modalities make sense?
F: By switching off the laser pointer clear SN visualization via fluorescence imaging was possible.
SI Figure 2. Intraoperative fluorescence imaging of SNs. A: White light image of the area harboring the SN;
B: Fluorescence imaging of the area under A allowed optical confirmation of having localized the SN;
C: Fluorescence imaging of the same SN as in D, with intact skin. No fluorescence signal could be detected, while gamma detection was possible (picture in picture right under).
D: After tissue preparation, the borders of the fluorescent SNs were clearly shown (picture in picture: corresponding white light image);
E: The laser pointer of the portable gamma camera interfered with fluorescence imaging; SN detection was possible, although detection was not very efficient.
DISCUSSION
This study describes two hybrid imaging set-ups (VITOM-GP and VITOM-GC) and their potential to provide surgical guidance in combination with the hybrid tracer ICG-99mTc-
nanocolloid. In both set-ups the in-depth information of the gamma signal was used to determine the site of incision and provided directional guidance for positioning of the VITOM. When the SN was exposed fluorescence imaging could be used to visually detect the SNs with respect to the anatomical context. These findings clearly underline the strengths and weaknesses of the two individual imaging signatures. Moreover, the reported detection percentages show that the hybrid modality-based find rates are highly similar to those previously reported for the individual modalities [13]. The current prototype set-up was not optimized from an efficacy point of view and their use influenced operating room logistics and the operation time. Nevertheless, in future studies, it remains to be evaluated it the use of an optimized hybrid modality can result in reduced morbidity, operation time and postoperative infection rates.
From the findings of the current study we were able to derive a number of engineering challenges that have to be faced before imaging-based hybrid surgical guidance modalities will become efficient tools for routine use. The clip-on design was considered convenient as it efficiently combined two clinically available modalities, but still allowed for their individual use. Unfortunately, the angled alignment was not optimal for distances smaller or larger than the focal plane. In both combined devices the angle between the modalities dictated spatial placement in order to get the information from the SN for both modalities (Figure 1). Most likely future hybrid modalities will require both modalities to be placed perpendicular to each other and with an identical field of view. Though this will require full hardware integration. The findings of the current study also suggest that placement of both image guidance modalities on a stable, but retractable, arm could be of value.
In the current set up the optimal detection plane of the individual modalities was shown to differ for the VITOM (>11 cm), GP (0-10 cm) and GC (0-30 cm). Furthermore, intraoperative adaptation of the fluorescence focus was considered inconvenient. The concept of hybrid imaging hardware could only be accurately evaluated in the focal plane of the VITOM (≈11 cm). In future hybrid devices the focus of the two modalities should be matched, at least in a certain range. Possibly an autofocus option should also be included for the optical imaging. The difference in fluorescence detection between the VITOM-GP and VITOM-GP could partly be explained by the failure of fluorescence detection in a patient with a body mass index
over 40. Fatty tissue hampers the fluorescence signal detection and this risk increases in patients with obesity.
The largest and final hurdle to be tackled, however, will be the difference in detection sensitivity between the radioguidance and fluorescence modalities used. Although full integration is possible from an engineering point of view, its realization is not straightforward when combination of state-of-the art detector sensitivity for both fluorescence and radioactivity is envisioned. Especially when considering that the fluorescence modality could benefit from higher fluorescence sensitivity at longer distances. This would require both a stronger excitation light-source and higher detection sensitivity. The white light option should remain included as this information created directional feedback and provided anatomical context. The difference in sensitivity between the GP and GC modalities influenced the acquisition time, collimation and field of view [2,6], all of which can be improved further.
Overall the VITOM-GP combination was preferred by the surgeons over the VITOM-GC combination. The reason for this was that the acoustic/numerical feedback provided by the GP provided information that could be processed simultaneously with the fluorescence imaging findings. Hereby two sensory organs, ears and eyes, work in conjunction, providing directional guidance for the placement of the fluorescence camera. In contrast, parallel display of the VITOM and GC findings relied on a single sensory organ, making it more difficult to process. Having the display of the two different imaging findings on two different screens was sometimes considered confusing. Hereby especially the lack of anatomical information in the GC images made it difficult to relate them to the fluorescence imaging findings. The value of the VITOM-GC combination could potentially increase when both imaging findings are integrated in a single (video screen) display, a technology that we previously successfully applied in a navigation set-up [23].
CONCLUSION
In this study we demonstrated that combined radio- and fluorescence imaging modalities have the potential to make sense in the hybrid surgical guidance concept. The integrated detection modalities were shown to work synergistically; overall the GC was most valuable for rough localization (10-30cm range) of the SNs, the GP for providing convenient real-time acoustic feedback, while fluorescence guidance allowed detailed real-time SN visualization.
Hybrid surgical guidance: Does hardware integration of gamma- and fluorescence- imaging modalities make sense? | 155
REFERENCES
1. KleinJan GH, Bunschoten a., Brouwer OR, Berg NS, Valdés-Olmos R a., Leeuwen FWB. Multimodal imaging in radioguided surgery. Clin Transl Imaging [Internet]. 2013 Dec 4 [cited 2014 Feb 3];1(6):433–44.
2. Povoski SP, Neff RL, Mojzisik CM, O’Malley DM, Hinkle GH, Hall NC, et al. A comprehensive overview of radioguided surgery using gamma detection probe technology. World J Surg Oncol [Internet]. 2009 Jan [cited 2013 Feb 14];7:11. 3. Nieweg OE, Tanis PJ, Kroon BB. The definition of a sentinel node. Ann Surg Oncol . 2001 Jul;8(6):538–41.
4. Heller S, Zanzonico P. Nuclear probes and intraoperative gamma cameras. Semin Nucl Med. Elsevier Inc.; 2011;41(3):166– 81.
5. Vermeeren L, Valdés Olmos RA, Klop WMC, Balm AJM, van den Brekel MWM. A portable gamma-camera for intraoperative detection of sentinel nodes in the head and neck region. J Nucl Med. 2010;51(5):700–3.
6. Tsuchimochi M, Hayama K. Intraoperative gamma cameras for radioguided surgery: technical characteristics, performance parameters, and clinical applications. Phys Med. 2013;29(2):126–38.
7. Hellingman D, Vidal-Sicart S, de Wit-van der Veen LJ, Paredes P, Valdés Olmos RA. A New Portable Hybrid Camera for Fused Optical and Scintigraphic Imaging: First Clinical Experiences. Clin Nucl Med. 2016 Jan;41(1):e39-43.
8. Lees JE, Bassford DJ, Blake OE, Blackshaw PE, Perkins AC. A Hybrid Camera for simultaneous imaging of gamma and optical photons. J Instrum. 2012;7(06):P06009–P06009.
9. Morton DL, Wen DR, Wong JH, Economou JS, Cagle LA, Storm FK, et al. Technical details of intraoperative lymphatic mapping for early stage melanoma. Arch Surg. 1992;127(4):392–399.
10. van Leeuwen FWB, Hardwick JCH, van Erkel AR. Luminescence-based Imaging Approaches in the Field of Interventional Molecular Imaging. Radiology. 2015;276(1):12–29.
11. Stoffels I, Leyh J, Pöppel T, Schadendorf D, Klode J. Evaluation of a radioactive and fluorescent hybrid tracer for sentinel lymph node biopsy in head and neck malignancies: prospective randomized clinical trial to compare ICG-(99m)Tc- nanocolloid hybrid tracer versus (99m)Tc-nanocolloid. Eur J Nucl Med Mol Imaging 2015;42(11):1631-1638
12. Brouwer OR, Buckle T, Vermeeren L, Klop WMC, Balm AJM, van der Poel HG, et al. Comparing the hybrid fluorescent- radioactive tracer indocyanine green-99mTc-nanocolloid with 99mTc-nanocolloid for sentinel node identification: a validation study using lymphoscintigraphy and SPECT/CT. J Nucl Med. 2012;53(7):1034–40.
13. Brouwer OR, van den Berg NS, Mathéron HM, van der Poel HG, van Rhijn BW, Bex A, et al. A hybrid radioactive and fluorescent tracer for sentinel node biopsy in penile carcinoma as a potential replacement for blue dye. Eur Urol. 2014;65(3):600–9.
14. KleinJan GH, van den Berg NS, Brouwer OR, de Jong J, Acar C, Wit EM, et al. Optimisation of Fluorescence Guidance During Robot-assisted Laparoscopic Sentinel Node Biopsy for Prostate Cancer. Eur Urol. 2014;66(6):991–8.
15. Christensen A, Juhl K, Charabi B, Mortensen J, Kiss K, Kjær A, et al. Feasibility of Real-Time Near-Infrared Fluorescence Tracer Imaging in Sentinel Node Biopsy for Oral Cavity Cancer Patients. Ann Surg Oncol. 2016;23(2):565–72. 16. Brouwer OR, Buckle T, Bunschoten A, Kuil J, Vahrmeijer AL, Wendler T, et al. Image navigation as a means to expand the
boundaries of fluorescence-guided surgery. Phys Med Biol. 2012;57(10):3123–36.
17. KleinJan GH, van den Berg NS, van Oosterom MN, Wendler T, Miwa M, Bex A, et al. Towards (hybrid) navigation of a fluorescence camera in an open surgery setting. J Nucl Med. 2016;57(10):1650-1653.
18. van den Berg NS, Simon H, Kleinjan GH, Engelen T, Bunschoten A, Welling MM, et al. First-in-human evaluation of a hybrid modality that allows combined radio- and (near-infrared) fluorescence tracing during surgery. Eur J Nucl Med Mol Imaging. 2015;42(11):1639-47
19. Mamelak AN, Drazin D, Shirzadi A, Black KL, Berci G. Infratentorial supracerebellar resection of a pineal tumor using a high definition video exoscope (VITOM®). J Clin Neurosci. 2012;19(2):306–9.
20. Buda A, Dell’Anna T, Vecchione F, Verri D, Di Martino G, Milani R. Near-Infrared Sentinel Lymph Node Mapping With Indocyanine Green Using the VITOM II ICG Exoscope for Open Surgery for Gynecologic Malignancies. J Minim Invasive Gynecol. 2016;(4):628-32.
21. Sánchez F, Benlloch JM, Escat B, Pavón N, Porras E, Kadi-Hanifi D, et al. Design and tests of a portable mini gamma camera. Med Phys. 2004;31(6):1384–97.
22. van den Berg NS, Miwa M, KleinJan GH, Sato T, Maeda Y, van Akkooi ACJ, et al. (Near-Infrared) Fluorescence-Guided Surgery Under Ambient Light Conditions: A Next Step to Embedment of the Technology in Clinical Routine. Ann Surg Oncol. 2016;23(8):2586–2595.
23. KleinJan GH, Bunschoten A, van den Berg NS, Valdes Olmos RA, Klop WMC, Horenblas S, et al. Fluorescence guided surgery and tracer-dose, fact or fiction? Eur J Nucl Med Mol Imaging. 2016;43(10):1857-1867
Hybrid surgical guidance: Does hardware integration of gamma- and fluorescence- imaging modalities make sense? | 157
208
Figures
Figure 1. Fluorescence camera navigation
Figure 2. Navigation of the FC. Video signal of the overhead camera of naviga
tion system allows projection of
SPECT/CT (A) or SPECT (B) onto the patient. Bony structures (low-dose CT) and
SNs/injection site (SPECT) are
shown. (C) Overlay of the SPECT on near-infrared video signal of the FC showing
2 SNs. (D) Fluorescence imaging
optically visualized the SN and thus allowed confirmation of FC navigation accura cy.
208
Figures
Figure 1. Fluorescence camera navigation
Figure 2. Navigation of the FC. Video signal of the overhead camera of naviga
tion system allows projection of
SPECT/CT (A) or SPECT (B) onto the patient. Bony structures (low-dose CT) and
SNs/injection site (SPECT) are
shown. (C) Overlay of the SPECT on near-infrared video signal of the FC showing
2 SNs. (D) Fluorescence imaging
optically visualized the SN and thus allowed confirmation of FC navigation accuracy.
Chapter 8
1
2
3
4
5
6
7
8
9
10
11
12
13
208 FiguresFigure 1. Fluorescence camera navigation
Figure 2. Navigation of the FC. Video signal of the overhead camera of naviga
tion system allows projection of SPECT/CT (A) or SPECT (B) onto the patient. Bony structures (low-dose CT) and
SNs/injection site (SPECT) are shown. (C) Overlay of the SPECT on near-infrared video signal of the FC showing
2 SNs. (D) Fluorescence imaging optically visualized the SN and thus allowed confirmation of FC navigation accura
cy.
208
Figures
Figure 1. Fluorescence camera navigation
Figure 2. Navigation of the FC. Video signal of the overhead camera of navigation system allows projection of SPECT/CT (A) or SPECT (B) onto the patient. Bony structures (low-dose CT) and SNs/injection site (SPECT) are shown. (C) Overlay of the SPECT on near-infrared video signal of the FC showing 2 SNs. (D) Fluorescence imaging optically visualized the SN and thus allowed confirmation of FC navigation accuracy.
208
Figures
Figure 1. Fluorescence camera navigation
Figure 2. Navigation of the FC. Video signal of the overhead camera of naviga
tion system allows projection of
SPECT/CT (A) or SPECT (B) onto the patient. Bony structures (low-dose CT) and
SNs/injection site (SPECT) are
shown. (C) Overlay of the SPECT on near-infrared video signal of the FC showing
2 SNs. (D) Fluorescence imaging
optically visualized the SN and thus allowed confirmation of FC navigation accura cy.
208
Figures
Figure 1. Fluorescence camera navigation
Figure 2. Navigation of the FC. Video signal of the overhead camera of naviga
tion system allows projection of
SPECT/CT (A) or SPECT (B) onto the patient. Bony structures (low-dose CT) and
SNs/injection site (SPECT) are
shown. (C) Overlay of the SPECT on near-infrared video signal of the FC showing
2 SNs. (D) Fluorescence imaging
optically visualized the SN and thus allowed confirmation of FC navigation accura cy.