Ultrasound Needle Visibility in Contrast Mode Imaging: An In Vitro and Ex Vivo Study.

PURPOSE

To evaluate needle visibility in ultrasound under contrast mode conditions.

MATERIALS AND METHODS

Needle visibility was evaluated for bevel, EchoTip and shaft of 18G Chiba biopsy needle with a 9 MHz linear probe (GE Logiq E9). Insertion angles varied between 30°(steep) and 90°(parallel to the probe surface). The acoustic output varied from 5-28%. 2 different contrast mode presets with either 'Amplitude Modulation' (Penetration) or 'Phase Inversion Harmonics' (High Resolution) were assessed. All other imaging parameters were kept constant. The visibility of bevel, EchoTip and shaft was assessed for grayscale and color-coded images with a 3-point Likert-like scale (not, poorly, well visible) by 2 independent readers. The echogenicity of the needle bevel, EchoTip and shaft was assessed in deciBel (dB) on the color-coded images.

RESULTS

With the parallel insertion angle, all needle areas were well visible. With steep insertion the EchoTip was the only visible area. High Resolution was superior to Penetration (p<0.001). The visibility and echogenicity of the needle bevel ( =0.109, p =0.178; =0.236, p =0.266; =0.956, p =0.001), EchoTip ( += 0.477, p += 0.018; =0.540, p += 0.006; =0.911, p =0.001) and shaft ( =0.124, p =0.563; =0.061, p += 0.775; += 0.926, p =0.001) increased with increasing acoustic output. Grayscale images were superior to color-coded images for needle visibility (p=0.004).

CONCLUSION

Parallel needle insertion, use of an echogenic tip, adequate choice of presets, increased acoustic output, and dual view of grayscale and color-coded images improve needle visibility in ultrasound under contrast mode conditions.