Calvarial and skull base metastases: comparison of nonenhanced and Gd-DTPA-enhanced MR images

Comparison of computed tomography and magnetic resonance imaging in evaluation of skull lesions

Background

Computed tomography (CT) and magnetic resonance imaging (MRI) have been incorporated into the basic imaging tools for evaluation of skull lesions. Despite the known advantages and disadvantages of CT and MRI in various aspects of evaluating skull lesions, it is not always feasible to perform both CT and MRI in evaluation of the same patient. The purpose of this study is to compare CT and MRI in evaluation of various skull lesions and to determine which imaging modality out of the two is more appropriate in evaluation of skull lesions and their characterization.

Results

There was no statistically significant difference between CT and MRI for detection of number of lesions, distribution of lesions, margins of the lesions, nature of the lesions, zone of transition, cortical breach, intralesional calcification, intralesional hemorrhage, associated soft tissue, and invasion into brain parenchyma (p value > 0.05 in all these parameters). Dural involvement was picked up better on MRI as compared to CT (p value 0.031). Another advantage of MRI over CT was better characterization of lesions by diffusion weighted imaging.

Conclusion

CT and MRI are equally efficient in providing adequate diagnostic information in various skull lesions and each of them can be used independent of the other to characterize and diagnose the lesions of skull. The slight advantage of MRI over CT is detection of dural involvement.

Calvarial angiomatous meningioma developed in the diploe

Background:

Angiomatous meningioma is a rare subtype of meningiomas. To the best of our knowledge, there have been no reports of intradiploic angiomatous meningioma.

Case Description:

A 53-year-old previously healthy woman was diagnosed with a calvarial lesion during a brain checkup. Cerebral magnetic resonance imaging showed an intradiploic tumor, 11 × 14 × 12 mm, in the right parietal bone. It was an enhancing, lobular tumor presenting as isointensity on T1- and hyperintensity on T2-weighted sequences, with an intense enhancement of the adjacent dura mater. Computed tomography revealed bone erosion at the tumor site, extending predominantly into the inner side, and sclerotic changes in the surrounding bone. Total resection was performed. Microscopically, the tumor tissue comprised cells with low-grade meningioma and intervening prominent vasculatures, consistent with angiomatous meningioma.

Conclusion:

Angiomatous meningioma should be considered as a differential diagnosis when an intradiploic tumor shows a lobular structure, intense enhancement of the adjacent dura mater, and sclerotic changes in the surrounding skull. These findings can support prompt tumor resection.

Intracranial dural, calvarial, and skull base metastases

Metastatic disease to the intracranial dura, the calvarium, and the skull base is relatively uncommon but presents unique diagnostic and management challenges in the patient with cancer. Modern imaging techniques have facilitated the detection of intracranial tumor deposits, leading to increased incidence. While dural and calvarial metastases often present with nonspecific symptoms, skull base metastases present with distinct clinical syndromes dependent on the local neurovascular structures affected. Intracranial dural metastases can often be confused with meningioma and pose a diagnostic challenge, as well as significant neurologic morbidity, especially in the setting of hemorrhage. Surgical intervention may be helpful in selected patients for symptomatic relief as well as survival benefit. Management paradigms need to take into account the relative risks, benefits, and likely outcomes for each possible modality of treatment. Surgical excision is useful in many patients and in combination with radiation therapy can provide significant palliation. While medical therapy is rarely an initial therapy in these entities, it may be of added benefit dependent on the underlying tumor histology and prior treatment history. Occasionally treatment with curative intent is justified.

Imaging pattern of calvarial lesions in adults

Calvarial lesions often present themselves as clinically silent findings on skull radiographs or as palpable masses that may cause localized pain or soreness. This review aims to explore the radiographic, computed tomography (CT), and magnetic resonance imaging (MRI) characteristics of calvarial neoplastic, inflammatory, and congenital lesions that are common in adults in order to facilitate a structured approach to their diagnosis and limit the differential diagnosis. In addition to reviewing the literature, we reviewed the records of 141 patients of the Montreal Neurological Institute and Hospital with radiologically documented calvarial lesions between 2001 and June 2009. CT is ideal for detecting bony lesions and is helpful in precisely localizing a lesion pre-surgically. MRI is best at identifying intradiploic lesions before they affect the cortical tables and is able to establish extraosseous involvement, especially when paramagnetic contrast is employed.

Imaging of the calvarium

The skull vault consists of a multitude of flat bones held together by the cranial sutures. Radiologists encounter a vast array of calvarial pathologies that tend to cause abnormalities in thickness, abnormalities in density, focal defects, or an excess of soft tissue or bone tissue. Further anomalies related to the cranial sutures and fontanelles occur in the dynamic pediatric skull. The imaging features of the host of conditions resulting in these commonly detected calvarial abnormalities are reviewed and illustrated.

The diploic venous system: surgical anatomy and neurosurgical implications

Object

There are few systematic investigations of the dissected surgical anatomy of the diploic venous system (DVS) in the neuroanatomical literature. The authors describe the DVS relative to different common neurosurgical approaches. Knowledge of this system can help avoid potential sources of unacceptable bleeding and may impact healing of the cranium.

Methods

Using a high-speed drill with a 2-mm bit, the authors removed the outer layer of the compact bone in the skull to expose the DVS in 12 formalin-fixed cadaver heads. Pterional, supraorbital, and modified orbitozygomatic craniotomies were performed to delineate the relationship of the DVS.

Results

The draining point of the frontal diploic vein (FDV) was located near the supraorbital notch. The draining point of the anterior temporal diploic vein (ATDV) was located in all pterional areas; the draining point of the posterior temporal diploic vein (PTDV) was located in all asterional areas. The PTDV was the dominant diploic vessel in all sides. The FDV and ATDV could be damaged during supraorbital, modified orbitozygomatic, and pterional craniotomies. The anterior DVS connected with the sphenoparietal and superior sagittal sinus (SSS). The posterior DVS connected with the transverse and sigmoid sinuses and was the dominant diploic vessel in all 24 sides. Of all the major diploic vessels, the location and pattern of distribution of the FDV were the most constant. The parietal bone contained the most diploic vessels. No diploic veins were found in the area delimited by the temporal squama.

Conclusions

The pterional, orbitozygomatic, and supraorbital approaches place the FDV and ATDV at risk. The major anterior diploic system connects the SSS with the sphenoparietal sinus. The posterior diploic system connects the SSS with the transverse and sigmoid sinuses.

Dural enhancement with primary calvarial lesions

The purpose of this study was to relate the pathological and imaging features of dural enhancement and meningeal sign ("dural tail") on contrast-enhanced T1-weighted magnetic resonance (MR) images from patients with primary calvarial lesions as well to assess the accuracy of MR imaging in predicting dural invasion. Thirty-two calvarial tumors studied with contrast-enhanced MR imaging and histopathological examination of the dural specimens were reviewed. Sixteen patients presented dural enhancement, eight with tumor invasion. Tumoral invasion of the dura was observed in one case without enhancement. Malignant lesions showed enhanced dura more commonly than benign lesions (P=0.02). Nodular and discontinuous dural enhancement was statistically associated with dural invasion (P=0.05). Dural tail did not show a specific pathological association. Meningeal enhancement is a nonspecific reaction to calvarial lesions unless nodular and discontinuous. False-negative and -positive cases of dural invasion imply some limitation of contrast-enhanced MR imaging in predicting dural invasion by calvarial neoplasms.

MR imaging for evaluation of lesions of the cranial vault: a pictorial essay

PURPOSE

A variety of diseases affect the calvaria. They may be identified clinically as palpable masses or incidentally in radiologic examinations. There are many diagnostic possibilities, including congenital, neoplastic, inflammatory and traumatic lesions. The purpose of this study is to illustrate the main calvarial lesions through MR imaging, their signal intensity and extension to neighboring sites.

METHOD

A retrospective analysis of 81 cases, from November 1996 to July 2001, was conducted. The examinations were performed on a 1.5 T equipment and each one of the cases was pathologically proven.

RESULTS

The results were: dermoid cysts [4 cases (5%)], epidermoid cysts [2 cases (2.5%)], cephalocele [14 cases (17.5%)], sinus pericranii [3 cases (3.7%)], leptomeningeal cysts [4 cases (5%)], Langerhans cell histiocytosis [10 cases (12.5%)], lipoma [4 cases (5%)], fibrous dysplasia [13 cases (16.2%)], osteoma [8 cases (10%)], hemangioma [1 case (1.2%)], meningioma [3 cases (3.7%)], chondrosarcoma [5 cases (6.2%)], hemangiosarcoma [1 case (1.2%)], multiple myeloma [3 cases (3.7%)], sarcomatous transformation of Paget disease [1 case (1.3%)], and metastasis [5 cases (6.2%)].

CONCLUSION

MRI identifies bone marrow abnormalities and invasion of adjacent tissues at an early stage. Therefore, it is an essential method when it commes to properly evaluating calvarial lesions.

Central nervous system: review of clinical use of contrast media

The clinical utility of intravenous contrast administration for magnetic resonance imaging in neoplastic disease of the brain, non-neoplastic disease of the brain, and in disease of the spine is reviewed. Magnetic resonance imaging (MRI) is the modality of choice for the evaluation of most suspected intracranial and spinal pathology. Contrast use substantially improves lesion detection and differential diagnosis. Applications are discussed in neoplastic disease, infection, vascular disorders, demyelinating disease, and trauma (specifically including in the spine disk herniation). Gadolinium chelates play as important a role in magnetic resonance imaging as do iodinated agents in computed tomography. Contrast administration facilitates time-efficient and cost-effective diagnosis.

Surgical resection of calvarial metastases overlying dural sinuses

OBJECTIVE

Few reports have addressed the surgical management of cranial metastases that overlie or invade the dural venous sinuses. To examine the role of surgery in the treatment of dural sinus calvarial metastases, we reviewed retrospectively 13 patients who were treated with surgery at the University of Texas M.D. Anderson Cancer Center between 1993 and 1999. We compared them with 14 patients who had calvarial metastases that did not involve a venous sinus.

METHODS

Clinical charts, radiological studies, pathological findings, and operative reports were analyzed retrospectively.

RESULTS

The median age of patients with dural sinus calvarial metastases was 54 years. Nine patients were men and four were women. Renal cell carcinoma and sarcoma were the most common primary tumors. Similar features were noted in the 14 patients with nonsinus calvarial metastases. Of the 13 dural sinus calvarial metastases, 11 involved the superior sagittal sinus, and 2 involved the transverse sinus. In nine patients, the involved sinus was resected, and in four patients, the sinus was reconstituted after tumor removal. Nine patients in the dural sinus calvarial metastases group received en bloc resection, and four received piecemeal resection. No operative deaths occurred. The overall median actuarial survival was 16.5 months. The survival times of the two groups were comparable. In the group with dural sinus calvarial metastases, transient postoperative neurological deficits occurred in two patients (15%), and a permanent deficit occurred in one patient (8%). No patients in the group with nonsinus calvarial metastases experienced deficits after resection. Compared with piecemeal resection, en bloc resection was associated with significantly less blood loss.

CONCLUSION

Complete extirpation of calvarial metastases that overlie or invade a dural sinus can be achieved with only slightly more morbidity than complete removal of calvarial metastases that are located away from the sinuses. En bloc resection is as safe as piecemeal resection and is more effective in limiting operative blood loss. The overall recurrence and survival rates of patients with dural sinus calvarial metastases are similar to those of patients with calvarial metastases that do not involve the sinuses. Therefore, involvement of a dural venous sinus should not discourage resection of calvarial metastases. In carefully selected cancer patients, surgery provides effective palliation of symptomatic calvarial metastases that overlie or invade the venous sinuses.

Skull base tumors: evaluation with contrast-enhanced MP-RAGE sequence

The purpose of this study is to assess the value of contrast-enhanced MP-RAGE sequence for evaluation of skull base tumors. A total of 36 patients were prospectively evaluated. MP-RAGE showed relatively higher CNRs than other sequences, and there was a significant difference of CNR between the MP-RAGE and contrast T1-weighted SE images when fat tissue was chosen as the background. MP-RAGE was significantly superior to other sequences in the diagnosis of the extent of tumors. Contrast-enhanced MP-RAGE sequence is useful in evaluation of skull base tumors because of its higher contrast, higher spatial resolution, multiplanar capability, and suppression of the fat signal.

[Intracranial metastasis in prostatic cancer]

The intracranial metastasis due to prostatic adenocarcinoma are quite rare, inside them, the ones placed in the parasellar region on the cranial base are exceptional. There are only 3 clinical cases found in the literature consulted, now we report here two more cases and we review the etiopathogenia, clinic presentation, diagnosis and treatment for this type of lesions. Usually there are very undifferentiated neoplasms, developed stages and with multiple metastasis at others levels. A patient with prostatic carcinoma known and neurological signs we should suspect the presence of intracranial metastasis. The diagnosis is made with image tests (basically with CT and MRI), being necessary in some cases the histological confirmation with a biopsy. Although the prognostic of these patients (less than 6 months in our cases) depends more of the evolutive stage of the illness than the type of treatment that the patients will be someated, we should establish it rapidly, on this way we can revert the neurological status and we will improve the quality of life of these patients.

Primary malignant lymphoma of the cavernous sinus--case report

A 59-year-old female presented with a very rare case of primary malignant lymphoma of the cavernous sinus manifesting as diplopia and right facial hypesthesia. Magnetic resonance (MR) imaging showed the tumor located in the right cavernous sinus as low intensity with marked enhancement by gadolinium. The tumor was partially removed by the transzygomatic extradural approach. The histological diagnosis was malignant lymphoma. Chest and abdominal computed tomography and gallium-67 scintigraphy revealed no other lesions in the body. The patient received conventional radiotherapy and her diplopia and right facial hypesthesia gradually improved. At 1 month after radiotherapy, MR imaging showed no evidence of residual tumor. Primary cavernous sinus malignant lymphoma is extremely rare, but should be considered in the differential diagnosis of cavernous sinus lesions. Histological confirmation of tumors in this region is essential for choosing the most appropriate treatment to achieve a better outcome.

The calvarium

The calvarium is a crucial structure that can manifest a great deal of pathology. The plain film remains the main imaging modality, although CT and MRI are becoming increasingly important. We discuss its anatomy, normal variants, congenital and developmental anomalies, hematologic disease, idiopathic disorders, neoplasms, metabolic disease, trauma, and the postoperative skull. Whenever possible, we emphasize CT and MRI.

Surgical implications of magnetic resonance-enhanced dura

The purpose of this study was to assess tissue changes responsible for dural enhancement of magnetic resonance imaging (MRI) and its clinical implications. A prospective surgical, histopathological, and MRI study was performed in 73 patients with various types of disease, including meningiomas (n = 29), craniofacial tumors with possible direct intracranial extension (n = 21), gliomas and brain metastasis in close proximity to the dura mater (n = 9), and a variety of nonneoplastic processes (n = 14). Contrast-enhanced MRI was obtained within 5 days before surgery and in some cases within 3 days after surgery as well. Histopathological examination of the dural specimens was performed in all 59 patients with neoplasia and in selected patients with nonneoplastic processes. Dural invasion was noted in 18 of 29 meningiomas, 15 of 21 craniofacial neoplasms, 3 of 5 gliomas, and 3 of 4 brain metastases. In these patients invasion was focal and in direct continuity with the tumors. MRI disclosed that dura invaded by the tumor had a break in the continuity of enhancement, or that there was no discernible enhancement. Association between patterns of dural enhancement and tumor invasion of dura was statistically significant (P < 0.001). The thickened-enhanced portion of the dura represented reactive changes. Postoperative enhancement was seen as early as 24 hours after surgery and was shown histologically to be associated with vasodilation and reactive changes.(ABSTRACT TRUNCATED AT 250 WORDS)

MR imaging of orbital mass lesions with contrast agent: a preliminary report

To investigate the advantage and limit of contrast enhancement in the examination of orbital mass lesions, precontrast T1- and T2-weighted, and postcontrast T1-weighted spin-echo images were retrospectively compared by two experienced observers. Using contrast material, intraocular tumors were well detected and characterized, and several orbital tumors were characterized as to whether cystic or necrotic and intracranial involvement was better evaluated. On the other hand, tumor-fat interface lost conspicuity when tumors showed enhancement. We conclude that gadopentetate-dimeglumine-administered T1-weighted images were helpful in detecting, differentiating and characterizing tumors of the orbit. However, the loss of contrast with fatty tissue is a disadvantage to be considered.

Magnetic resonance imaging contrast agents: theory and application to the central nervous system

The theoretical aspects of magnetic resonance (MR) imaging contrast agents are reviewed, and their current applications to the central nervous system (CNS) and their future applications are discussed. Profound differences exist between contrast agents used for MR imaging and computerized tomography (CT). In MR imaging, the contrast agents are not imaged directly but rather act on adjacent protons to shorten T1 and T2 relaxation times. This in turn results in signal intensity changes. The lanthanide metal, gadolinium, in the form of gadopentetate dimeglumine, has been found to be both safe and efficacious as the only currently approved contrast agent for MR imaging. Magnetic resonance imaging revolutionized the detection and treatment of disease affecting the brain and spine. Initially, it was thought that signal characteristics on MR imaging would allow differentiation of specific pathology. It was soon found that MR studies were able to detect more abnormalities but were less able to characterize them. The recent development of contrast agents for MR imaging has allowed this modality to surpass CT for the evaluation of most CNS lesions. At present, contrast-enhanced MR imaging is generally accepted as the study of choice for evaluating acoustic neurinomas, pituitary lesions, meningeal disease, primary and secondary brain tumors, active multiple sclerosis, intradural spinal neoplasms, intramedullary spinal disease, and postoperative states in both the spine and brain. Even when contrast-enhanced CT can detect the same abnormalities, evaluation of the lesions in multiple planes on MR imaging can sometimes yield invaluable information, especially prior to surgery. Future developments of contrast material for MR imaging include non-gadolinium compounds, intrathecal contrast media, cerebral blood flow and volume evaluation, and, possibly, antibody-labeled contrast agents.

New applications of MR contrast agents in neuroradiology

Contrast enhancement has now become an integral part of MR imaging. In this paper, the current uses of contrast agents in MR imaging of both the head and spine are reviewed. In addition, new applications of contrast in MR imaging, including some more current and controversial, are also explored.