Ridge number density: A new parameter for in vivo bone structure analysis

An advanced analysis of the mechanical properties of bone should include information about the microarchitecture of cancellous bone in addition to its density. It has recently been shown that high-resolution quantitative computed tomography and magnetic resonance imaging have the potential to assess such information in a noninvasive way in patients. Both techniques, however, lack sufficient spatial resolution to image the individual trabeculae with true precision. In this work, a new parameter, Ridge number density (RND), is introduced. RND is a measure for the trabecular number, which can be extracted directly from high-resolution three-dimensional (3D) images of patients. We applied the RND technique to a test group of nine healthy, postmenopausal women measured repetitively with a high-resolution 3D peripheral quantitative computed tomography (3D-pQCT) system with 165 × 165 × 165 μm³ voxel size. Simultaneously with the RND determination, the trabecular bone density (TBD) was also assessed in the same volume of interest. The examination site was the distal radius. The intersubject variability of the measured test group was 10.5% for RND and 26.3% for TBD. The root mean square error between first and second examinations (midterm reproducibility) was 1.6% and 1.1%, respectively. RND is determined independently from TBD and pertains to the structure of the cancellous bone. As such, it might add crucial information in cases where bone mass or bone density measurements alone give ambigous results.     

儿童后腹膜肿块CT表现

目的：报告儿童后腹膜常见与不常见占位病变的CT表现。材料和方法：对34例（32例经病理证实，2例随访复查证实)儿童后腹膜肿块病例完整的临床及CT检查资料进行分析。结果：本组儿童后腹膜占位病变共有11种．以肾上腺瘤和后腹膜神经母细胞瘤最常见，畸胎瘤和肾胚胎瘤、新生儿肾上腺出血其次．肾上腺皮质癌较少见，罕见的有横纹肌肉瘤和血管外皮瘤。临床和CT特点各有其不同。结论：临床特点与CT表现相结合，极大部分儿童后腹膜肿块可作出明确诊断。     

外伤后迟发性颅内血肿延误诊治20例分析

外伤后迟发颅内血肿是指伤后初次头颅CT检查时未发现颅内血肿,而于1～3 d后再次检查时发现者.     

新生儿颅内出血的临床分析

目的 为探讨各种类型新生儿颅内出血的早期诊断方法，明确其临床特点与CT的关系。方法 对176例经CT证实有颅内出血新生儿的临床资料进行回顾性分析。结果 176例患儿中缺氧所致123例(72．6％)，产伤21例(11．9％)，新生儿出血症22例(12．5％)，早产儿10例。患儿有意识障碍者156例(88．6％)，惊厥98例(55．68％)，肌张力改变113例(64．2％)，原始反射减弱或消失104例(59％)，贫血16例。CT示：SAH121例。占68．75％，为NICH最常见类型；SDH17例，IPH13例，IVH5例，混合性出血20例。结论 根据临床表现考虑NICH者应做头颅CT或头颅B超检查。Cr是确诊的最佳手段，能正确显示出血部位、范围、程度及区分各种类型，头颅B超对早产儿、低出生体重儿的IVH、IPH检出率高。     

SARS流行期间肺炎患者的临床表现和胸部影像变化的探讨

目的 探讨SARS流行期间肺炎患者的临床表现和胸部影像变化特点。方法 对76例SARS流行期间发热留观室收治的肺炎患者的临床表现及胸部影像进行分析。结果 (1)此组肺炎患者多为青壮年(占60．53％)，无固定职业或职业性质流动性较大者居多(69．74％)；(2)临床特征主要是发热，以中高热为多见(80．26％)，发病早期部分患者呼吸道症状并不明显(67．10％)，外周血WBC在正常或低于正常范围(85．53％)，淋巴细胞比例减少(75．00％)；(3)肺部CT表现为不同程度的炎性浸润；病灶形态以斑片状和球形多见(77．63％)；病灶常位于肺周边，常出现支气管气像；动态观察病变影像大多无明显进展(88．16％％)，经治疗均完全吸收。结论 SARS流行期间普通肺炎与非典型肺炎有相似的临床及胸部影像表现；肺部CT扫描能早期发现肺炎患者的异常阴影，明显优于胸片，但无特异性。因此，在SARS流行期间发热诊室医务人员应加强肺部炎性改变的早期诊断和鉴别诊断水平。     

Serial CT findings of Paragonimus infested dogs and the Micro-CT findings of the worm cysts.

OBJECTIVE: To investigate the serial CT findings of Paragonimus westermani infected dogs and the microscopic structures of the worm cysts using Micro-CT. MATERIALS AND METHODS: This study was approved by the committee on animal research at our institution. Fifteen dogs infected with P. westermani underwent serial contrast-enhanced CT scans at pre-infection, after 10 days of infection, and monthly thereafter until six months for determining the radiologic-pathologic correlation. Three dogs (one dog each time) were sacrificed at 1, 3 and 6 months, respectively. After fixation of the lungs, both multi-detector CT and Micro-CT were performed for examining the worm cysts. RESULTS: The initial findings were pleural effusion and/or subpleural ground-glass opacities or linear opacities at day 10. At day 30, subpleural and peribronchial nodules appeared with hydropneumothorax and abdominal or chest wall air bubbles. Cavitary change and bronchial dilatation began to be seen on CT scan at day 30 and this was mostly seen together with mediastinal lymphadenopathy at day 60. Thereafter, subpleural ground-glass opacities and nodules with or without cavitary changes were persistently observed until day 180. After cavitary change of the nodules, the migratory features of the subpleural or peribronchial nodules were seen on all the serial CT scans. Micro-CT showed that the cyst wall contained dilated interconnected tubular structures, which had communications with the cavity and the adjacent distal bronchus. CONCLUSION: The CT findings of paragonimiasis depend on the migratory stage of the worms. The worm cyst can have numerous interconnected tubular channels within its own wall and these channels have connections with the cavity and the adjacent distal bronchus.     

Combining spin echoes with gradient echoes in the context of the global coherent free precession pulse sequence.

To extend the signal longevity of magnetically excited spins in flowing fluids while in a state of global coherent free precession (GCFP), a refocusing radiofrequency (RF) pulse and bipolar gradient waveforms were combined with the GCFP sequence. The data demonstrate that RF refocusing in the presence of flowing blood is possible, but the improvement in signal amplitude depends on the static magnetic field homogeneity along the direction of motion and the displacement of the spins between the excitation and the RF refocusing pulse, as well as displacement during subsequent RF refocusing pulses. The least amount of phase dispersion and thus the longest lasting signal is obtained with the shortest echo spacing where only one line of data is recorded between two RF refocusing pulses. This approach was successfully used in a phantom and in vivo to image fast and slow blood flow. Depending on the experimental conditions, signal persistence is improved significantly compared to playing the same sequence without RF refocusing, but the improvement is limited by the product of blood flow velocity and the time between RF refocusing pulses.     

Epiploic appendagitis and omental infarction: pitfalls and look-alikes

Epiploic appendagitis and omental infarction are benign self-limiting conditions that are more frequent than generally assumed. Both disorders frequently mimic symptoms of an abdominal surgical emergency, often leading to clinical misdiagnosis of appendicitis or diverticulitis. Because a misdiagnosis can result in an unnecessary laparotomy, a correct diagnosis is of great importance. Ultrasound and computed tomography can be used to make a reliable diagnosis. This pictorial essay illustrates the various ultrasonographic and computed tomographic appearances of epiploic appendagitis and omental infarction and focuses on their radiologic differential diagnoses and pitfalls. Received: 22 February 2001/Accepted: 18 April 2001     

低剂量胸部螺旋CT扫描的应用价值

在ＣＴ扫描的各项检查中 ,胸部ＣＴ检查的患者占了很大比例 ,为了减少患者的Ｘ线照射量 ,延长球管的使用寿命 ,同时还要保证影像质量以满足临床诊断的要求 ,我们尝试了采用低剂量胸部螺旋ＣＴ的扫描方法 ,对患有肺部疾病的患者和健康体检人员进行肺癌普查 ,取得了令人满意的结果。1　材料和方法1.1　资料　ＭａｘｃｏｎｉＭｘ80 0 0。我院 2 0 0 1 12 10～ 2 0 0 2 4 10 ,共检查胸部ＣＴ患者 3 46人 ,其中女 12 4人 ,男 2 2 2人 ,年龄 14～ 93岁。1.2　扫描方法　患者仰卧扫描床上 ,手臂抱头 ,先行胸部正位定位像 ,再选择低剂量扫描程序 ,…     

Pelvic granulocytic sarcoma

 Granulocytic sarcoma is an uncommon extraskeletal tumor most frequently associated with leukemia. We present a case of bone location with unusual pattern in a patient with no evidence of myeloproliferative disorder at presentation or follow-up.