Brain SPECT imaging of neuropsychiatric disorders

Brain imaging has become an integral part of the evaluation of neurological and psychiatric disorders. Functional imaging techniques, SPECT and PET, together with structural modalities, CT and MRI, are widely employed. Functional imaging studies are routinely used in the diagnostic workup of patients with well-characterized neurological disorders, such as epilepsy and brain tumors, and have a growing role in research on psychiatric disorders without known mechanisms such as depression and schizophrenia. Furthermore, many well-defined neurological disorders manifest prominent psychiatric symptomatology which may pose difficulties in differential diagnosis. This review addresses the current knowledge of SPECT findings in patients who present with psychiatric phenomena, associated with disorders at the interface of neurology and psychiatry.     

Diffusion tensor imaging in normal aging and neuropsychiatric disorders

The application of diffusion imaging to the quantitative study of the effects of normal aging and neuropsychiatric diseases on brain tissue microstructure has witnessed its greatest development just over the last few years. Measures derived from diffusion imaging have already been shown to have great utility in identifying age- and disease-related degradation of regional microstructure, particularly of white matter. Investigations comparing diagnoses hold promise for contribution to differential diagnosis. Correlations with cognitive and motor performance provide evidence for functional ramifications of these diffusion measures.     

Applications of SPECT imaging of dopaminergic neurotransmission in neuropsychiatric disorders

Single photon emission computed tomography (SPECT) tracers selective for pre- and post-synaptic targets have allowed measurements of several aspects of dopaminergic (DA) neurotransmission. In this article, we will first review our DA transporter imaging in Parkinson's disease. We have developed the in vivo dopamine transporter (DAT) imaging with [123I]beta-CIT ((1R)-2beta-Carbomethoxy-3beta-(4-iodophenyl)tropane). This method showed that patients with Parkinson's disease have markedly reduced DAT levels in striatum, which correlated with disease severity and disease progression. Second, we applied DA imaging techniques in patients with schizophrenia. Using amphetamine as a releaser of DA, we observed the enhanced DA release, which was measured by imaging D2 receptors with [123I]IBZM (iodobenzamide), in schizophrenics. Further we developed the measurement of basal synaptic DA levels by AMPT (alpha-methyl-paratyrosine)-induced unmasking of D2 receptors. Finally, we expanded our techniques to the measurement of extrastriatal DA receptors using [123I]epidepride. The findings suggest that SPECT is a useful technique to measure DA transmission in human brain and may further our understanding of the pathophysiology of neuropsychiatric disorders.     

学龄期癫(癎)患儿SPECT局部脑血流显像和认知功能的关系

目的探讨学龄期癫癎患儿 SPECT 局部脑血流(rCBF)显像的特征和认知功能状况及其关系。方法对32例学龄期原发性强直和(或)阵挛发作(GTCS)癫癎患儿进行 SPECT 脑显像及认知功能测试,两者进行相关性分析,并与12例正常儿童进行认知功能比较.结果①32例学龄期原发性癫癎患儿 SPECT 脑显像30例异常,定位率为93.8%,其中29例50个部位 rCBF 减少,rCBF 降低百分比为(21.07±7.09)%;1例2个部位 rCBF 增高,rCBF 增高百分比为(32.22±4.31)%,有92.3%的病灶集中在额、颞、顶、枕叶。②学龄期癫癎患儿言语智商(VIQ)、操作智商(PIQ)和总智商(FIQ)明显低于正常儿童,并存在一定的认知偏异,具有 VIQ>PIQ 倾向:③SPECT 脑显像检出癫癎患儿的病灶个数与认知测试 VIQ、PIQ 和 FIQ 呈负相关,相关系数分别为-0.543(P=0.002)、-0.469(P=0.009)、-0.578(P=.001);病灶范围与 VIQ、PIQ 和 FIQ 呈负相关,相关系数分别为-0.560(P=0.003)、-0.142(P=0.016)、-0.582(P=0.001);病灶区 rCBF 降低和增高百分比与认知测试各智商相关性不显著。结论 SPECT rCBF 显像对儿童原发性癫癎有较高的定位诊断价值;学龄期癫癎患儿存在不同程度的认知障碍,其认知功能减低与病灶的个数和范围呈负相关。     

Neuropharmacological studies with SPECT in neuropsychiatric disorders

The last decade saw a rapid development of single photon emission computed tomography (SPECT) from a tool to assess cerebral blood flow to the study of specific neurotransmitter systems. Because of the relatively long half-life of SPECT radioisotopes, it is practical to measure the availability of neuroreceptors and transporters in conditions approaching equilibrium. The cost-efficiency of SPECT allowed studies in relatively large samples of patients with various neuropsychiatric disorders. We have applied this approach in studies of dopaminergic, serotonergic, and muscarinergic neurotransmission in patients with dementia, extrapyramidal disorders, schizophrenia, and alcoholism. No simple associations were observed between a single defect in one neurotransmitter system and a certain neuropsychiatric disease. Instead, complex dysfunction of several neurotransmitter systems in multiple, partially connected brain circuits have been implicated. Treatment effects also have been characterized. Microdialysis and neurotransmitter depletion studies showed that most radioligands and endogenous neurotransmitters compete for binding at receptors and transporters. Future research directions include the assessment of endogenous neurotransmitter concentrations measured by depletion studies and of genetic effects on neuroreceptor and transporter expression.     

γ-氨基丁酸A型-苯二氮革受体显像剂在神经系统疾病中的应用

γ-氨基丁酸A型-苯二氮革(GABAA-BZ)受体广泛分布于中枢神经系统,是嵌于神经细胞膜上的异质性多肽五聚体,不同的亚单位组合发挥不同的神经抑制性药理作用,如镇静催眠、抗惊厥、抗焦虑等.PET可用于活体内受体结合的研究.GABAA-BZ受体PET显像剂分为拮抗剂、激动剂、反向激动剂3类,其中以拮抗剂显像剂11C-氟马西尼最为成熟,在癫癎、焦虑症、抑郁症、植物状态、成瘾等神经精神疾病中广泛应用.     

FDG-PET imaging in duodenal cancer

F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) imaging is a useful modality in the detection of various tumors, including colon cancer and gastric cancer. We evaluated a patient with duodenal cancer with multiple metastases including brain metastases using FDG-PET imaging. It revealed multiple tumor uptake in the brain, clavicular fossa, mediastinum, right adrenal gland and duodenum. These results suggest that FDG-PET imaging may be useful in detecting the primary and metastatic lesions of duodenal adenocarcinoma.     

Positron emission tomography imaging of regional cerebral glucose metabolism

The (F-18) fluorodeoxyglucose (FDG) technique to measure local cerebral metabolic rate for glucose (LCMRglu) is well accepted and widely used by many institutions around the world. A large number of studies has been carried out in normal volunteers and patients with a variety of CNS disorders. Several investigators have noted that no significant age-related changes in cerebral glucose use occur with normal aging. Some important and interesting findings have been revealed following sensory, motor, visual, and auditory stimulations. Functional imaging with FDG in certain neurologic disorders has dramatically improved our understanding of their underlying pathophysiologic phenomena. Some abnormalities detected on the positron emission tomography (PET) images have no corresponding changes on either x-ray computed tomograms (XCT) or magnetic resonance images (MRI). In patients with Alzheimer's disease, primary sensorimotor, visual, and cerebellar metabolic activity appears relatively preserved. In contrast, parietal, temporal, and to some degree, frontal glucose metabolism is significantly diminished even in the early stages of the disease. Patients with Huntington's disease and those at risk of developing this disorder have a typical pattern of diminished CMRglu in the caudate nuclei and putamen. In patients with stroke, PET images with FDG have demonstrated abnormal findings earlier than either XCT or MRI and with a wider topographic distribution. FDG scans have revealed interictal zones of decreased LCMRglu in approximately 70% of patients with partial epilepsy. The location of the area of hypometabolism corresponds to the site of the epileptic focus as determined by electroencephalography and microscopic examination of the resected tissue. Ictal scans during partial seizures demonstrate areas of hypermetabolism corresponding to the sites of seizure onset and spread. Several investigators have reported relative hypofrontal CMRglu in patients with schizophrenia. In our center, FDG scans from patients with schizophrenia were successfully differentiated from those obtained in normal controls. Finally, our preliminary data (using PET, XCT, and MRI) in patients with CNS disorders indicate that MRI provides excellent delineation of the structural abnormalities. It may prove to be superior to XCT in the evaluation of certain diseases such as cerebral ischemia and infarcts, head injury, tumors, and white matter lesions. Metabolic imaging with FDG provides functional information not obtainable with either MRI or NMR spectroscopy. Therefore, PET studies will play a complementary role to the anatomic imaging in the management of patients with CNS disorders.     

5-羟色胺受体显像剂在神经系统疾病及脑功能研究中的应用

5-羟色胺(5-HT)受体广泛分布于中枢神经系统,参与精神与情绪、自主神经系统功能、睡眠与觉醒、内分泌活动等的调节,与疼痛、抑郁症、癫癎等诸多疾病存在广泛而直接的联系.随着5-HT受体核素显像剂的不断开发,利用SPECT、PET对中枢神经系统进行无创性的5-HT受体显像已经广泛开展,并为临床诊断和治疗上述疾病提供了独一...     

FDG-PET imaging in Pneumocystis carinii pneumonia

The authors present a case of a 26-year-old man, under investigation for Cushing syndrome, who presented acutely with a dry cough and fever. The blood tests were unremarkable apart from a moderate to severe leukopenia. Imaging tests were suggestive of an atypical pneumonia, which was proven to be Pneumocystis carinii pneumonia (PCP) on cytology examination of a bronchoalveolar lavage (BAL). The acute lung changes were demonstrated on a whole-body F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) study. After treatment, a follow-up study showed complete resolution of these changes. The authors suggest that FDG PET may have a role to play in the diagnosis and, in particular, the monitoring of PCP in immunocompromised patients.     

SPECT局部脑血流显像在皮质下梗死伴半侧空间忽略患者的应用

目的　探讨皮质下梗死所致半侧空间忽略与脑血流改变部位、范围及程度间的关系。方法　对 30例临床确诊为单侧皮质下梗死的右利手患者行SPECT局部脑血流 (rCBF)显像 ,判定rCBF改变的部位、范围及程度。结果　经忽略组合试验证实有半侧空间忽略表现的 2 1例皮质下梗死患者 ,SPECT显像示rCBF降低部位多累及大脑皮质功能区 (χ2 =7 91,P <0 0 0 5 )。最多见于额叶 ,其次是顶叶、颞叶和枕叶。最明显的部位是颞顶枕交界处。病灶区rCBF及rCBF降低百分比与忽略评分的r分别为 - 0 4 4和 0 31。病灶的范围、数量与忽略程度间呈显著正相关 (r分别为 0 74和 0 72 )。结论皮层下梗死所致忽略多累及皮质功能区。多部位联合损伤易出现忽略且程度更严重。     

Whole-body FDG-PET imaging in the management of patients with cancer

Fluorodeoxyglucose-positron emission tomography (FDG-PET) imaging is increasingly used for the management of patients with cancer. The technique is now well accepted by most physicians as an effective complement to the existing imaging modalities. For many malignancies, PET achieves high sensitivity and specificity. The critical role of this powerful technique is realized increasingly in the day-to-day practice of oncology. This is particularly true for the management of patients with non-small-cell lung cancer (NSCLC). The contribution of PET for the selection of patients eligible for curative treatments in this setting is well established. Convincing data also exist to support the use of PET for evaluating patients with recurrent colorectal carcinoma, for staging and restaging lymphomas, and for diagnosing recurrent thyroid carcinoma in the presence of elevated thyroglobulin and negative 131I scans. Other indications include staging of various recurrent malignancies, such as breast cancer, melanoma, and head and neck and gynecologic carcinomas. Existing data are limited for the determination of the impact of PET in certain malignancies, and further studies, which should include outcome information, will allow clarification of the role of this modality for such indications. Despite the small number of studies specifically designed to assess changes in management plans for some malignancies after performing PET the overall favorable results are encouraging enough at this time to include this modality as an essential element of the practice of modern oncology. Finally, the evolving role of PET imaging as a predictor of response after local or systemic treatment may add a major dimension to the application of this novel technique.     

Parametric imaging of regional cerebral blood flow with the short-lived isotope 195mAu

The use of the short-lived (30 s) isotope ^195mAu in brain perfusion studies has been tested on 40 patients and 8 volunteers. The activity of the eluate from the ^195mHg/¹⁹⁵Au generator was high enough to give good image statistics of brain perfusion after a single bolus injection. The examinations can be repeated after 3 min giving the same quality and without significant background. The use of a low-energy photon peak at 68 keV (Au–K) allows the imaging of brain perfusion in both lateral views with almost no look-through effect. With a modified height-over-area formula for the calculation of regional cerebral blood flow parametric images were obtained of high diagnostic value. The sensitivity and reproducibility, of the method has been demonstrated by mental stimulation tests on eight volunteers: after optical stimulation a clear increase of blood flow could be shown in the visual cortex.     

Automatic calculation of the arterial input function for cerebral perfusion imaging with MR imaging

An automated method for determination of arterial input function (AIF) for rapid determination of cerebral perfusion with dynamic susceptibility contrast magnetic resonance (MR) imaging was derived. In 100 patients, the automated method was used to create images of relative blood flow, relative cerebral blood volume, and mean transit time. In 20 patients, the voxel chosen with the automated AIF correlated with a large cerebral artery and exhibited less partial-volume averaging when compared with an AIF chosen manually. It is possible to reliably determine the AIF at dynamic susceptibility contrast MR imaging and eliminate the need for operator input and lengthy postprocessing.     

半侧空间忽略SPECT rCBF显像研究

目的　探讨半侧空间忽略的发生及程度与脑血流改变的部位、范围及程度间的关系。方法　对临床确诊为单侧脑卒中、忽略组合试验证实有忽略表现的右利手患者行SPECT局部脑血流(rCBF)显像 ,判定rCBF改变的部位、范围及程度。结果　SPECT显像示忽略患者的脑损伤部位最多见于额叶 ,其次是顶叶、枕叶、颞叶、基底节和丘脑。 2个或 2个以上部位的联合损伤更易出现忽略 ,最明显的部位是颞顶枕交界处。病灶区的rCBF及rCBF降低的百分比与忽略程度的相关系数为 - 0 34 (t=- 1.5 ,P >0 .0 5 )和 0 .34 (t=1.47,P >0 .0 5 ) ,病灶的范围、病灶数及病灶缺血体积与忽略程度之间的相关系数分别为 0 .71(t=4.13,P <0 .0 1)、0 .70 (t=4.0 7,P <0 .0 1)和 0 .6 4(t=3.40 ,P <0 .0 1)。结论　忽略患者病灶区的rCBF及rCBF降低的百分比与忽略程度的相关性较小 ,而病灶的范围、病灶数及缺血体积与忽略程度呈正相关。半侧空间忽略可发生于多个大脑部位的损伤 ,多部位联合损伤忽略程度更明显。     

State-of-the-Art FDG-PET imaging of lung cancer

The D-glucose analog 2-(fluorine-18)-fluoro-2-deoxy-D-glucose (FDG) is the most commonly used radionuclide in positron emission tomography (PET) of lung cancer. FDG-PET is a molecular imaging technique that images the preferential accumulation of FDG in malignant tissues with increased metabolism. Although FDG-PET is sensitive in the detection of lung cancer, FDG is not tumor specific and may accumulate in a variety of nonmalignant conditions. Occasional false-negative results may also occur. Whole body FDG-PET is a useful noninvasive technique to stage known or suspected non-small-cell lung cancer. The results allow more efficient use of invasive methods for histopathological staging. The combined use of CT and PET in dual imaging increases the number of patients with correctly staged non-small-cell lung cancer. CT/PET is also useful in the assessment of recurrent or residual disease. Future imaging agents are being developed which may allow more selective accumulation of radiopharmaceutical in malignant tissues.     

Real-time imaging of regional myocardial function using fast-SENC.

A technique for fast imaging of regional myocardial function using a spiral acquisition in combination with strain-encoded (SENC) magnetic resonance imaging (MRI) is presented in this paper. This technique, which is termed fast-SENC, enables scan durations as short as a single heartbeat. A reduced field of view (FOV) without foldover artifacts was achieved by localized SENC, which selectively excited the region around the heart. The two images required for SENC imaging (low- and high-tuning) were acquired in an interleaved fashion throughout the cardiac cycle to further shorten the scan time. Regional circumferential contraction and longitudinal shortening of both the left ventricle (LV) and right ventricle (RV) were examined in long- and short-axis views, respectively. The in vivo results obtained from five human subjects and five infarcted dogs are presented. The results of the fast-SENC technique in a single heartbeat acquisition were comparable to those obtained by conventional SENC in a long acquisition time. Therefore, fast-SENC may prove useful for imaging during stress or arrhythmia.