Safety and reproducibility of virtual-assisted lung mapping: a multicentre study in Japan

Abstract

Objectives: Virtual-assisted lung mapping (VAL-MAP) is a preoperative bronchoscopic multispot dye-marking technique using virtual images. The purpose of this study was to evaluate the safety, efficacy and reproducibility of VAL-MAP among multiple centres.

Methods: Selection criteria included patients with pulmonary lesions anticipated to be difficult to identify at thoracoscopy and/or those undergoing sub-lobar lung resections requiring careful determination of resection margins. Data were collected prospectively and, if needed, compared between the centre that originally developed VAL-MAP and 16 other centres.

Results: Five hundred patients underwent VAL-MAP with 1781 markings (3.6 ± 1.2 marks/patient). Complications associated with VAL-MAP necessitating additional management occurred in four patients (0.8%) including pneumonia, fever and temporary exacerbation of pre-existing cerebral ischaemia. Minor complications included pneumothorax (3.6%), pneumomediastinum (1.2%) and alveolar haemorrhage (1.2%), with similar incidences between the original centre and other centres. Marks were identifiable during operation in approximately 90%, whereas the successful resection rate was approximately 99% in both groups, partly due to the mutually complementary marks. The contribution of VAL-MAP to surgical success was highly rated by surgeons resecting pure ground glass nodules ( P < 0.0001), tumours ≤ 5 mm ( P = 0.0016), and performing complex segmentectomy and wedge resection ( P = 0.0072).

Conclusions: VAL-MAP was found to be safe and reproducible among multiple centres with variable settings. Patients with pure ground glass nodules, small tumours and resections beyond conventional anatomical boundaries are considered the best candidates for VAL-MAP.

Clinical trial registration number: UMIN 000008031. University Hospital Medical Information Network Clinical Trial Registry ( http://www.umin.ac.jp/ctr/ ).

Keywords: Ground glass opacity; Lung cancer; Marking; Metastatic pulmonary tumour; Segmentectomy.

Figure 1:

Steps of VAL-MAP. The lung ‘map’ was designed using radiology workstations and virtual bronchoscopy. Bronchoscopic dye injection was conducted within 3 days before surgery under fluoroscopic guidance to confirm the location of the metal-tip injection catheter (black arrow). After mapping, CT scan was taken within a few hours–days after VAL-MAP to visualize actual locations of markings (arrowhead). Using a radiology workstation, 3D images were further reconstructed, reflecting actual locations of markings. The operation was conducted using the 3D image for guidance. The white arrows indicate dye marks. VAL-MAP: virtual-assisted lung mapping.

Figure 2:

Visibility of VAL-MAP marks during surgery. (A) Visibility of marks was graded similarly between the leading institution (KU) and other multiple centres (MC). (B) Among the MC group, visibility of marks was graded similarly. (C) Visibility of marks according to the centre’s case number, showing almost no change throughout the experience. (D) Visibility of marks according to the time from VAL-MAP to surgery, demonstrating a decrease in visibility. VAL-MAP: virtual-assisted lung mapping.

Figure 3:

Contribution of VAL-MAP to surgery. (A) VAL-MAP’s contribution to surgery in the leading institution (KU) and other multiple centres (MC). There was no statistical difference between the groups. As described previously [12], the contribution was evaluated for each case by surgeons as Grade A, the same level of operative precision was judged to be impossible without VAL-MAP; Grade B, a similar level of precision was judged to be possible, but VAL-MAP enabled confident performance of the operation; and Grade C, the same operation was judged to be possible without VAL-MAP. (B) VAL-MAP’s contribution to surgery among the MC group. The centres that enrolled more than 10 patients are shown. VAL-MAP’s contribution was analysed by (C) radiological characteristics of the targeted lesion on CT scan (P < 0.0001), (D) the largest diameter of the targeted lesion measured on CT scan (P = 0.0016) and (E) selected operation types (P = 0.0072). VAL-MAP: virtual-assisted lung mapping.