Experience with computed tomographic angiography for the detection of intracranial aneurysms in the setting of acute subarachnoid hemorrhage

OBJECTIVE: To objectively compare computed tomographic angiography (CTA) with selective digital subtraction angiography (DSA) in the detection and anatomic definition of intracranial aneurysms, particularly in the setting of acute subarachnoid hemorrhage (SAH). METHODS: In a blinded prospective study, 40 patients with known or suspected intracranial saccular aneurysms underwent both CTA and DSA, including 32 consecutive patients with SAH in whom CTA was performed after CT images were obtained diagnostic for SAH. The CT angiograms were interpreted for presence, location, and size of the aneurysms, and anatomic features, such as the number of aneurysms lobes, aneurysm neck size (< or = 4 mm), and the number of adjacent arterial branches were suggested. The images obtained with CTA were then compared with the images obtained with DSA, with the later images serving as controls. RESULTS: DSA revealed 43 aneurysms in 30 patients and ruled out intracranial aneurysms in the remaining 10 patients. For aneurysm presence alone, the sensitivity and specificity for CTA was 86 and 90%, respectively. For the presence of an aneurysms, six CT angiogram showed false negative results and one CT angiogram showed a false positive result. False negative results were usually caused by technical problems with the image, tiny aneurysm domes (< 3 mm), and unusual aneurysm locations (i.e., intracavernous carotid or posterior inferior cerebellar artery aneurysms). The results obtained with CTA were, compared with the results obtained with DSA, more than 95% accurate in determining dome and neck size of aneurysm, aneurysm lobularity, and the presence and number of adjacent arterial branches. In addition, CTA provided a three-dimensional representation of the aneurysmal lesion, which was considered useful for surgical planning. CONCLUSION: CTA is useful for rapid and relatively noninvasive detection of aneurysms in common locations, and the anatomic information provided in images showing positive results is at least equivalent to that provided by DSA. In cases of SAH in which the nonaugmented CT and CTA results indicate a clear source of bleeding and provide adequate anatomic detail, we think it is possible to forego DSA before urgent early aneurysm surgery. In all other cases, DSA is indicated.     

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.     

Long-term follow-up study of unruptured intracranial aneurysms

OBJECTIVE: The purpose of this study was to clarify the risk of rupture of unruptured intracranial aneurysms among large groups of patients with various underlying diseases or conditions. METHODS: A long-term follow-up study of unruptured intracranial aneurysms was performed with 360 patients who were treated conservatively during the period from April 1969 to December 1992. RESULTS: Follow-up evaluation (between February and June 1994) could be performed for 234 (65%) of the patients. The underlying diseases included multiple aneurysms with subarachnoid hemorrhage for 60 patients, cerebral infarction for 108, intracerebral hemorrhage for 27, and other diseases for 39. Single aneurysms were present in 171 patients and multiple aneurysms in 63. The mean follow-up period was 75 months (range, 3-270 mo). Of the 234 patients, 132 (56.4%) survived, 59 (25.2%) died because of other diseases, 9 (3.8%) underwent surgery, and 34 (14.5%) showed bleeding from unruptured aneurysms, which was fatal for 18 of the patients. The average annual rupture rate for all patients was 2.3% (subarachnoid hemorrhage, 3.2%; cerebral infarction, 2.2%; intracerebral hemorrhage, 3.2%; other diseases, 3.6%). There were no significant differences among the patients according to underlying disease or aneurysm site. The cumulative rate of bleeding for all patients was 20% at 10 years after diagnosis and 35% at 15 years. The cumulative probability of rupture was significantly higher for the multiple aneurysms than the single aneurysms (P < 0.001). CONCLUSION: The risk of rupture of unruptured aneurysms is high, especially for multiple aneurysms, but there are no significant differences in the risk of rupture according to the underlying disease or the aneurysm location. Radical treatment should be considered for patients with unruptured intracranial aneurysms.     

Surgical management of unruptured asymptomatic aneurysms

The natural history of unruptured asymptomatic aneurysms in nuclear. Because of this uncertainty regarding risk of ultimate enlargement and/or hemorrhage, and in view of the significant mortality and morbidity traditionally involved in aneurysm surgery, clinicans have varied in their advocacy of surgical management of such lesions. Forty-nine consecutive patients harboring 52 such aneurysms were treated surgically over a 57-month period. There were no surgical deaths and morbidity was within acceptable limits. Patient population characteristic and surgical technique are discussed.     

Comparison of magnetic resonance volume flow rates, angiography, and carotid Dopplers. Preliminary results

BACKGROUND AND PURPOSE: We compared the results of conventional angiography, carotid Doppler, and magnetic resonance angiography volume flow rates to determine the clinical utility of volume flow rate assessment of blood flow to the anterior circulation in patients with carotid occlusive disease. METHODS: From 11 symptomatic patients, a total of 22 extracranial carotid arteries were studied with all three techniques. The studies were independently read, and regression analysis was used to compare the measurements. RESULTS: Carotid Doppler measurements of the distal extracranial carotid arteries were proportional to the inverse of the extracranial carotid volume flow rate (r = .53, R2 = 29%, P < .01), volume flow rates were proportional to the inverse of measured percent stenosis on angiography (r = .84, R2 = 71%, P < .01), and Dopplers were proportional to angiography (r = .94, R2 = 90%, P < .01). Symptomatic Doppler systolic velocity was significantly higher (P < .002), symptomatic measured stenosis was significantly higher (P < .002), and symptomatic volume flow rate was significantly lower (P < .01) than their respective asymptomatic-side values. These preliminary observations, however, may well change once a large data set, especially one in which more patients with high-grade carotid stenosis are included, is studied. CONCLUSIONS: Assessment of carotid volume flow rates by magnetic resonance angiography quantifies flow reduction secondary to atherosclerotic occlusive disease. The easily obtained flow data add both documentation of arterial flow characteristics related to internal carotid stenosis and information regarding the adequacy of collateral pathways.     

Repeat angiography and magnetic resonance imaging (MRI) of dissecting aneurysms of the intracranial vertebral artery. Report of four cases

We here present 4 cases with dissecting aneurysm (DA) of the intracranial vertebral artery, who were followed up by repeat cerebral angiography and MRI. The patients consisted of 2 males and 2 females, and the mean age was 43 years. Two cases were associated with polyarteritis nodosa (PN) and hypertension, respectively. Three of the cases developed subarachnoid haemorrhage (SAH), while the other one suffered from lateral medullary syndrome. In cerebral angiography, "pearl and string" signs were revealed in all cases, while a "double lumen" indicating a true diagnostic sign of DA was demonstrated in only one case. Repeat angiography showed that a bleb formation with a bulging of the aneurysmal sac was seen in 2 cases, and an irregularity of the wall in one case. On the other hand in one case, the ectatic part shrank, while the stenotic part was restored. In magnetic resonance imaging (MRI), a hyperintensity mass on T 1-weighted image (T 1-WI) adjacent to flow void suggesting either an intramural haematoma or a linear shape hyperintensity on T 1-WI were demonstrated in 3 cases. In the follow up MRI done in 2 cases, a serial change in the intensity from iso-intensity to hyperintensity on T 1-WI was observed in one case suggesting intramural haemorrhage, while an enlargement of the ectasic flow void was seen in the other case. Three of 4 cases were operated on by trapping of the aneurysms. One, who had systemic vascular diseases due to PN, and repeat angiography showed a regression of the aneurysm, was conservatively treated.(ABSTRACT TRUNCATED AT 250 WORDS)     

The role of magnetic resonance angiography in the assessment of intracranial vascular disease

Magnetic resonance techniques have a significant role in the evaluation of intracranial vascular diseases; however, to achieve an appropriate diagnosis, a combination of both magnetic resonance imaging and angiography are needed. It is extremely important for the interpreting physician to be aware of the potential limitations of the techniques being used. With this knowledge, magnetic resonance techniques can eliminate the need for more invasive procedures. An overview of the current methods and their applications and limitations is provided.     

Functional stereotaxy with magnetic resonance tomographic guidance

The paper summarizes experience with stereotactic operations by magnetic resonance imaging data by using a Russian OREOL stereotactic manipulator. It describes methods of preoperative preparation of patients by employing diagnostic magnetic resonance tomographs. A number of points of the procedure for identification and localization of deep target structures from magnetic resonance images in parkinsonism, temporal epilepsy and some mental disorders.     

A ten percent prevalence of asymptomatic familial intracranial aneurysms: preliminary report on 110 magnetic resonance angiography studies in members of 21 Finnish familial intracranial aneurysm families

The population in eastern Finland has been stable for generations, causing a high degree of genetic isolation and providing excellent possibilities for follow-up studies. Of 91 families with familial intracranial aneurysms, 21 were randomly selected for prospective magnetic resonance angiography studies for intracranial aneurysms. Sixteen intracranial aneurysms were detected in 11 asymptomatic family members of a total of 110 studied. The prevalence of intracranial aneurysms among these familial intracranial aneurysm families is 10%, approximately 10 times higher than in the average population. Our findings suggest that family members of familial intracranial aneurysm families should be examined for intracranial aneurysms. Familial intracranial aneurysm may be a genetic disorder.     

Mortality and morbidity of surgery for unruptured intracranial aneurysms: a meta-analysis

BACKGROUND AND PURPOSE: Greater availability and improvement of neuroradiological techniques have resulted in more frequent detection of unruptured aneurysms. Because prognosis of subarachnoid hemorrhage is still poor, preventive surgery is increasingly considered as a therapeutic option. Elective surgery requires reliable data on its risks. Therefore, we performed a meta-analysis on the mortality and morbidity of surgery for unruptured intracranial aneurysms. METHODS: Through Medline and additional searches by hand, we retrieved studies on clipping of unruptured (additional, symptomatic, or incidental) aneurysms published from 1966 through June 1996. Two authors independently extracted data. We used weighted linear regression for data analysis. RESULTS: We included 61 studies that involved 2460 patients (57% female; mean age, 50 years) and at least 2568 unruptured aneurysms (27% >25 mm, 30% located in the posterior circulation). Mortality was 2.6% (95% confidence interval [CI], 2.0% to 3.3%). Permanent morbidity occurred in 10.9% (95% CI, 9.6% to 12.2%) of patients. Postoperative mortality was significantly lower in more recent years for nongiant aneurysms and aneurysms with an anterior location; the last 2 characteristics were also associated with a significantly lower morbidity. CONCLUSIONS: In studies published between 1966 and 1996 on clipping of unruptured aneurysms, mortality was 2.6% and morbidity was 10.9%. In calculating the pros and cons of preventive surgery, these proportions should be taken into account.     

Haemoptysis associated with pulmonary varices: demonstration using computed tomographic angiography

A 67 yr old female with mitral stenosis presented with an acute haemoptysis caused by the rupture of pulmonary varices. Chest radiography and bronchoscopy showed nonspecific abnormalities. The diagnosis of this rare but potentially lethal complication was made using computed tomographic angiography with three-dimensional volume rendering.     

The clinical aspect of the joint use of magnetic resonance tomography of the brain and magnetic resonance angiography of the extra- and intracranial arteries in patients with arterial hypertension

NMR tomography (NMRT) of the brain and NMR angiography (NMRA) of the extra- and intracranial arteries were performed on the unit Magnetom 63 SP (1.5 T) Siemens in 13 healthy controls and 87 patients with cerebrovascular diseases initiated by arterial hypertension and atherosclerosis of major cerebral arteries. NMRA image of arterial impairment comprise curved extracranial arteries. NMRT picture of the brain was changed (extension of liquor spaces, small hyperintensive foci in the white matter) in mild and moderate hypertension. Frequency of these phenomena and their severity increase with growing severity of the disease reaching maximum in malignant hypertension. In atherosclerosis of the major cerebral arteries NMRT often detected strokes, for the most part ischemic. A direct relationship between the degree of arterial stenosis and incidence of the strokes was not found.     

Principles of magnetic resonance angiography

A strongly fluorescing 7-hydroxycoumarin (umbelliferone, U) oxidized in dilute (10 mumol/L-O, 1 mol/L) aqueous solution with CIO- or CIO- + H2O2 (but not with H2O2 alone) produces a strong chemiluminescence (CL). Light emission kinetics depends on the pH of solution (4.0-10.5) and the reaction has a low activation energy Ea = 31 +/- 2 kJ/mol (285-310 K). The spectrum covers the fluorescence of umbelliferone (400-550 nm, lambda max 460 nm). No red emission typical of 1 delta g, 1 sigma g, 1 sigma+g (O2)2 is observed either in the umbelliferone+CIO- or the umbelliferone +CIO- + H2O2 solution. The possible mechanism of CL and concomitant degradative oxidation of umbelliferone is discussed.     

Diagnosis of pulmonary embolism with magnetic resonance angiography

BACKGROUND: Diagnosing pulmonary embolism may be difficult, because there is no reliable noninvasive imaging method. We compared a new noninvasive method, gadolinium-enhanced pulmonary magnetic resonance angiography, with standard pulmonary angiography for diagnosing pulmonary embolism. METHODS: A total of 30 consecutive patients with suspected pulmonary embolism underwent both standard pulmonary angiography and magnetic resonance angiography during the pulmonary arterial phase at the time of an intravenous bolus of gadolinium. All magnetic resonance images were reviewed for the presence or absence of pulmonary emboli by three independent reviewers who were unaware of the findings on standard angiograms. RESULTS: Pulmonary embolism was detected by standard pulmonary angiography in 8 of the 30 patients in whom pulmonary embolism was suspected. All 5 lobar emboli and 16 of 17 segmental emboli identified on standard angiograms were also identified on magnetic resonance images. Two of the three reviewers reported one false positive magnetic resonance angiogram each. As compared with standard pulmonary angiography, the three sets of readings had sensitivities of 100, 87, and 75 percent and specificities of 95, 100, and 95 percent, respectively. The interobserver correlation was good (k=0.57 to 0.83 for all vessels, 0.49 to 1.0 for main and lobar vessels, and 0.40 to 0.81 for segmental vessels). CONCLUSIONS: In this preliminary study, gadolinium-enhanced magnetic resonance angiography of the pulmonary arteries, as compared with conventional pulmonary angiography, had high sensitivity and specificity for the diagnosis of pulmonary embolism. This new technique shows promise as a noninvasive method of diagnosing pulmonary embolism without the need for ionizing radiation or iodinated contrast material.     

A comparison of magnetic resonance and computed tomographic image quality after the implantation of tantalum and titanium spinal instrumentation

STUDY DESIGN: Tantalum- and titanium-based lumbar interbody fusion devices were implanted into two fresh human cadavers, and magnetic resonance and computed tomographic imaging were performed to evaluate adjacent spinal structures and the amount of metallic artifact. OBJECTIVE: The objective of this study was to prospectively compare the preliminary results of magnetic resonance imaging and computed tomography scanning image quality after the implantation of both titanium and tantalum spinal implants. SUMMARY OF BACKGROUND DATA: The availability of tantalum and titanium spinal implants brings theoretical magnetic resonance imaging compatibility along with several other desirable characteristics. The magnetic resonance imaging and computed tomographic imaging of tantalum spinal instrumentation has never been studied previously or compared with titanium instrumentation. METHODS: Titanium and tantalum spinal implants produced for anterior spinal fusion were each placed at two levels in the lumbar spine of two fresh cadaver specimens. Sequential spin echo T1-weighted and T2-weighted magnetic resonance imaging studies and computed tomographic scans were obtained. The resulting images were then graded to describe and compare the behavior of tantalum metal in magnetic resonance imaging and computed tomographic studies. RESULTS: Good T1 and T2 images were obtained that allowed visualization of the neural structures with minimal artifact. The optimal T1 images for tantalum metal were similar in quality to the optimal T1 parameters for titanium metal. T2 images for both tantalum and titanium metal were obtained with similar results for both metals. Gradient echo magnetic resonance imaging scans of both were poorly imaged with a large amount of artifact. Computed tomographic studies of tantalum implants produced a large amount of metal artifact when compared with computed tomographic studies of titanium implants. CONCLUSIONS: High-quality magnetic resonance imaging studies can be obtained after the implantation of both titanium and tantalum spinal instrumentation. Both of the metals produce similar images on magnetic resonance imaging studies with comparable amounts of metallic artifact. High-quality computed tomographic scans of titanium implants can be obtained with minimal distortion secondary to artifact. However, computed tomographic scanning is not the imaging modality of choice for the tantalum spinal implants because of the large amounts of artifact.     

Spiral CT angiography and surgical correlations in the evaluation of intracranial aneurysms

We investigated the accuracy of spiral computed tomography angiography (CTA) in the detection and study of intracranial aneurysms by comparing CTA with selective angiograms and surgical findings. Twenty-six patients (9 men and 17 women; mean age 53.1 +/- 1.8 years) with suspected intracranial aneurysms were submitted to CTA (1- to 2-mm slices, pitch 1:1, 24 s, RI = 1) after a conventional CT examination showing subarachnoid hemorrhage (SAH) in 19 cases and during neuroradiological investigations performed for other reasons in 7 cases. One hundred twenty to 150 ml iodate contrast agent (0.3-0.4 gI/ml) were injected intravenously at 5 ml/s rate and with 12- to 25-s delay calculated with a preliminary test bolus. Three-dimensional shaded surface display (3D SSD) and maximum intensity projection (MIP) reconstructions were obtained from axial images. Then, within 48 h, all patients were submitted to digital subtraction angiography (DSA), with separate assessment of CTA and DSA findings. Twenty-two aneurysms shown by CTA were confirmed at DSA and surgery (true positives), whereas the vascular lesion was not confirmed at DSA in 2 cases (false positives). The presence of intracranial aneurysms was excluded at both CTA and subsequent DSA in 7 cases (true negatives) and there were no false negatives; sensitivity was 100 %, specificity 77.8 %, and diagnostic accuracy 93.5 %. Computed tomography angiography aneurysm location was confirmed at surgery in all cases, with very high accuracy in assessing the presence of an aneurysm neck (100 %). Computed tomography angiography accurately depicted the aneurysm shape in 20 of 22 cases, but failed to depict its multilobed nature in 2 cases. The mean aneurysm diameter calculated at CTA was 0.99 +/- 0.12 cm vs 1.09 +/- 0.11 cm at surgery (p < 0.01). The present results suggest that the high sensitivity of CTA, if confirmed by further studies, might help in avoiding having to resort to arteriography after negative CTA in SAH patients.     

Benign hyperplasia of ectopic prostatic tissue. The computed tomographic and magnetic resonance findings in a patient with 2 locations

An open randomized controlled clinical trial was conducted to compare the reactogenicity of a recombinant hepatitis B vaccine (Engerix-B) when injected with the Bioject device (a pneumatically powered drug delivery system using disposable syringes) or with conventional syringe and needle, according to a 0.1 and 6 month vaccination schedule. Ninety-seven healthy young adults were enrolled in this study. Participants were asked to record local and general solicited symptoms and signs after each vaccination and to report each unsolicited symptom and sign that occurred during the study. The use of the jet-gun induced a statistically significant higher incidence of local symptoms and signs (solicited and unsolicited) than the use of syringe and needle.     

Cerebrovascular applications of magnetic resonance angiography

Magnetic resonance angiography (MRA) has been applied to a variety of different manifestations of cerebrovascular disease to date. Practically, the limitations of these techniques must be taken into account such that the appropriate method is applied to answer a specific clinical question and the acquisition parameters are chosen to maximise the sensitivity and specificity of the study. Based upon these results, it must be decided whether the conventional parenchymal MR and MRA evaluations are sufficient in a particular setting or whether it is necessary to commit the patient to a more traditional, invasive angiographic study for a more thorough investigation. Presently, MR angiographic studies and flow measurement techniques serve to compliment the more traditional spin-echo evaluation of patients with small aneurysms, arterial and venous occlusions, vascular malformations and in some cases of neoplastic vascular invasion. With well-trained technicians and carefully prescribed protocols, this new information and improved diagnostic sensitivity can be used routinely with only a minor increase in patient exam time.