Compatibility of standard vagus nerve stimulation and investigational microburst vagus nerve stimulation therapy with functional magnetic resonance imaging

Vagus nerve stimulation devices are conditionally approved in MRI with stimulation turned off and the requirement to modify the stimulation settings may be a barrier to scanning in some radiology practices. There is increasing interest in studying the effects of stimulation during MRI/fMRI. This study evaluated the safety of standard and investigational microburst vagus nerve stimulation therapies during MRI/fMRI. A prospective, multi-center study was conducted in patients with an investigational vagus nerve stimulation device that delivered either standard or investigational microburst vagus nerve stimulation. Thirty participants underwent sequential MRI and fMRI scans encompassing 188 total hours of scan time (62.7 hours with standard vagus nerve stimulation and 125.3 with investigational microburst vagus nerve stimulation). No adverse events were reported with active stimulation during MRI or during 12 months of follow-up. Our results support the safety and standard and investigational microburst vagus nerve stimulation therapy during MRI and fMRI scans.ABBREVIATIONS: VNS = vagus nerve stimulation; µVNS = microburst VNS; DRE = drug-resistant epilepsy; U.S. = United States; FOS = focal onset seizures; PGTC = primary generalized tonic-clonic seizures; IDE = investigational device exemption; SD = standard deviation; EEG = electroencephalogram.

Harmonized Multisite MRI-Based Quantification of Human Liver Fat and Stiffness: A Pilot Study

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is a leading cause of end-stage liver disease. NAFLD diagnosis and follow-up relies on a combination of clinical data, liver imaging, and/or liver biopsy. However, intersite imaging differences impede diagnostic consistency and reduce the repeatability of the multisite clinical trials necessary to develop effective treatments.

PURPOSE/HYPOTHESIS

The goal of this pilot study was to harmonize commercially available 3 T magnetic resonance imaging (MRI) measurements of liver fat and stiffness in human participants across academic sites and MRI vendors.

STUDY TYPE

Cohort.

SUBJECTS

Four community-dwelling adults with obesity.

FIELD STRENGTH/SEQUENCE

1.5 and 3 T, multiecho 3D imaging, PRESS, and GRE.

ASSESSMENT

Harmonized proton density fat fraction (PDFF) and magnetic resonance spectroscopy (MRS) protocols were used to quantify the FF of synthetic phantoms and human participants with obesity using standard acquisition parameters at four sites that had four different 3 T MRI instruments. In addition, a harmonized magnetic resonance elastography (MRE) protocol was used to quantify liver stiffness among participants at two different sites at 1.5 and 3 T field strengths. Data were sent to a single data coordinating site for postprocessing.

STATISTICAL TESTS

Linear regression in MATLAB, ICC analyses using SAS 9.4, one-sided 95% confidence intervals for the ICC.

RESULTS

PDFF and MRS FF measurements were highly repeatable among sites in both humans and phantoms. MRE measurements of liver stiffness in three individuals at two sites using one 1.5 T and one 3 T instrument showed repeatability that was high although lower than that of MRS and PDFF.

CONCLUSIONS

We demonstrated harmonization of PDFF, MRS, and MRE-based quantification of liver fat and stiffness through synthetic phantoms, traveling participants, and standardization of postprocessing analysis. Multisite MRI harmonization could contribute to multisite clinical trials assessing the efficacy of interventions and therapy for NAFLD.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY STAGE: 2.

Neuromorphometric associations with mood, cognition, and self-reported exercise levels in epilepsy and healthy individuals

Regular physical activity may promote beneficial neuroplasticity, e.g., increased hippocampus volume. However, it is unclear whether self-reported physical exercise in leisure (PEL) levels are associated with the brain structure features demonstrated by exercise interventions. This pilot study investigated the relationship between PEL, mood, cognition, and neuromorphometry in patients with idiopathic generalized epilepsy (IGEs) compared to healthy controls (HCs). Seventeen IGEs and 19 age- and sex-matched HCs underwent magnetic resonance imaging (MRI) at 3T. The Baecke Questionnaire of Habitual Physical Activity, Profile of Mood States, and Montreal Cognitive Assessment (MoCA) assessed PEL, mood, and cognition, respectively. Structural MRI data were analyzed by voxel- and surface-based morphometry. IGEs had significantly lower PEL (p < 0.001), poorer mood (p = 0.029), and lower MoCA scores (p = 0.027) than HCs. These group differences were associated with reduced volume, decreased gyrification, and altered surface topology (IGEs < HCs) in frontal, temporal and cerebellar regions involved in executive function, memory retrieval, and emotional regulation, respectively. These preliminary results support the notion that increased PEL may promote neuroplasticity in IGEs, thus emphasizing the role of physical activity in promoting brain health in people with epilepsy.

Cortical Mechanisms Underlying Immersive Interactive Virtual Walking Treatment for Amelioration of Neuropathic Pain after Spinal Cord Injury: Findings from a Preliminary Investigation of Thalamic Inhibitory Function

BACKGROUND

Neuropathic pain following spinal cord injury (SCI) affects approximately 60% of individuals with SCI. Effective pharmacological and non-pharmacological treatments remain elusive. We recently demonstrated that our immersive virtual reality walking intervention (VRWalk) may be effective for SCI NP. Additionally, we found that SCI NP may result from a decrease in thalamic γ-aminobutyric-acid (GABA), which disturbs central sensorimotor processing.

OBJECTIVE

While we identified GABAergic changes associated with SCI NP, a critical outstanding question is whether a decrease in SCI NP generated by our VRWalk intervention causes GABA content to rise.

METHOD

A subset of participants (n = 7) of our VRWalk trial underwent magnetic resonance spectroscopy pre- and post-VRWalk intervention to determine if the decrease in SCI NP is associated with an increase in thalamic GABA.

RESULTS

The findings revealed a significant increase in thalamic GABA content from pre- to post-VRWalk treatment.

CONCLUSION

While the current findings are preliminary and should be interpreted with caution, pre- to post-VRWalk reductions in SCI NP may be mediated by pre- to post-treatment increases in thalamic GABA by targeting and normalizing maladaptive sensorimotor cortex reorganization. Understanding the underlying mechanisms of pain recovery can serve to validate the efficacy of home-based VR walking treatment as a means of managing pain following SCI. Neuromodulatory interventions aimed at increasing thalamic inhibitory function may provide more effective pain relief than currently available treatments.

LITE-1 mediates behavioral responses to X-rays in Caenorhabditis elegans

Rapid sensory detection of X-ray stimulation has been documented across a wide variety of species, but few studies have explored the underlying molecular mechanisms. Here we report the discovery of an acute behavioral avoidance response in wild type Caenorhabditis elegans to X-ray stimulation. The endogenous C. elegans UV-photoreceptor protein LITE-1 was found to mediate the locomotory avoidance response. Transgenic expression of LITE-1 in C. elegans muscle cells resulted in paralysis and egg ejection responses to X-ray stimulation, demonstrating that ectopic expression of LITE-1 can confer X-ray sensitivity to otherwise X-ray insensitive cells. This work represents the first demonstration of rapid X-ray based genetically targeted (X-genetic) manipulation of cellular electrical activity in intact behaving animals. Our findings suggest that LITE-1 has strong potential for use in this minimally invasive form of neuromodulation to transduce transcranial X-ray signals for precise manipulation of neural activity in mammals, bypassing the need for invasive surgical implants to deliver stimulation.

Magnetic Resonance Imaging of Focused Ultrasound Radiation Force Strain Fields for Discrimination of Solid and Liquid Phases

OBJECTIVE

Focused ultrasound (FUS) has become a non-invasive option for some surgical procedures, including tumor ablation and thalamotomy. Extension of magnetic resonance (MR) imaging-guided focused ultrasound for ablation of slowly perfused cerebrovascular lesions requires a novel treatment monitoring method that does not rely on thermometry or high-frequency Doppler methods. The goal of this study was to evaluate the sensitivity and specificity of strain estimates based on MR acoustic radiation force imaging (MR-ARFI) for differentiation of solids and liquids.

METHODS

Strain fields were estimated in gelatin-based tissue-mimicking focused ultrasound phantoms on the basis of apparent displacement fields measured by MR-ARFI. MR-ARFI and diffusion-weighted imaging (DWI) measurements were made before and after FUS-induced heating to evaluate the performance of displacement, strain and apparent diffusion coefficient (ADC) measurements for the discrimination of solid and liquid phases.

RESULTS

As revealed by receiver operating characteristic analyses, axial normal strain and shear strain components performed significantly better than axial displacement measurements alone when predicting whether a gelatin had melted. Additional measurements must be made to estimate certain strain components, so this trade-off must be considered when developing clinical strategies. ADC had the best overall performance, but DWI is vulnerable to signal dropouts and susceptibility artifacts near cerebrovascular lesions, so this metric may have limited clinical applicability.

CONCLUSION

Strain components based on MR-ARFI apparent displacement measurements perform better than apparent displacement measurements alone at discriminating between solids and liquids. These methods are applicable to FUS treatment monitoring and evaluation of mechanical tissue properties in vivo.

X-ray perception: Animal studies of sensory and behavioral responses to X-rays

Since their discovery in 1895, many studies have been conducted to understand the effect of X-rays on neural function and behavior in animals. These studies examined a range of acute and chronic effects, and a subset of studies has attempted to determine if X-rays can produce any sensory responses. Here we review literature on animal behavioral responses to X-rays from 1895 until 2021 to assess the evidence for detection of X-rays by sensory receptors in animals. We focus on the changes in appetitive and consummatory behavior, radiotaxis, behavioral arousal, and olfactory responses to X-rays that have been reported in the literature. Taken together, the reviewed literature provides a large body of evidence that X-rays can induce sensory responses in a wide variety of animals and also suggests that these responses are mediated by known sensory receptors. Furthermore, we postulate the role of reactive oxygen species (ROS), the most biologically active byproduct of X-rays, as a key mediator of sensory receptor responses to X-rays.

Somatotopic Mapping of the Fingers in the Somatosensory Cortex Using Functional Magnetic Resonance Imaging: A Review of Literature

Multiple studies have demonstrated finger somatotopy in humans and other primates using a variety of brain mapping techniques including functional magnetic resonance imaging (fMRI). Here, we review the literature to better understand the reliability of fMRI for mapping the somatosensory cortex. We have chosen to focus on the hand and fingers as these areas have the largest representation and have been the subject of the largest number of somatotopic mapping experiments. Regardless of the methods used, individual finger somatosensory maps were found to be organized across Brodmann areas (BAs) 3b, 1, and 2 in lateral-to-medial and inferior-to-superior fashion moving from the thumb to the pinky. However, some consistent discrepancies are found that depend principally on the method used to stimulate the hand and fingers. Therefore, we suggest that a comparative analysis of different types of stimulation be performed to address the differences described in this review.

Focused Ultrasound Ablation of an Arteriovenous Malformation Model

Brain AVMs are rare but serious vascular lesions that often pose a management dilemma between the risk of various treatment modalities and uncertain natural history during observation. We describe preliminary data on the use of focused ultrasound as a novel therapeutic strategy. In an AVM model, one session of ultrasound gradually reduced flow through the lesion without inducing rupture. Due to its non-invasive yet immediate ablative effects, focused ultrasound may allow safer treatment of AVMs. However, further studies are needed to clarify its efficacy and side effect profile.

Somatotopic Arrangement of the Human Primary Somatosensory Cortex Derived From Functional Magnetic Resonance Imaging

Functional magnetic resonance imaging (fMRI) was used to estimate neuronal activity in the primary somatosensory cortex of six participants undergoing cutaneous tactile stimulation on skin areas spread across the entire body. Differences between the accepted somatotopic maps derived from Penfield's work and those generated by this fMRI study were sought, including representational transpositions or replications across the cortex. MR-safe pneumatic devices mimicking the action of a Wartenberg wheel supplied touch stimuli in eight areas. Seven were on the left side of the body: foot, lower, and upper leg, trunk beneath ribcage, anterior forearm, middle fingertip, and neck above the collarbone. The eighth area was the glabella. Activation magnitude was estimated as the maximum cross-correlation coefficient at a certain phase shift between ideal time series and measured blood oxygen level dependent (BOLD) time courses on the cortical surface. Maximally correlated clusters associated with each cutaneous area were calculated, and cortical magnification factors were estimated. Activity correlated to lower limb stimulation was observed in the paracentral lobule and superomedial postcentral region. Correlations to upper extremity stimulation were observed in the postcentral area adjacent to the motor hand knob. Activity correlated to trunk, face and neck stimulation was localized in the superomedial one-third of the postcentral region, which differed from Penfield's cortical homunculus.

X-ray excited luminescence spectroscopy and imaging with NaGdF4:Eu and Tb

We synthesized and characterized Eu and Tb doped NaGdF4 nanophosphors which generate visible light when excited by a focused X-ray beam. High resolution images were acquired through tissue by measuring light intensity vs. X-ray beam position.

Effects of a carbohydrate-restricted diet on hepatic lipid content in adolescents with non-alcoholic fatty liver disease: A pilot, randomized trial

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) has emerged as the most common form of liver disease among adolescents in industrialized countries. While lifestyle intervention remains the hallmark treatment for NAFLD, the most effective dietary strategy to reverse NAFLD in children is unknown.

OBJECTIVE

The objective of this study was to determine the effects of a moderately CHO-restricted diet (CRD) vs fat-restricted diet (FRD) in adolescents with NAFLD on reduction in liver fat and insulin resistance.

METHODS

Thirty-two children/adolescents (age 9-17) with obesity and NAFLD were randomized to a CRD (<25:25:>50% energy from CHO:protein:fat) or FRD (55:25:20) for 8 weeks. Caloric intakes were calculated to be weight maintaining. Change in hepatic lipid content was measured via magnetic resonance imaging, body composition via dual energy X ray absorptiometry and insulin resistance via a fasting blood sample.

RESULTS

Change in hepatic lipid did not differ with diet, but declined significantly (-6.0 ± 4.7%, P < .001 only within the CRD group. We found significantly greater decreases in insulin resistance (HOMA-IR, <.05), abdominal fat mass (P < .01) and body fat mass (P < .01) in response to the CRD vs FRD.

CONCLUSION

These findings suggest that consumption of a moderately CHO-restricted diet may result in decreased hepatic lipid as well as improvements in body composition and insulin resistance in adolescents with NAFLD even in the absence of intentional caloric restriction. Larger studies are needed to determine whether a CHO-restricted diet induces change in hepatic lipid independent of change in body fat.

Focused ultrasound blood brain barrier opening mediated delivery of MRI-visible albumin nanoclusters to the rat brain for localized drug delivery with temporal control

There is an ongoing need for noninvasive tools to manipulate brain activity with molecular, spatial and temporal specificity. Here we have investigated the use of MRI-visible, albumin-based nanoclusters for noninvasive, localized and temporally specific drug delivery to the rat brain. We demonstrated that IV injected nanoclusters could be deposited into target brain regions via focused ultrasound facilitated blood brain barrier opening. We showed that nanocluster location could be confirmed in vivo with MRI. Additionally, following confirmation of nanocluster delivery, release of the nanocluster payload into brain tissue can be triggered by a second focused ultrasound treatment performed without circulating microbubbles. Release of glutamate from nanoclusters in vivo caused enhanced c-Fos expression, indicating that the loading capacity of the nanoclusters is sufficient to induce neuronal activation. This novel technique for noninvasive stereotactic drug delivery to the brain with temporal specificity could provide a new way to study brain circuits in vivo preclinically with high relevance for clinical translation.

Rationale and design of a single-blind, randomised controlled trial of exercise training for managing learning and memory impairment in persons with multiple sclerosis

INTRODUCTION

This randomised controlled trial (RCT) examines treadmill walking exercise training effects on learning and memory performance, hippocampal volume, and hippocampal resting-state functional connectivity in persons with multiple sclerosis (MS) who have objective impairments in learning new information.

METHODS AND ANALYSIS

Forty fully ambulatory persons with MS who demonstrate objective learning and memory impairments will be randomly assigned into either the intervention or active control study conditions. The intervention condition involves supervised, progressive treadmill walking exercise training three times per week for a 3-month period. The active control condition involves supervised, progressive low-intensity resistive exercise that will be delivered at the same frequency as the intervention condition. The primary outcome will involve composite performance on neuropsychological learning and memory tests, and the secondary outcomes involve MRI measures of hippocampal volume and resting-state functional connectivity administered before and after the 3-month study period. Outcomes will be administered by treatment-blinded assessors using alternate test forms to minimise practice effects, and MRI data processing will be performed by blinded data analysts.

ETHICS AND DISSEMINATION

This study has been approved by a university institutional review board. The primary results will be disseminated via peer-reviewed publications and the final data will be made available to third parties in applicable data repositories. If successful, the results from this study will eventually inform subsequent RCTs for developing physical rehabilitation interventions (ie, treadmill walking exercise training) for improving learning and memory and its relationship with hippocampal outcomes in larger samples of cognitively impaired persons with MS. The results from this early-phase RCT will further lay preliminary groundwork for ultimately providing clinicians and patients with guidelines for better using chronic treadmill walking exercise for improving cognition and brain health. This approach is paramount as learning and memory impairment is common, burdensome and poorly managed in MS.

TRIAL REGISTRATION NUMBER

NCT03319771; Pre-results.

Characterization of different bubble formulations for blood-brain barrier opening using a focused ultrasound system with acoustic feedback control

Focused ultrasound combined with bubble-based agents serves as a non-invasive way to open the blood-brain barrier (BBB). Passive acoustic detection was well studied recently to monitor the acoustic emissions induced by the bubbles under ultrasound energy, but the ability to perform reliable BBB opening with a real-time feedback control algorithm has not been fully evaluated. This study focuses on characterizing the acoustic emissions of different types of bubbles: Optison, Definity, and a custom-made nanobubble. Their performance on reliable BBB opening under real-time feedback control based on acoustic detection was evaluated both in-vitro and in-vivo. The experiments were conducted using a 0.5 MHz focused ultrasound transducer with in-vivo focal pressure ranges from 0.1-0.7 MPa. Successful feedback control was achieved with all three agents when combining with infusion injection. Localized opening was confirmed with Evans blue dye leakage. Microscopic images were acquired to review the opening effects. Under similar total gas volume, nanobubble showed a more reliable opening effect compared to Optison and Definity (p < 0.05). The conclusions obtained from this study confirm the possibilities of performing stable opening using a feedback control algorithm combined with infusion injection. It also opens another potential research area of BBB opening using sub-micron bubbles.

Effectiveness of a carbohydrate restricted diet to treat non-alcoholic fatty liver disease in adolescents with obesity: Trial design and methodology

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disorder among children in the developed world and can progress to cirrhosis, hepatocellular carcinoma, and liver failure. No evidence-based dietary guidelines exist on the most effective diet prescription to treat NAFLD.

OBJECTIVE

To compare the effect of a carbohydrate (CHO)-restricted diet vs fat-restricted diet, the current standard of care, on changes in hepatic fat infiltration, body composition, and metabolic health over an 8-week period among overweight and obese children diagnosed with NAFLD.

METHODS

In this two-arm, parallel design randomized controlled trial (RCT), 40 participants aged 9 to 18 years were randomized to a CHO restricted diet (<25:>50:25% daily calories from CHO: fat: protein) or control, fat restricted diet (55,20:25% daily calories from CHO: fat: protein). This family-based diet intervention included: (1) a 2-week supply of groceries to feed a four-person household specific to the assigned diet; and (2) extensive education on diet implementation through biweekly, diet-specific group and individualized counseling sessions with participants and one parent or guardian led by a registered dietitian (RD). The primary outcome measure of this study was hepatic lipid, measured using magnetic resonance spectroscopy (MRS). Secondary outcomes included liver transaminases; markers of inflammation (hsCRP, IL-6, TNF-α); body composition; visceral adipose tissue; and insulin resistance. All testing was conducted at baseline and week 8; hepatic transaminases were also measured at weeks 2 and 4. This RCT is registered with ClinicalTrials.gov (ID: NCT02787668).

Sensing Passive Eye Response to Impact Induced Head Acceleration Using MEMS IMUs

The eye may act as a surrogate for the brain in response to head acceleration during an impact. Passive eye movements in a dynamic system are sensed by microelectromechanical systems (MEMS) inertial measurement units (IMU) in this paper. The technique is validated using a three-dimensional printed scaled human skull model and on human volunteers by performing drop-and-impact experiments with ribbon-style flexible printed circuit board IMUs inserted in the eyes and reference IMUs on the heads. Data are captured by a microcontroller unit and processed using data fusion. Displacements are thus estimated and match the measured parameters. Relative accelerations and displacements of the eye to the head are computed indicating the influence of the concussion causing impacts.

Portable perfusion phantom for quantitative DCE-MRI of the abdomen

PURPOSE

The aim of this study was to develop a portable perfusion phantom and validate its utility in quantitative dynamic contrast-enhanced magnetic resonance imaging of the abdomen.

METHODS

A portable perfusion phantom yielding a reproducible contrast enhancement curve (CEC) was developed. A phantom package including perfusion and static phantoms were imaged simultaneously with each of three healthy human volunteers in two different 3T MR scanners. Look-up tables correlating reference (known) contrast concentrations with measured ones were created using either the static or perfusion phantom. Contrast maps of image slices showing four organs (liver, spleen, pancreas, and paravertebral muscle) were generated before and after data correction using the look-up tables. The contrast concentrations at 4.5 min after dosing in each of the four organs were averaged for each volunteer. The mean contrast concentrations (4 organs × 3 volunteers = 12) were compared for the two scanners, and the intra-class correlation coefficient (ICC) was calculated. Also, the ICC of the mean K^trans values between the two scanners was calculated before and after data correction.

RESULTS

The repeatability coefficient of CECs of perfusion phantom was higher than 0.997 in all measurements. The ICC of the tissue contrast concentrations between the two scanners was 0.693 before correction, but increased to 0.974 after correction using the look-up tables (LUTs) of perfusion phantom. However, the ICC was not increased after correction using static phantom (ICC: 0.617). Similarly, the ICC of the K^trans values was 0.899 before correction, but increased to 0.996 after correction using perfusion phantom LUTs. The ICC of the K^trans values, however, was not increased when static phantom LUTs were used (ICC: 0.866).

CONCLUSIONS

The perfusion phantom reduced variability in quantitating contrast concentration and K^trans values of human abdominal tissues across different MR units, but static phantom did not. The perfusion phantom has the potential to facilitate multi-institutional clinical trials employing quantitative DCE-MRI to evaluate various abdominal malignancies.

Prolonged treatment with bevacizumab is associated with brain atrophy: a pilot study in patients with high-grade gliomas

Bevacizumab is widely used for treatment of high-grade gliomas and other malignancies. Because bevacizumab has been shown to be associated with neurocognitive decline, this study is designed to investigate whether prolonged treatment with bevacizumab is also associated with brain atrophy. We identified 12 high-grade glioma patients who received bevacizumab for 12 months at the first recurrence and 13 matched controls and blindly compared the volumes of the contralateral hemispheres and contralateral ventricle in these two groups at baseline and after 12 ± 2 months of the baseline scan by two independent analyses. The volumes of the contralateral hemispheres and ventricles did not differ significantly between the two groups at baseline. Whereas, in the control group the volumes of the contralateral hemisphere changed subtly from baseline to follow-up (p = 0.23), in the bevacizumab-treated group the volumes significantly decreased from baseline to follow-up (p = 0.03). There was significant increase in the contralateral ventricle volume from base line to follow-up scans in both the control group (p = 0.01) and in the bevacizumab group (p = 0.005). Both the absolute and the percentage changes of contralateral hemisphere volumes and contralateral ventricular volumes between the two patient groups were statistically significant (p < 0.05). Results of this study demonstrate prolonged treatment with bevacizumab is associated with atrophy of the contralateral brain hemisphere.

Smaller regional gray matter volume in homeless african american cocaine-dependent men: a preliminary report

Models of addiction include abnormalities in parts of the brain involving executive function/inhibitory control. Although previous studies have reported evidence of structural abnormalities in cocaine-dependent individuals, none have specifically targeted the homeless. The present preliminary study investigated brain structure in such an understudied group, homeless, crack-cocaine-dependent African American men (n = 9), comparing it to that in healthy controls (n = 8). Structural data were analyzed using voxel based morphometry (VBM) and a regions of interest (ROI) analysis. Homeless cocaine-dependent individuals had smaller gray matter volume in dorsolateral prefrontal cortex, anterior cingulate, the cerebellum, insula, and superior temporal gyrus. Most of these areas subserve executive function or inhibitory control. These results are similar to those found in most previous studies of non-homeless cocaine-dependent individuals. Reduced gray matter in executive function/inhibitory control regions of the brain in cocaine-dependent individuals may be a preexisting risk factor for the development of addiction and/or a consequence of drug abuse.

Spin-echo SS-PARSE: a PARSE MRI method to estimate frequency, R(2) and R(2)(') in a single shot

Spin-echo signals allow separate measurements of irreversible and reversible relaxation rates in MRI. A spin-echo version of single-shot parameter assessment by retrieval from signal encoding (SE-SS-PARSE) method has been developed to quantitatively and accurately map transverse magnetization magnitude, frequency, irreversible and reversible relaxation rates in a single shot. These image parameters can be applied to fMRI research as well as a number of neuroimaging applications. Following a description of the signal model, this article demonstrates the performance of SE-SS-PARSE in simulations with different noise levels and in phantom experiments. By solving an inverse problem, the estimated irreversible and reversible relaxation rates in SE-SS-PARSE are highly correlated with the reference relaxation rates from a standard technique (correlation coefficients: r(1)=0.9636 for reversible relaxation rate, r(2)=0.9788 for irreversible relaxation rate). The rapid SE-SS-PARSE technique has the potential to monitor transient changes in R(2) and R(2)(') while minimizing motion artifacts and also is free of geometric and ghosting errors. It is expected that this fast scan technique will find applications in both scientific research and clinical diagnosis.

Sources of referral to early phase clinical trials: a case for putting all your eggs in one basket

Abstract #3116

Background: Studies suggest that only 2% to 3% of all adult cancer patients and approximately 5% of breast cancer patients enroll in clinical trials. To better understand the factors that contribute to enrollment we collected data from patients on sources that prompted them to contact us.&#x2028; Methods: From Jan 2005 to Apr 2008 we screened nearly 400 patients for 8 Phase I/II clinical trials focused on immunotherapy of breast and ovarian cancer. We queried subjects about informational sources that led them to consider our clinical studies. Patients learned about our trials from sources including: Clinicians, the Internet (advocacy group websites, search engines, government/university sites), Other patients, Family/friends, Media, Community events and Postings seeking research participants. Many patients who cited a clinician as their referral source specifically referenced a private, multi-site breast cancer clinic in Southern California with which our clinical group has formed a partnership, or consortium. To ensure that this was represented in the data and because the clinician category comprised a large percentage of the referral sources we split the category into 2 groups-one being the private practice in California (to be referred to as “consortium”) and the other being all other clinicians.&#x2028; Results: Of the 399 patients screened, 336 (84%) were considered potentially eligible for study. A total of 72 patients, or 18% of those screened have enrolled in one of our trials to date.&#x2028; Among patients screened, most learned about our trials from clinicians outside the consortium (34%), the Internet (27%), and consortium clinicians (15%). Patients most often named her2support.org (35%) and clinicaltrials.gov (23%) as their specific Internet sources. The remaining sources, family/friends, patients, media sources, community events and postings in medical facilities, were each cited by &lt;5% of patients.&#x2028; Although consortium clinicians were responsible for only 15% of referrals, 50% of their referrals enrolled in a study. Only 16% of patients referred by other clinicians and 9% referred via the Internet were enrolled. Though other clinicians and the Internet are the most common referral sources, referrals from our consortium were significantly more likely to enroll than any other source (p&lt;0.001).&#x2028; This may be due to the fact that patients referred by the consortium were more likely to meet eligibility criteria. Relative to 93% of consortium referrals, 87% of other clinician and 79% of Internet referrals were potentially eligible for trial (p&lt;0.05). Patients referred by our consortium were significantly more likely to meet study criteria relative to those referred by other sources.&#x2028; Discussion: Physician referrals often lead to higher accrual to clinical trials relative to other referral sources. Our data reveal that accrual can be further improved by forming a close collaborative relationship with a single select practice of clinicians.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 3116.

Validation of V-SS-PARSE for single-shot flow measurement

As a variant of Single-Shot Parameter Assessment by Retrieval from Signal Encoding, Velocity Single-Shot Parameter Assessment by Retrieval from Signal Encoding, a single-shot imaging method, has been developed to realize fast and straightforward flow quantification by solving inverse problems. A robust signal model, including its local magnetization and its phase evolution during signaling (resulting in a more precise representation of the sampled signal) is described here. Magnitude, velocity, relaxation rate and frequency information can be retrieved without any extra reference image acquisitions, as demonstrated by phantom studies. In the presence of stationary background, retrieved magnitude maps and velocity maps show results comparable to those obtained by phase-contrast methods (r>.99, P=.005), even with brief single-shot 70-ms acquisition.