ABSTRACT
This study evaluated labelling efficiency and radiochemical purity of (99m)Tc colloid albumin to identify an optimal labelling protocol for sentinel node detection. Results indicate that a 72 h eluate is not recommended for high specific labelling of (99m)Tc colloid albumin. Ex vivo, significantly higher count rates were reached using a 2h eluate in vacuum or nitrogen. Labelling 26 MBq/microg (99m)Tc colloid albumin with a 2 h eluate under nitrogen is recommended because of the ease of labelling.
Subject(s)
Breast Neoplasms/diagnostic imaging , Lymph Nodes/diagnostic imaging , Radiopharmaceuticals , Technetium Tc 99m Aggregated Albumin , Adult , Aged , Aged, 80 and over , Albumins , Female , Humans , Lymphatic Metastasis , Middle Aged , Nitrogen/chemistry , Radionuclide Imaging , Sentinel Lymph Node Biopsy , Young AdultABSTRACT
The aim of this study was to evaluate the count rates of sentinel lymph nodes (SLNs) in patients with breast cancer in the operating theatre, using (99m)Tc-Nanocoll with different ratios of technetium-99m to technetium-99. After written informed consent had been obtained, we tested different ratios of (99m)Tc/(99)Tc-Nanocoll in a double-blinded randomised study performed in 161 patients. Twenty-five MBq/ microg (99m)Tc-colloid albumin was prepared in vacuum. In 87 patients (group A) a 2-h elution was used and in 74 patients (group B) a 24-h elution was used. Patients were subcategorised into subgroups 1 and 3, in which an SLN procedure for breast carcinoma was performed simultaneously with lumpectomy, and subgroups 2 and 4, in which an SLN procedure was performed 2-3 weeks after prior excision biopsy. All patients were injected along the lateral border of the areola (two injections: 50 MBq/0.3 ml intradermally and 50 MBq/2 ml intraparenchymally). Ex vivo measurement of count rates was performed with a gamma probe. Comparing groups A and B in respect of registered counts per second (cps) of excised SLNs, a significant difference was found ( P<0.004). When comparisons were made between subgroups 1 and 2 (2-h elution) and between subgroups 3 and 4 (24-h elution) in respect of registered cps of excised SLNs, no significant difference was found (subgroup 1 vs 2, P=0.825; subgroup 3 vs 4, P=0.915). Use of a 2-h elution in vacuum yielded a significantly higher count rate of maximum specific activity of (99m)Tc-colloid albumin in SLNs than was achieved using a 24-h elution in vacuum. SLN procedures performed 2-3 weeks after prior excision biopsy proved reliable as compared to SLN procedures performed simultaneously with lumpectomy.
Subject(s)
Breast Neoplasms/diagnostic imaging , Diagnostic Errors , Image Enhancement/methods , Injections/methods , Lymph Nodes/diagnostic imaging , Sentinel Lymph Node Biopsy/methods , Technetium Tc 99m Aggregated Albumin/administration & dosage , Adult , Aged , Aged, 80 and over , Dose-Response Relationship, Drug , Double-Blind Method , Female , Humans , Lymphatic Metastasis , Middle Aged , Radiometry/methods , Radionuclide Imaging , Radiopharmaceuticals/administration & dosage , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
The sentinel node (SLN) procedure has gained widespread acceptance for the axillary staging of patients who present with carcinoma of the breast. A first series of 21 patients were imaged 2 and 4 h after the injection of technetium-99m colloidal albumin. Preoperatively, axillary foci were located scintigraphically and with a hand-held gamma probe that was also used to detect the radiolabelled nodes 22 h later in the operating theatre. In a high percentage of our first series it was difficult to localise the sentinel node owing to a low count rate ex vivo. The aim of this study was to facilitate the detection of sentinel nodes by improving the count rate by the use of higher specific concentrations of 99mTc-colloidal albumin, with increased radiochemical labelling efficiency and stability. In vitro tests were performed to establish the radiochemical labelling efficiency and stability of different concentrations of 99-mTc-colloidal albumin. Concentrations of 2.5, 10, 20, 25, 30, 37 and 50 MBq 99mTc/microg colloidal albumin (Nanocoll) were prepared under nitrogen and in vacuum. The quality of the solutions was assessed by testing the radiochemical labelling efficiency and stability after 0.5, 2, 5, 8 and 24 h. The particle size of colloidal albumin was tested by dynamic light scattering at 30.2 degrees, 62.6 degrees and 90.0 degrees angles. Following the results of the in vitro studies, higher concentrations of 99mTc-colloidal albumin were used in vivo in a further series of 98 patients. For labelling under nitrogen, a maximum acceptable concentration of 10 MBq/microg was found, which complies with the specifications of the manufacturer. By preparing the labelling in vacuum vials, a 2.5 times greater radiochemical labelling efficiency over the entire period was achieved, and a significant improvement (P<0.002) in the in vivo series was found. It is concluded that although the rate of successful visualisation of the SLN was high in all studies, a better count rate (nine times higher) was achieved with the highest concentration of 99mTc-colloidal albumin, which facilitated the detection of the SLN by the gamma probe during surgery.
