ABSTRACT
Magnetic resonance angiography (MRA) hs inherent artifacts due to variation in velocity and direction of flowing blood in the carotid bulb and regions of stenosis. We examined the efficiency of dual 3-inch surface coils to delineate carotid artery flow better. Carotid MRA was performed on ten healthy volunteers and six patients, on a 1.5 T system. A special adapter was constructed to use with 3-inch (receive-only) coils, which were placed over the carotid bifurcations. Routine anterior neck coils were also used. Contiguous axial two-dimensional (45/8.7, 1.5 mm, flip angle 60 degrees) time-of-flight sequences were used. Image matrix was 256 x 256 with two signals averaged and acquisition time 6-10 min. These images were postprocessed and reformatted into angiographic views using a maximum intensity projection algorithm. Computer simulation of carotid artery blood flow throughout the cardiac cycle based on vessel contours derived from digital subtraction angiography was carried out by finite element analysis. Improved definition of vessel margin, particularly at the carotid bifurcation, and substantially increased signal-to-background ratio of flowing blood were obtained with 3-in-chcoils. Apparent loss of signal in the carotid bulb was diminished. In one patient, contiguous flow throughout a high-grade stenosis was well defined, with the surface coil method, while drop-off of signal was observed with routine neck coil imaging.
Subject(s)
Carotid Arteries/pathology , Magnetic Resonance Angiography/methods , Adult , Aged , Angiography, Digital Subtraction , Arteriosclerosis/diagnosis , Arteriosclerosis/diagnostic imaging , Arteriosclerosis/physiopathology , Blood Flow Velocity , Carotid Arteries/diagnostic imaging , Carotid Arteries/physiopathology , Carotid Artery Diseases/diagnosis , Carotid Artery Diseases/diagnostic imaging , Carotid Artery Diseases/physiopathology , Humans , Magnetic Resonance Angiography/instrumentation , Middle AgedABSTRACT
OBJECTIVE: Recent studies have shown that contrast (gadopentetate dimeglumine)-enhanced magnetic resonance imaging is useful in evaluating intraocular tumors and differentiating uveal melanoma from other simulating lesions. The purpose of this study was to study prospectively the role of fat-suppression technique and gadopentetate dimeglumine-enhanced magnetic resonance imaging in the evaluation of intraocular neoplasia. PATIENTS: Forty-three uveal melanomas and 20 other simulating intraocular lesions from 63 patients were prospectively evaluated on non-contrast-enhanced and post-contrast-enhanced T1-weighted images with and without fat-suppression technique and on T2-weighted images. RESULTS: Forty-one uveal melanomas (95%) were detected with standard pulse sequences and showed the characteristic hyperintense signal on non-contrast-enhanced T1-weighted images and hypointense signal with respect to the vitreous on T2-weighted images. All 33 uveal melanomas evaluated on non-contrast-enhanced T1-weighted images with fat-suppression technique were detected on non-contrast-enhanced images with fat-suppression technique. The intensity of the signal was statistically associated with the degree of pigmentation of the tumor on T1-weighted images with fat-suppression technique (P = .03). On post-contrast-enhanced T1-weighted images with or without fat-suppression technique, the 43 uveal melanomas showed enhancement. The degree of tumor enhancement was not statistically related to the degree of tumor pigmentation or the location of the tumor. Among the other simulating intraocular lesions, choroidal metastasis, retinoblastoma, choroidal leiomyoma, and medulloepithelioma demonstrated the same features on magnetic resonance imaging studies as uveal melanoma demonstrated on non-contrast-enhanced and post-contrast-enhanced T1-weighted images with or without fat-suppression technique. In our series, choroidal hemangioma, choroidal osteoma, posterior scleritis, retinal hemangioma, and Coats' disease can be differentiated from other amelanotic intraocular tumors by their characteristics on magnetic resonance imaging studies. CONCLUSIONS: We concluded that pre-and post-contrast-enhanced T1-weighted images with fat-suppression technique are most helpful in detecting small intraocular tumors with a thickness of more than 1.8 mm and in evaluating intraocular neoplasms and simulating lesions, particularly when T2-weighted images are not available. Moreover, in juxtapapillary choroidal or retinal tumor, fat-suppression technique may help in the detection of possible optic nerve or orbital extension by improving the conspicuousness of the tumor.
Subject(s)
Adipose Tissue/anatomy & histology , Eye Neoplasms/diagnosis , Gadolinium , Magnetic Resonance Imaging/methods , Meglumine , Organometallic Compounds , Pentetic Acid/analogs & derivatives , Adolescent , Adult , Aged , Child , Child, Preschool , Contrast Media , Drug Combinations , Evaluation Studies as Topic , Female , Gadolinium DTPA , Humans , Infant , Male , Middle Aged , Prospective Studies , Retinoblastoma/diagnosis , Uveal Neoplasms/diagnosisABSTRACT
A patient with severe bleeding due to carcinoma of the pharynx, uncontrollable by surgical intervention, was successfully treated by bilateral transcatheter embolization of the external carotid arteries using gel-foam. Although these lesions may appear hypovascular angiographically, this does not preclude embolization as a valuable therapeutic technique. Our experience with this patient indicates that transcatheter embolization is an especially appropriate approach to controlling bleeding in patients with extensive malignant disease when no other therapy is available.
