Wegener granulomatosis: MR imaging findings in brain and meninges

PURPOSE: To determine the spectrum of intracranial magnetic resonance (MR) imaging appearances of Wegener granulomatosis. MATERIALS AND METHODS: MR imaging studies in 19 patients with Wegener granulomatosis and possible central nervous system involvement were reviewed by two neuroradiologists. Intermediate-weighted and T2-weighted fast spin-echo MR images of the brain had been acquired in all patients, and spin-echo T1-weighted nonenhanced and gadolinium-enhanced images had been acquired in 18 patients. RESULTS: MR imaging findings included diffuse linear dural thickening and enhancement (n = 6); focal dural thickening and enhancement contiguous with orbital, nasal, or paranasal disease (n = 5); infarcts (n = 4); nonspecific white matter areas of high signal intensity on intermediate-weighted and T2-weighted images (n = 10); enlarged pituitary gland with infundibular thickening and enhancement (n = 2); a discrete cerebellar lesion that was probably granulomatous in origin (n = 1); and cerebral (n = 8) and cerebellar atrophy (n = 2). CONCLUSION: MR imaging demonstrated the wide spectrum of findings of central nervous system involvement in patients with Wegener granulomatosis and was particularly useful for the evaluation of direct intracranial spread from orbital, nasal, or paranasal disease.     

MR Imaging in Wegener granulomatosis of the spinal cord

Wegener granulomatosis is a multisystemic disorder characterized by necrotizing vasculitis that primarily involves the respiratory tract. The orbits, heart, skin, joints, and nervous system are frequently involved. We describe the MR imaging findings of Wegener granulomatosis in the cervical spine and correlate them with the histopathologic features. MR imaging showed epidural liquid masses surrounded by granulomatous masses that compressed the cervical myelin from behind.     

MR imaging of cardiac mass in Wegener granulomatosis

Wegener granulomatosis is a disorder of unknown etiology characterized by a necrotizing granulomatous vasculitis that primarily affects the paranasal sinuses, lungs, and kidneys. It is usually a disease of adults with infrequent cardiac involvement. We report the unusual presentation of this disorder in an adolescent with a cardiac mass. The findings on two-dimensional echocardiography and MR imaging are discussed.     

High-Resolution MRI Vessel Wall Imaging: Spatial and Temporal Patterns of Reversible Cerebral Vasoconstriction Syndrome and Central Nervous System Vasculitis

BACKGROUND AND PURPOSE:High-resolution MR imaging is an emerging tool for evaluating intracranial artery disease. It has an advantage of defining vessel wall characteristics of intracranial vascular diseases. We investigated high-resolution MR imaging arterial wall characteristics of CNS vasculitis and reversible cerebral vasoconstriction syndrome to determine wall pattern changes during a follow-up period.MATERIALS AND METHODS:We retrospectively reviewed 3T-high-resolution MR imaging vessel wall studies performed on 26 patients with a confirmed diagnosis of CNS vasculitis and reversible cerebral vasoconstriction syndrome during a follow-up period. Vessel wall imaging protocol included black-blood contrast-enhanced T1-weighted sequences with fat suppression and a saturation band, and time-of-flight MRA of the circle of Willis. Vessel wall characteristics including enhancement, wall thickening, and lumen narrowing were collected.RESULTS:Thirteen patients with CNS vasculitis and 13 patients with reversible cerebral vasoconstriction syndrome were included. In the CNS vasculitis group, 9 patients showed smooth, concentric wall enhancement and thickening; 3 patients had smooth, eccentric wall enhancement and thickening; and 1 patient was without wall enhancement and thickening. Six of 13 patients had follow-up imaging; 4 patients showed stable smooth, concentric enhancement and thickening; and 2 patients had resoluton of initial imaging findings. In the reversible cerebral vasoconstriction syndrome group, 10 patients showed diffuse, uniform wall thickening with negligible-to-mild enhancement. Nine patients had follow-up imaging, with 8 patients showing complete resolution of the initial findings.CONCLUSIONS:Postgadolinium 3T-high-resolution MR imaging appears to be a feasible tool in differentiating vessel wall patterns of CNS vasculitis and reversible cerebral vasoconstriction syndrome changes during a follow-up period.

Reversible cerebral vasoconstriction syndrome (RCVS) and CNS vasculitis are 2 distinct cerebrovascular disease entities with overlapping presenting symptoms of headache and, not uncommonly, neurologic deficits, which may be secondary to ischemic and/or hemorrhagic stroke.^1–4 Expeditious diagnosis is critical to discriminate the 2 disease entities to initiate appropriate and timely treatment.⁴ In addition to clinical and laboratory work-up, DSA, MRA, and CTA are the preferred imaging modalities, essential to diagnosis and disease management. However, current vascular imaging fails to distinguish both entities, often due to shared nonspecific luminal findings on DSA, MRA, and CTA.^1,5Radiographic discrimination using current vascular imaging is difficult due to the relative thinness of intracranial vessel walls, at most, 1–2 mm thick in the largest intracranial vessels. The size scale is near the resolution limit of present imaging technology. While DSA provides superior resolution, it only images the vessel lumen. CTA and MR imaging, on the other hand, can image extraluminal tissue; however, the resolution is near the limit for imaging the vessel wall. Of these methods, MR imaging tends to be the technique of choice due to its superior soft-tissue contrast compared with CTA. Thus, the successful application of MR imaging to scan the vessel wall would require using a higher resolution than is routinely used in clinical practice while using standard clinical imaging hardware. This is accomplished by extending the technical parameters of a clinical MR imaging scanner as much as possible within the limits of the scan time and signal and is termed “high-resolution MR imaging” (HRMRI).The utility of HRMRI in characterizing vessel wall patterns of intracranial artery diseases has been investigated.^6–9 Recent studies have identified distinct characteristics of arterial wall thickening and wall enhancement in RCVS and CNS vasculitis.^6,7 While these studies have described spatial patterns on HRMRI, they have not described the temporal evolution of these diseases; this information could further aid diagnosis and management. The aim of this study was to describe the spatial patterns and temporal evolution of RCVS and CNS vasculitis by examining vessel wall characteristics during a follow-up period by using 3T-HRMRI and thereby assess the potential of HRMRI to serve as a surveillance technique to identify changes in wall morphology with disease progression or remission. We hypothesized that 3T-HRMRI vessel wall imaging may differentiate the spatial and temporal patterns of RCVS and CNS vasculitis.     

MR imaging findings of spinal dural involvement with Wegener granulomatosis

Involvement of the brain and meninges is rare in cases of Wegener granulomatosis, occurring in 2% to 8% of cases. Meningeal involvement in association with Wegener granulomatosis has scarcely been reported as being confined to the dura mater of brain on images and is thought to represent granulomatous infiltration. There are a few reported cases of Wegener granulomatosis that document involvement of dura at the level of the spinal cord. We present the case of a 52-year-old man with Wegener granulomatosis involving the cervical spinal dura and include detailed MR imaging findings.     

Pulmonary manifestations of wegener granulomatosis: CT findings in 57 patients and a review of the literature

Wegener granulomatosis is a multisystem disease of unknown cause characterized by a necrotizing granulomatous vasculitis. In comparison to other vasculitides, the lung is the most common organ involved in wegener granulomatosis presenting with a very aggressive airways pathology and chronic relapsing course. Chest radiographs fail to describe the pattern and distribution of thoracic pathology sufficiently, and CT has shown to be more sensitive for detecting lung involvement. We present the CT findings of 57 patients with wegener granulomatosis and a review of the literature.     

Acute spinal subdural hematoma: MR and CT findings with pathologic correlates.

PURPOSETo determine the MR and CT findings that characterize acute spinal subdural hematoma (ASSH).METHODSThe MR, CT, and clinical findings in three patients with surgically proved ASSH were reviewed and also correlated with the postmortem MR, CT, and cryomicrotome findings in three other patients, two with ASSH and one with an acute spinal epidural hematoma.RESULTSImaging findings in ASSH included: (a) hyperdense lesions on plain CT within the dural sac, distinct from the adjacent low-density epidural fat and silhouetted against the lower-density spinal cord and cauda equina, which it compressed; (b) lack of direct continuity with the adjacent osseous structures; (c) clumping, loculation, and streaking of blood within the dural sac on both MR and Ct; and (d) an inhomogeneous and variable signal intensity to the ASSH on all MR pulse sequences, but, nevertheless, a striking low signal intensity on T2-weighted spin-echo or T2-weighted gradient-echo to a major part of the ASSH because of deoxyhemoglobin. Plain CT was most helpful in compartmentalizing the hematoma.CONCLUSIONWhen MR and plain CT are obtained as complementary studies, they provide characteristic findings that allow the prompt diagnosis of ASSH.     

Common and uncommon manifestations of Wegener granulomatosis at chest CT: radiologic-pathologic correlation

Wegener granulomatosis is an uncommon necrotizing vasculitis that classically manifests as a clinical triad consisting of upper and lower airway involvement and glomerulonephritis. Other less frequently involved organ systems include the central and peripheral nervous system and large joints. The diagnosis is based on a combination of clinical and laboratory findings. Because thoracic involvement often predominates, chest radiographic findings are often the first to suggest the diagnosis. However, chest computed tomography (CT) has superior sensitivity and specificity for evaluation of the airways, lung parenchyma, and mediastinum, particularly with the use of multiplanar reformatted and three-dimensional images. Common pulmonary radiologic findings include waxing and waning nodules, masses, ground-glass opacities, and consolidation. Airway involvement is usually characterized by circumferential tracheobronchial thickening, which can be smooth or nodular. Pleural effusions are the most common manifestation of pleural disease and can result from primary involvement or be secondary to renal failure. Mediastinal lymphadenopathy is a nonspecific finding and is usually reactive. Uncommon thoracic radiologic manifestations include involvement of the heart and great vessels. CT is the imaging modality of choice for diagnosis, surveillance, and follow-up in patients with Wegener granulomatosis.     

Normal appearance of arachnoid granulations on contrast-enhanced CT and MR of the brain: differentiation from dural sinus disease.

PURPOSETo determine the imaging appearance and frequency with which arachnoid granulations are seen on contrast-enhanced CT and MR studies of the brain.METHODSWe retrospectively reviewed 573 contrast-enhanced CT scans and 100 contrast-enhanced MR studies of the brain for the presence of discrete filling defects within the venous sinuses. An anatomic study of the dural sinuses of 29 cadavers was performed, and the location, appearance, and histologic findings of focal protrusions into the dural sinus lumen (arachnoid granulations) were assessed and compared with the imaging findings.RESULTSDiscrete filling defects within the dural sinuses were found on 138 (24%) of the contrast-enhanced CT examinations. A total of 168 defects were found, the majority (92%) within the transverse sinuses. One third were isodense and two thirds were hypodense relative to brain parenchyma. Patients with filling defects were older than patients without filling defects (mean age, 46 years versus 40 years). Discrete intrasinus signal foci were noted on 13 (13%) of the contrast-enhanced MR studies. The foci followed the same distribution as the filling defects seen on CT scans and were isointense to hypointense on T1-weighted images, variable in signal on balanced images, and hyperintense on T2-weighted images. Transverse sinus arachnoid granulations were noted adjacent to venous entrance sites in 62% and 85% of the CT and MR examinations, respectively. Arachnoid granulations were found in 19 (66%) of the cadaveric specimens, in a similar distribution as that seen on the imaging studies.CONCLUSIONDiscrete filling defects, consistent with arachnoid granulations, may be seen in the dural sinuses on 24% of contrast-enhanced CT scans and on 13% of MR studies. They are focal, well-defined, and typically located within the lateral transverse sinuses adjacent to venous entrance sites. They should not be mistaken for sinus thrombosis or intrasinus tumor, but recognized as normal structures.     

Evaluation of Wegener’s granulomatosis using 18F-fluorodeoxyglucose positron emission tomography/computed tomography

Objective

Wegener’s granulomatosis (WG) is a relatively rare disease characterized by granulomatous necrotizing vasculitis that primarily involves small- and medium-sized vessels. Systemic findings observed on ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) have not been well reported. The purpose of this study was to evaluate the FDG PET/CT imaging in the diagnosis and follow-up of patients with WG.

Materials and methods

Thirteen FDG PET/CT images obtained for 8 patients (2 men and 6 women) with WG were retrospectively analyzed. Of these, 6 were performed for diagnosis, 2 for restaging and follow-up, and 5 for assessment of treatment efficacy. Maximum standardized uptake values (max SUVs) and visual analyses were used to interpret the FDG PET/CT images. In addition, nonenhanced CT findings obtained during FDG PET/CT were described.

Results

WG lesions of the upper respiratory tract and lung were more clearly detected by FDG PET/CT fusion imaging than by nonenhanced CT alone, and all of the active lesions showed decreased FDG uptake after treatment. In addition, FDG PET/CT can provide complementary information to indicate biopsy site based on FDG uptakes.

Conclusions

FDG PET/CT is a feasible modality for evaluating lesion activities, therapeutic monitoring, and follow-up of WG. Furthermore, biopsy sites of WG lesions may be determined by FDG PET/CT.     

Wegener granuloma in the fourth ventricle

We report the case of a 57-year-old man with a known history of antineutrophil cytoplasmic antibody-positive Wegener granulomatosis with initial involvement of the upper and lower respiratory tract. MR imaging of the brain was performed because of new onset CNS symptoms (nausea, altered mental status). The images revealed a mass in the fourth ventricle. The mass diminished in size after systemic steroid treatment, as shown by follow-up MR imaging. The patient died in acute respiratory distress secondary to pneumonia. Histopathologic findings confirmed a Wegener granuloma of the fourth ventricle.     

Intracranial hemangiopericytomas: MR and CT features.

PURPOSETo describe the MR and CT imaging features of hemangiopericytoma and to identify the characteristics that might distinguish them from meningioma.METHODSWe retrospectively reviewed the CT and MR findings in 34 pathologically proved cases of hemangiopericytoma. We evaluated the size, shape, and location of the tumor; the presence of hydrocephalus, edema, and mass effect; the type of dural attachment (broad-based or narrow-based) and bone changes (erosion, hyperostosis); and the tumor''s density, signal, and contrast-enhancement characteristics.RESULTSThirty of 34 tumors were 4 cm or more in greatest dimension, 32 were lobular, and only seven were in the posterior fossa. Hydrocephalus was present in 18, edema in 30, and mass effect in 33. Twenty-three had broad-based dural attachment and 11 had narrow-based attachment. All 26 unenhanced CT scans showed hyperdense tumors; 19 were heterogeneous and seven homogeneous. All 27 contrast-enhanced CT scans showed enhancement; 17 were heterogeneous and 10 homogeneous. Bone erosion was present in 17 of 29 hemangiopericytomas imaged with CT. None had hyperostosis or tumor calcifications. On T1-weighted MR images, 13 of 17 tumors were isointense with cortical gray matter; on T2-weighted image, 10 of 17 were isointense. All 14 tumors imaged with contrast enhanced T1-weighted MR imaging showed enhancement, and 13 of these were heterogeneous; eight of the 14 had a "dural tail" sign.CONCLUSIONIntracranial hemangiopericytomas are multilobulated, extraaxial tumors, sometimes associated with narrow-based dural attachment and bone erosion. Unlike with meningiomas, hyperostosis and intratumoral calcification are not present.     

Wegener肉芽肿影像表现

目的提高对Wegener肉芽肿影像认识。方法收集本院1997-01～2004-04资料完整临床确诊为Wegener肉芽肿病例10例,回顾性分析其影像学表现。结果8例鼻窦受累,表现为双侧鼻窦黏膜不同程度增厚,其中3例中线结构破坏。2例眼眶浸润。1例喉狭窄。7例肺部病变,其中3例表现为典型的多发结节和空洞,其余表现为双肺散在渗出、小结节,多种征象并存,1例支气管阻塞合并左上肺不张。结论Wegener肉芽肿累及多器官,影像表现多样和复杂,诊断应结合临床、实验室检查和病理动态观察。     

Neurologic involvement in Beh?et disease: imaging findings in 16 patients

Beh?et disease is a rare multisystem immune-related vasculitis that is prevalent in Japan, the Middle East, and many Mediterranean countries. In our study population of 36 patients with Beh?et disease, 16 (44%) had CNS involvement. CT was noncontributory, except in a single patient with dural sinus thrombosis. MR imaging in nine patients showed foci of high signal intensity on T2-weighted images within the brainstem, the basal ganglia, and the cerebral hemispheres in that order of frequency. Unlike the plaques associated with multiple sclerosis, Beh?et lesions show no predilection for the periventricular regions.     

Wegener granulomatosis: CT features of parenchymal lung disease

Chest CT from eight patients with pulmonary Wegener granulomatosis were reviewed. The CT features of parenchymal lung involvement included multiple nodules or masses (seven of eight; 88%), ranging in size from 0.3 to 5.0 cm. Lung nodules demonstrated distinct feeding vessels in seven of eight patients (88%); and lesions similar to pulmonary infarcts, i.e., peripheral wedge-shaped lesions abutting the pleura, were identified in seven cases (88%). Scarring, spiculation, and pleural tags emanating from pulmonary nodules were prominent features (seven of eight; 88%). Other findings included cavitation (four of eight; 50%), air bronchograms through nodules (two of eight; 25%), and pleural effusions (two of eight; 25%). One patient on immunosuppressant therapy also demonstrated scattered ground glass infiltrates due to complicating pneumocystis pneumonia. In comparison to corresponding conventional chest radiography, CT examinations revealed more parenchymal lesions in five of eight cases (63%) and bilateral disease instead of unilateral disease in one of eight cases (13%). Feeding vessels were only identified on CT. Wegener granulomatosis is a primary necrotizing granulomatous vasculitis, and when it affects the lung it demonstrates CT features that are similar to other vessel-related disorders of the lung such as septic emboli, pulmonary infarcts, and tumor emboli of hematogenous metastases. We believe that these CT features--nodules with feeding vessels and wedge-shaped lesions abutting the pleura--are related to the necrotizing angiitis that affects pulmonary arteries and veins in this disease.     

Wegener granulomatosis of the eustachian tube and skull base mimicking a malignant tumor.

Wegener granulomatosis is a well-studied yet sometimes difficult-to-diagnose systemic vasculitis. Early treatment with immunosuppressants is the therapy of choice and usually controls the disease. Two cases of Wegener granulomatosis are presented, both with symptoms and imaging findings suggestive of a malignant tumor of the nasopharynx or skull base. The focus of upper respiratory involvement in each case was the eustachian tube.     

Hypertrophic cranial pachymeningitis: assessment with CT and MR imaging

Three patients with diffuse idiopathic cranial pachymeningitis with predominant involvement of the tentorium and falx are reported. Progressively increasing headaches were the usual symptoms, along with ataxia and various cranial nerve palsies. CT in all cases and MR imaging in two cases detected isolated thickened dura mater. In one case, MR depicted dural involvement as a very large, hypointense area with fine hyperintense edges on T2-weighted images. Microscopic examination of thickened dura revealed extensive fibrotic tissue with a chronic inflammatory infiltrate containing lymphocytes, plasma cells, and scattered eosinophils; these findings closely paralleled the MR features. Only four cases with similar pathologies have been described, all before the advent of CT and MR. We discuss the different causes of thickened dura mater as well as the significance of the fact that dural thickening can be responsible for occlusion of the dural sinuses. Cranial pachymeningitis is a rarely reported disease that can resemble other disorders associated with tentorial thickening; CT and MR can help differentiate it from these other disorders.     

Neurosarcoidosis presenting as acute infarction on diffusion-weighted MR imaging: summary of radiologic findings

A 36-year-old woman presented with acute-onset right lower extremity paresthesias, dysarthria, right facial droop, and right hemiparesis. CT and MR imaging of the brain revealed extensive white matter disease and left basal ganglia infarction with dural and leptomeningeal enhancement. Differential considerations included vasculitis, granulomatous disease, and neoplasm. Chest, abdomen, and pelvis CTs were normal. Right temporal lobe biopsy revealed noncaseating granulomatous inflammation consistent with neurosarcoidosis.     

Migration of Bone Wax into the Sigmoid Sinus after Posterior Fossa Surgery

BACKGROUND AND PURPOSE:Bone wax is a hemostatic agent that has been reported in some instances to migrate into the sigmoid sinus following posterior fossa surgery. The purpose of this study was to characterize the CT and MR imaging findings of this entity.MATERIALS AND METHODS:The study included 212 consecutive patients who underwent posterior fossa surgery and postoperative CT and contrast-enhanced MR imaging. The presence of sigmoid sinus bone wax migration was determined with the following criteria: sigmoid sinus filling defect showing low signal on all MR imaging pulse sequences; sigmoid sinus filling defect showing low CT attenuation, similar to fat attenuation; and clinical confirmation that bone wax was used intraoperatively. CT and MR imaging of an in vitro bone wax sample was also performed.RESULTS:We identified 6 cases of sigmoid sinus bone wax migration. In each case, a low-signal-intensity, low-attenuation filling defect was noted in the sigmoid sinus. The morphology was linear (n = 3) or globular (n = 3). In patients with serial imaging, the appearance of migrated bone wax remained stable over time. No adverse outcomes related to sigmoid sinus bone wax migration were encountered. In vitro imaging of bone wax confirmed low CT attenuation and low MR imaging signal intensity on T1WI and T2WI.CONCLUSIONS:Bone wax migration into the sigmoid sinus is a recognizable imaging finding after posterior fossa surgery that appears to have a benign clinical course. The finding should be distinguished from more serious complications, such as venous sinus thrombosis.

Bone wax is commonly used during the course of posterior fossa craniotomy to control bleeding from emissary veins or to pack violated mastoid air cells. The mastoid emissary vein often lies close to or within the retrosigmoid or suboccipital craniotomy bed and represents a channel in direct communication with the sigmoid sinus.¹ Awareness of the use of this agent is important in assessing postoperative imaging because its presence within a dural venous sinus might be mistaken for air, fat, or thrombus. The particular imaging characteristics of this agent can aid appropriate diagnosis. The appearance has been reported in the literature as low attenuation on CT (intermediate between fat and simple fluid) and as a signal void on MR imaging (attributable to its semicrystalline solid nature).² To our knowledge, only 2 prior studies of sigmoid sinus bone wax migration (including 8 total cases) have been reported in the literature, and conventional MR imaging features of the migrated bone wax were reported in only 1 of these cases.^3,4 The purpose of our study was to describe the CT and MR imaging features of sigmoid sinus bone wax migration after posterior fossa surgery. We also sought to assess the CT and MR imaging features of an in vitro bone wax sample.     

'Leave me alone' lesions of the petrous apex.

PURPOSEWhen troublesome MR imaging findings are noted in the petrous apex, the radiologist must determine if the area in question needs surgical therapy. Two nonsurgical entities, asymmetric fatty marrow and fluid-filled petrous air cells (trapped fluid), can be noted on conventional brain MR images and confused with pathologic lesions. Our observation that radiologists do not always confidently define the nonsurgical petrous apex lesions precipitated this investigation.METHODSTwenty-three patients with either asymmetric fatty marrow (six) or unilateral effusion in a pneumatized petrous apex (17) on MR images were studied. Eighteen patients underwent high-resolution temporal bone CT. For all patients, the medical charts were reviewed retrospectively and/or the surgical and clinical follow-up findings were reviewed with the referring physician.RESULTSIn the patients with asymmetric fatty marrow, MR signal intensity followed fat on all sequences. The questioned apex in the patients with trapped fluid showed mixed MR signal characteristics (low to high T1 signal, high T2 signal). CT scans confirmed nonexpansile air-cell opacification.CONCLUSIONAsymmetric fatty marrow in the petrous apex and petrous air-cell effusions have characteristic MR and CT features that facilitate their correct diagnosis. Effusions with intermediate or high T1 signal are most frequently confused with cholesterol granulomas. In those patients, long-term CT follow-up may be helpful to confirm their stability.