兔眼玻璃体内植物性异物常规MRI与磁敏感加权成像研究

目的 探讨兔眼玻璃体内植物性异物常规MRI及磁敏感加权成像(SWI)的诊断价值.方法 实验动物120只,右眼玻璃体内分别植入1枚直径0.3 mm、长3 mm的植物性异物,其中海棠木、竹子、松木、桃枝、仙人掌刺、麦芒各20枚,以左眼为对照,不植入异物,均于术后2 h行常规MRI及SWI序列检查.结果 对于120枚兔眼玻璃体内植物性异物,T1WI、T2WI、PDWI、SWI分别检出20、119、64、120枚,所检出的异物除SWI序列的相位图呈高信号、混杂高信号或低信号外余均呈低信号.T1WI、PDWI 检出异物直径较实际植入异物直径小;T2WI检出异物直径与实际植入异物直径基本一致;SWI检出异物直径较实际植入异物直径大.结论 T2WI,SWI诊断兔眼玻璃体内植物性异物较T1WI、PDWI更敏感,且异物在SWI上具有放大效应,SWI可作为眼玻璃体内微小植物性异物的优选检出手段,是常规MRI的重要补充.     

兔眼玻璃体内鱼刺异物的MRI表现

目的:探讨兔眼玻璃体内鱼刺异物的MRI表现。方法:选取16只新西兰健康大白兔,将其右眼玻璃体内随机植入2枚鱼刺异物,异物直径0.15～0.20mm、长度1.5～3.5mm,左眼作为正常对照,均于术后2h行MRI检查。结果:T1WI检出4枚鱼刺异物,T2WI检出15枚鱼刺异物,PDWI检出6枚,SWI检出26枚。检出的异物在T1WI、T2WI、PDWI、幅值图、最小信号强度投影(mIP)图及磁敏感加权(SWI)图上呈点状或线状低信号,相位图上呈高信号或混杂高信号。结论:兔眼玻璃体内鱼刺异物的MRI表现具有特征性,SWI序列的应用可提高兔眼玻璃体内鱼刺异物的检出率。     

兔眼玻璃体内木质异物的磁敏感加权成像研究

目的 探讨兔眼玻璃体内木质异物的磁敏感加权成像(SWI)的特点.方法 取实验兔48只,右眼玻璃体内分别植入1枚直径0.2 mm、长2 mm的木质异物,以不植入异物的左眼为对照,于术后2小时行SWI序列检查.结果 对于48枚兔眼玻璃体内木质异物,SWI序列检出率为100％,检出的异物呈点状或条状,在幅值图、最小信号强度投影(mIP)图及SWI图上呈低信号,相位图上31枚呈低信号,13枚呈高信号.SWI序列检出异物直径较异物实际直径大.结论 兔眼玻璃体内木质异物在SWI序列上具有特征性,异物在SWI上具有放大效应,SWI序列可用于兔眼玻璃体内微小木质异物的检出和诊断.     

兔眼玻璃体内鱼刺异物的磁敏感加权成像实验研究

目的探讨兔眼玻璃体内鱼刺异物的磁敏感加权成像(SWI)表现。材料与方法取16只健康新西兰大白兔,将每只兔的右眼玻璃体内随机植入2根直径0.15～0.2mm、长1.5～3.5mm的鱼刺异物,左眼玻璃体不植入异物作为对照,所有兔均于术后2h行SWI序列检查。结果 16只兔中,12只右眼玻璃体内2根鱼刺异物在SWI序列上均显示,2只仅显示1根,2只均未显示。所检出的26根鱼刺异物在SWI序列幅值图、最小密度投影(MinIP)图及SWI图上均呈点状或线状低信号,在相位图上亦呈点状或线状,其中18根呈高信号,8根呈混杂高信号。结论兔眼玻璃体内鱼刺异物在SWI序列上具有特征性,SWI序列幅值图、MinIP图、SWI图以及相位图联合应用有助于兔眼玻璃体内鱼刺异物的检出和诊断。     

USPIO增强MRI检测兔动脉粥样硬化斑块的实验研究

目的:探讨USPIO增强MRI检测兔动脉粥样硬化(AS)斑块的可行性及价值.方法:健康雄性新西兰大白兔30只,随机分为实验组20只,对照组10只.实验组采用球囊导管损伤主动脉内膜结合高脂饮食的方法建立兔动脉粥样硬化模型,对照组不做干预.观察USPIO增强前后AS斑块MRI信号表现,并与病理检查结果行对照研究.结果:12例兔AS模型成功建立,扫描范围内共发现普鲁士蓝染色阳性斑块67个,USPIO增强前后信号明显改变者共53个.USPIO增强T_2WI及T_2~*WI表现为斑块中央信号减低,其负性强化峰值出现在注射对比剂后96h.USPIO增强3D-TOF序列表现为管壁点状充盈缺损.病理检查发现,氧化铁颗粒主要沉积在内膜下、泡沫细胞中以及泡沫细胞融合崩解的粥样坏死物中.结论:USPIO增强MRI能检出并反映兔动脉粥样硬化斑块成分,有望用于对AS病变诊断及斑块稳定性的评估.     

球内异物伤玻璃体切割术后视乳头区荧光造影观察

目的 观察球内异物伤玻璃体切割术后视乳头区的眼底荧光造影(FFA)特征.方法 观察行玻璃体切割手术的19例(21眼)球内异物伤病例,术后2~6个月行FFA检查.结果 球内异物伤玻璃体切割术后,5眼出现视乳头早期局部弱荧光,12眼出现视乳头后期强荧光.结论 球内异物伤玻璃体切割术后,视乳头异常荧光改变比例较高,提示玻璃体切割术后视乳头处血管损伤比例可能较高,这可能为玻璃体切割术后视力不佳原因之一.     

海水对兔眼视网膜形态学的影响

目的观察海水进入兔眼玻璃体后不同时间视网膜组织的形态学改变。方法25只健康成年新西兰白兔按伤后30min、2h、6h、12h和24h随机均分为5组,以每组动物右眼为实验眼,左眼为自身对照眼。实验眼玻璃体中注射0.5ml实验用人工海水,对照眼注入0.5ml平衡盐溶液。分别在伤后30min、2h、6h、12h和24h用光学显微镜和透射电子显微镜观察视网膜的组织形态学变化。结果对照组兔眼视网膜组织结构层次清楚,染色均匀,细胞形态规整,未见明显病理改变。实验眼30min组视网膜神经节细胞层稍水肿,2h组神经纤维水肿明显,视网膜内节线粒体肿胀,空泡变性。6h时内核层细胞数开始减少,12h组视网膜神经节细胞层和内核层出现细胞核碎裂、边集,细胞数目明显减少。光感受器细胞内线粒体空泡变,核膜皱缩,内陷,内外节空泡变明显增多。结论海水进入兔眼玻璃体早期即可引起视网膜组织形态学发生改变,随着时间的延长,组织损伤逐渐加重。6~12h即发生不可逆性改变。     

球后麻醉致一过性黑朦2例

球后麻醉致一过性黑朦者比较少见,我们在手术中遇到2例,特报告如下: 患者杨某某,因左眼老年性白内障入院,查:右眼视力3.0,眼压2.73kPa,晶体混浊,B 超查玻璃体及视网膜未见异常。入院后行右眼白内障囊外摘除术,常规消毒,铺单后,2％利多卡因行右眼注射,注入2.5ml,五分钟后患者述无光感,此时眼压指测正常,眼球无突出,分析认为视神经麻醉可能性最大,     

兔运动对骨软骨骨折转归的影响:MRI表现与MMP-13表达

目的：观察实验兔运动对骨软骨骨折转归影响及骨片覆盖软骨MMP-13表达,探讨骨软骨骨折与剥脱性骨软骨炎的关系。方法：随机选用30只月龄及体重相近的健康新西兰大白兔,雌雄不限;试验组20只建立兔膝股骨髁骨软骨骨折模型,假手术对照组10只,所有模型均不进行内固定及外固定。术后即进行术侧膝关节间歇主动活动（IAM）与间歇被动活动（IPM）;术后1、2周分别从试验组中随机抽取10只实验兔行MRI检查、大体观察、组织学检查,假手术对照组10只于术后2周行上述检查。MRI扫描序列包括TSE-T1WI、TSE-T2WI、T2WI/SPAIR、3D/WATSc/FFE/T1WI。结果：术后1、2周,骨折线均清晰,骨软骨骨折片移位14（14/20）;骨片覆盖软骨术后2周较术后1周损伤重（P〈0.05）;骨折区成纤维细胞数术后2周较术后1周多（P〈0.05）。术后第2周,股骨髁骨折处骨质增生,MRI示薄层低信号,骨片内部分骨小梁坏死;骨片覆盖软骨MMP-13表达,术后2周较术后1周表达程度明显增高（P〈0.05）,对照组仅2（2/10）只轻度表达。结论：运动可使兔股骨髁骨软骨骨折愈合不佳,术后2周变化类似剥脱性骨软骨炎的特点;骨软骨骨折后骨片覆盖软骨MMP-13表达升高,对临床治疗骨软骨骨折及评价预后具有重要意义。     

软组织内非金属异物嵌入伤MRI检出及其临床价值

目的:探讨软组织内非金属异物嵌入伤MRI检出及其临床价值.方法:对6例患者分别行X线及MRI检查,对照分析MRI影像特征及手术结果.结果:6例患者X线检查均为阴性,MRI发现6处异物(6个)均经手术证实,异物发现率100％.6例异物于T1WI上呈略高信号,T2WI上呈等信号或稍低信号,STIR像上均呈低信号,其周围可见...     

多模态影像技术评价冠状动脉微循环障碍模型的实验研究

目的:探讨多模态影像技术评价山羊动物模型冠状动脉微循环障碍（CMD）的价值。方法:雌雄不限,按5~8月龄随机挑选实验用萨能奶山羊10只。麻醉后经股动脉选择性插管,于不同分支冠状动脉远端缓慢注入1 ml单分散聚苯乙烯微球混合液（含微球计数约1.14×10 6/ml）,建立CMD动物模型。成功建模7 d后行双能...     

The cerebral effects of carbon dioxide during digital subtraction angiography in the aortic arch and its branches in rabbits.

PURPOSEWe studied the neurotoxicity of carbon dioxide as a contrast agent in the central nervous system by performing CO2 digital subtraction angiography (DSA) in the aortic arch and its branches in experimental animals.METHODSTwenty-five rabbits underwent intraarterial CO2 DSA while under general anesthesia, during which 50 angiograms were obtained after administration of 3 mL/kg CO2. MR imaging was performed before and after the angiographic procedure. The animals were killed 12 hours later and their brains examined macroscopically and microscopically.RESULTSThree animals died of a cause irrelevant to CO2. No animal had clinical symptoms of hemiplegia or stroke. Neither MR imaging nor macroscopic and microscopic examination of the brain revealed any ischemic infarct hemorrhage, thrombosis, or foci of necrosis.CONCLUSIONThe absence of neurologic symptoms, the lack of pathologic findings at MR imaging, and the negative pathologic findings in the brain encourage further research on CO2 neurotoxicity of the central nervous system and support its application in the imaging of intracranial vessels.     

MR of optic papilla protrusion in patients with high intracranial pressure.

PURPOSETo evaluate the signal characteristics of the optic papilla (optic nerve head) on routine cranial MR images in patients with clinical evidence of optic papilla elevation caused by high intracranial pressure, and to compare these findings with findings in healthy adult volunteers.METHODSWe reviewed retropectively the MR imaging examinations of 15 patients who were referred with objectively decreased visual acuity and funduscopic findings of optic papilla elevation. T1-weighted and T2-weighted axial MR images were obtained by using conventional spinecho acquisitions on 1.5-T MR imagers. In addition, the MR imaging studies in 10 healthy adult volunteers without visual impairment were reviewed as controls.RESULTSIn 10 (67%) of the 15 patients, visual elevation of the optic papilla was shown by MR imaging. In all 15 patients, the MR signal intensity of the optic papilla was hypointense relative to the vitreous of the globe on T2-weighted images. In the healthy volunteer group, the optic papillae were all similarly hypointense relative to the vitreous of the globe on T2-weighted images; however, these optic papillae were flat.CONCLUSIONClinical examination and MR imaging may show elevation of the optic papilla in patients with high intracranial pressure. When chronic, optic papilla elevation has been shown to correlate well with severe loss of vision. Actual edema of the optic papilla seems to play little role in the physical elevation observed clinically in the chronic stages of this pathologic process.     

Whole-body MR imaging in children: principles, technique, current applications, and future directions

In whole-body magnetic resonance (MR) imaging, the entire body from the vertex to the toes is imaged in one or more planes with one or multiple sequences to allow evaluation of multisystem diseases in a single examination. Whole-body MR imaging is particularly useful for examining children because it does not involve exposure to radiation and allows a complete work-up for disease staging within a single session of sedation or anesthesia. At whole-body MR imaging with a sliding table platform, a body coil may be used, but the resultant images have a low signal-to-noise ratio (SNR) and low resolution; use of a combination of phased-array coils results in images with an improved SNR and higher resolution. As whole-body MR imaging techniques undergo further refinement, the role of the modality in oncologic and nononcologic imaging continues to expand. Its use in the staging of lymphoma and other malignancies has been studied extensively. Whole-body MR imaging does not provide functional information and cannot yet be used to differentiate benign from malignant lymphadenopathy. However, whole-body MR imaging performed with integrated diffusion-weighted sequences may complement or replace positron emission tomography, which involves substantial radiation exposure. Other promising avenues for future research include whole-body MR imaging at 3 T and the combination of molecular imaging or positron emission tomography with whole-body MR imaging.     

Intraocular tumors: evaluation with MR imaging

Sixty-seven ocular tumors were studied with magnetic resonance (MR) imaging and computed tomography (CT). These tumors included primary uveal melanoma (n = 55), circumscribed choroidal hemangioma (n = 3), diffuse choroidal hemangioma (n = 1), retinal capillary hemangioma (n = 1), medulloepithelioma (n = 1), choroidal nevus (n = 1), retinoblastoma (n = 1), and choroidal metastases (n = 4). MR imaging demonstrated all these lesions, while CT demonstrated 88%. Associated retinal detachment was more easily distinguished from the neoplasms with MR imaging. Extrascleral extension of melanoma and hemorrhagic cystic necrosis within the melanoma were clearly demonstrated with MR imaging, but not with CT. Ninety-three percent of melanomas were markedly hyperintense, compared with the intensity of the vitreous body, on T1-weighted images and hypointense on T2-weighted images. All metastatic lesions were isointense on T1-weighted images and hypointense on T2-weighted images. The circumscribed choroidal hemangiomas were hyperintense on T1-weighted images and isointense on T2-weighted images. MR imaging is superior to CT in detection of intraocular tumors and may be more specific in diagnosis.     

Magnetic resonance imaging in the evaluation of osteochondritis dissecans of the patella

OBJECTIVE: The objective was to evaluate the magnetic resonance (MR) appearance of patellar osteochondritis dissecans (OCD). MATERIALS AND METHODS: We retrospectively analyzed MR images of 16 patients (18 cases, mean age 20 years) using OCD of the patella. In 5 cases surgery was carried out, and we compared the surgical findings with the MR imaging findings in these cases. RESULTS: In all 18 cases, OCD was located central-inferiorly on the patella, and the average size was 11 x 11 x 7 mm. Subchondral deformities were present in 16 out of 18 cases (88.9%), subchondral cyst formation in 4 cases (22.2%), reactive bone marrow signal in 8 cases (44.4%), overlying patellar cartilage abnormality in 14 cases (77.8%), loose body in 2 cases (11.1%), patella alta in 8 cases (44.4%), hypoplastic sulcus in 7 cases (38.9%), and synovitis in 4 cases (22.2%). In all 5 cases in which surgery was carried out, the cartilage abnormality classified on the MR images was confirmed, and a loose body was removed at arthroscopy in 2 of the 5 cases. CONCLUSION: Magnetic resonance imaging of patellar OCD typically shows subchondral deformity and variable abnormalities of the overlying patellar cartilage located central-inferiorly on the patella.     

Percutaneous translumbar spinal cord compression injury in a dog model that uses angioplasty balloons: MR imaging and histopathologic findings

BACKGROUND AND PURPOSE: Previous animal models for spinal cord injury required laminectomy and exposure of the spinal cord to create direct trauma, compromising imaging by both surgical artifact and the nature of the production of the injury. Our purpose was to study a model that uses percutaneous intraspinal navigation with an angioplasty balloon, providing a controlled degree of spinal cord compression and allowing improved MR imaging of spinal cord injury. METHODS: Nine mongrel dogs were studied. MR images were obtained of six dogs after technique development in three dogs. Angioplasty balloons measuring 7 or 4 mm in diameter and 2 cm in length were placed in the midthoracic subarachnoid space. Imaging was performed by using a 1.5-T MR imaging unit before and after balloon inflation. The balloon was inflated within 5 seconds and deflated after 30 minutes. T1- and T2-weighted and contrast-enhanced images were acquired. Spinal cords were submitted for pathologic examination. RESULTS: All four animals with 7-mm balloons experienced hemorrhage, and three had axonal injury revealed by histopathologic examination. One of two animals with 4-mm balloons experienced no injury, and one had axonal injury without hemorrhage. Regional parenchymal enhancement was seen in two of the animals with 7-mm balloons. CONCLUSION: This percutaneous spinal cord injury model results in a graduating degree of injury. It differs from previous techniques by avoiding surgical exposure and the associated artifacts, yet it offers histopathologic findings similar to those of human spinal cord injury. The canine spinal cord is amenable to MR imaging with clinical imaging units. Further evaluations with various durations of compression and various balloon sizes are warranted.     

Gadolinium-enhanced MR imaging, T2-weighted MR imaging, and transurethral ultrasonography

PURPOSE: To assess the value and problems of dynamic gadolinium-enhanced MR imaging, T2-weighted MR imaging, and transurethral ultrasonography(TUUS) in staging of urinary bladder cancer. MATERIALS AND METHODS: Dynamic gadolinium-enhanced MR imaging and FSE T2-weighted MR imaging of 64 patients with urinary bladder cancer who subsequently had surgery were retrospectively reviewed and compared with TUUS findings. RESULTS: Specificity for muscular invasion was 90.5% with TUUS, significantly better than with dynamic MR imaging (64.9%) (p < 0.05). The rates of overestimation of superficial cancer(pT1) with dynamic MRI and T2-weighted MR imaging were 35.1%(13/37) and 24.3%(9/37), respectively. The staging accuracy of invasive cancer(pT2 or over) was 85.2% with dynamic MR imaging, which was better than the rate of 75.0% achieved with T2-weighted MR imaging. CONCLUSION: Although TUUS was a better modality for diagnosing superficial cancer(pT1), dynamic MR imaging was found to be better for diagnosing invasive(pT2 or over) cancer.     

Iron particles enhance visualization of experimental gliomas with high-resolution sonography

BACKGROUND AND PURPOSE: Intraoperative MR imaging and sonography are used for navigation during neurosurgical procedures. The purpose of this experimental study was to evaluate the potential of high-resolution sonography using superparamagnetic iron oxide (SPIO) particles as a contrast medium to delineate brain tumors and to relate these findings with those of MR imaging. METHODS: C6 gliomas were implanted in 36 rats. Eleven days after tumor implantation, the animals underwent MR imaging with a 1.5-T MR imaging unit. Twelve animals received gadopentetate dimeglumine immediately before the MR examination, 12 animals were injected with SPIO particles 24 hours before MR imaging, and 12 animals received no contrast agent. Immediately after MR imaging, the animals were sacrificed and their brains were removed and placed in saline. Sonography was performed instantly after brain removal. Brains were embedded in paraffin, and sections were stained for iron with Perl's stain and for macrophages with ED-1 immunohistochemistry. RESULTS: At MR imaging, the tumors appeared hyperintense on T2-weighted and gadolinium-enhanced T1-weighted images. After application of SPIO particles, they became markedly hypointense on T2-weighted images and hypo- to hyperintense on T1-weighted images. On sonograms, gliomas were iso- to slightly hyperechoic to normal brain parenchyma on nonenhanced and on gadolinium-enhanced images. After application of SPIO particles, tumors became markedly hyperechoic and were distinctly demarcated from the surrounding brain tissue. CONCLUSION: SPIO particles improved the detection and demarcation of the experimental gliomas on sonograms, which may improve intraoperative neuronavigation with sonography.     

Small (<20 mm) enhancing hepatic nodules seen on arterial phase MR imaging of the cirrhotic liver: clinical implications

OBJECTIVE: To determine the significance in patients with cirrhosis of small (<20 mm) hepatic nodules that show no hyperintensity on T2-weighted MR images but that enhance during arterial phase MR imaging, we reviewed the cases of patients with such nodules. MATERIALS AND METHODS: Our review of radiology reports yielded 68 nodules in 40 patients with cirrhosis that showed no hyperintensity on T2-weighted MR images but had rapid enhancement during arterial phase MR imaging after administration of a gadolinium contrast agent. Thirty-four patients (60 nodules) had multiple follow-up MR imaging examinations (range of length of follow-up, 1-72 months; average length of follow-up, 15 months 2 weeks). The final diagnosis of the nodule was determined by pathology reports or after at least 2 years of follow-up to ensure nodule stability and, therefore, benignity. Two radiologists independently reviewed MR images of the nodules, noting the size, signal intensity on T1- or T2-weighted images, and homogeneity of contrast enhancement. RESULTS: Nine (13%) of the 68 nodules were hepatocellular carcinomas (HCCs). The size of nodules on the first MR examination was between 4 and 20 mm (mean size, 9.5 mm). No significant correlation between the diagnosis of HCC and nodule signal intensity (p = 0.48) or contrast enhancement homogeneity (p = 0.56) on first MR examination was found. Positive predictive value (PPV) and negative predictive value (NPV) for diagnosing HCC on the basis of nodule growth were 100% and 98%, respectively. For diagnosing HCC on the basis of a change in nodule signal intensity, the PPV was 60% and the NPV was 91%. For diagnosing HCC on the basis of a change of enhancement homogeneity, the PPV was 63%, and the NPV was 94%. CONCLUSION: A finding of growth in small, early-enhancing nodules in patients with cirrhosis is highly predictive of HCC. When small nodules are observed on a single examination, close follow-up of the patient appears appropriate.