Image-guided, stereotactic perforator flap surgery: a prospective comparison of current techniques and review of the literature

A review of visualized preoperative imaging with a focus on surgical procedures of the breast

Preoperative imaging has become a valuable tool in the planning of perforator flaps, and to date, computed tomographic angiography (CTA) has been shown to be the gold standard in this role. The evidence for this is a source of constant investigation, with advances in newer modalities coming to the fore. A literature review was undertaken to evaluate the current role of relevant imaging modalities in 'visualized surgery'-the ability to map anatomy prior to surgical incision. A focus is made on their accuracy in perforator mapping and correlation with improved clinical outcomes in the context of deep inferior epigastric artery perforator (DIEP) flap surgery. Other applications for preoperative imaging in breast surgery such as imaging of alternate donor sites or of the recipient site and imaging for volumetric assessment are also discussed. Preoperative imaging is integral to the planning of reconstructive breast surgery. This review has discussed the range of imaging techniques used to map and visualize perforator vasculature, and whilst there are varied clinical applications for the imaging modalities, CTA has been demonstrated to be the most precise and to confer the best clinical outcomes. Applications of the other imaging techniques are varied and these should remain as valid alternatives, particularly for patients where radiation or contrast exposure should be limited. Further studies could focus on the development of a more definitive protocol regarding the approach to preoperative imaging in breast surgery.

In vitro evaluation of a novel fiducial marker for computed tomography and magnetic resonance imaging of soft tissues in small animals

OBJECTIVE

To construct and optimize a fiducial marker suitable for both CT and MRI.

SAMPLE

Fiducial markers containing serial dilutions of iopamidol mixed with water.

PROCEDURES

IV tubing sets were infused with serial dilutions (0% to 100%; increments of 10%) of iopamidol. Tubing ends were sealed; additional seals were added to create an equilateral triangle. A reference point was created by placing a crimp in 1 side. Markers were fixed to a gelatin soft tissue-attenuating phantom and evaluated by use of CT and MRI. For CT, simple linear regression analysis was used to assess the relationship between the percentage of marker contrast medium and quantitative variables, including marker attenuation, attenuation changes in the phantom, and beam-hardening artifact length. A subjective grading scheme for artifact creation on CT images and marker visibility on MRI images was used. Measurements were obtained by investigators who were unaware of the contents of each marker.

RESULTS

Percentage of contrast medium in each marker was strongly correlated with marker attenuation (r(2) = 0.96), artifact length (r(2) = 0.765), and mean attenuation changes within the phantom (r(2) = 0.826) for CT. Subjective CT scores indicated that concentrations of contrast medium > 50% resulted in excessive artifacts. Markers with concentrations of iopamidol > 50% had poor subjective MRI visibility scores. No artifacts were seen on MRI.

CONCLUSIONS AND CLINICAL RELEVANCE

A marker containing a 10% solution of iodinated contrast medium mixed with water provided ideal contrast for both CT and MRI.

Developments in image-guided deep circumflex iliac artery flap harvest: a step-by-step guide and literature review

PURPOSE

The deep circumflex iliac artery (DCIA) flap has evolved significantly over time in the intricacies of flap design and breadth of surgical application. This has been facilitated by advances in preoperative imaging and planning, in particular, computed tomographic angiography. Studies have highlighted that advanced imaging modalities and other technologies such as image-guided stereolithographic biomodeling can substantially improve flap planning, flap harvest, and operative outcomes.

PATIENTS AND METHODS

The present report comprises a combined literature review and clinical cohort study of 20 consecutive patients to assess the modern technologies applied to DCIA flap planning and harvest. We have also described a step-by-step guide for the implementation of these techniques into clinical practice.

RESULTS

The protocol for a single, standardized technique of computed tomographic angiography scanning is presented and was applied to a range of techniques in the preoperative planning of DCIA flaps. These include 1) bony and vascular imaging analysis of both donor and recipient sites, 2) stereolithographic "biomodeling" of both donor and recipient bony and vascular anatomy, and 3) the use of preoperative "virtual surgery" with image-guided stereotactic navigation. The application and role of each technique was explored.

CONCLUSIONS

Modern imaging and stereolithographic techniques are innovations that can substantially improve surgical outcomes in DCIA flap surgery, such as has been highlighted in our clinical experience and in published studies. Notably, few outcome studies have been reported, and the need for larger case series and comparative studies is apparent.

Preoperative imaging for perforator flaps in reconstructive surgery: a systematic review of the evidence for current techniques

BACKGROUND

Although preoperative imaging of perforator vasculature in planning microvascular reconstruction is commonplace, there has not been any clear demonstration of the evidence for this practice, or data comparing the many available modalities in an evidence-based approach. This article aims to provide an objective, evidence-based review of the literature on this subject.

METHODS

The evidence supporting the use of various modalities of imaging was investigated by performing focused searches of the PubMed and Medline databases. The articles were ranked according to the criteria set out in March 2009 Oxford Centre for Evidence-Based Medicine definitions. Endpoints comprised objective outcome data supporting the use of imaging, including flap loss, unplanned returns to theater, operative time reduction, and surgeon-reported stress.

RESULTS

The objective high level of evidence for any form of preoperative perforator imaging is low with only small number of comparative studies or case series investigating computed tomographic angiography (CTA), magnetic resonance angiography, handheld Doppler, color duplex, and classic angiography. Of all modalities, there is a growing body of level 2b evidence supporting the use of CTA.

CONCLUSION

While further multicenter trials testing hard outcomes are needed to conclusively validate preoperative imaging in reconstructive surgery, sufficient evidence exists to demonstrate that preoperative imaging can statistically improve outcomes, and that CTA is the current gold standard for perforator mapping.

A mini pig model for visualization of perforator flap by using angiography and MIMICS

BACKGROUND

Research performed using animal models has assisted in the understanding of flap anatomy and physiology. Pigs' vasculature in the skin is anatomically and physiologically similar to human, making it an ideal model for research. Until now, most vascular imaging studies are of two-dimensions. The aim of this study is to provide a three-dimensional (3D) model that reveals detailed architecture of the vascular network of the porcine, for accurate quantitative assessment.

METHODS

Five Guangxi Bama minipigs were anaesthetized intramuscularly and underwent whole body lead oxide-gelatin injection. Spiral computed tomography scanning was performed on the subjects and three-dimensional reconstructions were made. Another minipig was used, and underwent Cardiografin injection. 3D-reconstruction was executed in vivo. All subjects were then dissected by layers to document the individual perforators.

RESULTS

Angiography using perfusion with lead oxide-gelatine mixture has the advantage of illustrating distinctively the vessels and their perforating branches. However, it is incapable of displaying other tissues structures. Angiography through perfusion with Cardiografin in vivo has the advantage of demonstrating the relationship between arteries and bones. Yet it could only display coarsely the vascular trunk, and is incapable of displaying the vascular network. By combining these two methods, the 3D structure, source, course, and territories of the arteries were presented distinctively.

CONCLUSIONS

3D modeling in combination with traditional sectional imaging of the pig model enables blood vessels to be displayed more dynamically with greater realism. The procedure described could be useful for future flap research, by offering a better visualization of the vascular structure of the skin flap, allowing for better anatomical understanding.