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Venous cavernoma at 8 Tesla MRI
Abstract
Cavernous angiomas or cavernomas are vascular malformations, which may be associated with risk of bleeding episodes. We present a case report comparing high resolution 8 Tesla gradient echo (GE) imaging with routine fast spin echo (FSE) at 1.5 Tesla in a patient with venous cavernoma. A 55-year-old male with a history of hemorrhagic stroke was studied using high-resolution 8 Tesla magnetic resonance imaging (MRI) system, which revealed venous cavernoma (9 x 8.6 mm) in the left parietal region and visualized adjacent microvascular supply. Signal loss was prominent in the cavernoma region compared to surrounding brain tissue, and signal intensity declined by factor 7.3 +/- 2.4 (679 +/- 62%) on GE images at 8 Tesla. Cavernoma was not apparent on routine T(2)-weighted FSE images at 1.5 Tesla MRI. This case report indicates that GE images at 8 Tesla can be useful for evaluation of vascular pathologies and microvasculature.
... approximately 30% of epilepsy patients are not found to have an underlying lesion; some authors have posited that an improved detection of CCMs could aid in the identifica seizures) not visualized at 1.5 T. [22,46] MR imaging in both experimental and clinical s human CCMs and murine CCMs by high using high-field MR imaging results correlated with the histopathological findings obtained using confocal microscopy, confirming the angioarchitecture of CCMs at near histological resolution. Novak et al. [36] reported a case of a 55-year-old with a frontal hemorrhage, although at 1.5 Tesla the CCM was not apparent. When closely analyzed, the CCM appeared larger and signal loss was several times greater on 8 T MR images than on 1.5-T images. ...
... imaging techniques, approximately 30% of epilepsy patients are not found to have an underlying lesion; some authors have posited that an improved detection of CCMs could aid in the identification of CCMs (causing cryptogenic [22,46] Several authors have investigated the imaging effects of high MR imaging in both experimental and clinical settings. [36,38,46,48,49] Shenkar et al. [48,49] evaluated ex human CCMs and murine CCMs by high-resolution MR imaging at 9.4 or 14.1 T. The results obtained field MR imaging results correlated with the histopathological findings obtained using confocal microscopy, confirming the angioarchitecture of CCMs at near histological resolution. Novak et old ...
... lts correlated with the histopathological findings obtained using confocal microscopy, confirming the angioarchitecture of CCMs at near histological resolution. Novak et old with a frontal hemorrhage, although at 1.5 Tesla the CCM was not apparent. When closely analyzed, the CCM appeared larger and signal loss was several times greater on T images. [36] Schlamann et al. [46] performed imaging in 10 consecutive CCM These authors found one additional hypointensity, which was not visible in the T examination, and multiple new small hypointense lesions were detected at 7 T in a patient with familial CCM. However, because of increased susceptibility artifacts, these lesions appeared on aver ...
Cerebral cavernous malformations (CCMs) are divided into sporadic and familial forms. For clinical imaging, T2-weighted gradient-echo sequences have been shown to be more sensitive than conventional sequences. Recently more advanced imaging techniques such as high-field and susceptibility-weighted MR imaging have been employed for the evaluation of CCMs. Furthermore, diffusion tensor imaging and functional MR imaging have been applied to the preoperative and intraoperative management of these lesions. In this paper, the authors attempt to provide a concise review of the emerging imaging methods used in the clinical diagnosis and treatment of CCMs.
... MRI is the most sensitive and specific modality for identifying cavernomas and is well demonstrated using gradient echo-based sequences such as SWI and DWI. Higher MRI field strength scanner has an advantage in detecting and monitoring small size cavernomas [10]. ...
... It is well known that susceptibility effect increases as the field strength increase and are more evident by the use of gradient-echo imaging sequences. Therefore, abnormalities in the arteriovenous network that are not clearly apparent on routine MRI may become easily identifiable at higher magnetic fields [10]. ...
... How or if those effects on ultra-high-field imaging improve the diagnosis of various cerebral pathologies has yet to be evaluated. Few recent studies provide initial data that ultra-high-field magnetic resonance imaging at 7 T improves the detection of cerebral cavernous malformations when compared to 1.5 T (Dammann et al., 2010;Novak et al., 2003;Schlamann et al., 2010). Our study therefore aims to evaluate SWI sequences at 7 T for the detection of CCM and associated DVAs in comparison with SWI at 3 T for the first time in a larger series of CCM patients. ...
... With the availability of high and ultra-high field strength conditions improved for susceptibility weighted imaging. Initial data suggest that ultra-high-field magnetic resonance imaging at 7 T improves the detection of cerebral cavernous malformations when compared to 1.5 T (Dammann et al., 2010;Novak et al., 2003;Schlamann et al., 2010). Still, there is an ongoing discussion in the pertinent literature if the increased sensitivity of CCM detection reported by previous authors is due to high field strength per se or to SWI sequences since for some data lesion prevalence has been evaluated at high field using SW imaging and at lower field using GRE sequences (Campbell et al., 2010;Schlamann et al., 2010). ...
Background and aim
In the diagnosis of cerebral cavernous malformations (CCMs) magnetic resonance imaging is established as the gold standard. Conventional MRI techniques have their drawbacks in the diagnosis of CCMs and associated venous malformations (DVAs). The aim of our study was to evaluate susceptibility weighted imaging SWI for the detection of CCM and associated DVAs at 7 T in comparison with 3 T.
Patients and methods
24 patients (14 female, 10 male; median age: 38.3 y (21.1 y–69.1 y) were included in the study. Patients enrolled in the study received a 3 T and a 7 T MRI on the same day. The following sequences were applied on both field strengths: a T1 weighted 3D GRE sequence (MP-RAGE) and a SWI sequence. After obtaining the study MRIs, eleven patients underwent surgery and 13 patients were followed conservatively or were treated radio-surgically.
Results
Patients initially presented with haemorrhage (n = 4, 16.7%), seizures (n = 2, 8.3%) or other neurology (n = 18, 75.0%). For surgical resected lesions histopathological findings verified the diagnosis of CCMs. A significantly higher number of CCMs was diagnosed at 7 T SWI sequences compared with 3 T SWI (p < 0.05). Additionally diagnosed lesions on 7 T MRI were significantly smaller compared to the initial lesions on 3 T MRIs (p < 0.001). Further, more associated DVAs were diagnosed at 7 T MRI compared to 3 T MRI.
Conclusion
SWI sequences at ultra-high-field MRI improve the diagnosis of CCMs and associated DVAs and therefore add important pre-operative information.
... On sequential sagittal images, hemosiderin and calcium deposits were visible as areas of signal loss within basal ganglia and scattered within the brain. 34 Association between WMC and patterns of periventricular microvasculature is demonstrated in a series of 8 T images obtained from a 45-year-old woman with a small vessel disease ( Figure 4). Rapid acquisition with relaxation enhancement (RARE) images (A, B, C) at the level of ventricles showed confluent WMC extending from the anterior and posterior horns of the ventricles. ...
... Incidental findings at high field MRI include iron deposits within brain tissue, fat and calcium deposits within the falx 33 ( Figure 5), and vascular pathologies such as angiomas and venous cavernomas. 34 Some angiomas and cavernomas that were not identified at the lower field were more prominent and appeared larger at high field. Cavernous malformations may be clinically silent, or the patient may present with acute neurological deficit, seizures, or hemorrhagic strokes. ...
As the race for increased magnetic field strength continues, ultra high field magnetic resonance systems are entering the
clinical arena. Human brain imaging at ultra high field (7, 8, and 9.4 Tesla) offers an unprecedented resolution for anatomical
imaging that approaches in-vivo microscopy. Results from healthy volunteers and from stroke and tumor studies have demonstrated
that high field MRI can visualize microvasculature, details of pathological conditions, and iron deposits with a resolution
not obtainable at lower fields. High-resolution maps of brain function and biochemical markers have been obtained at 7 Tesla.
Clinical brain imaging is feasible at ultra high magnetic field, but more studies need to be done to determine its diagnostic
potential.
... Depending on the strength, lesions may appear to be larger than in reality. More specifically, high-field imaging at 7 T causes lesions to appear 11% larger than in conventional imaging techniques[29][30][31]. ...
Microsurgical resection, stereotactic radiosurgery (SRS), and conservative management are
three methods of treatment for intracranial cavernomas. However if left untreated, cavernomas
may lead to intracerebral hemorrhage, seizures, focal neurologic deficits, or headaches. Deciding
how to manage a cavernoma patient depends on a multitude factors. While microsurgery is the
standard treatment for intracranial cavernomas, conservative treatment should be the choice
for the patients without new or progressive neurological deficits and two or more documented
hemorrhages and with seizure responsive to the medical treatment. For the others the treatment
is primarily surgical for the cases with non-eloquent locations and the results have been best
where complete excisions is achieved.
Radiosurgery, especially Gamma Knife (GK) usage is an important alternative for treatment
of deep and eloquent area located cavernomas and for the patients who do not accept surgical
treatment.
Keywords: Cavernoma; Cerebral; Gamma knife; Radiosurgery
... The core is formed by multiple foci of mixed signal intensities, which represents hemorrhage in various stages of evolution. [12] A low signal intensity hemosiderin ring that completely surrounds the lesion is a common finding. ...
Cavernous angiomas are cerebral cavernous malformations and they are relatively rare lesions. Two forms of cavernous angiomas have been described: a sporadic form, in which patients usually have a single lesion, and a familial form, the hallmarks of which are multiple lesions and autosomal dominant transmission. The familial form appears to be very uncommon and has mainly been described in the Hispanic population. We report two cases of multiple intracranial cavernous angiomas which is an autosomal dominant pattern of inheritance. It is very rare to find this in non Hispanic population.
... The use of conventional 1.5 T MR imaging is limited, as CM lesions may not be visualized unless high-field MR imaging is used. Using MR strengths of up to 14 Tesla, several studies have illustrated the ability of high-field imaging to visualize lesions as hypointensities that were not otherwise apparent [23][24][25]. Depending on the strength, lesions may appear to be larger than in reality. More specifically, high-field imaging at 7 T causes lesions to appear 11% larger than in conventional imaging techniques [25]. ...
Cerebral cavernous malformations are the most common vascular malformations and can be found in many locations in the brain. If left untreated, cavernomas may lead to intracerebral hemorrhage, seizures, focal neurological deficits, or headaches. As they are angiographically occult, their diagnosis relies on various MR imaging techniques, which detect different characteristics of the lesions as well as aiding in planning the surgical treatment. The clinical presentation and the location of the lesion are the most important factors involved in determining the optimal course of treatment of cavernomas. We concisely review the literature and discuss the advantages and limitations of each of the three available methods of treatment-microsurgical resection, stereotactic radiosurgery, and conservative management-depending on the lesion characteristics.
... Currently, high-field MRI scanners operating at 3 Tesla (3T) are
entering routine clinical use and are becoming available from most manufacturers. They can
offer improved quality and spatial resolution in conditions with subtle differences between
normal and abnormal tissue (5, 6). ...
It is sometimes difficult to confirm the location of a microadenoma in Cushing disease. Recently, we experienced an 11-yr-old female case of Cushing disease with hyperprolactinemia. She was referred to our hospital because of decrease of height velocity with body weight gain. On admission, she had typical symptoms of Cushing syndrome. Although no pituitary microadenomas were detected on 1.5 Tesla MRI of the brain, endocrinological examinations including IPS and CS sampling were consistent with Cushing disease with hyperprolactinemia. Oral administration of methyrapone instead of neurosurgery was started after discharge, but subsequent 3 Tesla MRI of the brain clearly demonstrated a 3-mm less-enhanced lesion in the left side of the pituitary gland. Finally, transsphenoidal surgery was performed, and a 3.5-mm left-sided microadenoma was resected. Compared with 1.5 Tesla MRI, 3 Tesla MRI offers the advantage of a higher signal to noise ratio (SNR), which provides higher resolution and proper image quality. Therefore, 3 Tesla MRI is a very useful tool to localize microadenomas in Cushing disease in children as well as in adults. It will be the first choice of radiological examinations in suspected cases of Cushing disease.
... This sequence should be part of the imaging protocol in all patients with a positive family history of cavernoma, all patients with a suspicion of focal or generalized seizures, and in all patients with DVA (there is a signifi cant coincidence between occurrence of DVA and cavernoma). Due to this high sensitivity of susceptibility-weighted sequences, 3-Tesla MR machines and moreover 7-Tesla technology might be able to detect more subtle cavernomas of the brain and thus enable us to get more insights into the pathogenesis and bleeding risk of these malformations (Novak et al. 2003). However, turbo spin-echo sequences using a long echo train, i.e. all FLAIR sequences, are very insensitive to this susceptibility effect. ...
Cavernomas are endothelium lined sinusoidal blood cavities without other features of normal blood vessels like muscular or adventitial layers. No brain tissue is present between the blood cavities
Cavernomas may occur sporadically, after radiation, or hereditarily following an autosomal dominant trait
The majority of cavernomas present with seizures
Annual bleeding rate of cavernomas ranges between 0.25% and 0.7% per year During follow-up of cavernomas, progression in size can occur which is related to osmotic changes
Cavernomas may be calcified and have a typically pop-corn like appearance on MRI
Surgical resection is recommended for cavernomas presenting with symptomatic hemorrhage in accessible and non-eloquent locations
Capillary telangiectasias are composed of multiple thin-walled vascular channels between normal brain parenchyma
Diagnosis of capillary telangiectasias is made with MRI. Non-specific symptoms may be associated, tinnitus being more common
Therapy and follow-up of capillary telangiectasias is not necessary
... A study 3 reported a tremendous enhancement of venous structures at 8T up to 100 µm in size, including perforating venous drainage. This is further confirmed in Novak and coworkers' work, 4 which utilized 8T acquisition to visualize venous cavernoma from a hemorrhagic stroke case. A study 5 demonstrated that very detailed microvasculatures (such as intracortical veins) can be visualized clearly in 7T MR venography, but no quantitative analysis of vessel visibility was carried out. ...
Although multiple studies demonstrate benefits of high field imaging of cerebrovasculature, a detailed quantitative analysis of complete cerebrovascular system is unavailable. To compare quality of MR angiography (MRA) acquisitions at various field strengths, we used 3-dimensional (3D) geometric cerebrovascular models extracted from 1.5T/3T/7T scans.
The 3D cerebrovascular models were compared in volume, length, and number of branches. A relationship between the vascular length and volume was statistically derived. Acquisition performance was benchmarked against the maximum volume at infinitive length.
The numbers of vessels discernible on 1.5T/3T/7T are 138/363/907. 3T shows 3.3(1.9) and 7T 1.2(9.1) times more arteries (veins) than 1.5T. The vascular lengths and volumes at 1.5T/3T/7T are 3.7/12.5/22.7 m and 15.8/26.6/28.0 cm3. For arteries: 3T-1.5T gain is very high in length, high in volume; 7T-3T gain is medium in length, small in volume. For veins: 3T-1.5T gain is moderate in length, high in volume; 7T-3T gain is very high in length, moderate in volume. 1.5T shows merely half of vascular volume. At 3T 6%, while at 7T only 1% of vascular volume is missing.
Our approach differs from standard approaches based on visual assessment and signal (contrast)-to-noise ratio. It also measures absolute acquisition performance, provides a unique length-volume relationship, and predicts length/volume for intermediate teslages.
... Clinical imaging may become possible in vivo at higher field strengths. A recent report has shown the same level of details in clinical MR imaging at 8 T of a patient with proliferative capillary telangiectasia, likely representing an early stage of CCM genesis (18). The same features of lesion angioarchitecture revealed at high field imaging may be definable by optimized sequences at medium field strengths (3-6 T) likely to be more widely available clinically in upcoming years. ...
We hypothesized that structural details that have not been described previously would be revealed in cerebral cavernous malformations (CCM) through the use of high-field magnetic resonance and confocal microscopy. The structural details of CCMs excised from patients were sought by examination with high-field magnetic resonance imaging (MRI) and correlated with confocal microscopy of the same specimens. Novel features of CCM structure are outlined, including methodological limitations, venues for future research, and possible clinical implications.
CCM lesions excised from 4 patients were fixed in 2% paraformaldehyde and subjected to high-resolution MRI at 9.4 or 14.1-T by spin echo and gradient recalled echo methods. Histological validation of angioarchitecture was conducted on thick sections of CCM lesions using fluorescent probes to endothelium under confocal microscopy.
Images of excised human CCM lesions were acquired with proton density-weighted, T1-weighted, T2-weighted spin echo, and T2*-weighted gradient recalled echo MRI. These images revealed large "bland" regions with thin-walled caverns and "honeycombed" regions with notable capillary proliferation and smaller caverns surrounding larger caverns. Proliferating capillaries and caverns of various sizes were also associated with the walls of apparent larger blood vessels in the lesions. Similar features were confirmed within thick sections of CCMs by confocal microscopy. MRI relaxation times in different regions of interest suggested the presence of different states of blood breakdown products in areas with apparent angiogenic proliferative activity.
High-field MRI techniques demonstrate novel features of CCM angioarchitecture, visible at near histological resolution, including regions with apparently different biological activity. These preliminary observations will motivate future research, correlating lesion biological and clinical activity with features of MRI at higher field strength.
... [1][2][3] Although standard magnetic resonance imaging (MRI) scanners use 1.5T magnets, MRI with stronger magnetic field strength may offer improved image quality and spatial resolution in conditions with subtle differences between normal and abnormal tissue. 4,5 We hypothesized that microadenomas associated with Cushing's disease might be visualized with better resolution and accuracy using high-strength MRI. We present five cases of adrenocorticotrophic hormone (ACTH)-secreting adenomas that showed ambiguous radiographic evidence of tumor on standard MRI. ...
Because radiographic visualization of a pituitary microadenoma is frequently difficult, we hypothesized that microadenomas associated with Cushing's disease may be better resolved and localized via acquisition with 3-Tesla (3T) compared with standard 1.5-Tesla (1.5T) magnetic resonance imaging (MRI). Five patients (four females, one male; age range, 14 to 50 years old) with endocrine and clinical confirmation of Cushing's disease underwent 1.5T and 3T MRI and corticotropin-releasing hormone stimulation/inferior petrosal sinus sampling (IPSS) as part of their preoperative evaluation. All patients underwent a transnasal trans-sphenoidal pituitary adenomectomy. In two cases, tumor could not be localized on either 1.5T or 3T MRI on the initial radiologist's review. In two other cases, the 1.5T images delineated the tumor location, but it was more clearly defined on 3T MRI. In a fifth case, the 1.5T MRI showed a probable right-sided adenoma. However, on both 3T MRI and at surgical exploration the tumor was localized on the left side. Therefore, in three of five cases, 3T MRI either more clearly defined tumors seen on 1.5T MRI or predicted the location of tumor contrary to the 1.5T images. IPSS identified the correct side of the tumor in two patients, an incorrect location in two patients, and was indeterminate in one patient. In certain cases 3T MRI is a new tool that may ameliorate imaging difficulties associated with adrenocorticotrophic hormone-secreting pituitary adenomas. Its role in the diagnostic evaluation of Cushing's disease will be better defined with further experience.
Cavernomas have various different names. Cerebral cavernoma, cerebral cavernous malformation (CCM), cryptic angioma, cavernous hemangioma, and cavernous angioma are well used and sometimes confused in terms of nomenclature. As these lesions are not neoplastic, it has been argued that the terms ‘hemangioma’ and ‘cavernoma’ should be avoided. Additionally, it is important to note that according to newer nomenclature (ISSVA classification of vascular anomalies), these lesions are known as slow flow venous malformations [1]. It is probably helpful in reports to include the word ‘cavernous’ as this term is ubiquitous in the literature and most familiar to many clinicians. Therefore, the term ‘cerebral cavernous malformations (CCMs)’ are recommended and used in this chapter [1–6].
Cerebral cavernous malformations (CCMs), are low-flow vascular malformations. These lesions on histology characteristically lack mural elements of mature vascular structures and intervening parenchymal neural tissue. Most of the CNS cavernomas are incidental findings in imaging studies performed for other pathologies/nonspecific complaints. Seizures are the most usual clinical presentation. Hemorrhage is not an uncommon complication with a varying reported annual rate of bleed. These lesions are usually not seen on digital subtraction angiography (DSA). MRI provides the most sensitive and specific method of diagnosing and characterizing CCMs in the brain. A typical cavernoma have a popcorn-like appearance with a well delineated reticulated core of mixed signal intensities on T2WI. The heterogeneous nucleus is surrounded by hemosiderin and manifests as a peripheral ring of hypo-intensity on T2WI and to a lesser extent on T1WI. T2*-weighted GRE sequence is more sensitive in detecting CCMs and demonstrates greater signal when compared to conventional spin-echo sequences. Susceptibility-weighted imaging (SWI) is highly sensitive for CCMs and accompanying DVAs, and is superior to GRE in detecting multifocal, familial cavernomas.
Introduction The Promises of Ultrahigh Field Strenghts Imaging of Venous Vasculature at Different Magnetic Fields New Horizons in Image Contrast Technical Challenges of Ultrahigh-Field MRI Conclusions References
In this review, current (clinical) applications and possible future directions of ultrahigh-field (≥7 T) magnetic resonance (MR) imaging in the brain are discussed. Ultrahigh-field MR imaging can provide contrast-rich images of diverse pathologies and can be used for early diagnosis and treatment monitoring of brain disease. These images may provide increased sensitivity and specificity. Several limitations need to be overcome before worldwide clinical implementation can be commenced. Current literature regarding clinically based ultrahigh-field MR imaging is reviewed, and limitations and promises of this technique are discussed, as well as some practical considerations for the implementation in clinical practice.
In the study we assessed the distortion of 7.0 T magnetic resonance (MR) images in reference to 1.5 T MR images in the radiosurgery of metastatic brain tumors. Radiosurgery with Gamma Knife Perfexion was performed for the treatment of a 54-yr-old female patient with multiple brain metastases by the co-registered images of the 7.0 T and 1.5 T magnetic resonance images (MRI). There was no significant discrepancy in the positions of anterior and posterior commissures as well as the locations of four metastatic brain tumors in the co-registered images between 7.0 T and 1.5 T MRI with better visualization of the anatomical details in 7.0 T MR images. This study demonstrates for the first time that 7.0 T MR images can be safely utilized in Perfexion Gamma Knife radiosurgery for the treatment of metastatic brain tumors. Furthermore 7.0 T MR images provide better visualization of brain tumors without image distortion in comparison to 1.5 T MR images.
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.
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.
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.
Our small series suggests that ultra-high-field magnetic resonance imaging at 7 T improves the detection of cavernomas.
Cavernous haemangiomas belong to a group of vascular malformations that are developmental defects of the vascular bed. Occurrence of an asymptomatic cavernoma in the pons is uncommon and worthy of record. At autopsy, cavernomas have to be differentiated from traumatic haemorrhagic lesions in head injury cases. We hereby report a case in which a pontine cavernous haemangioma was detected at autopsy in a 25-year-old female who died due to burn injuries. (c) 2009 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.
Although it is generally accepted that developmental venous anomalies (DVAs) are benign vascular malformations, over the past years, we have seen patients with symptomatic DVAs. Therefore, we performed a retrospective study and a literature study to review how, when, and why DVAs can become clinically significant.
Charts and angiographic films of 17 patients with DVAs whose 18 vascular symptoms could be attributed to a DVA were selected from a neurovascular databank of our hospital. MRI had to be available to rule out any other associated disease. In the literature, 51 cases of well-documented symptomatic DVAs were found. Pathomechanisms were divided into mechanical and flow-related causes.
Mechanical (obstructive or compressive) pathomechanisms accounted for 14 of 69 symptomatic patients resulting in hydrocephalus or nerve compression syndromes. Flow-related pathomechanisms (49 of 69 patients) could be subdivided into complications resulting from an increase of flow into the DVA (owing to an arteriovenous shunt using the DVA as the drainage route; n=19) or a decrease of outflow (n=26) or a remote shunt with increased venous pressure (n=4) leading to symptoms of venous congestion. In 6 cases, no specific pathomechanisms were detected.
Although DVAs should be considered benign, under rare circumstances, they can be symptomatic. DVAs, as extreme variations of normal venous drainage, may represent a more fragile venous drainage system that can be more easily affected by in- and outflow alterations. The integrity of the DVA needs to be preserved irrespective of the treatment that should be tailored to the specific pathomechanism.
Venous angiomas, or developmental venous anomalies (DVAs), represent the most often occurring cerebral vascular malformation. The clinical significance of a DVA is, however, at present unclear.
A retrospective analysis was carried out on two series of consecutive cranial MRIs performed between January 1990 and August 1996 in a university department of neuroradiology and in a large radiological private practice. The medical records of all patients in whom a DVA was diagnosed were screened to identify the specific complaint which necessitated the imaging procedure.
A total of 67 patients with DVA could be identified. In 12 patients an associated cavernoma was found. The main reason for performing the MRI was the evaluation of seizures or of headaches. In all patients with DVA in whom an intracerebral haemorrhage was diagnosed an associated cavernoma was present at the site of the haemorrhage. None of the 67 patients showed an association between the complaints that led to the MRI and the location of the DVA.
DVAs do not seem to be associated with a specific clinical presentation. In a significant percentage of cases, however, coexisting cavernomas are found which have a defined bleeding potential and should be treated independently of the DVA. This study supports the hypothesis that DVAs are a congenital abnormality of venous drainage without clinical significance.
Although the prevalence of brain cavernomas is high (0.50%), for unknown reasons, only a few of them display aggressive clinical behavior.
From a personal series of 65 operated and histopathologically verified cavernomas, we have conducted a long-term study, both retrospectively and prospectively, of the main features that cause some cavernomas to be dynamic lesions.
Hemorrhage is the most common phenomenon. Extralesional bleeding due to the rupture of peripheral caverns is most often observed. These are never as immediately devastating as hemorrhages originating from a high-flow, high-pressure AVM. Extralesional hemorrhages tend toward spontaneous resorption, but the risk of recurrence exists and may lead to permanent disability or death (especially when the lesion is located in the brain stem). Intralesional bleeding caused by rupture of contiguous caverns is less frequently observed. This may lead to the formation of large cysts. Calcifications are mostly observed in patients presenting with chronic epilepsy. The bleeding risk of calcified cavernomas is low, but it can exist and should be taken into account in the surgical decision making. The growth of the cavernomatous matrix was obvious in three large cavernomas (two with calcification). No bleeding was found inside the lesions, suggesting a pure "intrinsic" growth. The role of pathologic angiogenic factors is highly probable in these cases. "De novo" appearing lesions were observed in five cases (four belonging to familial forms) on the magnetic resonance imaging survey of operated patients. Perilesional atrophy was observed in three cases (two operated) in patients with a long-lasting evolution. It suggests that the brain metabolism can be disturbed by slow, chronic effusion of blood around the cavernoma.
The dynamism of cavernomas is determined by extrinsic factors, mainly hemorrhage (with its own consequences); and by intrinsic factors: the pseudotumoral growth of the cavernous matrix. Therefore, when they are symptomatic, cavernomas should be totally removed.
Cavernous sinus cavernomas are rare lesions associated with high rates of intraoperative mortality and morbidity resulting from profuse bleeding. In this paper, the authors report their experience in treating five patients with histologically confirmed cavernous sinus cavernomas and describe the efficacy of induced hypotension in facilitating excision of the lesion.
All five patients were women ranging in age from 25 to 54 years, with an average age of 42 years. The mass was small in one and large (>3 cm in diameter) in four. In one patient with a large mass, cardiac arrest occurred after the craniotomy, and remarkable reduction in the size of the cavernoma was evident on postmortem examination. The other three large lesions were successfully removed piecemeal after induction of hypotension (60-80 mm Hg systolic pressure), which remarkably reduced the mass and the bleeding during surgery. In the remaining patient, who had a small lesion, the cavernoma was removed in one piece.
Cavernous sinus cavernoma can be thought of as a cluster of sinusoidal cavities, the size of which varies depending on the systemic blood pressure. During surgery, reduction of the mass and control of bleeding from the cavernoma can be achieved by inducing hypotension, which enables the safe excision of this lesion. This technique should be considered by surgeons resecting a cavernous sinus tumor, especially when cavernoma is suspected.
The purpose of this work was to describe the deep vascular anatomy of the human brain using high resolution MR gradient echo imaging at 8 T.
Gradient echo images were acquired from the human head using a transverse electromagnetic resonator operating in quadrature and tuned to 340 MHz. Typical acquisition parameters were as follows: matrix = 1,024 x 1,024, flip angle = 45 degrees, TR = 750 ms, TE = 17 ms, FOV = 20 cm, slice thickness = 2 mm. This resulted in an in-plane resolution of approximately 200 microm. Images were analyzed, and vascular structures were identified on the basis of location and course.
High resolution ultra high field magnetic resonance imaging (UHFMRI) enabled the visualization of many small vessels deep within the brain. These vessels were typically detected as signal voids, and the majority represented veins. The prevalence of the venous vasculature was attributed largely to the magnetic susceptibility of deoxyhemoglobin. It was possible to identify venous structures expected to measure below 100 microm in size. Perforating venous drainage within the deep gray structures was identified along with their parent vessels. The course of arterial perforators was more difficult to follow and not as readily identified as their venous counterparts.
The application of high resolution gradient echo methods in UHFMRI provides a unique detailed view of particularly the deep venous vasculature of the human brain.
The purpose of this work was to describe the human leptomeningeal and cortical vascular anatomy as seen at high resolution on an 8 T UHFMRI system.
With a 1024 x 1024 matrix, axial gradient echo images of the cerebral cortex were acquired on a human volunteer at 8 T with TR 500 ms, TE 16 ms, flip angle 22.5 degrees, bandwidth 53 kHz, and slice thickness 2.84 mm. The same subject was evaluated at 1.5 T using similar parameters. The images were then reviewed in detail and compared with known cortical and leptomeningeal vascular anatomy.
Two hundred forty micron in-plane resolution images of the human brain were acquired at 8 T without evident artifact from susceptibility distortions, RF penetration, or dielectric resonances. The CSF, gray matter, and white matter structures were well discerned. The microscopic leptomeningeal vascular anatomy was well visualized, and the course of small perforating cortical vessels could be followed from the cortical surface to the white matter junction.
Initial 8 T images of the brain demonstrate detailed leptomeningeal and cortical vascular anatomy.
The purpose of this work is to discuss radio frequency (RF) penetration and its relevance to imaging the human head and to acquire images containing intricate structures located at the center of the brain with ultra high field MRI (UHFMRI).
A simple plane wave analysis of RF penetration was performed based on Maxwell equations as a function of frequency up to 900 MHz. Gradient-recalled images were acquired at 8 T (340 MHz) using an RF resonator operating in quadrature. Typical acquisition parameters were as follows: TR = 750 ms, TE = 17 ms, slice thickness = 2 mm, FOV = 20 x 20 cm, matrix = 1,024 x 1,024. The specific absorption rate was well below 1 W/kg.
A simple analytical treatment, for a plane wave up to 900 MHz, reveals a lack of decreasing penetration depth with frequency beyond 200 MHz. Gradient-recalled echo images acquired from the human head displayed good contrast, homogeneity, and resolution. Importantly, excellent structural detail was observed on the resulting MR images, demonstrating that RF penetration is not a problem at 8 T. Images reveal excellent detail including the red nucleus, anterior commissure, fornix, mamillary body, pineal gland, and ependymal lining of the fourth ventricle.
Structures located at the center of the human brain can be clearly visualized at 8 T with no detectable loss in signal intensity arising from RF penetration. The ability to examine these structures with UHFMRI will provide a powerful new modality for diagnostic radiology.
The presence of magnetic susceptibility can lead to substantial geometric distortions when imaging the human head at 8 T. These are particularly significant in gradient echo images where susceptibility often results in a noticeable loss of MR signal in the temporal lobe, the frontal lobe, and the paranasal sinus regions. In this work, anterior coronal gradient and spin echo images were acquired from the frontal lobe and sinus regions. The spin echo was shown to significantly overcome the loss of signal observed in the corresponding gradient echo images, resulting in data of greatly increased quality. In conclusion, whereas susceptibility artifacts are significant in ultra high field MRI, they can be largely surmounted by using spin echo techniques, as had been previously demonstrated in studies at lower field strength.
Magnetic susceptibility provides the basis for functional studies and image artifacts in MRI. In this work, magnetic susceptibility and the associated artifacts were analyzed at 8 T in phantoms and in the human head.
A mineral oil phantom was constructed in which three cylindrical air-filled tubes were inserted. This phantom was analyzed with gradient-recalled echo and SE imaging techniques acquired using varying TEs and receiver bandwidths. To visualize the presence of magnetic susceptibility artifacts in the head at 8 T, near axial, coronal, and sagittal GE images were also acquired from human volunteers.
The use of gradient-recalled echo imaging resulted in the production of significant magnetic susceptibility artifacts. These artifacts could be readily visualized in phantom samples containing air-filled cylindrical tubes. In the human head, susceptibility artifacts produced significant image distortion in the skull base region. In this area, susceptibility artifacts often resulted in the complete loss of MR signal. Magnetic susceptibility artifacts were manifested as bands of varying signal intensity in the frontal lobe and temporal bone region. In addition, they produced clear distortions in the appearance of brain vasculature and seemed to accentuate the relative size of venous structures within the brain.
When using gradient-recalled echo imaging in combination with relatively long TE values, magnetic susceptibility artifacts can be severe at 8 T. These artifacts could be reduced by increasing receiver bandwidths and by lowering effective TEs. As ultra high field MRI provides a fertile ground for the study of susceptibility artifacts in MRI, improvements obtained at this field strength will have a direct impact on studies performed at lower field strengths.
To review the natural history and determine the rates of intra- and extralesional hemorrhaging of brainstem cavernous malformations (cavernomas) monitored by one neuro-ophthalmology service.
A record review of all patients with brainstem cavernomas who were evaluated by a neuroophthalmology service between 1987 and 1999 was performed. We recorded the clinical symptoms and Rankin disability grade at presentation, during the worst clinical episode, and at the last follow-up examination. Magnetic resonance imaging scans were reviewed for evidence of intralesional hemorrhage (a bleeding episode), edema, or venous anomalies, and the cavernoma size was assessed.
Thirty-seven patients (age range, 6-73 yr; mean age at presentation, 37.5 yr) underwent a mean of 4.9 years of follow-up monitoring. At presentation, there were 27 bleeding events and 8 nonhemorrhagic events; 2 patients did not exhibit symptoms. Patients who were at least 35 years of age exhibited a lower risk of bleeding episodes (odds ratio, 0.15; 95% confidence interval, 0.1-0.4). Cavernomas of at least 10 mm were associated with a higher risk of bleeding episodes (odds ratio, 3.48; 95% confidence interval, 1.3-9.4). Thirty-nine bleeding episodes occurred in 31 patients, yielding a bleeding rate of 2.46%/yr. There were eight rebleeding episodes, yielding a rebleeding rate of 5.1%/yr. Three patients experienced extralesional bleeding episodes; all of these patients experienced rebleeding. Of the 39 follow-up magnetic resonance imaging scans, the cavernoma size was unchanged in 66.7%, smaller in 18%, and larger in 15%. At the last follow-up examination, the mean Rankin grade was 1.0 for all patients, 0.6 for the 25 nonsurgically treated patients, and 1.4 for the 12 surgically treated patients.
Rebleeding is not more common among patients who first present with bleeding, and it often has little effect on the neurological status of patients. Significant morbidity attributable to a brainstem cavernoma occurred in 8% of patients during follow-up monitoring of medium duration.
Optimal treatment strategies and neurologic outcome after stroke depend on an accurate characterization of the lesion. There is a need for high resolution noninvasive imaging for assessment of the infarct size, perfusion, and vascular territory. MRI at the ultra high field (UHF) of 8 T offers unprecedented resolution, but its utility for stroke evaluation has not been determined yet.
A 55-year-old man with hypertension experienced sudden onset of speech arrest and right-sided hemiparesis that resolved in < 24 h with minimal neurologic deficit. MRI at 1.5 T showed initially a left posterior frontal lesion with subacute infarct (hyperintense on T2-weighted spin echo images) and right-sided frontal and periventricular lesions consistent with chronic infarct. There were many smaller white matter lesions. Delayed studies showed high signal changes involving the gray matter only on T1-weighted images.
Gradient echo and rapid acquisition with relaxation enhancement (RARE) multislice images revealed a serpentine area of low signal in the left posterior frontal lobe gray matter suggestive of a hemorrhagic infarct, right-sided frontal lesion also showing iron deposits, multiple periventricular and cortical areas with abnormal high signal regions that were consistent with old infarcts, and numerous small vessels readily visible, more prominent on the right.
MRI at 8 T displays lesions with a high resolution and striking anatomic details. Susceptibility to iron and sensitivity to detect blood products are increased at 8 T. The imaging characteristics at high field are different from those at low field, but both represent findings of iron products.
The authors review the pertinent literature dealing with all aspects of cerebral cavernous malformations in the adult. Clinical, neuroradiological, pathological, and epidemiological aspects are presented. The clinical significance of bleeding from cavernous malformations and various hemorrhage patterns are discussed in relation to the factors that influence hemorrhage rates. Recent reports describing the genetic mechanisms of inheritance, de novo formation, and angiogenesis of cavernomas are reviewed as well. Brainstem cavernomas have received special attention, since their clinical management is controversial in the literature. Presently, microsurgical removal is favored by the majority of authors and stereotactic radiosurgery appears to be inappropriate for prevention of bleeding from a cavernoma. Our own case material consists of data of 72 patients operated upon during the past 5 years. Twenty-four patients harbored the lesion within the brainstem, 18 within the deep white matter of the hemispheres, 12 in the basal ganglia or thalamus, 11 in superficial areas of the hemisphere, and seven within the cerebellum. The perioperative morbidity rate was 29.2% (21/72) while the rate of long-term morbidity was 5.5% (4/72), with no mortality in this series. It is concluded that cerebral cavernous malformations, including lesions in critical regions of the brain, can be treated microsurgically with excellent results and an acceptable morbidity.