Role of CT and MRI in the design and development of orthopaedic model using additive manufacturing

Objective

To study the role of Computed tomography (CT) and Magnetic resonance imaging (MRI) for design and development of orthopaedic model using additive manufacturing (AM) technologies.

Percutaneous discography: comparison of low-dose CT, fluoroscopy and MRI in the diagnosis of lumbar disc disruption

Aim: To compare the diagnostic accuracy of low-dose computed tomography (CT), magnetic resonance imaging (MRI) and fluoroscopy in percutaneous discography in patients scheduled for lumbar spondylodesis. Material and methods: Within a prospective pilot study, 18 disc segments of 11 patients with radicular or pseudoradicular pain prior to anteroposterior spondylodesis were evaluated. After injection of a mixture of non-ionic iodine-containing contrast agent and gadolinium-based contrast medium into the disc spaces, all patients underwent conventional fluoroscopy, as well as low-dose CT and MRI. The occurrence of memory pain during contrast injection was recorded. CT, MRI and fluoroscopic images were analyzed independently by two readers blinded to the clinical findings. Results: There was 100% agreement between CT and MRI discography in the detection, localization and grading of degenerative changes. In contrast, conventional fluoroscopy identified only 9 of the 12 abnormal segments. Memory pain following puncture was identified in 3 of the 12 affected segments. Summary: Low-dose CT and MRI discography have a similar accuracy in the assessment of disc disruption and they are superior to fluoroscopic discography.     

Contrast-enhanced MRI versus myelography and contrast-enhanced CT in postdiskectomy problems

Summary The differentiation between scar tissue and disk herniation is essential in postdiskectomy problems of the lumbar spine, since reoperation on scar tissue alone is often unfavourable. Epidural scar is a vascularized tissue, and enhancement can be seen after intravenous contrast injection, allowing differentiation from avascular disk material. Ten patients who had previously undergone surgery for lumbar disk herniation and with recurrent symptoms severe enought to warrant repeat surgery were examined by myelography, magnetic resonance imaging (MRI), and computed tomography (CT) before reoperation. MRI was performed with T1- and T2-weighted sequences in sagittal and axial projections before and after intravenous contrast injection. CT scans were obtained before and during intravenous contrast infusion. Reoperation revealed scar tissue, alone or together with disk, in 9 of 10 patients. Enhancement of scar but not of disk material was observed on MRI in 8 cases, but in none on CT. No enhancement of disk was seen with either modality. The correct diagnosis was given by MRI in 9 of 10 patients and by CT in 3 of 10. CT was superior to MRI in only 1 patient, who had a bony stenosis. Myelography could not separate disk from scar in any case. In conclusion, contrast-enhanced MRI was superior to MRI without contrast, CT before and after contrast, as well as myelography in discriminating disk from scar tissue.     

腹膜孤立性纤维瘤CT和MRI表现与病理对照分析

目的探讨腹膜孤立性纤维瘤的cT和MRI影像学特征及其与病理学的关系。方法回顾分析经手术病理证实的腹膜孤立性纤维瘤的3例CT和2例MRI影像学表现。并与手术病理组织学结果作对照分析。结果本病的CT表现为肿块境界清楚．轮廓光滑,由两种不同密度的实质成分组成,增强扫描显著强化,动脉期瘤内见多条肿瘤血管影,平衡期肿瘤持续显著强化。MRI表现为T1WI与骨骼肌等信号,T2WI高于肌肉信号,增强扫描显著强化。病理学检查：肿瘤由散在分布密集区和稀疏区的梭形细胞组成,瘤细胞间含有粗细不均的胶原纤维。免疫组化：CD34和Vimentin阳性。结论腹膜孤立性纤维瘤的CT、MRI表现具有一定的特征性,CT和MRI对孤立性纤维瘤的诊断具有重要价值。     

下肢慢性淋巴水肿的MRI表现与淋巴闪烁造影的比较

目的探讨下肢慢性淋巴水肿的 MRI 表现和诊断价值。方法对12例慢性淋巴水肿下肢作 MRI 检查,并与淋巴闪烁显像(Lymphangioscintigraphy LAS)相比较。结果 MRI 图像的特征是皮下组织层明显增厚伴广泛水肿;真皮下扩张的淋巴管以及淋巴液潴留在组织间形成“裂隙”使皮下组织层呈典型的网络状或蜂窝状结构。结论 MRI 清晰地显示增生扩张的集合淋巴管和淋巴干及乳糜池,以及组织中乳糜返流的程度和范围。LAS 图像的特征包括显影剂在组织中弥散、积聚(真皮返流)或滞留在注射点;淋巴管显影不充分或不显影;淋巴结延迟显影或不显影及数目和形态的变化。MRI 较全面地显示各级淋巴管、淋巴结以及周围软组织的形态变化。LAS 有助于判断淋巴系统的功能状况。两种检查联合使用,能更全面反映周围淋巴系统的形态解剖及功能的变化,提高肢体慢性淋巴水肿的诊断。     

下肢慢性淋巴水肿的MRI表现与淋巴闪烁造影的比较

目的　探讨下肢慢性淋巴水肿的ＭＲＩ表现和诊断价值。方法　对１２ 例慢性淋巴水肿下肢作ＭＲＩ检查,并与淋巴闪烁显像（Ｌｙｍｐｈａｎｇｉｏｓｃｉｎｔｉｇｒａｐｈｙ ＬＡＳ） 相比较。结果　ＭＲＩ图像的特征是皮下组织层明显增厚伴广泛水肿;真皮下扩张的淋巴管以及淋巴液潴留在组织间形成“裂隙”使皮下组织层呈典型的网络状或蜂窝状结构。结论　ＭＲＩ清晰地显示增生扩张的集合淋巴管和淋巴干及乳糜池,以及组织中乳糜返流的程度和范围。ＬＡＳ图像的特征包括显影剂在组织中弥散、积聚（ 真皮返流）或滞留在注射点;淋巴管显影不充分或不显影;淋巴结延迟显影或不显影及数目和形态的变化。ＭＲＩ较全面地显示各级淋巴管、淋巴结以及周围软组织的形态变化。ＬＡＳ有助于判断淋巴系统的功能状况。两种检查联合使用,能更全面反映周围淋巴系统的形态解剖及功能的变化,提高肢体慢性淋巴水肿的诊断     

肝血管平滑肌脂肪瘤的CT和MRI诊断

目的 探讨肝血管平滑肌脂肪瘤(AML)的MRI与CT影像表现.方法 对2009-2011年我院手术病理证实的12例肝AML临床资料进行回顾性分析.结果 男3例,女9例,发病年龄34～60岁(平均44.17岁).12例共14个病灶,其中发生在肝左叶8个,右叶6个.9例行MRI检查,2例行CT检查,1例同时行CT及MRI检查.8个病灶边界较清晰;8个病灶于MRI和(或)CT上显示出脂肪成分;增强后门脉期至延迟期9个病灶强化程度稍减退或呈高信号;5例见肿瘤压迫周围血管包括门脉及腔静脉,1例左肝静脉早显,6例显示出扭曲畸形的血管.所有病灶均无门静脉癌栓.12例均手术切除并经病理证实为血管平滑肌脂肪瘤.结论 影像学检查显示肝内肿瘤具有良好的边界、瘤内脂肪成分、增强延迟强化及扭曲畸形的血管时应考虑肝血管平滑肌脂肪瘤的可能.     

胰腺黏液性囊性肿瘤的CT、MR诊断

目的分析胰腺黏液性囊性肿瘤（MCN）的CT及MR影像特点。方法18例胰腺黏液性囊性肿瘤均经病理证实,其中囊腺瘤11例,交界性肿瘤4例,囊腺癌3例。患者均进行了CT和（或）MR检查,回顾性分析肿瘤的CT及MR影像表现。结果胰腺黏液性囊性肿瘤平均大小为6．7cm,11例位于胰体、尾：除2例囊腺瘤为单房性无间隔外,其余16例均为多房性。3例囊腺癌囊壁及间隔明显增厚或囊壁上见壁结节,其中2例的囊腔直径大于2．0cm;13例非恶性肿瘤的囊壁及小房间隔较薄且均匀,无壁结节,小房直径大于2．0cm。1例囊壁钙化,4例合并胰腺炎改变,1例合并有胆总管扩张,1例周围血管包绕。结论胰腺黏液性囊性肿瘤的CT及MR表现具有一定的特点,有助于黏液性囊性肿瘤的诊断及鉴别诊断。     

Congenital diastematomyelia in the upper thoracic spine. Diagnostic comparison of CT,CT-myelography,MRI, and US

Diastematomyelia (DM) in the upper thoracic spine is a rare congenital abnormality.The case presented is a comparison of CT, CT myelography, magnetic resonance imaging (MRI), and high resolution ultrasound imaging (US) in a female newborn.     

肝脏肿瘤的CT和MRI检查研究进展

肝脏肿瘤是人体最常见的肿瘤之一,组织类型复杂。CT及MRI在肝脏肿瘤的诊断中至关重要,选择正确的扫描方法、序列、参数及图像后处理技术等直接影响诊断的准确性。本文对肝脏肿瘤的CT及MRI检查技术的研究进展做一综述。     

Two cases of retained foreign bodies after cholecystectomy: Diagnosis by sonography,CT, angiography,and MRI

We encountered two cases of subphrenic abscesses around surgical sponges that had eeen left at cholecystectomy. These cases had been operated on either eight years or seven years earlier, respectively. These lesions resembled another diseases, especially, liver tumors. In order to make a differential diagnosis, various diagnostic procedures were carried out. Sonography showed a cystic mass with spongiform structures in one case. But in another case, no information of internal structures could be obtained because of the presence of a calcified wall. On CT, the lesions appeared as either round or elliptic masses that contained calcified foci in both cases. Angiography showed the extended and compressed branches of the hepatic artery. Spotty stains were also observed in one case. This appearance resembled a hepatic tumor. MR demonstrated both T1 and T2 elongated masses. The internal structures of the mass were clearly revealed by the improved version of the MR machine. MR proved to be extremely useful in making a differential diagnosis. It is, however, important to evaluate the findings of these imaging procedures synthetically and in association with a careful review of a patient's prior surgical history.     

胆囊腺肌瘤病的CT与MRI诊断价值

目的 探讨胆囊腺肌增生症的CT和MRI表现特点,提高诊断正确性.方法 回顾性分析我院2011年8月至2014年3月34例经病理检查证实的胆囊腺肌瘤病(adenomyomatosis of gallbl-adder,GBA)患者的CT和MRI资料.结果 本组行CT检查34例,其中术前确诊为GBA 25例,诊断为慢性胆囊炎5例,漏诊4例;行MRI检查20例,其中术前确诊为GBA 17例,诊断为慢性胆囊炎3例.CT及MRI平扫表现为胆囊壁弥漫性或局限性增厚,部分腔内、外面毛糙不整.增强表现为动脉期黏膜强化,门静脉期强化范围进展,延迟期持续强化,罗-阿氏窦腔内无强化.结论 CT与MRI对胆囊腺肌瘤病有较高的诊断价值,而罗阿氏窦的显示可作为定性的主要诊断依据.     

间质磁共振淋巴造影技术在下肢淋巴水肿中的临床应用

目的 评价皮内注射顺磁性造影剂钆贝葡胺进行间质磁共振淋巴造影的可行性.方法 下肢淋巴水肿进展期患者10例共12侧患肢.在双足第1～4趾蹊背面皮内各注射钆贝葡胺1ml,共8 ml,选择三维容积内插快速绕相梯度回波,并行最大密度投影重建显示淋巴管和淋巴结.结果 10例12侧患肢中有11侧小腿段显示串珠状淋巴管,最佳强化时间在造影后15～30 min,大腿段显示6侧,最佳强化时间在造影后45 min.结论 间质磁共振淋巴造影是一种安全有效可行的显示淋巴水肿下肢淋巴管的新方法.     

Characterization of small (<4 cm) solid renal masses by computed tomography and magnetic resonance imaging: Current evidence and further development

Diagnosis of renal cell carcinomas (RCC) subtypes on computed tomography (CT) and magnetic resonance imaging (MRI) is clinically important. There is increased evidence that confident imaging diagnosis is now possible while standardization of the protocols is still required. Fat-poor angiomyolipoma show homogeneously increased unenhanced attenuation, homogeneously low signal on T2-weighted MRI and apparent diffusion coefficient (ADC) map, may contain microscopic fat and are classically avidly enhancing. Papillary RCC are also typically hyperattenuating and of low signal on T2-weighted MRI and ADC map; however, their gradual progressive enhancement after intravenous administration of contrast material is a differentiating feature. Clear cell RCC are avidly enhancing and may show intracellular lipid; however, these tumors are heterogeneous and are of characteristically increased signal on T2-weighted MRI. Oncocytomas and chromophobe tumors (collectively oncocytic neoplasms) show intermediate imaging findings on CT and MRI and are the most difficult subtype to characterize accurately; however, both show intermediately increased signal on T2-weighted with more gradual enhancement compared to clear cell RCC. Chromophobe tumors tend to be more homogeneous compared to oncocytomas, which can be heterogeneous, but other described features (e.g. scar, segmental enhancement inversion) overlap considerably between tumors. Tumor grade is another important consideration in small solid renal masses with emerging studies on both CT and MRI suggesting that high grade tumors may be separated from lower grade disease based upon imaging features.     

CT vs MRCP: Optimal Classification of IPMN Type and Extent

Introduction Intraductal papillary mucinous neoplasms (IPMNs) of the pancreas are being diagnosed with increased frequency. CT scanning commonly serves as the primary imaging modality before surgery. We hypothesized MRCP provides better characterization of IPMN type/extent, which more closely matches actual pathology. Methods Of 214 patients treated with IPMN (1991–2006), 30 had both preoperative CT and MRCP. Of these, 18 met imaging study criteria. Independent readers performed retrospective, blinded analyses using standardized criteria for IPMN type and extent. Results A ductal connection was detected on 73% of MRCP scans and only 18% of CT. IPMN type was classified differently in seven (39%); four (22%) of which were read on CT as having main duct involvement where this was not appreciated on MRCP or found on surgical pathology. MRCP showed multifocal disease in 13(72%) versus only 9(50%) on CT. A different disease distribution was seen in 9(50%). Finally, 101 branch lesions were identified on MRCP compared to 46 on CT. Conclusions CT falls short of MRCP in detecting a ductal connection, estimating main duct involvement, and identification of small branch duct cysts. These factors influence diagnostic accuracy, cancer risk stratification and operative strategy. MRCP should be employed for optimal management of patients with IPMN. Joshua A. Waters, C. Max Schmidt contributed equally to this work. These findings were presented at the American Hepatopancreaticobiliary Association Meetings in Las Vegas, NV in April, 2007.     

Computed tomography in cases of multiple sclerosis: Problems of differential diagnosis in cases with atypical findings

The value of computed tomography in the diagnosis of multiple sclerosis is undisputed. The examination is usually carried out as a routine part of the examination program.We report on the CT results of 112 patients with confirmed or suspected MS. Seventy-three patients were examined without, 39 with intravenous administration of a contrast medium. In 41% of the patients, isolated or multiple hypodense foci were found as a manifestation of a multilocular demyelinization process. In 17.8%, only cerebro-at-rophic changes were encountered. In 30.3% of the cases the CT showed normal results. In the group of patients examined with a contrast medium, a pathological contrast medium concentration was found in 30.7%.The differential diagnostic demarcation against other diseases of the CNS with similar CT findings and problems of differential diagnosis with MRI are discussed.