Case Report. MRI and MR angiography of basilar artery dissection in a child

MRI showed a pontine infarct and mural thickening of intermediate signal in T1-weighted images proximal to occlusion of the basilar artery in a 10-year-old boy. Two days later the mural thickening was of high signal, consistent with methaemoglobin formation and MR angiography (MRA) showed nonspecific lack of flow in the mid-segment of the basilar artery, which corresponded to a tapered occlusion at arteriography. MRI is more useful than MRA for noninvasive diagnosis of basilar artery dissection. Received: 2 August 1996 Accepted: 8 November 1996     

Craniocervical artery dissection: MR imaging and MR angiographic findings

Dissection of the carotid and vertebral arteries is a not so uncommon cause of stroke and has to be considered as a differential diagnosis especially in younger patients. Therapeutic and prognostic implications are different from those in extracranial atherosclerotic disease. Dissection results from hemorrhage into the vessel wall usually between the layers of the media. Digital subtraction angiography (DSA) depicts the resulting luminal compromise that may reveal some typical, but not specific, findings. The same is true for non-invasive angiographic techniques such as time-of-flight magnetic resonance angiography (MRA) and computed tomography angiography (CTA), which have shown accurate results compared with DSA. The main advantage of these techniques is the direct visualization of the vessel wall confirming the intramural hematoma. This is achieved best with MR imaging due to the high signal of blood degradation products on T1- and T2-weighted images. Therefore, MRI in combination with MRA is presently the method of choice for initial diagnosis and follow-up of craniocervical artery dissection (CCAD). In some questionable cases, CTA is a non-invasive alternative that is independent of flow phenomena. Received: 4 May 1998; Revision received: 8 September 1998; Accepted: 10 November 1998     

Intracranial artery dissections: serial evaluation with MR imaging,MR angiography,and source images of MR angiography

BACKGROUND AND PURPOSE: To assess chronological change in intracranial artery dissections with magnetic resonance imaging (MRI), MR angiography (MRA), and source images of MRA, and to determine whether the source images of MRA provide additional useful information to the combined evaluation of MRI and MRA. MATERIALS AND METHODS: Seven consecutive patients with intracranial artery dissections who were diagnosed by clinical history and conventional angiography were followed sequentially with MRI and MRA (mean follow-up duration, 8.8 months). Two observers independently reviewed the signal intensity of the arterial wall on T1-weighted images, luminal structures on MRA, and source images of MRA. RESULTS: In three (43%) of seven patients, the affected arterial wall had high signal intensity area from 4 to 62 days after onset on T-weighted images. Double lumen on MRA wasobserved only in one patient during the course of the study, whereas a definite low-intensity linear area in the lumen on source images of MRA was seen from 0 to 773 days after onset in all patients. When information from the source images of MRA was added to evaluation with both MRI and MRA, detectability increased to 100% from day 0 to day 3 and 67% from day 4 to day 30. CONCLUSION: The signal intensity of the dissected wall and the luminal structures on MRA and its source images vary according to chronological age. The use of source images from MRA in addition to the combined evaluation of MRI and MRA may provide more accurate diagnosis and follow-up study of intracranial artery dissections.     

Dissection of cranial arteries in the neck: correlation of MRI and arteriography

Summary Retrospective correlation of MRI and angiographic findings in nine patients with suspected cervical vascular dissections revealed MRI evidence of vessel abnormalities in eight patients, seven of whom proved to have arterial dissections. One patient whose MRI showed no abnormalities also proved to have a dissection, shown by angiography. Two patients had associated pseudoaneurysms not demonstrated by MRI. Five dissections involved the carotid arteries and three the vertebral arteries. Seven of the nine patients had associated transient neurologic deficits, while two had permanent deficits. Frank infarction of the brain was demonstrated by MRI in five cases. MRI findings suggestive of dissection included: (1) increased signal from the entire vessel; (2) a border of increased signal surrounding the lumen, with luminal narrowing; (3) poor or absent visualization of the vessel; and (4) significant compromise of the vessel lumen by adjacent abnormal increased signal tissue.     

Three-dimensional MRI of hemifacial spasm with surgical correlation

MRI was used to investigate 100 patients with hemifacial spasm, using 3D-FT T2-weighted (CISS) and contrast-enhanced 3D-FT T1-weighted (turbo-FLASH) sequences in all cases. MR angiography was performed in 54 patients, using 3D-MT FISP images. Decompression of the facial nerve through a retromastoid craniotomy was performed in all patients. Hemifacial spasm caused by tumours in the cerebellopontine angle was not included. Vascular contact with the facial nerve root-exit zone or at the internal auditory canal was present in 96 of 100 patients with hemifacial spasm. The vessel responsible was the vertebral artery (VA) in 18 cases, the posterior inferior cerebellar artery (PICA) in 23, the anterior inferior cerebellar artery (AICA) in 22, the VA and PICA in 24, VA and AICA in 3, PICA and AICA in 1, VA, PICA and AICA in 4, and a vein in 1 case. CISS images showed compressive vascular loops better than contrast-enhanced turbo-FLASH images alone. The sensitivity of MRI was high, since only one false-negative case was found among the 100 patients who underwent surgery. Received: 10 July 1995 Accepted: 4 June 1996     

Intracranial contrast-enhancing masses in infants with capillary haemangioma of the head and neck: intracranial capillary haemangioma?

Contrast-enhancing intracranial masses are rarely found in infants with extracranial capillary haemangiomas (CH). We aimed to assess their nature and progression in three patients undergoing CT and/or MRI. The changes in size of both extra- and intracranial lesions were recorded. In a fourth case, a single examination was obtained. All patients harboured one or two enhancing intracranial nodular, meningeal-based lesions. Diffuse leptomeningeal enhancement of the cerebellar surface was also seen in one, which disappeared at follow-up. In all but one of the cases, the intracranial lesions were on the same side as the extracranial CH. These lesions and the extracranial CH demonstrated parallel changes in size (suggesting that both represent CH) during follow-up of 1–2 years: the size of intracranial lesions and the extracranial CH decreased in two cases, whereas it was unchanged in the third. One patient had a persistent trigeminal artery, while another had cerebellar atrophy with high signal in the cortex on T2-weighted images. In some cases, extracranial CH are part of PHACE syndrome; the association with intracranial CH might represent a peculiar phenotype of this rare vascular phakomatosis. As extracranial CH are known to regress spontaneously in the majority of cases, a conservative approach is recommended also for presumed intracranial CH; surgery should be avoided unless follow-up studies demonstrate growth. Received: 7 July 1998 Accepted: 13 October 1998     

MRI in acute subarachnoid haemorrhage; findings with a standardised stroke protocol

There is doubt as to whether acute haemorrhage is visible on MRI. We carried out MRI within 6 h of symptom onset on five patients with minor (low Hunt and Hess grades 1 or 2) subarachnoid haemorrhage (SAH) diagnosed by CT to search for any specific pattern. We used our standard stroke MRI protocol, including multiecho proton density (PD)- and T2-weighted images, echoplanar (EPI) diffusion- (DWI) and perfusion- (PWI) weighted imaging, and MRA. In all cases SAH was clearly visible on PD-weighted images with a short TE. In four patients it caused a low-signal rim on the T2*-weighted source images of PWI, and DWI revealed high signal in SAH. In the fifth patient SAH was perimesencephalic; susceptibility effects from the skull base made it impossible to detect SAH on EPI DWI and T2*-weighted images. Perfusion maps were normal in all cases. MRA and conventional angiography revealed an aneurysm in only one patient. Stroke MRI within 6 h of SAH thus shows a characteristic pattern.     

Utility of the variable flip angle 3D fast-spin echo (isoFSE) sequence on 3T MR for diagnosing vertebrobasilar artery dissection

We aimed to investigate the utility of the isoFSE sequence, one of the variable flip angle 3D fast-spin echo sequences, on 3T-MR for displaying vessel walls and diagnosing vertebrobasilar artery dissection (VAD). We retrospectively evaluated 12 initial and 28 follow-up images from 12 patients diagnosed with either intracranial VAD or carotid artery dissection. The image quality for displaying the vessel wall was scored using a five-point scale (1 poor, 5 excellent) on initial T1-weighted isoFSE images for each region of the arteries. The intracranial artery dissection findings assessed at time points after onset were evaluated on initial and follow-up T1/T2-weighted isoFSE images. For small arteries, including the anterior/posterior inferior cerebellar artery, similar high scores were obtained on both unenhanced and contrast-enhanced T1-weighted isoFSE images (average: 4.7–5.0, p?>?0.2). On unenhanced images, dissected vertebral arteries showed significantly lower scores than non-dissected vertebral arteries for both readers (p?=?0.017 and 0.015, respectively), but the scores were high (3.9 and 4.0, respectively). Definitive findings of VAD were observed on the initial images except in one case. For all cases, definitive findings were seen on at least one of the initial or follow-up images. Temporal changes in the findings could be observed for all cases. In conclusion, we showed favorable wall visualization on T1-weighted isoFSE images and the utility of follow-up imaging using unenhanced-T1/T2-weighted and contrast-enhanced T1-weighted isoFSE sequences with acceptable scan times, which could promote the regular use of 3D black-blood vessel wall imaging.     

MRI and clinical features in amyotrophic lateral sclerosis

MRI of the brain and spinal cord was performed in 21 patients with amyotrophic lateral sclerosis (ALS), 8 normal volunteers and 16 neurological disease controls. High signal was seen in the intracranial corticospinal tract in 16 of the 21 patients on T2-weighted and in 10 on proton density (PD)-weighted images. In one patient, the high signal on T2-weighted images became less marked with progression of the disease. Low signal intensity was seen in the motor cortex in 12 of the 21 patients. High signal in the anterolateral column of the spinal cord on T1 weighted images was seen in 14, and high signal in the lateral corticospinal tract on T2 weighted images was seen in 7 of the 21 patients. The relationship between the abnormal images and upper motor neurone signs remained unclear. High signal intensity was seen in the corticospinal tract in the brain on T2-weighted images in two normal volunteers and four disease controls, and on PD weighted images in three disease controls. Low signal intensity in the motor cortex on T2 weighted images was seen in three normal volunteers and four disease controls. However, high signal intensity was seen in the intracranial corticospinal tract on T1 weighted images in five patients with ALS who showed pronounced upper motor neurone signs including spastic paraparesis, but not in controls. Thus, abnormalities on MRI in the brain and spinal cord should be considered in the diagnosis of ALS, and high signal intensity of the intracranial corticospinal tract on T1-weighted images may reflect the severe pathological changes of the upper motor neurones in ALS. Received: 18 March 1997 Accepted: 2 May 1997     

Extracranial internal carotid and vertebral artery dissections: angiographic spectrum,course and prognosis

We reviewed the clinical and radiological findings of 93 consecutive patients with 111 extracranial internal carotid (ICAD) and vertebral artery (VAD) dissections and one concomitant intracranial VAD; 83% of the patients had unilateral and 17% multiple vessel dissections. The diagnosis was made by intra-arterial digital subtraction angiography in 92 patients and MR angiography in one. Follow-up angiography was performed in 77 cases (83%): of 49 initially stenotic arteries, 40 became completely or almost completely normal, while three showed slight improvement. Of 30 initially occluded arteries, nine had completely or partly recanalised. Of 12 pseudoaneurysms eight were unchanged at follow-up. The proximal vertebral artery was involved as often as the C1-C2 level. Recurrences were rare: a new dissection in another vessel was found in three patients. Kinking or coiling was found in 23% of the dissected internal carotid arteries.     

MRI of spinal epidural lymphoma

We reviewed the MRI features in eight patients with spinal epidural lymphoma (clinically primary in 4 patients); one patient had multiple lesions. The cervical spine was involved in one patient, the thoracolumbar spine in 5 and the sacrum in two. Mean longitudinal extension of the epidural lesion was 2.6 vertebral segments. The tumours were homogeneously isointense with the spinal cord on T1-weighted images and isointense or hyperintense on proton-density and T2-weighted images. The spinal cord was compressed in four patients but showed signal changes in only one. In five patients the lesions communicated through the intervertebral formaina with paravertebral soft tissue masses. In all but one of the patients diffuse signal changes in the vertebral body marrow consistent with osteolytic or osteobalstic changes were identified adjacent to or at distance from the epidural lesion. Vertebral collapse was observed in two patients.     

MR imaging of intracranial vertebral artery occlusion

Summary Magnetic resonance (MR) images of nine patients with intracranial vertebral artery occlusion (five proved, four presumed) have been reviewed. In two of nine, both vertebral arteries were occluded and in five of the nine, the basilar artery was also blocked. All occluded arteries showed absence of flow void and were clearly demonstrated as mildly hypo-mildly hyperintense structures to brainstem parenchyma on the T1-weighted images. In two of five patients with basilar artery occlusion, retrograde filling of the distal basilar artery was detected. Thus, MR imaging, in particular the T1-weighted image, is a pertinent diagnostic modality for evaluating intracranial vertebral artery occlusion. Angiography does not seem to be required for confirmation.     

软组织脉管畸形的MRI诊断

目的 探讨MRI对软组织脉管畸形的诊断价值.资料与方法 回顾性分析575例脉管畸形患者的MRI表现.结果 490例血管畸形,T1WI等信号88例,混杂信号402例;T2WI不均匀高信号475例,较均匀高信号15例,圆形血管样高信号210例,在病变的边缘可见尖角样改变216例.43例淋巴管畸形,T1WI等信号2例,混杂信号36例;T2WI不均匀高信号38例,5例T1WI、T2WI表现为脂肪增厚,另见囊状灶26例.42例血管、淋巴管混合畸形,T1WI等信号2例,混杂信号40例;T2WI不均匀高信号42例.结论 MRI能反映脉管畸形的特征,对其诊断与鉴别诊断有重要价值.     

Magnetic resonance signal intensity and volume changes after endovascular treatment of intracranial aneurysms causing mass effect

To determine when and how intracranial aneurysms causing mass effect change following endovascular treatment, we used MRI to assess patients for 2–3 years after the interventional procedure. Nine patients who had aneurysms compressing the surrounding structures underwent endovascular treatment. Proximal occlusion of the parent artery was performed in seven cases, and in two the aneurysm was embolised with microcoils. After embolisation, signal intensity within aneurysms tended to be high on both T1- and T2-weighted images. When there was rapid reduction in size high-signal zones within aneurysms became isointense or gave low signal on T1-weighted images. On T2-weighted images, isointense or low-signal foci appeared within high-signal areas in the aneurysm, giving mixed intensity. In typical cases, the mean volume of the aneurysm fell to approximately 30 % of its initial value 2–12 months after treatment. After this, no additional reduction was observed. The aneurysms which showed little signal intensity change tended to shrink more slowly and to a lesser degree than the more typical cases. Aneurysms which gave high signal on both T1- and T2-weighted images early following embolisation shrank more quickly than those showing little signal change. Received: 24 February 1997 Accepted: 19 June 1997     

2D time-of-flight MR angiography using concatenated saturation bands for determining direction of flow in the intracranial vessels

We prospectively studied 15 patients to assess 2D time-of-flight (TOF) magnetic resonance angiography (MRA) with concatenated saturation bands for determining the direction of intracranial blood flow. This MRA sequence was compared to T2-weighted spin-echo MRI, 3D-TOF MRA, and intra-arterial angiography (IAA) as regards demonstration of vessels and determination of the direction of flow in the circle of Willis and its branches. The 2D-TOF MRA sequence demonstrated flow in 98.5 % vessel segments identified on IAA, 3D-TOF demonstrating 92 % and spin-echo images 77 %. The direction of flow shown on the 2D-TOF sequence was correct in 94 % when compared to conventional angiography, the remaining six segments not demonstrating flow. In ten patients, the flow abnormalities demonstrated by this MRA technique provided clinical information similar to that of conventional angiography in nine, but it was incomplete in three, and misleading in one. Slow retrograde flow in ophthalmic artery collaterals and differentiation of arteries and veins presented some problems. 2D-TOF MRA with concatenated saturation bands provides flow direction information using widely available, easily applicable TOF techniques, and can be a useful adjunct to MRI and MRA if information on flow direction is needed. Received: 18 October 1995 Accepted: 16 August 1996     

Carotid and vertebral artery trauma: clinical and angiographic features.

Injury to the carotid or vertebral artery is an important clinical entity that requires angiography for definitive diagnosis and evaluation. The common carotid artery may be injured by penetrating trauma while the internal carotid artery is usually damaged by either trivial or blunt trauma. With trivial trauma extracranial internal carotid artery dissection should be considered if there is unilateral headache, Horner's syndrome or delayed transient ischaemic attack, and intracranial dissection if a profound neurological defect occurs immediately following trauma. Injury to the internal carotid artery following blunt trauma includes dissection of the extracranial internal carotid artery, carotid-cavernous fistula and pseudoaneurysm formation. These should be considered in a patient with delayed neurological deficit, mandibular or skull fracture, a constellation of orbital signs or diffuse subarachnoid haemorrhage, respectively. Vertebral artery injury is less frequent. Dissection typically follows abrupt cervical rotation and occurs at C1-2, whereas penetrating trauma may involve either the proximal or distal vertebral artery and occlusion, arteriovenous fistula or pseudoaneurysm may be found. Endovascular techniques may be used in either the carotid or vertebral artery to close fistulae or occlude an extensively damaged vessel.     

Carotid and vertebral artery dissections: clinical aspects, imaging features and endovascular treatment

Extracranial arterial dissections are a recognised cause of stroke, particularly in young adults. Clinical diagnosis may be difficult, and the classical triad of symptoms is uncommon. Imaging plays a pivotal role in the diagnosis of extracranial arterial dissections, and this review provides a detailed discussion of the relative merits and limitations of currently available imaging modalities. Conventional arteriography has been the reference standard for demonstrating an intimal flap and double lumen, which are the hallmarks of a dissection, and for detecting complications such as stenosis, occlusion or pseudoaneurysm. Noninvasive vascular imaging methods, such as ultrasound (US), magnetic resonance angiography (MRA) and computed tomography angiography (CTA) are increasingly replacing conventional angiography for the diagnosis of carotid and vertebral dissections. Ultrasound provides dynamic and "real-time" information regarding blood flow. Source data of MRA and CTA and additional cross-sectional images can provide direct visualisation of the mural haematoma and information about the vessel lumen. Anticoagulation to prevent strokes is the mainstay of medical treatment, but randomised trials to define the optimal treatment regime are lacking. Surgery has a limited role in management of dissections, but endovascular procedures are gaining importance for treatment of complications and if medical management fails.     

MRI appearances of calcified regions within intracranial tumours

The MRI appearances of calcification within intracranial tumours was assessed by reviewing MR images of 11 calcified tumours documented by CT. The signal intensity of the calcified regions was varied and nonspecific on both T1-and T2-weighted images. They were seen as signal void exclusively on T2-weighted images in only 2 patients. Gadolinium enhancement of the calcified portion occurred in 7 of 10 patients. These findings reflect the presence of tumour parenchyma within the calcified region, as proved in 5 lesions examined histologically.     

Contrast-enhanced MR angiography of the supra-aortic vessels in 24 seconds: a feasibility study

A contrast-enhanced, gradient-echo 3D pulse sequence providing angiographic information in 24 s was tested in five healthy subjects and used prospectively in 21 patients for the investigation of the cervical arteries. Indications included suspected stenosis of the carotid (in 13), or vertebral arteries (in 1), carotid dissection (3), variants of the branches of the aortic arch (2) and extracranial carotid aneurysms (2). The results in all patients were compared with those of intra-arterial digital subtraction angiography (DSA). In patients with carotid stenosis, they were also compared with high-resolution 3D time-of-flight (TOF) MR angiography (MRA). Good quality MR angiograms of the neck vessels were obtained with the fast 3D sequence in 20 of the 21 patients. One claustrophobic patient was unable to co-operate. The degree of internal carotid artery (ICA) stenosis was graded correctly (compared to DSA) in 21 of 24 cases (87.5 %). Two mild stenoses were overestimated as moderate using the fast MR sequence and one high-grade stenosis was misdiagnosed as a complete occlusion. Carotid dissection was confirmed in one case and correctly excluded in two. Four extracranial ICA aneurysms in two patients, arterial variants and stenosis of the origin of the vertebral artery were correctly diagnosed using the contrast-enhanced MR angiogram. Three-dimensional TOF MRA was unsuccessful due to motion artefacts in half of the cases of ICA stenosis. Received: 6 August 1998 Accepted: 21 December 1998     

流动伪影在颅内动脉瘤MRI诊断中的价值

目的 评价流动伪影对颅内动脉瘤的诊断价值。资料与方法 搜集经DSA(10例)或手术(5例)证实的15例同时合并有流动伪影的颅内动脉瘤的MRI和MRA资料进行回顾分析。使用Siemens Impact1．0T超导型MR扫描仪。全部患者均行脑MRSE序列扫描，13例行3D TOF MRA动脉期扫描。结果 15例颅内动脉瘤共显示29个流动伪影，在所有MR序列图像上均表现为动脉瘤残腔水平的不规则条带状影，且均位于相位编码方向上。T2WI较T1WI上所显示的伪影更为粗大、明显。结论 合理地应用流动伪影有助于颅内动脉瘤的诊断和鉴别诊断。