In vivo labelling of RBC with 99mTc for blood pool imaging using different stannous radiopharmaceuticals

The in vivo 99mTc-RBC labelling efficiency and stability of labelling was assessed after pretinning with a high-stannous content DTPA kit (Sn DTPA) in comparison with Sn-pyrophosphate (Sn PPi) and a low-stannous DTPA kit (DTPA). The distribution in Sprague Dawley rats showed that similar fractions of administered 99mTc remained within the blood pool after pretinning with Sn DTPA and Sn PPi when equal quantities of stannous ions (15 micrograms/kg) and equal time intervals (30 min) between successive IV injections of pretinning agent and 99mTc-pertechnetate were used. Significantly lower fractions were found when DTPA (1.9 micrograms Sn2+/kg) was used for pretinning. The rate of 99mTc elution emphasises the importance of the Sn2+ concentration used, not only for labelling efficiency but also for stability of the labelling. Satisfactory intravascular activity, exceeding 80% during the first hour post-injection, was demonstrated in three volunteers after 99mTc injection, when Sn DTPA was used for pretinning. Left ventricular ejection fractions (LVEF) measured by equilibrium radionuclide angiography after pretinning with Sn DTPA in 24 patients correlated well (r = 0.98) with those obtained by contrast angiographies over a broad spectrum of values (0.14-0.72). Four repeated LVEF measurements at 45-min intervals in six additional patients at rest showed excellent reproducibility in each patient: maximum variation was less than 6%.     

In vivo/in vitro labeling of red blood cells with 99mTc

Red blood cells (RBC) were labeled with ^99mTc in vitro after in vivo pretreatment with a stannous solution. The whole in vivo/in vitro procedure took 30–40 min. Pretinning was carried out by injection of either 6 mg DTPA and 0.6 mg Sn⁺⁺ (Sn-DTPA) or 5 mg pyrophosphate and 0.7 mg Sn⁺⁺ (Sn-PYP). The results of 1,356 patients were evaluated. The labeling yield was 89.7% (mean) after pretinning with Sn-DTPA and 88.2% following Sn-PYP pretreatment, the median values being 94% and 92%, respectively. The new method was successfully used in over 2,000 patients who had a radionuclide-ventriculography and in 38 patients studied for localization of occult gastrointestinal bleeding. Adverse side effects have never been observed.     

Oxidation states of 99mTc in technetium chelates studied by the ICES method

The chemical shifts of ^99mTc core-electron binding energies were measured in solid samples by means of the internal conversion electron spectroscopy (ICES) method. Technetium chelates with citric acid, DTPA, EDTA and ethylenediamine-N,N′-tetraacetohydroxamic acid (EDTAHA) as ligands were prepared in solution at (2–4) × 10⁻⁷ M Tc concentration (no-carrier-added). The samples for ICES measurements were made by evaporation of the solution in vacuum to dryness. The following chemical shifts ΔE_B [K^99mTcO₄-^99mTc(chelate)] were found in the systems investigated: 1.9 and 4.1 eV for ^99mTc(Sn)citr; 2.1, 3.2 and 4.3 eV for ^99mTc(Sn)DTPA; 1.9 and 3.6 eV for ^99mTc(Sn)EDTA; 1.8 and 3.3 eV for ^99mTc(Sn)EDTAHA. Standard deviations of the shifts are 0.2 eV. These shifts were compared with those of inorganic technetium oxocompounds and correlated with oxidation states via a potential model. It was concluded, that these shifts refer to technetium oxidation states in chelates as follows: 1.8–2.1 eV to ^99mTc(V), 3.2–3.6 eV to ^99mTc(IV) and 4.1–4.3 eV to ^99mTc(III).     

Bromine-82 contamination in fission product 99mTc-generator eluate

Following receipt of fission product ^99mTc-generators, results of radionuclide purity analysis, performed within 30 min after the first elution, demonstrated detectable levels of a contaminate radionuclide not previously reported. Gamma spectroscopy and half-life determinations confirmed the presence of ⁸²Br. Bromine-82 activity, in eluates from the first elution of 30 generators, received weekly during a 7-month period, ranged from 0.22 Ci (8.235 kBq) to 0.67 Ci (24.68 kBq) per eluate. The ratio of ⁹⁹Mo to ^99mTc ranged from 0.13 nCi to 0.39 nCi per mCi ^99mTc. The presence of ⁸²Br in ^99mTc-generator eluate resulted in falsely elevated ⁹⁹Mo assay determinations using whole vial ⁹⁹Mo assay procedures. For every 0.1 Ci ⁸²Br present in ^99mTc eluate the ⁹⁹Mo assay results were elevated by 1 Ci. Gamma spectroscopy of eluates from additional elutions of these generators failed to detect the presence of ⁸²Br demonstrating the displacement of monovalent bromine anions from the alumina column during the first elution.     

Evaluation of white cell scintigraphy using indium-111 and technetium-99m labelled leucocytes

Indium-111 oxine labelled leucocyte (¹¹¹In oxine leucocyte) scintigraphy is the test of choice in detecting occult infection and localising focal inflammation. ¹¹¹In oxine labelling is technically difficult and expensive and leucocyte labelling with technetium-99m stannous colloid (^99mTc Sn colloid) has been considered to be an alternative. Leucocytes from 40 cases referred for investigation of occult infection or localisation of inflammation were simultaneously labelled with ¹¹¹In oxine and ^99mTc Sn colloid with dual isotope acquisition performed at 1, 3 and 24 h. Twenty-four hour ^99mTc Sn colloid scans were corrected for ¹¹¹In downscatter. Each case was independently interpreted by two experienced observers. Twentyone patients demonstrated positive ¹¹¹In oxine leucocyte scans. Using ¹¹¹In oxine leucocyte scans as the gold standard, ^99mTc Sn colloid leucocyte scanning had an overall sensitivity of 86% and a specificity of 95%. Clinical follow-up verified that three patients had false negative ^99mTc Sn colloid leucocyte scans and one patient had a false positive. Further clinical evaluation of ^99mTc Sn colloid labelled leucocytes is required before they can become a reliable replacement for ¹¹¹In oxine leucocytes. Correspondence to: S. Boyd     

Measurement of the secretion of technetium-99m hexamethylpropylene amine oxime into breast milk

There are no published data for the activity of technetium-99m hexamethylpropylene amine oxime (^99mTc-HMPAO) found 1in breast milk. The amount of radioactivity in breast milk following the administration of 500 MBq^99mTc-HMPAO for a brain perfusion study has been measured. The effective dose to the infant was calculated to be 0.26 mSv, so necessitating no interruption of breast feeding. Unbound^99mTc is readily secreted into breast milk and the effective dose will remain less than 1 mSv if the^99mTc-HMPAO labelling effici ency is 99% for the worse reported case, and could remain <1 mSv for the mean reported case for^99mTc-HMPAO labelling efficiencies down to 94%.     

Technetium-99m and indium-111 double labelling of granulocytes for kinetic and clinical studies

A new technique of labelling granulocytes with both technetium-99m hexamethylpropylene amine oxime (HMPAO) and indium-111 in a single protocol was developed in order to exploit the advantages of each radiolabel in clinical and investigative studies. Fourteen patients were included in this prospective study. Granulocytes were labelled with both¹¹¹In-tropolonate and^99mTc-HMPAO. In vitro shape change assay and in vivo distribution and recovery studies were performed to assess the activation of and damage to these cells due to the labelling procedure. The comparative kinetics of¹¹¹In and^99mTc in the blood, liver, spleen, and bone marrow were studied by blood sampling and dual radionuclide imaging early (1 h) and late (24 h) after injection. The functional integrity of the double-labelled granulocytes and the feasibility of the technique were investigated in 14 patients with a painful prosthetic hip due to causes other than infection. The efficiency of double labelling was 63% (SD 14%) for¹¹¹In and 39% (SD 12%) for^99mTc-HMPAO. In vitro granulocyte activation and ex vivo recovery values were comparable to those from single radionuclide labelling. No artefactual granulocyte sequestration was seen in the lungs or liver. The radioactivity was distributed between the liver, spleen and bone marrow and, to a lesser extent, the lung. Early^99mTc counts in the liver, spleen and bone marrow, in relation to background, were significantly higher than¹¹¹In counts while the reverse was seen in late images. Furthermore, circulating free^99mTc was significantly higher than free¹¹¹In at 24 h. Organ^99mTc counts, expressed in relation to the activity in early images, decreased in the spleen, increased in the liver and remained unchanged in bone marrow, whereas¹¹¹In counts increased in the bone marrow and liver, and decreased in the spleen. Granulocytes can be labelled with both¹¹¹In and^99mTc-HMPAO in a single protocol without crosschelation, cellular activation or damage. By favourably exploiting their kinetics for early and late imaging, double-labelled granulocytes may be useful in several clinical and investigative situations.     

Significance of alteration in biodistribution of labeled lymphocytes exposed to stannous ion

The biodistribution patterns of ^99mTc (^99mTc-lymph) and ¹¹¹In-lymphocytes with [¹¹¹In-(Sn)-lymph] or without (¹¹¹In-lymph) stannous ion treatment was compared in Lewis rats. Syngeneic lymphocytes were labeled with either 125 Ci (4.63 MBq) ^99mTc or 5 uCi (1985 kBq) ¹¹¹In per 2×10⁷ cells. Mean labeling efficiency for ^99mTc and ¹¹¹In was 68.61%±3.90% (SEM) and 87.22%±2.01% (SEM) respectively. ^99mTc-lymph (n=4), ¹¹¹In-lymph (n=6) and ¹¹¹In-(Sn)-lymph (n=6) rats received 2x10⁷ cells and were killed 18 h later. While ^99mTc-lymph demonstrated significantly less localization in spleen, lymph nodes, and blood (P(F)0.01) as compared with ¹¹¹In-lymph, ¹¹¹In-(Sn)lymph also demonstrated a significant difference (P[F]=0.0001) in lymph node accumulation when compared to ¹¹¹In-lymph. As the activity levels utilized are not associated with cell radiation damage, these alterations in biodistribution do not reflect viability or chromosomal damage, but appear related to stannous ion exposure.Support from the American Heart Association-Virginia Affiliate     

Oxygen bubbling can improve the labelling of pentavalent technetium-99m dimercaptosuccinic acid

It has previously been reported that almost all of the trivalent technetium-99m dimercaptosuccinic acid (^99mTc (III) DMSA) present in the labelling product of pentavalent technetium-99m DMSA (^99mTc (V) DMSA) can be changed into^99mTc (V) DMSA by bubbling with pure oxygen. We therefore performed studies in animals (mice) and humans to investigate the effect of such oxygen bubbling on the labelling efficiency of and on the renal uptake of^99mTc. The method of labelling of^99mTc (V) DMSA was that of Hirano. It was found that oxygen bubbling oxidized the contaminated^99mTc (III) DMSA into^99mTc (V) DMSA in vitro and decreased the uptake of radioactivity in the kidney in both animals and humans.     

Comparative investigations of renal scanning agents

A comparison was made of the biologic behavior of the following radiopharmaceuticals for use in cases of renal disease: ¹³¹I-Hippuran, ¹⁹⁷Hg-chlormerodrin, ^99mTc-DTPA(Sn), ^99mTc-glucono-galactogluconate-calcium(Sn). Biologic investigations included determining the organ distribution, the blood, liver, kidney, and urine clearances, and the whole body retention of the radiopharmaceuticals after intravenous injection in normal Wistar rats. Clinical investigation of the usefulness of these labeled compounds was performed in 32 patients with different nephrologic and urologic kidney diseases. For better evaluation of the tracers, two were administered simultaneously, in the following combinations: ¹⁹⁷Hg-chlormerodrin and ¹³¹I-Hippuraan, ¹⁹⁷Hg-chlormerodrin and ^99mTc-DTPA(Sn) or ^99mTc-DTPA(Fe), ¹⁹⁷Hg-chlormerodrin and ^99mTc-Fe-ascorbic acid, ¹⁹⁷Hg-chlormerodrin and ^99mTc-gluconate, and ^99mTc-gluconate and ^99mTc-Fe-ascorbic acid. The results show that the chelates DTPA(Sn) and DTPA(Fe) labeled with ^99mTc are very useful in static and dynamic investigations of kidney function and morphology, and that ^99mTc-Fe-ascorbic acid and ^99mTc-gluconate are very useful for the study of kidney morphology. The superiority of these preparations over ¹³¹I-Hippuran and ¹⁹⁷Hg-chlormerodrin was evident above all in cases of renal failure and radiologically silent kidney.     

Further investigations of morpholino pretargeting in mice—establishing quantitative relations in tumor

Purpose This laboratory has previously published on phosphorodiamidate morpholino (MORF) pretargeting of tumor in which an anti-tumor antibody conjugated with MORF (a DNA analogue) is first administered, followed at a later time by the radiolabeled complementary MORF (cMORF) as the effector. In the present study, the pharmacokinetics of the antibody and effector were measured under different conditions in mice to establish their quantitative relationships with tumor accumulations by pretargeting.Methods A cytosine-free 18 mer cMORF was conjugated with MAG₃ for ^99mTc labeling while the anti-CEA antibody MN14 was conjugated with DTPA for ¹¹¹In labeling and with MORF to impart binding affinity for radiolabeled cMORF. Mice bearing LS174T thigh tumors were used to study: (1) the pharmacokinetics of MN14-MORF by administering ¹¹¹In-MN14 at doses between 10 and 100 g with sacrifice at 2 days and at 30 g with sacrifice between 1 and 3 days; (2) the biodistribution of ^99mTc-cMORF following one to four injections (containing 0.15 g each and separated by 1 h) to animals having received 30 g of antibody–MORF 2 days earlier and with sacrifice at 3 h after the final injection; and (3) the influence on the biodistribution of ^99mTc-cMORF of a 2 to 4 day interval between the administration of 30 g of antibody–MORF and 0.30 g of ^99mTc-cMORF.Results (1) The biodistribution of antibody in percent accumulation (%ID or %ID/g) was largely independent of antibody dose but the absolute accumulation of antibody in tumor increased linearly with dose, showing no evidence of tumor saturation of CEA sites by MN14. Over 1–3 days post antibody administration, blood levels of radiolabeled antibody decreased as expected; however, tumor levels remained constant, thus showing an absence of antibody clearance in tumor over this period. (2) With fixed antibody–MORF dose and increasing number of injections of ^99mTc-cMORF, cumulative percent blood levels steadily decreased in agreement with the values calculated based on the antibody–MORF in blood. In contrast, cumulative percent tumor levels stayed fairly constant over the first two injections. Thus the antibody–MORF in tumor became saturated with cMORF more slowly than that in blood owing to delivery differences. (3) As expected, percent blood levels decreased with increasing interval between injections of antibody–MORF and ^99mTc-cMORF. The percent tumor accumulation, however, remained constant over the 3 day interval, thus demonstrating only slow loss of MORF expression in situ. The ^99mTc-cMORF accumulation in tumor after saturation was mathematically determined based on the antibody–MORF concentration in tumor while the blood levels of ^99mTc-cMORF were determined based on the concentration of antibody-MORF in blood.Conclusion Contrary to conclusions arrived at in our earlier study, the results of this study show that tumor CEA sites were not saturated even at the highest antibody dose investigated, that accessibility of MORF sites in tumor by ^99mTc-cMORF was unhindered and that the maximum percent tumor accumulation of ^99mTc-cMORF depended only on the tumor delivery efficiency of ^99mTc-cMORF.     

Cyclotron production of (99m)Tc: experimental measurement of the (100)Mo(p,x)(99)Mo, (99m)Tc and (99g)Tc excitation functions from 8 to 18 MeV

Introduction

The cyclotron-based ¹⁰⁰Mo(p,2n)^99mTc transformation has been proposed as a viable alternative to the reactor based ²³⁵U(n,f)⁹⁹Mo→^99mTc strategy for production of ^99mTc. Despite efforts to theoretically model the amount of ground-state ^99gTc present at end of bombardment for the (p,2n) reaction, experimental validation has yet to be performed. The co-production of ^99gTc may have important implications in both the subsequent radiopharmaceutical chemistry and patient dosimetry upon injection.

Methods

To determine the extent of ^99gTc co-production, we have experimentally measured the ¹⁰⁰Mo(p,x)⁹⁹Mo, ^99mTc, and ^99gTc excitation functions in the 8–18 MeV range using a combination of natural abundance and 97.42% enriched ¹⁰⁰Mo foils along with γ-ray spectrometry and ICP-MS. Although the excitation functions for production of ⁹⁹Mo and ^99mTc have been presented previously in the literature, to the best of our knowledge, this work presents the first experimental evaluation of the ¹⁰⁰Mo(p,2n)^99gTc excitation function.

Results

From the experimental cross-section measurements, the ^99mTc production yields and ^99mTc/^99m+gTc nuclei ratio were calculated for various thick target irradiation conditions. Results suggest that TBq quantities of ^99mTc can be achieved with a ^99mTc/^99m+gTc nuclei ratio that is on par with the current ⁹⁹Mo/^99mTc generator standard eluted at a 24-h frequency.

Conclusion

These findings suggest that the cyclotron production of ^99mTc may be a feasible alternative to the current reactor-based production strategy.     

Development of 68Ga-labelled DTPA galactosyl human serum albumin for liver function imaging

Purpose

The hepatic asialoglycoprotein receptor is responsible for degradation of desialylated glycoproteins through receptor-mediated endocytosis. It has been shown that imaging of the receptor density using [^99mTc]diethylenetriamine pentaacetic acid (DTPA) galactosyl human serum albumin ([^99mTc]GSA) allows non-invasive determination of functional hepatocellular mass. Here we present the synthesis and evaluation of [⁶⁸Ga]GSA for the potential use with positron emission tomography (PET).

Methods

Labelling of GSA with ⁶⁸Ga was carried out using a fractionated elution protocol. For quality control thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC) and size exclusion chromatography (SEC) techniques were evaluated. Stability of [⁶⁸Ga]GSA was studied in phosphate-buffered saline (PBS) and human serum. For in vivo evaluation [⁶⁸Ga]GSA distribution in Lewis rats was compared with [^99mTc]GSA by using a dual isotope protocol. PET and planar imaging studies were performed using the same scaled molar dose of [⁶⁸Ga]GSA and [^99mTc]GSA. Time-activity curves (TAC) for heart and liver were generated and corresponding parameters calculated (t50, t90).

Results

[⁶⁸Ga]GSA can be produced with high radiochemical purity. The best TLC methods for determining potential free ⁶⁸Ga include 0.1 M sodium citrate as eluent. None of the TLC methods tested were able to determine potential colloids. This can be achieved by SEC. HPLC confirmed high radiochemical purity (>98 %). Stability after 120 min incubation at 37 °C was high in PBS (>95 % intact tracer) and low in human serum (～27 % intact tracer). Biodistribution studies simultaneously injecting both tracers showed comparable liver uptake, whereas activity concentration in blood was higher for [⁶⁸Ga]GSA compared to [^99mTc]GSA. The [^99mTc]GSA TACs exhibited a small degree of hepatic metabolism compared to the [⁶⁸Ga]GSA curves. The mean [⁶⁸Ga]GSA t90 was higher than the mean t90 for [^99mTc]GSA. The mean [⁶⁸Ga]GSA t50 was not significantly different from the mean t50 for [^99mTc]GSA.

Conclusion

This study provides a promising new ⁶⁸Ga-labelled compound based on a commercially used kit for imaging the functional hepatocellular mass.     

Iodine-125 labeled phenylphosphonic acid: A new radiopharmaceutical for long-term investigations of the skeleton

A skeletal seeking radiopharmaceutical labeled with a long-lived radionuclide was developed to evaluate regional bone formation and its subsequent resorption. The agent is [phosphonate (phenylmethylene hydroxy) bis]-I-125 or I-125 PA. Tissue distribution studies in mice (N=16) showed approximately 40% of the administered dose to be retained by the skeleton up to 336 hours post IV injection. The percentage of the dose accumulated by the thyroid gland remained at less than 0.5%, indicating minimal deiodination of the I-125 PA. Whole body retention studies in the same species revealed a triexponential release pattern with the longest component comprising 33% of the dose with a biologic half-life of 962 days. A fractured rat tibia model was studied with I-125 PA and Tc-99^m MDP. Chronic loss of the I-125 PA relative to normal tibia was quantitated: five days (62.8%); 30 days (47.4%). Concomitant increased uptake of the Tc-99^m MDP was observed at the fracture site relative to normal: five days (186%); 30 days (1,041%). The above data suggest that I-125 PA can be utilized to measure acute bone formation and chronic resorption.     

HPLC separated fractions of 99mTc(NaBH4)-HEDP as myocardial infarct imaging agents

Component fractions of ^99mTc(NaBH₄)-HEDP mixtures, isolated by anion exchange high performance liquid chromatography (HPLC), have been evaluated as myocardial infarct imaging agents in two animal models. Results from both the isoproterenol-induced myocardial infarction model, and the heat-induced myocardial necrosis model, show that the several HPLC isolated components exhibit significantly different abnormal/normal heart uptake ratios. In addition, the HPLC isolated component of shortest chromatographic retention time exhibits a higher abnormal/normal heart uptake ratio than does ^99mTc(Sn)-PyP, the current agent of choice for clinical myocardial infarct imaging.     

Is a Technetium-99m Macroaggregated Albumin Scan Essential in the Workup for Selective Internal Radiation Therapy with Yttrium-90? An Analysis of 532 Patients

Purpose

To determine if baseline patient, tumor, and pretreatment evaluation characteristics could help identify patients who require technetium-99m (^99mTc) macroaggregated albumin (^99mTc MAA) imaging before selective internal radiation therapy (SIRT).

Left ventricular dysfunction in coronary artery disease: Comparison between rest-redistribution thallium 201 and resting technetium 99m methoxyisobutyl isonitrile cardiac imaging

Background

We compared rest-redistribution thallium 201 and resting technetium 99m methoxyisobutyl isonitrile (MIBI) cardiac imaging in 29 men with angiographically proven coronary artery disease and regional ventricular dysfunction. Left ventricular ejection fraction at radionuclide angiography was 35%±9%.

Methods and Results

Regional left ventricular wall motion was assessed on gated^99mTc MIBI images according to a 3-point scale (0=normal, 1=hypokinetic, 2=akinetic or dyskinetic).²⁰¹Tl and^99mTc MIBI uptake values were analyzed quantitatively. A total of 435 myocardial segments were classified on the basis of wall motion analysis into three groups: group 1 (normal wall motion;n=201), group 2 (hypokinetic;n=132), and group 3 (akinetic or dyskinetic;n=102).²⁰¹Tl and^99mTc MIBI uptake values were significantly higher in groups 1 and 2 compared with group 3 (p<0.05) and in group 1 compared with group 2 (p<0.05). When²⁰¹Tl and^99mTc MIBI uptake values were directly compared, no significant differences in groups 1 and 2 were observed. In group 3,^99mTc MIBI uptake (67%±14%) was significantly lower (p<0.001) than initial (72%±11%) and delayed²⁰¹Tl uptake (73%±12%).

Conclusion

Thus rest-redistribution²⁰¹Tl and resting^99mTc MIBI cardiac imaging reflect the severity of left ventricular dysfunction in coronary artery disease. However, in segments with severely impaired regional ventricular function,²⁰¹Tl uptake is significantly higher than^99mTc MIBI uptake.     

99mTc/188Re-labelled lipid nanocapsules as promising radiotracers for imaging and therapy: formulation and biodistribution

Purpose This study focusses on a promising carrier system for imaging and therapeutic purposes using lipid nanocapsules. To assess their potential for clinical use, we labelled nanocapsules with ^99mTc and ¹⁸⁸Re and analysed some kinetic biodistribution parameters after intravenous injection in rats. Methods Lipophilic complexes [^99mTc/¹⁸⁸Re(S₃CPh)₂(S₂CPh)] (^99mTc/¹⁸⁸Re-SSS) were encapsulated within the nanoparticles during their manufacture with quantitative yield and satisfactory radiochemical purity. Rats were injected intravenously with 3.7 MBq ^99mTc/¹⁸⁸Re-labelled nanocapsules and sacrificed at 5, 15 and 30 min and 1, 2, 4, 8, 12, 16, 20 and 24 h. Results Dynamic scintigraphic acquisitions showed predominant hepatic uptake, and ex vivo counting indicated a long circulation time of labelled nanocapsules, with a half-life of 21±1 min for ^99mTc and 22±2 min for ¹⁸⁸Re. Very weak urinary elimination was observed, indicating good stability of ^99mTc and ¹⁸⁸Re labelling. Conclusion ^99mTc/¹⁸⁸Re-SSS nanocapsules can be obtained with high yield and satisfactory radiochemical purity. The biodistributions of ^99mTc/¹⁸⁸Re-labelled nanocapsules are close to those of classical PEG-coated particles and show good stability of ¹⁸⁸Re/^99mTc-SSS labelling.     

Rapid measurement of blood leakage during regional chemotherapy

In order to avoid complications after regional chemotherapy (isolated hyperthermic perfusion) of the extremities, rapid measurement of blood leakage from the extracorporeal to the systemic circulation is important. A method using technetium-99m in vivo red blood cell (RBC) labelling is reported that provides results within 3 min. Blood samples drawn from the systemic and the extracorporeal circulation were measured for ^99mTc activity using a mobile well counter, and the leakage values calculated. The mean result was 7.6%±6.5%/15 min (n=209). The corresponding flow rate was 100.2±85.7 ml/15 min (mean ± SD). The values for isolation perfusion of the upper and the lower extremities are compared. The leakage results using ^99mTc RBC labelling were correlated with other blood pool markers. Iodine-125 human serum albumin and indium-113 m transferrin were administered in subgroups of 4 and 19 patients simultaneously. Using linear regression, the coefficient of correlation was 0.72 for ^99mTc/^113mIn and 0.58 for ^99mTc/¹²⁵I. Comparison with the alternatives suggests that the rapid method of leakage measurement after ^99mTc RBC labelling can be considered one of the most practicable and reliable methods available.This paper is dedicated to Prof. E. Oberhausen, Homburg/Saar, on the occasion of his 65th birthday Correspondence to: C. Alexander     

Tc Nanocoll: A radiopharmaceutical for sentinel node localisation in breast cancer—In vitro and in vivo results

This study evaluated labelling efficiency and radiochemical purity of ^99mTc 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 ^99mTc colloid albumin. Ex vivo, significantly higher count rates were reached using a 2 h eluate in vacuum or nitrogen. Labelling 26 MBq/μg ^99mTc colloid albumin with a 2 h eluate under nitrogen is recommended because of the ease of labelling.