Comparing the Diagnostic Value of Ultrasound and Magnetic Resonance Imaging for Placenta Accreta: A Systematic Review and Meta-analysis

The aim of this study was to evaluate the diagnostic value of ultrasound (US) as compared with magnetic resonance imaging (MRI) in the detection of placenta accreta. Sensitivity, specificity, summary receiver operating characteristic curves and areas under the curve (AUCs) were described and calculated using Meta-Disc Statistical Software, Version 1.4 (Unit of Clinical Biostatistics, Ramón y Cajal Hospital, Madrid, Spain). In the 13 studies included, US sensitivity was 83% (95% confidence interval [CI] 77%–88%), US specificity was 95% (95% CI: 93%–96%) and the diagnostic odds ratio (DOR) was 63.41 (95% CI: 29.04–138.48). In the MRI studies, sensitivity was 82% (95% CI: 72%–90%), specificity was 88% (95% CI: 81%–94%) and the DOR was 22.95 (95% CI: 3.19–165.11). Summary receiver operating characteristic analysis indicated that the diagnostic value of US in detection of placenta accreta is not significantly different from that of MRI. Both US and MRI were highly sensitive and specific in the detection of placenta accreta to support effective diagnostic methods.     

二维及实时三维超声心动图评价右心室容积的准确度研究

目的 (1)评价实时三维超声心动图测量右心室容积的准确度;(2)探讨二维超声心动图测量右心室容积的方法及其准确度.方法 27例健康志愿者,在24 h内进行常规二维超声心动图(2-DE)、实时三维超声心动图(RT-3DE)及心脏核磁共振(cMRI)检查.2-DE计算右室容积采用Simpson法、对切半椭圆体法和双平面面积-长度法(简称双平面法);RT-3DE采用三平面成像法(Tri-plane)及Tom-Tec 4D RV-Function CAP进行容积计算(结果分别记为RT-3DEV1、RT-3DE V2).cMRI图像采用Argus软件计算容积.将2-DE与RT-3DE测量的结果与cMRI结果对比研究.结果 Simpson法、对切半椭圆体法及RT-3DEV1所得结果低估RVEDV及RVESV (P＜0.001),差异有统计学意义;双平面法及RT-3DE V2结果对RVEDV及RVESV有一定的高估或低估(P＞0.05),但差异无统计学意义.相关分析表明,Simpson法及RT-3DEV1测值与cMRI测值相关性较差(RVEDV,r=0.37,0.38; RVESV,r=0.35,0.38).RT-3DE V2、对切半椭圆体法及双平面法测值均与cMRI测值高度相关,(RVEDV,r=0.72,0.73,0.85;RVESV,r=0.60,0.73,0.80).Bland-Alrman分析显示,RT-3DE V2及双平面法与cMRI的右室容积测值的平均差值更小、一致性界限更窄.结论 (1) RT-3DE采用Tom-Tec 4D RV-Function CAP软件进行分析能够较准确的测量右心室容积;(2)二维测量方法中,双平面面积-长度法能够较准确测量右心室容积.     

盆腔脂肪增多症的MRI诊断

目的 总结盆腔脂肪增多症的MRI表现，探讨盆腔相关测量的应用价值。方法 12例有完整临床和MRI检查资料的盆腔脂肪增多症病例，分析其临床表现、MRI及其他影像学检查结果，在矢状面T1WI分别测量膀胱形态指数、膀胱直肠间距、直肠骶椎间距和膀胱精囊角，并与正常组20例进行对照。结果 ①12例均表现为不同程度的盆腔脏器周围脂肪组织增多、膀胱和直肠受压变形、膀胱精囊角增大，MRI可多角度显示盆腔脂肪增多和脏器受压的程度。②矢状面T1WI测量盆腔脂肪增多症组的膀胱形态指数、膀胱直肠间距、直肠骶椎间距和膀胱精囊角均显著高于正常对照组(P＜0．05--0．01)；以对照组；x 3s为阈值，膀胱形态指数和膀胱精囊角诊断的敏感性、特异性和阳性预测值均为为100％。结论 MRI是诊断盆腔脂肪增多症的最佳影像检查方法，矢状面T1WI膀胱形态指数和膀胱精囊角的测量对本症的定量诊断最有价值。     

相控线圈在上腹部磁共振检查中的作用

目的 选择合适的脉冲线圈以获得清晰的腹部磁共振图像。方法 14例病人采用体线圈和体部相控阵线圈分别进行腹部磁共振扫描，两种线圈 的扫描序列完全一致，比较两种线圈所获图像的质量。结果 用相控阵线圈采集的腹部磁共振图像的平均信噪比明显高于体线圈所获图像（P＜0．05）。结论 利用体部相控阵线圈可明显提高腹部磁共振图像的质量。     

Echo Particle Image Velocimetry for Estimation of Carotid Artery Wall Shear Stress: Repeatability,Reproducibility and Comparison with Phase-Contrast Magnetic Resonance Imaging

Measurement of hemodynamic wall shear stress (WSS) is important in investigating the role of WSS in the initiation and progression of atherosclerosis. Echo particle image velocimetry (echo PIV) is a novel ultrasound-based technique for measuring WSS in vivo that has previously been validated in vitro using the standard optical PIV technique. We evaluated the repeatability and reproducibility of echo PIV for measuring WSS in the human common carotid artery. We measured WSS in 28 healthy participants (18 males and 10 females, mean age: 56 ± 12 y). Echo PIV was highly repeatable, with an intra-observer variability of 1.0 ± 0.1 dyn/cm² for peak systolic (maximum), 0.9 dyn/cm² for mean and 0.5 dyn/cm² for end-diastolic (minimum) WSS measurements. Likewise, echo PIV was reproducible, with a low inter-observer variability (max: 2.0 ± 0.2 dyn/cm², mean: 1.3 ± 0.1 dyn/cm², end-diastolic: 0.7 dyn/cm²) and more variable inter-scan (test–retest) variability (max: 7.1 ± 2.3 dyn/cm², mean: 2.9 ± 0.4 dyn/cm², min: 1.5 ± 0.1 dyn/cm²). We compared echo PIV with the reference method, phase-contrast magnetic resonance imaging (PC-MRI); echo PIV-based WSS measurements agreed qualitatively with PC-MRI measurements (r = 0.89, p < 0.05). Significant differences were observed in some WSS measurements (echo PIV vs. PC-MRI): WSS at peak systole: 21 ± 7.0 dyn/cm² vs. 15 ± 5.0 dyn/cm²; time-averaged WSS: 8.9 ± 3.0 dyn/cm² vs. 7.1 ± 3.0 dyn/cm² (p < 0.05); WSS at end diastole: 3.8 ± 2.8 dyn/cm² vs. 3.9 ± 2 dyn/cm² (p > 0.05). For the first time, we report that echo PIV can measure WSS with good repeatability and reproducibility in adult humans with a broad age range. Echo PIV is feasible in humans and offers an easy-to-use, ultrasound-based, quantitative technique for measuring WSS in vivo in humans with good repeatability and reproducibility.     

鼻咽癌咽后淋巴结转移的磁共振成像

目的:观测鼻咽癌咽后淋巴结转移的MRI异常指征。材料和方法:对40例正常对照组和47例鼻咽癌初诊患者的MRI所见进行观察。测量咽后淋巴结轴面最大径,观察淋巴结信号改变,记录鼻咽癌咽壁受累数。结果:对照组有23例显示外侧咽后淋巴结,大小未超过8mm;内侧咽后淋巴结均未显示。以对照组淋巴结8mm最大径作为正常上限,病变组有72.3％的外侧咽后淋巴结肿大,其中异常内侧咽后淋巴结也有4例显示。两组淋巴结信号变化相似。原发肿瘤侵犯咽壁数目与咽后淋巴结转移有关。结论:MRI发现咽后淋巴结肿大较CT敏感,但淋巴结大小仍是判断有无肿瘤转移的主要指征。     

动态磁共振成像在乳腺癌保乳术中的术前评估作用

[目的]评价动态增强磁共振成像（MRI）在乳腺癌保乳根治术的术前评估作用.[方法]平均年龄35.8岁的65 例女性乳腺癌患者,术前均行钼靶及MRI检查,对钼靶、MRI评估是否可行保乳手术进行分析,通过病理诊断来评价MRI在评估乳腺癌多中心病灶以及切缘范围上的准确性.[结果]65例患者中,钼靶术前评估认为可保乳术患者64.6%,低于MRI评估的83.1%,且两者相比差异有显著性（P＜0.05）.对癌块切缘判断准确率MRI为80%,显著高于钼靶的53.8%（P＜0.05）.[结论]在中青年女性的I~IIb期乳腺癌保乳术的术前评估方法中,动态增强MRI成像较钼靶更能准确判断有无多中心病灶及肿块切缘范围,更有利于决定是否采取保乳手术和更准确地判断手术切缘.     

前列腺癌的磁共振成像:直肠内线圈与腹部相控阵线圈的比较

目的比较直肠内线圈(endorectalcoil，ERC)和腹部相控阵线圈(torsophasedarray，TORs0PA)对前列腺检查的图像质量及对前列腺癌显示的差别。方法对123位患者行前列腺MRl检查，每位患者先用TORSOPA检查，然后行ERC检查。对30例病理证实为前列腺癌患者的MRI图像进行评价。将前列腺分为6个区，左、右侧的底部、中部和尖部，由阅片者对每个分区是否有癌作出评价。结果123位受检者中有1位未完成ERC检查。两组图像质量无明显差别(Y2=2．562，P=0．278)。MRI和穿刺病理对照，ERC与TORSOPA比较，对肿瘤定位的敏感性和阴性预期值明显升高(由58．8％和82．6％上升为86．2％和93．0％)，诊断的特异性、准确度和阳性预期值无明显变化。结论直肠内线圈比腹部相控阵线圈MRI对前列腺癌的定位更敏感。     

Magnetic Resonance Imaging vs. Transvaginal Ultrasound for Cervical Length Assessment in the Second Half of Pregnancy

The purpose of this cross-sectional study involving 42 women between 20 and 39 weeks gestation was to compare transvaginal ultrasound (TVUS) vs. magnetic resonance imaging (MRI) in the assessment of cervical length measurement during the second half of pregnancy and to evaluate the reproducibility of cervical measurements obtained through MRI. Cervical length was measured through TVUS by a single examiner. On the same day, all women also had MRI and cervical length was assessed by two independent blinded observers. There were no significant differences in the mean cervical length obtained through TVUS and MRI (paired t-test, p = 0.191). The Bland-Altman test indicated concordance between measurements obtained through methods as well as good intra- and interobserver reproducibility for MRI measurements. Intraclass correlation coefficient was 0.990 (95% confidence interval [CI]: 0.982 to 0.995; p < 0.001) for measurements performed using MRI by two different observers and 0.995 (95% CI: 0.991 to 0.997; p < 0.001) for measurements performed using the same method by a single operator. Cervical length measured through TVUS and MRI does not differ significantly. There is a good reproducibility of cervical measurements obtained through MRI. (E-mail: crpires@uol.com.br)     

磁共振成像诊断乳腺癌的研究进展

乳腺癌是女性最常见的恶性肿瘤之一,早期诊断对其治疗与预后十分重要,而磁共振成像(MRI)在乳腺癌的早期诊断中发挥着越来越重要的作用。MRI主要包括:动态增强扫描、弥散加权成像、灌注成像、磁共振波谱分析及磁共振引导下穿刺活检术。MRI以其本身所特有的优点成为乳腺癌早期诊断的一种十分重要的手段。     

Automated Registration of Freehand B-Mode Ultrasound and Magnetic Resonance Imaging of the Carotid Arteries Based on Geometric Features

An automated method for registering B-mode ultrasound (US) and magnetic resonance imaging (MRI) of the carotid arteries is proposed. The registration uses geometric features, namely, lumen centerlines and lumen segmentations, which are extracted fully automatically from the images after manual annotation of three seed points in US and MRI. The registration procedure starts with alignment of the lumen centerlines using a point-based registration algorithm. The resulting rigid transformation is used to initialize a rigid and subsequent non-rigid registration procedure that jointly aligns centerlines and segmentations by minimizing a weighted sum of the Euclidean distance between centerlines and the dissimilarity between segmentations. The method was evaluated in 28 carotid arteries from eight patients and six healthy volunteers. First, the automated US lumen segmentation method was validated and optimized in a cross-validation experiment. Next, the effect of the weighting parameter of the proposed registration dissimilarity metric and the control point spacing in the non-rigid registration was evaluated. Finally, the proposed registration method was evaluated in comparison to an existing intensity-and-point-based method, a registration using only the centerlines and a registration using manual US lumen segmentations. Registration accuracy was measured in terms of the mean surface distance between manual US segmentations and the registered MRI segmentations. The average mean surface distance was 0.78 ± 0.34 mm for all subjects, 0.65 ± 0.09 mm for healthy volunteers and 0.87 ± 0.42 mm for patients. The results for the complete set were significantly better (Wilcoxon test, p < 0.01) than the results for the intensity-and-point-based method and the centerline-based registration method. We conclude that the proposed method can robustly and accurately register US and MR images of the carotid artery, allowing multimodal analysis of the carotid plaque to improve plaque assessment.     

磁共振成像在蜂蜇伤致横纹肌溶解诊断中的应用

目的观察蜂蜇伤致横纹肌溶解的MRI表现,探讨MRI对蜂蜇伤致横纹肌溶解症的诊断价值。方法收集2008年9月2009年12月急诊科及肾内科蜂蜇伤患者4例。对其行蜇伤部位MR增强扫描,对其中1例患者行远离部位肢体扫描。总结MRI征象,评价MRI在蜂蜇伤所致横纹肌溶解临床诊治中的作用。结果蜇伤部位显示T1WI稍低,T2WI高信号影像,在T2WI加压脂影像中显示最为清晰,横纹肌损伤有局部随肌间隙扩散趋势,但远端无蜇伤肌肉受累。结论蜂蜇伤导致的横纹肌溶解可在MRI影像上得到直观反映。MRI具有良好的软组织对比度,能及时反映横纹肌受累范围及程度、治疗后恢复情况等,可为其临床诊治评估提供有利信息。     

颞下颌关节磁共振成像与X线关节造影的对比性研究

目的　为口腔医学临床上颞下颌关节紊乱综合征 (TMJDS)的诊断提供更好的影像学参考。方法　在国产磁共振系统上 ,采用自行研制的颞下颌关节MRI表面线圈完成颞下颌关节区的MRI成像 ,并与关节造影进行了对比性研究。结果　MRI成像效果良好 ,更能清晰地显示出关节盘及其相关组织的结构状态 ,同时 ,由于对人体无任何放射性损害 ,无侵犯性操作 ,这些均是X线平片关节造影、CT无法比拟的。结论　采用本技术完成的颞下颌关节MRI成像 ,更有助于临床TMJDS的诊断。