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Contains fulltext : 69879.pdf (Publisher’s version ) (Open Access) The role of fluorodeoxyglucose positron emission tomography (FDG PET) in the diagnostic localization of infectious diseases has expanded rapidly in years. In general, sensitivity of FDG PET in depicting infections compares favorably to other diagnostic modalities . It is shown to be useful in patients with suspected osteomyelitis, especially in chronic low grade infections and in vertebral osteomyelitis. although the sensitivity of FDG PET in prosthetic joint infections is very high, reported specificity varies considerably. In experienced centers, FDG uptake localized along the interface between bone and prosthesis can be used to diagnose infection with acceptable specificity. Combined leukocyte scintigraphy and bone scanning, however, remains the standard scintigraphic method for diagnosis of infected joint prostheses. FDG PET has shown promising results in vascular graft infections, in the evaluation of metastatic infectious foci inpatients with blood stream infections and in neutropenic patients, but further studies are needed before definitive conclusions can be drawn . In fever of unknown origin (FUO), FDG PET appears to be of great advantage as malignancy, inflammation and infection can be detected. Image fusion combining PET and computed tomography facilitates anatomical localization of increased FDG uptake and better guiding for further diagnostic tests to achieve a final diagnosis. In conclusion, the body of evidence on utility of FDG PET in infectious diseases and FUO is growing and FDG PET may become one of the preferred diagnostic procedures for many of these diseases, especially when a definite diagnosis cannot easily be achieved.

Contains fulltext : 52045.pdf (Publisher’s version ) (Open Access) Multi-modality imaging is rapidly becoming an essential tool in oncology. Clinically, the best example of multimodality imaging is seen in the rapid evolution of hybrid positron emission tomography (PET)/computed tomography (CT) and single positron emission computed tomography (SPECT)/CT scanners. However, use of multi-modality imaging is prone to artefacts and pitfalls. Important artefacts that may lead to clinical misinterpretation result from the use of CT data to correct for attenuation and the existence of mismatches between the fused images, for example due to respiratory movement. Furthermore, for institutions who proceed from a standalone PET to a hybrid PET-CT, there is an issue of interchangeability between these systems, especially for quantitative studies. Another issue is visualisation: hospital PACS is not sufficiently capable of adequately viewing integrated images. This article reviews and illustrates the most common artefacts and pitfalls that can be encountered in multi-modality nuclear medicine imaging. For correct management of oncological patients it is essential to be able to detect and correctly interpret these artefacts and pitfalls. Therefore, solutions and recommendations to these problems are provided.

Contains fulltext : 52967.pdf (Publisher’s version ) (Closed access) PURPOSE: The integrin alpha(v)beta(3) is expressed on sprouting endothelial cells and on various tumour cell types. Due to the restricted expression of alpha(v)beta(3) in tumours, alpha(v)beta(3) is considered a suitable receptor for tumour targeting. In this study the alpha(v)beta(3) binding characteristics of an (111)In-labelled monomeric, dimeric and tetrameric RGD analogue were compared. METHODS: A monomeric (E-c(RGDfK)), dimeric (E-[c(RGDfK)](2)), and tetrameric (E{E[c(RGDfK)](2)}(2)) RGD peptide were synthesised, conjugated with DOTA and radiolabelled with (111)In. In vitro alpha(v)beta(3) binding characteristics were determined in a competitive binding assay. In vivo alpha(v)beta(3) targeting characteristics of the compounds were assessed in mice with SK-RC-52 xenografts. RESULTS: The IC(50) values for DOTA-E-c(RGDfK), DOTA-E-[c(RGDfK)](2), and DOTA-E{E[c(RGDfK)](2)}(2)were 120 nM, 69.9 nM and 19.6 nM, respectively. At all time points, the tumour uptake of the dimer was significantly higher as compared to that of the monomer. At 8 h p.i., tumour uptake of the tetramer (7.40+/-1.12%ID/g) was significantly higher than that of the monomer (2.30+/-0.34%ID/g), p

Contains fulltext : 52853.pdf (Publisher’s version ) (Closed access) Interleukin 8 (IL-8) is a chemotactic cytokine that binds with a high affinity to receptors expressed on neutrophils. Previous studies with various animal models showed that (99m)Tc-labeled IL-8 accumulates specifically and rapidly in infectious and inflammatory foci. The aims of the present study were to evaluate the safety of IL-8 in humans and to assess the value of (99m)Tc-IL-8 scintigraphy in patients with suspected localized infections. METHODS: (99m)Tc-IL-8 was intravenously injected at 400 MBq into 20 patients with various suspected localized infections. Patients were monitored for IL-8-related side effects for 4 h. Whole-body imaging was performed directly after injection and at 4 h after injection. Imaging after 24 h was performed for the first 7 patients and for subsequent patients when the results of (99m)Tc-IL-8 scintigraphy at 4 h after injection were normal or equivocal. Blood was drawn at several time points to determine the total number of leukocytes and leukocyte differentiation (all patients) and to determine pharmacokinetics (6 patients). RESULTS: (99m)Tc-IL-8 scintigraphy was performed for 20 patients (13 men and 7 women) with a mean age of 60 y (range, 21-76 y). No significant side effects were noted. Patients had suspected joint prosthesis infections (n = 9), osteomyelitis (n = 8), liver abscess (n = 1), and soft-tissue infections (n = 2). (99m)Tc-IL-8 was rapidly cleared from the blood and most other organs. In 10 of 12 patients with infections, (99m)Tc-IL-8 localized the infection at 4 h after injection. In 1 patient with vertebral osteomyelitis and in 1 patient with an infected knee prosthesis, (99m)Tc-IL-8 scintigraphy results were false-negative. In 8 patients with noninfectious disorders, no focal accumulation of (99m)Tc-IL-8 was found. CONCLUSION: Injection of (99m)Tc-IL-8 is well tolerated. (99m)Tc-IL-8 scintigraphy is a promising new tool for the detection of infections in patients as early as 4 h after injection.

Contains fulltext : 50977.pdf (Publisher’s version ) (Closed access) Fine-needle aspiration biopsy (FNAB) is inconclusive in up to 20% of patients with solitary thyroid nodules. In these cases, hemithyroidectomy is necessary, but only 20% of the nodules prove to be thyroid carcinoma. The aim of this study was to explore the potential of (18)F-FDG PET to reduce the number of unnecessary hemithyroidectomies in the preoperative assessment of thyroid nodules with inconclusive FNAB results. METHODS: Forty-four consecutive patients, scheduled for hemithyroidectomy because of inconclusive FNAB findings, participated in this prospective study. (18)F-FDG PET of the thyroid region was performed before hemithyroidectomy, and standardized uptake values were calculated. The final histopathologic diagnosis served as a standard of reference. RESULTS: Histopathologic examination of the surgical specimens revealed 7 well-differentiated thyroid carcinomas in 6 patients, all accumulating (18)F-FDG (negative predictive value, 100%). (18)F-FDG accumulated in 13 of 38 benign nodules. The pre-PET probability for cancer in this study population was 14% (6/44), and the post-PET probability increased to 32% (6/19). The percentage of unnecessary hemithyroidectomies in a hypothetical algorithm using (18)F-FDG PET was only 30% (13/44), compared with 86% (38/44) without (18)F-FDG PET. (18)F-FDG PET reduced the number of futile hemithyroidectomies by 66% (25/38) (95% confidence interval, 49%-80%; Fisher's exact test, P = 0.0038). Semiquantitative analysis using standardized uptake values did not help to further reduce this number. CONCLUSION: In addition to data in the literature demonstrating accurate detection of thyroid cancer by (18)F-FDG PET, this study showed that (18)F-FDG PET should play an important role in the management of patients with inconclusive cytologic diagnosis of a thyroid nodule. (18)F-FDG PET reduced the number of futile hemithyroidectomies by 66%. Although PET is a relatively costly procedure, this cost outweighs the costs and risks associated with unnecessary thyroid surgery.

Contains fulltext : 49906.pdf (Publisher’s version ) (Open Access) [18F]Fluorodeoxyglucose (FDG) positron emission tomography (PET) is a useful imaging tool in the evolving management of patients with colorectal carcinoma. This technique is able to measure and visualize metabolic changes in cancer cells. This feature results in the ability to distinguish viable tumor from scar tissue, in the detection of tumor foci at an earlier stage than possible by conventional anatomic imaging and in the measurement of alterations in tumor metabolism, indicative of tumor response to therapy. Nowadays, FDG-PET plays a pivotal role in staging patients before surgical resection of recurrence and metastases, in the localization of recurrence in patients with an unexplained rise in serum carcinoembryonic antigen and in assessment of residual masses after treatment. In the presurgical evaluation, FDG-PET may be best used in conjunction with anatomic imaging in order to combine the benefits of both anatomical (CT) and functional (PET) information, which leads to significant improvements in preoperative liver staging and preoperative judgment on the feasibility of resection. Integration of FDG-PET into the management algorithm of these categories of patients alters and improves therapeutic management, reduces morbidity due to futile surgery, leads to substantial cost savings and probably also to a better patient outcome. FDG-PET also appears to have great potential in monitoring the success of local ablative therapies soon after intervention and in the prediction and evaluation of response to radiotherapy, systemic therapy, and combinations thereof. This review aims to outline the current and future role of FDG-PET in the field of colorectal cancer.

Contains fulltext : 49930.pdf (Publisher’s version ) (Closed access) 111In-Diethylenetriaminepentaacetic acid-octreotide generally is used for the scintigraphic imaging of neuroendocrine and other somatostatin receptor-positive tumors. On the basis of the successful targeting of octreotide, radiolabeled somatostatin analogs, such as 90Y-(1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid [DOTA])0-Tyr3-octreotide and 177Lu-DOTA0-Tyr3-octreotate, were developed for peptide receptor radionuclide therapy. However, the maximum tolerated doses of these analogs are limited because of the high and persistent renal uptake that leads to relatively high radiation doses in the kidneys. Renal uptake can be reduced by coinfusion of basic amino acids or polypeptides. However, high doses of basic amino acids can induce severe side effects. It was reported that the infusion of gelatin-based plasma expanders resulted in increased low-molecular-weight proteinuria, suggesting that these plasma expanders interfere with the tubular reabsorption of peptides and proteins. In the present study, we analyzed the effects of several plasma expanders on the renal uptake of 111In-octreotide in rats and mice. METHODS: Wistar rats and BALB/c mice were injected with 0.5 or 0.1 mL of plasma expander, respectively. Thereafter, the animals received 111In-octreotide intravenously. Animals were killed at 20 h after the injection of the radiopharmaceutical. Organs were dissected, and the amount of radioactivity in the organs and tissues was measured. RESULTS: The administration of 20 mg of Gelofusine in rats or 4 mg in mice was as effective in reducing the renal uptake of 111In-octreotide as the administration of 80 or 20 mg of lysine in rats or mice, respectively, without reducing 111In-octreotide uptake in receptor-positive organs. Plasma expanders based on starch or dextran had no effect on the renal uptake of 111In-octreotide. CONCLUSION: The gelatin-based plasma expander Gelofusine significantly reduced the kidney uptake of 111In-octreotide as effectively as did lysine. Because Gelofusine is a well-known and generally used blood volume substitute that can be applied safely without the induction of toxicity, evaluation of this compound for its potential to reduce the kidney uptake of radiolabeled peptides in patients is warranted.

Contains fulltext : 48993.pdf (Publisher’s version ) (Closed access) Timely identification of metastatic complications of bloodstream infections due to spreading of the microorganisms to distant sites, although critical, is often difficult. As (18)F-FDG accumulates in activated leukocytes in infectious lesions, (18)F-FDG PET represents a promising imaging technique in these patients. The aim of this study was to assess the value of (18)F-FDG PET in detecting infectious foci in patients at high risk of metastatic complications. METHODS: The results of all (18)F-FDG PET scans ordered because of suspected metastatic infection from October 1998 to September 2004 were analyzed retrospectively. These results were compared with conventional investigation techniques and the final clinical diagnosis. RESULTS: The results of 40 (18)F-FDG PET scans were evaluated. In 60% of all episodes, Gram-positive bacteria were cultured, in 18% Gram-negative bacteria, in 20% Candida spp., and in 3% the infection was polymicrobial. Metastatic complications were diagnosed in 75% of all episodes. A median number of 4 diagnostic procedures to search for metastatic infection had been performed before (18)F-FDG PET was ordered. (18)F-FDG PET diagnosed a clinically relevant new focus in 45% of cases and confirmed abnormalities already diagnosed in 30% of cases. The positive predictive value of (18)F-FDG PET was 91% and the negative predictive value was 100%. CONCLUSION: (18)F-FDG PET is a valuable imaging technique in patients at high risk of metastatic infectious disease, even when the results of other diagnostic procedures are normal.

Contains fulltext : 58917.pdf (Publisher’s version ) (Open Access) Radioimmunotherapy (RIT) can be performed with various radionuclides. We tested the stability, biodistribution, and therapeutic efficacy of various radioimmunoconjugates ((131)I, (88/90)Y, (177)Lu, and (186)Re) of chimeric antirenal cell cancer monoclonal antibody G250 (mAb cG250) in nude mice with subcutaneous renal cell cancer (RCC) tumors. METHODS: The (88/90)Y and (177)Lu labeling procedures of cG250 conjugated with cyclic diethylenetriaminepentaacetic acid anhydride (cDTPA), isothiocyanatobenzyl-DTPA (SCN-Bz-DTPA), or 1,4,7,10-tetraazacyclododecanetetraacetic acid (DOTA) were characterized. Stability of the labeled conjugates in plasma at 37 degrees C was assessed. Biodistribution and therapeutic efficacy of labeled cG250 were compared in nude mice with SK-RC-52 human RCC xenografts. RESULTS: Both SCN-Bz-DTPA and DOTA were stable in vitro (

Contains fulltext : 57728.pdf (Publisher’s version ) (Open Access) The CXC chemokines are a family of closely related chemoattractant cytokines that bind to, attract, and activate neutrophils to variable degrees. In this study, the relationship between neutrophil-binding affinity and suitability for infection imaging was investigated in a selected group of CXC chemokines. Neutrophil-activating peptide-2 (NAP-2, 70 residues; also called CXCL7) binds with high affinity to the CXCR2 receptor on neutrophils. Recently, C-terminally truncated NAP-2-variants have been described that have enhanced neutrophil-binding affinity and neutrophil-stimulating capacity. Here, NAP-2 and its C-terminal shortened variants NAP-2(1-68), NAP-2(1-66), and NAP-2(1-63) were labeled with (99m)Tc via the hydrazinonicotinamide (HYNIC) chelator and their potential for imaging of infection was investigated in a rabbit model of infection. The CXC chemokine interleukin-8 (IL-8) was used for comparison. In addition, a series of (99m)Tc-labeled CXC chemokines were screened for their potential to image infection, including CTAP-III, GCP-2, ENA-78, PF-4, and IP-10. METHODS: The receptor-binding affinity of HYNIC-conjugated NAP-2 and its analogs was compared in competitive binding assays on Jurkat cells transfected with the CXCR2 receptor gene. Biodistribution of labeled NAP-2 (analogs) and other CXC chemokines in rabbits with intramuscular Escherichia coli infections was determined both by gamma-camera imaging and by counting dissected tissues at 6 h after injection. RESULTS: The CXCR2-binding affinity of the HYNIC-conjugated NAP-2 analogs relative to NAP-2 was as follows: NAP-2(1-68), 2.5-fold; NAP-2(1-66), 10-fold; and NAP-2(1-63), 3-fold. In the rabbit model, uptake in the abscess (in percentage injected dose per gram +/- SEM) was 0.084 +/- 0.015 for NAP-2, 0.098 +/- 0.010 for NAP-2(1-68), 0.189 +/- 0.044 for NAP-2(1-66), and 0.114 +/- 0.017 for NAP-2(1-63) at 6 h after injection. In comparison, higher uptake in the abscess was found for labeled IL-8, a modest uptake was found for GCP-2 and ENA-78, and a low uptake was found for CTAP-III, PF-4, and IP-10. CONCLUSION: This study showed a clear relationship between affinity to receptors on neutrophils and suitability for infection imaging. Of the NAP-2 variants, NAP-2(1-66) combined highest affinity to CXCR2 with the best characteristics for imaging. IL-8 binds to both CXCR1 and CXCR2 with high affinity and showed a superior imaging quality. The other CXC chemokines tested bind to neutrophils with lower affinity and were shown to be less suitable for infection imaging in this study.

Contains fulltext : 57827.pdf (Publisher’s version ) (Closed access) A single, low dose of recombinant human thyroid-stimulating hormone (rhTSH) doubles 24-h RAIU and causes a more homogeneous distribution of radioiodine on thyroid scintigrams of patients with nodular goiter. Pretreatment with rhTSH allows the therapeutic dose of (131)I to be reduced by 50%-60% without compromising the result of thyroid volume reduction. The present study focused on the dosimetric aspects of therapy with a reduced dose of (131)I after pretreatment with rhTSH in patients with nodular goiter. METHODS: Thirty-six patients were treated with (131)I to reduce thyroid volume. Nine patients were pretreated with a single dose of 0.01 mg of rhTSH, and 9 patients, with 0.03 mg of rhTSH. Two control groups of 9 patients, matched for thyroid weight and 24-h radioactive iodide uptake, were not pretreated with rhTSH. The therapeutic dose of (131)I was aimed at being sufficient to result in retention of 3.7 MBq of (131)I per gram of thyroid tissue at 24 h. Thyroid radioactivity after (131)I administration was measured every 24 h for 3 d and on days 7, 10, 14, 21, and 28. A model of iodine biokinetics was used to estimate absorbed doses in organs. Protein-bound (131)I activity was measured at 1, 2, 3, 7, and 10 d and at 2, 3, and 4 wk after (131)I therapy. RESULTS: The administered activities were 1.5 times lower in the 0.01-mg rhTSH group and 1.9 times lower in the 0.03-mg rhTSH group than in the control groups. The absorbed dose in the thyroid was similar in the rhTSH-pretreated groups and in the control groups. In the organs of excretion (bladder) and uptake (stomach) of inorganic iodide, the absorbed doses were 2- to 3-fold lower in the pretreated groups than in the control groups. The effective dose equivalent outside the thyroid was considerably lower in the rhTSH-pretreated groups than in their respective control groups (1.6-fold in the 0.01-mg rhTSH group and 2.3-fold in the 0.03-mg rhTSH group). The time course of protein-bound (131)I activity in serum and the cumulated protein-bound (131)I activity in serum did not differ significantly between rhTSH-pretreated and control groups. CONCLUSION: (131)I therapy after pretreatment with a single, low dose of rhTSH, with the dose reduced according to the rhTSH-induced increase in 24-h radioactive iodide uptake, caused lower radiation-absorbed doses in extrathyroidal organs and tissues, especially bladder and stomach, and no significant increase in the release of (131)I-labeled thyroid hormones into the circulation of patients with nodular goiter. Thus, this mode of therapy can be recommended, especially when the dose of radioiodine to be administered without rhTSH pretreatment is high.

Contains fulltext : 58957.pdf (Publisher’s version ) (Closed access) Radiolabeled chemotactic peptides have been studied for their applicability to the visualization of infectious and inflammatory foci. Because a radiolabeled leukotriene B4 (LTB4) antagonist allowed visualization of intramuscular E. coli abscesses in rabbits within a few hours after injection, we decided to test the imaging characteristics of this agent in a more clinically relevant model of pulmonary aspergillosis. The pharmacokinetics and imaging characteristics of the 111In-labeled LTB4 antagonist DPC11870 were studied in New Zealand White rabbits with experimental pulmonary aspergillosis infection. The imaging characteristics of 111In-DPC11870 were compared with those of 67Ga-citrate, a radiopharmaceutical commonly used to detect pulmonary infections in patients. METHODS: Pulmonary aspergillosis was induced in the left lung of rabbits by intratracheal inoculation of 1 x 10(8) conidia of Aspergillus fumigatus. Three days after the inoculation, the rabbits received 111In-DPC11870 or 67Ga-citrate intravenously. Images were acquired at several time points up to 24 h after injection. RESULTS: Pulmonary aspergillosis was visualized with both agents. Images acquired after injection of 111In-DPC11870 showed uptake in the pulmonary lesions from 6 h after injection. Because of accumulation at the site of infection and clearance from the background, the images improved with time. Region-of-interest analysis at 24 h after injection revealed infected lung-to-normal lung ratios of 5.0 +/- 1.5 for 111In-DPC11870 and 2.9 +/- 0.6 for 67Ga-citrate. CONCLUSION: The radiolabeled LTB4 antagonist DPC11870 clearly delineated experimentally induced pulmonary aspergillosis in rabbits. Images acquired at 24 h after injection of 111In-DPC11870 were superior to those obtained after injection of 67Ga-citrate.

Item does not contain fulltext In patients with nodular goiter, radioiodine ((131)I) therapy results in a mean reduction in thyroid volume (TV) of approximately 40% after 1 yr. We have demonstrated that pretreatment with a single, low dose of recombinant human TSH (rhTSH) doubles 24-h radioactive iodine uptake (RAIU) in these patients. We have now studied the safety and efficacy of therapy with a reduced dose of (131)I after pretreatment with rhTSH. Twenty-two patients with nodular goiter received (131)I therapy, 24 h after im administration of 0.01 (n = 12) or 0.03 (n = 10) mg rhTSH. In preceding diagnostic studies using tracer doses of (131)I, 24-h RAIU without and with rhTSH pretreatment (either 0.01 or 0.03 mg) were compared. Therapeutic doses of (131)I were adjusted to the rhTSH-induced increases in 24-h RAIU and were aimed at 100 micro Ci/g thyroid tissue retained at 24 h. Pretreatment with rhTSH allowed dose reduction of (131)I therapy by a factor of 1.9 +/- 0.5 in the 0.01-mg and by a factor of 2.4 +/- 0.4 in the 0.03-mg rhTSH group (P < 0.05, 0.01 vs. 0.03 mg rhTSH). Before and 1 yr after therapy, TV and the smallest cross-sectional area of the tracheal lumen were measured with magnetic resonance imaging. During the year of follow-up, serum TSH, free T(4) (FT(4)), T(3), and TSH receptor antibodies were measured at regular intervals. TV before therapy was 143 +/- 54 ml in the 0.01-mg group and 103 +/- 44 ml in the 0.03-mg rhTSH group. One year after treatment, TV reduction was 35 +/- 14% (0.01 mg rhTSH) and 41 +/- 12% (0.03 mg rhTSH). In both groups, smallest cross-sectional area of the tracheal lumen increased significantly. In the 0.01-mg rhTSH group, serum FT(4) rose, after (131)I treatment, from 15.8 +/- 2.8 to 23.2 +/- 4.4 pM. In the 0.03-mg rhTSH group, serum FT(4) rose from 15.5 +/- 2.5 to 23.5 +/- 5.1 pM. Individual peak FT(4) levels, reached between 1 and 28 d after (131)I treatment, were above the normal range in 12 patients. TSH receptor antibodies were negative in all patients before therapy and became positive in 4 patients. Hyperthyroidism developed in 3 of these 4 patients between 23 and 25 wk after therapy. In conclusion, in patients with nodular goiter pretreatment with a single, low dose of rhTSH allowed approximately 50-60% reduction of the therapeutic dose of radioiodine without compromising the efficacy of TV reduction.

Item does not contain fulltext BACKGROUND: Infection of a renal or hepatic cyst is a serious complication of autosomal dominant polycystic kidney disease (ADPKD). Although crucial for successful management, early diagnosis is difficult, largely because of nonspecific symptoms and limitations of conventional imaging techniques. Because of an increased metabolic rate, inflammatory cells take up large amounts of glucose. 18-F-fluorodeoxyglucose (FDG), therefore, represents a promising agent for detection of cyst infections using positron emission tomography (PET). METHODS: The authors studied the results of 7 FDG PET scans in 3 ADPKD patients suspected of renal or hepatic cyst infection. Two PET scans were performed in patient A (PET 1 and 2), one PET scan was performed in patient B (PET 3), and 4 PET scans were performed in patient C (PET 4, 5, 6 and 7). RESULTS: FDG PET identified the infected cysts in 2 episodes of renal cyst infection (PET 2 and 3), 2 episodes of hepatic cyst infection (PET 6 and 7), and 1 episode of both renal and hepatic cyst infection (PET 1). In patient C, FDG PET was normal after 6 weeks of antibiotic treatment for hepatic cyst infection (PET 4) and again at a time when hepatic cyst infection was suspected, but eventually colchicine intoxication was diagnosed (PET 5). CONCLUSION: In these patients, FDG PET proved very helpful in diagnosing and in excluding renal and hepatic cyst infections. It is concluded that FDG PET is a promising new imaging technique enabling early identification of renal and hepatic cyst infections in ADPKD patients.

Item does not contain fulltext Several radiolabeled chemotactic peptides have been tested for their suitability to show infection and inflammation. Leukotriene B(4) (LTB(4)) receptor-binding ligands could be useful agents for revealing neutrophilic infiltrations because the LTB(4) receptor is abundantly expressed on neutrophils after an inflammatory stimulus. In this study, we investigated the in vivo and in vitro characteristics of a new hydrophilic (111)In-labeled LTB(4) antagonist. METHODS: The LTB(4) antagonist DPC11870-11 was labeled with (111)In and intravenously injected into New Zealand White rabbits with Escherichia coli infection in the left thigh muscle. The pharmacokinetics and biodistribution were studied by serial scintigraphic imaging (0-24 h after injection) and by ex vivo counting of dissected tissues (6 and 24 h after injection). The receptor-mediated in vivo localization of the compound was investigated in 3 rabbits that received an excess of nonradioactive indium-labeled agent 2 min before the administration of the (111)In-labeled LTB(4) antagonist. RESULTS: In rabbits with intramuscular E. coli infection, the abscess was visualized as early as 2 h after injection. Accumulation in the abscess increased with time, resulting in excellent images at 6 h after injection. Blood clearance was rapid in the first hours after injection (alpha-half-life = 30 +/- 6 min, 85%; beta-half-life = 25.7 +/- 0.8 h, 15%). Abscess-to-background ratios, as derived from the region-of-interest analysis, increased to 34 +/- 7 at 24 h after injection. The images of both groups showed moderate uptake in the liver, spleen, kidneys, and bone marrow. No activity was seen in the bladder, indicating almost complete retention in the kidneys. The uptake in the abscess could be blocked completely by injection of an excess of nonradioactive agent, indicating a specific receptor-ligand interaction of the radiolabeled agent in the infected tissue. Biodistribution data showed that after saturation of the LTB(4) receptor, the abscess uptake, in percentage injected dose per gram, was significantly reduced (0.03 +/- 0.02 vs. 0.24 +/- 0.06, P = 0.008). CONCLUSION: The modified LTB(4) antagonist showed infectious foci rapidly after injection because of specific receptor-ligand interaction. Because of the high abscess-to-background ratios that were obtained and the fact that no accumulation of radioactivity was observed in the gastrointestinal tract, this compound has excellent characteristics for revealing infectious and inflammatory foci.

Item does not contain fulltext PURPOSE: Infective endocarditis (IE) is characterized by aggregation of activated platelets, fibrin, and bacteria. DMP444, a high-affinity glycoprotein IIb/IIIa receptor antagonist, binds to the fibrinogen-binding domain of activated platelets, depicting a key feature of IE. Tc-99m DMP444 scintigraphy was studied in a group of patients with possible IE. METHODS: Tc-99m DMP444 (600 MBq; 16 mCi) planar and SPECT images of the heart were recorded in patients with possible IE for as long as 6 hours after injection. Results were compared to echocardiography and the Duke classification. RESULTS: Sixteen patients (age range, 37 to 78 years) participated. DMP444 imaging was positive on SPECT in five patients, and all had definite endocarditis (affecting both prosthetic and native valves). Eleven patients were DMP444 negative, seven with no proof of IE. The remaining four patients were classified as having IE, but three had been receiving adequate intravenous antibiotic regimens for > or = 2 weeks at the time of scintigraphy and one had Q-fever endocarditis. CONCLUSIONS: DMP444 SPECT allows in vivo visualization of IE if it is performed within 1 to 2 weeks after the start of antibiotic treatment. Given the high affinity of DMP444 for activated platelets, the results indicate the involvement of activated platelets in early IE.

Item does not contain fulltext To enhance the therapeutic efficacy of radioimmunotherapy of cancer, several pretargeting strategies have been developed. In pretargeted radioimmunotherapy, the tumor is pretargeted with an antibody construct that has affinity for the tumor-associated antigen on the one hand and for a radiolabeled hapten on the other. The radiolabeled hapten is administered in a later phase, preferably after the antibody construct has cleared from the circulation. In pretargeted radioimmunotherapy, 2 main approaches can be distinguished: pretargeting strategies based on the avid interaction between streptavidin (SA) or avidin and biotin, and pretargeting strategies based on the use of bispecific antibodies. In pretargeting strategies based on biotin and SA or avidin, the use of a clearing agent that could remove the pretargeting construct from the circulation markedly improved the targeting of the radiolabeled biotin to the tumor. Thus, multistep injection schemes in which 3-5 different agents are subsequently injected were developed. In bispecific antibody-based pretargeting strategies, the use of bivalent haptens improved the efficacy of the tumor targeting, and a 2-step pretargeted radioimmunotherapy strategy is now being tested in cancer patients. Preclinical studies as well as studies on cancer patients have shown that these pretargeting strategies can result in higher radiation doses to the tumor than can directly radiolabeled antitumor antibodies. Here, the development and state of the art of the most effective approaches for pretargeted radioimmunotherapy are reviewed.

Item does not contain fulltext PURPOSE: There is increasing evidence that the chimeric monoclonal antibody G250 (cG250) can be internalized by G250 antigen-expressing renal cell carcinoma (RCC) cells. Thus, accumulation in tumors of cG250 labeled with residualizing radionuclides might be higher than that of nonresidualizing (131)I-cG250. Here, we present a study comparing intrapatiently the accumulation of (131)I-cG250 and (111)In-cG250 in RCC metastases. EXPERIMENTAL DESIGN: Five patients were i.v. injected with 222 MBq (111)In-ITC-DTPA-cG250 and 222 MBq (131)I-cG250 on days 0 and 4, respectively. Directly and 4 days after the injection of both antibody preparations, whole body gamma camera images were acquired. The scintigraphic images were analyzed visually and quantitatively. The radioactivity in tissues was calculated and expressed as percentage injected dose in organs or percentage injected dose/g in metastases. For the latter, tumor:blood ratios were also calculated. Twenty-five metastases were analyzed completely. RESULTS: At 4 days postinjection, the (111)In-ITC-DTPA-cG250 images revealed more metastatic lesions (n = 47) than (131)I-cG250 (n = 30). Quantitative analysis of the images showed higher activities of (111)In-ITC-DTPA-cG250 than (131)I-cG250 in 20 of 25 lesions. The mean overall half-life of both antibody preparations in plasma was similar. CONCLUSIONS: (111)In-ITC-DTPA-cG250 outperformed (131)I-cG250 for visualization of metastatic RCC lesions, not just because of the superior gamma camera characteristics of (111)In, but more importantly, also because higher tumor:blood ratios were obtained. The higher activities of (111)In-ITC-DTPA-cG250 in metastatic lesions might be caused by internalization and subsequent intracellular retention of the radiolabel, implying that in future radioimmunotherapy trials with cG250 in RCC patients, the use of a residualizing radionuclide should be considered.

Item does not contain fulltext Radiolabeled autologous leukocytes are the gold standard for imaging infectious foci in patients. Good results have also been reported for radiolabeled heterologous leukocytes from noninfected donors. Until now, the 2 methods have not been directly compared. In this study, we compared the infection-imaging potential of 99mTc-hexamethylpropyleneamine oxime (HMPAO)-labeled autologous granulocytes with that of 99mTc-HMPAO-labeled granulocytes from either infected or noninfected donors in rabbits with Escherichia coli infection. METHODS: The radiolabeled granulocyte preparations were studied in rabbits with an E. coli infection in the left calf muscle. The soft-tissue infections were scintigraphically visualized after injection of 18 MBq of either 99mTc-HMPAO purified autologous granulocytes or radiolabeled purified heterologous granulocytes from infected or noninfected donor rabbits. Gamma camera images were acquired at 2 min and at 1, 2, and 4 h after injection. After the last image, the rabbits were killed and uptake of the radiolabel in the dissected tissues was determined. RESULTS: The 99mTc-HMPAO autologous granulocytes and heterologous granulocytes from infected donors accurately revealed the infectious focus in the calf muscle at 2 h after injection. At 4 h after injection, a significantly better (P < 0.05) delineation of the infection was established with the 99mTc-HMPAO autologous granulocytes and 99mTc-HMPAO heterologous granulocytes from the infected rabbits than with the heterologous granulocytes from noninfected donors. With both cell preparations, the intensity of uptake in the infected calf muscle continuously increased until 4 h after injection. The 99mTc-HMPAO heterologous granulocytes from noninfected donors showed no significant increase in contrast after 2 h after injection. Absolute uptake in the infected calf muscle was much higher for 99mTc-HMPAO autologous granulocytes (7.81 +/- 1.21 percentage injected dose [%ID]) and 99mTc-HMPAO heterologous infected granulocytes (8.91 +/- 1.92 %ID) than for the radiolabeled heterologous noninfected granulocytes (2.32 +/- 0.75 %ID) (P < 0.04) at 4 h after injection. The ratio of infected muscle to noninfected contralateral muscle was significantly higher for 99mTc-HMPAO autologous granulocytes and 99mTc-HMPAO heterologous granulocytes from infected donors than for 99mTc-HMPAO heterologous granulocytes from noninfected donors (5.53 +/- 1.09, 3.86 +/- 0.75, and 1.86 +/- 0.31, respectively; P < 0.05). CONCLUSION: For nuclear medicine imaging of infection, purified granulocytes derived from infected rabbits are superior to purified granulocytes derived from noninfected donor rabbits. In addition, autologous granulocytes gave similar results to heterologous granulocytes from infected donor rabbits, suggesting the need for intrinsic cell activation for specific granulocyte migration.

Item does not contain fulltext Although autologous leukocytes, labelled with 111In or 99mTc, is still considered the "gold standard" nuclear medicine technique to image infection and inflammation, there is a great need for a less cumbersome and less hazardous approach. Over the last few decades the range of radiopharmaceuticals to investigate infectious and non-microbial inflammatory disorders is vastly expanding. Radiolabelled monoclonal antibodies and antibody-fragments, radiolabelled chemotactic peptides and cytokines, and radiolabelled antibiotics are promising new approaches in the field of nuclear medicine. Recently, positron emission tomography (PET) with 18FJDG has been introduced and has been shown to delineate infectious and inflammatory foci with high sensitivity. Here, a survey is presented of the different approaches in use or under investigation.

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