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Objective:To evaluate the clinical value of 5.0 T ultra-high filed MRI system in assessing intracranial arteries segments and vessel branchers.Methods:This study was a prospective study. Totally 40 consecutive healthy volunteers were recruited from Zhongshan Hospital, Fudan University from September 1, 2021 to November 30, and all participants who underwent either 3.0 T or 5.0 T time-of-flight MR angiography (TOF-MRA) in random order were divided into 3.0 T MR group and 5.0 T MR group with 20 volunteers for each group. Image quality was assessed by Likert 5 scoring systems and signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR),and score in visualization of intracranial arteries [middle cerebral artery (MCA) and its segments, anterior cerebral artery (ACA) and its segments, posterior cerebral artery (PCA) and its segments, lenticulostriate arteries (LA) and pontine artery (PA)] were assessed from 0 to 3 (≥2: good depiction of vessel segment). Quantitative indicators were compared between 2 groups using independent t test or Mann-Whitney U test. Results:Among the 40 subjects, there were 29 males and 11 females, aged 20-69 (50±12) years. SNR and CNR were both significantly higher in 5.0 T MR group than those in 3.0 T MR group (SNR: 187±9 vs 91±4, t=31.59, P<0.001; CNR: 156±7 vs 70±4, t=31.45, P<0.001), but there was no significant difference in subjective scores of image quality between the 5.0 T MR and 3.0 T MR groups [5.0 (4.0, 5.0), 5.0 (5.0, 5.0) points, respectively, Z=-1.23, P=0.218]. In the evaluation of cerebral arteries, the visualizations of the proximal and middle segments of MCA, ACA and PCA was better than those in the 3.0 T MR group, and there was no significant difference in the scores ( P>0.05), while the visualizations of proximal arteries in the 5.0 T MR group were significantly better than those in the 3.0 T MR group ( P<0.05). Furthermore, small vessel branches such as LA and PA in 5.0 T MR group were visualized better than those in 3.0 T MR group ( P<0.001). Conclusion:TOF-MRA by ultra-high filed 5.0-T provides an optimal choice in visualization of distal large arteries and small vessel branches, which could be useful for the diagnosis on cerebral vascular disease.
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OBJECTIVE: To assess the feasibility of susceptibility-weighted imaging (SWI) while monitoring changes in renal oxygenation level after water loading. MATERIALS AND METHODS: Thirty-two volunteers (age, 28.0 +/- 2.2 years) were enrolled in this study. SWI and multi-echo gradient echo sequence-based T2* mapping were used to cover the kidney before and after water loading. Cortical and medullary parameters were measured using small regions of interest, and their relative changes due to water loading were calculated based on baseline and post-water loading data. An intraclass correlation coefficient analysis was used to assess inter-observer reliability of each parameter. A receiver operating characteristic curve analysis was conducted to compare the performance of the two methods for detecting renal oxygenation changes due to water loading. RESULTS: Both medullary phase and medullary T2* values increased after water loading (p 0.05). Interobserver reliability was excellent for the T2* values, good for SWI cortical phase values, and moderate for the SWI medullary phase values. The area under receiver operating characteristic curve of the SWI medullary phase values was 0.85 and was not different from the medullary T2* value (0.84). CONCLUSION: Susceptibility-weighted imaging enabled monitoring changes in the oxygenation level in the medulla after water loading, and may allow comparable feasibility to detect renal oxygenation level changes due to water loading compared with that of T2* mapping.
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Adult , Female , Humans , Male , Young Adult , Kidney/metabolism , Magnetic Resonance Imaging/methods , Oxygen/blood , ROC Curve , Reproducibility of Results , Water/administration & dosageABSTRACT
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.
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Objective To investigate imaging characteristics of multistep hepatocarcinogenesis in cirrhotic livers on susceptibility-weighted imaging (SWI).Methods Seventy-three patients with 83 nodules in cirrhotic livers underwent hepatic MR imaging with SWI.Two radiologists reviewed MR images by consensus.Imaging characteristics of dysplastic nodules (DN),DN with malignant foci and hepatocellular carcinoma (HCC) were evaluated.Prussian blue staining was performed for semiquantification of hepatic iron content and above cirrhosis-associated nodules.Results Positive iron staining of background liver parenchyma was found in 69 of 73 patients and 4 HCC patients showed iron-negative staining of background liver parenchyma.Nine DNs appeared as hypointensity or isointensity with pathologically confirmed similar (n =7) or slightly decreased (n =2) iron deposition compared with background liver parenchyma.SWI detected 14 of 15 DNs with malignant foci.Seven patients appeared as homogeneous hyperintensity and 1 patient appeared as heterogeneous hyperintensity due to intratumoral hemorrhages.The remaining 6 patients demonstrated as nodule-in-nodule appearance with iron deposition in all background nodules,iron deposition with grade 1 in one internal HCC foci,and iron-free in 5 internal HCC foci.The remaining 50 patients with hepatic iron deposition had 55 HCC lesions.Three HCC lesions had iron deposition with grade 1 to 2 and the remaining 52 HCC lesions were pathologically iron-resistant.HCC appeared as hyperintensity compared with siderotic surrounding liver parenchyma.However,HCCs with diameter larger than 3 cm usually demonstrated heterogeneous hyperintensity due to intratumoral hemorrhage.Conclusions SWI could accurately demonstrate dynamic iron depletion on multistep hepatocarcinogenesis in cirrhotic livers.On SWI images,DNs appear as hypointensity due to siderosis and malignant nodules appear as hyperintensity due to iron depletion.