Complementary use of computed tomography and magnetic resonance imaging in assessing skull base lesions.

Twenty-six patients underwent computed tomography (CT) and magnetic resonance imaging (MRI) of skull base lesions at the Cleveland Clinic Foundation. CT provided improved bone detail, documenting invasion of the lamina papyracea, orbital floor, fovea ethmoidalis, cribriform plate, pterygoid plates, hard palate, and skull base. MRI defined invasion of the orbit, dura, brain, and cavernous sinus. Improved soft-tissue-tumor interface was evident on MRI. MRI was superior to CT in determining carotid artery involvement. MRI distinguished between tumor and retained secretions in the paranasal sinuses. Combining radiographic tumor staging reliably predicted surgical findings; however, MRI consistently yielded sufficient diagnostic information and the additional expense of performing two imaging procedures may not be justified.     

Value of magnetic resonance imaging in assessing bone destruction in head and neck lesions

We utilized low-field magnetic resonance imaging (MRI) to evaluate 12 patients with head and neck lesions and suspected skull base or facial bone destruction. All except one had high resolution computed tomography (CT). MRI was performed on a 0.15 tesla (low-field) resistive unit, with routinely good resolution due mainly to the use of specially designed rf receiver coils (surface coils). T1 and T2 weighted spin echo images were performed in all cases. In three instances axial, coronal, and sagittal images were done. All CTs were done with high resolution techniques on state-of-the-art equipment. Comparison of the CT and MR images (at low-field strength) showed that MRI's main strength lies in its freedom to perform images in any plane and to visualize intracranial lesions with early brain involvement. Otherwise, the two modalities are comparable. Bone destruction seen on CT was always detectable on MRI, although CT is clearly superior in resolving bone detail. MRI is recommended when direct coronal CT scans are not obtainable to evaluate superiad tumor extension. The improved visualization of nasopharyngeal soft tissue and cavernous sinus region is likely to make MRI the examination of first choice in evaluating lesions of the nasopharynx, skull base, and cavernous sinus.     

Innovations in neuroimaging of skull base pathology

Recent advances in CT and MR technology have allowed detailed imaging of the skull base with greater diagnostic accuracy. Innovations such as multidetector volumetric CT scanners with 3-D reconstructions provide soft tissue and bony detail with very high resolution for small structures such as the neural foramina. CT angiography can assess vascular structures noninvasively, and CT perfusion can help differentiate between malignant and benign tumors. MR technology has provided high-resolution, rapid volumetric sequences that are useful in skull base imaging. MR angiography and MR venography can also assess vascular structures noninvasively. PET scanning and CT/PET scanning will increasingly become a mainstay of head and neck tumor imaging for initial staging, monitoring response to therapy,and detecting recurrent disease or metastases. Many more diagnostic imaging options are available to the head and neck surgeon today than ever before.     

Three-dimensional magnetic resonance imaging in skull base lesions

Three-dimensional (3D) magnetic resonance (MR) imaging is a new digital technique developed 2 years ago by a multidisciplinary group of head and neck surgeons, clinical radiologists, and mathematicians at the University of Munich. In this study, the clinical value of this method, which has been improved significantly during the last 9 months, is evaluated in lesions of the skull base. Our results indicate that 3D reconstruction based on two-dimensional (2D) MR images reveals topographic details of interesting structures. In addition, this method offers new possibilities for the preoperative planning of tumor resection, particularly in lesions close to the skull base. However, this imaging technique will have to be improved before it achieves widespread clinical use.     

Height and shape of the skull base as risk factors for skull base penetration during endoscopic sinus surgery

OBJECTIVES: Computed tomography (CT) and magnetic resonance imaging have identified several risk factors for life-threatening complications of skull base penetration during endoscopic sinus surgery (ESS). We compared these risk factors between groups of patients with and without penetration. METHODS: We performed a retrospective review of direct coronal paranasal sinus CT scans. Using preoperative CT scans of 100 patients without and 7 patients with penetration, we classified height into 4 groups and contour into 2 groups. The frequencies of shape and height differences of the right and left halves of the skull base were calculated in each group. RESULTS: In 6 of the 7 patients who had skull base penetration, ESS was performed by a resident or junior staff member who had less than 3 years of experience with this technique. Shape asymmetry was seen in 4 of the 7 patients (57%) with penetration, which was a significantly higher rate than in patients without penetration (18 of 100; p = .032). The frequencies of a low skull base and a height difference were 15% and 28%, respectively. CONCLUSIONS: The most important risk factor for skull base penetration was the surgeon's inexperience. An asymmetry of shape of the right and left halves of the skull base was significantly related to inadvertent skull base penetration during ESS.     

Congenital cholesteatoma of the mastoid temporal bone

OBJECTIVE: Congenital mastoid cholesteatomas are rare lesions of the temporal bone. The clinical presentation of these lesions is variable, making them difficult to identify preoperatively. We evaluated our series of mastoid congenital cholesteatomas (CCs) in an effort to better define the clinical presentation, imaging characteristics, and surgical challenges specific to this lesion. STUDY DESIGN: Retrospective chart and radiologic study review. METHODS: The medical records of patients with the diagnosis of mastoid CC on radiologic imaging over a 15-year period were reviewed. All had surgical and pathologic confirmation. Eight patients underwent preoperative computed tomography (CT). Six also underwent magnetic resonance (MR) scanning. Demographic information, clinical presentation, imaging results, and operative findings were recorded. RESULTS: Nine patients with the diagnosis of mastoid CC satisfying the inclusion criteria were found. Clinical findings were variable, with the most common presentation being an incidental finding. Imaging findings were more uniform. All CT scans demonstrated an expansile, well-circumscribed mass centered within the mastoid portion of the temporal bone. All MR scans showed a well-circumscribed mass with high intensity on T2-weighted images with precontrasted T1 sequences showing the lesion to be isointense or slightly hyperintense to cerebrospinal fluid (CSF). Operative findings included lateral mastoid cortex erosion, sigmoid sinus exposure, ossicular destruction, facial nerve exposure, and associated postauricular abscess. Management of these lesions is reviewed. CONCLUSION: Congenital mastoid cholesteatomas have a variable and nonspecific clinical presentation. Surgical challenges arise from the indolent nature of this clinical entity, which belies the extent of otologic involvement. Imaging with CT and magnetic resonance imaging are diagnostic, defines the extent of these lesions, and facilitates preoperative surgical planning.     

颅底炎性假瘤的诊断和治疗——附2例报道

目的探讨颅底炎性假瘤的诊断和治疗方法。方法报道2004年和2006年在我科诊治的2例颅底炎性假瘤,并结合文献对该病的临床表现、病理学特点、影像学特征、治疗方法及疗效进行总结分析。结果颅底炎性假瘤侵袭性的临床表现易误诊为恶性肿瘤,在病理学上无特异性的表现,在影像学上表现为T2加权低信号,治疗效果不佳,容易复发。结论T2加权低信号是颅底炎性假瘤的影像学特征,颅底炎性假瘤的治疗应根据自身特点,进一步优化治疗方案。     

Value of secondary coronal reconstructions in computed tomography of the paranasal sinuses

INTRODUCTION: Before sinus surgery, computed tomography (CT) of the paranasal sinuses and anterior skull base is a standard procedure in the diagnostic evaluation. However, coronal sections necessary for the analysis of the complex anatomy of this region are often not applicable in multiple injured or elderly patients due to the impossibility to maintain the required position for the coronal scans. Secondary coronal reconstruction of primary axially acquired scans could help to overcome this problem. This technique was, however, hampered so far by an insufficient resolution in case of conventional CT. We therefore compared the quality of primary coronally acquired conventional CT images with the resolution of multiplanar reformatted coronal images of primary axially acquired scans by means of a new CT generation, the Multidetector Computed Tomography (MDCT). MATERIAL AND METHODS: 10 patients were each examined with conventional CT or MDCT respectively. The quality of primary coronally acquired conventional scans (CT) versus secondary coronal reconstructions (MDCT) was compared by evaluating typical anatomic landmarks. RESULTS: As compared to conventional CT, the coronal reconstruction of primary axially acquired scans by means of MDCT revealed an equal resolution and additionally no essential impairment by amalgam artefacts. CONCLUSION: Our results demonstrate the excellent quality of secondary coronal reconstructions by means of MDCT in the CT evaluation of the paranasal sinuses and the anterior skull base as compared to primary coronally acquired images via conventional CT.     

Invasion of the skull base by carcinomas: histopathologically evidenced findings with CT and MRI

The depth and extent of the invasion of the skull base by a tumor are the most critical information for successful en bloc resection of the tumor. The only means available for the evaluation of these factors are CT or MRI images. In order to clarify the ability of these imaging modes to delineate the invasion of the skull base, preoperative images of ten patients who underwent en bloc resection of skull base tumors at Kobe University Hospital were compared with the histopathological findings of the resected specimens. CT proved to be superior to MRI for evaluating bone destruction of the skull base. On the other hand, MRI provided more useful information about intracranial invasion than CT. As a hypertrophic linear shadow on Gd-enhanced MRI represented dural invasion or thickened dura mater adjacent to the tumor, this technique should be taken into consideration to determine the dural resection. We concluded that preoperative evaluation of the depth of skull base invasion by both CT and Gd-enhanced MRI is essential for planning complete tumor resection.     

Three-dimensional computed tomography angiography of the internal carotid artery for preoperative evaluation of sinonasal lesions and intraoperative surgical navigation

INTRODUCTION: Three-dimensional computed tomographic angiography (3DCTA) demonstrates the spatial relationships of the internal carotid artery (ICA) and adjacent skull base. This imaging modality may be incorporated into intraoperative surgical navigation during endoscopic skull base surgery. METHODS: The charts of patients who had undergone 3DCTA imaging between July 2002 and February 2005 were reviewed. For 3DCTA, 1 mm axial computed tomography (CT) scan images were obtained with simultaneous intravenous contrast bolus on a multidetector CT scanner (Somatom Sensation 16, Siemens, Munich, Germany). The CBYON Suite version 2.6 to 2.8 (Med-Surgical Services, Mountain View, CA) was also used for creating CTA images through its volume-rendering protocols. RESULTS: A total of 22 3DCTA studies were performed for diagnostic evaluation or preoperative planning. In 18 instances, the 3DCTA images were used during intraoperative surgical navigation. The specific indications for obtaining the 3DCTA study included neoplasm (11 cases), cerebrospinal fluid leak (3 cases), fibro-osseous lesion (2 cases), mucocele (2 cases), and other (4 cases). Images generated by 3DCTA facilitated the definition of the anatomic relationships between the ICA and skull base lesion. During intraoperative surgical navigation, the 3DCTA provided critical information about the ICA location and adjacent skull base anatomy in the operative field. CONCLUSIONS: 3DCTA is a useful means for assessing the ICA and its relationship to skull base lesions. Incorporation of 3DCTA into intraoperative surgical navigation facilitates the comprehension of operative field anatomy in the ICA region. As a result, this imaging technique, especially when combined with intraoperative surgical navigation, may extend the applications of minimally invasive endoscopic approaches to the skull base.     

Intraoperative magnetic resonance imaging for skull base surgery

OBJECTIVES/HYPOTHESIS: Skull base surgery has evolved over the past several decades. Major improvements in the imaging of skull base pathology led to better target localization and better surgical planning. The objectives of this study were to assess the use of intraoperative magnetic resonance (MR) imaging in the management of a series of patients with skull base pathology. We hypothesized that high-quality intraoperative MR imaging would have an impact on surgery in this patient group. STUDY DESIGN: Prospective, non-randomized, cohort study. METHODS: Thirty-one patients with skull base lesions underwent surgery in a 1.5-Tesla intraoperative MR suite. The concepts of a moving magnet, high magnetic field strength, and radiofrequency coil design are presented. RESULTS: Eleven of 31 patients had the course of surgery significantly altered by the information acquired from the images obtained during surgery. CONCLUSIONS: Intraoperative MR imaging is a valuable adjunct to skull base surgery. One third of patients had altered surgery as a result of this adjunct. Intraoperative MR imaging is of particular value in the treatment of pituitary adenomas and benign skull base tumors.     

Radiographic evaluation of the skull base.

The anatomic complexities of the skull base and the variable clinical presentation of skull base tumors often precludes accurate determination of tumor boundaries by history and physical alone. Imaging, employing computed tomography (CT) and magnetic resonance imaging (MR) allows for accurate tumor mapping and planning of appropriate therapeutic intervention. Calvarium floor involvement and extracranial lesions are well delineated by CT. While multiplanar MR is unparalleled in demonstrating tumor boundaries and extension through the skull base. In order to employ these imaging modalities in an efficient way, it is important to understand the limitations and capabilities of these modalities as well as the imaging characteristics of common skull base lesions.     

Clinically-directed ct in occult disease of the skull base involving foramen ovale

Occult disease of the skull base may present as an isolated neurogenic symptom in the absence of physical signs or radiologic findings. It therefore often remains undiagnosed until advanced. Computed tomography (CT) provides the potential for diagnostic imaging far beyond conventional radiology. Not only do current generation scanners provide exquisite bone detail, they also provide the capability of soft tissue imaging. In the past year, we have matched the diagnostic problem of occult disease of the middle fossa skull base and its foramina with the potential diagnostic imaging solution of CT. Five patients were referred with possible occult middle fossa skull base disease — all had persistent unilateral facial paresthesia in the distribution of one of the lower two trigeminal nerve divisions (V2, V3) as their only complaint; all had previously been extensively investigated (including axial CT); all remained undiagnosed. Utilizing clinically-directed CT (based on acoustic neuroma diagnostic index of suspicion and imaging experience), 2 of the 5 patients were found to have small mass lesions involving foramen ovale. This presentation will demonstrate our experience based on image-manipulated CT, actively monitored by both radiologist and otolaryngologist.     

增强MRI联合DWI序列对恶性肿瘤侵犯甲状软骨的诊断价值研究

目的探讨增强MRI联合DWI序列对喉癌和下咽癌患者的甲状软骨受累诊断价值,为制定合理的治疗方案及术中的具体处理提供重要的参考价值。方法选取自2013年1月~2014年12月在首都医科大学附属北京同仁医院头颈外科197例住院并行手术的原发喉癌及下咽癌患者,所有患者术前均行增强MRI检查,以组织病理学的结果作为金标准,计算增强MRI对喉癌和下咽癌患者的甲状软骨是否受累判断的敏感性、特异性、阳性预测值及阴性预测值,如果MRI判断为甲状软骨受累,还进一步判断肿瘤侵犯甲状软骨范围;影像学结果与病理对比分析并计算敏感性、特异性、阳性预测值及阴性预测值。所得数据并进行统计学分析。结果197例患者均行手术治疗,术后病理示63例患者（32.0%）甲状软骨受肿瘤侵及。MRI判断肿瘤侵犯甲状软骨与病理结果比较其敏感性、特异性、阳性预测值、阴性预测值分别为94%、87%、78%、97%。MRI判断肿瘤侵犯甲状软骨内板与病理结果比较其敏感性、特异性、阳性预测值、阴性预测值分别为90%、82%、61%、96%。MRI判断肿瘤侵犯甲状软骨外板与病理结果比较其敏感性、特异性、阳性预测值、阴性预测值分别为89%、84%、57%、97%。MRI对于甲状软骨内板和外板受累诊断结果的Kappa值分别为0.62和0.60。结论对于局部晚期喉癌或下咽癌是否侵犯甲状软骨的术前诊断中,可以采用常规序列联合SE EPI扩散加权成像弥散序列的MRI诊断。同时应用MRI对肿瘤侵犯甲状软骨范围进行诊断具有可行性。     

Clinical applications of three-dimensional CT images for diseases of the anterior and middle cranial base

CT scanning has made significant contributions to the diagnostic, therapeutic and prognostic aspects for the managements of the lesions in the paranasal sinuses and the orbit. The current availability of 3-D imaging reformatted from CT scans has added a new dimension to anatomic investigations and pre- and postoperative evaluations of the skull base structures. Twenty-five craniomaxillofacial 3-D CT examinations were performed during the year of the 1989 for the purpose of the diagnosis of the pathology, surgical planning and postoperative evaluation in reconstructive surgery of the skull base. Results: 1. The use of 3-D CT improves the display of the location and volume of the pathology and affords the accurate therapeutic and surgical planning. 2. Preoperative 3-D CT imagings are useful for the display of the bony erosion of the skull base. Stereotaxic 3-D CT imagings are particularly appreciated in the diagnostic aspects of the management of the pathology. 3. In the reconstructive surgery of the skull base, an accurate prefabricated model of the bony defect can be made to aid the surgery. 4. A major limitation of 3-D CT is its inability to reconstruct the pathology of soft tissues with the same fidelity afforded bony structures.     

侵犯眼眶及颅底的鼻窦囊肿的诊断和治疗

目的：总结侵犯眼眶及颅底的鼻窦囊肿的诊断和治疗要点。方法：回顾性研究侵犯眼眶及颅底的30例鼻窦囊肿患者的临床资料。均行CT和MRI检查。所有患者均在鼻内镜下进行手术,其中4例加用了辅助切口。术后均使用激素治疗并常规行鼻内镜复查。结果：所有患者均顺利完成手术,无并发症发生,术中出血50-150ml。术后患者眼球突出、复视、眼球运动障碍、头痛、鼻塞等症状明显改善或痊愈。随访2年以上,除1例患者在术后3个月出现复发外,其他均未复发。结论：鼻内镜手术是治疗鼻窦囊肿的有效方法,术前影像学检查对其诊断、手术难度的估计和器械的准备非常重要。为将囊肿内容物彻底清除及改善外观,合适的辅助切口是必要的。     

Efficacy of controlling rhinosinusitis on the prevention of complications in pituitary surgery with transsphenoidal approach

Objective

The microscopic transcolumellar transseptal transsphenoidal approach (TSA) is the one of the most widely used methods for the surgical treatment of sellar and parasellar lesions. But nasal and paranasal sinus inflammation is the relative contraindications of TSA. This study was performed to investigate the results of pre TSA treatment options according to the degree of nasal and paranasal sinus inflammation on the paranasal sinus computed tomography scan (PNS CT).

Methods

From January 2005 to September 2010, 145 consecutive patients underwent operation of pituitary lesions through the TSA. The preoperative CT images for these patients were reviewed, and 26 patients were identified with sinus opacification on PNS CT. We then analyzed presenting symptoms, physical and endoscopic examination, Lund–Mackay score on PNS CT and preoperative management of the sinus problem retrospectively.

Results

Twenty-six patients had sinus opacification on PNS CT. Eight patients had the symptoms of sinusitis corresponding to PNS CT finding, so they had therapeutic antibiotics, and had TSA after symptomatic improvement. Three patients had the symptoms of sinusitis and sinus opacification with mean Lund–Mackay score of 5.33, so they underwent endoscopic sinus surgery first, and they got TSA a few months after. One patient underwent endoscopic sinus surgery and TSA simultaneously. No patient had a serious complication including intracranial infection.

Conclusion

TSA is a relatively safe technique, but intracranial complication after surgery may be fatal. Therefore rigorous evaluation and management is mandatory. It is especially important to treat rhinosinusitis issues preoperatively. Our preliminary data may be helpful to evaluate and manage the paranasal sinus inflammation before TSA.     

Paranasal sinus malignancy: a comprehensive update

A retrospective analysis of 60 cases of paranasal sinus cancer in patients admitted between 1970 and 1985 was undertaken. Forty-six tumors originated in the maxillary sinus, and 14 originated in the ethmoid sinuses. Computed tomography, magnetic resonance imaging, and endoscopic sinus examination aided in early diagnosis of sinus cancer. Computed tomography aided in staging tumors; Caldwell-Luc alone was inadequate for staging tumors invading deeper sites such as the orbits or pterygoid muscle. There were 15 early (T1 or T2) and 31 advanced (T3 or T4) maxillary sinus cancers. Multimodality therapy incorporated radiation, surgery, and chemotherapy. The 5-year survival rate was 49%. We prefer preoperative radiotherapy for advanced lesions and postoperative radiotherapy for early lesions. The use of preoperative radiation therapy has increased our globe salvage rate. All but one of the patients who developed recurrent disease showed recurrence at the primary site prior to developing regional or distant metastasis. Radiation therapy, combined with aggressive surgical management to remove all tumor, provided the best survival rates in advanced lesions.     

Primary B cell lymphoma of the sphenoid sinus: CT and MRI characteristics with correlation to perfusion and spectroscopic imaging features

Primary non-Hodgkin lymphoma (NHL) of the paranasal sinuses is a rare neoplasm that cannot be easily diagnosed and differentiated as its clinical, histological, and imaging features are similar to those of other inflammatory and tumorous diseases in their early stages. We evaluated the morphological and functional imaging characteristics of primary NHL of the sphenoid sinus using CT and MR imaging. Morphological CT and MR imaging as well as perfusion CT imaging and proton MR spectroscopy (PRESS technique, TE = 135) was performed in three patients with the histological diagnosis of highly malignant primary B cell lymphoma of the sphenoid sinus. In all patients an inhomogeneous contrast agent enhancement as well as bony erosion of the sphenoid sinus was identified in CT and MR sections. In one patient an infiltration of the adjacent dura was present. The mean blood flow of the lymphomas was 135 ml/min per 100 g tissue, the mean blood volume was 8.06 ml/min, while the mean transit time and the mean permeability surface area product values were 5.11 s and 26.53 ml/min per 100 g, respectively. The mean choline to creatine ratio in the proton MR spectroscopy was 5.7. Cross-sectional imaging findings are not sufficient to establish the diagnosis of a primary NHL in the sphenoid sinus. Physiologic imaging offers valuable information that may be characteristic of the tumor. Future studies may lead to a safe differentiation of the lymphomas from other pathologic entities based on the combination of morphological and functional imaging.