Magnetic Resonance Imaging of the Cavernous Sinus

Transcription

1 187 Magneti Resonane Imaging of the Cavernous Sinus David L. Daniels 1 Peter Peh Leighton Mark Kathleen Pojunas lan L. Williams Vitor M. Haughton The magneti resonane (MR) appearane of the avernous sinus was studied by orrelating the MR images of normal volunteers and ryomirotomi setions from six adavers. In addition, MR images of patients with parasellar masses were ompared with orresponding intravenously enhaned omputed tomographi (CT) sans. The MR appearane of the ranial nerves in the avernous sinuses is demonstrated, as well as MR signs of a parasellar mass, inluding obliteration of intraavernous venous spaes, displaement of the intraavernous internal arotid artery, and bulging of the lateral wall of the avernus sinus. MR proved to be more effetive than CT in delineating the parts of the avernous sinus. Magneti resonane (MR) imaging has the potential to demonstrate the intraavernous segments of ranial nerves in ontrast to the negligible signals of flowing blood. Our artile desribes the normal MR appearane of the avernous sinuses and the MR signs of avernous sinus lesions. Materials and Methods This artile appears in the Marh/pril 1985 issue of JNR and the May 1985 issue of JR. Presented at the annual meeting of the merian Soiety of Neuroradiology, oston, June This work was supported by a grant from General Eletri Medial Systems., ll authors: Department of Radiology, Medial College of Wisonsin, Froedtert Memorial Lutheran Hospital, 9200 W. Wisonsin ve., Milwaukee, WI ddress reprint requests to D. L. Daniels. JNR 6: , Marh/pril /85/ merian Roentgen Ray Soiety Six fresh frozen adaver heads were embedded in styrofoam boxes with a solution of arboxymethyl ellulose gel. The orbitomeatal lines and sellae turiae were identified with fluorosopy. With a horizontally utting heavy-duty sledge ryomirotome (LK 2250) and serial photography of the surfaes of the speimens (1), anatomi images of the avernous sinuses were obtained in planes parallel or perpendiular to the orbitomeatal line. In the anatomi images, the intraavernous segments of ranial nerves III-VI and of the internal arotid arteries (ICs) were identified using published anatomi, omputed tomographi (CT), and MR literature (2-6). group of seven normal volunteers and 15 patients were hosen for MR imaging. The patients inluded two with pituitary adenomas involving avernous sinuses and one with a parasellar aneurysm. The diagnoses were verified with onventional linial, CT, angiographi, and surgial (two ases) findings. The volunteers and patients were studied in prototype 1.3, 1.4, or 1.5 T General Eletri MR sanners. Initially, a partial saturation (PS) sagittal image was used to determine loations for axial and oronal PS, inversion reovery (IR ), and spin-eho (SE) imaging. Setions parallel (axial plane) and/or perpendiular (oronal plane) to the orbitomeatal line were obtained. Sequenes inluded PS ( mse TR, one or two averages, 128 x 256 or 256 x 256 matrix, and 3, 5, or 10 mm slie thikness); PS in a prospetive zoom mode in whih the field of view was redued to 12.5 m ( mse TR); IR (1500 mse TR, 600 mse TI, one average, 128 x 256 matrix, and 5-mm-thik slies); and SE (2000 mse TR, 25, 50, 75, and 100 mse TEs, 128 x 256 matrix, one average, and 5-mm-thik slies). xial and oronal MR images of the patients were ompared with ryomirotomi setions to identify ranial nerves in the avernous sinus. MR images of patients with parasellar masses were orrelated with orresponding intravenously enhaned CT images made on CT IT 8800 or 9800 sanners with onventional radiographi fators.

2 188 DNIELS ET L. JNR :6, Marh/pril 1985 Fig. 1.-Pituitary gland and anterior part of avernous sinus., Coronal ryomirotomi setion. (Reprinted from [7].) e, 5-mm-thik IR image, 128 x 256 matrix, one average. C, 3-mmthik PS image, 128 x 256 matrix, two averages. Cranial nerve III is superolateral, IV is lateral, and V' and VI together are inferolateral to internal arotid artery. etween ranial nerve V 2 and V' is prominent venous spae (white arrows). Lateral wall (urved arrow) of avernous sinus. P = pituitary gland; = IC; ON = opti nerve; OC = opti hiasm. Results The important landmarks of the avernous sinus in axial and oronal ryomirotomi setions are ranial nerves III-VI, the gasserian ganglion in Mekel ave, the IC, and the lateral wall of the avernous sinus. The oronal ryomirotomi setions show that the ranial nerves in the avernous sinuses have a onstant position with respet to the IC (fig. 1). Cranial nerve III is superolateral to the artery, ranial nerve IV (whih is muh smaller than III) is lateral, and ranial nerves V 1 and VI together are inferolateral. prominent venous spae and ranial nerve V 2 below it are at the inferior aspet of eah avernous sinus. Coronal ryomirotomi setions through the posterior part of the avernous sinus show ranial nerves III and IV and Mekel ave lateral to the IC (figs. 2 and 3). The oronal PS or IR images with slie thikness of 3 or 5 mm show small foi of high-intensity signals that orrespond to ranial nerves III, V 1, V 2 and VI in the avernous sinuses (figs. 1 and 4). The intensity of the signals is approximately equal to that of the orpus allosum. djaent flowing blood produes negligible signals. The nerves (espeially ranial nerve III) are better defined on a PS image using a zoom tehnique (fig. 4). The venous spae between V 1 and V 2 appears as a region of negligible signals. In oronal PS setions through the posterior aspet of the avernous sinus, Mekel ave appears as an oval-shaped region with slightly greater signal intensity than erebrospinal fluid (CSF) (figs. 2 and 3). In 5-mm-thik oronal SE images, ranial nerves V 1, V 2, and VI have high-intensity signals (fig. 4). The venous spae above V 2 has negligible signals. Cranial nerves III and IV are not onfidently identified. Mekel ave has a low- or high-intensity signal depending on the pulse sequenes. In T2-weighted images (late ehoes in SE images) it has an intense signal; in T1-weighted images (PS) it has a low intensity signal. In axial images individual

3 JNR:6, Marh/pril 1985 MR IMGING OF THE CVERNOUS SINUS 189 Fig. 2.-Posterior to fig. 1., Coronal ryomirotomi setion. Mekel ave {M} is lateral to vertial segment of IC {}., 3-mm-thik PS image, 256 x 256 matrix, two averages. Mekel ave is oval area of low signal intensity. Cranial nerve III is identifie. IN = infundibulum; OC = opti hiasm; P = pituitary gland. {Reprinted from [7].} Fig. 3.-Posterior to fig. 2., Coronal ryomirotomi setion. S, 3-mm-thik PS image, 256 x 256 matrix, two averages. Mekel ave {M} has slightly less intense signal than ranial nerve III. OC = opti hiasm; = internal arotid artery. {Reprinted from [7].} ranial nerves in the avernous sinuses are not differentiated (fig. 5). In T2-weighted images, high-intensity signal from CSF is deteted lateral to the lateral wall of the avernous sinus, while in PS images the CSF and the lateral wall both have low-intensity signals (fig. 5C). The lateral wall appears either straight or urving slightly onavely. Masses in the avernous sinus were learly demonstrated in the MR studies (figs. 4, 6, and 7). parasellar mass obliterated the venous spae above ranial nerve V 2, obsured the ranial nerves on oronal MR images, and usually produed bulging of the lateral wall of the involved avernous sinuses. Tumor produing a greater signal intensity than the blood in the avernous sinuses or ICs was easily deteted when it enroahed on these strutures. In one ase displaement of the arotid artery was demonstrated; in the other enasement of the arotid artery was demonstrated. Disussion MR demonstrates the ranial nerves effetively. Cranial nerves VII and VIII an be identified on a PS sequene beause they are surrounded by low-intensity signals from

4 190 DNIELS ET L. JNR:6, Marh/pril 1985 Fig. 4.-Coronal images of left parasellar aneurysm deforming pituitary gland., 5-mm-thik PS zoom image, 128 x 256 matrix, four averages., PS image, 128 x 256 matrix, two averages. C, SE image, 128 x 256 matrix, one average. 0, Enhaned CT san. neurysm (urved arrows) enhanes homogeneously in 0 but has inhomogeneous MR signals, probably beause of turbulent blood flow. Cranial nerves in right avernous sinus have high-intensity signals. Prominent venous spae (losed arrows) above ranial nerve V2 has negligible signals. OC = opti hiasm ; P = pituitary; = IC. ( reprinted from [7].) D Fig. 5.-Progressively more rostral axial images. and, 3-mm-thik PS images, 256 x 256 () and 128 x 256 () matries, two averages eah. Mekel ave (M) has slightly greater signal intensity than CSF. C, 3-mm-thik PS image, 256 x 256 matrix, two averages. Lateral wall of avernous sinus and adjaent CSF have negligible signal (arrow). = IC. ( and C reprinted from [7].) either the CSF or the petrous bone [8]. Cranial nerves III, V', V 2, and VI in the avernous sinus also an be shown with MR beause they are surrounded by low-intensity signal from flowing blood. We were unable to image ranial nerve IV in the avernous sinus, probably beause of its small size and lose proximity to ranial nerve III. MR demonstrates the ontents of the avernous sinuses more effetively than CT does. With MR the arotid arteries,

5 JNR :6, Marh/pril 1985 MR IMGING OF THE CVERNOUS SINUS 191 Fig. 6.-Prolatinoma extending laterad (straight arrows), enasing right IC, and obsuring ranial nerves in right avernous sinus. Corresponding oronal 3-mm-thik PS image, 128 x 256 matrix, two averages (), and enhaned CT san (). Cranial nerves III and V' plus VI are adjaent to left IC, and venous spae (urved arrows) is above V2. More anterior, 3-mm-thik PS image, 128 x 256 matrix, two averages (C), and enhaned CT san (0). V 2 in left foramen rotundum. OC = opti hiasm; = IC. o Fig. 7.-Partly ysti pituitary adenoma (thin arrow) extending to right avernous sinus (thik arrow)., 5-mm-thik PS image, 128 x 256 matrix, two averages., SE image, 128 x 256 matrix, one average. C, Enhaned CT san. Tumor displaes right IC () but not lateral avernous sinus wall (urved arrow). ranial nerves, and vasular hannels in the avernous sinus an be resolved onsistently, while CT often fails to show vasular strutures in the avernous sinuses unless dynami sanning tehniques are used. The anatomi landmarks in MR studies, inluding ranial nerves III, V', and V 2, the venous spae between V' and V 2, and the arotid artery, an be used to detet masses enroahing on the avernous sinuses. Therefore MR has greater sensitivity than CT for deteting

6 192 DNIELS ET L. JNR:6, Marh/pril 1985 tumor enroahment on the avernous sinus or enasement or displaement of the arotid artery. Our ases showed that tumor has a greater signal intensity than avernous sinus blood. The speifiity and sensitivity of MR versus CT in avernous sinus pathology an be determined in a larger series of patients. CKNOWLEDGMENTS We thank Cheryl D. Tauber, Laurie. Dunk, Peggy Dreifke, Linda Hutten, and Janie lba for assistane in performing this study. REFERENCES 1. Raushning W, ergstrom K, Peh P. Correlative raniospinal anatomy studies by omputed tomography and ryomirotomy. J Comput ssist Tomogr 1983;7 : Umansky F, Nathan H. The lateral wall of the avernous sinus. J Neurosurg 1982;56: Harris FS, Rhoton L. natomy of the avernous sinus, a mirosurgial study. J Neurosurg 1976;45 : Kline L, ker JD, Post MJD, Vitek JJ. The avernous sinus: a omputed tomographi study. JNR 1981 ;2: Segall HD, hmadi J, MComb JG, lee CS, eker TS, Han JS. Computed tomographi observations pertinent to intraranial venous thromboti and olusive disease in hildhood. Radiology 1982;143: Hawkes RC, Holland GN, Moore WS, Corston R, Kean DM, Worthington S. The appliation of NMR imaging to the evaluation of pituitary and juxtasellar tumors. JNR 1983;4: Daniels DL, Pojunas KW, Peh P, Haughton VM. Magneti resonane imaging of the sella and juxtasellar region. Milwaukee: General Eletri, Daniels DL, Herfkens R, Koehler PR, et al. Magneti resonane imaging of the internal auditory anal. Radiology 1984;151 :