Novel imaging techniques for intraoperative margin assessment in surgical oncology: A systematic review

Abstract

Inadequate margins continue to occur frequently in patients who undergo surgical resection of a tumor, suggesting that current intraoperative methods are not sufficiently reliable in determining the margin status. This clinical demand has inspired the development of many novel imaging techniques that could help surgeons with intraoperative margin assessment. This systematic review provides an overview of novel imaging techniques for intraoperative margin assessment in surgical oncology, and reports on their technical properties, feasibility in clinical practice and diagnostic accuracy. PubMed, Embase, Web of Science and the Cochrane library were systematically searched (2013-2018) for studies reporting on imaging techniques for intraoperative margin assessment. Patient and study characteristics, technical properties, feasibility characteristics and diagnostic accuracy were extracted. This systematic review identified 134 studies that investigated and developed 16 groups of techniques for intraoperative margin assessment: fluorescence, advanced microscopy, ultrasound, specimen radiography, optical coherence tomography, magnetic resonance imaging, elastic scattering spectroscopy, bio-impedance, X-ray computed tomography, mass spectrometry, Raman spectroscopy, nuclear medicine imaging, terahertz imaging, photoacoustic imaging, hyperspectral imaging and pH measurement. Most studies were in early developmental stages (IDEAL 1 or 2a, n = 98); high-quality stage 2b and 3 studies were rare. None of the techniques was found to be clearly superior in demonstrating high feasibility as well as high diagnostic accuracy. In conclusion, the field of imaging techniques for intraoperative margin assessment is highly evolving. This review provides a unique overview of the opportunities and limitations of the currently available imaging techniques.

Keywords: cancer; medical imaging; surgical margin; surgical oncology; systematic review.

FIGURE 1

The three areas of interest at which imaging techniques could assist surgeons with intraoperative margin assessment: the surgical field, the cavity and the specimen [Color figure can be viewed at wileyonlinelibrary.com]

FIGURE 2

PRISMA flowchart [Color figure can be viewed at wileyonlinelibrary.com]

FIGURE 3

Number of publications per year (displayed above each column) stratified per IDEAL‐stage (percentages within the columns). The number of publications increased each year, which was mainly driven by the increasing portion of studies in the IDEAL 1 and 2a stage. The portions of stage 2b and 3 remain relatively small over the years

FIGURE 4

The number of studies (displayed above each column) per group of imaging technique stratified per area of interest. Studies investigating two techniques were included in the figure twice

FIGURE 5

The relation between resolution and acquisition time. Four groups were distinguished with (A), studies that scanned part(s) of the surface, (B) part(s) of the subsurface, (C) the complete surface and (D) the complete subsurface. The numbers provided with each symbol refer to the original studies as displayed in Supplementary Table 2

FIGURE 6

Overview of feasibility in clinical practice summarized per imaging category and sorted from highest to lowest feasibility. The number of studies per imaging category scoring a “yes” was obtained from Supplementary Table 3 and expressed as a percentage for each individual feasibility criterion. The total number of studies per imaging category is displayed between parentheses [Color figure can be viewed at wileyonlinelibrary.com]