Significance of endotension,endoleak, and aneurysm pulsatility after endovascular repair

OBJECTIVE: The lack of aneurysm pulsatility after endovascular aneurysm repair (EVAR) is deemed by some an important guide to the effectiveness of exclusion. However, factors that contribute to aneurysm pulsatility after EVAR have not been elucidated. This study quantitatively analyzed the effects of systemic pressure, aneurysm sac pressure, endoleak, branch outflow from aneurysm sac, and intra-sac thrombus on aneurysm pulsatility after EVAR. METHODS: In an ex vivo model, an artificial aneurysm sac was incorporated within a mock circulation comprised of rubber tubing and a pulsatile pump. The aneurysm sac was then completely excluded from the circulatory circuit with two types of stent-grafts, ie, supported and unsupported, and heparinized canine blood was circulated. Systemic circulation and aneurysm sac pressure was recorded in the absence and presence of endoleaks, and simulated open and closed lumbar branch outflow from the aneurysm sac. The aneurysm sac was then filled with organized human thrombus, and all pressure measurements were repeated. Two observers blinded to the above-mentioned variables independently evaluated aneurysm sac pulsatility with palpation in five separate experiments. Analysis of variance was performed, with significance accepted at P =.05. RESULTS: Systemic pressure was simulated in the artificial circulation to range from 100/60 to 180/60 mm Hg. Regardless of the simulated lumbar branch outflow from the aneurysm, sac pressure was directly related to the presence of endoleak (P <.001). Aneurysm sac pulsatility was present only when the lumbar branch outflow was patent and not dependent on sac pressures. Aneurysm sac thrombosis or type of stent-graft did not influence sac pressure and pulsatility. CONCLUSIONS: In this model, after EVAR pulsatility depends on aneurysm sac outflow, regardless of endoleak, sac thrombosis, sac pressure, or stent-graft. Furthermore, persistent pulsatility does not predict systemic intra-sac pressure, nor does lack of pulsatility reflect freedom of the aneurysm sac from systemic pressurization. This ex vivo model suggests that aneurysm pulsatility is an unreliable guide for predicting aneurysm sac pressurization after EVAR. Other diagnostic methods must be used to assess successful aneurysm exclusion.     

Intracranial saccular aneurysm enlargement determined using serial magnetic resonance angiography

OBJECT: The goal of this study was to determine the frequency of enlargement of unruptured intracranial aneurysms by using serial magnetic resonance (MR) angiography and to investigate whether aneurysm characteristics and demographic factors predict changes in aneurysm size. METHODS: A retrospective review of MR angiograms obtained in 57 patients with 62 unruptured, untreated saccular aneurysms was performed. Fifty-five of the 57 patients had no history of subarachnoid hemorrhage. The means of three measurements of the maximum diameters of these lesions on MR source images defined the aneurysm size. The median follow-up period was 47 months (mean 50 months, range 17-90 months). No aneurysm ruptured during the follow-up period. Four patients (7%) harbored aneurysms that had increased in size. No aneurysms smaller than 9 mm in diameter grew larger, whereas four (44%) of the nine aneurysms with initial diameters of 9 mm or larger increased in size. Factors that predicted aneurysm growth included the size of the lesion (p < 0.001) and the presence of multiple lobes (p = 0.021). The location of the aneurysm did not predict an increased risk of enlargement. CONCLUSIONS: Patients with medium-sized or large aneurysms and patients harboring aneurysms with multiple lobes may be at increased risk for aneurysm growth and should be followed up with MR imaging if the aneurysm is left untreated.     

Contrast-enhanced magnetic resonance angiography

With technological advances in magnetic resonance angiography (MRA), spatial resolution of 1-mm perforating vessels can reliably be visualized and accurately located in reference to patients' anatomic landmarks without exposing patients to ionizing radiation or iodinated contrast, resulting in optimal perforator selection, improved flap design, and increased surgical efficiency. As their experience with MRA in breast reconstruction has increased, the authors have made changes to their MRA protocol that allow imaging of the vasculature in multiple donor sites (buttock, abdomen, and upper thigh) in one study. This article provides details of this experience with multiple donor site contrast-enhanced MRA.     

Assessment of Moyamoya disease with 3.0-T magnetic resonance angiography and magnetic resonance imaging versus conventional angiography

3.0-T magnetic resonance (MR) angiography and MR imaging were compared with conventional angiography for the evaluation of moyamoya disease in 13 preoperative patients (26 hemispheres) with moyamoya disease (4 males and 9 females aged 21-54 years). The correlation between MR angiography scores determined by modified Houkin's grading system (MRA score) and conventional angiography stages determined by Suzuki's grading system (CA stage) was analyzed. Other MR findings such as moyamoya vessel scores, "ivy sign" scores, and the presence of small, medium, and large cerebrovascular attack (CVA) lesions were compared with CA stages. MRA scores were significantly correlated with CA stages (p < 0.01). Moyamoya vessel scores correlated well with CA stages (p < 0.01). There was no significant correlation between "ivy sign" scores and CA stages, and no significant differences in CA stages with the presence and absence of CVA lesions of any size. 3.0-T MR angiography can be used as a vascular assessment in moyamoya disease with its priority of noninvasive nature and visual clarity compared with conventional angiography. The findings of 3.0-T MR angiography may reflect the steno-occlusive changes in moyamoya disease.     

Ruptured cerebral aneurysm not detected by magnetic resonance angiography in juvenile autosomal dominant polycystic kidney

Recently, it has been reported that magnetic resonance angiography (MRA) is useful for screening and following up cerebral aneurysms in patients with autosomal dominant polycystic kidney disease (ADPKD). However, a patient was encountered with a ruptured cerebral aneurysm that was not detected by routine MRA. The patient, a 29-year-old man with ADPKD, was followed up at our hospital for more than 5 years. Ten months after an MRA examination, he suddenly developed severe headache. Brain computed tomography revealed subarachnoid hemorrhage. Digital subtraction angiography detected an aneurysm with a diameter of approximately 2 mm in the anterior communicating artery. Clipping of the aneurysm was immediately performed and he recovered without sequela after operation. Magnetic resonance angiography is useful to detect cerebral aneurysms, but it can not detect aneurysms measuring less than 4 mm.     

Stereotactic magnetic resonance angiography.

Visualization of the surgical trajectory with respect to the cerebral vasculature may enhance the safety of some stereotactic neurosurgical procedures. Traditional stereotactic angiography is tedious and, being an invasive procedure, poses some risk to the patient. A technique of projecting a stereotactically defined surgical trajectory onto magnetic resonance angiograms is presented.     

Children with cerebral venous thrombosis diagnosed with magnetic resonance imaging and magnetic resonance angiography.

From 1985 to 1991, 13 children were diagnosed at the University of Illinois College of Medicine at Peoria, Saint Francis Medical Center, with cerebral venous thrombosis (CVT) by magnetic resonance imaging scan. Ages ranged from newborn to 5 years. Six children were premature neonates, five were term neonates and two were 5 years old. In the premature neonates, thrombosis was usually associated with other problems. All the term neonates had seizures. In all neonates, thrombosis resolved without any specific treatment. In the two older children, one presented with pseudotumor cerebri and one with coma. These children required neurosurgical intervention. Follow-up magnetic resonance imaging scans were obtained in 9 of 13 children and showed thrombus resolution in each case. Three children were studied in the acute and convalescent stages by magnetic resonance angiography using time-of-flight techniques. Each follow-up magnetic resonance angiogram showed improvement in venous flow consistent with their clinical course and other imaging studies. We conclude that 1) CVT in children encompasses a range of clinical conditions which may or may not require neurosurgical intervention; 2) magnetic resonance imaging is superior to other modalities for the diagnosis of CVT; and 3) magnetic resonance angiography is an alternative means to monitor the evolution of CVT and efficacy of therapeutic intervention.     

Use of magnetic resonance angiography for the preoperative evaluation of patients with infrainguinal arterial occlusive disease

Purpose: This study was designed to determine whether magnetic resonance angiography (MRA) will allow preoperative management decisions without the need for contrast arteriography in patients with lower extremity ischemia caused by infrainguinal arterial occlusive disease.Methods: Forty-five patients with lower extremity ischemia in 50 limbs were evaluated by both two-dimensional time-of-flight MRA and intraarterial digital subtraction angiography (DSA) between February 1992 and June 1995. Independent management plans were based on clinical presentation, pulse volume recordings, and separate reviews of the MRA and DSA.Results: Of 50 limbs, 23 required arterial bypass, 19 percutaneous transluminal angioplasty, 5 patch angioplasty, and 3 amputation. MRA and DSA correlated exactly in 89.5% of infrainguinal arterial segments, whereas interpretations disagreed in 10.5% of arterial segments. Mismatches that had an influence on patient treatment decisions occurred in only 8 (2.3%) of 352 arterial segments. Independent MRA- and DSA-based revascularization plans agreed in 45 (90%) extremities. MRA predicted the level of arterial reconstruction in all 23 limbs that required arterial bypass. MRA identified focal stenoses amenable to percutaneous transluminal angioplasty in 18 (94.7%) of the 19 limbs that ultimately underwent percutaneous transluminal angioplasty. A strategy of preoperative planning by MRA with confirmatory intraoperative arteriography would represent a 31% cost savings per patient at our institution while eliminating the morbidity of preoperative DSA.Conclusions: When used in combination with the patient's physical examination and segmental limb pressures with plethysmography, MRA is sufficient for planning infrainguinal arterial bypass procedures and selecting patients for percutaneous transluminal angioplasty. (J Vasc Surg 1996;23:792-801.)     

Overestimation of carotid artery stenosis with magnetic resonance angiography compared with digital subtraction angiography

BACKGROUND AND PURPOSE: Three-dimensional time-of-flight (3D TOF) magnetic resonance angiography (MRA) is generally considered to overestimate the degree of stenosis in the internal carotid artery (ICA) in comparison with the reference standard intraarterial digital subtraction angiography (DSA). We evaluated whether the degree of stenosis was more accurately assessed with 3D TOF MRA if corresponding projections on MRA and DSA were compared instead of comparison of maximal stenosis at MRA with maximal stenosis at DSA. METHODS: From February 1997 to December 1999, we included 186 symptomatic and 17 asymptomatic consecutive patients suspected of having carotid artery stenosis on the basis of clinical presentation and screening with duplex ultrasound scan examination. All patients subsequently underwent DSA and MRA imaging. From each ICA, 12 maximum intensity projections with 3D TOF MRA and two or three projections with DSA were obtained. First, we compared the maximal stenosis at MRA with the maximal stenosis at DSA. Subsequently, we used the stenosis at MRA measured on the projection corresponding with the DSA projection that showed the maximal stenosis. For both strategies, the mean differences in stenosis and sensitivity and specificity for assessment of severe stenosis (70% to 99%) were calculated and compared. RESULTS: The MRA and DSA images of 354 ICAs could be compared. The sensitivity and specificity of MRA with the projection that showed the maximal stenosis were 92.6% (95% CI, 85.3% to 97.0%) and 82.7% (95% CI, 78.1% to 87.3%), respectively. The sensitivity and specificity with the MRA projection, corresponding with the DSA projection showing the maximal stenosis, were 88.3% (95% CI, 81.8% to 94.8%) and 89.6% (95% CI, 85.9% to 93.3%), respectively. The mean difference between maximal stenosis at MRA and DSA was 7.5% (95% CI, 5.2% to 9.9%). The mean difference between stenosis at MRA and DSA in corresponding projections was 0.4% (95% CI, -2.0% to 2.7%). CONCLUSION: If corresponding MRA and intraarterial DSA projections are compared, 3D TOF MRA does not overestimate carotid stenosis.     

Comparison of magnetic resonance with computed tomography angiography for preoperative localization of the Adamkiewicz artery in thoracoabdominal aortic aneurysm patients

OBJECTIVE: Preoperative localization of the Adamkiewicz artery and its segmental supplier in advance of thoracic aortic aneurysm (TAA) and thoracoabdominal aortic aneurysm (TAAA) repair is proposed to be useful to prevent postoperative paraplegia. The diagnostic potential of magnetic resonance angiography (MRA) and computed tomography angiography (CTA) was evaluated for the preoperative localization of the Adamkiewicz artery in white TAAA patients. METHODS: Thirty-nine consecutive patients with a TAA(A) scheduled for elective open surgical aortic repair preoperatively underwent MRA and CTA. Objective image quality was assessed by measuring the signal-to-noise ratio and contrast-to-noise ratio of the Adamkiewicz artery and was related to patient thickness. Two independent observers scored the location of the Adamkiewicz artery and the subjective image quality of vessel-background contrast of the Adamkiewicz artery, image noise, spinal cord tissue enhancement, epidural venous enhancement, and overall image quality. RESULTS: Average detection rate for Adamkiewicz artery localization was 71% (67% to 74%) for CTA and 97% (94% to 100%) for MRA. Interobserver agreement was 82% for CTA and 94% for MRA. Signal-to-noise ratio was significantly higher (P < .001) and contrast-to-noise ratio was significantly (P < .001) lower for CTA than for MRA. Contrast of the Adamkiewicz artery (P < .001) and overall image quality (P < .004) were judged to be significantly better for MRA. Spinal cord tissue enhancement was judged stronger at CTA (P < .03), with significantly less epidural venous enhancement (P < .001). No significant difference was found in image noise. Signal-to-noise and contrast-to-noise decreased significantly (P < .001) with increasing patient thickness for CTA but not for MRA. CONCLUSIONS: Localization of the Adamkiewicz artery in white TAAA patients is possible with both CTA and MRA. Compared with CTA, MRA is more favorable because of the higher Adamkiewicz artery detection rate, the higher contrast-to-noise ratio, and its independence of patient thickness.     

Visualizing type IV endoleak using magnetic resonance imaging with a blood pool contrast agent

Growing evidence suggests that graft porosity hampers aneurysm shrinkage in patients who have been treated with the original Excluder device. To our knowledge, this suspected porosity has never been visualized in such patients. We present three patients treated with the original Excluder device whose aneurysms did not shrink in the first 2 years after treatment. Computed tomography (CT) angiography and late phase CT did not show endoleak. We performed late phase magnetic resonance imaging with a blood pool agent to visualize graft porosity. Our cases illustrate the usability of a new contrast agent and a new imaging strategy for visualizing slow-flow endoleaks that can not be imaged using currently used imaging techniques with conventional contrast agents.     

Intraoperative assessment of aneurysm clipping using magnetic resonance angiography and diffusion-weighted imaging: technical case report

OBJECTIVE AND IMPORTANCE: To use intraoperative magnetic resonance imaging, including magnetic resonance angiography and diffusion-weighted imaging, to monitor the surgical treatment of a patient with an intracranial aneurysm. TECHNIQUE: Intraoperative imaging was performed with a ceiling-mounted, mobile, 1.5-T magnet (developed in collaboration with Innovative Magnetic Resonance Imaging Systems, Inc., Winnipeg, MB, Canada) that included high-performance 20-mT/m gradients. Pre- and postclipping, intraoperative, T1-weighted, angiographic and diffusion-weighted magnetic resonance images were obtained from a patient with an incidental, 8-mm, anterior communicating artery aneurysm. RESULTS: T1-weighted images demonstrated brain anatomic features, with visible shifts induced by surgery. Magnetic resonance angiography demonstrated the aneurysm and indicated that, after clipping, the A1 and A2 anterior cerebral artery branches were patent. Diffusion-weighted studies demonstrated no evidence of brain ischemia. CONCLUSION: For the first time, intraoperative magnetic resonance imaging has been used to monitor the surgical treatment of a patient with an intracranial aneurysm.     

Evaluation of aortoiliac aneurysm before endovascular repair: comparison of contrast-enhanced magnetic resonance angiography with multidetector row computed tomographic angiography with an automated analysis software tool

PURPOSE: The purpose of this study was to assess accuracy and reliability of a volumetric analysis of abdominal aneurysms on the basis of multidetector row computed tomographic angiography (CTA) and magnetic resonance angiography (MRA) with a commercially available automated vessel analysis software program. MATERIALS AND METHODS: Twenty patients with abdominal aortic aneurysms underwent preoperative CTA and MRA before endovascular repair. Postdeployment CTA was performed in 15 of these 20 patients (75%). All preoperative CTA and MRA and postdeployment CTA data sets were analyzed with an automated software tool. The length of the stent grafts on postdeployment CTA was measured and compared with the true length of the primary component. Two readers independently evaluated 13 vessel parameters on preoperative CTA and MRA, which are considered to be important in planning stent graft deployment. RESULTS: With the automated analysis software tool, all measurements could be performed on either CTA or MRA data sets. There was no statistically significant difference between postdeployment measurements of stent graft length on CTA and the true dimensions of the implanted stent grafts. Interobserver agreement for all of the measurements with either CTA or MRA was good to excellent (interclass coefficient, 0.71 to 0.99) with only minimal mean differences of measured dimensions between both readers (range, -2.0 to +2.3 mm, Bland-Altman). Intermodality agreement between CTA and MRA was good to excellent (interclass coefficient, 0.62 to 0.98) with small mean differences of measured dimensions between both methods (range, -4.1 to +2.1 mm, Bland-Altman). CONCLUSION: Volumetric measurement with an automated analysis software tool allows a fast, precise, and reliable noninvasive preoperative determination of all aortic dimensions on the basis of either CTA or MRA data sets.     

Factors associated with elimination of type II endoleak during the first year after endovascular aneurysm repair

ObjectiveThe natural history of endoleak type II (ET II) after endovascular aneurysm repair (EVAR) is still debatable. The aim of this study was to examine the presence of preoperative and postoperative factors associated with persistence of ET II during the initial 12-month follow-up period.MethodsA two-center retrospective study including patients subjected to EVAR from 2006 to 2017 was undertaken. Patients with ET II at 1-month computed tomography angiography (CTA) were categorized into two groups, resolution (group 1) vs persistence (group 2) of ET II at 12-month CTA. Preoperative demographics, comorbidities, aneurysm anatomic details, and pelvic artery index were assessed. Intraoperative details were also recorded.ResultsOf 825 patients, 140 (17%) patients (mean age, 71.7 ± 8.5 years; 94% male) presented with ET II at 1-month CTA. Group 1 included 58 patients (41%) and group 2, 82 patients (59%). The anatomic characteristics of the inferior mesenteric artery and lumbar arteries and the pelvic artery indices were not associated with ET II persistence. All patients in group 1 had presence of intraluminal thrombus (ILT) on preoperative CTA (group 1, 100%; group 2, 67%; P = .001), and the circular pattern of ILT was more common in group 1 (group 1, 44%; group 2, 24%; P = .01). At 12-month CTA, the mean sac regression was higher in group 1 (group 1, −3 ± 4 mm; group 2, 0.55 ± 3 mm; P = .000). After multivariate analysis, persistence of ET II was directly associated only with intraoperative internal iliac occlusion (odds ratio [OR], 0.232; 95% confidence interval [CI], 0.06-0.86; P = .03) and inversely with statin therapy (OR, 2.6; 95% CI, 1.01- 6.8; P = .047) and sac regression (OR, 1.24; 95% CI, 1.11-1.39; P = .001).ConclusionsInduced occlusion of the internal iliac artery during EVAR was the only factor associated with persistence of ET II during the first year after EVAR. The presence and pattern of ILT may play a role in ET II persistence, whereas the number of patent infrarenal aortic branches and their diameter as well as the pelvic artery indices were not associated with ET II. The use of statins may have a positive effect on ET II resolution during the first postoperative year. Sac diameter is more likely to regress in patients with ET II resolution.