ACR Appropriateness Criteria ® Abdominal Aortic Aneurysm: Interventional Planning and Follow-Up

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.

ACR Appropriateness Criteria® Thoracoabdominal Aortic Aneurysm or Dissection: Treatment Planning and Follow-Up

As the incidence of thoracoabdominal aortic pathology (aneurysm and dissection) rises and the complexity of endovascular and surgical treatment options increases, imaging follow-up of patients remains crucial. Patients with thoracoabdominal aortic pathology without intervention should be monitored carefully for changes in aortic size or morphology that could portend rupture or other complication. Patients who are post endovascular or open surgical aortic repair should undergo follow-up imaging to evaluate for complications, endoleak, or recurrent pathology. Considering the quality of diagnostic data, CT angiography and MR angiography are the preferred imaging modalities for follow-up of thoracoabdominal aortic pathology for most patients. The extent of thoracoabdominal aortic pathology and its potential complications involve multiple regions of the body requiring imaging of the chest, abdomen, and pelvis in most patients. The ACR 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.

Appropriateness of surgery performed for abdominal aortic aneurysm at tertiary hospitals in Spain

BACKGROUND

To analyze the appropriateness of the type of repair (open or endovascular) performed for abdominal aortic aneurysm (AAA) in five university hospitals in Spain, according to evidence-based recommendations.

METHODS

A multicenter, retrospective cross-sectional study of patients with AAA who underwent elective open surgical repair (OSR) or endovascular aneurysm repair (EVAR). Data were collected on demographic and clinical variables and type of surgical repair. A pair of vascular surgeons from each participating hospital performed a blinded assessment based on GRADE recommendations. The concordance between the two evaluators and the agreement between their evidence-based recommendation and the procedure actually performed were assessed.

RESULTS

A total of 186 patients were selected; 179 were included. Mean age was 72.5 years (standard deviation [SD], 8.4), mean Charlson Comorbidity Index (CCI) was 2.04 (SD, 1.9). OSR was performed in 53.2% (n=99) and EVAR in 46.8% (n=87) of cases. Overall, 65.9% (118/179) of interventions performed were considered appropriate: 50% (47/94) of OSRs and 83.5% (71/85) of EVARs. The patient characteristics were similar for all the hospitals, but the chosen surgical technique did show significant differences among these centers. There were no significant differences among the hospitals in the proportion of cases judged as appropriate, either overall (p=0.346) or for each type of procedure (p=0.531 and p=0.538 for OSR and EVAR, respectively).

CONCLUSIONS

In this study, the majority of the AAA repairs performed were appropriate according to GRADE recommendations. A higher proportion of EVARs were considered appropriate than OSRs. Choice of AAA repair should be standardized through the use of evidence-based clinical practice guidelines, while incorporating patient preferences, to reduce the existing variability and ensure appropriate selection of AAA repair technique.

ACR Appropriateness Criteria® Nontraumatic Aortic Disease

Nontraumatic aortic disease can be caused by a wide variety of disorders including congenital, inflammatory, infectious, metabolic, neoplastic, and degenerative processes. Imaging examinations such as radiography, ultrasound, echocardiography, catheter-based angiography, CT, MRI, and nuclear medicine examinations are essential for diagnosis, treatment planning, and assessment of therapeutic response. Depending upon the clinical scenario, each of these modalities has strengths and weaknesses. Whenever possible, the selection of a diagnostic imaging examination should be based upon the best available evidence. 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 include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment. The purpose of this document is to assist physicians select the most appropriate diagnostic imaging examination for nontraumatic aortic diseases.

Collard M, Sutphin PD, Kalva SP, Majdalany BS, Collins JD, Eldrup-Jorgensen J, Francois CJ, Ganguli S, Gunn AJ, Kendi AT, Khaja MS, Obara P, Reis SP, Vijay K, Dill KE. ACR Appropriateness Criteria® Abdominal Aortic Aneurysm Follow-up (Without Repair)

Abdominal aortic aneurysm (AAA) is defined as aneurysmal dilation of the abdominal aorta to 3 cm or greater. A high degree of morbidity and mortality is associated with AAA rupture, and imaging surveillance plays an essential role in mitigating the risk of rupture. Aneurysm size and growth rate are factors associated with the risk of rupture, thus surveillance imaging studies must be accurate and reproducible to characterize aneurysm size. Ultrasound, CT angiography, and MR angiography provide an accurate and reproducible assessment of size, while radiographs and aortography provide limited evaluation. 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 include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Dynamic Volumetric Computed Tomography Angiography Is a Preferred Method for Unclassified Endoleaks by Conventional Computed Tomography Angiography After Endovascular Aortic Repair

Background

The aim of this study was to assess the feasibility and safety of dynamic volumetric computed tomography angiography (DV‐CTA) for endoleaks detected but not classified by conventional CTA in patients after endovascular aortic repair.

Methods and Results

From January 2016 to October 2017, 24 patients with endoleaks with aneurysm sac enlargement detected but not classified by conventional CTA were randomly assigned to the conventional CTA group and the DV‐CTA group for further evaluation. The amount of contrast agent, radiation dosage, and changes in creatinine during the operation were compared between the 2 groups. Reintervention was performed according to the endoleak classification followed by the 6‐ and 12‐month follow‐up. The accuracy of classifying endoleaks by DV‐CTA was comparable to that by digital subtraction angiography. Additionally, the total amount of contrast agent and the radiation dosage in the DV‐CTA group during the operation were diminished by 14.0% (P=0.007) and 12.1% (P=0.004), respectively, compared with those in the conventional CTA group. No contrast‐induced nephropathy was observed. All endoleaks were treated instantly after identification. No endoleaks were found in any of the patients during follow‐up.

Conclusions

DV‐CTA could replace digital subtraction angiography as an alternative method for the classification of endoleaks that cannot be differentiated by conventional CTA. Additionally, the amount of contrast agent and the total radiation dosage were substantially reduced, which improved safety among operators and patients.

Intermodality feature fusion combining unenhanced computed tomography and ferumoxytol-enhanced magnetic resonance angiography for patient-specific vascular mapping in renal impairment

OBJECTIVE

The purpose of this study was to establish the feasibility of fusing complementary, high-contrast features from unenhanced computed tomography (CT) and ferumoxytol-enhanced magnetic resonance angiography (FE-MRA) for preprocedural vascular mapping in patients with renal impairment.

METHODS

In this Institutional Review Board-approved and Health Insurance Portability and Accountability Act-compliant study, 15 consecutive patients underwent both FE-MRA and unenhanced CT scanning, and the complementary high-contrast features from both modalities were fused to form an integrated, multifeature image. Source images from CT and MRA were segmented and registered. To validate the accuracy, precision, and concordance of fused images to source images, unambiguous landmarks, such as wires from implantable medical devices or indwelling catheters, were marked on three-dimensional (3D) models of the respective modalities, followed by rigid co-registration, interactive fusion, and fine adjustment. We then compared the positional offsets using pacing wires or catheters in the source FE-MRA (defined as points of interest [POIs]) and fused images (n = 5 patients, n = 247 points). Points within 3D image space were referenced to the respective modalities: x (right-left), y (anterior-posterior), and z (cranial-caudal). The respective 3D orthogonal reference axes from both image sets were aligned, such that with perfect registration, a given point would have the same (x, y, z) component values in both sets. The 3D offsets (Δx mm, Δy mm, Δz mm) for each of the corresponding POIs represent nonconcordance between the source FE-MRA and fused images. The offsets were compared using concordance correlation coefficients. Interobserver agreement was assessed using intraclass correlation coefficients and Bland-Altman analyses.

RESULTS

Thirteen patients (aged 76 ± 12 years; seven female) with aortic valve stenosis and chronic kidney disease and two patients with thoracoabdominal vascular aneurysms and chronic kidney disease underwent FE-MRA for preprocedural vascular assessment, and unenhanced CT examinations were available in all patients. No ferumoxytol-related adverse events occurred. There were 247 matched POIs evaluated on the source FE-MRA and fused images. In patients with implantable medical devices, the mean offsets in spatial position were 0.31 ± 0.51 mm (ρ = 0.99; Cb = 1; 95% confidence interval [CI], 0.99-0.99) for Δx, 0.27 ± 0.69 mm (ρ = 0.99; Cb = 0.99; 95% CI, 0.99-0.99) for Δy, and 0.20 ± 0.59 mm (ρ = 1; Cb = 1; 95% CI, 0.99-1.00) for Δz. Interobserver agreement was excellent (intraclass correlation coefficient, >0.99). The mean difference in offset between readers was 1.5 mm.

CONCLUSIONS

Accurate 3D feature fusion is feasible, combining luminal information from FE-MRA with vessel wall information on unenhanced CT. This framework holds promise for combining the complementary strengths of magnetic resonance imaging and CT to generate information-rich, multifeature composite vascular images while avoiding the respective risks and limitations of both modalities.

Surveillance of abdominal aortic aneurysm using accelerated 3D non-contrast black-blood cardiovascular magnetic resonance with compressed sensing (CS-DANTE-SPACE)

BACKGROUND

3D non-contrast high-resolution black-blood cardiovascular magnetic resonance (CMR) (DANTE-SPACE) has been used for surveillance of abdominal aortic aneurysm (AAA) and validated against computed tomography (CT) angiography. However, it requires a long scan time of more than 7 min. We sought to develop an accelerated sequence applying compressed sensing (CS-DANTE-SPACE) and validate it in AAA patients undergoing surveillance.

METHODS

Thirty-eight AAA patients (all males, 73 ± 6 years) under clinical surveillance were recruited for this study. All patients were scanned with DANTE-SPACE (scan time 7:10 min) and CS-DANTE-SPACE (scan time 4:12 min, a reduction of 41.4%). Nine 9 patients were scanned more than 2 times. In total, 50 pairs of images were available for comparison. Two radiologists independently evaluated the image quality on a 1-4 scale, and measured the maximal diameter of AAA, the intra-luminal thrombus (ILT) and lumen area, ILT-to-muscle signal intensity ratio, and the ILT-to-lumen contrast ratio. The sharpness of the aneurysm inner/outer boundaries was quantified.

RESULTS

CS-DANTE-SPACE achieved comparable image quality compared with DANTE-SPACE (3.15 ± 0.67 vs. 3.03 ± 0.64, p = 0.06). There was excellent agreement between results from the two sequences for diameter/area and ILT ratio measurements (ICCs> 0.85), and for quantifying growth rate (3.3 ± 3.1 vs. 3.3 ± 3.4 mm/year, ICC = 0.95.) CS-DANTE-SPACE showed a higher ILT-to-lumen contrast ratio (p = 0.01) and higher sharpness than DANTE-SPACE (p = 0.002). Both sequences had excellent inter-reader reproducibility for quantitative measurements (ICC > 0.88).

CONCLUSION

CS-DANTE-SPACE can reduce scan time while maintaining image quality for AAA imaging. It is a promising tool for the surveillance of patients with AAA disease in the clinical setting.