Brain Computed Tomography Angiographic Scans as the Sole Diagnostic Examination for Excluding Aneurysms in Patients with Perimesencephalic Subarachnoid Hemorrhage

Digital subtraction cerebral angiography after negative computed tomography angiography findings in non-traumatic subarachnoid hemorrhage

Background

CT angiography (CTA) is widely used for the detection of vascular lesions in patients with non-traumatic subarachnoid hemorrhage (ntSAH); however, digital subtraction angiography (DSA) remains the gold standard for diagnosis. Our aim was to analyze the diagnostic yield of DSA after negative high-resolution CTA findings.

Methods

Records of patients with a CTA-negative ntSAH at a single institution from 2014 to 2018 were retrospectively analyzed. ntSAH patterns were categorized as cortical, perimesencephalic, or diffuse. Subsequent DSA findings were compared across the three cohorts.

Results

A total of 186 patients had CTA-negative ntSAH. The ntSAH pattern was identified as cortical (n=77, 41.4%), diffuse (n=60, 32.3%), or perimesencephalic (n=49, 26.3%). In eight patients (4%), DSA revealed a vascular lesion (one cervical arteriovenous fistula and seven atypical aneurysms) after negative CTA findings. All eight patients with positive DSA findings had diffuse SAH (13% of patients with a diffuse pattern). The seven aneurysms included four blister or dissecting (two basilar artery, one superior cerebellar artery, and one dorsal wall internal carotid artery), two fusiform (one posterior communicating artery and one anterior spinal artery), and one saccular aneurysm (middle cerebral artery).

Conclusion

DSA identified a causative lesion in 4% of patients with CTA-negative ntSAH, but only in patients with diffuse ntSAH. Most of the lesions detected were atypical aneurysms and were found on delayed angiograms. These results suggest that DSA can help to diagnose CTA-negative ntSAH caused by unusual aneurysms, and repeat DSA may be needed only for patients with diffuse ntSAH.

CT angiogram negative perimesencephalic subarachnoid hemorrhage: is a subsequent DSA necessary? A systematic review

Background

Perimesencephalic subarachnoid hemorrhage (PMSAH) is a benign subtype with distinct clinical-radiologic features. Digital subtraction angiography (DSA) remains the gold standard investigation for exclusion of a macrovascular cause, although increasingly more clinicians rely solely on CT angiography (CTA). The primary aim of this systematic review was to evaluate the current literature regarding the negative predictive value of CTA.

Methods

A systematic search in concordance with the PRISMA checklist was performed for studies published between 2000 and 2018. Studies with ≥10 adult patients diagnosed on a non-contrast brain CT with a PMSAH, who underwent a negative CTA and were subsequently subject to a DSA, were included. Simple pooled analysis was performed to inform the negative predictive value (95% CI) of CTA and the risk of DSA- and CTA-related complications.

Results

Eighteen studies (669 patients) were included. All patients were subject to at least one DSA, the first one mostly performed within 24 hours of CTA (68.6%). 144 patients (21.5%) underwent a second DSA and a third repeat DSA was performed in one patient. The overall negative predictive value of CTA was 99.0% (95% CI 97.8% to 99.5%). The risk of complications following DSA and CTA were 1.35% (3/222) and 0% (0/41), respectively.

Conclusions

Undertaking a DSA after a negative CTA may not add any further diagnostic value in patients with PMSAH and may lead to net harm. This observation needs to be validated in a large-scale prospective multicenter study with complete case ascertainment and robust data on CTA and DSA complications.

Meta-analysis of recent literature on utility of follow-up imaging in isolated perimesencephalic hemorrhage

OBJECTIVES

Isolated perimesencephalic subarachnoid hemorrhage is an uncommon, distinct subtype of subarachnoid hemorrhage with a more benign prognosis. A negative computed tomographic angiogram has been shown to be reliable in excluding aneurysmal rupture as the underlying etiology. However, some studies continue advocating for more imaging to determine a vascular cause in perimesencephalic subarachnoid hemorrhage. The objective of this study is to evaluate the evidence for use and utility of repeat angiographic imaging after a negative computed tomographic angiogram in patients with perimesencephalic subarachnoid hemorrhage.

PATIENTS AND METHODS

Retrospective institutional analysis of patients with perimesencephalic subarachnoid hemorrhage was performed from 2014 to 2017 for number and types of follow-up angiographic imaging studies performed. Updated meta-analysis of literature was performed from 2014 onwards to assess the utility of follow-up imaging after a negative initial angiographic study.

RESULTS

The institutional review revealed no utility of additional imaging after a negative computed tomographic angiogram in 6 patients with isolated perimesencephalic subarachnoid hemorrhage. Literature review and metaanalysis of 13 studies with 588 patients revealed a vascular etiology in 3 patients with isolated perimesencephalic subarachnoid hemorrhage from a single study- 2 aneurysms and 1 patient with vasculitis.

CONCLUSIONS

Use of repeat angiographic imaging after a negative computed tomographic angiogram for perimesencephalic subarachnoid hemorrhage patients remains not uncommon, despite previous meta-analysis. Review of the more recent literature is consistent with previously published meta-analysis and shows limited benefits despite frequent use. In patients with a strictly defined perimesencephalic subarachnoid hemorrhage pattern and clinical picture consistent with perimesencephalic subarachnoid hemorrhage, an initial negative computed tomographic angiogram should be adequate and repeated follow-up studies can be avoided.

Digital Subtraction Angiography for CT Angiogram Negative Haemorrhages

BACKGROUND

In patients with subarachnoid haemorrhage (SAH) and a negative finding on CT angiography (CTA), further imaging with digital subtraction angiography (DSA) is commonly performed to identify the source of bleeding. The purpose of this study was to investigate whether negative findings on CTA can reliably exclude aneurysms in patients with acute SAH.

METHODS

This retrospective study identified all DSAs performed between August 2010 and July 2014 within our institution. CT angiography was performed with a 64-section multidetector row CT scanner. Only DSAs from patients with confirmed SAH and a negative CTA result were included in the final analyses. A fellowship-trained neuroradiologist reviewed the imaging results.

RESULTS

Of the 857 DSAs, 50 (5.83%) were performed in 35 patients with CTA-negative SAH. Of the 35 patients, three (8.57%) had positive findings on the DSA. In one patient, suspicious dissection of the extra- and intra-cranial segment of the right vertebral artery could not be confirmed even in retrospect. In the second patient, the suspicious finding of tiny protuberance from the left paraclinoid internal carotid artery (ICA) on DSA did not change on follow-up and did not change patient's management. The third patient had a posterior inferior cerebellar artery aneurysm, which was not seen on the initial CTA owing to the incomplete coverage of the head on the CTA.

CONCLUSION

In patients with SAH, negative findings on a technically sound CTA are reliable in ruling out aneurysms in any pattern of SAH or no blood on CT. Our observations need to be confirmed with larger prospective studies.

The Clinical Value of d-Dimer Level in Patients with Nonaneurysmal Subarachnoid Hemorrhage

OBJECTIVE

More nonaneurysmal subarachnoid hemorrhage (NaSAH) are found in clinical practice. However, the precise mechanisms in which d-dimer level is associated with clinical condition in patients with NaSAH remain unclear. But even more, the data assessing the risk of clinical course in the patients with NaSAH are scarce. Our objective was to investigate whether d-dimer levels correlated with complication and outcome in patients with NaSAH.

METHODS

Between February 2013 and May 2017, 92 patients suffering from NaSAH were treated in our hospital. Patient characteristics, radiologic features, laboratory findings, complications, and outcomes were analyzed retrospectively. Patients were stratified into the perimesencephalic (PM) subarachnoid hemorrhage (SAH) group and the nonperimesencephalic (NPM) SAH group according to the bleeding type, and the NPM-SAH group was further divided into 2 subgroups into the NPM-elevated group and the NPM-normal group based on the value of the d-dimer. After statistical analysis, the NPM-SAH and PM-SAH groups were compared; the same was true for the NPM-elevated group and the NPM-normal group.

RESULTS

The rate of complications in the NPM-SAH group was higher than in the PM-SAH group, including early hydrocephalus, delayed cerebral ischemia, clinical vasospasm, pneumonia, and hyponatremia. Our results showed that d-dimer levels in patients with NPM-SAH were more elevated than in those with PM-SAH. Further analysis of subgroups demonstrated that patients with elevated d-dimer levels had a higher incidence of complications than those with normal d-dimer levels, especially the risks of shunt-dependent hydrocephalus and pneumonia. In addition, disability, and even death, could be seen in patients with higher levels of d-dimer, but the long-term outcomes were not particularly obvious between these groups.

CONCLUSIONS

Elevated d-dimer levels on admission were significantly associated with complication in patients with NPM-SAH. In addition to conventional radiologic diagnosis, d-dimer levels can increase the ability of a rapid differential diagnosis between NPM-SAH and PM-SAH.

Non-aneurysmal subarachnoid hemorrhage: When is a second angiography indicated?

Purpose Repeat imaging in patients with non-aneurysmal subarachnoid hemorrhage (NASAH) remains controversial. We aim to report our experience with NASAH with different hemorrhage patterns, and to investigate the need for further diagnostic workup to determine the underlying cause of hemorrhage. Method We conducted a retrospective analysis of all spontaneous SAH with an initial negative computed tomography (CT) with angiography (CTA) and/or digital subtraction angiography (DSA) from October 2011 through May 2017. According to the bleeding pattern on the admission CT scan, NASAH was divided into two subgroups: (1) perimesencephalic SAH (PMSAH) and (2) non-perimesencephalic SAH (nPMSAH). Radiological data included the admission CT, CTA, DSA, and magnetic resonance imaging (MRI) with angiography (MRA). Results Seventy-four patients met the inclusion criteria. Thirty-nine (52.7%) patients had PMSAH on the initial CT scan, and 35 (47.3%) had nPMSAH. All underwent CTA and/or DSA revealing no vascular abnormalities. Forty-seven (63.5%) patients underwent subsequent diagnostic workup. DSA was performed in all patients at least once. No abnormalities were found on the repeat DSA or other radiological follow-up studies except in one (1.4%) patient with nPMSAH, in whom a follow-up DSA revealed a small saccular anterior choroidal artery aneurysm, considered to be the source of hemorrhage. Conclusion A repeat DSA may not be needed in case of PMSAH, if the initial negative DSA is technically adequate with absence of hematoma and vasospasm. In contrast, a follow-up DSA should be mandatory for confirming or excluding vascular pathology in case of nPMSAH in order to prevent rebleeding.

CT angiography in non-traumatic subarachnoid hemorrhage: the importance of arterial attenuation for the detection of intracranial aneurysms

BACKGROUND

Computed tomography angiography (CTA) is today the primary method for the detection of intracranial aneurysms. The technique has evolved considerably during the last decade, and it is important to establish criteria for high image quality, especially with regard to improving the diagnosis of small aneurysms.

PURPOSE

To evaluate diagnostic accuracy and image quality by arterial attenuation of CTA in patients with non-traumatic subarachnoid hemorrhage (SAH).

MATERIAL AND METHODS

Between 2005 and 2011, CTA and digital subtraction angiography (DSA) were performed in 326 patients with non-traumatic SAH. Sensitivity and specificity for aneurysm detection were evaluated per patient, per aneurysm, and per ruptured aneurysm. The image quality of CTA was evaluated by arterial attenuation measurements (mean Hounsfield units [HU]) in the internal carotid artery (ICA).

RESULTS

In all, 285 aneurysms in 235 patients were detected by DSA, 19 aneurysms were missed on CTA, and 223 aneurysms were classified as ruptured. In 91 patients, no aneurysm was found. Correct diagnosis with CTA was made in 28 patients with perimesencephalic hemorrhage. Sensitivity and specificity (95% confidence interval) calculated per patient were 91.6% (87.3-94.9) and 87.9% (79.8-93.6), respectively, per aneurysm 93.3% (89.7-95.9) and 88% (79.9-93.6), and per ruptured aneurysm 94.9% (91.3-97.3) and 96.7% (90.7-99.3). Arterial attenuation (in HU) in CTA revealing true positive ruptured aneurysms and true negative aneurysms (mean 535 ± 110 HU) differed significantly (P = 0.02) from false negative ruptured aneurysms (mean 424 ± 30 HU).

CONCLUSION

CTA has high sensitivity and specificity for the detection of ruptured aneurysms. The sensitivity is related to arterial attenuation in the ICA.

Cerebral Angiography for Evaluation of Patients with CT Angiogram-Negative Subarachnoid Hemorrhage: An 11-Year Experience

BACKGROUND AND PURPOSE

CT angiography is increasingly used to evaluate patients with nontraumatic subarachnoid hemorrhage given its high sensitivity for aneurysms. We investigated the yield of digital subtraction angiography among patients with SAH or intraventricular hemorrhage and a negative CTA.

MATERIALS AND METHODS

An 11-year, single-center retrospective review of all consecutive patients with CTA-negative SAH was performed. Noncontrast head CT, CTA, DSA, and MR imaging studies were reviewed by 2 experienced interventional neuroradiologists and 1 neuroradiologist.

RESULTS

Two hundred thirty patients (mean age, 54 years; 51% male) with CTA-negative SAH were identified. The pattern of SAH was diffuse (40%), perimesencephalic (31%), sulcal (31%), isolated IVH (6%), or identified by xanthochromia (7%). Initial DSA yield was 13%, including vasculitis/vasculopathy (7%), aneurysm (5%), arteriovenous malformation (0.5%), and dural arteriovenous fistula (0.5%). An additional 6 aneurysms/pseudoaneurysms (4%) were identified by follow-up DSA, and a single cavernous malformation (0.4%) was identified by MRI. No cause of hemorrhage was identified in any patient presenting with isolated intraventricular hemorrhage or xanthochromia. Diffuse SAH was due to aneurysm rupture (17%); perimesencephalic SAH was due to aneurysm rupture (3%) or vasculitis/vasculopathy (1.5%); and sulcal SAH was due to vasculitis/vasculopathy (32%), arteriovenous malformation (3%), or dural arteriovenous fistula (3%).

CONCLUSIONS

DSA identifies vascular pathology in 13% of patients with CTA-negative SAH. Aneurysms or pseudoaneurysms are identified in an additional 4% of patients by repeat DSA following an initially negative DSA. All patients with CT-negative SAH should be considered for DSA. The pattern of SAH may suggest the cause of hemorrhage, and aneurysms should specifically be sought with diffuse or perimesencephalic SAH.

Recurrent Perimesencephalic Subarachnoid Hemorrhage After 12 Years: Missed Diagnosis, Vulnerable Anatomy, or Random Events?

BACKGROUND

Perimesencephalic subarachnoid hemorrhage (PMSAH) is a well-defined subtype of angiogram-negative SAH, characterized by a benign natural history and a virtually nonexistent risk of recurrence. Few case reports of recurrent PMSAH exist in the literature, all occurring after relatively short time intervals ranging from 5 days to 31 months, mostly in patients on antithrombotic therapy. We present a unique case of ultra-late PMSAH recurrence after 12 years, in a patient not receiving antithrombotic medications.

CASE DESCRIPTION

A woman presented with 2 similar episodes of sudden-onset severe headache and neck pain, without associated neurologic deficits: a first episode at the age of 48 years and a second at 60 years. In each instance, the pattern of hemorrhage was consistent with PMSAH, platelet count and coagulation tests were normal, and a full etiologic work-up, including CTA, catheter angiography, and magnetic resonance imaging, failed to reveal an underlying vascular or tumoral etiology. The patient had a favorable clinical course each time.

CONCLUSIONS

Although exceptional, recurrence of PMSAH is not impossible. If the 2 events are assumed to be random and independent of each other, binomial statistics yield approximately a 79 per billion chance of 2 or more episodes occurring over an 80-year lifetime. However, other possibilities should be kept in mind, including tiny and radiographically occult vascular lesions or particular venous anatomy predisposing patients to recurrent bouts of PMSAH. Patients should not be told that the risk of recurrence is zero, but that it is close to zero.

The negative predictive value of CT angiography in the setting of perimesencephalic subarachnoid hemorrhage

Background

Perimesencephalic subarachnoid hemorrhage (PMSAH) is only rarely associated with a ruptured cerebral aneurysm and CT angiography (CTA) has very good sensitivity and specificity for aneurysm detection. The necessity for invasive imaging with digital subtraction angiography (DSA) is therefore debatable. We chose to assess the negative predictive value (NPV) of CTA in a series of patients with PMSAH treated at our institution over a 9-year period.

Methods

We retrospectively assessed the diagnostic yield of DSA after initial negative CTA in patients with a PMSAH pattern defined as blood centered anterior to the midbrain and/or pons within the pre-pontine or interpeduncular cistern with possible quadrigeminal or ambient cistern extension; possible extension into the basal parts of the sylvian fissures but not the lateral sylvian fissures; possible extension to the cisterna magna but not centered on the cisterna magna; and possible extension into the fourth ventricle and occipital horns of the lateral ventricles.

Results

Using this definition of PMSAH, of 72 patients, one patient showed a potentially significant finding on DSA that was not demonstrated on initial CTA (NPV 98.61% (95% CI 92.47% to 99.77%)). However, when cisterna magna extension was excluded from the definition of PMSAH, no false negative CTAs in 56 patients were encountered (NPV 100% (95% CI 93.56% to 100.00%)).

Conclusions

The NPV of normal CTA for an arterial abnormality in patients with PMSAH is high and our results therefore question the role of invasive imaging. The findings also suggest that a prospective study designed to clarify the necessity of performing DSA in this population would be feasible.

Use of Follow-Up Imaging in Isolated Perimesencephalic Subarachnoid Hemorrhage

Background and Purpose—

Multiple studies have shown that negative computed tomographic angiograms (CTAs) are reliable in excluding aneurysms in patients with isolated perimesencephalic subarachnoid hemorrhage (pSAH). We evaluate the use of digital subtraction angiography versus CTA for initial diagnosis and of angiographic follow-ups in patients with pSAH by performing an institutional analysis and a meta-analysis of literature.

Methods—

Retrospective institutional analysis of patients with pSAH was performed from 2008 to 2014. The number and types of follow-up imaging studies were tabulated. Initial and follow-up studies were evaluated by an experienced neuroradiologist for intracranial aneurysm. Meta-analysis of literature was performed to assess the use of initial digital subtraction angiography and of follow-up imaging.

Results—

Our institutional review revealed no additional use of initial digital subtraction angiography or of any angiographic follow-up after initial negative CTA in patients with pSAH on noncontrast CT. Meta-analysis of 40 studies yielded a total of 1031 patients. Only 8 aneurysms were first diagnosed on follow-ups (0.78%). Careful review showed that some of these aneurysms reported on follow-up are of questionable validity. Initial digital subtraction angiography and follow-up imaging after a negative initial CTA showed no statistically significant benefits.

Conclusions—

In patients meeting the strict imaging criteria of pSAH, initial negative CTA is reliable in excluding aneurysms. A critical review of the literature through meta-analysis shows no foundation for multiple follow-up studies in patients with pSAH.

Nonaneurysmal perimesencephalic subarachnoid hemorrhage: diagnosis, pathophysiology, clinical characteristics, and long-term outcome

Patients with nonaneurysmal perimesencephalic subarachnoid hemorrhage (NAPSAH) have no discernible source for the bleeding and generally are considered to have a benign condition. Correctly diagnosing these patients is essential because a missed aneurysm can have catastrophic consequences. Those presenting with NAPSAH have a low risk of complications and better outcome than patients presenting with aneurysmal subarachnoid hemorrhage; however, a limited body of literature suggests that not all of these patients are able to return to their premorbid functional status. Clinical screens of cognitive status, such as the mini-mental status examination, suggest good recovery of these patients, although these tests may lack sensitivity for identifying deficits in this patient population. More comprehensive neuropsychologic testing in some studies has identified deficits in a wide range of cognitive domains at long-term follow-up in patients with NAPSAH. Because these patients often do not lose consciousness (and thus do not have substantial transient global ischemia) and they do not undergo a procedure for aneurysm repair, the cognitive sequelae can be explained by the presence of blood in the subarachnoid space. NAPSAH presents an opportunity to understand the effects of subarachnoid blood in a clinical setting.

Subarachnoid hemorrhage: beyond aneurysms

OBJECTIVE

Spontaneous subarachnoid hemorrhage (SAH) typically prompts a search for an underlying ruptured saccular aneurysm, which is the most common nontraumatic cause. Depending on the clinical presentation and pattern of SAH, the differential diagnosis may include a diverse group of causes other than aneurysm rupture.

CONCLUSION

For the purposes of this review, we classify SAH into three main patterns, defined by the distribution of blood on unenhanced CT: diffuse, perimesencephalic, and convexal. The epicenter of the hemorrhage further refines the differential diagnosis and guides subsequent imaging. Additionally, we review multiple clinical conditions that can simulate the appearance of SAH on CT or MRI, an imaging artifact known as pseudo-SAH.

Repeat digital subtraction angiography after a negative baseline assessment in nonperimesencephalic subarachnoid hemorrhage: a pooled data meta-analysis

OBJECT

A repeat digital subtraction angiography (DSA) study of the cranial vasculature is routinely performed in patients with diffuse nonperimesencephalic subarachnoid hemorrhage (SAH) after negative baseline CT angiography (CTA) and DSA studies. However, DSA carries a low but substantial risk of neurological complications. Therefore, the authors evaluated the added value of repeat DSA in patients with initial angiographically negative diffuse nonperimesencephalic SAH.

METHODS

A systematic review of the contemporary literature was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. Studies from January 2000 onward were reviewed since imaging modalities have much improved over the last decade. A pooled analysis was conducted to identify the detection rate of repeat DSA. In addition, the diagnostic yield of repeat DSAs in a prospectively maintained single-center series of 1051 consecutive patients with SAH was added to the analysis.

RESULTS

An initial search of the literature yielded 179 studies, 8 of which met the selection criteria. Another 45 patients from the authors' institution were included in the study, providing 368 patients eligible for the pooled analysis. In 37 patients (10.0%, 95% CI 7.4%-13.6%) an aneurysm was detected on repeat DSA. The timing of the repeat DSA varied from 1 to 6 weeks after the initial DSA. The use of 3D techniques was poorly described among these studies, and no direct comparisons between CTA and DSA were made.

CONCLUSIONS

Repeat DSA is still warranted in patients with a diffuse nonperimesencephalic SAH and negative initial assessment. However, the exact timing of the repeat DSA is subject to debate.

Nontraumatic subarachnoid hemorrhage management: evaluation with reduced iodine volume at CT angiography

PURPOSE

To evaluate the technical quality and the diagnostic performance of a protocol with use of low volumes of contrast medium (25 mL) at 64-detector spiral computed tomography (CT) in the diagnosis and management of adult, nontraumatic subarachnoid hemorrhage (SAH).

MATERIALS AND METHODS

This study was performed outside the United States and was approved by the institutional review board. Intracranial CT angiography was performed in 73 consecutive patients with nontraumatic SAH diagnosed at nonenhanced CT. Image quality was evaluated by two observers using two criteria: degree of arterial enhancement and venous contamination. The two independent readers evaluated diagnostic performance (lesion detection and correct therapeutic decision-making process) by using rotational angiographic findings as the standard of reference. Sensitivity, specificity, and positive and negative predictive values were calculated for patients who underwent CT angiography and three-dimensional rotational angiography. The intraclass correlation coefficient was calculated to assess interobserver concordance concerning aneurysm measurements and therapeutic management.

RESULTS

All aneurysms were detected, either ruptured or unruptured. Arterial opacification was excellent in 62 cases (85%), and venous contamination was absent or minor in 61 cases (84%). In 95% of cases, CT angiographic findings allowed optimal therapeutic management. The intraclass correlation coefficient ranged between 0.93 and 0.95, indicating excellent interobserver agreement.

CONCLUSION

With only 25 mL of iodinated contrast medium focused on the arterial phase, 64-detector CT angiography allowed satisfactory diagnostic and therapeutic management of nontraumatic SAH.

Cerebral aneurysm exclusion by CT angiography based on subarachnoid hemorrhage pattern: a retrospective study

Background

To identify patients with spontaneous subarachnoid hemorrhage for whom CT angiography alone can exclude ruptured aneurysms.

Methods

An observational retrospective review was carried out of all consecutive patients with non-traumatic subarachnoid hemorrhage who underwent both CT angiography and catheter angiography to exclude an aneurysm. CT angiography negative cases (no aneurysm) were classified according to their CT hemorrhage pattern as "aneurismal", "perimesencephalic" or as "no-hemorrhage."

Results

Two hundred and forty-one patients were included. A CT angiography aneurysm detection sensitivity and specificity of 96.4% and 96.0% were observed. All 35 cases of perimesencephalic or no-hemorrhage out of 78 CT angiography negatives also had negative angiography findings.

Conclusions

CT angiography is self-reliant to exclude ruptured aneurysms when either a perimesencephalic hemorrhage or no-hemorrhage pattern is identified on the CT within a week of symptom onset.

Perimesencephalic subarachnoid hemorrhage: risk factors, clinical presentations, and outcome

BACKGROUND

Perimesencephalic nonaneurysmal subarachnoid hemorrhage (PNSH) appears to have an origin and natural history distinct from aneurysm rupture. However, the risk factors and complications of this pattern are still in debate. We performed a study with goals of comparing PNSH risk factors and clinical presentations with other sorts of spontaneous subarachnoid hemorrhages (SAH) and exhibit the PNSH outcome and prognosis.

METHODS

Retrospective review of patients who experienced SAH between May 2006 and July 2008 in the First Affiliated Hospital of Chongqing Medical University was undertaken. Patients were categorized as perimesencephalic nonaneurysmal subarachnoid hemorrhage (PNSH), nonperimesencephalic nonaneurysmal subarachnoid hemorrhage (NPNSH), aneurismal subarachnoid hemorrhage (ASH), and uncertain SAH of which the patterns were not clear. The possible risk factors and clinical presentations within the three groups were used to proceed for statistical analysis.

RESULTS

A total of 159 residents were identified. Among of them, 12 patients had the perimesencephalic pattern. Patients with PNSH showed less likelihood with the female (P=0.029), alcohol consumption (P=0.033), hypertensive (P=0.005), diabetes (P=0.013) or hyperlipidemia (P=0.034) when compared with aneurismal SAH. The clinical presentations of this pattern showed less conscious disturbance (P=0.004), vomiting (P=0.005), or poor Hunt & Hess Grade (P=0.003). There was one death among PNSH patients during 12 months mean follow-up.

CONCLUSIONS

Patients with PNSH present better clinical course than other forms of SAH, which could assist the diagnosis of this pattern. The moderate clinical course may suggest clinician apt to exclude aneurysm rupture. However, similar presents in remaining nonaneurysmal subarachnoid hemorrhage might suggest benign entities in other forms of nonaneurysmal subarachnoid hemorrhage.

CT angiography: current technology and clinical use

Since 1958, catheter angiography has assumed the role of gold standard for vascular imaging, despite the invasive nature of the procedure. Less invasive techniques for vascular imaging, such as computed tomographic angiography (CTA), have been developed and have matured in conjunction with developments in catheter arteriography. In a few cases, such as imaging, the aorta and the pulmonary arteries, CTA has supplanted catheter angiography as the gold standard. The expanding role of CTA emphasizes the need for deep, broad-based understanding of physical principles. This review describes CT hardware and associated software for angiography. The fundamentals of CTA physics are complemented with several clinical examples.

Aneurysmal subarachnoid hemorrhage diagnosis with computed tomographic angiography and OsiriX

PURPOSE

Recent advances in computed tomographic angiography (CTA) have resulted in its replacing digital subtraction angiography (DSA). However, CTA requires a powerful workstation and experienced technicians for image postprocessing. OsiriX, a free open-source medical imaging software with powerful three-dimensional (3D) capability, enables neurosurgeons to perform 3D rendering without extensive training. In this study, we examined the sensitivity and specificity of CTA with OsiriX as the primary diagnostic tool for intracranial aneurysms.

METHOD

From May 2006 to March 2009, 121 patients with spontaneous subarachnoid hemorrhage (SAH) underwent CTA. The CTA source images were 3D rendered by neurosurgeons using OsiriX. All the possible locations for aneurysms were carefully reviewed. DSA was performed on every patient in any of the following conditions: for negative CTA findings, after surgical clipping of aneurysms or before transarterial embolization of aneurysms.

RESULT

Of the 121 patients, 8 were excluded because DSA data were not available. In the remaining 113 patients, 20 patients had negative CTA findings. CTA with OsiriX detected 106 aneurysms in 93 patients, of which 103 were confirmed by DSA or postoperative DSA; 3 infundibular dilated pouches of small arteries were mistaken for aneurysms. Two anterior communicating artery aneurysms (1.5 mm and 1 mm) were missed by CTA from among all 113 patients. The sensitivity and specificity of CTA for detecting aneurysms on a per-patient basis were 98.9% and 100%, respectively. The sensitivity and specificity of CTA for detecting aneurysms on a per-aneurysm basis for detecting aneurysms were 98.1% and 86.3%, respectively.

CONCLUSION

CTA with OsiriX enables accurate detection of intracranial aneurysms. Cerebral DSA should be reserved for those patients with negative CTA findings.

Coronary artery segmentation using geometric moments based tracking and snake-driven refinement

Automatic or semi-automatic segmentation and tracking of artery trees from computed tomography angiography (CTA) is an important step to improve the diagnosis and treatment of artery diseases, but it still remains a significant challenging problem. In this paper, we present an artery extraction method to address the challenge. The proposed method consists of two steps: (1) a geometric moments based tracking to secure a rough centerline, and (2) a fully automatic generalized cylinder structure-based snake method to refine the centerlines and estimate the radii of the arteries. In this method, a new line direction based on first and second order geometric moments is adopted while both gradient and intensity information are used in the snake model to improve the accuracy. The approach has been evaluated on synthetic images as well as 8 clinical coronary CTA images with 32 coronary arteries. Our method achieves 94.7% overlap tracking ability within an average distance inside the vessel of 0.36 mm.

Negative CT angiography findings in patients with spontaneous subarachnoid hemorrhage: When is digital subtraction angiography still needed?

BACKGROUND AND PURPOSE

CTA is becoming the frontline modality to reveal aneurysms in patients with SAH. However, in about 20% of SAH patients no aneurysm is found. In these cases, intra-arterial DSA is still performed. Our aim was to evaluate whether negative findings on CTA can reliably exclude aneurysms in patients with acute SAH.

MATERIALS AND METHODS

We conducted a retrospective analysis of all negative findings on CTAs performed from 2005 to 2009 in patients with spontaneous SAH. Findings were compared with DSA. CTAs were performed with a 64-section multidetector row CT scanner.

RESULTS

One hundred ninety-three patients with SAH and negative findings on CTA who underwent subsequent DSA were identified. The distribution of blood on unenhanced CT was the following: PMH in 93 patients, diffuse aneurysmal pattern in 50, no blood on CT (xanthochromic LP) in 32, and peripheral sulcal distribution in 18. All patients with PMH had negative findings on DSA. One patient with no blood on CT had vasculitis on DSA. Six of 18 (33%) patients with peripheral blood had vasculitis on DSA. Three of these were also diagnosed by CTA. All except 1 patient with diffuse aneurysmal blood had negative findings on DSA. One patient was diagnosed with an aneurysm on DSA (1/50, 0.5%). Repeat delayed DSA performed in 28 of these patients revealed a small aneurysm in 4 (14%). Five patients had a complication of DSA (2.6%); 1 was a clinical stroke (0.5%).

CONCLUSIONS

In patients with SAH, negative CTA findings are reliable in ruling out aneurysms in the PMH pattern or no blood on CT. DSA is indicated in the diffuse aneurysmal pattern of SAH, and repeat delayed DSA is required if the initial DSA findings are negative. When the blood is peripheral, CTA should be scrutinized for vasculitis and DSA is recommended for confirmation.

Perimesencephalic nonaneurysmal subarachnoid hemorrhage caused by jugular venous occlusion: case report

OBJECTIVE

The cause of perimesencephalic nonaneurysmal subarachnoid hemorrhage remains unknown. We describe a patient in whom jugular venous occlusion preceded the occurrence of perimesencephalic nonaneurysmal subarachnoid hemorrhage. This finding supports the theory that the source of the hemorrhage is venous in origin.

CLINICAL PRESENTATION

A 25-year-old man presented with sudden onset of headache after his head was held in a headlock during a playful fight 48 hours before the ictus. His computed tomographic (CT) scan on admission demonstrated a perimesencephalic pattern of subarachnoid hemorrhage. CT angiography excluded the presence of an underlying aneurysm or vascular malformation but showed bilateral jugular venous obstruction with hematoma surrounding the right internal jugular vein. Magnetic resonance imaging and a 4-vessel cerebral angiogram confirmed the CT angiographic findings.

INTERVENTION

The patient was observed as an inpatient and had no complication of his hemorrhage. Follow-up at 5 months with CT angiography showed resolution of his neck hematoma and reopening of his internal jugular veins.

CONCLUSION

The presence of acute jugular venous occlusion as a cause of perimesencephalic nonaneurysmal subarachnoid hemorrhage supports a venous origin of hemorrhage.

Occurrence of perimesencephalic subarachnoid hemorrhage during pregnancy

BACKGROUND

Perimesencephalic subarachnoid hemorrhage (P-SAH) is a benign subset of subarachnoid hemorrhage with a favorable prognosis and low rate of re-bleeding. Risk factors may include hypertension and tobacco use, but it has not previously been reported during pregnancy.

METHODS

We report two cases of P-SAH in pregnant women, a 40-year-old female, 8-weeks pregnant and a 37-year-old female at 35 weeks gestational age.

RESULTS

CT scan confirmed P-SAH in both cases. CT angiography in one case and cerebral angiogram in the other did not reveal aneurysm or other potential bleeding source. The patients underwent transcranial Doppler ultrasound monitoring without evidence of vasospasm.

CONCLUSION

P-SAH hemorrhage may occur during early or late pregnancy. We do not propose an increased risk of P-SAH during pregnancy. The clinical course appears favorable and CT angiography alone may be considered the preferred diagnostic test to assess for aneurysm in first trimester pregnancy.

Recurrent perimesencephalic subarachnoid hemorrhage during antithrombotic therapy

INTRODUCTION

In patients with non-aneurysmal perimesencephalic hemorrhage, spontaneous rebleeding does not occur. The lack of reported recurrences may lead to less cautious administration of antithrombotic therapy.

METHODS

Case report.

RESULTS

A 57-year-old woman with a perimesencephalic pattern of hemorrhage and negative CT angiography was treated with carbasalate calcium and intravenous heparin because of an acute coronary syndrome. Three days after installment of this antithrombotic therapy she experienced a recurrent perimesencephalic hemorrhage leading to hydrocephalus and a decrease in consciousness. She died the same day as a result of ventricular fibrillation.

CONCLUSION

In the early phase after perimesencephalic hemorrhage, anticoagulant therapy may lead to rebleeding. The risks and benefits of antithrombotic therapy should be carefully weighed in patients with a perimesencephalic pattern of hemorrhage and negative CT angiography.

Does black blood MRA have a role in the assessment of intracerebral aneurysms?

The aim of this study was to assess whether the addition of a black blood (BB) sequence to standard three-dimensional time-of-flight (3D-TOF) imaging yields improved quantitative assessment of intracranial aneurysms. Thirty seven patients with 42 proven intracranial aneurysms underwent intra-arterial digital subtraction angiography, 3D-TOF and BB MRI imaging. This multimodality imaging was used to create a composite reference aneurysm description. The 3D-TOF and BB imaging were graded on a subjective seven-point scale to determine what improvement if any the addition of BB imaging yielded. Comparison of measurements from all imaging modalities demonstrated no significant difference (p < 0.01) in aneurysm length/width or parent vessel width. Aneurysm neck measurements were underestimated on 3D-TOF images although there was still a significant correlation (R(2) = 0.72, p < 0.05). Comparison of TOF and BB examinations to the composite reference using the Wilcoxon signed-rank test showed significant improvement in the demonstration of the aneurysm to parent/branch vessels and the morphology/size of the aneurysm neck, particularly in the setting of local haematoma or slow flow (p < 0.001). We propose the addition of the BB sequence as a useful adjunct to 3D-TOF imaging particularly when detailed aneurysm morphology is required or there is thrombus in subarachnoid space.

[Non-aneurysmal subarachnoid haemorrhage]

A subarachnoid haemorrhage (SAH) is frequent after a severe head injury. Traumatic-SAH is associated with a bad outcome and may induce cerebral vasospasm. There is no agreement on the treatment based on the amount of traumatic-SAH. Non-aneurysmal SAH accounts for 15% of all causes of non-traumatic SAH. There is a risk of cerebral vasospasm, although less frequent than after aneurysmal rupture. The improvement in imaging techniques has decreased the frequency of idiopathic SAH.

Detection of intracranial aneurysms with 64 channel multidetector row computed tomography: Comparison with digital subtraction angiography

PURPOSE

To compare the contribution of 64 channel multidetector row computed tomography angiography (64MDCT-angiography) with digital subtraction angiography (DSA) in the detection of intracranial aneurysms.

METHODS AND MATERIALS

Twenty-nine patients (10 males and 19 females, age: 40-84 years; average: 61.9 years) with clinical and imaging findings strongly suggesting the presence of subaracnoid hemorrhage underwent 64MDCT-angiography and DSA with a short interval between the two examinations (less than 12 h-5 days). CT parameters were: 64 mm x 0.5 mm collimation, pitch-0.828 and helical pitch-53. DSA were performed with standard technique (four vessel catheterization) and multiple projections. Axial CT scans as well as maximum intensity projection, volume rendering and multiplanar reformations and angiographic views were independently reviewed by four readers (two for 64MDCT-angiography and two for DSA). Consensus was reached for discordant cases. DSA was considered as the standard of reference.

RESULTS

In 29 patients, 28 aneurysms were found (14 patients had 1 aneurysm, 4 patients had 2 aneurysms and 2 patients had 3 aneurysms; in 9 patients no aneurysm were found). 64MDCT-angiography detected 26/28 aneurysms. No false-positive sites were recognized. The sensitivity, specificity, positive and negative predictive values and diagnostic accuracy were, respectively, 92.8, 100, 100, 99.4 and 99.5%.

CONCLUSIONS

64MDCT-angiography is helpful in detecting intracranial aneurysms with results similar to those of DSA but with less discomfort and risks for the patients and can be considered for the first line imaging technique. Conventional angiography is still needed in doubtful cases or negative MDCT-angiography associated with a strong clinical suspect.

Sixty-four-row multisection CT angiography for detection and evaluation of ruptured intracranial aneurysms: interobserver and intertechnique reproducibility

BACKGROUND AND PURPOSE

The purpose of this work was to assess intertechnique and interobserver reproducibility of 64-row multisection CT angiography (CTA) used to detect and evaluate intracranial aneurysms.

MATERIALS AND METHODS

From October 2005 to November 2006, 54 consecutive patients with nontraumatic subarachnoid hemorrhage (SAH) underwent both CTA and digital substraction angiography (DSA). Four radiologists independently reviewed CT images, and 2 other radiologists reviewed DSA images. Aneurysm diameter (D), neck width (N), and the presence of a branch arising from the sac were assessed.

RESULTS

DSA revealed 67 aneurysms in 48 patients and no aneurysm in 6 patients. Mean sensitivity and specificity of CTA for the detection of intracranial aneurysms were, respectively, 94% and 90.2%. For aneurysms less than 3 mm, CTA had a mean sensitivity of 70.4%. Intertechnique and interobserver agreements were good for the detection of aneurysms (mean kappa = 0.673 and 0.732, respectively) and for the measurement of their necks (mean kappa = 0.753 and 0.779, respectively). Intertechnique and interobserver agreements were excellent for the measurement of aneurysm diameters (mean kappa = 0.847 and 0.876, respectively). In addition, CTA was accurate in determining the N/D ratio of aneurysms and adjacent arterial branches. However, the N/D ratio was overestimated by all of the readers at CTA.

CONCLUSION

Sixty-four-row multisection CTA is an imaging method with a good interobserver reproducibility and a high sensitivity and specificity for the detection and the morphologic evaluation of ruptured intracranial aneurysms. It may be used as an alternative to DSA as a first-intention imaging technique in patients with SAH.