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Henry Rusinek

Publications and source records attributed to Henry Rusinek.

At least 19 recordsLinked to original sources
PubMed2007

Hippocampal hypometabolism predicts cognitive decline from normal aging.

OBJECTIVE: This longitudinal study used FDG-PET imaging to predict and monitor cognitive decline from normal aging. METHODS: Seventy-seven 50-80-year-old normal (NL) elderly received longitudinal clinical examinations over 6-14 years (561 person-years, mean per person 7.2 years). All subjects had a baseline FDG-PET scan and 55 subjects received follow-up PET exams. Glucose metabolic rates (MRglc) in the hippocampus and cortical regions were examined as predictors and correlates of clinical decline. RESULTS: Eleven NL subjects developed dementia, including six with Alzheimer's disease (AD), and 19 declined to mild cognitive impairment (MCI), on average 8 years after the baseline exam. The baseline hippocampal MRglc predicted decline from NL to AD (81% accuracy), including two post-mortem confirmed cases, from NL to other dementias (77% accuracy), and from NL to MCI (71% accuracy). Greater rates of hippocampal and cortical MRglc reductions were found in the declining as compared to the non-declining NL. CONCLUSIONS: Hippocampal MRglc reductions using FDG-PET during normal aging predict cognitive decline years in advance of the clinical diagnosis. Future studies are needed to increase preclinical specificity in differentiating dementing disorders.

Aged↗
PubMed2007

Renal function measurements from MR renography and a simplified multicompartmental model.

The purpose of this study was to determine the accuracy and sources of error in estimating single-kidney glomerular filtration rate (GFR) derived from low-dose gadolinium-enhanced T1-weighted MR renography. To analyze imaging data, MR signal intensity curves were converted to concentration vs. time curves, and a three-compartment, six-parameter model of the vascular-nephron system was used to analyze measured aortic, cortical, and medullary enhancement curves. Reliability of the parameter estimates was evaluated by sensitivity analysis and by Monte Carlo analyses of model solutions to which random noise had been added. The dominant sensitivity of the medullary enhancement curve to GFR 1-4 min after tracer injection was supported by a low coefficient of variation in model-fit GFR values (4%) when measured data were subjected to 5% noise. These analyses also showed the minimal effects of bolus dispersion in the aorta on parameter reliability. Single-kidney GFR from MR renography analyzed by the three-compartment model (4.0-71.4 ml/min) agreed well with reference measurements from (99m)Tc-DTPA clearance and scintigraphy (r = 0.84, P < 0.001). Bland-Altman analysis showed an average difference of 11.9 ml/min (95% confidence interval = 5.8-17.9 ml/min) between model and reference values. We conclude that a nephron-based multicompartmental model can be used to derive clinically useful estimates of single-kidney GFR from low-dose MR renography.

Computer Simulation↗
PubMed2006

Early detection of Alzheimer's disease using neuroimaging.

Neuroimaging is being increasingly used to complement clinical assessments in the early detection of Alzheimer's disease (AD). Structural magnetic resonance imaging (MRI) and metabolic positron emission tomography (FDG-PET) are the most clinically used and promising modalities to detect brain abnormalities in individuals who might be at risk for AD but who have not yet developed symptoms. The knowledge of established risk factors for AD enabled investigators to develop enrichment strategies for longitudinal imaging studies to reduce the sample sizes and study duration. The present review focuses on the results obtained by MRI and FDG-PET studies that examined the preclinical AD stages in several at risk populations: (1) individuals from families with autosomal dominant early-onset AD (FAD), (2) patients with mild cognitive impairment (MCI), particularly in memory, who are at very high risk for declining to AD with an estimated decline rate of 10-30% per year, (3) normal young and middle-age subjects carriers of known susceptibility genes for late-onset AD such as the Apolipoprotein E (ApoE) E4 allele, and (4) as age is the main risk factor for AD, normal elderly individuals followed to the onset of MCI and AD. Overall, these studies show that the use of imaging for the early detection of AD is successful even in the earlier stages of disease when clinical symptoms are not fully expressed and the regional brain damage may be limited.

Alzheimer Disease↗
PubMed2006

Clinical significance of dilated Virchow-Robin spaces in mild traumatic brain injury.

PRIMARY OBJECTIVE: To investigate the relationship between the number of dilated Virchow-Robin spaces (VRS) and neurocognitive findings in patients with traumatic brain injury (TBI). RESEARCH DESIGN: Thirty-eight patients with TBI and 21 controls were studied. METHODS AND PROCEDURES: Fifteen patients underwent MRI within a mean interval of 5.4 (range 1-12) days from the brain injury and 23 after an average period of 5.5 (range 0.2-31) years. All subjects were examined with a battery of 13 neuropsychological tests (NP). MAIN OUTCOMES AND RESULTS: The average number of VRS was significantly higher in patients than in controls. There were no significant differences between patients and controls in terms of NP tests. The number of VRS showed a significant inverse correlation with processing speed and a positive correlation with visual perceptual of attention only in patients studied within a short delay of trauma. CONCLUSIONS: VRS are not directly associated to neurocognitive findings, suggesting that they may represent a result of the shear-strain injury.

Adolescent↗
PubMed2006

Effect of blood vessels on measurement of nodule volume in a chest phantom.

PURPOSE: To identify, by using a chest phantom, whether vessels that contact lung nodules measuring less than 5 mm in diameter will affect nodule volume assessment. MATERIALS AND METHODS: Forty synthetic nodules (20 with ground-glass attenuation and 20 with solid attenuation) that measured less than 5 mm in diameter were placed into a chest phantom either adjacent to (n = 30) or isolated from (n = 10) synthetic vessels. Nodules were imaged by using low-dose (20 mAs) and diagnostic (120 mAs) multi-detector row computed tomography (CT). Nodules that were known to lie in direct contact with vessels were confirmed by visual inspection. Nontargeted 1.25 x 1.00-mm sections were analyzed with a three-dimensional computer-assisted method for measuring nodule volume. A mixed-model analysis of variance was used to examine the influence of several factors (eg, the presence of adjacent vessels; tube current-time product; and nodule attenuation, diameter, and location) on measurement error. RESULTS: The mean absolute error (MAE) for all nodules adjacent to vessels was 2.3 mm(3), which was higher than the MAE for isolated nodules (1.9 mm(3)) (P < .001). This difference proved significant only for diagnostic CT (2.2 mm(3) for nodules adjacent to vessels vs 1.3 mm(3) for nodules isolated from vessels) (P < .05). A larger MAE was noted for nodules with ground-glass attenuation (2.3 mm(3)) versus those with solid attenuation (2.0 mm(3)), for increasing nodule volume (1.66 mm(3) for nodules smaller than 20 mm(3) vs 2.83 mm(3) for nodules larger than 40 mm(3)), and for posterior nodule location (P < .05). CONCLUSION: The presence of a vessel led to a small yet significant increase in volume error on diagnostic-quality images. This represents less than one-third of the overall error, even for nodules larger than 40 mm(3) or approximately 4 mm in diameter. This increase, however, may be more important for smaller nodules with errors of less than 3 mm(3).

Diagnostic Errors↗
PubMed2005

Appendicitis in children: low-dose CT with a phantom-based simulation technique--initial observations.

PURPOSE: To retrospectively determine the accuracy of low-dose (20-mAs) computed tomography (CT) in the diagnosis of acute appendicitis in children by using a technique that enables the simulation of human CT scans acquired at a lower tube current given the image acquired at a standard dose. MATERIALS AND METHODS: Institutional review board approval was obtained, informed consent was not required, and the study was HIPAA compliant. The authors reviewed 100 standard-dose pediatric abdominal-pelvic CT scans (50 positive and 50 negative scans) obtained in 100 patients and corresponding simulated low-dose (20-mAs) scans. The standard-dose scans were obtained for evaluation in patients suspected of having appendicitis. Scans were reviewed in randomized order by four experienced pediatric radiologists. The patients with positive findings included 21 girls (mean age, 9.2 years) and 29 boys (mean age, 8.4 years). The patients with negative findings included 28 girls (mean age, 9.2 years) and 22 boys (mean age, 8.4 years). Simulation was achieved by adding noise patterns from repeated 20-mAs scans of a pediatric pelvis phantom to the original scans obtained with a standard tube current. Observers recorded their confidence in the diagnosis of appendicitis by using a six-point scale. Dose-related changes were analyzed with generalized estimating equations and the nonparametric sign test. RESULTS: There was a statistically significant (P < .001, sign test) decrease in both sensitivity and accuracy with a lower tube current, from 91.5% with the original tube current to 77% with the lower tube current. A low dose was the only statistically significant (P < .001) risk factor for a false-negative result. The specificity was unchanged at 94% for both the images obtained with the original tube current and the simulated low-dose images. The overall accuracy decreased from 92% with the original dose to 86% with the low dose. CONCLUSION: Preliminary findings indicate that it is feasible to optimize the CT dose used to evaluate appendicitis in children by using phantom-based computer simulations.

Adolescent↗
PubMed2005

Effect of CT image compression on computer-assisted lung nodule volume measurement.

PURPOSE: To evaluate the effect of two-dimensional wavelet-based computed tomographic (CT) image compression according to the Joint Photographic Experts Group (JPEG) 2000 standard on computer-assisted assessment of nodule volume. MATERIALS AND METHODS: This HIPAA-compliant study was approved by the research board at the authors' institution; patients' informed consent was not required. Fifty-one nodules in 23 patients (seven men, 16 women; mean age, 59 years; age range, 39-75 years) were selected on low-dose CT scans that were compressed to levels of 10:1, 20:1, 30:1, and 40:1 by using a two-dimensional JPEG 2000 wavelet-based image compression method. Nodules were classified according to size (< or = 5 mm or > 5 mm in diameter), location (central, peripheral, or abutting pleura or fissures), and attenuation (solid, calcified, or subsolid). Regions of interest were placed on the original images and transposed onto compressed images. Nodule volumes on original (noncompressed) and compressed images were measured by using a computer-assisted method. A mixed-model analysis of variance was conducted for statistical evaluation. RESULTS: Nodule volumes averaged 388.1 mm3 (range, 34-3474 mm3). There were three calcified, 33 solid noncalcified, and 15 subsolid nodules (13 with ground-glass attenuation). Average volume decreased with increasing compression level, to 383 mm3 (10:1), 370 mm3 (20:1), 360 mm3 (30:1), and 354 mm3 (40:1). No significant difference was identified between measurements obtained on original images and those compressed to a level of 10:1. Significant differences were noted, however, between original images and those compressed to a level of 20:1 or greater (P < .05). Compression level significantly interacted with nodule size, location, and attenuation (P < .001). The effect of compression was greater for nodules with ground-glass attenuation than for those with higher attenuation values. The difference in mean volumes between original images and those compressed to a level of 20:1 was 34.9 mm3 for nodules with ground-glass attenuation, compared with 8.3 mm3 for higher-attenuation nodules, a 4.2-fold difference. CONCLUSION: Nodule volumes measured on images compressed to a level of 20:1 differed significantly from those measured on noncompressed images, especially for nodules with ground-glass attenuation. This difference could affect the assessment of nodule change in size as measured with computer-assisted methods.

Adult↗
PubMed2005

Automatic 4-D registration in dynamic MR renography based on over-complete dyadic wavelet and Fourier transforms.

Dynamic contrast-enhanced 4-D MR renography has the potential for broad clinical applications, but suffers from respiratory motion that limits analysis and interpretation. Since each examination yields at least over 10-20 serial 3-D images of the abdomen, manual registration is prohibitively labor-intensive. Besides in-plane motion and translation, out-of-plane motion and rotation are observed in the image series. In this paper, a novel robust and automated technique for removing out-of-plane translation and rotation with sub-voxel accuracy in 4-D dynamic MR images is presented. The method was evaluated on simulated motion data derived directly from a clinical patient's data. The method was also tested on 24 clinical patient kidney data sets. Registration results were compared with a mutual information method, in which differences between manually co-registered time-intensity curves and tested time-intensity curves were compared. Evaluation results showed that our method agreed well with these ground truth data.

Algorithms↗
PubMed2005

The role of quantitative structural imaging in the early diagnosis of Alzheimer's disease.

The goal of this article is to review the role of structural neuroimaging in the diagnosis of Alzheimer's disease (AD). We present relevant neuroanatomy, highlight progress in the domain of AD imaging, and review the clinical characteristics of the prodromal phase of AD. We describe the history of the diagnostic issue by examining at cross-section and longitudinally the differences between patients who have AD and normal controls. We also present how subsequent works applied these characteristic traits to the early detection of the prodromal disease and to prediction of future decline. The article delineates the differences between subjects who have mild cognitive impairment and AD, which illustrate the spreading of the pathology with disease progression. The last section describes problems encountered in the differential diagnosis.

Aged↗
PubMed2005

Perfusion imaging of the liver: current challenges and future goals.

Improved therapeutic options for hepatocellular carcinoma and metastatic disease place greater demands on diagnostic and surveillance tests for liver disease. Existing diagnostic imaging techniques provide limited evaluation of tissue characteristics beyond morphology; perfusion imaging of the liver has potential to improve this shortcoming. The ability to resolve hepatic arterial and portal venous components of blood flow on a global and regional basis constitutes the primary goal of liver perfusion imaging. Earlier detection of primary and metastatic hepatic malignancies and cirrhosis may be possible on the basis of relative increases in hepatic arterial blood flow associated with these diseases. To date, liver flow scintigraphy and flow quantification at Doppler ultrasonography have focused on characterization of global abnormalities. Computed tomography (CT) and magnetic resonance (MR) imaging can provide regional and global parameters, a critical goal for tumor surveillance. Several challenges remain: reduced radiation doses associated with CT perfusion imaging, improved spatial and temporal resolution at MR imaging, accurate quantification of tissue contrast material at MR imaging, and validation of parameters obtained from fitting enhancement curves to biokinetic models, applicable to all perfusion methods. Continued progress in this new field of liver imaging may have profound implications for large patient groups at risk for liver disease.

Carcinoma, Hepatocellular↗
PubMed2005

Dilated perivascular spaces: hallmarks of mild traumatic brain injury.

BACKGROUND AND PURPOSE: Recent animal and human studies have shown an increased frequency of enlarged, high-convexity Virchow-Robin spaces (VRS) in several neurologic diseases, suggesting their role as neuroradiologic markers of inflammatory changes. The aim of this study was to determine the prevalence of high-convexity dilated VRS in mild traumatic brain injury (TBI). METHODS: T2-weighted, T1-weighted, fluid-attenuated inversion recovery, and T2*-weighted gradient-echo brain MR images were acquired in 24 patients with TBI (10 women, 14 men; mean age, 33.6; range, 18.1-50.8 years) and 17 age- and sex-matched healthy control subjects (nine women, eight men; mean age, 32.8; range, 18.4-47.8 years). The mean interval after TBI was 3.6 days (range, 1-9 days) in 15 patients and 3.7 years (range, 0.6-13.4 years) in nine patients. Axial T2-weighted images were used to identify dilated VRS and to measure CSF volume; T1-weighted images were used to measure brain volume. Dilated VRS were identified as punctuate areas with CSF-like signal intensity in the high-convexity white matter. RESULTS: Mean (+/- standard deviation) number of VRS was significantly higher in patients (7.1 +/- 4.6) than in controls (3.0 +/- 3.0, P = 0.002) [corrected] In controls, VRS were associated with age (R = 0.69, P < .001) whereas in patients, they neither correlated with brain and CSF volumes nor with age and the elapsed time from injury. CONCLUSION: Our results suggest that the increased number of dilated VRS is a radiologic marker of mild head injury that is readily detectable on T2-weighted images. Because their number does not vary with time from injury, VRS probably reflect early and permanent brain changes.

Adolescent↗
PubMed2005

Assessing global invasion of newly diagnosed glial tumors with whole-brain proton MR spectroscopy.

BACKGROUND AND PURPOSE: Because of their invasive nature, high-grade glial tumors are uniformly fatal. The purpose of this study was to quantify MR imaging-occult, glial tumor infiltration beyond its radiologic margin through its consequent neuronal cell damage, assessed by the global concentration decline of the neuronal marker N-acetylaspartate (NAA). METHODS: Seventeen patients (10 men; median age, 39 years; age range, 23-79 years) with radiologically suspected (later pathologically confirmed) supratentorial glial neoplasms, and 17 age- and sex-matched controls were studied. Their whole-brain NAA (WBNAA) amounts were obtained with proton MR spectroscopy: for patients on the day of surgery (n = 17), 1 day postsurgery (n = 15), and once for each control. To convert into concentrations, suitable for intersubject comparison, patients' global NAA amounts were divided by their brain volumes segmented from MR imaging. Least squares regression was used to analyze the data. RESULTS: Pre- and postoperative WBNAA (mean +/- SD) of 9.2 +/- 2.1 and 9.7 +/- 1.8 mmol/L, respectively, in patients were indistinguishable (P = .369) but significantly lower than in controls (12.5 +/- 1.4 mmol/L). Mean resected tumor size (n = 15) was approximately 3% of total brain volume. CONCLUSION: The average 26% WBNAA deficit in the patients, which persisted following surgical resection, cannot be explained merely by depletion within the approximately 3% MR imaging-visible tumor volume or an age-dependent effect. Although there could be several possible causes of such widespread decline--perineuronal satellitosis, neuronal deafferentation, Wallerian and retrograde degeneration, vasogenic edema, functional diaschisis, secondary vascular changes--most are a direct or indirect reflection of extensive, MR imaging-occult, microscopic tumor cell infiltration, diffusely throughout the otherwise "normal-appearing" brain.

Adult↗
PubMed2005

Brain compression without global neuronal loss in meningiomas: whole-brain proton MR spectroscopy report of 2 cases.

We report the findings from whole-brain proton MR spectroscopy, quantifying the neuronal marker N-acetylaspartate (NAA), for 2 presurgical meningioma patients and 10 healthy controls. The patients' whole-brain NAA (WBNAA) concentrations were considerably elevated (3+ SDs) compared with healthy controls when excluding the tumors from brain volume; WBNAA levels normalized following correction to approximate "preneoplastic" brain size. These results suggest global neuronal preservation in these 2 patients while their brains were compressed by large, slowly growing, extra-axial masses.

Brain↗
PubMed2004

Functional renal MR imaging.

MR imaging is the only noninvasive test that may provide a complete picture of renal status with minimal risk to the patient, simultaneously improving diagnosis and lowering costs. This article reviews several MR renography techniques, including approaches for quantifying renal perfusion and glomerular filtration rate. Also discussed are clinical applications for the diagnosis and follow-up of renovascular disease, hydronephrosis,and renal transplant dysfunction. The article concludes with an overview of technical problems and challenges facing MR renography.

Contrast Media↗
PubMed2004

Renal magnetic resonance imaging.

PURPOSE OF REVIEW: Current magnetic resonance imaging systems allow the visualization of normal and diseased kidney, with exquisite resolution of renal structures. Dynamic contrast magnetic resonance imaging has the potential, unique among all noninvasive modalities, to differentiate diseases that affect different portions of the vascular-nephron system. This article reviews the most important recently published studies in selected topics chosen because of their clinical relevance or potential for technical developments. RECENT FINDINGS: Magnetic resonance imaging is used increasingly to evaluate renal masses, the prenatal genitourinary system, urinary obstruction and infection, renal vasculature, and the kidneys of transplant donors and recipients. Dynamic contrast magnetic resonance renography based on gadolinium chelated to diethylenetriamine pentaacetic acid, a safe (non-nephrotoxic) paramagnetic agent, emerges as the functional renal imaging modality of choice. Both perfusion and filtration rates can be assessed in individual kidney. SUMMARY: Magnetic resonance imaging has the potential to provide a complete anatomic, physiologic, kidney-specific evaluation. With future advances in automated image analysis methods we can expect functional renal magnetic resonance imaging to play an influential role in management of renal disease.

Acute Disease↗
PubMed2004

Magnetic resonance and PET studies in the early diagnosis of Alzheimer's disease.

The demographics of aging identify an immediate need for the early diagnosis and development of dementia prevention strategies. Recent neuropathological studies have pointed to the early involvement of the hippocampus and entorhinal cortex in the progression of Alzheimer's disease in the brain. In particular, these studies have implicated tau-related pathology as an important cause of neuronal death. In addition, there is a large body of evidence showing that beta-amyloid, which has a predilection for the neocortex, is also involved early in the course of the disease and may also have toxic effects on cells. In vivo cerebrospinal fluid studies have shown that markers for these brain changes have a diagnostic value for Alzheimer's disease and that some measures also provide diagnostic specificity for Alzheimer's disease. Structural and metabolic imaging studies demonstrate brain changes in impaired and at-risk individuals. While currently available magnetic resonance and positron emission tomography techniques are not by themselves specific for the pathologic features of Alzheimer's disease, there are patterns of change that have been useful for the early diagnosis. As such, both prediction and longitudinal imaging studies demonstrate a capacity to recognize abnormalities that relate to future Alzheimer's disease and most recently to future mild cognitive impairment. This review highlights cross-sectional, prediction, and longitudinal magnetic resonance and positron emission tomography imaging studies and attempts to put into perspective their utility for the early diagnosis of Alzheimer's disease, and for their utility to provide diagnostic specificity. It is concluded that there is considerable promise for an early and specific diagnosis for Alzheimer's disease by combining information from imaging and biomarker modalities.

Alzheimer Disease↗
PubMed2004

Assessment of vasculature using combined MRI and MR angiography.

OBJECTIVE: The purpose of this study was to compare combined cine gradient-recalled echo MRI and MR angiography with conventional angiography in the evaluation of the pulmonary vascular supply in patients with pulmonary atresia, ventricular septal defect, and major aortopulmonary collateral arteries. MATERIALS AND METHODS: Eleven patients who underwent both MRI and conventional angiography were retrospectively reviewed. Contiguous 2D cine gradient-recalled echo images (TR range/TE, 30-80/4.8; flip angle, 20 degrees or 30 degrees ) and 3D MR angiographic images (TR range/TE range, 3.8-5.0/1.3-2.0; acquisition time, 13-32 sec) using gadopentetate meglumine (0.1-0.2 mmol/kg) were obtained. The presence, size, and course of the pulmonary arteries (main, right, left) and major aortopulmonary collateral arteries (>/= 5 mm) were determined. Presence of minor collateral arteries (< 5 mm) was also noted. Results were compared with findings at conventional angiography. RESULTS: MRI showed all main (n = 4) and branch (n = 17) pulmonary arteries found at conventional angiography and showed the pulmonary confluence in five of six cases. MRI showed all major aortic collaterals (n = 22) with a highly significant correlation between MRI and conventional angiography measurements (r = 0.84, p < 0.001 [95% confidence interval, -0.35 to 0.40]). One coronary artery collateral was not shown on MRI examination. At MRI, 12 of 14 major and four of seven minor brachiocephalic artery collaterals were shown. MRI showed more minor aortic collaterals than angiography (22 vs 18 vessels, respectively). CONCLUSION: Combined cine gradient-recalled echo MRI and MR angiography is a reliable method for imaging pulmonary vascular supply in patients with these disorders. Additional prospective studies comparing MRI and conventional angiography may determine whether routine preoperative conventional angiography is required.

Aorta↗