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Toward optimization of imaging system and lymphatic tracer for near-infrared fluorescent sentinel lymph node mapping in breast cancer.

Mieog JS, Troyan SL, Hutteman M, Donohoe KJ, van der Vorst JR, Stockdale A, Liefers GJ, Choi HS, Gibbs-Strauss SL, Putter H, Gioux S, Kuppen PJ, Ashitate Y, Löwik CW, Smit VT, Oketokoun R, Ngo LH, van de Velde CJ, Frangioni JV, Vahrmeijer AL - Ann. Surg. Oncol. (2011)

Bottom Line: Contrast agent quenching at the injection site and dilution within lymphatic channels were major contributors to signal strength of the SLN.Optimal injection dose of ICG:HSA ranged between 400 and 800 μM.No adverse reactions were observed.

View Article: PubMed Central - PubMed

Affiliation: Department of Surgery, Leiden University Medical Center, Leiden, The Netherlands.

ABSTRACT

Background: Near-infrared (NIR) fluorescent sentinel lymph node (SLN) mapping in breast cancer requires optimized imaging systems and lymphatic tracers.

Materials and methods: A small, portable version of the FLARE imaging system, termed Mini-FLARE, was developed for capturing color video and two semi-independent channels of NIR fluorescence (700 and 800 nm) in real time. Initial optimization of lymphatic tracer dose was performed using 35-kg Yorkshire pigs and a 6-patient pilot clinical trial. More refined optimization was performed in 24 consecutive breast cancer patients. All patients received the standard of care using (99m)Technetium-nanocolloid and patent blue. In addition, 1.6 ml of indocyanine green adsorbed to human serum albumin (ICG:HSA) was injected directly after patent blue at the same location. Patients were allocated to 1 of 8 escalating ICG:HSA concentration groups from 50 to 1000 μM.

Results: The Mini-FLARE system was positioned easily in the operating room and could be used up to 13 in. from the patient. Mini-FLARE enabled visualization of lymphatic channels and SLNs in all patients. A total of 35 SLNs (mean = 1.45, range 1-3) were detected: 35 radioactive (100%), 30 blue (86%), and 35 NIR fluorescent (100%). Contrast agent quenching at the injection site and dilution within lymphatic channels were major contributors to signal strength of the SLN. Optimal injection dose of ICG:HSA ranged between 400 and 800 μM. No adverse reactions were observed.

Conclusions: We describe the clinical translation of a new NIR fluorescence imaging system and define the optimal ICG:HSA dose range for SLN mapping in breast cancer.

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Related in: MedlinePlus

Optimization of ICG:HSA dose as a function of the complex trade-off between fluorescence quenching at the injection site and dilution of fluorophore in lymphatic channels. a Preclinical studies in Yorkshire pigs. Subcutaneous injection sites (left; white arrows) showing quenching and resected SLNs (right) showing NIR fluorophore dilution for increasing concentrations of ICG:HSA. For each are displayed color video (left columns) and 800 nm NIR fluorescence (right columns) images obtained using 760 nm excitation light at 7.7 mW/cm2. All camera exposure times were 45 ms. Data are representative of n = 3 pigs. b Optimization of ICG:HSA dose for breast cancer SLN mapping: Signal-to-background ratio (mean ± SD) of the SLNs (ordinate) as a function of injected dose of ICG:HSA (abscissa) in women undergoing SLN mapping for breast cancer. Statistical comparisons are: 200 vs. 400 μM, P = .001; 200 vs. 500 μM, P = .001; 200 vs. 600 μM, P < .0001; 200 vs. 800 μM, P = .001; 1000 vs. 400 μM, P < .0001; 1000 vs. 500 μM, P < .0001; 1000 vs. 600 μM, P < .0001; 1000 vs. 800 μM, P < .0001. The SBRs of the 400, 500, 600, and 800 μM concentration groups were not significantly different, although a trend was found favoring the 600 μM concentration group (500 vs. 600, P = .06)
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Fig2: Optimization of ICG:HSA dose as a function of the complex trade-off between fluorescence quenching at the injection site and dilution of fluorophore in lymphatic channels. a Preclinical studies in Yorkshire pigs. Subcutaneous injection sites (left; white arrows) showing quenching and resected SLNs (right) showing NIR fluorophore dilution for increasing concentrations of ICG:HSA. For each are displayed color video (left columns) and 800 nm NIR fluorescence (right columns) images obtained using 760 nm excitation light at 7.7 mW/cm2. All camera exposure times were 45 ms. Data are representative of n = 3 pigs. b Optimization of ICG:HSA dose for breast cancer SLN mapping: Signal-to-background ratio (mean ± SD) of the SLNs (ordinate) as a function of injected dose of ICG:HSA (abscissa) in women undergoing SLN mapping for breast cancer. Statistical comparisons are: 200 vs. 400 μM, P = .001; 200 vs. 500 μM, P = .001; 200 vs. 600 μM, P < .0001; 200 vs. 800 μM, P = .001; 1000 vs. 400 μM, P < .0001; 1000 vs. 500 μM, P < .0001; 1000 vs. 600 μM, P < .0001; 1000 vs. 800 μM, P < .0001. The SBRs of the 400, 500, 600, and 800 μM concentration groups were not significantly different, although a trend was found favoring the 600 μM concentration group (500 vs. 600, P = .06)

Mentions: Our group has previously reported that ICG (and ICG:HSA) exhibits intense quenching (i.e., reduction of fluorescence emission) as its concentration is increased.15 That is, increasing concentration actually decreases fluorescence, so there would theoretically be no benefit to injecting high concentration for SLN mapping. This effect is demonstrated vividly in Fig. 2a (left), where the injection site becomes dramatically less fluorescent as concentration increases. As a general rule, if the concentration is high enough to see green color at the injection site, ICG fluorescence is severely quenched.Fig. 2


Toward optimization of imaging system and lymphatic tracer for near-infrared fluorescent sentinel lymph node mapping in breast cancer.

Mieog JS, Troyan SL, Hutteman M, Donohoe KJ, van der Vorst JR, Stockdale A, Liefers GJ, Choi HS, Gibbs-Strauss SL, Putter H, Gioux S, Kuppen PJ, Ashitate Y, Löwik CW, Smit VT, Oketokoun R, Ngo LH, van de Velde CJ, Frangioni JV, Vahrmeijer AL - Ann. Surg. Oncol. (2011)

Optimization of ICG:HSA dose as a function of the complex trade-off between fluorescence quenching at the injection site and dilution of fluorophore in lymphatic channels. a Preclinical studies in Yorkshire pigs. Subcutaneous injection sites (left; white arrows) showing quenching and resected SLNs (right) showing NIR fluorophore dilution for increasing concentrations of ICG:HSA. For each are displayed color video (left columns) and 800 nm NIR fluorescence (right columns) images obtained using 760 nm excitation light at 7.7 mW/cm2. All camera exposure times were 45 ms. Data are representative of n = 3 pigs. b Optimization of ICG:HSA dose for breast cancer SLN mapping: Signal-to-background ratio (mean ± SD) of the SLNs (ordinate) as a function of injected dose of ICG:HSA (abscissa) in women undergoing SLN mapping for breast cancer. Statistical comparisons are: 200 vs. 400 μM, P = .001; 200 vs. 500 μM, P = .001; 200 vs. 600 μM, P < .0001; 200 vs. 800 μM, P = .001; 1000 vs. 400 μM, P < .0001; 1000 vs. 500 μM, P < .0001; 1000 vs. 600 μM, P < .0001; 1000 vs. 800 μM, P < .0001. The SBRs of the 400, 500, 600, and 800 μM concentration groups were not significantly different, although a trend was found favoring the 600 μM concentration group (500 vs. 600, P = .06)
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Fig2: Optimization of ICG:HSA dose as a function of the complex trade-off between fluorescence quenching at the injection site and dilution of fluorophore in lymphatic channels. a Preclinical studies in Yorkshire pigs. Subcutaneous injection sites (left; white arrows) showing quenching and resected SLNs (right) showing NIR fluorophore dilution for increasing concentrations of ICG:HSA. For each are displayed color video (left columns) and 800 nm NIR fluorescence (right columns) images obtained using 760 nm excitation light at 7.7 mW/cm2. All camera exposure times were 45 ms. Data are representative of n = 3 pigs. b Optimization of ICG:HSA dose for breast cancer SLN mapping: Signal-to-background ratio (mean ± SD) of the SLNs (ordinate) as a function of injected dose of ICG:HSA (abscissa) in women undergoing SLN mapping for breast cancer. Statistical comparisons are: 200 vs. 400 μM, P = .001; 200 vs. 500 μM, P = .001; 200 vs. 600 μM, P < .0001; 200 vs. 800 μM, P = .001; 1000 vs. 400 μM, P < .0001; 1000 vs. 500 μM, P < .0001; 1000 vs. 600 μM, P < .0001; 1000 vs. 800 μM, P < .0001. The SBRs of the 400, 500, 600, and 800 μM concentration groups were not significantly different, although a trend was found favoring the 600 μM concentration group (500 vs. 600, P = .06)
Mentions: Our group has previously reported that ICG (and ICG:HSA) exhibits intense quenching (i.e., reduction of fluorescence emission) as its concentration is increased.15 That is, increasing concentration actually decreases fluorescence, so there would theoretically be no benefit to injecting high concentration for SLN mapping. This effect is demonstrated vividly in Fig. 2a (left), where the injection site becomes dramatically less fluorescent as concentration increases. As a general rule, if the concentration is high enough to see green color at the injection site, ICG fluorescence is severely quenched.Fig. 2

Bottom Line: Contrast agent quenching at the injection site and dilution within lymphatic channels were major contributors to signal strength of the SLN.Optimal injection dose of ICG:HSA ranged between 400 and 800 μM.No adverse reactions were observed.

View Article: PubMed Central - PubMed

Affiliation: Department of Surgery, Leiden University Medical Center, Leiden, The Netherlands.

ABSTRACT

Background: Near-infrared (NIR) fluorescent sentinel lymph node (SLN) mapping in breast cancer requires optimized imaging systems and lymphatic tracers.

Materials and methods: A small, portable version of the FLARE imaging system, termed Mini-FLARE, was developed for capturing color video and two semi-independent channels of NIR fluorescence (700 and 800 nm) in real time. Initial optimization of lymphatic tracer dose was performed using 35-kg Yorkshire pigs and a 6-patient pilot clinical trial. More refined optimization was performed in 24 consecutive breast cancer patients. All patients received the standard of care using (99m)Technetium-nanocolloid and patent blue. In addition, 1.6 ml of indocyanine green adsorbed to human serum albumin (ICG:HSA) was injected directly after patent blue at the same location. Patients were allocated to 1 of 8 escalating ICG:HSA concentration groups from 50 to 1000 μM.

Results: The Mini-FLARE system was positioned easily in the operating room and could be used up to 13 in. from the patient. Mini-FLARE enabled visualization of lymphatic channels and SLNs in all patients. A total of 35 SLNs (mean = 1.45, range 1-3) were detected: 35 radioactive (100%), 30 blue (86%), and 35 NIR fluorescent (100%). Contrast agent quenching at the injection site and dilution within lymphatic channels were major contributors to signal strength of the SLN. Optimal injection dose of ICG:HSA ranged between 400 and 800 μM. No adverse reactions were observed.

Conclusions: We describe the clinical translation of a new NIR fluorescence imaging system and define the optimal ICG:HSA dose range for SLN mapping in breast cancer.

Show MeSH
Related in: MedlinePlus