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Fast 18F labeling of a near-infrared fluorophore enables positron emission tomography and optical imaging of sentinel lymph nodes.

Ting R, Aguilera TA, Crisp JL, Hall DJ, Eckelman WC, Vera DR, Tsien RY - Bioconjug. Chem. (2010)

Bottom Line: The new conjugate incorporates (18)F(-) in a single, aqueous step, targets mouse SLN rapidly (1 h) with reduced distal lymph node accumulation, permits PET or scintigraphic imaging of SLN, and enables NIRF-guided excision and histological verification even after (18)F decay.This embodiment is superior to current SLN mapping agents such as nontargeted [(99m)Tc]sulfur colloids and Isosulfan Blue, as well as the phase III targeted ligand [(99m)Tc]SPECT Lymphoseek counterpart, species that are visible by SPECT or visible absorbance separately.Facile incorporation of (18)F into a NIRF probe should promote many synergistic PET and NIRF combinations.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology, University of California, San Diego, La Jolla, California 92093, USA.

ABSTRACT
We combine a novel boronate trap for F(-) with a near-infrared fluorophore into a single molecule. Attachment to targeting ligands enables localization by positron emission tomography (PET) and near-infrared fluorescence (NIRF). Our first application of this generic tag is to label Lymphoseek (tilmanocept), an agent designed for receptor-specific sentinel lymph node (SLN) mapping. The new conjugate incorporates (18)F(-) in a single, aqueous step, targets mouse SLN rapidly (1 h) with reduced distal lymph node accumulation, permits PET or scintigraphic imaging of SLN, and enables NIRF-guided excision and histological verification even after (18)F decay. This embodiment is superior to current SLN mapping agents such as nontargeted [(99m)Tc]sulfur colloids and Isosulfan Blue, as well as the phase III targeted ligand [(99m)Tc]SPECT Lymphoseek counterpart, species that are visible by SPECT or visible absorbance separately. Facile incorporation of (18)F into a NIRF probe should promote many synergistic PET and NIRF combinations.

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Multimodality imaging of a mouse injected with a 10 μL, 1 nmol, 48.1 μCi dose of 18F-labeled Lymphoseek 3 (0.048 Ci/μmol). The red arrows indicates the location of the sentinel lymph node. (A) Pre-excision, live-mouse PET (red color table)/CT (blue color table) scan (left) and postoperative PET/CT scan (right) of the mouse with excised nodes (right and left lumbar and popliteal) that are placed below the excision site in the field of view. (B) Bright field images of the mouse with skin removed before (left) and after node excision (right). (C) NIRF images taken 90 min postexcision on a custom full field IR camera before (left) and after (right) lymph node excision. The injection site was covered with black cardboard to block intense signal from the foot and allow better visualization of the fluorescent lymph nodes. (D) H and E stain (top, color images) and NIRF (bottom, black and white images) histological verification of lymph node excision. A PET projection video of panel A is given as Supporting Information.
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fig3: Multimodality imaging of a mouse injected with a 10 μL, 1 nmol, 48.1 μCi dose of 18F-labeled Lymphoseek 3 (0.048 Ci/μmol). The red arrows indicates the location of the sentinel lymph node. (A) Pre-excision, live-mouse PET (red color table)/CT (blue color table) scan (left) and postoperative PET/CT scan (right) of the mouse with excised nodes (right and left lumbar and popliteal) that are placed below the excision site in the field of view. (B) Bright field images of the mouse with skin removed before (left) and after node excision (right). (C) NIRF images taken 90 min postexcision on a custom full field IR camera before (left) and after (right) lymph node excision. The injection site was covered with black cardboard to block intense signal from the foot and allow better visualization of the fluorescent lymph nodes. (D) H and E stain (top, color images) and NIRF (bottom, black and white images) histological verification of lymph node excision. A PET projection video of panel A is given as Supporting Information.

Mentions: NIRF imaging was conducted using multiple cameras because of radioactive licensing regulations. IR image acquisition of the nonradioactive compositions in Figure 2 was performed on a Maestro small animal imaging instrument (CRI Inc.) with a 820 nm emission filter and a 710−760 nm excitation wavelength. Data were collected over a 0.5−20 s exposure. Image processing was performed with Maestro version 2.0.2 and Photoshop. The Maestro, used for Figure 2, was the best instrument for real-time, fluorescence-guided node excision, although a custom system optimized for real-time intraoperative imaging would be yet more convenient. The success of sentinel lymph node excision was 100% as determined by histology with the Maestro. Because animals containing 18F could not be transported to the Maestro, NIRF in vivo image acquisition of 18F-labeled compounds was performed on two systems closer to the hot cell and PET scanner. The first was an eXplore Optix (ART, Advanced Research Technologies Inc.) optical imaging system. This is a point source-detector system with a 750 nm excitation laser and a 780 nm long pass filter placed before the photomultiplier tube for single-photon fluorescence detection. The regions of interest were raster-scanned in 1.5 mm steps with laser powers ranging from 200 to 800 μW and signal integration times ranging from 200 to 1000 ms per point. Image processing was performed with Optix version 2 and Photoshop. However, the slow raster scan of the Optix made real-time, image-guided node excision difficult, so a custom full field system (37) was employed for faster NIRF imaging of 18F-labeled compounds (Figure 3C). This system used a pulsed laser tuned to 720 nm (Mai TaiSpectraPhysics) whose output was passed through an expansion lens and diffuser for uniform area illumination. Area detection of the fluorescence intensity was acquired in reflection mode using a 780 nm fluorescence filter and standard 50 mm lens (Nikon) mounted to a microchannel plate (Picostar HRI, La Vision) for signal amplification, which was coupled to an electron-multiplying CCD camera (Andor) to capture the image. Subsequent image processing was performed with Image J and Photoshop. Both the Optix and custom systems can measure nanosecond decay kinetics to provide extra information about probe lifetime and depth, but this dimension was not exploited here.


Fast 18F labeling of a near-infrared fluorophore enables positron emission tomography and optical imaging of sentinel lymph nodes.

Ting R, Aguilera TA, Crisp JL, Hall DJ, Eckelman WC, Vera DR, Tsien RY - Bioconjug. Chem. (2010)

Multimodality imaging of a mouse injected with a 10 μL, 1 nmol, 48.1 μCi dose of 18F-labeled Lymphoseek 3 (0.048 Ci/μmol). The red arrows indicates the location of the sentinel lymph node. (A) Pre-excision, live-mouse PET (red color table)/CT (blue color table) scan (left) and postoperative PET/CT scan (right) of the mouse with excised nodes (right and left lumbar and popliteal) that are placed below the excision site in the field of view. (B) Bright field images of the mouse with skin removed before (left) and after node excision (right). (C) NIRF images taken 90 min postexcision on a custom full field IR camera before (left) and after (right) lymph node excision. The injection site was covered with black cardboard to block intense signal from the foot and allow better visualization of the fluorescent lymph nodes. (D) H and E stain (top, color images) and NIRF (bottom, black and white images) histological verification of lymph node excision. A PET projection video of panel A is given as Supporting Information.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
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fig3: Multimodality imaging of a mouse injected with a 10 μL, 1 nmol, 48.1 μCi dose of 18F-labeled Lymphoseek 3 (0.048 Ci/μmol). The red arrows indicates the location of the sentinel lymph node. (A) Pre-excision, live-mouse PET (red color table)/CT (blue color table) scan (left) and postoperative PET/CT scan (right) of the mouse with excised nodes (right and left lumbar and popliteal) that are placed below the excision site in the field of view. (B) Bright field images of the mouse with skin removed before (left) and after node excision (right). (C) NIRF images taken 90 min postexcision on a custom full field IR camera before (left) and after (right) lymph node excision. The injection site was covered with black cardboard to block intense signal from the foot and allow better visualization of the fluorescent lymph nodes. (D) H and E stain (top, color images) and NIRF (bottom, black and white images) histological verification of lymph node excision. A PET projection video of panel A is given as Supporting Information.
Mentions: NIRF imaging was conducted using multiple cameras because of radioactive licensing regulations. IR image acquisition of the nonradioactive compositions in Figure 2 was performed on a Maestro small animal imaging instrument (CRI Inc.) with a 820 nm emission filter and a 710−760 nm excitation wavelength. Data were collected over a 0.5−20 s exposure. Image processing was performed with Maestro version 2.0.2 and Photoshop. The Maestro, used for Figure 2, was the best instrument for real-time, fluorescence-guided node excision, although a custom system optimized for real-time intraoperative imaging would be yet more convenient. The success of sentinel lymph node excision was 100% as determined by histology with the Maestro. Because animals containing 18F could not be transported to the Maestro, NIRF in vivo image acquisition of 18F-labeled compounds was performed on two systems closer to the hot cell and PET scanner. The first was an eXplore Optix (ART, Advanced Research Technologies Inc.) optical imaging system. This is a point source-detector system with a 750 nm excitation laser and a 780 nm long pass filter placed before the photomultiplier tube for single-photon fluorescence detection. The regions of interest were raster-scanned in 1.5 mm steps with laser powers ranging from 200 to 800 μW and signal integration times ranging from 200 to 1000 ms per point. Image processing was performed with Optix version 2 and Photoshop. However, the slow raster scan of the Optix made real-time, image-guided node excision difficult, so a custom full field system (37) was employed for faster NIRF imaging of 18F-labeled compounds (Figure 3C). This system used a pulsed laser tuned to 720 nm (Mai TaiSpectraPhysics) whose output was passed through an expansion lens and diffuser for uniform area illumination. Area detection of the fluorescence intensity was acquired in reflection mode using a 780 nm fluorescence filter and standard 50 mm lens (Nikon) mounted to a microchannel plate (Picostar HRI, La Vision) for signal amplification, which was coupled to an electron-multiplying CCD camera (Andor) to capture the image. Subsequent image processing was performed with Image J and Photoshop. Both the Optix and custom systems can measure nanosecond decay kinetics to provide extra information about probe lifetime and depth, but this dimension was not exploited here.

Bottom Line: The new conjugate incorporates (18)F(-) in a single, aqueous step, targets mouse SLN rapidly (1 h) with reduced distal lymph node accumulation, permits PET or scintigraphic imaging of SLN, and enables NIRF-guided excision and histological verification even after (18)F decay.This embodiment is superior to current SLN mapping agents such as nontargeted [(99m)Tc]sulfur colloids and Isosulfan Blue, as well as the phase III targeted ligand [(99m)Tc]SPECT Lymphoseek counterpart, species that are visible by SPECT or visible absorbance separately.Facile incorporation of (18)F into a NIRF probe should promote many synergistic PET and NIRF combinations.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology, University of California, San Diego, La Jolla, California 92093, USA.

ABSTRACT
We combine a novel boronate trap for F(-) with a near-infrared fluorophore into a single molecule. Attachment to targeting ligands enables localization by positron emission tomography (PET) and near-infrared fluorescence (NIRF). Our first application of this generic tag is to label Lymphoseek (tilmanocept), an agent designed for receptor-specific sentinel lymph node (SLN) mapping. The new conjugate incorporates (18)F(-) in a single, aqueous step, targets mouse SLN rapidly (1 h) with reduced distal lymph node accumulation, permits PET or scintigraphic imaging of SLN, and enables NIRF-guided excision and histological verification even after (18)F decay. This embodiment is superior to current SLN mapping agents such as nontargeted [(99m)Tc]sulfur colloids and Isosulfan Blue, as well as the phase III targeted ligand [(99m)Tc]SPECT Lymphoseek counterpart, species that are visible by SPECT or visible absorbance separately. Facile incorporation of (18)F into a NIRF probe should promote many synergistic PET and NIRF combinations.

Show MeSH
Related in: MedlinePlus