Display of 3-dimensional ultrasonographic images for interventional procedures: volume-rendered versus multiplanar...

The goal of this project was to assess the display of 3-dimensional ultrasonographic images as used for interventional procedures, particularly the conspicuity of various targets and interventional devices, comparing volume-rendered (VR) versus multiplanar reformatted (MPR) display approaches.

A series of ultrasonographic phantoms were made from a petroleum gel with cornstarch used to vary the echo texture. Three-dimensional ultrasonographic target and device conspicuity were judged with a 5-point visual rating scale. The MPR image was considered the reference standard. Volume-rendered image conspicuity was judged for combinations of 7 different postprocessing display parameters and compared with MPR images.

Definite visualization of the embedded objects occurred in 92% of MPR and 13% of VR test situations (P < .0001). Volume-rendered display was associated with a mean conspicuity degradation of 2.6 on a scale of 0 through 4 (P < .0001) compared with MPR methods. The proportion of satisfactory VR images was greatest in test situations with a large degree of difference of echogenicity between the background medium and the embedded object. The transparent-type postprocessing rendering modes were superior to the surface-type rendering modes (P < .0001).

Current 3-dimensional ultrasonographic MPR imaging display in a solid organ environment provides better visualization performance of target and needle conspicuity than VR image display when there are not large differences in the signal levels of targeted structures and devices compared with surrounding tissues. The difficulty in viewing both target and device with VR imaging may restrict its ability to guide interventional procedures in some clinical situations.