Pre-selected Region Of Interest Research Articles

Inhibitory control in young adult women with fetal alcohol syndrome: Findings from a pilot functional magnetic resonanceimaging study.

Executive dysfunction, especially impaired inhibitory control, is a common finding in individuals with fetal alcohol syndrome (FAS). Previous research has mostly focused on neural correlates of inhibitory deficits in children and adolescents. We investigated inhibitory functions and underlying cerebral activation patterns in young adult women with FAS. Task performance and functional magnetic resonance imaging (fMRI) data were acquired during a Go/NoGo (GNG) inhibition task in 19 young adult women with FAS and 19 healthy female control subjects. Whole-brain activation and task performance analyses were supplemented by region of interest (ROI) analyses of fMRI data within a predefined cognitive control network (CCN). Task performance did not differ significantly between groups on errors of commission, associated with inhibitory control. Similarly, overall activation within the preselected ROIs did not differ significantly between groups for the main inhibitory contrast NoGo > Go. However, whole-brain analyses revealed activation differences in the FAS group when compared to controls under inhibitory conditions. This included hyperactivations in the left inferior frontal, superior temporal, and supramarginal gyri in the FAS group. Likewise, lateralization tendencies toward right-hemispheric ROIs were weaker in FAS subjects. In contrast to comparable inhibitory performance, attention-related errors of omission were significantly higher in the FAS group. Correspondingly, FAS subjects had lower activity in attention-related temporal and parietal areas. The known alterations of inhibitory functions associated with prenatal alcohol exposure in children and adolescents were not seen in this adult sample. However, differential brain activity was observed, reflecting potential compensatory mechanisms. Secondary results suggest that there is impaired attentional control in young adult women with FAS.

MALDI TOF Mass Spectrometry Imaging of Blood Smear: Method Development and Evaluation.

The aim of this study was to develop and evaluate matrix assisted LASER desorption ionization (MALDI) time-of-flight (TOF) mass spectrometry imaging (MSI) of blood smear. Integrated light microscope and MALDI IT-TOF mass spectrometer, together with a matrix sublimation device, were used for analysis of blood smears coming from healthy male donors. Different blood plasma removal, matrix deposition, and instrumental settings were evaluated using the negative and positive ionization modes while agreement between the light microscopy images and the lateral distributions of cellular marker compounds served as the MSI quality indicator. Red and white blood cells chemical composition was analyzed using the differential m/z expression. Five seconds of exposure to ethanol followed by the 5 min of 9-aminoacridine or α-cyano-4-hydroxycinnamic acid deposition, together with two sets of instrumental settings, were selected for the MALDI TOF MSI experiments. Application of the thin and transparent matrix layers assured good correspondence between the LASER footprints and the preselected regions of interest. Cellular marker m/z signals coincided well with the appropriate cells. A metabolite databases search using the differentially expressed m/z produced hits which were consistent with the respective cell types. This study sets the foundations for application of blood smear MALDI TOF MSI in clinical diagnostics and research.

A data-driven respiratory motion estimation approach for PET based on time-of-flight weighted positron emission particle tracking.

PurposeRespiratory motion of patients during positron emission tomography (PET)/computed tomography (CT) imaging affects both image quality and quantitative accuracy. Hardware‐based motion estimation, which is the current clinical standard, requires initial setup, maintenance, and calibration of the equipment, and can be associated with patient discomfort. Data‐driven techniques are an active area of research with limited exploration into lesion‐specific motion estimation. This paper introduces a time‐of‐flight (TOF)‐weighted positron emission particle tracking (PEPT) algorithm that facilitates lesion‐specific respiratory motion estimation from raw listmode PET data.MethodsThe TOF‐PEPT algorithm was implemented and investigated under different scenarios: (a) a phantom study with a point source and an Anzai band for respiratory motion tracking; (b) a phantom study with a point source only, no Anzai band; (c) two clinical studies with point sources and the Anzai band; (d) two clinical studies with point sources only, no Anzai band; and (e) two clinical studies using lesions/internal regions instead of point sources and no Anzai band. For studies with radioactive point sources, they were placed on patients during PET/CT imaging. The motion tracking was performed using a preselected region of interest (ROI), manually drawn around point sources or lesions on reconstructed images. The extracted motion signals were compared with the Anzai band when applicable. For the purposes of additional comparison, a center‐of‐mass (COM) algorithm was implemented both with and without the use of TOF information. Using the motion estimate from each method, amplitude‐based gating was applied, and gated images were reconstructed.ResultsThe TOF‐PEPT algorithm is shown to successfully determine the respiratory motion for both phantom and clinical studies. The derived motion signals correlated well with the Anzai band; correlation coefficients of 0.99 and 0.94‐0.97 were obtained for the phantom study and the clinical studies, respectively. TOF‐PEPT was found to be 13–38% better correlated with the Anzai results than the COM methods. Maximum Standardized Uptake Values (SUVs) were used to quantitatively compare the reconstructed‐gated images. In comparison with the ungated image, a 14–39% increase in the max SUV across several lesion areas and an 8.7% increase in the max SUV on the tracked lesion area were observed in the gated images based on TOF‐PEPT. The distinct presence of lesions with reduced blurring effect and generally sharper images were readily apparent in all clinical studies. In addition, max SUVs were found to be 4–10% higher in the TOF‐PEPT‐based gated images than in those based on Anzai and COM methods.ConclusionA PEPT‐ based algorithm has been presented for determining movement due to respiratory motion during PET/CT imaging. Gating based on the motion estimate is shown to quantifiably improve the image quality in both a controlled point source phantom study and in clinical data patient studies. The algorithm has the potential to facilitate true motion correction where the reconstruction algorithm can use all data available.

Abnormal Functional Connectivity in Cognitive Control Network, Default Mode Network, and Visual Attention Network in Internet Addiction: A Resting-State fMRI Study.

Internet addiction (IA) has become a global mental and social problem, which may lead to a series of psychiatric symptoms including uncontrolled use of internet, and lack of concentration. However, the exact pathophysiology of IA remains unclear. Most of functional connectivity studies were based on pre-selected regions of interest (ROI), which could not provide a comprehensive picture of the communication abnormalities in IA, and might lead to limited or bias observations. Using local functional connectivity density (lFCD), this study aimed to explore the whole-brain abnormalities of functional connectivity in IA. We evaluated the whole-brain lFCD resulting from resting-state fMRI data in 28 IA individuals and 30 demographically matched healthy control subjects (HCs). The correlations between clinical characteristics and aberrant lFCD were also assessed. Compared with HCs, subjects with IA exhibited heightened lFCD values in the right dorsolateral prefrontal cortex (DLPFC), left parahippocampal gyrus (PHG), and cerebellum, and the bilateral middle cingulate cortex (MCC) and superior temporal pole (STP), as well as decreased lFCD values in the right inferior parietal lobe (IPL), and bilateral calcarine and lingual gyrus. Voxel-based correlation analysis revealed the significant correlations between the Young's Internet Addiction Test (IAT) score and altered lFCD values in the left PHG and bilateral STP. These findings revealed the hyper-connectivity in cognitive control network and default mode network as well as the hypo-connectivity in visual attention network, verifying the common mechanism in IA and substance addiction, and the underlying association between IA, and attention deficit/hyperactivity disorder in terms of neurobiology.

Use of mTRAQ derivatization reagents on tissues for imaging neurotransmitters by MALDI imaging mass spectrometry: the triple spray method

During drug development, matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry is used for visually elucidating the distribution of substances such as biomarkers, candidate compounds, and metabolites in the tissues. However, it is difficult to make relative comparisons between tissue sections and there are still many challenges. Here, we report a new method of “triple spray” for the comparison of analyte distribution in multiple tissue slices. This method targets amino acids and amines, and it incorporates the application of the internal standard in the on-tissue derivatization step. With further development, it has the potential to alleviate problems caused by the matrix effect. Initially, we measured three serial sections of rat brain to verify the efficacy of this method. In the hypothalamus, where gamma-aminobutyric acid (GABA) is known to be present in high concentration, the GABA levels of the three serial section showed little variation (CV = 1.62%). Subsequently, we compared the GABA level in the brain between stroke-prone spontaneous hypertensive rats (SHRSP) and Wistar-Kyoto (WKY) rats with three individuals each. It showed significant differences between these models at the pre-selected region of interest (p < 0.05). Our results show that the triple spray allows for relative comparison among multiple tissue slices with high reproducibility.Graphical abstract

How age of acquisition influences brain architecture in bilinguals.

In the present study, we explored how Age of Acquisition (AoA) of L2 affected brain structures in bilingual individuals. Thirty-six native English speakers who were bilingual were scanned with high resolution MRI. After MRI signal intensity inhomogeneity correction, we applied both voxel-based morphometry (VBM) and surface-based morphometry (SBM) approaches to the data. VBM analysis was performed using FSL's standard VBM processing pipeline. For the SBM analysis, we utilized a semi-automated sulci delineation procedure, registered the brains to an atlas, and extracted measures of twenty four pre-selected regions of interest. We addressed three questions: (1) Which areas are more susceptible to differences in AoA? (2) How do AoA, proficiency and current level of exposure work together in predicting structural differences in the brain? And (3) What is the direction of the effect of AoA on regional volumetric and surface measures? Both VBM and SBM results suggested that earlier second language exposure was associated with larger volumes in the right parietal cortex. Consistently, SBM showed that the cortical area of the right superior parietal lobule increased as AoA decreased. In contrast, in the right pars orbitalis of the inferior frontal gyrus, AoA, proficiency, and current level of exposure are equally important in accounting for the structural differences. We interpret our results in terms of current theory and research on the effects of L2 learning on brain structures and functions.

Hyperthermia-Induced Disruption of Functional Connectivity in the Human Brain Network

BackgroundPassive hyperthermia is a potential risk factor to human cognitive performance and work behavior in many extreme work environments. Previous studies have demonstrated significant effects of passive hyperthermia on human cognitive performance and work behavior. However, there is a lack of a clear understanding of the exact affected brain regions and inter-regional connectivities.Methodology and Principal FindingsWe simulated 1 hour environmental heat exposure to thirty-six participants under two environmental temperature conditions (25°C and 50°C), and collected resting-state functional brain activity. The functional connectivities with a preselected region of interest (ROI) in the posterior cingulate cortex and precuneus (PCC/PCu), furthermore, inter-regional connectivities throughout the entire brain using a prior Anatomical Automatic Labeling (AAL) atlas were calculated. We identified decreased correlations of a set of regions with the PCC/PCu, including the medial orbitofrontal cortex (mOFC) and bilateral medial temporal cortex, as well as increased correlations with the partial orbitofrontal cortex particularly in the bilateral orbital superior frontal gyrus. Compared with the normal control (NC) group, the hyperthermia (HT) group showed 65 disturbed functional connectivities with 50 of them being decreased and 15 of them being increased. While the decreased correlations mainly involved with the mOFC, temporal lobe and occipital lobe, increased correlations were mainly located within the limbic system. In consideration of physiological system changes, we explored the correlations of the number of significantly altered inter-regional connectivities with differential rectal temperatures and weight loss, but failed to obtain significant correlations. More importantly, during the attention network test (ANT) we found that the number of significantly altered functional connectivities was positively correlated with an increase in executive control reaction time.Conclusions/SignificanceWe first identified the hyperthermia-induced altered functional connectivity patterns. The changes in the functional connectivity network might be a possible explanation for the cognitive performance and work behavior alteration.

Rapid dopaminergic and GABAergic modulation of calcium and voltage transients in dendrites of prefrontal cortex pyramidal neurons

The physiological responses of dendrites to dopaminergic inputs are poorly understood and controversial. We applied dopamine on one dendritic branch while simultaneously monitoring action potentials (APs) from multiple dendrites using either calcium-sensitive dye, voltage-sensitive dye or both. Dopaminergic suppression of dendritic calcium transients was rapid (<0.5 s) and restricted to the site of dopamine application. Voltage waveforms of backpropagating APs were minimally altered in the same dendrites where dopamine was confirmed to cause large suppression of calcium signals, as determined by dual voltage and calcium imaging. The dopamine effects on dendritic calcium transients were fully mimicked by D1 agonists, partially reduced by D1 antagonist and completely insensitive to protein kinase blockade; consistent with a membrane delimited mechanism. This dopamine effect was unaltered in the presence of L-, R- and T-type calcium channel blockers. The somatic excitability (i.e. AP firing) was not affected by strong dopaminergic stimulation of dendrites. Dopamine and GABA were then sequentially applied on the same dendrite. In contrast to dopamine, the pulses of GABA prohibited AP backpropagation distally from the application site, even in neurons with natural Cl− concentration (patch pipette removed). Thus, the neocortex employs at least two distinct mechanisms (dopamine and GABA) for rapid modulation of dendritic calcium influx. The spatio-temporal pattern of dendritic calcium suppression described in this paper is expected to occur during phasic dopaminergic signalling, when midbrain dopaminergic neurons generate a transient (0.5 s) burst of APs in response to a salient event.

Are the effects of cannabis dependence on glucose metabolism similar to schizophrenia? An FDG PET understanding

Background:Cannabis has been associated with transient psychotic states; however, the causal relationship between cannabis and schizophrenia continues to remain a matter of debate. Epidemiological and some biological studies hint at cannabis being an independent risk factor for schizophrenia; this has not been definitively proved.Aims:We aimed to understand the patterns of glucose uptake in important brain regions among individuals with cannabis dependence and schizophrenia. Furthermore, we compared the interregional metabolic rates in pertinent neural circuits among individuals with cannabis dependence, schizophrenia and normal controls.Setting and Design:This is a case-control cross-sectional study that was carried out by a general psychiatry department in collaboration with a nuclear diagnosis unit.Materials and Methods:Male volunteers with cannabis dependence, schizophrenia and normal controls underwent FDG PET scanning. Glucose uptakes in pre-selected regions of interest were compared using MANOVA. Finally, Chow tests were used to compare interregional metabolic relationships in the mesocortical and cortical-subcortical-cerebellum circuits.Results:Significant differences (P<0.05) were noted among individuals with cannabis dependence and schizophrenia in the medial and lateral temporal regions. When the neural circuits were compared, significant interregional differences (P<0.05) were noted between individuals with cannabis dependence and normal controls. However, among individuals with cannabis dependence and schizophrenia, no significant differences (P>0.05) were noted in these patterns.Conclusions:Our findings suggest that cannabis dependence can alter interregional relationships in a manner similar to schizophrenia. This indicates that cannabis could potentially play a role in the development of psychosis by altering neural circuits.

Diffusion Tensor Imaging Detects Clinically Important Axonal Damage after Mild Traumatic Brain Injury: A Pilot Study

The goal of the current investigation was to detect clinically important axonal damage in cerebral white matter after mild traumatic brain injury (TBI) using diffusion tensor imaging (DTI). To this end, we evaluated a prospective, pilot study of six subjects with isolated mild TBI and six matched orthopedic controls. All subjects underwent DTI scanning, post-concussive symptom (PCS) assessment, and neurobehavioral testing within 72 h of injury. Fractional anisotropy (FA) and trace values in white matter voxels of whole brain and five preselected regions of interest (ROI) were compared in mild TBI and control subjects using a quantile approach. In addition, whole brain images were analyzed using voxel-based morphometry. All subjects underwent quality of life and repeat PCS assessment at 1 month. Whole brain images revealed significantly lower 1(st) percentile trace values (mean 0.465 vs. 0.488, p = 0.049) among mild TBI subjects. These trace values correlated with PCS scores at both 72 h (r = -0.57, p = 0.05) and 1 month (r = -0.61, p = 0.04). Analysis of ROIs showed mild TBI subjects to have significantly lower mean trace in the left anterior internal capsule (0.536 vs. 0.574, p = 0.007) and higher maximum ROI-specific median FA values (mean 0.801 vs. 0.756, p = 0.035) in the posterior corpus callosum. These FA values correlated with 72-h PCS score (r = -0.63, p = 0.03), and two neurobehavioral tests (visual motor speed [r = 0.63, p = 0.03] and impulse control [r = 0.59, p = 0.04]). Collectively, DTI detected significantly lower trace and elevated FA values in mild TBI subjects compared to controls. These abnormalities correlated to poor clinical outcome. We believe these findings represent axonal swelling, an early step in the process of axonal injury.

Observing the density increase curve after intravenous contrast medium administration using a bolus triggering system: a method for detection cardiovascular disorders?

Recently bolus tracking systems were developed to improve the timing of intravenous contrast media application in helical computed tomography. We investigated the benefit of this new method as a parameter of the cardiac function. Retrospective analysis of 64 patients which incidentally underwent bolus triggered contrast enhanced helical CT and invasive investigation of the heart within one week. All examinations were performed on the CT scanner Somatom Plus 4 Volume Zoom (Siemens Corp., Forchheim, Germany) using the C.A.R.E. Bolus software. This performs repetitive low-dose test scans (e.g. for the abdomen: 140 kV, 20 mA, Tl 0.5 s) and measures the Hounsfield attenuation (increase over the baseline) in a preselected region of interest. The displayed increase of vascular density over the time after peripheral contrast media injection (75 ml lopromid (300 mg/ml), 2 ml/s) was categorised to three types: (a) rapid increase, (b) deceleration before a 100 HE threshold was reached and (c) one or more peaks. The findings of the invasive investigation of the heart were correlated to the findings of the bolus-tracking measurements. The examinations were categorized as follows: 19 type A, 34 type B, 11 type C. We found a high significant correlation between the type of the Hounsfield attenuation and systolic pressure in the left ventricle. There was no correlation between the type of the Hounsfield attenuation and the diastolic pressure in the left ventricle, the pressures related to the right ventricle or the ejection fraction. The bolus-tacking system showed a sensitivity of 53, a specificity of 82, an accuracy of 70%, a positive predictive value of 70% and a negative predictive value of 70% in detection of left heart failure. The bolus tracking system C.A.R.E.-bolus often shows atypical Hounsfield attenuation in cases of cardiac failure but is not suitable as a screening method of the cardiopulmonary function.

Neuroimaging of NREM Sleep in Primary Insomnia: A Tc-99-HMPAO Single Photon Emission Computed Tomography Study

The objectives of this study were to: 1) demonstrate the feasibility of combining polysomnography and SPECT neuroimaging to study NREM sleep in primary insomnia and 2) evaluate possible functional CNS abnormalities associated with insomnia. Patients with insomnia and good sleeper controls were studied polysomnographically for three nights with a whole brain SPECT Scan of NREM sleep on Night 3. Groups were screened for medical/psychiatric history, substance use, and matched on age, body mass index, and education. Sleep Research Laboratory and Nuclear Medicine Center Nine females, 5 patients with chronic psychophysiologic insomnia and 4 healthy good sleepers (mean age 36 years, SD 12, range 27-55). N/A. Tomographs of regional cerebral blood flow during the 1st NREM sleep cycle were successfully obtained. Contrary to our expectations, patients with insomnia showed a consistent pattern of hypoperfusion across all 8 pre-selected regions of interest, with particular deactivation in the basal ganglia (p=.006). The frontal medial, occipital, and parietal cortices also showed significant decreases in blood flow compared to good sleepers (p<.05). Subjects with insomnia had decreased activity in the basal ganglia relative to the frontal lateral cortex, frontal medial cortex, thalamus, occipital and parietal cortices (p<.05). This study demonstrated the feasibility of combining neuroimaging and polysomnography to study cerebral activity in chronic insomnia. These preliminary results suggest that primary insomnia may be associated with abnormal central nervous system activity during NREM sleep that is particularly linked to basal ganglia dysfunction.

FFT regression and cross-noise reduction for comparing images in remote sensing

In many remote sensing studies it is desired to quantify the functional relationship between images of a given target that were acquired by different sensors. Such comparisons are problematic because when the pixel values of one image are plotted versus the other, the 'cross-noise' is quite high. Typically, the correlation coefficient is quite low, even when the compared images look alike. Nevertheless, we can try to quantify the functional relationship between two images by a suitable regression model function Y = f ( X ), while choosing one of them as 'the reference' Y and using the other one as a 'predictor' X . The underlying assumption of classical regression is that Y is absolutely correct while X is erroneous. Thus, the objective is to fit X to Y by choosing the parameters of Y = f ( X ), which minimize the 'residuals' ( “ - Y ). When comparing images in remote sensing this objective is not valid because Y itself is error prone. The alternative FFT regression method presented herein comprises a two-stage sensor fusion approach, whereby the initially low correlation between X and Y is increased and the residuals are dramatically decreased. First, pairwise image transforms are applied to X and Y whereby the correlation coefficient is increased, e.g. from roughly 0.4 to about 0.8-0.85. A predicted image Y fft is then derived by least squares minimization between the amplitude matrices of X and Y, via the 2D FFT. In the second stage, there are two options: For one time predictions, the phase matrix of Y is combined with the amplitude matrix of Y fft, whereby an improved predicted image Y plock is formed. Usually, the residuals of Y plock versus Y are about half of the values of Y fft versus Y . For long term predictions, the phase matrix of a 'field mask' is combined with the amplitude matrices of the reference image Y and the predicted image Y fft . The field mask is a binary image of a pre-selected region of interest in X and Y . The resultant images Y pref and Y pred are modified versions of Y and Y fft respectively. The residuals of Y pred versus Y pref are even lower than the residuals of Y plock versus Y . Images Y pref and Y pred represent a close consensus of two independent imaging methods which view the same target. The practical utility of FFT regression is demonstrated by examples wherein remotely sensed NDVI images X are used for predicting yield distributions in agricultural fields. Reference yield maps Y were derived by yield monitors which measure the flow rate of the crop while it is being harvested. The 2D FFT transforms, as well as other mathematical operations in this paper were performed in the 'MATLAB' environment.

Optimized Enhancement in Helical CT: Experiences With a Real-Time Bolus Tracking System in 628 Patients

AIMS: Ultrafast detector technology enables bolus-triggered application of contrast media. In a prospective study we investigated the benefit of this new method with the intention of optimizing enhancement during examination of the chest and abdomen.MATERIALS AND METHODS: In total, we examined 548 patients under standardized conditions. All examinations were performed on a Somatom Plus 4 Power CT system (Siemens Corp., Forchheim, Germany) using the CARE-Bolus software. This produces repetitive low-dose test images (e.g. for the lung: 140kV, 43mA, TI 0.5s) and measures the Hounsfield attenuation in a pre-selected region of interest. After exceeding a defined threshold, a diagnostic spiral CT examination was begun automatically. The data obtained from 321 abdominal CT and 179 lung CT examinations were correlated with different parameters such as age, weight and height of the patients and parameters of vascular access. In a group of 80 patients, the injection of contrast medium was stopped after reaching a pre-defined threshold of an increase of 100HU over the baseline. Then, we assessed the maximal enhancement of liver, pulmonal artery trunk and aortic arch.RESULTS: There was no correlation between bolus geometry and age, body surface or weight. In helical CT of the abdomen the threshold was reached after a mean trigger time of 27s (range 13–67s) and only 65ml (range 41–105ml) of contrast medium were administered. In helical CT of the lung the threshold was reached after 21s (range 12–48s) and the mean amount of administered contrast medium was 48ml (range 38–71ml).CONCLUSION: Bolus triggering allows optimized enhancement of the organs and reduces the dose of contrast material required compared with standard administration.Kirchner, J. (2000). Clinical Radiology55, 368–373.

Evaluation of soft-tissue masses using segmented color Doppler velocity images: preliminary observations.

We report our initial experience with segmented color Doppler velocity-based estimates of tumor vascularity for various histogically proven soft-tissue masses. Color Doppler sonography of 23 histologically proven masses in 22 patients was performed. Digital color Doppler images were acquired directly off the scanner output or from video recordings and stored on a personal computer as 24-bit gray-scale and color composite images. A color Doppler velocity segmentation and analysis algorithm was applied to the digital images, from which we calculated the normalized percentage of color Doppler area. Normalization was determined by expressing color Doppler area as a percentage of the area enclosed by a preselected region of interest. We also calculated mean percentage, SD, and cumulative distribution of color Doppler area, relative to a fixed threshold, for the acquired image data sets. Estimates of mean percentage of color Doppler area showed a dynamic range of at least two or three orders of magnitude between lowest and highest values obtained. A scatterplot of mean percentage of color Doppler area versus SD of percentage of color Doppler area showed a linear monotonic relationship (r2 = .92), illustrating increasing vascular heterogeneity with mean vascularity. Preliminary data also suggest the presence of at least two distinct groups of masses (p < .0001) based on these vascularity estimates. One group corresponds to high-grade lesions in which tumor angiogenesis is expected to be important in predicting biologic behavior. The second group appeared to have little or no relationship to tumor vascularity or was of an intermediate (or lower) histologic grade. Quantitative color Doppler estimates of tumor vascularity can be obtained over a wide dynamic range. Such estimates provide a mechanism to assess vascular heterogeneity of soft-tissue tumors. Preliminary data suggest that two biologically distinct groups of masses may be separable on the basis of quantitative velocity-based estimates of tumor vascularity as obtained from color Doppler sonography.

Determination of changes in tumor blood perfusion after hydralazine treatment by dynamic paramagnetic-enhanced magnetic resonance imaging

Magnetic resonance imaging, using the paramagnetic chelate gadopentetate dimeglumine as a perfusing agent, was used to investigate the effect of the vasoactive drug hydralazine on tumor blood perfusion. The method requires measurements of the magnetic resonance image intensity changes with time on a pre-selected region of interest in the tumor image, immediately following intravenous injection of gadopentetate dimeglumine. The present study showed that the initial slope of the intensity-time curve can be used, to a first approximation, to infer tumor blood perfusion. With the dynamic imaging technique, it was demonstrated that, in the KHT sarcoma implanted intramuscularly in the hind leg of C3H/HeN mice, intraperitoneal administration of hydralazine reduced the volume-averaged tumor blood perfusion in a dose-dependent manner. The intrinsically high spatial resolution of magnetic resonance imaging allows a detailed study of the heterogeneous nature of tumor blood perfusion. The potential applications of this imaging technique to study the differential effects of hydralazine on perfusion between tumor and normal tissues will be discussed. The clinical utility of the technique should be promising because of its non-invasive nature.