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.     

A comparison of CT and MRI in the assessment of the pituitary and parasellar region

We have carried out a prospective study to compare high resolution thin slice, contrast-enhanced, axial computed tomography (CT) with unenhanced magnetic resonance imaging (MRI) at 1.5T in the assessment of the pituitary and parasellar region. Forty patients with suspected pituitary disease presenting to an endocrine unit were studied. MRI was superior to CT for the identification of the posterior pituitary and pituitary stalk and was better at showing the cystic nature of tumours. Visualization of the optic chiasm and assessment of displacement of the optic chiasm and the carotid arteries were also better with MRI. CT was equally good at showing cavernous sinus displacement or invasion, sphenoid sinus invasion and erosion of the floor of the sella turcica and was the only technique able to show calcification of the gland. More focal abnormalities were seen in the pituitary gland with CT than with unenhanced MRI, but there was a higher false positive rate for microadenoma detection with CT. All the scans were interpreted separately by three observers, two radiologists and one clinician. The percentage agreement between the observers for the identification of pituitary and parasellar structures was better for MRI than for CT and the clinician in particular found interpretation of the MR images easier. MRI thus not only gives more information overall than CT but it is a more reliable technique between different observers for the assessment of the pituitary and parasellar region.     

Origin of high signal intensity in the cavernous sinus in MR angiographic source images: correlation between MR and conventional angiography

OBJECTIVE: To investigate the origin of a high signal intensity in a cavernous sinus on magnetic resonance (MR) angiography. METHODS: Time-of-flight MR angiography was performed in 20 patients scheduled for conventional angiography for disease not related to carotid cavernous fistula. Venous drainage pattern was assessed, and flow rate to a cavernous sinus was semiquantitatively evaluated on conventional angiography. RESULTS: Two sinuses showed high signal intensity in the anterior portion. These were associated with direct venous drainage to the anterosuperior aspect of the cavernous sinus from the superficial middle cerebral vein, and their flow rates were among the 10% of the sides with the highest flow rates. Two other sinuses showed high signal intensity in the posterior portion. Their flow rates from the superficial petrosal sinus were also among the 10% of the sides with the highest flow rates. CONCLUSION: High signal intensity in the anterior or posterior portions of the cavernous sinus is probably a result of inflow from the superficial middle cerebral vein and the superior petrosal sinus, respectively.     

High-resolution MR imaging of juxtasellar meningiomas with CT and angiographic correlation

The purpose of this study was to compare the relative merits of MR imaging, CT, and angiography in the preoperative evaluation and postoperative follow-up of patients with juxtasellar meningiomas. High-resolution MR studies in nine patients with juxtasellar meningiomas were evaluated and compared with CT and angiography. The techniques were compared for the evaluation of suprasellar, parasellar, and intrasellar extension, as well as for vascular displacement or encasement, postoperative recurrence or residual calcification, and bone changes. MR provided additional information considered significant by the neurosurgeon when compared with CT, and MR was considered superior to CT in the juxtasellar area. Although MR does not obviate angiography, in many cases angiographic findings were predictable by MR.     

颅内动静脉瘘的CT和MRI诊断价值

目的:探讨CT和MRI对颅内动静脉瘘的诊断价值。方法:回顾性分析18例颅内动静脉瘘的CT和MRI表现。18例均经DSA检查明确诊断。其中12例行CT检查;16例行MRI检查,同期6例行MRA检查。结果:颅内动静脉瘘的CT和MRI的特征性表现为脑沟、脑裂、基底池内血管影增粗、增多,呈散在分布,受累及的静脉窦增粗,且病变区没有畸形血管团。海绵窦硬脑膜动静脉瘘在T2WI上表现为局部流空信号增宽,MRA原始图像显示局部有较丰富的异常纤细血流信号。结论:认识颅内动静脉瘘的CT和MRI表现,有助于早期诊断及治疗。MRI对显示软脑膜血管扩张优于CT。选择性脑血管造影是确诊本病的可靠手段。     

Cavernous sinus and inferior petrosal sinus flow signal on three-dimensional time-of-flight MR angiography.

BACKGROUND AND PURPOSE: Venous flow signal in the cavernous sinus and inferior petrosal sinus has been shown on MR angiograms in patients with carotid cavernous fistula (CCF). We, however, identified flow signal in some patients without symptoms and signs of CCF. This review was performed to determine the frequency of such normal venous flow depiction at MR angiography. METHODS: Twenty-five 3D time-of-flight (TOF) MR angiograms obtained on two different imaging units (scanners A and B) were reviewed with attention to presence of venous flow signal in the cavernous sinus or inferior petrosal sinus or both. Twenty-five additional MR angiograms were reviewed in patients who had also had cerebral arteriography to document absence of CCF where venous MR angiographic signal was detected, as well as to gain insight into venous flow patterns that might contribute to MR angiographic venous flow signal. Differences in scanning technique parameters were reviewed. RESULTS: Nine (36%) of the 25 MR angiograms obtained on scanner A but only one (4%) of the 25 obtained on scanner B showed flow signal in the cavernous or inferior petrosal sinus or both in the absence of signs of CCF. On review of 25 patients who had both MR angiography and arteriography, three patients with venous signal at MR angiography failed to exhibit CCF at arteriography. CONCLUSION: Identification of normal cavernous sinus or inferior petrosal sinus venous signal on 3D TOF MR angiograms may occur frequently, and is probably dependent on technical factors that vary among scanners. The exact factors most responsible, however, were not elucidated by this preliminary review.     

Tributary venosinus occlusion and septic cavernous sinus thrombosis: CT and MR findings.

PURPOSEIn autopsy reports of patients who died of septic cavernous sinus thrombosis, tributary venosinus occlusion has been a common finding related to intracranial inflammatory complications. The purpose of this article is to illustrate the MR and CT appearance of septic cavernous sinus thrombosis and tributary venous occlusion.METHODSOver a period of 7 years, eight patients with septic cavernous sinus thrombosis were examined by contrast-enhanced thin-section CT. The CT scans of these eight patients and those of 30 healthy control subjects were assessed independently and subjectively by two blinded readers to ascertain the presence, size, and density of areas of nonopacification within the cavernous sinus and the presence of filling defects and dilation of tributary veins and venous sinuses. In six subjects, MR images supplemented by a contrast-enhanced spoiled gradient-recalled acquisition in the steady state (SPGR) sequence were assessed with respect to the presence of filling defects, expansion, and signal abnormalities within the cavernous sinus and tributary veins and sinuses. The MR and CT findings were compared.RESULTSThe CT studies of the eight patients were consistently differentiated from those of the control subjects by the two readers. Contrast-enhanced CT findings in patients included areas of nonopacification that were present within the cavernous sinus bilaterally in six cases and unilaterally in two. The size of the filling defects exceeded 7 mm in 76% of thrombosed cavernous sinuses compared with 9% of control subjects. The mean density of filling defects in patients differed significantly from those in control subjects. Comparison of the MR and CT findings in six cases showed the contrast-enhanced SPGR sequence to be equivalent to CT with respect to delineation of filling defects.CONCLUSIONContrast-enhanced high-resolution CT findings indicate that venosinus thrombosis associated with septic cavernous sinus thrombosis is not restricted to the superior ophthalmic vein and is more common than previously assumed. A contrast-enhanced SPGR MR sequence may be used as a reliable alternative to establish the diagnosis of cavernous sinus and tributary venosinus thrombosis.     

MR imaging of pituitary adenoma: CT, clinical, and surgical correlation

Twenty-five patients with suspected pituitary adenoma were evaluated prospectively with CT and MR. Nine patients underwent transsphenoidal surgery, and three of these showed a documented decrease in size of mass on bromocriptine therapy. CT was more sensitive than MR for detecting focal lesions (seven vs three) and sellar-floor erosion (12 vs six). MR was superior to CT in identifying infundibular abnormalities (seven vs six), focal abnormalities of the diaphragma sellae (10 vs seven), cavernous sinus invasion (four vs two), and optic chiasm compression (six vs zero). Thus, MR may be the procedure of choice for optimal identification and localization of macroadenoma. For patients with suspected microadenoma, however, this preliminary series indicates that CT remains the radiographic procedure of choice.     

Roentgenological investigation of cavernous sinus structure with special reference to paracavernous cranial nerves

Summary We have evaluated the anatomical structure of cavernous sinuses in parasellar blocks obtained from adult cadavers to gain clinically useful information. Ten microdissectional studies of parasellar blocks (20 sides of cavernous sinus) were carried out with special emphasis on the course of paracavernous cranial nerves (3rd to 6th). These were also examined on plain radiographs. Secondly, CT investigations of the cavernous sinuses (notably as to paracavernous cranial nerves) were undertaken in twenty clinical cases having presumed parasellar lesions and in three parasellar blocks from cadavers. The results from microdissectional studies and plain radiographs were as follows. It was found that the 3rd cranial nerve entered the lateral wall of the cavernous sinus close to the antero-inferior part of the posterior clinoid on lateral projection. The 4th cranial nerve, on the other hand, entered near the postero-inferior portion of the posterior clinoid on the same view. Variations in Parkinson's triangle were fairly often noted, although marked asymmetry was not seen in individual cases. From CT findings, it was found that a postenhanced, magnified direct coronal study was essential for identifying paracavernous cranial nerves more clearly. The 3rd and 5th cranial nerves were fairly well identified on axial and coronal projections. Careful radiological investigation including plain skull radiographs & CT seems to be of value for those who diagnose or treat parasellar lesions.     

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.     

MR of vascular encasement in parasellar masses: comparison with angiography and CT

The relationship between tumor mass and vascular involvement as seen on MR imaging was examined in 11 patients with masses in the parasellar region, and the findings were correlated with CT and angiography. In six cases, MR was superior to CT and angiography in depicting the relationship of the tumor to adjacent blood vessels. In these cases, MR demonstrated tumor surrounding the blood vessel without changing the diameter of its lumen. Angiography did not reveal encasement in these cases. In four cases, both MR and angiography showed signs of vascular encasement with narrowing of the vessel's lumen. In two cases, MR was equivocal while angiography revealed vascular encasement in one case and was negative for encasement in the other. CT was less sensitive than MR in defining vascular encasement since there is usually little contrast between an enhancing tumor and the major blood vessels. Coronal scanning appeared to be the best plane of imaging and correlated well with the anteroposterior angiogram. We propose that MR is the method of choice for evaluating arterial encasement by tumors and may obviate the need for angiography in those cases in which MR is positive for a basal lesion.     

Dynamic CT scanning for the evaluation of pituitary tumor invasion to the cavernous sinus

A CT method for evaluating cavernous sinus invasion by pituitary adenomas or parasellar tumors is described. This technique is easily performed without special software. A persistent, isolated visualization of the internal carotid artery seems to indicate invasion of the cavernous sinus.     

Fat deposition in the cavernous sinus in Cushing disease

Fat density in the cavernous sinus on computed tomography (CT) is described in 6 out of 16 (37.5%) patients with Cushing disease. This finding may aid in making a specific diagnosis in patients with a pituitary mass. It was not seen in 30 random CT studies of the sella; however, parasellar fat was incidentally noted in one patient with acromegaly.     

Variations of the superficial middle cerebral vein: classification using three-dimensional CT angiography

BACKGROUND AND PURPOSE: Classification of variations of the superficial middle cerebral vein (SMCV) remains ambiguous. We propose a new classification system based on embryologic development for preoperative examination. METHODS: Three-dimensional CT angiography was used to evaluate 500 SMCVs (in 250 patients). The outflow vessels from the SMCV were classified into seven types on the basis of embryologic development. The 3D CT angiograms in axial stereoscopic and oblique views and multiple intensity projection images were evaluated by the same neurosurgeon on two occasions. Inconsistent interpretations were regarded as equivocal. RESULTS: Three-dimensional CT angiography clearly depicted the SMCV running along the lesser wing or the middle cranial fossa. However, the outflow vessel could not be confirmed as the sphenoparietal, cavernous, or emissary type in 39 (8%) of the sides. SMCVs running in the middle cranial fossa to join the transverse sinus or superior petrosal sinus were accurately identified. SMCVs were present in 456 sides: 62% entered the sphenoparietal sinus or the cavernous sinus and 12% joined the emissary vein. Nine vessels were the superior petrosal type, 10 the basal type, 12 the squamosal type, and 44 the undeveloped type. CONCLUSION: Three-dimensional CT angiography can depict the vessels and their anatomic relationship to the bone structure, allowing identification of the SMCV variant in individual patients. Preoperative planning for skull base surgery requires such information to reduce the invasiveness of the procedure. With the use of our classification system, 3D CT angiography can provide exact and practical information concerning the SMCV.     

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.     

颈内动脉海绵窦段创伤性假性动脉瘤破入蝶窦的CT和MRI诊断

目的评价CT和MRI对颈内动脉海绵窦段创伤性假性动脉瘤（TPA）破入蝶窦的诊断价值.方法对经DSA证实的6例海绵窦段TPA破入蝶窦的CT和MRI资料进行回顾性分析.全部患者均行CT检查,5例行MR检查.结果6例颈内动脉海绵窦段TPA中,CT平扫均显示蝶窦侧壁骨折及其密度增高,2例CT增强扫描均可见蝶窦呈明显均匀强化,强化程度与正常血管一致,海绵窦扩大,1例CT血管成像（CTA）明确显示动脉瘤体与瘤颈.5例行MR SE序列平扫,患者均表现为分层状混杂长T1、混杂长T2信号的血栓,4例尚可见瘤腔内的流空现象;3例增强扫描示蝶窦呈明显均匀强化,强化程度与正常血管一致,其中1例在相位编码方向上流动伪影明显;2例MR血管成像均明确显示瘤体与瘤颈.结论CT和MRI是诊断颈内动脉海绵窦段TPA破入蝶窦的有效非创伤性检查,并可作为手术前后长期随访的良好检查方法.     

MR of craniopharyngiomas: tumor delineation and characterization

MR imaging and CT (with and without contrast enhancement) were performed in 20 patients with an established or clinically suspected diagnosis of craniopharyngioma. Fifteen had biopsy-proven craniopharyngioma and five had presumed craniopharyngioma based on clinical and CT findings. In two cases MR was superior to contrast-enhanced CT in demonstrating the tumor. A variable appearance on T1-weighted MR images reflected the pathologic appearance of craniopharyngiomas. High intensity on T1-weighted images corresponded to high cholesterol content or presence of methemoglobin. MR was the preferred method in the evaluation of tumor extent, especially in the cavernous sinus and posterior clival region. CT was superior to MR in detecting the presence of calcification, which with the clinical history correctly suggested the diagnosis of craniopharyngioma. Both MR and CT studies are desired initially to establish the diagnosis and to evaluate tumor extent. MR was the preferred method in detecting the presence of recurrent tumor.     

MR imaging of cavernous sinus involvement by pituitary adenomas

The ability of high-resolution MR imaging (1.5 T) to detect invasion of the cavernous sinuses by pituitary adenoma was determined through a retrospective review of 74 patients. These patients were divided into three groups: 25 normal subjects, 24 subjects with invasive pituitary adenomas, and 25 subjects with noninvasive pituitary adenomas. A fourth group of 30 patients, who subsequently underwent surgery for pituitary adenoma, was evaluated prospectively by MR for the presence or absence of cavernous sinus invasion. Several features were analyzed: (1) the detectability of the medial and lateral dural margins of the cavernous sinus (2) the size and variation in intensity of compartments within the cavernous sinus (3) the relationship of endocrine function to the surgical and MR appearance of the cavernous sinus and (4) carotid artery displacement or encasement by tumor. The normal cavernous sinuses were usually symmetric, but their sizes varied. The lateral dural margin of the cavernous sinus was always recognized on MR as a linear, discrete, low-intensity area. The medial dural margin (pituitary capsule) was seen on MR in only two of the 25 normal patients. In all 24 patients with cavernous sinus invasion involvement was unilateral and was most common with laterally positioned prolactin or adrenocorticotropic hormone secretory adenomas. Invasion of the cavernous sinus was suspected by MR in only two of the 13 invasive microadenomas and was questionable in three. In 10 of the 11 macroadenomas with surgically proved dural invasion, MR demonstrated an asymmetric increase in size and intensity of the superior and inferior cavernous sinus compartments. Noninvasive macroadenomas compressed and displaced the cavernous sinus bilaterally. The prospective MR evaluation of 30 patients undergoing surgery for pituitary tumor revealed a sensitivity for predicting cavernous sinus invasion of 55%, a specificity of 85.7%, a positive predictive value of 62.5%, and a negative predictive value of 81.8%. No feature permitted certain distinction between invasive and noninvasive microadenomas, as the medial dural wall of the cavernous sinus could not be reliably identified. The most specific sign of cavernous sinus invasion was carotid artery encasement.     

64层螺旋CT对颈内动脉海绵窦瘘的诊断价值

目的探讨64层螺旋CT在颈内动脉海绵窦瘘（ICCF）诊断中的价值。方法回顾性分析我院经血管内栓塞治疗成功的ICCF共16例,所有患者均经64层螺旋CT及DSA检查。结果 CT主要表现：所有患者患侧眼球突出、海绵窦扩大、眼上静脉扩张,部分患者眼下静脉、内眦静脉、面静脉、小脑半球上表面外侧脑膜静脉扩张,岩上、下窦扩张,眼外肌肿胀,眼球壁增厚。利用高级血管处理软件显示直接型瘘10例,间接型瘘6例。结论 64层螺旋CT克服了常规CT对颈动脉海绵窦瘘直接征象的显示并不满意的弱点,可清楚显示颈动脉海绵窦瘘瘘口的位置和大小,同时可以有效地评价Willis环的功能,可为颈动脉海绵窦瘘的诊断、治疗及疗效评价提供有价值的信息。     

The role of MR and CT in evaluating clival chordomas and chondrosarcomas

Sixteen chordomas and nine chondrosarcomas of the clivus were evaluated with CT and MR either before (22 cases) or after (three cases) treatment with proton beam irradiation. The ability of these imaging techniques to provide information necessary to direct patient treatment was studied. The tumor was detected and its gross margins were identified by both techniques in all instances. No reliable diagnostic features allowing differentiation between these two tumors were encountered. MR generally was superior in defining the exact position of the brainstem and optic chiasm relative to the tumor, and it frequently provided superior information about tumor extension into the nasopharynx and cavernous sinus. CT was always better than MR in demonstrating tumoral calcification and in defining the exact anatomy of bone destruction. MR was generally superior to CT in demonstrating the position of the cavernous internal carotid artery relative to the tumor and often provided superior visualization of the vertebral and basilar arteries. In cases in which bone-induced artifact obscured the interface between the neural axis and tumor in the CT image, or in which the tumor had suprasellar extension and was likely to compress the optic chiasm and tracts, MR was of great value in planning irradiation therapy. The high occurrence of clinically asymptomatic signal intensity alterations in the MR studies of previously treated patients appears to limit the differential diagnostic value of this information. Given its greater availability and lower cost, CT appears to be the technique of choice for routine follow-up of previously treated patients.