Imaging of skull base tumors in adults

The skull base is divided into three parts: anterior, central and posterior. Numerous foramina are located in the skull base and transmit important neurovascular structures. Numerous types of tumor can be observed at the skull base. They are classified as anterior, central and posterior skull base tumors. They are also divided into three groups according to their origin: tumors arising from the skull base itself, intracranial tumors and extracranial tumors invading the skull base. Imaging is very important for diagnosis, treatment and follow-up of patients with skull base tumors. Magnetic resonance imaging is the most useful modality as it visualizes the lesion on different planes and permits the planning of therapy. Computed tomography depicts the osseous lesions more precisely and may be necessary before surgery. Catheter angiography is now in most cases replaced by magnetic resonance angiography. Interventional neuroradiology is necessary if the lesion is highly vascularized or if a vessel is encased in the tumor.     

Three-dimensional MR reconstruction images of skull base tumors

Forty-eight patients with skull base tumors were evaluated prospectively with T1-weighted spin-echo two-dimensional (2D) magnetic resonance (MR) sequences, a three-dimensional (3D) MR TurboFLASH (fast low-angle shot) sequence, and a 3D reconstruction window technique. All patients underwent surgery with histopathologic correlation, and the three MR imaging techniques were compared to assess representation of tumor margins and the topographic relationship of tumor to surrounding tissue and adjacent vasculature. The best results were obtained with standard 2D spin-echo sequences after administration of the paramagnetic contrast agent gadopentetate dimeglumine. The 2D MR sequences gave the highest contrast-to-noise ratios, with decreasing values for 3D sequences and 3D reconstructions, respectively. Nevertheless, 3D MR imaging, by virtue of its good representation of adjacent structures, aided surgeons in planning surgical intervention. This study presents the technical features of 3D imaging of the skull base, the choices involved in its implementation, and its potential clinical applications.     

Radiation therapy for metastases to the base of the skull.

The clinical features and management of 46 patients with metastatic involvement of the base of the skull were retrospectively analyzed. Diagnosis could often be made on clinical grounds, with a limited number of investigations necessary. Local treatment with megavoltage radiotherapy relieved symptoms in 78% of patients, with improvement lasting until death in most. Field size and dosage are discussed. The likelihood of response dropped sharply the longer treatment was delayed. Therefore, if the clinical picture is suggestive, treatment should not be withheld even if radiographic investigations are negative.     

颅底肿瘤的MRI诊断

目的分析颅底区域肿瘤的MRI特点,以提高对此部位肿瘤的认识。方法经手术后病理证实的颅底肿瘤63例,回顾性分析其MRI表现。结果脊索瘤10例,转移瘤5例,三叉神经瘤5例,软骨瘤5例,软骨肉瘤2例,鼻咽纤维血管瘤3例,脑膜瘤11例,侵袭性垂体瘤11例,鼻咽癌9例,颈静脉球瘤2例。颅底区域肿瘤MR表现各异,垂体腺瘤、脑膜瘤等少数肿瘤的MR信号具有特征性,肿瘤的位置对定性诊断有一定的帮助。结论颅脑MRI可充分显示颅底区域肿瘤的部位、累及范围,部分肿瘤可依据其信号、部位与侵犯特征作出定性诊断。     

Amyloidoma of the skull base

We report a case of a primary amyloidoma of the skull base. Plain radiography and CT showed a lytic, highly destructive lesion with multiple scattered calcifications within. MR imaging revealed that the tumor was isoto hypointense to muscle on T1-weighted images and extremely hypointense on T2-weighted images. In contrast to two previous reports, marked enhancement after the administration of contrast material was absent. Bone amyloidomas are very rare and are frequently misinterpreted as chondrosarcomas.     

颅底肿瘤的影像学诊断(附121例分析)

目的：分析并总结颅底肿瘤的常见病变及其MR、CT表现。方法：对121例MR检查颅底肿瘤者的临床资料及影像学所见进行回顾性分析。结果：颅底肿瘤的发病率如下：①垂体瘤最多见(27／121)；②鼻咽、副鼻窦恶性肿瘤浸润(16／121)。三叉神经瘤(15／121)和脑膜瘤(14／121)为次好发肿瘤；③转移性肿瘤(7／121)。神经纤维瘤(7／121)。骨纤维异常增殖(6／121)和脊索瘤(6／121)为第三位好发肿瘤；④其它少见病例有颈静脉球瘤。软骨瘤。鼻咽纤维血管瘤和鼻咽纤维肉瘤。他们分别有其相应的CT、MR表现。结论：CT、MR不仅对颅底肿瘤的诊断与鉴别诊断有重要作用。而且在临床决定手术或放疗前对肿瘤的局部和进展范围及其周围关系的正确判定中CT、MR检查是必要的。     

CT studies of tumors of the skull base, facial skeleton and nasopharynx.

Fifty cases of tumors of the base of the skull, facial skeleton and nasopharynx were studied by CT. The tumoral densities were measured and compared to the pterygoid muscle density which was used as reference. Results showed no relationship between tumoral density and histology, and intravenous contrast medium injection was not useful. CT, however, does offer many advantages in the diagnosis of nasopharynx tumors, (5 cases) and in the determination of the extension of facial skeleton tumors.     

Giant-cell tumor of the skull base

Giant cell tumors are uncommon primary bone tumors. They primarily occur in the long bones. Giant cell tumors are extremely rare in the skull and head and neck. When it does occur, the maxilla and mandible are the common sites to be involved. We described two cases of giant cell tumor in the temporal bone. In the non-contrast enhanced CT, the lesion presents as a soft tissue density mass with expansion of the bone. The bony cortex is usually intact. The adjacent soft tissues and cerebral parenchyma show no infiltration or edema. The post contrast scan reveals homogenous enhancement of the mass. Received: 20 April 1998 Accepted: 11 August 1998     

Invasive aspergilloma of the skull base

Summary Aspergillus infection originating in the nasal cavity or paranasal sinuses is a rare cause of benign, locally invasive disease affecting the skull base. We describe a case in which extensive disease led to bilateral proptosis and invasion of the anterior cranial fossa.     

Skull base tumours Part II. Central skull base tumours and intrinsic tumours of the bony skull base

With the advances of cross-sectional imaging radiologists gained an increasing responsibility in the management of patients with skull base pathology. As this anatomic area is hidden to clinical exam, surgeons and radiation oncologists have to rely on imaging studies to plan the most adequate treatment. To fulfil these endeavour radiologists need to be knowledgeable about skull base anatomy, about the main treatment options available, their indications and contra-indications and needs to be aware of the wide gamut of pathologies seen in this anatomic region. This article will provide a radiologists' friendly approach to the central skull base and will review the most common central skull base tumours and tumours intrinsic to the bony skull base.     

Primary lymphoma of the skull base

This case demonstrates the rare finding of a primary malignant lymphoma of the frontobasis and ethmoidal cells in a patient presenting with progressive loss of vision. Computed tomography and MRI demonstrated a homogenously enhancing tumour with extensive bony destructions of the skull base. After transsphenoidal biopsy, histology revealed a highly malignant primary B-cell lymphoma. The patient was further treated with immunochemotherapy. Tissue diagnosis is, therefore, crucial before a definitive therapy is instituted.     

CT of the base of the skull

This article emphasizes the value of high-resolution CT scanning in evaluating the skull base. The use of axial and coronal sections, imaged at both bone and soft tissue windows, is emphasized, and a systematic approach to analysis of lesions of the skull base is offered.     

Surgical treatment of malignant tumors of the paranasal sinuses with involvement of the base of the skull

After 18 years of close cooperation between ORL and neurosurgery in the treatment of the base of the skull, the authors present their surgical conception and technique for the treatment of malignant tumors of the paranasal sinuses involving the base of the skull. Three basically different surgical procedures are possible: 1. Extracranial partial resection of the anterior base of the skull sparing the contents of the orbit. 2. Radical revision of superior maxilla, ethmoid bone, and base of the skull including exenteratio orbitae. 3. Combined intra-extracranial approach. An interdisciplinary cooperation and the combination of macro- and microsurgery will be more successful with respect to survival chances, functional and esthetic results.