Gadoxetic acid-enhanced magnetic resonance imaging in the assessment of hepatic sinusoidal obstruction syndrome in a mouse model

BACKGROUND Neoadjuvant chemotherapy can cause hepatic sinusoidal obstruction syndrome(SOS)in patients with colorectal cancer liver metastases and increases posto-perative morbidity and mortality.AIM To evaluate T1 mapping based on gadoxetic acid-enhanced magnetic resonance imaging(MRI)for diagnosis of hepatic SOS induced by monocrotaline.METHODS Twenty-four mice were divided into control(n=10)and experimental(n=14)groups.The experimental groups were injected with monocrotaline 2 or 6 days before MRI.MRI parameters were:T1 relaxation time before enhancement;T1 relaxation time 20 minutes after enhancement(T_(1post));a reduction in T1 relaxation time(△T_(1)%);and first enhancement slope percentage of the liver parenchyma(ESP).Albumin and bilirubin score was determined.Histological results served as a reference.Liver parenchyma samples from the control and experimental groups were analyzed by western blotting,and organic anion transporter polypeptide 1(OATP1)was measured.RESULTS T_(1post),△T_(1)%,and ESP of the liver parenchyma were significantly different between two groups(all P<0.001)and significantly correlated with the total histological score of hepatic SOS(r=-0.70,0.68 and 0.79;P<0.001).△T_(1)%and ESP were positively correlated with OATP1 levels(r=0.82,0.85;P<0.001),whereas T_(1post) had a negative correlation with OATP1 levels(r=-0.83;P<0.001).INTRODUCTION Hepatic sinusoidal obstruction syndrome(SOS)is also known as hepatic veno-occlusive disease of the liver[1].The main pathological feature of hepatic SOS is damage to liver terminal vessels,and the clinical symptoms of it include ascites and abdominal pain[2].It was first proposed in 1979 as an early complication of hematopoietic stem cell transplantation[3].The prevalence ranges from 5%to 60%,and hepatic SOS is a potentially severe complication and can even lead to death in severe cases[4].Recently,systemic neoadjuvant chemotherapy became widely regarded as one of the causes hepatic SOS in the patients with advanced metastatic colorectal cancer[5,6],especially those were treated with oxaliplatin[7,8].Oxaliplatin-based preoperative chemotherapy is used for patients with colorectal liver metastases as the standard regimen[8,9],because it could improve tumor resection outcome by shrinking the metastatic sites and reducing recurrence rate[10].Nevertheless,chemotherapy-induced hepatic SOS has been associated with a higher risk of postresection morbidity[11],such as intraoperative bleeding,intraoperative transfusions,and postoperative liver failure[12].Therefore,it is important to detect and diagnose of hepatic SOS timely.Currently,the gold standard is still based on liver biopsy[13],but it is an invasive procedure and has several limitations and complications,such as hemorrhage[14].A noninvasive diagnostic modality is needed for the assessment of hepatic SOS.Some noninvasive tools have been used for diagnosis of hepatic SOS.Researchers have utilized a preoperative platelet count and aspartate aminotransferase to platelet ratio index[15].In addition,some imaging methods such as shear wave ultrasonography,computed tomography,and gadoxetic acid-enhanced magnetic resonance imaging(MRI)have been promoted as useful methods for evaluation of hepatic SOS[16-18].Recent studies with monocrotaline(MCT)-treated rats were conducted to investigate diagnosis and prediction of severity of SOS.For example,intravoxel incoherent motion diffusion-weighted imaging,non-Gaussian diffusion models,and T1 rho quantification[19,20].The MCT-induced hepatic SOS animal model was reproducible,with a detailed pathological scoring criteria[21].Gadoxetic acid is a hepatocyte-specific contrast substance,which can provide parenchymal contrast in the hepato-biliary phase.It is reported that gadoxetic acid is absorbed into the liver parenchyma via organic anion transporter polypeptide 1(OATP1)on the hepatocyte membranes[22-24].Recently,several authors have described the feasibility of gadoxetic acid-enhanced MRI for the diagnosis of oxaliplatin-induced hepatic SOS[25].They mainly diagnosed hepatic SOS based on the signal intensity of the hepatobiliary specific phase.However,there were several limitations due to the inconsistency between signal intensity of the liver parenchyma and the concentration of contrast agent for evaluation of the degree of hepatic SOS[26].Therefore,we measured T1 relaxation time on parametric mapping because it is linearly related to the concentration of the contrast agent and is not affected by other factors[27].Yang et al[28]demonstrated T1 mapping on gadoxetic acid-enhanced MRI for the assessment of oxaliplatin-induced liver injury in a C57BL/6 mouse model.However,the main pathological changes in their model were hepatocyte degeneration and fibrosis.Therefore,we aimed to explore the effectiveness of T1 mapping based on gadoxetic acid-enhanced MRI for the diagnosis of hepatic SOS in a C57BL/6 mouse model,as well as a possible relation between OATP1 Levels and MRI parameters.

Remodeling of motor cortex function in acute cerebral infarction patients following human urinary kallidinogenase A functional magnetic resonance imaging evaluation after 6 months

A total of 29 patients were treated within 48 hours after acute subcortical cerebral infarction with Xuesaitong or Xuesaitong plus human urinary kallidinogenase for 14 days. Neurological deficits, activity of daily living, and evaluations of distal upper limb motor functions at the 6-month follow-up showed that patients treated with Xuesaitong plus human urinary kallidinogenase recovered better than with Xuesaitong alone. In addition, functional MRI revealed that activation sites were primarily at the ipsilesional side of injury in all patients. Human urinary kallidinogenase induced hyperactivation of the ipsilesional primary sensorimotor cortex, premotor cortex, supplementary motor area, and contralesional posterior parietal cortex. Results showed that human urinary kallidinogenase improved symptoms of neurological deficiency by enhancing remodeling of long-term cortical motor function in patients with acute cerebral infarction.

In vivo tracking of human adipose-derived stem cells labeled with ferumoxytol in rats with middle cerebral artery occlusion by magnetic resonance imaging

Ferumoxytol, an iron replacement product, is a new type of superparamagnetic iron oxide ap- proved by the US Food and Drug Administration. Herein, we assessed the feasibility of tracking transplanted human adipose-derived stem cells labeled with ferumoxytol in middle cerebral artery occlusion-injured rats by 3.0 T MRI in vivo. 1 × 104 human adipose-derived stem cells labeled with ferumoxytol-heparin-protamine were transplanted into the brains of rats with middle cerebral artery occlusion. Neurologic impairment was scored at 1, 7, 14, and 28 days after transplantation. T2-weighted imaging and enhanced susceptibility-weighted angiography were used to observe transplanted cells. Results of imaging tests were compared with results of Prussian blue staining. The modified neurologic impairment scores were significantly lower in rats transplanted with cells at all time points except I day post-transplantation compared with rats without transplantation. Regions with hypointense signals on T2-weighted and enhanced susceptibility-weighted angiography images corresponded with areas stained by Prussian blue, suggesting the presence of superparamagnetic iron oxide particles within the engrafted cells. Enhanced susceptibility-weighted angiography image exhibited better sensitivity and contrast in tracing ferumoxytol-heparin-protamine-labeled human adipose-derived stem ceils compared with T2-weighted imaging in routine MRI.

Tracking of iron-labeled human neural stem cells by magnetic resonance imaging in cell replacement therapy for Parkinson＇s disease

Human neural stem cells（h NSCs） derived from the ventral mesencephalon are powerful research tools and candidates for cell therapies in Parkinson＇s disease. However, their clinical translation has not been fully realized due, in part, to the limited ability to track stem cell regional localization and survival over long periods of time after in vivo transplantation. Magnetic resonance imaging provides an excellent non-invasive method to study the fate of transplanted cells in vivo. For magnetic resonance imaging cell tracking, cells need to be labeled with a contrast agent, such as magnetic nanoparticles, at a concentration high enough to be easily detected by magnetic resonance imaging. Grafting of human neural stem cells labeled with magnetic nanoparticles allows cell tracking by magnetic resonance imaging without impairment of cell survival, proliferation, self-renewal, and multipotency. However, the results reviewed here suggest that in long term grafting, activated microglia and macrophages could contribute to magnetic resonance imaging signal by engulfing dead labeled cells or iron nanoparticles dispersed freely in the brain parenchyma over time.

Magnetic resonance imaging:Is there a role in clinical management for acute ischemic colitis?

AIM:To validate the utility of magnetic resonance imaging(MRI) for the clinical management of acute ischemic colitis(IC).METHODS:This is a magnetic resonance(MR) prospective evaluation of 7 patients who were proved to have acute IC on the basis of clinical,endoscopic and computed tomography(CT) findings and who were imaged in our institution between February 2011 and July 2012.The mean age of the patients was 72.28 years.Abdominal CTs were obtained using a 64-detector row configuration for all patients with un-enhanced and contrast-enhanced scans,in the late arterial phase(start delay 45-50 s) and in the portal venous phase(start delay 70-80 s).The MR examinations were performed using a 1.5T superconducting magnet,using Fast Imaging Employing Steady State Acquisition and T2-weighted fast-recovery fast-spin echo sequences in axial and coronal plane.CT and MRI examinations were analysed for the presence of colonic abnormalities and associated findings.RESULTS:Segmental involvement was seen in 6 patients(85.71%),with a mean length of involvement of 412 mm(range 145.5-1000 mm).Wall thickness varied between 6 mm and 17.5 mm(mean 10.52 mm) upon CT examinations and from 5 to 15 mm(mean 8.8 mm) upon MR examinations.The MRI appearance of the colonic wall varied over the time:TypeⅠappearance with a 3 layer sandwich sign was seen in 5 out of 12 examinations(41.66%),patients underwent MR within a mean of 36 h(ranging from 1 to 54 h) after the CT examination.Type Ⅱ and Ⅲ appearance with a 2 layer sign,was seen in 4 examinations(33.33%),patients underwent MR within a mean of 420.5 h(ranging from 121 to 720 h) after the CT examination.In the remaining three MRI examinations,performed within a mean of 410 h(ranging from 99.5 to 720 h) the colonic wall appeared normal.CONCLUSION:MRI,only using precontrast images,may be used as a substitute for invasive procedures in diagnosis and follow-up of acute IC.

Pancreatic neuroendocrine neoplasms: Magnetic resonance imaging features according to grade and stage

AIMTo describe magnetic resonance (MR) imaging features of pancreatic neuroendocrine neoplasms (PanNENs) according to their grade and tumor-nodes-metastases stage by comparing them to histopathology and to determine the accuracy of MR imaging features in predicting their biological behavior.METHODSThis study was approved by our institutional review board; requirement for informed patient consent was waived due to the retrospective nature of the study. Preoperative MR examinations of 55 PanNEN patients (29 men, 26 women; mean age of 57.6 years, range 21-83 years) performed between June 2013 and December 2015 were reviewed. Qualitative and quantitative features were compared between tumor grades and stages determined by histopathological analysis.RESULTSIll defined margins were more common in G2-3 and stage III-IV PanNENs than in G1 and low-stage tumors (P < 0.001); this feature had high specificity in the identification of G2-3 and stage III-IV tumors (90.3% and 96%, 95%CI: 73.1-97.5 and 77.7-99.8). The mean apparent diffusion coefficient value was significantly lower in G2-3 and stage III-IV lesions compared to well differentiated and low-stage tumors (1.09 × 10-3 mm2/s vs 1.45 × 10-3 mm2/s and 1.10 × 10-3 mm2/s vs 1.53 × 10-3 mm2/s, P = 0.003 and 0.001). Receiving operator characteristic analysis determined optimal cut-offs of 1.21 and 1.28 × 10-3 mm2/s for the identification of G2-3 and stage III-IV tumors, with sensitivity and specificity values of 70.8/80.7% and 64.5/64% (95%CI: 48.7-86.6/60-92.7 and 45.4-80.2/42.6-81.3).CONCLUSIONMR features of PanNENs vary according to their grade of differentiation and their stage at diagnosis and could predict the biological behavior of these tumors.

Magnetic resonance imaging correlates of bee sting induced multiple organ dysfunction syndrome: A case report

Occasionally systemic complications with high risk of death,such as multiple organ dysfunction syndrome(MODS),can occur following multiple bee stings.This case study reports a patient who presented with MODS,i.e.,acute kidney injury,hepatic and cardiac dysfunc-tion,after multiple bee stings.The standard clinical findings were then correlated with magnetic resonance imaging(MRI)findings,which demonstrates that MRI may be utilized as a simpler tool to use than other mul-tiple diagnostics.

Diffusion-weighted magnetic resonance imaging in cancer: Reported apparent diffusion coefficients,in-vitro and invivo reproducibility

There is considerable disparity in the published apparent diffusion coefficient(ADC) values across different anatomies. Institutions are increasingly assessing repeatability and reproducibility of the derived ADC to determine its variation,which could potentially be used as an indicator in determining tumour aggressiveness or assessing tumour response. In this manuscript,a review of selected articles published to date in healthy extracranial body diffusion-weighted magnetic resonance imaging is presented,detailing reported ADC values and discussing their variation across different studies. In total 115 studies were selected including 28 for liver parenchyma,15 for kidney(renal parenchyma),14 for spleen,13 for pancreatic body,6 for gallbladder,13 for prostate,13 for uterus(endometrium,myometrium,cervix) and 13 for fibroglandular breast tissue. Median ADC values in selected studies were found to be 1.28 × 10-3 mm2/s in liver,1.94 × 10-3 mm2/s in kidney,1.60 × 10-3 mm2/s in pancreatic body,0.85 × 10-3 mm2/s in spleen,2.73 × 10-3 mm2/s in gallbladder,1.64 × 10-3 mm2/s and 1.31 × 10-3 mm2/s in prostate peripheral zone and central gland respectively(combined median value of 1.54×10-3 mm2/s),1.44 × 10-3 mm2/s in endometrium,1.53 × 10-3 mm2/s in myometrium,1.71 × 10-3 mm2/s in cervix and 1.92 × 10-3 mm2/s in breast. In addition,six phantom studies and thirteen in vivo studies were summarized to compare repeatability and reproducibility of the measured ADC. All selected phantom studies demonstrated lower intra-scanner and inter-scanner variation compared to in vivo studies. Based on the findings of this manuscript,it is recommended that protocols need to be optimised for the body part studied and that system-induced variability must be established using a standardized phantom in any clinical study. Reproducibility of the measured ADC must also be assessed in a volunteer population,as variations are far more significant in vivo compared with phantom studies.

Functional magnetic resonance imaging and the brain: A brief review

Functional magnetic resonance imaging(fMRI) is em-ployed in many behavior analysis studies, with blood oxygen level dependent-(BOLD-) contrast imaging being the main method used to generate images. The use of BOLD-contrast imaging in f MRI has been refined over the years, for example, the inclusion of a spin echo pulse and increased magnetic strength were shown to produce better recorded images. Taking careful precautions to control variables during measurement, comparisons between different specimen groups can be illustrated by f MRI imaging using both quantitative and qualitative methods. Differences have been observed in comparisons of active and resting, developing and aging, and defective and damaged brains in various studies. However, cognitive studies using f MRI still face a number of challenges in interpretation that can only be overcome by imaging large numbers of samples. Furthermore, f MRI studies of brain cancer, lesions and other brain pathologies of both humans and animals are still to be explored.

Clinical value of gadoxetic acid-enhanced magnetic resonance imaging in surgery for hepatocellular carcinoma- with a special emphasis on early hepatocellular carcinoma

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.

Multimodality functional imaging using DW-MRI and 18F-FDG-PET/CT during radiation therapy for human papillomavirus negative head and neck squamous cell carcinoma: Meixoeiro Hospital of Vigo Experience

AIMTo noninvasively investigate tumor cellularity measured using diffusion-weighted magnetic resonance imaging (DW-MRI) and glucose metabolism measured by 18F-labeled fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) during radiation therapy (RT) for human papillomavirus negative (HPV-) head and neck squamous cell carcinoma (HNSCC).METHODSIn this prospective study, 6 HPV- HNSCC patients underwent a total of 34 multimodality imaging examinations DW-MRI at 1.5 T Philips MRI scanner [(n = 24) pre-, during- (2-3 wk), and post-treatment (Tx), and 18F-FDG PET/CT pre- and post-Tx (n = 10)]. All patients received RT. Monoexponential modeling of the DW-MRI data yielded the imaging metric apparent diffusion coefficient (ADC) and the mean of standardized uptake value (SUV) was measured from 18F-FDG PET uptake. All patients had a clinical follow-up as the standard of care and survival status was documented at 1 year.RESULTSThere was a strong negative correlation between the mean of pretreatment ADC (ρ = -0.67, P = 0.01) and the pretreatment 18F-FDG PET SUV. The percentage (%) change in delta (∆) ADC for primary tumors and neck nodal metastases between pre- and Wk2-3 Tx were as follows: 75.4% and 61.6%, respectively, for the patient with no evidence of disease, 27.5% and 32.7%, respectively, for those patients who were alive with disease, and 26.9% and 7.31%, respectively, for those who were dead with disease.CONCLUSIONThese results are preliminary in nature and are indicative, and not definitive, trends rendered by the imaging metrics due to the small sample size of HPV- HNSCC patients in a Meixoeiro Hospital of Vigo Experience.

Hepatobiliary phases in magnetic resonance imaging using liverspecific contrast for focal lesions in clinical practice

BACKGROUND Challenging lesions,difficult to diagnose through non-invasive methods,constitute an important emotional burden for each patient regarding a still uncertain diagnosis(malignant x benign).In addition,from a therapeutic and prognostic point of view,delay in a definitive diagnosis can lead to worse outcomes.One of the main innovative trends currently is the use of molecular and functional methods to diagnosis.Numerous liver-specific contrast agents havebeen developed and studied in recent years to improve the performance of liver magnetic resonance imaging(MRI).More recently,one of the contrast agents introduced in clinical practice is gadoxetic acid(gadoxetate disodium).AIM To demonstrate the value of the hepatobiliary phases using gadoxetic acid in MRI for the characterization of focal liver lesions(FLL)in clinical practice.METHODS Overall,302 Lesions were studied in 136 patients who underwent MRI exams using gadoxetic acid for the assessment of FLL.Two radiologists independently reviewed the MRI exams using four stages,and categorized them on a 6-point scale,from 0(lesion not detected)to 5(definitely malignant).The stages were:stage 1-images without contrast,stage 2-addition of dynamic phases after contrast(analogous to usual extracellular contrasts),stage 3-addition of hepatobiliary phase after 10 min(HBP 10’),stage 4-hepatobiliary phase after 20 min(HBP 20’)in addition to stage 2.RESULTS The interobserver agreement was high(weighted Kappa coefficient:0.81-1)at all stages in the characterization of benign and malignant FLL.The diagnostic weighted accuracy(Az)was 0.80 in stage 1 and was increased to 0.90 in stage 2.Addition of the hepatobiliary phase increased Az to 0.98 in stage 3,which was also 0.98 in stage 4.CONCLUSION The hepatobiliary sequences improve diagnostic accuracy.With growing potential in the era of precision medicine,the improvement and dissemination of the method among medical specialties can bring benefits in the management of patients with FLL that are difficult to diagnose.

MRI在局灶性机化性肺炎和周围型肺癌鉴别诊断中的应用

目的:探讨磁共振成像(MRI)对局灶性机化性肺炎(FOP)和周围型肺癌(PLC)的鉴别诊断价值。方法:回顾性分析2022年12月-2023年12月在本院就诊的60例PLC患者临床资料,将其作为PLC组,另取60例FOP患者作为FOP组。比较两组一般资料[年龄、性别、体质量指数(BMI)、吸烟史]和MRI征象[形态学特征(毛刺征、分叶征、空泡征、胸膜凹陷征、脓肿形成情况、纵隔淋巴结肿大情况),病变的表观扩散系数(ADC)值,病灶最大径及位置];采用ROC曲线分析相关参数对PLC患者的诊断价值。结果:PLC组患者毛刺征、分叶征、空泡征、脓肿形成、纵隔淋巴结肿大占比均较FOP组大,且ADC值较FOP组小,差异有统计学意义(P<0.05)。ROC曲线分析结果显示,存在毛刺征(AUC=0.658)值和纵隔淋巴结肿大(AUC=0.642),ADC值过低(AUC=0.758)对PLC的发生具有诊断价值,三者联合(AUC=0.767)诊断价值更高(P<0.05)。结论:存在毛刺征和纵隔淋巴结肿大,ADC值过低可以作为筛选PLC和FOP的诊断条件,且三者联合诊断价值更高。

提高医学影像技术专业进修生CMR扫描技术的教学方法及思考

在重庆医科大学附属第一医院金山院区进行的心脏磁共振(cardiovascular magnetic resonance,CMR)扫描技术短期进修中,医学影像技术专业的进修生遇到了几个主要问题:不熟悉扫描流程、扫描序列的功能及其参数设置,以及对常见心脏病诊断的理解不全面,导致无法有效处理扫描过程中的参数冲突。此外,进修生迫切希望能在短时间内掌握扫描技术,以便回归工作岗位时应用所学知识。针对上述问题和需求,笔者提出了一套教学改进措施,包括针对扫描技术规范、扫描序列及其参数特性的详细讲解,解决扫描过程中的参数冲突的策略,以及常见心脏病诊断的关键点。教学中采用了理论与实践相结合的方法,使进修生能在短期内有效掌握CMR扫描技术。通过这种教学方法,进修生不仅在短暂的学习期间基本掌握了CMR扫描技术,回到各自单位后,也能够独立开展相关技术项目,显著提高了进修生的技术掌握度和满意度。

Three-dimensional reconstructed magnetic resonance scans:Accuracy in identifying and defining knee meniscal tears

AIM To determine whether three-dimensional(3D) reconstruction from conventional magnetic resonance imaging(MRI) is able to accurately detect a meniscal tear, and define the configuration.METHODS Thirty-three patients' 3T MRI scan data were collected and sagittal uni-planar 3D reconstructions performed from the preoperative MRI. There were 24 meniscal tears in 24 patients, and nine controls. All patients had arthroscopic corroboration of MRI findings. Two independent observers prospectively reported on all 33 reconstructions. Meniscal tear presence or absence was noted, and tear configuration subsequently categorised as either radial, bucket-handle, parrot beak, horizontal or complex.RESULTS Identification of control menisci or meniscal tear presence was excellent(Accuracy: observer 1 = 90.9%; observer 2 = 81.8%). Of the tear configurations, bucket handle tears were accurately identified(Accuracy observer 1 and 2 = 80%). The remaining tear configurations were notaccurately discernable.CONCLUSION Uni-planar 3D reconstruction from 3T MRI knee scan sequences are useful in identifying normal menisci and menisci with bucket-handle tears. Advances in MRI sequencing and reconstruction software are awaited for accurate identification of the remaining meniscal tear configurations.

Characteristics of magnetic Fe_3O_4 nanoparticles encapsulated with human serum albumin

Magnetic nanoparticles （Fe304） were prepared by chemical precipitation method using Fe^2＋ and Fe^3＋ salts with sodium hydroxide in the nitrogen atmosphere. Fe3O4 nanoparticles were coated with human serum albumin（HSA） for magnetic resonance imaging as contrast agent. Characteristics of magnetic particles coated or uncoated were carried out using scanning electron microscopy and X-ray diffraction. Zeta potentials, package effects and distributions of colloid particles were measured to confirm the attachment of HSA on magnetic particles. Effects of Fe3O4 nanoparticles coated with HSA on magnetic resonance imaging were investigated with rats. The experimental results show that the adsorption of HSA on magnetic particles is very favorable to dispersing of magnetic Fe3O4 particles, while the sizes of Fe3O4 particles coated are related to the molar ratio of Fe3O4 to HSA. The diameters of the majority of particles coated are less than 100 nm. Fe3O4 nanoparticle coated with HSA has a good biocompatibility and low toxicity. This new contrast agent has some effects on the nuclear magnetic resonance imaging of liver and the lowest dosage is 20μmol/kg for the demands of diagnosis.

面向急性缺血性脑卒中的CT生成MRI算法

急性缺血性脑卒中病灶在计算机断层扫描(CT)上表现不明显,但在核磁共振成像(MRI)上可以清晰显示。然而,当患者体内有金属植入物等特殊情况则无法进行MRI检测,使得患者的治疗受到延误。通过CT生成MRI可在急性缺血性脑卒中的诊断和治疗中起到至关重要的作用,但现有的医学影像跨模态生成方法从CT得到的MRI缺乏病灶信息且边界模糊。为了解决上述问题,提出一种基于影像组学和扩散生成对抗网络的急性缺血性脑卒中CT生成MRI算法,通过影像组学在CT上进行病灶特征增强,突出生成MRI的病灶信息,引入梯度损失为生成图像与真实图像增加边缘感知约束,提升生成MRI的质量。在ISLES2018挑战赛数据集上的实验结果表明,该算法生成的MRI在整体上的峰值信噪比为23.051 dB,结构相似度为0.798,皮尔逊相关系数为0.969,并且病灶区域的互信息为2.075,与现有的生成模型相比,该算法的各项指标均达到最优。此外,经3名经验丰富的放射科医生在生成的MRI上确定病灶并进行阳性/阴性分类,其中生成的MRI中无错误病灶,且分类准确率可达到86.61%,可作为一种辅助工具协助医生进行诊断。

MRI及临床病理特征对乳腺癌人表皮生长因子受体2表达状态的鉴别诊断价值

目的 探讨MRI联合临床病理特征在乳腺癌人表皮生长因子受体2(human epidermal growth factor receptor 2, HER-2表达状态中的鉴别诊断价值,尤其是在HER-2低表达乳腺癌中的鉴别诊断价值。材料与方法 回顾性分析2018年1月至2019年12月在复旦大学附属肿瘤医院经病理证实为乳腺癌的患者治疗前乳腺MRI图像,205例患者均行双侧乳腺平扫及增强MRI检查。根据免疫组织化学和荧光原位杂交结果将HER-2状态分为HER-2阴性(包括零、低表达)和阳性(过表达)。分析各组临床病理特征及MRI特征,临床病理特征包括年龄、月经状态、雌激素受体(estrogen receptor, ER)、孕激素受体(progesterone receptor, PR)、激素受体(hormone receptor, HR)、分子分型和Ki-67水平。MRI特征包括纤维腺体类型、背景实质强化、多灶或多中心、瘤内T2WI高信号、瘤周水肿、病灶类型、病灶大小、肿块形状、边缘、内部强化模式、非肿块强化分布及内部强化模式。单因素分析中,对于HER-2阴、阳性组间比较,年龄采用独立样本t检验,病灶大小采用Mann-Whitney U检验,其余临床病理特征及MRI特征采用χ^(2)检验;对于HER-2零、低和过表达组的比较,年龄采用单因素方差分析,病灶大小采用Kruskal-Wallis H检验;其余临床病理特征及MRI特征采用χ^(2)检验。多因素分析采用二元logistic回归分析,用受试者工作特征曲线下面积(area under the curve, AUC)、敏感度和特异度评价模型的诊断效能。结果 HER-2阴性中零表达59例、低表达79例,HER-2阳性(过表达) 67例。HER-2阴性与阳性组临床病理特征中,ER、PR、HR和分子分型差异有统计学意义(P均<0.001),MRI特征中肿块边缘差异有统计学意义(P=0.020)。进一步比较HER-2低表达组与零表达组、HER-2低表达组与过表达组,临床病理特征中,ER、PR、HR、分子分型和Ki-67水平(以中位数40%为截断值)组间差异具有统计学意义(ER、PR、HR、分子分型:P均<0.001;Ki-67:P<0.001,P=0.037);MRI特征中,瘤内T2WI高信号与肿块形状组间差异具有统计学意义(瘤内T2WI高信号:P=0.031,P=0.011;肿块形状:P=0.012,P=0.025),且肿块边缘在HER-2低表达与零表达组间差异有统计学意义(P=0.036)。联合临床病理和MRI特征的多因素分析提示,PR状态、Ki-67水平及肿块形状是鉴别乳腺癌HER-2低表达与零表达的独立预测因素,AUC、敏感度和特异度分别为0.772、79.7%和70.9%;PR状态及瘤内T2高信号是鉴别HER-2低表达与过表达的独立预测因素,AUC、敏感度、特异度分别为0.793、69.8%和76.1%。结论 MRI影像特征对乳腺癌HER-2表达状态具有鉴别诊断价值,尤其在HER-2低表达与零表达或过表达乳腺癌鉴别诊断中。联合临床病理特征,PR阳性、Ki-67低于40%、肿块形状不规则和瘤内T2WI高信号可提示HER-2低表达乳腺癌。

Neuroimaging in human prion disease:Searching in the mist

Human prion disease is a rare,uniformly fatal neurodegenerative disorder.Its precise pathogenesis is obscure.The clinical profile of the disease differs among its various forms.There are no definitive diagnostic tests(except for brain biopsy)or proven treatment.To increase the clinical diagnostic sensitivity and specificity,three laboratory tests,including electroencephalogram,cerebrospinal fluid testing for 14-3-3 protein,and magnetic resonance imaging,are currently used.Additionally,proton magnetic resonance spectroscopy,positron emission tomography and single photon emission computed tomography can provide interesting and novel results in the research of human prion disease.

基于局部区域对应点匹配的MRI图像层间插值方法

目的医学影像层间插值对提高图像分辨率十分重要。基于灰度插值的传统算法在处理结构复杂,层间灰度变化大的区域时常会造成组织细节丢失或边缘模糊。本研究旨在建立一种局部区域对应点匹配插值算法,从而有效改善插值图像质量。方法构建一种局部区域对应点匹配算法。通过将线性插值图像与同位置原始扫描图像之间的对比构建误差图像并确定出高误差区域。对非高误差区域使用线性插值。对于各高误差区分别采用对应点匹配方法处理:首先根据每个区域的局部信息确定其对应于点对匹配度误差函数最小误差的最优参数组,然后为区域内每个插值点找到两侧图像上的最佳匹配点对用于该插值点灰度计算。将此方法应用于轴、矢、冠状位方向系列扫描图像的层间插值,将插值图像与同位置原始扫描图像的均方差作为评价插值质量的标准。结果与其他算法插值结果相比,局部区域对应点匹配算法可显著降低插值误差,矢状位图像插值结果的改善尤为突出。与整体对应点匹配算法插值结果相比,其误差平均值降低达19%,有效改善了原高误差区域的插值质量。结论本研究建立的局部区域对应点匹配插值算法可以有效地解决以往算法在处理复杂组织边界区域插值时的不足,显著提高图像层间插值的精度和质量。