| Popis: |
The ability of volume-rendered three-dimensional echocardiography (3DE) in displaying atrial septal defects (ASD) in a dynamic mode has been demonstrated; however the quantitative accuracy of 3DE in sizing the defect is not known. In this study, we examined the reliability of measuring the ASD size directly on 3-D image reconstructions. In 10 explanted pig hearts, we created a total of 10 ASDs of various types and shapes (2 primum, 5 secundum and 3 sinus venosus). Suspending the hearts in a water bath, 2DE images were collected. An ultrasound transducer was mounted on a motorized parallel scanning device and we attained 21 6 slices over a distance of 60 mm. Digital reformation, interpolation and segmentation (threshold and opacity) were subsequently performed, and 3DE reconstructions accomplished; Appropriate cut planes were used to display the ASDs en face . Using a new processing algorithm, measurements of maximum diameter (Max D) and minimum diameter (Min D) were done directly on the 3DE image. These were compared with independently measured anatomic data. In addition, interobsever variability was also assessed. Results All 3D reconstructions successfully displayed the ASDs of all types. The site, shape and size were well appraised in it's true form and corresponded well with the anatomic specimens. The Maximum D was (Mean ± SD in mms): 16.9 ± 5.6 (range 8.5–27.5) by anatomy and 17.5 ± 4.8, (range 9–4) by 3DE; Minimum D was: 12.3 ± 4 (range 6–18) by anatomy, and 12.6 ± 4 (range 7–19) by 3DE. The correlations between 3DE (y) and anatomy (x) were: Maximum D: y = 0.83x + 3.4; r = 0.97, p l 0.001. Min D: y = 0.92x + 1.3, r = 0.92, p l 0.001. Interobserver concordance was also excellent for both Max and Min diameters (r = 0.93 and r = 0.98). Conclusion 3DE provides excellent visualization of ASDs in unique en face projections not available in conventional imaging techniques. 3DE makes it possible to derive multiple diameter measurements of ASDs not attainable from 2DE. Measurements of ASD, now readily performed directly on 3DE images, accurately define the size of ASDs. These qualitative and quantitative capabilities of 3DE enhance the clinical potential of this technique in sizing the ASDs required for catheter or surgical interventions. |
