The image acquisition is based on the external detection in coincidence of the emitted rays, and a valid annihilation event requires a coincidence within 12 nanoseconds between two detectors on opposite sides of the scanner. For accepted coincidences, lines of response connecting the coincidence detectors are drawn through the object and used in the image reconstruction.
For more information, see http://www.imaginis.com/nuclear-medicine/nuc_pet.asp
Plantar fibromatosis is a benign nodular disorder of the plantar fascia (which is also known as the plantar aponeurosis). The plantar fascia is a thin, wide, long tissue that begins on the bottom (plantar) aspect of the heel and will continue forward through the arch to the ball of the foot. This tissue is a type of ligament that is made of bands of fibers that act as a shock absorber during weight bearing.
Plantar fibromatosis is most commonly found in the region of the arch but may occur at any point on the plantar fascia. These nodules often begin as pain free bumps under the skin but may become very painful during periods of high activity such as running, tennis, aerobics, and other similar activities. There may be redness and swelling in those regions but often will not show signs of irritation. It should be noted that this condition may occur in other parts of the body with subsequent renaming of the condition specific to that part.
This was plagiarised from http://www.valleyfoot.com/, which seems now to be broken. However, a Google search for “Plantar fibromatosis” yields lots of hits.