Three-dimensional posterior segment ultrasonography: clinical experience

To introduce a commercially available three-dimensional ultrasonography unit into everyday clinical practice and to evaluate the qualitative and quantitative information of the acquired images and to clarify the indications for 3-D echography.

3-D scanning was performed on 59 referred patients with indications for conventional B/A-scan. On 7 patients with an intraocular mass with well-delineated borders 10 repeated volume measurements were carried out.

The duration of the ultrasound examination was extended with 8-10 min. 3-D echography offered images of unique perspectives, not previously available with conventional B-scan. The digital technology allowed easy (re)evaluation and follow-up. The coefficient of variation of the repeated volume measurements was less than 5% for all the patients. The standard deviations ranged from 2.22 to 4.75 mm3.

At its current level of technological development 3-D posterior segment ultrasonogaphy left the status of an entirely research laboratory tool and entered the clinical practice. Nevertheless 3-D imaging is neither a rival nor a substitute of conventional B-scan since it is static and needs time intervals for reconstruction. However 3-D ultrasonography is a useful clinical supplement to conventional B/A echography in departments to which a substantial number of complicated cases (esp. intraocular tumours) is referred. It enables volume measurements with good intraobserver reproducibility and is excellent for teaching and training purposes of ophthalmology residents.