Cardiac gating 1 in nuclear magnetic resonance imaging

In order to obtain NMR images of the heart, and to measure blood flow by NMR, the signal acquisition must be synchronized wilh the patient's cardiac cycle. Some of the problems of detecting the cardiac cycle within a strong unqorm magnetic field without introducing R F interference into the imaging system are discussed. some general applications of cardiac gated NMR imaging are presented.     

Tubular duplication of the esophagus. Contribution of magnetic resonance imaging in anatomical analysis before surgery

The authors report a tubular duplication of the thoracic esophagus in a 17-year-old male. This anomaly, rare in the adult, can be explained either by a failure of esotracheal compartmentalisation, or a notochordodysraphy or more probably by an error during vacuolisation of the esophagus. The anatomical characteristics of the duplication were clearly seen on MRI. This investigation showed the intramural duplication, with only a thin barrier without muscle, between the esophageal lumen and the duplication channel two communications were present between the esophageal lumen and the duplication. The esophagus was accessed by right thoracotomy. The close contact between the duplication and the esophagus did not allow them to be separated. A subtotal esophagectomy was necessary, with digestive continuity being restored by coloplasty after a left cervicotomy and a laparotomy. The anatomy seen on the MRI should have predicted that an esophagectomy was necessary and that a thoracotomy could have been avoided by performing the procedure with a closed thorax.     

Magnetic resonance imaging and neuropsychological testing in the spectrum of normal aging

OBJECTIVE:

To understand the relationships between brain structures and function (behavior and cognition) in healthy aging.

METHOD:

The study group was composed of 56 healthy elderly subjects who underwent neuropsychological assessment and quantitative magnetic resonance imaging. Cluster analysis classified the cohort into two groups, one (cluster 1) in which the magnetic resonance imaging metrics were more preserved (mean age: 66.4 years) and another (cluster 2) with less preserved markers of healthy brain tissue (mean age: 75.4 years).

RESULTS:

The subjects in cluster 2 (older group) had worse indices of interference in the Stroop test compared with the subjects in cluster 1 (younger group). Therefore, a simple test such as the Stroop test could differentiate groups of younger and older subjects based on magnetic resonance imaging metrics.

CONCLUSION:

These results are in agreement with the inhibitory control hypotheses regarding cognitive aging and may also be important in the interpretation of studies with other clinical groups, such as patients with dementia and mild cognitive impairment.     

MRI辅助诊断胎儿脑积水的价值

目的探讨MRI(磁共振,magnetic resonance imaging)在胎儿脑积水的早期诊断与判断预后的价值。方法对26例产前经B超检查发现或怀疑为脑积水的胎儿(轻度25例,重度1例)进行MRI扫描,予查血染色体,生后定期复查患儿脑积水变化,并根据生长发育测量指标与贝利发育量表评价生长发育情况。结果经MRI检查,确诊轻中度脑积水23例,重度2例,正常1例,其中有4例B超疑似的轻度脑积水经MRI确诊,有1例经MRI扫描未发现脑积水;继续妊娠18例,1例因"肺发育不良"死亡,存活17例;5例在生后6月或纠正胎龄6月时经贝利小儿智力发育量表测定稍低于正常,经功能锻炼和/或药物治疗后再次贝利发育量表测定均达到正常水平,12例测定正常。结论在诊断胎儿中枢神经系统畸形时,MRI具有较高的阳性率,能准确的反映脑积水的程度,未合并其他畸形且不伴有染色体异常的单纯性轻、中度胎儿脑积水预后较好,MRI可作为胎儿脑积水产前诊断的重要补充。     

Clinically low-risk prostate cancer: evaluation with transrectal doppler ultrasound and functional magnetic resonance imaging

OBJECTIVES:

To evaluate transrectal ultrasound, amplitude Doppler ultrasound, conventional T₂‐weighted magnetic resonance imaging, spectroscopy and dynamic contrast‐enhanced magnetic resonance imaging in localizing and locally staging low‐risk prostate cancer.

INTRODUCTION:

Prostate cancer has been diagnosed at earlier stages and the most accepted classification for low‐risk prostate cancer is based on clinical stage T1c or T2a, Gleason score ≤6, and prostate‐specific antigen (PSA) ≤10 ng/ml.

METHODS:

From 2005 to 2006, magnetic resonance imaging was performed in 42 patients, and transrectal ultrasound in 26 of these patients. Seven patients were excluded from the study. Mean patient age was 64.94 years and mean serum PSA was 6.05 ng/ml. The examinations were analyzed for tumor identification and location in prostate sextants, detection of extracapsular extension, and seminal vesicle invasion, using surgical pathology findings as the gold standard.

RESULTS:

Sixteen patients (45.7%) had pathologically proven organ‐confined disease, 11 (31.4%) had positive surgical margin, 8 (28.9%) had extracapsular extension, and 3 (8.6%) presented with extracapsular extension and seminal vesicle invasion.Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy values for localizing low‐risk prostate cancer were 53.1%, 48.3%, 63.4%, 37.8% and 51.3% for transrectal ultrasound; 70.4%, 36.2%, 65.1%, 42.0% and 57.7% for amplitude Doppler ultrasound; 71.5%, 58.9%, 76.6%, 52.4% and 67.1% for magnetic resonance imaging; 70.4%, 58.7%, 78.4%, 48.2% and 66.7% for magnetic resonance spectroscopy; 67.2%, 65.7%, 79.3%, 50.6% and 66.7% for dynamic contrast‐enhanced magnetic resonance imaging, respectively.Sensitivity, specificity, PPV, NPV and accuracy values for detecting extracapsular extension were 33.3%, 92%, 14.3%, 97.2% and 89.7% for transrectal ultrasound and 50.0%, 77.6%, 13.7%, 95.6% and 75.7% for magnetic resonance imaging, respectively. For detecting seminal vesicle invasion, these values were 66.7%, 85.7%, 22.2%, 97.7% and 84.6% for transrectal ultrasound and 40.0%, 83.1%, 15.4%, 94.7% and 80.0% for magnetic resonance imaging.

CONCLUSION:

Although preliminary, our results suggest that imaging modalities have limited usefulness in localizing and locally staging clinically low‐risk prostate cancer.     

Partial epilepsy: A pictorial review of 3 TESLA magnetic resonance imaging features

Epilepsy is a disease with serious consequences for patients and society. In many cases seizures are sufficiently disabling to justify surgical evaluation. In this context, Magnetic Resonance Imaging (MRI) is one of the most valuable tools for the preoperative localization of epileptogenic foci. Because these lesions show a large variety of presentations (including subtle imaging characteristics), their analysis requires careful and systematic interpretation of MRI data. Several studies have shown that 3 Tesla (T) MRI provides a better image quality than 1.5 T MRI regarding the detection and characterization of structural lesions, indicating that high-field-strength imaging should be considered for patients with intractable epilepsy who might benefit from surgery. Likewise, advanced MRI postprocessing and quantitative analysis techniques such as thickness and volume measurements of cortical gray matter have emerged and in the near future, these techniques will routinely enable more precise evaluations of such patients. Finally, the familiarity with radiologic findings of the potential epileptogenic substrates in association with combined use of higher field strengths (3 T, 7 T, and greater) and new quantitative analytical post-processing techniques will lead to improvements regarding the clinical imaging of these patients. We present a pictorial review of the major pathologies related to partial epilepsy, highlighting the key findings of 3 T MRI.     

MnFe2O4纳米胶束合成及其应用于磁共振分子影像的可行性

BACKGROUND: Studies have shown that the saturation magnetization of nanoparticles can be increased by increasing of particle size of nanoparticles or cluster-like aggregation of multiple nanoparticles. But the increased particle size can reduce the cycle time of nanoparticles in the body. OBJECTIVE: To synthesize MnFe₂O₄  nanomicelles and explore the feasibility of its application in magnetic resonance molecular imaging. METHODS: MnFe₂O₄  nanoparticles were synthesized using thermal decomposition method and self-assembled with polyethylene glycol-polycaprolactone amphiphilic diblock copolymers (PEG-PCL) to construct PEG-PCL-MnFe₂O₄  nanomicelles. The characteristics of the MnFe₂O₄ nanoparticles and nanomicelles were tested. Then, MnFe₂O₄  nanoparticles and nanomicelles at different iron concentrations (0, 0.01, 0.02, 0.03, 0.04, 0.06, 0.08, 0.1, 0.2, 0.4, 0.6, 0.8 mmol/L) were placed into EP tubes. Relaxation rate of the nanomicelles were measured using magnetic resonance scanner. RESULTS AND CONCLUSION: (1) MnFe₂O₄  nanoparticles appeared as round under transmission electron microscopy. The size of nanoparticles was 11 nm with good monodispersion. The Zeta-particle size was (11.18±1.72) nm. The molar ratio of Fe/Mn was 2.13:1. The size of PEG-PCL-MnFe₂O₄  nanomicelles ranged from 52 to 86 nm, with a mean Zeta-particle size of (78.8±12.4) nm. (2) The signal intensity (SI) change of PEG-PCL-MnFe₂O₄  nanomicelles and PEG-PCL-Fe₃O₄ nanomicelles shared similar trend according to iron concentration. With the increasing of iron concentration, SI first increased and then decreased in T1WI, and it gradually decreased in T2WI and T2*WI. The SI changes in T2*WI were significantly stronger than that in T2WI and T1WI. Taken together, our results show that PEG-PCL-MnFe₂O₄ nanomicelles are expected to perform as a sensitive contrast agent used in T2WI as their moderate particle size, good monodisperse and strong T₂ relaxation.     

Early non-invasive diagnosis and treatment of acute eosinophilic myopericarditis by cardiac magnetic resonance

We report a case of early non-invasive diagnosis of acute eosinophilic myopericarditis (AEM) by cardiovascular magnetic resonance (CMR) before cardiac biopsy. A 35-yr-old woman presented with a flu-like illness, followed by pleuritic chest pain and shortness of breath. Transthoracic echocardiography revealed mild left ventricular (LV) systolic dysfunction with borderline LV wall thickness and moderate pericardial effusion. The patient had peripheral eosinophilia and CMR was performed immediately at first day of visit before cardiac biopsy. CMR showed diffuse subepicardial high T2 signals and diffuse late gadolinium enhancement in LV. Steroid therapy was immediately initiated and patient's symptom was rapidly improved. Endomyocardial biopsy at hospital day 3 reported multifocal mild infiltration of eosinophils and lymphocytes. The patient was finally confirmed as acute eosinophilic myopericarditis. This presentation emphasizes on the role of CMR which enables early non-invasive diagnosis of AEM and visualize the extent of the myocarditis.     

The value of preoperative magnetic resonance imaging in predicting postoperative recovery in patients with cervical spondylosis myelopathy: a meta-analysis

This meta-analysis was designed to elucidate whether preoperative signal intensity changes could predict the surgical outcomes of patients with cervical spondylosis myelopathy on the basis of T1-weighted and T2-weighted magnetic resonance imaging images. We searched the Medline database and the Cochrane Central Register of Controlled Trials for this purpose and 10 studies meeting our inclusion criteria were identified. In total, 650 cervical spondylosis myelopathy patients with (+) or without (-) intramedullary signal changes on their T2-weighted images were examined. Weighted mean differences and 95% confidence intervals were used to summarize the data. Patients with focal and faint border changes in the intramedullary signal on T2 magnetic resonance imaging had similar Japanese Orthopaedic Association recovery ratios as those with no signal changes on the magnetic resonance imaging images of the spinal cord did. The surgical outcomes were poorer in the patients with both T2 intramedullary signal changes, especially when the signal changes were multisegmental and had a well-defined border and T1 intramedullary signal changes compared with those without intramedullary signal changes. Preoperative magnetic resonance imaging including T1 and T2 imaging can thus be used to predict postoperative recovery in cervical spondylosis myelopathy patients.     

A Proposal of New Reference System for the Standard Axial, Sagittal, Coronal Planes of Brain Based on the Serially-Sectioned Images

Sectional anatomy of human brain is useful to examine the diseased brain as well as normal brain. However, intracerebral reference points for the axial, sagittal, and coronal planes of brain have not been standardized in anatomical sections or radiological images. We made 2,343 serially-sectioned images of a cadaver head with 0.1 mm intervals, 0.1 mm pixel size, and 48 bit color and obtained axial, sagittal, and coronal images based on the proposed reference system. This reference system consists of one principal reference point and two ancillary reference points. The two ancillary reference points are the anterior commissure and the posterior commissure. And the principal reference point is the midpoint of two ancillary reference points. It resides in the center of whole brain. From the principal reference point, Cartesian coordinate of x, y, z could be made to be the standard axial, sagittal, and coronal planes.     

Dynamic magnetic resonance imaging of the female pelvis: radio-anatomy and pathologic applications. Preliminary results

Dynamic MRI of the pelvis was performed in 16 young nulliparous, normally continent women. The examinations were performed in the dorsal decubitus position. Using Turbo-Flash scans (acquisition time: 2.1 sec), sagittal images were obtained at rest and with maximal pelvic straining. The sacral promontory-subpubic (PSP) and the subpubic-subsacral axes (SPSS) measured respectively 80.5° and 30° in relation to the horizontal plane, without a statistically significant difference between rest and straining. A marked deformation of the posterior wall of the bladder was observed in 13 cases and the bladder neck was frontally deformed in 10 cases. With straining, the base of the bladder did not descend beyond 15 mm below the SPSS, and the cervix stayed at least 14 mm above the SPSS. These were established as the normal criteria for pelvic assessment. 20 multiparous patients (mean age 65 years), referred for urinary stress incontinence and/or prolapse, were investigated using the criteria previously established. The PSP, SPSS, and vaginal angle measured 80.95°, 30.57°, and 69.69° respectively in relation to the horizontal. No statistically significant difference was detected between straining and rest conditions. The angle of the uterus in relation to the horizontal was 57.36° at rest and 65.90° in straining with a difference that was statistically significant. In six patients, the base of the bladder descended more than 1.5 cm while straining and in seven patients the cervix descended at least 1.4 cm below the SPSS while straining, both statistically significant differences. Overall, between our control and study populations, there were no significant differences between PSP and SPSS measured on straining and at rest. However, differences were detected in the vaginal angle, bladder-base position, and cervical position. These results suggest the potential substitution of MRI for colpocystography.     

异位妊娠的MRI表现及其病理基础

目的 探讨异位妊娠的MRI表现及其病理基础.方法 回顾分析37例经手术、病理证实的异位妊娠(EP)的临床资料.所有病例确诊EP后均于术前行盆腔MRI平扫和增强扫描,同时测量子宫内膜厚度,并与35例正常宫内孕(EIUP)子宫内膜厚度比较.结果 37例EP均为输卵管妊娠,其中右侧25例,左侧12例;35例为自然妊娠EP,2例为辅助生殖技术后复合妊娠;37个异位孕囊均呈囊实性表现或实性肿块,直径(3.6±1.8) cm;22例孕囊内片状软组织结构,呈等T1长T2信号,27例异位孕囊囊胚内或周围见片状短T1短T2信号;增强扫描T1WI EP孕囊壁呈连续或中断的环形强化,壁厚,强化强度类似子宫蜕膜,其中26例强化的孕囊壁呈分层状;35例单纯EP子宫内膜厚度[(0.36±0.11)cm],与宫内早孕[(0.40±0.10) cm]比较差异无统计学意义(P＞0.05).37例EP病理:输卵管腔内均见大量血块、胎盘绒毛和滋养叶细胞,其中6例切开的输卵管腔内见羊膜囊和胚胎结构.结 论宫旁囊实性或实性肿块、出血,异位孕囊囊壁呈连续或中断的分层状的蜕膜样强化和显著的子宫蜕膜反应是输卵管妊娠特征性的MRI表现,MRI能于术前做出EP的明确诊断.     

Liver lobe-based magnetic resonance diffusion-weighted imaging using multiple b values in patients with hepatitis B-related liver cirrhosis: association with the liver disease severity according to the Child-Pugh class

OBJECTIVE:To determine the associations of liver lobe-based magnetic resonance diffusion-weighted imaging findings using multiple b values with the presence and Child-Pugh class of cirrhosis in patients with hepatitis B.METHODS:Seventy-four cirrhotic patients with hepatitis B and 25 healthy volunteers underwent diffusion-weighted imaging using b values of 0, 500, 800 and 1000 sec/mm². The apparent diffusion coefficients of individual liver lobes for b_(0,500), b_(0,800) and b_(0,1000) were derived from the signal intensity averaged across images obtained using b values of 0 and 500 sec/mm², 0 and 800 sec/mm², or 0 and 1000 sec/mm², respectively, and were statistically analyzed to evaluate cirrhosis.RESULTS:The apparent diffusion coefficients for b_(0,500), b_(0,800) and b_(0,1000) inversely correlated with the Child-Pugh class in the left lateral liver lobe, the left medial liver lobe, the right liver lobe and the caudate lobe (r=–0.35 to –0.60, all p<0.05), except for the apparent diffusion coefficient for b_(0,1000) in the left medial liver lobe (r=–0.17, p>0.05). Among these parameters, the apparent diffusion coefficient for b_(0,500) in the left lateral liver lobe best differentiated normal from cirrhotic liver, with an area under the receiver operating characteristic curve of 0.989. The apparent diffusion coefficient for b_(0,800) in the right liver lobe best distinguished Child-Pugh class A from B–C and A–B from C, with areas under the receiver operating characteristic curve of 0.732 and 0.747, respectively.CONCLUSION:Liver lobe-based apparent diffusion coefficients for b_(0,500) and b_(0,800) appear to be associated with the presence and Child-Pugh class of liver cirrhosis.     

多模态MRI技术在激素性股骨头坏死微循环及脂肪含量病理机制研究中的应用

目的利用多模态MRI技术检测塌陷前期激素性股骨头坏死(SIONFH)患者的股骨头骨组织微循环障碍及脂肪化的情况,并探讨二者与SIONFH疾病发展的相关性。 方法纳入在广州中医药大学第一附属医院骨科确诊的SIONFH塌陷前期患者(即ARCO I期～Ⅲ期早期),运用多模态MRI技术[包括功能性磁共振非对称回波的最小二乘估算法迭代水脂分离序列(IDEAL－IQ)、体素内不相干运动磁共振扩散加权成像(IVIM-DWI)、T₁WI和T₂WI/fs]进行诊断研究。具体流程包括在采用T₁WI和T₂WI/fs实现原发灶结构定位的基础上,运用IVIM-DWI和IDEAL-IQ分别测量不同区域(坏死区、硬化区、正常区)的局部微循环(f)和脂肪含量(FF)。重点分析股骨头骨组织微循环障碍及组织脂肪化情况与ARCO分期的相关性,同时对2种病理机制之间相关性进行探讨研究。数据比较采用单因素方差分析、LSD-t检验、Pearson相关性分析。 结果SIONFH不同区域的局部微循环和脂肪含量比较,差异均有统计学意义(P值均小于0.05)。其中,在IDEAL-IQ序列中,坏死区FF值最高,硬化区FF值最低。在IVIM-DWI中,坏死区f值最低,硬化区其次,正常区最高。部微循环和脂肪含量呈负相关(r＝－0.37,P值均小于0.05)。ARCO Ⅲ期早期的f值最小,而FF值最小(P值均小于0.05),并且FF值与ARCO分期呈正相关(r＝0.72,P值均小于0.01),但f值与ARCO分期之间无明显相关性。 结论多模态MRI技术(IDEAL-IQ、IVIM-DWI、T₁WI和T₂WI/fs)定量测量得出,SIONFH在塌陷前期中局部微循环进行性障碍和组织脂肪化增加会关联性出现,并随ARCO分期的进展而逐步加重。     

Structural brain alterations in individuals at ultra-high risk for psychosis: a review of magnetic resonance imaging studies and future directions

Individuals at ultra-high-risk (UHR) for psychosis have become a major focus for research designed to explore markers for early detection of and clinical intervention in schizophrenia. In particular, structural magnetic resonance imaging studies in UHR individuals have provided important insight into the neurobiological basis of psychosis and have shown the brain changes associated with clinical risk factors. In this review, we describe the structural brain abnormalities in magnetic resonance images in UHR individuals. The current accumulated data demonstrate that abnormalities in the prefrontal and temporal cortex and anterior cingulate cortex occur before illness onset. These regions are compatible with the regions of structural deficits found in schizophrenia and first-episode patients. In addition, the burgeoning evidence suggests that such structural abnormalities are potential markers for the transition to psychosis. However, most findings to date are limited because they are from cross-sectional rather than longitudinal studies. Recently, researchers have emphasized neurodevelopmental considerations with respect to brain structural alterations in UHR individuals. Future studies should be conducted to characterize the differences in the brain developmental trajectory between UHR individuals and healthy controls using a longitudinal design. These new studies should contribute to early detection and management as well as provide more predictive markers of later psychosis.     

超微超顺磁性纳米氧化铁标记犬口腔黏膜上皮细胞与磁共振成像实验

BACKGROUND: Epithelial cells are commonly used as the seed cell in tissue engineering; however, there is still a lack of an effective in vivo noninvasive trace technology. OBJECTIVE: To investigate the feasibility of labeling canine oral epithelial cells with ultrasmall superparamagnetie iron oxide (USPIO) and magnetic resonance imaging (MRI) in vitro.  METHODS: Oral epithelial cells from beagles were primary cultured, and then labeled by 0.75 mg/L poly-L-lysine combined with USPIO (0, 5, 10, 25, 50 and 100 mg/L), respectively. To determine the optimal dosage, the intracellular iron expression was identified by Prussian blue staining, and the cell viability in different groups was detected by cell counting kit-8. Finally, 2×105 labeled cells were suspended with 1 mL PBS buffer, and were screened using 3.0 T MR on T2*WI sequences in vitro.  RESULTS AND CONCLUSION: USPIO prepared with 0.75 mg/L poly-L-lysine could successfully label dog oral epithelial cells. Prussian blue staining showed intracellular blue spots, and the intracellular blue spots became more with the concentration increasing and saturated at the concentration of 25 mg/L. Cell counting kit-8 indicated that the cell viability did not change when the concentration < 25 mg/L. Among the T2*WI sequences, the MRI signal intensity decreased with the concentration increasing. In conclusion, canine oral epithelial cells can be effectively labeled with USPIO making no impact on cell viability when the concentration < 25 mg/L, and MRI can be used to track these labeled cells in vitro．     

磁共振增强三维短时反转恢复变角激发T2WI快速自旋回波序列在成人精道解剖结构显示中的应用价值

目的 探讨MR增强三维短时反转恢复变角激发T₂加权成像(T₂WI)快速自旋回波(3D STIR T₂WI SPACE)序列对成人精道解剖结构显示的可行性及应用价值。方法 回顾性研究。收集2016 年11 月—2019 年3 月复旦大学附属华东医院MR室58 例成年男性腹盆腔MRI资料,年龄29~87 岁,按年龄分为低龄组(≤60岁,22 例)和高龄组(＞60岁, 36例)两组。所有患者均在德国西门子Syngo Via数据后处理工作站3D Viewer薄层最大强度投影(MIP)后行多平面重组(MPR)及曲面重组(CPR)。用3D Viewer行薄层MIP,获得冠状位、轴位、矢状位薄层MIP重建图。观察输精管壶腹段、后腹膜段和精囊腺的形态、走行、信号强度、背景抑制情况,参照日本Oh-Oka团队的评分标准,分别在MPR轴位和CPR 图像对输精管壶腹段、后腹膜段和精囊腺进行图像质量评分。采用Wilcoxon符号秩检验对比分析MPR轴位与CPR图像分别在输精管壶腹段、后腹膜段和精囊腺的图像质量评分,Wilcoxon秩和检验对比分析低龄组和高龄组在CPR图像上的图像质量评分。统计前列腺小囊检出率,并在3D Viewer获得的冠状位、轴位、矢状位三个方位薄层MIP重建图上测量前列腺小囊三个方位的径线值。结果 58例男性腰腿痛患者116侧输精管后腹膜段、壶腹段和精囊腺MR增强3D STIR T₂WI SPACE序列 MPR轴位和CPR图像质量评分分别为3(3,3)、2(2,2)、2(1,2)分和2(2,2)、2(1,2)、2(1,2)分,差异均有统计学意义(Z=10.232、5.196、2.000, P值均＜0.05)。22例(44侧)低龄组和36例(72侧)高龄组腰腿痛患者输精管后腹膜段、壶腹段和精囊腺MR增强3D STIR T₂WI SPACE序列CPR图像在的图像质量评分分别为2(1,2)、2(1,2)、1(1,2)分和2(2,2)、2(2,2)、2(1,2)分,组间比较差异均有统计学意义(Z=2.673、2.249、3.042, P值均＜0.05)。58例患者前列腺小囊检出率为27.58%(16/58),前列腺小囊冠、横、矢三个方位径线值分别为5.35(4.33,6.88)、7.50(5.90,9.00)、8.00(6.43,10.78)mm。结论 MR增强3D STIR T₂WI SPACE序列能较清晰显示精囊腺、输精管壶腹段、后腹膜段以及前列腺小囊等精道精细结构解剖,可为指导临床提供影像学参考。     

The use of MR images to evaluate the risks associated with proximal locking of intramedullary tibial nails

Vascular complications associated with locked intramedullary tibial nailing are infrequent but always serious, with a secondary amputation rate of 30%. These complications, based on an MR study of the anatomic relationships between the interlocking screws and the neurovascular or articular structures at the proximal end of the tibia, have been analysed. Two types of nails were used one with anterior-posterior locking and a specially designed prototype with oblique locking. In particular this study emphasised the anatomic risk of injury to the popliteal structures when using anterior-posterior locking, as well as to the anterior tibial vessels and proximal tibiofibular joint when using oblique locking. As no locking method appears to be better than any other, the best is that associated with the lowest morbidity. Consequently, the use of frontal instead of anterior-posterior locking is recommended the use of oblique locking, which this study has shown carries a much higher risk of complications, is strongly advised against.     

In vivo multimodal magnetic particle imaging (MPI) with tailored magneto/optical contrast agents

Magnetic Particle Imaging (MPI) is a novel non-invasive biomedical imaging modality that uses safe magnetite nanoparticles as tracers. Controlled synthesis of iron oxide nanoparticles (NPs) with tuned size-dependent magnetic relaxation properties is critical for the development of MPI. Additional functionalization of these NPs for other imaging modalities (e.g. MRI and fluorescent imaging) would accelerate screening of the MPI tracers based on their in vitro and in vivo performance in pre-clinical trials. Here, we conjugated two different types of poly-ethylene-glycols (NH₂-PEG-NH₂ and NH₂-PEG-FMOC) to monodisperse carboxylated 19.7 nm NPs by amide bonding. Further, we labeled these NPs with Cy5.5 near infra-red fluorescent (NIRF) molecules. Bi-functional PEG (NH₂-PEG-NH₂) resulted in larger hydrodynamic size (∼98 nm vs. ∼43 nm) of the tracers, due to inter-particle crosslinking. Formation of such clusters impacted the multimodal imaging performance and pharmacokinetics of these tracers. We found that MPI signal intensity of the tracers in blood depends on their plasmatic clearance pharmacokinetics. Whole body mice MPI/MRI/NIRF, used to study the biodistribution of the injected NPs, showed primary distribution in liver and spleen. Biodistribution of tracers and their clearance pathway was further confirmed by MPI and NIRF signals from the excised organs where the Cy5.5 labeling enabled detailed anatomical mapping of the tracers.in tissue sections. These multimodal MPI tracers, combining the strengths of each imaging modality (e.g. resolution, tracer sensitivity and clinical use feasibility) pave the way for various in vitro and in vivo MPI applications.