Characterization and evaluation of the artemis camera for fluorescence-guided cancer surgery

Abstract

Purpose: Near-infrared (NIR) fluorescence imaging can provide the surgeon with real-time visualization of, e.g., tumor margins and lymph nodes. We describe and evaluate the Artemis, a novel, handheld NIR fluorescence camera.

Procedures: We evaluated minimal detectable cell numbers (FaDu-luc2, 7D12-IRDye 800CW), preclinical intraoperative detection of sentinel lymph nodes (SLN) using indocyanine green (ICG), and of orthotopic tongue tumors using 7D12-800CW. Results were compared with the Pearl imager. Clinically, three patients with liver metastases were imaged using ICG.

Results: Minimum detectable cell counts for Artemis and Pearl were 2 × 10(5) and 4 × 10(4) cells, respectively. In vivo, seven SLNs were detected in four mice with both cameras. Orthotopic OSC-19-luc2-cGFP tongue tumors were clearly identifiable, and a minimum FaDu-luc2 tumor size of 1 mm(3) could be identified. Six human malignant lesions were identified during three liver surgery procedures.

Conclusions: Based on this study, the Artemis system has demonstrated its utility in fluorescence-guided cancer surgery.

Fig. 1

Artemis NIR imaging system. a The NIR fluorescence imaging Artemis handheld system is positioned on a movable trolley. Ring light (1) and lens (2) have to be attached to the handheld camera (3) to obtain NIR fluorescence images. Instead of lens and ring light, a scope (4) can be attached to the handheld camera when minimal invasive surgery is applied. b Schematic representation of the Artemis camera with light path and filters. The sample is illuminated by a ring light around the camera lens.

Fig. 2

Calibration of the Artemis system and minimal detection limit of hypopharyngeal tumor cells. a, c Signal-to-noise (SNR) and b, d signal-to-background (SBR) ratios of concentration ranges of a, b ICG and c, d CW800 imaged in 96-well plates. Measurements from control wells with 0 μM ICG and CW800 are shown as red horizontal lines. e Bioluminescence was correlated to the number of FaDu-luc2 cells. f FaDu-luc2 cells were incubated with the EGFR-specific nanobody 7D12-800CW and g non-specific nanobody R2-800CW for 2 hours. After incubation, cells were washed twice and cell pellets containing different amount of cells were imaged using the Artemis and Pearl imaging system.

Fig. 3

Sentinel lymph node detection using indocyanine green. Cervical sentinel lymph nodes could clearly be identified after injection of 100 μM ICG (10 μl) in the tongue (T) using both the Artemis and Pearl imaging system within 10 min after injection. Contrast-to-noise ratios (CNR) of the Artemis and Pearl are shown. LNL = lymph node left; LNR = lymph node right.

Fig. 4

Near-infrared fluorescence delineation of orthotopic tongue tumors. OSC-19-luc2-cGFP tongue tumors could clearly be identified after injection of the epidermal growth factor receptor-specific nanobody 7D12-800CW (50 μg) using both the Artemis and Pearl. No fluorescence could be observed after injection of 50 μg of control nanobody R2-800CW. Contrast-to-noise ratios (CNR) calculated by using the Artemis and Pearl are shown. A = Artemis; P = Pearl.

Fig. 5

Tumor detection limit. Hypopharyngeal FaDu-luc2 tumors of different sizes visualized using bioluminescence imaged by a the IVIS Spectrum system could clearly be delineated in vivo using both b the Artemis and c Pearl. f In vivo tumor signal-to-background ratios (SBR) were calculated. Twenty-four hours after injection of 7D12-800CW and R2-800CW, all tumors were repeatedly halved until submillimeter size. Tumor pieces were measured using the d Artemis and e Pearl. g Contrast-to-noise ratios (CNR) were plotted against the volume of the tumor pieces. Ruler lines denote millimeters. K = kidney; T = tumor; M = muscle; A = Artemis; P = Pearl.

Fig. 6

Near-infrared fluorescence imaging of colorectal liver metastases: 24 h after injection of 10 mg indocyanine green, colorectal liver metastases could clearly be identified by a rim around the tumor (I and II). Benign lesion (III) could be identified by fluorescence without the rim. Images are depicted in a visible light, b NIR fluorescence signal, and c a real-time overlay.