Cerebral cavernous hemangiomas at 7 Tesla: initial experience

RATIONALE AND OBJECTIVES

Cavernous malformations (cavernomas) occur in 0.4%-0.9% of the population. The most common symptoms of cavernous malformations are seizures. An improved detection of small cavernomas might possibly help to clarify cryptogenic seizures, which represent 30% of all seizures. The aim of this study was to evaluate the benefit of magnetic resonance imaging at a field strength of 7 T in the detection of cavernomas.

MATERIALS AND METHODS

Ten consecutive patients with known cavernomas were enrolled in this study. First a T2*-weighted gradient echo sequence was performed at 1.5 T with a slice thickness of 6 mm in axial orientation. Subsequently, the examination was repeated at 7 T. Both examinations were independently read by two blinded senior neuroradiologists. Localization and dimension of the hypointensities were recorded.

RESULTS

One additional hypointensity was detected in one patient, which was not visible in the 1.5 T examination even retrospectively. In another patient with known cavernomatosis, innumerable new small hypointense lesions were detected at 7 T.

CONCLUSION

Our small series suggests that ultra-high-field magnetic resonance imaging at 7 T improves the detection of cavernomas.

Percutaneous embolization of carotid paragangliomas using solely Onyx

BACKGROUND AND PURPOSE

Paragangliomas are highly vascularized usually benign neoplasms arising from nerve tissue. Endovascular preoperative embolization is used to facilitate surgery but is often not complete, due to tiny feeding arteries not feasible for selective catheterization. Our purpose was to evaluate angiographic and clinical outcome using Onyx for percutaneous glomus tumor embolization.

MATERIALS AND METHODS

A consecutive series of 4 patients with 6 paragangliomas located at the bifurcation of the common carotid artery were treated with percutaneous embolization using Onyx as the sole embolic material.

RESULTS

Complete devascularization of the 6 paragangliomas was achieved using a percutaneous embolization technique with Onyx as a sole agent, combined with an endovascular microballoon that offered protection of the internal carotid artery.

CONCLUSIONS

Further documentation is necessary to prove the higher grade of devascularization of paragangliomas with Onyx compared with other embolic material and the associated potential to facilitate surgery. Nevertheless, Onyx seems to be safe when used percutaneously due to its lavalike pattern flow and its controllable properties, allowing slow tumor bed penetration.

First clinical study on ultra-high-field MR imaging in patients with multiple sclerosis: comparison of 1.5T and 7T

BACKGROUND AND PURPOSE

Higher magnetic field strengths and continuous improvement of high-resolution imaging in multiple sclerosis (MS) are expected to provide unique in-vivo and non-invasive insights in pathogenesis and clinical monitoring. The purpose of this study was to investigate the potential of high-resolution imaging of MS lesions in vivo comparing 7T with conventional 1.5T.

MATERIALS AND METHODS

Twelve consecutive patients with clinically definite MS were scanned on a 7T whole-body scanner and on a 1.5T Avanto. The 1.5T and 7T imaging protocol consisted of high-resolution axial proton density (PD) + T2-weighted turbo spin-echo and T2*-weighted gradient-echo (GRE), and sagittal T1-weighted 3D magnetization-prepared rapid acquisition of gradient echo.

RESULTS

The sequence parameters at 7T had to be modified because of specific absorption rate (SAR) restrictions while keeping contrast parameters equivalent to 1.5T. White matter lesions were better detected and delineated from adjacent structures at 7T compared with 1.5T. There were 42% of the patients who showed additional lesions at 7T: there were 97 white matter lesions detected on 1.5T versus 126 lesions at 7T, an increase of 23%. The perivascular migration of MS lesions was well visualized on T2*-weighted GRE sequences. In larger lesions (10 mm), a multilayer structure was revealed on T2*-weighted GRE not seen at 1.5T. Because of the higher resolution, it was possible to differentiate between juxtacortical white matter lesions and cortical lesions. There were 44% of the subcortical lesions depicted at 7T that showed cortical involvement.

CONCLUSIONS

Ultra-high-field imaging of patients with MS at 7T was well tolerated and provided better visualization of MS lesions in the gray matter and demonstrated structural abnormalities within the MS lesions themselves more effectively.

Endovascular treatment resolves non-hemorrhagic brainstem dysfunction due to tentorial dural AV fistula

Tentorial dural arteriovenous fistulas (tDAVF) clinically present usually with subarachnoid and/or intraparenchymal hemorrhage. Reported rates range from 58% to 92% and neurological deficits occur in 79% to 92% of patients. This is due to venous congestion resulting from retrograde leptomeningeal venous drainage, which rarely, can be clinically silent. A 69-year-old woman presented with vertigo, double vision and gait instability. Cerebral digital subtraction angiography revealed a tDAVF with retrograde cerebellar venous drainage directed through the vein of Galen into the straight sinus. MRI showed extensive cerebellar edema due to venous congestion. Clinical manifestations of cerebellar and brainstem dysfunction resolved completely after transarterial embolization with N-butylcyanoacrylate.

Neuroimaging of infections of the central nervous system

Neuroimaging plays a crucial role in the diagnosis and therapeutic management of neurologic infections. This article summarizes imaging findings in brain abscesses, ventriculitis, viral diseases, and opportunistic infections. In cases of uncomplicated meningitis, cranial computed tomography is sufficient to exclude brain edema, hydrocephalus, and skull base pathology. Magnetic resonance imaging (MRI) is superior in depicting complications (e.g., empyema, vasculitis). Diffusion-weighted imaging (DWI) shows parenchymal complications of meningitis earlier and is of help in differentiation of pyogenic abscess from other ring-enhancing lesions. Proton magnetic resonance spectroscopy can produce specific peak-patterns in cases of abscess, such as the presence of lactate and cytosolic amino acids. In toxoplasmosis, DWI may help to differentiate from lymphoma, showing no restriction of water diffusion. In patients with viral encephalitis, DWI allows earlier lesion detection. MRI has revolutionized the rapid diagnosis of spinal abscess.

Embolization of intracranial arteriovenous malformations with ethylene-vinyl alcohol copolymer (Onyx)

BACKGROUND AND PURPOSE

Endovascular therapy of intracranial arteriovenous malformations (AVMs) is increasingly used. However, it is still under discussion which embolic material is optimal. We report our experience in the treatment of AVMs with ethylene-vinyl alcohol copolymer (Onyx).

MATERIALS AND METHODS

Between July 2002 and January 2008, brain AVMs were embolized with Onyx in 82 consecutive patients in our department. There were 41 females and 41 males with a mean age of 44.2 years (range, 15-85 years). Clinical presentation included symptoms due to intracerebral hemorrhage (n = 37), seizures (n = 18), nonhemorrhagic neurologic deficits (n = 8), headaches (n = 9), or incidental symptoms (n = 10). According to the Spetzler-Martin scale, 59 AVMs were grades I-II, 16 were grade III, and 7 were grades IV-V.

RESULTS

Complete obliteration at the end of all endovascular procedures was achieved in 20/82 patients (24.4%), with an average of 75% (range, 30%-100%) volume reduction. A mean of 2.9 (range, 1-10) feeding pedicles was embolized per patient, whereas an average of 2.6-mL Onyx was used per patient. Procedure-related permanent disabling morbidity was 3.8%, whereas mortality was 2.4%.

CONCLUSIONS

The overall initial complete obliteration rate of intracranial AVMs with Onyx embolization is relatively high, compared with other embolic agents, with evidence of stability with time. Morbidomortality rates due to AVM embolization as a single treatment method or as a part of a multimodality treatment should be further assessed regarding the natural course of the disease.

Endovascular treatment of intracranial aneurysms in patients 65 years or older: clinical outcomes

BACKGROUND AND PURPOSE

A controversial discussion concerning treatment of aneurysms in elderly patients exists. The aim of this study was to analyze clinical outcome in patients older than 65 years harboring intracranial aneurysms after endovascular treatment.

MATERIALS AND METHODS

A total of 108 patients aged 65 years or older (mean age, 72 years, range, 65-87 years) were selected for endovascular treatment between 1997 and 2005. A total of 85 (78.7%) patients had an acute subarachnoid hemorrhage (SAH). SAH was classified according to Hunt and Hess (HH) grade: I (n = 16), II (n = 11), III (n = 33), IV (n = 19), and V (n = 6). There were 69 aneurysms that were small; 46, medium; 8, large; and 5, giant. Occlusion rate was categorized as complete (100%), subtotal (95% to 99%), and incomplete (<95%) obliteration according to the Raymond scale.

RESULTS

Endovascular treatment was technically feasible in 108 of 113 aneurysms. Complete occlusion could be achieved in 80 patients; basal remnant was seen in 26 patients and a dog ear in 2 patients. Procedural complications included thrombotic vessel occlusion (n = 9), aneurysmal rupture (n = 4), and stenosis of the parent vessel (n = 2). The Glasgow Outcome Scale (GOS) for the patients with SAH after 6 months was good recovery (n = 43), moderate disability (n = 12), severe disability (n = 28), persistent vegetative state (n = 5), and death (n = 18). Outcome for the patients with unruptured aneurysms was good recovery in all 23 patients. On follow-up digital subtraction angiography (DSA) in 69 patients, complete aneurysmal occlusion was confirmed in 81% after 6 months. Five patients with recanalization were re-treated with coiling.

CONCLUSION

Endovascular treatment of ruptured and unruptured intracranial aneurysms in this subgroup was safe and effective.