Acute subarachnoid haemorrhage: 3D time-of-flight MR angiography versus intra-arterial digital angiography

Cerebral Digital Subtraction Angiography in Acute Intracranial Hemorrhage: Considerations in Critically Ill Children

Cerebrovascular disorders are an important cause of morbidity and mortality in children. Although minimally invasive, cerebral digital subtraction angiography (DSA) has been shown to be safe in children and is a valuable, and perhaps underutilized, technique for the diagnosis and management of pediatric cerebrovascular disorders in the critical care setting. Through a case-based approach, we explore the utility of DSA in critically ill children with acute intracranial hemorrhage (ICH). We discuss the use of DSA in the acute management of aneurysm and arteriovenous malformation rupture as well as cerebral vasospasm. Those caring for critically ill children with acute ICH should consider cerebral DSA as part of a comprehensive approach to the diagnosis and management of these conditions.

Ultra high field TOF-MRA: A method to visualize small cerebral vessels. 7T TOF-MRA sequence parameters on different MRI scanners - Literature review

INTRODUCTION

Time-of-flight (TOF) angiography is a technique allowing to visualize the blood flow in vessels. 7T ToF-MRA is able to visualize the whole Circle of Willis including small perforating branches without any known side effects as opposed to usually used DSA and CTA with high exposition to the radiation and high doses of contrast as far as CTA is concerned.

AIM

The aim of this review is to describe ultra-high field ToF-MRA and present different protocol data depending on the scanner used in the study.

MATERIALS AND METHODS

PubMed, Embase, Ovid, Google Scholar databases were searched. Selection of studies for this systematic review included 7T magnetic resonance angiography studies. We searched for type of head coil used in various studies, flip angle, echo time, repetition time, field-of-view (FOV), number of slices per slab, matrix, voxel size and acquisition time.

DISCUSSION

Visualization for the small perforating vessels of the Circle of Willis, that are not fully visualized using low-field-strength MRA is improving with increasing magnetic field strength, which has been proved by several studies.

CONCLUSION

Ultra-high filed ToF-MRA has found to be a superior method in depicting cerebral microvasculature. 7T ToF-MRA seems to be a reliable method for visualization of arteries up to the second order cerebral arteries and has a potential to replace DSA.

Valutazione degli aneurismi cerebrali con Angio-RM

Una delle applicazioni più studiate dell'angiografia a risonanza magnetica è rappresentata dallo studio degli aneurismi cerebrali.

In molti casi infatti è possibile ottenere immagini molto vicine a quelle dell'angiografia digitale arteriosa; tuttavia sono spesso presenti inconvenienti tecnici (scarso rapporto segnale/rumore e caduta del segnale di flusso a causa di turbolenze) che penalizzano la tecnica impedendole di imporsi come reale alternativa all'angiografia digitale arteriosa in tutti i casi.

É opinione unanime che per minimizzare questi limiti tecnici sia necessario restringere il campo di applicazione alle apparecchiature RM dotate di alto campo magnetico statico e sia necessario adottare la tecnica di acquisizione 3D TOF.

In questo lavoro abbiamo voluto presentare i risultati del confronto fra angio-RM e angiografia digitale arteriosa ricavati dalla nostra casistica e quelli relativi a tutti i casi pubblicati finora studiati con apparecchiature ad alto campo e tecnica 3D TOF (496 casi).

Nel nostro reparto abbiamo studiato complessivamente 39 aneurismi (di cui 6 giganti) in 30 pazienti confrontando le immagini angio-RM (tecnica 3D TOF, trasferimento della magnetizzazione e Flip Angle variabile) e di angiografia digitale arteriosa. Nel caso degli aneurismi giganti sono state acquisite in più sequenze 2D TOF e 3D TOF post-contrasto (Gd-DTPA).

La sovrapponibilità fra angio-RM e angiografia digitale arteriosa è risultata elevata per quanto riguarda l'individuazione della lesione, la sede e, in misura minore, l'orientamento del fondo e la stima dello spasmo associato eventualmente presente; invece la immagini RM sono risultate di minore ausilio diagnostico per la valutazione del colletto e dei rapporti con i vasi adiacenti.

I nostri risultati sono sostanzialmente confermati da quelli finora pubblicati in letteratura.

L'angiografia a risonanza magnetica, in virtù della sua elevata sensibilità, rappresenta un'importante tecnica di screening per gli aneurismi cerebrali essendo in grado di individuare anche lesioni molto piccole (fino a dimensioni di 2–3 mm).

Importanti limiti sono rappresentati tuttora dalla scarsa sovrapponibilità all'angiografia digitale arteriosa nella valutazione del colletto (a causa di caduta del segnale per flusso turbolento) e nella visualizzazione dei vasi adiacenti (per l'impossibilità con angio-RM di ottenere una progressiva opacizzazione dei vasi come invece avviene con angiografia digitale arteriosa).

Nonostante questi limiti in molti casi è possibile ottenere un'adeguata visualizzazione dell'aneurisma per cui l'angio-RM diventa un importante ausilio pre-chirurgico in quanto in grado di fornire numerose immagini della lesione su ogni piano dello spazio consentendo di valutare la lesione con la proiezione più idonea (anche assiale).

Per quanto riguarda gli aneurismi giganti (la cui valutazione con tecnica TOF è penalizzata dal lento flusso all'interno della sacca) abbiamo riscontrato che il maggior segnale è ottenibile con la sequenza 3D TOF con somministrazione di mezzo di contrasto paramagnetico.

Angio-CT

After nine months' experience with helical CT (Elscint Twin), we describe an epicrisis in 13 patients with intracranial aneurysms, 12 of whom were referred to us by the emergency room for suspect subarachnoid hemorrhage. After standard CT scan confirming subarachnoid hemorrhage, patients underwent angio-CT with display of the sac responsible for bleeding in all cases.

All patients subsequently underwent digital angiography which confirmed the angio-CT findings and in three cases disclosed associated malformations. The sensitivity, specificity and diagnostic accuracy of the technique are assessed in relation to the quality of the images obtained (MIP) in such a short time (15 min on average).

The diagnostic information is comparable to that offered by angio-MR with the obvious positive and negative aspects linked to each method.

Digital angiography remains the technique of choice in terms of diagnostic accuracy, but carries some risk to the patient.

Update on the management of subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) is a devastating cerebrovascular disease. Outcome after SAH is mainly determined by the initial severity of the hemorrhage. Neuroimaging, in particular computed tomography, and aneurysm repair techniques, such as coiling and clipping, as well as neurocritical care management, have improved during the last few years. The management of a patient with SAH should have an interdisciplinary approach with case discussions between the neurointensivist, interventionalist and the neurosurgeon. The patient should be treated in a specialized neurointensive care unit of a center with sufficient SAH case volume. Poor-grade patients can be observed for complications and delayed cerebral ischemia through continuous monitoring techniques in addition to transcranial Doppler ultrasonography such as continuous electroencephalography, brain tissue oxygenation, cerebral metabolism, cerebral blood flow and serial vascular imaging. Neurocritical care should focus on neuromonitoring for delayed cerebral ischemia, management of hydrocephalus, seizures and intracranial hypertension, as well as of medical complications such as hyperglycemia, fever and anemia.

State of the art in managing nontraumatic intracerebral hemorrhage

Nontraumatic intracerebral hemorrhage constitutes a major public health problem worldwide. Intracerebral hemorrhage leads to a high rate of morbidity and mortality. To date, no medical or surgical trials have clearly attested to the benefit of a particular therapy. The aim of this review was to summarize the best evidence for management decision-making in intracerebral hemorrhage.

Epidemiology of aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a form of hemorrhagic stroke that affects up to 30,000 individuals per year in the United States. The incidence of aSAH has been shown to be associated with numerous nonmodifiable (age, gender, ethnicity, family history, aneurysm location, size) and modifiable (hypertension, body mass index, tobacco and illicit drug use) risk factors. Although early repair of ruptured aneurysms and aggressive postoperative management has improved overall outcomes, it remains a devastating disease, with mortality approaching 50% and less than 60% of survivors returning to functional independence. As treatment modalities change and the percentage of minority and elderly populations increase, it is critical to maintain an up-to-date understanding of the epidemiology of SAH.

The role of contrast-enhanced MR angiography in the assessment of recently ruptured intracranial aneurysms: a comparative study

We evaluated contrast-enhanced MR angiography (MRA) for the identification of recently ruptured cerebral aneurysms. We studied 23 aneurysms in 18 patients (age range 34-72 years) with aneurysms of the anterior (n = 17) and posterior (n = 6) circulation by comparing 3D time-of-flight (TOF), contrast-enhanced MRA and digital subtraction angiography (DSA). In four of 23 aneurysms, 3D-TOF did not show the lesion. Contrast-enhanced MRA successfully depicted all aneurysms except one. T1 contamination artefacts from subarachnoid or intraparenchymal haemorrhages were evident on the 3D-TOF images in six cases. The artefacts were completely eliminated on the contrast-enhanced MRA images by subtraction of the pre-contrast images. The diagnostic information in patients with subarachnoid haemorrhages (SAHs) provided by contrast-enhanced MRA was comparable to that provided by DSA.

Computed Tomography and Magnetic Resonance Angiography in Cervicocranial Vascular Disease

Although catheter angiography, or digital subtraction angiography (DSA), is still regarded as the gold standard for imaging of cervicocranial vascular disease, its morbidity, cost, and time-consuming features have prompted the development of noninvasive techniques based on computed tomography (CT) and magnetic resonance imaging. With the advent of powerful software, CT and magnetic resonance angiography are complementing and, in some cases, even replacing DSA in the diagnostic evaluation of carotid atherostenosis, unruptured aneurysms, dissections, stroke, penetrating trauma to the neck, and dural venous sinus occlusive disease. They offer advantages over DSA not only in reduced morbidity and time-saving but also in assessment of brain parenchyma, quantitative perfusion, and abnormalities of vessel walls. In the evaluation of blunt neck injuries and intracranial vascular malformations, fistulas, and vasculitis, CT and magnetic resonance angiography still do not provide as much information as DSA.

Magnetic resonance angiography in the selection of patients suitable for neurosurgical intervention of ruptured intracranial aneurysms

This study was aimed at establishing whether magnetic resonance angiography (MRA) can be applied to planning and performing surgery on ruptured intracranial aneurysms, especially in the early phase, without recourse to intra-arterial digital subtraction angiography (IA-DSA). From February 1998 to August 2001, in all patients presenting with a subarachnoid hemorrhage, MRA was performed first. A three-dimensional time-of-flight MRA protocol with T2-weighted coronal and axial images was used. If MRA demonstrated an aneurysm, surgery was undertaken. IA-DSA was limited to patients with negative or inconclusive MRA findings. We compared MRA images with operative findings in positive patients and with IA-DSA in negatives. IA-DSA was considered the gold standard when MRA findings were inconclusive. In this study, 205 consecutive patients (mean age 52.7 years, 69% women) were included. In 133 patients (64.9%) MRA demonstrated an aneurysm, directly followed by neurosurgical intervention. In 33 patients (16.1%) MRA findings were categorized as inconclusive. In 39 patients (19.0%) MRA results were negative. No false-negative ruptured aneurysms were selected by MRA. In only one patient surgical intervention was performed based on false-positive MRA findings. MRA can replace IA-DSA as a first diagnostic modality in the selection of patients suitable for surgical treatment of ruptured intracranial aneurysms.

Subarachnoid hemorrhage

The medical and surgical management of aneurysmal SAH has changed dramatically in the past few decades. Surgical management emphasizes early triage and repair of the responsible aneurysm. Medical management focuses on maintenance of adequate volume, monitoring cerebral vasospasm, and initiation of medical maneuvers or interventional procedures designed to improve vessel patency and CBF. The results of these techniques have not been studied in randomized controlled trials; however, several large retrospective analyses reveal a significant decrease in mortality and morbidity with the institution of these measures. Future improvements will continue to develop with increased understanding of cerebral vasospasm and in neurologic monitoring.

Aneurysm and Subarachnoid Haemorrhage

Although CT angiography is more and more widely used as diagnostic tool in SAH, DSA remains a useful technique. Indeed DSA is mandatory in patients with SAH and negative angio-CT, and in all other doubtful cases. Angiography is also necessary in order to perform an endovascular treatment. Sometimes, after a SAH a first angiogram may be normal due to spasm, haematoma or in case of a real perimesencephalic haemorrhage. The need for a second angiogram is discussed. Finally some aspects concerning the aneurysmal growth and rupture are also discussed.

Diagnostic accuracy of magnetic resonance angiography for cerebral aneurysms in correlation with 3D-digital subtraction angiographic images: a study of 133 aneurysms

BACKGROUND AND PURPOSE

We investigated the sensitivity of 3D-time-of flight (3D-TOF) magnetic resonance angiography (MRA) in the detection of cerebral aneurysms with the use of 3D digital subtraction angiography as the gold standard. We also evaluated the effects of location and number of aneurysms (and experience of the reader) on the sensitivity.

METHODS

3D-TOF MRA was performed in 82 patients with 133 cerebral aneurysms. Each patient underwent rotational angiography. Three-dimensional reconstructed images were obtained from data of the rotational angiography (as the gold standard). A blind study with 4 readers of different experiences was performed to evaluate the diagnostic accuracy of 3D-TOF MRA for cerebral aneurysms.

RESULTS

One hundred five (79%) of all 133 aneurysms were detected with MRA by a neuroradiologist, 100 (75%) were detected by an experienced neurosurgeon, 84 (63%) were detected by a general radiologist, and 80 (60%) were detected by a resident neuroradiologist. For each reader, the detectability was lower for small aneurysms (<3 mm in maximum diameter) and/or for those located at the internal carotid artery and anterior cerebral artery. False-positive aneurysms were 29 for the neuroradiologist, 19 for the neurosurgeon, 31 for the general radiologist, and 30 for the resident neuroradiologist; most of the aneurysms were at the internal carotid artery. Causes of the false-positive and false-negative results included complex flow in a tortuous artery and susceptibility artifacts.

CONCLUSIONS

Although MRA is useful in the diagnosis of cerebral aneurysms, sufficient experience and careful attention are necessary for accurate diagnosis of aneurysms located at the internal carotid and anterior cerebral arteries.

Intracranial aneurysms: CT angiography and MR angiography for detection prospective blinded comparison in a large patient cohort

PURPOSE

To compare computed tomographic (CT) angiography and magnetic resonance (MR) angiography with intraarterial digital subtraction angiography (DSA) in the detection of intracranial aneurysms.

MATERIALS AND METHODS

One hundred forty-two patients underwent intraarterial DSA to detect aneurysms. CT angiography, three-dimensional time-of-flight MR angiography, and intraarterial DSA were performed contemporaneously. Film hard-copy images and maximum intensity projection reconstructions of the CT angiograms and MR angiograms were reviewed at different times.

RESULTS

The accuracy per patient for the best observer was 0.87 at CT angiography and 0.85 at MR angiography. The accuracy per aneurysm for the best observer was 0.73 at CT angiography and 0.67 at MR angiography. Differences between readers and modalities were not significant. Interobserver agreement was good: kappa value of 0.73 for CT angiography and of 0.74 for MR angiography. The sensitivity for detection of aneurysms smaller than 5 mm was 0.57 for CT angiography and 0.35 for MR angiography compared with 0.94 and 0.86, respectively, for detection of aneurysms 5 mm or larger. The accuracy of both CT angiography and MR angiography was lower for detection of internal carotid artery aneurysms compared with that at other sites. With low observer confidence, the likelihood of correct interpretation was significantly poorer.

CONCLUSION

CT angiography and MR angiography have limited sensitivity in the detection of small aneurysms but good interobserver agreement. There is no significant difference in diagnostic performance between the noninvasive modalities.

Intracranial aneurysms: clinical value of 3D digital subtraction angiography in the therapeutic decision and endovascular treatment

PURPOSE

To evaluate three-dimensional (3D) digital subtraction angiography (DSA) as a supplement to two-dimensional (2D) DSA in the endovascular treatment (EVT) of intracranial aneurysms.

MATERIALS AND METHODS

In 22 ruptured aneurysms, neck visualization, aneurysm shape, and EVT feasibility were analyzed at 2D DSA (anteroposterior, lateral, and rotational views) and at maximum intensity projection (MIP) and surface shaded display (SSD) 3D DSA. The possibility of obtaining a working view for EVT at 3D DSA and the relevance of measurements in choosing the first coil also were assessed.

RESULTS

Two-dimensional DSA images clearly depicted the aneurysm neck in four of 22 aneurysms; MIP images, in 10; and SSD images, in 21, but SSD led to overestimation of the neck size in one aneurysm. Aneurysm shape was precisely demonstrated in five of 22 aneurysms at 2D DSA, in eight at MIP, and in all cases at SSD. In two of 22 aneurysms, EVT seemed to be nonfeasible at 2D DSA; however, SSD demonstrated feasibility and EVT was successfully performed. In one aneurysm, only SSD demonstrated the extension of the neck to a parent vessel, which was proved at surgery. Working views for EVT were deduced from 3D DSA findings in 20 of 21 aneurysms. The choice of the first coil was correct in 19 of 21 aneurysms.

CONCLUSION

Three-dimensional DSA is valuable for evaluating the potential for EVT, finding a working view, and performing accurate measurements.

Subarachnoid haemorrhage: diagnosis, causes and management

The incidence of subarachnoid haemorrhage (SAH) is stable, at around six cases per 100 000 patient years. Any apparent decrease is attributable to a higher rate of CT scanning, by which other haemorrhagic conditions are excluded. Most patients are <60 years of age. Risk factors are the same as for stroke in general; genetic factors operate in only a minority. Case fatality is approximately 50% overall (including pre-hospital deaths) and one-third of survivors remain dependent. Sudden, explosive headache is a cardinal but non-specific feature in the diagnosis of SAH: in general practice, the cause is innocuous in nine out of 10 patients in whom this is the only symptom. CT scanning is mandatory in all, to be followed by (delayed) lumbar puncture if CT is negative. The cause of SAH is a ruptured aneurysm in 85% of cases, non-aneurysmal perimesencephalic haemorrhage (with excellent prognosis) in 10%, and a variety of rare conditions in 5%. Catheter angiography for detecting aneurysms is gradually being replaced by CT angiography. A poor clinical condition on admission may be caused by a remediable complication of the initial bleed or a recurrent haemorrhage in the form of intracranial haematoma, acute hydrocephalus or global brain ischaemia. Occlusion of the aneurysm effectively prevents rebleeding, but there is a dearth of controlled trials assessing the relative benefits of early operation (within 3 days) versus late operation (day 10-12), or that of endovascular treatment versus any operation. Antifibrinolytic drugs reduce the risk of rebleeding, but do not improve overall outcome. Measures of proven value in decreasing the risk of delayed cerebral ischaemia are a liberal supply of fluids, avoidance of antihypertensive drugs and administration of nimodipine. Once ischaemia has occurred, treatment regimens such as a combination of induced hypertension and hypervolaemia, or transluminal angioplasty, are plausible, but of unproven benefit.

Can noninvasive imaging accurately depict intracranial aneurysms? A systematic review

PURPOSE

To perform a systematic review to determine the accuracy of computed tomographic (CT) angiography, magnetic resonance (MR) angiography, and transcranial Doppler ultrasonography (US) in depicting intracranial aneurysms.

MATERIALS AND METHODS

A 1988-1998 literature search for studies with 10 or more subjects in which noninvasive imaging was compared with angiography was undertaken. Studies meeting initial criteria were evaluated by using intrinsically weighted standardized assessment to determine suitability for inclusion. Studies scoring greater than 50% were included.

RESULTS

Of 103 studies that met initial criteria, 38 scored greater than 50%. CT angiography and MR angiography had accuracies per aneurysm of 89% (95% CI: 87%, 91%) and 90% (95% CI: 87%, 92%), respectively. For US, data were scanty and accuracy was lower, although the CIs overlapped those of CT angiography and MR angiography. Sensitivity was greater for detection of aneurysms larger than 3 mm than for detection of aneurysms 3 mm or smaller-for CT angiography, 96% (95% CI: 94%, 98%) versus 61% (95% CI: 51%, 70%), and for MR angiography, 94% (95% CI: 90%, 97%) versus 38% (95% CI: 25%, 53%). Diagnostic accuracy was similar for anterior and posterior circulation aneurysms.

CONCLUSION

CT angiography and MR angiography depicted aneurysms with an accuracy of about 90%. Most studies were performed in populations with high aneurysm prevalence, which may have introduced bias toward noninvasive examinations.

Aneurysm detection with computed tomographic angiography in a 1-month-old infant

We report an infant whose clinical condition deteriorated acutely at 1 month of age because of a subarachnoid hemorrhage with an intracerebellar hematoma. Computed tomographic angiography revealed an aneurysm of the left posterior inferior cerebellar artery. Because of the critical condition of the child and her very young age, the decision to perform surgery was based solely on the computed tomographic angiography findings.

Free-breathing 3D coronary MRA: the impact of "isotropic" image resolution

During conventional x-ray coronary angiography, multiple projections of the coronary arteries are acquired to define coronary anatomy precisely. Due to time constraints, coronary magnetic resonance angiography (MRA) usually provides only one or two views of the major coronary vessels. A coronary MRA approach that allowed for reconstruction of arbitrary isotropic orientations might therefore be desirable. The purpose of the study was to develop a three-dimensional (3D) coronary MRA technique with isotropic image resolution in a relatively short scanning time that allows for reconstruction of arbitrary views of the coronary arteries without constraints given by anisotropic voxel size. Eight healthy adult subjects were examined using a real-time navigator-gated and corrected free-breathing interleaved echoplanar (TFE-EPI) 3D-MRA sequence. Two 3D datasets were acquired for the left and right coronary systems in each subject, one with anisotropic (1.0 x 1.5 x 3.0 mm, 10 slices) and one with "near" isotropic (1.0 x 1.5 x 1.0 mm, 30 slices) image resolution. All other imaging parameters were maintained. In all cases, the entire left main (LM) and extensive portions of the left anterior descending (LAD) and the right coronary artery (RCA) were visualized. Objective assessment of coronary vessel sharpness was similar (41% +/- 5% vs. 42% +/- 5%; P = NS) between in-plane and through-plane views with "isotropic" voxel size but differed (32% +/- 7% vs. 23% +/- 4%; P < 0.001) with nonisotropic voxel size. In reconstructed views oriented in the through-plane direction, the vessel border was 86% more defined (P < 0.01) for isotropic compared with anisotropic images. A smaller (30%; P < 0.001) improvement was seen for in-plane reconstructions. Vessel diameter measurements were view independent (2.81 +/- 0.45 mm vs. 2.66 +/- 0.52 mm; P = NS) for isotropic, but differed (2.71 +/- 0.51 mm vs. 3.30 +/- 0.38 mm; P < 0.001) between anisotropic views. Average scanning time was 2:31 +/- 0:57 minutes for anisotropic and 7:11 +/- 3:02 minutes for isotropic image resolution (P < 0.001). We present a new approach for "near" isotropic 3D coronary artery imaging, which allows for reconstruction of arbitrary views of the coronary arteries. The good delineation of the coronary arteries in all views suggests that isotropic 3D coronary MRA might be a preferred technique for the assessment of coronary disease, although at the expense of prolonged scan times. Comparative studies with conventional x-ray angiography are needed to investigate the clinical utility of the isotropic strategy.

Computerized tomography angiography in patients with subarachnoid hemorrhage: from aneurysm detection to treatment without conventional angiography

OBJECT

The purpose of this study was to determine prospectively whether and to what extent computerized tomography (CT) angiography can serve as the sole imaging method for a preoperative workup in patients with ruptured intracranial aneurysms.

METHODS

During a 1-year period, all patients who presented to the authors' hospital with subarachnoid hemorrhage demonstrated by unenhanced CT scanning or lumbar puncture underwent CT angiography. Two radiologists evaluated the CT angiography source images and maximum intensity projection slabs and arrived at a consensus. They categorized the quality of the CT angiography as adequate or inadequate and classified aneurysms that were detected as definitely or possibly present. The parent artery of anterior communicating artery aneurysms was identified by asymmetrical anterior cerebral artery size and asymmetrical aneurysm location. The parent artery was indicated by the larger A1 segment in cases of asymmetrical A1 size. Only CT angiograms of adequate quality that revealed aneurysms classified as definitely present and with an unequivocal parent artery were presented to the neurosurgeons, who decided whether preoperative digital subtraction (DS) angiography should still be performed. Forty-nine of the 100 studied patients did not undergo surgery because of poor clinical condition, nonaneurysmal cause of the hemorrhage, or endovascular treatment of the ruptured aneurysm. Of the 51 patients who underwent surgery, radiologists required DS angiography in 17 patients; the imaging technique provided greater certainty in 13 instances. The neurosurgeons required DS angiography 11 times; this provided additional information in two instances. Twenty-three (45%) of the 51 patients were surgically treated successfully on the basis of CT angiography findings alone.

CONCLUSIONS

Computerized tomography angiography can replace DS angiography as the preoperative neuroimaging technique in a substantial proportion of patients with ruptured intracranial aneurysms.

Perimesencephalic hemorrhage. Exclusion of vertebrobasilar aneurysms with CT angiography

BACKGROUND AND PURPOSE

It is important to recognize a perimesencephalic pattern of hemorrhage in patients with subarachnoid hemorrhage (SAH), because in 95% of these patients the cause is nonaneurysmal and the prognosis is excellent. The purpose of this study was to investigate whether CT angiography can accurately exclude vertebrobasilar aneurysms in patients with perimesencephalic patterns of hemorrhage and therefore replace digital subtraction angiography (DSA) in this setting.

METHODS

In 40 patients with posterior fossa SAH as shown on unenhanced CT, 2 radiologists independently evaluated unenhanced CT for distinguishing between perimesencephalic and nonperimesencephalic pattern of hemorrhage and assessed CT angiography for detection of aneurysms. All patients subsequently underwent DSA or autopsy.

RESULTS

Observers agreed in 38 of 40 patients (95%) in differentiating perimesencephalic and nonperimesencephalic patterns of hemorrhage on unenhanced CT. On the CT angiograms, both observers detected a vertebrobasilar aneurysm in 16 patients and no aneurysm in 24 patients. These findings were confirmed by DSA or autopsy. No patients with a perimesencephalic pattern of hemorrhage were found to have an aneurysm on either CT angiography or DSA.

CONCLUSIONS

Good recognition of a perimesencephalic pattern of hemorrhage is possible on unenhanced CT, and CT angiography accurately excludes and detects vertebrobasilar aneurysms. DSA can be withheld in patients with a perimesencephalic pattern of hemorrhage and negative CT angiography.

The usefulness of magnetic resonance angiography in surgery for intracranial aneurysms that have bled

BACKGROUND

Once it was confirmed that magnetic resonance imaging (MRI) including angiography (MRA) could demonstrate intracranial aneurysms, a study was set up to establish whether satisfactory images could be obtained to plan and execute early surgery on ruptured intracranial aneurysms without recourse to intra-arterial digital subtraction angiography (IA.DSA) in the acute phase of the illness.

METHODS

All patients presenting with a subarachnoid haemorrhage (SAH) were considered for MR studies. The patient selection was based on whether they were considered fit enough to tolerate scanning and did not have a known contraindication. A standard protocol was used--a three-dimensional time-of-flight with T1 and T2-weighted sagittal and axial images. If an aneurysm was demonstrated and early surgery was undertaken they were entered into the study.

RESULTS

Over a 25-month period, 122 patients were submitted for MR studies, these being selected from over 200 patients presenting with an SAH. Aneurysms were believed to be present in 55 patients who were clinically suitable for early surgery. There were 21 males and 34 females, with an age range of 23-79 years, a mean of 50.5 years. Sixty-three aneurysms in all were demonstrated and 55 of these were surgically dealt with. There were two false positives.

CONCLUSION

MRI is the investigation of choice to plan surgery in those patients presenting with an SAH who, on clinical grounds, would be considered suitable for early surgery. The imaging is easily obtained, non-invasive, avoids radiation, and in view of the multiple images obtained is often superior to conventional DSA.

Spontaneous intracranial hemorrhage: which patients need diagnostic cerebral angiography? A prospective study of 206 cases and review of the literature

BACKGROUND AND PURPOSE

In spontaneous intracerebral hemorrhage (ICH), the site, age of the patients, and preexisting hypertension are important factors in determining the possibility of finding an underlying vascular abnormality by cerebral angiography. To what extent these three factors affect the indication for angiography remains controversial. A prospective study was carried out to correlate the angiographic findings with these three factors.

METHODS

Two hundred six consecutive spontaneous ICH cases with an age range from 5 to 79 years (median, 45) were investigated with CT and cerebral angiography over a 3-year period (April 1993 through March 1996). Exclusion criteria were (1) poor surgical risk or severely neurologically disabled patients, (2) refusal of angiography, (3) patients in whom severe coagulopathy accounted for the hemorrhage, (4) bleeding into tumor, or (5) subarachnoid hemorrhage-predominant cases.

RESULTS

Angiographic yield (the frequency of positive angiography in a defined patient group) was significantly higher in patients (1) at or below the median age of 45 than those above (53/105, 50%, versus 18/101, 18%; P < .001) and (2) without preexisting hypertension than those with (64/145, 44%, versus 5/58, 9%; P < .001). The correlation of age and preexisting hypertension to angiographic yield was independent (logistic regression coefficients -0.056 and -1.59 and SE 0.12 and 0.515, respectively, both P < .001). In patients of the younger age group without preexisting hypertension, angiographic yield was 48% in putaminal, thalamic, or posterior fossa ICH and 65% in lobar ICH. In the older hypertensive patients, the yields were 0% and 10%, respectively. However, in patients with isolated intraventricular hemorrhage, most were normotensive and the yield was high in both age groups (67% versus 63%).

CONCLUSION

Diagnostic cerebral angiography should be considered for all spontaneous ICH patients except those over 45 years old with preexisting hypertension in thalamic, putaminal, or posterior fossa hemorrhage.