Clinical utility of multislice computed tomographic angiography for detection of cerebral vasospasm in acute subarachnoid hemorrhage.

Digital subtraction angiography (DSA) has been used as the standard method for detecting cerebral vasospasm after subarachnoid hemorrhage (SAH). Multislice computed tomographic angiography (CTA) is a relatively recent method used for evaluating the vasculature of the intracranial arteries. The purpose of this study was to compare multislice CTA and DSA for the detection and quantification of cerebral vasospasm after SAH, and to analyze the usefulness of multislice CTA. Eight patients with SAH underwent initial CTA with DSA within 72 hours after the onset of symptoms and follow-up multislice CTA and DSA 8 to 48 days after SAH. Five arterial locations were established in the A1 and A2 segments of the anterior cerebral artery, the M1 and M2 segments of the middle cerebral artery and the posterior cerebral artery (PCA) on both multislice CTA and DSA images. Vasospasm was classified as none, mild (up to 30% reduction in luminal diameter), moderate (31-60% reduction), and marked (at least 60% reduction) using the scale of Schneck and Kricheff. The multislice CT system used the following parameters: 1.25 mm collimation and 3.75 pitch with a 4-channel system. The degree of vasospasm revealed by the multislice CTA was significantly correlated with the degree of vasospasm revealed by DSA. In general, most discrepancies between CTA and DSA were in the detection of mild and moderate vasospasm. We found that the consistency between multislice CTA and DSA was greater for mild (100%, n=3) or moderate (100%, n=3) vasospasm than none (n=1) or marked vasospasm (n=1). However, it was unclear whether multislice CTA was more specific for a proximal location (A1, M1, PCA) or distal location (A2, M2) for evaluation of cerebral arteries. Multislice CTA can detect angiographic vasospasm after SAH with an accuracy similar to that of DSA. Multislice CTA is highly sensitive, specific and accurate in detecting mild and moderate cerebral vasospasm. It is less accurate for detecting no vasospasm and marked vasospasm. Therefore, the authors propose that multislice CTA be considered as a useful tool for the detection and management of intracranial vasospasm after SAH.     

Detection of intracranial aneurysms with two-dimensional and three-dimensional multislice helical computed tomographic angiography

OBJECTIVE: Computed tomographic angiography (CTA) has become a diagnostic method for the detection of intracranial aneurysms in cases of subarachnoid bleeding. We sought to evaluate the detection of aneurysms with CTA with a novel multislice helical computed tomographic scanner. METHODS: Prospectively, 179 patients underwent multislice CTA, followed by digital subtraction angiography (DSA) of both carotid arteries with or without the posterior circulation, DSA of one carotid artery with or without the posterior circulation, or DSA of the posterior circulation alone. The total number of carotid arteries studied was 298, and the number of vertebrobasilar arteries studied was 124. RESULTS: Of 178 aneurysms verified with DSA or intraoperatively, CTA failed to detect 7 aneurysms of 1 to 2 mm and 1 partially thrombosed, 4-mm aneurysm. The sensitivity and specificity of CTA for aneurysm detection were 0.96 and 0.97, respectively. CONCLUSION: The first generation of multislice computed tomographic technology does not improve CTA to surpass DSA for the detection of small aneurysms of 1 to 2 mm. In practice, however, CTA is superior as a fast noninvasive method without complications.     

Computed tomography angiography for quantification of cerebral vasospasm following aneurysmal subarachnoid hemorrhage

PurposeThe purpose of this study was to assess the accuracy of computed tomography angiography (CTA) for quantification of cerebral vasospasm following aneurysmal subarachnoid hemorrhage in proximal and middle segments of intracranial arteries.Materials and methodsTwenty consecutive patients (7 men, 13 women; mean age, 47 ± 7 [SD] years; age range: 27–78 years) with aneurysmal subarachnoid hemorrhage who underwent CTA and digital subtracted angiography (DSA) with a 6-hour window at baseline and during vasospasm period were included. Twelve artery segments were analyzed in each patient. Vasospasm was blindly quantified on CTA and digital subtracted angiography (DSA) by two independent readers with discordance > 10% resolved by open data consensus. Inter-reader and inter-test correlations with DSA as reference, and causes of discordant readings were analyzed. The best sensitivity and specificity of CTA for determination of vasospasm ≥ 50% on DSA was determined using receiver operating curve analysis.ResultsTwo-hundred-and-ten arterial segments were analyzed after exclusion of 30 segments with missing data or metallic artifacts. An inter-reader discordance >10% was observed in 82 segments (82/210; 39% [95% CI: 32–46]). Inter-test discordances >10% were observed respectively in 115 segments (115/210; 55% [95% CI: 49–62]) with the junior reader and in 73 segments (73/210; 35% [95% CI: 29–42]) with the senior reader. They were related to reader error in 55 (55/210; 26% [95% CI: 20–32]) with the junior reader and 13 (13/210; 6% [95% CI: 3–9]) with the senior reader, as well systematic biases in 8 (8/210; 4% [95% CI: 1–6]), and intrinsic limitation in 52 (52/210; 25% [95% CI: 19–31]). Best sensitivity and specificity of CTA were observed for a threshold value of 30% (sensitivity = 88% [95% CI: 78–97%]; specificity = 84% [95% CI: 77–90%]; area under curve = 0.92 [95% CI: 0.86–0.97]). On a patient basis, sensitivity was 100% (specificity = 60% [95% CI: 38–81%]; area under curve = 0.97 [95% CI: 89–100%] for this same threshold.ConclusionOur study shows a moderate accuracy of CTA for the quantification of cerebral vasospasm, mostly related to challenging interpretation and intrinsic limitations. CTA may rule-out angiographic vasospasm ≥ 50% when no segment has vasospasm over than 30%.     

Prospective study comparing three-dimensional computed tomography and magnetic resonance imaging for evaluating the renal vascular anatomy in potential living renal donors

OBJECTIVE: To prospectively compare the accuracy of multislice spiral computed tomographic angiography (CTA) and magnetic resonance angiography (MRA) in evaluating the renal vascular anatomy in potential living renal donors. SUBJECTS AND METHODS: Thirty-one donors underwent multislice spiral CTA and gadolinium-enhanced MRA. In addition to axial images, multiplanar reconstruction and maximum intensity projections were used to display the renal vascular anatomy. Twenty-four donors had a left laparoscopic donor nephrectomy (LDN), whereas seven had right open donor nephrectomy (ODN); LDN was only considered if the renal vascular anatomy was favourable on the left. CTA and MRA images were analysed by two radiologists independently. The radiological and surgical findings were correlated after the surgery. RESULTS: CTA showed 33 arteries and 32 veins (100% sensitivity) whereas MRA showed 32 arteries and 31 veins (97% sensitivity). CTA detected all five accessory renal arteries whereas MRA only detected one. CTA also identified all three accessory renal veins whereas MRA identified two. CTA had a sensitivity of 97% and 47% for left lumbar and left gonadal veins, whereas MRA had a sensitivity of 74% and 46%, respectively. CONCLUSION: Multislice spiral CTA with three-dimensional reconstruction was more accurate than MRA for both renal arterial and venous anatomy.     

Disappearance and reappearance of a cerebral aneurysm: a case report

BACKGROUND: The false-negative rate of DSA in the setting of a ruptured cerebral aneurysm is approximately 15% (Topcuoglu M, Ogilvy C, Carter B, et al. Subarachnoid hemorrhage without evident cause on initial angiography studies: diagnostic yield of subsequent angiography and other neuroimaging tests. J Neurosurg 2003;98:1235-1240). Detecting these aneurysms is imperative to avoid repeat hemorrhage. Rarely, one is able to document the phenomenon of the disappearance and subsequent reappearance of the ruptured aneurysm. CASE DESCRIPTION: This is a case report of subarachnoid hemorrhage (SAH) in which a cerebral aneurysm of the M1 segment of the left proximal middle cerebral artery was initially detected by CTA at an outside hospital only to evade detection with both CTA and DSA at our institution. Repeat DSA 1 week later revealed the culprit aneurysm, which was then treated endovascularly. CONCLUSIONS: Patients with significant SAH and negative DSA findings should be considered for further diagnostic testing including CTA or repeat DSA. The current literature supports the strategy used at our institution of initial CTA and DSA in the setting of SAH, and then subsequent repeat DSA as warranted if the initial studies are nondiagnostic. Timing of repeat examination, as demonstrated in this case, should favor a shorter time course.     

Feasibility of multi-slice computed tomography in the diagnosis of arteriogenic erectile dysfunction

OBJECTIVE: To compare computed tomography (CT) angiography (CTA) obtained by multi-slice CT (a new minimally invasive method) with the current standard of arterial imaging, digital subtraction angiography (DSA), in diagnosing arteriogenic erectile dysfunction (ED). PATIENTS AND METHODS: Twenty-one patients with suspected arteriogenic ED underwent DSA and CTA after providing informed consent. Prostaglandin E1 was injected into the penile cavernosal body and then non-ionic contrast medium was rapidly infused into the antecubital vein. The DSA and CTA images were diagnosed as showing a normal or abnormal status by three reviewers independently. CTA was undertaken on an outpatient basis but DSA required hospitalization. RESULTS: In the 42 internal pudendal arteries, DSA showed 28 normal and 14 impaired arteries; CTA showed 21 normal arteries and 21 occlusions. The CTA image correlated closely with the diagnosis of stenosis or occlusion in internal pudendal arteries, with a sensitivity of 93%, a specificity of 71% and an accuracy of 79%. In the cavernosal arteries, DSA depicted 14 normal and 28 impaired arteries; CTA showed seven normal arteries and 35 occlusions. The CTA image agreed closely with the diagnosis of stenosis or occlusion in cavernosal arteries, with a sensitivity of 96%, a specificity of 43% and an accuracy of 79%. Of the 42 inferior epigastric arteries, DSA could not depict 11 arteries but CTA showed all 42 inferior epigastric arteries. CONCLUSIONS: CTA images correlated with DSA images; at present DSA is better than CTA in visualizing stenosis in fine arteries. However, CTA is less invasive and relatively inexpensive, and in future will probably provide even greater improvements in graphic quality. CTA would be an adequate replacement for DSA in evaluating internal pudendal arterial stenosis.     

Comparison of computerized tomography angiography and digital subtraction angiography in ruptured cerebral aneurysm surgery

Objective: The aim of the present study was to review the efficacy of 16‐row multislice computerized tomography angiography (CTA) in ruptured cerebral aneurysm surgery by comparison with conventional digital subtraction angiography (DSA). Methods: A systemic review of patients suffering from ruptured cerebral aneurysm was performed. We report the results obtained during the 19‐month period from April 2003 to October 2004. In total, 32 patients had undergone aneurysm surgeries, in which 11 patients had both DSA and CTA performed. Results: Among the 11 patients with both DSA and CTA performed, two aneurysms were missed in DSA in two patients. The sensitivity and specificity of CTA were 100%. The correlation of CTA with DSA in operative findings was 100%. Our CTA could detect the aneurysm size down to 2 mm in diameter. Conclusion: The diagnostic accuracy of 16‐row multislice CTA is promising and it compares well with DSA for detection and evaluation of ruptured cerebral aneurysms. It is safe and effective to establish treatment decision on the basis of CTA alone in the majority of cases.     

Effects of a nitric oxide donor on and correlation of changes in cyclic nucleotide levels with experimental vasospasm

OBJECTIVE: Vasospasm after subarachnoid hemorrhage (SAH) may result from hemoglobin-mediated removal of nitric oxide (NO) from the arterial wall. We tested the ability of the long-acting, water-soluble, NO donor (Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-1,2-diolate (DETA/NO), delivered via continuous intracisternal infusion, to prevent vasospasm in a nonhuman primate model of SAH. METHODS: First, vasorelaxation in response to DETA/NO was characterized in vitro by using monkey basilar artery rings under isometric tension. Next, monkeys were randomized to undergo angiography, unilateral SAH, and no treatment (SAH only, n = 4) or treatment with DETA/NO (1 mmol/L, 12 ml/d, n = 4) or decomposed DETA/NO (at the same dose, n = 4). Vasospasm was assessed by angiography, which was performed on Day 0 and Day 7. Levels of cyclic adenosine monophosphate and cyclic guanosine monophosphate (cGMP) were measured in cerebral arteries on Day 7. RESULTS: DETA/NO produced significant relaxation of monkey arteries in vitro, which reached a maximum at concentrations of 10(-5) mol/L. In monkeys, angiography demonstrated significant vasospasm of the right intradural cerebral arteries in all three groups, with no significant difference in vasospasm among the groups (P > 0.05, analysis of variance). The ratios of cGMP or cyclic adenosine monophosphate levels in the right and left middle cerebral arteries were not different among the groups (P > 0.05, analysis of variance). There was no significant correlation between arterial cGMP contents and the severity of vasospasm. CONCLUSION: DETA/NO did not prevent vasospasm. There was no correlation between the severity of vasospasm and cyclic adenosine monophosphate and cGMP levels in the cerebral arteries. These results suggest that events downstream of cyclic nucleotides may be abnormal during vasospasm.     

Vasospasm after traumatic subarachnoid haemorrhage: Transcranial Doppler evaluation. Case report

A case of vasospasm after traumatic subarachnoid haemorrhage (SAH) is reported here. Transcranial Doppler Sonography (TCD) was used to evaluate mean flow velocity (MFV) changes of the basal cerebral arteries related to vasospasm. Accelleration of MFV of the right middle cerebral artery (MCA) indicating vasospasm was first noted on TCD evaluation, and then proved by carotid angiography (CAG). Evaluation of all TCD results revealed that the process of relaxation or normalization of the spastic artery started from the proximal side of the basal intracranial artery and gradually moving to the distal side. This interesting phenomenon could be a common process found in vasospasm cases.     

Arterial diameters on catheter and computed tomographic angiography

BackgroundThe diagnosis of cerebral vasospasm is hampered by lack of an accurate, noninvasive test. Computed tomographic angiography (CTA) may be useful but the correlation between arterial diameters determined from catheter digital subtraction angiography (DSA) and CTA over a range of artery sizes would need to be determined to show this. The purpose of this study was to determine the correlation between artery diameters measured on DSA and multidetector CTA.MethodsTwo hundred forty artery diameters were measured in DSA and CTA from 46 patients who underwent both studies within 12 hours of each other. Axial cross section, maximum intensity projection, and volume-rendered images were measured and compared by linear correlation. Two independent readers measured CTA diameters to determine interobserver variability by linear correlation. Values also were categorized and compared by χ² and κ statistics. Analysis was repeated with unmeasurable arteries assigned a value of 0.ResultsThere were significant correlations between arterial diameters measured on DSA and those from CTA measured by any method (R² ranging from 0.45 to 0.76, P < .0001), although there was a tendency for the slope of this relationship to be less than 1, indicating underestimation of diameter of large and overestimation of diameter of small arteries with CTA. Computed tomographic angiography diameters also correlated significantly between the 2 reviewers with higher values often when unmeasureable arteries were assigned a value of 0 (κ = 0.23-0.55, P < .0001).ConclusionArterial diameters measured on multidetector CTA correlate well with those determined from DSA and should permit use of CTA for quantitative study of cerebral vasospasm and other conditions requiring accurate measurement of arterial diameters. The limitation of CTA remains the inability to measure some arteries due to artifact.     

Subarachnoid haemorrhage of unknown aetiology: what next?

Subarachnoid haemorrhage (SAH) is often associated with negative cerebral angiography. Following the exclusion of other causes, a patient may be suspected of harbouring an occult intracranial aneurysm, with risk of recurrent bleeding and death. These patients are often identified on the basis of clinical presentation and computed tomography (CT) findings, and require expeditious further investigation if morbidity and mortality are to be minimized. Currently available options include repeated cerebral angiography, surgical exploration, and the newer technologies of computed tomography angiography (CTA) and magnetic resonance angiography (MRA). We review these options, based on current literature, with particular emphasis on the expanding roles of CTA and MRA. A multimodality management protocol is proposed, with decisions based on clinical urgency, patient progress and the natural history of aneurysmal SAH, particularly vasospasm and aneurysm thrombosis.     

Evaluation of cerebral vasospasm in patients with subarachnoid hemorrhage using single photon emission computed tomography

Cerebral vasospasm (CVS) occurs as a result of the breakdown in cerebral autoregulation mechanisms. Because cerebral vasospasm can occur after subrachnoid hemorrhage (SAH), it is important to evaluate borderline perfusion. Evaluation of borderline vascular insufficiency is important to reduce ischemic complications. In this study 25 patients with SAH were investigated by somatosensory evoked potentials (SEP), computed tomography (CT), digital subtraction angiography (DSA) and single photon emission computed tomography (SPECT) in order to predict borderline ischemic areas. Clinical grades were also correlated with these investigations. Thirteen patients had symptomatic vasospasm and 15 patients had angiographic vasospasm. SPECT showed hypoperfusion in 22 out of 25 patients. CT predicted CVS in 8 of these 22 patients. Our study shows that brain perfusion SPECT is a non-traumatic, non-invasive, non-allergic, inexpensive method for the prediction of cerebral vasospasm. We conclude that brain SPECT with Tc-99m HM-PAO is an accessible technique that can demonstrate varying degrees of regional tissue hypoperfusion in patients with delayed ischemic deficits due to CVS following SAH.     

Computed tomographic angiography and perfusion in the diagnosis of brain death

IntroductionAccording to Polish brain death (BD) criteria, instrumental confirmatory tests should be used in certain clinical situations, particularly any case for which clinical examinations seem inadequate. Electrophysiological tests are often unavailable. Therefore, cerebral perfusion testing is the method of choice with four-vessel digital subtraction angiography (DSA), the gold standard. Unfortunately, DSA is an expensive and invasive examination that requires an experienced neuroradiologist and the availability of an angiography suite. Recently, multirow computed tomographic devices became available, even in smaller hospitals in Poland. Despite this fact, computed tomographic angiography (CTA) and computed tomographic perfusion (CTP) are not accepted in BD diagnosis protocols in Poland because of limited experience and a lack of widely accepted criteria. In this situation, we started a multicenter trial to determine the accuracy of CTA and CTP to confirm BD.MethodsWe examined 24 patients who fulfilled standard clinical BD criteria. We recognized the absence of brain perfusion in CTA examination following the criteria proposed by the French Society of Neuroradiology, namely, the absence of opacification of M4 middle cerebral artery segments (M4-MCA) and of deep cerebral veins.ResultsIn all of our patients, CTA showed absence of opacification of M4 segments and of deep cerebral veins. In addition, three patients had CTA showing weak opacification of A2 segments of the anterior cerebral artery (A2-ACA) and M2 or M3-MCA. Opacification of the basilar artery or of the posterior cerebral arteries was not noted in any case. In all patients, CTP revealed zero values of regional cerebral blood volume and regional cerebral blood flow. Conventional angiography confirmed cerebral circulatory arrest in all 24 cases.ConclusionCTA and CTP seem to be promising radiological examinations for the diagnosis of BD. They may be noninvasive alternatives to conventional cerebral angiography, and to the other instrumental confirmatory tests, that are unavailable or inadequate.     

Pitfalls in the preoperative evaluation of subarachnoid hemorrhage without digital subtraction angiography: report on 2 cases

BACKGROUND: Digital subtraction angiography has been used in the diagnosis of aneurysmal SAH and as a preoperative imaging method. However, new methods such as MRA and CTA are now deemed by many institutions to provide sufficient information to allow surgery to go ahead without a preliminary DSA scan. We report on 2 cases of SAH in which there were additional lesions that were difficult to evaluate because of the lack of DSA information. CASE DESCRIPTIONS: The fist patient demonstrated SAH with IVH. Computed tomographic angiography revealed an ACoA aneurysm with a bleb. We first thought that the SAH and IVH were both caused by a ruptured ACoA aneurysm but noted that hemorrhage pattern was inconsistent with the location and orientation of the aneurysm. A DSA scan revealed a dural arteriovenous fistula in the region of the craniocervical junction, supplied by the right occipital artery. We surmised that the SAH and IVH were caused by a large varix of DAVF and that the ACoA aneurysm would be unruptured. The second patient presented with a 1-week history of headaches and nausea and was diagnosed to have an SAH caused by a ruptured MCA aneurysm. We suspected vasospasm in the second portion of the MCA on CTA, but could not precisely evaluate the affected lesions. A diffusion-weighted MRI scan 4 days after surgery revealed a high-intensity area in the region of the right MCA. The MCA had already seemed to be affected at admission because vasospasm rarely develops within 4 days of the onset of SAH. CONCLUSIONS: As long as the CTA scan is of adequate quality and shows the aneurysm clearly, we consider that an additional DSA provides little useful information for surgery. However, in such cases, the information from a DSA scan is needed for the evaluation of secondary factors that are not directly associated with the aneurysm.     

The correlation between immunological reaction in the arterial wall and the time course of the development of cerebral vasospasm in a primate model

To investigate the role of immunological reactions in the development of cerebral vasospasm after subarachnoid hemorrhage (SAH), the authors studied the correlation between immune/inflammatory reactions in the arterial wall and the time course of vasospasm in primates. Twenty monkeys were divided into four groups of 5 animals each: 1) a control group of sham-operated animals, 2) animals subjected to angiography 3 days after the induction of SAH (3-day SAH), 3) animals subjected to angiography 7 days after SAH (1-week SAH), and 4) animals subjected to angiography 7 and 14 days after SAH (2-week SAH). To induce SAH, the main cerebral arteries on the right were dissected free of the arachnoid, and an autologous blood clot was placed around the arteries. To evaluate vasospasm, all animals underwent a baseline angiogram before SAH; angiography was repeated at different intervals in each group, as outlined above. Histopathological changes and the deposition of the immunoglobulin IgG in the arterial wall were evaluated immunohistochemically in each group. The cerebral arteries on the side of the clot showed evidence of mild vasospasm (-24.6% reduction) on the angiogram performed on Day 3, severe vasospasm (-51.7%) on Day 7, and mild vasospasm (-12.8%) on Day 14. The infiltration of inflammatory cells was most marked in the spastic arterial wall in the 1-week SAH group. In the 2-week SAH group, severe myonecrosis and intimal disruption were observed, even in the vessels that showed only mild vasospasm, and the inflammatory reactions had almost abated.(ABSTRACT TRUNCATED AT 250 WORDS)     

Subarachnoid Heamorrhage-Induced Chronic Cerebral Vasospasm in the Rabbit: IV-DSA Versus IA-DSA

Summary.  Background: Chronic cerebral vasospasm is delayed-onset cerebral arterial narrowing in response to blood clots left in the subarachnoid space after aneurysmal subarachnoid haemorrhage (SAH). Rabbit models of vasospasm have been developed as in vivo experimental pathogenesis and the treatments of cerebral vasospasm using human vessels are not possible. The present study assessed the diagnostic accuracy of the intravenous digital subtraction angiography (IV-DSA) in chronic cerebral arterial spasm following induced SAH in the rabbit.  Method: Ten rabbits' left leg veins catheterised by intravascular access needle and 3F catheters introduced to the right leg arteries probing the proximal of the vertebral arteries. Initially IV-DSA and intra-arterial digital subtraction angiography (IA-DSA) was performed. Three millilitres of fresh autologous arterial blood was injected into the cisterna magna of the ten rabbits' in order to produce in vivo model of chronic SAH. Angiograms were obtained 15 minutes and 72 hours after the SAH.  Findings: Diameters of the basilar arteries were similar to each other in both methods and reduced after the SAH.  Interpretation:The present study shows that IV-DSA is a relatively simple and effective method for demonstrating cerebral vessels, especially the basilar artery. Published online September 2, 2002 Correspondence: Tanzer Sancak M.D., Mesa Camyolu sitesi, B1 Blok A17 Yenikent, Cayyolu, Ankara, Turkey.     

全脑CT灌注同步CT血管成像评价蛛网膜下腔出血后表现及预后

目的探讨全脑CT灌注同步CT血管成像评价蛛网膜下腔出血(SAH)后表现及预后的价值。方法 SAH患者71例,按发病时间分为急性期(3天内)与延迟期(4～15天)。所有患者接受CT平扫、CTA及CT灌注成像(CTP),以动脉期数据重建VR脑动脉图像,生成全脑灌注脑血容量(CBV)、脑血流量(CBF)、平均通过时间(MTT)、达峰时间(TTP)图像,判断有无脑血管痉挛,分析不同预后患者CTP各参数的变化。结果 71例SAH患者中,急性期SAH患者44例,预后差者占31.82%(14/44),延迟期SAH患者27例,其中预后差者占40.74%(11/27,χ2=0.584,P=0.445)。急性期和延迟期预后好与预后差患者的CTP各参数差异均有统计学意义(P均<0.05)。结论CTP结合CTA同步检查有助于判断不同时期SAH继发脑血管痉挛患者的预后,指导临床及时进行合理治疗。     

Wall Imaging of Cerebral Aneurysms with a Modified Surface-Rendering Technique of Spiral CT

Summary ? Background. There has been no detailed documentation of the advantages of three-dimensional (3D) wall imaging of cerebral aneurysms. The usefulness of such endoscopic images obtained with modified spiral computed tomography angiography (CTA) was therefore examined in comparison with conventional spiral CTA and digital subtraction angiography (DSA).  Methods. Fifteen of 45 patients who underwent conventional spiral CTA in our department in the past 4 years, were further studied with a technical modification of surface-rendering reconstruction in spiral CT. Endoscopic images were obtained by regulating the lower and higher thresholds of spiral CT scans in processing. Digital subtraction angiography was also performed for 14 of the 15 patients. The 3D wall images of the cerebral aneurysms were assessed in comparison with findings from conventional CTA and DSA.  Findings. The true orifice of the aneurysms could be visualized with the endoscopic mode in all of the 15 cases. In paraclinoid aneurysms, particularly below the anterior clinoid process, the relationships to associated vessels and bone structures were more clearly disclosed with this mode. The endoscopic images of aneurysms with rigid clots or neighboring distended veins were not as adversely affected as conventional CTA. In 4 of the 15 the wall imaging precisely located the branches arising from the dome of aneurysms which DSA could not.  Interpretation. Wall imaging of complex or small cerebral aneurysms provided valuable information on their relationships to associated arteries and surrounding bony structures. The endoscopic mode, a simple modification of surface rendering, is easily available in commercial CT processing packages.     

Surgical manipulation of primate cerebral arteries in established vasospasm

It is generally believed that surgery in the face of angiographic vasospasm is dangerous due to an increased incidence of postoperative cerebral ischemia. One theory is that arterial narrowing is exacerbated by surgical manipulation of vasospastic vessels during aneurysm dissection and clipping. This theory was tested in a primate model of cerebral vasospasm and the results reported. Six monkeys underwent baseline cerebral angiography, followed by induction of subarachnoid hemorrhage (SAH) on both sides of the circle of Willis. An equal amount of fresh autologous blood clot was placed around each internal carotid, anterior cerebral, and middle cerebral artery. Six days later, angiography was repeated and the right craniectomy was reopened for clot evacuation and surgical manipulation of the right cerebral arteries, including placement of a temporary aneurysm clip on the right middle cerebral artery. The left cerebral arteries were not exposed or manipulated, and served as controls. Twenty-four hours later angiography was repeated, then the animals were killed. Equal and significant vasospasm (greater than 40% reduction in vessel caliber compared to baseline, p less than 0.05) was seen in the middle cerebral arteries on both sides of the circle of Willis in all animals 6 and 7 days after SAH. There was no significant change in the severity of vasospasm on Day 7 compared with Day 6 in the right cerebral arteries. Increased risk of postoperative cerebral ischemia for surgery in the peak vasospasm period may be due to mechanisms other than increased arterial narrowing precipitated by surgical manipulation.