AJR: 3D ultrasound with matrix array transducer reliably measures renal volume

Three-dimensional sonography with a matrix array transducer is a reliable means of measuring renal volume during evaluations of patients with reduced renal function, according to a study in the February issue of the American Journal of Roentgenology.

According to Hyun Cheol Kim, MD, from the department of radiology at East-West Neo Medical Center, Kyung Hee University in Seoul, South Korea, and colleagues, the measurement of bipolar renal length is traditionally regarded as an initial requirement during sonographic exams of patients with suspected renal impairment because reduced renal length is considered an indicator of irreversible chronic renal disease.

There have been some claims, the authors wrote, that 3D sonography with freehand and mechanical acquisition techniques can be used to measure renal volume with high accuracy, but they add that these methods are slow and can be complicated in terms of volumetric data acquisition.

In this study, Kim and colleagues wanted to evaluate the reproducibility of 3D sonography with a matrix array transducer as a means of measuring renal volume and to investigate correlations between renal volume and renal function. They enrolled 120 patients with one of the five stages of chronic renal disease and 20 healthy volunteers.

Routine 2D sonography was initially performed by a radiologist (10 years of experience in sonographic examinations) using an ultrasound system equipped with a 2- to 5-MHz convex transducer (iU22, Philips Healthcare). The same radiologist immediately performed 3D ultrasound with a matrix array transducer (X3-1, Philips Healthcare) after 2D sonography.

The authors found that the reproducibility of 3D sonography measurements obtained with the matrix array transducer was greater than that of 2D sonographic measurements. The correlation between normalized total renal volume obtained with matrix array transducer 3D sonography and estimated GFR for two observers was better than that between normalized total renal volume obtained with 2D sonography and estimated glomular filtration rate.

Kim and colleagues also found that the mean normalized total renal volumes obtained with matrix array transducer 3D sonography in stages 0 and 1 were significantly larger than those in other stages. The mean normalized total renal volume in stage 5 disease was significantly smaller than the volumes in the other stages.

The authors concluded that matrix array transducer 3D sonography provides a more reliable means of determining renal volume in patients with reduced renal function.