Biomedical subjects

F Fazio

Publications and source records attributed to F Fazio.

At least 163 records · Page 9Linked to original sources

PubMed1996

Registration of multi-modal biomedical images of the heart.

Integration of multi-modal biomedical images of the heart (PET, SPET, MRI, Echocardiography) is a diagnostic procedure of increasing interest. Different registration techniques can be used to spatially correlate two independent tomographic scans of the same patient, each technique presenting relative merits and limitations. Integration of cardiac with respect to neurological images is difficult, because the heart is a non-rigid and moving organ. The experiences of this approach of integrated diagnosis are thus limited to date. However, registration of PET, SPET, MRI, Echocardiographic images has been described with accuracy considered acceptable for clinical applications. Registration techniques for the integration of multi-modal biomedical images of the heart, the clinical applications of cardiac image fusion and the experiences reported in the literature are presented in this paper.

Diagnostic Imaging↗

PubMed1996

Quantitative comparison of direct antibody labeling and tumor pretargeting in uveal melanoma.

UNLABELLED: SPECT radioimmunoscintigraphy with 99mTc-labeled anti-melanoma monoclonal antibodies (MAbs) 225.28S is being used to detect uveal melanoma. Recently, pretargeting methods have been described to reduce background activity and perform imaging in a shorter time interval. METHODS: We compared the three-step pretargeting method with conventional radioimmunoscintigraphy in 15 patients with a clinical and laboratory diagnosis of uveal lesion. High-resolution SPECT radioimmunoscintigraphy was performed in all patients with directly labeled MAbs and, 1 wk later, with the three-step pretargeting technique. Eleven patients underwent eye enucleation and specimens of uveal melanoma were available for histology, whereas four patients underwent conservative therapy. The percent injected dose (%ID) delivered to the tumor and the tumor-to-background ratio were calculated. RESULTS: In all three-step radioimmunoscintigraphy studies, there was a reduction of nonspecific nasopharyngeal background. The three-step radioimmunoscintigraphy tumor-to-nontumor ratio was 3.1 +/- 1.3 versus 1.5 +/- 0.5 of conventional radioimmunoscintigraphy, while the percent injected dose on the tumor was similar for the two methods (4.4 +/- 3.0 versus 3.8 +/- 2.8) x 10(-3). CONCLUSION: Improved SPECT imaging with the three-step radioimmunoscintigraphy results from reduced background and from higher counting statistics due to reduction of time interval between radiotracer administration and imaging, whereas the absolute amount of tracer delivered to the tumor by the two methods is comparable.

Antibodies, Monoclonal↗

PubMed1996

[A comparison between propafenone and hydroquinidine perorally in the treatment of recent-onset atrial fibrillation].

The aim of this study was to assess the effectiveness of propafenone and quinidine to restore sinus rhythm in patients with paroxysmal atrial fibrillation. Eighty consecutive patients with recent onset atrial fibrillation were randomized to one of the following oral treatments: a) propafenone 450 mg as single dose followed by 300 mg t.i.d.; b) hydroquinidine 900 mg/24 hours + digoxin if necessary. Drugs were given for a maximum of three days and withdrawn at the restoration of sinus rhythm. If atrial fibrillation was persistent, the other drug was administered after two days wash out. The two groups did not differ from each other with respect to left atrial size, age and presence of organic heart disease, and kind of cardiopathies between the two groups. Sinus rhythm was restored in 39 patients of group 1 (93%) and 36 of group 2 (95%). In conclusion, oral propafenone is as effective as quinidine in the treatment of paroxysmal atrial fibrillation.

Administration, Oral↗

PubMed1996

Imaging osteomyelitis with streptavidin and indium-111-labeled biotin.

UNLABELLED: Animal studies of infection imaging by a two-step protocol have shown that important improvements in target to nontarget ratios are possible. In this protocol, unlabeled streptavidin is administered and allowed sufficient time to accumulate in the lesion, probably by nonspecific processes, and to clear elsewhere. Thereafter, 111Inbiotin is administered. A fraction of the labeled biotin may be retained in the lesion because of biotin's high affinity for streptavidin while most of the activity is cleared through the kidneys. METHODS: Radioscintigraphy with unlabeled streptavidin followed with 111Inlabeled biotin was performed in 15 patients with chronic osteomyelitis. As controls, each patients received either 111In-labeled biotin without the preadministration of streptavidin or 111In-labeled nonspecific IgG. RESULTS: Regions of focal uptake were identified in all patients receiving streptavidin followed by radiolabeled biotin as early as 10 min postadministration of radioactivity, and retention of label was evident through 24 hr. Coincident regions of abnormal accumulation were apparent with 111In-IgG, but only in delayed images. Moreover, with 111In-biotin alone, without the preadministration of streptavidin, focal accumulations were detected in areas similar to that identified with the two-step protocol. Although, these observations were only in the earliest images. CONCLUSION: The results of this preliminary clinical investigation suggest that a two-step protocol with unlabeled streptavidin and radiolabeled biotin may be an alternative for the detection of infection.

Adult↗

PubMed1995

Different neural systems for the recognition of animals and man-made tools.

Using positron emission tomography, we mapped brain activity in normal volunteers during the recognition of visual stimuli representing living (animals) and non-living (artefacts) entities. The subjects had to decide whether pairs of visual stimuli were different representations of the same object, or different objects. Animal recognition was associated with activations in the inferior temporo-occipital areas, bilaterally, whereas artefact recognition engaged a predominantly left hemispheric network, involving the left dorsolateral frontal cortex. These findings, which concur with clinical observations in neurological patients, provide in vivo evidence for a fractionation of the neural substrates of semantic knowledge in man.

Adult↗

PubMed1995

Clinical/metabolic correlations in multiple system atrophy. A fludeoxyglucose F 18 positron emission tomographic study.

OBJECTIVE: To evaluate the regional cerebral metabolic involvement; the relationships among regional brain metabolism, clinical features, and quantitative measures of disease severity; and the patterns of brain involvement that can be related to the different types of onset: striatonigral degeneration vs olivopontocerebellar atrophy. DESIGN: Fludeoxyglucose F 18 positron emission tomography (PET) studies performed in patients with multiple system atrophy (MSA) were evaluated for their clinical features at the onset of the disease and at the time of the PET study. CASES: Seventeen patients diagnosed as having probable MSA and 10 age-matched controls. RESULTS: The hypometabolism in the putamen-pallidum complex and in the cerebellum was the best discriminant for disease classification. The efficacy of levodopa treatment was positively correlated with the metabolic activity of the putamen-pallidum complex. The patients with olivopontocerebellar atrophy type (N = 8) had a prevalent hypometabolism in the cerebellum, while the patients with striatonigral degeneration type (N = 9) had a prevalent impairment in the pallidum-putamen complex. We demonstrated a negative correlation between (1) severity of parkinsonism and metabolic values of putamen and caudate; (2) severity of cerebellar signs and metabolism in the cerebellum; and (3) autonomic dysfunction and metabolic activity in the thalamus, frontal, and temporal regions, bilaterally. CONCLUSIONS: These findings support the selective metabolic reduction in the putamen and cerebellum as a marker of MSA. The clinical/metabolic correlations, demonstrating the expected dependence of extrapyramidal and cerebellar signs by dysfunction of basal ganglia and cerebellum, also support a possible involvement of central nervous system structures in autonomic control.

Atrophy↗

PubMed1995

An elastic computerized brain atlas for the analysis of clinical PET/SPET data.

An elastic computerized brain atlas was developed for the analysis of positron emission tomography/single-photon emission tomography (PET/SPET) data. It consists of a set of digital anatomical contours and a template of regions of interest, schematically describing the brain, derived from a currently used anatomical/functional brain atlas. A warping algorithm, matching equivalent contours, was implemented to elastically fit the atlas to individual brain images. The elastic computerized brain atlas was applied to representative magnetic resonance imaging (MRI)-PET/SPET studies, MRI providing the anatomical information used by the matching procedure. The atlas is suited for clinical use in a nuclear medicine environment.

Brain↗

PubMed1995

Spatial registration of echocardiographic and positron emission tomographic heart studies.

A method has been developed to match corresponding heart regions from functional echocardiographic (Echo) and metabolic fluorine-18-fluoro-2-deoxy-D-glucose ([18F]FDG) positron emission tomography (PET) studies in individual patients. Echo and PET images are spatially correlated by determining homologous anatomical landmarks (the two papillary muscles and the inferior junction of the right ventricle), identifiable in images obtained by both acquisition modalities. Echo-PET image registration is first performed in the plane identified by the three landmarks, using a rigid rotate-translate scale model. The registration parameters are then used to transform the whole PET volume. This allows a consistent Echo-PET regional analysis, according to a segmental subdivision of the heart. The technique was tested on patients. The overlay of Echo and PET registered images proved the reliability of realignment of the three markers and a good spatial correlation of myocardial walls. This approach to image registration could be applied to other acquisition modalities (such as magnetic resonance imaging and single-photon emission tomography), provided that the three anatomical landmarks are visualized.

Deoxyglucose↗

PubMed1995

Specificity and sensitivity of exercise-induced ST segment elevation for detection of residual viability: comparison with fluorodeoxyglucose and positron emission tomography.

OBJECTIVES: We evaluated the sensitivity and specificity of exercise-induced ST segment elevation for the detection of residual myocardial viability. BACKGROUND: Assessment of residual viability after myocardial infarction is relevant for establishing indication for revascularization. We have previously shown that exercise-induced ST segment elevation is a marker of residual viability. METHODS: We studied 34 patients with a previous Q wave myocardial infarction (anterior in 21, inferior in 13) of whom 18 (group A) had exercise-induced ST segment elevation in more than one lead (mean [+/- SD] 1.8 +/- 0.9 mm, range 1 to 4) and 16 (group B) did not. All patients underwent rest technetium-99m methoxyisobutyl isonitrile single-photon emission computed tomography (SPECT), fluorine-18 (F-18) fluorodeoxyglucose positron emission tomography and coronary angiography. The time elapsed between the infarction and the viability study was 72 +/- 108 days (range 15 to 400) in group A and 516 +/- 545 days (range 14 to 1,800) in group B. RESULTS: The presence and site of previous infarction were confirmed by SPECT studies in all 34 patients. Uptake of F-18 fluorodeoxyglucose within the infarcted area was present in 18 of 18 patients in group A but in only 9 (56%) of 16 in group B (p < 0.01). In patients with an anterior infarction, the sensitivity, specificity and predictive accuracy of exercise-induced ST segment elevation for detection of residual viability were 82%, 100% and 86%, respectively (95% confidence intervals 46% to 83.5%, 59% to 100% and 55.6% to 87.1%, respectively). CONCLUSIONS: Exercise-induced ST segment elevation in infarct-related leads has a high specificity and acceptable sensitivity for detection of residual viability within the infarcted area.

Coronary Angiography↗

PubMed1995

Clinical brain radionuclide imaging studies.

A recent survey of the knowledge and practice of both positron-emission tomography (PET) and single-photon emission computed tomography (SPECT) of the brain among referring physicians in Europe (neurologists and psychiatrists) showed a disquieting lack of knowledge of the potential of these methodologies in the investigation and management of patients of their own specialities. The need to bring the knowledge of the potential of these techniques to the practicing physicians is paramount. It is imperative that the methodologies and concepts that preside over the application of these techniques in neurology and psychiatry must become more uniform if an impact is to be felt at a clinical level. There is clear improvement in the instrumentation available with the new state-of-the-art tomographic devices and with the development of new technetium-based radiopharmaceuticals for the study of cerebral perfusion. The constant progress made with ligands that permit the study of neurotransmission, tumor metabolism, and turnover do expand our capability to improve the knowledge concerning neurophysiology, neuropathology, and neuropharmacology of a variety of disease states. PET and SPECT will be progressively included in protocols aimed at stratifying patients with dementia, monitoring therapeutic trials, and improving our ability to determine outcome. Clinical usefulness of PET and SPECT begin to emerge in cerebral vascular disease, in the identification of cerebral death, in epilepsy, in cerebral trauma, in the investigation of HIV-positive patients with cerebral involvement, and in the monitoring of tumor recurrence and postirradiation damage. This review article outlines a current perspective of SPECT and PET as practiced in Europe, its potential, and its limitations.

Brain↗

PubMed1995

Avidin and 111In-labelled biotin scan: a new radioisotopic method for localising vascular graft infection.

OBJECTIVES: To evaluate a new imaging technique, for diagnosis of prosthetic vascular graft infection. Avidin is a protein which accumulates nonspecifically at sites of inflammation or infection. Due to its extremely low dissociation constant with biotin sites of infection can be imaged, using avidin as a pre-target, followed by injection of 111In-labelled biotin. This technique is much simpler than the common scintigraphic methods which employ labelling of blood components and its target-to-background ratio is greater than the methods employing radiolabelled proteins. DESIGN: Prospective clinical study. SETTING: A single department of vascular surgery and one of nuclear medicine of a Northern Italian hospital. MATERIALS: Between May 1993 and May 1994, 31 grafts in 26 patients were studied; the series included 23 men and three women with a mean age of 65.5 years (range 54-76 years). The prosthetic graft (Dacron -16, ePTFE -15) were: aortoaortic 5, aortobifemoral 15, aortoiliac 1, and femoropopliteal 10. Sixteen patients were suspected of having a vascular graft infection (Group A), the other 10 patients served as controls (Group B). 20 mg of Avidin were injected iv, followed 24 h later by i.v. injection of 500 micrograms of Biotin labelled with 74 MBq of 111In. CHIEF OUTCOME MEASURES: Whole-body imaging was performed at 10 min and 2 h post-injection, along with SPECT imaging when indicated. Scan results were correlated with the traditional imaging modalities and the clinical outcome of the patients. MAIN RESULTS: In Group A: two patients (three grafts) were excluded from the study, there were six true-positives, one false-positive and 11 true-negatives. Results in Group B: 10 true-negatives. The overall sensitivity was 100%, the specificity 95%, the accuracy 96%, the positive predictive value 86% and the negative predictive value 100%. CONCLUSIONS: These data suggest that Avidin/111In-labelled Biotin scintigraphy is a useful non invasive diagnostic method for early diagnosis of suspected prosthetic vascular graft infection.

Aged↗

PubMed1995

Systemic and cerebral kinetics of 16 alpha [18F]fluoro-17 beta-estradiol: a ligand for the in vivo assessment of estrogen receptor binding parameters.

Estrogen receptors are expressed in several brain areas of various animal species, and steroid hormones exert physiologic and biochemical effects on the central nervous system. The aim of the present study was to evaluate in female adult rats, the suitability of 16 alpha [18F]fluoro-17 beta-estradiol ([18F]FES), a selective estrogen receptor ligand, for the in vivo assessment of brain estrogen receptors. This was considered to be a preliminary step in evaluating the potential usefulness of [18F]FES for studies of cerebral estrogen receptors with positron emission tomography (PET) in nonhuman primates and human subjects. We evaluated (a) the time course of the metabolic degradation of [18F]FES in blood; (b) the time course of distribution of the tracer in discrete cerebral areas; (c) the inhibitory effect of increasing doses of cold estradiol on cerebral [18F]FES uptake; and (d) the possibility of in vivo quantification of estrogen receptor binding parameters using both equilibrium and dynamic kinetic analyses. We quantified [18F]FES binding to estrogen receptors using both equilibrium and dynamic kinetic analyses. The results of this study indicate that [18F]FES is a suitable tracer for the measurement of estrogen receptors in the pituitary and hypothalamus, using either the equilibrium or the kinetic analysis. However, [18F]FES is inadequate for the in vivo investigation of estrogen binding sites in brain areas with low receptor density, such as the hippocampus.

Animals↗

PubMed1995

Application of a surface matching image registration technique to the correlation of cardiac studies in positron emission tomography (PET) by transmission images.

The aim of this work is to assess the accuracy of a surface matching registration (SMR) technique for the correlation of cardiac studies in positron emission tomography (PET). Registration parameters were estimated by matching corresponding body surfaces, extracted from transmission studies, aligned to the PET emission images to be correlated. The accuracy of the SMR technique in this specific application was assessed by computer simulations, phantom experiments and on clinical PET data. Registration accuracy was evaluated in relation to the body surfaces (external, internal and the combination of the two) used by the SMR method. Better results were found when matching shaped and irregular surfaces such as internal lung contours. The robustness of the method was verified for different counting statistics recorded in transmission images. A clinical validation of the SMR method was performed on fluorine-18-deoxyglucose PET cardiac studies.

Computer Simulation↗

PubMed1995

Regional cerebral metabolism of glucose in comatose and vegetative state patients.

Regional cerebral metabolism of glucose (rCMRglu) was evaluated in patients who were in a coma and vegetative state to determine the level of brain function during these conditions. rCMRglu was measured in 17 discrete brain regions with (/-) [18F] -fluoro-2-deoxy-D-glucose (FDG) and positrn emission tomography (PET) in 15 patients with ;brain pathology subsequent to cardiorespiratory arrest (CA), head trauma (HT), or brain ischemia (BI) resulting from cerebrovascular accident or brain surgery. Five comatose patients (Coma group, n = 5), and 10 vegetative state patients (VS, patients awake but not aware) were studied. The VA patients were subdivided, according to the length of their VS condition, into a VS group (n = 6, < 3 months if CA or BI patients, or < 12 months if HT patients) and a persistent vegetative state group (PVS, n = 4, > 3 months if CA or BI patients of > 12 months if HT patients.) Ten normal age-matched subjects served as control. Global CMRglu was 6.72 +/- 0.93 (+/-SD) mg/100 g/min in control subjects. It was significantly (p < - 0.001) reduced to 3.70 +/- 61 in coma, to 3.45 +/- in VS, and to 2.33 +/- 0.34 mg/100 g/min in PVS patients. rCMRglu was significantly reduced (p < - 01001) from control values in all the 17 structures surveyed in every patient. In the Coma and VS groups, there was an overlapping of rCMRglu in the majority of the brain structures. (ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1995

Increased interictal cerebral glucose metabolism in a cortical-subcortical network in drug naive patients with cryptogenic temporal lobe epilepsy.

Positron emission tomography with [18F]-2-fluoro-2-deoxy-D-glucose ([18F]FDG) has been used to assess the pattern of cerebral metabolism in different types of epilepsies. However, PET with [18F]FDG has never been used to evaluate drug naive patients with cryptogenic temporal lobe epilepsy, in whom the mechanism of origin and diffusion of the epileptic discharge may differ from that underlying other epilepsies. In a group of patients with cryptogenic temporal lobe epilepsy, never treated with antiepileptic drugs, evidence has been found of significant interictal glucose hypermetabolism in a bilateral neural network including the temporal lobes, thalami, basal ganglia, and cingular cortices. The metabolism in these areas and frontal lateral cortex enables the correct classification of all patients with temporal lobe epilepsy and controls by discriminant function analysis. Other cortical areas--namely, frontal basal and lateral, temporal mesial, and cerebellar cortices--had bilateral increases of glucose metabolism ranging from 10 to 15% of normal controls, although lacking stringent statistical significance. This metabolic pattern could represent a pathophysiological state of hyperactivity predisposing to epileptic discharge generation or diffusion, or else a network of inhibitory circuits activated to prevent the diffusion of the epileptic discharge.

3-O-Methylglucose↗

PubMed1995

High-resolution SPECT study of regional cerebral blood flow in drug-free and drug-naive schizophrenic patients.

OBJECTIVE: The purpose of the study was to compare regional cerebral blood flow (CBF) in schizophrenic patients never treated with psychotropic drugs (drug-naive) and in schizophrenic patients free from drugs for various amounts of time. METHOD: Seventeen schizophrenic patients (nine who were drug naive and eight who had been drug free for at least 3 weeks) and 12 healthy volunteers were included in the study. Regional cerebral perfusion was studied with the use of a head-dedicated, high-resolution single photon emission computed tomography (SPECT) system. Cerebral SPECT scans were performed with technetium-99m-hexamethyl-propyleneamine oxime as a tracer. Regional CBF was measured as a ratio of regional tracer uptake to either cerebellar or whole brain tracer uptake. RESULTS: When the cerebellum was taken as the reference region, the drug-naive patients showed a significant bilateral reduction of perfusion in the mesial, dorsolateral, and basal prefrontal cortex, in the temporal cortex, and in the subcortical gray structures: thalamus, caudate nucleus, and putamen/pallidum complex. No significant differences emerged in the comparison between the drug-free patients and the healthy subjects. With correction for whole brain activity, some of the differences that had been found disappeared, but a significant hypoperfusion persisted in the basal ganglia and thalamus of the drug-naive, but not the drug-free, patients. Few correlations between symptom presentation and regional CBF perfusion were observed in the schizophrenic patients. CONCLUSIONS: These results suggest a pattern of cerebral hypoperfusion in schizophrenic patients never treated with neuroleptics that was not detectable in patients who had undergone various periods of pharmacological washout.

Adolescent↗

PubMed1995

[18F]FDG PET study in obsessive-compulsive disorder. A clinical/metabolic correlation study after treatment.

BACKGROUND: We used [18F]FDG and PET in patients with obsessive-compulsive disorder (OCD) to evaluate cerebral metabolic involvement before and after treatment with serotonin-specific reuptake inhibitors. METHOD: In 11 untreated, drug-free adults, regional cerebral metabolic rate for glucose (rCMRglu) was compared with that of 15 age-matched normal controls. RESULTS: rCMRglu values were significantly increased in the cingulate cortex, thalamus and pallidum/putamen complex. After treatment a significant improvement in obsessive-compulsive symptoms on the Y-BOC scale (t = 3.59, P < 0.01) was associated with a significant bilateral decrease of metabolism in the whole cingulate cortex (P < 0.001). Clinical and metabolic data were significantly intercorrelated (Kendall's tau = 0.65; P < 0.01). CONCLUSIONS: These findings indicate that OCD is associated with functional hyperactivity of a selected neuronal network and that treatment to reduce symptoms may have a selective neuromodulatory effect on cingulate cortex.

Adolescent↗

PubMed1995

Myocardial glucose uptake evaluated by positron emission tomography and fluorodeoxyglucose during hyperglycemic clamp in IDDM patients. Role of free fatty acid and insulin levels.

Myocardial and whole-body glucose metabolism was assessed in 19 insulin-dependent diabetes mellitus (IDDM) patients. A hyperglycemic clamp was performed 1) in the absence of insulin at free fatty acid (FFA) levels of 1.0 mmol/l (test 1); 2) in the absence of insulin at low FFA levels (0.1 mmol/l) by means of a lipid-lowering drug, acipimox (test 2); 3) during insulin infusion to achieve systemic levels of 400 pmol/l and FFA levels of 0.1 mmol/l (test 3); and 4) at the insulin levels of test 3 but increasing FFA to 1.0 mmol/l by means of heparin and intralipid infusion (test 4). Myocardial glucose uptake was measured by positron emission tomography (PET) and 2-[18F]fluoro-2-deoxy-D-glucose. Whole-body glucose uptake was measured in the four conditions by the glucose infusion rate during the PET scanning period. Myocardial glucose uptakes were 40.3 +/- 18.0, 395.5 +/- 139.6, 852.2 +/- 99.1, and 1,388.4 +/- 199.1 mumol.kg tissue-1.min-1 (mean +/- SD) and whole-body glucose uptakes were 10.1 +/- 2.3, 10.1 +/- 3.4, 42.8 +/- 5.8, and 30.5 +/- 5.6 mumol.kg body wt-1.min-1 during tests 1, 2, 3, and 4, respectively. Thus, in IDDM patients without coronary artery disease under the condition of hyperglycemia, an increase of myocardial glucose uptake was obtained either by lowering of FFA levels during hypoinsulinemia or by an increase in FFA levels during hyperinsulinemia. In both conditions no significant changes of whole-body glucose uptake were demonstrated.

Adult↗