Magnetic resonance imaging in 80 cases of orbital tumors

Magnetic resonance imaging (MRI) is a new medical imaging technique which has been used in evaluating ocular and orbital diseases in recent years. Owing to the high resolution of soft tissues and lesions, it is superior to ultrasound and computed tomography in the localization and characterization of an orbital tumor in diagnosis. In this paper, we analysed 80 cases of MR images of orbital tumors by which all the lesions were detected. Benign or malignant disorders were recognized in 59 cases and complete tumors with accurate localization were shown in 79 cases. The principles of MRI, signal intensity of various tumors and the indications of MRI were discussed.     

Magnetic resonance imaging of a mediastinal ependymoma

Ependymomas typically occur in the brain and spinal cord, and represent 5% and 16% of primary intracranial and spinal cord tumors respectively. Ependymomas arising outside the central nervous systems are uncommon and when they do occur are usually seen in the sacrococcygeal region. Other reported sites include the pelvis, spinal nerve roots, and lung. An extraspinal mediastinal ependymoma is a rare occurrence, with only two previously reported cases to our knowledge. In both instances, the lesion arose in the posterior mediastinum, and were imaged with either chest radiographs alone or chest radiographs and computed tomography. In our case, plain radiography was followed by magnetic resonance imaging. This report documents the clinical, pathological, and magnetic resonance imaging findings in a case of a posterior mediastinal ependymoma. Primary mediastinal ependymomas are rare lesions that may be considered in the differential diagnosis of a posterior mediastinal mass.     

Magnetic resonance imaging of the shoulder

MRI has rapidly become a commonly used technique for evaluation of the shoulder. It provides a wealth of information regarding the entire shoulder girdle, and it is the most accurate noninvasive method available for imaging the rotator cuff. There have been numerous technical improvements in MRI in the relatively short time that clinical MRI has been in existence. Further refinements in design, new imaging sequences, and additional clinical experience should help to increase the accuracy and flexibility of this imaging modality.     

Magnetic resonance imaging of the wrist

MR imaging of the wrist has the unique capability of simultaneously demonstrating bone and soft tissue structures. Its exquisite sensitivity for detecting bone marrow edema makes it and ideal screening tool for diagnosing radiographically occult osseous injuries and areas of AVN. This, together with its ability to provide a comprehensive, non-invasive assessment of the ligaments, tendons, nerves, and components of the TFC make MRI a very powerful tool for evaluating patients with wrist pain of uncertain etiology. Its exact role in the work-up of these patients has not been entirely established, but with further advances in technology and the radiologist's understanding of wrist anatomy and pathology, MRI is assuming a more central role in this clinical setting.     

Magnetic resonance imaging of the musculoskeletal system: the spine

Magnetic resonance imaging in the patient who has had surgery is discussed. The most common indication for postoperative imaging is in the distinction between postoperative fibrosis and recurrent disc herniation. Magnetic resonance imaging is invaluable in the assessment of potential causes of failed back surgery syndrome such as postoperative infection, arachnoiditis and adjacent segment degeneration. Magnetic resonance imaging assumes a less important role in postoperative patients with metal hardware owing to image degradation secondary to metal artifact. Magnetic resonance imaging has a complementary role with computed tomography evaluation of spinal trauma. It excels at the noninvasive evaluation of spinal deformities and neoplasms.     

Magnetic resonance imaging of the female pelvis

Evaluation of pelvic pathology is an important part of most radiology practices. Magnetic resonance imaging (MRI) has proven itself to be a useful and cost-effective method in evaluating many of these diseases. This article reviews appropriate MR imaging techniques and findings of common gynecologic disorders. Uterine pathology is categorized into congenital anomalies, benign lesions (leiomyomas, adenomyosis, endometrial polyps, and nabothian cysts), and malignancies (endometrial and cervical carcinoma). Adnexal pathology reviewed includes endometriosis, polycystic ovaries, teratomas, and benign and malignant ovarian epithelial tumors.     

Magnetic resonance imaging of the olfactory apparatus

The magnetic resonance imaging visualization of the olfactory apparatus is reported in this article. We used a superconductor-type magnetic resonance device (Siemens Magnetom H15 (1.5 T) with a surface coil. The subjects were patients with posttraumatic anosmia. The olfactory bulbs were clearly visualized in the frontal plane magnetic resonance images, the olfactory bulbs and the foramina of the cribriform plate were visualized in the sagittal section, and the olfactory bulbs, tracts, and other structures were visualized in the coronal sections. The olfactory nerves could not be seen.     

Magnetic resonance imaging arthrography of the ankle

Magnetic resonance imaging (MRI) arthrography of the ankle is a useful diagnostic modality in the detection and staging of lateral ankle ligament tears, particularly in patients who fail to respond to conservative management. MRI arthrography also may be helpful in determining the extent of ligamentous injury in professional athletes, for whom immediate surgical repair may be the initial treatment. Preoperative planning is optimized with MRI arthrography. Frequently, alternative diagnoses may be made for conditions that can simulate lateral ligamentous injury, thus obviating the need for diagnostic arthroscopy.     

Magnetic resonance imaging anatomy of the female urethra: a direct histologic comparison

OBJECTIVE: To define the urethral structures visible on magnetic resonance imaging (MRI) relevant to stress urinary incontinence. METHODS: The urethra and surrounding tissues were harvested from 13 female cadavers (ages 21-81) and fixed in 10% buffered formalin. High-resolution T1- and T2-weighted images were obtained at 1.5 tesla. Mallory trichrome-stained histologic sections were prepared in corresponding planes from the cadaveric specimens. Immunohistologic stains for smooth muscle (actin) and vascular endothelium (CD-34 and factor VIII) were obtained on two specimens. Histology and MRI were compared using side-by-side correlation of projected images and by superimposing projected images. Comparison was also made to a non-cadaveric urethral MRI of a 29-year-old woman and to the MRI of another specimen imaged pre- and post-fixation. RESULTS: Distinct layers of the cadaveric urethra were seen best on proton density and T2-weighted images. From the center to the periphery, a series of concentric rings were visible: an inner bright ring, the mucosa; a dark ring, the submucosa; an outer bright ring, the smooth muscle of the urethra in a loose connective tissue matrix; and a peripheral dark ring, the striated urogenital sphincter muscle of the urethra in dense connective tissue. No significant alterations were caused by fixation. These cadaveric images matched the non-cadaveric MRI of the 29-year-old woman. CONCLUSION: The internal urethral anatomy visible on high-resolution MRI can be identified and confirmed histologically, and these findings may form the basis for future anatomic investigation of stress urinary incontinence and other urethral abnormalities.     

Magnetic resonance imaging in a case of Wernicke's encephalopathy

Wernicke's encephalopathy is an uncommon disorder caused by a thiamine deficiency which is clinically characterized by the triad of ophthalmoplegia, ataxia and disturbances of consciousness, each finding being variably present. The disease is caused by malnutrition or malabsorption, and is often associated with prolonged alcohol intake, neoplasm and extensive inflammatory processes of the digestive tract and parenteral hyperalimentation-induced gastrointestinal mucosal atrophy. Clinical diagnosis can be elusive and MRI may be the only imaging technique able to detect the cerebral lesions, whose type and distribution are characteristic of the Wernicke's encephalopathy, whereas CT is positive only in exceptional cases. We report a case of a 56-year-old woman who developed a Wernicke's encephalopathy 1 month after a colonic resection with signal intensity changes located in the mammillary bodies and in the medial thalamic nuclei.     

Magnetic resonance imaging of seronegative sacroiliitis

A total of 27 patients with advanced previously untreated non-small-cell lung cancer were treated with paclitaxel and ifosfamide. The starting dose of paclitaxel was 175 mg/m2 given for 3 h by intravenous infusion on day 1. Ifosfamide 4 g/m2 was given for 4 h by intravenous infusion on day 2. Dosage of the two drugs was modified according to nadir white blood count after each cycle. Involved in the treatment were 17 males and 10 female patients. The median age was 61 years (range 47-71 years) and the median Karnofsky performance status was 70% (range 60-90%), 13 cases were stage IIIb and 14 cases were stage IV. One case was not evaluable due to lost follow-up after a single dose of chemotherapy. There were five cases not determined due to a timing error. Of 21 evaluable cases, eight achieved partial response (PR 38%, confidence interval 18.1-61.5%), seven achieved stable disease, two had a minor response. The median survival time of the whole group was 255 days (range from 38 to 567 days). The major toxicities were myalgia; arthralgia and neuropathies. Throughout the study, only three cases (15%) were treated at dose level 0. After the first cycle, 18 cases were treated at dose level 1, after a second cycle, 13 cases were treated at dose level 2. Three cases with grade 3 leukopenia were seen at dose level 0. At dose level 1, two cases had grade 3 leukopenia. At dose level 2, four episodes of grade 3 leukopenia were noted. It is concluded that paclitaxel can be combined safely with ifosfamide at these dosage levels. The response rates were comparable to the other chemotherapy combination in advanced non-small-cell lung cancer. The survival results were acceptable and comparable to the cisplatin-containing regimen. This study indicates that combinations of paclitaxel and/or ifosfamide with other agents, such as gemcitabine and vinorelbine, should be explored.     

Magnetic resonance imaging of brain death

The db/db mutant mouse is a rodent model of genetic diabetes that develops renal glomerular lesions with striking mesangial matrix accumulation by the age of 16 weeks, after 8-10 weeks of sustained hyperglycemia. However, abnormalities in renal function that antedate or accompany the appearance of these pathologic changes, which resemble those found in human diabetes, have not been delineated. We therefore examined renal function in young db/ db mice and their nondiabetic db/m littermates from the age of 8 through 15 weeks. Serum creatinine and blood urea nitrogen concentrations at the onset of diabetes in db/db mice did not differ significantly from mean concentrations in db/m controls. An elevated creatinine clearance, due in large part to increased body weight, and increased urinary albumin excretion were observed in db/db compared with db/m mice soon after establishment of sustained hyperglycemia. A relative reduction in creatinine clearance was demonstrable in db/db mice at the age of 15 weeks, coincident with the appearance of overt compromise in renal function manifested by frank increases in the serum creatinine and blood urea nitrogen. The findings indicate that the well-documented glomerular pathology in db/db mice is accompanied by definable alterations in renal function, which are similar in chronology and nature to those found in human diabetes.     

Magnetic resonance imaging of acute stroke

In the investigation of ischemic stroke, conventional structural magnetic resonance (MR) techniques (e.g., T1-weighted imaging, T2-weighted imaging, and proton density-weighted imaging) are valuable for the assessment of infarct extent and location beyond the first 12 to 24 hours after onset, and can be combined with MR angiography to noninvasively assess the intracranial and extracranial vasculature. However, during the critical first 6 to 12 hours, the probable period of greatest therapeutic opportunity, these methods do not adequately assess the extent and severity of ischemia. Recent developments in functional MR imaging are showing great promise for the detection of developing focal cerebral ischemic lesions within the first hours. These include (1) diffusion-weighted imaging, which provides physiologic information about the self-diffusion of water, thereby detecting one of the first elements in the pathophysiologic cascade leading to ischemic injury; and (2) perfusion imaging. The detection of acute intraparenchymal hemorrhagic stroke by susceptibility weighted MR has also been reported. In combination with MR angiography, these methods may allow the detection of the site, extent, mechanism, and tissue viability of acute stroke lesions in one imaging study. Imaging of cerebral metabolites with MR spectroscopy along with diffusion-weighted imaging and perfusion imaging may also provide new insights into ischemic stroke pathophysiology. In light of these advances in structural and functional MR, their potential uses in the study of the cerebral ischemic pathophysiology and in clinical practice are described, along with their advantages and limitations.     

Magnetic resonance imaging of disseminated sclerosis

Multiple sclerosis is a chronic demyelinating disease. Paraclinical examinations may contribute to the diagnosis of multiple sclerosis. Magnetic resonance imaging (MRI) has a very high sensitivity concerning multiple sclerosis, and has made it possible to visualize multiple sclerosis plaques in vivo, to follow each plaque over the course of time and in this way to obtain information about the pathogenesis. MRI has shown that the size of plaques may vary considerably, and that plaques are dynamic structures with the ability to change in size over few weeks. By using MRI and the contrast agent Gadolinium-DTPA, it is possible to distinguish a newly developed plaque from an older one. Therefore, MRI has become an important examination in therapeutic trials. Just now, MRI with Gadolinium-DTPA is being used to evaluate the efficacy of plasmapheresis and immunoglobulin treatment in a joint study between Rigshospitalet and Hvidovre Hospital.     

Magnetic resonance imaging of primary cardiomyopathies

Cardiomyopathies are diseases of the myocardium of unknown etiology associated with cardiac dysfunction. On the grounds of their morphology and pathophysiology, primary or idiopathic cardiomyopathies may be classified into a number of disorders; namely, hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, dilated cardiomyopathy, and restrictive cardiomyopathy. The term "secondary cardiomyopathies" is reserved to specific heart muscle diseases clinically very similar to primary cardiomyopathies. Cardiac magnetic resonance imaging has long been used to study cardiac morphology and, more recently, to assess blood flow, perfusion, and contractile function. The emerging role of magnetic resonance imaging for the understanding and treatment of primary cardiomyopathies cannot be underestimated. From a clinical point of view, an examination based on a single, efficient, and noninvasive MR study focusing on the clinically relevant features of cardiomyopathies is an objective and reproducible means for diagnosing and monitoring hypertrophic, arrhythmogenic, dilated, and restrictive cardiomyopathies.     

Magnetic resonance imaging of elephantiasis neuromatosa

We present the case of a 43-year-old man with neurofibromatosis type 1 who developed elephantiasis neuromatosa of his left leg. The gross limb enlargement was extremely disfiguring, and resulted in such severe disability that he was only able to walk a very short distance using crutches. Previous debulking procedures had resulted in massive blood loss, and prior to attempting further surgical intervention MRI studies were requested. Taking advantage of the excellent tissue characterisation and multiplanar imaging capabilities of MRI, we were able to assess the extent of soft tissue and osseous involvement. The use of recently developed MR angiographic sequences enabled us to non-invasively provide detailed images to assess the relationship of the lesions to the major vessels, as well as the vascular supply and angiographic features of the lesions themselves. This article describes our MRI-based findings, which precluded debulking surgery in this unusual manifestation of neurofibromatosis.