Position paper on requirements for toxicological studies in the specific case of radiopharmaceuticals.

This is a position paper of the Radiopharmacy Committee of the EANM (European Association of Nuclear Medicine) addressing toxicology studies for application of new diagnostic and therapeutic radiopharmaceuticals (RP) that are not approved (i.e., not having a marketing authorization or a monograph in the European Pharmacopoeia), excluding endogenous and ubiquitous substances in humans. This paper discusses the requirements for clinical trials with radiopharmaceuticals for clinical research applications, not necessarily intended to aim at a marketing authorization. If marketing authorization is intended, scientific advice of the competent authorities is mandatory and cannot be replaced by this position paper. The position paper reflects the view of the Radiopharmacy Committee of the EANM and can be used as a basis for discussions with the responsible authorities.

Global abnormalities in lymphatic function following systemic therapy in patients with breast cancer.

BACKGROUND: Breast cancer-related lymphoedema (BCRL) is a result of interaction between several pathophysiological processes, and is not simply a 'stopcock' effect resulting from removal of axillary lymph nodes. The aim of this study was to test the hypothesis that there is a constitutional 'global' lymphatic dysfunction in patients who develop BCRL. METHODS: Lower-limb lymphoscintigraphy was performed in 30 women who had undergone axillary lymph node dissection at least 3 years previously, of whom 15 had BCRL and 15 did not. No patient had any clinical abnormality of the lower limb. The control group comprised 24 women with no history of cancer or lower-limb lymphoedema. (99m) Tc-Nanocoll was injected subcutaneously into the first webspace of each foot, followed by whole-body imaging. Scans were reported as abnormal if there was delay in lymph transport or rerouting through skin or deep system. Quantification was expressed as the percentage injected activity accumulating in ilioinguinal nodes. RESULTS: Mean(s.d.) ilioinguinal nodal accumulation at 150 min was significantly lower in women with BCRL than in those without (2·7(2·5) versus 5·9(4·8) per cent respectively; P = 0·006). Abnormal findings on lower-limb lymphoscintigraphy were observed in 17 of the 30 patients: ten of the 15 women who had BCRL and seven of the 15 who did not. None of the 24 control subjects had abnormal scan findings. CONCLUSION: Women with BCRL had reduced lower-limb lymph drainage, supporting the hypothesis of a predisposition to BCRL. A surprisingly high proportion of patients with breast cancer also demonstrated lymphatic dysfunction, despite clinically normal lower limbs. Possible explanations could be a systemic effect of breast cancer or its treatment, or an unidentified association between breast cancer and lymphatic dysfunction. REGISTRATION NUMBER: ISRCTN84866416 ( http://www.isrctn.com).

An investigation of lymphovenous communications in the upper limbs of breast cancer patients.

BACKGROUND: Approximately 25% of breast cancer patients who undergo treatment to the axilla develop breast cancer-related lymphoedema (BCRL). The aim of this study was to test the hypothesis that lymphovenous communications (LVCs) open and act as a protective mechanism against the development of BCRL. METHODS: Five patients (Group 1) received intradermal injections of (99m)Technetium-labelled autologous erythrocytes into the 2nd ipsilateral hand webspace before and 6-12 weeks following axillary node clearance surgery (ANC). Ten patients at least three years after ANC were also recruited (Group 2); seven had developed BCRL and three had not. Blood was sampled from ipsilateral and contralateral antecubital veins 5, 15, 30, 60, 120 and 180 min post-injection to assess pre-nodal shunting from lymph to blood (LVCs), since nodes block erythrocyte transit. The proportion of activity remaining in the depot was used to calculate the degree of shunting in those with evidence of LVCs. RESULTS: Significant erythrocyte-bound activity, increasing over time, was detected contralaterally in 3 of the 5 patients from Group 1 (none of whom developed BCRL) and 3 of 7 patients with BCRL from Group 2, which indicated the presence of LVCs. The degree of shunting was more marked in those patients who did not develop BCRL compared with those who did. CONCLUSIONS: The time-course of erythrocyte-bound contralateral activity indicates transit through lymphovenous communications rather than needle-induced trauma. Lymphovenous communications large enough to transmit erythrocytes are probably constitutional rather than induced. A larger study is warranted to assess any resulting protection against BCRL.

A constitutional predisposition to breast cancer-related lymphoedema and effect of axillary lymph node surgery on forearm muscle lymph flow.

AIM: The aims of this prospective study were (a) to examine the relationship between pre-operative muscle lymph flow and the predisposition to BCRL in women treated by axillary nodal surgery for breast cancer; and (b) to test the 'stopcock' hypothesis that axillary lymph node surgery impairs forearm lymph flow in the short term. METHODS: (99m)Tc-nanocoll was injected intramuscularly into both forearms of women undergoing surgery for breast cancer. Lymphatic clearance rate constant, k, representing lymph flow per unit interstitial fluid volume, was measured as the fractional disappearance rate of radioactivity from the depot site by gamma camera imaging. Axillary lymph node activity was calculated as percentage injected activity. BCRL was assessed by clinical examination and upper limb perometry. RESULTS: Of 38 pre-operative women, 33 attended at 8 ± 6 weeks post-operatively and 31 at 58 ± 9 weeks post-operatively. Seven patients (18%) developed BCRL. Prior to surgery the BCRL-destined patients had a higher mean k (0.0962 ± 0.034%/min) than non-BCRL patients (0.0830 ± 0.019%/min) (p = 0.10, unpaired t test). Post-operative k values were not significantly different from pre-operative, in either the ipsilateral (operated) or contralateral limb. Also, post-operative k values did not differ significantly between both upper limbs. Furthermore, there was no significant difference between pre- and post-operative axillary activity. CONCLUSION: Patients who develop BCRL have high lymph flow pre-surgery, which may predispose them to lymphatic overload and failure. Axillary lymph node surgery has no early, measurable effect on forearm muscle lymph flow despite surgical disruption of routes of lymph drainage.

Short- and long-term responses to molybdenum-99 shortages in nuclear medicine.

Most nuclear medicine studies use (99)Tc(m), which is the decay product of (99)Mo. The world supply of (99)Mo comes from only five nuclear research reactors and availability has been much reduced in recent times owing to problems at the largest reactors. In the short-term there are limited actions that can be taken owing to capacity issues on alternative imaging modalities. In the long-term, stability of (99)Mo supply will rely on a combination of replacing conventional reactors and developing new technologies.

Joint practice guidelines for radionuclide lymphoscintigraphy for sentinel node localization in oral/oropharyngeal squamous cell carcinoma.

Involvement of the cervical lymph nodes is the most important prognostic factor for patients with oral/oropharyngeal squamous cell carcinoma (OSCC), and the decision of whether to electively treat patients with clinically negative necks remains a controversial topic. Sentinel node biopsy (SNB) provides a minimally invasive method for determining the disease status of the cervical node basin, without the need for a formal neck dissection. This technique potentially improves the accuracy of histologic nodal staging and avoids overtreating three-quarters of this patient population, minimizing associated morbidity. The technique has been validated for patients with OSCC, and larger-scale studies are in progress to determine its exact role in the management of this patient population. This document is designed to outline the current best practice guidelines for the provision of SNB in patients with early-stage OSCC, and to provide a framework for the currently evolving recommendations for its use. Preparation of this guideline was carried out by a multidisciplinary surgical/nuclear medicine/pathology expert panel under the joint auspices of the European Association of Nuclear Medicine (EANM) Oncology Committee and the Sentinel European Node Trial (SENT) Committee.

A pilot study of dual-isotope lymphoscintigraphy for breast sentinel node biopsy comparing intradermal and intraparenchymal injection.

AIMS: Identification of sentinel lymph nodes (SLN) may depend on the tissue plane of tracer injection. To explore this, we developed a dual-isotope technique to compare the lymphatic drainage basins accessed by intradermal and parenchymal injections. METHODS: Fifteen breast cancer patients had simultaneous parenchymal and intradermal injections of (99m)Tc-labelled human immunoglobulin G (HIG) and (111)In-HIG, respectively, 2-4h before axillary lymph node clearance surgery. All 228 freshly dissected nodes were assayed by well counting and examined for metastatic disease by haematoxylin/eosin staining and immuno-histochemistry. RESULTS: Total nodal uptake following intradermal injection was 10 times more than after parenchymal injection. Tracer uptake within the first three draining nodes divided patients into three groups; four (group 1) had identical 1st, 2nd and 3rd echelon nodes, six (group 2) had identical 1st and 2nd echelon nodes and five (group 3) had different 1st echelon nodes. With respect to the first, second and third groups, there was close, moderate and poor correlation (Pearson), respectively, between individual nodal counts accumulated from the two injection sites. Of eight patients with nodal disease, the SLN identified by intradermal and parenchymal injections contained disease in seven and four patients, respectively. CONCLUSIONS: Comparison of nodal tracer distributions from the two injection planes allows a functional model to be developed with two possible routes of drainage from the parenchymal plane, one joining the tract from the areolar plexus and the other passing independently to the axilla which builds upon Sappey's original anatomical model. This may explain the variable uptake, discordance and false negative SLN identification.

EANM/ESC guidelines for radionuclide imaging of cardiac function.

Radionuclide imaging of cardiac function represents a number of well-validated techniques for accurate determination of right (RV) and left ventricular (LV) ejection fraction (EF) and LV volumes. These first European guidelines give recommendations for how and when to use first-pass and equilibrium radionuclide ventriculography, gated myocardial perfusion scintigraphy, gated PET, and studies with non-imaging devices for the evaluation of cardiac function. The items covered are presented in 11 sections: clinical indications, radiopharmaceuticals and dosimetry, study acquisition, RV EF, LV EF, LV volumes, LV regional function, LV diastolic function, reports and image display and reference values from the literature of RVEF, LVEF and LV volumes. If specific recommendations given cannot be based on evidence from original, scientific studies, referral is given to "prevailing or general consensus". The guidelines are designed to assist in the practice of referral to, performance, interpretation and reporting of nuclear cardiology studies for the evaluation of cardiac performance.

The clearance kinetics of autologous RhD-positive erythrocytes coated ex vivo with novel recombinant and monoclonal anti-D antibodies.

Anti-D is given routinely to pregnant RhD-negative women to prevent haemolytic disease of the fetus and newborn. To overcome the potential drawbacks associated with plasma-derived products, monoclonal and recombinant forms of anti-D have been developed. The ability of two such antibodies, BRAD-3/5 monoclonal anti-D IgG (MAD) and rBRAD-3/5 recombinant anti-D IgG (RAD), to clear RhD-positive erythrocytes from the circulation was compared using a dual radiolabelling technique. Six RhD-positive males received autologous erythrocytes radiolabelled with (99m)Tc and (51)Cr and coated ex vivo with MAD and RAD. Blood samples were collected up to 1 h following intravenous injection, and percentage dose of radioactivity in the samples determined. Three different levels of coating were used on three separate occasions. No significant differences between MAD and RAD were observed in the initial clearance rate constant at any dose level. The log[activity]-time clearance plots were curved, showing a reduction in the clearance rate constant with time. This reduction was more marked for RAD than for MAD. The results support a dynamic model for the clearance of antibody-coated erythrocytes that may have wider relevance for the therapeutic use of antibodies.

Lymphatic transfer studies with immunoglobulin scintigraphy after axillary surgery.

AIMS: The study objective was to investigate the effects of axillary lymph node clearance surgery on the function and morphology of the lymphatic system of the upper limb in women with breast cancer. METHODS: Nineteen women were studied before and 3 months after surgery. Fifteen were studied again 12 months after surgery. On each occasion, scintigraphy following intradermal hand webspace injection of Tc-99m-human polyclonal immunoglobulin was performed to include the affected upper limb and torso. RESULTS: There was considerable functional variability in response to surgery. Seven patients subsequently developed breast cancer-related lymphedema (BCRL). Neither lymph re-routing (defined as a change in lymph vessel morphology or definition) nor linear velocity of protein transit up the arm was associated with the development of BCRL. Blood pool activity, judged from visual inspection of the cardiac blood pool on the whole body images, was earlier and more marked 3 and 12 months after surgery than before. The count rate (per 100 pixels/MBq injected activity), measured in a cardiac region of interest, was significantly higher after surgery than before, was higher in patients who developed BCRL and, in the patient population as a whole, correlated positively with arm swelling. CONCLUSION: The consequences of axillary lymph node clearance were variable, unexpected and largely persistent. An increased rate of access of intradermally injected protein into the blood pool is significantly associated with BCRL.

Adverse events and treatment interruption in tuberculosis patients with and without HIV co-infection.

BACKGROUND: Serious treatment associated adverse events are thought to occur more frequently in individuals with tuberculosis (TB) who are co-infected with HIV. A study was undertaken to assess the frequency of serious (grade III/IV) adverse events and interruption of anti-TB treatment in the era of effective antiretroviral therapy. METHODS: The incidence of serious adverse events was retrospectively compared in 312 individuals treated for TB, 156 of whom were co-infected with HIV. RESULTS: 111 HIV infected individuals (71%) received highly active antiretroviral therapy at the same time as anti-TB treatment. Serious adverse events were recorded in 40% HIV infected and 26% HIV uninfected individuals (p = 0.008). Peripheral neuropathy and persistent vomiting were more common in co-infected patients (p<0.001; p = 0.006), although all cause interruption of anti-TB treatment occurred with similar frequency in the two groups (13% in HIV infected patients and 15% in HIV uninfected patients; p = 0.74). In 85% of HIV infected patients and 87% of HIV uninfected individuals this was due to hepatotoxicity, which typically presented within 2 months of starting treatment. The median delay in restarting treatment was 4 weeks, so most individuals required full TB re-treatment. CONCLUSION: Despite a greater rate of serious (grade III/IV) adverse events among HIV infected individuals, discontinuation of anti-TB treatment occurred with a similar frequency in HIV infected and HIV uninfected individuals.

Virological response to highly active antiretroviral therapy is unaffected by antituberculosis therapy.

We compared 156 human immunodeficiency virus (HIV)-infected patients who had tuberculosis with control populations of similar size. Of 111 patients with HIV infection and tuberculosis who received highly active antiretroviral therapy (HAART) and therapy for tuberculosis concurrently, 92 (83%) achieved or maintained virus loads of <50 copies/mL, and 99 (89%) achieved or maintained a >or=2 log10 reduction in virus load after 6 months. Virological response and changes in CD4 cell count were equivalent to those in 111 matched HIV-infected subjects without tuberculosis starting HAART. Tuberculosis recurrence rates were similar to those found in an HIV-uninfected population of 156 subjects (3% and 1%, respectively). Treatment for HIV and tuberculosis does not compromise outcomes for either disease.

Radiolabelled leukocytes for imaging inflammation: how radiochemistry affects clinical use.

Indium-111((111)In)-labelled leukocytes were introduced for imaging inflammation about 25 years ago. A few years later methods to label leukocytes with Technetium-99m ((99m)Tc) were developed, but the two radiolabels cannot be used interchangeably. The amount of radioactivity which can be administered with (111)In is low, because of its 67-h half-life and associated radiation dose. This results in low count density in images. However, (111)In labelling is very stable, with binding to intracellular macromolecules and particulates, and there is minimal urinary or faecal excretion. In contrast, (99m)Tc has a half-life of 6 h and can be administered in higher doses, resulting in improved image quality. However, (99m)Tc labelling is less stable because the trapped form is soluble and there is excretion of (99m)Tc through both the kidneys and intestine, which limits imaging of disease in the abdomen except at early times. There is interest in extending inflammation imaging to PET. Although leukocytes can be labelled with (18)F-FDG, its half-life and stability are not optimal and radiometals such as Copper-64 are being evaluated. Despite the laborious nature of leukocyte labelling, it has yet to be replaced by direct injection agents.

Variation in lymphatic function may predispose to development of breast cancer-related lymphoedema.

AIMS: Breast cancer-related lymphoedema (BCRL) remains a common complication of breast cancer treatment. Many features of this condition remain poorly understood, such as why only approximately 25% of women are affected after similar treatment, and the phenomenon of 'sparing', in which regions of an otherwise swollen arm, most commonly the hand, remain unaffected. This study uses dual-isotope lymphoscintigraphy, involving measurement of rate of clearance of radiolabelled protein from a subcutaneous depot and subsequent appearance in blood, to quantify alterations in lymphatic function in women with BCRL, and to further investigate differences between those in whom the hand is involved with swelling and those in whom it is spared. METHODS: Participants received a depot injection of human immunoglobulin G in the dorsum of both hands, labeled with technetium-99m on one side and indium-111 on the other. Rates of clearance from the depot and appearance in venous blood were measured at regular intervals over a 3 h period. RESULTS: A total of 18 women with a history of BCRL were studied. Significant reductions in both depot clearance and venous appearance were observed in the affected arm compared with the unaffected contralateral control. On sub-group analysis, significant differences were also observed between swollen and spared hand groups, both for the affected and unaffected contralateral arm. DISCUSSION: This study, as well as confirming impaired lymphatic function in arms affected by BCRL, also shows underlying variation in lymphatic function in the unaffected contralateral arm, between those with and without hand sparing. This raises the possibility that the risk of developing BCRL may be, in part, pre-determined.

Cerebral neutrophil recruitment, histology, and outcome in acute ischemic stroke: an imaging-based study.

BACKGROUND AND PURPOSE: Evidence now exists for a pathogenic role for neutrophils in acute cerebral ischemia. We have studied the patterns and temporal profile of cerebral neutrophil recruitment to areas of acute ischemic stroke (IS) and have attempted to correlate this with neurological status and outcome. METHODS: Patients with cortical middle cerebral artery (MCA) IS were recruited within 24 hours of clinical onset. Neutrophil recruitment was studied using indium-111 (111In) troponolate-labeled neutrophils, planar imaging, and single-photon emission computed tomography (SPECT). Volume of brain infarction was calculated from concurrent computed tomography (CT). Hematoxylin and eosin sections were obtained postmortem (n=2). Outcome was measured using Barthel, Rankin, and National Institute of Health Stroke (NIHSS) scales. RESULTS: Fifteen patients were studied. Significant 111In-neutrophil recruitment to ipsilateral hemisphere, as measured by asymmetry index (AI), was demonstrated within 24 hours of onset in 9 patients; this response was heterogenous between patients and on repeated measurement attenuated over time. Histologically, recruitment was confirmed within intravascular, intramural, and intraparenchymal compartments. Interindividual heterogeneity in neutrophil response did not correlate with infarct volume or outcome. In an exploratory analysis, neutrophil accumulation appeared to correlate significantly with infarct expansion (Spearman rho=0.66; P=0.03, n=12). CONCLUSIONS: Neutrophils recruit to areas of ischemic brain within 24 hours of symptom onset. This recruitment attenuates over time and is confirmed histologically. While neutrophil accumulation may be associated with either the magnitude or the rate of infarct growth, these results require confirmation in future studies.

Tissue-to-blood transport of radiolabelled immunoglobulin injected into the web spaces of the hands of normal subjects and patients with breast cancer-related lymphoedema.

AIM: The ability to return interstitial protein to central blood is key to the defence against oedema. The aim of this study was to quantify this ability by measuring the rate at which radiolabelled human immunoglobulin (HIgG) accumulated in blood following injection into the subcutis of the hand in normal volunteers and in patients with breast cancer-related lymphoedema (BCRL). METHODS: A total of 37 control subjects (healthy normal volunteers or breast cancer patients prior to treatment) and 18 women with BCRL were studied with dual-isotope lymphoscintigraphy. Each received bilateral subcutaneous depot injection in the dorsal web space of HIgG labelled with Tc-99m on one side and In-111 on the other. Activities remaining at the depot and accumulating in blood were measured at regular intervals for 3 h. Clearance from the depot was exponential and expressed as the rate constant k(depot) (min(-1)). Accumulation in blood was essentially linear and, using an estimate of blood volume based on height and weight, was expressed as the linear constant b(blood) (% administered activity x min(-1)). The time axis intercept of this linear fit was recorded as an index of the minimum time to arrival of radioprotein in blood. The efficiency with which radioprotein that has left the depot (extra-depot activity) is transported into blood [tissue-to-blood (T-B) transport] was quantified (1) as the quotient b(blood)/k(depot), and (2) as a function of time after injection by comparing the total amount of radioprotein in blood at any time with the total amount of radioprotein that was no longer in the depot at the same time. RESULTS: Tc-99m-HIgG and In-111-HIgG behaved similarly and are interchangeable. At all times between 60 and 180 min in controls, about 50% of protein that had left the depot was present in blood. T-B transport was reduced to about 20% in BCRL arms in which the hand was involved in swelling (p < 0.001 versus controls), but remained unchanged in patients in whom the hand was spared. The minimum time to arrival of radioprotein in blood was not reduced in BCRL; on the contrary, there appeared to be a small proportion of injected activity that arrived rapidly in blood in BCRL patients but not in controls. CONCLUSION: We conclude that T-B transport is only impaired in BCRL when radioprotein is injected into swollen tissue. Significant quantities of radioprotein may escape from the arm via local access to blood. Individual variation in this capacity may explain the regional sparing observed in BCRL.

Accumulation of technetium-99m glucarate: in vitro cell cultures and in vivo tumour models.

99mTc-glucarate is an investigational radiopharmaceutical which has been shown to accumulate in acute cerebral and myocardial injuries and in some tumours. In the present work, a survey of possible factors affecting the cellular accumulation of 99mTc-glucarate was carried out in cell lines and strains in vitro and in murine tumours in vivo. Accumulation was enhanced under hypoxic conditions in 12 of the 16 human and murine cell lines and strains studied, and inhibited in the presence of nitroimidazoles. At temperatures lower than 37 degrees C, accumulation was reduced, but a hypoxic/aerobic differential was maintained. Aerobic accumulation of 99mTc-glucarate was enhanced by cyanide. In transplanted tumours in mice, 99mTc-glucarate showed high tumour/muscle and tumour/blood ratios at early times after injection. Pharmacological enhancement of the extent of hypoxia by the administration of hydralazine or nitro-L-arginine resulted in significantly increased accumulation of 99mTc-glucarate in the tumour. The in vitro and in vivo properties of 99mTc-glucarate suggest that it may be useful for tumour imaging in the clinic, although the exact mechanism(s) by which it localizes in tumours remains unknown.

The influence of carrier on 99mTc radiopharmaceuticals.

High specific activity 99mTc-labelled radiopharmaceuticals are required in order to avoid saturating receptor sites and to minimise pharmacologic or toxic effects. The specific activity of 99mTc-pertechnetate is maximised by use shortly after elution from a generator which had been eluted at frequent intervals. Effective specific activity can be maximised by a variety of means. Often is it possible to label a very small amount of precursor with a large amount of 99mTc and use the product without further purification; this is limited by the potency of the ligand and the efficiency of labelling, which in turn is affected by the choice of chelator. A variety of purification techniques have been used, ranging from solvent extraction, solid-phase extraction cartridges, and size-exclusion columns to high-pressure liquid chromatography. Excess unchelated thiol-containing ligands (e.g. N2S2, N3S) can be removed by a thiol-trapping resin. Finally, solid-phase synthesis, in which the precursor is immobilised on a solid support (resin or gold) and only released into solution during chelation of 99mTc, is a promising method. High specific activity will become increasingly important with the next generation of 99mTc radiopharmaceuticals.