J Korean Soc Med Ultrasound.  2001 Mar;20(1):81-86.

The Lunula: An Ultrasound Imaging Approach

• Choi SJ
• Shin MJ
• Ahn JM
• Kim SM

Abstract

PURPOSE
The lunula is the white, half-moon-shaped area seen on some, but not all nails. Usually the lunula is the topographic marker of the distal part of the nail matrix, and known to have the ability of nail production. Ultrasonographic imaging of the lunula has not been reported before. This study was undertaken to demonstrate normal ultrasonographic features of the lunula.
MATERIALS and METHODS
Ultrasonographic examination of the lunula was performed in the right thumb of 20 healthy volunteers (10 M, 10 F, mean age 30, range 26-36 years) with a real-time, high-resolution ultrasound unit (Sequoia 512, Acuson, Mountain view, CA, USA) with 8-15 MHz linear transducers. Gray scale, color, and spectral Doppler imagings were performed with longitudinal scanning.
RESULTS
: The lunula was not seen inspection in three of the 20 volunteers. The mean size of the lunula in the other 17 volumteen was 3.31 +/- 1.24 mm (range 2 -6.2 mm). Gray scale ultrasound imaging showed the lunula; ovoid shaped hypoechoic zone in proximal fingernail in 18 of 20 volunteers (mean size, 6.74 +/- 0.98 mm, range, 5 -8.8 mm). In two of 20 volunteers, the lunula was indistinct on gray scale ultrasound examination. However, all lunulas were identifiable on color Doppler imaging by detecting vascularity within the lunula. Spectral wave pattern of the lunula was a bi-dierectional pulsatile wave. Peak velocity was within 5 -15 m/sec (mean, 8 m/sec).
CONCLUSION
The lunula is identifiable on ultrasound examination as a hypervascular, ovoid shaped, hypoechoic zone in proximal fingernail. This normal structure should not be misinterpreted as an abnormal subungual lesion.

MeSH Terms

Healthy Volunteers
Nails
Thumb
Transducers
Ultrasonography*
Volunteers