Intraocular Lymphoma after Cardiac Transplantation: Magnetic Resonance Imaging Findings

We report a case of intraocular lymphoma in a 65-year-old man, 15 months after cardiac transplantation. On Magnetic Resonance (MR) images, the iris and the anterior chamber of the right eye were found to be involved with an enhancing soft-tissue lesion. To our knowledge, this is the first case of post-transplantation intraocular lymphoma evaluated with MR imaging.

Experimental Model for Research on the Blood-Ocular Barrier

PURPOSE: The eyeball has 2 blood-ocular barriers, i.e., the blood-retinal and blood-aqueous barriers. The purpose of this study was to evaluate if triolein emulsion could disrupt the barriers, and we wanted to suggest as an experimental model for future blood-ocular barrier studies. MATERIALS AND METHODS: The triolein emulsion was made of 0.1 ml triolein and 20 ml normal saline, and this was infused into the carotid artery of ten cats (the experimental group). As a control group, only normal saline was infused in another ten cats. Precontrast and postcontrast T1-weighted MR images were obtained at 30 minutes and 3 hours after embolization in both groups. The signal intensities were evaluated qualitatively and quantitatively in the anterior and posterior chambers and also in the vitreus fluid. Statistical analysis was performed by employing the Kruskal Wallist test, Dunn's Multiple Comparison test and the Wilcoxon signed rank test. RESULTS: In the control group, no contrast enhancement was demonstrated in the anterior or posterior chamber or in the vitreus fluid of the ipsilateral or contralateral eyeball on the 30 minutes MR images. The anterior chambers of the ipsilateral and contralateral eyeballs revealed delayed contrast enhancement on the 3 hour MR images. In the experimental group, the 30 minute-postembolization MR images were not different from those of the control group. The 30 minute-postembolization MR images demonstrated delayed contrast enhancement in the anterior chamber of the ipsilateral and contralateral eyeballs and in the posterior chamber of the ipsilateral eyeball. The delayed contrast enhancement of the posterior chamber of the ipsilateral eyeball was statistically significant (p<0.05). CONCLUSION: The present study demonstrated significant contrast enhancement in the posterior chamber with infusion of the triolein emulsion, and this can serve as a model for blood-aqueous barrier studies.

MR Imaging of Orbital Inflammatory Pseudotumors with Extraorbital Extension

OBJECTIVE: To demonstrate a variety of MR imaging findings of orbital inflammatory pseudotumors with extraorbital extension. MATERIALS AND METHODS: We retrospectively reviewed the MR features of five patients, who were diagnosed clinically and radiologically as having an orbital inflammatory pseudotumor with extraorbital extension. RESULTS: The types of orbital pseudotumors were a mass in the orbital apex (n = 3), diffuse form (n = 2), and myositis (n = 1). The extraorbital extension of the orbital pseudotumor passed through the superior orbital fissure in all cases, through the inferior orbital fissure in two cases, and through the optic canal in one case. The orbital lesions extended into the following areas: the cavernous sinus (n = 4), the middle cranial fossa (n = 4), Meckel's cave (n = 2), the petrous apex (n = 2), the clivus (n = 2), the pterygopalatine fossa and infratemporal fossa (n = 2), the foramen rotundum (n = 1), the paranasal sinus (n = 1), and the infraorbital foramen (n = 1). On MR imaging, the lesions appeared as an isosignal intensity with gray matter on the T1-weighted images, as a low signal intensity on the T2-weighted images and showed a marked enhancement on the post-gadolinium-diethylene triamine pentaacetic acid (post-Gd-DTPA) T1-sequences. The symptoms of all of the patients improved when they were given high doses of steroids. Three of the five patients experienced a recurrence. CONCLUSION: MR imaging is useful for demonstrating the presence of a variety of extraorbital extensions of orbital inflammatory pseudotumors.

Comparison of Orbital Pseudotumor and Lymphoma: Clinical and Radiological Findings

PURPOSE: To compare the clinical and radiological findings of orbital pseudotumor with those of orbital lymphoma. MATERIALS AND METHODS: The clinical and radiological features of 12 orbital pseudotumors were compared with those of 17 orbital lymphomas, the nature of all lesions being confirmed by tissue biopsy. Twenty-four CT scans and nine MR images were retrospectively reviewed and compared, with special focus on the location of a tumor in the orbit, the invasion of periorbital structures, tumor margin, bilaterality, and signal intensity. The initial symptoms at admission were also classified and compared. RESULTS: In 50% of cases, orbital pseudotumors were located in both extraconal and intraconal space; 75% involved two or more extraocular muscles, and 33% involved the optic nerve. Margins were either infiltrative (75%) or ill-defined (92%). As for orbital lymphomas, 64% occupied extraconal space, invading one or less extraocular muscle (76%) and conjunctiva (29%). Seventy-one percent had a sharp margin, and 65% were lobulated or round. In pseudotumors, orbital pain and visual loss were major symptoms, while in lymphomas a painless orbital mass was the initial symptom. CONCLUSION: CT or MR image analysis of lesion location, margin, and the involvement of adjacent extra-ocular muscle or optic nerves may help differentiate between orbital lymphoma and orbital pseudo tumor.

MR Imaging of the Orbital Apex: Anatomy and Pathology

The apex of the orbit is basically formed by the optic canal, the superior orbital fissure, and their contents. Space-occupying lesions in this area can result in clinical deficits caused by compression of the optic nerve or extraocular muscles. Evenvascular changes in the cavernous sinus can produce a direct mass effect and affect the orbitapex. When pathologic changes in this region is suspected, contrast-enhanced MR imaging with fat saturation is very useful. According to the anatomic regions from which the lesions arise, they can be classified as belonging to one of five groups; lesions of the optic nerve-sheath complex, of the conal and intraconal spaces, of the extraconal space and bony orbit, of the cavernous sinus or diffuse. The characteristic MR findings of various orbital lesions will be described in this paper.

MR Imaging Findings of Orbitofacial Infarction Secondary to Rhinoorbital Mucormycosis: A Case Report

Rhino-orbital mucormycosis is the most frequently fatal fungal infection commonly occurring in patients with poorly controlled diabetes mellitus and and those who are immunocompromised, and requires prompt treatment. We describe a case of rhino-or-bital mucormycosis with orbital cellulitis and paranasal sinusitis, as seen on initial MR images, which on follow-up images had evol ved to orbitofacial infarction. MR imaging was useful for the demonstration of orbitofacial infarction, seen as areas of lack of enhancement and thus suggesting vascular invo l vement by mucor hyphae.

Usefulness of CISS Technique in the MR Imaging Diagnosis of Intraocular Lesions

PURPOSE: To assess the usefulness of CISS images in the diagnosis of intraocular lesions, we compared CISSimages with 3mm and 1mm sliced spin-echo T2-weighted images. MATERIALS AND METHODS: In 14 patients with 15intraocular lesions(retinal detachment 10, choroidal melanoma, 2 ; cavernous hemangioma, 1 ; PHPV, 1 ; andretinoblastoma, 1). we used a 1.5T MR unit obtain CISS images and 3mm and 1mm sliced spin-echo T2-weighted images.All lesions were analyzed, and after dividing them into two subgroups(linear lesions, n=11 ; mass lesions, n=4),CISS and spin-echo T2-weighted images were compared for detection rate and conspicuity. RESULTS: With regard tothese two parameters, CISS images were superior to 1mm and 3mm sliced spin-echo T2-weighted images. For theassessment of linear lesions, CISS images (detection rate, 100% ; conspicuity, 2.88) were superior to both 1mm and3mm sliced spin-echo T2-weighted images. For mass lesions CISS images were superior to 3mm sliced spin-echoT2-weighted images, but for conspicuity, there was no significant difference between CISS images (2.75) and 1mmsliced spin-echo T2-weighted images(2.2). CONCLUSION: Due to their higher detection rate and greater conspicuity,CISS images were superior to spin-echo T2-weighted images for the diagnosis of intraocular lesions less than 3mmin diameter ; for the diagnosis of intraocular lesions, they might therefore be a useful adjunct to SE images.

MRI Findings of Hydroxyapatite Orbital Implants

PURPOSE: To assess MR findings of hydroxyapatite orbital implants and their usefulness for the evaluation of fibrovascular ingrowth. MATERIALS AND METHODS: MR images of 32 hydroxyapatite orbital implants were obtained six months after implantation surgery. We retrospectively analysed MR images for signal intensity and contrast enhancement in both central and peripheral zones of the implants. The degree of contrast enhancement in an implant was compared with that of the temporalis muscle on contrast enhanced fat suppressed T1 weighted images. RESULTS: On T1-weighted images, implants showed a higher signal intensity than that of the vitreous body in the opposite globe. All implants showed peripheral contrast enhancement, densely enhanced in 30 cases and faintly in two. Three implants showed dense central contrast enhancement, and in the remainder, enhancement was similar to that of gray matter. On T2 weighted images, bright signal intensity was noted in 29 implants, focally in 19 and diffusely in ten. In most cases, areas of peripheral iso- to low signal intensity on T2-weighted images corresponded well with the contrast-enhanced area on T1 weighted images. CONCLUSION: At six months ofter surgery, Gd-enhanced MR imaging was useful for the evaluation of fibrovascular ingrowth in hydroxyapatite orbital implants.

Orbital Blowout Fracture: MR Findings

PURPOSE: To access the usefulness of magnetic resonance(MR) in the evaluation of orbital blowout fracture. MATERIALS AND METHODS: Fourteen patients with orbital blow out fractures diagnosed by plain radiography(n = 8) or computed tomography(CT)(n = 6) were examined with MR. Twenty blowout fractures including six patients with two lesions were presented and the fracture site of the orbit was the medial wall in 11 cases and the orbital floor innine cases. MR images in nine cases of six patients could be compared with CT scans. On MR images, were trospectively evaluated the presence of fracture, herniation of orbital fat, abnormality of extraocular muscle, intraorbital hematoma and intrasinus hemorrhage. In nine cases we also compared these findings with CT scans. RESULTS: Eighteen orbital blowout fractures with fat herniation could be diagnosed on MR images. In only nine of these 18 cases, the fracture itself could be seen on MR images as a disruption of the orbital wall, which produce a signal void. But two blow out fractures without orbital fat herniation, seen on CT, were not detected on MRimages. Twenty abnormalities of extraocular muscle in 18 cases were depicted on MR images. There were nosignificant differences between MR and CT in the evaluation of orbital fat herniation and extraocular muscle abnormality ; however, in one case oblique sagittal MR images provided more useful information about the status ofthe inferior rectus muscle. Intraorbital hematoma was detected by MR in three patients. We were able to establish the presence of intraorbital hematoma by using the different signal intensities from fat or muscle on T1- and/or T2-weighted images. MR was found to be superior to CT in one case of intraorbital hematoma because of the iso-density of hematoma compared to muscle. MR also detected intrasinus hemorrhage which on T1-weighted images revealed high signal intensity in ten cases. MR was more valuable in demonstrating intrasinus hemorrhage in onecase where a CT scan showed only hypodense fluid. CONCLUSION: MR is a useful diagnostic modality in the evaluation of orbital blowout fracture with orbital fat herniation. Compared with CT, it also provides more valuable information about associated extraocular muscle abnormality, subacute hemorrhage in the orbit and paranasal sinus.