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Biomedical subjects

Michael H Buonocore

Publications and source records attributed to Michael H Buonocore.

At least 19 recordsLinked to original sources
PubMed2007

Comparison of the neural basis for imagined writing and drawing.

Drawing and writing are complex processes that require the synchronization of cognition, language, and perceptual-motor skills. Drawing and writing have both been utilized in the treatment of aphasia to improve communication. Recent research suggests that the act of drawing an object facilitated naming, whereas writing the word diminished accurate naming in individuals with aphasia. However, the relationship between object drawing and subsequent phonological output is unclear. Although the right hemisphere is characteristically mute, there is evidence from split-brain research that the right hemisphere can integrate pictures and words, likely via a semantic network. We hypothesized that drawing activates right hemispheric and left perilesional regions that are spared in aphasic individuals and may contribute to semantic activation that supports naming. Eleven right-handed subjects participated in a functional MRI (fMRI) experiment involving imagined drawing and writing and 6 of the 11 subjects participated in a second fMRI experiment involving actual writing and drawing. Drawing and writing produced very similar group activation maps including activation bilaterally in the premotor, inferior frontal, posterior inferior temporal, and parietal areas. The comparison of drawing vs. writing revealed significant differences between the conditions in areas of the brain known for language processing. The direct comparison between drawing and writing revealed greater right hemisphere activation for drawing in language areas such as Brodmann area (BA) 46 and BA 37.

Adult↗
PubMed2006

Attentional control and brain metabolite levels in methamphetamine abusers.

BACKGROUND: Methamphetamine abuse is associated with neurotoxicity to frontostriatal brain regions with concomitant deleterious effects on cognitive processes. METHODS: By using a computerized measure of selective attention and single-voxel proton magnetic resonance spectroscopy, we examined the relationship between attentional control and brain metabolite levels in the anterior cingulate cortex (ACC) and primary visual cortex (PVC) in 36 currently abstinent methamphetamine abusers and 16 non-substance-using controls. RESULTS: The methamphetamine abusers exhibited reduced attentional control (i.e., increased Stroop interference) compared with the controls (p = .04). Bonferroni-adjusted comparisons revealed that ACC levels of N-acetyl aspartate (NAA)-creatine and phosphocreatine (Cr) were lower and that levels of choline (Cho)-NAA were higher in the methamphetamine abusers compared with the controls, at the adjusted p value of .0125. Levels of NAA-Cr, but not of Cho-NAA, within the ACC correlated with measures of attentional control in the methamphetamine abusers (r = -.41; p = .01) but not in controls (r = .22; p = .42). No significant correlations were observed in the PVC (methamphetamine abusers, r = .19; p = .28, controls, r = .38; p = .15). CONCLUSIONS: Changes in neurochemicals within frontostriatal brain regions including ACC may contribute to deficits in attentional control among chronic methamphetamine abusers.

Adult↗
PubMed2006

Brain lactate responses during visual stimulation in fasting and hyperglycemic subjects: a proton magnetic resonance spectroscopy study at 1.5 Tesla.

Proton magnetic resonance spectroscopy ((1)H-MRS) studies showing increased lactate during neural activation support a broader role for lactate in brain energy metabolism than was traditionally recognized. Proton MRS measures of brain lactate responses have been used to study regional brain metabolism in clinical populations. This study examined whether variations in blood glucose influence the lactate response to visual stimulation in the visual cortex. Six subjects were scanned twice, receiving either saline or 21% glucose intravenously. Using (1)H-MRS at 1.5 Tesla with a long echo time (TE=288 ms), the lactate doublet was visible at 1.32 ppm in the visual cortex of all subjects. Lactate increased significantly from resting to visual stimulation. Hyperglycemia had no effect on this increase. The order of the slice-selective gradients for defining the spectroscopy voxel had a pronounced effect on the extent of contamination by signal originating outside the voxel. The results of this preliminary study demonstrate a method for observing a consistent activity-stimulated increase in brain lactate at 1.5 T and show that variations in blood glucose across the normal range have little effect on this response.

Adult↗
PubMed2006

The intersubject and intrasubject reproducibility of FMRI activation during three encoding tasks: implications for clinical applications.

The goal of the present study was to evaluate the inter- and intrasubject reproducibility of FMRI activation for three memory encoding tasks previously used in the context of presurgical functional mapping. The primary region of interest (ROI) was the medial temporal lobe (MTL). Comparative ROIs included the inferior frontal and fusiform gyri which are less affected by susceptibility-induced signal losses than the MTL regions. Eighteen subjects were scanned using three memory encoding paradigms: word-pair, pattern, and scene encoding. Nine subjects underwent repeat scanning. Intersubject reproducibility of FMRI activation was evaluated by examining the percent of subjects who showed activation within a given ROI and the range to which individual laterality indices (LIs) varied from the mean. Intrasubject test-retest reproducibility was evaluated by examining the LI test-retest correlation, the average difference between LIs from two separate imaging sessions, and concordance ratios of activation volumes (R(volume) and R(overlap)). For scene encoding the reproducibility of activation volume and LIs within the MTL were as good as or better than the reproducibility within the fusiform and inferior frontal ROIs. For pattern encoding and word-pair encoding, the reproducibility of activation volume and LIs within the MTL tended to be worse compared to the fusiform and inferior frontal ROIs. The differences in FMRI reproducibility appeared more dependent on the task than the susceptibility effects. The results of this study suggest that FMRI-based assessment of the neural substrates of memory using a scene encoding task may be a useful clinical tool.

Acoustic Stimulation↗
PubMed2006

Frequency of sub-clinical cerebral edema in children with diabetic ketoacidosis.

Symptomatic cerebral edema occurs in approximately 1% of children with diabetic ketoacidosis (DKA). However, asymptomatic or subclinical cerebral edema is thought to occur more frequently. Some small studies have found narrowing of the cerebral ventricles indicating cerebral edema in most or all children with DKA, but other studies have not detected narrowing in ventricle size. In this study, we measured the intercaudate width of the frontal horns of the lateral ventricles using magnetic resonance imaging (MRI) in children with DKA during treatment and after recovery from the DKA episode. We determined the frequency of ventricular narrowing and compared clinical and biochemical data for children with and without ventricular narrowing. Forty-one children completed the study protocol. The lateral ventricles were significantly smaller during DKA treatment (mean width, 9.3 +/- 0.3 vs. 10.2 +/- 0.3 mm after recovery from DKA, p < 0.001). Children with ventricular narrowing during DKA treatment (22 children, 54%) were more likely to have mental status abnormalities than those without narrowing [12/22 vs. 4/19 with Glasgow Coma Scale (GCS) scores below 15 during therapy, p = 0.03]. Multiple logistic regression analysis revealed that a lower initial PCO2 level was significantly associated with ventricular narrowing [odds ratio (OR) = 0.88, 95% confidence interval (95% CI) = 0.78-0.99, p = 0.047). No other variables analyzed were associated with ventricular narrowing in the multivariate analysis. We conclude that narrowing of the lateral ventricles is evident in just over half of children being treated for DKA. Although children with ventricular narrowing did not exhibit neurological abnormalities sufficient for a diagnosis of 'symptomatic cerebral edema', mild mental status abnormalities occurred frequently, suggesting that clinical evidence of cerebral edema in children with DKA may be more common than previously reported.

Adolescent↗
PubMed2005

Hippocampal volume is preserved and fails to predict recognition memory impairment in aged rhesus monkeys (Macaca mulatta).

Aged monkeys exhibit deficits in memory mediated by the medial temporal lobe system, similar to the effects of normal aging in humans. The contribution of structural deterioration to age-associated memory loss was explored using magnetic resonance imaging techniques. We quantified hippocampal, cerebral and ventricular volumes in young (n = 6, 9-12 years) and aged (n = 6, 24-29 years) rhesus monkeys. Eleven subjects were tested on a recognition memory task, delayed non-matching-to-sample (DNMS). Compared to young animals, aged monkeys exhibited robust learning deficits and significant memory impairments when challenged with longer retention intervals. Hippocampal volume was statistically equivalent across age groups, differing by less than 6%, and there was no correlation between this measure and DNMS performance. Variability in cerebral volume was greater in the aged compared to young monkeys and this parameter was marginally correlated with DNMS performance with a 10-min delay. These findings confirm and extend the conclusion of recent post-mortem histological analyses demonstrating that normal cognitive aging occurs independently of gross structural deterioration in the primate hippocampus.

Aging↗
PubMed2005

Methamphetamine users in sustained abstinence: a proton magnetic resonance spectroscopy study.

BACKGROUND: Abnormal patterns of metabolite levels have been detected by magnetic resonance spectroscopy in frontostriatal regions of individuals meeting DSM-IV criteria for methamphetamine dependence, but less is known about the effects of drug abstinence on metabolite levels. OBJECTIVE: To assess the effects of long-term methamphetamine use and drug abstinence on brain metabolite levels. DESIGN: To assess regional specific metabolite levels using magnetic resonance spectroscopy imaging techniques in 2 groups of currently abstinent methamphetamine users: methamphetamine users who recently initiated abstinence and methamphetamine users who had initiated abstinence more than 1 year prior to study. SETTING: Participants were recruited from outpatient substance abuse treatment centers. PARTICIPANTS: Eight methamphetamine users with sustained abstinence (1 year to 5 years) and 16 recently abstinent methamphetamine users (1 month to 6 months) were compared with 13 healthy, non-substance-using controls. MAIN OUTCOME MEASURES: Magnetic resonance spectroscopy measures of N-acetylaspartate-creatine and phosphocreatine (NAA/Cr), choline-creatine and phosphocreatine (Cho/Cr), and choline-N-acetylaspartate (Cho/NAA) ratios were obtained in the anterior cingulate cortex as well as in the primary visual cortex, which served as a control region. RESULTS: The absolute values of Cr did not differ between controls and methamphetamine users. Methamphetamine users had abnormally low NAA/Cr levels within the anterior cingulate cortex, regardless of the time spent abstinent (F(2,34) = 12.61; P<.001). No NAA/Cr group differences were observed in the primary visual cortex (F(2,33) = 0.29; P = .75). The Cho/NAA values for the anterior cingulate cortex were abnormally high in the methamphetamine users who recently initiated abstinence but followed a normal pattern in the methamphetamine users who had initiated abstinence more than 1 year prior to study (F(2,34) = 7.31; P = .002). CONCLUSIONS: The relative choline normalization across periods of abstinence suggests that following cessation of methamphetamine use, adaptive changes occur, which might contribute to some degree of normalization of neuronal structure and function in the anterior cingulum. More research is needed to elucidate the mechanisms underlying these adaptive changes.

Adult↗
PubMed2005

Estimation of extraction fraction (EF) and glomerular filtration rate (GFR) using MRI: considerations derived from a new Gd-chelate biodistribution model simulation.

Previous reports have described the use of magnetic resonance imaging (MRI) to estimate single-kidney extraction fraction (EF) and glomerular filtration rate (GFR), by measuring the concentration difference of intravenously injected Gd-chelate ([Gd]) in the renal artery and renal vein from measurements of blood T1. Problematic is the fact that [Gd] measurements in the renal artery are often inaccurate due to the small size, tortuousness and motion of the vessel. Consequently, the [Gd] in the inferior vena cava (IVC) below the renal vein ostia (i.e., the infrarenal IVC) has been used instead of the renal artery [Gd], based on the assumption that the [Gd] in the infrarenal IVC is the same as it is in the renal artery. However, this assumption has neither been theoretically nor experimentally investigated. Herein, we describe new difference and differential equation pharmacological models that can predict the biodistribution of Gd-chelate throughout the extracellular space. Assuming known average normal blood flows and GFR, our models predict that the infrarenal IVC [Gd] is 3.2% to 4.7% greater than the renal artery [Gd], and that the EF estimate using this IVC measurement is overestimated by 14.2%-20.0%. To support these predictions, algebraic equations are derived which show that the infrarenal IVC must develop a relatively high [Gd] in order to satisfy Gd flux constraints within the vascular system. These results suggest that the infrarenal IVC [Gd] is not a valid substitute for the renal artery [Gd].

Algorithms↗
PubMed2005

Detection of cerebral {beta}-hydroxy butyrate, acetoacetate, and lactate on proton MR spectroscopy in children with diabetic ketoacidosis.

BACKGROUND AND PURPOSE: Ketone bodies provide important alternate fuel for brain metabolism, and their transport into the brain increases with prolonged fasting. During diabetic ketoacidosis (DKA), serum ketone concentrations markedly increase; however, little is known about whether ketone bodies accumulate in cerebral tissues during DKA. We used proton MR spectroscopy (MRS) to detect cerebral beta-hydroxy butyrate (betaOHB) and acetone/acetocaetate (AcAc) in children with DKA. METHODS: Twenty-five children underwent brain MRS: nine within 4 hours of the start of treatment for DKA; 11, at 4-8 hours; and five, at 8-12 hours. MRS was repeated after their recovery from the DKA episode at > or =72 hours after the start of treatment. MRS was evaluated for peaks corresponding to betaOHB (doublet centered on 1.20 ppm) and lactate (doublet centered on 1.33 ppm). Difference spectroscopy was used to identify the AcAc peak at 2.22-2.26 ppm. RESULTS: betaOHB was detected in 13 children (52%), more frequently within 4 hours (eight children, 89%) than after 4 hours (five children, 31%). AcAc was detected in 15 children (60%), more frequently at >4 hours after the start of treatment (12 patients, 75%) than in the first 4 hours (three patients, 33%). Lactate was detected in five children (18%), all within the first 8 hours of treatment. CONCLUSION: In children, betaOHB and AcAc accumulate in the brain during DKA, and they can be detected on MRS. Care should be taken in interpreting MRS results in patients with DKA to avoid erroneously attributing betaOHB peaks to lactate.

3-Hydroxybutyric Acid↗
PubMed2004

The amygdala is enlarged in children but not adolescents with autism; the hippocampus is enlarged at all ages.

Autism is a neurodevelopmental disorder characterized by impairments in reciprocal social interaction, deficits in verbal and nonverbal communication, and a restricted repertoire of activities or interests. We performed a magnetic resonance imaging study to better define the neuropathology of autistic spectrum disorders. Here we report findings on the amygdala and the hippocampal formation. Borders of the amygdala, hippocampus, and cerebrum were defined, and their volumes were measured in male children (7.5-18.5 years of age) in four diagnostic groups: autism with mental retardation, autism without mental retardation, Asperger syndrome, and age-matched typically developing controls. Although there were no differences between groups in terms of total cerebral volume, children with autism (7.5-12.5 years of age) had larger right and left amygdala volumes than control children. There were no differences in amygdala volume between the adolescent groups (12.75-18.5 years of age). Interestingly, the amygdala in typically developing children increases substantially in volume from 7.5 to 18.5 years of age. Thus, the amygdala in children with autism is initially larger, but does not undergo the age-related increase observed in typically developing children. Children with autism, with and without mental retardation, also had a larger right hippocampal volume than typically developing controls, even after controlling for total cerebral volume. Children with autism but without mental retardation also had a larger left hippocampal volume relative to controls. These cross-sectional findings indicate an abnormal program of early amygdala development in autism and an abnormal pattern of hippocampal development that persists through adolescence. The cause of amygdala and hippocampal abnormalities in autism is currently unknown.

Adolescent↗
PubMed2004

Investigation of neuroanatomical differences between autism and Asperger syndrome.

BACKGROUND: Autism and Asperger syndrome (ASP) are neurobiological conditions with overlapping behavioral symptoms and of unknown etiologies. Results from previous autism neuroimaging studies have been difficult to replicate, possibly owing to site differences in subject samples, scanning procedures, and image-processing methods. We sought (1) to determine whether low-functioning autism (LFA; IQ<70), high-functioning autism (HFA; IQ>or=70), and ASP constitute distinct biological entities as evidenced by neuroanatomical measures, and (2) to assess for intersite differences. METHODS: Case-control study examining coronally oriented 124-section spoiled gradient echo images acquired on 3 magnetic resonance imaging (MRI) systems, and processed by BrainImage 5.X. Participants were recruited and underwent scanning at 2 academic medicine departments. Participants included 4 age-matched groups of volunteer boys aged 7.8 to 17.9 years (13 patients with LFA, 18 with HFA, 21 with ASP, and 21 control subjects), and 3 volunteer adults for neuroimaging reliability. Main outcome measures included volumetric measures of total, white, and gray matter for cerebral and cerebellar tissues. RESULTS: Intersite differences were seen for subject age, IQ, and cerebellum measures. Cerebral gray matter volume was enlarged in both HFA and LFA compared with controls (P =.009 and P =.04, respectively). Cerebral gray matter volume in ASP was intermediate between that of HFA and controls, but nonsignificant. Exploratory analyses revealed a negative correlation between cerebral gray matter volume and performance IQ within HFA but not ASP. A positive correlation between cerebral white matter volume and performance IQ was observed within ASP but not HFA. CONCLUSIONS: Lack of replication between previous autism MRI studies could be due to intersite differences in MRI systems and subjects' age and IQ. Cerebral gray tissue findings suggest that ASP is on the mild end of the autism spectrum. However, exploratory assessments of brain-IQ relationships reveal differences between HFA and ASP, indicating that these conditions may be neurodevelopmentally different when patterns of multiple measures are examined. Further investigations of brain-behavior relationships are indicated to confirm these findings.

Adolescent↗
PubMed2004

Four-dimensional magnetic resonance velocity mapping of blood flow patterns in the aorta in patients with atherosclerotic coronary artery disease compared to age-matched normal subjects.

PURPOSE: To test the hypothesis that age and atherosclerotic coronary artery disease (CAD) may influence aortic blood flow patterns. MATERIALS AND METHODS: A total of 21 patients with CAD, 37-86 years old, were studied, together with 20 age-matched normal subjects. Time-resolved, three-direction velocity data over an entire volume were obtained with sequential single-slice two-dimensional cardiac-gated magnetic resonance (MR) velocity-encoded phase-contrast sequences. RESULTS: In both normal subjects and CAD patients, the time it took for particles to travel from aortic valve to descending aorta was significantly longer in the elderly age group than in the younger (37-46 years old). This time was significantly longer in patients than in normal subjects. Systolic velocities were significantly higher in young normal subjects than in elderly normal subjects, and significantly lower in CAD patients than in age-matched normal subjects. Retrograde velocity was higher in CAD patients than in normal subjects, and higher in elderly CAD patients than in young. CONCLUSION: CAD patients have abnormal blood flow patterns in the aorta compared with age-matched normal subjects, especially young patients ages 37-46. The aging process has a similar effect on blood flow patterns as atherosclerosis. Ascending aorta flow is chaotic in some very elderly normal subjects and in CAD patients of all ages. Chaotic aortic flow may result in reduced blood flow into the coronary arteries.

Adult↗
PubMed2004

Mechanism of cerebral edema in children with diabetic ketoacidosis.

OBJECTIVES: Cerebral edema during diabetic ketoacidosis (DKA) has been attributed to osmotic cellular swelling during treatment. We evaluated cerebral water distribution and cerebral perfusion during DKA treatment in children. STUDY DESIGN: We imaged 14 children during DKA treatment and after recovery, using both diffusion and perfusion weighted magnetic resonance imaging (MRI). We assessed the apparent diffusion coefficients (ADCs) and measures reflecting cerebral perfusion. RESULTS: The ADC was significantly elevated during DKA treatment (indicating increased water diffusion) in all regions except the occipital gray matter. Mean reductions in the ADC from initial to postrecovery MRI were: basal ganglia 4.7 +/- 2.5 x 10(-5) mm(2)/s (P=.002), thalamus 3.7 +/- 2.8 x 10(-5) mm(2)/s, (P=.002), periaqueductal gray matter 4.3 +/- 5.1 x 10(-5) mm(2)/s (P=.03), and frontal white matter 2.0 +/- 3.1 x 10(-5) mm(2)/s (P=.03). In contrast, the ADC in the occipital gray matter increased significantly from the initial to postrecovery MRI (mean increase 3.9 +/- 3.9 x 10(-5) mm(2)/s, P=.004). Perfusion MRI during DKA treatment revealed significantly shorter mean transit times (MTTs) and higher peak tracer concentrations, possibly indicating increased cerebral blood flow (CBF). CONCLUSIONS: Elevated ADC values during DKA treatment suggests a vasogenic process as the predominant mechanism of edema formation rather than osmotic cellular swelling.

Adolescent↗
PubMed2003

Brain regions showing increased activation by threat-related words in panic disorder.

Threat-related stimuli consistently activate the posterior cingulate cortex in normal subjects and have exaggerated effects on memory in patients with panic disorder. We hypothesized that panic patients would show increased response to threat-related stimuli in the posterior cingulate cortex. While undergoing fMRI, six panic patients and eight healthy volunteers made valence judgements of threat-related and neutral words. Both groups showed threat-related activation in the left posterior cingulate and left middle frontal cortices, but the activation was significantly greater in panic patients. Panic patients also had more right>left asymmetry of activation in the mid-parahippocampal region. The increased responsivity observed in the posterior cingulate and dorsolateral prefrontal cortices is consistent with the hypothesis that panic disorder patients engage in more extensive memory processing of threat-related stimuli.

Adult↗
PubMed2003

Posterior cingulate cortex activation by emotional words: fMRI evidence from a valence decision task.

Functional imaging studies consistently find that emotional stimuli activate the posterior cingulate cortex, a region that appears to have memory-related functions. However, prior imaging studies have not controlled for non-emotional stimulus features that might activate this region by engaging memory processes unrelated to emotion. This study examined whether emotional words activated the posterior cingulate cortex when these potentially confounding factors were controlled. Sixty-four pleasant and 64 unpleasant words were matched with neutral words on non-emotional features known to influence memory. Eight subjects underwent block-designed functional magnetic resonance imaging scans while evaluating the valence of these words. The posterior cingulate cortex was significantly activated bilaterally during both unpleasant and pleasant compared to neutral words. The strongest activation peak with both unpleasant and pleasant words was observed in the left subgenual cingulate cortex. Anteromedial orbital and left inferior and middle frontal cortices were also activated by both pleasant and unpleasant words. Right amygdala and auditory cortex were activated only by unpleasant words, while left frontal pole was activated only by pleasant words. The results show that activation of the posterior cingulate cortex by emotional stimuli cannot be attributed to the memory-enhancing effects of non-emotional stimulus features. The findings are consistent with the suggestion that this region may mediate interactions of emotional and memory-related processes. The results also extend prior findings that evaluating emotional words consistently activates the subgenual cingulate cortex, and suggest a means of probing this region in patients with mood disorders.

Acoustic Stimulation↗
PubMed2003

Breast tissue differentiation using arterial spin tagging.

An arterial spin tagging (AST) pulse sequence has been developed to measure T(1) and relative blood perfusion. This full sequence is composed of three sequences: selective tagging, nonselective tagging, and nontagging. Perfusion quantification error resulting from imperfect inversion and acquisition slice profiles has been addressed in the literature. In this work, the error is reduced through the application of optimized Shinnar-Le Roux (SLR) RF pulses and a semi-log linear regression data-processing technique. A threshold approach based on the breast tissue T(1) and relative blood perfusion is introduced to show that these two parameters can be applied to breast tissue differentiation and potentially to cancer detection.

Breast↗
PubMed2003

Cortical, medullary, and pelvocaliceal MR renography with and without diuretic modification.

RATIONALE AND OBJECTIVES: This study was conducted to define and characterize magnetic resonance (MR) contrast medium enhancement of the renal cortex, medulla, and pelvocaliceal system in normal and hydronephrotic kidneys with and without furosemide administration. MATERIALS AND METHODS: In 30 subjects known or suspected to have unilateral hydronephrosis and normal serum creatinine levels, multiple timed sets of coronal fast spoiled gradient-echo images were acquired before and after contrast medium administration. MR renograms were derived from changes in the signal intensity (SI) of the cortex, medulla, and pelvocaliceal system. Ten subjects received 40 mg of intravenous furosemide approximately 10 minutes before contrast medium administration. RESULTS: The following values were significantly different between subjects who were given furosemide and those who were not: the peak cortical, medullary, and pelvocaliceal system SIs measured in the normal kidneys during the 4 1/2 minutes following contrast medium administration (163.2 +/- 17.7 [mean arbitrary units plus or minus standard error] vs 120.5 +/- 10.2 [P = .033], 155.5 +/- 18.8 vs 111.5 +/- 9.4 [P = .025], and 332.5 +/- 27.2 vs 229.3 +/- 31.9 [P = .026], respectively); the crossover time between the SI curves of the pelvocaliceal system and the medulla in the normal kidney (2.45 minutes +/- 0.2 vs 3.27 minutes +/- 0.25 [P = .02]); and the peak SIs of the cortex, medulla, and pelvocaliceal system in the unilateral obstructive hydronephrotic kidneys throughout the first 4 1/2 minutes after contrast medium administration (174.6 +/- 16.4 vs 90.6 +/- 13.7 [P = .003], 117.6 +/- 14.1 vs 86.7 +/- 11.8 [P = .015], and 337.2 +/- 41.4 vs 143.1 +/- 74.4 [P = .034], respectively). CONCLUSION: MR renography can be used to depict three separate components of renal enhancement: cortical, medullary, and pelvocaliceal. Furosemide-induced diuresis increases renal parenchymal and pelvocaliceal SI and urinary flow rates.

Adult↗