客观认识统计参数图评价脑功能影像的作用

上世纪90年代初,英国Hilmmersmith医院Friston等[1]开发了统计参数图(SPM)软件.目前认为SPM是脑功能影像学研究中较为理想的方法.     

Validation of a resolution-independent method for the quantification of 123I-FP-CIT SPECT scans

OBJECTIVE: To verify the applicability of a recently described resolution-independent method for the semi-quantification of 123I-FP-CIT scans. METHODS: Visual interpretation, 'conventional' and resolution-independent semi-quantification was performed on 60 123I-FP-CIT scans. Using ROC analysis, the results were compared to the final clinical diagnosis after a follow-up of at least 18 months. Sensitivity and specificity values were calculated and a cut-off value of the specific binding, which differentiated between normal and abnormal scans with high sensitivity and specificity, was given. RESULTS: Application of the resolution-independent method to a new set of 123I-FP-CIT SPECT data yielded a cut-off value of the specific striatal binding of 55 ml. Corresponding values of sensitivity and specificity were 95% and 72%, respectively. Further, based on the values of the area under the ROC curve and the 95% confidence interval of different semi-quantitative methods, the resolution-independent semi-quantification agreed best with the final clinical diagnosis. CONCLUSION: We found a similar value of the specific 123I-FP-CIT binding as the one previously described in the literature, which proved the validity of the resolution-independent method. Further, this method, among other 'conventional' semi-quantitative methods, agreed best with the final clinical diagnosis. For this reason we recommend its use to aid in the diagnostic process.     

Conversion of brain SPECT images between different collimators and reconstruction processes for analysis using statistical parametric mapping

To make it possible to share a normal database in single photon emission computed tomography (SPECT) studies, we developed a new method for converting a SPECT image in one physical condition to that in another condition for data acquisition and reconstruction. A Hoffman 3-dimensional brain phantom experiment was conducted to determine systematic differences between collimators and reconstruction processes. SPECT images for the brain phantom were obtained using fan-beam collimators with scatter and attenuation corrections and using parallel-hole collimators without any correction. Dividing these two phantom images after anatomical standardization by Statistical Parametric Mapping 99 (SPM99) created a 3-dimensional conversion map. This conversion map was applied to convert an anatomically standardized SPECT image using parallel-hole collimators without any correction to that using fan-beam collimators with scatter and attenuation corrections in eleven subjects who underwent sequential SPECT measurements using different collimators after injection of 99mTc ethyl cysteinate dimer. The SPM99 demonstrated adequate validity of this conversion in comparative analyses of these sequential SPECT images with different collimators. This may be a promising approach for further sharing of a normal database in SPECT imaging between different cameras.     

Reproducibility of a standardized quantitative analysis using fixed regions of interest to differentiate movement disorders on 123I-FP-CIT SPECT

The present prospective study evaluated the diagnostic value of a standardized analysis of (123)I-N-omega-(fluoropropyl)-2beta-carbomethoxy-3beta-(4-iodophenyl)tropane (FP-CIT) SPECT studies acquired on a triple-head gamma-camera for patients with clinically uncertain movement disorders having tremor as the most striking feature. METHODS: (123)I-FP-CIT studies were performed on 52 consecutive patients (27 male and 25 female; mean age, 49.2 y; range, 17-80 y) who had a clinical diagnosis of Parkinson's disease (PD) (n = 21), hypokinetic rigid syndrome (n = 19), dystonia (n = 8), or essential tremor (n = 4). In all patients, the final diagnosis was based on a thorough clinical examination, the family history, and a 2-y follow-up. Two independent technologists analyzed (123)I-FP-CIT studies using a standardized quantitative method applying both fixed regions of interest (ROIs) and manually drawn ROIs. The mean values from both methods were compared using the Student t test, and the intra- and intertechnologist variabilities were tested. RESULTS: In patients with PD, all ratios were significantly lower (P < 0.001) than those in patients with other movement disorders. No significant differences were found between the other groups tested. The manual method resulted in significantly lower values than did the standardized method (P < 0.001) and, for the putamen, showed significant differences between technologists. The standardized method showed no significant differences between technologists. The intra- and intertechnologist variabilities for this method were 0.14 +/- 0.13 (confidence value, 2.4%) and 0.19 +/- 0.18 (confidence value, 3.1%), respectively, whereas the intraclass correlation coefficients were 0.99 for 1 technologist and 0.98 for the 2 independent technologists. CONCLUSION: Our data confirm that (123)I-FP-CIT SPECT has value in the differentiation of PD from other movement disorders. Acquisition using a triple-head gamma-camera and subsequent standardized analysis using fixed ROIs result in good intra- and intertechnologist agreement and can easily be applied in clinical practice.     

Application of MRI-based partial-volume correction to the analysis of PET images of mu-opioid receptors using statistical parametric mapping.

The accurate quantification of brain radioactivity concentration is limited by the spatial resolution of the PET scanner for structures smaller than 2-3 times the resolution. In the presence of enlarged cerebrospinal fluid spaces or regions of cortical neuronal loss, a significant underestimation of gray-matter radioactivity concentration due to the resulting partial-volume averaging can potentially occur. To recover the true radioactivity concentration from PET data, algorithms that use the high-resolution anatomic information provided by MRI have been developed. Their effect on PET quantification has been assessed using regions of interest and non-operator-dependent voxel-based analyses such as statistical parametric mapping (SPM), although the mechanisms that lead to an improvement in PET quantification after partial-volume correction (PVC), compared with no PVC, have not been addressed. METHODS: We studied the influence of our previously described MRI-based PVC algorithm on SPM analysis of age effects on mu-opioid receptor (mu -OR) binding using (11)C-carfentanil PET in 14 healthy subjects (age range, 29-74 y). RESULTS: Mu-OR binding increased with age at a rate of about 0.9% per year in the left temporal cortex after PVC, consistent with the results obtained from human autoradiographic studies. Without PVC, no significant relationship with age was observed. PVC decreased mainly the residual variability of voxel mu-OR binding values around the age regression line. CONCLUSION: MRI-based PVC improves the sensitivity and accuracy of voxel-based statistical analysis of PET data.     

图像重建条件对PET脑显像SPM分析结果的影响

目的 探讨不同图像重建条件对^18F—FDG PET脑显像统计参数图（SPM）处理结果的影响。方法对6名健康受试者分别实施真、假针刺条件下的^18F-FDG PET脑显像。分别用4种重建条件进行图像重建。对每一重建结果均用SPM软件进行对齐、归一化及平滑处理，并进行配对t检验。结果 （1）SPM校正多重比较（P校正〈0．05）的统计学处理示，4种条件的重建结果中无一像素超阈值激活；（2）SPM未校正多重比较（P未校正〈0．001）的统计学处理示，4种重建条件的SPM结果不一致。2种重建算法（滤波反投影法和有序子集最大期望值迭代法）间差异最明显，不仅激活的像素总数及区域个数有差异，激活区的空间位置也大多不一致。结论 PET图像重建条件对SPM未校正多重比较的统计学处理结果有影响，下结论要慎重。     

Postsurgical cerebral perfusion changes in idiopathic normal pressure hydrocephalus: a statistical parametric mapping study of SPECT images.

Our goal was to study cerebral blood flow (CBF) changes after surgery in a group of 15 patients with idiopathic normal pressure hydrocephalus (NPH). METHODS: We used hexamethylpropyleneamine oxime SPECT and statistical parametric mapping (SPM), an image analysis method that does not require prior selection of regions of interest. RESULTS: Our study showed areas of significant increase in perfusion in specific regions of both frontal lobes and the right parietal lobe. Regions of increased perfusion were found in the left prefrontal dorsolateral areas (Brodmann's areas 9 and 45 or 47), right frontal premotor area (Brodmann's area 44), right medial prefrontal region (Brodmann's area 10 or 32), right frontal white matter area (superior longitudinalis fasciculus), and right basal ganglia (lenticular nucleus, putamen, and globus pallidus). In the right hemisphere, another region of increased perfusion was found in the inferior parietal lobule (Brodmann's area 40). The 2 areas most related to clinical improvement were Brodmann's area 32 and the frontal part of the left lobule of Reil insula. CONCLUSION: The results obtained with the SPM method of image analysis confirm and expand on previous CBF literature in NPH, with specific CBF regions located in frontal and parietal areas that improve after surgery in idiopathic NPH.     

SPECT image analysis using statistical parametric mapping in patients with Parkinson's disease.

This study investigated alterations in regional cerebral blood flow (rCBF) in patients with Parkinson's disease using statistical parametric mapping (SPM). METHODS: Noninvasive rCBF measurements using 99mTc-ethyl cysteinate dimer (ECD) SPECT were performed on 28 patients with Parkinson's disease and 48 age-matched healthy volunteers. The Parkinson's disease patients were divided into two groups, 16 patients with Hoehn and Yahr stage I or II and 12 patients with Hoehn and Yahr stage III or IV. We used the raw data (absolute rCBF parametric maps) and the adjusted rCBF images in relative flow distribution (normalization of global CBF for each subject to 50 mL/100 g/min with proportional scaling) to compare these groups with SPM. RESULTS: In patients with stage I or II Parkinson's disease, we found a diffuse decrease in absolute rCBF in the whole brain with sparing of the central gray matter, hippocampus and right lower temporal lobe compared with healthy volunteers. Adjusted rCBF increased in both putamina and the right hippocampus. In patients with stage III or IV disease, rCBF decreased throughout the whole brain. Adjusted rCBF increased bilaterally in the putamina, globi pallidi, hippocampi and cerebellar hemispheres (dentate nuclei) and in the left ventrolateral thalamus, right insula and right inferior temporal gyrus. CONCLUSION: SPM analysis showed that significant rCBF changes in Parkinson's disease accompanied disease progression and related to disease pathophysiology in the functional architecture of thalamocortex-basal ganglia circuits and related systems.     

SPECT imaging in head injury interpreted with statistical parametric mapping.

This study investigated regional cerebral blood flow in head-injured patients using statistical parametric mapping (SPM) to detect hypoperfusion on (99m)Tc-hexamethylpropyleneamine oxime (HMPAO) SPECT scans. METHODS: Acute and follow-up SPECT and MRI scans from 61 patients who were admitted to a regional neurosurgical unit were examined. Patients had acute MRI and SPECT at 2-18 d after injury and on follow-up between 130 and 366 d after injury. Thirty-two scans from non-head-injured patients were used as a SPECT control group. The SPECT images were first aligned to the Talairach-Tournoux atlas and then analyzed statistically with SPM. RESULTS: SPECT detected more extensive abnormality than MRI in acute and follow-up stages. This effect was more pronounced on follow-up of patients with diffuse injury. Examination of a focal injury group indicated the involvement of frontal and temporal lobes and the anterior cingulate. Blood flow abnormalities persist, to a lesser extent, on follow-up scans. The diffuse group displayed low blood flow in the frontal and temporal lobes, including cingulate involvement, which persists at follow-up with additional involvement of the thalamus. CONCLUSION: SPM has a role in SPECT image interpretation because it allows better visualization than other methods of quantitative analysis of the spatial distribution of abnormalities in focal and diffuse head injury. Frontal lobe blood flow abnormality (particularly anterofrontal regions and mesiofrontal areas) is common after head injury.     

Subcortical aphasia after striatocapsular infarction: quantitative analysis of brain perfusion SPECT using statistical parametric mapping and a statistical probabilistic anatomic map.

This study examined the relationship between the severity of aphasia and regional cerebral perfusion on brain SPECT using statistical parametric mapping (SPM) and a statistical probabilistic anatomic map (SPAM) in patients with a striatocapsular infarction (SCI) along with the other clinical and imaging findings. METHODS: The subjects were 16 right-handed Korean-speaking patients with a left SCI who underwent 99mTc-ethylcyteinate dimer (99mTc-ECD) SPECT (8.1 +/- 4.8 d [mean +/- SD] after onset). MRI showed that no patient had any abnormality in the cerebral cortex (6.8 +/- 6.0 d after onset). The aphasia quotient (AQ), which is a measure of the severity of aphasia, was obtained by using the Korean version of the Western Aphasia Battery (5.3 +/- 3.9 d after onset). For quantitative evaluation of cerebral perfusion, the asymmetry indices (AIs) for subcortical and cortical areas were calculated using SPM and SPAM. The infarct size was measured using MRI. RESULTS: Aphasia occurred in 15 (2 global, 7 transcortical, and 6 anomic aphasia) of the 16 patients. Left cerebral cortical hypoperfusion was observed in all 15 patients with subcortical aphasia. Aphasia was more severe in 6 patients with extensive cerebral cortical hypoperfusion than in the remaining 10 patients (AQ = 41.8 +/- 25.2 points vs. 84.2 +/- 7.7 points [mean +/- SD], P = 0.001). There was an association between the AQ and age (rho = -0.665), infarct size (rho = -0.594), AIs of the frontal cortex (rho = -0.653), temporal cortex (rho = -0.782), parietal cortex (rho = -0.694), whole cerebral cortex (rho = -0.768), and the cerebellar cortex (rho = 0.765). Voxel-based SPM analysis showed a significant positive correlation between the AQ and the perfusion of the left temporal cortex and the right cerebellum. CONCLUSION: The severity of subcortical aphasia after a left SCI without cortical abnormalities on MRI is associated with the extent and severity of the left cerebral cortical hypoperfusion on brain perfusion SPECT performed during the subacute stage, particularly in the left temporal cortex. Quantitative brain perfusion SPECT using SPM and SPAM can help in evaluating subcortical aphasia in a SCI because it provides functional information that cannot be obtained by morphologic imaging.     

Creation and validation of an I-123 FP-CIT template for statistical image analysis using high-resolution SPECT for parkinsonian patients

Objective

The aim of this study was to create a new template for the anatomical normalization of I-123 FP-CIT SPECT images of Japanese people to evaluate dopamine transporter binding.

Methods

The subjects consisted of 16 normal control subjects (5 females and 11 males; mean age ± SD, 51.6 ± 9.5 years, ranging from 25 to 62 years) and 21 parkinsonian patients (7 females and 14 males; mean age ± SD, 70.7 ± 9.4 years, ranging from 49 to 85 years). All normal control subjects and 21 patients with parkinsonism underwent MRI. A total of 148 MBq of I-123 FP-CIT was intravenously injected as a bolus, and a SPECT scan was started 4 h later. Data were analyzed with the Statistical Parametric Mapping 8 (SPM8) software. At first, I-123 FP-CIT SPECT images were co-registered to MRI images and MRI images were normalized to Montreal Neurological Institute (MNI) space using a gray.nii template. Co-registered I-123 FP-CIT SPECT images were normalized using the predetermined normalization parameters for MRI images. Then, anatomically normalized I-123 FP-CIT SPECT images were divided by background counts individually measured using ROIs set on the cerebral cortices. The I-123 FP-CIT template was created by averaging the normalized SPECT images of the 16 normal control subjects. Thereafter, the averaged MRI images of the 16 normal control subjects were also created.

Results

A visual inspection revealed that there were no apparent differences between the I-123 FP-CIT images subjected to the two methods of anatomical normalization in normal control subjects. However, a group comparison by a paired t test using SPM8 revealed that the I-123 FP-CIT binding was significantly higher in the substriatal and temporal regions in I-123 FP-CIT images directly normalized with the I-123 FP-CIT template than in those normalized by the predetermined parameters with MRI, while it was higher in the bilateral frontal cortical regions in the latter than in the former images.

Conclusion

We successfully created an I-123 FP-CIT template for Japanese people. This template is thought to be useful and reliable for the statistical analysis of I-123 FP-CIT images, although some problems exist in the evaluation of parkinsonian patients. The results of a paired t test using SPM suggest that we should use the same normalization method in statistical image analyses.

     

Calibration of gamma camera systems for a multicentre European 123I-FP-CIT SPECT normal database

Purpose

A joint initiative of the European Association of Nuclear Medicine (EANM) Neuroimaging Committee and EANM Research Ltd. aimed to generate a European database of [¹²³I]FP-CIT single photon emission computed tomography (SPECT) scans of healthy controls. This study describes the characterization and harmonization of the imaging equipment of the institutions involved.

Methods

¹²³I SPECT images of a striatal phantom filled with striatal to background ratios between 10:1 and 1:1 were acquired on all the gamma cameras with absolute ratios measured from aliquots. The images were reconstructed by a core lab using ordered subset expectation maximization (OSEM) without corrections (NC), with attenuation correction only (AC) and additional scatter and septal penetration correction (ACSC) using the triple energy window method. A quantitative parameter, the simulated specific binding ratio (sSBR), was measured using the ??Southampton?? methodology that accounts for the partial volume effect and compared against the actual values obtained from the aliquots. Camera-specific recovery coefficients were derived from linear regression and the error of the measurements was evaluated using the coefficient of variation (COV).

Results

The relationship between measured and actual sSBRs was linear across all systems. Variability was observed between different manufacturers and, to a lesser extent, between cameras of the same type. The NC and AC measurements were found to underestimate systematically the actual sSBRs, while the ACSC measurements resulted in recovery coefficients close to 100% for all cameras (AC range 69?C89%, ACSC range 87?C116%). The COV improved from 46% (NC) to 32% (AC) and to 14% (ACSC) (p?Conclusion A satisfactory linear response was observed across all cameras. Quantitative measurements depend upon the characteristics of the SPECT systems and their calibration is a necessary prerequisite for data pooling. Together with accounting for partial volume, the correction for scatter and septal penetration is essential for accurate quantification.     

统计参数图和ROI联合应用在多巴胺转运蛋白PET显像分析中的价值

目的 探讨联合应用统计参数图(SPM)和感兴趣区(ROI)方法在帕金森病(PD)患者多巴胺转运蛋白(DAT)PET图像分析中的价值.方法 临床确诊的41例PD患者,其中23例早期(Hoehn-Yahr Ⅰ～Ⅱ级),年龄(56.2±8.1)岁;18例晚期(Hoehn-Yahr Ⅲ～Ⅳ级),年龄(59.1±7.6)岁.健康对照组12名,年龄(58.84±7.2)岁.分别进行18F-N-(3-氟丙基)-2β-甲酯基-3β-(4'-碘苯基)去甲基托烷(FP-β-CIT)PET显像,对所获得的脑PET图像分别进行ROI及SPM分析.结果 应用ROI方法,与健康对照组相比,在23例早期PD患者中,尾状核、前壳核和后壳核的DAT分别减少29.1%、53.2%和76.0%;18例晚期PD患者的尾状核、前壳核和后壳核的DAT分别减少48.0%、65.5%和83.5%.SPM分析可直观显示,早期和晚期PD双侧壳核DAT较健康对照组减少,尤其是患肢的对侧壳核和后壳核区域.结论 PD患者纹状体内18F-FP-CIT的摄取显著降低,尤以患肢的对侧壳核最为明显;联合应用SPM和ROI方法有助于DAT PET图像的综合分析.     

Spatial normalization of spine MR images for statistical correlation of lesions with clinical symptoms

An image analysis method was developed for spatial normalization of spine magnetic resonance images. A deformable shape model of the spine is first constructed, and it is subsequently used by an automated algorithm to find a shape transformation that places patient data into a stereotactic space. Very good agreement with manual segmentations was observed. The main application of this method is in lesion-deficit analysis for determining associations between structural damage and clinical symptoms.     

AD型与非AD型变性痴呆大脑葡萄糖代谢的SPM分析

目的 探讨阿尔茨海默病(AD)型与非AD型变性痴呆患者的大脑葡萄糖代谢特征.方法 对23例AD患者、24例非AD型变性痴呆[包括9例帕金森病痴呆(PDD)、7例额颞痴呆(FTD)及8例路易体痴呆(DLB)]患者及40名健康对照者进行静息状态下的18F-脱氧葡萄糖(FDG)PET脑显像.结果 采用统计参数图(SPM)法进行基于体素水平分析.结果 (1)AD组:AD患者大脑葡萄糖代谢较对照组减低的脑区包括双侧颞-顶联合皮质区、额叶、楔前叶及后扣带回等部位.(2)非AD型变性痴呆组:FTD组大脑葡萄糖代谢较对照组减低的脑区包括双侧额叶、顶叶、岛叶、扣带回及左侧楔前叶、右侧皮质下结构等部位,以双侧额叶及皮质下结构为著;PDD组大脑葡萄糖代谢较对照组减低的脑区包括双侧额叶、颞-顶联合皮质区及皮质下结构,如基底节、丘脑等部位;DLB组大脑葡萄糖代谢较对照组减低的脑区包括双侧枕叶、楔前叶、额叶、顶叶及左侧前扣带回、右侧颞叶及皮质下结构如基底节、丘脑等部位,以双侧颞-顶-枕叶联合皮质区为著.结论 AD型与非AD型变性痴呆的大脑葡萄糖代谢特征不同,18F-FDG PET脑显像可为临床诊断及鉴别诊断神经变性痴呆提供依据.