Cost-effectiveness of screening unruptured cerebral aneurysms in Japan

European Radiology -     

Computed angiotomography of unruptured cerebral aneurysms

Twenty-seven unruptured cerebral aneurysms in 25 patients were detected by computed angiotomography. A comparison of the computed angiotomographic features in common aneurysm sites with plain CT and conventional arteriography was carried out. An isodense, round cisternal defect and a calcification or high-density mass in the basal cisterns on plain CT are important findings suggestive of unruptured aneurysms larger than 7 mm in diameter. The identification of the aneurysm, as well as of the afferent and efferent arteries on computed angiotomography is essential for the direct diagnosis of smaller unruptured aneurysms related to the circle of Willis. This is possible in a number of cases when the aneurysms are relatively large. It appears that the aneurysm size must be larger than 3 mm in diameter to permit its recognition on the basis of angiotomography and the avoidance of false-positive findings.     

Endovascular strategy for unruptured cerebral aneurysms

The treatment of unruptured intracranial aneurysms (UIAs) remains complex and not clearly defined. While for ruptured intracranial aneurysms the management and the treatment option (surgery or endovascular treatment) are well defined by several trials, for asymptomatic UIAs the best management is still currently uncertain. The rationale to treat an UIA is to prevent the rupture and its consequent SAH and all complications derived from hemorrhage or reduce/eliminate neurological palsy. Although this statement is correct, the indication to treat an UIA should be based on a correct balance between the natural history of UIA and treatment risk. Patient's clinical history, aneurysm characteristics, and strategy management influence the natural history of UIAs and treatment outcomes. In the last 10 years and more, two important large multicenter studies were performed in order to analysis of all these factors and to evaluate the best treatment option for UIAs. The aim of this paper is to try to synthesize the possible indications to the endovascular treatment (EVT), when and how to treat an UIA.     

Cost-effectiveness of treatment of unruptured intracranial aneurysms in patients with a history of subarachnoid hemorrhage

RATIONALE AND OBJECTIVES: The study goal was to evaluate the cost-effectiveness of surgery and endovascular treatment of unruptured intracranial aneurysms in patients with a history of subarachnoid hemorrhage from a previous aneurysm, incorporating the results of the prospective International Study of Unruptured Intracranial Aneurysms. MATERIALS AND METHODS: Using a Markov model, we performed a decision and cost-effectiveness analysis comparing surgery or endovascular treatment with no treatment. Twelve clinical scenarios were defined based on aneurysm size and location. Probabilistic sensitivity analyses were performed for 50- and 40-year-old cohorts. Treatment was considered to be cost-effective at an incremental cost-effectiveness ratio less than $100,000 per quality-adjusted life-year. RESULTS: In 50-year-old patients, no treatment was the most cost-effective strategy for aneurysms located in the cavernous carotid artery. For aneurysms less than 7 mm located in the anterior circulation, no treatment was the most cost-effective strategy. Endovascular treatment was the most cost-effective option for 7- to 24-mm aneurysms, whereas surgery was the most cost-effective option for aneurysms of 25 mm or larger. For aneurysms less than 7 mm and located in the posterior circulation, endovascular treatment was the most cost-effective option, whereas surgery was the most cost-effective option for 7- to 12-mm aneurysms. No treatment was the most cost-effective strategy for aneurysms of 13 mm or larger. CONCLUSION: For 50-year-old patients with a history of aneurysmal subarachnoid hemorrhage, treatment of unruptured aneurysms that are located in the cavernous carotid artery, or small (<7 mm) and located in the anterior circulation, or large (>or=13 mm) and located in the posterior circulation is ineffective or not cost-effective.     

未破裂脑动脉瘤血管内治疗的安全性及影像学结果

目的　观察未破裂脑动脉瘤血管内治疗后的安全性及影像学结果。方法　将可解脱弹簧圈栓塞未破裂脑动脉瘤 (必要时支架或球囊辅助 ) ,去除可能的出血因素。结果　 5 7例共 6 5个未破裂动脉瘤 ,5 2个致密栓塞 ,12个栓塞程度大于 90 % ,1个栓塞程度少于 90 %。血管造影随访 (6～ 36个月 ) ,30个致密栓塞 2 9个仍稳定 ,1个动脉瘤再生长 ;11个栓塞程度大于 90 %中 1个完全消失 ,7个稳定 ,3个再生长 ;1个栓塞程度少于 90 %的再生长。结论　未破裂脑动脉瘤血管内治疗是必要的也是安全的方法 ,致密栓塞的影像学结果更好 ,长期疗效需进一步的随访观察。     

Aneurysmal wall enhancement and perianeurysmal edema after endovascular treatment of unruptured cerebral aneurysms

Introduction

Perianeurysmal edema and aneurysm wall enhancement are previously described phenomenon after coil embolization attributed to inflammatory reaction. We aimed to demonstrate the prevalence and natural course of these phenomena in unruptured aneurysms after endovascular treatment and to identify factors that contributed to their development.

Methods

We performed a retrospective analysis of consecutively treated unruptured aneurysms between January 2000 and December 2011. The presence and evolution of wall enhancement and perianeurysmal edema on MRI after endovascular treatment were analyzed. Variable factors were compared among aneurysms with and without edema.

Results

One hundred thirty-two unruptured aneurysms in 124 patients underwent endovascular treatment. Eighty-five (64.4 %) aneurysms had wall enhancement, and 9 (6.8 %) aneurysms had perianeurysmal brain edema. Wall enhancement tends to persist for years with two patterns identified. Larger aneurysms and brain-embedded aneurysms were significantly associated with wall enhancement. In all edema cases, the aneurysms were embedded within the brain and had wall enhancement. Progressive thickening of wall enhancement was significantly associated with edema. Edema can be symptomatic when in eloquent brain and stabilizes or resolves over the years.

Conclusions

Our study demonstrates the prevalence and some appreciation of the natural history of aneurysmal wall enhancement and perianeurysmal brain edema following endovascular treatment of unruptured aneurysms. Aneurysmal wall enhancement is a common phenomenon while perianeurysmal edema is rare. These phenomena are likely related to the presence of inflammatory reaction near the aneurysmal wall. Both phenomena are usually asymptomatic and self-limited, and prophylactic treatment is not recommended.     

Endovascular treatment of unruptured intracranial aneurysms

BACKGROUND AND PURPOSE: Intracranial aneurysms are common, with an overall frequency ranging from 0.8% to 10%. Because prognosis after subarachnoid hemorrhage is still very poor, treatment of unruptured aneurysms, either neurosurgically or endovascularly, has been advocated. However, risk of rupture and subsequent subarachnoid hemorrhage needs to be considered against the risks of elective treatment. We analyzed the technical feasibility, safety, and efficacy of endovascular treatment of a consecutive series of unruptured cerebral aneurysms. METHODS: From July 1997 through December 2000, a total of 76 patients with 82 unruptured cerebral aneurysms were treated at our institution. Endovascular treatment was administered to 39 consecutive patients with a total of 42 unruptured cerebral aneurysms. Thirty-six aneurysms were treated with an endovascular technique; in six patients, the parent artery was occluded to eliminate aneurysmal perfusion. Aneurysms were located either in the anterior (n = 31) or posterior (n = 11) circulation. Eight patients had experienced previous subarachnoid hemorrhage from other aneurysms and were treated electively after complete rehabilitation. Ten patients had neurologic symptoms; in 21 patients, the aneurysm was an incidental finding. Eighteen aneurysms were small (0-5 mm), 11 were medium (6-10 mm), nine were large (11-25 mm), and four were giant (> 25 mm). Occlusion rate was categorized as complete (100%), subtotal (95-99%), and incomplete (< 95%) obliteration. RESULTS: Endovascular treatment was technically feasible for 38 of 42 aneurysms. Complete (100%) or nearly complete (95-99%) occlusion was achieved in 34 of 38 aneurysms. In four aneurysms of the internal carotid artery, only incomplete (< 95%) occlusion was achieved. All patients except one with mild neurologic deficits according to the Glasgow Outcome Scale and one with mild memory dysfunction but no focal neurologic deficit achieved good recovery, resulting in a morbidity rate of 4.8% and a mortality rate of 0%. CONCLUSION: Endovascular embolization of unruptured cerebral aneurysms is an effective therapeutic alternative to neurosurgical clipping and is associated with low morbidity and mortality rates. For the management of unruptured aneurysms, endovascular treatment should be considered.     

MR angiography and surgery for unruptured familial intracranial aneurysms in persons with a family history of cerebral aneurysms.

OBJECTIVE: We used MR angiography to determine prevalence of unruptured familial intracranial aneurysms in a prepaid medical care program. We compared surgical outcomes and the cost of treating unruptured versus ruptured aneurysms. We compared the cost of MR angiography with the cost of screening mammography and with the cost of surgically treating a ruptured aneurysm. SUBJECTS AND METHODS: During a 30-month period, we performed MR angiography to show cerebral aneurysms in 63 surgical candidates who had one or more first-degree relatives with an aneurysm. Unruptured aneurysms seen on MR angiography were evaluated by digital subtraction angiography (DSA) and treated surgically. RESULTS: MR angiography showed nine unruptured aneurysms in six patients. Eight aneurysms were seen on MR angiography and nine were seen on DSA. Seven unruptured aneurysms were treated surgically. The mean treatment cost was 50% lower for an unruptured aneurysm than that for a ruptured aneurysm. No patient surgically treated for an unruptured aneurysm required rehabilitation, unlike 25% of patients with ruptured aneurysms. The annual total cost of MR angiography was equivalent to 2.9% of the annual cost of screening mammography. The annual cost of MR angiography equaled half the cost of treating one patient after aneurysm rupture. CONCLUSION: MR angiography showed a 9.5% prevalence of unruptured aneurysms among persons who had one or more first-degree relatives with a cerebral aneurysm. DSA confirmed 88% of aneurysms found on MR angiography. Persons with unruptured aneurysms had better treatment outcomes at lower cost than did patients treated for aneurysm rupture. The annual MR angiography cost was low compared with the cost of screening mammography and with the cost of treating one patient with aneurysm rupture.     

颅内未破动脉瘤的研究进展

未破裂颅内动脉瘤(UIA)是指没有破裂史或者与以前出血没有关系的颅内动脉瘤,包括偶然发现的动脉瘤和多发动脉瘤中未破裂的动脉瘤.UIA不管是自然破裂还是手术处理,均存在较大风险.目前,随着影像技术(特别是无创性影像技术)的发展和健康查体意识的提高,越来越多的UIA被发现,选择保守观察还是手术处理,对于患者本身、神经内外科、介入科、影像科医师,都是一个非常棘手的问题.本文将对近年来国内外专家学者在该领域的研究成果进行综述.     

Treatment of unruptured aneurysms with GDCs: clinical experience with 247 aneurysms

BACKGROUND AND PURPOSE: The GDC system is a valuable therapeutic alternative to surgical treatment of intracranial aneurysms. We present our clinical experience with the GDC technique used to treat unruptured cerebral aneurysms. METHODS: This is a retrospective review of 217 patients with 247 unruptured intracranial aneurysms who underwent embolization with GDCs between August 1991 and June 2000. One hundred sixty-seven of the 217 were female patients. Patient age ranged from 13 to 83 years. In 118 patients, the aneurysms were found when unrelated non-neurologic conditions indicated angiography, CT angiography, or MR angiography (group 1). Fifty-one patients with mass effect symptoms comprised group 2, 12 patients with aneurysms associated with arteriovenous malformations or tumors of the brain comprised group 3, 17 patients with unruptured aneurysms treated during the chronic phase of subarachnoid hemorrhage (SAH) comprised group 4, and 19 patients treated during the acute phase of SAH due to another ruptured aneurysm comprised group 5. RESULTS: Angiographic results revealed complete occlusion in 138 of 247 aneurysms (55.9%), neck remnants in 92 (37.2%), and incomplete occlusion in three (1.2%). GDC embolization was attempted unsuccessfully in 14 aneurysms (5.7%). Of the 198 patients without acute SAH (groups 1-4), 186 (93.9%) of 198 remained neurologically unchanged. Eleven of the 217 patients (5.1%) experienced neurologic deterioration caused by immediate procedural complications. One patient died (0.5%) as a result of aneurysmal rupture during embolization. For asymptomatic patients and those treated after the chronic period of SAH, the mean hospitalization stay was 2.9 days. CONCLUSION: GDC technology constitutes safe treatment for unruptured aneurysms, with successful anatomic and clinical results and low complication rates achieved.     

Inflow hemodynamics evaluated by using four-dimensional flow magnetic resonance imaging and the size ratio of unruptured cerebral aneurysms

Purpose

Prediction of the rupture risk is critical for the identification of unruptured cerebral aneurysms (UCAs) eligible for invasive treatments. The size ratio (SR) is a strong morphological predictor for rupture. We investigated the relationship between the inflow hemodynamics evaluated on four-dimensional (4D) flow magnetic resonance (MR) imaging and the SR to identify specific characteristics related to UCA rupture.

Methods

We evaluated the inflow jet patterns and inflow hemodynamic parameters of 70 UCAs on 4D flow MR imaging and compared them among 23 aneurysms with an SR ≧2.1 and 47 aneurysms with an SR ≦2.0. Based on the shape of inflow streamline bundles with a velocity ≧75% of the maximum flow velocity in the parent artery, the inflow jet patterns were classified as concentrated (C), diffuse (D), neck-limited (N), and unvisualized (U).

Results

The incidence of patterns C and N was significantly higher in aneurysms with an SR ≧2.1. The rate of pattern U was significantly higher in aneurysms with an SR ≦2.0. The maximum inflow rate and the inflow rate ratio were significantly higher in aneurysms with an SR ≧2.1.

Conclusions

The SR affected the inflow jet pattern, the maximum inflow rate, and the inflow rate ratio of UCAs. In conjunction with the SR, inflow hemodynamic analysis using 4D flow MR imaging may contribute to the risk stratification for aneurysmal rupture.

     

Cost-effectiveness of colorectal cancer screening

PURPOSE: To determine the most cost-effective colorectal cancer screening strategy costing less than $100,000 per life-year saved and to determine how available strategies compare with each other. MATERIALS AND METHODS: Standardized methods were used to calculate incremental cost-effectiveness ratios (ICERs) from published estimates of cost and effectiveness of colorectal cancer screening strategies, and the direction and magnitude of any effect on the ratio from parameter estimate adjustments based on literature values were estimated. RESULTS: Strategies in which double-contrast barium enema examination was performed emerged as optimal from all studies included. In average-risk individuals, screening with double-contrast barium enema examination every 3 years, or every 5 years with annual fecal occult blood testing, had an ICER of less than $55,600 per life-year saved. However, double-contrast barium enema examination screening every 3 years plus annual fecal occult blood testing had an ICER of more than $100,000 per life-year saved. Colonoscopic screening had an ICER of more than $100,000 per life-year saved, was dominated by other screening strategies, and offered less benefit than did double-contrast barium enema examination screening. CONCLUSION: Double-contrast barium enema examination can be a cost-effective component of colorectal cancer screening, but further modeling efforts are necessary.     

Cost-effectiveness of whole-body CT screening

PURPOSE: To make preliminary estimates of the effectiveness (in life-years) and cost-effectiveness (in costs per life-year) of whole-body computed tomographic (CT) screening. MATERIALS AND METHODS: Costs and effectiveness (in life-years) of onetime whole-body CT screening relative to those of no screening were calculated by using a decision-analytic model. It was assumed that any benefits from screening were due to earlier detection of disease and improvement in survival relative to survival with routine care. Eight conditions were included in the model: ovarian, pancreatic, lung, liver, kidney, and colon cancer; abdominal aortic aneurysm; and coronary artery disease. Costs of the screening examination, follow-up tests, and patient care were estimated. The base-case analysis was performed for a hypothetical cohort of 500 000 self-referred asymptomatic 50-year-old men. For sensitivity analyses, the age and sex of the cohort were varied. Results were expressed in 2001 U.S. dollars per life-year gained. RESULTS: Compared with routine care, whole-body CT screening provided minimal gains in life expectancy (0.016 6 years or 6 days) at an average additional cost of 2513 dollars per patient, or an incremental cost-effectiveness ratio of 151 000 dollars per life-year gained. Most patients (90.8%) had at least one positive finding, but only 2.0% had disease; work-up in patients with a false-positive result of screening accounted for 32.3% of total costs (1720 dollars of 5332 dollars). Results were sensitive to the prevalence of disease, the effect of screening on stage of disease at diagnosis, the specificity of screening, and the costs of follow-up for false-positive findings. CONCLUSION: Even with assumptions favorable to whole-body CT, implementation of onetime screening would not be cost-effective compared with currently funded medical interventions; follow-up for false-positive findings would add a substantial financial burden to the health care system.     

Treatment of unruptured intracranial aneurysms: decision and cost-effectiveness analysis

PURPOSE: To prospectively perform a decision and cost-effectiveness analysis of surgical and endovascular treatments of unruptured intracranial aneurysms, with incorporation of the results of the prospective International Study of Unruptured Intracranial Aneurysms. MATERIALS AND METHODS: With use of a Markov model, a decision and cost-effectiveness analysis was performed for comparison of surgical or endovascular treatment with no treatment. Twelve clinical scenarios were defined on the basis of aneurysm size and location. Probabilistic sensitivity analyses were performed for 50- and 40-year-old patient cohorts. Treatment was considered to be cost-effective at an incremental cost-effectiveness ratio less than $100,000 per quality-adjusted life-year. RESULTS: In 50-year-old patients, no treatment was the most cost-effective strategy for aneurysms located in the cavernous carotid artery. For aneurysms smaller than 7 mm located in the anterior circulation, no treatment was the most cost-effective strategy. Endovascular treatment was the most cost-effective option for 7-24-mm aneurysms, whereas surgical treatment was the most cost-effective option for aneurysms 25 mm or larger. For aneurysms smaller than 7 mm or 25 mm or larger located in the posterior circulation, no treatment was the most cost-effective strategy. Surgical treatment was the most cost-effective option for 7-12-mm aneurysms, whereas endovascular treatment was the most cost-effective option for 13-24-mm aneurysms. CONCLUSION: For 50-year-old patients, treatment of aneurysms that are small (<7 mm), that are located in the cavernous carotid artery, or that are large (>or=25 mm) and located in the posterior circulation is ineffective or not cost-effective.     

The learning curve for coil embolization of unruptured intracranial aneurysms

BACKGROUND AND PURPOSE: Several studies have shown that procedural outcomes are better at high-volume institutions, possibly due to greater physician experience (learning) or practice (repetition). Our purpose was to determine whether outcomes for coil embolization improved with the experience of the practitioner, after adjusting for the perceived risk of treatment. METHODS: We identified all unruptured aneurysms treated with coil embolization at our institution from 1990 through 1997. A clinical nurse specialist abstracted the characteristics from cases that met the entry criteria. Two neurologists independently determined the complications by using definitions established a priori. The influence of experience of the treating-physician on complications was evaluated with univariate and multivariable logistic regression analyses. RESULTS: Sixteen complications occurred in 94 patients (17%) treated with coil embolization. Complications occurred in 53% of the first five cases that each of three physicians treated, and in 10% of later cases (P <.001). After an adjustment for all other predictors, including physician assessment of the risk of the procedure, the odds of a complication decreased with increasing physician experience (odds ratio, 0.69 for every five cases treated; 95% confidence interval: 0.50, 0.96; P=.03). CONCLUSION: The risk of complications with coil embolization of unruptured aneurysms appears to decrease dramatically with physician experience. Because the physicians in this study were highly experienced in other endovascular techniques at study onset, the rate of learning may not be generalizable to other centers.     

Endovascular treatment of unruptured intracranial aneurysms and circulating endothelial cells

Objectives

To evaluate the potential implication of circulating endothelial cells (CECs) in complications following endovascular treatment (EVT) of unruptured intracranial aneurysms. CECs characterized as CD146⁺/CD105⁺/CD45⁻/DAPI⁺ were considered to originate from an altered endothelial cell layer of the vessel wall.

Study design

In 15 patients, CECs were characterized and enumerated by the CellTracks^® System in blood samples from: (1) femoral artery (FA), (2) internal carotid artery (ICA) before (ICA₁) and after procedure (ICA₂), and (3) a peripheral vein before (PV₁) and after EVT (PV₂). Ischemic brain events were assessed using diffusion weighted imaging (DWI-MRI) before and 24 h after EVT.

Results

In ICA₁, the median number of single CECs and clusters of 2–5 CECs were higher than in FA, ICA₂, PV₁ and PV₂ samples (P < 0.001). Clusters >5 cells, sometimes >50 μm, were mainly observed in ICA₁ and never in PV₁, PV₂ or PV samples from ten healthy subjects. This distribution of CECs suggested femoral and ICA injury by the devices used, leading to endothelium shearing and desquamation of CECs. All patients discharged on day two (NIHSS score = 0), however silent ischemic brain lesions were observed in 9/15 (60%).

Conclusions

EVT detaches single and clusters of CECs from wall arteries that may be implicated in silent ischemic brain lesions genesis. Enumeration of CECs associated with DWI-MRI might represent an interesting strategy for monitoring and optimizing endovascular devices, and further limit EVT-related complications.