基于MRI、CT影像下膝关节及交叉韧带重建可视化的初步应用研究

目的通过MRI、CT影像结合三维重建交叉韧带及膝关节的股骨、胫腓骨部分，初步探讨MRI三维可视化临床应用的可行性。方法对16例正常受试者的双侧膝关节分别进行CT及MRI扫描，通过软件利用MRI三维重建交叉韧带，测量其解剖学数据；再利用CT影像三维重建膝关节的股骨、胫腓骨部分，进一步进行交叉韧带重建手术的计算机模拟。结果三维重建后的交叉韧带及膝关节的股骨、胫腓骨部分具有良好的形态和清晰的边界，可精确测量解剖数据；通过透明化处理，可以去除遮挡部分而清晰显示感兴趣部位；可进行交叉韧带重建手术的计算机模拟，并精确测量相关数据。结论基于MRI、CT影像下膝关节及交叉韧带的三维重建是可行的；三维影像重建后可以作为解剖学手段应用于正常人交叉韧带的解剖学研究，并对临床交叉韧带损伤的诊断及治疗具有重要意义。     

Three-dimensional analysis of pelvic volume in an unstable pelvic fracture

BACKGROUND: A model was developed to predict changes in pelvic volume associated with increasing pubic diastasis in unstable pelvic fractures. METHODS: Intact and postfracture pelvic volumes were calculated in 10 cadavers using computerized axial tomography (CT). The true pelvis was assumed to be either a sphere, a cylinder, or a hemi-elliptical sphere. Using the appropriate equations for calculating the volume of each of these shapes, pelvic volume was predicted and then compared with the measured values. RESULTS: The observed volume changes associated with increasing pubic diastasis were much smaller than previously reported. The mean difference between the measured and predicted volume was 20.0 +/- 9.9% for the sphere, 10.7 +/- 6.5% for the cylinder, and 4.5 +/- 5.9% for the hemi-elliptical sphere. The differences between these means were statistically significant (p < 0.001). CONCLUSIONS: This data suggests that the hemi-elliptical sphere best describes the geometric shape of the true pelvis and better predicts quantitative changes in pelvic volume relative to an increasing pubic diastasis as the radius has little effect on the change in volume. Due to the small changes in volume observed with increasing diastasis, factors other than the absolute change in volume must account for the clinically observed effects of emergent pelvic stabilization.     

Surgical navigation display system using volume rendering of intraoperatively scanned CT images.

As operative procedures become more complicated, simply increasing the number of devices will not facilitate such operations. It is necessary to consider the ergonomics of the operating environment, especially with regard to the provision of navigation data, the prevention of technical difficulties, and the comfort of the operating room staff. We have designed and created a data-fusion interface that enables volumetric Maximum Intensity Projection (MIP) image navigation using intra-operative mobile 3D-CT data in the OR. The 3D volumetric data reflecting a patient's inner structure is directly displayed on the monitor through video images of the surgical field using a 3D optical tracking system, a ceiling-mounted articulating monitor, and a small-size video camera mounted at the back of the monitor. The system performance and accuracy was validated experimentally. This system provides a novel interface for a surgeon with volume rendering of intra-operatively scanned CT images, as opposed to preoperative images.     

CT三维重建技术对肩胛骨骨折的诊断价值

目的：探讨螺旋CT三维表面遮盖法重建(surface shaded display，SSD)及容积重建技术(volume rendering technique，VRT)对肩胛骨骨折的诊断应用价值。方法：使用SIEMENS PLUS4螺旋CT机对20例肩胛骨骨折患者进行扫描，全部数据输入工作站进行SSD及VRT处理，并与X线、二维CT(2D CT)检查结果进行对照分析。结果：2D CT扫描的结果经临床与手术证实为临床诊断的重要依据，经统计学分析，X线检查及SSD的诊断准确率分别为94．44％和97．78％，假阴性率分别为17．65％和7．84％，X线检查的假阳性率为0．76％；VRT诊断正确率为100％。SSD、VRT检出骨折创伤的数量与X线、2D CT的结果差异无显著性意义，但是显示损伤的质量优于X线和2D CT。术后对8例进行3D CT复查，VRT能立体显示术后肩胛骨骨质及内固定物的形态与结构。结论：螺旋3DCT是诊断肩胛骨骨折的有效手段，可指导手术计划的制定和内固定物的选择，应作为诊断复杂性肩部骨折的首选方法。VRT对骨折术后内固定物的位置及复位效果的判断有较高的应用价值。     

Fast surface and volume rendering based on shear-warp factorization for a surgical simulator.

Fast simultaneous visualization of 3D medical images and medical instruments is necessary for a surgical simulator. Because unconstrained motion of a medical instrument is more frequent than that of the patient, the visualization of medical instruments is performed in real time using surface rendering. However, volume rendering is usually used for realistic visualization of the 3D medical image. We have developed an algorithm to combine a volume-rendered image and a surface-rendered image using a Z-buffer for depth cueing, which is applied to a surgical simulator. Surface rendering is used for visualization of a medical instrument, whereas 3D medical images such as CT and MRI are usually visualized by volume rendering, because segmentation of the medical image is difficult. In this study, when the volume-rendered image is combined with the surface-rendered image, the amount of computation is reduced by early ray termination and instrument-region masking in the sheared image space. Using these methods, a fast combination of volume-rendered and surface-rendered images is performed with high image quality. The method is appropriate for real-time visualization of 3D medical images and medical instrument motion in the images, and can be applied to image-guided therapy and surgical simulators.     

MRI of wrist and hand masses

Hand and wrist masses represent a common diagnostic challenge. They are predominantly due to pseudomasses, which are mostly cysts and to benign masses that include tenosynovial tumors, fibrohamartolipomas, vascular malformations, glomus tumors and epidermal inclusion cysts. Malignant tumors of the wrist and the hand are extremely rare. Magnetic resonance imaging is the imaging technique of choice to characterize and circumscribe lesions to determine the best treatment option.     

健康股骨髁间窝的MRI测量及临床意义研究

[目的]对健康髁间窝进行形态学测量、分型并年龄相关分析,为髁间窝形态相关疾病发病机制的阐明提供依据。[方法]对351例(男166例182膝,女154例169膝)膝关节MRI检查未见明显异常者进行轴位及冠状位测量,依轴位形态对髁间窝分型,并分析各指标与年龄的相关性。[结果]对200例膝进行分型,其中A型112例,占56%;U型83例,占41.5%;W型5例,占2.5%,不同性别间各型比例无统计学差异;无论轴位还是冠状位男性髁间窝宽度及深度均大于女性;按性别及髁间窝形态分层后,无论性别、轴位还是冠状位A型髁间窝宽度均最小,W型最大,U型居中;深度A型最深,W型最浅,U型居中;髁间窝宽度及深度与年龄在一定程度上均呈负相关,但除男性A型髁间窝轴位深度外,其余指标与年龄的相关性均无统计学意义。[结论]髁间窝形态的A/U/W分型中A型最多,W型最少,U型居中;男性髁间窝宽度及深度均大于女性;A型髁间窝最深、最窄,W型最宽、最浅,U型居中;髁间窝宽度及深度与年龄的相关性不明显。     

Three-dimensional multislice helical computed tomography with the volume rendering technique in the detection of vascular complications after liver transplantation

BACKGROUND: Hepatic artery stenosis and thrombosis are common complications in liver transplant patients. Digital subtraction angiography (DSA) has served as the gold standard to make this diagnosis. More recently, three-dimensional helical computed tomographic arteriography (3D CTA) with maximum intensity projection and shaded surface display techniques has been compared with DSA. The purpose of this study was to determine whether 3D CTA with the volume rendering technique is a useful and accurate tool in the detection of vascular complications after liver transplantation. METHODS: Thirty-five consecutive liver transplant patients underwent 3D CTA with volume rendering technique. The standard of reference was DSA for 20 patients and imaging and clinical follow-up for 15 patients. Two blinded reviewers evaluated the axial and 3D CTA images in consensus. RESULTS: 3D CTA with volume rendering technique detected 10 hepatic artery stenoses, six hepatic artery thromboses, two hepatic artery pseudoaneurysms, two splenic artery aneurysms, two portal vein stenoses, and four redundant hepatic arteries. In one case computed tomography (CT) detected a moderate hepatic artery stenosis, while conventional angiography showed a normal artery. The sensitivity of CT for detecting vascular lesions was 100%, specificity was 89% (8 of 9), accuracy was 95% (19 of 20), positive predictive value was 92% (11 of 12), and negative predictive value was 100% (8 of 8). CONCLUSIONS: 3D CTA is a useful and accurate noninvasive technique for detection of vascular complications in liver transplant patients.     

Optimal sampling of MRI slices for the assessment of knee cartilage volume for cross-sectional and longitudinal studies

Background  

MRI slices of 1.5 mm thickness have been used in both cross sectional and longitudinal studies of osteoarthritis, but is difficult to apply to large studies as most techniques used in measuring knee cartilage volumes require substantial post-image processing. The aim of this study was to determine the optimal sampling of 1.5 mm thick slices of MRI scans to estimate knee cartilage volume in males and females for cross-sectional and longitudinal studies.     

利用骨盆模型在三维透视导航下行骨盆骨折手术的研究

目的 与二维透视导航相比,在骨盆模型上验证三维透视导航在骨盆骨折螺钉置入术中的应用价值,为其在临床的应用提供参考. 方法 取24个人工骨盆模型,采用三维透视导航(三维透视导航组)与二维透视导航(二维透视导航组)在骨盆模型的耻骨支、坐骨支及骶髂关节分别置入空心钉.所有模型按1～24的顺序标号,其中单号的左侧和双号的右侧使用三维透视导航,其余使用二维透视导航.比较两组之间的设备注册时间、获取图像时间、置入螺钉时间、手术总时间及置入螺钉长度等. 结果 三维透视导航组和二维透视导航组手术总时间平均分别为(34.8±2.9)、(29.8±4.5)min,差异有统计学意义(t=-7.776,P=0.000);其中设备注册时间平均分别为(1.4±0.3)、(1.5±0.3) min,置入螺钉时间平均分别为(15.9±2.0)、(16.4 ±2.5)min,两组比较差异均无统计学意义(P＞0.05);获取图像时间平均分别为(13.0±1.8)、(8.8±1.0) min,差异有统计学意义(t=17.482,P=0 000).两组置入螺钉长度平均分别为(94.9±7.8)、(87.8±11.3) mm,差异有统计学意义(t=-4.431,P=0.000).二维透视导航组有2例螺钉末端顶破皮质. 结论 与二维透视导航相比,三维透视导航下行骨盆骨折螺钉固定术,可以提高手术精确度,降低术后并发症的发生率,并能安全准确地置入尽可能长的螺钉.     

MRI and venographic aspects of pelvic venous insufficiency

Pelvic venous insufficiency is a frequent pathology in multiparous women. Diagnosis can be made by chance or suspected in the case of symptoms suggesting pelvic congestion syndrome or atypical lower limb varicosity fed by pelvic leaks. After ultrasound confirmation, dynamic venography is the reference pretherapeutic imaging technique, searching for pelvic varicosity and possible leaks to the lower limbs. MRI is less invasive and allows a three-dimensional study of the varicosity and, with dynamic angiography, it can assess ovarian reflux. It also helps to plan or even sometimes avoid diagnostic venography.     

An augmented reality navigation system for pediatric oncologic surgery based on preoperative CT and MRI images

Purpose

In pediatric endoscopic surgery, a limited view and lack of tactile sensation restrict the surgeon's abilities. Moreover, in pediatric oncology, it is sometimes difficult to detect and resect tumors due to the adhesion and degeneration of tumors treated with multimodality therapies. We developed an augmented reality (AR) navigation system based on preoperative CT and MRI imaging for use in endoscopic surgery for pediatric tumors.

Methods

The patients preoperatively underwent either CT or MRI with body surface markers. We used an optical tracking system to register the reconstructed 3D images obtained from the CT and MRI data and body surface markers during surgery. AR visualization was superimposed with the 3D images projected onto captured live images. Six patients underwent surgery using this system.

Results

The median age of the patients was 3.5 years. Two of the six patients underwent laparoscopic surgery, two patients underwent thoracoscopic surgery, and two patients underwent laparotomy using this system. The indications for surgery were local recurrence of a Wilms tumor in one case, metastasis of rhabdomyosarcoma in one case, undifferentiated sarcoma in one case, bronchogenic cysts in two cases, and hepatoblastoma in one case. The average tumor size was 22.0 ± 14.2 mm. Four patients were treated with chemotherapy, three patients were treated with radiotherapy before surgery, and four patients underwent reoperation. All six tumors were detected using the AR navigation system and successfully resected without any complications.

Conclusions

The AR navigation system is very useful for detecting the tumor location during pediatric surgery, especially for endoscopic surgery.     

基于皮肤生物力学的推进皮瓣三维有限元模型与模拟分析

目的 探讨建立局部推进皮瓣的三维有限元模型,用以观测计算推进皮瓣手术后手术区域皮肤变形及应力分布情况,以供临床皮瓣设计参考.方法 通过人体额部离体头皮的生物力学实验研究获取皮肤的生物力学参数,再利用三维有限元软件MSC Marc/Mentat 2005建立局部推进皮瓣的三维有限元模型,设计同一皮瓣修复不同面积的创面,模拟出皮瓣在不同的抻长比例下,观测手术区域术后皮肤组织的变形情况、相应的应力-应变分布情况.结果 皮瓣推进后的抻长比例越大,术后手术区域的应力最大值也随之越大,但不符合线性规律.在不顾及皮瓣血运的条件下,理论上皮瓣抻长比例的最大限度可达到40%,若＞40%,皮肤应力将超过屈服极限.结论 利用三维有限元方法及人体皮肤生物力学参数模拟分析推进皮瓣具有可行性,但其抻长比例应控制在40%范围内,以确保安全.     

基于皮肤生物力学的推进皮瓣三维有限元模型与模拟分析

目的 探讨建立局部推进皮瓣的三维有限元模型,用以观测计算推进皮瓣手术后手术区域皮肤变形及应力分布情况,以供临床皮瓣设计参考.方法 通过人体额部离体头皮的生物力学实验研究获取皮肤的生物力学参数,再利用三维有限元软件MSC Marc/Mentat 2005建立局部推进皮瓣的三维有限元模型,设计同一皮瓣修复不同面积的创面,模拟出皮瓣在不同的抻长比例下,观测手术区域术后皮肤组织的变形情况、相应的应力-应变分布情况.结果 皮瓣推进后的抻长比例越大,术后手术区域的应力最大值也随之越大,但不符合线性规律.在不顾及皮瓣血运的条件下,理论上皮瓣抻长比例的最大限度可达到40%,若＞40%,皮肤应力将超过屈服极限.结论 利用三维有限元方法及人体皮肤生物力学参数模拟分析推进皮瓣具有可行性,但其抻长比例应控制在40%范围内,以确保安全.     

基于皮肤生物力学的推进皮瓣三维有限元模型与模拟分析

目的 探讨建立局部推进皮瓣的三维有限元模型,用以观测计算推进皮瓣手术后手术区域皮肤变形及应力分布情况,以供临床皮瓣设计参考.方法 通过人体额部离体头皮的生物力学实验研究获取皮肤的生物力学参数,再利用三维有限元软件MSC Marc/Mentat 2005建立局部推进皮瓣的三维有限元模型,设计同一皮瓣修复不同面积的创面,模拟出皮瓣在不同的抻长比例下,观测手术区域术后皮肤组织的变形情况、相应的应力-应变分布情况.结果 皮瓣推进后的抻长比例越大,术后手术区域的应力最大值也随之越大,但不符合线性规律.在不顾及皮瓣血运的条件下,理论上皮瓣抻长比例的最大限度可达到40%,若＞40%,皮肤应力将超过屈服极限.结论 利用三维有限元方法及人体皮肤生物力学参数模拟分析推进皮瓣具有可行性,但其抻长比例应控制在40%范围内,以确保安全.     

半月板损伤MRI表现与关节镜下表现的对比研究

目的探讨MRI对半月板损伤的诊断价值,进一步明确MRI信号对手术指证的参考意义。方法采集MRI诊断的97例（141个）损伤半月板的相关资料,以关节镜下半月板损伤表现为诊断＂金标准＂,应用SPSS 17.0软件对结果进行统计学分析。采用Kappa值检验MRI对半月板损伤诊断的有效性,然后用Х^2检验分析MRI对内、外侧半月板损伤诊断价值的差异。根据MRI的损伤信号表现分成三组,A组：MRI表现为Ⅰ级信号的半月板;B组：MRI表现为Ⅱ级信号的半月板;C组：MRI表现为Ⅲ级信号的半月板。应用Х^2检验分析各组需要手术处理的损伤半月板数量的差异。结果 （1）MRI诊断半月板撕裂有较好的有效性（K=0.58）,且对于内、外侧半月板撕裂的诊断无统计学差异;（2）不同信号间需行手术处理的半月板数比较具有统计学差异（Х^2=62.357,P〈0.05）。两组间比较：A组和B组无统计学差异（Х^2=5.332,P〉0.02）;C组分别和A、B组相比,均有有统计学差异（Х^2=33.930,P〈0.01）、（Х^2=47.781,P〈0.01）。结论 MRI是诊断半月板撕裂伤的一种比较有效的手段,MRI表现可以作为手术指证的参考,但应结合临床症状和体征综合考虑。     

耻骨联合分离程度与骨盆容量变化相关性的实验研究

[目的]探讨不稳定的骨盆骨折耻骨联合分离程度与骨盆容量变化之间的关系,预测骨盆出血量.[方法]防腐尸体骨盆8具;去除盆腔脏器,保留盆壁筋膜;骨刀凿断耻骨联合,切断双侧骶棘,骶结节韧带和骶髂前韧带,制成开放性骨盆骨折,使耻骨联合分离至1、3、5、7 cm时,用螺旋CT扫描,用标准CAD测量软件计算盆腔容量.[结果]在开放性骨盆骨折中随着耻骨联合分离距离加大,骨盆腔容量逐渐增大.耻骨联合完整时,盆腔容量平均值为(915±121)ml,耻骨联合分离1、3、5、7 cm时,盆腔容量平均值分别为(969±114)、(1074±112)、(1 247±120)、(1 406±103)ml.其相关性r=0.77,P＜0.01,其回归方程为骨盆容量(ml)=918+50*耻骨联合分离距离(cm).[结论]不稳定骨盆骨折时,随着耻骨联合的分离程度增加,骨盆容量明显增加,根据耻骨联合分离距离可预测骨盆内出血量,指导临床治疗.     

Assessment of a semiautomated pelvic floor measurement model for evaluating pelvic organ prolapse on MRI

Introduction and hypothesis

The objective of this study was to assess the performance of a semiautomated pelvic floor measurement algorithmic model on dynamic magnetic resonance imaging (MRI) images compared with manual pelvic floor measurements for pelvic organ prolapse (POP) evaluation.

Methods

We examined 15 MRIs along the midsagittal view. Five reference points used for pelvic floor measurements were identified both manually and using our semiautomated measurement model. The two processes were compared in terms of accuracy and precision.

Results

The semiautomated pelvic floor measurement model provided highly consistent and accurate locations for all reference points on MRI. Results also showed that the model can identify the reference points faster than the manual-point identification process.

Conclusion

The semiautomated pelvic floor measurement model can be used to facilitate and improve the process of pelvic floor measurements on MRI. This will enable high throughput analysis of MRI data to improve the correlation analysis with clinical outcomes and potentially improve POP assessment.