An ultrasonic imaging system is described which visually assists biopsy needle insertion. The system produces pixel values of pixels along one or more paths of needle insertion. A tissue density analyzer is responsive to the pixel values to estimate tissue density along a path of needle insertion. A needle path calculator is responsive to the tissue density analyzer and proposes one or more favorable paths through imaged tissue for insertion of the biopsy needle. The system may be used in conjunction with a three dimensional navigation system which spatially locates the needle and ultrasound image plane in 3D space.
