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Find video protocols related to scientific articles indexed in Pubmed.
High resolution 3D MRI of mouse mammary glands with intra-ductal injection of contrast media.
Magn Reson Imaging
PUBLISHED: 08-29-2014
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The purpose of this study was to use high resolution three-dimensional (3D) magnetic resonance imaging (MRI) to study mouse mammary gland ductal architecture based on intra-ductal injection of contrast agents. Female FVB/N mice age 12-20weeks (n=12), were used in this study. A 34G, 45° tip Hamilton needle with a 25?L Hamilton syringe was inserted into the tip of the nipple. Approximately 20-25?L of a Gadodiamide/Trypan blue/saline solution was injected slowly over one minute into the nipple and duct. To prevent washout of contrast media from ducts due to perfusion, and maximize the conspicuity of ducts on MRI, mice were sacrificed one minute after injection. High resolution 3D T1-weighted images were acquired on a 9.4T Bruker scanner after sacrifice to eliminate motion artifacts and reduce contrast media leakage from ducts. Trypan blue staining was well distributed throughout the ductal tree. MRI showed the mammary gland ductal structure clearly. In spoiled gradient echo T1-weighted images, the signal-to-noise ratio of regions identified as enhancing mammary ducts following contrast injection was significantly higher than that of muscle (p<0.02) and significantly higher than that of contralateral mammary ducts that were not injected with contrast media (p<0.0001). The methods described here could be adapted for injection of specialized contrast agents to measure metabolism or target receptors in normal ducts and ducts with in situ cancers.
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Blood-Brain Barrier Permeable Gold Nanoparticles: An Efficient Delivery Platform for Enhanced Malignant Glioma Therapy and Imaging.
Small
PUBLISHED: 08-08-2014
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The blood-brain barrier (BBB) remains a formidable obstacle in medicine, preventing efficient penetration of chemotherapeutic and diagnostic agents to malignant gliomas. Here, a transactivator of transcription (TAT) peptide-modified gold nanoparticle platform (TAT-Au NP) with a 5 nm core size is demonstrated to be capable of crossing the BBB efficiently and delivering cargoes such as the anticancer drug doxorubicin (Dox) and Gd(3+) contrast agents to brain tumor tissues. Treatment of mice bearing intracranial glioma xenografts with pH-sensitive Dox-conjugated TAT-Au NPs via a single intravenous administration leads to significant survival benefit when compared to the free Dox. Furthermore, it is demonstrated that TAT-Au NPs are capable of delivering Gd(3+) chelates for enhanced brain tumor imaging with a prolonged retention time of Gd(3+) when compared to the free Gd(3+) chelates. Collectively, these results show promising applications of the TAT-Au NPs for enhanced malignant brain tumor therapy and non-invasive imaging.
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Intranasal nerve growth factor attenuates tau phosphorylation in brain after traumatic brain injury in rats.
J. Neurol. Sci.
PUBLISHED: 06-24-2014
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Traumatic brain injury (TBI) is a considerable cause of mild cognitive impairment and dementia. Intranasal administration of nerve growth factor (NGF) has previously been found to improve cognitive function after TBI, but the mechanism remains unclear. This study aimed to investigate the effects of intranasal NGF on the tau hyperphosphorylation following TBI. A modified Feeney's weight-drop model was used to induce TBI. Rats were randomly divided into control group, TBI group, TBI+NGF group, TBI+PDTC group and TBI+IL-1ra group. Rats in TBI+NGF group were administered with NGF (5 ?g/d) for 3d before surgery. Hyperphosphorylated tau protein was remarkable in the peri-contusional cortex area with TBI. Both western blotting and immunostaining results displayed intranasal pretreatment of NGF significantly reduced tau phosphorylation. To evaluate the underlying mechanism, the levels of glycogen synthase kinase 3? (GSK-3?), interleukin-1? (IL-1?), and the DNA binding activity of nuclear factor-?B (NF-?B) were assayed. NGF markedly inhibited GSK-3?. NGF also reduced TBI-induced elevation of IL-1? and NF-?B DNA binding activity. Furthermore, PDTC and IL-1ra were injected to prove a potential signaling pathway among NF-?B, IL-1? and GSK-3?. Taken together, these findings demonstrated that intranasal NGF could effectively attenuate the hyperphosphorylation of tau after TBI, which might involve an integrated signaling pathway related to NF-?B.
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Argatroban for preventing occlusion and restenosis after extracranial artery stenting.
Eur. Neurol.
PUBLISHED: 04-08-2014
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Restenosis following extracranial artery stenting is a limitation that affects long-term outcomes. Effective and satisfying pharmacological strategies in preventing restenosis have not been established. This study aimed to evaluate whether argatroban, a direct thrombin inhibitor, could reduce the risk of in-stent restenosis after extracranial artery stenting.
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Quantitative evaluation of internal marks made using MRgFUS as seen on MRI, CT, US, and digital color images - A pilot study.
Phys Med
PUBLISHED: 02-19-2014
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This pilot study compared the detectability of internal thermal marks produced with MRI-guided focused ultrasound (MRgFUS) on MRI, computed tomography (CT), ultrasonography (US), and color images from digital scanning. Internal marks made using MRgFUS could potentially guide surgical, biopsy or radiotherapy procedures. New Zealand White rabbits (n = 6) thigh muscle were marked using a Philips MRgFUS system. Before and after sonications, rabbits were imaged using T1- and T2-weighted MRI. Then rabbits were sacrificed and imaging was performed using CT and US. After surgical excision specimens were scanned for color conspicuity analysis. Images were read by a radiologist and quantitative analysis of signal intensity was calculated for marks and normal muscle. Of a total of 19 excised marks, approximately 79%, 63%, and 62% were visible on MRI, CT, and US, respectively. The average maximum temperature elevation in the marks during MRgFUS was 39.7 ± 10.1 °C, and average dose diameter (i.e., the diameter of the area that achieved a thermal dose greater than 240 cumulative equivalent minutes at 43 °C) of the mark at the focal plane was 7.3 ± 2.1 mm. On MRI the average normalized signal intensities were significantly higher in marks compared to normal muscle (p < 0.05). On CT, the marked regions were approximately 10 HU lower than normal muscle (p < 0.05). The results demonstrate that MRgFUS can be used to create internal marks that are visible on MRI, CT and US.
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A preclinical evaluation of neural stem cell-based cell carrier for targeted antiglioma oncolytic virotherapy.
J. Natl. Cancer Inst.
PUBLISHED: 07-04-2013
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Oncolytic adenoviral virotherapy (OV) is a highly promising approach for the treatment of glioblastoma multiforme (GBM). In practice, however, the approach is limited by poor viral distribution and spread throughout the tumor mass.
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Endovascular stenting for atherosclerotic subclavian artery stenosis in patients with other craniocervical artery stenosis.
J. Thromb. Thrombolysis
PUBLISHED: 06-08-2013
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Atherosclerotic subclavian artery stenosis (SAS) accompanied with other craniocervical artery stenosis (OCAS) is not uncommon in practice. We sought to investigate the safety and efficacy of endovascular stenting for SAS in patients with OCAS. Between January 2004 and February 2012, 71 consecutive atherosclerotic SAS patients who underwent primary stenting in our medical center were included. The enrolled patients were divided into combined-SAS group (n = 51) and solitary-SAS group (n = 20) depending on the presence or absence of OCAS. Data of demographics, procedure, and the followed-up were retrieved and analyzed. The technical success rate was 95.8%; the clinical success rate was 90.1%. There was no catheter-related major stroke or death. The immediate outcomes had no statistical difference between groups. During a mean of 27 ± 20 months (range 2-88 months) followed-up, 7 (10.3%) restenosis and 12 (17.6%) clinical events were identified. The primary patency rate was 95.3, 84.9 and 84.9% at 12, 24 months, and final followed-up respectively, which had no statistical difference between groups (odds ratio (OR), 2.60; 95% confidence interval (CI), 0.54-12.53; P = 0.232). The overall clinical event-free survival rate was 93.5, 86.2 and 54.6%, respectively, where the result of combined-SAS group was inferior to that of the solitary-SAS group (OR, 3.34; 95% CI, 1.02-11.00; P = 0.047). Endovascular stenting was safe and feasible for atherosclerotic SAS in patients with OCAS, although the combined OCAS may have a significant influence on the long-term outcome. Further studies are warrant to investigate the effects of revascularization for multiple craniocervical artery stenoses on the cerebral hemodynamics and long-term outcomes.
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MRI of neonatal necrotizing enterocolitis in a rodent model.
NMR Biomed
PUBLISHED: 06-05-2013
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Neonatal necrotizing enterocolitis (NEC) is a poorly understood life-threatening illness afflicting premature infants. Research is hampered by the absence of a suitable method to monitor disease progression noninvasively. The primary goal of this research was to test in vivo MRI methods for the noninvasive early detection and staging of inflammation in the ileum of an infant rat model of NEC. Neonatal rats were delivered by cesarean section at embryonic stage of day 20 after the beginning of pregnancy and stressed with formula feeding, hypoxia and bacterial colonization to induce NEC. Naturally born and dam-fed neonatal rats were used as healthy controls. In vivo MRI studies were performed using a Bruker 9.4-T scanner to obtain high-resolution anatomical MR images using both gradient echo and spin echo sequences, pixel-by-pixel T2 maps using a multi-slice-multi-echo sequence, and maps of the apparent diffusion coefficient (ADC) of water using a spin echo sequence, to assess the degree of ileal damage. Pups were sacrificed at the end of the MRI experiment on day 2 or 4 for histology. T2 measured by MRI was increased significantly in the ileal regions of pups with NEC by histology (106.3 ± 6.1 ms) compared with experimentally stressed pups without NEC (85.2 ± 6.8 ms) and nonstressed, control rat pups (64.9 ± 2.3 ms). ADC values measured by diffusion-weighted MRI were also increased in the ileal regions of pups with NEC by histology [(1.98 ± 0.15) × 10(-3) mm(2) /s] compared with experimentally stressed pups without NEC [(1.43 ± 0.16) × 10(-3) mm(2) /s] and nonstressed control pups [(1.10 ± 0.06) × 10(-3) mm(2) /s]. Both T2 and ADC values between these groups were found to be significantly different (p < 0.03). The correlation of MRI results with histologic images of the excised ileal tissue samples strongly suggests that MRI can noninvasively identify NEC and assess intestinal injury prior to clinical symptoms in a physiologic rat pup model of NEC. © 2013 The Authors. NMR in Biomedicine published by John Wiley & Sons, Ltd.
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Relationship between Cerebral Atherosclerosis and Leukoaraiosis in Aged Patients: Results from DSA.
J Neuroimaging
PUBLISHED: 04-30-2013
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There are some controversial results on the relationship between cerebral atherosclerosis and leukoaraiosis in the published papers, where cerebral atherosclerosis was often evaluated by ultrasonography, CTA or MRA. We analyzed data in which patients underwent both MRI and DSA to explore the above relationship in the aged people.
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High-resolution MRI of excised human prostate specimens acquired with 9.4T in detection and identification of cancers: validation of a technique.
J Magn Reson Imaging
PUBLISHED: 09-20-2011
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To evaluate feasibility of high-resolution, high-field ex vivo prostate magnetic resonance imaging (MRI) as an aid to guide pathologists examination and develop in vivo MRI methods.
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The diverse pathology and kinetics of mass, nonmass, and focus enhancement on MR imaging of the breast.
J Magn Reson Imaging
PUBLISHED: 05-19-2011
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To compare the pathology and kinetic characteristics of breast lesions with focus-, mass-, and nonmass-like enhancement.
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Active Crohns disease in the small bowel: evaluation by diffusion weighted imaging and quantitative dynamic contrast enhanced MR imaging.
J Magn Reson Imaging
PUBLISHED: 05-13-2011
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To determine relative diagnostic value of MR diffusion and perfusion parameters in detection of active small bowel inflammation in patients with Crohns disease (CD).
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Diffusion-weighted MR imaging of abdominopelvic abscesses.
Emerg Radiol
PUBLISHED: 05-01-2011
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This study was conducted to determine the incremental value of diffusion-weighted MR imaging (DW-MRI) over T2-weighted imaging diagnosing abdominopelvic abscesses and compare apparent diffusion coefficient (ADC) values of abscesses and non-infected ascites. In this IRB-approved, HIPAA-compliant study, two radiologists retrospectively compared T2-weighted, T2-weighted?+?DW-MRI and T2-weighted?+?contrast enhanced MR images of 58 patients (29 with abscess, 29 with ascites) who underwent abdominal MRI for abscess detection. Confidence and sensitivity was compared using McNemars test. ADC of abscesses and ascites was compared by t test, and a receiver operating characteristic (ROC) curve was constructed. Detection of abscesses and confidence improved significantly when T2-weighted images were combined with DW-MRI (sensitivity: observer 1-100%, observer 2-96.6%) or contrast enhanced images (sensitivity: both observers-100%) compared to T2-weighted images alone (sensitivity: observer 1-65.5%, observer 2-72.4%). All abscesses showed restricted diffusion. Mean ADC of abscesses (observer 1-1.17?±?0.42?×?10(-)³?mm²/s, observer 2-1.43?±?0.48?×?10(-3) mm²/s) was lower than ascites (observer 1-3.57?±?0.68?×?10(-3) mm²/s, observer 2-3.42?±?0.67?×?10(-3) mm²/s) (p?
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Non-contrast enhanced MRI for evaluation of breast lesions: comparison of non-contrast enhanced high spectral and spatial resolution (HiSS) images versus contrast enhanced fat-suppressed images.
Acad Radiol
PUBLISHED: 04-04-2011
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The aims of this study were to evaluate high spectral and spatial resolution (HiSS) magnetic resonance imaging (MRI) for the diagnosis of breast cancer without the injection of contrast media by comparing the performance of precontrast HiSS images to that of conventional contrast-enhanced, fat-suppressed, T1-weighted images on the basis of image quality and in the task of classifying benign and malignant breast lesions.
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HiSStology: high spectral and spatial resolution magnetic resonance imaging detection of vasculature validated by histology and micro-computed tomography.
Mol Imaging
PUBLISHED: 03-01-2011
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High spectral and spatial resolution (HiSS) data, acquired with echo-planar spectroscopic imaging (EPSI), can be used to acquire water spectra from each small image voxel. These images are sensitive to changes in local susceptibility caused by superparamagnetic iron oxide particles (SPIO); therefore, we hypothesized that images derived from HiSS data are very sensitive to tumor neovasculature following injection of SPIO. Accurate image registration was used to validate HiSS detection of neovasculature with histology and micro-computed tomographic (microCT) angiography. Athymic nude mice and Copenhagen rats were inoculated with Dunning AT6.1 prostate tumor cells in the right hind limb. The tumor region was imaged pre- and post-intravenous injection of SPIO. Three-dimensional assemblies of the CD31-stained histologic slices of the mouse legs and the microCT images of the rat vascular casts were registered with EPSI. The average distance between HiSS-predicted regions of high vascular density on magnetic resonance imaging and CD31-stained regions on histology was 200 ?m. Similarly, vessels identified by HiSS in the rat images coincided with vasculature in the registered microCT image. The data demonstrate a strong correlation between tumor vasculature identified using HiSS and two gold standards: histology and microCT angiography.
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In vivo MRI of early stage mammary cancers and the normal mouse mammary gland.
NMR Biomed
PUBLISHED: 01-25-2011
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Since the advent of screening mammography, approximately one-quarter of newly diagnosed breast cancers are at the earliest preinvasive stage of ductal carcinoma in situ (DCIS). Concomitant with this improvement in early detection has been a growing clinical concern that distinguishing aggressive from indolent DCIS is necessary to optimize patient management. Genetically engineered mouse models offer an appealing experimental framework in which to investigate factors that influence and predict progression of preinvasive neoplasias. Because of the small size of early stage carcinomas in mice, high-resolution imaging techniques are required to effectively observe longitudinal progression. The purpose of the present study was to evaluate the feasibility of MRI for assessment of in situ mammary neoplasias and early invasive mammary cancers that stochastically arise in mammary glands of C3(1) SV40 Tag transgenic mice. Additionally, images of normal mammary glands from wild-type FVB/N mice were acquired and compared with those from transgenic mice. Sixteen mice underwent MR examinations employing axial two-dimensional multi-slice gradient recalled echo scans (TR/TE =?1000/5.5 ms) with fat suppression in a two-step process targeting both the upper and lower mammary glands. MRI successfully detected in situ and early invasive neoplasias in transgenic mice with high sensitivity and specificity. The average signal-to-noise ratio (SNR) of in situ lesions on fat-suppressed high-resolution T(1) -weighted images was 22.9, which was lower than that of invasive tumors, lymph nodes and muscle (average SNR of 29.5-34.9, p < 0.0001) but significantly higher than that of normal mammary tissue (average SNR = 5.5, p < 0.0001). Evaluation of wild-type mammary glands revealed no cancerous or benign lesions, and comparable image contrast characteristics (average SNR = 5.2) as compared with normal tissue areas of transgenic mice. This present study demonstrates that MRI is an excellent candidate for performing longitudinal assessment of early stage mammary cancer disease progression and response to therapy in the transgenic model system.
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Use of a reference tissue and blood vessel to measure the arterial input function in DCEMRI.
Magn Reson Med
PUBLISHED: 07-29-2010
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Accurate measurement of the arterial input function is critical for quantitative evaluation of dynamic contrast enhanced magnetic resonance imaging data. Use of the reference tissue method to derive a local arterial input function avoided large errors associated with direct arterial measurements, but relied on literature values for K(trans) and v(e). We demonstrate that accurate values of K(trans) and v(e) in a reference tissue can be measured by comparing contrast media concentration in a reference tissue to plasma concentrations measured directly in a local artery after the 1-2 passes of the contrast media bolus-when plasma concentration is low and can be measured accurately. The values of K(trans) and v(e) calculated for the reference tissue can then be used to derive a more complete arterial input function including the first pass of the contrast bolus. This new approach was demonstrated using dynamic contrast enhanced magnetic resonance imaging data from rodent hind limb. Values obtained for K(trans) and v(e) in muscle, and the shape and amplitude of the derived arterial input function are consistent with published results.
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Influence of vessel size and tortuosity on in-stent restenosis after stent implantation in the vertebral artery ostium.
Cardiovasc Intervent Radiol
PUBLISHED: 05-15-2010
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Percutaneous transluminal angioplasty and stenting is emerging as an alternative for treating atherosclerotic stenosis in the vertebral artery ostium. However, in-stent restenosis (ISR) still remains a critical issue to be addressed. Little is known about the relationship between anatomic characteristics of the artery and ISR after stent implantation. In this study, we have evaluated influential factors for ISR in a cohort of the patients with stenting in the vertebral artery ostium.
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High-resolution magnetic resonance colonography and dynamic contrast-enhanced magnetic resonance imaging in a murine model of colitis.
Magn Reson Med
PUBLISHED: 04-08-2010
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Inflammatory bowel disease, including ulcerative colitis, is characterized by persistent or recurrent inflammation and can progress to colon cancer. Colitis is difficult to detect and monitor noninvasively. The goal of this work was to develop a preclinical imaging method for evaluating colitis. Herein, we report improved MRI methods for detecting and characterizing colitis noninvasively in mice, using high-resolution in vivo MR images and dynamic contrast-enhanced MRI studies, which were confirmed by histologic studies in a murine model of colitis. C57Bl6/J male mice were treated with 2.5% dextran sulfate sodium in their drinking water for 5 days to induce colitis. MR images were acquired using a 9.4-T Bruker scanner from 5-25 days following dextran sulfate sodium treatment. In dynamic contrast-enhanced MRI studies, Gd uptake (K(trans)) and its distribution (v(e)) were measured in muscle and normal and inflamed colons after administering Gd-diethyltriaminepentaacetic acid (Gd-DTPA). T(2)-weighted MR images distinguished normal colon from diffusely thickened colonic wall occurring in colitis (P <0.0005) and correlated with histologic features. Values of K(trans) and v(e) obtained from dynamic contrast-enhanced MRI were also significantly different in inflamed colons compared to normal colon (P < 0.0005). The results demonstrate that both T(2)-weighted anatomic imaging and quantitative analysis of dynamic contrast-enhanced MRI data can successfully distinguish colitis from normal colon in mice.
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Multi-parametric MR imaging of transition zone prostate cancer: Imaging features, detection and staging.
World J Radiol
PUBLISHED: 03-30-2010
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Magnetic resonance (MR) imaging has been increasingly used in the evaluation of prostate cancer. As studies have suggested that the majority of cancers arise from the peripheral zone (PZ), MR imaging has focused on the PZ of the prostate gland thus far. However, a considerable number of cancers (up to 30%) originate in the transition zone (TZ), substantially contributing to morbidity and mortality. Therefore, research is needed on the TZ of the prostate gland. Recently, MR imaging and advanced MR techniques have been gaining acceptance in evaluation of the TZ. In this article, the MR imaging features of TZ prostate cancers, the role of MR imaging in TZ cancer detection and staging, and recent advanced MR techniques will be discussed in light of the literature.
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The influence of temporal resolution in determining pharmacokinetic parameters from DCE-MRI data.
Magn Reson Med
PUBLISHED: 02-27-2010
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We investigated the influence of the temporal resolution of dynamic contrast-enhanced MRI data on pharmacokinetic parameter estimation. Dynamic Gd-DTPA (Gadolinium-diethylene triamine pentaacetic acid) enhanced MRI data of implanted prostate tumors on rat hind limb were acquired at 4.7 T, with a temporal resolution of approximately 5 sec. The data were subsequently downsampled to temporal resolutions in the range of 15 sec to 85 sec, using a strategy that involves a recombination of k-space data. A basic two-compartment model was fit to the contrast agent uptake curves. The results demonstrated that as temporal resolution decreases, the volume transfer constant (K(trans)) is progressively underestimated (approximately 4% to approximately 25%), and the fractional extravascular extracellular space (v(e)) is progressively overestimated (approximately 1% to approximately 10%). The proposed downsampling strategy simulates the influence of temporal resolution more realistically than simply downsampling by removing samples.
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Dynamic contrast-enhanced magnetic resonance imaging in prostate cancer.
Top Magn Reson Imaging
PUBLISHED: 12-17-2009
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Prostate cancer remains a major health concern for the male population. During the past decade, a dramatic increase in prostate-specific antigen and transurethral resection of the prostate has resulted in increased detection rate of small lesions and increased incidence of this disease. Needle biopsies in asymptomatic men have also contributed to the increased incidence of prostate cancer, leading to an increasing incidence-to-mortality ratio. Magnetic resonance imaging (MRI) is the modality of choice in prostate cancer patients with increased prostate-specific antigen levels before or after prostate cancer diagnosis confirmed by biopsy and T2-weighted imaging (T2W) has been used as a standard technique in detection. During the last decade, dynamic contrast-enhanced MRI has emerged as one of the main techniques used in multiparametric MRI of the prostate gland in cancer patients. Dynamic contrast-enhanced MRI has been routinely used for detection and diagnosis of the tumor, for staging and monitoring the therapeutic response, as well as for guiding targeted biopsies in patients with suspected prostate cancer or with a negative biopsy result. In this article, we are going to review the analysis techniques of dynamic contrast-enhanced MRI and its various clinical applications in prostate cancer patients.
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Ductal carcinoma in situ: X-ray fluorescence microscopy and dynamic contrast-enhanced MR imaging reveals gadolinium uptake within neoplastic mammary ducts in a murine model.
Radiology
PUBLISHED: 10-30-2009
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To combine dynamic contrast material-enhanced (DCE) magnetic resonance (MR) imaging with x-ray fluorescence microscopy (XFM) of mammary gland tissue samples from mice to identify the spatial distribution of gadolinium after intravenous injection.
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Fourier component imaging of water resonance in the human breast provides markers for malignancy.
Phys Med Biol
PUBLISHED: 09-09-2009
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The purpose of this paper is to demonstrate that voxels with inhomogeneously broadened water resonances, as revealed by high spectral and spatial resolution (HiSS) MRI, correlate with underlying tumor pathology findings, and thus carry diagnostically useful information. Thirty-four women with mammographically suspicious breast lesions were imaged at 1.5 T, using high-resolution echo-planar spectroscopic imaging. Fourier component images (FCIs) of the off-peak spectral signal were generated, and clusters of voxels with significant inhomogeneous broadening (broadened clusters) were identified and correlated to biopsy results. Inhomogeneously broadened clusters were found significantly more frequently in malignant than in benign lesions. A larger percentage of broadened cluster voxels were found inside the malignant versus benign lesions. The high statistical significance for separation of benign and malignant lesions was robust over a large range of post-processing parameters, with a maximum ROC area under curve of 0.83. In the human breast, an inhomogeneously broadened water resonance can serve as a correlate marker for malignancy and is likely to reflect the underlying anatomy or physiology.
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Kinetic curves of malignant lesions are not consistent across MRI systems: need for improved standardization of breast dynamic contrast-enhanced MRI acquisition.
AJR Am J Roentgenol
PUBLISHED: 08-22-2009
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The purpose of this study was to compare MRI kinetic curve data acquired with three systems in the evaluation of malignant lesions of the breast.
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Characterization of response to radiation mediated gene therapy by means of multimodality imaging.
Magn Reson Med
PUBLISHED: 05-19-2009
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Imaging techniques are under development to facilitate early analysis of spatial patterns of tumor response to combined radiation and antivascular gene therapy. A genetically modified, replication defective adenoviral vector (Ad.EGR-TNFalpha), injected intratumorally, mediates infected cells to express tumor necrosis factor alpha (TNFalpha), which is increased after exposure to radiation. The goal of this study was to characterize an image based "signature" for response to this combined radiation and gene therapy in mice with human prostate xenografts. This study is part of an imaged guided therapy project where such a signature would be useful in guiding subsequent treatments. Changes in the tumor micro-environment were assessed using MRI registered with electron paramagnetic resonance imaging which provides images of tissue oxygenation. Dynamic contrast-enhanced MRI was used to assess tissue perfusion. When compared with null vector (control) treatment, the ratio of contrast agent (Gd-DTPA-BMA) washout rate to uptake rate was lower (P = 0.001) after treatment, suggesting a more balanced perfusion. Concomitantly, oxygenation significantly increased in the treated animals and decreased or did not change in the control animals (P < 0.025). This is the first report of minimally invasive, quantitative, absolute oxygen measurements correlated with tissue perfusion in vivo.
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A new approach to analysis of the impulse response function (IRF) in dynamic contrast-enhanced MRI (DCEMRI): a simulation study.
Magn Reson Med
PUBLISHED: 05-19-2009
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The purpose of this research was to develop a novel numerical procedure to deconvolute the arterial input function (AIF) from contrast concentration vs. time curves and to obtain the impulse response functions (IRFs) from dynamic contrast-enhanced MRI (DCEMRI) data. Numerical simulations were performed to study variations of contrast concentration vs. time curves and the corresponding IRFs. The simulated contrast media concentration curves were generated by varying the parameters of an empirical mathematical model (EMM) within reasonable ranges based on a previous experimental study. The AIF was calculated from plots of contrast media concentration vs. time in muscle under assumption that they are well approximated by the "two-compartment model" (TCM). A general simple mathematical model of the IRF was developed, and the physiological meaning of the model parameters was determined by comparing them with the widely accepted TCM. The results demonstrate that the deconvolution procedure developed in this research is a simple, robust, and useful technique. In addition, "impulse response analysis" leads to the derivation of novel parameters relating to tumor vascular architecture, and these new parameters may have clinical utility.
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Plasma C-reactive protein is related to cognitive deterioration and dementia in patients with mild cognitive impairment.
J. Neurol. Sci.
PUBLISHED: 04-12-2009
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To investigate the relationship between plasma C-reactive protein (CRP) and the risk for cognitive deterioration and development of dementia in patients with mild cognitive impairment (MCI).
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Quantitative analysis of dynamic contrast enhanced MRI for assessment of bowel inflammation in Crohns disease pilot study.
Acad Radiol
PUBLISHED: 03-17-2009
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The aim of this study was to evaluate the feasibility of quantitative analysis of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) data in the detection of bowel inflammation in patients with Crohns disease.
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Magnetic resonance imaging of the natural history of in situ mammary neoplasia in transgenic mice: a pilot study.
Breast Cancer Res.
PUBLISHED: 03-01-2009
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Because of the small size of in situ mammary cancers in mouse models, high-resolution imaging techniques are required to effectively observe how lesions develop, grow and progress over time. The purpose of this study was to use magnetic resonance (MR) imaging to track in vivo the transition from in situ neoplasia to invasive cancer in a transgenic mouse model of human cancer.
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Sensitivity to tumor microvasculature without contrast agents in high spectral and spatial resolution MR images.
Magn Reson Med
PUBLISHED: 01-24-2009
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Contrast-enhanced (CE)-MRI is sensitive to cancers but can produce adverse reactions and suffers from insufficient specificity and morphological detail. This research investigated whether high spectral and spatial resolution (HiSS) MRI detects tumor vasculature without contrast agents, based on the sensitivity of the water resonance line shape to tumor blood vessels. HiSS data from AT6.1 tumors inoculated in the hind legs of rats (N = 8) were collected pre- and post-blood pool contrast agent (iron-oxide particles) injection. The waterline in small voxels was significantly more asymmetric at the tumor rim compared to the tumor center and normal muscle (P < 0.003). Composite images were synthesized, with the intensity in each voxel determined by the Fourier component (FC) of the water resonance having the greatest relative image contrast at that position. We tested whether regions with high contrast in FC images (FCIs) contain vasculature by comparing FCIs with CE-MRI as the "gold standard" of vascular density. The FCIs had 75% +/- 13% sensitivity, 74% +/- 10% specificity, and 91% +/- 4% positive predictive value (PPV) for vasculature detection at the tumor rim. These results suggest that tumor microvasculature can be detected using HiSS imaging without the use of contrast agents.
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Alcohol consumption and transition of mild cognitive impairment to dementia.
Psychiatry Clin. Neurosci.
PUBLISHED: 01-22-2009
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Mild cognitive impairment (MCI) is a prodrome for dementia. Alcohol drinking patterns may affect cognitive functions and the effects may accumulate to a significant level at an advanced age. This study investigated the relationship between alcohol consumption and risks for dementia in a cohort of elderly patients with MCI.
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Can DCEMRI assess the effect of green tea on the angiogenic properties of rodent prostate tumors?
Phys Med
PUBLISHED: 01-08-2009
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The purpose of this research was to test whether dynamic contrast enhanced MRI could assess the effect of green tea on the angiogenic properties of transplanted rodent tumors. Copenhagen rats bearing AT6.1 prostate tumors inoculated in the hind limbs were randomly assigned to cages in which they were allowed to only drink either plain water (control group) or water containing green tea extract (treated group). Assignments were made after a baseline MRI experiment (week 0) was performed on each rat at 4.7T. All the rats were subsequently imaged at day 7 (week 1) and day 14 (week 2) to follow tumor growth and vascular development. The two-compartment pharmacokinetic model was used to analyze the dynamic contrast Gd-DTPA enhanced MRI data on a pixel-by-pixel basis over the tumor area to obtain the volume transfer constant (K(trans)) and extravascular extracellular space (v(e)). An identity Chi-squared test showed that the distributions of averaged histograms (n=6) of K(trans) and v(e) were significantly different from week 0 to both weeks 1 and 2 (p<0.001) in both the control and the treated rats due to increasing areas of tumor necrosis. However, the tumor growth rate was statistically indistinguishable between control and treated rats. There was no significant difference in the distributions of K(trans) and v(e) between control and treated rats. The results showed that no effects of green tea on tumor micro-vasculature were measurable by dynamic Gd-DTPA enhanced MRI.
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Comparing post-operative human breast specimen radiograph and MRI in lesion margin and volume assessment.
J Appl Clin Med Phys
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The purpose of this research is to evaluate the potential for identifying malignant breast lesions and their margins on large specimen MRI, in comparison to specimen radiography and clinical dynamic contrast enhanced MRI (DCE-MRI). Breast specimens were imaged with an MR scanner immediately after surgery, with an IRB-approved protocol and with the patients informed consent. Specimen sizes were at least 5 cm in diameter and approximately 1 to 4 cm thick. Coronal and axial gradient echo MR images without fat suppression were acquired over the whole specimens using a 9.4T animal scanner. Findings on specimen MRI were compared with findings on specimen radiograph, and their volumes were compared with measurements obtained from clinical DCE-MRI. The results showed that invasive ductal carcinoma (IDC) lesions were easily identified using MRI and the margins were clearly distinguishable from nearby tissue. However, ductal carcinoma in situ (DCIS) lesions were not clearly discernible and were diffused with poorly defined margins on MRI. Calcifications associated with DCIS were visualized in all specimens on specimen radiograph. There is a strong correlation between the maximum diameter of lesions as measured by radiograph and MRI (r = 0.93), as well as the maximum diameter measured by pathology and radiograph/MRI (r>0.75). The volumes of IDC measured on specimen MRI were slightly smaller than those measured on DCE-MRI. Imaging of excised human breast lumpectomy specimens with high magnetic field MRI provides promising results for improvements in lesion identification and margin localization for IDC. However, there are technical challenges in visualization of DCIS lesions. Improvements in specimen imaging are important, as they will provide additional information to standard radiographic analysis.
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Empirical mathematical model for dynamic manganese-enhanced MRI of the murine pancreas for assessment of ?-cell function.
Magn Reson Imaging
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Autoimmune ablation of pancreatic ?-cells and alteration of its microvasculature may be a predictor of Type I diabetes development. A dynamic manganese-enhanced MRI (MEMRI) approach and an empirical mathematical model were developed to monitor whole pancreatic ?-cell function and vasculature modifications in mice. Normal and streptozotocin-induced diabetic FVB/N mice were imaged on a 9.4T MRI system using a 3D magnetization prepared rapid acquisition gradient echo pulse sequence to characterize low dose manganese kinetics in the pancreas head, body and tail. Average signal enhancement in the pancreas (head, body, and tail) as a function of time was fit by a novel empirical mathematical model characterizing contrast uptake/washout rates and yielding parameters describing peak signal, initial slope, and initial area under the curve. Signal enhancement from glucose-induced manganese uptake was fit by a linear function. The results demonstrated that the diabetic pancreatic tail had a significantly lower contrast uptake rate, smaller initial slope/initial area under the curve, and a smaller rate of Mn uptake following glucose activation (p<0.05) compared to the normal pancreatic tail. These observations parallel known patterns of ?-cell loss and alteration in supportive vasculature associated with diabetes. Dynamic MEMRI is a promising technique for assessing ?-cell functionality and vascular perfusion with potential applications for monitoring diabetes progression and/or therapy.
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Hyperthermically induced changes in high spectral and spatial resolution MR images of tumor tissue--a pilot study.
Phys Med Biol
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This pilot study investigated the feasibility of using MRI based on BOLD (blood-oxygen-level-dependent) contrast to detect physiological effects of locally induced hyperthermia in a rodent tumor model. Nude mice bearing AT6.1 rodent prostate tumors inoculated in the hind leg were imaged using a 9.4 T scanner using a multi-gradient echo pulse sequence to acquire high spectral and spatial resolution (HiSS) data. Temperature increases of approximately 6 °C were produced in tumor tissue using fiber-optic-guided light from a 250 W halogen lamp. HiSS data were acquired over three slices through the tumor and leg both prior to and during heating. Water spectra were produced from these datasets for each voxel at each time point. Time-dependent changes in water resonance peak width were measured during 15 min of localized tumor heating. The results demonstrated that hyperthermia produced both significant increases and decreases in water resonance peak width. Average decreases in peak width were significantly larger in the tumor rim than in normal muscle (p = 0.04). The effect of hyperthermia in tumor was spatially heterogeneous, i.e. the standard deviation of the change in peak width was significantly larger in the tumor rim than in normal muscle (p = 0.005). Therefore, mild hyperthermia produces spatially heterogeneous changes in water peak width in both tumor and muscle. This may reflect heterogeneous effects of hyperthermia on local oxygenation. The peak width changes in tumor and muscle were significantly different, perhaps due to abnormal tumor vasculature and metabolism. Response to hyperthermia measured by MRI may be useful for identifying and/or characterizing suspicious lesions as well as guiding the development of new hyperthermia protocols.
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Safety limitations of MR-HIFU treatment near interfaces: a phantom validation.
J Appl Clin Med Phys
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Magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) is a noninvasive image-guided technique used to thermally ablate solid tumors. During treatment, ultrasound reflections from distal media interfaces can shift prescribed treatment locations. The purpose of this study was to investigate the effect of normal incidence reflections from air, acrylic (modeling bone), and rubber on treatment location, temperature elevation, and heating patterns by performing ultrasound exposures in a tissue-mimicking phantom and in ex vivo porcine tissue using a clinical MR-HIFU platform. The results demonstrated a shift in treatment location toward the distal interface when targeted closer than 2 cm from the interface, especially for acrylic. Our study demonstrated that the ultrasound wave reflections from a distal air interface had less effect than the acrylic interface (modeling bone) on the heating pattern and focal location. This study provides useful information to better understand the limitations and safety concerns of performing MR-HIFU treatments with commercial clinical equipment.
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T(2)? relaxation times of intraductal murine mammary cancer, invasive mammary cancer, and normal mammary gland.
Med Phys
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This study investigates the feasibility of T(2)? to be a diagnostic indicator of early breast cancer in a mouse model. T(2)? is sensitive to susceptibility effects due to local inhomogeneity of the magnetic field, e.g., caused by hemosiderin or deoxyhemoglobin. In these mouse models, unlike in patients, the characteristics of single mammary ducts containing pure intraductal cancer can be evaluated.
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What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

How does it work?

We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

Video X seems to be unrelated to Abstract Y...

In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.