Correction of frequency and phase variations induced by eddy currents in localized spectroscopy with multiple echo times.

As a consequence of the time-varying magnetic field induced by eddy currents, frequency drifting occurs when the sampling window of localized spectroscopy continuously shifts. The frequency drifting and the concomitant phase variations can severely affect spectroscopy results when data are acquired with multiple echo times (TEs), such as in the measurement of glutamate (Glu) concentration using the TE-averaged method. Specifically, the averaged spectra are further broadened and distorted in the presence of residual eddy currents, and editing of the coupled spins of Glu C4 protons is affected, resulting in errors in the measured relative intensity ratio. Postacquisition correction using unsuppressed water as reference can effectively minimize this detrimental effect, as manifested by the significantly enhanced signal intensity. Also, it is demonstrated that the methyl signals of creatine (Cr) at 3.0 ppm and choline (Cho) at 3.2 ppm can be used as internal references in finding frequency and phase disparities between different TEs.     

主动呼吸控制技术(ABC)在肺癌放射治疗中的应用

目的：使用主动呼吸控制技术（aetive brething control,ABC）治疗非小细胞肺癌患者，评价呼吸运动时肺部肿瘤动度的影响及ABC技术的优势和可行性，并评价近期疗效和急性放射反应。方法：选择9例使用ABC技术联合三维造型放疗技术治疗的非小细胞系癌患者进行分析。CT定位扫描时分别采集ABC和自由呼吸（free breath.FB）状态下的图像，评价呼吸运动对肺部肿瘤动度和PTV边界的影响唾弃；并比较两种计划的DVH，放疗剂量为54-60Gy/18-20次。3Gy/次，1次/天，5天/周，定期随访，评价近期疗效及急性放射反应。结果：应用ABC技术后，隔肌的平均位移从FB时的43.5mm（20.0-32.0mm）降低为3.6mm（0.5-72.mm）,胸壁的侧方位移从FB时的3.2mm（2.8-4.0mm）降低为1.2mm（0.5-1.6mm）.PTV边界可以从FB时的1.5mm减少为0.75cm;肺的V20从21.8%降低为15.0%,减少了30.6%.中位随访6个月时,9例患者中有6例CR,3例PR.急性放射副反应都很轻微,仅为I-II.结论：在肺癌的精确放射治疗中,呼吸动度的影响不可忽视.而ABC系统可以有效的降低呼吸运动时治疗的影响,提高放疗的精确性,减少副反应.,但该系统使用较为复杂,延长了治疗的时间,个别患者不能忍受.     

组织工程中胶原支架材料的研究进展

组织工程是应用工程学、生命科学的原理和方法来制备具有生物活性的人工替代物,用以维持、恢复或提高人体组织、器官的一部分或全部功能。组织工程的研究主要集中在种子细胞的选择、支架材料的制备、组织工程骨的构建及体内植入相容性情况等方面。其中生物支架材料的选择是组织、器官重建的关键因素之一。理想的细胞种植基质材料应具备：①良好的     

166Ho-DOTMP radiation-absorbed dose estimation for skeletal targeted radiotherapy.

166Ho-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetramethylene-phosphonate (DOTMP) is a tetraphosphonate molecule radiolabeled with 166Ho that localizes to bone surfaces. This study evaluated pharmacokinetics and radiation-absorbed dose to all organs from this beta-emitting radiopharmaceutical. METHODS: After two 1.1-GBq administrations of 166Ho-DOTMP, data from whole-body counting using a gamma-camera or uptake probe were assessed for reproducibility of whole-body retention in 12 patients with multiple myeloma. The radiation-absorbed dose to normal organs was estimated using MIRD methodology, applying residence times and S values for 166Ho. Marrow dose was estimated from measured activity retained after 18 h. The activity to deliver a therapeutic dose of 25 Gy to the marrow was determined. Methods based on region-of-interest (ROI) and whole-body clearance were evaluated to estimate kidney activity, because the radiotracer is rapidly excreted in the urine. The dose to the surface of the bladder wall was estimated using a dynamic bladder model. RESULTS: In clinical practice, gamma-camera methods were more reliable than uptake probe-based methods for whole-body counting. The intrapatient variability of dose calculations was less than 10% between the 2 tracer studies. Skeletal uptake of 166Ho-DOTMP varied from 19% to 39% (mean, 28%). The activity of 166Ho prescribed for therapy ranged from 38 to 67 GBq (1,030-1,810 mCi). After high-dose therapy, the estimates of absorbed dose to the kidney varied from 1.6 to 4 Gy using the whole-body clearance-based method and from 8.3 to 17.3 Gy using the ROI-based method. Bladder dose ranged from 10 to 20 Gy, bone surface dose ranged from 39 to 57 Gy, and doses to other organs were less than 2 Gy for all patients. Repetitive administration had no impact on tracer biodistribution, pharmacokinetics, or organ dose. CONCLUSION: Pharmacokinetics analysis validated gamma-camera whole-body counting of 166Ho as an appropriate approach to assess clearance and to estimate radiation-absorbed dose to normal organs except the kidneys. Quantitative gamma-camera imaging is difficult and requires scatter subtraction because of the multiple energy emissions of 166Ho. Kidney dose estimates were approximately 5-fold higher when the ROI-based method was used rather than the clearance-based model, and neither appeared reliable. In future clinical trials with 166Ho-DOTMP, we recommend that dose estimation based on the methods described here be used for all organs except the kidneys. Assumptions for the kidney dose require further evaluation.     

MR T2加权成像显示胆囊壁增厚点状高信号的意义

目的研究病理组织学证实的胆囊腺肌瘤病、慢性胆囊炎和管壁增厚型胆囊腺癌在MRL加权成像（T2WI）显示病变胆囊壁点状高信号的特征。方法38例患者（胆囊腺肌瘤病16例，慢性胆囊炎13例，管壁增厚型胆囊腺癌9例），每例均进行了MR常规T1WI、常规T2WI和3mm薄层T2WI及MR胰胆管成像（MRCP）。所有患者均接受了胆囊切除手术。2名高年资放射科医生共同分析不同序列MRI，观察胆囊壁增厚及T2WI显示病变胆囊壁点状高信号的不同表现，将观察结果与病理组织学检查所见对照。结果所有患者的胆囊壁均明显增厚，厚度范围5～15mm，平均9mm。T2WI显示病变胆囊壁存在各种各样的点状高信号，在胆囊腺肌瘤病，点状高信号分布于整个增厚的胆囊壁，且数量较多（5～15个／cm^2），较大（直径2～7mm），边界清楚，呈现中等至明显高信号；在慢性胆囊炎，点状高信号主要位于增厚胆囊壁的黏膜侧，数量较少（3～5个／cm^2），较小（直径2～4mm），边界清楚，呈中等至明显高信号；在管壁增厚型胆囊腺癌，点状高信号边界欠清，呈现稍高信号，其数量和大小差异较大，分布范围取决于癌组织浸润胆囊壁的深度。结论胆囊腺肌瘤病、慢性胆囊炎和管壁增厚型胆囊腺癌在T2WI呈现的点状高信号有一定差别，正确识别这些点状高信号的特征有助于鉴别诊断良恶性胆囊壁增厚。     

变温培养对泰乐菌素发酵的影响

在泰乐菌素发酵过程中的不同阶段采用不同的培养温度,通过实验考察其对泰乐菌素发酵的影响。实验结果表明,变温培养的发酵水平要高于其它恒温培养的发酵水平。