99mTc-Human Albumin Nanocolloids is a radiopharmaceutical agent used as a generic tracer for lymphoscintigraphy, particularly for imaging sentinel nodes. It consists of human albumin nanoparticles labeled with the radioisotope technetium-99m (99mTc), which emits gamma radiation that can be detected by imaging techniques such as single-photon emission computed tomography (SPECT).
When injected into the body, 99mTc-Human Albumin Nanocolloids are taken up by the lymphatic system and accumulate in the sentinel lymph nodes, which are the first lymph nodes to receive drainage from a tumor site. By visualizing the uptake of the tracer in these nodes, healthcare providers can identify the pathways of lymphatic drainage and determine the potential spread of cancer cells.
Lymphoscintigraphy using 99mTc-Human Albumin Nanocolloids is a valuable tool in various cancer surgeries, particularly in breast cancer and melanoma, where accurate identification of sentinel nodes is crucial for staging and treatment planning. It helps surgeons locate and remove the sentinel nodes for pathological examination, aiding in the diagnosis and management of cancer patients.
Overall, 99mTc-Human Albumin Nanocolloids play a vital role in lymphatic mapping and sentinel node detection, providing valuable information for oncologic procedures and improving patient outcomes.
Description
99mTc-Human Albumin Nanocolloids (Human Serum Albumin, HSA) is a generic tracer used as injected molecule for the imaging of sentinel nodes (lymphoscintigraphy). 95% of the particles must have a diameter smaller than 80 µm.
Clinical applications
99mTc-Labeled nanoparticles of human serum albumin (HSA) are suitable for sentinel node lymphoscintigraphy (breast cancer, melanoma, head and neck tumors), bone marrow scanning, inflammation imaging or subcutaneous lymphatic scanning. Subcutaneous doses used for lymphatic scanning are around 0.5 mCi per injection site, while inflammation and bone marrow scanning need 5 to 15 mCi.
Some formulations of HSA nanoparticles are used for inhalation scintigraphy, i.e., to perform the quantitative assessment of pulmonary ventilation (as complement for the lung perfusion studies) and the diagnosis of pulmonary embolism and obstructive pulmonary disease. About 3 mCi needs to be inhaled by the patient.
Availability and price
Products for lymphoscintigraphy (size ranges of particles are given between brackets):
- BRIT (TCK-53), GE Healthcare (Nanocoll®), Medi-Radiopharma (Senti-Scint / Tc- MR-4 – 100-600nm, Nano-Scan / Tc-MR-7 – £ 80nm, Nano-Albumon / Tc-MR-3 – 10-100nm)
Brand names of discontinued tracers include:
- Microcis (IBA Molecular, EU MA 1999), Microlite (Pharmalucence).
Products for inhalation:
- GE Healthcare (Venticoll), Medi-Radiopharma (Nano-Vent – 10-80nm).
Patient doses of cold albumin colloids are available at prices ranging from US$ 140 to 180 per mCi.
Competition
In general, there is a lot of competition among manufacturers of human albumin derivatives. Almost all manufacturers of cold kits propose at least one form of an albumin derivative, despite the difficulty in accessing to a reliable source of human blood derivative and the reproducibility of the kit manufacturing process.
Comments
The use of products of human origin such as HSA which have a different source quality from one batch to another have always raised some suspicion about the reproducibility of the labeling. Several times, the source of the HSA was the reason for supply shortage. Also, albumin derivatives are very old products which tend to be substituted by synthetic vectors.
In October 2014, the FDA recognized 99mTc-Tilmanocept as the new Golden Standard for sentinel node detection. This may probably result in the short-term disappearance from the market of all other generic tracers sold for this indication.