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Biomedical subjects

F Nobili

Publications and source records attributed to F Nobili.

At least 19 recordsLinked to original sources
PubMed2007

99mTc-HMPAO and 99mTc-ECD brain uptake correlates of verbal memory in Alzheimer's disease.

AIM: Technetium-99m hexamethylpropylene amine oxime ((99m)Tc-HMPAO) and technetium-99m N,N-1,2-ethylene diylbis-Lcysteine diethyl ester dihydrochloride ((99m)Tc-ECD) SPECT are widely used in Dementia Clinics for early and differential diagnosis. They have been shown to perform differently in Alzheimer's disease (AD), but the impact of such differences on both research and clinical work is unknown. We investigated the differences between the 2 compounds in research work by assessing correlation between performance on a verbal memory task and cerebral perfusion in 2 matched groups of AD patients. METHODS: Nineteen pairs of patients with mild to moderate AD undergoing SPECT with either 99mTc-HMPAO or (99m)Tc-ECD were retrospectively selected in a Memory Clinic. Patients were matched for sex, age (+/-3 years) and the Mini-Mental State Examination score (+/-2 points) with a case-control procedure, thus obtaining 2 well-matched groups. The score on the Grober-Buschke selective reminding test (SRT) was correlated with SPECT in each group by means of statistical parametric mapping 99 (height threshold: P<0.01). RESULTS: (99m)Tc-HMPAO SPECT yielded 3 significant correlation clusters involving inferior and middle frontal gyri, para-hippocampal gyrus and putamen in the right hemisphere; the middle and superior temporal gyri, insula and claustrum in the left hemisphere. (99m)Tc-ECD gave a significant cluster of correlation in left postcentral gyrus and inferior parietal lobule. CONCLUSION: (99m)Tc-HMPAO SPECT correlation sites seem more consistent than (99m)Tc-ECD ones with the neurophysiological models of verbal memory, as designed both in normal individuals and in pathological conditions. The demonstration of such relevant differences introduces a source of variability among studies performed with either of the 2 compounds, which must be considered when interpreting results.

Aged↗
PubMed2006

Mild cognitive impairment (MCI) in medical practice: a critical review of the concept and new diagnostic procedure. Report of the MCI Working Group of the European Consortium on Alzheimer's Disease.

Mild cognitive impairment (MCI) was proposed as a nosological entity referring to elderly people with mild cognitive deficit but no dementia. MCI is a heterogeneous clinical entity with multiple sources of heterogeneity. The concept of MCI was reviewed and a diagnostic procedure with three different stages was proposed by the European Consortium on Alzheimer's Disease Working Group on MCI. Firstly, MCI should correspond to cognitive complaints coming from the patients or their families; the reporting of a relative decline in cognitive functioning during the past year by a patient or informant; cognitive disorders as evidenced by clinical evaluation; absence of major repercussions on daily life; and absence of dementia. These criteria, similar to those defined during an international workshop in Stockholm, make it possible to identify an MCI syndrome, which is the first stage of the diagnostic procedure. Secondly, subtypes of MCI had to be recognised. Finally, the aetiopathogenic subtype could be identified. Identifying patients at a high risk for progression to dementia and establishing more specific and adapted therapeutic strategies at an early stage, together with more structured overall management, is made possible by the diagnostic procedure proposed.

Activities of Daily Living↗
PubMed2006

The Von Restorff effect in ageing and Alzheimer's disease.

The purpose of the study was to evaluate the Von Restorff effect in normal ageing and in Alzheimer's disease (AD). A shortened paradigm was administered to three groups of subjects: young volunteers, elderly volunteers and patients with early-stage AD (MMSE>20). Each subject was presented with 25 lists of 10 words each, the target word appearing in double font size. A free recall phase followed the presentation of each list; after completion of the battery, a size recognition test was administered and subjects were inquired regarding the strategy employed and perception of target words. The total number of recalled words differed significantly among the three groups (young volunteers 144.4+/-38.6, elderly volunteers 86.5+/-17.6, patients 44.2+/-14.6). A significant difference in percentage of recall was found between target and non-target words in young (60.0+/-13.8% vs. 45.7%+/-15.0%, p<0.001) and in elderly (31.2+/-11.4% vs. 20.2+/-6.9%, p<0.001) volunteers, but not in patients (10.7+/-6.9% vs. 11.8+/-7.3%). The present study highlights that the Von Restorff effect can be detected in healthy elderly subjects, and that it is significantly reduced in patients in the early stage of AD. On the basis of the findings of the present study it is not possible to disentangle the contribution of visual-perceptual and encoding impairment, both of them potentially contributing to the observed reduction.

Adult↗
PubMed2006

Stimulating or conventional perineural catheters after hallux valgus repair: a double-blind, pharmaco-economic evaluation.

BACKGROUND: We prospectively evaluated direct analgesia-related costs of continuous sciatic nerve block using either a stimulating or conventional catheter after hallux valgus repair. METHODS: The perineural catheter was inserted through a stimulating introducer either blindly (group Conventional, n= 38) or while stimulating via the catheter (group Stimulating, n= 38). Nerve block was induced with 25 ml of mepivacaine 15 mg/ml, and was followed 3 h later by a patient-controlled infusion of ropivacaine 2 mg/ml (basal infusion: 3 ml/h; incremental dose: 5 ml; lock-out time: 30 min). Rescue tramadol [100 mg intravenous (i.v.)] was given if required. Local anesthetic consumption, need for rescue tramadol and post-operative nausea and vomiting (PONV) treatment, and patient's satisfaction were recorded during first 24-h infusion. Cost calculations were based on the acquisition cost of drugs and devices. RESULTS: Both techniques were similarly effective, but local anesthetic consumption and need for rescue analgesics were lower in the Stimulating group [respectively, 120 vs. 153 ml (P= 0.004) and 21% vs. 60% (P= 0.001)]. The analgesia-related costs for 24 h were similar when 100-ml bags of ropivacaine 2 mg/ml were used (66 euro vs. 67 euro; P= 0.26). When 200-ml bags of ropivacaine were used, the analgesia-related costs were higher in the Stimulating group than the Conventional group (75 euro vs. 55 euro; P= 0.0005). CONCLUSIONS: Direct costs of continuous sciatic nerve block ranged from 55 to 75 euro. Stimulating catheters reduced local anesthetic consumption and need for rescue analgesics. This was only cost effective when 100-ml bags of 2 mg/ml ropivacaine were used, while the cheapest combination was the use of conventional catheters and 200-ml bags of ropivacaine.

Adult↗
PubMed2005

Global cognitive impairment should be taken into account in SPECT-neuropsychology correlations: the example of verbal memory in very mild Alzheimer's disease.

PURPOSE: To examine the impact of severity of global cognitive impairment on SPECT-neuropsychology correlations, we correlated a verbal memory test with brain perfusion in patients with very mild Alzheimer's disease (AD), taking into account the Mini-Mental State Examination (MMSE) score as an index of global cognitive impairment. METHODS: Twenty-nine outpatients (mean age 78.2+/-5.5 years) affected by very mild, probable AD underwent brain SPECT with 99mTc-ethylcysteinate dimer and a word list learning test. SPM99 was used for voxel-based correlation analysis after normalisation to mean cerebellar counts (height threshold: p<0.01). In a first analysis, only age and years of education were inserted as nuisance covariates, while in a second analysis the MMSE score was inserted as well. RESULTS: In the first analysis, two clusters of significant correlation were found in both hemispheres, mainly including regions of the right hemisphere, such as the inferior parietal lobule, the middle temporal gyrus and the posterior cingulate. Significant correlation in the left hemisphere was observed in the lingual lobule, the parietal precuneus and the posterior cingulate. After taking into consideration the MMSE, the largest cluster of correlation was found in the left hemisphere, including the parietal gyrus angularis, the posterior cingulate and the middle temporal gyrus. CONCLUSION: The wide differences observed between the correlations achieved with and without taking into account the MMSE score indicate that severity of global cognitive impairment should be considered when searching for brain perfusion-neuropsychology correlations. In the present case, this strategy resulted in correlations that more closely matched neuropsychological models of verbal memory deficit.

Aged↗
PubMed2005

White matter hyperintensities on brain magnetic resonance in systemic sclerosis.

OBJECTIVE: To evaluate the brain status of patients with systemic sclerosis (SSc). METHODS: Fourteen female patients with SSc aged 24-74, with a disease duration of 1-12 years and without other relevant systemic diseases, were enrolled. All patients and an age matched female control group (CG) of 14 clinically normal subjects, underwent brain magnetic resonance examination at 1.5 T; spin echo proton density weighted images were evaluated. Mann-Whitney U and Spearman rank correlation tests were used for statistical analysis. RESULTS: 170 white matter hyperintensities >/=2 mm in diameter were counted in the patient group (range 0-75, mean 12.1, median 4.5), only 13 in the CG (0-2, 0.9, 1, respectively), with a significant difference (p = 0.011). Moreover, 208 white matter hyperintensities <2 mm were found in the patient group (0-38, 14.9, 8, respectively), only 31 in the CG (0-7, 2.0, 1, respectively), with a significant difference (p = 0.006). No statistically significant correlation between the number of hyperintensities and either patient's age or disease duration was observed. CONCLUSION: White matter hyperintensities are more common in patients with SSc than in a CG. These findings might be related to obliterative microvascular processes due to the disease. Early brain involvement in patients with SSc may occur.

Adult↗
PubMed2004

Spray-dried plasma improves growth performance and reduces inflammatory status of weaned pigs challenged with enterotoxigenic Escherichia coli K88.

We investigated whether spray-dried plasma (SDP) improved growth and health of piglets challenged with enterotoxigenic Escherichia coli K88 (ETEC). Forty-eight pigs weaned at 21 d (BW = 4.88 +/- 0.43 kg) received one of four diets containing 6% SDP or fish proteins (as-fed basis) either nonmedicated (SDP-NM and FP-NM diets) or medicated with 0 or 250 mg/kg of colistine + 500 mg/kg of amoxycycline (SDP-M and FP-M diets), for 15 d. On d 4, pigs were orally challenged with ETEC. On d 15, eight pigs per dietary group were killed, blood and saliva were collected for analysis of K88 fimbriae-specific immunoglobulin (Ig)-A, and jejunum was removed for villi preparation, histological analysis, and cytokine expression. The presence or absence of K88 receptors (K88+ and K88- pigs respectively) was determined by villous adhesion assay. Effects of protein source on ADG (P = 0.04) and ADFI (P < 0.01), as well of medication on ADFI (P < 0.02), of all pigs were observed. In sacrified pigs, there was an effect of protein source on ADG (P = 0.03) and ADFI (P < 0.001), as well an interaction between medication and presence of K88 receptor (P = 0.02) for feed:gain ratio. Plasma K88 specific IgA were low in all K88 pigs and higher in K88+ pigs fed FP-NM compared with all the other groups (P < 0.05), except SDP-M. An interaction was found among protein source, medication, and presence of K88 receptors (P = 0.04). Saliva IgA concentrations were high in all pigs fed FP-NM and low in all other pigs. Jejunum of pigs fed FP-NM showed some ulcerations, edema, and mild inflammatory cell infiltration (ICI). In pigs fed FP-M, edema was reduced. Conversely, only a mild ICI was observed in pigs fed SDP-NM and SDP-M. Crypt depth was increased in K88+ pigs fed SDP-NM and an interaction between protein source and presence of K88 receptors was observed (P < 0.05). Expressions of tumor necrosis factor-alpha and interleukin (IL)-8 were lower in pigs fed SDP-NM and SDP-M than in those fed FP-NM and FP-M, either K88- or K88+ (P < 0.01). In pigs fed FP diets, expression of IL-8 tended to increase (P = 0.08) in K88+ compared with K88- subjects. Expression of interferon-gamma increased in K88 and K88+ pigs fed FP-M as compared with other pigs (P < 0.01). These results indicate that feeding with SDP improved growth performance and protected against E. coli-induced inflammatory status, and suggest that use of SDP-NM can be considered a valid antibiotic alternative.

Animal Feed↗
PubMed2003

Psychological and social aspects in management of Alzheimer's patients: an inquiry among caregivers.

A survey in the cities of Genoa and Savona (Italy) was performed to examine stress levels in caregivers of patients with Alzheimer's disease in the context of a project of the Italian Ministry of Health named Cronos. It offered free anticholinesterase inhibitor therapy to patients who addressed dedicated Neurological Units; in this occasion caregivers could be invited to express the main difficulties encountered in managing demented people during an interview conducted by health personnel of the Neurophysiology Service. Caregivers were mainly women, daughters or spouses, with a medium educational level, retired, housekeepers, employees or teachers; they claimed a lowering of economic standard of living of the family owing to extra expenses for assistance. Satisfaction was expressed towards specialists, while support by general practitioners and other sanitary services was usually lacking and money contribution from the government or territorial services was considered inadequate. From the emotional point of view, caregivers claim loss of free time, friendships and hobbies, and feel isolated in the social context; sometimes the patient's death is thought of as a solution. A strong need for information and support is clearly emerging and any further interventions should take these requirements into consideration.

Aged↗
PubMed2002

Duplex scanning of neck vessels: need for extending the consensus on indications.

We studied the percentage and distribution of appropriate indications for duplex scanning of neck vessels in an outpatient population. A total of 650 consecutive outpatients sent by their general practitioner (GP) or a specialist for duplex scanning of epi-aortic arterial vessels were studied. The aim was to verify the percentage of appropriate (APR) an inappropriate (INAPR) indications for the examination, according to the current literature. After analysis of indications as reported by GPs or specialists and a brief anamnestic examination, 77% of patients were found to have had one or more APR and 23% of patients had none. Analysis of severity of atheromasic lesions between the two groups showed that patients with APR had significantly ( p<0.001, chi-square test) more severe lesions than patients with INAPR. In more detail, no patient with INAPR had severe (>60%) stenosis while 6.4% of patients with APR had severe stenosis. Moreover, the percentage of normal examinations or intima-media thickness only was 32.5% in patients with INAPR but fell to 17.2% in patients with APR. In the entire group, women were more represented than men even after consideration of the natural prevalence of female gender in the local population. Among inappropriate indications for the examination, isolated dizziness or vertigo, syncope and tinnitus were the most frequent. Continuous medical education is needed to reduce inappropriate indications and thus to find solutions, although partial, to shorten the waiting lists that have become an urgent problem for the public health systems of several Western countries. However, this appears to be difficult challenge, as experiments conducted on this issue by other researchers only gave transient positive results.

Aged↗
PubMed2002

Spinal block or total intravenous anaesthesia with propofol and remifentanil for gynaecological outpatient procedures.

BACKGROUND AND OBJECTIVE: The aim of this prospective, randomized study was to compare the preparation and discharge times, the side-effects and patient satisfaction after gynaecological outpatient procedures performed using either spinal block or total intravenous anaesthesia with propofol and remifentanil. METHODS: With Ethics Committee approval and written informed consent, 40 healthy females scheduled for hysteroscopic ablation of endometrial neoplasm were randomly allocated to receive either a spinal block with bupivacaine 0.5% hyperbaric solution 10 mg (n = 20) or total intravenous anaesthesia with propofol and remifentanil (n = 20). Preparation and discharge times, as well as occurrence of untoward events and anaesthesia-related costs, were recorded. RESULTS: The median (range) preparation time was 7 (7-10) min with general anaesthesia, and 11 (7-21) min with spinal block (P = 0.00005). No differences in discharge time from the postanaesthesia care unit and incidence of hypotension or bradycardia, or both, were reported between the two groups. Hospital discharge times were 156 (101-345) min after general anaesthesia and 296 (195-720) min after spinal anaesthesia (P = 0.0005). Acceptance of the anaesthesia technique was better after general (100%) than after spinal anaesthesia (75%) (P = 0.04). No differences in total costs were reported between spinal block ([symbol: see text] 155 ([symbol: see text] 117-[symbol: see text] 224)) and propofol-remifentanil general anaesthesia ([symbol: see text] 143 ([symbol: see text] 124-[symbol: see text] 203) (P = 0.125)). CONCLUSIONS: Accurate titration of short-acting intravenous anaesthetic drugs such as propofol and remifentanil results in shorter preparation times and earlier home discharge after outpatient gynaecological procedures compared with spinal anaesthesia with hyperbaric bupivacaine 10 mg, with better patient acceptance and no increased costs.

Adult↗
PubMed2002

Brain functional involvement by perfusion SPECT in systemic sclerosis and Behçet's disease.

Involvement of the central nervous system is frequent in systemic immune-mediated diseases, such as systemic lupus erythematosus, Behçet's disease (BD), and systemic sclerosis (SSc). Structural brain examinations, such as computed tomography and magnetic resonance imaging, may be useful in diagnosing and following-up these cerebral syndromes in some cases, but they are more often inconclusive. Single photon emission computed tomography (SPECT) with perfusion tracers is a powerful method that can disclose brain involvement in many clinical situations, even in patients with subtle neurological symptoms. In fact, perfusion tracers can disclose regional hypoperfusion caused by both ischemia due to vascular narrowing and neuronal metabolic derangement due to direct neuronal damage. The latter phenomenon occurs because the blood flow to the brain is strictly regulated by metabolic demands, so that hypometabolism is reflected by hypoperfusion in most instances. SPECT findings in 42 mainly neurologically asymptomatic patients with SSc and in eight mainly neurologically symptomatic patients with BD are reported. SPECT was shown to be very sensitive and disclosed brain functional deficits in approximately half of SSc patients without neurological complaints and in all patients with BD, who had various neurological symptoms but usually inconclusive structural brain examinations.

Aged↗
PubMed2002

Carotid atherosclerosis in patients with rheumatoid arthritis: a preliminary case-control study.

A preliminary study was undertaken to investigate the severity of atherosclerotic lesions of neck arteries in patients with rheumatoid arthritis (RA) in comparison with matched controls. The working hypothesis derives from the recent view that the atherosclerotic plaque is essentially an inflammatory lesion. Thus, patients affected by a chronic inflammatory disease, such as RA, might show acceleration of atherosclerosis despite treatment with anti-inflammatory drugs. In 19 patients with RA the prevalence of atherosclerosis of internal carotid arteries, as seen on high-resolution duplex-scanning of neck arteries, was significantly (p < 0.05) higher than in 19 controls, whereas no significant difference was found for the other arteries. Factors underlying this finding are not known; increased levels of homocysteine and other thiol compounds that may enhance atherosclerosis in RA patients deserve further investigation. Moreover, more specific factors of RA are currently being investigated. In fact, immune complexes fixing C1q bind to endothelial receptors, thus triggering an upregulation of adhesion molecules, such as E-selectin and intercellular and vascular cell adhesion molecules 1, on the endothelium surface.

Aged↗
PubMed2002

Abnormal "low grade" transformation zone: current diagnostic gold standard.

The aim of this work was to examine different methods of investigation in the diagnosis of the abnormal "low grade" transformation zone of the portio. Over a period of one year 41 patients subjected to colposcopic examination underwent exo-endocervical sampling for oncologic evaluation and for detection of viral and bacterial infections (HPV, HSV, adenovirus, mycoplasmas and chlamydia trachomatis), as well as portio biopsy. A 65.8% correlation was found between cytology and the HPV-DNA test results, while histology and the presence of the HPV virus agreed in 51.4% of cases. In those cases in which minimal histological alterations were found (koilocytosis) a high percentage of HPV negativity was found. In discordant negative cytologic tests that were however positive for HPV by PCR, the genotypes identified were always 6 and 11.

Base Sequence↗
PubMed2001

Unique biochemical nature of carp retinol-binding protein. N-linked glycosylation and uncleavable NH2-terminal signal peptide.

Retinol transport and metabolism have been well characterized in mammals; however, very little is known in fish. To study the mechanism by which fish retinol-binding protein (RBP) is able to remain in plasma besides its small molecular size, we isolated RBP cDNA from a carp liver cDNA library. Comparison of the deduced amino acid sequence with that of known vertebrate RBPs showed that carp RBP has high homology to the other cloned vertebrate RBPs, but it lacks the COOH-terminal tetrapeptide, RNL(S)L, which is most likely involved in the interaction with transthyretin in mammalian RBPs. In addition, the primary structure of carp RBP contains two consensus N-linked glycosylation sites that represent a unique feature. We have obtained experimental evidence, by in vitro and in vivo expression experiments, that both sites are indeed glycosylated. We have also characterized the protein as a complex type N-linked glycoprotein by lectin binding assay, neuraminidase and endoglycosidase H and F digestion. Inhibition of glycosylation by tunicamycin treatment of transfected cells caused a great reduction of RBP secretion. Since kidney filtration of anionic proteins is less than half that of neutral protein of the same size, this finding strongly suggests that the amount of carp RBP filtration through kidney glomeruli may be reduced by a glycosylation-dependent increase in the molecular size and negative charge of the protein. A second unique feature of carp RBP as secretory protein is the presence of a nonconserved NH(2)-terminal hydrophobic domain, which functions as an insertion signal but is not cleaved cotranslationally and remains in the secreted RBP.

Amino Acid Sequence↗
PubMed2001

Relationships between cortisol, dehydroepiandrosterone sulphate and insulin-like growth factor-I system in dementia.

Changes in the hypothalamus-pituitary-adrenal axis (HPAA) function, entailing elevated cortisol circulating titres, occur in aging and in some neurological conditions, such as Alzheimer's disease (AD). Excess cortisol has neurotoxic effects which affect hippocampal neurones. Dehydroepiandrosterone sulphate (DHEAS) has an antiglucocorticoid activity and neuroprotective effects, but its levels decrease with aging. Glucocorticoids influence the production of insulin-like growth factor-I (IGF-I) and modify its systemic and neurotrophic biological activity by inducing changes in IGF-binding proteins (IGFBPs). We looked for relationships between cortisol, DHEAS levels, and IGF-I - IGFBPs system in AD. Cortisol, DHEAS and GH levels at 02:00, 08:00, 14:00, 20:00 h, basal IGF-I, IGFBP-1 and IGFBP-3 levels were determined by RIAs or IRMA in 25 AD patients, aged 58-89 yr, and in 12 age-matched healthy controls. AD subjects had higher cortisol, lower DHEAS levels and increased cortisol/DHEAS ratio (C/Dr) than controls. In AD cases, total IGF-I, IGFBP-3, and IGF-I/IGFBP ratios were significantly lowered, while IGFBP-1 levels were significantly higher than in controls. We found a significant inverse correlation between IGF-I and IGFBP-3 levels vs C/Dr, and between both IGF-I/IGFBPs ratios vs mean cortisol levels. IGFBP-3 correlated directly with DHEAS. Cortisol was directly and IGF-I inversely correlated with cognitive impairment. In AD patients we found that alterations in HPAA function and elevated C/Dr are related to lowered total and free IGF-I levels. These findings and their relationship to cognitive impairment suggest that changes in hormonal set-up might influence the clinical presentation of the disease.

Adrenal Glands↗
PubMed2001

Clinical correlative evaluation of an iterative method for reconstruction of brain SPECT images.

BACKGROUND: Brain SPECT and PET investigations have showed discrepancies in Alzheimer's disease (AD) when considering data deriving from deeply located structures, such as the mesial temporal lobe. These discrepancies could be due to a variety of factors, including substantial differences in gamma-cameras and underlying technology. Mesial temporal structures are deeply located within the brain and the commonly used Filtered Back-Projection (FBP) technique does not fully take into account either the physical parameters of gamma-cameras or geometry of collimators. In order to overcome these limitations, alternative reconstruction methods have been proposed, such as the iterative method of the Conjugate Gradients with modified matrix (CG). However, the clinical applications of these methods have so far been only anecdotal. The present study was planned to compare perfusional SPECT data as derived from the conventional FBP method and from the iterative CG method, which takes into account the geometrical and physical characteristics of the gamma-camera, by a correlative approach with neuropsychology. METHODS: Correlations were compared between perfusion of the hippocampal region, as achieved by both the FBP and the CG reconstruction methods, and a short-memory test (Selective Reminding Test, SRT), specifically addressing one of its function. A brain-dedicated camera (CERASPECT) was used for SPECT studies with 99mTc-hexamethylpropylene-amine-oxime in 23 consecutive patients (mean age: 74.2 +/- 6.5) with mild (Mini-Mental Status Examination score > or =15, mean 20.3 +/- 3), probable AD. Counts from a hippocampal region in each hemisphere were referred to the average thalamic counts. RESULTS: Hippocampal perfusion significantly correlated with the MMSE score with similar statistical significance (p < 0.01) between the two reconstruction methods. Correlation between hippocampal perfusion and the SRT score was better with the CG method (r = 0.50 for both hemispheres, p < 0.01) than with the FBP method (r = 0.37 and 0.43, respectively for the right and left hemisphere, p < 0.05 and p < 0.02). The bootstrap procedure showed that such correlation indexes were statistically different both in the right (p < 0.01) and in the left (p < 0.05) hemisphere. CONCLUSION: These results are interpreted as a better performance of the CG reconstruction method in correctly detecting counts from hippocampal ROI. By using the same gamma-camera or collimator, alternative methods for brain SPECT reconstruction may improve quality of data and then help SPECT diagnostic accuracy.

Aged↗
PubMed2001

Pulsatile electrical impedance response from cerebrally dead adult patients is not a reliable tool for detecting cerebral perfusion changes.

The original objective of this work was to verify the possibility of using electrical pulsatile cerebral impedance measurements as a diagnostic aid for assessing the brain-death condition in adults; a subordinate target was to validate a simple method for detecting perfusional changes in the brain. To this end, impedance signals were recorded, for a comparative study, from both live subjects and brain-dead patients, using a simple four-electrode arrangement. Rather unexpectedly, pulsatile transcephalic impedance waveforms exhibiting a temporal dependance similar to those of live subjects were detected in artificially ventilated, cerebrally dead, adult subjects; distributions of the time delays between impedance peaks and ECG peaks were also recorded for the two groups (dead and live subjects). These data provided no evidence, at the 1% significance level, against the hypothesis that the two sample groups are drawn from identical populations. The detection of impedance variations from brain-dead patients can be explained by the residual persistence of blood flow through the scalp, by mechanical variations synchronous with the heart beat and by the presence of the oscillating flow and the systolic spikes that precede the final blood flow arrest. The fact that impedance variations can be traced back to a multiplicity of causes, unrelated to the normal unidirectional flow, renders the transcephalic impedance method inappropriate for detecting cerebral perfusion changes in adults. This conclusion is also strengthened by some theoretical results recently derived from a multilayer model of the head.

Adult↗