均一吸收体中SPECT重建多解性的探讨

通过对重建图像噪声特性的分析，间接证明ＳＰＥＣＴ的解具有多样性。分别用ＴｒｅｔｉａｋＭｅｔｚ、Ｇｕｌｂｅｒｇ、富谷武浩等推导的３种等价重建方法和Ｂｅｌｉｎｉ等推导的重建方法，经计算机模拟重建衰减均匀分布的图像，先预置相同的重建图像的空间分辨率，再比较它们的噪声特性。两种方法重建图像的噪声分布：前者近图像边缘时增大，而后者减小，从而间接证明在假定均匀衰减条件下，ＳＰＥＣＴ的重建有多解性。     

L-Dopa-responsive Parkinson's syndrome in association with phenylketonuria: In vivo dopamine transporter and D2 receptor findings.

Reports of parkinsonism in phenylketonuria are exceedingly rare. We report on a patient who had received a delayed diagnosis of phenylketonuria as an infant and subsequently developed levodopa-responsive parkinsonism at the age of 33. Single-photon emission computed tomography (SPECT) using (123)I-FP-CIT ([(123))I]-2 beta-carbomethoxy-3beta-(-4-iodophenyl)-N-(3-fluoropropyl)-nortropane) used to measure dopamine transporter levels on two occasions, 7 and 9 years after the onset of neurological symptoms, were normal. Iodine-123-iodo-lisuride SPECT (IBZM) imaging, however, showed reduced caudate over putamen binding. This combination of imaging findings indicates a possible upregulation of postsynaptic D2 receptors in the context of intact presynaptic dopamine nerve terminal density.     

Single photon emission computerized tomography in childhood hydrocephalus

Single photon emission computerized tomography (SPECT) is now widely used as one of the tools in evaluating cerebral blood flow (CBF). The authors report the CBF changes in childhood hydrocephalus. Five pediatric cases studied by ¹²³I-IM SPECT in children are presented. The authors counted radioactivities both in early and delayed images in each patient, and calculated the reabsorption ratio (RR). Two negative-RR cases and three positive-RR cases were found. All of the negative-RR patients had a poor prognosis, while all of the positive-RR patients had a favorable outcome.     

MRI and SPECT findings in amyotrophic lateral sclerosis

Summary MRI was performed in 21 patients and single photon emission computed tomography (SPECT) withN-isopropyl-p-¹²³I iodoamphetamine in 16 patients, to visualize upper motor neurone lesions in amyotrophic lateral sclerosis. T2-weighted MRI revealed high signal along the course of the pyramidal tract in the internal capsule and cerebral peduncle in 4 of 21 patients. SPECT images were normal in 4 patients, but uptake was reduced in the cerebral cortex that includes the motor area in 11.     

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.     

单光子发射计算机断层扫描在颅脑创伤后的临床研究

目的 探索单光子发射计算机断层扫描（SPECF）在脑外伤评估及预后方面的价值的依据。方法 28例中、重度颅脑损伤患者分别于伤后3天、10天及3～4周接受SPECF、CT检查及临床评定。3个月后所有患者行脑外伤综合征的临床测试，对首检SPECF显像阳性者复查SPECF，分析首检SPECF显像阳性者与损伤程度的关系，动态观察SPECF显像与预后的关系。结果 SPECF显像阳性与脑损伤程度有关，首检SPECF显像阳性提示预后良好，复查SPECF显像阳性提示多出现脑外伤综合征。对幕上损伤患者表现的小脑症状、体征可以做出合理的解释。结论 在中至重度颅脑损伤后SPECF显像与CT扫描比较更敏感，脑SPECF具有无创性、功能性及灵敏性高等特点，是脑外伤后功能评估、预后判断及临床研究的可靠方法。     

Mortality risk associated with ejection fraction differs across resting nuclear perfusion findings

Background  Left ventricular ejection fraction (LVEF) is a significant predictor of morbidity and death. The nuclear summed rest score (SRS) measures myocardial perfusion defects and provides prognostic information, but its effects on long-term outcomes are not fully established. Moreover, information regarding the potential interaction between these 2 covariates is limited. The purpose of this study was to determine whether the mortality risk associated with LVEF is the same across all values of SRS in a population undergoing evaluation for ischemic heart disease. Methods and Results  We examined 3,187 patients who underwent cardiac catheterization and perfusion single photon emission computed tomography imaging with a maximum follow-up of 8.1 years and median follow-up of 3.1 years. Cox proportional hazards modeling showed that increasing nuclear SRS and decreasing LVEF were independently associated with a higher long-term mortality rate, with a clinically significant interaction between them (P=.032). Patients with a normal LVEF and a high SRS (greater perfusion abnormality) have a prognosis similar to those with a reduced LVEF. Conclusions  Resting perfusion studies provide prognostic information for long-term survival and significantly impact the interpretition of mortality risk associated with changes in LVEF. Patient prognostication, risk stratification, and future research using these variables should take this interaction into account. Supported by a grant from the Tom & Lynn Royster Foundation. Durham, NC, and a National Institutes of Health Research Fellowship Grant (T5 GM08679-04), Bethesda, Md.     

Impact of photon energy recovery on the assessment of left ventricular volume using myocardial perfusion SPECT

BACKGROUND: Photon energy recovery (PER) is a spectral deconvolution technique validated for scatter removal in patients and phantom studies. The purpose of this study was to examine the impact of PER on left ventricular volume measurement based on myocardial perfusion single photon emission computed tomography (SPECT). METHODS AND RESULTS: SPECT acquisitions were performed by use of a static cardiac phantom and in 25 patients after a rest injection of technetium 99m sestamibi by use of multiple energy windows (126-136, 137-144, and 145-154 keV). Data were successively reconstructed with and without PER, by use of iterative reconstruction and post-processing filtering (Butterworth filter; order, 5; cutoff, 0.30 cycles/pixel). Image contrast was evaluated in reconstructed data, and volumes were calculated by use of QGS. PER increased reconstructed image contrast from 62% +/- 2.7% to 84.3% +/- 5.7% in the phantom studies (P <.0001) and from 49% +/- 2% to 73% +/- 2% in patients (P <.0001). Although it remained underestimated (P <.0001), phantom volume was higher after PER correction compared with uncorrected data (50.9 +/- 0.8 mL vs 44.6 +/- 1 mL, P <.0001). The error in volume measurement was decreased by PER correction (16.6% +/- 1.3% vs 27% +/- 1.7% [uncorrected data], P <.0001). In patients, left ventricular volume increased from 83 +/- 10 mL to 91 +/- 10 mL (P <.0001), and the PER-induced volume increase was correlated with the image contrast increase (r = 0.61, P =.001). Finally, the percentage of volume increase was higher in patients with small left ventricular volumes. CONCLUSIONS: PER has a significant impact on image contrast and left ventricular volume measurement by use of perfusion SPECT. PER improves the accuracy of phantom volume assessment. In patients, volume increase is correlated to image contrast increase and is higher in those with small ventricles.     

抑郁症的基础与认知激活脑SPECT显像

目的通过抑郁症患者基础和认知激活局部脑血流（ｒＣＢＦ）灌注显像的半定量分析，评估抑郁症患者的脑血流灌注异常。方法选择２７例未经抗抑郁治疗、ＩＣＤ１０分类为中度抑郁发作伴躯体症状的患者，１５例年龄匹配的健康人作正常对照。２７例患者中２１例、１５例健康人中１３例行双日法基础与认知激活脑ｒＣＢＦ显像；另６例患者及２例健康人仅行基础脑ＳＰＥＣＴ显像。认知激活采用Ｗｉｓｃｏｎｓｉｎ卡片分类试验。半定量分析在横断面图像７～１１帧上进行，将各ＲＯＩ的平均计数与同侧小脑的最高计数相除，得到各ＲＯＩ的ｒＣＢＦ比值。结果抑郁症左额叶和左颞叶的基础ｒＣＢＦ值均为０７２０，明显低于对照组（０７６４和０７５０，Ｐ＜００５）；左额、左颞、左顶叶的认知激活ｒＣＢＦ值分别为０７１９、０６９０及０７０１，明显低于对照组（０７８２、０７５２和０７６６，Ｐ＜００１和Ｐ＜００５）。结论①抑郁症患者存在左额叶、左颞叶的局部血流低灌注。②额叶、颞叶皮层低灌注可能是引起抑郁症认知障碍、心境低落的原因。③Ｗｉｓｃｏｎｓｉｎ卡片分类试验认知激活脑ＳＰＥＣＴ显像有助于提高抑郁症的诊断准确性