^99Tc^m-TP5-3 microSPECT/CT探测乳腺癌化疗后细胞凋亡的实验研究

目的 合成新型凋亡显像剂^99Tc^m-半胱氨酸-膜联蛋白V（TP5-3）,研究其在小鼠体内生物分布和药代动力学特点,探讨^99Tc^m-TP5-3 microSPECT/CT检测乳腺癌单次化疗后肿瘤早期细胞凋亡的可行性.方法 以直接还原法对TP5-3进行^99Tc^m标记,HPLC检测产物的标记率;进行正常小鼠体内^99Tc^m-TP5-3的生物分布及药代动力学研究.建立荷MDA-MB-231人乳腺癌裸鼠模型,取10只分为2组,化疗组单次腹腔内注射紫杉醇（每只40 mg/kg）,对照组注射等体积生理盐水,48 h后由尾静脉注射37 MBq ^99Tc^m-TP5-3,进行microSPECT/CT图像采集,显像后立即处死、取材,比较2组肿瘤的放射性摄取（％ID/g）、T/NT（NT取肌肉）;采用流式细胞术和病理学检测肿瘤凋亡细胞.采用单因素方差分析、两样本t检验和直线相关分析数据.结果^99Tc^m-TP5-3标记率＞95％,室温放置4h放化纯仍保持在（96.0±1.5）％,稳定性好.正常小鼠注射显像剂后30 min肾脏放射性摄取最高[（8.48±1.07） ％ID/g],其他脏器分布较少;血液清除快,注射后4h血液放射性摄取[（2.07±0.35） ％ID/g]较注射后5 min[（13.74±4.21） ％ID/g]减少了85％（F=11.310,P＜0.05）;显像剂主要浓聚于肾、肝和胃,经肾脏排泄.化疗后99^Tc^m-TP5-3 microSPECT/CT显像示化疗组T/NT为4.21±0.06,对照组T/NT仅1.57±0.67（f=12.820,P＜0.05）;化疗后生物分布实验示,化疗组肿瘤放射性摄取明显高于对照组,分别为（4.82±0.54） ％ID/g和（1.44±0.38） ％ID/g（t=0.679,P＜0.05）.肿瘤放射性摄取与流式细胞仪测定的凋亡细胞百分比呈正相关（r=0.985,P＜0.05）.HE染色示化疗后肿瘤组织有大量凋亡细胞,而对照组仅有少量.结论 ^99Tc^m-TP5-3标记方法简单,生物分布理想,具备优良的药代动力学特性;^99Tc^m-TP5-3 microSPECT/CT可用于早期检测荷乳腺癌裸鼠模型化疗后的肿瘤细胞凋亡水平.     

喉和鼻咽鳞状细胞癌整合素αvβ3放射性核素显像实验研究

目的 研究99Tcm标记的聚乙二醇(PEG)4修饰的环状RGD二聚体(99Tcm-3P-RGD2)显像用于检测人喉和鼻咽鳞状细胞癌(简称鳞癌)整合素αvβ3表达的可靠性.方法 对荷人HEP-2喉鳞癌、荷人CNE-1鼻咽鳞癌裸鼠各6只进行99Tcm-3P-RGD2平面显像,采用勾画ROI技术计算T/NT.显像结束后,测量99Tcm-3P-RGD2在荷瘤鼠体内的放射性分布,计算肿瘤与各组织器官的％ID/g.取肿瘤组织,行整合素αvβ3免疫组织化学染色,并参照Fromowitz法进行半定量分析.两组间比较采用独立样本t检验,相关性分析采用线性相关法.结果 荷HEP-2、CNE-1裸鼠2h显像时T/NT 分别为2.08±0.04与1.54±0.10.体内放射性分布示:HEP-2肿瘤2h放射性摄取值为(4.56±0.67)％ID/g,肿瘤与血液、肌肉的T/NT分别为6.37±0.68与4.44±0.42;CNE-1肿瘤2h放射性摄取值为(1.69 ±0.18) ％ID/g,肿瘤与血液、肌肉的T/NT分别为2.49±0.09与1.86±0.07.HEP-2、CNE-1肿瘤αvβ3免疫组织化学染色Fromowitz评分分别为4.97±0.37与2.60±0.36.荷HEP-2裸鼠2h显像时T/NT、％ID/g及免疫组织化学染色Fromowitz评分均显著高于荷CNE-1裸鼠(t值分别为11.83、7.17和11.31,P均＜0.05).2种荷瘤鼠2h显像时T/NT与免疫组织化学染色Fromowitz评分的相关性均较好(HEP-2:r2h =0.97,P＜0.05;CNE-1:r'2h =0.97,P＜0.05).结论 99Tcm-3P-RGD2显像有望成为检测喉和鼻咽鳞癌αvβ3表达的无创和有效方法.     

99Tcm标记反义肽核酸探针的制备及其荷瘤裸鼠体内分布

目的 探讨99Tcm标记反义肽核酸(PNA)探针的新方法及其在生物体内的分布.方法 合成12mer且5'端含有四肽G-(D)-A-G-G的c-myc mRNA反义、无义PNA片段,利用G-(D)-A-G-G形成的N4结构为螯合基团进行99Tcm标记,用聚酰胺薄膜层析法和高效液相色谱仪法(HPLC)测定其标记率和标记物的稳定性,并行人结肠癌荷瘤裸鼠体内分布[每克组织百分注射剂量率(%ID/g)]及显像研究.采用SAS 6.22软件对数据进行分析.结果 反义、无义PNA片段合成物的纯度>95%.99Tcm标记c-myc mRNA反义、无义PNA的标记率>95%,标记物室温放置18 h测定其标记率仍可达95%以上.c-myc mRNA反义、无义PNA片段4～8℃下放置3个月标记率仍>95%.HPLC测定标记物呈单峰.99Tcm标记c-myc mRNA反义PNA主要分布在荷瘤鼠肾、脾、肿瘤、肠道、肝组织中,99Tcm标记c-myc mRNA无义PNA在荷瘤鼠血液、脾、肾、肝及肺组织中分布较多;注射后4 h两者在荷瘤鼠肿瘤组织中的分布差异有统计学意义[(1.11±0.12)%ID/g和(0.14±0.02)%ID/g;t=14.75,P<0.01].99Tcm标记c-mycmRNA反义PNA在小鼠体内肿瘤/肌肉、肿瘤/肺的摄取比值较高,肿瘤显像明显.结论 用99Tcm标记c-myc mRNA反义、无义PNA的方法简单,标记率高,标记物稳定,前者有望成为一种新型肿瘤显像剂.     

脂质体介导^99Tc^m-EGFR mRNA反义肽核酸在荷SKOV3卵巢癌裸鼠体内的分布及显像

目的 评价脂质体介导对^99Tc^m-表皮生长因子受体（EGFR） mRNA反义PNA体外靶细胞摄取、荷瘤裸鼠体内特异显像及生物学分布的影响.方法 利用碱基互补配对原则将带有短肽螯合功能的EGFRmRNA反义PNA与部分互补寡核苷酸杂交,再以配体交换法对反义探针进行^99Tc^m标记,然后以脂质体包裹反义探针,用HPLC法鉴定标记物的标记率.分析脂质体介导及非脂质体介导^99Tc^m-EGFR mRNA反义PNA在体外人卵巢癌SKOV3细胞中的摄取率及滞留率的差别,同时分析两者在荷SKOV3卵巢癌裸鼠模型体内生物学分布及显像情况的差异.数据分析采用两样本t检验（或t＇检验）及Wilcoxon秩和检验.结果 脂质体介导及非脂质体介导^99Tc^m-EGFR mRNA反义PNA6h内标记率均在95％以上.两者在注射后1、2、4、6、12及24 h后的细胞摄取率分别为（28.90±1.12）％、（32.76±1.20）％、（38.20±3.11）％、（41.23±1.60）％、（46.63±1.55）％和（46.78±2.14）％,（3.51±0.39）％、（3.90±0.40）％、（4.69±0.18）％、（5.91±0.26）％、（5.30±0.22）％和（5.39±0.17）％,差异有统计学意义（t＇=47.11～58.67,Z=2.80,均P＜0.05）,两者滞留率差异亦有统计学意义（t＇=7.25～11.55,Z=2.80,均P＜0.05）.注射两探针后1h荷瘤裸鼠肿瘤部位均可显像,但脂质体介导使肿瘤显像更为清楚,肿瘤摄取高峰T/NT由3.95上升至5.02,并明显增加注药后各时间点T/NT（t=3.96,t＇=12.65～ 14.69,Z=2.83～5.29,均P＜0.05）.分子探针主要分布在肿瘤、肾脏及肝脏组织中.肿瘤摄取量随时间逐渐增加,1h时非介导组为（1.49±0.09） ％ID/g,介导后为（2.15±0.21） ％ID/g;6 h时分别为（3.90±0.65） ％ID/g和（5.00±0.10） ％ID/g;脂质体介导后可增加注药后各个时间点的肿瘤/肌肉（t=11.24,t＇=3.96～ 11.94,均P＜0.05）.结论 脂质体介导可以明显促进^99Tc^m-EGFR mRNA反义PNA进入细胞,并提高对EGFR高表达肿瘤的显像效?     

99Tcm-J591的制备及荷人前列腺癌裸鼠显像

目的 研究99Tcm-抗前列腺特异性膜抗原(PSMA)抗体J591与前列腺癌细胞体外结合性能、在荷人前列腺癌裸鼠显像及体内分布情况.方法 用改进的Schwarz方法进行99Tcm标记J591,经Sephadex G-50柱分离纯化;用纸层析法和三氯醋酸法测定标记率与放化纯;用流式细胞术测定99Tcm-J591与肿瘤细胞在体外的结合性能.以PSMA阳性的C4-2前列腺癌荷瘤裸鼠为实验组,PSMA阴性的PC3前列腺癌荷瘤裸鼠为对照组,2组均经静脉注射99Tcm-J591 6.2～ 8.5 MBq(25 μg/只)后,分别于2、6、12及24h后行γ显像,利用ROI技术获得各时间点T/NT(NT为对侧肌肉组织).12 h显像后分批处死裸鼠(实验组4只,对照组5只),取肿瘤、心、肝、肾、胃、骨骼、肌肉和血液等组织,测湿质量和放射性计数,计算％ID/g,采用两样本t检验比较2组间差异.结果 99Tcm直接标记J591的标记率为(78.9±6.2)％,放化纯为(92.3±5.1)％,放射性比活度为68.7 MBq/mg.流式细胞术分析结果显示,J591与99Tcm-J591在体外均能结合PSMA阳性的C4-2细胞,与PSMA阴性的PC3细胞不结合.实验组静脉注射99Tcm-J591后6h,肿瘤部位出现明显放射性浓聚,至12 h放射性浓聚范围增大,边缘更清晰,2、6、12和24 h T/NT分别为1.9±1.1、4.3±1.8、5.6±2.7和1.4±0.6;对照组肿瘤部位未见明显放射性浓聚,各时间点T/NT均小于2.体内分布结果显示:注药后12 h,实验组肿瘤放射性为(20.1±5.2) ％ID/g,对照组为(5.8±2.6)％ID/g,两者差异有统计学意义(t=5.37,P＜0.001);其余部位2组间放射性摄取差异无统计学意义(均t＜1.98,均P＞0.05).结论 99Tcm-J591具有良好的免疫活性和生物分布特性,对接种于裸鼠体内的人前列腺癌具有靶向定位性能,可望用于前列腺癌的导向诊断及导向治疗.     

新型骨显像剂99Tcm-BIPrDP的制备及生物学性质研究

目的 探讨99Tcm-1-羟基-3-(2-丁基-1H-咪唑-1-基)丙烷-1,1-双膦酸(BIPrDP)用于骨显像的可能性.方法 以2-丁基咪唑为原料,经过3步反应得到BIPrDP.以SnCl2为还原剂,在100℃下沸煮BIPrDP钠盐溶液(50 mg/ml,100μl)与新鲜淋洗的Na99TcmO4溶液(37.0 MBq)混合液30 min,制得99Tcm-BIPrDP.用TLC测定标记率和稳定性.测定99Tcm-BIPrDP在正辛醇-水中的脂水分配系数(log P)和在新鲜肝素抗凝的人血血浆中的血浆蛋白结合率.向ICR小鼠尾静脉注射0.2 ml (7.4 MBq) 99Tcm-BIP(r)DP,分别在5、10、15、30、60、120和240 min时处死小鼠,取其心、肝、脾、肺、肾、骨骼、肌肉、性腺、肠、胃、脑和血液,测其质量及放射性计数,计算％ ID/g及骨放射性与各组织中放射性的比值.计算血药清除动力学方程.对新西兰兔静脉注射99Tcm-BIPrDP后于不同时问显像.用单因素方差分析方法对不同时间各组织％ID/g进行统计学分析.结果 99Tcm-BIPrDP的标记率和放化纯均＞95％,在放置6h后仍具有很好的稳定性.99Tcm-BIPrDP在pH值为7.0和7.4时的log P分别为-2.396 ±0.035和-2.242±0.025,99Tcm-BIPrDP的血浆蛋白结合率为(47.07±0.05)％.在注射99Tcm-BIPrDP 30 min后小鼠骨摄取达到最大值(19.20％ID/g),且能持久,在4h时为18.98％ID/g.在所有的非靶向性组织中,99Tcm-BIPrDP在肾的摄取最高,5min时为24.50％ID/g,4h为5.22％ID/g.其他重要器官普遍摄取较低,在4h时肌肉和脑最低,分别为0.18 ％ID/g和0.03 ％ID/g.在5 min时99Tcm-BIPrDP在血液中的摄取为18.60％ID/g,随后迅速降低,在4h时仅为0.40％ID/g,血药动力学方程为C ＝9.109e-0.262t+2.696e-0.00558t.从药物清除曲线可看出该药在小鼠体内血液清除速率较快,与小鼠体内分布中的血液清除趋势一致.注射99Tcm-BIPrDP后1h即可获得清晰的兔骨显影,在其他软组织中摄取低,清除快.各组织不同时间％ ID/g差异有统计学意义(F=5.65 ～ 859.24,P均＜0.05).结论 99Tcm-BIPrDP制备方便,骨显影清晰,是一种较有潜力的新型骨显像剂.     

99Tcm-c-myc mRNA反义肽核酸荷结肠癌裸鼠显像

目的 制备99Tcm-c-myc mRNA反义肽核酸(PNA)显像探针,通过反义显像研究99Tcm-c-myc mRNA反义PNA早期诊断结肠癌的可行性.方法 利用化学合成法在c-myc mRNA反义PNA片段的5'端连上4个氨基酸[G-(D)-A-G-G]和1个氨基丁酸(Aba),再利用配体交换法对c-myc mRNA反义PNA行99Tcm标记.并用同样的方法制备99Tcm-c-myc mRNA无义PNA.进行人结肠癌LS174-T荷瘤裸小鼠显像.采用SAS 6.12软件进行统计学处理.结果 99Tcm-c-myc mRNA反义PNA 6h内标记率＞95%.血清孵育5h后标记率为91.1%.无义PNA的标记率与反义PNA基本一致.1h时反义组荷瘤裸鼠右后肢肿瘤部位可清晰显影,4h内未见明显变化.无义组肿瘤部位始终未见明显放射性摄取.注射99Tcm-c-myc mRN反义PNA 1h后,反义组与无义组肿瘤与对侧组织的放射性(T/N)比值分别为5.06±1.35和1.53±0.30,差异有统计学意义(t=4.47, P=0.04).结论 99Tcm-c-myc mRNA反义PNA可在荷瘤裸鼠活体内与高表达c-myc基因的人结肠癌LS174-T肿瘤组织特异结合,在肿瘤反义显像中有潜在的应用价值.     

^99Tc^m-精氨酸-谷氨酸-苏氨酸在荷人肺癌H1299裸鼠体内分布和显像

目的通过研究^99Tc^m-精氨酸-谷氨酸-苏氨酸（RET）在荷人肺癌H1299裸鼠体内的分布及显像,探讨其用于肺癌显像的可行性。方法采用^99Tc^m-直接法标记RET,再行^99Tc^m-RET与NSCLC细胞H1299的结合实验。荷人肺癌H1299裸鼠尾静脉注射^99Tc^m-RET后,行不同时间（15、30min,1、2．4、8、24、48h组各4只鼠）体内分布实验,分别测定组织放射性摄取（％ID／g）;另取荷瘤鼠3只,注射4．81MBq^99Tc^m-RET后于0．5、1、2、4．5、5、6h行γ显像。结果^99Tc^m-直接标记RET的标记率为（93．15±2．02）％,与H1299细胞的最高结合率为（3．56±0．37）％。荷瘤裸鼠尾静脉注射^99Tc^m-RET后4h肿瘤放射性摄取达（4．96±1．05）％ID／g,肝脏、脾脏有较多放射性摄取[（15．89±1．84）％ID／g和（10．83±1．66）％ID／g];而心脏和血液的放射性摄取较少,相应的T／NT分别为5．70±0．21和12．40±0．11。注射^99Tc^m-RET后4．5～6．0h肿瘤显影清晰。结论^99Tc^m-RET具有亲肺癌的特性,有可能成为一种亲肺癌显像剂。     

HER2放射性配体99Tcm-ABH2的制备及荷乳腺癌裸鼠显像

目的 制备99 Tcm-人表皮生长因子受体2(HER2)亲和体(ABH2),探讨其作为HER2阳性乳腺癌分子显像剂的可行性.方法 以葡庚糖酸钠和SnC12·2H2O为标记体系在ABH2上标记99Tcm,测定标记产物的标记率和放化纯,再用PBS和血清测定标记后6.0h内的稳定性.用表达HER2的MBA-MD-361乳腺癌细胞测定99Tcm-ABH2的平衡解离常数(Kd).于4只荷MBA-MD-361乳腺癌小鼠尾静脉注射37 MBq 99Tcm-ABH2,注射后1.0、4.5 h进行SPECT/CT显像,计算肿瘤对肝脏、大脑、肺、心脏、骨骼、肌肉的T/NT,2d后预先注射200 μg未标记的ABH2,再注射37 MBq 99Tcm-ABH2,以相同方法显像,应用单因素方差分析对比不同显像的T/NT.结果 99 Tcm-ABN2标记率在99％以上,其在PBS和血清中都稳定,在血清中37 ℃保温6.0 h放化纯达(95.0±1.0)％.99Tcm-ABH2的Kd为1.7 nmol/L.荷瘤鼠注射99Tcm-ABH2后1.0和4.5h显像见乳腺癌的放射性摄取,99 Tcm-ABH2主要从泌尿系统清除;4.5 h肿瘤对肝脏、肺、大脑、心脏、肌肉、骨骼的T/NT分别为1.81±0.60、8.95±1.13、20.08±6.12、7.61±0.56、10.62± 1.78、11.422.07;阻断后注射99Tcm-ABH2,4.5 h相应T/NT分别为0.60±0.23、3.05± 1.38、5.24±2.17、2.42± 1.02、8.16±2.66、2.76±0.48(F=29.38,P＜0.05).结论 成功制备了高纯度的99Tcm-ABH2,荷瘤鼠实验表明99Tcm-ABH2能够特异地对HER2阳性乳腺癌进行显像.     

99Tcm标记RGD环肽四聚体在神经胶质瘤裸鼠模型中的显像研究

目的 制备99Tcm标记的含有精氨酸-甘氨酸-天冬氨酸(Arg-Gly-Asp,RGD)序列的环肽四聚体99Tcm-联肼尼克酰胺(HYNIC)-E{E[c(RGDfK)]2}2,评价其在整合素αvβ3表达阳性的荷人神经胶质瘤裸鼠模型的生物分布和显像.方法 以HYNIC为双功能螫合剂,以三羟甲基甘氨酸(tricine)和三苯基膦三磺酸钠(TPfffS)为协同配体,采用两步法制备99Tcm-HYNIC-E{E[c(RGDfK)2}2.通过体外受体竞争结合实验比较e(RGDyK)单体、HYNIC-E[c(RGDfK)2二聚体和HYNIC-E{E[c(RGDfK)]2}2四聚体与整合素αvβ3亲和力.生物分布实验数据显示,99Tcm-HYNIC-E{E[c(RGDtK)]2}2主要经肾排泄;注射后1h,肿瘤对99Tcm-HYNIC-E{E[c(RGDfK)]2}2的摄取为99Tcm-HYNIC-E[c(RG-DfK)]2的2倍,分别为(10.32±0．07)％ID／g和(5.15±O.52)％ID／g,与体外受体竞争结合实验数据相一致;注射后4h,肿瘤对99Tcm-HYNIC-E{E[c(RGDfK)]2}2的摄取仍达(9.35.4±1.35)％ID／g,表明标记物在肿瘤中的滞留时间足够长.r显像结果显示,注射后1h肿瘤清晰可见.注射后4h显像效果更佳.结论 99Tcm-HYNIC-E{E[c(RGDfK)]2}2具有较高的肿瘤摄取和较长的肿瘤滞留时间,可以用于整合素αvβ3表达阳性肿瘤的显像;放射性核素(如90Y)标记的RGD环肽四聚体可用于整合素(αvβ3表达阳性肿瘤的治疗.     

Molecular imaging techniques in body imaging

Molecular imaging of the body involves new techniques to image cellular biochemical processes, which results in studies with high sensitivity, specificity, and signal-to-background. The most prevalently used molecular imaging technique in body imaging is currently fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET). FDG PET has become the method of choice for the staging and restaging of many of the most common cancers, including lymphoma, lung cancer, breast cancer, and colorectal cancer. FDG PET has also become extremely valuable in monitoring the response to therapeutic drugs in many cancers. New PET agents, such as fluorothymidine and acetate, have also shown promise in the evaluation of response to therapy and in the staging of prostate cancer. Magnetic resonance (MR) spectroscopy has shown promise in the evaluation of prostate cancer. Breast cancer evaluation benefits from advances in spectroscopic imaging and contrast-enhanced kinetic evaluation of vascular permeability, which is altered in neoplastic processes because of release of angiogenic factors. Superparamagnetic iron oxide (SPIO) particles represent the first of an expanding line of MR contrast agents that target specific cellular processes. SPIO particles have also been used in the evaluation of the cirrhotic liver and at MR lymphangiography.     

Molecular imaging: integration of molecular imaging into the musculoskeletal imaging practice

Chronic musculoskeletal diseases such as arthritis, malignancy, and chronic injury and/or inflammation, all of which may produce chronic musculoskeletal pain, often pose challenges for current clinical imaging methods. The ability to distinguish an acute flare from chronic changes in rheumatoid arthritis, to survey early articular cartilage breakdown, to distinguish sarcomatous recurrence from posttherapeutic inflammation, and to directly identify generators of chronic pain are a few examples of current diagnostic limitations. There is hope that a growing field known as molecular imaging will provide solutions to these diagnostic puzzles. These techniques aim to depict, noninvasively, specific abnormal cellular, molecular, and physiologic events associated with these and other diseases. For example, the presence and mobilization of specific cell populations can be monitored with molecular imaging. Cellular metabolism, stress, and apoptosis can also be followed. Furthermore, disease-specific molecules can be targeted, and particular gene-related events can be assayed in living subjects. Relatively recent molecular and cellular imaging protocols confirm important advances in imaging technology, engineering, chemistry, molecular biology, and genetics that have coalesced into a multidisciplinary and multimodality effort. Molecular probes are currently being developed not only for radionuclide-based techniques but also for magnetic resonance (MR) imaging, MR spectroscopy, ultrasonography, and the emerging field of optical imaging. Furthermore, molecular imaging is facilitating the development of molecular therapies and gene therapy, because molecular imaging makes it possible to noninvasively track and monitor targeted molecular therapies. Implementation of molecular imaging procedures will be essential to a clinical imaging practice. With this in mind, the goal of the following discussion is to promote a better understanding of how such procedures may help address specific musculoskeletal issues, both now and in the years ahead.     

Molecular imaging will replace myocardial perfusion imaging

Conclusion   “The order is rapidly fadin’. And the first one now will later be last ...” In 2008 myocardial perfusion imaging is the main-stay of nuclear cardiology. However, the lyrics of Dylan from the 1960s are applicable today, as we are in rapidly changing times in medicine. We are seeing a paradigm shift in disease detection and treatment from a focus on cardiovascular morphology, function, and pathophysiology to genetic and molecular events. Cardiovascular molecular imaging will be the vanguard of noninvasive imaging in this era. Nuclear cardiology is uniquely positioned to play a central role in both the clinical and research applications of cardiovascular molecular imaging. The question should not be whether myocardial perfusion imaging will remain the dominant clinical application but how does nuclear cardiology transition to embrace and foster cardiovascular molecular imaging. If we do not do this, there are several other imaging specialties that will be more than willing to fill this void.     

用于肿瘤显像的三种显像剂

肿瘤阳性显像具有较高的敏感性和特异性,易于对肿瘤的原发、复发以及转移做出定性、定位诊断。201Tl、99mTc-甲氧基异丁基异腈已经用于鉴别诊断良恶性病灶、寻找转移灶、评价治疗效果和判断预后,99mTc-氮-二(N-乙基-N-乙氧基二硫代氨基甲酸盐)在肿瘤中的应用则尚在探讨中。     

Optimizing joint imaging: MR imaging techniques

For optimizing MR of the joints, a sophisticated knowledge of MR system hard-and software condition, and coil technologies, sequence and contrast preparation techniques, and the use of paramagnetic contrast agents is necessary. This review article discusses the basic principles of the appropriate use of surfacecoilsas well as the different conventional and fast imagingsequences, including three-dimensional (3D)MR imaging. In addition, the applications of contrast agents as well as the most important contrast prepaation techniques are reviewed.     

Magnetic resonance imaging: Review of imaging techniques and overview of liver imaging

Magnetic resonance imaging (MRI) of the liver is slowly transitioning from a problem solving imaging modality to a first line imaging modality for many diseases of the liver. The well established advantages of MRI over other cross sectional imaging modalities may be the basis for this transition. Technological advancements in MRI that focus on producing high quality images and fast imaging, increasing diagnostic accuracy and developing newer function-specific contrast agents are essential in ensuring that MRI succeeds as a first line imaging modality. Newer imaging techniques, such as parallel imaging, are widely utilized to shorten scanning time. Diffusion weighted echo planar imaging, an adaptation from neuroimaging, is fast becoming a routine part of the MRI liver protocol to improve lesion detection and characterization of focal liver lesions. Contrast enhanced dynamic T1 weighted imaging is crucial in complete evaluation of diseases and the merit of this dynamic imaging relies heavily on the appropriate timing of the contrast injection. Newer techniques that include fluoro-triggered contrast enhanced MRI, an adaptation from 3D MRA imaging, are utilized to achieve good bolus timing that will allow for optimum scanning. For accurate interpretation of liver diseases, good understanding of the newer imaging techniques and familiarity with typical imaging features of liver diseases are essential. In this review, MR sequences for a time efficient liver MRI protocol utilizing newer imaging techniques are discussed and an overview of imaging features of selected common focal and diffuse liver diseases are presented.     

Comparison of contrast-enhanced fundamental imaging, second-harmonic imaging, and pulse-inversion harmonic imaging

RATIONALE AND OBJECTIVES: To investigate the feasibility of recent contrast-specific ultrasound techniques in depicting vascular flow and the effects of changing the output power of the transducer and insonation mode on contrast enhancement, the authors performed an experimental study with a flow phantom. METHODS: While changing the mechanical index and the sound insonation mode (continuous and intermittent), images were obtained with three contrast-enhanced ultrasound techniques: fundamental, second-harmonic, and pulse-inversion harmonic imaging (PIHI) after a bolus injection of microbubble contrast agent. The images were compared on a time-intensity curve. RESULTS: In assessing fixed flow (10 cm/s), PIHI showed the best depiction of flow signal. In intermittent scanning, increases in the mechanical index caused stronger flow signals and longer enhancement duration in all techniques. However, continuous scanning revealed poor depiction of flow signal regardless of the technique or changes in the mechanical index because of significant bubble destruction. CONCLUSIONS: Microbubble-enhanced PIHI with intermittent scanning at a high mechanical index can depict vascular flow highly effectively without shortening the duration of enhancement.     

Undersampled projection-reconstruction imaging for time-resolved contrast-enhanced imaging.

In time-resolved contrast-enhanced 3D MR angiography, spatial resolution is traded for high temporal resolution. A hybrid method is presented that attempts to reduce this tradeoff in two of the spatial dimensions. It combines an undersampled projection acquisition in two dimensions with variable rate k-space sampling in the third. Spatial resolution in the projection plane is determined by readout resolution and is limited primarily by signal-to-noise ratio. Oversampling the center of k-space combined with temporal k-space interpolation provides time frames with minimal venous contamination. Results demonstrating improved resolution in phantoms and volunteers are presented using angular undersampling factors up to eight with acceptable projection reconstruction artifacts.