Biomedical subjects

M T De Cristofaro

Publications and source records attributed to M T De Cristofaro.

16 recordsLinked to original sources

PubMed2000

Use of technetium-99m hexamethylpropylene amine oxime SPET for the study of cerebral blood flow reactivity after acetazolamide infusion in patients with Behçet's disease.

The purpose of this study was to characterise the nature of the baseline perfusion defects found in patients with Behçet's disease using hexamethylpropylene amine oxime single-photon emission tomography in conjunction with acetazolamide test (Acz SPET). Eleven patients underwent both baseline and Acz SPET. Regions of interest (ROIs) were drawn on the areas with decreased perfusion (D-ROI) and, in the same section, on areas with normal perfusion (N-ROI). The ROIs were then repositioned on the corresponding section on Acz SPET. The mean ROI counts were then transformed into a perfusion index value (PIV) with reference to the global brain counts. In total we found 24 D-ROIs (17 in the cortical and 7 in subcortical grey matter). The influence of Acz infusion was selectively registered in the D-ROIs, where PIVs changed from 1.23+/-0.17 (baseline SPET) to 1.63+/-0.23 (Acz SPET) (P<0.001). No significant difference was seen in the N-ROIs (1.46+/-0.21 and 1.40+/-0.17, respectively, on baseline SPET and Acz SPET). Our results demonstrate that Acz infusion increases the regional cerebral blood flow within baseline grey matter perfusion defects. This finding suggests that baseline perfusion abnormalities could reflect a disconnection rather than local vasculitic involvement.

Acetazolamide↗

PubMed1998

Regional cerebral blood flow in juvenile systemic lupus erythematosus: a prospective SPECT study. Single photon emission computed tomography.

OBJECTIVE: Using single photon emission computed tomography (SPECT) we evaluated the presence and evolution of changes in brain perfusion in juvenile systemic lupus erythematosus (JSLE). METHODS: SPECT was performed in 14 patients with active JSLE divided in 2 groups: the first included 7 patients without central nervous system (CNS) involvement and the second 7 patients with minor neuropsychiatric symptoms (headache, reactive depression, cognitive impairment, mood swing). SPECT findings were compared to seroimmunological and magnetic resonance imaging (MRI) data. After 6 month followup, a second SPECT scan was performed in 12 of 14 patients. RESULTS: At baseline, SPECT showed perfusion defects in 2 patients without neuropsychiatric symptoms and in 5 patients with CNS involvement. In one of the 7 patients with altered SPECT, MRI showed focal hyperintensities. MRI alterations were observed in another patient who had a normal SPECT scan. Cortical atrophy was present in 5 of 14 patients. Correlation between neuropsychiatric manifestations and SPECT findings was not clearly evident because the major part of JSLE patients with CNS involvement and with SPECT alterations had multiple symptoms, but showed focal hypoperfusion on SPECT imaging. No significant association was found between seroimmunological data and SPECT findings. At followup, improvement of perfusion alterations was observed in 6 of 7 patients with altered SPECT and, in 3 of them, findings might be attributed to changes in steroid treatment. CONCLUSION: Perfusion abnormalities in SLE may represent reversible lesions or subclinical CNS involvement. Moreover, SPECT imaging appears to be useful in detecting and monitoring CNS involvement in SLE.

Adolescent↗

PubMed1997

Possible pathogenetic role of activated platelets in the primary antiphospholipid syndrome involving the central nervous system.

Neurological disorders occurring in the primary antiphospholipid syndrome (neuro-PAPS) have not yet been completely understood. Platelet activation has been suggested to play a crucial role in the pathogenesis of hemostatic disorders in the antiphospholipid syndrome, but no association with neuro-PAPS has been investigated so far. Therefore, we investigated 16 patients with PAPS by flow cytometry in the presence of circulating activated platelets as defined by the surface expression of activation-dependent glycoprotein CD62. In addition, the relationship among activated platelets and anticardiolipin antibodies (aCL) was evaluated. Compared to normal subjects CD62 was found significantly increased in these patients. Furthermore, a significantly increased percentage of CD62-positive platelets was found in the neuro-PAPS group (nine patients) compared to the non-neuro-PAPS patients (seven subjects). On the contrary, no significant difference was found between the two groups with regard to aCL IgG and platelet number. Furthermore, within the neuro-PAPS group, no difference was evidenced, in the CD62-positive platelet percentage, between the four subjects with thrombocytopenia and the five with the normal blood platelet count. Similarly, neuro-PAPS subjects with previous peripheral arterial and/or venous thrombosis did not show a significantly more elevated level of CD62-positive platelets. Finally, a linear correlation was found between the aCL IgG level and the CD62-positive platelet percentage in all the patients and, more significantly, in the neuro-PAPS group, but not within the non-neuro-PAPS patients. Our data demonstrate that circulating activated platelets are detectable by flow cytometry in the majority of PAPS patients and suggest the existence of a relationship among activated platelets, aCL, and neurological disease that patients affected by PAPS might undergo.

Adult↗

PubMed1997

High-performance computing and networking as tools for accurate emission computed tomography reconstruction.

It is well known that the quantitative potential of emission computed tomography (ECT) relies on the ability to compensate for resolution, attenuation and scatter effects. Reconstruction algorithms which are able to take these effects into account are highly demanding in terms of computing resources. The reported work aimed to investigate the use of a parallel high-performance computing platform for ECT reconstruction taking into account an accurate model of the acquisition of single-photon emission tomographic (SPET) data. An iterative algorithm with an accurate model of the variable system response was ported on the MIMD (Multiple Instruction Multiple Data) parallel architecture of a 64-node Cray T3D massively parallel computer. The system was organized to make it easily accessible even from low-cost PC-based workstations through standard TCP/IP networking. A complete brain study of 30 (64x64) slices could be reconstructed from a set of 90 (64x64) projections with ten iterations of the conjugate gradients algorithm in 9 s, corresponding to an actual speed-up factor of 135. This work demonstrated the possibility of exploiting remote high-performance computing and networking resources from hospital sites by means of low-cost workstations using standard communication protocols without particular problems for routine use. The achievable speed-up factors allow the assessment of the clinical benefit of advanced reconstruction techniques which require a heavy computational burden for the compensation effects such as variable spatial resolution, scatter and attenuation. The possibility of using the same software on the same hardware platform with data acquired in different laboratories with various kinds of SPET instrumentation is appealing for software quality control and for the evaluation of the clinical impact of the reconstruction methods.

Algorithms↗

PubMed1994

Quantitative comparison between 99mTc-HMPAO and 99mTc-ECD: measurement of arterial input and brain retention.

This report describes a comparative study between technetium-99m ethyl cysteinate dimer (ECD) and 99mTc-hexamethylpropylene amine oxime (HMPAO) in five neurological patients. The conversion kinetics of the tracers in the blood from forms capable of diffusion across the blood-brain barrier to non-diffusible forms were studied by arterial sampling and rapid octanol extraction. We observed that HMPAO has a faster conversion rate in the blood but that the fraction of the injected dose available for brain extraction is higher than in the case of ECD. Regional brain concentrations of the tracers were measured with single-photon emission tomography (SPET) 35 min and 60 min after the injection and remained stable within this interval. On the basis of the measurements of the arterial input and of SPET brain concentrations of the tracers, the regional steady-state influx constants (Ki in ml/min/g) were determined for several brain regions. In the grey matter the Ki values were (mean +/- SD) 0.32 +/- 0.03 and 0.35 +/- 0.04 for HMPAO and ECD, respectively; in the white matter the values were 0.23 +/- 0.01 and 0.23 +/- 0.02, respectively. The Ki values of the two tracers in corresponding regions were closely correlated (P < 0.001). The correspondence of the Ki values of ECD and HMPAO demonstrates that ECD can also be considered a tracer that may be used for quantitative measurements of brain perfusion.

Aged↗

PubMed1994

Quantitation of brain perfusion with 99mTc-bicisate and single SPECT scan: comparison with microsphere measurements.

This study describes and validates in a preliminary manner a method to measure the steady-state influx constant (Ki) of 99mTc-bicisate with one single photon emission computed tomography (SPECT) scan. The method is based on the analysis of the arterial concentration of the radioactivity. The results of this quantitation procedure were compared with regional CBF (rCBF) measurements made using 99mTc-microspheres (MI). Two quantitative indexes of perfusion, fractional brain uptake (FBU) and normalized (with cerebellum) brain uptake (NBU), were also evaluated. Two SPECT studies were performed on seven cardiovascular patients who had no signs of neurological disease. In the first of these, 99mTc-bicisate was used, while in the other, which was performed 2 days later, MI were injected into the left heart ventricle. The values of the FBU, NBU, and Ki of 99mTc-bicisate were calculated in several gray and white matter brain regions of interest (ROIs) and compared with the rCBF values measured with MI in coupled ROIs. Mean FBU values were 0.00008 +/- 0.00002 and 0.00004 +/- 0.00001 in the gray and the white matter, respectively. Mean NBU values were 0.99 +/- 0.04 and 0.54 +/- 0.05, mean Ki values were 0.36 +/- 0.06 and 0.19 +/- 0.03 ml g-1 min-1 and mean rCBF values were 0.51 +/- 0.04 and 0.27 +/- 0.04 ml g-1 min-1 in gray and white matter, respectively. Analysis of variance of the regression gave different F values for the regressions with rCBF of FBU (F = 19, n = 126), NBU (F = 289, n = 112), and Ki (F = 117, n = 126).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1993

Brain perfusion abnormalities in drug-naive, lactate-sensitive panic patients: a SPECT study.

Using single photon emission computed tomography (SPECT) and 99mTc-hexamethylpropyleneamine oxime (HM-PAO), we assessed brain perfusion in seven patients with panic disorder (PD) and in five age-matched normal subjects at rest. No patient had ever received drug treatment for panic. All patients were sensitive to lactate-induced panic. Computed tomography (CT) scans did not reveal any morphological abnormalities of the brain in any of the PD patients. Two indices of cerebral perfusion were calculated; these demonstrated alterations of brain perfusion in the PD group. Significant right-left asymmetry was found in the inferior frontal cortex of the PD patients. We also observed a significant blood flow increase in the left occipital cortex and a significant decrease in the hippocampal regions bilaterally. Although the changes seen in the inferior frontal cortex and occipital cortex may be related to anxiety experienced by the patients during the study, the pattern of hippocampal hypoperfusion appears to be characteristic of panic disorder. This suggests that the hippocampal structures may play an important role in the pathophysiology of panic disorder.

Adult↗

PubMed1992

Merkel cell carcinoma and iodine-131 metaiodobenzylguanidine scan.

Two cases of Merkel cell carcinoma, a neuroendocrine neoplasia of the skin, investigated with iodine-131 metaiodobenzylguanidine (131I-mIBG) scintigraphy, are reported. Uptake in the tumor was evident only in 1 case. The possible diagnostic and therapeutic role of 131I-mIBG in patients with this rare neoplasm is discussed.

3-Iodobenzylguanidine↗

PubMed1991

An analysis of the arterial input curve for technetium-99m-HMPAO: quantification of rCBF using single-photon emission computed tomography.

Arterial radioactivity content after the intravenous administration of HMPAO in seven human subjects was analyzed. Arterial sampling of 99mTc-HMPAO was performed on each subject over a 25-min period postinjection. The lipophilic fraction of the tracer present in the blood was rapidly extracted with octanol. An analysis of the time course of the extracted and nonextracted octanol fractions was performed in order to calculate the arterial input of the tracer available for brain extraction. HMPAO net regional brain clearances were then calculated and compared with rCBF values obtained in the same patients using 99mTc-microspheres injected into the left ventricle of the heart. HMPAO brain clearances were 0.41 +/- 0.01 and 0.27 +/- 0.01 ml/min/g for grey and white matter, respectively. Linear regression analysis was performed and the following result was obtained: clearance (HMPAO) = 0.07 + 0.43 . rCBF with a high significance (p less than 0.001). This equation can be used for the transformation of HMPAO clearances into rCBF values. Our study demonstrates that by using HMPAO and SPECT it is possible to obtain a quantitative estimate of rCBF in humans.

Adult↗

PubMed1990

Evaluation of technetium 99m cyclobutylpropylene amine oxime as a potential brain perfusion imaging agent for SPET.

Technetium 99m d,l-cyclobutylpropylene amine oxime (99mTc-CBPAO) has been developed as a brain-imaging agent for single photon emission tomography (SPET). 99mTc-CBPAO can be prepared using a simple labelling procedure suitable for routine clinical use. It has a high in vitro stability, as has been demonstrated by high-pressure liquid chromatography (HPLC) analysis. This shows that 3 h after labelling, less than 5% of the primary lipophilic complex which is capable of crossing the blood-brain barrier (BBB) converts to a secondary hydrophilic complex. Brain uptake (% dose/g wet tissue) of 99mTc-CBPAO, determined at 5 and 30 min after injection in two groups of six adult male Sprague-Dawley rats, was found to be 0.74 +/- 0.06 and 0.73 +/- 0.13 (mean +/- SD), respectively. These values are not significantly different from those obtained repeating the experiment with 99mTc-labelled hexamethylpropylene amine oxime (99mTc-HMPAO) (0.72 +/- 0.15 at 5 min and 0.88 +/- 0.24 at 30 min after injection). Since the rat brain uptake of 99mTc-CBPAO remained unchanged for a period of time suitable for tomographic study, the comparison of the two tracers was extended to two groups of ten patients. The latter were affected by neurological and psychiatric disorders and were studied with SPET. Human brain uptake (% dose/cc cortical grey matter) of 99mTc-CBPAO and 99mTc-HMPAO were 3.04 +/- 0.57 and 4.22 +/- 0.46 (mean x 10(-3) +/- SD x 10(-3), respectively, with a 32% significant difference. In two other groups of five patients, the first transit time-activity curves of the two tracers were compared.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

A brain phantom for studying contrast recovery in emission computerized tomography.

A brain phantom is described that is characterized by a high anatomical definition and by the possibility of varying the internal contrast with the use of a single radioactive solution. The experimental work was done with a single-photon emission computerized tomographic (SPET) rotating camera. The phantom was used to study the contrast recovery of both the filtered back-projection and an iterative reconstruction algorithm. Moreover, it was also used to find a cross-calibration factor between activity concentrations in the SPET slices and an external reference.

Algorithms↗

PubMed1990

Subcortical arteriosclerotic encephalopathy: single photon emission computed tomography-magnetic resonance imaging correlation.

Regional cerebral blood flow was studied using 99mTc-HM-PAO and single photon emission computed tomography (SPECT) in five healthy subjects and in eight patients with clinical and computed tomography (CT) features of subcortical arteriosclerotic encephalopathy. All the patients and controls underwent magnetic resonance imaging (MRI). Circumscribed cortical hypoperfusion was observed in three patients, and in one case there was no evidence of cortical or sulcal alterations on MRI. In all the patients, a reduction of the white matter perfusion was found in periventricular and/or supraventricular regions. This pattern was substantially correlated with the typical white matter hyperintensities shown by MRI scans. These findings support the hypothesis that white matter hypoperfusion is the most prominent functional abnormality in subcortical arteriosclerotic encephalopathy.

Aged↗

PubMed1988

[Study of myocardial perfusion at rest using technetium Tc 99m methoxy-isobutylisonitrile: comparison with labeled microspheres and thallium 201].

In order to evaluate the potential usefulness of 99m technetium (Tc)-methoxy-isobutyl-isonitrile (MIBI) as a myocardial perfusion tracer in man, its myocardial distribution at rest was compared with that of 201thallium (TI). Perfusion images obtained with 99mTc-labelled microspheres, whose myocardial distribution is exclusively coronary flow dependent, were used as reference. The study was performed on twelve patients (10 males and 2 females, mean age 55.4 +/- 6.4) with suspected effort angina and without a history of previous myocardial infarction. In the space of two weeks patients underwent rest and exercise 99mTc-MIBI myocardial scintigraphy, exercise-redistribution 201TI myocardial scintigraphy, 99mTc-labelled microsphere scintigraphy after microsphere injection in the left ventricle at rest during catheterization before performing left ventriculography and coronary angiography. The comparison with microsphere distribution was limited to rest 99mTc-MIBI scintigraphy and redistribution 201TI images. Single photon emission tomography (SPECT) was employed. SPECT was performed using a double-head Rotacamera with a 360 degrees rotation arc. Ninety projections of 20 seconds each were acquired; subsequently image reconstruction was performed using an iterative algorithm. To evaluate regional perfusion the left ventricular wall was divided into 18 segments; the uptake pattern of each segment was graduated according to a qualitative score (0: severe defect; 1: moderate defect; 2: normal uptake). The quality of tomographic myocardial 99mTc-MIBI and 99mTc-microspheres images was higher than that of 201TI tomograms in account of the different physical characteristics of the two radionuclides.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1986

Usefulness of the TRH test in the management of patients with differentiated thyroid cancer.

Thirty patients thyroidectomized for differentiated thyroid cancer were studied. Serum TSH was assayed in basal conditions and after TRH stimulation, while patients were in suppressive therapy with thyroid hormones. The basal TSH was normal in all the patients and less than 2 microU/ml in 20 patients. The TRH test was negative (no TSH response) in 27 patients and in all the cases with the basal TSH lower than 2 microU/ml.

Adult↗

PubMedDate not supplied

[MRI and HM-PAO SPECT in 20 patients with drug-resistant partial epilepsy].

Twenty consecutive patients with chronic partial seizures with onset before twenty years of age were investigated by means of 0.5 T MRI (20) and HM-PAO (19) in order to identify focal alterations amenable to surgical therapy. MRI evidentiated parenchymal lesions in 7 patients. Findings consistent with unilateral medial temporal sclerosis and cortico-subcortical parietal scars were found in two patients each. Small solid nodular lesions in the temporal lobe were observed in two patients. These and one additional patient with nodular partially cystic lesions in temporal lobe were administered a paramagnetic contrast agent (Gadolinium DPA) intravenously. In one case a contrast enhancement was observed. Histologic examination post surgery revealed a low grade glioma in one patient. HM-PAO SPECT examination showed area of abnormal captation in 9 of 19 patients. Aspects of EEG correlation with the MRI and SPECT findings are discussed. Our data supported the usefulness of magnetic resonance and SPECT imaging in the completion of pre-surgical assessment in this kind of patients.

Adult↗

PubMedDate not supplied

MRI and SPECT investigations of the CNS in SLE patients.

Twenty-two SLE patients were examined with Magnetic Resonance Imaging (MRI) and Single Photon Emission Computed Tomography (SPECT). Multifocal areas of cerebral blood flow (CBF) defects were found in 81.8% of the patients. These alterations were present in patients with severe neurological disorders, in those with neuropsychiatric symptoms only, and also in asymptomatic cases. Anticardiolipin antibodies (aCL) were detected in all patients, but no correlation was found between serum aCL positivity and neurological involvement. The high incidence of cerebral blood flow disorders found in asymptomatic patients, and their poor correlation with the MRI alterations suggest a primary defect of CBF in these patients.

Adolescent↗