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PubMed2003

Estimating correlation by using a general linear mixed model: evaluation of the relationship between the concentration of HIV-1 RNA in blood and semen.

Estimating the correlation coefficient between two outcome variables is one of the most important aspects of epidemiological and clinical research. A simple Pearson's correlation coefficient method is usually employed when there are complete independent data points for both outcome variables. However, researchers often deal with correlated observations in a longitudinal setting with missing values where a simple Pearson's correlation coefficient method cannot be used. General linear mixed models (GLMM) techniques were used to estimate correlation coefficients in a longitudinal data set with missing values. A random regression mixed model with unstructured covariance matrix was employed to estimate correlation coefficients between concentrations of HIV-1 RNA in blood and seminal plasma. The effects of CD4 count and antiretroviral therapy were also examined. We used data sets from three different centres (650 samples from 238 patients) where blood and seminal plasma HIV-1 RNA concentrations were collected from patients; 137 samples from 90 different patients without antiviral therapy and 513 samples from 148 patients receiving therapy were considered for analysis. We found no significant correlation between blood and semen HIV-1 RNA concentration in the absence of antiviral therapy. However, a moderate correlation between blood and semen HIV-1 RNA was observed among subjects with lower CD4 counts receiving therapy. Our findings confirm and extend the idea that the concentrations of HIV-1 in semen often differ from the HIV-1 concentration in blood. Antiretroviral therapy administered to subjects with low CD4 counts result in sufficient concomitant reduction of HIV-1 in blood and semen so as to improve the correlation between these compartments. These results have important implications for studies related to the sexual transmission of HIV, and development of HIV prevention strategies.

Anti-HIV Agents↗

PubMed1992

Correlations of developmental end points observed after 2,4,5-trichlorophenoxyacetic acid exposure in mice.

A large-scale developmental toxicology study of 2,4,5-trichlorophenoxyacetic acid was conducted in four inbred strains and one outbred strain of mice. The most significant developmental effects observed were reduced fetal weight and increased incidences of cleft palate (malformation) and prenatal death (deaths/resorptions). The correlation coefficients among the proportion of deaths/resorptions, proportion of malformations, average fetal weights, and number of viable fetuses were investigated, with each variable measured on a per-litter basis. Generally, the correlation coefficients between average fetal weight and number of viable fetuses were negative for the control and low-dose groups in the C57BL/6, C3H/He, and BALB/c strains. Overall, the correlation coefficients between proportion of malformations and number of viable fetuses were not significant. The correlation coefficients between proportion of malformations and average fetal weight were negative for all but one case. The correlations were weak in the control and low-dose groups, in which the malformation rates were very low, and were strong in the high-dose groups. The correlation coefficients between proportion of deaths/resorptions and proportion of malformations were generally positive at the high doses; some negative correlations were observed in control and low-dose groups. The correlation coefficients between proportion of deaths/resorptions and average fetal weight were negative for the A/JAX and CD-1 strains. In summary, the strongest relationship observed was the negative correlation between fetal weight and malformation.

2,4,5-Trichlorophenoxyacetic Acid↗

PubMed1998

How phenotypic variation and life history trait correlation enhance mean fitness in prey populations.

The relative effects of phenotypic variation and trait correlations on mean population fitness are poorly understood. Moreover, when fitness is evaluated in the context of ecological processes such as predation, theoretical development is lacking. To address this deficiency, we simulate a predator-prey system, where the prey population is composed of three phenotypes that differ in fecundity and predator evasiveness. We use equilibrium population size and allele frequencies to examine the relative effects of trait variation and correlation on mean population fitness. When no correlation is present, increasing variance in either trait increases equilibrium population size. Negative correlations coupled with increasing variance in both traits increases equilibrium population size. Positive correlations are more likely to increase equilibrium population size when variances are inversely related. With respect to allele frequencies, as variance in both traits increases, populations with positive correlations experience greater loss of genetic diversity than those with negative correlations. Thus, selection as a dynamic ecological process (frequency-dependent predation) favors trade-offs, whether they are between trait means (negative correlations) or variances (positive correlations).

Animals↗

PubMed2000

Poor correlation between body surface area and glomerular filtration rate.

PURPOSE: The aim of this study was to determine the correlation between body surface area (BSA) and glomerular filtration rate (GFR) measured by Tc-99m DTPA clearance in adult patients with cancer. METHODS: GFR was determined by Tc-99m DTPA clearance in adult patients with cancer. Height and actual body weight were measured. Ideal body weight was calculated. BSA was calculated using the Du Bois and Du Bois linear method using both actual and ideal body weight. RESULTS: Included in the study were 122 patients. The mean GFR measured by Tc-99m DTPA clearance was 87 ml/min (range 30-174 ml/min). The mean BSA (actual weight) was 1.76 m2 (median 1.73 m2, range 1.31-2.58 m2). The mean BSA (ideal body weight) was 1.63 m2 (median 1.63 m2, range 1.20-2.00 m2). The overall correlation between BSA (actual weight) and GFR in this adult population was r = 0.24, and the 95% confidence interval was 0.06-0.4. The correlation between BSA (ideal body weight) and GFR was r = 0.22. The correlation between BSA and GFR excluding patients with a BSA < 1.5 m2 or > 2.0 m2 was 0.12. When patients with GFR < 50 ml/min or > 100 ml/min were excluded, the correlation with BSA was 0.07. The correlations between GFR and height, actual weight and ideal weight were 0.22, 0.21 and 0.22, respectively. CONCLUSIONS: This study demonstrated a poor correlation between GFR determined by Tc-99m DTPA clearance and BSA calculated using the Du Bois and Du Bois linear method. The 95% confidence interval for the correlation between BSA and GFR was 0.06-0.4 indicating that a strong applicable clinical correlation is very unlikely.

Adult↗

PubMed2006

Genetic and environmental correlations of bone mineral density at different skeletal sites in females and males.

Bone mineral density (BMD) is a complex trait having genetic and environmental determination. There are gender-specific differences in BMD measurements, and the rate of BMD changes with age and lifestyle. Previous studies have shown that the genetic loci underlying BMD variation are gender-specific in mice and humans. Our study aimed to investigate correlations between BMD at the spine, hip, and ultradistal radius (UD) and degree of shared genetic and environmental factors among them in females and males, separately. For a large sample of 4,489 subjects containing 2,667 females and 1,822 males from 512 Caucasian pedigrees, we performed bivariate variance decomposition analyses. Our results showed that the genetic correlations (rhoG), environmental correlations (rhoE), and phenotypical correlations (rhoP) were all significant and positive. Strong genetic correlations were observed in both female and male groups, ranging 0.590-0.738 and 0.583-0.773, respectively. Genetic correlations of BMD at the spine, hip, and UD were generally higher than environmental correlations. In summary, we are the first to test the genetic and environmental correlations in females and males, separately. It is suggested that the phenotypic correlations of BMDs at the three different sites may have more genetic than environmental components. BMDs at the spine and hip may share more environmental components in females than males. We did not detect gender-specific difference in spine/UD and hip/UD. It is also indicated that the environmental factors that preserve or increase BMD at one skeletal site may have similar beneficial effects on some other skeletal sites and vice versa.

Absorptiometry, Photon↗

PubMed2005

Quantitative analysis of the corpus callosum in children with cerebral palsy and developmental delay: correlation with cerebral white matter volume.

BACKGROUND: The direct quantitative correlation between thickness of the corpus callosum and volume of cerebral white matter in children with cerebral palsy and developmental delay has not been demonstrated. OBJECTIVE: This study was conducted to quantitatively correlate the thickness of the corpus callosum with the volume of cerebral white matter in children with cerebral palsy and developmental delay. MATERIAL AND METHODS: A clinical database of 70 children with cerebral palsy and developmental delay was established with children between the ages of 1 and 5 years. These children also demonstrated abnormal periventricular T2 hyperintensities associated with and without ventriculomegaly. Mid-sagittal T1-weighted images were used to measure the thickness (genu, mid-body, and splenium) and length of the corpus callosum. Volumes of interest were digitized based on gray-scale densities to define the hemispheric cerebral white matter on axial T2-weighted and FLAIR images. The thickness of the mid-body of the corpus callosum was correlated with cerebral white matter volume. Subgroup analysis was also performed to examine the relationship of this correlation with both gestational age and neuromotor outcome. Statistical analysis was performed using analysis of variance and Pearson correlation coefficients. RESULTS: There was a positive correlation between the thickness of the mid-body of the corpus callosum and the volume of cerebral white matter across all children studied (R=0.665, P=0.0001). This correlation was not dependent on gestational age. The thickness of the mid-body of the corpus callosum was decreased in the spastic diplegia group compared to the two other groups (hypotonia and developmental delay only; P<0.0001). Within each neuromotor subgroup, there was a positive correlation between thickness of the mid-body of the corpus callosum and volume of the cerebral white matter. CONCLUSION: The thickness of the mid-body of the corpus callosum positively correlates with volume of cerebral white matter in children with cerebral palsy and developmental delay, regardless of gestational age or neuromotor outcome. Assessment of the thickness of the corpus callosum might help in estimating the extent of the loss of volume of cerebral white matter in children with a broad spectrum of periventricular white matter injury.

Agenesis of Corpus Callosum↗

PubMed2005

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

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

Aged↗

PubMed2004

Amyloid beta peptide 1-42 highly correlates with capillary cerebral amyloid angiopathy and Alzheimer disease pathology.

Recent studies reported both positive [Thal et al. (2003) J Neuropathol Exp Neurol 62:1287-1301] and negative [Tian et al. (2003) Neurosci Lett 352:137-140] correlations between cerebral amyloid angiopathy (CAA) and Alzheimer's disease (AD) pathology. We have recently shown high correlations between neuritic AD pathology and amyloid beta peptide (Abeta) deposits in the capillary/pericapillary compartment (CapCAA) with only low correlations to general CAA (non-capillary). We have now studied the relationship between CapCAA and AD pathology with respect to the distribution of Abeta40 and 42 in the frontal cortex of 100 human postmortem brains from both male and female, demented and non-demented patients (mean age +/- SD 84.3 +/- 9.3 years). Using polyclonal antibodies to Abeta40 and 42, capillary and plaques positivity were assessed semiquantiatively on a four-point scale. Abeta42 deposits in capillaries correlated highly with both Abeta42 deposits in plaques and morphological AD criteria (CERAD, Braak stages, and NIA-Reagan-Institute criteria), while only a low correlation with CAA was observed. Abeta40 deposits in capillaries differed morphologically from Abeta42 ones: they were limited to capillary walls, were significantly less frequent in both capillaries and plaques compared to Abeta42 ( P < 0.01), and showed a low correlation with morphological AD criteria ( P < 0.05) and general CAA ( P < 0.01). By contrast, Abeta42 deposits were seen in the glia limitans rather than in capillary walls themselves, and showed high correlation with morphological AD criteria ( P < 0.01). These data indicate that CapCAA is characterized by Abeta42 deposits in pericapillary spaces or in the glia limitans. A low correlation between CAA and CapCAA, but high correlations between morphological AD criteria and CapCAA suggest different pathomechanisms for both types of CAA, and a close relation between CapCAA and AD pathology (both neuritic and plaque type). These data support the concept of a neuronal origin of Abeta via drainage from interstitial fluid from the central nervous system along basement membranes to capillaries.

Aged↗

PubMed2006

Correlations of tissue macrophages and cytoskeletal protein expression with renal fibrosis in patients with diabetes mellitus.

BACKGROUND: In clinicopathological studies of cellular remodeling in the progression of diabetic nephropathy, it has not been well described whether tissue macrophage numbers and the expression of two cytoskeletal proteins--alpha-smooth muscle actin (alphaSMA) and vimentin--correlate with the disease severity. METHODS: Renal biopsy specimens from 23 patients with noninsulin-dependent diabetes mellitus (NIDDM) were examined by immunoperoxidase methods for CD68+ macrophages and alphaSMA and vimentin staining in paraffin-embedded samples. alphaSMA staining was evaluated in mesangial and interstitial myofibroblastic cells, and vimentin staining was evaluated in podocytes and mesangial and tubular cells. RESULTS: Glomerular macrophage numbers were not correlated with any clinicopathological scores. However, the interstitial macrophage score was significantly correlated with serum creatinine (sCr) and strongly correlated with the interstitial fibrosis score. Both alphaSMA and vimentin were detectable in the mesangium, without significant correlation with each other. A positive correlation was observed between mesangial alphaSMA and urinary (u-) protein levels. In contrast, an inverse correlation was observed between levels of mesangial vimentin and u-protein. Mesangial alphaSMA, but not vimentin, showed a significant correlation with glomerular sclerosis. Podocytic vimentin levels tended to decrease in patients with higher sCr levels. The severity of interstitial peritubular alphaSMA was correlated strongly with interstitial macrophage proliferation and significantly with the interstitial fibrosis score. CONCLUSIONS: The expression of mesangial alphaSMA may play a role in the progression of glomerular damage, while, on the other hand, newly acquired mesangial vimentin seems to be attenuated by heavy proteinuria. In addition, it was suggested that peritubular alphaSMA-positive myofibroblastic cells, in collaboration with interstitial macrophages, contribute to the progression of interstitial fibrosis in diabetic nephropathy.

Actins↗

PubMed1980

Ipsilateral and contralateral correlations between EEG and EP principal components.

Correlations between EP and EEG principal components are reported. The signs of the correlations appear to depend on 3 factors: frequency of the EEG, whether the EP and EEG were measured from ipsilateral or contralateral leads, and EP latency. Correlations are negative between EP amplitude (at 100-500 msec) and EEG alpha from ipsilateral leads. When the EP measurements are from leads contralateral to the eEG alpha measurements, the correlations are positive. EEG beta, however, shows the opposite pattern (ipsilateral correlations are positive, while contralateral correlations are negative). Finally, there is some indication of higher ipsilateral correlations for earlier EP components (as opposed to lower correlations for later EP components), and higher contralateral correlations for later EP components. The EPs and EEGs were taken during separate experimental conditions as part of the same experimental session. The original EP measurements were amplitudes (N100, P150, N200, and P300) to words flashed on a television screen, as S1 of a CNV paradigm. The EEGs were 4 sec epochs taken immediately upon television presentation of a word or picture problem.

Adolescent↗

PubMed1989

Electroencephalographic correlates of blood flow and oxygen metabolism provided by positron emission tomography in patients with cerebral infarction.

Quantitative EEG data were analyzed statistically with respect to cortical cerebral blood flow (CBF) and oxygen metabolism (CMRO2) measured by positron emission tomography in 47 patients with unilateral cerebral infarction. Relative value of the square root of average power was used as a percentage power fraction (PPF) for each frequency category. Power ratio index (PRI) was calculated by dividing the combined delta-PPF and theta-PPF by the combined alpha-PPF and beta-PPF. Delta-PPF, theta-PPF and PRI correlated negatively with regional CBF (rCBF) and CMRO2 (rCMRO2) whereas alpha-PPF and beta-PPF correlated positively. In the acute stage, delta-PPF, alpha-PPF and PRI correlated with rCBF at all but the frontopolar region whereas the correlation with rCMRO2 was poor. Alpha-PPF and PRI correlated also with rCMRO2 in the frontal, central, parietal and occipital regions while delta-PPF correlated with rCBF only in the parietal and occipital regions in the subacute stage. In the chronic stage, all EEG quotients correlated significantly with both rCBF and CMRO2 in the central and parietal regions. In the frontopolar region, only the theta-PPF correlated with rCBF throughout. In the comparison of hemispheric mean values, the correlations were always closer for the affected hemisphere than for the contralateral hemisphere. Although hemispheric mean CBF and CMRO2 were significantly lower in patients with cortical infarcts on CT than in those with small subcortical infarcts, there was no significant difference in the EEG data between the 2 groups.

Brain↗

PubMed1993

Correlation between computed tomography and voltage and current source density spectral EEG parameters in patients with brain lesions.

In a group of patients with space-occupying brain lesions, CT measurements were correlated with absolute power (AP) and relative power (RP) of the delta, theta, alpha and beta EEG bands, calculated from the raw EEG potentials (EEGp) and from the Laplacian estimates also called "current source densities" (CSD). Rank correlations were calculated between the number of abnormal values in each band and the following CT measures: volume of the lesion and of the edema, density of the edema, percentage of ventricular collapse and midline shift. Abnormal spectral values are those which are significantly higher than the norm for the same age, in the delta and theta bands, and significantly lower in the alpha and beta bands. Spectral parameters obtained from the CSD showed higher correlations with CT measures than those calculated from the EEGp. In the Laplacian, all CT measures had a significant correlation with delta AP. Theta AP was significantly correlated with the volume and density of the edema, as well as with midline shift. Significant correlations were also observed with delta and alpha RP. However, changes in RP were considered to be a consequence of the increase in delta AP. Canonical correlation analyses between AP and RP calculated from EEGp or CSD and the first 3 CT measures showed that the volume of the lesion was only correlated with delta AP and RP. The volume and density of the edema showed a significant correlation with delta, theta and alpha AP calculated from EEGp and only with theta and alpha AP in the Laplacian. Since the EEGp tends to produce a more extensive and diffuse picture of abnormality, whereas the Laplacian acts as a spatial filter emphasizing local sources over distant sources, we concluded that edema is related not to delta activity, but to the theta and alpha power.

Adolescent↗

PubMedDate not supplied

Correlations of synaptic and pathological markers with cognition of the elderly.

It has been suggested that the physical basis for dementia is structural or functional loss of synapses. To confirm this finding, we performed an enzyme-linked immunoassay (ELISA) with a monoclonal antibody (EP10) to a synaptophysin-like protein in brain samples from 45 prospectively studied elderly subjects with an average age of 83.3 +/- 10.1 years. We compared the synaptic marker to immunoreactivity with a newly developed PHF antibody (TG3). The cases were selected on the basis of availability of frozen tissue, and included subjects ranging from clinically normal to end-stage dementia. As an initial assessment, we determined Pearson product moment correlations for two clinical measures--the Blessed test of information, concentration, and memory (BICM) and the Fuld object Memory Evaluation (FOME)--with ELISA data and with traditional pathologic markers. We found strong correlations (p < 0.01-0.001) for BICM with brain weight, neuronal loss in the basal nucleus of Meynert (nbM), counts of senile plaques (SP) in the neocortex and hippocampus, and neurofibrillary tangles (NFT) in all areas except the parahippocampal cortex. Except in the occipital lobe, where paired helical filament changes are relatively uncommon, TG3-immunoreactivity also correlated strongly with BICM. Weak correlations (p < 0.05) were found for BICM with EP10-immunoreactivity in only the temporal and parietal lobes. Only the pathologic variables showed any significant correlations with FOME. Because inclusion of normal subjects with few or no pathologic lesions could have been driving the strong correlations with pathologic markers, we limited the analysis to those subjects with dementia (BICM; 8). After making this correction, EP10-immunoreactivity in all cortical areas and the hippocampus correlated better (p < 0.05-0.01) with BICM but not FOME. The present univariate analysis suggests that synaptic markers may not be the best structural correlate of dementia and that markers indicative of cytoskeletal changes, e.g., SP, NFT and PHF protein accumulation, may be better correlates of dementia in the elderly.

Aged↗

PubMed2005

Resting SPECT-neuropsychology correlation in very mild Alzheimer's disease.

OBJECTIVE: To investigate the relationships between brain function and some of the most frequently impaired cognitive domains in the first stages of Alzheimer's disease (AD), we searched for correlation between the scores on 3 neuropsychological tests and brain perfusion, assessed by single photon emission computed tomography (SPECT) in patients with very mild AD. METHODS: Twenty-nine consecutive outpatients (mean age 78.2+/-5.5) affected by probable AD in the very mild phase (i.e. with a score > or =20 on the mini-mental state examination, MMSE) underwent brain SPECT with (99m)Tc-ethylcisteinate dimer. For correlative purposes, word list learning (by the selective reminding test, SRT), constructional praxis test (CPT) and visual search test (VST) were chosen a priori out of an extended battery employed to diagnose AD at first patient evaluation. Voxel-based correlation analysis was achieved by statistical parametric mapping (SPM99) with a height threshold of P=0.005. Age, years of education and the MMSE score were inserted in the correlative analysis as confounding variables. RESULTS: The SRT score showed correlation with brain perfusion in 3 clusters of the left hemisphere, including the post-central gyrus, the parietal precuneus, the inferior parietal lobule and the middle temporal gyrus, and in one cluster in the right hemisphere including the middle temporal gyrus and the middle occipital gyrus. The CPT score was significantly correlated with brain perfusion in the parietal precuneus and the posterior cingulate gyrus in the left hemisphere, whereas the VST score gave a significant correlation with brain perfusion in a left cluster including the parietal precuneus and the superior temporal gyrus. CONCLUSIONS: Cognitive impairment in very mild AD is reflected by brain dysfunction in posterior associative areas, with peculiar topographical differences proper of each domain. The parietal precuneus was a common site of correlation of all 3 neuropsychological tests. This region, together with the posterior cingulate and the superficial posterior temporal-parietal cortex, is thought to be affected by disconnection from the mesial temporal lobe, besides being directly affected by increased oxidative stress and by atrophy as well. The impairment of these areas is thought to contribute to cognitive decline in verbal memory, constructional praxis and visual sustained attention which are indeed among the earliest signs of cognitive impairment in AD. SIGNIFICANCE: Assessing the relationships between neuropsychology and brain functional imaging is a key approach to clarify the pathophysiology of cognitive failure in AD; the specificity of these findings in AD remains to be proven through comparison with correlation achieved in matched controls.

Aged↗

PubMed2005

Bladder transitional cell carcinoma: correlation of contrast enhancement on computed tomography with histological grade and tumour angiogenesis.

AIM: To investigate the correlation between the degree of contrast enhancement of bladder cancer in the early enhanced phase of helical computed tomography (CT) and microvessel density (MVD), vascular endothelial growth factor (VEGF) and histological grade. MATERIALS AND METHODS: Sixty-five patients with transitional cell carcinoma of the bladder were examined by incremental unenhanced CT and helical CT at 40-45 s after initiation of intravenous administration of contrast medium before surgery. The CT density in Hounsfield units of bladder carcinomas were measured in the middle of the maximum diameter section of the cancer lesions on unenhanced and enhanced CT. The degree of contrast enhancement of the tumour was determined as the absolute increase in Hounsfield units. Histological grade, VEGF and MVD were analysed for each cancer. The Pearson and Spearman correlation tests were used to determine the strength of the relationships between CT enhancement and histological grade, VEGF expression and MVD. RESULTS: Different degrees of enhancement were observed in 91 cancers during the early enhanced phase of helical CT. Mean MVDs and mean CT enhancing values of different histological grade groups were statistically different (p < 0.001). A positive correlation was found in the CT-enhancing value of bladder cancer and MVD (Pearson correlation test; r = 0.938, p < 0.001) and histological grade (Spearman rank correlation; r = 0.734, p < 0.001). VEGF of bladder cancer did not correlate with the change in CT attenuation (Spearman rank correlation; r = 0.087, p = 0.410) and MVD (Spearman rank correlation, r = 0.103, p = 0.330). CONCLUSION: In bladder cancer, the degree of contrast enhancement during the early enhanced helical CT is correlated with the MVD and histological grade of tumour. It is possible that MVD is the histopathological basis of early contrast enhancement of bladder cancer.

Adult↗

PubMed2005

US correlation for MRI-detected breast lesions in women with familial risk of breast cancer.

AIM: To examine the value of US correlation for MRI-detected breast lesions in women with familial risk of breast cancer. METHODS: From an initial dataset of 245 women with positive family history who had breast cancer surveillance involving mammography or MRI between November 1994 and February 2001, 179 subjects with follow-up data were selected. A total of 43 women with 48 MRI-detected lesions underwent further assessment with US. Histopathological correlation was available from 38 breast biopsies performed for 33 women. RESULTS: Sonographic correlates were identified in 32 (66.7%) of the 48 MRI-detected lesions, with cancer present in 11 (34.4%) of these. This compares with 1 (6.3%) cancer found in the 16 lesions without sonographic correlates. Of the 12 malignant lesions, 11 (91.7%) had sonographic correlates whereas 21 (58.3%) of the 36 benign lesions had sonographic correlates. In all 74% of breast biopsies were performed under US guidance compared with 8% under MRI guidance. The proportion of MRI- and US-correlated benign and malignant lesions undergoing US-guided biopsy were 85.7% and 90.9%, respectively. CONCLUSION: The probability of cancer was significantly higher in MRI-detected breast lesions with sonographic correlates compared with those without such correlation. The advantage of convenient biopsy under US guidance as opposed to MRI guidance highlights the value of sonographic assessment of MRI-detected breast lesions.

Adult↗

PubMed2004

Evaluation of internal lung motion for respiratory-gated radiotherapy using MRI: Part I--correlating internal lung motion with skin fiducial motion.

PURPOSE: To measure the internal lung motion due to respiration using magnetic resonance images (MRIs); to evaluate the correlation between lung motion and skin surface motion and the reliability of tracking lung motion with external fiducials. METHODS AND MATERIALS: An MRI protocol using fast gradient-echo sequences was developed to acquire dynamic cine images of the thoracoabdominal region along the axial, sagittal, and coronal planes. The subjects (3 healthy volunteers and 4 lung cancer patients) were instructed to perform normal or altered breathing during MRI. Lung vessels identified on MRI were used as anatomic landmarks for internal lung structures. From sagittal cine MRI scans, the positions of the lung vessels and skin surface were tracked and their movements measured. Correlation between the movements of the external markers and internal structures was then calculated and analyzed. RESULTS: Lung vessel motion in the superior-inferior (SI) direction correlated best with mid-upper abdominal skin surface movement (correlation coefficient, 0.89 +/- 0.09 and 0.87 +/- 0.23 for volunteers and patients, respectively). The anterior-posterior (AP) vessel motion generally correlated poorly with the skin surface movement, with marker placement on the upper chest yielding the strongest results (correlation coefficient, 0.72 +/- 0.23 and 0.44 +/- 0.27 for volunteers and patients, respectively). The strength of the correlation depended on the locations of the tracked vessels, locations of the skin surface, and subjects' breathing patterns. The best correlation was seen between the motion of an abdominal fiducial and SI lung motion. Significant intersubject variability was also observed. CONCLUSION: Movement of an external fiducial may not correlate fully with, or predict, internal lung motion. Effective monitoring of respiration may have to rely on a combination of multiple fiducials and other physiologic parameters, such as lung volume and/or air flow.

Adult↗

PubMed2005

Different methods of heart rate variability analysis reveal different correlations of heart rate variability spectrum with average heart rate.

UNLABELLED: Heart rate variability (HRV) spectrum can be calculated from the R-R or the sequence of instantaneous heart rates (IHRs). Because these signals are reciprocal, their use in the determination of the correlation of HRV with average HR may yield opposite results. AIM: The aim of this study is to reveal how HRV parameters correlate with HR depending on the kind of signal used and whether the normalization procedure or use of corrected signals affect the correlations. METHODS: Electrocardiographic recordings (512 beats) of 55 patients were considered in the analysis. RR and IHRs were calculated. Both signals were divided by their average values yielding the corrected RR and IHR. Heart rate variability spectra were estimated from these 4 kinds of signals. Total power (TP), low frequency (LF) and high frequency (HF) components, LF/HF ratio, and normalized values (ie, nLF, nHF) were calculated. RESULTS: Total power and LF estimated from RR correlated negatively with HR, but those calculated from IHR revealed a trend toward a positive correlation (respective correlation coefficients significantly differed, P < .01). The sign of correlation between HF and HR was the same regardless of the type of signal applied. The application of corrected signals made the results almost identical despite different signal origins (RR or IHR). The correlations of LF/HF, nLF, and nHF with HR were similar in all cases. CONCLUSIONS: The type of signal determines the sign of correlation among TP, LF, and HR. The parameters obtained from corrected signals, normalized quantities, and LF/HF reveal a consistent relationship with HR.

Electrocardiography↗