Advances in determining abdominal aortic aneurysm size and growth

Table 1 Summary of studies comparing between various Dmax measurements

Ref.	Journal, yr	Variables	Main results	Highlights
Lederle et al[31]	J Vasc Surg, 1995	US, CTaxial	US smaller than CTaxial an average of 0.27 cm	Difference < 0.2 cm in 44% and > 0.5 cm in 33% of patients
Jaakkola et al[23]	Eur J Vasc Endovasc Surg, 1996	US, CTaxial	Mean AAA anteroposterior CTaxial-US difference was 2.6 ± 3.9 mm. Mean transverse difference was 0.8 ± 4.4	Interobsever differences < 5 mm in 84% of the US and 91% of the CTaxial recordings
Wanhainen et al[32]	Eur J Vasc Endovasc Surg, 2002	US, CTaxial	In AAAs the mean diameter did not differ significantly	95% of differences between US and CTaxial are expected to be < 8.0 mm in anteroposterior and < 10.6 mm in transverse measurements
Sprouse et al[33]	J Vasc Surg, 2003	US, CTaxial	CTaxial (5.69 ± 0.89 cm) significantly larger than US (4.74 ± 0.91 cm)	Strong correlation between CTmax and US (r = 0.705), but difference < 1.0 cm in only 51% of cases
Singh et al[34]	Eur J Vasc Endovasc Surg, 2004	US, CTaxial	Total: US smaller by -0.11 mm, aortas < 30 mm: US smaller by -0.64 mm, aortas 30-39 mm: CT smaller by 0.67 mm, aortas > 40 mm: CT smaller 1.09 mm	Differences > 5 mm are expected in 8% of patients. Variability increases with increasing diameter
Sprouse et al[35]	Eur J Vasc Endovasc Surg, 2004	US, CTaxial CTorth	Mean CTaxial (58.0 mm) significantly larger than USmax (53.9 mm) or CTorth (54.7 mm). Insignificant difference between US and Dorth	When aortic angulation was < 25°, Daxial (55.3 mm), US (54.3 mm), and Dorth (54.1 mm) were similar. When aortic angulation was > 25°, Daxial (60.1 mm) was significantly larger than US (53.8 mm) and Dorth (55.0 mm)
Manning et al[36]	J Vasc Surg, 2009	US, CTaxial, CTorth	US smaller than CTaxial by 9.6 mm and CTorth by 7.3 mm	Of all CT recordings, diameter perpendicular to the maximal ellipse on axial sections most closely approximates the findings of US and therefore this most closely approximates criteria used in the UKSAT
Foo et al[37]	Eur J Vasc Endovasc Surg, 2011	US, CTorth	US underestimated AAA size compared to CTorth by a mean difference of 0.21 (± 0.39) cm	Limits of agreement were -0.55 to 0.96 cm, exceeding clinical acceptability. 70% of patients with US < 5.5 cm presented CTorth > 5.5 cm
Kontopodis et al[38]	Eur J Radiol, 2013	CTaxial, CTorth	CTaxial greater than CT orth by 2 mm (range: 0-12.3 mm)	20% of the CTs presented Daxial above and Dorth below 5.5 cm which is threshold for repair. Growth rates should be determined with either axial or orthogonal technique not interchanging between methods

AAA: Abdominal aortic aneurysm; CT: Computed tomography; CTorth: Orthogonal maximum diameter measured from CT images; CTaxial: Axial maximum diameter measured from CT images; US: Ultrasonography.

Table 2 Summary of studies comparing between orthogonal diameter computed tomography and volume measurements

Ref.	Journal, yr	Population	Definition of size-change	Main results
Wever et al[45]	Eur J Vasc Endovasc Surg, 2000	Post-EVAR	LOAs	37%, discordance Dmax and volume measurements. A decrease in aneurysm size was missed using Dmax in 14% of cases and an increase in 19% of cases
Prinssen et al[46]	Eur J Vasc Endovasc Surg, 2003	Post-EVAR	NA	Volume data resulted in more "good/wait" while Diameter data resulted in more "not good/further diagnostics"-decisions
Kritpracha et al[42]	JEVT, 2004	Post-EVAR	10% for volume, 5 mm for diameter	Volume changed in 81% of studies (15% increase and 66% decrease). Dmax changed 57% (4% increase and 53% decrease). Among 20 studies with increased volume, Dmax increased in only 5
van Keulen et al[43]	J Endovasc Ther, 2009	Post-EVAR	5% for volume, 5 mm for diameter	Volumetry detected aneurysm growth in 24% and shrinkage in 54% of patients, which was reflected by Dmax in 10.6% and 28% respectively
Parr et al[40]	Eur J Radiol, 2011	Small AAAs	LOAs	42% of patients who had increased aortic volume did not display corresponding diameter changes
Kauffmann et al[41]	Eur J Radiol, 2012	Small AAAs	LOAs	4/28 (14.3%) patients presented volume increase which was not reflected in Dmax
Kontopodis et al[44]	Eur J Radiol, 2014	Small AAAs	LOAs	18% of patients who had increased aortic volume did not display corresponding diameter changes. AAAs presenting rapid volume increase had a 10-fold risk to be operated, while the risk was 3-fold for rapid Dmax increase

LOAs: Limits of agreement; AAA: Ab dominal aortic aneurysm; EVAR: Endovascular aneurysm repair; NA: Not available.