MSCT图像重组技术在眼眶上、下裂骨折的应用价值

目的探讨多层螺旋CT(MSCT)图像重组技术在眼眶上、下裂外伤诊断中的临床应用价值。方法对临床初诊有眼眶外伤患者470例行MSCT常规轴位扫描,获取容积描数据后,在图像后处理工作站进行MPR、VRT重组,对各种重组结果进行回顾性对比分析。结果 MSCT骨折直接征象为骨皮质不连续、碎骨片移位,间接征象为鼻窦粘膜增厚共计41例,粘膜血肿征共计11例、鼻窦积血积液59例,眶下裂泪滴征24例及小空泡征2例。在98例眶上裂骨折中,轴位、轴位+MPR、轴位+VRT重建技术对骨折的显示率分别为86.7%、100%、97.9%,(Χ~2值/P值轴位*轴位+MPR-13.923/0.000、Χ~2值/P~(值轴位*轴位+VRT)-8.735/0.003),差异有统计学价值。在59例眶下裂骨折中,轴位、轴位+MPR、轴位+VRT重建技术对骨折的显示率分别为81.4%、100%、94.9%,(Χ~2值/P值轴位*轴位+MPR-12.131/0.000、Χ~2值/P~(值轴位*轴位+VRT)-5.187/0.023),差异有统计学价值。结论多层螺旋CT轴位结合MPR、VR重建图像能辨析解剖形态,准确显示眶上裂、眶下裂骨折的分型、范围、程度,轴位+MPR显示率最高,多种重建技术能为临床诊断和治疗提供可靠的影像诊断依据。     

磁共振成像对膝关节急性软骨损伤的研究

目的探讨光纤1.5T磁共振在膝关节急性软骨损伤时的序列优化,及其在不同级别损伤中的诊断价值。方法收集40例急性膝关节外伤患者,行常规扫描并加扫FS-3D-SPRG(fast)、Fiesta-c、MERGE序列,患者两周内进行临床手术或关节镜治疗,将临床手术或关节镜结果作为金标准,评价上述序列在不同级别软骨损伤时的准确度、敏感度、特异度和临床一致性(Kappa值)。结果 1)FS-3D-SPRG(fast)序列的敏感度为94.29%,特异度为95.29%,Kappa值为0.793;2)Fiesta-c序列的敏感度为92.21%,特异度为98.16%,Kappa值为0.896;3)MERGE序列的敏感度为90.54%,特异度为95.18%,Kappa值为0.558。结论 1)Fiesta-c序列具有良好的软骨/关节液、软骨/骨对比度,与临床手术的符合度很高,尤其对软骨钙化带的显示最为清晰;2)3D-FS-SPGR(fast)序列经过参数改动,扫描时间明显缩短(仅需3min11s),在本次实验中也得到了较好的效果,可作为软骨损伤时的优化序列,但低级别软骨损伤时假阴性较高;3)采用3D-FS-SPGR序列进行MIP重建,可得到直观软骨图像,对诊断有较大参考意义;4)MERGE序列在本次研究中,无论从软骨显示,还是与临床结果对照,不及PDWI、Fiesta-c、3D-FS-SPGR序列。     

扩散张量成像扩散梯度方向与DTI图像质量的相关性研究

目的:探讨磁共振扩散张量成像(DTI)时扩散梯度方向对图像质量的影响。方法:对30例健康志愿者行头部常规MRI及DTI检查。DTI检查时分别采用15、25和55这三个不同的扩散梯度方向。在右侧内囊后肢3/4处(皮质脊髓束)设定感兴趣区,测量平均扩散系数(DCavg)、部分各向异性(FA)和三个本征值(λ1、λ2、λ3),分别对3个扩散方向的DCavg和FA值进行统计学分析。使用3个本征值计算FA理论值,并与测量值进行比较。选定内囊层面的FA图,计算全层面可显示FA值<0.3的纤维束百分比,并进行统计学分析。结果:三个扩散梯度方向图像上测量的DC值差异无统计学意义(P>0.05),而FA值差异均有统计学意义(P<0.05),显示FA值<0.3的纤维束的百分比差异均有极显著性意义(P<0.01)。扩散梯度方向为15时FA测量值与理论计算值之间差异有统计学意义(P<0.05),为25和55时差异无统计学意义(P>0.05)。结论:选择扩散梯度方向为25时兼顾了图像信噪比和扫描时间,值得在临床应用中推广。     

MRI MnDPDP增强对原发性肝细胞癌的诊断价值

目的 :评估MRIMnDPDP增强不同延迟时间成像对原发性肝细胞癌的诊断价值。材料和方法 :对 3 6例HCCs行MRIMnDPDP增强研究。静脉滴注MnDPDP结束后 5min开始每隔 5min成像 1次 ,直至 40min ;第二天行延迟 2 4h成像。成像序列为SET1WI和FMPSPGRT1WI。对不同延迟时间图像的信噪比 (S/N)、对比度噪声比 (C/N)及病灶显示率进行比较研究。结果 :(1)不同延迟时间图像的S/N无统计学差异。 (2 ) 5～ 2 5min图像肝与HCC之间C/N高于 3 0min以后图像 (P<0 0 5 )。 (3 )病灶显示率和定性率均以延迟 2 4h最高 (92 7% ) ,但各组图像之间无显著差异。结论 :MnDPDP增强MRI的HCC显示率和定性率均以延迟 2 4h图像为佳     

MUSICA参数的应用评价

随着CR技术在临床中的应用,其强大的后处理功能给影像技师及临床医师的工作带来极大的方便.MUSICA(MULTI-SCALE IMAGE CONTRAST AMPLIFICATION)参数,即多层次影像对比度放大技术,是AGFA公司在1994年开发的一种先进实用的技术,它使得图像后处理功能变得更加简单实用.MUSICA各项参数的合理运用,使从一幅影像上获取不同诊断结果成为可能,从而最大限度地满足了临床要求.     

膝关节运动性骨挫伤的MRI诊断

目的探讨膝关节运动性骨挫伤的MRI特征及诊断价值。方法选取近年X线平片未见膝关节骨折,而MRI检查显示膝关节骨髓有异常改变32例进行回顾性分析。结果 32例患者骨挫伤45处,合并韧带损伤12处,半月板损伤5例,软骨损伤2例。根据骨挫伤MR表现分为3型:Ⅰ型(14例),为邻近膝关节骨骺或干骺端松质骨内斑片状、地图状异常信号改变,边缘模糊。Ⅱ型(5例),除与I型表现相似外合并骨皮质连续性中断。Ⅲ型(13型),为紧靠皮质下局灶性的异常信号区。结论 MRI能揭示膝关节骨挫伤的病理改变,准确显示膝关节骨挫伤的部位和范围及有无其它附属结构的损伤,是膝关节骨挫伤的最佳检查手段。     

螺旋CT图像后处理在膝关节骨折中的应用

近年来 ,螺旋CT及图像后处理在临床工作中广泛应用 ,逐步应用于全身各部位 ,充分显示了独特的优势和临床应用价值。图像后处理包括MPR(multiplanarreconstruction)和 3D(threedimen sionalreconstruction)。膝关节结构复杂 ,骨块相互重叠 ,普通X线和轴位图像很难全面客观的显示     

膝关节股骨远端截骨导板的旋转对截骨准确性的影响

目的:研究股骨远端截骨定位器械旋转对股骨远端截骨面的影响。方法:术中截骨验证:在外旋位时股骨远端截骨导板相对后倾;内旋位时股骨远端截骨导板相对前倾;股骨截骨导板的外翻角度则随着内外旋角度的增大而减小。据此建立数学模型计算:以髓内杆为旋转轴,标准位时股骨远端截骨导板与髓内杆在冠状面存在有角度A的外翻,而在矢状面上有角度B的前后倾。定义实际外翻角A’为实际的截骨面与髓内杆垂直面在冠状面上的夹角,实际前后倾角度B’为实际的截骨面与髓内杆垂直面之间在矢状面上的夹角,实际股骨远端截骨导板相对标准位的截骨导板旋转角度为C。通过数学模型计算实际外翻角A’和实际前后倾角度B’。结果:通过计算得出tan A’=tan A*cos C,sin B’=sin A/(1+cos2 A/tan2C)1/2(当C为正值时B’取正值,当C为负值时B’取负值)。当A取5°、6°或7°时,在30°股骨截骨导板的旋转偏差范围内,对实际的外翻角度的影响较小,在1°偏差以内。无论内外旋转,实际的外翻角度均小于设定的外翻角A;但对于实际的前后倾影响较大,当A取6°、旋转角度为30°时,前后倾的偏差约3°。结论:膝关节置换术中股骨远端截骨导板的旋转对截骨面的前后倾与外翻有较大的影响。     

20例骨纤维皮质缺损的临床与X线分析

骨纤维皮质缺损是一种好发于儿童干骺端的良性纤维性病变。本病在儿童中发病率较高 ,日常工作中较为常见 ,由于对本病的认识不足容易误诊。笔者搜集 2 0例 ,分析临床及Ｘ线特点 ,以提高对本病的认识。1　材料与方法　　本组 2 0例中 ,男 12例 ,女 8例 ,年龄 4～ 17岁 ,其中 4～ 8岁 14例 ,9～ 17岁 6例 ,发病部位均在膝关节附近 ,因膝关节疼痛拍片发现 7例 ,外伤偶然发现 13例 ,其中无症状 13例。体检 :局部肿胀、压痛 4例。2 0例均摄正侧位Ｘ线片 ,Ｘ线照片要求对比度、清晰度良好 ,病灶因重叠显示不清晰的在透视下斜位或切线位点片。2　结…     

纤维性骨皮质缺损的X线、CT诊断分析

目的:总结纤维性骨皮质缺损的影像学表现特点,加深对本病的认识,提高影像诊断能力。方法:回顾性分析2006～2012年经临床追踪或手术病理证实的28例纤维性骨皮质缺损患者的影像资料。28例均行X线正侧位片检查,其中12例加行病变处切线位片检查,16例行CT检查,分析纤维性骨皮质缺损的X线、CT检查的诊断特点。结果:28例纤维性骨皮质缺损的病灶均位于长管状骨,其中股骨远侧干骺端16例,1例累及双股骨远侧干骺端;胫骨近侧干骺端6例;腓骨近侧干骺端2例;胫骨远侧干骺端2例;肱骨干2例。病灶位于病骨侧后缘20例;位于后缘8例。其典型的影像学表现为:病灶X线正位片呈椭圆形或圆形低密度透亮区,边缘多清晰、锐利,见硬化边;X线切线位片和CT图像示局部骨皮质凹陷缺损、病灶表浅、不深入髓腔、病灶表面未见骨壳。结论:纤维性骨皮质缺损通过X线正侧位片、切线位片和CT图像分析可明确诊断。     

股骨颈CR摄影后处理参数优化组合

目的：调整CR后处理参数,分析其对不同解剖结构显示效果的影响,为临床实际应用作出更具针对性的选择提供理论依据。方法：抽取39例髋关节正位影像资料,以关节面、骨小梁、肌间隙、皮下脂肪作为评价对象,观察参数调整前后的影像显示情况,并对数据作统计分析。结果：具体为多级图像对比度放大技术4.0、边缘增强3.5、减低噪声4.5、动态范围压缩3.5的参数调整对关节面、皮下脂肪显示影响不明显,但能够改善骨小梁、肌间隙视觉质量,并且对于后者的影响更显著。结论：优化后的参数能够提高部分解剖结构的显示能力,在临床实际中可以有针对性的选择使用。     

Quantitative Computertomographie der Knochenmineraldichte des Unterkiefers Darstellung der topographischen Verteilung der Knochenmineraldichte bei automatisierter Segmentierung der Kieferstrukturen

PURPOSE: Confirmation of a new technique for evaluating bone mineral density (BMD). Colored coded imaging of topographical distribution of bone mineral density in the spongy substance. METHOD: For 20 patients, dental CT examinations of the mandible were made in axial slices. Spongy substance and cortical bone pixels were automatically segmented at foramina mentalia level by means of threshold fixation. The segments were separated in areas relevant to implantology. For each region, BMD was measured by means of quantitative computed tomography (QCT). Spongiose substance of 20 mandibles was segmented by using three threshold intervals to image topographical BMD distribution. RESULTS: Cortical bone and spongy substance could be automatically segmented for 20 mandibles. BMD could be measured in each region. The results were comparable with those of other techniques. Three threshold intervals were segmented for 20 mandibles in the spongy substance to depict topographical BMD distribution. CONCLUSIONS: Areas of low BMD can be detected by imaging topographical BMD distribution. This way, subjective rating by the examiner is eliminated.     

A method to optimize the processing algorithm of a computed radiography system for chest radiography

A test methodology using an anthropomorphic-equivalent chest phantom is described for the optimization of the Agfa computed radiography "MUSICA" processing algorithm for chest radiography. The contrast-to-noise ratio (CNR) in the lung, heart and diaphragm regions of the phantom, and the "system modulation transfer function" (sMTF) in the lung region, were measured using test tools embedded in the phantom. Using these parameters the MUSICA processing algorithm was optimized with respect to low-contrast detectability and spatial resolution. Two optimum "MUSICA parameter sets" were derived respectively for maximizing the CNR and sMTF in each region of the phantom. Further work is required to find the relative importance of low-contrast detectability and spatial resolution in chest images, from which the definitive optimum MUSICA parameter set can then be derived. Prior to this further work, a compromised optimum MUSICA parameter set was applied to a range of clinical images. A group of experienced image evaluators scored these images alongside images produced from the same radiographs using the MUSICA parameter set in clinical use at the time. The compromised optimum MUSICA parameter set was shown to produce measurably better images.     

CT determination of bone mineral density and structural investigations on the axial skeleton for estimating the osteoporosis-related fracture risk by means of a risk score

In addition to the pure measurement of bone mineral density (BMD) in osteodensitometry, the investigation of bone structure is becoming increasingly important for estimating fracture risk. In a clinical study, a risk score was proposed which separately assesses BMD and structural parameters for spongious and cortical bone and aggregates them into a single diagnostic parameter. In 120 lumbar vertebrae from 40 patients, BMD was determined separately for spongious and cortical bone by means of quantitative CT using a single energy procedure (SE-QCT/85 kV). In addition, structural parameters based on high resolution CT were calculated for the spongiosa and cortical bone. For all patients the number of osteoporosis-related fractures was determined on the entire skeletal system. According to WHO criteria, the patients were subdivided into four groups: 1, normal; 2, osteopenic; 3, osteoporotic without fractures; 4, severely osteoporotic. Weighting factors were determined by means of multivariate least-squares analysis and used to calculate a risk score of all parameters. The ability of the individual parameters and of the sum of discriminate between the individual groups was tested. If one considers the individual parameters (BMD and the fractal structural values for spongious and cortical bone), they allow a statistically significant separation of the four groups, although there is overlapping in the value ranges. In patients with fractures, there was a significant reduction in the cortical mineral density, accompanied by a deterioration in structural properties. The following individual values were obtained (minimum-mean-maximum): spongiosa BMD (mg ml-1), unfractured: 62-112-163, fractured: 9-48-77; cortical BMD (mg ml-1), unfractured: 190-287-405, fractured: 133-191-269; spongiosa structural parameter, unfractured: 0.35-0.73-1.01, fractured: 0.95-1.24-1.58; cortical structural parameter, unfractured: 18-31-65, fractured: 21-44-66. Above 77 mg ml-1 CaHA in the spongiosa and 270 mg ml-1 CaHA in cortical bone, no fractures were observed. By appropriately selecting the weighting factors, the score is free of overlapping between the groups with and without fractures (values: unfractured 1-9-15, fractured 16-21-29). With higher score values, the fracture risk is increasing.     

Factors influencing visualization of vertebral metastases on MR imaging versus bone scintigraphy

OBJECTIVE: The purpose of this study was to investigate whether the location and size of vertebral body metastases influence the difference in detection rates between MR imaging and bone scintigraphy. MATERIALS AND METHODS: We retrospectively evaluated the vertebral body lesions detected on MR imaging in 74 patients with known widely disseminated metastatic disease. Three radiologists independently reviewed the MR images and bone scintigraphs. MR imaging findings included lesion size and its spatial relationship to the bony cortex (intramedullary, subcortical, and transcortical) and results were correlated with those of planar technetium 99m bone scintigraphy. RESULTS: Findings on bone scans were negative for all intramedullary lesions without cortical involvement shown on MR imaging, regardless of their size. Findings on bone scans (71.3% for transcortical and 33.8% for subcortical) were frequently positive for lesions with cortical involvement (trans- or subcortical), and the probability of positive findings on bone scans was also influenced by the lesion size. Statistical analysis showed a positive correlation among cortical involvement, lesion size, and positive findings on bone scintigraphy (p < 0.0001). CONCLUSION: Location (the presence of cortical bone involvement on MR imaging) and size of the vertebral body metastases appear to be important contributing factors to the difference in detection rates between MR imaging and bone scintigraphy. Cortical involvement is likely the cause of positive findings on bone scans. Early vertebral metastases tend to be small and located in the medullary cavity without cortical involvement, and therefore, findings may be positive on MR images but negative on bone scans.     

Magnetic resonance in the identification and assessment of extent and severity of bone contusion damage: comparison of several types of imaging (SE/T1, GE/T2 and SE/T1) with fat suppression

INTRODUCTION: Bone marrow contusion is a common cause of chronic joint pain in the post-traumatic knee; it is usually associated with meniscal and/or ligament damage but it may also be the only abnormal sign. In this condition MRI plays a fundamental role because it is the only imaging technique which can diagnose it and accurately assess its extent and any cortical bone and/or cartilage involvement. We investigated the diagnostic potentials of 3 MR sequences in identifying and assessing the extent of bone contusion. MATERIAL AND METHODS: January, 1994, to December, 1997, we performed 539 MR examinations of the knee on 478 patients with chronic joint pain following trauma. We used T1-weighted SE, T2*-weighted GE and T1-weighted SE sequences with fat saturation (fs), paying great attention to technical parameter setting. The images were retrospectively reviewed by groups of radiologists using 2 semi-objective evaluation systems: a qualitative assessment to grade the ease of detection of the contusion with each sequence and a quantitative assessment of contusion extent and of osteochondral involvement, if any, again for each sequence. RESULTS: The qualitative analysis showed that GE and SE-fs sequences were superior to the conventional ones in identifying bone contusion foci; GE sequences tended to overestimate the number of poorly depictable lesions relative to SE-fs ones. The quantitative analysis showed that the conventional sequences tend to underestimate the foci extent, while GE and SE-fs sequences performed nearly the same in the assessment of high-grade lesions. The number of low-midgrade lesions was overestimated by GE sequences relative to SE-fs ones. DISCUSSION AND CONCLUSIONS: GE and SE-fs sequences permit accurate studies of bone contusions. Diagnostic efficacy is increased by enhancing the signal from non-fatty structures within a tissue rich in fat: the quantitative reduction of the non-fatty structural component and/or its replacement with abnormal components is thus best shown. Fat-suppression sequences were more accurate in defining lesion size, which is also related to low susceptibility to the artifacts from extrinsic and especially intrinsic structural inhomogeneities. In contrast, GE sequences demonstrated high susceptibility, which caused poorer definition of the contusion borders and, consequently, overestimation of the lesion size.     

High-resolution magnetic resonance imaging of trabecular bone in the wrist at 3 tesla: initial results

PURPOSE: To evaluate the feasibility of high-resolution magnetic resonance imaging (MRI) of trabecular bone of the wrist at 3 Tesla (3T) in vivo and to assess the potential benefit of the increased resolution for clinical assessment of structural changes in spongy bone. MATERIAL AND METHODS: High-resolution MRI of the wrist was performed with a whole-body 3T MR scanner using a dedicated circularly polarized transmit-receive wrist-coil. Two 3D-FISP sequences with a spatial resolution of 300 x 300 x 300 microm3 in a measuring time of TA = 7:51 min, and 200 x 200 x 200 microm3 in TA = 9:33 min were applied. Seven young healthy volunteers and three elderly subjects with suspected osteoporosis were examined. The signal-to-noise ratio (SNR) in the optimized setup at 3T was compared to measurements at 1.5T. RESULTS: The images at 3T allow microscopic analysis of the bone structure at an isotropic spatial resolution of 200 microm in examination times of <10 min. Differences in the structure of the spongy bone between normal and markedly osteoporotic subjects are well depicted. The SNR at 3T was found up to 16 times higher than at 1.5T applying unchanged imaging parameters. CONCLUSION: The proposed high-resolution MRI technique offers high potential in the diagnosis and follow-up of diseases with impaired bone structure of hand and/or wrist in clinical applications.     

Imaging of bone micro-injuries

PURPOSE: We evaluated the fundamental signs of each imaging modality to define the role of MRI in identifying and characterizing bone micro-injuries. MATERIALS AND METHODS: We retrospectively reviewed 50 MRI examinations performed after preliminary conventional radiography on 25 stress fractures and 25 insufficiency fractures between 1989 and 2002. The number of lesions identified was 55: 11 were evaluated with CT and 9 with radionuclide bone scan. RESULTS: Although bone micro-injuries have different pathogenetic mechanisms, the final outcome is a cortical and/or spongy bone fissure, followed by repair processes. Conventional x-ray showed the presence of a lesion in 24/55 cases. Radionuclide bone scanning allowed suspicion or confirmation of the lesion in 8/9 cases. MR identified the lesion in all cases. CT allowed recognition of the lesion in 10/11 cases. CONCLUSIONS: When a bone micro-injury is suspected following conventional radiography, MRI is the most sensitive and specific modality able to complete the diagnostic work-up.     

骨斑点症的影像学表现(附6例报告及文献复习)

目的:提高对骨斑点症的影像学认识.方法:对6例患者均行全身骨X线检查,4例行CT与MRI检查.结果:6例患者发病均较广泛并双侧对称,病灶呈大小不等的圆形,类圆形硬化结节.大部分病灶位于骨松质内,并与骨小梁走行一致,少部分位于骨皮质内.相邻关节软骨无异常改变.结论:骨斑点症X线、CT、MRI表现均具有特异征象,可明确诊断.     

Quantitative vertebral x-ray computed tomography. Results in 105 women consulting for osteoporosis

Quantitative vertebral CT scan imaging is a method developed to provide direct measurements of mineralization of vertebral body spongy tissue, and is presently the most precise procedure for the early detection of spinal osteoporosis. A fracture threshold has been defined below which are found 95% of patients with a crushed vertebra: it is situated at 70% of the value for mineralization normal for the age of patients. Patients with marked reductions in their level of mineralization can be kept under surveillance before the onset of fracture. In patients with vertebral collapses the density is correlated significantly with the number of crush fractures. In addition, measurement of vertebral spongy bone density has allowed the importance of the vertebral lesion to be determined in various osteoporotic disorders, including those with only cortical fractures, and in this way to differentiate them.