Photoacoustic microscopy: a novel approach for studying perforator skin flap in a mouse model

Abstract

Background: A comprehensive understanding of cutaneous microvessels is key to the design and use of the perforator skin flap. Compared with the various imaging technologies that have been applied in the clinical practice of the perforator skin flap, photoacoustic microscopy (PAM) is a very promising noninvasive imaging modality with high resolution and deep penetration in biological tissues.Methods: PAM was employed to explore its multiple applications in a perforator skin flap. The following experiments were then conducted in 3 parts. In part 1, 7 mice were used to obtain the preoperative perforator mapping on the mouse back. In parts 2 and 3, 7 mice were used to design and harvest the multiterritory perforator flap. The status of the flap and the morphological changes of choke vessels were subsequently observed by PAM at several time points. Results:The results showed that PAM could visualize and assess the vascular physiological and pathological conditions of the skin tissue in real time in vivo with high spatial and temporal resolution. It could also provide preoperative perforator mapping, including the total number of perforators, localization, vascular territories, and diameter. Furthermore, it could offer a quantitative, objective method to monitor the status of the perforator skin flap, and was capable of noninvasive characterization of the changes of choke vessels that play an important role in multiterritory perforator skin flap expansion and survival.Conclusions: PAM has great potential to be an effective and precise quantitative imaging tool for perforator skin flap research, such in as flap design, monitoring, and choke vessel observation.

Monitoring angiogenesis in skin autografts using photoacoustic microscopy

“…Over the last decade, ultrasound, x‐ray angiography, magnetic resonance angiography, and computed tomographic angiography are the most often used imaging modalities for observing vessels [26]. However, there are some limitations in these imaging tools; for example, disappointing resolution makes it tough to offer detailed visualization of the angiogenesis of the skin autograft on early time points; and these approaches could not get images in a noninvasive and portable way; more importantly, x‐ray, MRA, and CTA demand to inject angiographic agents which actually interrupt the intrinsic physiology of vessel and impede the process of observation [27]. All of these show various intrinsic limitations; therefore, they are not able to obtain images in a noninvasive, dynamic, in vivo and real‐time way.…”

NIR‐II imaging with ICG for identifying perforators, assessing flap status and predicting division timing of pedicled flaps in a porcine model

“…Currently, various approaches used for flap design and use seem ineffective [19]. For example, few methods is satisfactory to easily, quickly and comfortably locate the perforators at both high resolution and depths; the evaluation of flap status and the time of flap division are often evaluated via convention and personal experience based on skin warmth, color, capillary refill and dermal bleeding, but these signs are subjective and have limited sensitivity and/or specificity [18, 20]. In addition, ultrasound, X‐ray, CTA, MRA, laser Doppler flow measurement and thermography also have many problems [21].…”

“…Despite flaps have broadly been used in the field of plastic and reconstructive surgery, there still remains challenging for us to have a comprehensive understanding of vascular supply which limits to locate the perforators, assess flap status and predict optimal division timing of pedicled flaps [15,18]. Currently, various approaches used for flap design and use seem ineffective [19].For example, few methods is satisfactory to easily, quickly and comfortably locate the perforators at both high resolution and depths; the evaluation of flap status and the time of flap division are often evaluated via convention and personal experience based on skin warmth, color, capillary refill and dermal bleeding, but these signs are subjective and have limited sensitivity and/or specificity [18,20]. In addition, ultrasound, X-ray, CTA, MRA, laser Doppler flow measurement and thermography also have many problems [21].…”

“…Despite flaps have broadly been used in the field of plastic and reconstructive surgery, there still remains challenging for us to have a comprehensive understanding of vascular supply which limits to locate the perforators, assess flap status and predict optimal division timing of pedicled flaps [15, 18]. Currently, various approaches used for flap design and use seem ineffective [19].…”

Real‐time visualization of skeletal muscle necrosis in mice and swine through NIR‐II/I fluorescence imaging

“…However, NIR‐II imaging has not been used in a clinical environment, mainly because of a lack of suitable imaging instruments and optical probes. Most NIR imaging instruments are built for the laboratory, such as Bruker Xtreme, which is only suitable for small animals like mice [5]. The particular imaging platform and lack of portable CCD components restrict the application of NIR‐II/I imaging in the clinic.…”