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At least 55 records · Page 3Linked to original sources

PubMed1999

Results of a prospective multicenter study for evaluation of the diagnostic quality of an open whole-body low-field MRI unit. A comparison with high-field MRI measured by the applicable gold standard.

OBJECTIVE: To evaluate the diagnostic quality of an open whole-body low-field MRI scanner compared to high-field scanners. MATERIALS AND METHODS: Over a period of 3 months, 401 patients with diseases of the kidney (n = 78), the shoulder (n = 122), the spine (n = 105) and the cerebrum (n = 96) were prospectively evaluated in four participating centers. They all underwent clinical evaluation, low-field and high-field MRI examination and surgical or follow-up confirmation of diagnosis. Clinical, histopathologic, high-field and low-field MRI diagnoses were recorded in standardized questionnaires that were centrally evaluated. Statistical evaluation comprised two parts: ROC analysis assessed accuracy of MRI and clinical diagnoses; furthermore rates of concordance of high- and low-field MRI diagnosis were calculated. RESULTS: We found no statistically relevant difference in high-field MRI diagnosis compared to low-field MRI diagnostic accuracy measured by clinical or surgical gold standard in three of the four regions examined; in cerebral examinations there was a small yet significant advantage for the high-field systems (P = 0.01). CONCLUSION: We conclude that the open low-field scanner we evaluated using clinical and surgical gold standard as reference is able to achieve comparable diagnostic accuracy compared to high-field scanners at lower costs and greater patient comfort. Limitations due to field strength (signal-to-noise ratio, resolution, scan time) seem to be relevant only in a very small number of cases that warrant high-field examination.

Adult↗

PubMed2003

Assessment of pleomorphic adenomas using MRI and dynamic contrast enhanced MRI.

We evaluated magnetic resonance images (MRI) and the value of dynamic contrast enhanced MRI (DCE-MRI) of pleomorphic adenomas retrospectively. MRI was performed for 18 pleomorphic adenomas, including 11 cases with DCE-MRI. We obtained the following results on the MRI and DCE-MRI. (a). Pleomorphic adenomas showed a predilection for homogeneous intermediate signal intensity on T1-weighted images (T1WI), heterogeneous high signal intensity on T2-weighted images, and heterogeneous enhancement on Gd-T1WI. (b). Of 11 contrast index (CI) curves of pleomorphic adenomas, nine CI curves (81.8%) increased gradually to 600 s or increased gradually, reached a plateau, and sustained the plateau to 600 s. The remaining two (18.2%) increased gradually and decreased gradually thereafter. (c). CI curves reached the maximum CI index at 135-300 s.

Adenoma, Pleomorphic↗

PubMed1999

[Diagnosis of magnetic resonance imaging (MRI) for blowout fracture--three advantages of MRI].

INTRODUCTION: Magnetic resonance imaging (MRI) gives a much more detailed picture of the soft tissue than computerized tomography (CT). In blowout fracture cases, it is very easy to observe the incarcerated orbital tissue. SUBJECTS: We performed MRI in 19 blowout fracture cases. RESULTS: After evaluating the images, we found three advantages of MRI. The first is that even small herniation of the orbital contents can easily be detected because the orbital fatty tissue contrasts well around the other tissues in MRI. The second is that the incarcerated tissues can be clearly differentiated because a clear contrast between the orbital fatty tissue and the extraocular muscle can be seen in MRI. The third is that the running images of the incarcerated muscle belly can be observed because any necessary directional slies can be taken in MRI. CONCLUSION: These advantages are very important in the diagnosis of blowout fractures. MRI should be employed in blowout fracture cases in addition to CT.

Adolescent↗

PubMedDate not supplied

19F-MRI of stomach and intestine using 50% FTPA emulsion under 2 T MRI system.

1H-MRI is of clinical value in many lesions, but imaging of gastrointestinal lesions is still difficult by 1H-MRI. To overcome this weak point of 1H-MRI, rabbit stomachs were examined by 19F-MRI using 50% FTPA emulsion. We also examined the stability of 50% FTPA emulsion in the stomach and its absorption from the gastrointestinal tract. We found that 50% FTPA emulsion was very stable at pH 1.5, and only a very small amount was absorbed. A rabbit (weighing 2 kg) was anesthetized, and 100 ml of 50% FTPA emulsion was infused into the stomach by catheter. 19F-MRI was performed in this rabbit using a 2 T superconducting MRI system designed for human use, and clear pictures of the stomach were obtained. From our results we conclude that 19F-MRI of the stomach using 50% FTPA emulsion is of practical value.

Animals↗

PubMed2003

MRI-guided SPECT perfusion measures and volumetric MRI in prodromal Alzheimer disease.

OBJECTIVE: To identify group differences in the prodromal phase of Alzheimer disease (AD) using quantitative single-photon emission computed tomography (SPECT) perfusion and magnetic resonance imaging (MRI) volume measures within specific volumes of interest. SETTING: Gerontology research unit. PARTICIPANTS: There were 17 healthy controls, 56 nondemented patients with memory problems who did not develop AD during 3 to 5 years of follow-up (questionables), and 27 nondemented patients with memory problems who developed AD during follow-up (converters). METHODS: A Tc 99m hexamethylpropyleneamine oxime SPECT study and an MRI were performed in each participant at baseline. Mean SPECT activity concentration and MRI volume were estimated within 9 structures: rostral anterior cingulate, caudal anterior cingulate, posterior cingulate, hippocampus, entorhinal cortex, basal forebrain, temporal horn, amygdala, and the banks of the superior temporal sulcus. Data were analyzed using overall and pairwise discriminant analysis, and performance in pairwise group discrimination was measured using correlated receiver operating characteristic curve analysis. RESULTS: The overall (3-group) discriminant function was significant for SPECT (F test, P<.001) and MRI (F test, P<.0001). For the SPECT analysis, the ranking of structures for discriminating among the 3 groups was, in order of decreasing discriminating power, caudal anterior cingulate, temporal horn, superior temporal sulcus, entorhinal cortex, hippocampus, rostral anterior cingulate, amygdala, basal forebrain, and posterior cingulate. For the MRI analysis, this ranking was entorhinal cortex, superior temporal sulcus, temporal horn, hippocampus, amygdala, caudal anterior cingulate, rostral anterior cingulate, basal forebrain, and posterior cingulate. Combining the 2 modalities yielded significantly better discrimination performance than did either alone. Furthermore, the correlation between SPECT and MRI measures was low. CONCLUSION: Measures of structure activity concentration and volume carry independent information; both reveal group differences in prodromal AD.

Aged↗

PubMed1996

MRI of encephalitis in children: comparison of CT and MRI in the acute stage with long-term follow-up.

We examined 14 children aged 28 days to 12.7 years with encephalitis by CT or MRI. Of the patients examined by CT 58% had a normal first scan, whereas all MRI investigations demonstrated abnormalities. The clinical features correlated with several MRI investigations. On MRI herpes (HSV) encephalitis started in the medial temporal lobe and encephalomalacia developed within a few weeks. All patients had a follow-up examination 0.5 to 6.5 years after the acute phase. MRI revealed abnormalities in 13 of the 14 children; one boy, with lesions in only the white matter, had a normal follow-up MRI. Even with immediate, optimal therapy the children demonstrated severe parenchymal abnormalities. Signal abnormalities seen in the acute phase of the disease were likely to persist. In children with HSV encephalitis atypical lesions in different areas were seen.

Acute Disease↗

PubMed2006

Implant detectibility of intervertebral disc spacers in post fusion MRI: evaluation of the MRI scan quality by using a scoring system--an in vitro study.

INTRODUCTION: Intervertebral spacers for anterior spine fusion are made of different materials, such as titanium and cobalt chromium alloys and carbon fiber-reinforced polymers. Implant-related susceptibility artifacts can decrease the quality of MRI scans. The aim of this cadaveric study was to demonstrate the extent that implant-related MRI artifacting affects the postfusion differentiation of determined regions of interest (ROIs). METHODS: In six cadaveric porcine spines, we evaluated the postimplantation MRI scans of a titanium, cobalt-chromium and carbon spacer that differed in shape and surface qualities. A spacer made of human cortical bone was used as a control. A defined evaluation unit was divided into ROIs to characterize the spinal canal as well as the intervertebral disc space. Considering 15 different MRI sequences read independently by an interobserver-validated team of specialists the artifact-affected image quality of the median MRI slice was rated on a score of 0-3. A maximum score of 18 points (100%) for the determined ROIs was possible. RESULTS: Turbo spin echo sequences produced the best scores for all spacers and the control. Only the control achieved a score of 100%. For the determined ROI maximum scores for the cobalt-chromium, titanium and carbon spacers were 24%, 32% and 84%, respectively. CONCLUSION: By using favored T1 TSE sequences the carbon spacer showed a clear advantage in postfusion spinal imaging. Independent of artifact dimensions, the scoring system used allowed us to create an implant-related ranking of MRI scan quality in reference to the bone control.

Alloys↗

PubMed1997

The value of MRI in early Perthes' disease: an MRI study with a 2-year follow-up.

Eleven hips in nine patients with Perthes' disease were studied by plain radiography at 3-month and MRI at 6-month intervals over a period of 2 years. The aim was to clarify the value of MRI in estimating epiphyseal involvement and in predicting uncoverage of the epiphysis. Signal intensities of the epiphysis and metaphysis were visually evaluated from T1- (T1W) and T2-weighted (T2W) images. The extent of decreased signal intensity (DSI) in the epiphyses was volumetrically calculated from T1W images and then compared with follow-up radiographs. The area of epiphyseal DSI corresponding best with Catterall's classification was seen by MRI 3-8 months after the first symptoms. MRI images obtained earlier usually showed less involvement than the follow-up radiographs. However, two features predicting extensive epiphyseal necrosis were: (1) DSI on both T1W and T2W images covering over two-thirds of the epiphysis and (2) diffuse bone marrow oedema of the femoral neck and metaphysis. When T1W images showed a reappearance of high signal intensity patches in the lateral quarter of the epiphysis, no clinically significant uncoverage was seen during the follow-up. Extensive epiphyseal necrosis can, therefore, sometimes be predicted by MRI even within the first 3 months, but MRI visualises epiphyseal involvement more clearly 3-8 months after the first symptoms.

Child↗

PubMed2001

MRI of the wrist and finger joints in inflammatory joint diseases at 1-year interval: MRI features to predict bone erosions.

The aim of this study was to assess the ability of MRI determined synovial volumes and bone marrow oedema to predict progressions in bone erosions after 1 year in patients with different types of inflammatory joint diseases. Eighty-four patients underwent MRI, laboratory and clinical examination at baseline and 1 year later. Magnetic resonance imaging of the wrist and finger joints was performed in 22 patients with rheumatoid arthritis less than 3 years (group 1) who fulfilled the American College of Rheumatology (ACR) criteria for rheumatoid arthritis, 18 patients with reactive arthritis or psoriatic arthritis (group 2), 22 patients with more than 3 years duration of rheumatoid arthritis, who fulfilled the ACR criteria for rheumatoid arthritis (group 3), and 20 patients with arthralgia (group 4). The volume of the synovial membrane was outlined manually before and after gadodiamide injection on the T1-weighted sequences in the finger joints. Bones with marrow oedema were summed up in the wrist and fingers on short-tau inversion recovery sequences. These MRI features was compared with the number of bone erosions 1 year later. The MR images were scored independently under masked conditions. The synovial volumes in the finger joints assessed on pre-contrast images was highly predictive of bone erosions 1 year later in patients with rheumatoid arthritis (groups 1 and 3). The strongest individual predictor of bone erosions at 1-year follow-up was bone marrow oedema, if present at the wrist at baseline. Bone erosions on baseline MRI were in few cases reversible at follow-up MRI. The total synovial volume in the finger joints, and the presence of bone oedema in the wrist bones, seems to be predictive for the number of bone erosions 1 year later and may be used in screening. The importance of very early bone changes on MRI and the importance of the reversibility of these findings remain to be clarified.

Arthritis, Psoriatic↗

PubMed2004

Quality assurance of clinical MRI scanners using ACR MRI phantom: preliminary results.

Clinical magnetic resonance imaging (MRI) scanners play an important role in the diagnosis of diseases and management of patient treatment. Quality assurance (QA) of the clinical MRI scanners is mandatory to obtain optimal images in a modern hospital. In this report, the phantom test for the American College of Radiology (ACR) MRI accreditation is used as the essential part of the MRI QA protocols. Seven important assessments of MR image quality are included as follows: geometric accuracy, high-contrast resolution, slice thickness accuracy, slice position accuracy, image intensity uniformity, percent signal ghosting, and low-contrast object detectability. In addition, signal-to-noise ratio and central frequency are monitored as well. The MRI QA procedures were applied to four clinical MRI scanners in our institute twice within 3 months. According to the QA results, the service engineers were more efficient in solving scanners problems when the ACR phantom test was run.

Humans↗

PubMed2001

Effect of vasodilator hydralazine on tumor microvascular random flow and blood volume as measured by intravoxel incoherent motion (IVIM) weighted MRI in conjunction with Gd-DTPA-Albumin enhanced MRI.

We studied the effect of hydralazine on tumor blood volume fraction and microvascular random flow velocity magnitude by IVIM weighted MRI in conjunction with dynamic Gd-DTPA-Albumin enhanced MRI. Blood volume fraction maps were obtained from the dynamic Gd-DTPA-Albumin enhanced MRI measurements. The average blood volume fraction of R3230 AC adenocarcinoma decreased from 0.125 +/- 0.022 (s.d.) ml/g to 0.105 +/- 0.018 (s.d.) ml/g (p < 0.001) after the administration of hydralazine at a dose of 5 mg/kg. The microvascular random flow velocity magnitude maps were obtained from the IVIM weighted MRI signals by utilizing the Gd-DTPA-Albumin measured blood volume fractions as an input in the compartmental modeling analysis of the IVIM weighted MRI signal. The random-directional microvascular flow induced MRI signal attenuation was separated from the molecular diffusion induced signal attenuation. Flow induced attenuation was more significant after the administration of hydralazine. The mean microvascular random flow velocity magnitude increased from 0.52 +/- 0.15 (s.d.) mm/sec to 0.73 +/- 0.23 (s.d.) mm/sec (p < 0.05) in the presence of the above blood volume fraction change.

Adenocarcinoma↗

PubMed1994

Magnetic resonance imaging (MRI) and arthroscopy in the detection of meniscal degenerations: correlation of arthroscopy and MRI with histology findings.

In a prospective double-blind study, the capability of magnetic resonance imaging (MRI) and arthroscopy in the detection and grading of meniscal degenerations is evaluated by correlating MRI findings and arthroscopic diagnoses with a histologic grading model. In 82.8% of our results, grading based on MRI studies corresponded with the histologic grading classification. In 12 instances a meniscal degeneration verified at light microscopy was not detected at MRI, whereas in 15 cases tomography yielded a false-positive result. The overall accuracy was calculated to be 0.93 with a specificity of 0.79 and a sensitivity of 0.96. Concerning the evaluation of meniscal degenerations, MRI provides a positive predictive value of 0.95 and a negative predictive value of 0.82. Compared with the diagnostic specificity of the anterior and posterior zones, that of the intermediate segment of the meniscus is significantly reduced (p < 0.001). At arthroscopy, meniscal degenerations were diagnosed with an overall accuracy of 38.8%, a sensitivity of 27.5%, and a specificity of 75.5%. In 80 cases of grade 3 abnormalities, five false-negative diagnoses were made initially. These results suggest that MRI offers a valuable diagnostic potential providing reliable information about the internal consistency of the meniscus complementary to diagnostic arthroscopy.

Adult↗

PubMed2001

Co-registration of EEG and MRI data using matching of spline interpolated and MRI-segmented reconstructions of the scalp surface.

Accurate co-registration of MRI and EEG data is indispensable for the correct interpretation of EEG maps or source localizations in relation to brain anatomy derived from MRI. In this study, a method for the co-registration of EEG and MRI data is presented. The method consists of an iterative matching of EEG-electrode based reconstructions of the scalp surface to scalp-segmented MRIs. EEG-electrode based surface reconstruction is achieved via spline interpolation of individually digitized 3D-electrode coordinates. In contrast to other approaches, neither fiducial determination nor any additional provisions (such as bite bars, other co-registration devices or head shape digitization) are required, and co-registration errors associated with inaccurate fiducial determination are avoided. The accuracy of the method was estimated by calculating the root-mean-square (RMS) deviation of spline interpolated and MRI-segmented surface reconstructions in 20 subjects. In addition, the distance between co-registered and genuine electrode coordinates was assessed via a simulation study, in which surface reconstruction was based on virtual electrodes determined on the scalp surface of a high-resolution MRI data set. The mean RMS deviation of surface reconstructions was 2.43 mm, and the maximal distance between any two matched surface points was 5.06 mm. The simulated co-registration revealed a mean deviation of genuine and co-registered electrode coordinates of 0.61 mm. It is concluded that surface matching using spline interpolated reconstructions of scalp surfaces is a precise and highly practicable method to co-register EEG and MRI data.

Adult↗

PubMed2000

MRI findings in haemophilic joints treated with radiosynoviorthesis with development of an MRI scale of joint damage.

We hypothesized that magnetic resonance imaging (MRI) scans taken prior to radiosynoviorthesis may be predictive of response to the procedure in persons with haemophilia. Specifically, response would be inversely related to the severity of synovial hyperplasia. Radiosynoviorthesis was administered to 21 joints with recurrent haemorrhage (target joints). A detailed self-report of haemorrhage history, joint evaluation with scoring according to the World Federation of Haemophilia orthopaedic joint and pain scales, plain radiographs, and MRI studies of the joints were performed pre- and post-radiosynoviorthesis. To augment comparison of the MRI findings to those assessed using the Arnold-Hilgartner and Pettersson scales, a provisional MRI scale for evaluation of haemophilic arthropathy was designed. We found the MRI findings prior to the procedure were not predictive of clinical response; independent of the severity of synovial hyperplasia, most joints bled less and showed improvement by the WFH orthopaedic score. There was generally no change in the severity of synovial hyperplasia after the procedure. We conclude that MRI evaluation is not routinely indicated prior to radiosynoviorthesis.

Adolescent↗

PubMedDate not supplied

Diagnostic potential of ultrafast contrast-enhanced MRI of the breast in hypervascularized lesions: are there advantages in comparison with standard dynamic MRI?

PURPOSE: Our goal was to evaluate possible diagnostic advantages of ultrafast MRI of the breast in comparison with dynamic MRI. METHOD: Thirty patients with 35 hypervascularized lesions were selected prospectively after undergoing standard dynamic MRI (temporal resolution 87 s). Patients underwent additional ultrafast imaging (temporal resolution 2 s). Onset, rate, and pattern of enhancement were analyzed. RESULTS: Histopathology revealed 15 malignant and 20 benign lesions (3-40 mm). Enhancement pattern was centripetal in 2 benign and 4 malignant lesions, centrifugal in 5 and 3, and homogeneous in 13 and 8. The onset of lesion enhancement ranged from 3 to 13 s (parenchymal enhancement 4-14 s) and the rate of enhancement from 3 to 70%/s, both without any correlation to the histologic diagnosis. There was no significant difference between ultrafast and standard dynamic MRI. CONCLUSION: Ultrafast MRI does not provide additional information in comparison with standard dynamic MRI.

Adolescent↗

PubMed2005

Reliability of progressive and additive MRI scoring systems for evaluation of haemophilic arthropathy in children: expert MRI Working Group of the International Prophylaxis Study Group.

Effective treatment of haemophilic arthropathy requires a detailed evaluation of joint integrity. Methodological assessment of magnetic resonance imaging (MRI) scores are needed to assure reproducibility of measurements when comparing results of clinical trials conducted in different centres. We compared the reliability of two MRI scoring systems for assessment of haemophilic arthropathy: one progressive system that displays the most severe change and one additive system that depicts osteochondral and soft tissue-related changes. A total of 47 1.5 T MRI examinations of knees (n = 21) and ankles (n = 26) of 42 haemophilic boys, age range, 22 months to 18 years, performed at different centres (Toronto, n = 20, Europe, n = 12 and Denver, n = 15) were independently reviewed by four radiologists at two occasions. Twenty-two examinations were from children <9 years and 25 from children >/=9. Sagittal and coronal gradient-echo (MPGR, 3D FLASH with fat saturation, GRASS) images were obtained. The MRI examinations of the ankle and knee studies presented with osteochondral abnormalities in 38.5% and 23.8% of the cases respectively. The two scoring systems demonstrated an excellent inter-reader [progressive, 0.88; additive (A, e, s and h components), 0.86] and intra-reader [progressive, 0.92; additive (A, e, s and h components), 0.93] reliability using intraclass correlation coefficients (ICCs). Although ICCs were slightly higher for knees when compared with ankles, and for older children when compared with younger children, all values fell within excellent inter- and intra-reader reliability categories. The two MRI scoring systems demonstrated a comparable reliability. This result constitutes the basis for further development of a combined MRI scoring system for assessment of haemophilic arthropathy, which incorporates progressive and additive components.

Adolescent↗

PubMed2006

Practice MRI: reducing the need for sedation and general anaesthesia in children undergoing MRI.

The aim of this study was to evaluate the effectiveness of a practice magnetic resonance unit, in preparing children to undergo magnetic resonance procedures without general anaesthesia (GA) or sedation. The records of children who attended the practice MRI between February 2002 and April 2004 were retrospectively reviewed. Each record was assessed as to whether the child had passed or failed the practice MRI intervention. Those children who were considered to have passed and were proceeded to a clinical non-GA MRI had the report of the clinical scan reviewed. If the scan had been reported as non-diagnostic because of movement artefact it was classified as a failed scan, otherwise it was considered a pass. One hundred and thirty-four children undertook a practice MRI (age range 4.1-16.1 years, median age 7.7 years, 47% boys) and 120/134 (90%) passed the practice session. In all, 117/120 (98%) subsequently had a clinical non-GA MRI and 110/117 (94%) passed (median age 7.8 years, 47% boys). Preparation is a safe and effective method to reduce the need for sedation and GA in children undergoing a clinical MRI scan. It provides a positive medical experience for children, parents and staff, and results in cost savings for the hospital.

Adolescent↗

PubMed1997

Gadolinium enhanced MRI predicts clinical and MRI disease activity in relapsing-remitting multiple sclerosis.

The aim of the study was to evaluate the predictive power of baseline gadolinium (Gd) enhanced MRI in relation to subsequent clinical and MRI activity. Sixty eight patients with clinically definite relapsing-remitting multiple sclerosis had a baseline Gd enhanced MRI and were followed up clinically and by monthly Gd enhanced MRI for six months. The occurrence of relapses during the follow up period was predicted by the presence of at least one enhancing lesion on the baseline MRI (P < 0.05). The number and volume of enhancing lesions at baseline were significantly associated with both enhancing lesions observed during the follow up period (P < 0.0001) and the accumulation of abnormality on T2 weighted images (P < 0.0001). Moreover, the presence of three or more enhancing lesions at baseline scan was consistently associated with the development of permanent abnormalities on T2 weighted images six months later. The study suggests that the number and volume of Gd enhancing lesions at a single examination are strong short term predictors of subsequent clinical and MRI activity.

Adult↗