Computed tomography diagnosis of primary aorto-enteric fistula

Primary aorto-enteric fistulae are rare. Preoperative diagnosis is important but is difficult and cannot usually be confirmed by upper gastrointestinal series, aortography and endoscopy. Computed tomography demonstrating an abdominal aortic aneurysm with air bubbles in its wall and "soft tissue" mass posteriorly should raise the possibility of penetration of the aneurysm into the lumen of the bowel and related consequences (hematoma, sepsis, infected operating field).     

Computed tomography of life-threatening complications of abdominal aortic aneurysm. The disrupted aortic wall

A localized disruption of the conspicuity of the wall of the aorta was noted on intravenous contrast-enhanced computed tomography (CT) scans of ten patients with ruptured abdominal aortic aneurysm (n = 6) or aortoenteric fistula (n = 4). Subsequently, we reviewed 84 scans of patients with uncomplicated aneurysm (n = 70) or aneurysm graft repair (n = 14) to determine if a disrupted wall has diagnostic implications. In this control group, the wall of the aneurysm was conspicuous throughout in 95% of 64 patients who received iodinated contrast material intravenously and in 55% of 20 patients who did not. In the proper clinical setting, CT scans performed with intravenous administration of iodinated contrast material can provide direct evidence of disruption of the wall of an abdominal aortic aneurysm. In selected cases, this may be important for the diagnosis of rupture. Disrupted conspicuity of the wall, in combination with effacement of the fat plane between an aneurysm and the juxtaposed intestine, increases the accuracy of CT for the diagnosis of aortoenteric fistula.     

Aortic dissection with concurrent abdominal aortic aneurysm: computed tomography diagnosis

Thoracic aortic dissection in association with preexisting abdominal aortic aneurysm is rare. An illustrative case is presented in which an additional complication of contained aortic rupture and renal infarction occurred. Computed tomography was the primary diagnostic modality.     

Aortocaval fistula complicating abdominal aortic aneurysm: diagnosis with gadolinium-enhanced three-dimensional MR angiography

With approximately 150 reported cases, fistulas between the abdominal aorta and inferior vena cava are rare. Preoperative clinical diagnosis of aortocaval fistula is difficult because the classical triad of abdominal pain, pulsatile abdominal mass, and abdominal machinery-like bruit may be absent in up to 50 % of patients. We report a case of aortocaval fistula complicating abdominal aortic aneurysm which was diagnosed preoperatively using breath-hold gadolinium-enhanced three-dimensional MR angiography. Received: 2 June 1998; Revision received: 28 September 1998; Accepted: 20 November 1998     

MRI diagnosis of aortocaval fistula secondary to ruptured infrarenal abdominal aortic aneurysm

MRI was utilized to demonstrate the exact site of fistula between a ruptured saccular aneurysm of the infrarenal abdominal aorta and the inferior vena cava in a 64-year-old man.     

Computed tomography of primary aortocaval fistula.

Spontaneous aortocaval fistula is a rare but documented complication of arteriosclerotic abdominal aortic aneurysm. Most cases reported have presented clinically with a palpable aneurysm, abdominal bruit, and high output congestive heart failure. A diagnosis in such cases requires active demonstration of findings secondary to arteriovenous shunting, which can be optimized utilizing proper CT bolus technique and dynamic scanning. We describe several CT findings--all of which may be typical for and support the diagnosis of this potentially lethal complication of abdominal aortic aneurysm.     

Posterior "Nutcracker" phenomenon in a patient with abdominal aortic aneurysm

European Radiology - We report on a posterior "nutcracker" phenomenon due to an abdominal aortic aneurysm in a patient with a retro-aortic left renal vein. A 71-year-old man with a known...     

Posterior "Nutcracker" phenomenon in a patient with abdominal aortic aneurysm

We report on a posterior "nutcracker" phenomenon due to an abdominal aortic aneurysm in a patient with a retro-aortic left renal vein. A 71-year-old man with a known abdominal aortic aneurysm presented in the emergency room with mild hematuria and flank pain. Computed tomography angiography revealed an aortic aneurysm, which compressed the left renal vein between the aorta and the vertebral column. Compression of the left renal vein, due to the aorta with consecutive congestion and hematuria as well as flank pain, was previously described as nutcracker phenomenon. In case of a retro-aortic left renal vein, increase of the aortic diameter can lead to compression of the renal vein and furthermore to the classical signs and symptoms of the "nutcracker" phenomenon, even though the aneurysm is not ruptured or there are no aorto-caval or aorto-left renal vein fistulas.     

Computed tomography of a thrombosed left anterior vena cava

A case of transposed (left) inferior vena cava (IVC) with a normal suprarenal IVC visible on computed tomography (CT) is presented. There is concomitant recanalized thrombosis of the left IVC with venous collaterals present. Caval anomalies, differential diagnosis of a left IVC, and CT demonstration of thrombosis of major abdominal venous structures and associated venous collaterals are discussed.     

Quantification of aortic distensibility in abdominal aortic aneurysm using ECG-gated multi-detector computed tomography

Rationale and objectives

To detect distensibility changes that might be an indicator for an increased risk of rupture, cross-sectional area changes of abdominal aortic aneurysms (AAA) have been determined using ECG-gated CT.

Materials and methods

Distensibility measurements of the aorta were performed in 67 patients with AAA. Time-resolved images were acquired with a four detector-row CT system using a modified CT-angiography protocol. Pulsatility-related cross-sectional area changes were calculated above and at AAA level by semiautomatic segmentation; distensibility values were obtained using additional systemic blood pressure measurements. Values were compared for small Ø< 5 cm (n=44) and large Ø> 5 cm (n?=?23) aneurysms.

Results

The aorta could be segmented successfully in all patients. Upstream AAA distensibility D was significantly higher than at AAA level for both groups: means above AAA (at AAA) D _above = (1.3±0.8)·10^?5 Pa^?1 (D _AAA = (0.6±0.5)·10^?5 Pa^?1) t-test p_D<0.0001. Differences of the distensibility between smaller and larger aneurysms were not found to be significant.

Conclusion

Distensibility can be measured non-invasively with ECG-gated CT. The reduction of distensibility within aneurysms compared to normal proximal aorta is subtle; the lack of difference between both small and large aneurysms suggests that this reduction occurs early in the aneurysm's development. Hence, reduced distensibility might be a predictive parameter in patients with high risk of aortic disease.

     

Aortobronchopulmonary fistula complicating aortic aneurysm: diagnosis in four cases

Aortobronchopulmonary fistula, a fistulous connection between the aorta and lung, is uniformly fatal in untreated cases. However, with early recognition and surgery, the survival rate exceeds 80%. We have had four patients with aortobronchopulmonary fistula, all of which resulted from thoracic aortic aneurysms (two after grafting of thoracic aortic aneurysms, one mycotic, one atherosclerotic). All four patients presented with hemoptysis. All four had a chest radiograph, which in two showed the aneurysm and in three showed airspace disease adjacent to the aorta. The aneurysm was shown by CT in one of two patients and by aortography in two of three patients. Neither CT nor aortography showed the fistula. Aortobronchopulmonary fistula was proved by surgery in two of the patients and by autopsy in the other two. A high index of suspicion is necessary to make the diagnosis of aortobronchopulmonary fistula. The diagnosis should be considered in patients who have minor or major hemoptysis, with either coexisting thoracic aortic aneurysms or history of thoracic aneurysm repair.     

多层螺旋CT血管成像在腹主动脉瘤中的诊断应用

目的探讨多层螺旋CT血管成像在腹主动脉瘤（AAA）中的诊断价值。方法30例临床疑诊AAA患者均经16层螺旋CT血管成像（MSCTA）。采用最大密度投影（M1P）、多平面重组（MPR）、容积再现（VR）技术对传送至AW4.1工作站的原始数据进行重建,获得二维或三维的立体图像。结果30例疑诊AAA患者中有7例真性腹主动脉瘤,15例假性动脉瘤,8例主动脉夹层。MPR能准确显示瘤体位置、形态、范围及附壁血栓。MIP能较好地显示瘤壁及附壁血栓内的钙化。VR技术能立体精确显示腹主动脉、瘤体及周围组织结构的空间关系。结论多层螺旋CT血管成像是一种无创、快速的检查方法,为临床诊断、治疗腹主动脉瘤提供重要信息。     

Computed tomography of carotid-cavernous fistula

Fourteen patients with angiographically-proven carotid-cavernous fistulas were evaluated by computed tomography (CT). Unilateral or bilateral exophthalmos was noted in 12 patients. Slight blurring of the margin of the globe was present in two, presumably due to pulsations of the globe or conjunctival edema. Superior ophthalmic veins were prominent in 12 patients and were often larger on the side of the fistula. Irregularity or absence of contrast enhancement of the superior ophthalmic vein may indicate partial or complete thrombosis. Focal bulging or diffuse distention of the cavernous sinus was noted in nine patients. Enlargement of the extraocular muscles was observed in seven with swelling of the eyelids and edema of the conjunctiva in eight patients. The pattern of venous drainage, type of fistula, and time intervals between trauma, commencement of fistula, and CT scan may affect the CT manifestations of carotid-cavernous fistulas.