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1.
2.
The challenges in detection, localization, and staging of prostate cancer have prompted the investigation of the role of various
magnetic resonance (MR) methodologies in a large cohort of men prior to biopsy. The identification of suspicious areas of
malignancy was carried out using magnetic resonance imaging (MRI), magnetic resonance spectroscopic imaging (MRSI) and diffusion-weighted
imaging (DWI). Our data shows that apparent diffusion coefficient (ADC) may be a reliable marker to differentiate normal,
benign, and malignant prostate tissues similar to the metabolite ratio. Also, the combined use of MRSI and DWI improves the
diagnosis of prostate cancer. In this review, we present our experience on the use of MRI, MRSI and DWI methods in the assessment
of prostate cancer in Indian men. Further, analysis of the comparison of the ADC and the metabolite ratio values reported
in the literature across various patient populations are presented.
An erratum to this article can be found at 相似文献
3.
Plein S Smith WH Ridgway JP Kassner A Beacock DJ Bloomer TN Sivananthan MU 《Magma (New York, N.Y.)》2001,13(2):101-108
This study investigates the use of real-time acquisition in cardiac magnetic resonance imaging (MRI) for measurements of left
ventricular dimensions in comparison with conventional gradient echo acquisition. Thirty-one subjects with a variety of left
ventricular morphologies to represent a typical clinical population were studied. Short-axis data sets of the left ventricle
(LV) were acquired using a conventional turbo-gradient echo and an ultrafast hybrid gradient echo/echo planar sequence with
acquisition in real-time. End-diastolic volume (EDV), end-systolic volume (ESV), ejection fraction (EF) and left ventricular
mass (LV mass) were measured. The agreement between the two acquisitions and interobserver, intraobserver and interstudy variabilities
were determined. The bias between the two methods was 5.86 ml for EDV, 0.23 ml for ESV and 0.94% for EF. LV mass measurements
were significantly lower with the real-time method (mean bias 14.38 g). This is likely to be the result of lower spatial resolution
and chemical shift artefacts with the real-time method. Interobserver, intraobserver and interstudy variabilities were low
for all parameters. In conclusion, real time acquisition in MRI can provide accurate and reproducible measurements of LV dimensions
in subjects with normal as well as abnormal LV morphologies, but LV mass measurements were lower than with conventional gradient
echo imaging.
Presented in abstract form at the International Society of Magnetic Resonance in Medicine meeting in Denver, Colorado in April
2000. 相似文献
4.
Jeanette Schulz-Menger Oliver Strohm Rainer Dietz Matthias G. Friedrich 《Magma (New York, N.Y.)》2000,11(1):82-83
5. Summary Contrast-enhanced MRI may serve as a sensitive noninvasive tool for the detection and follow-up of myocardial involvement
in patients with systemic sarcoidosis. 相似文献
5.
Gadolinium-enhanced magnetic resonance angiography of the pelvis in patients with erectile impotence
Michael K. Stehling Libin Liu Gerhard Laub Kurt Fleischmann Ulrike Rohde 《Magma (New York, N.Y.)》1997,5(3):247-254
This study evaluted the potential of contrast-enhanced digital-subtraction magnetic resonance angiography (CE-DS-MRA) for
noninvasive angiographic delineation of the arterial supply of the penis in patients with erectile dysfunction. After induction
of an erection with prostaglandin E, a three-dimensional fast imaging with steady-state precision (FISP) sequence with TE
of 1.8–2 milliseconds, TR of 4.4–5 milliseconds, and flip angle of 40°–60° was used to obtain high-resolution angiograms of
the pelvis and penis during the injection of gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA) 0.3 mmol/kg body weight,
within 30–50 seconds. DS maximum intensity projections (MIPs) and multiplanar reconstructions (MPRs) were compared with clinical
work-up and directional Doppler ultrasound in 11 patients. In all 11 patients (100%), the arterial supply of the penis could
be delineated from the aortic bifurcation via the iliac and internal pudendal arteries to the dorsal and deep penile arteries.
Of the 22 internal pudendal arteries, 6 (27%) were occluded on CE-DS-MRA and 5 (23%) had stenoses, of which 4 (18%) were greater
than 50%. In 7 patients (64%) good correlation between CE-DS-MRA and clinical findings and/or Doppler ultrasound was found;
in 2 patients (18%), the correlation was moderate, and in 2 patients (18%) results were discrepant. In 6 patients (55%), MRA
provided additional information to the clinical and Doppler ultrasound work-up. CE-DS-MRA can delineate small sessels such
as the internal pudendal and penile arteries and thus has the potential to become a noninvasive angiography method in the
work-up of erectile impotence.
Supported by Siemens Medical Systems, Erlangen; Schering AG, Berlin; and Agfa-Gevaert AG, Leverkusen. 相似文献
6.
Cardiac magnetic resonance imaging (MRI) on small animals is possible but remains challenging and not well standardized. This publication aims to provide an overview of the current techniques, applications and challenges of cardiac MRI in small animals for researchers interested in moving into this field. Solutions have been developed to obtain a reliable cardiac trigger in both the rat and the mouse. Techniques to measure ventricular function and mass have been well validated and are used by several research groups. More advanced techniques like perfusion imaging, delayed enhancement or tag imaging are emerging. Regarding cardiac applications, not only coronary ischemic disease but several other pathologies or conditions including cardiopathies in transgenic animals have already benefited from these new developments. Therefore, cardiac MRI has a bright future for research in small animals. 相似文献
7.
Gordon DeMeester Michael Morich Alex Byrne Frank Davies David Melotte Adrian Thomas 《Magma (New York, N.Y.)》2001,13(3):193-198
The desire to improve patient comfort and acceptance of high field magnetic resonance imaging (MRI) systems results in new-approaches
to magnet and other critical MRI component design. One such approach, based upon an anatomical field of view analysis, is
presented in this paper. The approach is utilized to define imaging volume requirements for short, high field, solenoid magnet
designs that maintain whole body imaging capability. A short magnet design with excellent magnetic field homogeneity is presented
accordingly. Combined with a novel flared gradient coil the overall system achieves improvements in openness. 相似文献
8.
Zhang Z van den Bos EJ Wielopolski PA de Jong-Popijus M Duncker DJ Krestin GP 《Magma (New York, N.Y.)》2004,17(3-6):201-209
Myoblast transplantation is a promising means of restoring cardiac function in infarcted areas. For optimization of transplant protocols, tracking the location and fate of the injected cells is necessary. An attractive imaging modality for this is magnetic resonance imaging (MRI) as it is noninvasive and as iron-labeled myoblasts provide a signal attenuation in T2*-weighted protocols. The aim of this study was to develop an efficient iron-labeling protocol for myoblasts and to visualize single-labeled cells using a clinical 1.5-T scanner. Pig myoblasts were labeled with a superparamagnetic iron oxide (SPIO) agent using a liposome transfection agent. Labeling efficiency, toxicity, cell viability, and proliferative capacity were measured for 10 days. Magnetic resonance (MR) of myoblast cultures used a T2*-weighted three-dimensional protocol with a maximum in-plane resolution of 19.5 × 26.0 m2 and 50 m slices. Use of liposomes improved SPIO labeling efficiency. Labeling did not induce toxicity or affect cell viability or proliferation. The cell distribution as observed with light and fluorescence microscopy matched the signal voids observed in the MRI datasets. Liposomes promote fast, nontoxic and efficient SPIO labeling of myoblasts that can be tracked by MRI microscopy in clinical scanners using susceptibility-weighted protocols. 相似文献
9.
Fissoune R Pellet N Chaabane L Contard F Guerrier D Briguet A 《Magma (New York, N.Y.)》2004,17(3-6):229-235
High-resolution MRI of obese (fa/fa) Zucker rats was investigated to characterize and assess in vivo adipose tissue distribution. Thirty animals were gavaged with a placebo, a PPAR activator (pioglitazone), or a dual PPAR activator (LM 4156). At day 15, T1-weighted images were acquired in vivo using a 2TMRI system with a high in-plane spatial resolution (254 m). Fat volumes of selected territories were measured by image segmentation, and the retroperitoneal fat was weighed post-mortem. Body-weight gain was significant with pioglitazone (101.8±5.9 g, p<0.01 vs. placebo). The good quality of MR images allowed the delimitation and quantification of different fat territories. In response to pioglitazone, the retroperitoneal fat was more important compared to placebo (+23%, p<0.01) while subcutaneous fat was not different. No significant effects were observed with LM 4156. In vivo measurements of fat volumes were strongly correlated with ex vivo tissue weights (r=0.91). High-resolution MRI provides an in vivo measurement of adipose tissue distribution in obese Zucker rats. Specific fat depots of regions that were particularly involved in drug response were determined in vivo. Fat remodeling was observed with pioglitazone but not with a dual PPAR activator (LM 4156). 相似文献
10.
Automatic segmentation and plaque characterization in atherosclerotic carotid artery MR images 总被引:1,自引:0,他引:1
Adame IM van der Geest RJ Wasserman BA Mohamed MA Reiber JH Lelieveldt BP 《Magma (New York, N.Y.)》2004,16(5):227-234
In vivo MRI provides a means to non-invasively image and assess the morphological features of atherosclerotic carotid arteries.
To assess quantitatively the degree of vulnerability and the type of plaque, the contours of the lumen, outer boundary of
the vessel wall and plaque components, need to be traced. Currently this is done manually, which is time-consuming and sensitive
to inter- and intra-observer variability. The goal of this work was to develop an automated contour detection technique for
tracing the lumen, outer boundary and plaque contours in carotid MR short-axis black-blood images. Seventeen patients with
carotid atherosclerosis were imaged using high-resolution in vivo MRI, generating a total of 50 PD- and T1-weighted MR images.
These images were automatically segmented using the algorithm presented in this work, which combines model-based segmentation
and fuzzy clustering to detect the vessel wall, lumen and lipid core boundaries. The results demonstrate excellent correspondence
between automatic and manual area measurements for lumen (r=0.92) and outer (r=0.91), and acceptable correspondence for fibrous cap thickness (r=0.71). Though further optimization is required, our algorithm is a powerful tool for automatic detection of lumen and outer
boundaries, and characterization of plaque in atherosclerotic vessels. 相似文献
11.
Clinical examinations of reptiles are physically limited and therefore usually have to be complemented by other methods. This is especially true for Chelonians. A modern imaging technique like magnetic resonance imaging is well suited for this purpose. Its application and practical experiences with tortoises are presented. 相似文献
12.
Monitoring the survival of islet transplants by MRI using a novel technique for their automated detection and quantification 总被引:1,自引:1,他引:0
Daniel Jirak Jan Kriz Michal Strzelecki Jiabi Yang Craig Hasilo David J. White Paula J. Foster 《Magma (New York, N.Y.)》2009,22(4):257-265
Object There is a clinical need to be able to assess graft loss of transplanted pancreatic islets (PI) non-invasively with clear-cut
quantification of islet survival. We tracked transplanted PI in diabetic mice during the early post-transplant period by magnetic
resonance imaging (MRI) and quantified the islet loss using automatic segmentation technique.
Materials and methods Magnetically labeled islet iso-, allo- and xenografts were injected into the right liver lobes. Animals underwent MRI scanning
during 14 days after PI transplantation. MR images were processed using custom-made software, which automatically detects
hypointense regions representing PI. It is based on morphological top-hat and bottom-hat transforms.
Results Manually and automatically detected areas, corresponding to PI, differed by 4% in phantoms. Signal loss regions due to PI
decreased comparably in all groups during the first week post transplant. Throughout the second week post-transplant, the
signal loss area continued in a steep decline in case of allografts and xenografts, whereas the decline in case of isografts
slowed down.
Conclusion Automatic segmentation allows for the more reproducible, objective assessment of transplanted PI. Quantification confirms
the assumption that a significant number of islets are destroyed in the first week following transplantation irrespective
of allografts, xenografts or isografts. 相似文献
13.
K. T. Moriarty D. G. O. Mclntyre K. Bingham R. Coxon P. M. Glover P. L. Greenhaff I. A. Macdonald H. S. Bachelard P. G. Morris 《Magma (New York, N.Y.)》1994,2(3):429-432
We have used natural abundance13C magnetic resonance spectroscopy (MRS) to measure glycogen content of muscle and liver before and after heavy exercise, and after consumption of different carbohydrate-based drinks. After an overnight fast, five healthy men (mean±SEM age 23±1 years) exercised to exhaustion at 75% of VO2max on two occasions (mean work rate 165±8 W for 78±14 min) and then, in a single blind random order, consumed either of two drinks containing the same carbohydrate load (177 g). Spectra were recorded over Vastus Lateralis muscle and the liver before and after exercise, and hourly for 5 h after the carbohydrate load. In muscle, glycogen content after exercise was 37% and 31% of basal (preexercise) concentration before consuming the drinks. After carbohydrate loading, glycogen concentration had increased significantly (p<0.05) to 70% and 64% of basal concentration respectively after 5 h. Hepatic glycogen concentration did not change significantly throughout. The study demonstrates the feasibility of sequential MRS measurement of muscle and liver glycogen before and after exercise and after carbohydrate loading. 相似文献
14.
Huang R Posnansky O Celik A Oros-Peusquens AM Ermer V Irkens M Wegener HP Shah NJ 《Magma (New York, N.Y.)》2006,19(3):124-133
The use of magnetic resonance imaging (MRI)-based methods for the direct detection of neuronal currents is a topic of intense investigation. Much experimental work has been carried out with the express aim of establishing detection thresholds and sensitivity to flowing currents. However, in most of these experiments, magnetic susceptibility enhancement was ignored. In this work, we present results that show the influence of a susceptibility artefact on the detection threshold and sensitivity. For this purpose, a novel phantom, consisting of a water-filled cylinder with two wires of different materials connected in series, was constructed. Magnitude MR images were acquired from a single slice using a gradient-echo echo planar imaging (EPI) sequence. The data show that the time course of the detected MR signal magnitude correlates very well with the waveform of the input current. The effect of the susceptibility artefacts arising from the two different wires was examined by comparing the magnitudes of the MR signals at different voxel locations. Our results indicate the following: (1) MR signal enhancement arising from the magnetic susceptibility effect influences the detection sensitivity of weak current; (2) the detection threshold and sensitivity are phantom-wire dependent; (3) sub-μ A electric current detection in a phantom is possible on a 1.5-T MR scanner in the presence of susceptibility enhancement. 相似文献
15.
Cavallaro A Fellner F Matzel KE Stadelmaier U Rupprecht T Böwing B Hohenberger W Bautz W 《Magma (New York, N.Y.)》1998,7(3):179-183
The aim of this study was to determine whether low-field magnetic resonance (MR) imaging can safely and accurately depict
inflammatory changes in patients with anal dynamic graciloplasty, in whom high-field MR imaging is contraindicated and ultrasonography
and computed tomography are inadequate. A 0.2-T field-strength MR examination was performed in six patients with anal dynamic
graciloplasty malfunction in whom reoperation was contemplated. The following sequences were applied:T
2-weighted turbo spinecho with fat saturation,T
1-weighted conventional spin-echo, and contrastenhancedT
1-weighted conventional spin-echo with fat saturation. Results indicated that none of the patients experienced relevant discomfort,
pacemaker malfunction, or electrode dislocation with low-field MR imaging. Inflammatory pelvic changes were visualized in
four patients and atrophy of the transposed gracilis muscle in another. Surgery was thus avoided in the four, who underwent
conservative treatment for their pelvic inflammation. It was concluded that these prelininary results demonstrate the feasibility
of MR imaging with a low field strength in patients with anal dynamic graciloplasty. In such patients, in whom diagnostic
imaging had been problematic, the potential for safe and accurate visualization will be a boon to treatment planning. 相似文献
16.
In vivo 31P-MRS investigations have been widely used in small animals to study skeletal muscle function under normal and pathological conditions. Paradoxically in these studies, the benefit provided by 31P-MRS in terms of non-invasiveness is lost because of the utilization of experimental setups that integrate invasive devices for inducing muscle contractions and for measuring mechanical performance. These traditional methodologies, which require surgical preparations, have obvious limitations regarding repeatability in the same animal. The purpose of this review is to highlight the technical aspects of the in vivo MR investigations of skeletal muscle function in small animal models. We will more particularly address the issue related to the invasiveness of different procedures used so far in order to show finally that a further step into non-invasiveness can be achieved, in particular with the support of muscle functional 1H-MRI. 相似文献
17.
Detection of myocardial viability in acute infarction using contrast-enhanced <Superscript>1</Superscript>H magnetic resonance imaging 总被引:2,自引:0,他引:2
Hillenbrand HB Sandstede J Lipke C Köstler H Pabst T Werner E Ertl G Hahn D Bauer WR 《Magma (New York, N.Y.)》2003,16(3):129-134
Background Reperfusion strategies salvage myocardium at risk in acute myocardial infarction (MI). This clinical study was performed to
determine whether areas without evidence of delayed MRI contrast enhancement in MI correspond to viability by means of percent
systolic wall thickening (%SWT) and enddiastolic wall thickness (EDWT) in chronic infarction.
Methods Twenty MRI studies were performed in ten patients within 6 days of MI and 3 months post-MI. On a segmental basis the percentage
of viable myocardium as defined by contrast-enhanced MRI (no delayed MRI contrast enhancement) in acute MI was measured and
was compared with %SWT and EDWT in chronic MI.
Results Of the 1718 segments in acute infarction in which the percentage of viable myocardium was measured 1333 were found to be completely
viable by means of contrast-enhanced MRI (no delayed MRI contrast enhancement). All of these segments revealed %SWT on day
90 post-MI, and 97% of segments were viable by means of an EDWT of more than 5.5 mm. In 85 segments the proportion of viable
myocardium was 50–99% (mean 56±8%), with 92% segments found to be viable by means of %SWT and 92% by EDWT, and of 156 segments
with viable myocardium between 1–49% (36±8%) 79% were found to be viable by means of %SWT and 82% by EDWT. Corresponding proportions
of 144 segments with transmural delayed MRI contrast enhancement in acute MI were 45% and 17%.
Conclusions In acute reperfused MI viable myocardium as delineated by contrast-enhanced MRI is correlated with clinical parameters of
viability. Delayed MRI contrast enhancement resolves nontransmural MI and may become a valuable clinical tool when planning
revascularization procedures. 相似文献
18.
Java-based graphical user interface for the MRUI quantitation package 总被引:24,自引:4,他引:20
Naressi A Couturier C Devos JM Janssen M Mangeat C de Beer R Graveron-Demilly D 《Magma (New York, N.Y.)》2001,12(2-3):141-152
This article describes the Java-based version of the magnetic resonance user interface (MRUI) quantitation package. This package
allows MR spectroscopists to easily perform time-domain analysis of in vivo MR spectroscopy data. We show that the Java programming
language is very well suited for developing highly interactive graphical software applications such as the MRUI software.
We have also established that MR quantitation algorithms, programmed in other languages, can easily be embedded into the Java-based
MRUI by using the Java native interface (JNI). This new graphical user interface (GUI) has been conceived for the processing
of large data sets and uses prior knowledge data-bases to make interactive quantitation algorithms more userfriendly. 相似文献
19.
Comparison of plain radiographs and magnetic resonance images in the evaluation of periosteal reaction and osteoid matrix in osteosarcomas 总被引:1,自引:0,他引:1
Rosa Dosdá Luis Martí-Bonmatí Francisco Menor Francisco Aparisi Carmen Rodrigo Veronica Ricart 《Magma (New York, N.Y.)》1999,9(1-2):72-80
To determine the relationship and the degree of agreement between radiographs and MR images for the existence of osteoid matrix
and periosteal reactions in the initial diagnosis of osteosarcomas. the plain radiographs and MR studies of 54 patients with
proven osteosarcoma were retrospectively evaluated. In each tumor the visualization and type of osseous matrix, periosteal
reaction and Codman angle were recorded independently for both techniques and by consensus between two radiologists. In 37
tumors agreement existed regarding osteoid matrix and in 31 cases regarding periosteal reactions. The Kappa statistic showed
a significant relationship between both tests (0.49 and 0.44, respectively). Both techniques were also not statistically different
in the proportion of findings with the McNemar test. Therefore, the ability of MR images seems important in reporting the
MR features of bone tumors. Identification of osteoid mineralization and periosteal reaction can also be used with MR in the
diagnosis of osteosarcoma. 相似文献
20.
Heverhagen JT Hahn HK Wegmann M Herz U Shaffer Whitaker CD Matschl V Alfke H 《Magma (New York, N.Y.)》2004,17(2):80-85
Small animal models are widely used to study various pathologies. Magnetic resonance imaging (MRI) allows investigation of these animals in a non-invasive way. Therefore, the aim of our study was to develop and evaluate a low-cost approach to measure lung volumes in small animal MRI using a clinical scanner and a specially designed RF coil. Five mice (three of an established emphysema model and two controls) were investigated in a 1.0-T clinical scanner using a specially built small animal saddle coil and three different three-dimensional sequences; overall imaging time was approximately 16 min. Lung volumes were calculated from these images using an interactive watershed transform algorithm for semi-automatic image segmentation. The gold standard for the volume measurement was water displacement after surgical explantation. MRI measured volumes correlated significantly with ex vivo measurements on the explanted lungs (r = 0.99 to 0.89; p < 0.05). Mean lung volume in emphysema model mice was larger than in controls. High-resolution, small animal MRI using a clinical scanner is feasible for volumetric analysis and provides an alternative to a dedicated small animal scanner. 相似文献