脑动静脉畸形的MRA诊断技术及诊断价值

目的：回顾性分析脑动静脉畸形（AVM）的MRA诊断方法厦诊断价值。方法：51例AVM病人,男30人,女21人,年龄为9—66岁。均进行MR平扫压3D—TOFMBA或3D—PCMBA扫描。结果：删能清晰显示瘤巢压AVM的继发改变,MBA可基本显示AVM的全貌。结论：船认是诊断AVM的有效方法,但常需结合DSA。     

C T、常规MRI 序列和SWI 诊断弥漫性轴索脑损伤比较

目的:探讨弥漫性轴索损伤(DAI)的CT、常规MRI序列和磁敏感加权成像(SWI)表现与诊断价值。方法:回顾分析42例DAI患者的影像资料,分析、比较CT、MRI和SWI的信号特征及脑内病灶显示率。结果:SWI显示病灶最多、最敏感;脑CT扫描次之;常规MRI序列敏感性差,只有部分病灶显示。结论:CT、MRI和SWI对DAI早期诊断、治疗及评价预后具有重要参考价值,SWI是诊断DAI最有效的首选影像学检查方法。     

磁共振血管造影对颈部静脉系统疾病诊断的应用价值

目的：探讨三维动态增强磁共振血管成像（30 DCE MRA）对于颈部静脉系统疾病的临床应用价值。方法：对7例疑有颈部静脉病变的病人进行了3D DCE MRA检查,观察对病变血管及正常血管显示情况。结果：7例检查图像都能清晰显示正常血管结构及病变情况。其中2例正常,2例颈静脉血栓,1例颈静脉癌栓,1例颈静脉扩张,2例动静脉瘘。所有病例均经手术及（或）DSA证实。结论：3D DCE MRA是一种简便,易行,有效的血管检查方法,分辨率高,假阳性率低,在临床上已广泛应用,但临床上多限于动脉系统疾病的诊断。只要选择合适的序列、扫描时间及对比剂的剂量就能较好显示静脉血管情况。此项技术的应用,在颈部静脉病变诊断中有很大的实用价值。     

头颅电子计算机断层扫描血管造影和头颅磁共振血管成像在颅内动脉瘤中诊断价值比较的回顾性研究

摘要 目的：研究对比头颅电子计算机断层扫描血管造影（CTA）和头颅磁共振血管成像（MRA）在颅内动脉瘤中诊断价值。方法：回顾性分析医院2019年1月2日～2020年12月15日收治的60例疑似颅内动脉瘤患者资料,所有受试者均开展头颅CTA检查、MRA检查以及数字减影血管造影（DSA）检查。以DSA检查结果为金标准,比较头颅CTA和头颅MRA诊断颅内动脉瘤的效能。此外,对比头颅CTA和头颅MRA诊断不同分级、不同部位颅内动脉瘤的符合率。结果：DAS检查结果显示确诊动脉瘤患者48例,共检出动脉瘤74个,CTA检出动脉瘤65个,MRA检出动脉瘤51个,CTA动脉瘤检出率高于MRA检出率（均P＜0.05）。以DSA结果为金标准,CTA诊断颅内动脉瘤的灵敏度、特异度以及准确度分别为94.20%（65/69）、60.00%（3/5）、91.89%（68/74）,均高于MRA的82.26%（51/62）、41.67%（5/12）、75.68%（56/74）（均P＜0.05）。CTA诊断1级颅内动脉瘤的符合率为13.85%（9/65）,高于MRA的7.84%（4/51）（P＜0.05）。各种检查方式诊断不同部位颅内动脉瘤的符合率对比均无明显差异（均P＞0.05）。结论：CTA诊断颅内动脉瘤的灵敏度、特异度以及准确度均高于MRA,可提高对小直径肿瘤的检出率。然而,MRA具有无辐射、检测费用少、安全性高等优势,临床实际工作中可综合选择合理的检查方式。     

CT、常规MRI序列和SWI诊断弥漫性轴索脑损伤比较

目的：探讨弥漫性轴索损伤（DAI）的CT、常规MRI序列和磁敏感加权成像（SWI）表现与诊断价值。方法：回顾分析42例DAI患者的影像资料,分析、比较CT、MRI和SWI的信号特征及脑内病灶显示率。结果：SWI显示病灶最多、最敏感;脑CT扫描次之;常规MRI序列敏感性差,只有部分病灶显示。结论：CT、MRI和SWI对DAI早期诊断、治疗及评价预后具有重要参考价值,SWI是诊断DAI最有效的首选影像学检查方法。     

64排CT血管造影在脑动静脉畸形诊断中的价值

目的：探讨64排CT血管造影（computedtomography angiographycTA）对脑动静脉畸形（cerebral arefiovenousmalformation,AVM）的诊断价值。方法：16例AVM患者,均行64排螺旋CT血管造影检查,使用多种重建方法,由两名有经验的医生对畸形血管团进行分析。结果：16例均为单发瘤巢,16例AVM均显示了大小不等的畸形血管团及供血动脉和引流静脉,其中,2例同时伴脑出血（12．5％）,3例有出血后软化灶形成（18．75％）,16例发现有供血动脉31支,16例发现有明确的引流静脉21支。结论：64排CTA安全．快速．结合多种重建方法．可以清晰显示AVM的供血动脉、瘤巢．引流静脉．为临床治疗提供了可靠的信息．     

MRI检查在肝门部胆管癌诊断中的应用

目的:评价MR平扫、MRCP、DWI序列及MR动态增强扫描等不同MR检查方法对肝门部胆管癌的诊断价值。方法:回顾性分析经手术及病理证实的9例肝门部胆管癌在上述不同MRI检查方法中所显示的影像特征,提高对肝门部胆管癌的诊断认识。结论:肝门部胆管癌在MRI平扫上表现为边界不清的等、稍长T1信号稍高T2混杂信号团块,MRCP可明确显示肝门区肝管狭窄、截断征象,远侧肝管的显著扩张,DWI序列病灶表现为扩散受限稍高信号,MR动态增强扫描动脉期病变表现为不强化或轻度强化,程度不一的延迟强化较具特征性,同时增强MR对胆管壁和邻近肝实质的侵犯、血管侵犯以及肝门、腹膜后淋巴结转移有明显的诊断价值。合理选择上述多种MRI检查方法结合临床胆管癌相关抗原、CA19-9检测能对大多数肝门部胆管癌做出正确诊断,对疾病的诊断、分型、临床治疗路径选择具有重要价值。     

对比剂动力学时间分辨成像及弥散加权成像技术活体动态监测兔VX2肌肉肿瘤生物学生长与血管生成

目的:应用对比剂动力学时间分辨成像(Time Resolved Imaging of Contrast Kinetics,TRICKS)技术增强磁共振血管成像(MRangiography,MRA)及弥散加权成像(Diffusion Weighted Imaging,DWI)技术活体动态监测兔VX2肌肉肿瘤生物学生长与血管生成,探讨肿瘤血管生成与肿瘤生长的关系。方法:30只新西兰白兔,每只均在右后腿肌肉内接种VX2肿瘤细胞1×107建立肿瘤模型。分别在肿瘤接种后第4、7、10、13、16天(每个时间点6只)分别进行T1WI、T2WI、DWI、TRICKS动态增强MRA及T1WI增强延迟扫描,活体监测兔VX2肌肉肿瘤血管生成,肿瘤标本HE及CD31免疫组化染色进行验证。两位医师双盲法分别测量不同生长点肿瘤的长、短径及体积,并与大体病理标本比较;测定TRICKS增强动态MRA所能显示肿瘤血管的最小直径及形态变化;观察ADC值变化与肿瘤生长的关系。结果(:1)ADC值随着肿瘤体积的长大而逐渐增大。(2)MRI活体测定肿瘤大小与病理大体标本所测算肿瘤体积的差异无显著性。(3)TRICKS增强MRA动态显示肿瘤血管的最小...     

CT灌注、MR灌注和DWI成像综合应用在肝脏疾病的诊断价值

目的:探讨CT、MR几种功能成像(包括CT灌注、MR灌注和DWI成像)综合应用在肝脏疾病的诊断价值。方法:37例常规CT和/或MR诊断信心不足的患者,补充进行了DWI成像、CT和MR灌注成像以辅助诊断。其中,18例为肝癌术后或TACE、RFA、PEI等方法治疗后,对肝脏复发或原病灶治疗后活性情况的判断;7例为对肝内多发病灶的检出及诊断;4例肝脓肿;肝腺瘤3例,FNH5例。结果:37例患者在结合了功能成像后做出的综合影像诊断,较单纯常规CT和/或MR扫描,诊断准确率和病灶检出率均有提高。7例肝癌术后患者,常规平扫及增强扫描对术区是否有有活性的肿瘤残存还是局部复发诊断困难,DWI成像诊断为术后的炎性增生或肝脏局限性灌注异常。后患者经随访3-6个月,一般状况和生化指标无明显异常,且影像表现基本无变化。11例原发性肝癌TACE、RFA、PEI等方法治疗后的患者,CT和/或MR常规平扫及增强扫描可疑病灶仍有部分活性区但不能确定,加扫了DWI成像,其中的7例进行了MR灌注成像,6例进行了CT灌注成像。经ADC值以及灌注值的评估,病灶坏死区和残留活性区的区分更加明确。7例肝内多发病灶的患者,DWI图像较MR常规扫描检出病灶数目多且病灶显示更为清晰;4例肝脓肿、3例肝腺瘤,5例FNH患者常规CT/MR表现不典型,未能明确良恶性诊断,经DWI和灌注扫描均获明确定性,3例肝脓肿经超声导引下肝穿刺证实,2例肝腺瘤和3例FNH经受术证实,其余病例经临床及影像随访证实。结论:功能成像作为常规扫描的有益补充,其诊断价值不容忽视,可以提高病灶检出率和诊断准确率。     

鞍旁海绵状血管瘤的MRI诊断及误诊分析

目的:分析鞍旁海绵状血管瘤MR影像特点及误诊原因,提高对该疾病的诊断及鉴别诊断水平。方法:收集我院经手术病理证实的13例鞍旁海绵状血管瘤,术前均行MRI平扫及增强扫描,5例行3D-ASL检查,分析其影像学资料。结果:9例表现为横向哑铃状,鞍旁大,鞍内小,病灶主体位于颈内动脉外侧,颈内动脉海绵窦段被病灶包绕;1例鞍旁与鞍内病灶大小相似,1例病灶主体位于颈内动脉内侧,2例病灶完全位于颈内动脉外侧;7例垂体显示不清,6例垂体受推移;6例T2W I表现为类似脑脊液的极高信号;仅5例行3D-ASL检查,病灶均呈低灌注。误诊9例,其中4例误诊垂体腺瘤,5例误诊脑膜瘤。结论:横向哑铃状、病灶主体位于颈内动脉外侧及T2W I类似脑脊液的极高信号是鞍旁海绵状血管瘤的典型影像特征。对于不典型病变,借助3D-ASL可以减少误诊,充分掌握MRI影像特征及鉴别诊断的要点,对提高临床术前诊断水平具有重要价值。     

Value of DSA in the Diagnostic Workup of Pulsatile Tinnitus

ObjectivesPulsatile tinnitus (PT) is a rare complaint, but can be a symptom of life-threatening disease. It is often caused by vascular pathologies, e.g. dural arteriovenous fistula (dAVF), arteriovenous malformation (AVM) or vascularized tumors. The current diagnostic pathway includes clinical examination, cranial MRI and additional DSA. The aim of this study was to evaluate the diagnostic impact of DSA in the diagnostic workup of patients with PT in comparison to MRI alone.MethodsRetrospectively, 54 consecutive patients with pulsatile tinnitus were evaluated. All patients had a diagnostic workup including cranial MRI and DSA. MRI examinations were blinded to the results of DSA and retrospectively analyzed in consensus by two experienced neuroradiologists. The MR-examinations were evaluated for each performed sequence separately: time-of-flight-angiography, ce-MRA, T2, ce-T1-sequence and ce-T1-sequence with fat saturation.Results37 of the 54 patients revealed a pathology explaining PT on MRI, which was detected by the readers in 100% and proofed by means of DSA. 24 dAVF, four paraganglioma, two AVM and seven more pathologies were described. All patients without pathology on MRI did also not show any pathology in DSA.ConclusionsMR imaging is sufficient to exclude pathology in patients with pulsatile tinnitus.     

Diagnostic Accuracy of Computer Tomography Angiography and Magnetic Resonance Angiography in the Stenosis Detection of Autologuous Hemodialysis Access: A Meta-Analysis

Purpose

To compare the diagnostic performances of computer tomography angiography (CTA) and magnetic resonance angiography (MRA) for detection and assessment of stenosis in patients with autologuous hemodialysis access.

Materials and Methods

Search of PubMed, MEDLINE, EMBASE and Cochrane Library database from January 1984 to May 2013 for studies comparing CTA or MRA with DSA or surgery for autologuous hemodialysis access. Eligible studies were in English language, aimed to detect more than 50% stenosis or occlusion of autologuous vascular access in hemodialysis patients with CTA and MRA technology and provided sufficient data about diagnosis performance. Methodological quality was assessed by the Quality Assessment of Diagnostic Studies (QUADAS) instrument. Sensitivities (SEN), specificities (SPE), positive likelihood ratio (PLR), negative likelihood values (NLR), diagnostic odds ratio (DOR) and areas under the receiver operator characteristic curve (AUC) were pooled statistically. Potential threshold effect, heterogeneity and publication bias was evaluated. The clinical utility of CTA and MRA in detection of stenosis was also investigated.

Result

Sixteen eligible studies were included, with a total of 500 patients. Both CTA and MRA were accurate modality (sensitivity, 96.2% and 95.4%, respectively; specificity, 97.1 and 96.1%, respectively; DOR [diagnostic odds ratio], 393.69 and 211.47, respectively) for hemodialysis vascular access. No significant difference was detected between the diagnostic performance of CTA (AUC, 0.988) and MRA (AUC, 0.982). Meta-regression analyses and subgroup analyses revealed no statistical difference. The Deek’s funnel plots suggested a publication bias.

Conclusion

Diagnostic performance of CTA and MRA for detecting stenosis of hemodialysis vascular access had no statistical difference. Both techniques may function as an alternative or an important complement to conventional digital subtraction angiography (DSA) and may be able to help guide medical management.     

The Added Diagnostic Value of Dynamic Contrast-Enhanced MRI at 3.0 T in Nonpalpable Breast Lesions

Objective

To investigate the added diagnostic value of 3.0 Tesla breast MRI over conventional breast imaging in the diagnosis of in situ and invasive breast cancer and to explore the role of routine versus expert reading.

Materials and Methods

We evaluated MRI scans of patients with nonpalpable BI-RADS 3–5 lesions who underwent dynamic contrast-enhanced 3.0 Tesla breast MRI. Initially, MRI scans were read by radiologists in a routine clinical setting. All histologically confirmed index lesions were re-evaluated by two dedicated breast radiologists. Sensitivity and specificity for the three MRI readings were determined, and the diagnostic value of breast MRI in addition to conventional imaging was assessed. Interobserver reliability between the three readings was evaluated.

Results

MRI examinations of 207 patients were analyzed. Seventy-eight of 207 (37.7%) patients had a malignant lesion, of which 33 (42.3%) patients had pure DCIS and 45 (57.7%) invasive breast cancer. Sensitivity of breast MRI was 66.7% during routine, and 89.3% and 94.7% during expert reading. Specificity was 77.5% in the routine setting, and 61.0% and 33.3% during expert reading. In the routine setting, MRI provided additional diagnostic information over clinical information and conventional imaging, as the Area Under the ROC Curve increased from 0.76 to 0.81. Expert MRI reading was associated with a stronger improvement of the AUC to 0.87. Interobserver reliability between the three MRI readings was fair and moderate.

Conclusions

3.0 T breast MRI of nonpalpable breast lesions is of added diagnostic value for the diagnosis of in situ and invasive breast cancer.     

Magnetic resonance imaging and ultrasound study in the diagnosis og facial angiodysplasias in children: competition or collaboration?

This study deals with the capacities of noninvasive magnetic resonance imaging (MRI) with magnetic resonance angiography (MRA) without administration of magnetic resonance contrast substances in the diagnosis of facial soft tissue angiodysplasias in children. Indications for their use are defined. The methodology of the studies is proposed. Their diagnostic role and relationship with the other noninvasive technique of medical visualization--ultrasound study (USS) with Doppler color mapping (DCM) are assessed. As compared with USS, MRI may more accurately and objectively establish the organotopic characteristics of facial soft tissue angiodysplasias and detect lesions of the deep facial parts, maxillary bones, and paranasal sinuses in the diagnosis of these abnormalities. The use of MRI may define the belonging of angiodysplasias to the arterial or venous bed, reveal afferent and efferent vessels, including intracranial ones, and to detect intracranial angiodysplastic changes. USS with DSM was superior to MRI with MRA in defining functional (hemodynamic) parameters of angiodysplasias, which makes this method indispendable in planning treatment and in evaluating its efficiency. Comprehensive examination of patients with large and extensive angiodysplasias of facial soft tissues has indicated that facial angiodysplasias are external manifestations of a more generalized angiodysplastic process in most cases, which, in large and extensive facial angiodysplasias, makes it expedient to perform MRI with MRA of the brain and, if possible, the whole body. The high informative value of MRI with MRA in studying angiodysplasias makes them the method of choice in the diagnosis of this group of diseases.     

多层螺旋计算机断层扫描联合磁共振成像对早期中央型肺癌及术后复发的诊断价值

目的:探讨多层螺旋计算机断层扫描(MSCT)联合磁共振成像(MRI)对早期中央型肺癌及术后复发的诊断价值。方法:选取2015年8月到2017年2月我院收治的早期中央型肺癌患者98例,所有患者均经MSCT和MRI检查。分析并对比单独MSCT的诊断结果及MSCT联合MRI的诊断结果。随访1年,观察并比较疑似复发的患者单独MSCT的诊断结果及MSCT联合MRI的诊断结果,并比较其对复发诊断的灵敏度、特异度。结果:MSCT联合MRI对早期中央型肺癌诊断的准确率、误诊率、漏诊率分别为94.90%、1.02%、4.08%,与单独MSCT诊断的82.65%、9.18%、8.16%比较,MSCT联合MRI诊断的准确率明显升高,误诊率明显降低(P0.05),而两种诊断方法的漏诊率比较差异无统计学意义(P0.05)。随访1年后,98例患者共复查122例次,共有49例复发。MSCT联合MRI诊断早期中央型肺癌患者术后复发的灵敏度、特异度分别为97.96%、93.15%,均高于单独MSCT诊断的83.67%、82.19%(P0.05)。结论:MSCT联合MRI诊断早期中央型肺癌准确率较高,且在诊断术后复发中可提高灵敏度、特异度。     

平山病的过屈位MRI 表现及其临床价值

目的：探讨平山病的过屈位颈椎MRI特征性影像学表现及其临床诊断价值。方法：总结分析经临床证实的5 例平山病患者 的临床及MRI资料,并结合相关文献报道进行回顾性分析。所有患者均行常规生化检查,脑脊液检查,肌电图检查及肌肉活检。结 果：5 例均为青少年男性,呈单侧上肢远端无力伴萎缩,其中1 例患者累及另一侧,尺侧肌萎缩明显,上肢呈斜坡样改变,均无感觉 障碍和锥体束征;肌电图检查显示神经源性改变,提示受损节段多在下颈髓前角细胞。屈颈MRI检查均可见下颈髓前移、硬脊膜 外间隙增宽,可见迂曲条状血管流空影。结论：平山病的过屈位MRI表现具有一定的特征性,对平山病的诊断具有重要价值。     

Initial Imaging Analysis of Budd-Chiari Syndrome in Henan Province of China: Most Cases Have Combined Inferior Vena Cava and Hepatic Veins Involvement

Aim

To evaluate the type of venous involvement in Chinese Budd-Chiari syndrome (BCS) patients and the relative diagnostic accuracy of the different imaging modalities.

Methods

Using digital subtraction angiography (DSA) as a reference standard, color Doppler ultrasound (CDUS), computed tomography angiography (CTA), and magnetic resonance angiography (MRA) were performed on 338 patients with BCS. We analyzed the course of the main and any accessory hepatic veins (HVs) and the inferior vena cava (IVC) to assess the etiology of obstructed segments and diagnostic accuracy of CDUS, CTA and MRA.

Results

Among the 338 cases, there were 8 cases (2.4%) of isolated IVC membranous obstruction, 45 cases (13.3%) of isolated HV occlusion, and 285 cases (84.3%) with both IVC membranous obstruction and HV occlusion. Comparing with DSA, CDUS, CTA had a diagnostic accuracy of 89.3% and 80.2% in detecting BCS, and 83.4% of cases correctly correlated by MRA.

Conclusion

In Henan Province, most patients with BCS have complex lesions combining IVC and HV involvement. The combination of CDUS and CTA or MRI is useful for diagnosis of BCS and guiding therapy.     

Progression of central nervous system disease from pediatric to young adulthood in sickle cell anemia

Silent cerebral infarcts and arteriopathy are common and progressive in individuals with sickle cell anemia. However, most data describing brain lesions in sickle cell anemia are cross-sectional or derive from pediatric cohorts with short follow-up. We investigated the progression of silent cerebral infarct and cerebral vessel stenosis on brain MRI and MRA, respectively, by describing the incidence of new or worsening lesions over a period of up to 25 years among young adults with sickle cell anemia and explored risk factors for progression. Forty-four adults with sickle cell anemia (HbSS or HbSβ⁰thalassemia), exposed to chronic transfusions (n = 12) or hydroxyurea (n = 32), median age 19.2 years (range 18.0–31.5), received a screening brain MRI/MRA and their results were compared with a clinical exam performed during childhood and adolescence. We used exact log-rank test to compare MRI and MRA progression among any two groups. The hazard ratio (HR) and 95% confidence interval (CI) were calculated from Cox regression analyses. Progression of MRI and MRA occurred in 12 (27%) and 4 (9%) young adults, respectively, relative to their pediatric exams. MRI progression risk was high among participants with abnormal pediatric exams (HR: 11.6, 95% CI: 2.5–54.7) and conditional or abnormal transcranial Doppler ultrasound velocities (HR: 3.9, 95% CI: 1.0–15.1). Among individuals treated with hydroxyurea, high fetal hemoglobin measured in childhood was associated with lower hazard of MRI progression (HR: 0.86, 95% CI: 0.76–0.98). MRA progression occurred more frequently among those with prior stroke (HR: 8.6, 95% CI: 1.2–64), abnormal pediatric exam (P = 0.00084), and elevated transcranial Doppler ultrasound velocities (P = 0.004). Brain MRI/MRA imaging in pediatrics can identify high-risk patients for CNS disease progression in young adulthood, prompting consideration for early aggressive treatments.     

Non-Enhanced MR Imaging of Cerebral Aneurysms: 7 Tesla versus 1.5 Tesla

Purpose

To prospectively evaluate 7 Tesla time-of-flight (TOF) magnetic resonance angiography (MRA) in comparison to 1.5 Tesla TOF MRA and 7 Tesla non-contrast enhanced magnetization-prepared rapid acquisition gradient-echo (MPRAGE) for delineation of unruptured intracranial aneurysms (UIA).

Material and Methods

Sixteen neurosurgical patients (male n = 5, female n = 11) with single or multiple UIA were enrolled in this trial. All patients were accordingly examined at 7 Tesla and 1.5 Tesla MRI utilizing dedicated head coils. The following sequences were obtained: 7 Tesla TOF MRA, 1.5 Tesla TOF MRA and 7 Tesla non-contrast enhanced MPRAGE. Image analysis was performed by two radiologists with regard to delineation of aneurysm features (dome, neck, parent vessel), presence of artifacts, vessel-tissue-contrast and overall image quality. Interobserver accordance and intermethod comparisons were calculated by kappa coefficient and Lin''s concordance correlation coefficient.

Results

A total of 20 intracranial aneurysms were detected in 16 patients, with two patients showing multiple aneurysms (n = 2, n = 4). Out of 20 intracranial aneurysms, 14 aneurysms were located in the anterior circulation and 6 aneurysms in the posterior circulation. 7 Tesla MPRAGE imaging was superior over 1.5 and 7 Tesla TOF MRA in the assessment of all considered aneurysm and image quality features (e.g. image quality: mean MPRAGE7T: 5.0; mean TOF7T: 4.3; mean TOF1.5T: 4.3). Ratings for 7 Tesla TOF MRA were equal or higher over 1.5 Tesla TOF MRA for all assessed features except for artifact delineation (mean TOF7T: 4.3; mean TOF1.5T 4.4). Interobserver accordance was good to excellent for most ratings.

Conclusion

7 Tesla MPRAGE imaging demonstrated its superiority in the detection and assessment of UIA as well as overall imaging features, offering excellent interobserver accordance and highest scores for all ratings. Hence, it may bear the potential to serve as a high-quality diagnostic tool for pretherapeutic assessment and follow-up of untreated UIA.