Metallic hip implants: CT with multiplanar reconstruction

Thirty consecutive patients with metallic implants in the hip were evaluated with both standard transaxial computed tomography (CT) and multiplanar reconstruction (MPR) to assess the contribution of MPR. The metallic devices included total hip replacements (n = 6), one or more surgical plates with screws (n = 9), acetabular pins or screws (n = 9), and Knowles pins (n = 6). The metallic implants were on the side of interest in 25 hips and in the contralateral hip in five cases. One patient had bilateral hardware. MPR reformats axially acquired data into other planes. The reconstruction program weights the true signal over the randomly distributed artifacts by integrating adjacent axial images. Examination using standard transaxial imaging was graded as excellent in five cases, adequate in 15 cases, and inadequate in ten cases. After MPR, 19 studies were classified as excellent, 11 were classified as adequate, and none were classified as inadequate. It is concluded that MPR significantly reduced artifacts caused by metal present in transaxial images.     

Analysis of 51 tibial triplane fractures using CT with multiplanar reconstruction

OBJECTIVE: We determined the most common patterns of triplane fractures and assessed the risk of epiphyseal separation in each pattern. MATERIALS AND METHODS: Fifty-one children with tibial triplane fractures underwent CT, and the resultant scans underwent multiplanar reconstruction. We categorized epiphyseal and physeal involvement, the number of fragments, the appearance of the Salter-Harris fracture in each plane, and the degree of separation of the epiphyseal fragments. RESULTS: The classic two-fragment type of fracture with medial epiphyseal extension occurred most frequently (33/51). All three-fragment types (8/51) of fractures resulted in a separate anterolateral fragment. Extension to the medial malleolus was common (12/51). None of the four reported fractures types involving anteromedial physeal separation was seen. Children with epiphyseal separation requiring surgery were older (odds ratio [OR] = 1.7) and had plafond involvement (OR = 5), CONCLUSION: CT and multiplanar reconstruction of triplane fractures improve the understanding of patterns of injury and their relative prevalence.     

Spiral CT with multiplanar reconstruction in the diagnosis of sternoclavicular osteomyelitis

Objective The purpose of this study was to determine whether contrast-enhanced spiral CT scanning supplemented by multiplanar reconstruction is of value in the evaluation of suspected infection of the sternoclavicular joints.Materials and Methods Seven patients with suspected infection of the sternoclavicular joints were evaluated with spiral CT using narrow collimation (4 mm) and close interscan reconstruction (2–4 mm). All patients were scanned immediately following the injection of 120 ml Omnipaque-300 at a rate of 3 ml/s. Spiral CT scans were of 24 or 32 s duration and done as single-breathhold studies. All images were then filmed at soft tissue and bone settings (window width 2300, window center 270). In selected cases, coronal, sagittal, and/or oblique reconstrution of data was done for review.Results All studies were successfully completed without any interscan or intrascan motion. In six cases, infections of the sternoclavicular joint was found, including five cases of osteomyelitis of the clavicular head. The scans obtained during the phase of high contrast enhancement allowed definition of the extension into the soft tissue and muscle. Bone windows demonstrated subtle cortical and periosteal abnormalities.Conclusion Imaging of the sternoclavicular joints with standard CT can be difficult due to interscan motion and the inability to get good data sets for reconstruction. Spiral CT with 24to 32-s acquisition allows high quality images enabling detection of disease and definition of extent of disease, thus helping to guide patient management.     

Multislice helical CT: the value of multiplanar image reconstruction in assessment of the bronchi and small airways disease

We examined 23 consecutive patients (11 males and 12 females with mean age of 56 years) with possible airway diseases to assess the impact of multiplanar image reconstruction (MPR) on the degree of confidence and accuracy in diagnosing bronchial abnormalities and emphysema. The thorax was scanned contiguously at 1 mm slice thickness using Siemens Volume Zoom Multislice CT scanner. Images were reconstructed at 1 mm slice thickness (lung windows L-600HU W-1600HU utilizing high spatial frequency algorithm) in the axial (10 mm apart), sagittal (4 images per lung) and coronal (6 images) plane. Paddle wheel image reconstructions were also performed in the assessment of bronchiectasis. Axial images were assessed with and without the help of MPR by three chest radiologists at two separate occasions (at least 4 weeks apart). The presence of bronchiectasis, emphysema and bronchiolitis in each lobe was documented on a confidence scale of 0 to 3. The overall mean confidence for each observer with and without MPR was compared. Consensus diagnosis was used as the gold standard for the assessment of the diagnostic accuracy of each observer. A confidence score of 2 or more for any lobe was considered diagnostic of the particular airway disease. The diagnostic accuracy for each observer with and without MPR was compared. Consensus reporting diagnosed bronchiectasis in 7 patients (30.4%), bronchiolitis in 5 patients (21.7%) and emphysema in 12 patients (52%). MPR did not increase the confidence of assessing the different abnormalities for all observers but improvement in diagnosing bronchiectasis was noted in two observers. The improvement did not reach statistical significance. However, agreement between observers in the diagnosis of bronchiectasis and emphysema was improved when the MPR images were used in conjunction with standard axial imaging (Kappa statistic improved from 0.29 to 0.54 for bronchiectasis and from 0.7 to 0.81 for emphysema). Agreement on the diagnosis of bronchiolitis was not improved by MPR for all observers. Our results suggest that MPR seems to improve the confidence in diagnosing bronchiectasis and emphysema.     

Helical CT with multiplanar and three-dimensional reconstruction of nonneoplastic abnormalities of the trachea

Helical CT is being increasingly used for the evaluation of suspected tracheal diseases. Although nonneoplastic and noninfectious diseases of the trachea are rare, their appearance on CT images may be highly suggestive of the diagnosis. High quality multiplanar and 3D reconstructions including 3D surface-shaded display and virtual bronchoscopy are helpful to characterize tracheal abnormalities and to demonstrate the location and extent of the diseases.     

多层螺旋CT多平面重组在肺癌术前评价中的应用

多层螺旋CT(MSCT)多平面重组(MPR)技术达到了真正意义的各向同性,能够利用螺旋CT容积扫描数据在任意角度重建出高质量的图像,克服了横段面扫描角度的限制,在影像学诊断中具有重要作用。本文旨在综述MSCT的MPR技术在肺癌术前评价中的应用。     

Image quality of multiplanar reconstruction of pulmonary CT scans using adaptive statistical iterative reconstruction

Objective

We investigated the image quality of multiplanar reconstruction (MPR) using adaptive statistical iterative reconstruction (ASIR).

Methods

Inflated and fixed lungs were scanned with a garnet detector CT in high-resolution mode (HR mode) or non-high-resolution (HR) mode, and MPR images were then reconstructed. Observers compared 15 MPR images of ASIR (40%) and ASIR (80%) with those of ASIR (0%), and assessed image quality using a visual five-point scale (1, definitely inferior; 5, definitely superior), with particular emphasis on normal pulmonary structures, artefacts, noise and overall image quality.

Results

The mean overall image quality scores in HR mode were 3.67 with ASIR (40%) and 4.97 with ASIR (80%). Those in non-HR mode were 3.27 with ASIR (40%) and 3.90 with ASIR (80%). The mean artefact scores in HR mode were 3.13 with ASIR (40%) and 3.63 with ASIR (80%), but those in non-HR mode were 2.87 with ASIR (40%) and 2.53 with ASIR (80%). The mean scores of the other parameters were greater than 3, whereas those in HR mode were higher than those in non-HR mode. There were significant differences between ASIR (40%) and ASIR (80%) in overall image quality (p<0.01). Contrast medium in the injection syringe was scanned to analyse image quality; ASIR did not suppress the severe artefacts of contrast medium.

Conclusion

In general, MPR image quality with ASIR (80%) was superior to that with ASIR (40%). However, there was an increased incidence of artefacts by ASIR when CT images were obtained in non-HR mode.Multiplanar reconstruction (MPR) of CT images plays an important role in the interpretation of the three-dimensional anatomical location or extent of disease, and is an essential technique in daily clinical practice. Multidetector row CT (MDCT) is widely used, and advances in MDCT technology have facilitated better images with thinner slice thickness and extended coverage, which has allowed more MPR images to be evaluated in greater detail. Coronal MPR images produced by MDCT supply good image quality for lung assessment and show similar image quality to axial high-resolution (HR) CT images [1^,2].To further enhance CT image quality, improvements in temporal resolution and/or spatial resolution are needed. MDCT equipped with more rapid gantry rotation or more detector arrays has already evolved for the improvement of temporal resolution. GE Healthcare (Milwaukee, WI) recently produced an MDCT unit containing a new detector composed of garnet, which has a faster response than the previous detector material. This apparatus can provide improved spatial resolution by acquiring more data.Reconstruction algorithms are also important for improved image quality. Although the filtered back-projection algorithm has traditionally been used for image reconstruction, new reconstruction algorithms are being developed. The iterative reconstruction algorithm has already been used for image reconstruction of positron emission tomography (PET) or single photon emission CT (SPECT), resulting in improved image quality [3-6]. Iterative reconstruction was also used in early CT systems and is currently used by many manufacturers of clinical CT systems. Adaptive statistical iterative reconstruction (ASIR), recently developed for CT by GE Healthcare, is expected to improve low-contrast detectability by reducing noise when using the same radiation dose as would be used with filtered back-projection. It is also expected to reduce the radiation dose for a similar noise level compared with filtered back-projection. Until now, the quality of CT images from multiplanar reconstruction using ASIR had not been analysed. The purpose of this study was to evaluate the image quality of MPR using ASIR.     

矢状位重建在脊柱常见病变中的应用

目的 探讨矢壮位多平面重建在诊断脊柱常见病变中的应用方案与价值。方法 选取脊柱常见病人60例，经CT轴位平扫后对原始数据进行矢壮位多平面重建(MPR），并与常规轴位图像(2D CT)进行比较。结果 全部病例中共检出椎间盘突出42例，椎体及附件骨折16例，椎体肿瘤2例。结论 矢壮位多平面重建对脊柱常见病变的CT评价可以延伸到直观、立体地观察椎体及附件、椎间盘、脊髓病变的形态学表现，以及病变部位与周围结构的情况，对制定合理的治疗方案及预后的判断有一定的指导意义。     

Evaluation of multiplanar reconstruction in CT recognition of lumbar disk disease

Axial computed tomographic (CT) images were compared with sagittal and coronal reformations and myelograms in 60 patients to evaluate the diagnostic usefulness of multiplanar reconstructions for the recognition of lumbar disk disease. The axial CT scans were most sensitive and specific. The sagittal scans were helpful in evaluating the neural foramina, the size of the disk bulge into the spinal canal, especially at L5-S1, and patients with spondylolisthesis. The coronal images were the least informative, although they contributed to the evaluation of lumbar nerve roots. The myelograms and the sagittal images were equally useful in the detection of herniated disk, but axial scans were superior to either. It was concluded that reformatted sagittal and coronal images are not required if all axial images are normal. However, when uncertainty exists or complex anatomy is being evaluated, reformatted images may be helpful, particularly for reassurance.     

多层螺旋CT及多平面重组诊断嗜铬细胞瘤的价值

随着多层螺旋CT及三维后处理技术在临床的应用,对肾上腺嗜铬细胞瘤(adrenal pheochromocytomas)的诊断及鉴别诊断有很大的进步。回顾性分析我院自2000年6月~2006年6月期间收集的经手术及病理证实的14例嗜铬细胞瘤患者,探讨多层螺旋CT及多平面重组对嗜铬细胞瘤的诊断价值。1材料与方法1.1一般材料本组14例中,男性11例,女性3例,年龄22~55岁,平均年龄38.5岁。临床表现有腰痛头晕、头痛、心悸、多汗,有阵发性或持续性高血压症状者11例,发作时血压均在190/120~220/170mmHg,无明显临床症状,体检时发现3例。实验室检查24h尿中香草扁桃酸(VMA)1.…     

Coronal multiplanar reconstruction view from isotropic voxel data sets obtained with multidetector-row CT: assessment of detection and size of mediastinal and hilar lymph nodes

OBJECTIVE: To assess the detection and size of mediastinal and hilar lymph nodes by multiplanar reconstruction (MPR) view from isotropic voxel data sets obtained with multidetector-row computed tomography (MDCT). MATERIALS AND METHODS: Thin-section CT of 27 patients with mediastinal or hilar lymph node swelling was obtained with a 25.6-cm FOV, 512 x 512 matrix, and two protocols: A) 0.5-mm collimation, 0.3-mm interval, and B) 2-mm collimation, 1-mm interval. MPR views with a 0.5-mm slice thickness were obtained from these two data sets. Postcontrast axial CT used 5-mm collimation (set C). Two observers evaluated the presence and cranio-caudal length of swollen lymph nodes. Two other board-certified chest radiologists evaluated all three sets and established a gold standard by consensus. RESULTS: The accuracy of detection was 76%, 73%, and 68% for sets A, B, and C, respectively. There was a significant difference between sets A and C (McNemar's test: p<0.05) but not between sets A and B or B and C (p>0.05). The cranio-caudal length of lymph nodes was significantly correlated with the gold standard only in set A (Pearson's correlation coefficient: r=0.53, p<0.05). CONCLUSION: Non-contrast enhanced coronal MPR views constructed from isotropic voxel data sets may be substituted for axial enhanced CT for the evaluation of mediastinal and hilar lymph nodes.     

多层螺旋CT多平面重组观察额隐窝区域气房的临床意义

目的 应用多层螺旋CT的多平面重组(MPR)技术观察额隐窝区域诸气房,为额窦开放术中准确判断额窦开口提供帮助.方法 选择100例无额窦和额隐窝区域病变的患者行头部螺旋CT扫描,应用MPR技术在横断面、冠状面和矢状面3个重组图像上连续观察额隐窝区域诸气房.结果 100例共200侧中,186侧(93.0%)可见鼻丘气房.88侧(44.0%)可见额气房,其中Ⅰ型占51侧(58.0%),Ⅱ型占23侧(26.1%),Ⅲ型占14侧(15.9%).130侧(65.0%)可见筛泡上气房.23侧(11.5%)可见额筛泡气房.11侧(5.5%)可见眶上筛房.36侧(18.0%)可见额窦间隔气房.结论 运用多层螺旋CT的MPR技术可以多方位连续观察额隐窝区域诸气房,加深对该区域诸气房的理解,为内镜额窦开放术提供有价值的影像信息.     

16层螺旋CT三维和多平面重组对儿童先天性脊柱侧弯的评价

目的 运用16层螺旋CT三维（3D）和多平面重组技术对先天性脊柱侧弯患儿进行评估，探讨此技术的优势和临床指导意义。方法 搜集2004年4至10月司27例先天性脊柱侧弯患儿的影像学资料，男13例，女14例，中位年龄3岁。27例均进行了X线片、16层螺旋CT容积3D、标准和曲面多平面重组技术。结果 10例患者有分节异常，6例患者有形成异常，11例患者有复杂的、无法分类的畸形。15例肋骨畸形中，肋骨畸形的主要部分和脊柱旋转在同水平的有7例。8例合并脊髓纵裂，其中6例有完全或不完全的骨性隔。27例中的19例患者，多平面重组和3D图像显示出在常规X线片和常规轴面图像中未发现和认知的畸形并且全面评估了脊柱侧弯的程度，包括11例复杂畸形中7例归类为无法分类的脊柱畸形，4例为单侧未分节的骨桥合并同侧半椎体畸形；4例清晰显示出单侧未分节的骨桥（3例）和双侧骨桥融合（1例）；2例发现了掩蔽的半椎体畸形；2例重新评估了半椎体的类型和数目；27例曲面多平面重组图像更好的显示了椎管形态和脊髓弯曲情况，6例清晰显示椎管内骨性隔的生长方式和形态；4例患者标准多平面重组更好的显示了颅底-C1-C2的解剖和畸形，尤其是颅颈联合部畸形。结论 16层螺旋CT3D和标准或曲面多平面重组图像是诊断先天性脊柱侧弯、分析复杂多发或隐蔽脊柱和肋骨畸形的首选方法，在评价儿童脊柱侧弯的进展、修订手术方案较常规平片和（或）常规CT更具优势和指导意义。     

64层螺旋CT多平面重组与容积再现技术在骨盆与髋关节骨折诊断中的应用

<正>骨盆与髋关节骨折是急诊外伤中的常见疾病,目前,常规X线平片仍是骨科医师的首选辅助检查方法,但骨盆与髋关节结构相对复杂,常规X线平片对骨折的确切程度、骨折和关节的关系,特别是对     

儿童副鼻窦低剂量双螺旋CT轴位扫描多平面重组的应用研究

目的探讨儿童鼻窦低剂量双螺旋轴位扫描多平面重组技术的可行性和合理的扫描参数。方法 50例正常或轻度鼻窦炎年龄1～15岁儿童按扫描参数随机分为5组,每组10例。第1～3组电压120 kV,电流分别为100 mAs、50 mAs、30 mAs;第4组电压100 kV,电流30 mAs;第5组电压80 kV电流30 mAs。用Kruskal-Wallis H检验和Nemenyi法比较各组图像质量有无差异。结果第2～5组的容积CT剂量指数（CTDIvol）与第1组的CTDIvol比较分别减少50%、70%、82%、91%。5组图像质量评分结果之间有显著差异性（χ2=54.15,P〈0.0001）;其中,第2~4组与第1组、第3~4组与第2组、第4组与第3组比较图像质量评分之间无显著差别（χ2=0.19、2.32、0.83、1.19、0.23、0.38,P〉0.05）;第5组与第1~4组比较图像质量评分之间有显著差别（χ2=40.88、35.55、23.74、30.09,P〈0.01）。结论儿童鼻窦低剂量双螺旋轴位扫描多平面重组是可行的,扫描参数低至100 kV,30 mAs,CTDIvol 4.6 mGy仍可满足临床诊断要求。