Water Can Make the Clearest Ultrasonographic Image During Reduction of Nasal Fracture

1 Yuka Shigemura, MD Jun Akamatsu, MD, PhD Naoya Sugita, MD Takashi Nuri, MD, PhD Koichi Ueda, MD, PhD Department of Plastic and Reconstructive Surgery Chikamori Hospital Kōchi, Kochi Prefecture Japan Department of Plastic and Reconstructive Surgery Osaka Medical College Takatsuki, Osaka Japan Sir: U is now a very popular noninvasive imaging technique. It has been reported to be useful in the diagnosis and assessment of reduction in nasal bone fracture.1–3 Ultrasonography can detect local and superficial fractures. However, it is difficult to see the whole nasal bone and the neighboring facial bones because the probe cannot be applied to such a complicated 3D structure.4 Various media are used to solve the problem.4 Ultrasound signals are attenuated by passing through the medium. The attenuation rate can be calculated by the following relationship: Attenuation volume (dB) = Attenuation index (dB/cm/MHz) × Depth (cm) × Frequency (MHz). The lager the attenuation index of the medium, the more signals are absorbed as they pass through the medium. The greater the depth of the medium, the more ultrasound is absorbed. The higher the frequency of the ultrasound, the greater is the absorption as it passes through the medium. The attenuation index of water is the lowest in the various media (Table 1). Therefore, a clear ultrasonographic image can be obtained if water can be utilized as the medium. We used saline as the coupling medium for ultrasonography in nasal bone fracture. To keep saline on the face, the outer frame of a snorkeling mask made of thermoplastic elastomer was used (Fig. 1). To prevent saline from entering the nasal cavity, we sealed the nostrils with medical tape. The ultrasound probe could be applied through the pool of saline without adding pressure to the nasal bone fracture site. The ethical committees of Chikamori Hospital and Osaka Medical College approved this method before it was performed. The ultrasonographic images in the 4 different directions (axis, sagittal, inclining views from the right and left side) were scanned routinely before and after reduction. The probe (Venue 40, GE healthcare; 12-MHz linear array) was used under general anesthesia.