We read with great interest the recent article entitled “Use of Doppler Ultrasound to Avoid Injection Complications” by Dr. Lambros.1 We agree with the author that Doppler ultrasound is a useful tool to avoid injection complications. In addition, B-mode ultrasound with color Doppler was reported to assist echo-guided hyaluronidase injection in treating filler-induced vascular complications.2 However, we have to mention that limitation exists for this modality to detect some vascular lumens. Many factors will influence the sensitivity of color Doppler. The vascular diameter is the most important factor, and flow velocity is the second major parameter.3 The Doppler frequency is also an essential factor. The signal intensity will increase 16-fold if the frequency doubles, such as from 2 MHz to 4 MHz.4 Different machines, Doppler modalities, and factory settings will influence the sensitivity.5
For example, we herein report a case with filler-induced vascular complication in which signals of color Doppler could only be detected after vascular occlusion. This 35-year-old woman was referred to our clinic with skin necrosis on the right lateral chin after receiving hyaluronic acid (Restylane Vital; Q-Med, Uppsala, Sweden) for atrophic acne scar 5 days previously (Fig. 1). We performed soft-tissue echography to evaluate the lesion with a 10-MHz linear transducer. The color Doppler imaging revealed a hypoechoic pseudocystic vascular lumen close to a strong pulsating signal (Fig. 2). In the normal counterpart of the left lateral chin, we could find neither skin necrosis nor pulsating color Doppler signal. (See Figure, Supplemental Digital Content 1, which shows the normal counterpart of the left lateral chin. Neither skin necrosis nor pulsating color Doppler signals could be found in the normal counterpart of the left lateral chin, https://links.lww.com/PRS/E66.) The region of tissue necrosis was consistent with the tributary of the cutaneous branch of the inferior labial artery. However, in the normal condition, the lumen and the flow velocity of the vessel were too small and low, and the Doppler signal was undetectable. After occlusion of the artery, the flow velocity of the proximal end increased, and the transducer could detect the color Doppler signal.
In conclusion, Doppler ultrasound is valuable to avoid vascular complications in most clinical scenarios. However, the clinicians should be alerted that many factors will affect the sensitivity of this examination, and the possibility of false-negativity should always be kept in mind to avoid vascular complications.
The authors have no financial interest to declare in relation to the content of this communication.
1. Lambros V. Use of Doppler ultrasound to avoid injection complications. Plast Reconstr Surg. 2019;144:724e.
2. Kwon HJ, Kim BJ, Ko EJ, Choi SY. The utility of color Doppler ultrasound to explore vascular complications after filler injection. Dermatol Surg. 2017;43:1508–1510.
3. Delorme S, Peschke P, Zuna I, Van Kaick G. Sensitivity of color Doppler sonography: An experimental approach. Ultrasound Med Biol. 1999;25:541–547.
4. Zhu J. Effect of the probe frequency on sensitivity of color Doppler ultrasound to color blood flow: Comment on the Article by Torp-Pedersen et al. Arthritis Rheumatol. 2015;67:1681.
5. Torp-Pedersen S, Christensen R, Szkudlarek M, et al. Power and color Doppler ultrasound settings for inflammatory flow: Impact on scoring of disease activity in patients with rheumatoid arthritis. Arthritis Rheumatol. 2015;67:386–395.