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At least 19 recordsLinked to original sources
PubMedDate not supplied

Diagnostic accuracy of clinical assessment, magnetic resonance imaging, magnetic resonance arthrography, and intra-articular injection in hip arthroscopy patients.

BACKGROUND: Hip arthroscopy has defined elusive causes of hip pain. HYPOTHESIS/PURPOSE: It is postulated that the reliability of various investigative methods is inconsistent. The purpose of this study is to evaluate the diagnostic accuracy of these methods. STUDY DESIGN: Retrospective review of prospectively collected data. METHODS: Five parameters were assessed in 40 patients: clinical assessment, high-resolution magnetic resonance imaging, magnetic resonance imaging with gadolinium arthrography, intra-articular bupivacaine injection, and arthroscopy. Using arthroscopy as the definitive diagnosis, the other parameters were evaluated for reliability. RESULTS: Hip abnormality was clinically suspected in all cases with 98% accuracy (1 false positive). However, the nature of the abnormality was identified in only 13 cases with 92% accuracy. Magnetic resonance imaging variously demonstrated direct or indirect evidence of abnormality but overall demonstrated a 42% false-negative and a 10% false-positive interpretation. Magnetic resonance arthrography demonstrated an 8% false-negative and 20% false-positive interpretation. Response to the intra-articular injection of anesthetic was 90% accurate (3 false-negative and 1 false-positive responses) for detecting the presence of intra-articular abnormality. CONCLUSIONS: In this series, clinical assessment accurately determined the existence of intra-articular abnormality but was poor at defining its nature. Magnetic resonance arthrography was much more sensitive than magnetic resonance imaging at detecting various lesions but had twice as many false-positive interpretations. Response to an intra-articular injection of anesthetic was a 90% reliable indicator of intra-articular abnormality.

Arthrography↗
PubMed2005

Narrow band deformable registration of prostate magnetic resonance imaging, magnetic resonance spectroscopic imaging, and computed tomography studies.

PURPOSE: Endorectal (ER) coil-based magnetic resonance imaging (MRI) and magnetic resonance spectroscopic imaging (MRSI) is often used to obtain anatomic and metabolic images of the prostate and to accurately identify and assess the intraprostatic lesions. Recent advancements in high-field (3 Tesla or above) MR techniques affords significantly enhanced signal-to-noise ratio and makes it possible to obtain high-quality MRI data. In reality, the use of rigid or inflatable endorectal probes deforms the shape of the prostate gland, and the images so obtained are not directly usable in radiation therapy planning. The purpose of this work is to apply a narrow band deformable registration model to faithfully map the acquired information from the ER-based MRI/MRSI onto treatment planning computed tomography (CT) images. METHODS AND MATERIALS: A narrow band registration, which is a hybrid method combining the advantages of pixel-based and distance-based registration techniques, was used to directly register ER-based MRI/MRSI with CT. The normalized correlation between the two input images for registration was used as the metric, and the calculation was restricted to those points contained in the narrow bands around the user-delineated structures. The narrow band method is inherently efficient because of the use of a priori information of the meaningful contour data. The registration was performed in two steps. First, the two input images were grossly aligned using a rigid registration. The detailed mapping was then modeled by free form deformations based on B-spline. The limited memory Broyden-Fletcher-Goldfarb-Shanno algorithm (L-BFGS), which is known for its superior performance in dealing with high-dimensionality problems, was implemented to optimize the metric function. The convergence behavior of the algorithm was studied by self-registering an MR image with 100 randomly initiated relative positions. To evaluate the performance of the algorithm, an MR image was intentionally distorted, and an attempt was then made to register the distorted image with the original one. The ability of the algorithm to recover the original image was assessed using a checkerboard graph. The mapping of ER-based MRI onto treatment planning CT images was carried out for two clinical cases, and the performance of the registration was evaluated. RESULTS: A narrow band deformable image registration algorithm has been implemented for direct registration of ER-based prostate MRI/MRSI and CT studies. The convergence of the algorithm was confirmed by starting the registration experiment from more than 100 different initial conditions. It was shown that the technique can restore an MR image from intentionally introduced deformations with an accuracy of approximately 2 mm. Application of the technique to two clinical prostate MRI/CT registrations indicated that it is capable of producing clinically sensible mapping. The whole registration procedure for a complete three-dimensional study (containing 256 x 256 x 64 voxels) took less than 15 min on a standard personal computer, and the convergence was usually achieved in fewer than 100 iterations. CONCLUSIONS: A deformable image registration procedure suitable for mapping ER-based MRI data onto planning CT images was presented. Both hypothetical tests and patient studies have indicated that the registration is reliable and provides a valuable tool to integrate the ER-based MRI/MRSI information to guide prostate radiation therapy treatment.

Algorithms↗
PubMedDate not supplied

Demineralized bone matrix-induced ectopic bone formation in rats: in vivo study with follow-up by magnetic resonance imaging, magnetic resonance angiography, and dual-energy X-ray absorptiometry.

The aim of this study was to further explore the use of magnetic resonance imaging (MRI), magnetic resonance angiography (MRA), and dual-energy X-ray absorptiometry (DEXA) to assess bone formation and blood circulation in a pedicled bone graft substitute. In 14 Wistar rats, initially 10 weeks old, heterogeneous demineralized femur bone matrix implants were wrapped in pedicled adductor thigh muscle flaps. One rat died after surgery. Subsequently, bone formation and maintenance of blood vessel functionality were evaluated in six rats 6 weeks postimplantation by means of in vivo MRI/MRA and postmortem histomorphometry. The other seven rats were left for 12 weeks, whereafter bone formation was evaluated by in vivo DEXA and postmortem histomorphometry. The results demonstrated that after 6 weeks bone formation was present in four of six animals, quantified as 42 (+/-35)% and 25 (+/-19)% by means of MRI and histomorphometry, respectively. MRA was able to show patency of the pedicles of these four rats only, which suggests that the lack of blood supply in the other two rats is the cause of the failure to form bone. In the 12-week group, histology showed increased bone formation without signs of osteolysis, which was quantified histomorphometrically to be as high as 48 (+/-15)%. DEXA failed to show bone formation. It is concluded that in vivo MRI proved to be a reliable method for monitoring ectopic bone formation in a rat model, whereas in vivo DEXA was unable to detect the implants. Furthermore, in vivo MRA proved to be a useful technique for studying the circulation of muscle flaps in this animal model.

Absorptiometry, Photon↗
PubMed2004

Relationship of structural magnetic resonance imaging, magnetic resonance perfusion, and other disease factors to neuropsychological outcome in sickle cell disease.

OBJECTIVE: To investigate the relationship between neuropsychological functioning and radiographic findings in children with sickle cell disease (SCD) with no history of clinical neurological events. METHODS: Thirty-one patients with SCD randomly selected from a regional treatment center underwent neuropsychological and disease severity assessments. Of these, 22 also had structural magnetic resonance imaging and magnetic resonance perfusion studies performed. RESULTS: Forty-five percent of the imaged subgroup showed imaging abnormalities that were found to be correlated with disease severity but not neuropsychological level of performance indices. A significant relationship, however, was found between imaging abnormalities and increased variability in neuropsychological performance. CONCLUSIONS: These results corroborate the high rate of rheologic and vascular pathology in SCD and underscore the importance of representing neuropsychological functioning in multiple ways.

Adolescent↗
PubMed2005

Carbon monoxide brain toxicity: clinical, magnetic resonance imaging, magnetic resonance spectroscopy, and neuropsychological effects in 9 people.

Carbon monoxide (CO) exposure is a common cause of toxic brain damage, whereby effects range from transient neurological dysfunction to coma and death. A spectrum of severity of magnetic resonance imaging (MRI) findings after CO brain toxicity, including globus pallidus and white matter lesions, is well documented. Reports of MR spectroscopy (MRS) findings re main sparse. This article reports 9 people exposed to CO because of an apartment house's faulty gas heater. Four, with transient loss of consciousness after chronic moderate level CO exposure, suffered intellectual impairment without MRI abnormalities. The MRS of 1 individual demonstrated decreased n-acetyl aspartase in the basal ganglia, bilaterally. Of 5 exposed to high levels for about 12 hours, 1 died prior to clinical and/or MRI evaluation. One who suffered coma recovered but was lost to evaluation. Three, who were unconscious for hours to days, exhibited T2 MRI white matter signal abnormalities. MRS showed decreased basal ganglia n-acetyl aspartase in 2. One of these suffers a Parkinsonian syndrome. All 3 are intellectually impaired. This study demonstrates that although MRI and MRS are useful markers of CO-induced brain damage, they are not always sensitive to resultant intellectual dysfunction.

Acute Disease↗
PubMedDate not supplied

Gamekeeper thumb: diagnosis of ulnar collateral ligament injury using magnetic resonance imaging, magnetic resonance arthrography and stress radiography.

Ulnar collateral ligament (UCL) tears may be nondisplaced or displaced relative to the adductor pollicis aponeurosis. Nondisplaced tears typically heal with immobilization whereas displaced tears require surgery. Nineteen patients with UCL injuries were evaluated using MR Imaging (MRI), MR arthrography, and stress radiography (SR) to determine the efficacy of these techniques in differentiating nondisplaced from displaced UCL tears. Nineteen patients with UCL Injuries were evaluated. MRI was utilized in 5 patients, and MR arthrography in 14, with 12 of these 14 undergoing SR. They were followed until resolution of symptoms; those without relief, and those with suspected displaced UCL tears were surgically explored. Surgery and imaging was correlated. Eight patients underwent surgical repair. SR was abnormal in six patients treated surgically, but was negative in four of six conservatively treated patients with MR findings of nondisplaced tears. All patients with MR or MR arthrographic findings interpreted as being normal or as having a nondisplaced tear improved after conservative treatment. Based on surgical findings and clinical followup, MR arthrography accurately diagnosed 13 of 14 UCL injuries, with one false-positive interpretation. SR is often falsely negative. MR imaging with or without intra-articular contrast injection proved to be accurate in a small series of patients with UCL injuries.

Adult↗
PubMed2006

Advances in breast imaging: magnetic resonance imaging.

Magnetic resonance imaging (MRI) of the breast is rapidly becoming incorporated into clinical practice. Indications for breast MRI include staging of known breast cancer, monitoring response to chemotherapy, assessing recurrence, problem solving, and high-risk screening. Magnetic resonance spectroscopy is a promising technique that may decrease the number of benign biopsies generated by breast MRI in the clinical setting.

Breast Neoplasms↗
PubMedDate not supplied

From signal to image: magnetic resonance imaging physics for cardiac magnetic resonance.

Magnetic resonance imaging (MRI) is a powerful tool which enables the visualization of anatomy and the assessment of many physiological aspects of organ function. MRI and magnetic resonance angiography and magnetic resonance spectroscopy will play critical roles in cardiac applications during the next millennium. Thus, it is important to have a basic understanding of the most important physical processes in MR--the generation of nuclear magnetic resonance signals and their transformation into images. A conceptual description of these processes is the primary focus of this article. Also discussed are some additional signal manipulations specific to the needs of cardiac MRI, a field readily identified as the most significant in modern MRI technology development.

Heart Diseases↗
PubMed1993

Imaging criteria to identify the epileptic focus. Magnetic resonance imaging, magnetic resonance spectroscopy, positron emission tomography scanning, and single photon emission computed tomography.

The use of MRI, MRSI, PET, and SPECT scanning for preoperative evaluation of patients with epilepsy is reviewed. MRI provides the best anatomic detail and contains prognostic information. PET provides useful information in some patients for whom MRI findings are absent or contradictory. Interictal SPECT scanning lacks sufficient specificity to be of use in the preoperative evaluation of refractory patients, whereas ictal SPECT appears to be useful in temporal and extratemporal lobe epilepsy. The new technique of MRSI is described.

Diagnostic Imaging↗
PubMed1991

Assessment of middle-ear status during experimental otitis media using magnetic resonance imaging.

Magnetic resonance imaging has proved to be a useful tool for in vivo imaging of a variety of tissues. In this study, magnetic resonance imaging was applied to the middle ear of experimental animals with otitis media. Results showed that the presence and distribution of effusion within the middle-ear space could be readily determined. Moreover, following injection of gadolinium-diethylenetriaminepentaacetic acid, a contrast agent, the inflamed middle-ear mucosa could be resolved. A comparison between magnetic resonance imaging and tympanometry with respect to the diagnosis of effusion showed that negative pressure tympanograms were equivocal (50% effusion) and that flat or normal tympanograms were in error in approximately 20% of the observations. These data document a role for magnetic resonance imaging in in vivo studies of the pathogenesis of otitis media with effusion.

Acoustic Impedance Tests↗
PubMed1997

Chronically injured posterior cruciate ligament: magnetic resonance imaging.

Magnetic resonance imaging has been said to be highly reliable for diagnosis of acute posterior cruciate ligament insufficiency. In the present study, 13 patients whose posterior cruciate ligament insufficiency had been documented by magnetic resonance imaging within 10 weeks of the acute injury were recalled for a followup examination and magnetic resonance imaging. The followup interval ranged from 5 months to 4 years. In only 23% of the cases did the posterior cruciate ligament still appear discontinuous on followup magnetic resonance imaging. In the remaining 77%, the posterior cruciate ligament was continuous from tibia to femur, although it appeared abnormally arcuate or hyperbuckled. Conventional interpretation of these magnetic resonance images would suggest that the posterior cruciate ligament had healed. Nevertheless, by clinical examination results, these same patients all were judged to have posterior cruciate ligament insufficiency. Thus, it was concluded that although magnetic resonance imaging may be reliable for evaluation of acute posterior cruciate ligament injury, magnetic resonance imaging findings should not be used to infer functional status in chronic cases.

Chronic Disease↗
PubMed1990

Course of murine leukemia retrovirus infection determined in vivo by magnetic resonance imaging.

Magnetic resonance imaging was applied to measure the volumes of spleens and lymph nodes of mice infected with three different leukemia retroviruses (LP-BM5 murine leukemia virus, Friend, and Rauscher) in vivo. Anesthesia by rapid intraperitoneal injection of Saffan was sufficient for magnetic resonance imaging and could be repeated at appropriate intervals. Eleven frontal magnetic resonance images through the abdomen with a center-to-center distance of 1.5 mm between adjacent slices were acquired simultaneously. To optimally demarcate spleens from the surrounding tissues, the magnetic resonance images were mildly T2-weighted for mice infected with LP-BM5 murine leukemia virus and mildly T1-weighted for those infected with Friend and Rauscher virus. Measurements requiring only 3 to 4 hours in groups of 24 to 28 mice were accomplished by using a standardized holder (i) accommodating two animals in the supine position and (ii) ensuring reproducible positioning in the magnetic resonance-instrument, and (iii) by reducing the number of phase-encoding steps of mildly T2-weighted magnetic resonance images from 256 to 128. Volumes of spleens and inguinal lymph nodes were calculated from the respective cross-sectional areas. The weights and magnetic resonance image-derived volumes of spleens and inguinal lymph nodes correlated well (r greater than 0.95). Despite large variations in the extent of splenomegaly and lymphadenopathy at any given time, the progression of the disease could easily be followed by repeating magnetic resonance imaging at intervals. Thus, statistically relevant results can be obtained in an infection model requiring the use of only a few animals.

Alfaxalone Alfadolone Mixture↗
PubMed1994

Clinical impact of breast implant magnetic resonance imaging.

Magnetic resonance imaging has become the state-of-art technique to diagnose the loss of silicone gel-filled mammary implant integrity (rupture, gel leak). In a series of 39 patients considering implant removal (40 procedures, 74 devices), the impact of magnetic resonance imaging on the decisions made by the patient and surgeon was examined. In this selected group of patients, implant rupture or gel leak was found in 17 patients (16 grossly ruptured devices and 7 with gel leak). In 9 (53%) of these patients, magnetic resonance imaging was the decisive factor leading to the request for explantation by the patient. Diagnosis of implant rupture based on history and physical examination was made in 4 patients (confirmed in 3 and negated by magnetic resonance imaging and intraoperatively in 1). In 10 of the 14 remaining patients (26%) with "unexpected" loss of implant integrity (negative history and physical examination), magnetic resonance imaging evidence was the decisive factor for advising explantation by the surgeon. Negative magnetic resonance imaging results did not influence the patient's or surgeon's decisions. Magnetic resonance imaging appears to be a sensitive and specific technique, and there were no false-negative and one false-positive (gel-leak diagnosis) findings in this series.

Adult↗
PubMed1987

Multiple sclerosis disease activity correlates with gadolinium-enhanced magnetic resonance imaging.

Magnetic resonance imaging provides a method of visualizing multiple sclerosis plaques, but the age and activity of these plaques cannot be determined with routine magnetic resonance images. Gadolinium DTPA is a paramagnetic contrast agent that does not cross an intact blood-brain barrier. We studied 16 patients with multiple sclerosis, using magnetic resonance imaging, gadolinium-enhanced magnetic resonance imaging, and computed tomographic scans. Gadolinium enhancement of multiple sclerosis plaques correlated with the clinical activity of the disease and corresponded anatomically with the symptoms and signs. We conclude that gadolinium enhancement of magnetic resonance images is a promising tool in the investigation of multiple sclerosis lesions and that it may provide a method for objective follow-up in clinical trails.

Adult↗
PubMedDate not supplied

Assessment of cardiac function by magnetic resonance imaging.

Magnetic resonance imaging (MRI) is a unique and insightful tool for the assessment of physiology and function in congenital heart disease, in both the preoperative and postoperative state. MRI can accurately measure the volume and mass of unusual ventricular shapes, perform myocardial tissue and blood tagging, and can measure velocity and flow using phase-encoded velocity mapping. This has added new dimensions to research in pediatric cardiology. Newer techniques such as oxygen-sensitive MRI and echo-planar MRI promise further advances in the field. This article describes contemporary MRI studies of the physiology of complex congenital heart disease.

Blood Flow Velocity↗
PubMed1996

[From nuclear magnetic resonance to magnetic resonance imaging].

Magnetic resonance imaging is based upon the phenomenon of nuclear magnetic resonance. The patient is placed in a magnet the provides a strong magnetic field inducing a net magnetization due to hydrogen nuclei inside biological tissues. The image is formed from the localized measurement of this magnetization by means of radio-frequency waves. The contrast is a function of the number of hydrogen nuclei and of the time characteristics T1 and T2 of the return to equilibrium. Many other parameters can be measured by this method and the permanent improvement of the technique will extend further the field of its medical application.

Forecasting↗