Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 119
Filtrar
1.
Neuroimage ; 217: 116864, 2020 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-32360690

RESUMO

Collegiate football athletes are subject to repeated head impacts. The purpose of this study was to determine whether this exposure can lead to changes in brain structure. This prospective cohort study was conducted with up to 4 years of follow-up on 63 football (high-impact) and 34 volleyball (control) male collegiate athletes with a total of 315 MRI scans (after exclusions: football n â€‹= â€‹50, volleyball n â€‹= â€‹24, total scans â€‹= â€‹273) using high-resolution structural imaging. Volumetric and cortical thickness estimates were derived using FreeSurfer 5.3's longitudinal pipeline. A linear mixed-effects model assessed the effect of group (football vs. volleyball), time from baseline MRI, and the interaction between group and time. We confirmed an expected developmental decrement in cortical thickness and volume in our cohort (p â€‹< â€‹.001). Superimposed on this, total cortical gray matter volume (p â€‹= â€‹.03) and cortical thickness within the left hemisphere (p â€‹= â€‹.04) showed a group by time interaction, indicating less age-related volume reduction and thinning in football compared to volleyball athletes. At the regional level, sport by time interactions on thickness and volume were identified in the left orbitofrontal (p â€‹= â€‹.001), superior temporal (p â€‹= â€‹.001), and postcentral regions (p â€‹< â€‹.001). Additional cortical thickness interactions were found in the left temporal pole (p â€‹= â€‹.003) and cuneus (p â€‹= â€‹.005). At the regional level, we also found main effects of sport in football athletes characterized by reduced volume in the right hippocampus (p â€‹= â€‹.003), right superior parietal cortical gray (p â€‹< â€‹.001) and white matter (p â€‹< â€‹.001), and increased volume of the left pallidum (p â€‹= â€‹.002). Within football, cortical thickness was higher with greater years of prior play (left hemisphere p â€‹= â€‹.013, right hemisphere p â€‹= â€‹.005), and any history of concussion was associated with less cortical thinning (left hemisphere p â€‹= â€‹.010, right hemisphere p â€‹= â€‹.011). Additionally, both position-associated concussion risk (p â€‹= â€‹.002) and SCAT scores (p â€‹= â€‹.023) were associated with less of the expected volume decrement of deep gray structures. This prospective longitudinal study comparing football and volleyball athletes shows divergent age-related trajectories of cortical thinning, possibly reflecting an impact-related alteration of normal cortical development. This warrants future research into the underlying mechanisms of impacts to the head on cortical maturation.

2.
Radiology ; 296(1): 143-151, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32368961

RESUMO

Background Whole-body diffusion-weighted (DW) MRI can help detect cancer with high sensitivity. However, the assessment of therapy response often requires information about tumor metabolism, which is measured with fluorine 18 fluorodeoxyglucose (FDG) PET. Purpose To compare tumor therapy response with whole-body DW MRI and FDG PET/MRI in children and young adults. Materials and Methods In this prospective, nonrandomized multicenter study, 56 children and young adults (31 male and 25 female participants; mean age, 15 years ± 4 [standard deviation]; age range, 6-22 years) with lymphoma or sarcoma underwent 112 simultaneous whole-body DW MRI and FDG PET/MRI between June 2015 and December 2018 before and after induction chemotherapy (ClinicalTrials.gov identifier: NCT01542879). The authors measured minimum tumor apparent diffusion coefficients (ADCs) and maximum standardized uptake value (SUV) of up to six target lesions and assessed therapy response after induction chemotherapy according to the Lugano classification or PET Response Criteria in Solid Tumors. The authors evaluated agreements between whole-body DW MRI- and FDG PET/MRI-based response classifications with Krippendorff α statistics. Differences in minimum ADC and maximum SUV between responders and nonresponders and comparison of timing for discordant and concordant response assessments after induction chemotherapy were evaluated with the Wilcoxon test. Results Good agreement existed between treatment response assessments after induction chemotherapy with whole-body DW MRI and FDG PET/MRI (α = 0.88). Clinical response prediction according to maximum SUV (area under the receiver operating characteristic curve = 100%; 95% confidence interval [CI]: 99%, 100%) and minimum ADC (area under the receiver operating characteristic curve = 98%; 95% CI: 94%, 100%) were similar (P = .37). Sensitivity and specificity were 96% (54 of 56 participants; 95% CI: 86%, 99%) and 100% (56 of 56 participants; 95% CI: 54%, 100%), respectively, for DW MRI and 100% (56 of 56 participants; 95% CI: 93%, 100%) and 100% (56 of 56 participants; 95% CI: 54%, 100%) for FDG PET/MRI. In eight of 56 patients who underwent imaging after induction chemotherapy in the early posttreatment phase, chemotherapy-induced changes in tumor metabolism preceded changes in proton diffusion (P = .002). Conclusion Whole-body diffusion-weighted MRI showed significant agreement with fluorine 18 fluorodeoxyglucose PET/MRI for treatment response assessment in children and young adults. © RSNA, 2020 Online supplemental material is available for this article.

3.
Artigo em Inglês | MEDLINE | ID: mdl-32296882

RESUMO

PURPOSE: The purpose of this study was to investigate the prognostic value of whole-body metabolic tumor volume (MTV) and other metabolic tumor parameters, obtained from baseline and first restaging 18F-FDG PET/CT scans in melanoma patients treated with immune checkpoint inhibitors (ICIs). METHODS: Eighty-five consecutive melanoma patients (M, 57; F, 28) treated with ICIs who underwent PET/CT scans before and approximately 3 months after the start of immunotherapy were retrospectively enrolled. Metabolic tumor parameters including MTV for all melanoma lesions were measured on each scan. A Cox proportional hazards model was used for univariate and multivariate analyses of metabolic parameters combined with known clinical prognostic factors associated with overall survival (OS). Kaplan-Meier curves for patients dichotomized based on median values of imaging parameters were generated. RESULTS: The median OS time in all patients was 45 months (95% CI 24-45 months). Univariate analysis demonstrated that MTV obtained from first restaging PET/CT scans (MTVpost) was the strongest prognostic factor for OS among PET/CT parameters (P < 0.0001). The median OS in patients with high MTVpost (≥ 23.44) was 16 months (95% CI 12-32 months) as compared with more than 60 months in patients with low MTVpost (< 23.44) (P = 0.0003). A multivariate model including PET/CT parameters and known clinical prognostic factors revealed that MTVpost and the presence of central nervous system lesions were independent prognostic factors for OS (P = 0.0004, 0.0167, respectively). One pseudoprogression case (1.2%) was seen in this population and classified into the high MTVpost group. CONCLUSION: Whole-body metabolic tumor volume from PET scan acquired approximately 3 months following initiation of immunotherapy (MTVpost) is a strong prognostic indicator of OS in melanoma patients. Although the possibility of pseudoprogression must be considered whenever evaluating first restaging PET imaging, it only occurred in 1 patient in our cohort.

4.
Sci Rep ; 10(1): 6996, 2020 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-32332790

RESUMO

There is a need for noninvasive repeatable biomarkers to detect early cancer treatment response and spare non-responders unnecessary morbidities and costs. Here, we introduce three-dimensional (3D) dynamic contrast enhanced ultrasound (DCE-US) perfusion map characterization as inexpensive, bedside and longitudinal indicator of tumor perfusion for prediction of vascular changes and therapy response. More specifically, we developed computational tools to generate perfusion maps in 3D of tumor blood flow, and identified repeatable quantitative features to use in machine-learning models to capture subtle multi-parametric perfusion properties, including heterogeneity. Models were developed and trained in mice data and tested in a separate mouse cohort, as well as early validation clinical data consisting of patients receiving therapy for liver metastases. Models had excellent (ROC-AUC > 0.9) prediction of response in pre-clinical data, as well as proof-of-concept clinical data. Significant correlations with histological assessments of tumor vasculature were noted (Spearman R > 0.70) in pre-clinical data. Our approach can identify responders based on early perfusion changes, using perfusion properties correlated to gold-standard vascular properties.

5.
Biomedicines ; 8(3)2020 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-32143316

RESUMO

The antigen-specific apoptotic DNA immunotherapeutic, ADi-100, is designed to suppress type 1 diabetes and consists of two DNA plasmids encoding genetic sequences of the apoptosis-inducing molecule, BAX, and the secreted form of the autoantigen, glutamic acid decarboxylase 65, that is CpG hyper-methylated to avoid inflammatory signaling (msGAD55). Upon a four-day treatment with ADi-100 of young female non-obese diabetic (NOD) mice, the frequency of various tolerogenic dendritic cell populations increased in draining lymph nodes; these cells lost the capacity to stimulate glutamic acid decarboxylase (GAD)-specific CD4+ T lymphocytes and were associated with the previously demonstrated enhancement of GAD-specific regulatory T cells. The efficacy of two ADi-100 formulations containing different proportions of BAX and msGAD55, 1:4 (10/40 µg) and 1:2 (17/33 µg), was evaluated in mildly hyperglycemic pre-diabetic NOD female mice. Both formulations suppressed the incidence of diabetes by 80% in an antigen-specific manner, while all untreated mice developed diabetes. However, treatment of pre-diabetic mice with significantly higher hyperglycemia, denoting progressive disease, showed that ADi-100 1:2 strongly suppressed diabetes incidence by 80% whereas the ADi-100 1:4 was less effective (50%). As an antigen-specific monotherapy, ADi-100 is highly efficacious in reversing elevated hyperglycemia to prevent diabetes, in which increasing apoptosis-inducing BAX content is a promising immune tolerance feature.

6.
Magn Reson Med ; 84(3): 1661-1671, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32077521

RESUMO

PURPOSE: Motion artifact limits the clinical translation of high-field MR. We present an optical prospective motion correction system for 7 Tesla MRI using a custom-built, within-coil camera to track an optical marker mounted on a subject. METHODS: The camera was constructed to fit between the transmit-receive coils with direct line of sight to a forehead-mounted marker, improving upon prior mouthpiece work at 7 Tesla MRI. We validated the system by acquiring a 3D-IR-FSPGR on a phantom with deliberate motion applied. The same 3D-IR-FSPGR and a 2D gradient echo were then acquired on 7 volunteers, with/without deliberate motion and with/without motion correction. Three neuroradiologists blindly assessed image quality. In 1 subject, an ultrahigh-resolution 2D gradient echo with 4 averages was acquired with motion correction. Four single-average acquisitions were then acquired serially, with the subject allowed to move between acquisitions. A fifth single-average 2D gradient echo was acquired following subject removal and reentry. RESULTS: In both the phantom and human subjects, deliberate and involuntary motion were well corrected. Despite marked levels of motion, high-quality images were produced without spurious artifacts. The quantitative ratings confirmed significant improvements in image quality in the absence and presence of deliberate motion across both acquisitions (P < .001). The system enabled ultrahigh-resolution visualization of the hippocampus during a long scan and robust alignment of serially acquired scans with interspersed movement. CONCLUSION: We demonstrate the use of a within-coil camera to perform optical prospective motion correction and ultrahigh-resolution imaging at 7 Tesla MRI. The setup does not require a mouthpiece, which could improve accessibility of motion correction during 7 Tesla MRI exams.

7.
Neurology ; 93(24): e2284-e2293, 2019 12 10.
Artigo em Inglês | MEDLINE | ID: mdl-31748250

RESUMO

OBJECTIVE: To test the hypothesis that transcranial magnetic resonance-guided focused ultrasound (tcMRgFUS) thalamotomy is effective, durable, and safe for patients with medication-refractory essential tremor (ET), we assessed clinical outcomes at 3-year follow-up of a controlled multicenter prospective trial. METHODS: Outcomes were based on the Clinical Rating Scale for Tremor, including hand combined tremor-motor (scale of 0-32), functional disability (scale of 0-32), and postural tremor (scale of 0-4) scores, and total scores from the Quality of Life in Essential Tremor Questionnaire (scale of 0-100). Scores at 36 months were compared with baseline and at 6 months after treatment to assess for efficacy and durability. Adverse events were also reported. RESULTS: Measured scores remained improved from baseline to 36 months (all p < 0.0001). Range of improvement from baseline was 38%-50% in hand tremor, 43%-56% in disability, 50%-75% in postural tremor, and 27%-42% in quality of life. When compared to scores at 6 months, median scores increased for hand tremor (95% confidence interval [CI] 0-2, p = 0.0098) and disability (95% CI 1-4, p = 0.0001). During the third follow-up year, all previously noted adverse events remained mild or moderate, none worsened, 2 resolved, and no new adverse events occurred. CONCLUSIONS: Results at 3 years after unilateral tcMRgFUS thalamotomy for ET show continued benefit, and no progressive or delayed complications. Patients may experience mild degradation in some treatment metrics by 3 years, though improvement from baseline remains significant. CLINICALTRIALSGOV IDENTIFIER: NCT01827904. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that for patients with severe ET, unilateral tcMRgFUS thalamotomy provides durable benefit after 3 years.


Assuntos
Tremor Essencial/diagnóstico , Tremor Essencial/cirurgia , Psicocirurgia/métodos , Tálamo/cirurgia , Terapia por Ultrassom/métodos , Idoso , Idoso de 80 Anos ou mais , Estudos de Coortes , Estudos Cross-Over , Tremor Essencial/fisiopatologia , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Psicocirurgia/tendências , Método Simples-Cego , Inquéritos e Questionários , Tálamo/fisiologia , Fatores de Tempo , Terapia por Ultrassom/tendências
8.
Stroke ; 50(12): 3408-3415, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31619150

RESUMO

Background and Purpose- Imaging is frequently used to select acute stroke patients for intra-arterial therapy. Quantitative cerebral blood flow can be measured noninvasively with arterial spin labeling magnetic resonance imaging. Cerebral blood flow levels in the contralateral (unaffected) hemisphere may affect capacity for collateral flow and patient outcome. The goal of this study was to determine whether higher contralateral cerebral blood flow (cCBF) in acute stroke identifies patients with better 90-day functional outcome. Methods- Patients were part of the prospective, multicenter iCAS study (Imaging Collaterals in Acute Stroke) between 2013 and 2017. Consecutive patients were enrolled after being diagnosed with anterior circulation acute ischemic stroke. Inclusion criteria were ischemic anterior circulation stroke, baseline National Institutes of Health Stroke Scale score ≥1, prestroke modified Rankin Scale score ≤2, onset-to-imaging time <24 hours, with imaging including diffusion-weighted imaging and arterial spin labeling. Patients were dichotomized into high and low cCBF groups based on median cCBF. Outcomes were assessed by day-1 and day-5 National Institutes of Health Stroke Scale; and day-30 and day-90 modified Rankin Scale. Multivariable logistic regression was used to test whether cCBF predicted good neurological outcome (modified Rankin Scale score, 0-2) at 90 days. Results- Seventy-seven patients (41 women) met the inclusion criteria with median (interquartile range) age of 66 (55-76) yrs, onset-to-imaging time of 4.8 (3.6-7.7) hours, and baseline National Institutes of Health Stroke Scale score of 13 (9-20). Median cCBF was 38.9 (31.2-44.5) mL per 100 g/min. Higher cCBF predicted good outcome at day 90 (odds ratio, 4.6 [95% CI, 1.4-14.7]; P=0.01), after controlling for baseline National Institutes of Health Stroke Scale, diffusion-weighted imaging lesion volume, and intra-arterial therapy. Conclusions- Higher quantitative cCBF at baseline is a significant predictor of good neurological outcome at day 90. cCBF levels may inform decisions regarding stroke triage, treatment of acute stroke, and general outcome prognosis. Clinical Trial Registration- URL: https://www.clinicaltrials.gov. Unique identifier: NCT02225730.


Assuntos
Encéfalo/irrigação sanguínea , Circulação Cerebrovascular/fisiologia , Acidente Vascular Cerebral/diagnóstico por imagem , Acidente Vascular Cerebral/fisiopatologia , Idoso , Isquemia Encefálica/complicações , Isquemia Encefálica/diagnóstico por imagem , Isquemia Encefálica/fisiopatologia , Feminino , Humanos , Imagem por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Neuroimagem/métodos , Estudos Prospectivos , Acidente Vascular Cerebral/etiologia , Resultado do Tratamento
9.
Clin Cancer Res ; 25(22): 6683-6691, 2019 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-31444249

RESUMO

PURPOSE: Quantitative ultrasound approaches can capture tissue morphologic properties to augment clinical diagnostics. This study aims to clinically assess whether quantitative ultrasound spectroscopy (QUS) parameters measured in hepatocellular carcinoma (HCC) tissues can be differentiated from those measured in at-risk or healthy liver parenchyma. EXPERIMENTAL DESIGN: This prospective Health Insurance Portability and Accountability Act (HIPAA)-compliant study was approved by the Institutional Review Board. Fifteen patients with HCC, 15 non-HCC patients with chronic liver disease, and 15 healthy volunteers were included (31.1% women; 68.9% men). Ultrasound radiofrequency data were acquired in each patient in both liver lobes at two focal depths (3/9 cm). Region of interests (ROIs) were drawn on HCC and liver parenchyma. The average normalized power spectrum for each ROI was extracted, and a linear regression was fit within the -6 dB bandwidth, from which the midband fit (MBF), spectral intercept (SI), and spectral slope (SS) were extracted. Differences in QUS parameters between the ROIs were tested by a mixed-effects regression. RESULTS: There was a significant intraindividual difference in MBF, SS, and SI between HCC and adjacent liver parenchyma (P < 0.001), and a significant interindividual difference between HCC and at-risk and healthy non-HCC parenchyma (P < 0.001). In patients with HCC, cirrhosis (n = 13) did not significantly change any of the three parameters (P > 0.8) in differentiating HCC from non-HCC parenchyma. MBF (P = 0.12), SI (P = 0.33), and SS (P = 0.57) were not significantly different in non-HCC tissue among the groups. CONCLUSIONS: The QUS parameters are significantly different in HCC versus non-HCC liver parenchyma, independent of underlying cirrhosis. This could be leveraged for improved HCC detection with ultrasound in the future.

10.
Mol Imaging Biol ; 2019 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-31325083

RESUMO

PURPOSE: Tumor response assessments on positron emission tomography (PET)/magnetic resonance imaging (MRI) scans require correct quantification of radiotracer uptake in tumors and normal organs. Historically, MRI scans have been enhanced with gadolinium (Gd)-based contrast agents, which are now controversial due to brain deposition. Recently, ferumoxytol nanoparticles have been identified as an alternative to Gd-based contrast agents because they provide strong tissue enhancement on MR images but are not deposited in the brain. However, it is not known if the strong T1- and T2-contrast obtained with iron oxide nanoparticles such as ferumoxytol could affect MR-based attenuation correction of PET data. The purpose of our study was to investigate if ferumoxytol administration prior to a 2-deoxy-2-[18F]fluoro-D-glucose [18F]FDG PET/MR scan would change standardized uptake values (SUV) of normal organs. PROCEDURES: Thirty pediatric patients (6-18 years) with malignant tumors underwent [18F]FDG-PET/MR scans (dose 3 MBq/kg). Fifteen patients received an intravenous ferumoxytol injection (5 mg Fe/kg) prior to the [18F]FDG-PET/MR scans (group 1). Fifteen additional age- and sex-matched patients received unenhanced [18F]FDG-PET/MR scans (group 2). For attenuation correction of PET data, we used a Dixon-based gradient echo sequence (TR 4.2 ms, TE 1.1, 2.3 ms, FA 5), which accounted for soft tissue, lung, fat, and background air. We used a mixed linear effects model to compare the tissue MRI enhancement, quantified as the signal-to-noise ratio (SNR), as well as tissue radiotracer signal, quantified as SUVmean and SUVmax, between group 1 and group 2. Alpha was assumed at 0.05. RESULTS: The MRI enhancement of the blood and solid extra-cerebral organs, quantified as SNR, was significantly higher on ferumoxytol-enhanced MRI scans compared to unenhanced scans (p < 0.001). However, SUVmean and SUVmax values, corrected based on the patients' body weight or body surface area, were not significantly different between the two groups (p > 0.05). CONCLUSION: Ferumoxytol administration prior to a [18F]FDG PET/MR scan did not change standardized uptake values (SUV) of solid extra-cerebral organs. This is important, because it allows injection of ferumoxytol contrast prior to a PET/MRI procedure and, thereby, significantly accelerates image acquisition times.

11.
J Neurotrauma ; 36(19): 2762-2773, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31044639

RESUMO

Collegiate football athletes are subject to repeated traumatic brain injuriesthat may cause brain injury. The hippocampus is composed of several distinct subfields with possible differential susceptibility to injury. The aim of this study is to determine whether there are longitudinal changes in hippocampal subfield volume in collegiate football. A prospective cohort study was conducted over a 5-year period tracking 63 football and 34 volleyball male collegiate athletes. Athletes underwent high-resolution structural magnetic resonance imaging, and automated segmentation provided hippocampal subfield volumes. At baseline, football (n = 59) athletes demonstrated a smaller subiculum volume than volleyball (n = 32) athletes (-67.77 mm3; p = 0.012). A regression analysis performed within football athletes similarly demonstrated a smaller subiculum volume among those at increased concussion risk based on athlete position (p = 0.001). For the longitudinal analysis, a linear mixed-effects model assessed the interaction between sport and time, revealing a significant decrease in cornu ammonis area 1 (CA1) volume in football (n = 36) athletes without an in-study concussion compared to volleyball (n = 23) athletes (volume difference per year = -35.22 mm3; p = 0.005). This decrease in CA1 volume over time was significant when football athletes were examined in isolation from volleyball athletes (p = 0.011). Thus, this prospective, longitudinal study showed a decrease in CA1 volume over time in football athletes, in addition to baseline differences that were identified in the downstream subiculum. Hippocampal changes may be important to study in high-contact sports.

12.
J Neurosurg ; : 1-6, 2019 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-31026836

RESUMO

OBJECTIVE: Skull density ratio (SDR) assesses the transparency of the skull to ultrasound. Magnetic resonance-guided focused ultrasound (MRgFUS) thalamotomy in essential tremor (ET) patients with a lower SDR may be less effective, and the risk for complications may be increased. To address these questions, the authors analyzed clinical outcomes of MRgFUS thalamotomy based on SDRs. METHODS: In 189 patients, 3 outcomes were correlated with SDRs. Efficacy was based on improvement in Clinical Rating Scale for Tremor (CRST) scores 1 year after MRgFUS. Procedural efficiency was determined by the ease of achieving a peak voxel temperature of 54°C. Safety was based on the rate of the most severe procedure-related adverse event. SDRs were categorized at thresholds of 0.45 and 0.40, selected based on published criteria. RESULTS: Of 189 patients, 53 (28%) had an SDR < 0.45 and 20 (11%) had an SDR < 0.40. There was no significant difference in improvement in CRST scores between those with an SDR ≥ 0.45 (58% ± 24%), 0.40 ≤ SDR < 0.45 (i.e., SDR ≥ 0.40 but < 0.45) (63% ± 27%), and SDR < 0.40 (49% ± 28%; p = 0.0744). Target temperature was achieved more often in those with an SDR ≥ 0.45 (p < 0.001). Rates of adverse events were lower in the groups with an SDR < 0.45 (p = 0.013), with no severe adverse events in these groups. CONCLUSIONS: MRgFUS treatment of ET can be effectively and safely performed in patients with an SDR < 0.45 and an SDR < 0.40, although the procedure is more efficient when SDR ≥ 0.45.

13.
Pediatr Radiol ; 49(5): 646-651, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30712160

RESUMO

BACKGROUND: Resistivity index (RI) of the pericallosal artery as is commonly measured during head ultrasound (US) examination in neonates. Some studies have shown that RI measured with gentle compression of the fontanelle provides additional information in cases of neonatal brain anomalies. OBJECTIVE: The purpose of this study was to establish normal RI values with and without compression in a large population of neonates with normal cranial ultrasound as a function of gestational age. MATERIALS AND METHODS: The authors of this retrospective study reviewed the RI of 323 infants with normal gray-scale cranial US and with a gestational age ranging 26-42 weeks. We conducted the exams both with and without compression of the anterior fontanelle and we studied changes in RI depending on gestational age, gender and type of delivery. RESULTS: Infants with a gestational age of more than 35 weeks tended to have a lower RI (P=0.011). The compression of the anterior fontanelle emphasized the change in RI with increasing gestational age, with higher gestational ages having a lower RI (P<0.001). The results concerning the percentage change between baseline RI and RI with compression showed that infants with higher gestational ages have a smaller percentage change in RI (P=0.002). CONCLUSION: We established the normal values for RI from 26 weeks to 42 weeks of gestation. The results of the study show the importance of taking the gestational age into consideration when evaluating the RI.


Assuntos
Artérias Cerebrais/diagnóstico por imagem , Artérias Cerebrais/fisiologia , Fontanelas Cranianas/diagnóstico por imagem , Fontanelas Cranianas/fisiologia , Ultrassonografia Doppler Transcraniana/métodos , Resistência Vascular/fisiologia , Feminino , Idade Gestacional , Humanos , Recém-Nascido , Masculino , Valores de Referência , Reprodutibilidade dos Testes , Estudos Retrospectivos
14.
Cell Death Dis ; 10(2): 36, 2019 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-30674867

RESUMO

CD47 monoclonal antibodies (mAbs) activate tumor-associated macrophages (TAMs) in sarcomas to phagocytose and eliminate cancer cells. Though CD47 mAbs have entered clinical trials, diagnostic tests for monitoring therapy response in vivo are currently lacking. Ferumoxytol is an FDA-approved iron supplement which can be used "off label" as a contrast agent: the nanoparticle-based drug is phagocytosed by TAM and can be detected with magnetic resonance imaging (MRI). We evaluated if ferumoxytol-enhanced MRI can monitor TAM response to CD47 mAb therapy in osteosarcomas. Forty-eight osteosarcoma-bearing mice were treated with CD47 mAb or control IgG and underwent pre- and post-treatment ferumoxytol-MRI scans. Tumor enhancement, quantified as T2 relaxation times, was compared with the quantity of TAMs as determined by immunofluorescence microscopy and flow cytometry. Quantitative data were compared between experimental groups using exact two-sided Wilcoxon rank-sum tests. Compared to IgG-treated controls, CD47 mAb-treated tumors demonstrated significantly shortened T2 relaxation times on ferumoxytol-MRI scans (p < 0.01) and significantly increased F4/80+CD80+ M1 macrophages on histopathology (p < 0.01). CD47 mAb-treated F4/80+ macrophages demonstrated significantly augmented phagocytosis of ferumoxytol nanoparticles (p < 0.01). Thus, we conclude that ferumoxytol-MRI can detect TAM response to CD47 mAb in mouse models of osteosarcoma. The ferumoxytol-MRI imaging test could be immediately applied to monitor CD47 mAb therapies in clinical trials.


Assuntos
Anticorpos Monoclonais/metabolismo , Antígeno CD47/genética , Imunoterapia/métodos , Macrófagos/metabolismo , Imagem por Ressonância Magnética/métodos , Nanopartículas/metabolismo , Osteossarcoma/genética , Animais , Humanos , Camundongos , Osteossarcoma/patologia
15.
J Magn Reson Imaging ; 49(7): e271-e281, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30614145

RESUMO

BACKGROUND: Pelvic ultrasound (US) diagnosis of uterine fibroids may overlook coexisting gynecological conditions that contribute to women's symptoms. PURPOSE: To determine the added value of pelvic MRI for women diagnosed with symptomatic fibroids by US, and to identify clinical factors associated with additional MRI findings. STUDY TYPE: Retrospective observational study. POPULATION: In all, 367 consecutive women with fibroids diagnosed by US and referred to our multidisciplinary fibroid center between 2013-2017. FIELD STRENGTH/SEQUENCE: All patients had both pelvic US and MRI prior to their consultations. MRIs were performed at 1.5 T or 3 T and included multiplanar T2 -weighted sequences, and precontrast and postcontrast T1 -weighted imaging. ASSESSMENT: Demographics, symptoms, uterine fibroid symptom severity scores, and health-related quality of life scores, as well as imaging findings were evaluated. STATISTICAL TESTS: Patients were separated into two subgroups according to whether MRI provided additional findings to the initial US. Univariate and multivariate regression analyses were performed. RESULTS: Pelvic MRI provided additional information in 162 patients (44%; 95% confidence interval [CI] 39-49%). The most common significant findings were adenomyosis (22%), endometriosis (17%), and partially endocavitary fibroids (15%). Women with pelvic pain, health-related quality of life scores less than 30 out of 100, or multiple fibroids visualized on US had greater odds of additional MRI findings (odds ratio [OR] 1.68, 2.26, 1.63; P = 0.02, 0.004, 0.03, respectively), while nulliparous women had reduced odds (OR 0.55, P = 0.01). Patients with additional MRI findings were treated less often with uterine fibroid embolization (14% vs. 36%, P < 0.001) or MR-guided focused US (1% vs. 5%, P = 0.04), and more often with medical management (17% vs. 8%, P = 0.01). DATA CONCLUSION: Pelvic MRI revealed additional findings in more than 40% of women presenting with symptoms initially ascribed to fibroids by US. Further evaluation using MRI is particularly useful for parous women with pelvic pain, poor quality of life scores, and/or multiple fibroids. LEVEL OF EVIDENCE: 4 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2019.

16.
Stroke ; 50(2): 373-380, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30636572

RESUMO

Background and Purpose- Noninvasive imaging of brain perfusion has the potential to elucidate pathophysiological mechanisms underlying Moyamoya disease and enable clinical imaging of cerebral blood flow (CBF) to select revascularization therapies for patients. We used hybrid positron emission tomography (PET)/magnetic resonance imaging (MRI) technology to characterize the distribution of hypoperfusion in Moyamoya disease and its relationship to vessel stenosis severity, through comparisons with a normative perfusion database of healthy controls. Methods- To image CBF, we acquired [15O]-water PET as a reference and simultaneously acquired arterial spin labeling (ASL) MRI scans in 20 Moyamoya patients and 15 age-matched, healthy controls on a PET/MRI scanner. The ASL MRI scans included a standard single-delay ASL scan with postlabel delay of 2.0 s and a multidelay scan with 5 postlabel delays (0.7-3.0s) to estimate and account for arterial transit time in CBF quantification. The percent volume of hypoperfusion in patients (determined as the fifth percentile of CBF values in the healthy control database) was the outcome measure in a logistic regression model that included stenosis grade and location. Results- Logistic regression showed that anterior ( P<0.0001) and middle cerebral artery territory regions ( P=0.003) in Moyamoya patients were susceptible to hypoperfusion, whereas posterior regions were not. Cortical regions supplied by arteries with stenosis on MR angiography showed more hypoperfusion than normal arteries ( P=0.001), but the extent of hypoperfusion was not different between mild-moderate versus severe stenosis. Multidelay ASL did not perform differently from [15O]-water PET in detecting perfusion abnormalities, but standard ASL overestimated the extent of hypoperfusion in patients ( P=0.003). Conclusions- This simultaneous PET/MRI study supports the use of multidelay ASL MRI in clinical evaluation of Moyamoya disease in settings where nuclear medicine imaging is not available and application of a normative perfusion database to automatically identify abnormal CBF in patients.


Assuntos
Bases de Dados Factuais , Imagem por Ressonância Magnética , Artéria Cerebral Média , Doença de Moyamoya , Tomografia por Emissão de Pósitrons , Adolescente , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Artéria Cerebral Média/diagnóstico por imagem , Artéria Cerebral Média/fisiopatologia , Doença de Moyamoya/diagnóstico por imagem , Doença de Moyamoya/fisiopatologia , Marcadores de Spin
17.
J Magn Reson Imaging ; 49(7): e183-e194, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30582251

RESUMO

BACKGROUND: Clinical knee MRI protocols require upwards of 15 minutes of scan time. PURPOSE/HYPOTHESIS: To compare the imaging appearance of knee abnormalities depicted with a 5-minute 3D double-echo in steady-state (DESS) sequence with separate echo images, with that of a routine clinical knee MRI protocol. A secondary goal was to compare the imaging appearance of knee abnormalities depicted with 5-minute DESS paired with a 2-minute coronal proton-density fat-saturated (PDFS) sequence. STUDY TYPE: Prospective. SUBJECTS: Thirty-six consecutive patients (19 male) referred for a routine knee MRI. FIELD STRENGTH/SEQUENCES: DESS and PDFS at 3T. ASSESSMENT: Five musculoskeletal radiologists evaluated all images for the presence of internal knee derangement using DESS, DESS+PDFS, and the conventional imaging protocol, and their associated diagnostic confidence of the reading. STATISTICAL TESTS: Differences in positive and negative percent agreement (PPA and NPA, respectively) and 95% confidence intervals (CIs) for DESS and DESS+PDFS compared with the conventional protocol were calculated and tested using exact McNemar tests. The percentage of observations where DESS or DESS+PDFS had equivalent confidence ratings to DESS+Conv were tested with exact symmetry tests. Interreader agreement was calculated using Krippendorff's alpha. RESULTS: DESS had a PPA of 90% (88-92% CI) and NPA of 99% (99-99% CI). DESS+PDFS had increased PPA of 99% (95-99% CI) and NPA of 100% (99-100% CI) compared with DESS (both P < 0.001). DESS had equivalent diagnostic confidence to DESS+Conv in 94% of findings, whereas DESS+PDFS had equivalent diagnostic confidence in 99% of findings (both P < 0.001). All readers had moderate concordance for all three protocols (Krippendorff's alpha 47-48%). DATA CONCLUSION: Both 1) 5-minute 3D-DESS with separated echoes and 2) 5-minute 3D-DESS paired with a 2-minute coronal PDFS sequence depicted knee abnormalities similarly to a routine clinical knee MRI protocol, which may be a promising technique for abbreviated knee MRI. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018.

18.
Artigo em Inglês | MEDLINE | ID: mdl-30530322

RESUMO

Stress echocardiography is used to detect myocardial ischemia by evaluating cardiovascular function both at rest and at elevated heart rates. Stress echocardiography requires excellent visualization of the left ventricle (LV) throughout the cardiac cycle. However, LV endocardial border visualization is often negatively impacted by high levels of clutter associated with patient obesity, which has risen dramatically worldwide in recent decades. Short-lag spatial coherence (SLSC) imaging has demonstrated reduced clutter in several applications. In this work, a computationally efficient formulation of SLSC was implemented into an object-oriented graphics processing unit-based software beamformer, enabling real-time (>30 frames per second) SLSC echocardiography on a research ultrasound scanner. The system was then used to image 15 difficult-to-image stress echocardiography patients in a comparison study of tissue harmonic imaging (THI) and harmonic spatial coherence imaging (HSCI). Video clips of four standard stress echocardiography views acquired with either THI or HSCI were provided in random shuffled order to three experienced readers. Each reader rated the visibility of 17 LV segments as "invisible," "suboptimally visualized," or "well visualized," with the first two categories indicating a need for contrast agent. In a symmetry test unadjusted for patientwise clustering, HSCI demonstrated a clear superiority over THI ( ). When measured on a per-patient basis, the median total score significantly favored HSCI with . When collapsing the ratings to a two-level scale ("needs contrast" versus "well visualized"), HSCI once again showed an overall superiority over THI, with by McNemar test adjusted for clustering.


Assuntos
Ecocardiografia sob Estresse/métodos , Coração/diagnóstico por imagem , Processamento de Imagem Assistida por Computador/métodos , Algoritmos , Artefatos , Humanos
19.
J Vasc Interv Radiol ; 29(12): 1672-1677, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30316674

RESUMO

PURPOSE: To measure the decay activity loss and delivery system residual activity loss of yttrium-90 (Y90) radioembolization treatments across resin and glass microsphere activities. MATERIALS AND METHODS: For Y90 administrations between December 2009 and June 2017 at the study institution, the prescribed activity, prepared activity, and delivered activity were recorded. Six hundred sixty-two administrations were reviewed-345 glass (0.21-8.52 GBq) and 317 resin (0.18-3.28 GBq). Twenty-five patients (all resin) were excluded for arterial stasis or catheter clogging. The percentage and actual losses of activity lost to decay and to delivery system residual were calculated for glass and resin microspheres. RESULTS: The median time between activity premeasurement and administration was 2.20 hours, resulting in a median activity lost to decay of 0.030 GBq or 2.35%, with no significant difference observed between glass and resin despite differences in preparation (P = .0697). Resin showed significantly higher activity lost to delivery system residual than glass (0.039 GBq vs 0.010 GBq, 3.01% vs 0.61%, P < .001). The percent activity lost to residual varied with activity prepared, with a maximum of 20.1% and 16.2% for the smallest activities of resin and glass, respectively. CONCLUSIONS: Residual activity loss differs between glass and resin microspheres. For resin microspheres in particular, percent residual activity loss increases with lower prepared activities. Protocols for activity calculation and preparation, patient dosimetry, and regulatory compliance must take these losses into consideration prospectively.


Assuntos
Embolização Terapêutica/métodos , Vidro , Compostos Radiofarmacêuticos/administração & dosagem , Dosagem Radioterapêutica , Radioisótopos de Ítrio/administração & dosagem , Humanos , Microesferas , Estudos Retrospectivos
20.
Ultrasound Med Biol ; 44(12): 2569-2577, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30224172

RESUMO

The aim of this study was to assess whether the number of liver point shear wave elastography (pSWE) measurements could be reduced compared with the currently recommended 10 valid measurements. Three thousand four hundred one pSWE examinations in patients with liver disease were performed with 10 consecutive valid measurements in liver segment 8. Liver fibrosis grading using published cutoff values were compared retrospectively using the median of 10 versus the first 1-9 measurements with Kendall's τ coefficient. Overall and binary (clinically significant [≥F2] versus non-significant [F0/F1]) fibrosis grading highly correlated when using 5-9 versus 10 valid measurements (τ = 0.96/0.95, p < 0.001). With the use of 5 valid measurements, a change in binary grading was observed in 87 of 3401 (2.6%) exams and only when velocities measured between 1.1 and 1.5 m/s. Therefore, using 5-9 valid measurements in pSWE of the liver results in a small portion of liver fibrosis grading misclassifications compared with use of 10 measurements and could help decrease scanning time, cost and discomfort in sonographers and patients.


Assuntos
Técnicas de Imagem por Elasticidade/métodos , Cirrose Hepática/diagnóstico por imagem , Cirrose Hepática/patologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Fígado/diagnóstico por imagem , Fígado/patologia , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Estudos Retrospectivos , Índice de Gravidade de Doença , Adulto Jovem
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA