MR直接关节造影在腕三角纤维软骨复合体损伤中的应用

目的 通过与腕关节镜结果对照,探讨MR直接关节造影在腕三角纤维软骨复合体(TFCC)损伤中的作用.方法 14例临床怀疑腕TFCC损伤的患者接受了常规MRI和MR直接关节造影,其中10例行腕关节镜检查.MR直接关节造影在腕拇长伸肌腱与伸指总肌腱间隙(相当于桡舟关节间隙)处进针,注入5～7 ml的钆喷替酸葡甲胺(0.1 mmol/L)混合液(0.3 ml钆喷替酸葡甲胺+100 ml生理盐水),与腕关节镜结果相对照,分析常规MRI和MR直接关节造影表现.结果 (1)14例中TFCC尺侧撕裂5例,桡侧撕裂4例,整体损伤5例(包括2例长期类风湿关节炎).(2)在脂肪抑制序列(STIR)及T2和T1WI序列上,损伤的TFCC表现为高信号或等信号,正常的低信号部分或完全消失,MR直接关节造影显示4例桡侧撕裂在腕TFCC的下尺桡关节和5例尺侧撕裂在尺骨茎突附着处可见不同程度的高信号对比剂聚集,5例整体损伤在下尺桡关节和尺骨茎突附着处均可见对比剂.MR直接关节造影表现与腕关节镜结果在损伤部位相符合,包括4例桡侧撕裂,3例尺侧撕裂和3例整体损伤.(3)14例腕TFCC损伤患者,8例伴有下尺桡关节半脱位,6例伴有尺桡骨骨挫伤,常规MRI和MR直接关节造影均可清晰地显示其滑膜反应和骨髓水肿等表现.结论 MR直接关节造影可以清晰地显示腕TFCC损伤,同时与常规MRI相结合能显示伴随的滑膜反应和骨髓水肿.     

MRI间接膝关节造影诊断半月板损伤的价值

目的:探讨MR I间接膝关节造影诊断半月板撕裂的价值。材料和方法:选取MR I平扫疑似半月板损伤32例,静脉注射常规剂量(0.1mmol/kg)与双倍剂量(0.2mmol/kg)造影剂(Gd-DTPA),运动后延时扫描。参照MR I平扫片对比两组不同浓度MR I关节造影表现。结果:两种不同浓度造影均可使半月板撕裂的高信号增加,以采用0.2mmol/kg造影效果较好。32个半月板,造影后确诊半月板撕裂18例(占56.3%),排除诊断8例(占25%),确诊和排除诊断合计占81.3%,6例可疑,可疑的6例经关节镜检查排除诊断3例。结论:对半月板损伤MR I平扫不能肯定诊断时,行间接膝关节造影对确定或排除诊断是十分必要的。0.1mmol/kg Gd-DTPA能达到诊断目的。     

Gd-DTPA动态增强MRI评价心肌微血管损伤

目的：探讨Gd-DTPA动态增强MRI评价心肌微血管损伤的可行性。方法：制作急性犬心肌梗死动物模型，在活体上用放射微球^99Tc—MAA测量心肌血流量，0．5％伊文蓝染色区分缺血心肌；心脏离体后用3％TTC染色区分梗死心肌，SP免疫组化染色观察心肌微血管并计算微血管体积分数。犬离体心脏左冠状动脉插管后作MRI平扫及Gd—DTPA动态增强扫描，测量正常、缺血和梗死心肌的信号强度，绘制时间-信号强度曲线。结果：在T1WI上，心肌信号强度无明显差异；在T2WI上，病变心肌信号强度较正常增高；Gd-DTPA灌注动态增强扫描，正常心肌时间-信号强度曲线呈下降形，危险心肌呈上升形，梗死心肌呈平直形，灌注晚期病变区呈明显环状强化。正常、危险和梗死心肌血流量、微血管体密度差异显著。结论：急性心肌梗死后心肌间质水肿、心肌含水量增加致T2WI信号增高。Gd-DTPA动态增强时间-信号强度曲线上升的斜率及峰值可以反映心肌微血管损伤及组织水肿的程度。     

肾上腺疾病的磁共振影像诊断

本对37例共43个肾上腺病灶的MRI作定性和定量分析，结果表明，（1）MR可清晰显示大于1.0cm的病灶及其与周围结构的关系；（2）MR对腺瘤与转移瘤的鉴别有较大的帮助，T2WI腺瘤类似于肝脏的信号强度，转移瘤与脂肪的信号强度相似；（3）嗜铬细胞瘤的MRI有特异性，T2WI呈明显高信号，45%见散在点状短T2低信号区。     

乳腺纤维腺瘤的MRI表现及与病理对照

目的观察乳腺纤维腺瘤的多种MRI表现，分析其病理基础，从而加深对纤维腺瘤的认识，提高MRI诊断准确率。方法对33例乳腺纤维腺瘤患者（38个病灶），行常规MR平扫和动态增强检查。所有病例均经病理证实，分析比较病灶的MRI形态学、信号强度及其动态增强特点等。结果33例38个乳腺纤维腺瘤的形态学表现以分叶状、类圆形为主，占89．5％（34／38）。MRI显示内部信号多较均匀，T1WI呈等、低信号，T2WI信号多样化，高信号者的黏液样变明显（平均指数1．9），间质细胞丰富（平均指数2．2）；呈低信号者间质多硬化，间质细胞分布稀疏。不同信号强度的2种指数差异有统计学意义（x^2值分别为11．267、10．415，P值均〈0．05）。肿瘤有完整的包膜，边界多清晰者占86．8％（33／38）。增强后无或轻度强化（5／38）、明显强化（33／38）；不同强化曲线的2种指数差异无统计学意义（x^2=1．171、2．861，P〉0．05）。强化程度与患者的年龄构成有一定的相关性，年龄较轻者，强化多明显。无强化分隔者（9／33），是由于瘤体内部间质纤维组织胶原化形成。结论乳腺纤维腺瘤的MR T2WI信号及强化程度表现多样化，和其瘤体内黏液硬化程度及间质细胞含量相关。认识纤维腺瘤的特征性MRI表现有助于鉴别诊断。     

颞颌关节区腱鞘巨细胞瘤的MRI表现

【摘要】目的:探讨颞颌关节区腱鞘巨细胞瘤（GCTTS）的MRI表现。方法:回顾性分析经手术病理证实的14例颞颌关节区GCTTS的MRI资料，所有病例均行颌面部常规3.0T MRI平扫及增强扫描，其中8例行磁共振动态增强（DCE-MRI）扫描，2例行1H-MRS检查。结果：14例GCTTS均呈弥漫性生长，伴明显骨质破坏，以膨胀性、溶骨性破坏为主，6例同时伴膨胀性、溶骨性骨质破坏，并出现颞颌关节间隙增宽及颅底组织的侵犯。14例GCTTS中，在T1W I上呈等低信号10例（10/14）、等信号3例(3/14)、混杂高信号1例(1/14)；在T2WI上病灶呈稍高信号6例（6/14）、低信号5例（5/14），混杂信号3例(3/14)。注射Gd-DTPA增强后，9例呈轻中度强化，4例呈明显强化，1例未见明显强化。DCE-MRI结果显示，7例时间-信号强度曲线（TIC）为速升平台型，1例为持续上升型。2例1H-MRS扫描均在3.2ppm处可见明显Cho峰。结论:颞颌关节区GCTTS表现为弥漫性、侵袭性生长；T1WI上以等/等低信号为主，T2WI上信号多样，可呈低、高及混杂信号；注入Gd-DTPA增强后可出现轻中度强化、明显强化；TIC以速升平台型为主。     

间接磁共振关节造影在色素沉着绒毛结节性滑膜炎中的应用

目的探讨间接磁共振关节造影在色素沉着绒毛结节性滑膜炎(pigmented villonodular synovitis,PVNS)中的诊断价值。资料与方法回顾性分析12例经手术及病理证实的PVNS患者的常规MRI、间接磁共振关节造影(indirect MR arthrography,I-MRa)资料。结果12例PVNS患者中关节滑膜呈弥漫性增生肥厚者10例,局限性2例。常规MR表现为T1WI等信号,T2WI高信号2例;T1WI、T2WI均为低信号9例。I-MRa表现为在关节积液的极高信号背景下增生肥厚滑膜呈中等强化的高信号,并对周围正常组织有不同程度的侵蚀。结论I-MRa与常规扫描序列相结合,不仅能更清晰地显示出病变累及的范围和程度,而且还可以显示滑膜对关节骨质的侵蚀、反映病变的血供等病理改变,从而可进一步提高PVNS定性及分期的准确性。     

中枢型神经纤维瘤病的临床表现与MR影像特征(附4例报告及文献复习)

目的 研究中枢型神经纤维瘤病（神经纤维瘤病2型，NF2）的临床表现与MR影像特征。方法 4例可疑NF2患于临床症状出现或加重后3周至2年内行头颅Gd-DTPA增强前后MRI检查，NF2的MRI诊断得到手术与病理证实。同时，记录了每例患的临床表现。结果 MRI平扫显示，NF2病灶的特征性表现为T1WI上呈低，等信号，而在T2WI上呈高信号，Gd-DTPA增强后，病灶呈明显强化，MRI还证实了4例NF2患均合并脑膜瘤，这些患最常见的症状是进行性耳聋，耳鸣，眩晕，步态不稳。结论 NF2具有恒常的能通过对比增强MR像证实的强化特征，因此，头颅Gd-DTPA增强前后MRI检查应成为诊断MF2的主要手段。     

弥散法MR膝关节造影可行性研究

目的评价MR对比剂静脉内注射、膝关节腔内弥散关节造影的可行性研究并寻找最佳检查参数. 资料与方法选取膝关节正常者24名,按常规方法进行扫描后再将其分为运动组和未运动组.每组再分为3小组.3个小组分别从静脉注入不同剂量的Gd-DTPA.注射完后未运动组受检者静卧于检查床,进行延迟扫描;运动组步行10 min后再进行扫描,并进行延迟.扫描结束后,对平扫和增强图像中的关节腔周围组织及关节腔内信号进行测量.采集后的数据按组归类,并进行统计处理,观察对比剂注射后关节腔内信号增加程度并选取最佳检查方法. 结果弥散法膝关节造影可使关节腔信号强度明显增加,与周围组织产生明显信号差,以采用注射剂量为0.2 mmol/kg体重,注射后受检者正常步行10 min后造影效果最佳. 结论弥散法MR膝关节造影可起到关节造影的效果,造影效果良好,是一种操作简单、危险性小、并发症少的检查方法.     

穿膜肽标记异硫氰酸荧光素及钆喷替酸葡甲胺行MR分子显像的探讨

目的选择穿膜肽的基本序列之一，构建目的多肽序列标记异硫氰酸荧光素（FITC）及钆喷替酸葡甲胺（Gd-DTPA），探讨穿膜肽携带FITC及Gd-DTPA跨膜转运性能及MR分子显像的价值。方法在穿膜肽9聚精氨酸[arginine]基础上，构建新目的多肽序列CPP13：LAGRRRRRRRRRK，固相合成多肽后标记FITC（记为CPP13-FITC）和Gd-DTPA（记为CPP13-DTPA-Gd）；分别取CPP13-FITC和FITC溶于无血清Dulbecco最低必须培养液（DMEM）培养基中，待HEPG2细胞及鼠骨髓干细胞爬片上生长至80％-90％汇合时，取2只30mm^2皿，弃去培养皿中培养液，一皿中加入CPP13-FITC／DMEM溶液，另一皿中加入FITC／DMEM溶液，37℃CO2孵箱中抚育10、30、60min时依次取出1片，磷酸平衡盐溶液（PBS）冲洗爬片后置于倒置荧光显微镜上观察细胞内出现荧光素分布的时间和部位。CPP13-DTPA-Gd作用肝癌细胞株HEPG2后，MRI研究CPP13-DTPA-Gd在细胞内转运性能及MRI的特点，将CPP13-DTPA-Gd溶于无血清DMEM培养基中，浓度为3mg／ml。待HEPG，细胞在100mm。培养皿中长至80％-90％汇合时，取3只皿分别加入CPP13-DTPA-Gd的DMEM溶液、DTPA-Gd／DMEM溶液和DMEM溶液，孵育30min后弃去培养液，以0．1MPBS反复冲洗，胰酶消化，加入2m 1l％琼脂糖／PBS溶液混匀，装入2ml离心管中，将3管固定于装有150ml 1％琼脂糖／PBS溶液的微量加样枪头盒中，待凝固后测定MR信号。结果固相合成多肽成功，测定分子量为1792．78，与理论值接近。纯度达到95％以上；标记荧光素后，倒置荧光显微镜观察细胞摄取显示10min时肝癌细胞株HEPG2和鼠骨髓干细胞胞质与细胞核内均出现荧光分布；CPP13标记的Gd-DTPA，作用细胞30min后MRI显示CPP13-DTPA-Gd作用HEPG2细胞组呈短TI、短T2信号。3层面内3组细胞感兴趣区T1信号强度（Ii）与琼脂糖T1信号强度（Io）的比值及统计学分析如下：（1）号管3层面内Iil／Io（为CPP—DTPA-Gd作用cell组管内信号值与管外烧杯内琼脂糖背景信号值的比值）分别为：2．84、2．60、2．48；（2）号管3层面内Ii2／Io（为Gd-DTPA作用cell组管内信号值与管外烧杯内琼脂糖背景信号值的比值）分别为1．15、1．11、1．12；（3）号管3层面内Ii3／Io（为空白cell对照组管内信号值与管外烧杯内琼脂糖背景信号值的比值）分别为1．13、1．11、1．11。两两组间F检验：（1）与（2）：F（I．2）=201．88（P〈0．001）；（1）与（3）：F（1．3）=206．37（P〈0．001）；（2）与（3）：F（2．3）=0．529（P=0．507）。说明T1WI信号强度与Gd-DTPA作用组及与单纯细胞组信号强度比较差异有统计学意义；HEPG2细胞不摄取Gd-DTPA，30min时信号强度与单纯细胞组信号强度间差异无统计学意义。结论在穿膜肽基本序列基础上成功地重新构建的多肽能够携带荧光素和MR对比剂，并有效地跨膜转运进入细胞，为MR分子显像提供了1种新的重要手段。     

In vitro study of relationship between signal intensity and gadolinium-DTPA concentration at high magnetic field strength

Although gadolinium-diethylene triamine pentaacetic acid (Gd-DTPA) has been used as a contrast material in MRI, it is known that the contrast enhancement effect is not uniform for high concentrations of Gd-DTPA. In order to evaluate the proper pulse sequences for dynamic MRI in aqueous solutions of Gd-DTPA, blood samples and melanoma cells, the signal intensity for several concentrations of Gd-DTPA were measured under inversion recovery (T1-weighted) at high magnetic field strength (7.0 Tesla). For aqueous solutions of Gd-DTPA, signal intensity correlated linearly with the concentration of Gd-DTPA between 0 mmol/L and 4 mmol/L. Using blood and melanoma cells, signal intensity correlated non-linearly with the concentration of Gd-DTPA between 0 mmol/L and 1.5 mmol/L. For concentrations of more than 4 mmol/L in aqueous solutions of Gd-DTPA, 1 mmol/L in blood and 1.5 mmol/L in melanoma, signal intensity decreased with increased Gd-DTPA concentration.     

Effect of field strength on gadolinium enhancement in MR imaging

This studv was designed to evaluate the influence of magnetic field strength on the relative enhancement effect (RE) of gadolinium (Gd)-chelates. Dilution series of two paramagnetic contrast agents (Gd-DTPA and Gd-DOTA) were examined in three commercially available MR systems. operating at different field strengths (02 T, 1. T, and 1.5 T). The RE was plotted against Gd concentration. The highest increases in signal intensity occurred with Gd concentrations of approximately L.0 mmol/L. No significant difference in RE was observed between MR systems ranging in field strength from 0.? T to 1.5 T. The RE of Gd-DTPA and Gd-DOTA was found to he equivalent.     

Contrast-dose relation in first-pass myocardial MR perfusion imaging

PURPOSE: To determine the regime of linear contrast enhancement in human first-pass perfusion cardiovascular magnetic resonance (CMR) imaging to improve accuracy in myocardial perfusion quantification. MATERIALS AND METHODS: A total of 10 healthy subjects were studied on a clinical 1.5T MR scanner. Seven doses of Gd-DTPA ranging from 0.00125 to 0.1 mmol/kg of body weight (b.w.) were administered as equal volumes by rapid bolus injection (6 mL/second). Resting periods of 15 minutes were introduced after delivery of Gd doses >0.01 mmol/kg b.w. For each subject, two series of rest perfusion scans were performed using two different multislice saturation-recovery perfusion sequences. Maximum contrast enhancement and maximum upslope were obtained in the blood pool of the left ventricular (LV) cavity and in the myocardium. The range of linear contrast-dose relation was determined by linear regression analysis. RESULTS: MR signal intensity increased linearly for contrast agent concentrations up to 0.01 mmol/kg b.w. in the LV blood pool and up to 0.05 mmol/kg b.w. in the myocardium. For Gd concentrations exceeding these thresholds the signal intensity response was not linear with respect to the contrast agent dose. CONCLUSION: Quantitative evaluation of cardiac MR perfusion data needs to account for signal saturation in both the LV blood pool and the myocardium.     

Pseudolayering of Gd-DTPA in the urinary bladder

When excreted gadolinium diethylenetriaminepentaacetic acid (DTPA) collects in the bladder of a supine patient during magnetic resonance (MR) imaging, a puzzling pattern of signal intensities is noted. A gradual change in urine signal intensity with progressive addition of Gd-DTPA does not occur; instead, three sharply defined "layers" are seen both on T1- and T2-weighted images within the urine-Gd-DTPA mixture. The physical basis for this triple-layering phenomenon was investigated. A bladder phantom was constructed to reproduce the phenomenon. T1 and T2 relaxivities of urine doped with varying concentrations of Gd-DTPA were measured in vitro; measured signal intensities corresponded closely to predicted intensities. Early urine concentrations of excreted Gd-DTPA may be relatively high (10-40 mmol/L), resulting in extremely short T1 and T2 values (less than 30 msec). These extremely short relaxation times cause an artifactual pseudolayering of signal within the urine-Gd-DTPA mixture.     

Potential contrast agents for MR arthrography: in vitro evaluation and practical observations

In an attempt to identify an ideal contrast agent for MR arthrography, signal behavior as well as T1 and T2 values for articular cartilage, menisci, and ligaments were determined in knees from cadavers and normal volunteers. Comparison was made with similar data derived for intraarticular blood, varying concentrations of an albumin-saline solution (simulating synovial fluid) and Gd-DTPA, 0.9% saline, Renografin 60%, and air. Cadaveric specimens were imaged after intraarticular administration of each substance. A 500-microM volume of Gd-DTPA proved to be an ideal contrast agent for MR arthrography, exhibiting excellent contrast differences with articular structures on T1-weighted images. An albumin concentration of 12%, potentially occurring in severe inflammatory arthritis, also manifested adequate contrast to articular cartilage on T1-weighted images. Renografin and saline provided inadequate contrast on T1-weighted images, and saline necessitated the use of T2-weighted sequences. Air was not found to be an optimal contrast agent. Intraarticular blood exhibited insufficient contrast differences with articular cartilage during the acute hemorrhagic phase. Synovial fluid associated with severe arthritis as compared with fresh intraarticular hemorrhage may thus prove to be a better biological contrast agent for MR arthrography. Saline is currently recommended for use in arthrography, but Gd-DTPA offers significant advantages and should be safety-tested for potential clinical use.     

Effects of iodinated contrast and field strength on gadolinium enhancement: implications for direct MR arthrography

PURPOSE: To optimize direct magnetic resonance (MR) arthrography by determining the effect of dilution of gadolinium in iodinated contrast, saline, or albumin on T1-weighted, T2-weighted, and gradient-recalled echo (GRE) images, and the effect of scanner field strength. MATERIALS AND METHODS: Gadopentetate dimeglumine was diluted into normal saline, albumin, or iodinated contrast (0.625 mmol/liter to 40 mmol/liter). Samples were scanned at 1.5T and 0.2T. Signal intensity was measured using T1-weighted spin-echo (SE), T2-weighted SE, and two- and three-dimensional GRE (20 degrees-75 degrees flip angle) sequences. Graphical analysis of signal intensity vs. gadolinium concentration was performed. RESULTS: Albumin had no effect on gadolinium contrast. Dilution of gadolinium in iodinated contrast decreased signal intensity on all sequences compared to samples of identical concentration diluted in saline at both 1.5T and 0.2T: with a 2 mmol/liter gadolinium solution at 1.5T, signal was decreased by 26.1% on T1-weighted images, 31.7% on GRE20 images, and 28.9% on GRE45 images, and the T2 value decreased by 71.1%; at 0.2T, signal was decreased by 23.5% on T1-weighted images. On all sequences, the peak signal shifted to the left (lower gadolinium concentration) when diluted in iodinated contrast. Peak signal was also seen at different gadolinium concentrations on different sequences and field strength: at 1.5T, peak in saline/iodine was 2.5/0.625 mmol/liter on T1-weighted images, and 2.5/1.25 mmol/liter on GRE20 and GRE45 sequences. At 0.2T, peak in saline/iodine was 0.625-2.5/1.25 mmol/liter on T1-weighted images, 0.625-2.5/1.25 on GRE45 images, 2.5-10.0/1.25-5.0 mmol/liter on GRE65 images, and 1.25-5.0/0.625-1.25 mmol/liter on GRE75 images. CONCLUSION: Dilution of gadolinium in iodinated contrast results in decreased signal on T1-weighted, T2-weighted, and GRE images compared to dilution in saline or albuminfor both 1.5-T and 0.2-T scanners; if gadolinium is diluted in iodinated contrast for MR arthrography, a lower concentration should be used because the peak is shifted to the left. The use of iodinated contrast should be minimized, as it may diminish enhancement and lower the sensitivity and specificity of MR arthrography. Optimal gadolinium concentration for MR arthrography is dependent on scanner field strength and a broader range of gadolinium concentration can be used to provide maximal signal at low field strength.     

In vitro evaluation of alternative oral contrast agents for MRI of the gastrointestinal tract

PURPOSE: In vitro evaluation of different materials as potential alternative oral contrast agents for small bowel MRI. MATERIALS AND METHODS: The T1 and T2 relaxation times of rose hip syrup, black currant extract, cocoa, iron-deferoxamine solution and a commonly used oral contrast material (1 mM Gd-DTPA) were determined in vitro at different concentrations on a 1.0 T clinical MR scanner. T1 values were obtained with an inversion prepared spoiled gradient echo sequence. T2 values were obtained using multiple echo sequences. Finally the materials were visualized on T1-, T2- and T2*-weighted MR images. RESULTS: The relaxation times of the undiluted rose hip syrup (T1=110+/-5 ms, T2=86+/-3 ms), black currant extract (T1=55+/-3 ms, T2=39+/-2 ms) and 5 mM iron-deferoxamine solution (T1=104+/-4 ms, T2=87+/-2 ms) were much shorter than for a 1mM Gd-DTPA solution (T1=180+/-8 ms, T2=168+/-5 ms). Dilution of black currant extract to 30% or a 3 mM iron-deferoxamine solution conducted to T1 relaxation times which are quite comparable to a 1 mM Gd-DTPA solution. Despite its much lower metal content an aqueous cocoa suspension (100 g/L) produced T2 relaxation times (T1=360+/-21 ms, T2=81+/-3 ms) more or less in the same range like the 5 mM iron-deferoxamine solution. Imaging of our in vitro model using clinical sequences allowed to anticipate the T1-, T2- and T2*-depiction of all used substances. Cocoa differed from all other materials with its low to moderate signal intensity on T1- and T2-weighted sequences. While all substances presented a linear 1/T1 and 1/T2 relationship towards concentration, rose hip syrup broke ranks with a disproportionately high increase of relaxation at higher concentrations. CONCLUSIONS: Rose hip syrup, black currant extract and iron-deferoxamine solution due to their positive T1 enhancement characteristics and drinkability appear to be valuable oral contrast agents for T1-weighted small bowel MRI. Cocoa with its differing relaxation and signal enhancement properties is a promising oral contrast agent but needs further clinical evaluation.     

Articular cartilage defects: detectability in cadaver knees with MR

The capability of 1.5-T MR imaging to detect focal defects in articular cartilage was investigated with cadaveric knees with and without intraarticular injection of saline and gadolinium-DTPA (Gd-DTPA). Full-thickness cartilage lesions ranging in diameter from 1 to 5 mm were surgically created in the femoral articular surfaces. Images were acquired with a variety of pulse techniques, slice thicknesses, and interslice gaps as well as one or two signal excitations. Potential intraarticular contrast agents (saline and Gd-DTPA) were tested, and their signal behaviors compared with that of hyaline cartilage. All cartilage defects were occult on T1-weighted and balanced images without Gd-DTPA. The smallest defect identified by using intraarticular saline was 3 mm in diameter and was apparent only on T2-weighted images. Intraarticular Gd-DTPA afforded detection of defects as small as 2 mm, even with short imaging times. Signal-intensity differences between saline and articular cartilage were minimal on T1-weighted images and increased on T2-weighted images; intensity differences were high between Gd-DTPA and articular cartilage on all imaging sequences. These results indicate that intraarticular fluid and appropriate selection of imaging sequences are necessary for delineation of focal defects in articular cartilage. They also show that Gd-DTPA is the optimal contrast agent for this purpose.     

口服静脉用钆喷酸葡胺稀释液改善MRCP质量的研究

目的　口服静脉用钆喷酸葡胺 (Gd DTPA)稀释液作为胃、十二指肠阴性对比剂 ,改善磁共振胰胆管成像(MRCP)质量。资料与方法　实验部分 :取Gd DTPA静脉注射液 1、2、3、4、5、6和 7ml分别加温开水配制成浓度分别为 4 .6 4、9.2 7、13.91、18.5 4、2 3.19、2 7.82和 32 .4 6mg/ml稀释液各 80ml,并依次分组。设立 80ml温开水对照组。行T1WI(SE)和重T2 WI(IR EXPRESS )成像 ,测量各组在不同成像序列的信号强度 ,并计算增强率。临床应用 :对 2 1例经多方位MRCP不能避开胃、十二指肠内高信号背景干扰者 ,行口服稀释液前和后立即、5和 10min放射状多角度MRCP ,然后对各解剖结构显示情况加以判定。结果　浓度为 2 3.19、2 7.82和 32 .4 6mg/ml稀释液在重T2 WI(IR EXPRESS)成像序列中信号强度和增强率最小 ,且无明显差别。口服稀释液前与后 5、10minMRCP图像对胆总管、胰管、胆囊结构的显示具有显著性差异 (P <0 .0 5 ) ;而口服稀释液后 5与 10minMRCP图像对上述结构的显示无明显差异 (P >0 .0 5 )。结论　可选用浓度为 2 3.19mg/mlGd DTPA稀释液 80ml,作为胃、十二指肠阴性对比剂抑制高信号背景 ;口服稀释液后 5min成像可获得较为理想的MRCP图像。