Imaging and printing in plastic and reconstructive surgery part 1: established techniques

Section: Technology and imaging Abstract Background: An increasing number of reconstructive surgeons are using modern imaging technologies for preoperative planning and intraoperative surgical guidance. Conventional imaging modalities such as CT and MRI are relatively affordable and widely accessible and offer powerful functionalities. In the first of a two-part series, we evaluate established three-dimensional (3D) imaging and printing techniques based on CT and MRI used in plastic and reconstructive surgery.

intraoperative guidance and medical education. 2,3 However, there is a lack of comprehensive review of these techniques that provides a global understanding of this novel field in a language suitable for clinicians.
Currently, a plethora of imaging modalities is being used in plastic and reconstructive surgery, mainly computed tomography angiography (CTA) and magnetic resonance angiography (MRA). [4][5][6][7][8][9] First reported for perforator-based flap planning in 2006, 6,7 CTA is widely used in preoperative investigations by institutions around the world and is considered the gold standard due to its high accuracy and reliability. 4 Magnetic resonance angiography bypasses radiation exposure but is limited by only being able to detect vessels greater than 1 mm in diameter. 14 It also has lower spatial resolution 15 and poorer contrast differentiation from the surrounding soft tissue. 16

3D perforator mapping
We identified that CTA and MRA are the most commonly used imaging modalities for 3D perforator mapping. Hence, we evaluated the software suites based on these modalities.

3D volumetric analysis
We focused our analysis of 3D volumetric analysis based on conventional 3D imaging techniques, CT and MRI. We systematically identified a list of software suites used to analyse 3D volumetric data from CT or MRI and examined their application in plastic and reconstructive surgery.

3D printing
Studies using 3D printing for preoperative planning in plastic and reconstructive surgery were assessed

3D perforator mapping
In perforator based, free flap reconstruction, plastic surgeons commonly rely on CTA-or MRA-based 3D reconstructed images of the relevant perforators for preoperative planning (see Figure 1).

CTA
Computed tomography angiography is the most commonly used imaging modality for 3D perforator mapping, using maximum intensity projection

Results and discussion
Numerous studies have explored the application of conventional imaging modalities for 3D perforator mapping, 3D volumetric analysis and 3D printing.

3D volumetric analysis
Accurate assessment of tissue volume is an important aspect of preoperative planning in plastic surgery. [34][35][36][37][38] Particularly in breast reconstructive surgery, volumetric analysis is paramount for achieving symmetrisation and a satisfactory outcome. [39][40][41][42][43][44] However, an accurate, reliable and convenient method of objective breast volumetric analysis has remained elusive (see Figure 2 and However, ImageJ has yet to be investigated in clinical application.

3D printing
In contrast to medical imaging modalities that are limited by being displayed on a 2D surface, such as a computer screen, a 3D-printed biomodel  39 Rha et al, 41 Rosson et al, 43 Herold et al, 44 Lee et al, 46 Chae et al, 51 Rha et al, 52 Blackshear et al, 131 and Corey et al 135 can additionally provide haptic feedback. 2,[53][54][55][56] Three-dimensional printing, also known as rapid prototyping or additive manufacturing, describes a process by which a product derived from computer-aided design (CAD) is built in a layerby-layer manner. [57][58][59] The main advantages of 3D printing are the ability to customise, cost-efficiency and convenience. 60,61 Since its introduction, the use of 3D printing in surgery has been extensively investigated.
In clinical application, two types of software

Preoperative planning
Three-dimensional printing has been most commonly used in plastic and reconstructive surgery for preoperative planning (see Table 3).

Autologous breast reconstruction
In

Intraoperative guidance
Use of 3D-printed fibular osteotomy guides for mandibular reconstruction has been studied extensively (see Table 4). 66

Disclosure
The authors have no financial or commercial conflicts of interest to disclose.