Design of a 3D printed coronary artery model for CT optimization

IntroductionTo design a custom phantom of the coronary arteries to optimize CT coronary angiography (CCTA) protocols.MethodsCharacteristics of the left and right coronary arteries (mean Hounsfield Unit (HU) values and diameters) were collected from consecutive CCTA examinations (n = 43). Four different materials (two mixtures of glycerine, gelatine and water, pig hearts, Ecoflex? silicone) were scanned inside a Lungman phantom using the CCTA protocol to find the closest model to in vivo data. A 3D printed model of the coronary artery tree was created using CCTA data by exporting a CT volume rendering into Autodesk Meshmixer? software. The model was placed in an acid bath for 5 h, then covered in Ecoflex?, which was removed after drying. Both the Ecoflex? and pig heart were later filled with a mixture of contrast (Visipaque 320 mg I/ml), NaCl and gelatin and scanned with different levels of tube current and iterative reconstruction (ASiR-V). Objective (HU, noise and size (vessel diameter) and subjective analysis were performed on all scans.ResultsThe gelatine mixtures had HU values of 130 and 129, Ecoflex? 65 and the pig heart 56. At the different mA/ASiR-V levels the contrast filled Ecoflex? had a mean HU 318 ± 4, noise 47±7HU and diameter of 4.4 mm. The pig heart had a mean HU of 209 ± 5, noise 38±4HU and a diameter of 4.4 mm. With increasing iterative reconstruction level the visualisation of the pig heart arteries decreased so no measurements could be performed.ConclusionThe use of a 3D printed model of the arteries and casting with the Ecoflex? silicone is the most suitable solution for a custom-designed phantom.Implications for practiceCustom designed phantoms using 3D printing technology enable cost effective optimisation of CT protocols.     

螺旋CT扫描与多模式三维重建诊断腰椎间盘突出症

目的 探讨螺旋CT扫描容积数据与三维重建诊断腰椎间盘突出症(LDH)的价值。资料与方法 94例行连续容积扫描：准直3～5mm，螺距1．5～3．0，以1．3～2．7mm间距后重建；源影像输入AW4．0工作站，应用多平面重建(MPR)、表面遮盖显示(SSD)和仿真内镜(VE)等软件显示病变，并与椎间盘镜(MED)诊治对照。结果 8例正常；LDH86例：中央型、侧旁、椎间管、椎管外、侧方及混合型分别为19、39、5、2、3、18例。三维重建显示LDH的立体结构为堤坡形、扁丘形、尖丘形、双(多)丘形及游离形分别为34、26、9、5、2例。VE诊断LDH的准确度、灵敏度、特异度分别为95％、100％、80％。VE能模拟MED效果。结论 容积数据与多模式三维重建能提供诊断LDH更全面的信息，并模拟微创手术治疗。     

A non-negative fast multiplicative algorithm in 3D scatter-compensated SPET reconstruction

Single-photon emission tomographic (SPET) reconstruction can be improved, especially for noisy images, by using the iterative expectation-maximization of the maximum-likelihood (EM-ML) algorithm. Its application to clinical routine is, however, hampered by the high number of iterations necessary to achieve acceptable results. Therefore various methods have been developed to accelerate the EM-ML algorithm. In this paper a new accelerated EM-ML-like multiplicative algorithm is proposed for SPET reconstruction. Contrary to some other accelerating methods, it preserves two of the most important properties of the EM-ML, namely pixel positivity inside the patient body and null activity outside. The convergence speed is improved by a factor which can reach 100 in high spatial frequency or low count regions. Good estimates in the low count region are obtained without any smoothing, even at typical routine clinical count rates. The algorithm used in conjunction with the 3D effective one scatter path model provides high-quality SPET images and accurate quantitation.     

多层螺旋CT三维及重建技术对骨盆骨折的诊断价值

目的：探讨多层螺旋CT（MSCT）三维、多平面重建（MPR）及容积再现技术（VR）技术在骨盆骨折中的诊断价值。方法对21例骨盆外伤患者行MSCT扫描后,运用CT、MPR及VR等技术进行图像重建并观察和分析,并与手术所见相对照,判断MSCT重建技术诊断骨盆骨折的优缺点。结果在21例骨盆外伤患者中, MSCT正确诊断骨盆27处骨折,其检出率100％。结论 MSCT、MPR及三维重建能够立体地显示骨盆骨折的部位、形态、骨折块移位特点和类型等空间信息,是一种快速无创伤显示的最佳方法,为临床制定手术方案提供可靠依据,具有重要的临床诊断价值。     

16排多层螺旋CT门静脉系统三维成像在腹部肿瘤的临床应用

目的：评价16排螺旋CT（MSCT）门静脉系统三维血管成像技术及其在腹部肿瘤中的临床应用价值。方法：使用GE Light-speed Ultra16排CT对86例疑及腹部肿瘤的病人行MSCT造影增强检查，在ADW4．2工作站进行腹部门脉系统血管重建，重建技术包括多平面重组（MPR）、容积再现技术（VR）和MIP（2D和3D）等。结果：86例门静脉系统MSCTA均清晰显示门静脉系统的解剖结构，直观立体的评价门静脉的走行、位置、有无肿瘤癌栓、门静脉与肿瘤的空间关系等，为门静脉及其相关性疾病提供了有价值的诊断信息，其中观察空间关系以VR图像最佳，观测静脉栓子以2D-MIP最佳。结论：MSCT门静脉系统三维血管成像能准确、直观、立体地显示其解剖特点，为腹部肿瘤的诊断与治疗提供重要依据。     

A new technique for the 3D reconstruction of the incisional hernia: A pilot study

PurposeThis study aimed to accurately evaluate incisional hernias with a new three-dimensional (3D) reconstruction technology, proving surgeons more information for intuitive and accurate judgments about incisional hernia to minimize the perioperative complications and recurrence rate.MethodThis was a pilot study using a new technique, 3D reconstruction, based on computed tomography (CT) scans to measure abdominal wall defect, herniary area, herniary volume, abdominal cavity volume, and the volume of transverse, oblique, and recti abdominis in three patients with incisional hernias.ResultsThe 3D reconstruction technique made automated segmentation of the bony skeleton, skin, outer abdominal wall, vessel, and hernia sac. The hernia sac, abdominal muscles, and their anatomic relationship were clearly illustrated in 3D reconstruction images. Moreover, abdominal cavity volume; herniary diameter, area, and volume; and the volume of transverse, oblique, and recti muscles could be evaluated through 3D reconstruction images. Surgeons can also freely combine, rotate, scale, and move the 3D reconstruction mode, modify the name and transparency of the 3D reconstruction model, and observe the internal structure of the tissue and the size, shape, and location of the lesion from multiple angles for better and accurate judgments.ConclusionThe herniary diameter, area, and volume and the volume of transverse, oblique, and recti abdominis can be accurately calculated through this 3D reconstruction technology. A three-dimensional vision of the abdomen through this technology can objectively and quantitatively evaluate the situation of incisional hernia, providing a more realistic means for diagnosis and treatment of incisional hernias.     

Spatial normalization of the fiber orientation distribution based on high angular resolution diffusion imaging data

Comparison of high angular resolution diffusion imaging (HARDI) measurements between subjects or between timepoints for the same subject are facilitated by spatial normalization. In this work an algorithm was developed to transform the fiber orientation distribution (FOD) function, based on HARDI data, taking into account not only translation, but also rotation, scaling, and shearing effects of the spatial transformation. The algorithm was tested using simulated data and intrasubject and intersubject normalization of in vivo human data. All cases demonstrated reliable transformation of the FOD. This technique makes it possible to compare the intravoxel fiber distribution between subjects, between groups, or between timepoints for a single subject, which will be helpful in HARDI studies of white matter disease. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.     

MR neurography of the median nerve at 3.0T: optimization of diffusion tensor imaging and fiber tractography

Objectives

The purpose of this study was to systematically assess the optimal b-value and reconstruction parameters for DTI and fiber tractography of the median nerve at 3.0 T.

Methods

Local ethical board approved study with 45 healthy volunteers (15 men, 30 women; mean age, 41 ± 3.4 years) who underwent DTI of the right wrist at 3.0 T. A single-shot echo-planar-imaging sequence (TR/TE 10123/40 ms) was acquired at four different b-values (800, 1000, 1200, and 1400 s/mm²). Two independent readers performed post processing and fiber-tractography. Fractional anisotropy (FA) maps were calculated. Fiber tracts of the median nerve were generated using four different algorithms containing different FA thresholds and different angulation tolerances. Data were evaluated quantitatively and qualitatively.

Results

Tracking algorithms using a minimum FA threshold of 0.2 and a maximum angulation of 10° were significantly better than other algorithms. Fiber tractography generated significantly longer fibers in DTI acquisitions with higher b-values (1200 and 1400 s/mm² versus 800 s/mm²; p < 0.001). The overall quality of fiber tractography was best at a b-value of 1200 s/mm² (p < 0.001).

Conclusions

In conclusion, our results indicate use of b-values between 1000 and 1400 s/mm² for DTI of the median nerve at 3.0 T. Optimal reconstruction parameters for fiber tractography should encompass a minimum FA threshold of 0.2 and a maximum angulation tolerance of 10.     

The EOS 2D/3D X-ray imaging system: A cost-effectiveness analysis quantifying the health benefits from reduced radiation exposure

Objectives

To evaluate the cost-effectiveness of the EOS^® 2D/3D X-ray imaging system compared with standard X-ray for the diagnosis and monitoring of orthopaedic conditions.

Materials and methods

A decision analytic model was developed to quantify the long-term costs and health outcomes, expressed as quality-adjusted life years (QALYs) from the UK health service perspective. Input parameters were obtained from medical literature, previously developed cancer models and expert advice. Threshold analysis was used to quantify the additional health benefits required, over and above those associated with radiation-induced cancers, for EOS^® to be considered cost-effective.

Results

Standard X-ray is associated with a maximum health loss of 0.001 QALYs, approximately 0.4 of a day in full health, while the loss with EOS^® is a maximum of 0.00015 QALYs, or 0.05 of a day in full health. On a per patient basis, EOS^® is more expensive than standard X-ray by between £10.66 and £224.74 depending on the assumptions employed. The results suggest that EOS^® is not cost-effective for any indication. Health benefits over and above those obtained from lower radiation would need to double for EOS to be considered cost-effective.

Conclusion

No evidence currently exists on whether there are health benefits associated with imaging improvements from the use of EOS^®. The health benefits from radiation dose reductions are very small. Unless EOS^® can generate additional health benefits as a consequence of the nature and quality of the image, comparative patient throughput with X-ray will be the major determinant of cost-effectiveness.     

The application of transabdominal 3D ultrasound for the diagnosis of gastric varices: A preliminary study

Objective

The aim of this study was to determine the feasibility of using transabdominal three-dimensional (3D) colour Doppler ultrasound as a non-invasive tool to demonstrate and quantify gastric varices.

Subjects and methods

A phantom study compared the 3D water flow volume data in a hose with the actual volume inside the hose at three different flow velocities. The prospective clinical study examined the reliability and reproducibility of 3D volume data for gastric varices (mild 28, moderate 26, large 8) in 62 patients. The 3D images were acquired using the colour Doppler with both convex and micro-convex probes.

Results

The phantom study showed a 12.4–17.6% difference between the 3D data and the actual volume with no difference between the two types of probes or three velocities. The detectability of gastric varices was identical between the two probes (54/62, 87.1%). However, the scanning efficiency was significantly greater for the micro-convex probe (66.9 ± 14.1%) than the convex probe (57.3 ± 14%, p = 0.012). Body mass index was the only factor that had a significant relationship with the detectability of varices. The mean volume (mL) of the 3D signal was 0.82 ± 0.74 for mild varices, 5.48 ± 3.84 for moderate varices, and 10.63 ± 6.67 for large varices with significant differences between different grades. The intra-/inter-rater reliability was excellent.

Conclusion

The method of 3D colour Doppler ultrasound is reliable and reproducible in the quantitative assessment of vascular volume and is applicable for grading gastric varices. This study may offer a practical usefulness for 3D ultrasonography as an alternative to endoscopy.     

调强放疗三维剂量验证系统精度测试及临床应用研究

目的 测试三维剂量验证系统Compass^R测量重建及独立计算剂量的精度,评估其临床应用可行性。方法 设计一系列宽度分别为2、1、0.5 cm的条纹状射野,并选取11例肺部调强放疗（IMRT）计划,使用胶片和电离室对被测系统的平面剂量分布和特定点绝对剂量进行验证测试;使用Compass^R对IMRT模体计划做基于解剖信息的三维剂量验证,验证体积γ通过率、平均剂量偏差等参数。结果 条纹状射野测试,与胶片测量相比,被测系统重建和计算剂量γ通过率大于90%（选用3%/3 mm、2%/2 mm标准）,宽度为0.5 cm射野在半影区内γ通过率略差,被测系统重建和计算剂量曲线与胶片测量的曲线最大偏离分别3.21%和2.70%;IMRT计划特定点绝对剂量偏差在3%以内,最大偏差发生在肺部,IMRT计划等中心平面测量重建与胶片测量的γ通过率平均为（94.65±1.93）% （选用3%/3 mm标准）;三维剂量验证结果,靶区及危及器官的体积γ通过率均大于90%,平均剂量的偏差<1%。结论 测试系统剂量精度可满足IMRT计划验证要求,并能给出与患者解剖结构相关的体积剂量误差与位置误差的信息,有利于评估其对临床的影响。     

利用计算机三维空间测量技术研究前交叉韧带单束重建时内口位置的选择

目的:通过建立膝关节三维模型研究前交叉韧带单束重建术的内口位置。方法:采用磁共振扫描建立10个正常志愿者的膝关节分别在0°、30°、60°、90°和120°时的三维模型,每个模型在股骨髁间窝外侧面标定35个点(A0、A15...A90,B0、B15......E90),在胫骨标定3个点(X、Y、Z),所有的股骨点与胫骨点分别进行组合,共可获得105个组合,测量每个组合的距离,并观察这些组合在膝关节从0°屈曲到120°时的距离变化量。最大变化值小于3mm的两点确定为等距点。结果:在105个组合中,共发现有13个组合的距离变化量没有超过3mm,分别为A0-X、A15-X、A30-X、A45-X、B0-Y、B15-Y、B30-Y、B45-Y、C0-Z、C15-Z、C30-Z、C45-Z和C60-Z。结论:股骨髁间外侧面与胫骨髁间隆突间不存在绝对的等距点,但是存在生理等距点,选择等距点时应该综合考虑股骨和胫骨的因素。B45-Y是推荐的重建韧带内口位置。     

Imaging of the central nervous system in child abuse: A computer-aided instructional program

This article describes a computer-aided instructional program dealing with diagnosis and classification of central nervous system injuries seen in child abuse. Cases were selected to demonstrate the spectrum of central nervous system injury seen in child abuse, with emphasis on features which can be used to help distinguish child abuse from accidental trauma. A review of the temporal changes of hematomas as seen by magnetic resonance imaging is also provided. Completion of the program requires 25–30 minutes. Free copies of the program may be obtained by contacting the authors.     

中枢神经系统狼疮的MRI表现(附三例报告及文献复习)

目的分析中枢神经系统狼疮的ＭＲＩ表现。材料与方法搜集了３例临床资料确诊为中枢神经系统狼疮的头颅ＭＲＩ片，复习了近几年国内外文献报告的中枢神经系统狼疮的ＭＲＩ表现。结果中枢神经系统狼疮的头颅ＭＲＩ表现为：（１）大脑、小脑半球深部白质、基底节区、脑干的异常信号灶，Ｔ１加权图像呈等或略低信号，Ｔ２ＷＩ呈高信号。（２）病灶往往为多发对称性，呈斑点状、条状、片状，周围无水肿带，无占位效应。其ＭＲＩ所见须与单纯性疱疹性脑炎、脱髓鞘病变、脑梗死等ＭＲＩ表现相鉴别。结论结合临床资料、ＭＲＩ可以诊断中枢神经系统狼疮。     

3D打印模型与CT三维重建影像辅助手术治疗复杂髋臼骨折的疗效

目的 探讨使用骨折3D打印模型辅助手术与参考骨折处CT 三维重建影像辅助手术治疗复杂髋臼骨折的疗效.方法 回顾性分析2017年10月-2020年9月汉中市中心医院骨关节外科手术治疗复杂髋臼骨折患者60例,男性36例,女性24例;年龄25～64岁,平均41.8岁.根据是否使用3D打印模型分为3D组(34例)及对照组(26...     

Facial reconstruction using 3-D computerized method: A scoping review of Methods,current Status,and future developments

Facial reconstruction (otherwise known as facial approximation) is an alternative method that has been widely accepted in forensic anthropological and archaeological circumstances. This method is considered useful for creating the virtual face of a person based on skull remain. Three-dimensional (3-D) traditional facial reconstruction (known as sculpture or manual method) has been recognized for more than a century; however, it was declared to be subjective and required anthropological training. Until recently, with the progression of computational technologies, many studies attempted to develop a more appropriate method, so-called the 3-D computerized facial reconstruction. This method also relied on anatomical knowledge of the face-skull relationship, divided into semi- and automated based computational method. The 3-D computerized facial reconstruction makes it more rapid, more flexible, and more realistic to generate multiple representations of faces. Moreover, new tools and technology are continuously generating fascinating and sound research as well as encouraging multidisciplinary collaboration. This has led to a paradigm shift in the 3-D computerized facial reconstruction to a new finding and new technique based on artificial intelligence in academia. Based on the last 10-years scientific-published documents, this article aims to explain the overview of the 3-D computerized facial reconstruction and progression as well as an issue relating to future directions to encourage further improvement.     

A 3D visualization tool for the design and customization of spinal braces

A new tool was developed and validated on an X-ray dummy to allow personalized design and adjustment of spinal braces. The 3D visualization of the external trunk surface registered with the underlying 3D bone structures permits the clinicians to select pressure areas on the trunk surface for proper positioning of correcting pads inside the brace according to the patient's specific trunk deformities. After brace fabrication, the clinicians can evaluate the actual 3D patient–brace interface pressure distribution visualized simultaneously with the 3D model of the trunk in order to customize brace adjustment and validate brace design with respect to the treatment plan.     

The concentration of glutamate in cerebral tissue as a factor for the assessment of the emotional state before death. A preliminary report

In this paper the concentration of glutamate in the hemispheres of the brain, the cerebellum and the brain stems of rats exposed to sensory stimulation before death and of control rats are presented. Statistically significant differences in the concentration of this neurotransmitter were found in the hemispheres of the brain in the cases of stress lasting 10 min and 1 min and in the cerebellum after a stress of 10 min. This suggests that it may be possible to diagnose the post-mortem state of emotional tension related to sensoric aversive input which takes place directly before death. Received: 12 December 1997 / Received in revised form: 14 August 1998     

Computer-assisted 3D reconstruction of the terminal branches of the cerebral arteries

We present a three-dimensional anatomical computer model of the terminal branches of the anterior cerebral artery, acquired from equidistant serial anatomical slices of three brains. The reconstructions provide a clear picture from all angles of the complicated course of the terminal branches of the cerebral arteries, which can help to identify them on conventional and magnetic resonance angiography. Our rendition of the cerebral arteries can also be matched with CT, MR or PET images to indicate the areas of extension of individual branches, allowing neuromorphological and functional correlations.     

Segmentation process significantly influences the accuracy of 3D surface models derived from cone beam computed tomography

Aims

To assess the accuracy of surface models derived from 3D cone beam computed tomography (CBCT) with two different segmentation protocols.

Materials and methods

Seven fresh-frozen cadaver heads were used. There was no conflict of interests in this study. CBCT scans were made of the heads and 3D surface models were created of the mandible using two different segmentation protocols. The one series of 3D models was segmented by a commercial software company, while the other series was done by an experienced 3D clinician. The heads were then macerated following a standard process. A high resolution laser surface scanner was used to make a 3D model of the macerated mandibles, which acted as the reference 3D model or “gold standard”. The 3D models generated from the two rendering protocols were compared with the “gold standard” using a point-based rigid registration algorithm to superimpose the three 3D models. The linear difference at 25 anatomic and cephalometric landmarks between the laser surface scan and the 3D models generate from the two rendering protocols was measured repeatedly in two sessions with one week interval.

Results

The agreement between the repeated measurement was excellent (ICC = 0.923–1.000). The mean deviation from the gold standard by the 3D models generated from the CS group was 0.330 mm ± 0.427, while the mean deviation from the Clinician's rendering was 0.763 mm ± 0.392. The surface models segmented by both CS and DS protocols tend to be larger than those of the reference models. In the DS group, the biggest mean differences with the LSS models were found at the points ConLatR (CI: 0.83–1.23), ConMedR (CI: −3.16 to 2.25), CoLatL (CI: −0.68 to 2.23), Spine (CI: 1.19–2.28), ConAntL (CI: 0.84–1.69), ConSupR (CI: −1.12 to 1.47) and RetMolR (CI: 0.84–1.80).

Conclusion

The Commercially segmented models resembled the reality more closely than the Doctor's segmented models. If 3D models are needed for surgical drilling guides or surgical planning which requires high precision, the additional cost of the commercial segmentation services seem to be justified to produce a more accurate surface models.