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A rapidly converging, iterative deconvolution algorithm with a novel resolution subsets-based approach RSEMD that operates on digital imaging and communications in medicine images to improve the quality of clinical CT images is presented. The RSEMD method was tested on Catphan 500 and anthropomorphic 4-D XCAT phantoms to determine the improvements in signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). The method was applied to preclinical CT images previously reconstructed by conventional software. To test the potential improvement in clinically relevant CT images we employed the 4-D XCAT phantom to simulate a small, low contrast lesion placed in the liver. In all of the phantom studies, the images proved to have higher resolution and lower noise as compared with filtered back projection. In general, the iterative deblurring restoration reaches the highest SNR and CNR values after approximately 20 iterations with an improvement factor of about 1.5 for both CNR and SNR in noisy CT images. We also found improvements in preclinical and clinical CT images after the application of RSEMD. The results obtained with the RSEMD method are in agreement with other iterative algorithms employed either in image space or with hybrid reconstruction algorithms which start in projection space and then follow in image domain. The RSEMD method can be applied to suboptimal routine-dose clinical CT images to improve the image quality to diagnostically acceptable levels.

Author(s): O'Bryant, Sid E; Johnson, Leigh A; Barber, Robert C; Braskie, Meredith N; Christian, Bradley; Hall, James R; Hazra, Nalini; King, Kevin; Kothapalli, Deydeep; Large, Stephanie; Mason, David; Matsiyevskiy, Elizabeth; McColl, Roderick; Nandy, Rajesh; Palmer, Raymond; Petersen, Melissa; Philips, Nicole; Rissman, Robert A; Shi, Yonggang; Toga, Arthur W; Vintimilla, Raul; Vig, Rocky; Zhang, Fan; Yaffe, Kristine; HABLE Study Team | Abstract: IntroductionMexican Americans remain severely underrepresented in Alzheimer's disease (AD) research. The Health a Aging Brain among Latino Elders (HABLE) study was created to fill important gaps in the existing literature.MethodsCommunity-dwelling Mexican Americans and non-Hispanic White adults and elders (age 50 and above) were recruited. All participants underwent comprehensive assessments including an interview, functional exam, clinical labs, informant interview, neuropsychological testing, and 3T magnetic resonance imaging (MRI) of the brain. Amyloid and tau positron emission tomography (PET) scans were added at visit 2. Blood samples were stored in the Biorepository.ResultsData was examined from nn=n1705 participants. Significant group differences were found in medical, demographic, and sociocultural factors. Cerebral amyloid and neurodegeneration imaging markers were significantly different between Mexican Americans and non-Hispanic Whites.DiscussionThe current data provide strong support for continued investigations that examine the risk factors for and biomarkers of AD among diverse populations.

This study examined whether peripheral vision reaction time (PVRT) in patients with mild traumatic brain injury (mTBI) correlated with white matter abnormalities in centroaxial structures and impairments in neuropsychological testing. Within 24 h after mTBI, crossed reaction times (CRT), uncrossed reaction times (URT), and crossed–uncrossed difference (CUD) were measured in 23 patients using a laptop computer that displayed visual stimuli predominantly to either the left or the right visual field of the retina. The CUD is a surrogate marker of the interhemispheric transfer time (ITT). Within 7 days after the injury, patients received a diffusion tensor-MRI (DTI) scan and a battery of neuropsychological tests. Nine uninjured control subjects received similar testing. Patients 18–50 years of age were included if they had a post-resuscitation Glasgow Coma Scale >13 and an injury mechanism compatible with mTBI. Healthy controls were either age- and gender-matched family members of the TBI patients or healthy volunteers. CUD deficits >2 standard deviations (SD) were seen in 40.9% of patients. The CUD of injured patients correlated with mean diffusivity (MD) (p

Objectives This study aims to compare ethnic difference in proximal aortic pulse wave velocity (PWV) and characteristic impedance (Zc). Background Increased aortic stiffness is an independent predictor of target organ damage, incident hypertension, and all-cause mortality. However, previous studies have not directly assessed proximal aortic function in Blacks, the ethnic population with disproportionately high risk for incident hypertension and target organ complications. Methods We evaluated the multiethnic, population-based DHS (Dallas Heart Study) participants (N = 2,544, 54.2% women, 49.7% Black) who underwent cardiac magnetic resonance at 1.5-T. Aortic stiffness and Zc were determined from aortic arch PWV and lumen area measurements. Linear regression was used to evaluate ethnic differences in proximal aortic wall stiffness using aortic arch PWV and Zc as dependent variables with and without adjustment for traditional cardiovascular risk factors. Because cardiac output was significantly higher in Blacks compared to Whites and Hispanics, additional comparisons of PWV and Zc were performed after adjustment for cardiac output and peripheral vascular resistance. Results Compared with Whites, both Blacks and Hispanics had higher levels of aortic arch PWV (4.25, 95% confidence interval [CI]: 4.15 to 4.35 m/s, vs. 4.72, 95% CI: 4.64 to 4.81 m/s, vs. 4.48, 95% CI: 4.33 to 4.63 m/s, respectively, both p 5 , vs. 75.6, 95% CI: 74.0 to 77.2 dyne·s/cm 5 , vs. 70.1, 95% CI: 67.6 to 72.8 dyne·s/cm 5 , respectively, both p Conclusions In a multiethnic population-based-sample, Blacks and Hispanics had higher proximal aortic stiffness compared with Whites independent of blood pressure and relevant risk factors.

PURPOSE We summarize the AAPM TG248 Task Group report on interoperability assessment for the commissioning of medical imaging acquisition systems in order to bring needed attention to the value and role of quality assurance testing throughout the imaging chain. METHODS To guide the clinical physicist involved in commissioning of imaging systems, we describe a framework and tools for incorporating interoperability assessment into imaging equipment commissioning. RESULTS While equipment commissioning may coincide with equipment acceptance testing, its scope may extend beyond validation of product or purchase specifications. Equipment commissioning is meant to provide assurance that a system is ready for clinical use, and system interoperability plays an essential role in the clinical use of an imaging system. CONCLUSION The functionality of a diagnostic imaging system extends beyond the acquisition console and depends on interoperability with a host of other systems such as the Radiology Information System, a Picture Archive and Communication System, post-processing software, treatment planning software, and clinical viewers.

To determine in a large multiethnic cohort the cardiovascular and genetic risk factors associated with smaller volume in the hippocampus, precuneus, and posterior cingulate, and their association with preclinical deficits in cognitive performance in patients younger and older than 50 years.The institutional review board approved the study and all participants provided written informed consent. Eligible for this study were 1629 participants (700 men and 929 women; mean age, 50.0 years ± 10.2 [standard deviation]) drawn from the population-based Dallas Heart Study who underwent laboratory and clinical analysis in an initial baseline visit and approximately 7 years later underwent brain magnetic resonance imaging with automated volumetry and cognitive assessment with the Montreal Cognitive Assessment (MoCA). Regression analysis showed associations between risk factors and segmental volumes, and associations between these volumes with cognitive performance in participants younger and older than 50 years.Lower hippocampal volume was associated with previous alcohol consumption (standardized estimate, -0.04; P = .039) and smoking (standardized estimate, -0.04; P = .048). Several risk factors correlated with lower total brain, posterior cingulate, and precuneus volumes. Higher total (standardized estimate, 0.06; P = .050), high-density lipoprotein (standardized estimate, 0.07; P = .003), and low-density lipoprotein (standardized estimate, 0.04; P = .037) cholesterol levels were associated with larger posterior cingulate volume, and higher triglyceride levels (standardized estimate, 0.06; P = .004) were associated with larger precuneus volume. Total MoCA score was associated with posterior cingulate volume (standardized estimate, 0.13; P = .001) in younger individuals and with hippocampal (standardized estimate, 0.06; P.05) and precuneus (standardized estimate, 0.08; P.023) volumes in older adults.Smaller volumes in specific brain regions considered to be early markers of dementia risk were associated with specific cardiovascular disease risk factors and cognitive deficits in a predominantly midlife multiethnic population-based sample. Additionally, the risk factors most associated with these brain volumes differed in participants younger and older than 50 years, as did the association between brain volume and MoCA score.

Purpose To study the feasibility of using an iterative reconstruction algorithm to improve previously reconstructed CT images which are judged to be non-diagnostic on clinical review. A novel rapidly converging, iterative algorithm (RSEMD) to reduce noise as compared with standard filtered back-projection algorithm has been developed. Materials and methods The RSEMD method was tested on in-silico, Catphan ® 500, and anthropomorphic 4D XCAT phantoms. The method was applied to noisy CT images previously reconstructed with FBP to determine improvements in SNR and CNR. To test the potential improvement in clinically relevant CT images, 4D XCAT phantom images were used to simulate a small, low contrast lesion placed in the liver. Results In all of the phantom studies the images proved to have higher resolution and lower noise as compared with images reconstructed by conventional FBP. In general, the values of SNR and CNR reached a plateau at around 20 iterations with an improvement factor of about 1.5 for in noisy CT images. Improvements in lesion conspicuity after the application of RSEMD have also been demonstrated. The results obtained with the RSEMD method are in agreement with other iterative algorithms employed either in image space or with hybrid reconstruction algorithms. Conclusions In this proof of concept work, a rapidly converging, iterative deconvolution algorithm with a novel resolution subsets-based approach that operates on DICOM CT images has been demonstrated. The RSEMD method can be applied to sub-optimal routine-dose clinical CT images to improve image quality to potentially diagnostically acceptable levels.

Background and purpose Vascular risk factors have been associated with decreased cerebral blood flow (CBF) but this is etiologically nonspecific and may result from vascular insufficiency or a response to decreased brain metabolic activity. We apply new MRI techniques to measure oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen consumption (CMRO2), hypothesizing that decreased CBF related to these vascular risk factors will be associated with increased OEF, confirming a primary vascular insufficiency. Methods 3T MRI was obtained on 70 community-based participants in this IRB-approved study with informed consent, with previous assessment of systolic blood pressure, hypertension medication, elevated serum triglycerides, low serum HDL, and diabetes mellitus. CBF was measured using phase contrast adjusted for brain volume (ml/100 g/min), OEF (%) was obtained from T2-Relaxation-Under-Spin-Tagging (TRUST), and CMRO2 (μmol/100 g/min) was derived using the Fick principle. Stepwise linear regression identified optimal predictors of CBF with age, sex, and hematocrit included for adjustment. This predictive model was then evaluated against OEF and CMRO2. Results Hypertriglyceridemia was associated with low CBF and high OEF. High systolic blood pressure was associated with high CBF and low OEF, which was primarily attributable to those with pressures above 160 mmHg. Neither risk factor was associated with significant differences in cerebral metabolic rate. Conclusion Low CBF related to hypertriglyceridemia was accompanied by high OEF with no significant difference in CMRO2, confirming subclinical vascular insufficiency. High CBF related to high systolic blood pressure likely reflected limitations of autoregulation at higher blood pressures.

Purpose: To test and evaluate an efficient iterative image processing strategy to improve the quality of sub-optimal pre-clinical PET images. A novel iterative resolution subset-based method to reduce noise and enhance resolution (RSEMD) has been demonstrated on examples of PET imaging studies of Alzheimer’s disease (AD) plaques deposition in mouse brains.Materials and Methods: The RSEMD method was applied to imaging studies of non-invasive detection of beta-amyloid plaque in transgenic mouse models of AD. Data acquisition utilized a Siemens Inveon® micro PET/CT device. Quantitative uptake of the tracer in control and AD mice brains was determined by counting the extent of plaque deposition by histological staining. The preclinical imaging software inviCRO® was used for fitting the recovery PET images to the mouse brain atlas and obtaining the time activity curves (TAC) from different brain areas. Results: In all of the AD studies the post-processed images proved to have higher resolution and lower noise as compared with images reconstructed by conventional EM methods. In general, the values of SNR reached a plateau at around 10 iterations with an improvement factor of about 2 over sub-optimal PET brain images.Conclusions: A rapidly converging, iterative deconvolution image processing algorithm with a resolution subsets-based approach RSEMD has been used for quantitative studies of changes in Alzheimer’s pathology over time. The RSEMD method can be applied to sub-optimal clinical PET brain images to improve image quality to diagnostically acceptable levels and will be crucial in order to facilitate diagnosis of AD progression at the earliest stages.

Background Obesity may increase heart failure risk through cardiac remodeling. Cross‐sectional associations between adiposity and cardiac structure and function have been elucidated, but the impact of longitudinal changes in adiposity on cardiac remodeling is less well understood. Methods and Results Participants in the Dallas Heart Study without cardiovascular disease or left ventricular dysfunction underwent assessment of body weight, anthropometrics, and cardiac magnetic resonance imaging at baseline and 7 years later. Associations between changes in indices of generalized and central adiposity with changes in left ventricular mass, volume, mass/volume ratio (concentricity), wall thickness, and ejection fraction were assessed using multivariable linear regression. The study cohort (n=1262) mean age was 44 years with 57% women, 44% black, and 36% obese participants. At follow‐up, 41% had ≥5% weight gain, and 15% had ≥5% weight loss. Greater weight gain was associated with younger age, lower risk factor burden, and lower body mass index at baseline. In multivariable models adjusting for age, sex, race, comorbid conditions at baseline and follow‐up, baseline adiposity, and cardiac measurement, increasing weight was associated with increases in left ventricular mass (β=0.10, P P P =0.002), with modest effects on end‐diastolic volume (β=0.04, P =0.044) and ejection fraction (β=0.05, P =0.046). Similar results were seen with other adiposity indices. Conclusions Concentric left ventricular remodeling is the predominant phenotype linked to increasing adiposity in middle age. Our findings support the importance of weight management to prevent secular changes in adiposity, concentric remodeling, and eventual heart failure over time.

Purpose: To evaluate an efficient iterative deconvolution method (RSEMD) for improving the quantitative accuracy of previously reconstructed breast images by commercial positron emission mammography (PEM) scanner. Materials and Methods: The RSEMD method was tested on breast phantom data and clinical PEM imaging data. Data acquisition was performed on a commercial Naviscan Flex Solo II PEM camera. This method was applied to patient breast images previously reconstructed with Naviscan software (MLEM) to determine improvements in resolution, signal to noise ratio (SNR) and contrast to noise ratio (CNR.) Results: In all of the patients’ breast studies the post-processed images proved to have higher resolution and lower noise as compared with images reconstructed by conventional methods. In general, the values of SNR reached a plateau at around 6 iterations with an improvement factor of about 2 for post-processed Flex Solo II PEM images. Improvements in image resolution after the application of RSEMD have also been demonstrated. Conclusions: A rapidly converging, iterative deconvolution algorithm with a novel resolution subsets-based approach RSEMD that operates on patient DICOM images has been used for quantitative improvement in breast imaging. The RSEMD method can be applied to clinical PEM images to improve image quality to diagnostically acceptable levels and will be crucial in order to facilitate diagnosis of tumor progression at the earliest stages. The RSEMD method can be considered as an extended Richardson-Lucy algorithm with multiple resolution levels (resolution subsets).

Background In the conventional paradigm of the progression of left ventricular hypertrophy, a thick-walled left ventricle (LV) ultimately transitions to a dilated cardiomyopathy. There are scant data in humans demonstrating whether this transition occurs commonly without an interval myocardial infarction. Methods and Results Participants (n=1282) from the Dallas Heart Study underwent serial cardiac magnetic resonance ≈7 years apart. Those with interval cardiovascular events and a dilated LV (increased LV end-diastolic volume [EDV] indexed to body surface area) at baseline were excluded. Multivariable linear regression models tested the association of concentric hypertrophy (increased LV mass and LV mass/volume 0.67 ) with change in LVEDV. The study cohort had a median age of 44 years, 57% women, 43% black, and 11% (n=142) baseline concentric hypertrophy. The change in LVEDV in those with versus without concentric hypertrophy was 1 mL (−9 to 12) versus −2 mL (−11 to 7), respectively, P P ≤0.01). The progression to a dilated LV was uncommon (2%, n=25). Conclusions In the absence of interval myocardial infarction, concentric hypertrophy was associated with a small, but significantly greater, increase in LVEDV after 7-year follow-up. However, the degree of LV enlargement was minimal, and few participants developed a dilated LV. These data suggest that if concentric hypertrophy does progress to a dilated cardiomyopathy, such a transition would occur over a much longer timeframe (eg, decades) and may be less common than previously thought. Clinical Trial Registration URL: http://www.clinicaltrials.gov . Unique identifier: NCT00344903.

Elevated urinary albumin to creatinine ratio (ACR) and white matter hyperintensity (WMH) volume seen on brain MRI are measures of microvascular disease which may have shared susceptibility to metabolic and vascular insults. We hypothesized that elevated ACR may be useful as inexpensive biomarker to predict presence of cerebral microvascular disease. We assessed the association between ACR at study entry and subsequent WMH volume. We evaluated pulse pressure, mean arterial pressure, hypertension duration, waist circumference, fasting glucose, glomerular filtration rate (GFR) and C-reactive protein (CRP) as potential mediators and diabetes as a moderator of the association between ACR and WMH. Data were collected at study entry and at follow-up approximately 7 years later in a multiethnic population sample of 1281 participants (mean age = 51, SD = 9.5) from Dallas County. Overall, ACR differences were only marginally (p = 0.05) associated with subsequent WMH. In mediator analysis, however, ACR differences related specifically to arterial pulsatility(β = 0.010, bootstrap 95% Confidence Interval (CI): 0.002 to 0.021) and waist circumference (β = -0.004, bootstrap 95% CI: -0.011 to -0.001) were significantly associated with WMH. ACR differences related to serum glucose and CRP were not associated with WMH. ACR evaluated at the same time as WMH had a higher level of significance (p0.001) indicating greater utility in predicting current cerebrovascular insults.

Hippocampal atrophy is reported in major depressive disorder (MDD). However, sample sizes were generally modest, and participant characteristics, including age, differed between studies. This study used a community sample to examine relationships between current depressive symptom severity and hippocampal volume across the adult lifespan. A total of 1936 adults with magnetic resonance images of the brain and Quick Inventory of Depressive Symptomatology Self-Report (QIDS-SR) scores were included. Brain volumes were quantified using the FSL program. Multiple linear regressions were performed using left, right, and total hippocampal volume as criterion variables, and predictor variables of QIDS-SR total, total brain volume, age, gender, education, psychotropic medications, alcohol use, and race/ethnicity. Post hoc analyses were conducted in participants with QIDS-SR scores ⩾11 (moderate or greater depressive symptom severity) and

Purpose To assess if fully automated localization of the aorta can be achieved using phase contrast (PC) MR images. Materials and Methods PC cardiac-gated MR images were obtained as part of a large population-based study. A fully automated process using the Hough transform was developed to localize the ascending aorta (AAo) and descending aorta (DAo). The study was designed to validate this technique by determining: (i) its performance in localizing the AAo and DAo; (ii) its accuracy in generating AAo flow volume and DAo flow volume; and (iii) its robustness on studies with pathological abnormalities or imaging artifacts. Results The algorithm was applied successfully on 1884 participants. In the randomly selected 50-study validation set, linear regression shows an excellent correlation between the automated (A) and manual (M) methods for AAo flow (r = 0.99) and DAo flow (r = 0.99). Bland-Altman difference analysis demonstrates strong agreement with minimal bias for: AAo flow (mean difference [A-M] = 0.47 ± 2.53 mL), and DAo flow (mean difference [A-M] = 1.74 ± 2.47 mL). Conclusion A robust fully automated tool to localize the aorta and provide flow volume measurements on phase contrast MRI was validated on a large population-based study. J. Magn. Reson. Imaging 2014;40:221–228. © 2013 Wiley Periodicals, Inc.

Purpose To assess oxygenation in abdominal organs with magnetic resonance imaging (MRI), a novel approach is presented to simultaneously measure both T1- and -maps serially during a single dynamic MRI scan in response to an oxygen challenge. Materials and Methods The proposed acquisition scheme consists of a multishot multiecho gradient echo planar imaging sequence (ms-GEPI) interleaved with a multishot inversion recovery echo planar imaging (ms-IR-EPI) sequence. Respiratory motion compensation was accomplished with standard belt triggering and by acquiring all image data at the same phase of expiration. This respiratory-triggered, free-breathing, interleaved tissue oxygenation level-dependent (TOLD) and blood oxygenation level-dependent (BOLD) acquisition technique was validated on phantoms and seven healthy volunteers in response to an oxygen challenge. Results Measurements of relaxation times both in vitro and in vivo were in good agreement with those obtained using conventional pulse sequences and reported in the literature. The interleaved sequence was able to measure oxygen-induced relaxation time changes in human abdominal organs. Conclusion The free-breathing respiratory-triggered interleaved T1 and sequence successfully provided relaxation time maps of abdominal organs in a dynamic scan without the need for image registration. The simultaneous monitoring of tissue and blood oxygenation improves time efficiency and should enhance studies comparing dynamic T1 and data within the abdomen. J. Magn. Reson. Imaging 2013;38:1230–1236. © 2013 Wiley Periodicals, Inc.

To evaluate the relationship between pulse wave velocity (PWV) from the aortic arch and subsequent cerebral microvascular disease independent of other baseline cardiovascular risk factors among the participants in the multiethnic Dallas Heart Study.Each subject gave written consent to participate in this HIPAA-compliant, institutional review board-approved prospective study. Aortic arch PWV was measured with phase-contrast magnetic resonance (MR) imaging in a population sample (n = 1270) drawn from the probability-based Dallas Heart Study. Seven years later, the volume of white matter hyperintensities (WMHs) was determined from brain MR images. Linear regression was conducted with aortic arch PWV, 15 other cardiovascular risk factors, and age, sex, and ethnicity included as predictors of WMH. The authors implemented a smoothly clipped absolute deviation-penalized variable selection method to evaluate an optimal predictive risk factor model.Aortic arch PWV helped predict WMH volume independent of the other demographic and cardiovascular risk factors (regression coefficient: 0.29; standard error: 0.06; 95% confidence interval: 0.17, 0.42; P.0001). The optimal predictor variables of subsequent WMH volume adjusted for sex and ethnicity included aortic arch PWV, age, systolic blood pressure, hypertension treatment, and congestive heart failure. The authors estimated that a 1% increase in aortic arch PWV (in meters per second) is related to a 0.3% increase in subsequent WMH volume (in milliliters) when all other variables in the model are held constant.Aortic arch PWV measured with phase-contrast MR imaging is a highly significant independent predictor of subsequent WMH volume, with a higher standardized effect than any other cardiovascular risk factor assessed except for age. In an optimal predictive model of subsequent WMH burden, aortic arch PWV provides a distinct contribution along with systolic blood pressure, hypertension treatment, congestive heart failure, and age.

BACKGROUND AND PURPOSE: Asymmetry of the hippocampus is regarded as an important clinical finding, but limited data on hippocampal asymmetry are available for the general population. Here we present hippocampal asymmetry data from the Dallas Heart Study determined by automated methods and its relationship to age, sex, and ethnicity. MATERIALS AND METHODS: 3D magnetization-prepared rapid acquisition of gradient echo MR imaging was performed in 2082 DHS-2 participants. The MR images were analyzed by using 2 standard automated brain-segmentation programs, FSL-FIRST and FreeSurfer. Individuals with imaging errors, self-reported stroke, or major structural abnormalities were excluded. Statistical analyses were performed to determine the significance of the findings across age, sex, and ethnicity. RESULTS: At the 90th percentile, FSL-FIRST demonstrated hippocampal asymmetry of 9.8% (95% CI, 9.3%–10.5%). The 90th percentile of hippocampal asymmetry, measured by the difference in right and left hippocampi volume and the larger hippocampus, was 17.9% (95% CI, 17.0%–19.1%). Hippocampal asymmetry increases with age (P = .0216), men have greater asymmetry than women as shown by FSL-FIRST (P = .0036), but ethnicity is not significantly correlated with asymmetry. To confirm these findings, we used FreeSurfer. FreeSurfer showed asymmetry of 4.4% (95% CI, 4.3%–4.7%) normalized to total volume and 8.5% (95% CI, 8.3%–9.0%) normalized by difference/larger hippocampus. FreeSurfer also showed that hippocampal asymmetry increases with age (P = .0024) and that men had greater asymmetry than women (P = .03). CONCLUSIONS: There is a significant degree of hippocampal asymmetry in the population. The data provided will aid in the research, diagnosis, and treatment of temporal lobe epilepsy and other neurologic disease.

Purpose To evaluate in clinical use a rapidly converging, efficient iterative deconvolution algorithm (RSEMD) for improving the quantitative accuracy of previously reconstructed breast images by a commercial positron emission mammography (PEM) scanner. Materials and methods The RSEMD method was tested on imaging data from clinical Naviscan Flex Solo II PEM scanner. This method was applied to anthropomorphic like breast phantom data and patient breast images previously reconstructed with Naviscan software to determine improvements in image resolution, signal to noise ratio (SNR) and contrast to noise ratio (CNR). Results In all of the patients’ breast studies the improved images proved to have higher resolution, contrast and lower noise as compared with images reconstructed by conventional methods. In general, the values of CNR reached a plateau at an average of 6 iterations with an average improvement factor of about 2 for post-reconstructed Flex Solo II PEM images. Improvements in image resolution after the application of RSEMD have also been demonstrated. Conclusions A rapidly converging, iterative deconvolution algorithm with a resolution subsets-based approach (RSEMD) that operates on patient DICOM images has been used for quantitative improvement in breast imaging. The RSEMD method can be applied to PEM images to enhance the resolution and contrast in cancer diagnosis to monitor the tumor progression at the earliest stages.

Asthma is associated with an increased risk of mild cognitive impairment and dementia. Depression and oral corticosteroid use are associated with atrophy of the hippocampus and are common in asthma. However, minimal neuroimaging data are available in asthma patients.We conducted a retrospective analysis of 1,287 adult participants from the Dallas Heart Study, an epidemiological sample of Dallas County residents. Study outcome variables were hippocampal volumes measured by FreeSurfer. ANOVA was used to examine a gender difference in hippocampal volumes. General Linear Models (GLM) were conducted to examine asthma diagnosis association with hippocampal volumes.The prevalence rate of asthma among our study sample was 10.8% with 9.6% in males and 11.7% in females. After controlling for demographic characteristics, participants with asthma had significantly smaller total, right, and left hippocampal volumes than those without asthma. The association of asthma with smaller hippocampal volume was significant among males but not among females.Hippocampal volume in a large and diverse sample of adults was significantly smaller in people with asthma as compared to those without asthma. These findings suggest that asthma may be associated with structural brain differences. Thus, medical illnesses without obvious direct neurodegenerative or even vascular involvement can be associated with brain changes. Because the hippocampus is a brain region involved in memory formation, these findings may have implications for treatment adherence that could have important implications for asthma treatment. Study limitations are the reliance on a self-reported asthma diagnosis and lack of additional asthma clinical information.

The purpose of this study was to explore the feasibility of assessing quality of diffusion tensor imaging (DTI) from multiple sites and vendors using American College of Radiology (ACR) phantom. Participating sites (Siemens (n=2), GE (n=2), and Philips (n=4)) reached consensus on parameters for DTI and used the widely available ACR phantom. Tensor data were processed at one site. B0 and eddy current distortions were assessed using grid line displacement on phantom Slice 5; signal‐to‐noise ratio (SNR) was measured at the center and periphery of the b=0 image; fractional anisotropy (FA) and mean diffusivity (MD) were assessed using phantom Slice 7. Variations of acquisition parameters and deviations from specified sequence parameters were recorded. Nonlinear grid line distortion was higher with linear shimming and could be corrected using the 2nd order shimming. Following image registration, eddy current distortion was consistently smaller than acquisition voxel size. SNR was consistently higher in the image periphery than center by a factor of 1.3–2.0. ROI‐based FA ranged from 0.007 to 0.024. ROI‐based MD ranged from 1.90×10−3 to 2.33×10−3mm2/s(median=2.04×10−3mm2/s). Two sites had image void artifacts. The ACR phantom can be used to compare key quality measures of diffusion images acquired from multiple vendors at multiple sites. PACS number(s): 87.57.‐s, 87.19.lf

BACKGROUND AND PURPOSE: Age-related white matter hyperintensities have prognostic implications, but no accepted clinical standard exists for their assessment. We propose a simple objective visual rating system by using 3T brain MR imaging. MATERIALS AND METHODS: MR imaging from 559 participants was processed by using an automated method to determine WMH volumes and evaluated with a new visual rating scale based on the single largest WMH lesion diameter regardless of location. The reproducibility of the visual system was assessed. The association of WMH visual scores and automated volumes was then compared with cognitive scores from the Montreal Cognitive Assessment, which was available for 510 participants. RESULTS: Inter-reader reproducibility was good for subsamples with both high (n = 52) and low (n = 40) prevalence of large automated WMH volumes (agreement of 67% and 87.5%, κ = 0.71 and 0.76, respectively). Correlation between increased WMH and cognitive deficit measurements was equal for our visual ratings and automated volumes (Spearman ρ = 0.118 and 0.109; P values = 0.008 and 0.014, respectively). The visual scale retained a significant association with MoCA score after adjusting for age, sex, and education (standardized β = −0.087, P = .042). CONCLUSIONS: We propose a simple visual WMH scoring system suitable for use as a baseline evaluation in clinical practice.

Hypoxia is reported to be a biomarker for poor prognosis in cervical cancer. However, a practical noninvasive method is needed for the routine clinical evaluation of tumor hypoxia. This study examined the potential use of blood oxygenation level-dependent (BOLD) contrast MRI as a noninvasive technique to assess tumor vascular oxygenation at 3T. Following Institutional Review Board-approved informed consent and in compliance with the Health Insurance Portability and Accountability Act, successful results were achieved in nine patients with locally advanced cervical cancer [International Federation of Gynecology and Obstetrics (FIGO) stage IIA to IVA] and three normal volunteers. In the first four patients, dynamic T₂*-weighted MRI was performed in the transaxial plane using a multi-shot echo planar imaging sequence whilst patients breathed room air followed by oxygen (15 dm³/min). Later, a multi-echo gradient echo examination was added to provide quantitative R₂* measurements. The baseline T₂*-weighted signal intensity was quite stable, but increased to various extents in tumors on initiation of oxygen breathing. The signal in normal uterus increased significantly, whereas that in the iliacus muscle did not change. R₂* responded significantly in healthy uterus, cervix and eight cervical tumors. This preliminary study demonstrates that BOLD MRI of cervical cancer at 3T is feasible. However, more patients must be evaluated and followed clinically before any prognostic value can be determined.

Objectives Electron beam computed tomography (EBCT) for coronary artery calcification can potentially evaluate liver fat, another marker of cardiovascular risk. We compared quantitative estimates of hepatic steatosis measured by EBCT with those obtained by a well-validated, accurate-measure, magnetic resonance spectroscopy (1H MRS). Methods EBCT and 1H MRS were performed in 2159 subjects from the Dallas Heart Study. Forty subjects were randomly selected from each of 5 subgroups of liver fat percent by 1H MRS (n = 200). EBCT average liver attenuation (HU) was determined in a 1- to 2-cm circular region of interest over the liver lobes. Pearson correlation coefficients were calculated. Using a previously defined 1H MRS hepatic steatosis cut point (>5.5%), an optimized EBCT liver attenuation cut point was determined by receiver operating characteristic analysis. Results 1H MRS liver fat content and EBCT average right lobe liver attenuation were moderately negatively correlated ( r = −0.64, P < 0.0001) in all subjects and in those with 1H MRS hepatic steatosis ( r = −0.71, P < 0.0001). This correlation did not improve with attenuation correction of the EBCT data using a standard calcium phantom or statistical transformation. Using an optimized receiver operating characteristic EBCT cut point (64.5 HU), sensitivity was 78% and specificity was 72% for detecting 1H MRS hepatic steatosis, with a high false negative rate. Risk factors for hepatic steatosis (obesity, diabetes mellitus, insulin resistance, metabolic syndrome) were more strongly correlated with 1H MRS than EBCT liver fat measures. Conclusions Liver attenuation on EBCT acquired for coronary artery calcification screening correlates modestly with 1H MRS measures of liver fat content, with a high false negative rate.

Background and Purpose— The natural history of white matter hyperintensity (WMH) progression resulting from normal aging versus comorbid vascular insults remains unclear. Therefore we investigated age-related differences in WMH volumes among a group with comorbid hypertension, abnormal body mass index, and diabetes mellitus to a normal aging group drawn from the same population lacking any of these comorbidities. Methods— WMH volumes were acquired using 3T MRI for 2011 Dallas Heart Study participants. The slope of the WMH versus age regression was compared between normal and comorbidity groups Results— Aging was linearly associated with greater log WMH volume for both normal ( P =0.02) and comorbidity ( P P P =0.173). The between-group difference in slope of expected WMH for age was significantly greater in the comorbidity groups ≥50 years of age ( P =0.0008) but not P =0.752). Conclusions— After 50 years of age, but not before, comorbid hypertension, obesity, and diabetes mellitus were associated with significantly larger WMH volumes for age compared with a normal aging group lacking these conditions. These results support the assertion that age-related differences in WMH volumes are significantly increased in the presence of comorbidities, but the effect is only detectable after 50 years of age.

Traumatic axonal injury (TAI) is a common mechanism of traumatic brain injury not readily identified using conventional neuroimaging modalities. Novel imaging modalities such as diffusion tensor imaging (DTI) can detect microstructural compromise in white matter (WM) in various clinical populations including TAI. DTI-derived data can be analyzed using global methods (i.e., WM histogram or voxel-based approaches) or a regional approach (i.e., tractography). While each of these methods produce qualitatively comparable results, it is not clear which is most useful in clinical research and ultimately in clinical practice. This study compared three methods of analyzing DTI-derived data with regard to detection of WM injury and their association with clinical outcomes. Thirty patients with TAI and 19 demographically similar normal controls were scanned using a 3 Tesla magnet. Patients were scanned approximately eight months postinjury, and underwent an outcomes assessment at that time. Histogram analysis of fractional anisotropy (FA) and mean diffusivity showed global WM integrity differences between patients and controls. Voxel-based and tractography analyses showed significant decreases in FA within centroaxial structures involved in TAI. All three techniques were associated with functional and cognitive outcomes. DTI measures of microstructural integrity appear robust, as the three analysis techniques studied showed adequate utility for detecting WM injury. (JINS, 2011, 17, 24–35)

Diffusion Tensor Imaging (DTI) was used to investigate the relationship between white matter and reading abilities in reading impaired and non-reading impaired children. Seventeen children (7 non-reading impaired, 10 reading impaired) participated in this study. DTI was performed with 2 mm isotropic resolution to cover the entire brain along 30 noncollinear directions. Voxelwise analyses were conducted on data processed through Tract Based Spatial Statistics (TBSS). The data replicated previous results seen across multiple studies and extended findings to include measures of both real word and pseudoword decoding. Negative correlations were observed in the left posterior corpus callosum between fractional anisotropy (FA) values and both measures of decoding. Positive correlations between FA values and real word and pseudoword decoding were observed in the left superior corona radiata. This extension of findings regarding correlations between the corona radiata and reading skills suggests an important direction for future research into the neurological substrates of reading.

Functional magnetic resonance images were acquired while children with and without dyslexia identified incongruous words embedded within fairy tale segments in a quasidichotic listening task. All children produced greater activation in the left hemisphere than in the right hemisphere during the binaural separation listening task. Children with dyslexia, who had a higher incidence of a dichotic left ear deficit from prescanning behavioral tests, produced fewer hits and more misses than control children while monitoring their left ears in the scanner. Control children produced stronger left hemispheric activation for ipsilateral left ear input than right hemispheric activation for ipsilateral right ear input, but ipsilateral activation patterns in children with dyslexia were symmetrical. Children with dyslexia who monitored their right ears first produced the lowest left hemispheric activation overall, suggesting that priming of the right ear may have inhibited the ability of children with a left ear deficit to adequately identify target words presented toward their left ears while in the scanner. Se registraron imágenes de resonancia magnética funcional mientras niños con sin dislexia identificaban palabras incongruentes inmersas en segmentos de un cuento de hadas, durante una tarea de escucha cuasi-dicótica. Todos los niños produjeron una mayor activación en el hemisferio izquierdo que en el derecho durante dicha tarea de separación auditiva binaural. Los niños con dislexia, quienes mostraban una mayor incidencia de deficiencia dicótica en el oído izquierdo demostrada por pruebas conductuales previas al escaneo, lograron menores aciertos y más fallas que los niños del grupo control, mientras se monitoreaban sus oídos izquierdos en el equipo. Los niños controles produjeron una activación más fuerte del hemisferio izquierdo para la estimulación ipsilateral del oído izquierdo que activación del hemisferio derecho para la estimulación ipsilateral del oído derecho, pero los patrones de activación ipsilateral en los niños de dislexia fueron simétricos. Los niños con dislexia que monitorearon primero sus oídos derechos produjeron la activación global más baja del hemisferio izquierdo, sugiriendo que poner atención al oído derecho puede haber inhibido la capacidad de los niños con una deficiencia del oído izquierdo para identificar adecuadamente palabras clave presentadas hacia el oído izquierdo mientras eran escaneados.

LAMP, K., K. GALLAGHER, R. MCCOLL, D. MATHEWS, R. QUERRY, and J. W. WILLIAMSON. Exercise-Induced Decrease in Insular Cortex rCBF during Postexercise Hypotension. Med. Sci. Sports Exerc., Vol. 39, No. 4, pp. 672–679, 2007. The insular cortex (IC), a region of the brain involved in blood pressure (BP) modulation, shows decreases in regional cerebral blood flow (rCBF) during postexercise hypotension (PEH). Purpose: To determine whether changes in IC neural activity were caused by prior exercise or by changes in BP, this investigation compared patterns of rCBF during periods of hypotension, which was induced by prior exercise (i.e., PEH) and sodium nitroprusside (SNP) infusion and a cold pressor (CP), to restore BP. Methods: Ten subjects were studied on three different days with randomly assigned conditions: i) resting baseline; ii) PEH; and iii) SNP-induced hypotension (matched to the PEH BP decrease). Data were collected for heart rate (HR) and mean BP, and rCBF was assessed using single-photon emission computed tomography (SPECT) as an index of brain activation. Results: Using ANOVA across conditions, there were differences (P G 0.05; mean T SD) from baseline during PEH for HR (+12 T 3 bpm) and mean BP (j8 T 2 mm Hg) and during SNP-induced hypotension (HR = +15 T 4 bpm; MBP = j9 T 2 mm Hg), with no differences between PEH and SNP. After exercise, there were decreases (P G 0.05) in the leg sensorimotor area, anterior cingulate, and the right and left inferior thalamus, right inferior insula, and left anterior insular regions. During SNP-induced hypotension, there were significant increases in the right and left inferior thalamus and the right and left inferior anterior IC. CP during PEH increased BP and IC activity. Conclusions: Data show that reductions in IC neural activity are not caused by acute BP decreases. Findings suggest that exercise can lead to a temporary decrease in IC neural activity

Purpose To introduce and evaluate the performance of an automated fat quantification method for water-saturated magnetic resonance images. Materials and Methods A fat distribution model is proposed for fat quantification on water saturated magnetic resonance images. Fat from both full- and partial-volume voxels are accounted for in this model based on image intensity histogram analysis. An automated threshold method is therefore proposed to accurately quantify total fat. This method is compared to a traditional full-volume-fat-only method in phantom and human studies. In the phantom study, fat quantification was performed on MR images obtained from a human abdomen oil phantom and was compared with the true oil volumes. In the human study, results of the two fat quantification methods of six subjects were compared on abdominal images with different spatial resolutions. Results In the phantom study, the proposed method provided significantly more accurate estimations of true oil volumes compared to the reference method (P < 0.0001). In human studies, fat quantification using the proposed method gave much more consistent results on images with different spatial resolutions, and on regions with different degrees of partial volume averaging. Conclusion The proposed automated method is simple, rapid, and accurate for fat quantification on water-saturated MR images. J. Magn. Reson. Imaging 2007;26:738–746. © 2007 Wiley-Liss, Inc.

The Wada test is widely used in the presurgical evaluation of potential temporal lobectomy patients to predict postoperative memory function. Expected asymmetry (EA), defined as Wada memory lateralized to the nonsurgical hemisphere, or a higher score after injection of the surgical hemisphere would be considered favorable in terms of postoperative memory outcome. However, in some cases, nonlateralized memory (NM) results, with no appreciable asymmetry, may occur because of impaired scores after both injections, often leading to denial of surgery. The reason for such nonlateralized Wada memory in patients with intractable temporal lobe epilepsy (TLE) remains unclear. Given that quantitative morphometric magnetic resonance imaging studies in TLE patients have shown bilateral regional atrophy in temporal and extratemporal structures, we hypothesized that the volume loss in contralateral temporal structures could contribute to nonlateralized Wada memory performance. To investigate this, we examined the relationship between the volume changes of temporal structures and Wada memory scores in patients with intractable TLE with mesial temporal sclerosis (MTS) using an age- and gender-matched control group. Memory was considered nonlateralized if the absolute difference in the total correct recall scores between ipsilateral and contralateral injections was

Background: Subcortical lacunar infarcts and white matter hyperintensities (WMH) are common neuroradiological findings, but few studies associate between these insults and cognition in a community-dwelling population. Methods: The Dallas Heart Study is a population-based initiative whose assessments included demographic and clinical findings including brain MRI and the Montreal Cognitive Assessment (MoCA). The presence and number of lacunes in subjects aged over 55 years were assessed by study physicians. The WMH volume was measured by an automated method. The association between the presence and number of lacunar infarcts and of WMH volume with the total MoCA score and subdomains was assessed using linear regression with adjustment for age, gender and self-reported ethnicity. Results: In 609 subjects with valid data, both the presence and the increasing number of lacunes were associated with lower MoCA scores, even after adjusting for demographic variables. The presence of lacunes was also associated with lower scores in the memory, executive and attention subdomains. The WMH volume was not significantly associated with the MoCA score. Conclusion: The presence and increasing number of lacunes in midlife is associated with a lower performance in multiple domains of a cognitive screening measure after adjusting for demographic factors.

Bioluminescent imaging is a valuable noninvasive technique for investigating tumor dynamics and specific biological molecular events in living animals to better understand the effects of human disease in animal models. The purpose of this study was to develop and test a strategy behind automated methods for bioluminescence image processing from the data acquisition to obtaining 3D images.In order to optimize this procedure a semi-automated image processing approach with multi-modality image handling environment was developed. To identify a bioluminescent source location and strength we used the light flux detected on the surface of the imaged object by CCD cameras. For phantom calibration tests and object surface reconstruction we used MLEM algorithm. For internal bioluminescent sources we used the diffusion approximation with balancing the internal and external intensities on the boundary of the media and then determined an initial order approximation for the photon fluence we subsequently applied a novel iterative deconvolution method to obtain the final reconstruction result.We find that the reconstruction techniques successfully used the depth-dependent light transport approach and semi-automated image processing to provide a realistic 3D model of the lung tumor. Our image processing software can optimize and decrease the time of the volumetric imaging and quantitative assessment.The data obtained from light phantom and lung mouse tumor images demonstrate the utility of the image reconstruction algorithms and semi-automated approach for bioluminescent image processing procedure. We suggest that the developed image processing approach can be applied to preclinical imaging studies: characteristics of tumor growth, identify metastases, and potentially determine the effectiveness of cancer treatment.

A Small Animal Imager (SAI) for PET has been designed, built, tested in phantoms, and applied to investigations in mice and rats. The device uses principles based on gamma-ray induced scintillation in crossed fiber optic detectors connected to Position Sensitive Photomultiplier Tubes (PSPMT). Each detector consists of an epoxied stack of 28 layers of 135 round 1 mm BCF-10 scintillating plastic fibers. The overlap region forms a 13.5times13.5times2.8 cm3 detector volume. Scintillating light from the fibers is detected by two (X and Y directions) Hamamatsu R-2486 PSPMTs with 16 anode wires in each of two orthogonal directions. A centroid-finding algorithm gives the position of a light cluster on the face (photocathode) of a PSPMT. The accuracy of the reconstruction of an interaction position is essentially independent of light cluster position. This translates to a nearly isotropic photon response for the entire detector. The system has been used to test several 3D image reconstruction algorithms, software modifications, and improvements. The sensitivity (~12.6 cps/kBq at 9 cm inner diameter) and sub-millimeter spatial resolution (better than 1 mm in phantoms) obtained with an iterative algorithm incorporating system modeling make the SAI a relatively inexpensive high performance animal imager. The SAI is currently being used for imaging experiments in mice and rats

Understanding the relationships between age-related changes in brain structure and cognitive function has been limited by inconsistent methods for assessing brain imaging, small sample sizes, and racially/ethnically homogeneous cohorts with biased selection based on risk factors. These limitations have prevented the generalizability of results from brain morphology studies.To determine the association of 3.0-T structural brain magnetic resonance (MR) imaging measurements with cognitive function in the multiracial/multiethnic, population-based Dallas Heart Study.Whole-brain, 2-dimensional, fluid-attenuated inversion recovery and 3-dimensional, magnetization-prepared, rapid acquisition with gradient echo MR imaging at 3.0 T was performed in 1645 Dallas Heart Study participants (mean [SD] age, 49.9 [10.5] years; age range, 19-85 years) who received both brain MR imaging and cognitive screening with the Montreal Cognitive Assessment between September 18, 2007, and December 28, 2009. Measurements were obtained for white matter hyperintensity volume, total brain volume, gray matter volume, white matter volume, cerebrospinal fluid volume, and hippocampal volume. Linear regression and a best predictive model were developed to determine the association of MR imaging biomarkers with the Montreal Cognitive Assessment total score and domain-specific questions.High-resolution anatomical MR imaging was used to quantify brain volumes. Scores on the screening Montreal Cognitive Assessment were used for cognitive assessment in participants.After adjustment for demographic variables, total brain volume (P .0001, standardized estimate [SE] = .1069), gray matter volume (P .0001, SE = .1156), white matter volume (P = .008, SE = .0687), cerebrospinal fluid volume (P = .012, SE = -.0667), and hippocampal volume (P .0001) were significantly associated with cognitive performance. A best predictive model identified gray matter volume (P .001, SE = .0021), cerebrospinal fluid volume (P = .01, SE = .0024), and hippocampal volume (P = .004, SE = .1017) as 3 brain MR imaging biomarkers significantly associated with the Montreal Cognitive Assessment total score. Questions specific to the visuospatial domain were associated with the most brain MR imaging biomarkers (total brain volume, gray matter volume, white matter volume, cerebrospinal fluid volume, and hippocampal volume), while questions specific to the orientation domain were associated with the least brain MR imaging biomarkers (only hippocampal volume).Brain MR imaging volumes, including total brain volume, gray matter volume, cerebrospinal fluid volume, and hippocampal volume, were independently associated with cognitive function and may be important early biomarkers of risk for cognitive insult in a young multiracial/multiethnic population. A best predictive model indicated that a combination of multiple neuroimaging biomarkers may be more effective than a single brain MR imaging volume measurement.

Objectives. Body weight-supported treadmill training (BWSTT) is a task-specific rehabilitation strategy that enhances functional locomotion in patients following spinal cord injury (SCI). Supraspinal centers may play an important role in the recovery of over-ground locomotor function in patients with motor-incomplete SCI. The purpose of this study was to evaluate the potential for supraspinal reorganization associated with 12 weeks of robotic BWSTT using functional magnetic resonance imaging (fMRI). Methods. Four men with motor-incomplete SCI participated in this study. Time since onset ranged from 14 weeks to 48 months post-SCI injury. All subjects were trained with BWSTT 3 times weekly for 12 weeks. This training was preceded and followed by fMRI study of supraspinal activity during a movement task. Testing of locomotor disability included the Walking Index for Spinal Cord Injury (WISCI II) and over-ground gait speed. Results. All subjects demonstrated some degree of change in the blood-oxygen-level-dependent (BOLD) signal following BWSTT. fMRI results demonstrated greater activation in sensorimotor cortical regions (S1, S2) and cerebellar regions following BWSTT. Conclusions. Intensive task-specific rehabilitative training, such as robotic BWSTT, can promote supraspinal plasticity in the motor centers known to be involved in locomotion. Furthermore, improvement in over-ground locomotion is accompanied by an increased activation of the cerebellum.

Purpose To compare the performance of a novel water-saturated b-SSFP sequence with that of a conventional T1-weighted turbo spin echo (T1W TSE) sequence for abdominal fat quantification. Materials and Methods A water-saturated, segmented, three-dimensional balanced steady-state free precession (b-SSFP) sequence and a traditional T1W TSE sequence were both employed on phantom and human studies. For phantom studies, a dual-layered phantom with known internal/external oil volumes was imaged using the two sequences. Images obtained by the two sequences were both processed using a computer-aided semiautomatic program for oil volume quantification. For human studies, six volunteers were scanned axially, centered at L2–L3 levels. Signal-to-noise ratio (SNR)fat, contrast-to-noise ratio (CNR)fat-muscle, CNRfat-large bowel, and CNRfat-small bowel were calculated on hand-drawn regions of interest (ROIs), and averaged over all six slices for each subject. Statistical analyses were then performed to determine the SNR and CNR differences between images obtained by the two techniques. Results The phantom studies show that water-saturated b-SSFP offers a significantly closer estimation of true oil volumes compared with that of T1W TSE (P < 0.0001), as well as a more accurate internal/external volume ratio (P = 0.0001). In human studies, three-dimensional water-saturated b-SSFP images demonstrated higher CNR than that of T1W TSE (P < 0.0005), and very close SNRfat (P = 0.045). Conclusion The proposed three-dimensional water-saturated b-SSFP sequence can generate high quality fat-only abdominal images with high CNR and SNR in shorter scan duration than the conventional T1W TSE approach. As images generated by this sequence suffer from no flow artifacts, and are less sensitive to bulk, respiratory, and bowel motion, three-dimensional water-saturated b-SSFP is a faster and more robust method for improving abdominal fat quantification using MRI. J. Magn. Reson. Imaging 2005;21:263–271. © 2005 Wiley-Liss, Inc.

This investigation compared patterns of regional cerebral blood flow (rCBF) during exercise recovery both with and without postexercise hypotension (PEH). Eight subjects were studied on 3 days with randomly assigned conditions: 1) after 30 min of rest; 2) after 30 min of moderate exercise (M-Ex) at 60-70% heart rate (HR) reserve during PEH; and 3) after 30 min of light exercise (L-Ex) at 20% HR reserve with no PEH. Data were collected for HR, mean blood pressure (MBP), and ratings of perceived exertion and relaxation, and rCBF was assessed by use of single-photon-emission computed tomography. With the use of ANOVA across conditions, there were differences ( P < 0.05; mean ± SD) from rest during exercise recovery from M-Ex (HR = +12 ± 3 beats/min; MBP = -9 ± 2 mmHg), but not from L-Ex (HR = +2 ± 2 beats/min; MBP = -2 ± 2 mmHg). After M-Ex, there were decreases ( P < 0.05) for the anterior cingulate (-6.7 ± 2%), right and left inferior thalamus (-10 ± 3%), right inferior insula (-13 ± 3%), and left inferior anterior insula (-8 ± 3%), not observed after L-Ex. There were rCBF decreases for leg sensorimotor regions after both M-Ex (-15 ± 4%) and L-Ex (-12 ± 3%) and for the left superior anterior insula (-7 ± 3% and -6 ± 3%), respectively. Data show that there are rCBF reductions within specific regions of the insular cortex and anterior cingulate cortex coupled with a postexercise hypotensive response after M-Ex. Findings suggest that these cerebral cortical regions, previously implicated in cardiovascular regulation during exercise, may also be involved in PEH.

The purpose of this investigation was to determine whether central command activated regions of the insular cortex, independent of muscle metaboreflex activation and blood pressure elevations. Subjects ( n = 8) were studied during 1) rest with cuff occlusion, 2) static handgrip exercise (SHG) sufficient to increase mean blood pressure (MBP) by 15 mmHg, and 3) post-SHG exercise cuff occlusion (PECO) to sustain the 15-mmHg blood pressure increase. Data were collected for heart rate, MBP, ratings of perceived exertion and discomfort, and regional cerebral blood flow (rCBF) by using single-photon-emission computed tomography. When time periods were compared when MBP was matched during SHG and PECO, heart rate (7 ± 3 beats/min; P < 0.05) and ratings of perceived exertion (15 ± 2 units; P < 0.05) were higher for SHG. During SHG, there were significant increases in rCBF for hand sensorimotor (9 ± 3%), right inferior posterior insula (7 ± 3%), left inferior anterior insula (8 ± 2%), and anterior cingluate regions (6 ± 2%), not found during PECO. There was significant activation of the inferior (ventral) thalamus and right inferior anterior insular for both SHG and PECO. Although prior studies have shown that regions of the insular cortex can be activated independent of mechanoreflex input, it was not presently assessed. These findings provide evidence that there are rCBF changes within regions of the insular and anterior cingulate cortexes related to central command per se during handgrip exercise, independent of metaboreflex activation and blood pressure elevation.

The purpose was to compare patterns of brain activation during imagined handgrip exercise and identify cerebral cortical structures participating in “central” cardiovascular regulation. Subjects screened for hypnotizability, five with higher (HH) and four with lower hypnotizability (LH) scores, were tested under two conditions involving 3 min of 1) static handgrip exercise (HG) at 30% of maximal voluntary contraction (MVC) and 2) imagined HG (I-HG) at 30% MVC. Force (kg), forearm integrated electromyography, rating of perceived exertion, heart rate (HR), mean blood pressure (MBP), and differences in regional cerebral blood flow distributions were compared using an ANOVA. During HG, both groups showed similar increases in HR (+13 ± 5 beats/min) and MBP (+17 ± 3 mmHg) after 3 min. However, during I-HG, only the HH group showed increases in HR (+10 ± 2 beats/min; P < 0.05) and MBP (+12 ± 2 mmHg; P < 0.05). There were no significant increases or differences in force or integrated electromyographic activity between groups during I-HG. The rating of perceived exertion was significantly increased for the HH group during I-HG, but not for the LH group. In comparison of regional cerebral blood flow, the LH showed significantly lower activity in the anterior cingulate (−6 ± 2%) and insular cortexes (−9 ± 4%) during I-HG. These findings suggest that cardiovascular responses elicited during imagined exercise involve central activation of insular and anterior cingulate cortexes, independent of muscle afferent feedback; these structures appear to have key roles in the central modulation of cardiovascular responses.

Cerebral oedema is a common complication of traumatic brain injury (TBI). The use of Fluid-Attenuated Inversion Recovery (FLAIR) imaging in combination with Diffusion Weighted Imaging (DWI) has the potential to distinguish between cytotoxic and vasogenic oedema. This study hypothesized a significant relationship between cytotoxic lesion volume and outcome.This observational study reports on a convenience sample where MRI was obtained for clinical purposes.Clinical post-TBI FLAIR and DWI images were analysed. For this study, lesions were defined as primarily cytotoxic oedema if the ratio of FLAIR to DWI lesion volume was comparable, defined as a ratio2. If the ratio of FLAIR to DWI lesion volume was ≥2, oedema was considered predominantly of vasogenic origin.The sample consisted primarily of males with TBIs whose injury severity ranged from complicated mild to severe. Analysis revealed that both oedema types are common after TBI and both are associated with functional deficits 6 months after injury.Acute MRI may be useful to assess pathology at the tissue after traumatic brain injury. Clinical trials targeting cytotoxic and vasogenic mechanisms of oedema formation may benefit from using DWI and FLAIR MRI as a means to differentiate the predominant oedema type after TBI.

Background The noninvasive measurement of absolute epicardial coronary arterial flow and flow reserve would be useful in the evaluation of patients with coronary circulatory disorders. Phase-contrast magnetic resonance imaging (PC-MRI) has been used to measure coronary arterial flow in animals, but its accuracy in humans is unknown. Methods and Results Twelve subjects (7 men, 5 women; age, 44 to 67 years) underwent PC-MRI measurements of flow in the left anterior descending coronary artery or one of its diagonal branches at rest and after administration of adenosine (140 μg·kg −1 ·min −1 IV). Immediately thereafter, intracoronary Doppler velocity (IDV) and flow measurements were made during cardiac catheterization at rest and after intravenous administration of adenosine. For the 12 patients, the correlation between MRI and invasive measurements of coronary arterial flow and coronary arterial flow reserve was excellent: coronary flow MRI (mL/min)= 0.85×coronary flow IDV (mL/min)+17 (mL/min), r =.89, and coronary flow reserve MRI =0.79×coronary velocity reserve IDV +0.34, r =.89. For the range of coronary arterial flows (18 to 161 mL/min) measured by MRI, the limit of agreement between MRI and catheterization measurements of flow was −13±30 mL/min; for the range of coronary reserves (0.7 to 3.7) measured by MRI, the limit of agreement between the two techniques was 0.1±0.4. Conclusions Cine velocity-encoded PC-MRI can noninvasively measure absolute coronary arterial flow in the left anterior descending artery in humans. PC-MRI can detect pharmacologically induced changes in coronary arterial flow and can reliably distinguish between those subjects with normal and abnormal coronary artery flow reserve.

In conclusion, cine gradient-echo MRI with myocardial tagging, using the apical long-axis and 4- and 2-chamber views, can quantify segmental wall motion with excellent reproducibility in follow-up studies. The combination of these 3 apical views permits rapid, complete assessment of all myocardial segments in a manner comparable to the standard segments used in echocardiography. This quantitative technique will offer substantial advantages in pharmacologic stress MRI studies performed for the detection of coronary artery disease or the assessment of contractile reserve during dobutamine infusion, as well as in studies of ventricular remodeling and its relation to left ventricular function.