Study Population

Consecutive adult patients (age ≥ 18 years) with BAV ( N = 53) who underwent both TTE and CTA imaging for aortic assessment within 6 months were retrospectively identified between 2006 and 2012. All TTE and CTA studies were measured de novo by experts. The study protocol was approved by the institutional review board.

TTE Imaging

TTE studies were performed on commercially available ultrasound systems (Vivid 7 [GE Healthcare, Milwaukee, WI] and iE33 [Philips Medical Systems, Andover, MA]). Studies were remeasured offline at both end-diastole and where best seen during systole using the two methods of edge selection in the parasternal LAX and short-axis (SAX) views ( Figure 1 ): (1) sinuses (LAX and SAX) and (2) Asc-Ao (LAX only). For the sinuses SAX measurement, the outer leading edge chosen was the right coronary sinus, which is perpendicular to the ultrasound beam (and thus has the best lumen-wall interface definition), measuring sinus to sinus (right to non and right to left), followed by a third non-to-left sinus measurement ( Figure 1 ). An additional “timing of measurement” was used for SAX sinuses measurement only: mid-diastole ( Figure 1 ). The Asc-Ao was defined as the largest clearly visualized dimension at approximately ≥2 cm above the sinotubular junction. To evaluate interobserver agreement, measurements were repeated by a second expert reader on a randomly selected subset of 19 patients. The term conventional method refers to TTE LAX L-L aortic measurement in end-diastole.

Schematic of TTE sinuses and Asc-Ao diameter acquisition. Ascending aortic diameters at the level of the sinuses (1) and Asc-Ao (2) where best visualized during systole by leading edge (A and B) and inner edge (C and D) . Ascending aortic diameters at the level of the sinuses and Asc-Ao during end-diastole by leading edge (E and F) and inner edge (G and H) . Ascending aortic diameters at the level of sinuses in SAX view where best visualized during systole by leading edge and inner edge (I and J) , mid-diastole by leading edge and inner edge (K and L) , and end-diastole by leading edge (M) . L , Left coronary sinus; LA , left atrium; LV , left ventricle; N , non-coronary sinus; R , right coronary sinus.

CTA Imaging

CTA imaging of the chest was performed using multislice dual-energy computed tomographic scanners (Siemens, Forchheim, Germany). Axial images 1 to 2 mm thick, reconstructed in a diastolic phase, were exported into dedicated reformatting software (Aquarius Intuition; TeraRecon, Foster City, CA) and used for analysis. The locations of maximum caliber of the sinuses and Asc-Ao were determined using multiplanar reformatting. A SAX image of the Asc-Ao perpendicular to the direction of blood flow was made using double-oblique reformatting at the site of maximum Asc-Ao caliber. Measurements of the maximum Asc-Ao diameter were made on this reformatted SAX image. A second measurement of the Asc-Ao caliber 90° perpendicular to the measurement of maximum diameter was also made on the SAX image ( Figure 2 ). Thus, Asc-Ao measurements were (1) maximum and (2) perpendicular to maximum.

CTA sinuses and Asc-Ao measurements. Diameter measurement at the level of the sinuses in three-chamber view (A) , multiplanar sinuses maximum reformatted SAX measurement (B) and Asc-Ao diameters on reformatted SAX view demonstrating maximum dimension and Asc-Ao diameter 90° perpendicular to maximum diameter (perpendicular-to-maximum) (C) . Note a 10-mm difference between the three-chamber view (A) and maximum view for the sinuses (B) .

A SAX image of the sinuses perpendicular to the direction of blood flow was made using double-oblique reformatting at the site of maximum sinuses caliber. The maximum sinuses diameter was measured on this SAX image, from sinus to sinus. The sinuses were also measured in a three-chamber view of the left ventricle (analogous to the TTE parasternal LAX view) created using multiplanar reformatting ( Figure 2 ). Thus, sinuses measurements were (1) maximum and (2) three-chamber view.

Measurements were made using the O-O method as per institutional protocol but also the I-I method for research purposes. To evaluate interobserver agreement, measurements were repeated by a second expert reader on a randomly selected subset of 19 patients.

Statistical Analysis

Continuous data are expressed as mean ± SD with ranges provided when appropriate. Comparisons between measurements were assessed using Lin concordance correlation coefficients and Bland-Altman plots. Assessment of interobserver variability was performed offline on the same images. Statistical analyses were performed using SAS version 9.3 (SAS Institute, Cary, NC) and R version 3.0.2 (R Foundation for Statistical Computing, Vienna, Austria).

Baseline Characteristics

Baseline characteristics are shown in Table 1 . Of 53 patients, 39 were men (74%). The mean age was 54 ± 14 years (range, 25–82 years). Forty patients (75%) had fusion of the right and left coronary cusps, 10 (19%) fusion of the right and noncoronary cusps, and one (2%) had fusion of the left and noncoronary cusps. Two patients (4%) were subsequently determined to have unicuspid aortic valves but were included because they were initially identified as having BAV, and unicuspid patients share significant natural history similarities with those with BAV, including aortopathy. Thirty-four patients (64%) had aortic stenosis, while 38 patients (72%) had aortic regurgitation. Mean time from TTE imaging to CTA imaging was 12 ± 29 days.

Aortic Measurements by Imaging Modality and Measuring Method

TTE Imaging

Assessment of the Asc-Ao and sinuses LAX by TTE imaging in systole allowed the best qualitative visualization of their dimensions (compared with end-diastole); nonetheless, all 53 patients had measurable images by either method. Assessment of the sinuses SAX by TTE imaging at mid-diastole allowed the best qualitative visualization of their SAX dimension (46 patients [87%] had measureable images), compared with systole (42 [79%]) and end-diastole (36 [68%]).

All systolic L-L Asc-Ao and sinuses LAX diameters were larger than those obtained at end-diastole by either the I-I or the L-L method ( P < .0001), with the exception of the mid-diastole L-L sinuses SAX, which was larger than the all sinuses LAX measurements ( P < .001) ( Table 2 ). The maximum aortic diameters measured by TTE imaging were systolic L-L Asc-Ao (43.8 ± 7.5 mm) and mid-diastolic L-L sinuses SAX (42.5 ± 7 mm). By the conventional measurement method (LAX end-diastolic L-L), the sinuses were dilated (≥45 mm) in 8 patients (15%), which increased to 11 patients (21%) by LAX systolic L-L measurement and to 16 (35%) by SAX mid-diastolic L-L measurement ( Table 3 ). Similarly but less marked, by the conventional method, the Asc-Ao was dilated (≥45 mm) in 26 patients (49%), which increased to 27 patients (51%) with LAX systolic L-L.

Table 2

Mean sinuses and mid-ascending aortic measurements by TTE and electrocardiographically gated CTA imaging

	Mean ± SD			Mean ± SD of paired difference			P
	Mid-diastole	End-diastole	Systole	Mid-diastole − end-diastole	Mid-diastole − systole	End-diastole − systole
Sinuses LAX L-L		39.4 ± 6.8	40.4 ± 6.9			−1 ± 1.4	<.0001
Sinuses LAX I-I		37.7 ± 6.8	38.7 ± 6.9			−1 ± 1.3	<.0001
Sinuses SAX L-L	42.5 ± 7.0	40.7 ± 6.7	41.8 ± 7.4	1.2 ± 2	−0.1 ± 1	−1.2 ± 1.6	<.0001
Sinuses SAX I-I	39.1 ± 6.7		39.0 ± 7.2		−0.4 ± 0.9		.00187
Asc-Ao L-L		42.6 ± 7.4	43.8 ± 7.5			−1.2 ± 1.6	<.0001
Asc-Ao I-I		41.1 ± 7.4	42.3 ± 7.3			−1.2 ± 1.7	<.0001

	Mean ± SD		Mean ± SD of paired difference	P
	Maximum	Three-chamber or perpendicular	Maximum − three-chamber/perpendicular
Sinuses O-O	44.7 ± 7.0	40.5 ± 6.9	4.3 ± 2.4	<.0001
Sinuses I-I	42.6 ± 7.0	38.2 ± 6.8	4.4 ± 2.3	<.0001
Asc-Ao O-O	45.2 ± 7.6	44.0 ± 7.7	1.2 ± 0.9	<.0001
Asc-Ao I-I	43.3 ± 7.5	41.8 ± 7.5	1.4 ± 0.9	<.0001

Table 3

Classification of aortic dilatation by different modalities and measurement methods

	Total	n (%)
Sinuses diameter < 40 mm
Systole LAX L-L	53	24 (45)
End-diastole LAX L-L	53	28 (53)
Systole LAX I-I	53	30 (57)
End-diastole LAX I-I	53	38 (72)
Systole SAX L-L	42	16 (38)
End-diastole SAX L-L	36	14 (39)
Mid-diastole SAX L-L	46	14 (30)
Systole SAX I-I	42	24 (57)
Mid-diastole SAX I-I	46	27 (59)
CTA three-chamber O-O	52	26 (50)
CTA three-chamber I-I	52	31 (60)
CTA maximum O-O	52	11 (21)
CTA maximum I-I	52	16 (31)
Sinuses dilation ≥ 45 mm
Systole LAX L-L	53	11 (21)
End-diastole LAX L-L	53	8 (15)
Systole LAX I-I	53	8 (15)
End-diastole LAX I-I	53	7 (13)
Systole SAX L-L	42	14 (33)
End-diastole SAX L-L	36	11 (31)
Mid-diastole SAX L-L	46	16 (35)
Systole SAX I-I	42	7 (17)
Mid-diastole SAX I-I	46	7 (15)
CTA three-chamber O-O	52	15 (29)
CTA three-chamber I-I	52	8 (15)
CTA maximum O-O	52	28 (54)
CTA maximum I-I	52	18 (35)
Mid–ascending aorta diameter < 40 mm
Systole LAX L-L	53	19 (36)
End-diastole LAX L-L	53	22 (42)
Systole LAX I-I	53	22 (42)
End-diastole LAX I-I	53	23 (43)
CTA perpendicular O-O	52	15 (29)
CTA perpendicular I-I	52	23 (44)
CTA maximum O-O	52	11 (21)
CTA maximum I-I	52	19 (37)
Mid–ascending aorta dilation ≥ 45 mm
Systole LAX L-L	53	27 (51)
End-diastole LAX L-L	53	26 (49)
Systole LAX I-I	53	24 (45)
End-diastole LAX I-I	53	21 (40)
CTA perpendicular O-O	52	25 (48)
CTA perpendicular I-I	52	23 (44)
CTA maximum O-O	52	28 (54)
CTA maximum I-I	52	26 (50)

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