Infected aortic aneurysms: imaging findings

PURPOSE: To determine the imaging characteristics of infected aortic aneurysms. MATERIALS AND METHODS: Review of records of patients with surgical and/or microbiologic proof of infected aortic aneurysm obtained over a 25-year period revealed 31 aneurysms in 29 patients. This study included 21 men and eight women (mean age, 70 years). One radiologist reviewed 28 computed tomographic (CT) studies (22 patients underwent CT once and three patients underwent CT twice), 12 arteriograms (12 patients underwent arteriography once), eight nuclear medicine studies (six patients underwent nuclear medicine imaging once and one patient underwent nuclear medicine imaging twice), and three magnetic resonance (MR) studies (three patients underwent MR imaging once). Features evaluated included aneurysm size, shape, and location; branch involvement; aortic wall calcification; gas; radiotracer uptake on nuclear medicine studies; and periaortic and associated findings. The location of infected aortic aneurysms was compared with that of arteriosclerotic aneurysms. RESULTS: Aneurysms were located in the ascending aorta (n = 2, 6%), descending thoracic aorta (n = 7, 23%), thoracoabdominal aorta (n = 6, 19%), paravisceral aorta (n = 2, 6%), juxtarenal aorta (n = 3, 10%), infrarenal aorta (n = 10, 32%), and renal artery (n = 1, 3%). Two patients had two infected aortic aneurysms. CT revealed 25 saccular (93%) and two fusiform (7%) aneurysms with a mean diameter at initial discovery of 5.4 cm (range, 1-11 cm). Paraaortic soft-tissue mass, stranding, and/or fluid was present in 13 (48%) of 27 aneurysms, and early periaortic edema with rapid aneurysm progression and development was present in three (100%) patients with sequential studies. Other findings included adjacent vertebral body destruction with psoas muscle abscess (n = 1, 4%), kidney infarct (n = 1, 4%), absence of calcification in the aortic wall (n = 2, 7%), and periaortic gas (n = 2, 7%). Angiography showed 13 saccular aneurysms with lobulated contour in 10 (77%). Nuclear medicine imaging showed increased activity consistent with infection in six (86%) of seven aneurysms. MR imaging showed three saccular aneurysms. Adjacent abnormal vertebral body marrow signal intensity was seen in one (33%) of three patients. CONCLUSION: Saccular aneurysms (especially those with lobulated contour) with rapid expansion or development and adjacent mass, stranding, and/or fluid in an unusual location are highly suspicious for an infected aneurysm.     

Takayasu's arteritis: evaluation with three-dimensional time-of-flight MR angiography

Three-dimensional time-of-flight MR angiography was performed in 16 patients with Takayasu's arteritis. Two regions were evaluated, the arch of aorta and its intrathoracic major branches, and the abdominal aorta with proximal portions of its major visceral and renal branches. Individual arteries and aortic segments, i. e. aortic arch and abdominal aorta, were evaluated for abnormalities such as stenosis, occlusion, dilatation and aneurysm formation. The results were compared with contrast angiography. Follow-up MR angiography was performed in three patients after 9–12 months. MR angiography demonstrated steno-occlusive lesions in all the patients and aneurysms in 2. In comparison with contrast angiography, good correlation was found in 129 of the 145 arteries and aortic segments. For the 12 false-positive results, incorrect slab placement and overestimation of stenosis were implicated. Interestingly, there were three false-negative results and one occlusion was underestimated as stenosis. A new lesion developed in 1 patient and one stenosis progressed in another patient upon follow-up. Three-dimensional time-of-flight MR angiography is a simple and fairly accurate method for documenting the lesions in Takayasu's arteritis and for its follow-up. Received 12 April 1995; Revision received 30 August 1995; Accepted 15 September 1995     

Aortic atherosclerosis detected with electron-beam CT as a predictor of obstructive coronary artery disease

RATIONALE AND OBJECTIVES: Several studies have demonstrated an association between coronary and aortic atherosclerosis. Aortic atherosclerosis is easily quantified by means of electron-beam computed tomography (CT). The aim of this study was to evaluate the usefulness of measurement of aortic atherosclerosis with electron-beam CT as an independent predictor of obstructive coronary artery disease (CAD). MATERIALS AND METHODS: Ninety-seven patients (67 men, 30 women; mean age, 61 years +/- 12) were enrolled and underwent electron-beam CT with and without contrast material. Coronary artery calcification was quantified with nonenhanced electron-beam CT by means of Agatston score. CAD was defined as luminal narrowing of the coronary artery by at least 70%, as measured with electron-beam angiography. Aortic atherosclerosis was quantified by measuring raised lesions of the aortic wall (plaque) and wall thickening (volume and thickness) in the midportion of the descending thoracic aorta (10 contiguous sections), as depicted at contrast material-enhanced CT angiography. RESULTS: Aortic plaque and calcification were detected only in patients who were at least 58 years old. The presence of aortic plaque was predictive of obstructive CAD, independent of coronary artery calcification. The sensitivity of aortic plaque (raised lesions) for obstructive CAD was 89% in patients at least 58 years old, and the specificity was 63%. Aortic calcification had a sensitivity of 56% and a specificity of 72% for diagnosis of obstructive CAD. CONCLUSION: This study demonstrated that aortic plaque detected with contrast-enhanced electron-beam CT was a more consistent predictor of obstructive CAD than other independent aortic variables. Aortic calcification depicted on nonenhanced CT images was highly specific for obstructive CAD.     

CT of aortic aneurysms: the distinction between mural and thrombus calcification

Aortic calcification, either mural or thrombus, is a common finding in patients with abdominal aortic aneurysms. Differentiating between the two sites of calcification is necessary in order to avoid confusing simple thrombus calcification with displaced calcified intima in aortic dissection. The CT scans of 145 cases of abdominal aortic aneurysm and seven cases of abdominal aortic aneurysm with dissection were analyzed with respect to the location of the calcification: mural only or mural and thrombus. Mural calcification was seen in all 152 patients with aneurysms whereas thrombus calcification was identified in only 33 (24%) of the 136 patients with thrombus. Displaced intimal calcification caused by aortic dissection can either appear similar to or, at times, be indistinguishable from thrombus calcification. Thrombus calcification was present in four (57%) of the seven patients with abdominal aortic aneurysms and dissection. To avoid the possibility of a false-positive diagnosis of aortic dissection in patients with abdominal aortic aneurysm, other signs of aortic dissection should be sought such as separation of the true and false lumina by an intimal flap.     

Imaging findings in Takayasu's arteritis

OBJECTIVE: The objective of our study was to evaluate the clinical usefulness of cross-sectional imaging for establishing the diagnosis of Takayasu's arteritis (TA), an inflammatory vascular disorder that produces arterial stenoses and aneurysms primarily involving the thoracoabdominal aorta and its branches and the pulmonary arteries. CONCLUSION: CT and MRI findings of TA include vascular wall thickening and enhancement early in the disease, and arterial stenoses, occlusions, and aneurysms later in the disease. Cross-sectional imaging is useful for establishing the diagnosis of TA and for showing response to nonsurgical therapy or for planning a surgical intervention.     

Electron beam CT features of the pulmonary artery in Takayasu's arteritis.

OBJECTIVE: Pulmonary artery involvement in Takayasu's arteritis is suggestive of the disease. Our aim was to use electron beam CT to study pulmonary artery changes in patients with Takayasu's arteritis. CONCLUSION: Diffuse wall thickening and dilatation or stenosis were significantly more frequent on CT in patients with Takayasu's arteritis than in the control subjects. Knowledge of these findings may be of value when assessing pulmonary artery involvement and thus may be helpful for the diagnosis of Takayasu's arteritis.     

大动脉瘤螺旋CT血管造影与DSA比较研究

目的:探讨大动脉瘤螺旋CT 血管造影(SCTA) 检查技术和应用价值,为合理选择SCTA 和DSA 检查方法提供依据。材料和方法:34 例大动脉瘤,均行SCTA 和DSA 检查,其中29 例经手术证实,术后7 例随访检查用SCTA。SCTA用最大强度投影( MIP) 和表面遮盖显示(SSD) 两种方法重建血管。结果:胸主动瘤10 例,腹主动脉瘤15 例,胸腹主动脉连续性动脉瘤2 例,髂动脉瘤7 例。SCTA 和DSA 均能较好地显示大动脉瘤的部位、形状、范围及夹层情况。MIP 重建图像能显示动脉壁钙化,SSD 重建图像能较好地显示动脉瘤的三维形态,SCTA 结合CT 横断面及多平面重建图像可更清楚显示动脉腔、动脉壁、附壁血栓及动脉周围组织结构。DSA 图像空间分辨力较SCTA 高,但不能清楚显示动脉壁、附壁血栓及动脉周围组织结构。结论:对大动脉瘤可首选SCTA 检查以替代DSA 检查。     

The fate of infrarenal abdominal aortic aneurysms after stent grafting: influence of thrombosis at side branch ostia

PURPOSE: To evaluate the effect of postoperative thrombosis of the side branch ostia on the shrinkage of endoluminally treated abdominal aortic aneurysms with patent side branch vessels. MATERIALS AND METHODS: Thirty-three patients were followed up with serial computed tomography (CT). Special attention was paid to presence or absence of retrograde enhancement of the side branch ostia after the covering of the patent side branch vessels by the stent graft and aneurysm diameter change on postoperative CT. Preoperative CT was also reviewed to assess the number of patent side branch vessels, degree of aneurysm wall calcification, and thickness of the mural thrombus. The patients with type 2 endoleak were excluded from this evaluation. The patients were divided into 2 groups, the nonthrombosed and thrombosed groups, based on presence or absence of retrograde enhancement of the side branch ostia as depicted on all postoperative CT. RESULTS: Type 1 endoleak was not seen in all patients. Preoperative diameter of the aneurysm was 4.75 +/- 0.18 cm in the thrombosed group (n = 12) and 4.98 +/- 0.35 cm in the nonthrombosed group (n = 8). There were no significant differences in follow-up periods, preoperative diameter of the aneurysm, number of patent side branch vessels, degrees of aneurysm wall calcification, and thickness of the mural thrombus between the 2 groups. The mean diameter of the aneurysm in the nonthrombosed group did not change at 3 and 6 months then first decreased at 12 months after the stent grafting. However, in the thrombosed group, the mean diameter of the aneurysm had decreased at 3 months after stent grafting. Thereafter, the aneurysms continuously shrank. CONCLUSIONS: Postoperative thrombosis of the side branch ostia may predict favorable shrinkage of endoluminally treated aneurysms.     

The thoracic aorta studied by MR imaging

Thirty-three patients with a variety of disorders of the thoracic aorta (aneurysm, dissection, Marfan syndrome, coarctation/pseudocoarctation, L-transposition, and Takayasu disease) were evaluated with magnetic resonance (MR) imaging. MR imaging delineated the presence and extent of thoracic aortic aneurysms and showed the relationship of the aneurysm to arch vessels; it also demonstrated intimal flaps and individual lumina in types A and B aortic dissection. Dilation of the ascending aorta in Marfan syndrome and focal narrowing of the aorta in coarctation were well visualized. The anteroposterior and side-to-side relationships of the aorta and pulmonary artery in L-transposition were demonstrated, as were aortic wall thickening and branch vessel narrowing in Takayasu arteritis. Initial experience suggests that MR imaging may provide a noninvasive method for evaluating thoracic aortic disease. Limitations include inferior spatial resolution, occasional difficulty in imaging the entire region of interest in one section, lack of signal from calcifications, and inability to monitor critically ill patients.     

大动脉炎的多层螺旋CT诊断

目的 :探讨大动脉炎的多层螺旋CT表现。方法 :回顾性分析 7例大动脉炎患者的CT表现 ,所有病例均经临床及多层螺旋CT血管成像 (MSCTA)确诊。结果 :7例大动脉炎患者多层螺旋CT血管成像主要表现为主动脉及其分支血管管腔的狭窄、闭塞、扩张及血管壁增厚与钙化。结论 :多层螺旋CT血管成像能准确诊断大动脉炎患者主动脉及其主要分支的管腔与管壁的变化。     

Failure of aneurysm sac shrinkage after endovascular repair; the effect of mural calcification

AIM: To evaluate the effect of abdominal aortic aneurysm wall calcification on subsequent sac shrinkage after endovascular repair. MATERIALS AND METHODS: Seventy-three patients underwent endovascular aneurysm repair. The degree of sac wall calcification on pre-procedural computed tomography (CT) examination was graded from 1 to 4 according to the degree of circumferential involvement. On follow-up CT imaging, the maximum transverse diameter (MTD) of the sac was recorded, as well as the presence or absence of endoleak. In those patients with a non-shrinking aneurysm, but no CT evidence of endoleak, contrast-enhanced ultrasound (USS) was performed. Any patient with an endoleak, however diagnosed, was excluded from the study. Kruskal-Wallis and Spearman's rank correlation coefficient testing was applied to compare the degree of calcification and change in MTD. RESULTS: Sixty-three pre-procedural CT images were available for calcification grading. Six of this group had endoleaks resulting in 57 sets of data being available for the study. A reduction in MTD occurred in 68.25% of these patients by 1 year post-procedure. Our figures show aortic calcification is inversely associated with MTD reduction at 6 months (p = 0.01), 1 year (p = 0.05) and 2 years (p = 0.05). CONCLUSION: This study indicates that the degree of aortic wall calcification is significant in predicting MTD reduction post-endovascular repair. The possible mechanisms and implications of this are discussed.     

多层螺旋CT造影在主动脉病变腔内修复术后随访的价值

目的:探讨多层螺旋CT血管造影(multi-detector rowspiral computed tomography angiography,MDCTA)及后处理技术在主动脉覆膜支架腔内修复术(transluminal stent-graft placement,TSGP)术后随访的临床应用价值。方法:21例接受TSGP主动脉疾病患者,包括:Stanford B型夹层13例,真性动脉瘤3例,假性动脉瘤2例,弓降部穿透性溃疡1例,胸主动脉瘤合并局限性夹层1例,胸主动脉瘤合并Stanford B型夹层1例,术后采用MDCTA进行随访,平均随访13个月(1~24个月)。采用轴位图像与多种重建图像相结合来显示支架形态、术前术后主动脉管腔情况的变化和有无并发症。结果:13例主动脉夹层覆膜支架置入后:所有患者均真腔扩大,假腔减小或消失并伴血栓形成,支架未发现移位或断裂;共3例(14%)随访中发现内漏,1例Ⅱ型内漏,建议随访观察;1例术后8个月复查新发现支架近端Ⅰ型内漏,密切随访2个月后患者出现胸痛,复查CT内漏增多,转外科治疗。1例腹主动脉瘤术后1月复查发现Ⅲ型内漏。所有患者介入术后CT随访图像均满足临床诊断需要。结论:MDCTA对主动脉覆膜支架置入术后随访较其他检查手段具有多方面的优越性,能及时观察术后疗效、发现并发症,对主动脉疾病覆膜支架腔内修复术后随访具有重要价值。     

Pulmonary artery disease in Takayasu's arteritis: angiographic findings.

One hundred sixteen arteriographic examinations in 98 patients with Takayasu's arteritis were studied retrospectively to evaluate the extent of aortic and pulmonary disease. Stenosis was the most frequent finding in the aorta and its branches, but occlusion, dilatation, and aneurysms were also seen. Adventitial vascular structures, consistent with dilated vasa vasorum, were observed in five patients (5%) and systemic artery-pulmonary artery communication was seen in six (6%). Twenty-one (70%) of 30 patients who had pulmonary arteriography were shown to have pulmonary artery involvement. Upper lobe pulmonary arterial branches showed abnormalities most frequently; segmental branches, followed by subsegmental branches, were most often involved. The frequency of abnormal findings on pulmonary arteriograms correlated with the number of involved brachiocephalic vessels. Stenotic lesions in the aorta and its branches progressed in five (45%) of 11 patients, and those in the pulmonary artery progressed in one (33%) of three cases. Takayasu's arteritis characteristically involves the systemic and pulmonary arteries, and the extent of arteritis in the major branches of the aortic arch appears to correlate with pulmonary arterial involvement. Both thoracic and abdominal aortographic studies and pulmonary arteriography are necessary to properly diagnose the extent of the disease, and angiography should be repeated for appropriate patient follow-up.     

CT of thoracic aortic aneurysms

Aneurysms of the thoracic aorta are most often the result of arteriosclerotic disease. Other causes include degeneration of the medial layer of the aortic wall, either idiopathically or due to genetic disorders such as Marfan syndrome; aortic dissection; trauma; syphilis and other bacterial infection; noninfective aortitis; and congenital anomaly. We review normal anatomy of the aorta and discuss our technique and interpretation of computed tomography (CT) in the evaluation of the thoracic aorta. We illustrate the CT appearance of different types of aortic aneurysms as well as discuss the use of CT for assessing complications of aneurysms, for postoperative follow-up, and in the differentiation of aortic aneurysm from a paraaortic mass.     

Initial experience with percutaneous transluminal angioplasty in the management of Takayasu's arteritis

We have performed percutaneous transluminal angioplasty (PTA) for 15 arterial stenoses in 11 patients with Takayasu's arteritis. The lesions included tight, proximally located renal artery stenosis (12 stenoses; nine patients), localized abdominal aortic stenosis (two patients) and occluded left common iliac artery (one patient). Clinically successful dilatation was achieved in seven patients (10 stenoses) with renal artery stenosis, in both the patients with abdominal aortic stenosis and in the only patient with an occluded left common iliac artery. No complications related to the procedure were encountered. The follow-up period (n = 7) ranged between 1 and 16 months, mean follow-up period after renal angioplasty was 5 months and after abdominal aortic angioplasty was 12.5 months. Initial success has been maintained in both the patients with abdominal aortic stenoses and in four out of five patients with renal artery stenosis. Percutaneous transluminal angioplasty offers an attractive alternative for the management of stenosing lesions in Takayasu's arteritis with good short term results.     

Aneurysm shrinkage after endovascular repair of aortic diseases

BACKGROUND: There are two graft materials for endovascular repair of aortic diseases, i.e., polyester and expanded polytetrafluoroethylene (ePTFE). The latest reports have suggested that there is graft-specific difference in outcomes. The purpose of this article was to evaluate the difference in terms of aneurysm shrinkage. PATIENTS AND METHODS: Eighty-six patients who underwent endovascular repair of aortic diseases were included. Forty patients had true aortic aneurysms, 8 had aortic pseudoaneurysms, and 38 had aortic dissections. Eighteen patients with true aortic aneurysms were treated with stent grafts fabricated with polyester, while the other 68 patients, including 22 patients with true aneurysms, 8 patients with pseudoaneurysms, and 38 patients with aortic dissections, were treated with stent grafts fabricated with ePTFE. All patients were followed-up by computed tomography (CT) for more than 1 year. The mean follow-up term was 28 months. Computed tomography confirmed that there were sufficiently long necks, and the aneurysm or the entry tear was completely excluded without any endoleak in all patients. The diameter of the preoperative lesion was compared with that measured on follow-up CT at 1 year and at the end of the follow-up term. Increase or decrease in the diameter by more than 5 mm was defined as a significant diameter change. RESULTS: Aneurysm shrinkage was observed in 40% of patients with true aneurysms, 88% of patients with pseudoaneurysms, and 55% of patients with aortic dissections at 1 year. There was no significant increase in patients with aneurysm shrinkage at the end of follow-up in any groups. In the case of true aortic aneurysms, shrinkage of aneurysms was observed more frequently with polyester-fabricated stent grafts (67%, 13/18) than with ePTFE-fabricated ones (18%, 4/22) at 1 year (P<.01). In contrast, expansion of aneurysms was observed only in patients treated with ePTFE (14%, 3/22). Shrinkage of the descending aorta was observed in 55% of patients with acute aortic dissections and 36% of patients with chronic aortic dissections. There was no case with aortic enlargement in either group. There was no significant difference between acute and chronic dissection in terms of shrinkage of the descending aorta. CONCLUSION: Expanded polytetrafluoroethylene appears to be effective for the treatment of pseudoaneurysms and aortic dissections. However, polyester seems to be more effective than ePTFE when true aneurysms are to be treated.     

Endovascular repair of thoracic aortic aneurysm and intramural hematoma in giant cell arteritis

An 80-year-old woman with established giant cell arteritis presented at the authors' institution with a 6.5-cm false aneurysm of the descending thoracic aorta complicated by focal dissection and intramural hematoma after a 1-week history of acute-onset chest pain. The patient underwent uncomplicated endovascular aortic repair with a 32-mm x 15-cm TagExcluder stent-graft. After the procedure, the intramural hematoma resolved and the patient's corticosteroid and immunosuppressive therapy was repeatedly adjusted. However, the giant cell arteritis activity relapsed after 8 months with development of a similar 1.5-cm false aneurysm below the thoracic stent-graft, complicated by focal intramural hematoma. Repeat uncomplicated thoracic stent-graft implantation was performed and CT follow-up displayed resorption of the intramural hematomas with no evidence of endoleak or any new aortic pathology. This report discusses the difficult management of patients with relapsing active aortic giant cell arteritis and the potential role for endovascular thoracic aortic repair.     

Aortic dissection: atypical patterns seen at MR imaging

Aortic dissection is typically manifested by an intimal flap separating true and false lumens. Atypical patterns lacking an intimal flap can occur, however, and are less well recognized. In this study, the authors review their experience with atypical patterns at magnetic resonance (MR) imaging. They evaluated the T1-weighted and gradient-echo MR images of the entire aorta in 64 patients with aortic dissection. In nine patients (14%) aortic wall thickening was the only sign of dissection in the thorax. In three of these cases, an intimal flap was found in the abdominal aorta; the other six patients had no flap in any region of the aorta, and this led to false-negative angiographic results in three cases. Aortic wall thickening as an atypical sign of dissection was seen more frequently in acute (29%) than in chronic (7%) dissection and was seen in only patients without Marfan syndrome. Two patients with atypical acute dissection at initial examination developed a clearly identifiable intimal flap at follow-up. Aortic wall thickening may represent the only sign of aortic dissection. In some cases, imaging the entire aorta can enable recognition of dissection in atypical cases.     

平板旋转血管造影及三维重组在主动脉病变中的应用

目的:评价平板旋转血管造影及三维重组在主动脉病变临床应用的价值.方法:对比分析31例主动脉病变患者的CT或MR、二维血管造影、旋转血管造影及三维重组影像学资料,并对其结果对比分析.31例均为男性,年龄18～81岁,平均56.5岁.结果:行胸主动脉造影28例,发现主动脉夹层25例,动脉瘤1例,假性动脉瘤1例,主动脉弓畸形1例.行腹主动脉造影3例,发现动脉瘤2例,1例为腹主动脉动脉硬化性改变并主动脉钙化.所有主动脉夹层、真性及假性动脉瘤造影与CT或MRI对比,病变的形态、大小、位置均相符.其中有2例夹层的造影提示CT诊断破口位置错误.1例主动脉弓畸形,CT误诊为动脉瘤,而造影则可以清晰显示扩张纡曲的畸形主动脉弓.其中23例主动脉夹层和3例真性动脉瘤造影后进行支架主动脉腔内隔绝术的介入治疗,术后均行二维血管造影,支架位置准确,隔绝效果良好,没有出现并发症.结论:平板旋转血管造影及三维重组对主动脉病变的诊断和治疗有较高的临床应用价值,可以提高介入治疗的安全性和成功率.     

Follow-up CT Evaluation of the Mural Changes in Active Takayasu Arteritis

Objective

We wanted to evaluate the mural changes by CT on the follow-up examination of patients with active Takayasu arteritis.

Materials and Methods

The study included 18 patients, (4 males and 14 females), with active Takayasu arteritis. A total of 44 CT examinations were done during the follow-up period (mean: 55.6 months). At the time of the last follow-up CT, the disease, on the basis of the erythrocyte sedimentation rate (ESR), was found to be inactive in five patients and the disease was active and persistent in 13 patients. The thickness and CT attenuation of the aortic wall on the precontrast, arterial and venous phases were measured on the initial and the follow-up CT examinations. The ratio of the mural attenuation over that of the back muscle on the initial CT was compared with the ratio found on the follow-up CT.

Results

The initial CT findings included high density and calcifications of the aortic wall in the precontrast images and a thickened wall with enhancements in the arterial and the venous phases. A low-attenuation ring was demonstrated in the venous phase in 15 patients (83%). On the follow-up evaluation, the mean mural thickness decreased significantly from 4.1 mm to 2.4 mm. The mean mural attenuation ratio in the venous phase decreased significantly from 1.9 to 1.3 (p = 0.001). The low attenuation ring was identified in seven patients (39%) who had only with active, persistent Takayasu arteritis.

Conclusion

The mural changes demonstrated by the follow-up CT evaluations for the patients with active Takayasu arteritis included a decrease of the mural thickness and enhancement, disappearance of the low-attenuation ring on the venous phase, and an increase of the mural attenuation and calcification on the precontrast phase.