A few considerations on "sonoelastography of the plantar fascia".

Radiology: Volume 261: Number 3—December 2011 n radiology.rsna.org 995 Deep fascia is a dense connective tissue that is commonly arranged in sheets that form a stocking around the muscles and tendons beneath the superfi cial fascia ( 1 ). In the limbs, the deep fascia is formed by an aponeurotic layer (investing layer) continuous with the epimysium, perimysium, and endomysium with the intermuscular septa ( 2 ). In contrast to deep fascia, there has been considerable controversy with respect to the organization of superfi cial fascia ( 3 ). According to standard textbooks of anatomy, the superfi cial fascia or “subcutaneous tissue” is described as a layer of loose areolar connective or adipose tissue that connects the skin to the underlying bones or deep fascia ( 3 ). The superfi cial fascia has two layers: the external fatty layer and the deep membranous layer ( 2 , 3 ). Traditionally, the membranous layer of superfi cial fascia is known to be present in restricted areas of the body, such as the lower anterior abdominal wall (Scarpa fascia) and the perineum (Colles fascia) ( 3 ). However, recent studies prove that the membranous layer is consistently found in the superfi cial fascia in many regions of the body, including extremities ( 3 ). In our opinion, it is diffi cult to distinguish the investing layer of the deep fascia from the deep membranous layer of the superfi cial fascia on MR images because they fuse on each side ( 3 ). The second comment addresses the optimal technique for showing the abnormal signal intensity of the deep fascia. In our opinion, the fat-suppressed T2-weighted image is the most useful for detecting abnormalities in deep fascia because a high-signal-intensity fl uid collection along deep fascia is easily detected with this sequence. Although the low signal intensity (representing gas) in deep fascia on the fat-suppressed T2weighted image is a specifi c fi nding for necrotizing infectious fasciitis, it is not sensitive. It is not diffi cult to detect low signal intensity on a fat-suppressed T2weighted image when it is combined with a T1-weighted image.