Magnetic resonance imaging of the cavernous sinus

The magnetic resonance (MR) appearance of the cavernous sinus was studied by correlating the MR images of normal volunteers and cryomicrotomic sections from six cadavers. In addition, MR images of patients with parasellar masses were compared with corresponding intravenously enhanced computed tomographic (CT) scans. The MR appearance of the cranial nerves in the cavernous sinuses is demonstrated, as well as MR signs of a parasellar mass, including obliteration of intracavernous venous spaces, displacement of the intracavernous internal carotid artery, and bulging of the lateral wall of the cavernous sinus. MR proved to be more effective than CT in delineating the parts of the cavernous sinus.     

海绵窦的MRI解剖

为海绵窦解剖的影像学和外科学提供基础资料。方法利用１１具头颅冠状断面层标本,３６例正常头颅冠状面平扫,动态和常规增强ＭＲＩ对照研究了海绵窦的位置,形态和内容。结果海绵窦为中颅凹两层硬脑膜民的硬脑膜窦,颈内动脉和外层神经位于海绵窦内,     

Dynamic MR imaging in Tolosa-Hunt syndrome

OBJECTIVE: To evaluate the cavernous sinuses with dynamic magnetic resonance (MR) imaging in patients with Tolosa-Hunt syndrome (THS). METHODS: The sellar and parasellar regions of five patients with THS and 12 control subjects were examined with dynamic MR (1.5 T) imaging in the coronal plane. Dynamic images were obtained with spin-echo (SE) sequences in three patients, and with fast spin-echo (FSE) sequences in two patients and control subjects. Conventional MR images of the cranium including sellar and parasellar regions were also obtained on T1-weighted pre- and post-contrast SE, and T2-weighted FSE sequences in the coronal plane. RESULTS: MR images revealed affected cavernous sinus with bulged convex lateral wall in three patients and concave lateral wall in two patients. In all control subjects, cavernous sinuses were observed with concave lateral wall. The signal intensity on T1- and T2-weighted images and contrast enhancement on post-contrast images of the affected cavernous sinuses in patients were similar to those of the unaffected cavernous sinuses in patients and control subjects. The dynamic images in all patients disclosed small areas adjacent to the cranial nerve filling-defects within the enhanced venous spaces of the affected cavernous sinus, which showed slow and gradual enhancement from the early to the late dynamic images. No such gradually enhancing area was observed in control subjects except one. The follow-up dynamic MR images after corticosteroid therapy revealed complete resolution of the gradually enhancing areas in the previously affected cavernous sinus. CONCLUSION: Dynamic MR imaging may facilitate the diagnosis of THS.     

The anatomy of the inferior petrosal sinus,glossopharyngeal nerve,vagus nerve,and accessory nerve in the jugular foramen.

PURPOSETo define the variations of the courses of the cranial nerves and the inferior petrosal sinuses as they enter and traverse the jugular foramen.METHODSThirty-nine cadaveric specimens containing the jugular foramen were scanned with 1-mm contiguous axial and coronal CT sections. Each specimen was dissected to evaluate the position of the cranial nerves and inferior petrosal sinus as they entered the jugular foramen.RESULTSThe glossopharyngeal nerve entered the most superior, anterior, and medial aspect of the jugular foramen and descended in the anterior portion of the jugular foramen, often within a groove. The vagus and accessory nerves could not be separated by CT. They entered the jugular foramen most often anterior or anterior and inferior to the jugular spine of the temporal bone and descended in a position ranging from medial to anterior to the jugular vein. The inferior petrosal sinus most often coursed inferior to the horizontal portion of the glossopharyngeal nerve and entered the jugular system in the jugular foramen, at the exocranial opening or below the skull base. A pars nervosa and pars venosa could be identified only at the endocranial opening, where the jugular spine separated the pars nervosa containing the inferior petrosal sinus and three cranial nerves from the pars venosa containing the jugular vein.CONCLUSIONOur evaluation demonstrated anatomic variation in the area of the jugular foramen.     

Comparison of plain radiographs and coronal CT scans in infants and children with recurrent sinusitis

We performed a prospective study of 70 infants and children with recurrent sinusitis. We compared plain radiographs with coronal CT scans of the sinuses to determine if plain radiographs can be used to accurately diagnose and localize residual sinus disease amenable to endoscopic surgery. This residual disease is thought to be important in the pathogenesis of recurrences of sinusitis. The patients were taking antibiotics and were clinically well at the time of the two examinations (performed on the same day). Findings on slightly over 80% of the CT scans were abnormal. In about 75% of the patients, the findings on plain radiographs did not correlate with those on CT scans. About 45% of the patients had normal findings on plain radiographs of at least one sinus with an abnormality of that sinus shown on CT scans. Almost 35% of the patients had what was interpreted as an abnormality of at least one sinus on plain radiographs, but that sinus was normal on CT scans. Sinusitis in infants and children is often underdiagnosed or overdiagnosed on the basis of findings on plain radiographs of the sinuses. Plain radiographs cannot be used to determine the need for, or to guide, endoscopic surgery on the sinuses.     

Comparison of MR imaging, CT, and angiography in the evaluation of the enlarged cavernous sinus

Twenty-one patients with enlargement of the cavernous sinus were studied with CT and MR imaging. Eighteen of the patients also had cerebral angiography. MR was superior to CT in differentiating parasellar aneurysms from neoplastic masses. MR was also superior to both CT and angiography in defining the relationships of cavernous sinus neoplasms to the internal carotid artery, pituitary gland, optic chiasm, infundibulum, and fifth cranial nerves. Only in the definition of bone erosion or hyperostosis was MR inferior to another method (CT). We conclude that MR should be the initial diagnostic study in patients with symptoms of a parasellar mass, with supplementation when necessary by CT and angiography.     

Magnetic resonance imaging of the optic nerves and chiasm

Magnetic resonance imaging (MR) of the optic nerves and chiasm was compared with computed tomography (CT) in 4 healthy volunteers, 4 patients without orbital or chiasmal abnormalities, and 4 patients with tumor (anterior clinoid meningioma in 2, optic nerve glioma in 1, and optic nerve sheath meningioma in 1). MR was found to be effective in demonstrating the optic nerves and related structures, particularly the intracanalicular portion of the nerve which is difficult to see with CT. Best results were achieved with partial saturation recovery (SR) images; inversion recovery (IR) and spin echo (SE) techniques were less successful because of decreased spatial resolution (in the case of SE) as well as difficulty in seeing the anterior clinoid processes. As axial views cannot always distinguish the ethmoid sinus tissue from the optic nerve, it may be necessary to employ both axial and coronal images.     

Cavernous sinus invasion by pituitary adenomas

One hundred ninety-eight surgically explored pituitary adenomas were evaluated preoperatively by high-resolution computed tomography (CT). At surgery, evidence of direct cavernous sinus invasion was demonstrated in 19. CT findings in these cases included cavernous sinus expansion (17 patients) and visible encasement of the internal carotid artery (14 patients). The invasive tumor often enhanced to a lesser degree than the cavernous sinuses and ipsilateral internal carotid artery. Intracavernous cranial nerve compression, obliteration, or displacement (14 patients), invasion of the lateral wall of the cavernous sinus (seven patients), and diffuse bone destruction (seven cases) were other findings. Magnetic resonance imaging in three patients provided excellent demonstration of intracavernous internal carotid artery encasement, but displacement and obliteration of intracavernous cranial nerves was not shown as well as it was with CT. Histologically, only three patients showed anaplastic features and only one of them had distant metastases. There was no correlation between histologic features, hormone assays, and invasiveness. This experience indicates any type of pituitary adenoma, regardless of its endocrinologic activity, can invade the cavernous sinus. Cavernous sinus involvement makes complete surgical removal difficult. Preoperative recognition of invasive behavior of these tumors has prognostic value and aids in designing appropriate management. CT is the most useful technique generally available for evaluation and follow-up.     

Protrusion of the optic nerve into the ethmoid and sphenoid sinus: prospective study of 150 CT studies

Damage to the optic nerve is a serious complication of intranasal sinus surgery. Protrusion of the optic canal into the sphenoid sinus is a major risk factor. In this prospective study of 150 CT studies, we found this anatomical variation in 8% of cases. It was consistently associated with pneumatisation of the ipsilateral anterior clinoid process. Protrusion of the optic nerve into the posterior ethmoid cells was never observed. CT is a useful part of the preoperative investigation of patients undergoing intranasal sinus surgery. Axial and coronal images obtained or by direct acquisition by reconstructions are necessary to show the position of the optic nerve.     

Significance of CT and MR findings in sphenoid sinus disease

Disorders of the paranasal sinuses, particularly the sphenoid sinus, can be associated with significant disorders of the optic and other cranial nerves. We examined 100 consecutive routine CT scans, 100 posterior fossa CT scans, and 100 MR scans to look for evidence of sinus disease, especially of the sphenoid sinus. The sphenoid sinus was abnormal in 7% of scans by all methods. Other sinuses were more frequently abnormal, including maxillary (23%), ethmoid (34%), and frontal (16%). Although MR was more sensitive in detecting sinus inflammation in the ethmoid and maxillary sinuses, the frequency of visible sphenoid sinus abnormalities detected by MR was not significantly greater when compared with CT. Of those patients with abnormal sphenoid sinuses, 24% had visual problems associated with the abnormality.     

Tumor invasion of the anterior skull base: a comparison of MR and CT studies

Seven patients who had tumors arising in the anterior face or paranasal sinuses and invasion of the anterior skull base were evaluated with magnetic resonance (MR) and high resolution CT. Magnetic resonance was superior in evaluating tumor encasement of the carotid artery and invasion of the cavernous sinus; for assessing the relationship of the tumor to the anterior brain, optic nerves, and optic chiasm; in providing coronal images free from dental artifact; and in determining tumor extent within the infratemporal fossa. Bone destruction was more easily observed on CT than MR.     

Fat in the normal cavernous sinus

Summary The cavernous sinuses of 17 patients examined by metrizamide CT cisternography with 1.5 mm-thick slices were reviewed. Most of the cavernous sinuses contained fatty components. Anterior lateral end and posterior end of the cavernous sinus are the common sites where the fat is visible.     

Petrosal sinus sampling for Cushing syndrome: anatomical and technical considerations. Work in progress

ACTH-producing microadenomas of the pituitary gland drain unilaterally into the adjacent cavernous sinus; therefore, petrosal sinus sampling to distinguish pituitary from ectopic-ACTH syndromes must always be performed bilaterally. A negative finding from a unilateral petrosal sinus sample does not exclude the presence of a contralateral ACTH-producing microadenoma. Hemiresection of the pituitary gland based on results of bilateral sampling can be performed if the adenoma is too small to be recognized at surgery. Large pituitary adenomas produce elevated ACTH levels in the petrosal sinuses bilaterally. However, if plain radiographs or CT scans provide unequivocally positive findings in Cushing syndrome (less than 20%), inferior petrosal sinus sampling is not indicated.     

Computed tomography of cavernous sinus diseases

Summary We retrospectively analyzed CT scans of 21 cavernous sinus lesions in an attempt to discover CT findings helpful to the differential diagnosis. With the integration of various CT observations it was possible to categorize the lesions into inflammatory, vascular, benign neoplastic and malignant metastatic lesions with few exceptions. Four of 5 cases of septic cavernous sinus thrombophlebitis revealed unilateral or bilateral multiple irregular filling defects in the enhancing cavernous sinus with or without orbital inflammatory change. Four of 5 cases of carotid-cavernous fistula demonstrated unilateral or bilateral diffuse bulging and homogeneous enhancement of the cavernous sinus with obliteration of normal low densities of cranial nerves and gasserian ganglion. Dilatation and tortuosity of superior ophthalmic vein were also associated. Four of 5 cases of benign neoplastic lesion showed well-circumscribed enhancing masses confined to the cavernous sinus with pressure erosion or hyperostosis of adjacent bone. Five of 6 cases of malignant metastatic lesion showed changes suggesting malignancy such as destruction of adjacent bone or associated manifestations of intracranial spread. As compared with the axial scan, coronal scans proved to be more sensitive in detection of subtle cavernous sinus expansion, and superior in evaluation of intracavernous neural structures, relationships with the pituitary gland and changes in the skull base. Axial scans, however, were superior in detection of associated orbital and intracranial abnormalities. Scans in both projections are needed in the evaluation of most cavernous sinus diseases.     

Cranial nerve assessment in cavernous sinus tumors with contrast-enhanced 3D fast-imaging employing steady-state acquisition MR imaging

Introduction  The purpose of this study is to apply contrast-enhanced 3D fast-imaging employing steady-state acquisition (3D-FIESTA) imaging to the evaluation of cranial nerves (CN) in patients with cavernous sinus tumors. Methods  Contrast-enhanced 3D-FIESTA images were acquired from ten patients with cavernous sinus tumors with a 3-T unit. Results  In all cases, the trigeminal nerve with tumor involvement was easily identified in the cavernous portions. Although oculomotor and abducens nerves were clearly visualized against the tumor area with intense contrast enhancement, they were hardly identifiable within the area lacking contrast enhancement. The trochlear nerve was visualized in part, but not delineated as a linear structure outside of the lesion. Conclusions  Contrast-enhanced 3D-FIESTA can be useful in the assessment of cranial nerves in and around the cavernous sinus with tumor involvement.     

鼻咽癌颅内侵犯的CT诊断（附40例分析）

目的探讨鼻咽癌颅内侵犯的CT表现特点。方法搜集经病理确诊为鼻咽癌并伴有颅内占位的CT资料40例。采用SOMATOMPLUS全身CT扫描机行鼻咽部及颅脑检查,38例行轴位扫描,层厚层距均为5mm,2例冠扫,层厚层距均为3mm,其中13例进行了增强扫描。结果（1）鼻咽癌原发病灶40例;（2）中颅窝病变海绵窦不对称,患侧增宽36例;蝶鞍破坏11例;颞极占位5例;（3）后颅窝病变桥脑小脑角区占位病变10例;（4）前颅窝病变1例;（5）颅底骨质破坏33例,其中以破裂孔及卵圆孔破坏、吸收扩大最常见,分别为30例和23例。结论CT可精确显示鼻咽癌颅内侵犯的部位、途径及范围,有助于临床分期及指导放疗野的设置。     

Comparison of the panoramic radiographic and CT features of post-Caldwell-Luc maxillary sinuses

OBJECTIVE: To clarify the panoramic radiographic features of the post-Caldwell-Luc maxillary sinus. METHODS: The panoramic radiographs were compared with the axial CT scans of 48 symptomatic post-Caldwell-Luc maxillary sinuses which had been operated on more than 5 years previously. RESULTS: The two characteristic features of the post-Caldwell-Luc maxillary sinus on panoramic radiographs were a right-angled triangular shape, due to absence of the floor of the maxillary sinus and radiopacity of the posterior wall and zygomatic bone, and an ill-defied panoramic innominate line. This shape was related to the finding of a contracted sinus with a radiolucent lumen on the CT scans. There was also close relationship between the ill-defined panoramic innominate line and thickened posterior wall on the CT scans. CONCLUSION: The characteristic features of the post-Caldwell-Luc maxillary sinus on panoramic radiographs were a right-angled triangular shape and an ill-defined panoramic innominate line. These features were related to a contracted sinus and a thickened posterior wall on the CT scans.     

The foramen lacerum--a route of access to the cranial cavity for malignant tumours below the skull base.

Thirteen malignant neoplasms (seven different tumour types) arising in the postnasal space or surrounding soft tissues extended upwards through the skull base into the middle cranial fossa. Gadolinium-enhanced magnetic resonance imaging (GdMRI) clearly revealed the route of the tumour into the cavernous sinus, parasellar region and floor of the middle cranial fossa. Since this extension alters both management and prognosis, GdMRI in the coronal plane is a necessary investigation for persistent and unexplained facial pain in order to demonstrate such lesions of the trigeminal nerve. Differentiation between neoplasms and aggressive inflammatory disease may be difficult.     

Endoscopic paranasal sinus surgery: radiographic evaluation of severe complications.

PURPOSE: To report our experience with the radiographic evaluation of severe complications resulting from the functional endoscopic sinus surgery (FESS) procedure. PATIENTS: Ten major complications were reviewed retrospectively. FINDINGS: Ten major complications occurred. Eight of 10 had injury to the floor of the anterior cranial fossa, fovea ethmoidalis (roof of the ethmoid sinus), or roof of the sphenoid sinus. Six patients presented with meningitis or rhinorrhea, two presented with headache and massive pneumocephalus; one patient who presented with meningitis had a large nasal frontal encephalocele. Noncontrast brain CT that included the paranasal sinuses adequately evaluated the source of pneumocephalus. Thin-section coronal CT accurately predicted the site of leak in five patients. Both coronal sinus CT and MR imaging were useful to confirm the nasal encephalocele. Two of 10 had vascular injury secondary to FESS. One patient presented with subarachnoid hemorrhage seen on noncontrast CT and cerebral angiography demonstrated an aneurysm of the anterior cerebral artery. The second patient suffered severe intraoperative hemorrhage. Emergency angiography revealed a pseudoaneurysm of the cavernous carotid artery, and balloon occlusion of the artery was performed. No deaths occurred in this series. CONCLUSION: Radiologists should be familiar with the rare, but potential complications of this commonly performed procedure in order to help direct the work-up in an efficacious manner.