s. There were statistically significant differences in liver SI, liver-to-muscle SI ratio and ADC values among group F0, F1-2 and F3-4 (F=46.571,15.803 and 15.317,P< 0.01). Liver-to-muscle SI ratio was highly negatively correlated with HF staging (r=-0.818,P<0.01), while liver SI and ADC values were moderately correlated with HF staging (r=-0.565, -0.630;P<0.01). Area under ROC curve (AUC) of liver-to-muscle SI ratio, liver SI and ADC value for differentiating hepatic fibrosis stage F0 and stage F1-4 were 0.916, 0.695 and 0.768, while the AUC for differentiating hepatic fibrosis stage F0-2 and stage F3-4 were 0.951, 0.904 and 0.900. Conclusion Liver-to-muscle SI ratio on SWI provide added diagnostic value and could be an useful parameter for staging hepatic fibrosis. Key words: Liver fibrosis; Liver cirrhosis; Magnetic resonance imaging

Value of MR susceptibility weighted imaging for characterization of small hepatocellular carcinoma in cirrhotic livers

Objective To investigate the value of susceptibility-weighted imaging (SWI) for characterization of small hepatocellular carcinoma (sHCC) in cirrhotic livers. Methods Two hundred seventy-two patients suspiciousof HCC underwent conventional MR imaging and susceptibility-weighted imaging (SWI). Two hundred and five patients were excluded due to either size larger than 3.0 cm, no cirrhosis or HCC. Finally, a total of 84 hepatocellular nodules in 67 patients were included in this prospective study. There were 22 DNs in 12 cases, 8 DNs with HCC foci in 7 cases, and 54 overt HCCs in 48 cases. Two abdominal radiologists independently evaluated signal intensity and enhancing pattern using conventional MRI set and conventional MRI combining with SWI set. A five-point scale was performed to evaluate diagnostic confidence of HCC. Kappa analysis was performed to assess interobserver agreement of the two sets by two readers.The diagnostic performance and confidence level were compared for each image set,ROC was used to evaluate the diagnostic efficiency. Results Good interobserver agreement was identified with a Kappa value of 0.923 for conventional MRI set and 0.865 for conventional MRI combining with SWI set, respectively. The diagnostic sensitivity, specificity, accuracy, and area under the alternative-free response ROC (Az) were 80.6% and 80.6%, 81.8% and 77.3%, 81.0% and 79.8%, 0.804 and 0.782 using conventional MRI set, and 93.5% and 85.5%, 90.9% and 86.4%, 92.9% and 85.7%, 0.898 and 0.859 using conventional MRI combining with SWI set for reader 1 and reader 2, respectively.The diagnostic confidence level of conventional MRI combining with SWI set for diagnosis of HCC with less than 2 cm in size(n=36) was significantly higher than that of conventional MRI (reader 1, 3.86±0.47 vs 3.40±0.91;reader 2, 3.85±0.57 vs 3.41±0.92;t values were 3.733 and 2.468, P were 0.001 and 0.018). Conclusion SWI can provide additional valuable information and improve diagnostic performance for characterization of sHCC in cirrhotic livers. Key words: Liver tumor; Cirrhosis; Magnetic resonance imaging

The value of susceptibility-weighted imaging (SWI) in patients with non-neonatal hypoxic-ischemic encephalopathy

ObjectiveIn susceptibility-weighted imaging (SWI) in the normal brain, cortical veins appear hypointense due to paramagnetic properties of deoxy-hemoglobin. Global cerebral anoxia decreases cerebral oxygen metabolism, thereby increasing oxy-hemoglobin levels in cerebral veins. We hypothesized that a lower cerebral oxygen extraction fraction in comatose patients with non-neonatal hypoxic-ischemic encephalopathy (IHE) produces a pattern of global rarefied or pseudo-diminished cortical veins due to higher oxy-hemoglobin. Purpose(1) To investigate the topographic relationship between susceptibility effects in cortical veins and related diffusion restrictions on diffusion-weighted imaging (DWI) in patients with IHE. (2) To relate imaging findings to patterns of altered resting activity on surface EEG. MethodsTwenty-three IHE patients underwent MRI. EEG patterns were used to classify the depth of coma. Regional vs. global susceptibility changes on SWI and patterns of DWI restrictions were compared with the depth of coma. ResultsAll patients exhibited areas of restricted cortical diffusion and SWI abnormalities. The dominant DWI restrictions encompassed widespread areas along the precuneus, frontal and parietal association cortices and basal ganglia. For SWI, nineteen patients had generalized bi-hemispherical patterns, the EEG patterns correlated with coma grades III–V. Four patients had focal decreases of deoxy-hemoglobin following DWI restrictions; associated with normal EEGs. ConclusionFocal patterns of diamagnetic effects on SWI according to relative decreases in deoxy-hemoglobin due to reduced metabolic demand are associated with normal EEG in IHE patients. Global patterns indicated increased depth of coma and widespread cortical damage. Clinical relevanceThe results indicate a potential diagnostic value of SWI in patients with IHE.

Susceptibility weighted imaging and diffusion weighted imaging in diagnostic and prognostic evaluation of diffuse axonal injury

Objective To assess the diagnostic value of susceptibility weighted imaging (SWIl)and diffusion weighted imaging (DWI) for diffuse axonal injury (DAI) and their correlation with evaluation of injury severity and outcome.Methods Forty-nine patients with clinically diagnosed DAI underwent routine T1WI,T2WI,DWI,and SWI scanning.Respective signal characteristics and distribution features were detected.Number and volume of DAI lesions detected in each sequence were compared and analyzed for correlation with Glasgow coma score (GCS) and Glasgow outcome score (GOS).Results By contrast,SWI provided relatively better detection of intracranial micro-hemorrhage lesions (P ＜ 0.01),while DWI attained better presented edema lesions (P ＜ 0.01).Lesion volumes on SWI and DWI were significantly higher than those on TIWI and T2WI,but they were significantly different in Mann-Whitney test (P ＜ 0.01).SWI lesion number and volume,DWI lesion number as well as major lesion number at vulnerable zones of alba,cortex-medullar junction,cerebellum,brain stem,corpus callosum,and basal ganglia were negatively correlated with GCS on admission,GCS at 1 hour before examination and GOS at follow-up (P ＜ 0.05).Moreover,DWI lesion volume showed negative relation to GCS at 1 hour before examination and GOS at follow-up (P ＜ 0.01).Conclusion SWI and DWI can be pretty sensitive and effective to detect intracranial micro-hemorrhage and edema lesions in posttraumatic DAI patients and hence offer more help for early diagnosis and treatment of DAI as well as outcome evaluation. Key words: Diffuse axonal injury; Magnetic resonance imaging; Cerebral microbleeds

An attempt toward objective assessment of brain tumor vascularization using susceptibility weighted imaging and dedicated computer program – a preliminary study

SummaryBackground:Susceptibility weighted imaging (SWI) is a novel MRI sequence which demonstrates the susceptibility differences between adjacent tissues and it is promising to be a sequence useful in the assessment of brain tumors vascularity. The aim of our study was to demonstrate usefulness of SWI in evaluation of intratumoral vessels in comparison to CET1 sequence in a standardized, objective manner.Material/Methods:10 patients with supratentorial brain tumors were included in the study. All of them underwent conventional MRI examination with a 1,5 T scanner. SWI sequence was additionally performed using the following parameters: TR 49 ms,TE 40 ms. We used authors’ personal computer software – Vessels View, to assess the vessels number.Results:Comparison of SWI and CET1 sequences was performed using our program. Analysis of all 26 ROIs demonstrated predominance of SWI in the amount of white pixels (vessel cross-sectional) and a similar number of elongated structures (blood vessels).Conclusions:To conclude, the results of this study are encouraging; they confirm the added value of SWI as an appropriate and useful sequence in the process of evaluation of intratumoral vascularity. Using our program significantly improved visualization of blood vessels in cerebral tumors. The Vessel View application assists radiologists in demonstrating the vessels and facilitates distinguishing them from adjacent tissues in the image.

Susceptibility-weighted imaging: The value in cerebral astrocytomas grading

To investigate the value of susceptibility weighted imaging (SWI) in evaluating the histopathologic grade of cerebral astrocytomas and compare the relative value of SWI and conventional magnetic resonance imaging (MRI) sequences. This is an analysis of 26 untreated patients with pathologically confirmed astrocytomas. The tumors were classified as low grade (grade I-II: 12 cases) or high grade (grade III-IV: 14 cases). Imaging was performed with a 3.0 T MRI scanner. Conventional sequences [T1-weighted imaging (T1WI), contrast enhanced T1WI (CE-T1WI), T2-weighted imaging (T2WI), and T2 FLuid Attenuated Inversion Recovery (T2FLAIR)] and SWI sequence (including CE-SWI) were done. The number of small vessels and the amount of blood products in the tumors were determined for each sequence. Differences between the two groups were analyzed statistically. SWI was more sensitive than conventional sequences (T1WI, CE-T1WI, T2WI, and T2FLAIR) in visualizing small vessels and microhemorrhages in cerebral astrocytomas (P < 0.01). CE-SWI was better than CE-T1WI sequences for visualizing tumor small vessels and microhemorrhages. SWI visualized greater numbers of small vessels and areas of microhemorrhages in high-grade tumors than in low-grade tumors (P < 0.01). This was especially true after contrast administration (P < 0.01). SWI plays an important role in astrocytoma grading, especially for enhanced astrocytomas after contrast injection. CE-SWI was better than CE-T1WI in visualizing tumor architecture.

Diagnostic value of susceptibility-weighted imaging for intracranial cavernous hemangioma

To explore the diagnostic value of susceptibility weighted imaging (SWI) for intracranial cavernous hemangioma.The magnetic resonance sequences of SWI,conventional imaging (MRI) and diffusion-weighted imaging (DWI) were performed in 37 patients of intracranial cavernous hemangioma to compare their different imaging capacities.Among them,the number of lesions found on T1WI,T2WI,DWI and SWI sequences were 40,41,42 and 50 respectively.Thus SWI may detect regular MRI negative or smaller lesions of intracranial cavernous hemangioma. Key words: Magnetic resonance imaging ; Hemangioma, cavernous, central, nervous system

Cerebral Thromboembolism: Value of Susceptibility-Weighted Imaging in the Initial Diagnosis of Acute Infarction

Susceptibility-weighted imaging (SWI) is commonly used to diagnose cerebral hemorrhage, calcification, and other T2* lesions. Its role in the detection of cerebral thromboemboli has been suggested for emboli of the anterior division of the middle cerebral artery (MCA). The purpose of our study was to determine SWI's accuracy and sensitivity in detection of all sites of cerebral thromboemboli, not just MCA emboli. Two neuroradiologists retrospectively reviewed consecutive MRI brain examinations with SWI for cerebral thromboemboli in 100 patients with clinical suspicion for stroke determined by the NIH Stroke Scale (NIHSS) score. FLAIR, MRA, CT, and catheter angiography were reviewed for thromboemboli in the same patients. Thromboembolic sites included: the internal carotid artery (ICA) terminus, anterior MCA, posterior MCA, any other cerebral artery, or if not present. The exclusion criteria included: no magnetic resonance angiogram (MRA) or catheter angiogram for comparison, lack of restricted diffusion, lacunar infarcts, and the presence of massive hemorrhage. The accuracy, sensitivity, and specificity of each imaging modality were determined. Twenty-four patients were excluded based on the aforementioned criteria. Cerebral thromboemboli were identified in 35 of the remaining 76 patients. Of the 35 patients with thromboemboli, 30 were identified on SWI. FLAIR detected 22/35 emboli, MRA 30/33, CT 18/35, and catheter angiography 12/12. The accuracies for SWI, FLAIR, and CT were 97%, 84%, and 74%, respectively. The sensitivities for SWI, FLAIR, and CT were 85%, 61%, and 52%, respectively. The specificities for SWI, FLAIR, and CT were 100%, 98%, and 93%, respectively. There is an adjunctive role of SWI to identify cerebral thromboemboli in patients with acute infarction. SWI is superior to FLAIR and CT, and complementary to MRA and catheter angiography in emboli detection. This study supports SWI detection of MCA emboli, but also emphasizes its utility in emboli detection of other arteries based on a high accuracy and sensitivity.