Accurate assessment of abdominal aortic aneurysm with intravascular ultrasound scanning: validation with computed tomographic angiography

ACR Appropriateness Criteria® Pulsatile Abdominal Mass, Suspected Abdominal Aortic Aneurysm: 2023 Update

Abdominal aortic aneurysm (AAA) is defined as abnormal dilation of the infrarenal abdominal aortic diameter to 3.0 cm or greater. The natural history of AAA consists of progressive expansion and potential rupture. Although most AAAs are clinically silent, a pulsatile abdominal mass identified on physical examination may indicate the presence of an AAA. When an AAA is suspected, an imaging study is essential to confirm the diagnosis. This document reviews the relative appropriateness of various imaging procedures for the initial evaluation of suspected AAA. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Diagnostic approach to peripheral arterial disease

This article discusses diagnostic imaging techniques used in the evaluation and management of patients with peripheral arterial disease (PAD). Along with a complete vascular examination, noninvasive physiologic testing is used for the initial evaluation of patients with suspected PAD. Duplex ultrasonography provides information on the degree of stenosis or occlusion within a vessel and allows assessment of the vessel wall and plaque morphology. Angiographic imaging techniques should be reserved for determining the optimal endovascular or surgical approach for patients requiring revascularization. Together, all available diagnostic modalities contribute to successful evaluation and management of patients with PAD.

Advances in vascular imaging

Advances in vascular surgery have mirrored advances in diagnostic imaging. Indeed, the endovascular revolution has been made possible largely by advances in computed tomography, magnetic resonance imaging, and vascular ultrasound. As technology allows better noninvasive vascular diagnosis, conventional angiography, once the gold standard for the diagnosis of vascular disease, is now reserved largely for intervention. This article discusses the current state of vascular imaging. Specific emphasis is placed on the comparative clinical utility of different imaging modalities in the detection and management of vascular disease.

Endoluminal AAA repair using intravascular ultrasound for graft planning and deployment: a 2-year community-based experience

PURPOSE

To examine the effectiveness of intravascular ultrasound (IVUS) and digital subtraction angiography (DSA) for preoperative planning and intraoperative deployment of stent-grafts to treat abdominal aortic aneurysms.

METHODS

One hundred seventy patients (143 men; mean age 73.6+/-7.2 years, range 51-89) underwent successful DSA and IVUS to determine suitability for stent-graft repair. Patients subsequently received the AneuRx (n=157) or Ancure (n=13) device; intraprocedural IVUS was used to survey the proximal endograft for proper apposition to the aortic wall.

RESULTS

Reliable preoperative IVUS measurements were obtained in all patients. Plaque morphology was assessed in 140 (82.3%) aortic necks; in 36 (25.7%), preoperative IVUS showed high-grade atherosclerotic plaque in the nonaneurysmal abdominal aortic neck. The procedure was successful in 168 (98.8%) cases (1 [0.6%] acute conversion and 1 access failure). There were 2 (1.2%) periprocedural deaths related to bowel ischemia. Four (2.3%) patients developed graft occlusion/kinking and 2 (1.2%) developed renal failure requiring dialysis within 30 days. Multivariate logistic regression analysis revealed that female gender (p=0.0247), a short nonaneurysmal aortic neck (p=0.0185), and presence of high-grade atherosclerotic plaque (p=0.0185) correlated with major acute complications. Over a mean 10.4-month follow-up (range 1-25), 11 patients died of unrelated causes; there was no known AAA rupture or device failure. The Kaplan-Meier estimate of survival at 1 year was 91.0%+/-2.8%. Sixteen (9.4%) patients underwent 17 secondary procedures for endoleak or graft limb occlusion at a mean 5.4 months after stent-graft repair (freedom from secondary intervention at 1 year 86.5%+/-3.2%).

CONCLUSIONS

Our findings suggest that IVUS may identify patients at increased risk of major adverse complications following endovascular repair. The combination of IVUS and DSA for endoluminal stent-graft planning and placement provides excellent short- and mid-term patient outcomes.

Intravascular ultrasound aids in the performance of endovascular repair of abdominal aortic aneurysm

PURPOSE

The purpose of this retrospective review was to assess the accuracy of aortic measurements with intravascular ultrasound scan (IVUS) compared with computed tomographic (CT) scan and to assess the role of IVUS in the performance of endovascular repair of abdominal aortic aneurysms (AAAs).

METHODS

Seventy-eight patients undergoing repair of AAA with the AneuRx stent graft (Medtronic AVE, Inc, Santa Rosa, Calif) underwent measurement with CT scan and IVUS. The initial selection of stent graft size was made on the basis of the CT scan measurements, but the final decision for size was made on the basis of the IVUS measurements. Standard measurements of a phantom tube obtained with IVUS, CT scan, and digital caliper were also compared.

RESULTS

IVUS measurements of the phantom standard agreed closely with CT scan measurements. However, stent graft size initially selected with CT measurement was altered in 28% of cases on the basis of intraoperative IVUS measurements. No type I endoleaks were encountered in our series, and no aortic cuffs were necessary for endoleak repair.

CONCLUSION

IVUS accurately measures the aorta for selection of stent grafts for endovascular repair of AAA and may prevent type I endoleaks and remedial procedures for their repair.

Endovascular versus conventional open repair of acute abdominal aortic aneurysm: feasibility and preliminary results

PURPOSE

To evaluate the feasibility of endovascular treatment of acute abdominal aortic aneurysm (AAA) with commercially prepared bifurcated systems.

METHODS

From January through July 2001, 22 patients (17 men; mean age 73.6 years, range 59-89) were referred with an acute (symptomatic/ruptured) AAA. Six patients were treated with emergent open surgery because of hemodynamic instability, but the other 16 patients underwent computed tomographic angiography with multidirectional reconstruction. Six (27%) aneurysms were suitable for endovascular repair (EVR) and were successfully treated. Procedural variables, morbidity, and mortality were compared between the EVR group and 6 patients of equivalent hemodynamic status from among the conventionally treated patients.

RESULTS

There was no mortality in either group. The median aneurysm diameter in the EVR group was 63 mm (range 48-84) versus 80 mm (45-82) in the matched surgically treated AAAs (p=0.628). Procedural duration was 193 minutes (150-265) for the EVR group compared to 203 minutes (130-270) for the matched group (p=0.630). Median blood loss was significantly less (p=0.010) in the EVR group (125 versus 3400 mL). Median length of stay (LOS) in intensive care was 8 hours (0-21) versus 62 hours (48-112) for the surgical group (p=0.004). Hospital LOS was significantly reduced (p=0.024) for the EVR patients (7.5 [2-16] versus 15.5 [10-34] days).

CONCLUSIONS

Endovascular treatment of acute aneurysm is feasible, and preliminary results are promising.

Using three-dimensional rotational angiography for sizing of covered stents

OBJECTIVE

The purpose of our study was to determine the value of three-dimensional (3D) rotational angiography in the assessment of patients to be treated with covered stents for peripheral arterial aneurysms.

CONCLUSION

Our preliminary experience suggests that 3D rotational angiography appears to be a valid tool in the pre- and perprocedural assessment of patients treated endovascularly for arterial aneurysms.

Accuracy of intravascular ultrasound for diameter measurement of phantom arteries

BACKGROUND

Uniplanar quantitative angiography (QA) is the standard method for measuring vessel diameter during surgical and endovascular procedures. Intravascular ultrasound (IVUS), a relatively new technology, is another means of obtaining this measurement. This study was designed to validate the accuracy of these two modalities by comparing each to direct caliper measurement, the gold standard, using phantom femoral artery segments (PAS).

MATERIALS AND METHODS

PAS diameter was measured with a 12.5-MHz mechanically rotating IVUS catheter (Boston Scientific Corp.) and QA (OEC Corp.) was compared to the direct caliper measurement (Mitutoyo Corp.) at 60 different locations within PAS. At each location minimal lumen diameter and perpendicular lumen diameter were measured and their mean was calculated. The intraclass correlation coefficients (ICCC) between direct caliper measurement and IVUS and uniplanar and biplanar angiography were calculated. Fisher's Z transformation was used to compare the correlation coefficients.

RESULTS

The ICCC for IVUS was 0.89. The ICCCs for uniplanar and biplanar angiography were 0.73 and 0.82, respectively. IVUS correlated more closely with direct caliper measurement than uniplanar and biplanar angiography (P = 0.00008, 0.02) Biplanar angiography correlated more closely with direct caliper measurement than uniplanar angiography (P = 0.04).

CONCLUSIONS

IVUS more accurately measures lumen diameter than uniplanar or biplanar angiography. Diameter measurement with biplanar angiography is more accurate than uniplanar angiography.

Prediction of aortoiliac stent-graft length: comparison of measurement methods

PURPOSE

To determine the accuracy of helical computed tomography (CT), projectional angiography derived from CT angiography, and intravascular ultrasonographic withdrawal (IUW) length measurements for predicting appropriate aortoiliac stent-graft length.

MATERIALS AND METHODS

Helical CT data from 33 patients were analyzed before and after endovascular repair of abdominal aortic aneurysm (Aneuryx graft, n = 31; Excluder graft, n = 2). The aortoiliac length of the median luminal centerline (MLC) and the shortest path (SP) that remained at least one common iliac arterial radius away from the vessel wall were calculated. Conventional angiographic measurements were simulated from CT data as the length of the three-dimensional MLC projected onto four standard viewing planes. These predeployment lengths and IUW length, available in 24 patients, were compared with the aortoiliac arterial length after stent-graft deployment.

RESULTS

The mean error values of SP, MLC, the maximum projected MLC, and IUW were -2.1 mm +/- 4.6 (SD) (P =.013), 9.8 mm +/- 6.8 (P <.001), -5.2 mm +/- 7.8 (P <.001), and -14.1 mm +/- 9.3 (P <.001), respectively. The preprocedural prediction of the postprocedural aortoiliac length with the SP was significantly more accurate than that with the MLC (P <.001), maximum projected MLC (P <.001), and IUW (P <.001).

CONCLUSION

The shortest aortoiliac path length maintaining at least one radius distance from the vessel wall most accurately enabled stent-graft length prediction for 31 AneuRx and two Excluder stent-grafts.

Three-dimensional intravascular ultrasound assessment of abdominal aortic aneurysm necks

PURPOSE

To document the accuracy of an automated analysis system for measuring lumen diameter and neck lengths of abdominal aortic aneurysms (AAAs) from intravascular ultrasound (IVUS) images and to describe additional features associated with 3-dimensional (3D) IVUS imaging.

METHODS

Twenty-two aortic aneurysms were studied with IVUS. Lumen diameters obtained using the automated analysis system were compared with manual measurements from axial IVUS scans, as were neck lengths obtained using automated analysis versus those measured with the aid of a displacement sensing device. Automated analyses were repeated by a second observer. Agreement was expressed as the coefficient of variation (CV).

RESULTS

Twenty proximal aortic, 6 distal aortic, and 3 iliac necks were available for analysis. Comparison between automated analysis and manual measurements for lumen diameter revealed a difference of 0.45 +/- 0.42 mm (mean +/- SD, Pearson's r = 0.99, p < 0.001, CV = 2.1%) and a difference of 0.05 +/- 0.12 cm (r = 0.99, p = 0.04, CV = 4.1%) for neck length. Interobserver difference for lumen diameter was 0.13 +/- 0.66 mm (r = 0.99, p < 0.001, CV = 3.4%) and 0.05 +/- 0.11 cm for length measurements (r = 0.99, p = 0.02, CV = 3.5%). The 3D IVUS imaging facilitated the identification of neck configuration.

CONCLUSIONS

Automated analysis of IVUS images allows accurate measurement of the lumen diameter of proximal and distal AAA necks and gives length measurements comparable to those of manual analysis. Longitudinal display of IVUS images aids in the elucidation of neck anatomy.