Search PubMed⌕ Search

Biomedical subjects

R R Edelman

Publications and source records attributed to R R Edelman.

At least 37 records · Page 2Linked to original sources
PubMed2000

1H magnetic resonance imaging of human lung using inversion recovery turbo spin echo.

Evaluation of lung pathologies using magnetic resonance imaging remains limited, primarily due to the lung's low proton density and high density of magnetic field susceptibility gradients. It is hypothesized that visualization of the lung is possible if signal intensity from muscle and/or fat is suppressed or reduced. Using the inversion recovery and frequency selective saturation pulse with a half-Fourier single-shot turbo spin-echo (HASTE) or a segmented, centric reordered turbo spin-echo (TSE) readout, signal intensity and contrast of tissues can be manipulated to enhance the visibility of the lung. Multislice images of the lung from 10 healthy volunteers were acquired with negligible motion artifacts. Peripheral pulmonary vessels appear well delineated. T(1) maps of the lung are also presented; the overall average was 1335 +/- 85 msec and 1245 +/- 93 msec with the volunteers performing breath-holding on end-expiration and end-inspiration, respectively. This difference is statistically significant, at P < 0.01.

Adult↗
PubMed2000

Semiquantitative assessment of uterine perfusion using first pass dynamic contrast-enhanced MR imaging for patients treated with uterine fibroid embolization.

The feasibility of using first pass dynamic contrast-enhanced MRI to monitor semiquantitatively the perfusion changes of the uterus after uterine arterial embolization is demonstrated. Ten women, who underwent uterine arterial embolization for fibroid treatment, were included in this study. To derive a perfusion index, an additional axial slice through the abdominal aorta was obtained simultaneously when acquiring MR perfusion data. This technique may prove valuable in monitoring the outcome of uterine arterial embolization and documentation of preserved uterine perfusion after this procedure. J. Magn. Reson. Imaging 2000;12:1004-1008.

Adult↗
PubMed2000

MR angiography of the vascular tree from the aorta to the foot: combining two-dimensional time-of-flight and three-dimensional contrast-enhanced imaging.

A composite approach for magnetic resonance (MR) angiography of the lower extremities is described. Thirty patients were studied with this approach, which combined a two-dimensional (2D) time-of-flight (TOF) technique with a 3D contrast-enhanced technique. A head/neck coil was selected for imaging mid-foot to upper calf, and the body coil was used for the remainder of the peripheral vascular tree. Acquired data were transferred to a workstation for postprocessing. The final maximum intensity projection images, which display the entire vascular anatomy from aortic bifurcation to foot, were created using a 1024 x 1024 matrix. Very small arteries can be differentiated in critical regions like the calf and foot. Compared with TOF-2D alone, the scan time was reduced. This method offers another option for MR angiography of the lower extremities. J. Magn. Reson. Imaging 2000;12:884-889.

Adult↗
PubMed2000

Imaging pulmonary blood flow and perfusion using phase-sensitive selective inversion recovery.

A technique is described for imaging pulmonary blood flow using a phase-sensitive selective inversion recovery (PS-SIR) sequence. PS-SIR image reconstruction provides excellent contrast, differentiating fully relaxed inflowing blood from inverted blood and lung tissue. The magnetization of the inverted tissues remains negative at any inversion delay less than that at which the magnetization of the lung tissue is nulled, whereas that of the fully relaxed inflowing blood is always positive. Pulmonary blood flow can be observed by tracking the propagation of the pixels with positive values. Five healthy volunteers were imaged. The normal pattern of blood flow advancing from the central arteries toward the peripheries and into the lung parenchyma with return toward the center via draining veins was depicted. The method offers promise for evaluating pulmonary blood flow without the need for image subtraction or contrast administration. Magn Reson Med 43:793-795, 2000.

Adult↗
PubMed2000

Multiple inversion recovery MR subtraction imaging of human ventilation from inhalation of room air and pure oxygen.

The feasibility of MR subtraction imaging of lung ventilation using air against oxygen using a multiple inversion recovery half-Fourier single-shot turbo spin echo (MIR-HASTE) sequence was investigated. Eight healthy, nonsmoking volunteers (3 males, 5 females; from 27 to 48 years of age) were studied on a 1.5 T MR unit. The ventilation image was obtained from the subtraction of the images acquired with the subject inhaling room air and 100% oxygen. By suppressing the signal from subcutaneous fat and thoracic muscle, MIR-HASTE improved the subtraction of signal arising from background tissues. Lung parenchyma, pulmonary veins, descending aorta, spleen, and kidney showed high signal difference, but pulmonary arteries exhibited minimal signal difference. Because of minimal signal change in the pulmonary arteries after inhalation of 100% oxygen, the average signal decreases in the left and right lungs including hilus and periphery amounted to only 19.4+/-4.5 and 20.2+/-3.4%, respectively, compared with regional averages of 23.6+/-5.4 and 24.1+/-3.1% for both lung peripheries alone. Magn Reson Med 43:913-916, 2000.

Administration, Inhalation↗
PubMed2000

Noninvasive pulmonary perfusion imaging by STAR-HASTE sequence.

The STAR-HASTE sequence has been shown to be useful for perfusion imaging in areas that are plagued by magnetic susceptibility artifacts. Pulmonary perfusion imaging with this technique was attempted in this study. Quantitative analysis was also conducted, using an appropriate kinetic model in one subject. In six healthy subjects, gradual enhancement was observed in pulmonary artery to distal lung parenchyma when inflow time was increased. Our initial results suggest that noninvasive evaluation of pulmonary perfusion by magnetic resonance imaging without administration of an exogenous agent is possible.

Adult↗
PubMed2000

A multicoil array designed for cardiac SMASH imaging.

Recently, several partially parallel acquisition (PPA) techniques have been presented which use spatial information inherent in an RF coil array to reconstruct an image from a reduced set of phase encoding steps. PPAs represent a change in paradigm for the RF coil designer since the focus for arrays to be used with PPAs is to optimize the spatial encoding that is provided by the array. One of the first practical implementations of PPA imaging was demonstrated using the SMASH technique. In this study, we present our results from the construction of the first array designed specifically for cardiac SMASH imaging. Additional design criteria are presented for SMASH arrays that are not considered in conventional array design. Using these design criteria, a four-element array was constructed and then tested in SMASH imaging experiments in the heart. This array has been used in all of our initial cardiac and head SMASH studies with good results.

Biophysical Phenomena↗
PubMed2000

Magnetic resonance imaging of the thorax. Past, present, and future.

Magnetic resonance imaging is a valuable modality of extreme flexibility for specific problem-solving capability in the thorax. This article reviews MR applications in the imaging of great vessels, which are currently the most important applications in the thorax; other established applications in the thorax; and pulmonary functional MR imaging.

Humans↗
PubMed2000

Multicentre dose-ranging study on the efficacy of USPIO ferumoxtran-10 for liver MR imaging.

AIM: A dose ranging multicentre phase-II clinical trial was conducted to evaluate the efficacy of ultrasmall superparamagnetic iron oxide (USPIO) ferumoxtran-10 for magnetic resonance (MR) imaging of focal hepatic lesions. MATERIAL AND METHODS: Ninety-nine patients with focal liver lesions received USPIO at a dose of 0.8 (n = 35), 1.1 (n = 32), or 1.7 (n = 32) mg Fe/kg. Liver MR imaging was performed before and after USPIO with T1-weighted and T2-weighted pulse sequences. Images were analysed by two independent readers for additional information (lesion detection, exclusion, characterization and patient management). Signal intensity (SI) based quantitative measurements were also taken. RESULTS: Post-contrast medium MR imaging showed additional information in 71/97 patients (73%) for reader one and 83/96 patients (86%) for reader two. The results with all three doses were statistically significant (P < 0.05). Signal intensity analysis revealed that all three doses increased liver SI on T1-weighted images and decreased liver SI on T2-weighted images. On T2-weighted images metastases increased in contrast relative to normal hepatic parenchyma whereas haemangiomas decreased in contrast. On T2-weighted images there was statistically improved efficacy at the intermediate dose, which did not improve at the highest dose. CONCLUSION: Ultrasmall superparamagnetic iron oxide was an effective contrast agent for liver MR imaging at all doses and a dose of 1.1 mg Fe/kg was recommended for future clinical trials.

Adult↗
PubMed2000

Contrast-enhanced 3D MR angiography with simultaneous acquisition of spatial harmonics: A pilot study.

A partially parallel image acquisition technique, simultaneous acquisition of spatial harmonics, or SMASH, was used to increase the spatial and/or temporal resolution in contrast material-enhanced three-dimensional magnetic resonance angiography of the abdominal aorta and renal arteries. In eight healthy subjects, the breath-hold duration was halved at constant spatial resolution, or the spatial resolution was doubled at fixed breath-hold duration, with a 30%-55% reduction in the signal-to-noise ratio but otherwise preserved or improved image quality.

Adult↗
PubMed2000

Captopril MR renography in a swine model: toward a comprehensive evaluation of renal arterial stenosis.

PURPOSE: To test the feasibility of captopril magnetic resonance (MR) renography and to validate the technique in an animal model of renal arterial stenosis. MATERIALS AND METHODS: Seven pigs with induced renal arterial stenosis were studied. MR renography was performed with a T1-weighted approach by using three-dimensional fast imaging with steady-state precession, or FISP, sequences after administration of a bolus of 0.1 mmol of gadopentetate dimeglumine per kilogram of body weight. Captopril was administered to improve the specificity. RESULTS: The results demonstrate that differences in renographic curves and indices are observed only if an anatomically substantial stenosis, typically a diameter reduction of more than 70%, is present and captopril is administered. CONCLUSION: In this preliminary experience in an animal model, captopril MR renography provided data consistent with expectations based on conventional renographic results.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1999

Silent functional magnetic resonance imaging demonstrates focal activation in rapid eye movement sleep.

Functional imaging of human sleep has been performed with nuclear medicine methods, but MRI has been difficult to implement, in part because of the noise associated with echo-planar imaging as well as the difficulty in reading physiologic signals in the MRI environment. We describe a silent MR sequence that can record brain activation over many hours with simultaneous acquisition of an EEG. This shows activation of occipital cortex and deactivation of frontal cortex during REM sleep, in agreement with previous studies using other techniques. MRI-Sleep-REM sleep.

Adult↗
PubMed1999

The ischemic penumbra: operationally defined by diffusion and perfusion MRI.

BACKGROUND: Identifying tissue at risk for infarction is important in deciding which patients would benefit most from potentially harmful therapies and provides a way to evaluate newer therapies with regard to the amount of ischemic tissue salvaged. OBJECTIVE: To operationally define and characterize cerebral tissue at risk for stroke progression. METHODS: We retrospectively selected 25 patients with an acute onset of a hemispheric stroke from our database who had undergone a combination of two diffusion-weighted MRI studies and a perfusion-weighted MRI study. We applied a logistic regression model using maps of the relative mean transit time and relative cerebral blood flow (rCBF) as well as three different maps of the relative cerebral blood volume (rCBV) to predict an operationally defined penumbra (region of mismatch between the diffusion lesion on day 1 and its extension 24 to 72 hours later). RESULTS: Maps of the rCBF and initial rCBV were significant predictors for identifying penumbral tissue. Our operationally defined penumbral region was characterized by a reduction in the initial rCBV (47% of contralateral control region [CCR]), an increase (163% of CCR) in the total rCBV, and a reduction (37% of CCR) in the rCBF, whereas the operationally defined ischemic core showed a more severe reduction in the rCBF (12% of CCR) and in the initial rCBV (19% of CCR). CONCLUSION: These MR indexes may allow the identification and quantification of viable but ischemically threatened cerebral tissue amenable to therapeutic interventions in the hyperacute care of stroke patients.

Aged↗
PubMed1999

Safety profile of ultrasmall superparamagnetic iron oxide ferumoxtran-10: phase II clinical trial data.

The safety data from the phase II clinical trial of ferumoxtran-10, an ultrasmall superparamagnetic iron oxide contrast agent, are presented. One hundred and four patients with focal liver or spleen pathologies underwent ferumoxtran-10-enhanced magnetic resonance (MR) imaging at doses of 0.8, 1.1, and 1.7 mg Fe/kg. Overall, 15% patients reported a total of 33 adverse events, regardless of causality. The adverse events most frequently seen were dyspnea (3.8%), chest pain (2.9%), and rash (2.9%). No serious adverse events were reported during the 48 hour observation period. There were no clinically significant effects on vital signs, physical examination, and laboratory results. Ferumoxtran-10 is a safe and well tolerated MR contrast agent.

Contrast Media↗
PubMed1999

Demonstration of gravity-dependent lung perfusion with contrast-enhanced magnetic resonance imaging.

Imaging of lung perfusion using contrast-enhanced dynamic magnetic resonance (MR) was performed in both the supine and prone positions in six volunteers. Regions of interest (ROIs) were chosen in the dependent and non-dependent portions of the right lung. The percentage increase in signal intensity (SI) and the mean slope were calculated. In the supine position, the dorsal ROI had a greater increase in SI (236.0% vs. 156.9%, P < 0.05) and a faster rise in the slope of enhancement (55.1%/sec vs. 30.1%/sec, P < 0.05) than the ventral ROI. After changing to the prone position, higher peak enhancement (234.3% vs. 177.4%, P < 0.05) and faster slopes (59.6%/sec vs. 35.3%/sec, P < 0.05) shifted to the anterior ROI. We conclude that dynamic contrast-enhanced MR imaging is sensitive to demonstrate gravitationally dependent differences in lung perfusion.

Adult↗
PubMed1999

Oxygen-enhanced magnetic resonance ventilation imaging of the human lung at 0.2 and 1.5 T.

Lung ventilation imaging using inhaled oxygen as a contrast medium was performed using both a 0.2 and a 1.5 T clinical magnetic resonance (MR) scanner in eight volunteers. Signal-to-noise-ratios (SNRs) of the ventilation images as well as T1 values of the lung acquired with inhalation of 100% oxygen and room air were calculated. The SNR was 9.7 +/- 3.0 on the 0.2 T MR system and 69.5 +/- 28.8 on the 1.5 T system (P < 0.001). The mean T1 value on the 0.2 T MR system with subjects breathing room air was 632 +/- 54 msec; with 100% oxygen, it was 586 +/- 41 msec (P < 0.01). At 1.5 T, the mean values were 904 +/- 99 msec and 790 +/- 114 msec, respectively (P < 0.0001). We conclude that MR oxygen-enhanced ventilation imaging of the lung is feasible with an open configured 0.2 T MR system.

Adult↗