BACKGROUND Indentifying predictive factors for postoperative recurrence of hepatocellular carcinoma(HCC)has great significance for patient prognosis.AIM To explore the value of gadolinium ethoxybenzyl diethylenetriami...BACKGROUND Indentifying predictive factors for postoperative recurrence of hepatocellular carcinoma(HCC)has great significance for patient prognosis.AIM To explore the value of gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid(Gd-EOB-DTPA)enhanced magnetic resonance imaging(MRI)combined with clinical features in predicting early recurrence of HCC after resection.METHODS A total of 161 patients with pathologically confirmed HCC were enrolled.The patients were divided into early recurrence and non-early recurrence group based on the follow-up results.The clinical,laboratory,pathological results and Gd-EOB-DTPA enhanced MRI imaging features were analyzed.RESULTS Of 161 patients,73 had early recurrence and 88 were had non-early recurrence.Univariate analysis showed that patient age,gender,serum alpha-fetoprotein level,the Barcelona Clinic Liver Cancer stage,China liver cancer(CNLC)stage,microvascular invasion(MVI),pathological satellite focus,tumor size,tumor number,tumor boundary,tumor capsule,intratumoral necrosis,portal vein tumor thrombus,large vessel invasion,nonperipheral washout,peritumoral enhancement,hepatobiliary phase(HBP)/tumor signal intensity(SI)/peritumoral SI,HBP peritumoral low signal and peritumoral delay enhancement were significantly associated with early recurrence of HCC after operation.Multivariate logistic regression analysis showed that patient age,MVI,CNLC stage,tumor boundary and large vessel invasion were independent predictive factors.External data validation indicated that the area under the curve of the combined predictors was 0.861,suggesting that multivariate logistic regression was a reasonable predictive model for early recurrence of HCC.CONCLUSION Gd-EOB-DTPA enhanced MRI combined with clinical features would help predicting the early recurrence of HCC after operation.展开更多
AIM To optimize the hepatobiliary phase delay time(HBPDT) of Gd-EOB-DTPA-enhanced magnetic resonance imaging(GED-MRI) for more efficient identification of hepatocellular carcinoma(HCC) occurring in different degrees o...AIM To optimize the hepatobiliary phase delay time(HBPDT) of Gd-EOB-DTPA-enhanced magnetic resonance imaging(GED-MRI) for more efficient identification of hepatocellular carcinoma(HCC) occurring in different degrees of cirrhosis assessed by Child-Pugh(CP) score.METHODS The liver parenchyma signal intensity(LPSI), the liver parenchyma(LP)/HCC signal ratios, and the visibility of HCC at HBP-DT of 5, 10, 15, 20, and 25 min(i.e., DT-5, DT-10, DT-15, DT-20, and DT-25) after injection of GdEOB-DTPA were collected and analyzed in 73 patients with cirrhosis of different degrees of severity(including 42 patients suffering from HCC) and 18 healthy adult controls.RESULTS The LPSI increased with HBP-DT more significantly in the healthy group than in the cirrhosis group(F = 17.361, P < 0.001). The LP/HCC signal ratios had a significant difference(F = 12.453, P < 0.001) among various HBP-DT points, as well as between CP-A and CP-B/C subgroups(F = 9.761, P < 0.001). The constituent ratios of HCC foci identified as obvious hypointensity(+++), moderate hypointensity(++), and mild hypointensity or isointensity(+/-) kept stable from DT-10 to DT-25: 90.6%, 9.4%, and 0.0% in the CP-A subgroup; 50.0%, 50.0%, and 0.0% in the CP-B subgroup; and 0.0%, 0.0%, and 100.0% in the CP-C subgroup, respectively.CONCLUSION The severity of liver cirrhosis has significant negative influence on the HCC visualization by GED-MRI. DT-10 is more efficient and practical than other HBP-DT points to identify most of HCC foci emerging in CP-A cirrhosis, as well as in CP-B cirrhosis; but an HBP-DT of 15 min or longer seems more appropriate than DT-10 for visualization of HCC in patients with CP-C cirrhosis.展开更多
AIM: To compare the diagnostic accuracy of pelvic phased-array magnetic resonance imaging (MRI) and endorectal ultrasonography (ERUS) in the preoperative staging of rectal carcinoma. METHODS: Thirty-four patients (15 ...AIM: To compare the diagnostic accuracy of pelvic phased-array magnetic resonance imaging (MRI) and endorectal ultrasonography (ERUS) in the preoperative staging of rectal carcinoma. METHODS: Thirty-four patients (15 males, 19 females) with ages ranging between 29 and 75 who have biopsy proven rectal tumor underwent both MRI and ERUS examinations before surgery. All patients were evaluated to determine the diagnostic accuracy of depth of transmural tumor invasion and lymph node metastases. Imaging results were correlated with histopathological findings regarded as the gold standard and both modalities were compared in terms of predicting preoperative local staging of rectal carcinoma. RESULTS: The pathological T stage of the tumors was: pT1 in 1 patient, pT2 in 9 patients, pT3 in 21 patients and pT4 in 3 patients. The pathological N stage of the tumors was: pN0 in 19 patients, pN1 in 9 patients and pN2 in 6 patients. The accuracy of T staging for MRI was 89.70% (27 out of 34). The sensitivity was 79.41% and the specificity was 93.14%. The accuracy of T staging for ERUS was 85.29% (24 out of 34). The sensitivity was 70.59% and the specificity was 90.20%. Detection of lymph node metastases usingphased-array MRI gave an accuracy of 74.50% (21 out of 34). The sensitivity and specificity was found to be 61.76% and 80.88%, respectively. By using ERUS in the detection of lymph node metastases, an accuracy of 76.47% (18 out of 34) was obtained. The sensitivity and specificity were found to be 52.94% and 84.31%, respectively. CONCLUSION: ERUS and phased-array MRI are complementary methods in the accurate preoperative staging of rectal cancer. In conclusion, we can state that phased-array MRI was observed to be slightly superior in determining the depth of transmural invasion (T stage) and has same value in detecting lymph node metastases (N stage) as compared to ERUS.展开更多
AIM To evaluate the diagnostic value of gadobenate dimeglumine(Gd-BOPTA)-enhanced hepatocyte-phase magnetic resonance imaging(MRI) in evaluating hepatic fibrosis and hepatitis.METHODS Hepatocyte-phase images of Gd-BOP...AIM To evaluate the diagnostic value of gadobenate dimeglumine(Gd-BOPTA)-enhanced hepatocyte-phase magnetic resonance imaging(MRI) in evaluating hepatic fibrosis and hepatitis.METHODS Hepatocyte-phase images of Gd-BOPTA-enhanced MRI were retrospectively evaluated in 76 patients with chronic liver disease. These patients were classified into five groups according to either the histopathological fibrosis stage(S0-S4) or the histopathological hepatitis grade(G0-G4). The relative enhancement ratio(RE) of the liver parenchyma in the T1-vibe sequence was calculated by measuring the signal intensity before(SI pre) and 90 min after(SI post) intravenous injection of Gd-BOPTA using the following formula: RE =(SI post-SI pre)/SI pre. One-way analysis of variance was used to compare the difference between the relative RE in the hepatocyte phase(REh) and the stage of hepatic fibrosis and the grade of hepatitis. Pearson's productmoment correlation analysis was used to evaluate the relationship between the REh and the levels of serologic liver functional parameters.RESULTS According to histopathological hepatic fibrosis stage, the 76 patients were classified into five groups: 16 in S0, 15 in S1, 21 in S2, 9 in S3, and 15 in S4 group. According to histopathological hepatitis grade, the 76 patients were also classified into five groups: 0 in G0, 44 in G1, 22 in G2, 8 in G3, and 2 in G3 group. With regard to the stage of hepatic fibrosis, REh showed significant differences between the S2 and S3 groups and between the S2 and S4 groups(P < 0.05), but no significant difference was observed between the other groups. With regard to the grade of hepatitis, REh showed significant differences between the G1 and G2 groups and between the G1 and G4 groups(P < 0.05), but no significant difference was observed between the other groups. Increased REh showed correlations with decreased serum levels of TB, ALT and AST(P < 0.05). CONCLUSION To some extent, measuring the REh using Gd-BOPTAenhanced MRI might be a noninvasive technique for assessing the stage of hepatic fibrosis. This method is able to differentiate no/mild hepatitis from advanced hepatitis. TB, ALT and AST levels can predict the degree of liver enhancement in the hepatocyte phase of Gd-BOPTA-enhanced MRI.展开更多
In this paper, an approach to the design of shielded radio-frequency (RF) phased-array coils for magnetic resonance imaging (MRI) is proposed. The target field method is used to find current densities distributed ...In this paper, an approach to the design of shielded radio-frequency (RF) phased-array coils for magnetic resonance imaging (MRI) is proposed. The target field method is used to find current densities distributed on primary and shield coils. The stream function technique is used to discretize current densities and to obtain the winding patterns of the coils. The corresponding highly ill-conditioned integral equation is solved by the Tikhonov regularization with a penalty function related to the minimum curvature. To balance the simplicity and smoothness with the homogeneity of the magnetic field of the coll's winding pattern, the selection of a penalty factor is discussed in detail.展开更多
Since its introduction in the 1970’s,magnetic resonance imaging(MRI)has become a standard imaging modality.With its broad and standardized application,it is firmly established in the clinical routine and an essential...Since its introduction in the 1970’s,magnetic resonance imaging(MRI)has become a standard imaging modality.With its broad and standardized application,it is firmly established in the clinical routine and an essential element in cardiovascular and abdominal imaging.In addition to sonography and computer tomography,MRI is a valuable tool for diagnosing cardiovascular and abdominal diseases,for determining disease severity,and for assessing therapeutic success.MRI techniques have improved over the last few decades,revealing not just morphologic information,but functional information about perfusion,diffusion and hemodynamics as well.Four-dimensional(4D)flow MRI,a time-resolved phase contrast-MRI with three-dimensional(3D)anatomic coverage and velocity encoding along all three flow directions has been used to comprehensively assess complex cardiovascular hemodynamics in multiple regions of the body.The technique enables visualization of 3D blood flow patterns and retrospective quantification of blood flow parameters in a region of interest.Over the last few years,4D flow MRI has been increasingly performed in the abdominal region.By applying different acceleration techniques,taking 4D flow MRI measurements has dropped to a reasonable scanning time of 8 to 12 min.These new developments have encouraged a growing number of patient studies in the literature validating the technique’s potential for enhanced evaluation of blood flow parameters within the liver’s complex vascular system.The purpose of this review article is to broaden our understanding of 4D flow MRI for the assessment of liver hemodynamics by providing insights into acquisition,data analysis,visualization and quantification.Furthermore,in this article we highlight its development,focussing on the clinical application of the technique.展开更多
BACKGROUND Synthetic magnetic resonance imaging(MRI)MAGnetic resonance imaging compilation(MAGiC)is a new MRI technology.Conventional T1,T2,T2-fluidattenuated inversion recovery(FLAIR)contrast images,quantitative imag...BACKGROUND Synthetic magnetic resonance imaging(MRI)MAGnetic resonance imaging compilation(MAGiC)is a new MRI technology.Conventional T1,T2,T2-fluidattenuated inversion recovery(FLAIR)contrast images,quantitative images of T1 and T2 mapping,and MAGiC phase sensitive inversion recovery(PSIR)Vessel cerebrovascular images can be obtained simultaneously through post-processing at the same time after completing a scan.In recent years,studies have reported that MAGiC can be applied to patients with acute ischemic stroke.We hypothesized that the synthetic MRI vascular screening scheme can evaluate the degree of cerebral artery stenosis in patients with acute ischemic stroke.AIM To explore the application value of vascular images obtained by synthetic MRI in diagnosing acute ischemic stroke.METHODS A total of 64 patients with acute ischemic stroke were selected and examined by MRI in the current retrospective cohort study.The scanning sequences included traditional T1,T2,and T2-FLAIR,three-dimensional time-of-flight magnetic resonance angiography(3D TOF MRA),diffusion-weighted imaging(DWI),and synthetic MRI.Conventional contrast images(T1,T2,and T2-FLAIR)and intracranial vessel images(MAGiC PSIR Vessel]were automatically reconstructed using synthetic MRI raw data.The contrast-to-noise ratio(CNR)values of traditional T1,T2,and T2-FLAIR images and MAGiC reconstructed T1,T2,and T2-FLAIR images in DWI diffusion restriction areas were measured and compared.MAGiC PSIR Vessel and TOF MRA images were used to measure and calculate the stenosis degree of bilateral middle cerebral artery stenosis areas.The consistency of MAGiC PSIR Vessel and TOF MRA in displaying the degree of vascular stenosis with computed tomography angiography(CTA)was compared.RESULTS Among the 64 patients with acute ischemic stroke,79 vascular stenosis areas showed that the correlation between MAGiC PSIR Vessel and CTA(r=0.90,P<0.01)was higher than that between TOF MRA and CTA(r=0.84,P<0.01).With a degree of vascular stenosis>50%assessed by CTA as a reference,the area under the receiver operating characteristic(ROC)curve of MAGiC PSIR Vessel[area under the curve(AUC)=0.906,P<0.01]was higher than that of TOF MRA(AUC=0.790,P<0.01).Among the 64 patients with acute ischemic stroke,39 were scanned for traditional T1,T2,and T2-FLAIR images and MAGiC images simultaneously,and CNR values in DWI diffusion restriction areas were measured,which were:Traditional T2=21.2,traditional T1=-6.7,and traditional T2-FLAIR=11.9;and MAGiC T2=7.1,MAGiC T1=-3.9,and MAGiC T2-FLAIR=4.5.CONCLUSION The synthetic MRI vascular screening scheme for patients with acute ischemic stroke can accurately evaluate the degree of bilateral middle cerebral artery stenosis,which is of great significance to early thrombolytic interventional therapy and improving patients’quality of life.展开更多
Different histopathological manifestations of focal liver lesions show varying common and uncommon imaging findings and some pathologies may show similar appearance despite of different histopathology.It is necessary ...Different histopathological manifestations of focal liver lesions show varying common and uncommon imaging findings and some pathologies may show similar appearance despite of different histopathology.It is necessary to characterise focal liver lesions accurately as not only benign and malignant lesions are managed differently,but also certain benign lesions have differing management.These lesions are increasingly being detected due to rapid growth of use of crosssectional imaging as well as improvement in image quality and new imaging techniques.Contrast enhanced magnetic resonance imaging(MRI)is considered the gold standard technique in characterising focal liver lesions.Addition of gadoxetic acid has been shown to significantly increase diagnostic accuracy in the detection and characterization of liver abnormalities.Classic imaging characteristics of common liver lesions,including their behaviour on gadoxetic acid enhanced MRI,have been described in literature over recent years.It is important to be familiar with the typical aspects of these lesions as well as know the uncommon and overlapping imaging features to reach an accurate diagnosis.In this article,we will review the well-described characteristic imaging findings of common and rare focal liver lesions and present several challenging cases encountered in the clinical setting,namely hepatocellular adenoma,focal nodular hyperplasia,hepatic angiomyolipoma,hepatocellular carcinoma,intrahepatic cholangiocarcinoma,neuroendocrine tumours as well as a pleomorphic liposarcoma of the liver.展开更多
Gadoxetic acid- or gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging(EOB-MRI) achieves excellent lesion detection and characterization for both hypervascular hepatocellula...Gadoxetic acid- or gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging(EOB-MRI) achieves excellent lesion detection and characterization for both hypervascular hepatocellular carcinoma(HCC) in arterial phase imagingand hypovascular early HCC(small well-differentiated HCC of the vaguely nodular type) in hepatobiliary phase imaging, and has become an indispensable imaging modality in the treatment of HCC. Early HCCs have been detected more frequently since the introduction of EOB-MRI into daily clinical practice. Early HCC is known to progress to conventional hypervascular HCC, and many risk factors have been identified for the hypervascularization of early HCC including the diameter of the tumor, presence of fat, and imaging findings of EOB-MRI. The rate of the development of hypervascular HCC was previously reported to be high in patients with chronic liver disease and early HCC. The presence of early HCC is regarded as a predictor for the recurrence of HCC following hepatic resection. On the other hand, although early HCC itself is currently not regarded as a target lesion for hepatic resection, early HCC at high risk of hypervascularity needs to be treated by local ablation therapy. If concomitant early HCC with progressed HCC is at high risk of hypervascularization and the functional liver reserve of a patient is sufficient, its simultaneous treatment at the time of hepatic resection for progressed HCC is recommended. Further studies on larger numbers of patients are needed before this strategy is adopted.展开更多
This study investigated the effect of velocity encoding on measurement of brain blood flow and blood volume of inflow and outflow using phase-contrast magnetic resonance angiography. A single two-dimensional phase-con...This study investigated the effect of velocity encoding on measurement of brain blood flow and blood volume of inflow and outflow using phase-contrast magnetic resonance angiography. A single two-dimensional phase-contrast magnetic resonance angiography slice was applied perpendicular to the internal carotid artery and the vertebral artery at C2 level. For each subject, the velocity encoding was set from 30 to 90 cm/s with an interval of 10 cm/s for a total of seven settings. Various velocity encodings greatly affected blood flow volume, maximal blood flow velocity and mean blood flow velocity in the internal carotid artery, but did not significantly affect vertebral arteries and jugular veins. When velocity encoding was 60-80 cm/s, the inflow blood volume was 655 _+ 118 mL/min, and the outflow volume was 506 _+ 186 mL/min. The ratio of outflow/inflow was steady at 0.78-0.83, and there was no aliasing in any of the images. These findings suggest that velocity encodings of 60 80 cm/s should be selected during measurement of cerebral blood flow volume using phase-contrast magnetic resonance angiography.展开更多
BACKGROUND Although contrast-enhanced magnetic resonance imaging(MRI)using gadoxetic acid has been shown to have higher accuracy,sensitivity,and specificity for the detection and characterization of hepatic metastases...BACKGROUND Although contrast-enhanced magnetic resonance imaging(MRI)using gadoxetic acid has been shown to have higher accuracy,sensitivity,and specificity for the detection and characterization of hepatic metastases compared with other modalities,the long examination time would limit the broad indication.Several abbreviated enhanced MRI(Ab-MRI)protocols without dynamic phases have been proposed to achieve equivalent diagnostic performance for the detection of colorectal liver metastases.However,an optimal protocol has not been established,and no studies have assessed the diagnostic performance of Ab-MRI combined with contrast-enhanced computed tomography(CE-CT),which is the preoperative imaging of colorectal cancer staging in clinical settings,to determine the best therapeutic strategy.AIM To compare the diagnostic performance of two kinds of Ab-MRI protocol with the standard MRI protocol and a combination of the Ab-MRI protocol and CE-CT for the detection of colorectal liver metastases.METHODS Study participants comprised 87 patients(51 males,36 females;mean age,67.2±10.8 years)who had undergone gadoxetic acid-enhanced MRI and CE-CT during the initial work-up for colorectal cancer from 2010 to 2021.Each exam was independently reviewed by two readers in three reading sessions:(1)Only single-shot fast spin echo(FSE)T2-weighted or fat-suppressed-FSE-T2-weighted,diffusion-weighted,and hepatobiliary-phase images(Ab-MRI protocol 1 or 2);(2)all acquired MRI sequences(standard protocol);and(3)a combination of an Ab-MRI protocol(1 or 2)and CE-CT.Diagnostic performance was then statistically analyzed.RESULTS A total of 380 Lesions were analyzed,including 195 metastases(51.4%).Results from the two Ab-MRI protocols were similar.The sensitivity,specificity,and positive and negative predictive values from Ab-MRI were non-inferior to those from standard MRI(P>0.05),while those from the combination of Ab-MRI protocol and CE-CT tended to be higher than those from Ab-MRI alone,although the difference was not significant(P>0.05),and were quite similar to those from standard MRI(P>0.05).CONCLUSION The diagnostic performances of two Ab-MRI protocols were non-inferior to that of the standard protocol.Combining Ab-MRI with CE-CT provided better diagnostic performance than Ab-MRI alone.展开更多
基金This study was reviewed and approved by the Meizhou People’s Hospital Institutional Review Board(Approval No.2022-C-36).
文摘BACKGROUND Indentifying predictive factors for postoperative recurrence of hepatocellular carcinoma(HCC)has great significance for patient prognosis.AIM To explore the value of gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid(Gd-EOB-DTPA)enhanced magnetic resonance imaging(MRI)combined with clinical features in predicting early recurrence of HCC after resection.METHODS A total of 161 patients with pathologically confirmed HCC were enrolled.The patients were divided into early recurrence and non-early recurrence group based on the follow-up results.The clinical,laboratory,pathological results and Gd-EOB-DTPA enhanced MRI imaging features were analyzed.RESULTS Of 161 patients,73 had early recurrence and 88 were had non-early recurrence.Univariate analysis showed that patient age,gender,serum alpha-fetoprotein level,the Barcelona Clinic Liver Cancer stage,China liver cancer(CNLC)stage,microvascular invasion(MVI),pathological satellite focus,tumor size,tumor number,tumor boundary,tumor capsule,intratumoral necrosis,portal vein tumor thrombus,large vessel invasion,nonperipheral washout,peritumoral enhancement,hepatobiliary phase(HBP)/tumor signal intensity(SI)/peritumoral SI,HBP peritumoral low signal and peritumoral delay enhancement were significantly associated with early recurrence of HCC after operation.Multivariate logistic regression analysis showed that patient age,MVI,CNLC stage,tumor boundary and large vessel invasion were independent predictive factors.External data validation indicated that the area under the curve of the combined predictors was 0.861,suggesting that multivariate logistic regression was a reasonable predictive model for early recurrence of HCC.CONCLUSION Gd-EOB-DTPA enhanced MRI combined with clinical features would help predicting the early recurrence of HCC after operation.
文摘AIM To optimize the hepatobiliary phase delay time(HBPDT) of Gd-EOB-DTPA-enhanced magnetic resonance imaging(GED-MRI) for more efficient identification of hepatocellular carcinoma(HCC) occurring in different degrees of cirrhosis assessed by Child-Pugh(CP) score.METHODS The liver parenchyma signal intensity(LPSI), the liver parenchyma(LP)/HCC signal ratios, and the visibility of HCC at HBP-DT of 5, 10, 15, 20, and 25 min(i.e., DT-5, DT-10, DT-15, DT-20, and DT-25) after injection of GdEOB-DTPA were collected and analyzed in 73 patients with cirrhosis of different degrees of severity(including 42 patients suffering from HCC) and 18 healthy adult controls.RESULTS The LPSI increased with HBP-DT more significantly in the healthy group than in the cirrhosis group(F = 17.361, P < 0.001). The LP/HCC signal ratios had a significant difference(F = 12.453, P < 0.001) among various HBP-DT points, as well as between CP-A and CP-B/C subgroups(F = 9.761, P < 0.001). The constituent ratios of HCC foci identified as obvious hypointensity(+++), moderate hypointensity(++), and mild hypointensity or isointensity(+/-) kept stable from DT-10 to DT-25: 90.6%, 9.4%, and 0.0% in the CP-A subgroup; 50.0%, 50.0%, and 0.0% in the CP-B subgroup; and 0.0%, 0.0%, and 100.0% in the CP-C subgroup, respectively.CONCLUSION The severity of liver cirrhosis has significant negative influence on the HCC visualization by GED-MRI. DT-10 is more efficient and practical than other HBP-DT points to identify most of HCC foci emerging in CP-A cirrhosis, as well as in CP-B cirrhosis; but an HBP-DT of 15 min or longer seems more appropriate than DT-10 for visualization of HCC in patients with CP-C cirrhosis.
文摘AIM: To compare the diagnostic accuracy of pelvic phased-array magnetic resonance imaging (MRI) and endorectal ultrasonography (ERUS) in the preoperative staging of rectal carcinoma. METHODS: Thirty-four patients (15 males, 19 females) with ages ranging between 29 and 75 who have biopsy proven rectal tumor underwent both MRI and ERUS examinations before surgery. All patients were evaluated to determine the diagnostic accuracy of depth of transmural tumor invasion and lymph node metastases. Imaging results were correlated with histopathological findings regarded as the gold standard and both modalities were compared in terms of predicting preoperative local staging of rectal carcinoma. RESULTS: The pathological T stage of the tumors was: pT1 in 1 patient, pT2 in 9 patients, pT3 in 21 patients and pT4 in 3 patients. The pathological N stage of the tumors was: pN0 in 19 patients, pN1 in 9 patients and pN2 in 6 patients. The accuracy of T staging for MRI was 89.70% (27 out of 34). The sensitivity was 79.41% and the specificity was 93.14%. The accuracy of T staging for ERUS was 85.29% (24 out of 34). The sensitivity was 70.59% and the specificity was 90.20%. Detection of lymph node metastases usingphased-array MRI gave an accuracy of 74.50% (21 out of 34). The sensitivity and specificity was found to be 61.76% and 80.88%, respectively. By using ERUS in the detection of lymph node metastases, an accuracy of 76.47% (18 out of 34) was obtained. The sensitivity and specificity were found to be 52.94% and 84.31%, respectively. CONCLUSION: ERUS and phased-array MRI are complementary methods in the accurate preoperative staging of rectal cancer. In conclusion, we can state that phased-array MRI was observed to be slightly superior in determining the depth of transmural invasion (T stage) and has same value in detecting lymph node metastases (N stage) as compared to ERUS.
基金Supported by National Natural Science Foundation of China,Nos.81571784 and 81601471Scientific and Technological Support Project for Social Development of Hunan Province,No.2015SF2020-4Project of Development and Reform Commission of Hunan Province,No.Xiang Cai Enterprise Means[2015]83
文摘AIM To evaluate the diagnostic value of gadobenate dimeglumine(Gd-BOPTA)-enhanced hepatocyte-phase magnetic resonance imaging(MRI) in evaluating hepatic fibrosis and hepatitis.METHODS Hepatocyte-phase images of Gd-BOPTA-enhanced MRI were retrospectively evaluated in 76 patients with chronic liver disease. These patients were classified into five groups according to either the histopathological fibrosis stage(S0-S4) or the histopathological hepatitis grade(G0-G4). The relative enhancement ratio(RE) of the liver parenchyma in the T1-vibe sequence was calculated by measuring the signal intensity before(SI pre) and 90 min after(SI post) intravenous injection of Gd-BOPTA using the following formula: RE =(SI post-SI pre)/SI pre. One-way analysis of variance was used to compare the difference between the relative RE in the hepatocyte phase(REh) and the stage of hepatic fibrosis and the grade of hepatitis. Pearson's productmoment correlation analysis was used to evaluate the relationship between the REh and the levels of serologic liver functional parameters.RESULTS According to histopathological hepatic fibrosis stage, the 76 patients were classified into five groups: 16 in S0, 15 in S1, 21 in S2, 9 in S3, and 15 in S4 group. According to histopathological hepatitis grade, the 76 patients were also classified into five groups: 0 in G0, 44 in G1, 22 in G2, 8 in G3, and 2 in G3 group. With regard to the stage of hepatic fibrosis, REh showed significant differences between the S2 and S3 groups and between the S2 and S4 groups(P < 0.05), but no significant difference was observed between the other groups. With regard to the grade of hepatitis, REh showed significant differences between the G1 and G2 groups and between the G1 and G4 groups(P < 0.05), but no significant difference was observed between the other groups. Increased REh showed correlations with decreased serum levels of TB, ALT and AST(P < 0.05). CONCLUSION To some extent, measuring the REh using Gd-BOPTAenhanced MRI might be a noninvasive technique for assessing the stage of hepatic fibrosis. This method is able to differentiate no/mild hepatitis from advanced hepatitis. TB, ALT and AST levels can predict the degree of liver enhancement in the hepatocyte phase of Gd-BOPTA-enhanced MRI.
基金Project supported by the National Nature Science Foundation of China (Grant No. 30900332)Grant of General Administration of Quality Supervision Inspection and Quarantine of China (Grant No. 201210079)+1 种基金the Program for Science and Technology Department of Zhejiang Province, China (Grant Nos. 2010C14010 and 2010C33172)the Natural Science Foundation of Zhejiang Province, China (Grant No. Y2090966)
文摘In this paper, an approach to the design of shielded radio-frequency (RF) phased-array coils for magnetic resonance imaging (MRI) is proposed. The target field method is used to find current densities distributed on primary and shield coils. The stream function technique is used to discretize current densities and to obtain the winding patterns of the coils. The corresponding highly ill-conditioned integral equation is solved by the Tikhonov regularization with a penalty function related to the minimum curvature. To balance the simplicity and smoothness with the homogeneity of the magnetic field of the coll's winding pattern, the selection of a penalty factor is discussed in detail.
文摘Since its introduction in the 1970’s,magnetic resonance imaging(MRI)has become a standard imaging modality.With its broad and standardized application,it is firmly established in the clinical routine and an essential element in cardiovascular and abdominal imaging.In addition to sonography and computer tomography,MRI is a valuable tool for diagnosing cardiovascular and abdominal diseases,for determining disease severity,and for assessing therapeutic success.MRI techniques have improved over the last few decades,revealing not just morphologic information,but functional information about perfusion,diffusion and hemodynamics as well.Four-dimensional(4D)flow MRI,a time-resolved phase contrast-MRI with three-dimensional(3D)anatomic coverage and velocity encoding along all three flow directions has been used to comprehensively assess complex cardiovascular hemodynamics in multiple regions of the body.The technique enables visualization of 3D blood flow patterns and retrospective quantification of blood flow parameters in a region of interest.Over the last few years,4D flow MRI has been increasingly performed in the abdominal region.By applying different acceleration techniques,taking 4D flow MRI measurements has dropped to a reasonable scanning time of 8 to 12 min.These new developments have encouraged a growing number of patient studies in the literature validating the technique’s potential for enhanced evaluation of blood flow parameters within the liver’s complex vascular system.The purpose of this review article is to broaden our understanding of 4D flow MRI for the assessment of liver hemodynamics by providing insights into acquisition,data analysis,visualization and quantification.Furthermore,in this article we highlight its development,focussing on the clinical application of the technique.
基金Wu Jieping Medical Foundation,No.320.6750.2020-11-22.
文摘BACKGROUND Synthetic magnetic resonance imaging(MRI)MAGnetic resonance imaging compilation(MAGiC)is a new MRI technology.Conventional T1,T2,T2-fluidattenuated inversion recovery(FLAIR)contrast images,quantitative images of T1 and T2 mapping,and MAGiC phase sensitive inversion recovery(PSIR)Vessel cerebrovascular images can be obtained simultaneously through post-processing at the same time after completing a scan.In recent years,studies have reported that MAGiC can be applied to patients with acute ischemic stroke.We hypothesized that the synthetic MRI vascular screening scheme can evaluate the degree of cerebral artery stenosis in patients with acute ischemic stroke.AIM To explore the application value of vascular images obtained by synthetic MRI in diagnosing acute ischemic stroke.METHODS A total of 64 patients with acute ischemic stroke were selected and examined by MRI in the current retrospective cohort study.The scanning sequences included traditional T1,T2,and T2-FLAIR,three-dimensional time-of-flight magnetic resonance angiography(3D TOF MRA),diffusion-weighted imaging(DWI),and synthetic MRI.Conventional contrast images(T1,T2,and T2-FLAIR)and intracranial vessel images(MAGiC PSIR Vessel]were automatically reconstructed using synthetic MRI raw data.The contrast-to-noise ratio(CNR)values of traditional T1,T2,and T2-FLAIR images and MAGiC reconstructed T1,T2,and T2-FLAIR images in DWI diffusion restriction areas were measured and compared.MAGiC PSIR Vessel and TOF MRA images were used to measure and calculate the stenosis degree of bilateral middle cerebral artery stenosis areas.The consistency of MAGiC PSIR Vessel and TOF MRA in displaying the degree of vascular stenosis with computed tomography angiography(CTA)was compared.RESULTS Among the 64 patients with acute ischemic stroke,79 vascular stenosis areas showed that the correlation between MAGiC PSIR Vessel and CTA(r=0.90,P<0.01)was higher than that between TOF MRA and CTA(r=0.84,P<0.01).With a degree of vascular stenosis>50%assessed by CTA as a reference,the area under the receiver operating characteristic(ROC)curve of MAGiC PSIR Vessel[area under the curve(AUC)=0.906,P<0.01]was higher than that of TOF MRA(AUC=0.790,P<0.01).Among the 64 patients with acute ischemic stroke,39 were scanned for traditional T1,T2,and T2-FLAIR images and MAGiC images simultaneously,and CNR values in DWI diffusion restriction areas were measured,which were:Traditional T2=21.2,traditional T1=-6.7,and traditional T2-FLAIR=11.9;and MAGiC T2=7.1,MAGiC T1=-3.9,and MAGiC T2-FLAIR=4.5.CONCLUSION The synthetic MRI vascular screening scheme for patients with acute ischemic stroke can accurately evaluate the degree of bilateral middle cerebral artery stenosis,which is of great significance to early thrombolytic interventional therapy and improving patients’quality of life.
文摘Different histopathological manifestations of focal liver lesions show varying common and uncommon imaging findings and some pathologies may show similar appearance despite of different histopathology.It is necessary to characterise focal liver lesions accurately as not only benign and malignant lesions are managed differently,but also certain benign lesions have differing management.These lesions are increasingly being detected due to rapid growth of use of crosssectional imaging as well as improvement in image quality and new imaging techniques.Contrast enhanced magnetic resonance imaging(MRI)is considered the gold standard technique in characterising focal liver lesions.Addition of gadoxetic acid has been shown to significantly increase diagnostic accuracy in the detection and characterization of liver abnormalities.Classic imaging characteristics of common liver lesions,including their behaviour on gadoxetic acid enhanced MRI,have been described in literature over recent years.It is important to be familiar with the typical aspects of these lesions as well as know the uncommon and overlapping imaging features to reach an accurate diagnosis.In this article,we will review the well-described characteristic imaging findings of common and rare focal liver lesions and present several challenging cases encountered in the clinical setting,namely hepatocellular adenoma,focal nodular hyperplasia,hepatic angiomyolipoma,hepatocellular carcinoma,intrahepatic cholangiocarcinoma,neuroendocrine tumours as well as a pleomorphic liposarcoma of the liver.
文摘Gadoxetic acid- or gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid-enhanced magnetic resonance imaging(EOB-MRI) achieves excellent lesion detection and characterization for both hypervascular hepatocellular carcinoma(HCC) in arterial phase imagingand hypovascular early HCC(small well-differentiated HCC of the vaguely nodular type) in hepatobiliary phase imaging, and has become an indispensable imaging modality in the treatment of HCC. Early HCCs have been detected more frequently since the introduction of EOB-MRI into daily clinical practice. Early HCC is known to progress to conventional hypervascular HCC, and many risk factors have been identified for the hypervascularization of early HCC including the diameter of the tumor, presence of fat, and imaging findings of EOB-MRI. The rate of the development of hypervascular HCC was previously reported to be high in patients with chronic liver disease and early HCC. The presence of early HCC is regarded as a predictor for the recurrence of HCC following hepatic resection. On the other hand, although early HCC itself is currently not regarded as a target lesion for hepatic resection, early HCC at high risk of hypervascularity needs to be treated by local ablation therapy. If concomitant early HCC with progressed HCC is at high risk of hypervascularization and the functional liver reserve of a patient is sufficient, its simultaneous treatment at the time of hepatic resection for progressed HCC is recommended. Further studies on larger numbers of patients are needed before this strategy is adopted.
基金the Medical Program of the Scientific & Technical Foundation in Xiamen(MRI study of chronic cerebrovascular insufficiency) in 2008,No.3502Z20084028
文摘This study investigated the effect of velocity encoding on measurement of brain blood flow and blood volume of inflow and outflow using phase-contrast magnetic resonance angiography. A single two-dimensional phase-contrast magnetic resonance angiography slice was applied perpendicular to the internal carotid artery and the vertebral artery at C2 level. For each subject, the velocity encoding was set from 30 to 90 cm/s with an interval of 10 cm/s for a total of seven settings. Various velocity encodings greatly affected blood flow volume, maximal blood flow velocity and mean blood flow velocity in the internal carotid artery, but did not significantly affect vertebral arteries and jugular veins. When velocity encoding was 60-80 cm/s, the inflow blood volume was 655 _+ 118 mL/min, and the outflow volume was 506 _+ 186 mL/min. The ratio of outflow/inflow was steady at 0.78-0.83, and there was no aliasing in any of the images. These findings suggest that velocity encodings of 60 80 cm/s should be selected during measurement of cerebral blood flow volume using phase-contrast magnetic resonance angiography.
基金approved by our institutional review board(No.20210035).
文摘BACKGROUND Although contrast-enhanced magnetic resonance imaging(MRI)using gadoxetic acid has been shown to have higher accuracy,sensitivity,and specificity for the detection and characterization of hepatic metastases compared with other modalities,the long examination time would limit the broad indication.Several abbreviated enhanced MRI(Ab-MRI)protocols without dynamic phases have been proposed to achieve equivalent diagnostic performance for the detection of colorectal liver metastases.However,an optimal protocol has not been established,and no studies have assessed the diagnostic performance of Ab-MRI combined with contrast-enhanced computed tomography(CE-CT),which is the preoperative imaging of colorectal cancer staging in clinical settings,to determine the best therapeutic strategy.AIM To compare the diagnostic performance of two kinds of Ab-MRI protocol with the standard MRI protocol and a combination of the Ab-MRI protocol and CE-CT for the detection of colorectal liver metastases.METHODS Study participants comprised 87 patients(51 males,36 females;mean age,67.2±10.8 years)who had undergone gadoxetic acid-enhanced MRI and CE-CT during the initial work-up for colorectal cancer from 2010 to 2021.Each exam was independently reviewed by two readers in three reading sessions:(1)Only single-shot fast spin echo(FSE)T2-weighted or fat-suppressed-FSE-T2-weighted,diffusion-weighted,and hepatobiliary-phase images(Ab-MRI protocol 1 or 2);(2)all acquired MRI sequences(standard protocol);and(3)a combination of an Ab-MRI protocol(1 or 2)and CE-CT.Diagnostic performance was then statistically analyzed.RESULTS A total of 380 Lesions were analyzed,including 195 metastases(51.4%).Results from the two Ab-MRI protocols were similar.The sensitivity,specificity,and positive and negative predictive values from Ab-MRI were non-inferior to those from standard MRI(P>0.05),while those from the combination of Ab-MRI protocol and CE-CT tended to be higher than those from Ab-MRI alone,although the difference was not significant(P>0.05),and were quite similar to those from standard MRI(P>0.05).CONCLUSION The diagnostic performances of two Ab-MRI protocols were non-inferior to that of the standard protocol.Combining Ab-MRI with CE-CT provided better diagnostic performance than Ab-MRI alone.