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Biomedical subjects

F Fazio

Publications and source records attributed to F Fazio.

At least 109 records · Page 6Linked to original sources
PubMed1999

Assessment of CABG-related risk in patients with CAD and LVD. Contribution of PET with [18F]FDG to the assessment of myocardial viability.

BACKGROUND: Previous studies have demonstrated that hibernating myocardium can be assessed by [18F]fluorodeoxyglucose ([18F]FDG) and positron emission tomography (PET). This study evaluated the use of [18F]FDG-PET for CABG related risk assessment in patients with coronary artery disease (CAD) and left ventricle dysfunction (LVD). METHODS: We retrospectively evaluated 241 to patients candidate CABG presenting with signs and symptoms of congestive heart failure (CHF) prevailing over ischemic signs. Of the 241 patients, 153 had undergone [18F]FDG-PET as well as conventional assessment: 110 out of 153 (group A) were operated because of PET evidence of hibernation. Of the 241 patients, 88 had not undergone [18F]FDG-PET: 86 out of 88 (group B) were operated on. The outcome of surgical patients was evaluated by considering all major perioperative complications including the use of mechanical and pharmacological support and in-hospital mortality. After hospital discharge, each patient was examined at 1, 4 and every 6 months thereafter. RESULTS: Perioperative use of mechanical supports and inotropic drugs, was significantly lower for the PET selected group (A) than for the non PET selected group (B). Mortality within 30 days of surgery was 0.9% in group A and 19.8% in group B. The only predictors of perioperative outcome were the presence of hibernating tissue and the ejection fraction. CONCLUSIONS: [18F]FDG-PET prior to CABG can be crucial for the assessment of perioperative risk in patients with CAD.

Coronary Artery Bypass↗
PubMed1999

Comparison of dual-head coincidence PET versus ring PET in tumor patients.

UNLABELLED: This study compared the multiring detector (Ring-PET) and the dual-head coincidence imaging system (DH-PET) for staging/ restaging neoplastic patients before or after surgery or radiochemotherapy. METHODS: Seventy patients with suspected tumor recurrence or metastatic dissemination received an intravenous dose of 18F-fluorodeoxyglucose (FDG) under overnight fasting and were studied in sequence with a dedicated positron emission tomograph with Ring-PET and a DH-PET. Ring-PET studies were performed 45-75 min postinjection and were followed by a DH-PET scan approximately 3 h postinjection. Number and location of the hypermetabolic lesions detected on DH-PET and Ring-PET reconstructed images were blindly assessed by three independent observers. RESULTS: DH-PET identified all 14 head lesions detected by Ring-PET, 53 of 63 thoracic lesions and 36 of 45 abdominal lesions. Of the 19 lesions not identified by DH-PET, 6 were smaller than 10 mm, 8 were between 10 and 15 mm and 1 was 18 mm; dimensions of 4 bone lesions were not available. A concordant restaging, based on location and number of lesions detected, was found in all 14 patients with head tumors, in 28 of 30 patients with thoracic tumors and in 24 of 26 patients with abdominal tumors. CONCLUSION: We found a good agreement between Ring-PET and DH-PET assessment of oncologic patients in detecting hypermetabolic lesions > or = 10-15 mm.

Adult↗
PubMed1999

Lack of prognostic value of 99mTc MIBI rest, 18F FDG and 201TL rest/redistribution on PTCA outcome of patients with moderate left ventricle dysfunction.

BACKGROUND: The clinical work-out of patients undergoing coronary revascularization includes the assessment of myocardial viability. This approach has to be defined in the different classes of patients. The aim of this study was to evaluate the predictive prognostic value of different techniques on outcome following PTCA in patients with moderate left ventricle dysfunction (left ventricle EF > or = 40%). METHODS: Seventeen patients with EF > or = 40% and undergoing PTCA were studied by 201Tl rest/redistribution, 18F-FDG and 99mTc-MIBI rest. Regional kinesis was scored by echo, dividing left ventricle in 11 segments. The echo evaluation was repeated at 1 and 6 months after revascularization. RESULTS: Global EF was 52.5 +/- 7% and 69 segments had abnormal kinesis. Patients underwent stress/rest 99mTc-MIBI SPET, rest/redistribution 201Tl SPET and rest 18F-FDG PET. Among the 11 segments defined on echo-matched tomographic images, the one with the highest activity at stress was assumed as reference (activity = 100%). If > 50% of reference segment, 18F-FDG and 201Tl uptakes were considered significant. After PTCA, the echo-follow-up did not demonstrated significant improvement of left ventricle function at 30 days after PTCA (EF 56 +/- 6%) as well as at 6 months (EF 56 +/- 9%). The positive predictive value under these conditions resulted: 46.5% with 99mTc-MIBI rest, 47.4% with 201Tl rest-redistribution and 45.7% with 18F-FDG. CONCLUSIONS: In summary, in the class of patients with moderately compromised function, considering as reference the improved regional kinesis after PTCA, 99mTc-MIBI at rest, 201Tl rest/redistribution and 18F-FDG do not exhibit a clear predictive value; patient population is then a highly relevant point to establish the accuracy of these diagnostic procedures.

Adult↗
PubMed1999

FDG/PET and spiral CT image fusion for medistinal lymph node assessment of non-small cell lung cancer patients.

BACKGROUND: To assess the potential usefulness of 18F-FDG/PET and spiral-CT images concurrent assessment and coregistration in staging mediastinal lymph node involvement in patients with non small cell lung cancer. METHODS: 28 patients waiting to undergo surgical treatment underwent spiral-CT and PET examinations on the same day. The results of the two studies were interpreted separately, together (CT&PET) and following their fusion in a single image (CT+PET). Results of spiral-CT, PET, CT&PET and CT+PET were assessed with respect to the histological diagnosis. RESULTS: A correct assessment of mediastinal lymph nodes was achieved by spiral-CT in 21 of the 28 patients, in 22 of the 28 patients by PET, in 24 patients by CT&PET and in 25 patients by CT+PET. CONCLUSIONS: CT+PET is more accurate than spiral-CT and PET alone in staging mediastinal lymph node involvement in lung cancer patients, with possible implications for their prognosis and therapy.

Aged↗
PubMed1998

Recovery of neglect after right hemispheric damage: H2(15)O positron emission tomographic activation study.

BACKGROUND: The neural correlates of recovery of unilateral neglect (ULN), as well as of other consequences of focal brain damage, are largely unknown. Functional neuroimaging methods (in particular, positron emission tomography [PET]) can be applied to the in vivo study of recovery mechanisms in neurologic patients. OBJECTIVE: To evaluate the functional cerebral correlates of recovery from ULN in patients with right-sided lesions, with the use of a PET activation paradigm. METHODS: Study of 3 patients with cerebrovascular lesions that involved corticosubcortical (patient 1) or subcortical (patients 2 and 3) areas of the right hemisphere. Unilateral neglect was tested twice, before and after completion of a 2-month rehabilitation program, after which all 3 patients showed considerable improvement. Similarly, 2 PET examinations were performed, before and after recovery, during the performance of a visuospatial task requiring the patients to detect and respond to visual targets moving on a computer screen from the right to the left visual hemifield (experimental condition). The cerebral activation was compared with a baseline task in which subjects responded to a black dot flashing in a fixed position of the right hemifield. RESULTS: The brain areas activated by the performance of the visuospatial task before and after recovery were compared. In all 3 patients, the regions notably more active after recovery were almost exclusively found in right-sided cortical areas and largely overlapped with those observed in a group of 4 normal subjects performing the same task. Other areas, which have been shown to be involved in attentional and oculomotor tasks in other PET studies, were also activated in patients with ULN. CONCLUSIONS: The behavioral recovery of ULN in these patients with predominantly subcortical lesions is mainly associated with cerebral activations in cortical regions similar to those observed in normal subjects. There is some evidence of functional reorganization in individual subjects, which involves other areas related to space representation and exploration.

Aged↗
PubMed1998

Preoperative and intraoperative radioimmunodetection of cancer pretargeted by biotinylated monoclonal antibodies.

The in vivo post-targeting of tumor by means of anti-carcinoembryonic-antigen (CEA) monoclonal antibodies (MAbs) and the avidin-biotin three-step system was tested by immunoscintigraphy and radioimmunoguided surgery (RIGS) in six patients with primary or recurrent rectal cancer. The patients were preoperatively injected with 1 mg of FO23C5 (anti-CEA) and/or B72.3 anti-tumor-associated glycoprotein (TAG-72) biotinylated MAb; after 24 hours, 1 mg of avidin was administered, and, after a further 24 hours, biotin labeled to Indium-111 (In111) was injected. Preoperative imaging was obtained by means of a gamma camera, and a portable gamma-detecting probe (Neoprobe 1000) was intraoperatively used to count tumor and surrounding normal tissue. Eight tumor sites were localized in the six patients. Four lesions were identified preoperatively and six intraoperatively with a mean tumor-to-normal-tissue (T/NT) ratio of 1:8. This method allowed preoperative scintigraphy and intraoperative radioimmunodetection to be performed with a single radioactive compound injection of biotin labeled to In111 within few days before surgery.

Adult↗
PubMed1998

The effects of semantic category and knowledge type on lexical-semantic access: a PET study.

Neuropsychological studies of patients with category-specific recognition disorders, as well as PET investigations of semantic category effects in visual recognition tasks, have led some authors to the hypothesis that visual-perceptual knowledge plays a crucial role in the recognition of natural items, such as animals, while functional-associative information is more important for the recognition of man-made tools. To study the cerebral correlates of the retrieval of different types of semantic knowledge about living and nonliving entities, we performed a PET experiment in which normal subjects were required to access visual- and functional-associative information related to visually presented words corresponding to animals and tools. The experimental conditions were the following: (1) Rest. (2) Baseline: letter detection in pseudo-words. (3) Animal, visual knowledge: decide whether the animal has a long or short tail with respect to the body. (4) Animal, associative knowledge: decide whether the animal is typically found in Italy. (5) Tool, visual knowledge: decide whether the object is longer than wider or vice versa. (6) Tool, functional knowledge: decide whether the object is typically used as a kitchen tool. Lexical-semantic access (all lexical conditions pooled) activated the prefrontal cortex on the left and the parietal-occipital junction and posterior cingulate cortex bilaterally. An analysis of the individual experimental conditions in comparison with the nonword baseline showed that accessing visual versus associative knowledge was associated with different activation patterns: predominantly frontal in the case of visual features, temporoparietal for associative knowledge. While the activation patterns involved similar areas for living and nonliving entities, in the case of the latter they were restricted to the left hemisphere. The analysis of main effects confirmed these findings: there were several significant differences in the visual-associative comparison, while category-related differences were less prominent. These findings indicate that the retrieval of different types of knowledge is associated with distinct patterns of brain activation; on the other hand, category-related differences were less evident than in picture matching and naming tasks.

Adult↗
PubMed1998

Hemispheric asymmetries and bimanual asynchrony in left- and right-handers.

It is known that, when both forearms are rotated rhythmically and symmetrically, the dominant hand leads in time by about 25 ms, irrespective of movement speed. Positron emission tomography was used to test the hypothesis that the asynchrony results from a functional hemispheric asymmetry. We found that in normal, adult right-handers portions of the motor and premotor motor areas are more active in the left than in the right hemisphere. The converse pattern was observed in left-handers. The results suggest that at least some components of the neural processing involved in bimanual coordination are carried out only in the hemisphere contralateral to the dominant hand. In particular, between-hands asynchrony may reflect the time for dispatching pace-setting commands to the contralateral hemisphere.

Adult↗
PubMed1998

Differential distribution of striatal [123I]beta-CIT in Parkinson's disease and progressive supranuclear palsy, evaluated with single-photon emission tomography.

Functional imaging of the presynaptic dopaminergic activity using single-photon emission tomography (SPET) and iodine-123 labelled 2-beta-carboxymethoxy-3-beta-(4-iodophenyl)tropane ([123I]beta-CIT) is important for the assessment of disease severity and progression in patients with Parkinson's disease (PD). However, its capability to discriminate between different extrapyramidal disorders has not yet been assessed. The aim of this study was to evaluate the possibility of differentiating patients with PD and with progressive supranuclear palsy (PSP) by means of this method. The distribution of [123I]beta-CIT in the basal ganglia was assessed in six normal subjects, 13 petients with PD and five patients with PSP in whom the disease was mild. SPET images were obtained 24+/-2 h after i.v. injection of the tracer using a brain-dedicated system (CERASPECT). MR and SPET images were co-registered in four normal subjects and used to define a standard set of 16 circular regions of interest (ROIs) on the slice showing the highest striatal activity. The basal ganglia ROIs corresponded to (1) the head of caudate, (2) a region of transition between the head of caudate and the anterior putamen, (3) the anterior putamen and (4) the posterior putamen. A ratio of specific to non-displaceable striatal uptake was calculated normalising the activity of the basal ganglia ROIs to that of the occipital cortex (V3"). ANOVA revealed a global reduction of V3" in all ROIs of PD and PSP patients compared with normal controls (P<0. 0001). A Mann-Whitney U test showed that the difference between PD and PSP patients was statistically significant for the caudate region only (Z value: 2.6; P<0.01). By subtracting V3" caudate values from those of the putamen, differentiation from PSP was possible in 10/13 PD patients. In conclusion, analysis of [123I]beta-CIT distribution in discrete striatal areas provides information on the relative caudate-putamen damage, with different values being obtained in patients clinically diagnosed as having either PD or PSP.

Aged↗
PubMed1998

Distinct brain loci in deductive versus probabilistic reasoning.

Deductive versus probabilistic inferences are distinguished by normative theories, but it is unknown whether these two forms of reasoning engage similar cerebral loci. To clarify the matter, positron emission tomography was applied during deductive versus probabilistic reasoning tasks, using identical stimuli. Compared to a language comprehension task involving the same stimuli, both probabilistic and deductive reasoning increased regional cerebral blood flow (rCBF) bilaterally in the mesial frontal region and in the cerebellum. In the direct comparison, probabilistic reasoning increased rCBF in left dorsolateral frontal regions, whereas deductive reasoning enhanced rCBF in associative occipital and parietal regions, with a right hemispheric prevalence. The results suggest that reasoning about syllogisms engages distinct brain mechanisms, depending on the intention to evaluate them deductively versus probabilistically.

Adult↗
PubMed1998

The bilingual brain. Proficiency and age of acquisition of the second language.

Functional imaging methods show differences in the pattern of cerebral activation associated with the subject's native language (L1) compared with a second language (L2). In a recent PET investigation on bilingualism we showed that auditory processing of stories in L1 (Italian) engages the temporal lobes and temporoparietal cortex more extensively than L2 (English). However, in that study the Italian subjects learned L2 late and attained a fair, but not an excellent command of this language (low proficiency, late acquisition bilinguals). Thus, the different patterns of activation could be ascribed either to age of acquisition or to proficiency level. In the current study we use a similar paradigm to evaluate the effect of early and late acquisition of L2 in highly proficient bilinguals. We studied a group of Italian-English bilinguals who acquired L2 after the age of 10 years (high proficiency, late acquisition bilinguals) and a group of Spanish-Catalan bilinguals who acquired L2 before the age of 4 years (high proficiency, early acquisition bilinguals). The differing cortical responses we had observed when low proficiency volunteers listened to stories in L1 and L2 were not found in either of the high proficiency groups in this study. Several brain areas, similar to those observed for L1 in low proficiency bilinguals, were activated by L2. These findings suggest that, at least for pairs of L1 and L2 languages that are fairly close, attained proficiency is more important than age of acquisition as a determinant of the cortical representation of L2.

Adult↗
PubMed1998

Regional glucose utilization in infarcted and remote myocardium: its relation to coronary anatomy and perfusion.

We studied the relationship between coronary anatomy, perfusion and metabolism in myocardial segments exhibiting transient and persistent perfusion defects on stress/rest 99Tcm-MIBI single photon emission tomography in 35 patients (31 males, 4 females, mean age 56 +/- 7 years) with a previous myocardial infarction. Quantitative coronary angiography and assessment of myocardial perfusion reserve and glucose metabolism were performed within 1 week of one another. Perfusion was assessed by SPET after the intravenous injection of 740 MBq of 99Tcm-MIBI at rest and after exercise. Regional myocardial glucose metabolism was assessed by position emission tomography at rest (200 MBq of 18F-2-deoxyglucose, FDG) after an overnight fast with no glucose loading. All 35 patients exhibited persistent perfusion defects consistent with the clinically identified infarct site, and 27 (77%) also showed various degrees of within-infarct FDG uptake; 11 patients developed exercise-induced transient perfusion defects within, or in the vicinity of, 15 infarct segments and resting FDG uptake was present in 10 of these segments (67%). Five patients also showed exercise-induced transient perfusion defects in nine segments remote from the site of infarct: resting FDG uptake was present in six of these regions (67%). Finally, nine patients had increased glucose uptake in non-infarcted regions not showing transient perfusion defects upon exercise testing and perfused by coronary arteries with only minor irregularities. Our results confirm the presence of viable tissue in a large proportion of infarct sites. Moreover, FDG uptake can be seen in regions perfused by coronary arteries showing minor irregularities, not necessarily resulting in detectable transient perfusion defects on a MIBI stress scan. Since the clinical significance of such findings is not clear, further studies should be conducted to assess the long-term evolution of perfusion, function and metabolism in non-revascularized patients of those remote areas which are apparently normally perfused, but show abnormal fasting FDG uptake after myocardial infarction. Such studies may have important implications for the management of post-infarct patients, as the preservation of coronary vasodilator reserve and myocardial metabolism in remote myocardium may be seen as an additional goal in the treatment of such patients.

Blood Glucose↗
PubMed1998

Imaging of the buffering effect of insulin antibodies in the autoimmune hypoglycemic syndrome.

Insulin autoimmune hypoglycemia is characterized by recurrent hypoglycemia and high levels of immunoreactive insulin in the presence of insulin autoantibodies. The mechanisms inducing hypoglycemia are largely unknown. An [123I]insulin scintigraphic scanning was performed to directly demonstrate the effect of antibodies on insulin biodistribution in one patient with this syndrome both before and after treatment. The patient had insulin autoantibodies IgG3 lambda, which had a single site dissociation constant (Kd = 10(-7) mol/L, by Scatchard analysis), a very fast dissociation rate of immune complexes, and a very rapid association of [125I]insulin. Insulin receptors on red blood cells were down-regulated. The [123I]insulin scintigraphic study imaged the buffering effect of antibodies on insulin bioavailability. [123I]Insulin was not removed from the blood, and no liver or kidney uptake of the hormone occurred. The frequency and severity of hypoglycemic episodes required treatment. Insulin antibody levels decreased and [123I]insulin biodistribution improved after treatment with plasmapheresis and prednisone. Improved hormone bioavailability was further evidenced by the reduction in the hypoglycemic delay after i.v. insulin from 90 min before any treatment to 60 min after plasmapheresis and 30 min after steroid administration. Glucose tolerance was normal after treatment. Plasmapheresis followed by steroid treatment can lower the insulin antibody concentration, abolish severe hypoglycemia, and improve insulin biodistribution and glucose tolerance in insulin autoimmune hypoglycemia.

Autoantibodies↗
PubMed1997

Functional heterogeneity of left inferior frontal cortex as revealed by fMRI.

Using functional magnetic resonance imaging (fMRI), we mapped brain activity in six normal volunteers during two silent verbal fluency tasks, one with a phonemic (letter) cue and one with a semantic (category) cue. In comparison with resting state, both tasks activated the anterior triangular portion of the left inferior frontal gyrus (IFG or F3, for third frontal gyrus) and the left thalamus. There were also areas activated in one task but not in the other: the posterior opercular portion of the left IFG for phonemic fluency, and the left retrosplenial region for semantic fluency. Our findings concur with normal psychophysical data and neuropsychological observations to suggest the recruitment of two overlapping but dissociable systems for the two tasks, and demonstrate functional heterogeneity within the left IFG (Broca's area), where the opercular portion is responsible for obtaining access to words through a phonemic/articulatory route.

Adult↗
PubMed1997

A PET follow-up study of recovery after stroke in acute aphasics.

The neural correlates of recovery from aphasia are largely unknown. Several different sources of evidence, from clinical studies to neurophysiological investigations, have suggested a contribution of the contralateral, undamaged hemisphere in recovery from aphasia. Eight patients with unilateral left hemispheric stroke were submitted to a standard language examination and to a [18F]FDG PET study in the recent phase after stroke (within 2 weeks) and 6 months later. All patients had a substantial recovery of specific aspects of language functions at the follow-up. Analysis of regional glucose metabolism showed hypometabolism in structurally unaffected regions both in the left and in the right hemisphere (diaschisis), in the acute stage. Glucose metabolism increased significantly on both sides in all patients at the second PET study. Regional analysis showed significant positive correlations between changes in metabolic values in several cortical and subcortical regions in the right hemisphere and changes in language performance at follow-up. The present findings show that an extensive, bihemispheric depression of metabolism is found in the acute stage after stroke in aphasic patients. Language recovery in the first months after aphasia onset is associated with regression of functional depression (diaschisis) in structurally unaffected regions, in particular in the right hemisphere.

Acute Disease↗
PubMed1997

Visuomotor transformations for reaching to memorized targets: a PET study.

Positron emission tomography (PET) was used to identify cortical and subcortical regions involved in the control of reaching to visual targets. Regional cerebral blood flow (rCBF) was measured in eight healthy subjects using H2(15)O PET during the performance of three different tasks. All tasks required central fixation while a 400-ms target was flashed every 5 s at a random location around a virtual circle centered on the fixation target. Additional instructions differed according to the task: (i) visual detection of the target without overt responses; (ii) immediate pointing to the most recent target in the sequence, and (iii) pointing to the previous target in the sequence. By design, the two motor tasks differed in the cognitive processing required. In each trial of immediate pointing, the spatial location of only the most recent target needed to be processed. In each trial of pointing to the previous, instead, while the most recent target was stored in memory for the movement of the next trial, the previous target had to be retrieved from memory to direct the current movement. Limb trajectories were comparable between the two motor tasks in terms of most spatiotemporal parameters examined. Significant rCBF increases were identified using analysis of covariance and t statistics. Compared with visual detection there was activation of primary sensorimotor cortex, ventrolateral precentral gyrus, inferior frontal gyrus in the opercular region, supramarginal gyrus, and middle occipital gyrus, all these sites in the hemisphere (left) contralateral to the moving limb, and cerebellar vermis, during both immediate pointing and pointing to the previous. During immediate pointing there was additional activation of left inferior parietal lobule close to the intraparietal sulcus, and when compared with pointing to the previous, dorsolateral prefrontal cortex bilaterally. During pointing to the previous, instead, there was additional activation of supplementary motor cortex, anterior and midcingulate, and inferior occipital gyrus in the left hemisphere; superior parietal lobule, supramarginal gyrus, and posterior hippocampus in the right hemisphere; lingual gyri and cerebellar hemispheres bilaterally; anterior thalamus; and pulvinar. The activation of two partially distinct cerebral networks in these two motor tasks reflects the different nature of signal processing involved. In particular, the specific activation of intraparietal sulcus and prefrontal cortex in immediate pointing appears characteristic of a network for visuospatial working memory. By contrast, the corticolimbic network engaged in pointing to the previous could mediate spatial attention and the sequence of encoding, recording, and decoding of spatial memories required by a dual task with two competing targets.

Adult↗
PubMed1997

Matching a computerized brain atlas to multimodal medical images.

A method for matching a digital brain anatomical atlas to multimodal medical images (MRI, PET, and SPET) was implemented. The digital atlas was derived from anatomical templates of the brain, cut according to the orbitomeatal orientation. The atlas consists of a set of contiguous slices schematically describing the brain as anatomical contours and of a set of regions of interest (ROIs) classifying the brain into functionally homogeneous areas. The matching procedure includes (a) an edge detection method for the extraction of anatomical contours and (b) a warping algorithm based on contour matching to fit the atlas to the individual brain anatomy, as described by MRI. Once the atlas is matched to MRI, the associated templates of ROI can be overlapped with functional PET/SPET studies, individually registered to MRI. The method was tested on MRI studies. The efficacy of the warping algorithm in overlapping atlas and MRI contours was assessed by calculating for each slice an index representing the extent of overlapping (I). Values of I in the range 0.8-0.9 were found (I = 1 complete overlapping). Local accuracy was also verified by comparing the position of correspondent anatomical ROI in the atlas and MRI images before and after warping. The atlas-matching procedure was applied to representative MRI/PET clinical images for an objective regional analysis of functional data.

Algorithms↗