An imaging plane, parallel to the ground, perpendicular (rotated 90°) to the long axis of the human body; the axial plane separates the superior from the inferior part (the head from the feet). Also called axial, transaxial or transversal plane.

Biplane endorectal and endovaginal probes are commonly used in obstetrics, gynecology and urology. They are generally composed of 2 arrays one linear for imaging of the longitudinal plane and a highly curved one to image the transverse plane. These two planes allow a perpendicular visualization of the region of interest.
Ultrasound imaging in both transverse and longitudinal planes enables e.g., precise multiple biopsies by simultaneous visualization of both planes in real-time.

(TIB) The bone thermal index is an exposure model for the case that the ultrasound beam passes through soft tissue and a focal region is in the immediate vicinity of bone.
The longitudinal waves of ultrasound are reflected and transformed into transverse waves, creating a heating effect. Muscle and bone absorb more energy at interfaces with other heterogeneous tissues.

See also Sheer Wave.

Ultrasonography of the kidneys (renal ultrasound) is part of a complete examination of the abdomen. Ultrasound is used to determine the size, shape, and exact position of the kidneys. Renal ultrasound provides important information regarding kidney function, related blood vessels, kidney stones, renal cysts, tumors, or hydronephrosis (suggestive of obstruction or blockage of the kidney).
The kidneys are scanned on longitudinal and transverse planes. Patients should avoid carbonated drinks such as soda or seltzer the day before, and have a full bladder for the test.
Lithotripsy is a therapeutic ultrasound procedure used to shatter simple stones in the kidney or upper urinary tract.

See also Urologic Ultrasound, Reflux Sonography.

If available, some graphic aids can be helpful to show image orientations.
1) A graphic icon of the labeled primary axes (A, L, H) with relative lengths given by direction sines and orientation as if viewed from the normal to the image plane can help orient the viewer, both to identify image plane orientation and to indicate possible in plane rotation.
2) Ingraphic prescription of obliques from other images, a sample original image with an overlaid line or set of lines indicating the intersection of the original and oblique image planes can help orient the viewer.


In all cases the scanning surface is assigned to the top of the image. The orientation of single oblique slices can be specified by rotating a slice in one of the basic orientations toward one of the other two basic orthogonal planes about an axis defined by the intersection of the 2 planes.

See also Histogram.