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At least 145 records · Page 8Linked to original sources
PubMed2006

Does high-field MR imaging have an influence on the classification of patients with clinically isolated syndromes according to current diagnostic mr imaging criteria for multiple sclerosis?

BACKGROUND AND PURPOSE: Current MR imaging criteria for multiple sclerosis (MS) do not specify the magnetic field strength. The aim of this study was to investigate whether different MR imaging field strengths, specifically high-field MR imaging, have an impact on the classification of patients with clinically isolated syndromes suggestive of MS, according to MR imaging and diagnostic criteria. METHODS: In a prospective intraindividual comparative study, we examined 40 patients with clinically isolated syndromes (CIS) consecutively with a 1.5 T and 3T MR imaging system, including axial sections of T2 turbo spin-echo, fluid-attenuated inversion recovery, and T1 spin-echo, before and after injection of gadolinium-diethylene-triaminepentaacetic acid. Constant resolution parameters were used for both field strengths. High-signal-intensity white matter lesions with a size of >3 mm were counted and categorized according to their anatomic location in infratentorial, callosal, juxtacortical, periventricular, and other white matter areas. Assessment of the fulfilled Barkhof MR imaging and McDonald diagnostic criteria was made separately for both field strengths in every patient. RESULTS: Eleven patients fulfilled more MR imaging criteria at 3T. Two of these patients fulfilled the criterion of dissemination in space (DIS) according to the first definition of McDonald criteria, which is based on imaging criteria alone. Another patient had DIS only at 3T, according to the second definition of the McDonald criteria including CSF parameters. CONCLUSION: MR field strength, specifically high-field MR imaging, has a substantial influence on the classification of patients with CIS according to imaging and a mild influence on the classification according diagnostic criteria for MS, leading to consequences for prognostic classification, imaging guidelines, and clinical trials.

Adolescent↗
PubMed1995

Altered vertebrobasilar flow in children: angiographic, MR, and MR angiographic findings.

PURPOSE: To characterize the clinical, MR, MR angiographic, and conventional angiographic findings in vertebrobasilar disease in children. METHODS: Eight children with posterior circulation ischemia and infarction had conventional spin-echo MR and MR angiography of the head and neck. Six patients had conventional angiography. RESULTS: Six patients had alteration of vertebral or basilar artery flow void on spin-echo images. MR angiography showed all six cases of angiographically proved vertebrobasilar dissection or occlusion despite overestimating the extent of arterial abnormality in two patients. In two patients the intracranial peripheral branch cutoff shown at angiography was correctly predicted on screening MR angiography. CONCLUSION: Posterior circulation infarction in children is usually secondary to traumatic injury to the vertebrobasilar circulation. MR and MR angiography noninvasively show vertebrobasilar flow disturbances and compare favorably with angiography in documenting dissection or occlusion of the vertebrobasilar circulation. MR angiography may obviate the need for invasive angiography in these children at diagnosis and during follow-up of anticoagulation therapy.

Adolescent↗
PubMed1993

Target delineation in radiosurgery for cerebral arteriovenous malformations. Assessment of the value of stereotaxic MR imaging and MR angiography.

A study of 6 selected arteriovenous malformation (AVM) patients was performed to investigate the feasibility of delineating an AVM on MR images and to compare the AVM volume outlined on different images. Conventional stereotaxic angiograms, stereotaxic MR images and MR angiograms using several different pulse sequences were obtained prior to radiosurgery. Treatment plans were made from the conventional stereotaxic angiograms. These plans were then transferred to a separate dose planning computer which displayed the MR images with the superimposed isodose lines. The radiated volumes of AVM and brain tissue were measured from these MR images. Last, an assessment was made of the radiation volume needed for an appropriate treatment of the AVM if the treatment plan was made from the MR images rather than from the conventional stereotaxic angiogram. It was possible to delineate medium and large size AVM nidi on stereotaxic MR images based on an integration of information obtained from various pulse sequences. The estimated volumes of the AVM nidi were found to be larger on the conventional stereotaxic angiograms than on the stereotaxic MR images. Consequently, a dose plan based on a conventional stereotaxic angiogram would result in a higher integral dose to the brain with the same target dose. By using reliable MR information it is expected that the volume of brain exposed to radiation could be decreased and the adverse effects of stereotactic radiosurgery for AVM thereby minimized.

Adult↗
PubMed1992

Comparative distribution of messenger RNAs encoding glutamic acid decarboxylases (Mr 65,000 and Mr 67,000) in the basal ganglia of the rat.

Glutamic acid decarboxylase, the enzyme required for GABA synthesis, exists as distinct isoforms, which have recently been found to be encoded by different genes. The relative expression of messenger RNAs encoding two isoforms of glutamic acid decarboxylase (Mr 67,000 and Mr 65,000) was measured at the single-cell level in neurons of the rat basal ganglia with in situ hybridization histochemistry. Both messenger RNAs were expressed in neurons of the striatum, pallidum, and substantia nigra pars reticulata, but marked differences in the relative level of labelling were observed with the two probes. In striatum, efferent neurons were more densely labelled for the messenger RNA encoding glutamic acid decarboxylase (Mr 65,000) than for the messenger RNA encoding glutamic acid decarboxylase (Mr 67,000), whereas the reverse was observed for GABA-ergic interneurons. Neurons of the entopeduncular nucleus were much more densely labelled for messenger RNA encoding glutamic acid decarboxylase (Mr 65,000) than for messenger RNA encoding glutamic acid decarboxylase (Mr 67,000). In addition, labelling for messenger RNA encoding glutamic acid decarboxylase (Mr 65,000) was higher in the entopeduncular nucleus (internal pallidum) than in the globus pallidus (external pallidum), a structure which expressed similar levels of both mRNAs. In contrast to neurons of the internal pallidum, efferent neurons of the substantia nigra pars reticulata expressed slightly more messenger RNA encoding glutamic acid decarboxylase (Mr 67,000) than that encoding the other isoform of the enzyme. The results suggest a differential expression of the messenger RNAs encoding the two isoforms of glutamic acid decarboxylase in subpopulations of basal ganglia neurons in rats.

Animals↗
PubMedDate not supplied

MR-Guided PTA in experimental bilateral rabbit renal artery stenosis and MR angiography follow-up versus histomorphometry.

PURPOSE: To assess in vivo 1) MR-guided percutaneous transluminal renal angioplasty (PTRA) in experimental bilateral rabbit renal artery stenosis (RAS); 2) postprocedural follow-up by gadolinium-enhanced MR angiography versus histomorphometry. METHODS: Fifteen male NZW rabbits of mean weight 4.0 kg (range 3.5-4.2 kg) underwent bilateral RAS induction by combined overdilation-deendothelialization with a gadolinium-filled balloon, passively MR-guided by the artifact of a 0.014-inch guidewire. After 4 weeks the rabbits were randomized into two groups: group A (n = 8) underwent right-sided PTRA for treatment of RAS, group B (n = 7) underwent left-sided PTRA. After another 4 weeks the rabbits were killed to assess by histomorphometry recurrent stenosis and contralateral induction injury stenosis lesions. Each step was preceded by gadolinium-enhanced three-dimensional MR angiography, and the cortex-to-aorta (C/A) signal intensity ratio was calculated. RESULTS: RAS induction was successful in all cases. Fourteen arteries developed restenosis and 13 only initial stenosis. MR-guided PTRAs were feasible in 22 arteries (73%). For a successful catheterization of the ostium (20 arteries, 66% success rate), 10-25 steps were required. Five to eight steps were required for balloon localization and inflation for each PTRA. The restenosis effect was reflected by a 16% (12%-27%) decrease in C/A values on MR angiograms (p < 0.05). CONCLUSION: MR guidance and MR angiography represent a feasible, less invasive alternative for performing and assessing experimental PTRA in RAS.

Angioplasty, Balloon↗
PubMed2002

Coarctation of the aorta: comparison of aortic dimensions between conventional MR imaging, 3D MR angiography, and conventional angiography.

Magnetic resonance angiography is increasingly used as a non-invasive method in the evaluation of coarctation of the aorta. The aim of this study was to compare aortic dimensions calculated by MR angiography and those obtained by more conventional MR sequences and conventional angiography. Twenty-six consecutive patients with coarctation underwent three-dimensional MR angiography. Two independent observers retrospectively evaluated three aortic segments, site of coarctation, presence of aneurysm and existence of collateral circulation. Three aortic segments were also compared with those obtained on classical MR sequences and conventional angiography. The MR angiography was successfully performed in all showing 1 aneurysm and collateral circulation in 8 patients. Almost perfect intraobserver ( r(2)>0.91) and excellent interobserver ( r(2)>0.80) reliabilities were obtained for each aortic segment no matter which MR sequence was employed. Similarly, mainly excellent ( r(2)>0.80) concordance analysis was observed between MR angiography measurements and those calculated by either spin-echo/gradient-echo sequences or conventional angiography. This study demonstrates that MR angiography is a fast, accurate and reproducible method in the evaluation of coarctation of the aorta. It provides excellent anatomic information and reliably detects collateral vessels. Magnetic resonance angiography could probably replace the conventional angiography and will provide an additional diagnostic value in combination with turbo spin-echo sequence.

Adolescent↗
PubMed1986

Conversion of human placental alkaline phosphatase from a high Mr form to a low Mr form during butanol extraction. An investigation of the role of endogenous phosphoinositide-specific phospholipases.

Alkaline phosphatase in a wide range of tissues has been shown to be anchored in the membrane by a specific interaction with the polar head group of phosphatidylinositol. It has previously been suggested that the production of low Mr alkaline phosphatase during the commonly used butanol extraction procedure may result from the activation of an endogenous phosphoinositide-specific phospholipase C which removes the 1,2-diacylglycerol responsible for membrane anchoring. This conversion process was investigated in greater detail with human placenta used as the source of alkaline phosphatase. Mr and hydrophobicity of the alkaline phosphatase were determined by gel filtration on TSK-250 and partitioning in Triton X-114, respectively. Alkaline phosphatase extracted from human placental particulate fraction with butanol at pH 5.4 or released by incubation with Staphylococcus aureus phosphatidylinositol-specific phospholipase C produced a form of alkaline phosphatase of Mr approx. 170,000 and relatively low hydrophobicity. By contrast, the butanol extract prepared at pH 8.3 was an aggregated form of Mr approx. 600,000 and was relatively hydrophobic. The effect of a variety of inhibitors and activators on the amount of low Mr alkaline phosphatase produced during butanol extraction revealed that it was a Ca2+- and thiol-dependent process. Proteinase inhibitors had no effect. [3H]Phosphatidylinositol hydrolysis by the particulate fraction, unlike low Mr alkaline phosphatase production, was relatively sensitive to heat inactivation, indicating that the phosphoinositide-specific phospholipases C from cytosol and lysosomes were unlikely to be responsible for conversion. A butanol-stimulated activity which removed the [3H]myristic acid from the variant surface glycoprotein ( [3H]mfVSG) of Trypanosoma brucei was detectable in the human placental particulate fraction. Since this activity was acid active, Ca2+- and thiol-dependent and relatively heat stable, it may be the same as that responsible for production of low Mr alkaline phosphatase. The only 3H-labelled product identified was phosphatidic acid, suggesting that the [3H]mfVSG-cleaving activity is a phospholipase D. These data strongly support the proposal that production of low Mr alkaline phosphatase during butanol extraction is an autolytic process occurring as the result of an endogenous phospholipase. However, they also suggest that the lysosomal and cytosolic phosphoinositide-specific phospholipases C that have previously been described in many mammalian tissues are not responsible for this process.

1-Butanol↗
PubMed2003

Portal cavernoma-associated cholangiopathy: a clinical and MR cholangiography coupled with MR portography imaging study.

Although biliary symptoms appear to be uncommon in patients with portal cavernoma, almost all of them have endoscopic retrograde cholangiographic abnormalities. The mechanisms underlying the biliary changes are explained poorly. This study in patients with portal cavernoma had 3 aims: (1) to assess the manifestations related to biliary involvement; (2) to evaluate with magnetic resonance (MR) imaging the aspect and frequency of cholangiographic changes; and (3) to clarify the mechanisms underlying biliary involvement. From December 1999 to July 2001, 25 consecutive adults with portal cavernoma without cancer or cirrhosis were studied with MR cholangiography coupled with MR portography. Seven patients presented with clinical manifestations of biliary disease. MR cholangiography findings were stenosis in 21 patients, with upstream dilatation in 16 and displacement in 13. MR cholangiography coupled with MR portography showed in all cases that the biliary abnormalities were secondary to a mass effect directly related to pressure by the cavernoma. In conclusion, in patients with portal cavernoma, clinical manifestations of biliary disease are most frequent; the cholangiographic abnormalities are very common and usually are caused by a mass effect by pressure from the veins composing the cavernoma. MR cholangiography coupled with MR portography is an effective noninvasive examination for simultaneous visualization of bile ducts and their relationship to the cavernoma.

Bile Duct Diseases↗
PubMed2002

Real-time-MR guidance for placement of a self-made fully MR-compatible atrial septal occluder: in vitro test.

PURPOSE: This in vitro study investigated the feasibility to visualize the placement of three different atrial septal occluder systems using real-time MR control. METHODS: The experiments were performed on an interventional 1.5 T high field whole body system. Real-time MR imaging was achieved by radial or spiral k-space filling in conjunction with the sliding window reconstruction technique yielding an imaging speed of 15 frames per second. The CardioSeal, Amplatzer Septal Occluder and a specially designed MR-compatible closure device were tested in a water bath. A punctured plastic wall served as model for the atrial septal defect. RESULTS: The delivery systems of the CardioSeal and Amplatzer Occluder were ferromagnetic and caused substantial artifacts, making the device placement impossible, even if the magnetic forces would have been acceptable. The self-made prototype caused only minor susceptibility artifacts allowing its visualization on the MR images. The MR imaging techniques applied enabled real-time control of the occluder including steering through the artificial septal foramen and visualization of the occluder deployment. CONCLUSION: Real-time MR imaging allows for guidance and placement of an MR-compatible septal occluder in vitro suggesting the feasibility to perform atrial septal occlusion under MR-guidance in vivo as well.

Heart Atria↗
PubMed2004

[Functional-anatomic evaluation of dilated uropathies in children using combined MR-nephrography and MR-urography compared to renal scintigraphy].

PURPOSE: To evaluate MR-tomographic assessment of split renal function and degree of obstruction compared to diuretic renal scintigraphy, and pathoanatomic imaging of the urinary tract as all in one exam. PATIENTS AND METHODS: In a prospective study 62 children, aged 1 month to 9.5 years, mean 2.8 years, underwent diuretic renal scintigraphy and dynamic MR-Nephrography at the same day except for 7 patients with a time interval of 1 day. In all patients we did T2w (water-technique MR-Urography) additionally. RESULTS: Comparing split renal function we found a very close correlation in 54 out of 62 patients (correlation coefficient = 0.95). Due to technical failures 8 cases couldn't be calculated. Comparing degrees of obstruction there was an agreement in 57 out of 62 patients, 3 studies were gradually over-, 2 underestimated. All but one morphologic diagnoses in advance obtained by ultrasound and completed by other imaging modalities later on were confirmed MR-urographically. Though correctly imaged the functionless upper moiety in a renal duplication with ureterocele was misinterpreted at a first glance. CONCLUSIONS: Combined MR-Nephrography and MR- Urography allows reliable assessment of split renal function and urinary excretion in children with obstructive uropathies compared to renal scintigraphy. T(2)w MR-Urography provides excellent depiction of dilated urinary tract. In near future MR-tomographic techniques will reduce or even replace scintigraphic and radiographic modalities in patients with urinary tract anomalies.

Child↗
PubMed1997

Diagnosis of liver metastases from colorectal adenocarcinoma. Comparison of spiral-CTAP combined with intravenous contrast-enhanced spiral-CT and SPIO-enhanced MR combined with plain MR imaging.

PURPOSE: The purpose of this study was to determine whether MR with and without SPIO (AMI-25) could replace spiral-CTAP in the staging of colorectal adenocarcinoma. MATERIAL AND METHODS: Thirty-five patients were studied prospectively by means of i.v. contrast-enhanced spiral-CT, spiral-CTAP, and MR of the liver. MR imaging was performed before and after infusion of AMI-25. Diagnoses were compared to intraoperative findings (n = 35) which included intraoperative ultrasound (n = 21), and follow-up CT (n = 18). RESULTS AND CONCLUSION: Fifteen patients were found to have a total number of 53 liver metastases and 43 benign lesions were detected. Evaluation was performed in four different ways: 1) i.v. contrast-enhanced spiral-CT; 2) i.v. contrast-enhanced spiral-CT + spiral-CTAP; 3) plain MR; 4) plain MR + SPIO-enhanced MR. I.v. contrast-enhanced spiral-CT, spiral-CTAP and SPIO-enhanced MR identified patients with liver metastases with equal sensitivity. However, owing to its significantly higher sensitivity, based on a lesion-by-lesion analysis, spiral-CTAP cannot be replaced by SPIO-enhanced MR in patients who are to undergo liver resection. A limitation in spiral-CTAP is its relatively low specificity.

Adenocarcinoma↗
PubMed2004

Assessment of myocardial function with interactive non-breath-hold real-time MR imaging: comparison with echocardiography and breath-hold Cine MR imaging.

PURPOSE: To compare a spiral gradient-echo sequence with a radial steady-state free precession sequence and to compare these two interactive real-time cardiac magnetic resonance (MR) imaging examinations with harmonic two-dimensional echocardiography (ECHO) for the evaluation of regional myocardial function. MATERIALS AND METHODS: Electrocardiographically triggered breath-hold steady-state free precession (BH-SSFP) MR imaging was the reference standard. Thirty-five nonselected patients scheduled for routine ECHO were included. Data from corresponding two-, three-, and four-chamber long-axis views and a midventricular short-axis view were acquired with each modality. Image quality and depiction of segmental wall motion were scored semiquantitatively by using the 16-segment model of the American Society of Echocardiography. Repeated-measures analysis of variance was performed to assess differences in image quality and wall motion depiction scores among the four imaging methods. Agreement was assessed by using Cohen kappa statistics. RESULTS: Compared with the image quality achieved with BH-SSFP MR imaging, the image quality achieved with radial MR imaging was similar (nonsignificant difference), but that achieved with spiral MR imaging and ECHO was significantly inferior (P <.0001). There were no significant differences in the image quality of the long- and short-axis views between the radial and BH-SSFP sequences, while the image quality of the long-axis spiral (P <.05) and the short- and long-axis ECHO (P <.0001) views was lower than that of the BH-SSFP views. Compared with the mean wall motion score for BH-SSFP MR imaging, the mean wall motion score for radial MR imaging was not significantly different, but those for ECHO (P <.05) and spiral MR imaging (P =.0003) were significantly lower. Cohen kappa coefficients for agreement with the BH-SSFP sequence regarding wall motion scoring were 0.47 for ECHO, 0.67 for the spiral sequence, and 0.89 for the radial sequence. CONCLUSION: The radial sequence enables similar accurate assessment of regional wall motion compared with the BH-SSFP sequence and yields image quality that is superior to that yielded by the spiral sequence and ECHO.

Adult↗
PubMed2004

MR imaging-guided prostate biopsy with a closed MR unit at 1.5 T: initial results.

The authors evaluated a magnetic resonance (MR) imaging-compatible biopsy device comprising a needle guide that can be visualized with MR imaging and manipulated mechanically from outside the MR unit. With approval from the local ethics committee and patient consent, this device was tested in 12 patients by using a closed 1.5-T MR unit and a body phased-array coil. Patients had elevated prostate-specific antigen levels (6-60 ng/mL) and one or more areas in the prostate that were suspicious for carcinoma at prebiopsy MR imaging. Biopsy was performed with transrectal access and with the patient prone. A 16-gauge MR imaging-compatible needle was successfully positioned with the device, and between six and nine tissue cores were obtained in each patient. In one patient, two suspicious basal areas could not be reached with the device. Histologic analysis showed prostate cancer in five patients and prostatitis in six. No complications were observed. The device enabled MR imaging-guided core-needle biopsy of prostate areas suspicious for cancer on MR images.

Aged↗
PubMed2005

Adding in vivo quantitative 1H MR spectroscopy to improve diagnostic accuracy of breast MR imaging: preliminary results of observer performance study at 4.0 T.

PURPOSE: To determine whether the addition of in vivo quantitative hydrogen 1 (1H) magnetic resonance (MR) spectroscopy can improve the radiologist's diagnostic accuracy in interpreting breast MR images to distinguish benign from malignant lesions. MATERIALS AND METHODS: The study was approved by the institutional review board and, where appropriate, was compliant with the Health Insurance Portability and Accountability Act. All patients provided written informed consent. Fifty-five breast MR imaging cases-one lesion each in 55 patients aged 24-66 years with biopsy-confirmed findings-were retrospectively evaluated by four radiologists. Patients were examined with contrast material-enhanced fat-suppressed T1-weighted 4.0-T MR imaging. The concentration of total choline-containing compounds (tCho) was quantified by using single-voxel 1H MR spectroscopy. For each case, the radiologists were asked to give the percentage probability of malignancy, the Breast Imaging and Reporting Data System category, and a recommendation for patient treatment. Two interpretations were performed for each case: The initial interpretation was based on the lesion's morphologic features and time-signal intensity curve, and the second interpretation was based on the lesion's morphologic features, time-signal intensity curve, and tCho concentration. Receiver operating characteristic (ROC), Wilcoxon signed rank, kappa statistic, and accuracy (based on the area under the ROC curve) analyses were performed. RESULTS: Of the 55 lesions evaluated, 35 were invasive carcinomas and 20 were benign. The addition of 1H MR spectroscopy resulted in higher sensitivity, specificity, accuracy, and interobserver agreement for all four radiologists. More specifically, two of the four radiologists achieved a significant improvement in sensitivity (P=.03, P=.03), and all four radiologists achieved a significant improvement in accuracy (P = .01, P = .05, P = .009, P < .001). CONCLUSION: Current study results suggest that the addition of quantitative 1H MR spectroscopy to the breast MR imaging examination may help to improve the radiologist's ability to distinguish benign from malignant breast lesions.

Adolescent↗
PubMed1993

Acute stroke in cats: comparison of dynamic susceptibility-contrast MR imaging with T2- and diffusion-weighted MR imaging.

PURPOSE: To evaluate the hemodynamics of acute stroke in cats by means of dynamic susceptibility-contrast magnetic resonance (MR) imaging compared with standard T2- and diffusion-weighted MR imaging. MATERIALS AND METHODS: Unilateral permanent occlusion of the middle cerebral artery was performed in 18 cats. MR imaging was performed with each method 2 hours (n = 2), 6 hours (n = 10), and 24 hours (n = 11) after occlusion. RESULTS: At every time point, dynamic MR images clearly showed ischemic regions of steady-state signal hyperintensity and areas of less dynamic decrease in signal intensity that corresponded closely to those seen on diffusion-weighted MR images. T2-weighted MR images did not reveal regions of high signal intensity 2 hours after occlusion. The measurements of relative blood volume obtained with the dynamic method were significantly lower in steady-state hyperintense ischemic areas of the affected side than those in the contralateral normal areas at 6 and 24 hours (P < .001). CONCLUSION: This dynamic method can advance the time of detection of early ischemia in comparison with T2-weighted MR imaging and provides functional information about hemodynamics not provided by other methods of MR imaging.

Acute Disease↗
PubMed1994

Posterosuperior glenoid impingement of the shoulder: findings at MR imaging and MR arthrography with arthroscopic correlation.

PURPOSE: To determine the utility of magnetic resonance (MR) imaging and MR arthrography in the evaluation of arthroscopic findings of posterosuperior glenoid impingement. MATERIALS AND METHODS: The findings at MR imaging, MR arthrography, and physical examination with the patient under anesthesia were retrospectively reviewed in eight patients with arthroscopic evidence of posterosuperior glenoid impingement. RESULTS: All patients had shoulder pain; anterior instability was found in six patients. Other than bone marrow abnormalities, findings at MR imaging were not reliable for the detection of posterosuperior glenoid impingement. MR arthrography was superior to routine MR imaging in all four cases in which it was done; positioning the shoulder in abduction and external rotation was beneficial in three of four patients. CONCLUSION: Impingement of the rotator cuff on the posterior superior glenoid labrum is a cause of posterior shoulder pain in athletes who throw. MR arthrography may allow detection of abnormalities associated with this clinical entity.

Adolescent↗
PubMed1990

MR arthrography of the shoulder: comparison with conventional MR imaging.

Twenty-three patients underwent both conventional MR imaging of the shoulder and MR shoulder arthrography for clinically suspected labral or rotator cuff abnormalities. Images obtained before and after contrast administration were studied independently, and without knowledge of clinical findings, by two radiologists for the presence of abnormalities of the glenoid labrum or rotator cuff. Results were correlated with surgical findings in all patients. Nine patients had surgically proved labral tears. MR arthrography detected all nine labral abnormalities, while six of the nine were missed on conventional MR imaging. Fourteen patients had surgically proved rotator cuff tears. MR arthrography detected 11 of the 14 tears and missed three partial tears on the bursal surface. Conventional MR imaging detected nine cuff tears and missed five tears; two of these were complete rotator cuff tears and three were partial tears of the undersurface of the rotator cuff. Our results suggest that MR arthrography enhances the accuracy of MR in the evaluation of the glenoid labrum and rotator cuff tendon.

Adolescent↗
PubMed1994

Metallic foreign bodies in the orbits of patients undergoing MR imaging: prevalence and value of radiography and CT before MR.

OBJECTIVE: The purpose of this study was to measure the prevalence of metallic foreign bodies in the orbits of 15,024 patients who were scheduled for MR imaging during a 4-year period and to determine if screening by plain radiography, CT, or both before MR imaging is efficacious. MATERIALS AND METHODS: Records of 15,024 patients scheduled for MR imaging were reviewed. A total of 1593 patients who had identified themselves as being at risk for an intraorbital metallic foreign body had undergone plain radiography or CT of the orbits. Plain radiographs and/or CT scans of patients reported as having orbital metal were reviewed to confirm the presence of a metallic foreign body and to identify its location. RESULTS: Metallic foreign bodies were discovered in 40 patients. Six of these patients had impaired vision in the involved eye. Ten patients had a metallic foreign body in or near the orbit but well away from the globe and were thought to be at low risk for movement of the foreign body as a result of MR imaging. The other 24 patients had metallic foreign bodies adjacent to or within the globe and were thought to be at risk for movement of the metallic foreign body as a result of MR imaging. CONCLUSION: The prevalence of intraorbital metallic foreign bodies in our study population was low (0.27%). Even in those patients identified as being at risk, the prevalence was only 2.5%. Based on the number of MR examinations performed annually in the United States and on data indicating that no radiographic screening is performed at 5% of institutions, we extrapolate that more than 2400 patients with intraorbital metallic foreign bodies have undergone MR imaging since 1986 without report of injury. These data allow us to infer that the risk of eye damage for patients who have intraorbital metal is low and that radiographic screening before MR imaging is not needed as often as it is done.

Blindness↗