Contribution of single photon emission computed tomography to the differential diagnosis of dementia in a memory clinic

To evaluate the contribution of single photon emission computed tomography (SPECT) to the differential diagnosis of dementia, we studied 48 consecutive patients (median age: 63) with a degenerative or vascular dementia, a 99mTc-HMPAO SPECT imaging, and a diagnostic confirmation (autopsy or genetic mutation). The SPECT scans were visually rated by two nuclear medicine physicians (first blinded to the clinical data, then with the data). Comparisons between clinical diagnoses and/or SPECT imaging and neuropathology were performed. At the time of SPECT was performed, the clinical diagnosis of Alzheimer's disease (AD) sensitivity was 83%, specificity was 76%, and diagnostic accuracy was 79%. The blinded SPECT sensitivity was 57%, specificity 92%, and diagnostic accuracy 75%. The SPECT associated with clinical data sensitivity was 65%, specificity 84%, and accuracy 75%. The clinical diagnosis of frontotemporal-lobar degeneration (FTLD), progressive supranuclear palsy (PSP), and corticobasal degeneration syndrome (CBDs) sensitivity was 83%, specificity 87%, and accuracy 85%. The blinded SPECT sensitivity was 50%, specificity 97%, and accuracy 79%. The SPECT associated with clinical data sensitivity was 61%, specificity was 93%, and accuracy 81%. Whenever the blinded SPECT interpretation agreed with the clinical diagnosis of AD and FTLD/PSP/CBDs, the condition was confirmed by neuropathological assessment in all cases. Compared with clinical diagnosis alone, SPECT imaging improved the specificity of the etiological diagnosis in degenerative dementia, although its sensitivity was not as good as that of clinical diagnosis. For AD and FTLD/PSP/CBDs, agreement between the clinical and SPECT-based diagnoses was always confirmed by neuropathological assessment.     

Value of single photon emission computed tomography in the characterization of fronto-temporal dementia subtypes

DFT (fronto-temporal dementia) was diagnosed in 33 patients (17 males and 16 females), mean age 74.9 years, using the criteria from Neary et al. (1998). The severity of the disease was evaluated based on the presence or absence of 4 clinical groups of signs (behavioral, affective, neurological signs and language) allowing the calculation of a global clinical ratio on 20. A CT-scan and a Single Photon Emission Computed Tomography (SPECT) scan using Tc99m-ECD with quantification of brain perfusion were then performed. This study confirmed the classical clinical forms of DFT: a psycho-affective form (21%), where negative symptoms are predominant, and a behavioral disinhibited form (9%). Most of our cases (40%) corresponded to a global form. Finally we also identified a fourth clinical form: cognitive form because of predominance of language disturbances (30%). Concerning SPECT, we found 4 topographic forms: frontal global (46%), frontal superior (24%), frontal inferior (15%) and frontal unilateral (12%). In the frontal inferior form, behavioral disturbances were correlated to the intensity of frontal inferior hypoperfusion, corresponding to an orbito-frontal dysfunction. In the frontal superior form, psycho-affective disturbances (apathy) were correlated with frontal superior hypoperfusion (anterior cingulum and superior dorso-lateral cortex). Finally, in global and frontal inferior SPECT forms, language disturbances were correlated with a frontal inferior hypoperfusion (prefrontal and inferior left frontal cortex).     

Evaluation of dopaminergic function in frontotemporal dementia using I-FP-CIT single photon emission computed tomography

Extrapyramidal symptoms are observed in frontotemporal dementia (FTD). (123)I-FP-CIT (DaT scan) single photon emission computed tomography (SPECT) can detect loss of presynaptic dopamine transporters in the striatum. We aimed to evaluate the dopaminergic status of the striatum in patients with FTD using DaT scan. Seven patients (age range 65-76 years), who fulfilled the Neary criteria and in whom the diagnosis of FTD was confirmed by hexamethylpropyleneamine oxime SPECT, were included in the study. The severity of the extrapyramidal symptoms was evaluated by the motor part of the Unified Parkinson's Disease Rating Scale (UPDRS). SPECT using (123)I-FP-CIT was done. A (region - occipital)/occipital ratio was calculated for the striatum, putamen and caudate nucleus. The results were compared with those of the 7 age-matched normal controls. The uptake of the radiotracer in the right and left striatum was reduced to 62% (p = 0.000) and 68% (p = 0.000), respectively, compared to controls. The motor UPDRS score of the patients with FTD showed a negative correlation to the uptake of the radiotracer. The presynaptic dopamine transporter in FTD is impaired, related to the severity of the extrapyramidal symptoms. Since an effective treatment for FTD is still to be established, there is a need for evaluating the efficacy of dopaminergic drugs.     

Opsoclonus-myoclonus syndrome with abnormal single photon emission computed tomography imaging

The single photon emission computed tomography (SPECT) findings in 2 patients with opsoclonus-myoclonus syndrome (OMS) who had similar symptoms in the acute stage of the disease are described. In 1 patient with encephalitis, SPECT showed increased blood flow in most of the cerebellum; the highest accumulation of the radiotracer was found in the cerebellar vermis and neighboring structures. These changes disappeared with clinical improvement. In the other patient with chronic OMS, SPECT demonstrated hypoperfusion in most of the cerebellum. Our results suggest that the cerebellum, particularly its middle portion, is involved in the generation of OMS. SPECT is a useful method that enables us to detect in vivo functional impairment in patients with OMS.     

Dopamine transporter single photon emission computerized tomography in the diagnosis of dementia with Lewy bodies

Dementia with Lewy bodies (DLB) is part of the spectrum of Lewy body disorders. However, it may be difficult to diagnose patients who have dementia but no Parkinsonism. Visual and semiquantitative assessment of the nigrostriatal dopaminergic nerve terminals in the putamen and caudate nuclei can be obtained with single photon emission computerized tomography (SPECT) using ligands that bind to the dopamine transporter molecule in the membranes of the nigrostriatal nerve terminals. This can be employed as a means of identifying subclinical degeneration of nigrostriatal neurones in patients with suspected DLB, increasing the probability of the diagnosis. In several studies, the sensitivity and specificity of abnormal dopamine transporter scans with regard to diagnosing probable DLB are better than 75 and 90%, respectively. This communication outlines the evidence for this and discusses some of the advantages, potential disadvantages, and areas of uncertainty with regard to the use of dopamine transporter SPECT in DLB diagnosis. © 2009 Movement Disorder Society     

Localization of epileptic foci with postictal single photon emission computed tomography

Effective surgical treatment of patients with intractable complex partial seizures depends on accurate preoperative seizure focus localization. We evaluated seizure localization with interictal and immediate postictal single photon emission computed tomographic images of cerebral perfusion using technetium-99m-hexamethyl-propyleneamineoxime (99mTc-HMPAO) in comparison with conventional ictal electroencephalographic (EEG) localization. Thirty-two patients with intractable complex partial seizures were studied. The mean delay from seizure onset to injection was 6.3 +/- 5.3 (SD) minutes. Independent blinded observers assessed the scans for interictal hypoperfusion and postictal focal hyperperfusion. Interictal scans alone were unreliable, indicating the correct localization in 17 patients (53%) and an incorrect site in 3 (9%). When interictal and postictal scans were interpreted together, the focus was correctly localized in 23 patients (72%). There was 1 false-positive study, and 8 patients had inconclusive changes, including 2 with inconclusive depth EEG studies. Postictal hyperperfusion was predominantly mesial temporal and frequently associated with hypoperfusion of lateral temporal cortex. Secondarily generalized seizures tended to show focal hyperperfusion less often than complex partial seizures did (Fisher's exact test p = 0.09). Combined interictal and immediate postictal single photon emission computed tomography with 99mTc-HMPAO is a useful noninvasive technique for independent confirmation of electrographic seizure localization. It may provide a suitable alternative to the use of depth electrode studies for confirmation of surface EEG findings in many patients with complex partial seizures.     

脑血管性痴呆与帕金森病神经心理学测验和脑单光子发射计算机断层扫描的对照研究

目的　研究脑血管性痴呆（ Ｖ Ｄ） 与帕金森病（ Ｐ Ｄ） 在神经心理学测验及脑单光子发射计算机断层扫描（ Ｓ Ｐ Ｅ Ｃ Ｔ） 的诊断和鉴别诊断的意义。方法　对３０ 例 Ｖ Ｄ、３１ 例 Ｐ Ｄ 和３０ 名正常老年人（ Ｎ Ａ） 进行神经心理学测验和 Ｓ Ｐ Ｅ Ｃ Ｔ 检查并比较检测结果。结果　神经心理学各项总分 Ｖ Ｄ 组最低［ 除积木测验（ Ｂ Ｄ） 外］ , Ｐ Ｄ 组次之, Ｎ Ａ 组最高;３ 组间差异均有非常显著性（ Ｆ＝ １８６７ ～６３９５ , Ｐ＜００１） 。在 Ｓ Ｐ Ｅ Ｃ Ｔ的检查中, Ｖ Ｄ 除额叶、左丘脑和右枕叶外余各脑区血流灌注均低于 Ｎ Ａ 组（ Ｐ＜００５） , Ｐ Ｄ 则为顶叶、颞叶、基底节和丘脑血流灌注低于 Ｎ Ａ 组（ Ｐ＜ ００５） 。结论　 Ｖ Ｄ 和 Ｐ Ｄ 的神经心理学测验和脑 Ｓ Ｐ Ｅ Ｃ Ｔ各有其特点,这两项检查可作为诊断和鉴别诊断 Ｖ Ｄ 和 Ｐ Ｄ 的辅助手段。     

The current place of single photon emission computed tomography in epilepsy evaluations

Single photon emission computed tomography is appropriate for peri-ictal imaging inpatients with focal epilepsy being considered for surgical treatment.     

Acute limbic encephalitis with focal hyperperfusion on single photon emission computed tomography

Here we report an 11-year-old boy with acute encephalopathy with neuropsychiatric symptoms. The patient had mildly decreased consciousness, delirious behavior, and affective changes next day of fever onset. Hematologic, biochemical, and metabolic examinations were unremarkable. CSF analysis revealed cell counts of 278 cells/mm³ and a protein level of 87 mg/dL. Although MRI revealed no abnormal findings, an increase in regional cerebral blood flow was present in the bilateral frontal lobes, mesial temporal lobes, and basal ganglia on single photon emission computed tomography. The measurement of the concentrations of biomarkers such as cytokines in the patient’s serum and cerebrospinal fluid revealed elevated levels of IL-4 and TNF-α in the cerebrospinal fluid. Immunohistochemical studies applying control human brain sections did not demonstrate the presence of autoantibodies. We considered that innate immunity rather than autoantibody response may have contributed to the neuropsychiatric symptoms of our patient. These results suggest heterogeneity of patients with acute encephalopathy with neuropsychiatric symptoms.     

The role of brain single photon emission computed tomography in the diagnosis of primary progressive aphasia.

We present two cases of primary progressive aphasia studied with neuropsychologic measures, computed tomography or magnetic resonance imaging, and single-photon emission computed tomography with technetium Tc99m-labeled hexamethylpropyleneamine oxime. Clinical and neuropsychologic observations revealed a marked, progressive loss of language functions over time with relative preservation of nonlanguage cognitive functions in both patients. The brain single-photon emission computed tomographic scan revealed marked left frontal and minimal left temporal and parietal hypoperfusion in case 1 and marked left posterior frontal and minimal left temporal hypoperfusion in case 2. The value of brain single-photon emission computed tomography in distinguishing primary progressive aphasia from Alzheimer's disease is described.     

抑郁症患者的脑单光子发射计算机断层摄影研究

为观察抑郁症患者局部脑血流（ｒＣＢＦ）情况，对１１例处于症状发作期的抑郁症患者及１３名正常对照者用９９ｍＴｃ标记的亚锡双半胱乙脂进行脑单光子发射电子计算机断层摄影（ＳＰＥＣＴ）。结果显示，观察组与对照组比较，左下额、左前颞及扣带皮质的ｒＣＢＦ显著下降（Ｐ＜０．０１），而右上额、右下额和两侧顶叶、枕叶的ｒＣＢＦ也有下降（Ｐ＜０．０５）。观察组尚存在上额皮质ｒＣＢＦ两侧非对称性（Ｐ＜０．０５），而对照组未见相应的非对称性。提示抑郁症发作时存在某些脑功能区ｒＣＢＦ下降以及两侧脑功能区局部的ｒＣＢＦ不对称性。     

Single photon emission tomography in dementia

Single photon emission tomography (SPET) is a technique which allows simple non-invasive measures of cerebral blood flow and indirectlymetabolism. It has considerablepotential as a tool for the differential diagnosis ofdementia. A review is presented tracing the development and current applications of the technique and the practical implications of its use.     

The EEG evaluation of single photon emission computed tomography abnormalities in epilepsy.

Single photon emission computed tomography (SPECT) has increasingly been used as a diagnostic procedure for localizing epileptic seizure foci and as a research tool for investigating the physiologic mechanisms underlying seizure activity. With increasing use of SPECT in localizing the seizure focus for epilepsy surgery, there arises a need to critically assess its current role in the evaluation of patients for epilepsy surgery, especially as it relates to other clinical and laboratory data used in presurgical evaluation. Ictal EEG discharge has traditionally been used as the "gold standard" against which SPECT studies are compared in assessing the latter's localizing value. However, this practice presents a major challenge because SPECT studies are often reserved for patients with nonlocalizing EEG or magnetic resonance imaging findings. Nonetheless, SPECT studies in evaluation for epilepsy surgery should always be performed with the knowledge of the patient's EEG activity preceding, during, and after the injection of the radiotracer. The advent of techniques such as subtraction SPECT with co-registration on magnetic resonance imaging (SISCOM) and computer image-guided surgery has great potential in enhancing the clinical electrophysiologic evaluation of SPECT-detected abnormalities in epilepsy. These techniques permit accurate spatial correlation between intracranial EEG activity and SPECT perfusion patterns. The techniques can also be used to evaluate the effect of the extent of EEG focus resection compared with that of SISCOM focus resection to determine which has more prognostic importance in postsurgical control of seizures. Both animal and human studies are warranted to advance our knowledge of the electrophysiology associated with the various SPECT perfusion patterns.     

Regional cerebral blood flow study with 99mTc-hexamethyl-propyleneamine oxime single photon emission computed tomography in Alzheimer's and multi-infarct dementia

Thirty-four demented patients, 19 with Alzheimer's and 15 with multi-infarct dementia, were studied using single photon emission computed tomography, and 99mTc-hexamethyl-propylenemine oxime as a tracer of regional cerebral perfusion. Tracer activity ratios, determined in cortical and subcortical regions, were compared with those of 11 age-matched controls. In both groups of demented patients, most of the cortical regions showed significant declines in tracer uptake from control values, with the greatest reductions in the parietal cortex. Significantly lower parietal indexes were found in the Alzheimer's patient group as compared both to the control values and to the group of multi-infarct dementia patients. A positive correlation was found between the magnitude of the parietal deficits and the severity of dementia.     

Early single photon emission computed tomography in Sturge-Weber syndrome

OBJECTIVES—Functional cerebral imaging PET and SPECT have shown hypometabolism and hypoperfusion in the area of vascular malformation in children with epilepsy due to Sturge-Weber syndrome. However, data are scarce in infants and do not exist in patients with Sturge-Weber disease without epilepsy. The pattern of perfusion during the first two years of life was studied including patients before the onset of seizures.
METHODS—Twenty two infants with later confirmed Sturge-Weber disease underwent SPECT examination using TOMOMATIC 564 (Medimatic) and xenon-133 at ages ranging from 8 days to 25 months. Twelve had never had seizures before SPECT and seven underwent a second SPECT a mean seven months later. Cerebral blood flow (CBF) was measured in the whole hemisphere and in the part of the cortex involved in the vascular malformation on both sides as well as a ″pathological to normal″ index for the hemisphere and vascular malformation. These values were compared with normal age paired values.
RESULTS—Compared with controls, CBF and the indices in the hemisphere and vascular malformation were significantly decreased in patients who already had had seizures before SPECT, whereas they were significantly increased in 75% of the patients who had never had any seizures. On second SPECT, the indices were decreased in all patients, including the four who still remained non-epileptic.
CONCLUSIONS—SPECT therefore detects CBF asymmetry in infants with Sturge-Weber disease, which tends to shift with age. The cortex involved in the vascular malformation is hyperperfused during the first year of life before first seizures. The classic hypoperfusion appears after one year of age, even in non-epileptic patients.

     

Brain single photon emission computed tomography (SPECT) in neuropediatrics

The clinical value in neuropediatrics of [99mTc]HM-PAO brain single photon emission computed tomography was preliminary evaluated by the consecutive investigation of 79 children. Planned epilepsy surgery was the most common indication for the investigation. In 56 children investigated because of epilepsy, SPECT yielded relevant information in 79% of cases examined. The corresponding figures for magnetic resonance imaging and CT were 49% of 35 and 36% of 56 cases, respectively. All 22 children with an epileptic focus, ascertained by freedom from seizures after removal of the area or by consistent neurophysiological and neuroradiological findings, also had abnormal perfusion in the relevant area. Twenty-three children were examined because of neurological signs and symptoms other than epilepsy. SPECT findings were useful for elucidating neonatal brain impairments. Hypoperfused areas in the brain of asphyxiated infants and in posthemorrhagic hydrocephalus corresponded to neuroradiological and autopsy findings. SPECT was found to be an excellent tool when analysing cerebrovascular accidents. In cases with signs and symptoms of a diffuse severe encephalopathy, SPECT did not clarify the etiology but provided information on the distribution of the lesions and probable underlying pathophysiological mechanisms.     

Nuclear magnetic resonance imaging and single photon emission tomography with radio-iodine labelled compounds in the diagnosis of dementia

White matter lesions and T1 changes were identified using NMR and then compared between groups of patients suffering from dementia of the Alzheimer type (DAT), Multiple infarct dementia (MID) and normal controls. All DAT and MID patients were also imaged with a gamma camera using 123Iodo-n-isopropyl-amphetamine, a radiopharmaceutical whose uptake in the brain follows the regional blood flow. While NMR was not able to differentiate between DAT and MID, 19 out of 21 DAT patients compared to four out of 18 MID patients showed bilateral parietal lesions on IMP scans.     

Predicting the accuracy of a diagnosis of Alzheimer's disease with 99mTc HMPAO single photon emission computed tomography

The current clinical practice of reporting images obtained with single photon emission computed tomography (SPECT) with 99mTc-d,l-hexamethylpropylene amine oxime (99mTc HMPAO) images was examined by having 16 experts evaluate the appearance of SPECT images in patients with probable Alzheimer type dementia (ATD), patients with major depressive episode (DSM-IV), and healthy volunteers. The experts rated diagnostic criteria of scan appearance in respect of importance for their individual diagnostic practice. Experts were nuclear medicine specialists, psychiatrists and physicists taking part in a European multi-centre collaborative project. They examined 158 perfusion scans and then the same perfusion scans together with statistical parametric maps (SPMs). The sensitivity of experts' diagnostic judgments was significantly and negatively correlated with the importance they attributed to reduced regional perfusion in the parietal lobes. A corresponding positive correlation was observed for diagnostic specificity against depressed and healthy volunteers. Similar results were observed with SPMs, where in addition area under the receiver operating characteristic (ROC) curve was significantly reduced with raters' increased diagnostic reliance on frontal lobe perfusion deficits. Sensitivity was greater with SPM for patients younger than 70 years and with dementia severity. The more importance experts placed on parietal (symmetrical) perfusion deficits, the less sensitive and the more specific their diagnostic judgment was. Using multiple raters in large patient samples may provide a way of identifying successful explicit diagnostic strategies for clinical image analysis.