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At least 1,621 records · Page 90Linked to original sources
PubMed2004

Micro-MRI methods to detect renal cysts in mice.

BACKGROUND: Mouse models of disease, especially using transgenic and knockout technologies, are powerful tools to analyze the molecular basis of disease. We recently reported that a new dynamic micro-MRI method with dendrimer-based contrast agents can visualize renal structure and function in normal living mice and mice with acute renal failure. While MRI contrast enhancement is useful for detecting functional impairment of the kidneys, this technology has limitations in assessing morphologic changes, particularly cystic disease, because contrast-enhanced micro-MRI depicts cysts as low-intensity areas that cannot be distinguished from fibrotic foci. METHODS: In the current study, we evaluated if micro-MRI employing a new three-dimensional MR hydrography signal sequence [three-dimensional fast imaging employing steady-state acquisition (3D-FIESTA)] can visualize chronic cystic changes without any contrast agents. RESULTS: We were able to positively depict multiple renal cortical cysts of approximately 0.2 mm diameter in a mouse model of sickle cell disease and observe serial changes of renal cysts (>0.2 mm diameter) in cyclooxygenase-2 (COX-2) knockout mice during a 21/2-month period. Some cysts decreased in size over time. CONCLUSIONS: Micro-MRI with 3D-FIESTA can depict cyst formation in the diseased kidneys of living mice without injection of contrast agents.

Anemia, Sickle Cell↗
PubMed1996

[Dynamic magnetic resonance imaging versus dynamic echography in the staging of Peyronie's disease].

Clinical examination and ultrasonography are often the only evaluation needed for patient with Peyronie's disease. Magnetic resonance angiography (MRA), a new magnetic resonance imaging (MRI), improves tissue contrast between the fibrous plaque and the near structures. A total of 25 patients with Peyronie's disease underwent palpation, ultrasonography and MRI after dynamic improvement with intrapenile 10 micrograms prostaglandin E1. The patients were studied with conventional ultrasonography (US) (7.5 MHz) and with 1.5 T superconductive magnet (two-dimensional Fourier transform gradient-echo time-of-flight, 2DFT-TOF, sequences and conventional T1 and T2 spin echo (SE) sequences). The US evaluation demonstrated the presence of plaques in 18/25 patients (72%). The SE sequences revealed evidence of plaques in 10/25 patients (40%). MR angiograph enabled the correct evaluation of plaques in 23/25 patients (92%), and identified the involvement of the septum intercavernosum, that was not detected on both US and SE images. MRA provides accurate preoperative information fo correct evaluation of plaque extension in IPP.

Alprostadil↗
PubMed2003

Image fusion of CT and MRI data enables improved target volume definition in 3D-brachytherapy treatment planning.

PURPOSE: To integrate MRI into CT-based 3D-brachytherapy treatment planning using a software system for image registration and fusion. METHODS AND MATERIALS: Sixteen patients with recurrent head-and-neck cancer, vulvar cancer, liposarcoma, and cervical cancer were treated with interstitial (n=12) and endocavitary (n=4) brachytherapy. CT and MRI scans were performed after implantation and prior to treatment planning. Image registration to integrate the CT and MR information into a single geometric framework was performed using a software algorithm based on mutual information. Conventional 3D-brachytherapy planning based on CT-information alone was compared to brachytherapy planning based on fused CT and MRI data. The accuracy of the image fusion was measured using predefined corresponding landmarks in the CT and MRI data. RESULTS: The presented automated algorithm proved to be robust and reliable (mean registration error 1.8 mm, range 0.8-4.1 mm, SD 0.9 mm). Tumor visualization was difficult using CT alone in all cases. Brachytherapy treatment planning based on fused CT and MRI data enabled better definition of target volume and risk structures as compared to treatment planning based on CT alone. CONCLUSIONS: Image registration and fusion is feasible for afterloading brachytherapy treatment planning. Treatment planning based on fused CT and MRI data resulted in improved target volume and risk structure definition.

Algorithms↗
PubMed2002

Some complications of common treatment schemes of thoracolumbar spine fractures can be predicted with magnetic resonance imaging: prospective study of 53 patients with 71 fractures.

STUDY DESIGN: Prospective cohort study. OBJECTIVES: To study the predictive value of magnetic resonance imaging (MRI) findings of thoracolumbar spine fractures concerning the radiologic and clinical outcome. SUMMARY OF BACKGROUND DATA: Disagreement about the proper treatment of thoracolumbar spine fractures is caused by insufficiency of conventional imaging techniques. Previous studies have shown that MRI is capable of distinguishing injury to all structures of the fractured spine and thus may help develop schemes with higher predictive power. METHODS: A total of 53 patients with 71 fractures were studied with MRI in a prospective fashion. A total of 24 patients with 39 fractures were treated conservatively and 29 patients with 32 fractures were treated operatively after a protocol concerning the treatment options. MRI scans were obtained within 1 week of injury and at the 2-year follow-up. Pain scores were obtained at the 2-year follow-up. Previously described MRI schemes concerning the trauma and post-trauma conditions were used. RESULTS AND CONCLUSIONS: An unfavorable outcome in the conservative group was related to the progression of kyphosis, which in most cases was predictable with the use of trauma MRI findings concerning the endplate comminution and vertebral body involvement. In the operatively treated group, recurrence of the kyphotic deformity was predictable by the lesion of the posterior longitudinal ligamentary complex together with endplate comminution and vertebral body involvement as seen on trauma MRI. The authors recommend the use of MRI to develop reliable prognostic criteria for these injuries.

Adolescent↗
PubMed2006

Complementary aspects of diffusion imaging and fMRI; I: structure and function.

Studying the intersection of brain structure and function is an important aspect of modern neuroscience. The development of magnetic resonance imaging (MRI) over the last 25 years has provided new and powerful tools for the study of brain structure and function. Two tools in particular, diffusion imaging and functional MRI (fMRI), are playing increasingly important roles in elucidating the complementary aspects of brain structure and function. In this work, we review basic technical features of diffusion imaging and fMRI for studying the integrity of white matter structural components and for determining the location and extent of cortical activation in gray matter, respectively. We then review a growing body of literature in which the complementary aspects of diffusion imaging and fMRI, applied as separate examinations but analyzed in tandem, have been exploited to enhance our knowledge of brain structure and function.

Brain Diseases↗
PubMed2001

Dementia with Lewy bodies and AD are not associated with occipital lobe atrophy on MRI.

Dementia with Lewy bodies (DLB) is associated with occipital changes in blood flow and metabolism, but structural changes in this region have not previously been assessed. The authors performed volumetric MRI measurement of the occipital lobe blind to the diagnosis in 23 subjects with DLB, 25 with AD, and 24 age-matched control subjects. There were no significant differences between groups in occipital lobe volume. The authors conclude gross structural changes in the occipital lobe do not occur in patients with mild to moderate DLB or AD.

Aged↗
PubMed1992

The efficacy of MR imaging in subdural empyema.

MRI findings of a 14-year-old boy with subdural empyema (SE) are reported and compared with those of serial CT-scan. He was admitted with fever, headache, right hemiplegia and facial palsy. Initial enhanced CT-scan revealed a slit left lateral ventricle and a shift in the mid-line structures, but failed to detect any SE. MRI at 10 days after admission clearly demonstrated SE as an area of low intensity on T1-weight (T1WI) and very high intensity on T2-weight (T2WI). Post-contrast enhanced MRI (CE-MRI), using Gd-DTPA, showed a contrast enhancement in the wall of SE. However, no definite parenchymal abnormal intensity areas were detected, suggesting that the diagnosis was made sufficiently early for timely treatment and good neurological outcome. CE-MRI proved to be a more powerful and better diagnostic procedure than enhanced CT-scan, and was very useful in determining the state and development of the disease.

Adolescent↗
PubMedDate not supplied

Pigmented villonodular synovitis of the foot: MR findings.

PURPOSE: To evaluate the MRI findings in the various forms of pigmented villonodular synovitis (PVNS) of the foot. MATERIALS AND METHODS: Seven hundred and fifty-three MR studies of the foot performed at our institute between June 1994 and April 2000 were retrospectively reviewed for the presence of PVNS. Spin echo (SE) T1W, Gradient echo (GE) T2*W, and fat suppression (Short Time Inversion Recovery: STIR) images were acquired with a 0.5 T superconductive unit (Vectra, GE Medical System, Milwaukee, WI, USA) provided with a dedicated transmitter/receiver coil. The site and type of lesions, the signal intensity patterns, and the presence of associated changes were evaluated. RESULTS: On the basis of the MR images and the above parameters, six patients (3 men, 3 women, age range: 35-48 years) with PVNS were selected. Three out of six PVNS were nodular, whereas the remaining three were diffuse. Of the three nodular forms, one was found in the sub-talar joint and the remaining two antero-medially to the talus. Instead, all of the diffuse lesions were located on the metatarsus. Perilesional oedema was seen in all cases, although more obvious in the nodular forms, whereas bone involvement (osteochondral erosion) was observed only in the diffuse metatarsal PVNS. Intra-articular bloody effusion was never observed. The MRI findings were confirmed by surgery in all cases. DISCUSSION: The high contrast resolution and multiplanar capabilities of MRI allow the complete evaluation of the structures of the foot affected by PVNS, and of the extent of soft tissue (bursae, synovial or nervous structures), bone and articular involvement. Although not specific, the presence of haemosiderin results in characteristic MR findings, due to the shortening of both T1 and T2 relaxation times. GET2* images are particularly well suited to this PURPOSE: Furthermore, in our experience, FIR images added better depiction of associated swelling. CONCLUSIONS: According to our results, MRI is now the most reliable technique for identifying and classifying PVNS, and allows correct treatment planning and effective monitoring.

Adult↗
PubMed1999

Blink reflex R2 changes and localisation of lesions in the lower brainstem (Wallenberg's syndrome): an electrophysiological and MRI study.

OBJECTIVES: Pathways of late blink reflexes are detected by high resolution MRI. Electronically matched stroke lesions superimposed to an anatomical atlas show the suspected course. METHODS: Fifteen patients with infarction of the lower brainstem, MRI lesions and electrically elicited blink reflexes were examined. The involved structures in patients with R2 and R2c blink reflex changes were identified by biplane high resolution MRI with individual slices matched to an anatomical atlas at 10 different levels using digital postprocessing methods. RESULTS: The blink reflexes were normal in five of 15 patients (33%) and showed loss or delay of R2 and R2c to stimulation ipsilaterally to lesion (R2-i and R2c-i) in eight (53%). Loss or delay of R2-i/R2c-i was seen in lesions covering the entire trigeminal spinal tract and nucleus (TSTN) at at least one level. These infarctions were located more dorsally within the medulla. Patients with normal blink reflexes showed lesions sparing or involving the TSTN only partially. They more often had incomplete Wallenberg's syndromes and MRI lesions were located more ventrally. CONCLUSIONS: Using digital postprocessing MRI methods it was possible to identify central pathways of late blink reflex in patients with Wallenberg's syndrome. This method is suggested as a new approach to identify incompletely understood functional structures of the brainstem.

Aged↗
PubMed2005

Contrast-enhanced MRI with new biodegradable macromolecular Gd(III) complexes in tumor-bearing mice.

The structures of polydisulfide-based biodegradable macromolecular Gd(III) complexes were modified to improve their in vivo retention time and MRI contrast enhancement. Steric hindrance was introduced around the disulfide bonds to control their access to free thiols in order to alter the degradation rate of the copolymers. Two new macromolecular agents, (Gd-DTPA)-cystine copolymers (GDCP) and (Gd-DTPA)-cystine diethyl ester copolymers (GDCEP), were prepared. Both agents were readily degraded in vitro and in vivo by the disulfide-thiol exchange reaction, but at a slow rate. The introduction of COOH and COOEt groups slowed down the degradation of the copolymers in the incubation with 15 microM cysteine. Metabolic degradation products were identified by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry in the urine samples from rats injected with the agents. The T(1) relaxivity (r(1)) was 5.43 mM(-1)s(-1) for GDCP, and 5.86 mM(-1)s(-1) for GDCEP, respectively, at 3T. MRI contrast enhancement of both agents was studied in nude mice bearing MDA-BM-231 human breast carcinoma xenografts, on a Siemens Trio 3T scanner. The modified agents resulted in more significant contrast enhancement in the blood pool and tumor periphery than (Gd-DTPA)-cystamine copolymers (GDCC) and a low-molecular-weight control agent, Gd-(DTPA-BMA), at a dose of 0.1 mmol-Gd/kg. The results demonstrate that the structural modification of the biodegradable macromolecular Gd(III) complexes resulted in a relatively slow degradation of the macromolecules and significantly improved in vivo contrast enhancement. The modified agents show promise for use in investigations of blood pool and cancer by contrast-enhanced (CE) MRI.

Animals↗
PubMedDate not supplied

Nuclear magnetic resonance imaging, a new approach to the investigation of refractory temporal lobe epilepsy.

Nuclear magnetic resonance is a noninvasive technique of imaging the brain using signals produced by magnetic fields and radiowaves. Sixteen patients with refractory temporal lobe epilepsy (TLE) had magnetic resonance imaging (MRI) during investigation for possible surgical management. These images plus those of 10 normal controls, were interpreted blind and the results from the TLE patients compared to the EEG and computerized tomographic (CT) scan findings. Fourteen patients compared with one normal control had one or more of the following: small temporal lobe, small mesial temporal structures, small hemisphere, and focal mesial temporal prolonged spin-spin relaxation time. These findings correlated with the electrographically determined seizure focus in 11 patients. Enlarged or asymmetrical temporal horns were seen with equal frequency in patients and controls and did not correlate with the seizure focus. CT scans were less likely to show these changes than MRI. Correlation of the MRI changes with histopathology of resected temporal lobes was poor. MRI reveals structural and possibly functional alterations which may aid in the localization of the seizure focus in the temporal lobes of patients with refractory complex partial seizures.

Adolescent↗
PubMed2000

Magnetic resonance and positron emission tomography changes during the clinical progression of Rasmussen encephalitis.

The authors describe serial positron emission tomography (PET) and magnetic resonance imaging (MRI) studies in a patient with pathologically confirmed Rasmussen Encephalitis (RE). Results of initial PET and MRI studies were normal. Subsequent studies showed involvement of the percentral and postcentral gyri and the putamen on PET, and the precentral and postcentral gyri on MRI. Coregistration of PET and MR images showed good correlation between the precentral and postcentral gyri involvement. However, subcortical involvement occurred earlier on PET than on MRI. The authors demonstrate the evolution of changes on PET and MR images in a patient with RE. Despite early pathologic confirmation of RE, there were no definite structural or functional imaging changes on PET or MRI until 3 years after symptom onset. These findings demonstrate the variability of imaging changes in RE, and the need to carefully correlate electro-physiologic and clinical findings to confirm the diagnosis of RE.

Brain↗
PubMed2004

Alcohol intake in relation to brain magnetic resonance imaging findings in older persons without dementia.

BACKGROUND: Consumers of light-to-moderate amounts of alcohol have a lower risk of dementia and, possibly, Alzheimer disease than do abstainers. Because vascular disease may contribute to symptoms of Alzheimer disease, reduction of cerebrovascular disease in consumers of light amounts of alcohol could account for that observation. However, a low concentration of alcohol may also have direct effects on the hippocampus, a brain structure highly affected by Alzheimer disease. OBJECTIVE: We investigated alcohol intake in relation to brain magnetic resonance imaging (MRI) findings of presumed vascular origin (ie, white matter lesions and infarcts) and findings more specifically found in early Alzheimer disease (ie, hippocampal and amygdalar atrophy). DESIGN: In a population-based sample of 1074 older persons without dementia (aged 60-90 y), we made brain MRIs from which we rated white matter lesions and brain infarcts. In a subset of 509 people, hippocampal and amygdalar volumes on MRI were measured. Alcohol intake was assessed by using a structured questionnaire. We categorized alcohol intake as lifetime abstention and very light (<1 drink/wk), light (>/=1 drink/wk to <1 drink/d), moderate (>/=1 drink/d to <4 drinks/d), and heavy (>/=4 drinks/d) intakes. RESULTS: Persons whose alcohol consumption was light to moderate had less severe white matter lesions and brain infarcts on MRI than did abstainers or heavy drinkers. Abstainers and very light drinkers had smaller hippocampal and amygdalar volumes on MRI than did light-to-moderate drinkers, but only if the former carried an apolipoprotein (APOE) epsilon4 allele. CONCLUSION: Light-to-moderate alcohol intake is associated with a lower prevalence of vascular brain findings and, in APOE epsilon4 carriers, hippocampal and amygdalar atrophy on MRI.

Aged↗
PubMed1995

[Space-occupying lesions of the lacrimal gland in CT and MRI exemplified by 4 cases].

In an extended case report, we discuss four cases with masses in the lacrimal fossa representing the most important entities in this region (lymphoma, pleomorphadenoma, inflammatory pseudotumor, and malignant epithelial tumor). The different indications for CT and MRI are explained. For the differential diagnosis of lacrimal gland lesions, the following imaging parameters are important: the shape of the lacrimal gland, the inner structure, the degree of contrast enhancement, and the surrounding bony structures. In the evaluation of the expansion of lacrimal gland lesions, CT in thin slices with multiplanar reconstructions is equal to MRI. However, the contrast-enhancement of lacrimal glands is better evaluated with MRI than with CT. The bony structures are better visualized on CT than on MRI.

Adenoma, Pleomorphic↗
PubMed1986

Oblique magnetic resonance imaging of the cardiovascular system.

This exhibit demonstrates that cardiac anatomy can be imaged by MRI in oblique planes that are equivalent to views obtained radiographically or at angiocardiography. These MR images may be obtained either by simple patient positioning or by electronic rotation of the imaging axis. The advantages of this technique include its simplicity and its ability to show detailed anatomy noninvasively. Major cardiac structures including chambers, walls, vessels and bronchi are optimally demonstrated in long axis or cross section. This permits estimation of chamber volume, wall thickness, vessel position and variations from normal. Smaller structures are also well visualized. These include the pericardium, papillary muscles, azygos vein and some cross sectional anatomy of the coronary arteries and veins. The valvular structures can be shown during diastole or systole. The ability of MRI to show these cardiac structures due to the intrinsic contrast differences in signal intensity between muscle, fat, flowing blood and lung suggest an important future for MR cardiac imaging in a broad group of congenital and acquired diseases of the heart, pericardium and great vessels.

Heart↗
PubMed1989

Diagnosing disk dysfunction and tissue changes in the temporomandibular joint with magnetic resonance imaging.

Magnetic resonance imaging (MRI) is a noninvasive technique that clearly documents disk positioning abnormalities and tissue structure changes not previously discovered except by surgical intervention and biopsy. The MRI also shows hyperplasias, disk folds, displaced disks, and disk thinning-important information to have before surgical intervention is begun. Overall, MRI provides a basis for complex dental treatment planning and prognostic evaluation.

Adult↗
PubMed1994

Magnetic resonance imaging and computed tomography of transitional cell carcinoma of renal pelvis and ureter.

Fourteen patients with clinically suspicious transitional cell carcinoma of renal pelvis or ureter were preoperatively examined with magnetic resonance imaging (MRI) and computed tomography (CT). All of the cases had surgical approval. In eleven of these patients, the tumor was correctly detected by MRI. Two cases were falsely positive including one squamous cell carcinoma (SCC) and one Wilms' tumor of the kidney. The final case was falsely negative. The positive predictive value of MRI was 92.9%. The sensitivity was 91.7%. In seven of the fourteen patients, the CT findings were truly positive. There were five falsely negative findings and two falsely positive cases. The positive predictive value by CT was 64.3%. The sensitivity was 59.3%. Tumor stagings were done for all patients. The accuracy rate of staging was 7/7 by CT and 10/11 by MRI. MRI showed better identification of distant metastasis in the liver, vertebrae and vascular structure because of its high tissue contrast and larger field of view. MRI had a higher positive predictive rate and sensitivity for identification of uroepithelial tumor than CT.

Aged↗
PubMed1996

Surgical treatment of extratemporal epilepsy: clinical, radiologic, and histopathologic findings in 60 patients.

PURPOSE AND METHODS: The aim of this study was to analyze clinical, radiologic, and histopathologic findings in 60 consecutive patients with medically intractable extratemporal epilepsy who were operated on between November 1987 and May 1993. RESULTS: Histologically, there were distinct structural abnormalities in 50 (83%) of the surgical specimens. Signal abnormalities on magnetic resonance imaging (MRI) were present in all patients with neoplastic lesions (n = 17) and in 94% of patients with nonneoplastic focal lesions (n = 32). Overall, structural abnormalities were detected by MRI in 47 (96%) of 49 patients with focal lesions. During a mean follow-up of 4 years, 30 (54%) patients remained completely seizure free, 11 (20%) had < or = 2 seizures per year, seven (12%) showed a seizure reduction of > or = 75%, and eight (14%) had < 75% reduction in seizure frequency. The fraction of seizure-free patients was 12 (80%) of 15 in patients with neoplastic lesions, 16 (52%) of 31 in patients with nonneoplastic focal lesions, and two (20%) of 10 for those without histopathologic abnormalities. The differences in seizure outcome between patients with and without focal lesions were statistically significant (p < 0.05), if seizure-free outcome was compared with persistent seizures. CONCLUSIONS: Focal lesions and particularly neoplasms are associated with improved postoperative seizure control compared with patients without histopathologic abnormalities. We advise caution in considering surgery to treat extratemporal epilepsy in patients who have normal MRI scans, because the outcome with the approach described in this study is poor in such cases.

Adolescent↗