Magnetic resonance imaging of intraocular tumors.
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Eye Neoplasms↗
Biomedical subjects
A E Flanders
Publications and source records attributed to A E Flanders.
Magnetic resonance imaging of orbital tumors.
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Bone Neoplasms↗
Lesions causing a mass in the medial canthus of the orbit: CT and MR features.
Few detailed radiologic articles treat the medial canthus as a "compartment" of the orbit. Nasal stuffiness and epiphora (excessive tearing) are frequent clinical manifestations of diseases involving the medial canthus of the orbit. Although some lesions can be adequately evaluated by clinical examination, imaging may show unsuspected deep extensions of the abnormality. CT has traditionally been the imaging method of choice because of the inherent contrast between structures in this region and its superb depiction of bone detail (Fig. 1). MR imaging can be useful in detecting subtle marrow invasion caused by lesions extending beyond the confines of the medial canthus (e.g., frontal bone, maxilla). In this pictorial essay, we illustrate the CT and MR appearances of diseases that can manifest as a medial canthal mass and provide practical differential diagnoses. Lesions can be inflammatory, neoplastic, or developmental in origin. Moreover, these lesions can result from abnormalities in the adjacent nasolacrimal apparatus, orbit, paranasal sinuses, and nasal cavity, or they can reflect an underlying systemic illness.
Female↗
Magnetic resonance imaging related to neurologic outcome in cervical spinal cord injury.
The purpose of this study was to examine the relationship between the initial intramedullary hemorrhage, as seen by magnetic resonance imaging (MRI), and the neurologic deficit and eventual neurologic outcome of acute cervical spinal cord injured subjects. MRI and motor assessments were performed on 24 subjects with motor complete (Frankel A & B) and incomplete (Frankel C & D) injuries. Recovery was determined by evaluating an initial and a final motor power following spinal cord injury (SCI), as defined by the manual muscle test (grade 1-5) and motor index score (MIS). Results showed that all 15 subjects having hemorrhage had motor complete injuries (Frankel A & B). Sixteen percent of the muscles in the upper extremities and 3% of the muscles in the lower extremities in these 15 subjects improved to a grade of > or = 3/5 at the final evaluation post-SCI. In comparison, of the nine subjects not having hemorrhage, eight had motor incomplete injuries (Frankel C & D) and had 73% and 74% of muscles improving in the upper and lower extremities, respectively. In addition, a change in MIS from initial to final evaluations showed a significant difference between subjects with hemorrhage and subjects without hemorrhage (upper extremities: p = .002 and lower extremities: p = .0001). In conclusion, the initial MR image and neurologic assessment correlated with motor power recovery.
Adolescent↗
Magnetic resonance imaging in acute spinal injury.
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Acute Disease↗
Role of magnetic resonance imaging in the evaluation of the hydroxyapatite orbital implant.
The role of magnetic resonance imaging (MRI) in the assessment of fibrovascular ingrowth in the integrated hydroxyapatite orbital implant is evaluated. Fifteen patients who underwent enucleation and placement of a hydroxyapatite orbital implant were evaluated for degree of implant vascularity with gadolinium-DPTA-enhanced MRI with surface coil before drilling the implant. On T1-weighted images, the hydroxyapatite sphere appeared with intermediate signal. After gadolinium-DPTA administration, all patients showed an enhancement in the implant consistent with the presence of fibrovascular ingrowth. The enhancement was most notable in the peripheral portions of the sphere and was seen as early as 5 months after implantation. Comparison of gadolinium-DPTA-enhanced MRI with contrast-enhanced computed tomography, ultrasonography, and color Doppler imaging suggests that these latter techniques are not as helpful in the detection of the fibrovascular tissue in the orbital implant. Bone scan, a technique used by many surgeons, demonstrates fibrovascular ingrowth, but it is limited by its one-dimensional low-resolution image. Because of its three-dimensional capability and its highest resolution, contrast-enhanced MRI with surface coil appears to be the best imaging method for evaluating the hydroxyapatite orbital implant and its fibrovascular ingrowth.
Adolescent↗
Intradural schwannomas of the spine: MR findings with emphasis on contrast-enhancement characteristics.
Intradural extramedullary schwannomas are nerve sheath neoplasms that consist of focal proliferations of Schwann cells involving a spinal nerve. We reviewed the MR findings in seven patients with pathologically proved intradural schwannomas. The contrast-enhancement characteristics on MR images were determined and compared with the histologic features of the tumor. Six lesions were variably hyperintense on T2-weighted images and one was uniformly hypointense compared with the signal intensity of the spinal cord. Signal on T1-weighted images ranged from hypointense to isointense. All seven tumors showed heterogeneous enhancement; in five, the enhancement involved only the periphery of the lesion. The pattern of enhancement did not correlate with the signal characteristics noted on unenhanced T1- and T2-weighted images. Pathologically, hyaline thickening of vessel walls and cyst formation were prevalent in the peripherally enhancing lesions. However, enhancement did not correlate with the relative proportion of Antoni type A and type B tissue. Recognition of the MR characteristics of intradural extramedullary schwannomas may be helpful in the differential diagnosis of spinal tumors. In particular, peripheral contrast enhancement of an intradural extramedullary tumor on MR images should suggest the diagnosis of schwannoma.
Adult↗
Prognostic significance of magnetic resonance imaging in the acute phase of cervical spine injury.
Fifty-seven patients with acute cervical spine injuries and associated major neurological deficit were examined within 2 weeks of injury by magnetic resonance (MR) imaging. All patients had abnormal scans, indicating intramedullary lesions. This study was undertaken to determine if the early MR imaging pattern had a prognostic relationship to the eventual neurological outcome. Three different MR imaging patterns were observed in these patients: 21 patients had patterns characteristic of intramedullary hematoma (Group 1); 17 had intramedullary edema over more than one spinal segment, but no hemorrhage (Group 2); and 19 had restricted zones of intramedullary edema involving one spinal segment or less (Group 3). The neurological state was determined using standard motor index scores at admission and at follow-up examination. Characteristically, the patients in Group 1 had admission motor scores significantly lower than the other two groups. At follow-up examination, the median percent motor recovery was 9% for Group 1, 41% for Group 2, and 72% for Group 3. These studies suggest that the MR imaging pattern observed in the acutely injured human spinal cord has a prognostic significance in the final outcome of the motor system. It is only when an accurate prognosis can be given at the outset that useful treatment data might be collected for homogeneous injury groups, and accurately based long-term planning made for the best patient care.
Adult↗
Diagnostic capabilities of magnetic resonance imaging and computed tomography in acute cervical spinal column injury.
The present study was conducted to evaluate the imaging capabilities of magnetic resonance imaging (MRI) in evaluating acute cervical spinal column injury and compare these results to that of computed tomographic (CT) imaging. Forty-nine patients undergoing MRI at a Level I and regional spinal cord trauma center to evaluate cervical spinal column injury were studied. Seventy-one injuries were identified by MRI. These injuries were classified as osseous (fracture/dislocation) (n = 21), disc herniation (n = 29), and spinal cord injury (edema/contusion/transection) (n = 21). Diagnostic imaging results in 33 of the 49 patients undergoing both MRI and CT were compared. CT demonstrated 22 fracture/dislocations compared to 10 on MRI. MRI demonstrated 19 disc protrusions compared to 7 on CT. Additionally, MR imaged 13 cord injuries as compared to 0 by CT. MR imaging proved superior in demonstrating spinal cord pathology and intervertebral disc herniation. CT was superior to MRI in demonstrating osseous injury. CT and MRI may be useful together in determining presence and extent of spinal column injury.
Adult↗
Clinical safety and efficacy of gadoteridol: a study in 411 patients with suspected intracranial and spinal disease.
In this phase III study, 411 adult patients with suspected intracranial or spinal disease underwent magnetic resonance (MR) imaging before and after intravenous injection of 0.1 mmol/kg gadoteridol (gadolinium 1,4,7-tris [carboxymethyl]-10-[2'-hydroxypropyl]-1,4,7,10-tetraazacyclododecane+ ++). MR images were evaluated by a single unblinded reader at each of 27 sites; the diagnosis was confirmed with one of nine imaging or surgical procedures within 8 weeks before or after MR imaging. After injection, no clinically significant changes were noted in laboratory values, physical examination, or vital signs. Adverse clinical events possibly or probably associated with injection of gadoteridol were seen in 18 of 411 patients (4.4%); the most common were dysgeusia and mild nausea, and all abated without residual effects. MR images enhanced with gadoteridol in patients with confirmed disease provided more diagnostic information than unenhanced images in 128 of 175 brain examinations (73.1%) and 93 of 137 spinal examinations (67.9%). A change in diagnosis because of additional information from contrast-enhanced images was considered likely in 63 of 214 cranial and 54 of 161 spinal studies.
Adult↗
Acute cervical spine trauma: correlation of MR imaging findings with degree of neurologic deficit.
A retrospective analysis of magnetic resonance (MR) imaging studies of 78 patients with acute cervical spinal cord injuries was undertaken to determine which observations related directly to the neurologic injury. All MR imaging studies were performed on a 1.5-T unit and assessed with respect to 14 parameters related to the bony spine, ligaments, prevertebral soft tissues, intervertebral disks, and spinal cord. Forty-eight patients also underwent non-contrast material-enhanced thin-section computed tomography (CT) of the cervical spine. MR imaging was the definitive modality in the assessment of soft-tissue injury, especially in the evaluation of the spinal cord and intervertebral disks. All patients with a neurologic deficit had abnormal spinal cords at MR imaging. Intramedullary hemorrhage was predictive of a complete lesion. The degree of associated bone and soft-tissue injury had no bearing on the extent of spinal cord injury or neurologic deficit. Patients with residual cord compression following reduction demonstrated greater neurologic compromise than those without compression.
Acute Disease↗
Orbital lymphoma. Role of CT and MRI.
CT and MRI have made it possible to make a strongly presumptive diagnosis of orbital lymphoid tumors. Orbital lymphomas are usually homogeneous masses of relatively high density and sharp margins. The lesions mold themselves to pre-existing structures without eroding the bone. On MR imaging, they appear as relatively hypointense images, particularly in T1-weighted MR scans.
B-Lymphocytes↗
Retinoblastoma and simulating lesions: role of CT and MR imaging.
Diagnosis of retinoblastoma is one of the most challenging problems of pediatric ophthalmology and radiology. It must be differentiated from numerous simulating lesions. Accurate diagnosis by means of ultrasonography, CT, and MR is essential for prompt treatment and prevention of metastasis. The CT and MR findings in 45 patients are presented in this article in order to evaluate and compare the usefulness of these two imaging techniques in the diagnosis of retinoblastoma.
Calcinosis↗
Conventional and fast spin-echo MR imaging: minimizing echo time.
Magnetic resonance imaging is frequently complicated by the presence of motion and susceptibility gradients. Also, some biologic tissues have short T2s. These problems are particularly troublesome in fast spin-echo (FSE) imaging, in which T2 decay and motion between echoes result in image blurring and ghost artifacts. The authors reduced TE in conventional spin-echo (SE) imaging to 5 msec and echo spacing (E-space) in FSE imaging to 6 msec. All magnetic gradients (except readout) were kept at a maximum, with data sampling as fast as 125 kHz and only ramp waveforms used. Truncated sinc radio-frequency pulses and asymmetric echo sampling were also used in SE imaging. Short TE (5.8 msec) SE images of the upper abdomen were compared with conventional SE images (TE = 11 msec). Also, FSE images with short E-space were compared with conventional FSE images in multiple body sites. Short TE significantly improved the liver-spleen contrast-to-total noise ratio (C/N) (7.9 vs 4.1, n = 9, P < .01) on T1-weighted SE images, reduced the intensity of ghost artifacts (by 34%, P < .02), and increased the number of available imaging planes by 30%. It also improved delineation of cranial nerves and reduced susceptibility artifacts. On short E-space FSE images, spine, lung, upper abdomen, and musculoskeletal tissues appeared crisper and measured spleen-liver C/N increased significantly (6.9 vs 4.0, n = 12, P < .01). The delineation of tissues with short T2 (eg, cartilage) and motion artifact suppression were also improved. Short TE methods can improve image quality in both SE and FSE imaging and merit further clinical evaluation.
Abdomen↗
Effect of MR imaging on the normal human pineal body: measurement of plasma melatonin levels.
Production of melatonin, a hormone synthesized and secreted by the pineal body, has been suppressed by electromagnetic fields in some but not all animal studies. Magnetic resonance (MR) imaging at 1.5 T was evaluated for its ability to modulate the level of melatonin in eight male volunteers. Subjects were exposed to three conditions, respectively, between 1:00 and 2:00 AM on different nights: (a) a series of routine MR pulse sequences for brain imaging in dark conditions, (b) dark control conditions, and (c) bright-light control conditions. Plasma was analyzed for melatonin and cortisol levels. Hormonal changes were analyzed by one-factor repeated measures within-subject analysis of variance. These conditions were associated with significant differences in melatonin levels: F(2, 6) = 7.95, and P = .021. Subjects exposed to darkness showed a typical increase in melatonin concentration. Subjects exposed to bright light showed a characteristic suppression of melatonin concentration. Those exposed to the MR imaging fields showed an increase in melatonin level similar to that seen in the dark control condition. Light and MR imaging had no significant effects on cortisol levels. Thus, MR imaging at field strengths known to modulate melatonin levels in rats did not suppress melatonin production in human subjects.
Adult↗
Paranasal sinus mucocele: unusual MR manifestations at 1.5 T.
The classic MR appearance of paranasal sinus mucoceles is due to its cystic composition. We present two cases of paranasal sinus mucocele that exhibit atypical signal characteristics. The morphology of this lesion, rather than its signal intensity, is paramount in establishing this diagnosis.
Female↗
CT characteristics of orbital pseudotumors and other orbital inflammatory processes.
Orbital pseudotumor is a nonspecific inflammatory process of unknown etiology that may mimic a true orbital neoplasm, specifically lymphoma. It exhibits a highly variable clinical and radiographic presentation. Thirty-nine patients with a presumptive diagnosis of orbital inflammatory disease were examined with CT and evaluated with respect to 13 findings associated with inflammatory disease of the orbit. Pseudotumor was included as part of the differential diagnosis in 25 patients. Twenty-one cases received a final (clinical) diagnosis of pseudotumor. The remainder were comprised of a broad range of orbital inflammatory conditions. Key radiographic features required to entertain or exclude the diagnosis of pseudotumor included establishing the presence of an orbital mass, extraocular muscle enlargement, bony erosion, enhancement, and associated paranasal sinus disease.
Adult↗