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Biomedical subjects

M Quarantelli

Publications and source records attributed to M Quarantelli.

At least 19 recordsLinked to original sources
PubMed2006

Characteristics, associations and outcome of partial agenesis of the corpus callosum in the fetus.

OBJECTIVES: To report, in a population of fetuses diagnosed with partial agenesis of the corpus callosum (PACC), the sonographic characterization, incidence of cerebral, extracerebral and chromosomal anomalies, and outcome. In addition, in some of our cases a comparison was made between findings on ultrasound and fetal magnetic resonance imaging (MRI). METHODS: This was a retrospective study of all cases of PACC seen at two referral centers for prenatal diagnosis of congenital anomalies over a 10-year period. The following variables were assessed: indication for referral, additional cerebral and extracerebral malformations, chromosomal abnormalities, and pregnancy and fetal/neonatal outcome. RESULTS: Among 54 cases of fetal agenesis of the corpus callosum detected in the referral centers during the observation period, PACC was diagnosed at prenatal sonography in 20 cases and confirmed at pre/postnatal MRI and necropsy examinations in 19 cases (35%). These 19 constituted the study group. The diagnosis was made in the sagittal planes and in 12 cases it was made prior to 24 weeks. In most cases the indication for referral was the presence of indirect signs of callosal anomalies, such as colpocephaly. In 10 cases PACC occurred in association with other anomalies and in nine it was isolated. MRI was particularly useful for demonstrating some additional cerebral anomalies such as late sulcation, migrational pathological conditions and heterotopia. Regarding pregnancy outcome, of those diagnosed before 24 weeks which had associated anomalies, all except two were terminated. Of the nine cases with isolated PACC, all were liveborn. Follow-up was available in eight, and two of these (25%) showed evidence of significant developmental delay. In our series the outcome of isolated PACC was not better than that of complete agenesis of the corpus callosum reported in other series. CONCLUSIONS: PACC can be diagnosed reliably and characterized in prenatal life. The sonographic sign present in most cases is colpocephaly. Prenatal MRI can be performed to confirm the diagnosis. It is particularly useful to demonstrate some additional cerebral anomalies such as late sulcation, migrational pathological conditions and heterotopia. The relatively poor survival rate is due to the high rate of terminations and associated major anomalies.

Abnormalities, Multiple↗
PubMed2006

Mapping the relative contribution of gray matter activity vs. volume in brain PET: a new approach.

Interpretation of brain positron emission tomography (PET) in terms of function vs. structure is ambiguous owing to the partial volume effect (PVE). Therefore, observed differences in tracer distribution could reflect differences in either activity or volume, a problem that applies principally to gray matter (GM) since white matter (WM) virtually always has uniform activity. To assess the contribution of GM volume vs. activity, we implemented a method to directly compare PET images with underlying structure, and applied it to resting-state (18)Fluoro-deoxy-glucose-PET (FDG) of healthy subjects. Methods. Average GM and WM PVE-corrected mean FDG uptake values were applied onto co-registered segmented magnetic resonance imaging data sets to generate a "virtual PET" in which activity is proportional to GM volume and resolution set to that of PET. The raw PET and virtual PET values were then compared across the sample of subjects, first voxel-wise to detect clusters with significant activity-volume mismatch, and second within regions-of-interest (ROI) to quantify mismatches between unsmoothed voxel values. Results. Relative to volume, there was significant hyperactivity of most GM structures of the dorsal brain-except the thalamus-and significant hypoactivity of the temporal lobe, hippocampal region, and cerebellum, consistent across the voxel- and ROI-based analyses. Conclusion. As applied to normals, our method documented the expected contribution of functional activity independently of local differences in GM volume in the normal pattern of FDG uptake, and disclosed marked heterogeneities in functional activity per unit GM volume among structures. This generic method should find applications in pathological states as well as for other PET and SPECT radiotracers.

Brain↗
PubMed2005

Grey matter loss in relapsing-remitting multiple sclerosis: a voxel-based morphometry study.

Global grey matter (GM) loss has been reported in multiple sclerosis (MS). We addressed the question of if and where GM loss is localized by means of optimized voxel-based morphometry, applied to MRI studies of 51 patients with clinically defined relapsing-remitting MS and 34 age-matched normal subjects, segmented into normal and abnormal brain tissues using a multiparametric approach. Segmented GM volumes were subsequently compared on a voxel-by-voxel basis to highlight regions of relative GM loss (P < 0.05, corrected for multiple comparisons at AnCova). Additionally, localized differences in brain asymmetry between the MS and the control groups were assessed by comparing on a voxel-by-voxel basis maps of GM differences between the two hemispheres (P < 0.05 corrected for multiple comparisons). In MS patients, GM volume was significantly decreased at the level of the left fronto-temporal cortex and precuneus, as well as of anterior cingulate gyrus and of caudate nuclei bilaterally. The only cortical region of significant GM loss in the right hemisphere was located in the postcentral area. Furthermore, GM loss regions were colocalized with increased GM asymmetries (Left < Right) in MS, confirming a preferential left-sided GM loss. Caudate atrophy correlated with lesion load, while no correlation between cortical regional GM loss and disease duration, clinical status or lesion load emerged. Our findings suggest that in RR-MS cortical GM reduction preferentially involves left fronto-temporal structures and deep GM, the latter correlating preferentially to global lesion load.

Adult↗
PubMed2005

Brain atrophy and lesion load in a large population of patients with multiple sclerosis.

OBJECTIVE: To measure white matter (WM) and gray matter (GM) atrophy and lesion load in a large population of patients with multiple sclerosis (MS) using a fully automated, operator-independent, multiparametric segmentation method. METHODS: The study population consisted of 597 patients with MS and 104 control subjects. The MRI parameters were abnormal WM fraction (AWM-f), global WM-f (gWM-f), and GM fraction (GM-f). RESULTS: Significant differences between patients with MS and control subjects included higher AWM-f and reduced gWM-f and GM-f. MRI data showed significant differences between patients with relapsing-remitting and secondary progressive forms of MS. Significant correlations between MRI parameters and between MRI and clinical data were found. CONCLUSIONS: Patients with multiple sclerosis have significant atrophy of both white matter (WM) and gray matter (GM); secondary progressive patients have significantly more atrophy of both WM and GM than do relapsing-remitting patients and a significantly higher lesion load (abnormal WM fraction); lesion load is related to both WM and even more to GM atrophy; lesion load and WM and GM atrophy are significantly related to Expanded Disability Status Scale score and age at onset (suggesting that the younger the age at disease onset, the worse the lesion load and brain atrophy); and GM atrophy is the most significant MRI variable in determining the final disability.

Adolescent↗
PubMed2001

Assessment of scanner performance and normalization of estimated relaxation rate values.

The purpose of this study was to develop and test a method for the assessment of Magnetic Resonance (MR) scanner performance suitable for routine brain MR studies and for normalization of calculated relaxation times. We hypothesized that regular monitoring of machine performance changes could provide a helpful normalization tool for calculating tissue MR parameters, thus contributing to support their use for longitudinal and comparative studies of both normal and diseased tissues. The method is based on the acquisition of phantom images during routine brain studies with standard spin-echo sequences. MR phantom and brain tissue parameters were used to assess the influence of machine related changes on relaxation parameter estimates. Experimental results showed that scanner performance may affect relaxation rate estimates. Phantom and in vivo results indicate that the correction method yields a reduction in variability of estimated phantom R1 values up to 29% and of R1 for different brain structures up to 17%. These findings support the validity of using brain coil phantoms for routine system monitoring and correction of tissue relaxation rates.

Brain↗
PubMed2000

Measurement of global brain atrophy in Alzheimer's disease with unsupervised segmentation of spin-echo MRI studies.

In 16 patients with probable Alzheimer's disease (AD; NINDS criteria, age range 56-78 years), gray matter (GM), white matter (WM), and cerebrospinal fluid (CSF) absolute and fractional volumes were measured with an unsupervised multiparametric post-processing segmentation method based on estimates of relaxation rates R1, R2 (R1 = 1/T1; R2 = 1/T2) and proton density [N(H)] from conventional spin-echo studies (Alfano et al. Magn. Reson. Med. 1997;37:84-93). Global brain atrophy, and GM and WM fractions significantly correlated with Mini-Mental Status Examination and Blessed Dementia Scale scores. Compared with normals, brain compartments in AD patients showed decreased GM (-6.84 +/- 1.58%) and WM fractions (-9.79 +/- 2.47%) and increased CSF fractions (+58.80 +/- 10.37%). Changes were more evident in early-onset AD patients. In AD, measurement of global brain atrophy obtained by a computerized procedure based on routine magnetic resonance studies could complement the information provided by neuropsychological tests for the assessment of disease severity.

Aged↗
PubMed2000

Automated segmentation and measurement of global white matter lesion volume in patients with multiple sclerosis.

A fully automated magnetic resonance (MR) segmentation method for identification and volume measurement of demyelinated white matter has been developed. Spin-echo MR brain scans were performed in 38 patients with multiple sclerosis (MS) and in 46 healthy subjects. Segmentation of normal tissues and white matter lesions (WML) was obtained, based on their relaxation rates and proton density maps. For WML identification, additional criteria included three-dimensional (3D) lesion shape and surrounding tissue composition. Segmented images were generated, and normal brain tissues and WML volumes were obtained. Sensitivity, specificity, and reproducibility of the method were calculated, using the WML identified by two neuroradiologists as the gold standard. The average volume of "abnormal" white matter in normal subjects (false positive) was 0.11 ml (range 0-0.59 ml). In MS patients the average WML volume was 31.0 ml (range 1.1-132.5 ml), with a sensitivity of 87.3%. In the reproducibility study, the mean SD of WML volumes was 2.9 ml. The procedure appears suitable for monitoring disease changes over time. J. Magn. Reson. Imaging 2000;12:799-807.

Adult↗
PubMed1999

Frequency encoding for simultaneous display of multimodality images.

UNLABELLED: An original method for simultaneous display of functional and anatomic images, based on frequency encoding (FE), merges color PET with T1-weighted MR brain images, and grayscale PET with multispectral color MR images. A comparison with two other methods reported in the literature for image fusion (averaging and intensity modulation techniques) was performed. METHODS: For FE, the Fourier transform of the merged image was obtained summing the low frequencies of the PET image and the high frequencies of the MR image. For image averaging, the merged image was obtained as a weighted average of the intensities of the two images to be merged. For intensity modulation, the red, green and blue components of the color image were multiplied on a pixel-by-pixel basis by the grayscale image. A comparison of the performances of the three techniques was made by three independent observers assessing the conspicuity of specific MRI and PET information in the merged images. For evaluation purposes, images from seven patients and a computer-simulated MRI/PET phantom were used. Data were compared with a chi-square test applied to ranks. RESULTS: For the depiction of MRI and PET information when merging color PET and T1-weighted MR images, FE was rated superior to intensity modulation and averaging techniques in a significant number of comparisons. For merging grayscale PET with multispectral color MR images, FE and intensity modulation were rated superior to image averaging in terms of both MRI and PET information. CONCLUSION: The data suggest that improved simultaneous evaluation of MRI and PET information can be achieved with a method based on FE.

Brain↗
PubMed1998

Reproducibility of intracranial volume measurement by unsupervised multispectral brain segmentation.

To assess the inter-study variability of a recently published unsupervised segmentation method (Magn. Reson. Med. 1997;37:84-93), 14 brain MR studies were performed in five normal subjects. Standard deviations for absolute and fractional volumes of intracranial compartments, which reflect the experimental variability, were smaller than 16.5 ml and 1.1%, respectively. By comparing the experimental component of the variability with the variability observed in our reference database, an estimate of the biological variability of the intracranial fractional volumes in the database population was obtained.

Adolescent↗
PubMed1997

Unsupervised, automated segmentation of the normal brain using a multispectral relaxometric magnetic resonance approach.

The purpose of this study was the development and testing of a method for unsupervised, automated brain segmentation. Two spin-echo sequences were used to obtain relaxation rates and proton-density maps from 1.5 T MR studies, with two axial data sets including the entire brain. Fifty normal subjects (age range, 16 to 76 years) were studied. A Three-dimensional (3D) spectrum of the tissue voxels was used for automatic segmentation of gray matter (GM), white matter (WM), and cerebrospinal fluid (CSF) and for calculation of their volumes. Accuracy and reproducibility were tested with a three-compartment phantom simulating GM, WM, and CSF. In the normal subjects, a significant decrease of GM fractional volume and increased CSF volume with age were observed (P < 0.0001), with no significant changes in WM. This multispectral segmentation method permits reproducible, operator-independent volumetric measurements.

Adolescent↗
PubMed1997

Diagnostic and prognostic role of 99mTc-Tetrofosmin in breast cancer.

99mTc-Tetrofosmin (TF) is a lipophilic diphosphine compound routinely used for myocardial scintigraphy. Extracardiac utilization has occurred in evaluation of patients with malignant neoplasms and in parathyroid adenomas. Although its uptake mechanisms are not completely understood, they appear similar to those of 99mTc Setamibi (MIBI). The importance of flow and the metabolic status of cells with an intracellular uptake depending on mitochondria and the Na+/K+ pump have been hypothesized. It has also been demonstrated that Tetrofosmin shares with MIBI the property of being a substrate for P-glycoprotein (P-gp), a multidrug resistance transporter. In this review the possible clinical role in breast cancer is analysed. First experiences suggest that scintimammography with TF is useful in patients with indeterminate Mammography and to obtain complementary data to avoid surgery and/or biopsy. TF is a reliable tracer for diagnosis of primary cancer, of local recurrence of axillary lymph node metastases. Preliminary data stimulate a possible role in functional imaging of chemoresistance and in differential diagnosis of distant metastases with main reference to the evaluation of single hot lesions at bone scan.

Animals↗
PubMed1994

MRI detects acute degeneration of the nigrostriatal dopamine system after MPTP exposure in hemiparkinsonian monkeys.

Exposure to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) can cause an acute chemical toxicity resulting in a parkinsonian state in humans and nonhuman primates. We wished to assess whether the toxicity from MPTP is associated with changes on magnetic resonance images of brain structures containing dopamine neuronal processes or with disrupture of the blood-brain barrier. Normal rhesus monkeys and monkeys at various times after being subjected to unilateral intracarotid injection of MPTP (0.4 mg/kg) were studied with magnetic resonance imaging using T1- and T2-weighted spin-echo and gradient-echo sequences. Disrupture of the blood-brain barrier was assessed also with magnetic resonance imaging after administration of gadolinium-diethylenetriamine pentaacetic acid. Parkinsonian symptoms contralateral to the infused carotid usually appeared within 1 day after MPTP exposure, reaching their peak severity by 7 days, when all monkeys showed clear clinical abnormalities. Magnetic resonance imaging changes developed in concomitance with the clinical signs and were characterized by increased signal intensity on T2-weighted images as well as decreased intensity on T1-weighted images of the ipsilateral caudate and putamen. T2 hyperintensity was also present just dorsal to the pars compacta of the substantia nigra, in the region of the proximal nigrostriatal tract. All magnetic resonance imaging changes dissipated in the next 2 weeks. There were no abnormalities at any time in the globus pallidus, nucleus accumbens, and other structures innervated by the mesocorticolimbic dopamine system. After MPTP exposure, there was no evidence of blood-brain barrier disrupture, suggesting that vasogenic edema was an unlikely factor in the production of the observed abnormalities.(ABSTRACT TRUNCATED AT 250 WORDS)

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1994

Regional cerebral blood flow imaging with 99mTc-bicisate SPECT in asymmetric Parkinson's disease: studies with and without chronic drug therapy.

Regional cerebral perfusion was assessed in six patients with asymmetric Parkinson's disease (PD) of mild to moderate severity and in six matched normal subjects using 99mTc-bicisate single photon emission computed tomography (SPECT). Regional activity was normalized to whole-brain activity. Each subject was studied twice, separated by 15.2 +/- 9.2 and 18.0 +/- 4.8 days in normals and PD patients, respectively. There was low intrasubject scan-rescan variability in normals, with all regions showing an average intrasubject difference in repeat studies of < 3%. In PD patients after chronic oral antiparkinsonian drugs had been withdrawn, as compared with normal subjects, there was increased perfusion in the caudate and lenticular nuclei contralateral to the worst affected extremities. This increased basal ganglia perfusion was attenuated by chronic oral therapy. The clinical relevance of these changes is indicated by the high positive correlation between various measures of clinical PD severity and the lenticular perfusion. These differences in basal ganglia perfusion measured with 99mTc-bicisate SPECT in mild to moderate, asymmetric PD may be secondary to increased metabolic demand resulting from alterations of synaptic activity.

Adult↗
PubMed1991

Analysis of leucocyte populations with the Coulter S-Plus STKR as a screening tool for haematological abnormalities.

In two institutions at Rome and Florence we evaluated the clinical sensitivity of two Coulter STKR systems using the NCCLS standard H20-T for leucocyte differential count in a patient population with high prevalence of haematologic abnormalities. Reference ranges of normal leucocytes were obtained on 278 adult subjects. On a population of 455 patient specimens, 200 specimens (44%) were flagged by the STKR because of a distributional abnormality, and 122 (27%) because of a morphological abnormality. Percentage of subtotal agreements between the STKR and the reference manual differential count was 85.4%, with 67.5% full and 20.9% partial agreements. Eight specimens that showed a morphological abnormality with the reference manual differential count were classified as normal by the STKR, with a false normal rate of 6.6%. Analysis of the STKR performance for morphological abnormalities showed acceptable sensitivity (82.0%) and rather low specificity (71.5%), low predictive value of positive results (51.3), high predictive value of negative results (91.5%) and efficiency of 74.3%. The main problems of the STKR differential count were a high rate of false monocyte count, and the misidentification of eosinophilias and low-concentration abnormal cells.

Evaluation Studies as Topic↗
PubMedDate not supplied

An assessment of the operating characteristics of Coulter Counter Model S-Plus STKR.

BACKGROUND AND METHODS: The operating performance of the Coulter Counter S Plus STKR was evaluated in two hospital laboratories in Rome and in Florence. Experimental design conformed to both the ICSH and NCCLS Standards for the evaluation of hematologic analyzers, and to the ECCLS guidelines for the multicenter evaluation of analyzers in clinical chemistry. RESULTS AND CONCLUSIONS: Cell counts in K3 EDTA were unchanged over 6 hours at room temperature and 72 hours at 4 degrees C, while MCV, MPV and leukocyte differentials were far less stable. Carry over, precision and linearity met the manufacturer's specifications, while a satisfactory relative accuracy was demonstrated by determining reference values on an adult reference group and by comparing the instrument with the previous model S Plus IV D. The accuracy of the leukocyte differentials was evaluated by the microscope reference method, and our results seemed to validate the hypotheses that the STKR model counts: i) eosinophils, basophils and banded neutrophils among GR; ii) variant lymphocytes among LY, and iii) various abnormal cells among mononuclear cells. However, in spite of this statistical significance, some difficulties in correctly classifying the mononuclear population were demonstrated.

Adult↗