Phase-sensitive cardiac tagging--REALTAG.

Fully inverting spins, instead of merely saturating them, provides superior contrast for tagging procedures. The resulting improvement in tag contrast-to-noise ratio (CNR) yields higher-precision tag detection. Also, thinner slices and hence reduced tag separations can be employed, providing displacement and strain measurements with better spatial resolution. Alternatively, the improved tag contrast can be used to obtain cine images covering a greater portion of the cardiac cycle. The use of standard magnitude reconstruction for images of these inversion tags causes rectification of the negative-valued signals from the tags, confounding the image interpretation. Therefore, a phase-sensitive reconstruction scheme of the inverted tags must be employed. Here we demonstrate the implementation of inverted tags with phase-sensitive reconstruction in a ramped-flip-angle, steady-state free precession (SSFP) sequence.     

Vessel-encoded arterial spin-labeling using pseudocontinuous tagging.

A new signal-to-noise ratio (SNR) efficient method is introduced for the mapping of vascular territories based on pseudocontinuous arterial spin labeling (ASL). A pseudocontinuous tagging pulse train is modified using additional transverse gradient pulses and phase cycling to place some arteries in a tag condition, while others passing through the same tagging plane are in a control condition. This is combined with a Hadamard or similar encoding scheme such that all vessels of interest are fully inverted or relaxed for nearly all of the encoding cycles, providing optimal SNR. The relative tagging efficiency for each vessel is measured directly from the ASL data and is used in the decoding process to improve the separation of vascular territories. High SNR maps of left carotid, right carotid, and basilar territories are generated in 6 min of scan time.     

A Bayesian iterative transmission gradient reconstruction algorithm for cardiac SPECT attenuation correction

Background  High-quality attenuation maps are critical for attenuation correction of myocardial perfusion single photon emission computed tomography studies. The filtered backprojection (FBP) approach can introduce errors, especially with low-count transmission data. We present a new method for attenuation map reconstruction and examine its performance in phantom and patient data. Methods and Results  The Bayesian iterative transmission gradient algorithm incorporates a spatially varying gamma prior function that preferentially weights estimated attenuation coefficients toward the soft-tissue value while allowing data-driven solutions for lung and bone regions. The performance with attenuation-corrected technetium 99m sestamibi clinical images was evaluated in phantom studies and in 50 low-likelihood patients grouped by body mass index (BMI). The algorithm converged in 15 iterations in the phantom studies. For the clinical studies, soft-tissue estimates had significantly greater uniformity of mediastinal coefficients (mean SD, 0.005 cm⁻¹ vs 0.011 cm⁻¹; P<.0001). The accuracy and uniformity of the Bayesian iterative transmission gradient algorithm were independent of BMI, whereas both declined at higher BMI values with FBP. Attenuation-corrected perfusion images showed improvement in myocardial wall variability (4.8% to 4.1%, P=.02) for all BMI groups with the new method compared with FBP. Conclusion  This new method for attenuation map reconstruction provides rapidly converging and accurate attenuation maps over a wide spectrum of patient BMI values and significantly improves attenuation-corrected perfusion images.     

直肠癌根治会阴部造口术后二期股薄肌移植肛门成形

目的　回顾性总结32例直肠癌根治会阴部造口术后二期股薄肌移植肛门成形术的治疗效果。方法　采用Williams 5级评分法对重建前后肛门功能进行评价。结果　二期股薄肌移植肛门成形术前,32例患者肛门功能均在4级以上[4级28.4%(9/32),5级71.6%(23/32)],二期股薄肌移植肛门成形术后肛门功能明显好转。结论　二期股薄肌移植肛门成形术是直肠癌根治会阴部造口术后有效的肛门重建手段。     

颈椎肿瘤单侧关节突关节切除后的稳定性重建

目的：探讨颈椎肿瘤单侧关节突关节切除后稳定性重建的方法及效果。方法：对1999—2005年存我院骨科手术治疗且得到随访的18例切除单侧关节突关节的颈椎肿瘤患者的资料进行分析，男10例，女8例；年龄16～72岁，平均46岁。神经根受压表现为主者10例，VAS评分2～8分，平均4．2分；脊髓压迫表现为主者8例．ASIA分级C级5例．D级3例。均采用颈后路患侧关节突关节、侧块切除，完整切除肿瘤组织，其中10例行单侧侧块钢板固定植骨融合，8例行双侧侧块钢板固定植骨融合。结果：随访3—60个月，平均20个月，1例透明细胞癌肺转移患者死亡．余存活无复发。10例神经根受压表现为主者术后疼痛VAS评分0—4分，平均1．6分。8例脊髓压迫表现为主者，5例术前C级者术后C级2例、E级3例，3例术前D级者术后D级2例．E级l例。双侧侧块钢板固定植骨融合者术后3个月4例m现骨性融合（其中1例3个月后失访），6个月7例达到骨性融合，内固定无断裂、松动、移位。无颈椎不稳。单侧侧块钢板固定植骨融合者．1例术后5个月出现颈部疼痛；9例在术后9个月骨性融合；1例12个月时仍未能骨性融合，螺钉松动。结论：颈后路侧块钢板同定植骨融合可以实现颈椎肿瘤单侧关节突关节切除后的颈椎稳定性重建。     

螺旋CT三维重建脊柱的临床意义和应用前景

目的：探讨螺旋CT扫描和三维重建在脊柱病变中的临床应用价值。方法：对12例脊柱疾病患者进行螺旋CT扫描和三维重建。结果：腰椎间盘突出症和椎管狭窄症3例，脊柱骨折5例，侧弯畸形2例，肿瘤2例，均得到正确诊治。结论：螺旋CT扫描及三维重建技术可广泛应用于脊柱病变的诊断，能直观显示脊柱病变部位的形态。     

螺旋CT扫描与多模式三维重建诊断腰椎间盘突出症

目的 探讨螺旋CT扫描容积数据与三维重建诊断腰椎间盘突出症(LDH)的价值。资料与方法 94例行连续容积扫描：准直3～5mm，螺距1．5～3．0，以1．3～2．7mm间距后重建；源影像输入AW4．0工作站，应用多平面重建(MPR)、表面遮盖显示(SSD)和仿真内镜(VE)等软件显示病变，并与椎间盘镜(MED)诊治对照。结果 8例正常；LDH86例：中央型、侧旁、椎间管、椎管外、侧方及混合型分别为19、39、5、2、3、18例。三维重建显示LDH的立体结构为堤坡形、扁丘形、尖丘形、双(多)丘形及游离形分别为34、26、9、5、2例。VE诊断LDH的准确度、灵敏度、特异度分别为95％、100％、80％。VE能模拟MED效果。结论 容积数据与多模式三维重建能提供诊断LDH更全面的信息，并模拟微创手术治疗。     

一种基于μ子进行核材料探测成像的模拟系统

宇宙射线斗子成像检测技术具有穿透力强、对高Z材料敏感等特点，特别适合检测特殊核材料，是监控核材料走私的有效方式之一。在搭建μ子成像检测硬件系统的同时，我们开发了一套针对实际硬件系统的模拟系统，并利用该系统开展斗子成像方法的研究。本文将介绍该模拟系统的有关情况，并给出利用该系统得到的仿真结果。相信这一工作将对实际宇宙射线μ子成像系统的设计给出指导意见。