Diffuse Paget's Disease of the Skull with Intense Uptake of Technetium-99m-Labeled Diphosphonate Tracer in Bone Scintigraphy.

Imaging in patients with Paget's disease of bone is very important clinically to show the presence of Pagetic abnormalities, assess disease progression, and identify adversely affected structures throughout disease course. Abnormalities and progression may be seen on radiographs, computed tomography, magnetic resonance imaging, and nuclear imaging. Herein, we report a case Paget's disease of bone showing diffuse characteristic pathology using technetium-99m-labelled diphosphonate tracer in bone scintigraphy (nuclear imaging). This case emphasizes the ability of nuclear imaging to rapidly visualize and assess progressive distribution of Pagetic involvement in a patient previously diagnosed with pituitary adenoma and mild Paget's disease of the skull.

An unusual delusion of duplication in a patient affected by Dementia with Lewy bodies.

BACKGROUND: Dementia with Lewy bodies (DLB) is the second most frequent diagnosis of progressive degenerative dementia in older people. Delusions are common features in DLB and, among them, Capgras syndrome represents the most frequent disturbance, characterized by the recurrent and transient belief that a familiar person, often a close family member or caregiver, has been replaced by an identical-looking imposter. However, other delusional conditions near to misidentification syndromes can occur in DLB patients and may represent a major psychiatric disorder, although rarely studied systematically. CASE PRESENTATION: We reported on a female patient affected by DLB who presented with an unusual delusion of duplication. Referring to the female professional caregiver engaged by her relatives for her care, the patient constantly described the presence of two different female persons, with a disorder framed in the context of a delusion of duplication. A brain 99Tc-hexamethylpropyleneamineoxime SPECT was performed showing moderate hypoperfusion in both occipital lobes, and associated with marked decreased perfusion in parieto-fronto-temporal lobes bilaterally. CONCLUSIONS: An occipital hypoperfusion was identified, although in association with a marked global decrease of perfusion in the remaining lobes. The role of posterior lobes is certainly important in all misidentification syndromes where a natural dissociation between recognition and identification is present. Moreover, the concomitant presence of severe attentional and executive deficits evocative for a frontal syndrome and the marked global decrease of perfusion in the remaining lobes at the SPECT scan also suggest a possible dysfunction in an abnormal connectivity between anterior and posterior areas.

Fluorescent Versus Radioguided Lymph Node Mapping in Bladder Cancer.

INTRODUCTION: The aim of the study was to compare 2 methods of the sentinel lymph node biopsy (SLNB) procedure in bladder cancer: we applied technetium radiocolloid (RadCol) detected by a gamma ray detection probe, and indocyanine green (ICG) detected by a near-infrared fluorescent (NIRF) camera. MATERIAL AND METHODS: The SLNB was performed on 50 patients using the RadCol and the ICG, followed by a lymphadenectomy and a pathologic examination. RESULTS: In the analyzed group of 47 patients (3 patients were excluded owing to the lack of lymphatic drainage from the tumor), the SLNB was performed using the 2 methods. The ICG with a NIRF-guided camera detected all sentinel lymph nodes (SLNs) in 46 cases, whereas RadCol detected them in 45 cases. In 12 (25.6%) of 47 patients, the ICG-fluorescent method revealed more SLNs than the RadCol method. In 8 (17%) patients, the SLNs revealed in the ICG fluorescence were metastatic. In 3 (6.4%) patients, we found SLNs outside the standard lymphadenectomy template, but a histopathologic examination showed they were negative for cancer. In 3 (6.4%) patients, the SLNs detected by both methods were negative for cancer, but other resected lymph nodes revealed metastases. CONCLUSION: Our study shows that SLNB procedure with the RadCol or the ICG method is useful for the evaluation of lymph nodes in bladder cancer. The new ICG fluorescent technique with a NIRF camera system is safe, enables live view of the results of the procedure, and does not create additional costs. However, it highlights more lymph nodes than the radioactive method.

PEGylation and biodistribution of an anti-MUC1 aptamer in MCF-7 tumor-bearing mice.

Aptamers are characterized by a rapid renal clearance leading to a short in vivo circulating half-life. In order to use aptamers as anticancer therapeutic agents, their exposure time to the tumor has to be enhanced via increasing residency in the bloodstream. A way to achieve this goal is by conjugating the aptamer to poly(ethylene glycol) (PEG). Herein, we present the conjugation of a bifunctionalized anti-MUC1 aptamer (NH(2)-AptA-SR) with the (99m)Tc coordinating moiety MAG2 and either a conventional branched PEG or the comb-shaped PolyPEG via a two-step synthesis. The isolated products were radiolabeled with (99m)Tc and their biodistribution and tumor-targeting properties in MCF-7 tumor bearing mice were analyzed and compared.

Osteopontin and bone metabolism: a histology and scintigraphy study in rats.

Osteopontin (OPN) is one of the major non-collagen proteins in extracellular bone matrix. To elucidate the function of OPN in bone metabolism, a cellular defect was created in parietal bone and tibia of 12 rats. In Group 1, the left defects were filled with OPN-coated hydroxyapatite (OPN-H). In Group 2, the right defects were filled with non-coated hydroxyapatite (N-H). In both groups, the contra lateral defects were used as control defects. In Group 3, OPN-H was inserted in the left defects and N-H in the right defects. Bone metabolism was measured by (45)Ca and technetium-99m methylene diphosphonate scintigraphy for 4 weeks. Scintigraphy did not show any significant differences in bone metabolism between the defects filled with OPN-H and N-H. A higher bone metabolism was measured between the parietal defects filled with OPN-H or N-H in comparison with the parietal control defects. This difference, however, was not significant and was less for tibia defects. Histological observation (7th week) shows less inflammatory cells at the tibia defects filled with OPN-H compared to the tibia defects filled with N-H. This study did not show any acceleration or inhibition of bone metabolism in parietal or tibia bone in rats, but there is some evidence that OPN might influence inflammatory cells in bone matrix.

GENIS: gene expression of sodium iodide symporter for noninvasive imaging of gene therapy vectors and quantification of gene expression in vivo.

With the goal of optimizing adenovirus-mediated suicide gene therapy for prostate cancer, we have developed a method based on the human sodium iodide symporter (hNIS) that allows for noninvasive monitoring of adenoviral vectors and quantification of gene expression magnitude and volume within the prostate. A replication-competent adenovirus (Ad5-yCD/mutTK(SR39)rep-hNIS) coexpressing a therapeutic yeast cytosine deaminase (yCD)/mutant herpes simplex virus thymidine kinase (mutTK(SR39)) fusion gene and the hNIS gene was developed. Ad5-yCD/mutTK(SR39)rep-hNIS and a replication-defective hNIS adenovirus (rAd-CMV-FLhNIS) were injected into contralateral lobes of the dog prostate and hNIS activity was monitored in live animals following administration of Na(99m)TcO(4) using gamma camera scintigraphy. Despite the close proximity of the urinary bladder, (99m)TcO(4)(-) uptake was readily detected in the prostate using viral dose levels (10(10) to 10(12) viral particles) that have been safely administered to humans. Due to its rapid clearance and short physical half-life (6 h), it was possible to obtain daily measurements of (99m)TcO(4)(-) uptake in vivo, allowing for dynamic monitoring of reporter gene expression within the prostate as well as biodistribution throughout the body. High-resolution autoradiography of prostate sections coupled with 3D reconstruction of gene expression demonstrated that the magnitude and volume of gene expression could be quantified with submillimeter resolution. Implementation of the GENIS (gene expression of Na/I symporter) technology in the clinic will facilitate optimization of future human gene therapy trials.

In vitro and in vivo evaluation of a 99mTc(I)-labeled bombesin analogue for imaging of gastrin releasing peptide receptor-positive tumors.

A new radiolabeled bombesin analogue, [99mTc(I)-PADA-AVA]bombesin (7-14), was synthesized and in vitro and in vivo characterized. High affinity and rapid internalization were obtained in binding assays. A specific binding towards gastrin releasing peptide receptors-positive tissues, pancreas and tumor, was observed in CD-1 nu/nu mice bearing PC-3 prostate adenocarcinoma xenografts. We therefore conclude that [99mTc(I)-PADA-AVA]bombesin (7-14) might have promising characteristics for applications in nuclear medicine, namely for diagnosis of GRP receptor overexpressing tumors.

Development of a Tc-99m labeled sigma-2 receptor-specific ligand as a potential breast tumor imaging agent.

A novel in vivo imaging agent, 99mTc labeled [(N-[2-((3'-N'-propyl-[3,3,1]aza-bicyclononan-3alpha-yl)(2"-methoxy-5-methyl-phenylcarbamate)(2-mercaptoethyl)amino)acetyl]-2-aminoethanethiolato] technetium(V) oxide), [99mTc]2, displaying specific binding towards sigma-2 receptors was prepared and characterized. In vitro binding assays showed that the rhenium surrogate of [99mTc]2, Re-2, displayed excellent binding affinity and selectivity towards sigma-2 receptors (K(i) = 2,723 and 22 nM for sigma-1 and sigma-2 receptor, respectively). Preparation of [99mTc]2 was achieved by heating the S-protected starting material, 1, in the presence of acid, reducing agent (stannous glucoheptonate) and sodium [99mTc]pertechnetate. The lipophilic racemic mixture was successfully prepared in 10 to 50% yield and the radiochemical purity was >98%. Separation of the isomers, peak A and peak B, was successfully achieved by using a chiralpak AD column eluted with an isocratic solvent (n-hexane/isopropanol; 3:1; v/v). The peak A and peak B appear to co-elute with the isomers of the surrogate, Re-2, under the same HPLC condition. Biodistribution studies in tumor bearing mice (mouse mammary adenocarcinoma, cell line 66, which is known to over-express sigma-2 receptors) showed that the racemic [99mTc]2 localized in the tumor. Uptake in the tumor was 2.11, 1.30 and 1.11 %dose/gram at 1, 4 and 8 hr post iv injection, respectively, suggesting good uptake and retention in the tumor cells. The tumor uptake was significantly, but incompletely, blocked (about 25-30% blockage) by co-injection of "cold" (+)pentazocine or haloperidol (1 mg/Kg). A majority of the radioactivity localized in the tumor tissue was extractable (>60%), and the HPLC analysis showed that it is the original compound, racemic [99mTc]2 (>98% pure). The distribution of the purified peak A and peak B was determined in the same tumor bearing mice at 4 hr post iv injection. The tumor uptake was similar for both isomers, but the blood and peripheral tissue content for the isomer in peak B was higher than that for the isomer in peak A. It is evident that the isomer in peak A displayed significantly better tumor/blood and tumor/muscle ratios. The higher rate of in vivo metabolism was also confirmed by the higher thyroid uptake values for the isomer in peak B as compared to peak A. In summary, a 99mTc-labeled sigma receptor imaging agent, [99mTc]2, has demonstrated the feasibility of using a 99mTc-labeled agent for imaging sigma receptor expression in tumor cells. This is the first time a subtype-selective 99mTc-labeled agent for imaging sigma receptor sites is reported.

Nitroimidazoles and hypoxia imaging: synthesis of three technetium-99m complexes bearing a nitroimidazole group: biological results.

Several Tc-99m complexes were synthesized, substituted with a nitroimidazole group, in order to visualize hypoxic tissues. The complexes were tested on rats (isolated hearts) and showed no significant uptake under hypoxic conditions.

Chemotactic peptide uptake in acute pancreatitis: correlation with tissue accumulation of leukocytes.

Chemotactic peptides bind specifically to receptors on leukocyte membranes. This property makes them prospective vehicles to evaluate inflammation and infection. We used two well-established models of acute pancreatitis to quantitate the binding of the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine-lysine (fMLFK) to leukocytes and its correlation to degree of organ inflammation. Uptake of the (99m)Tc-labeled nicotinyl hydrazine-derivatized chemotactic peptide analog fMLFK-HYNIC was measured in blood, pancreas, lung, and muscle specimens in rats with edematous or necrotizing pancreatitis and was compared with neutrophil sequestration assessed by myeloperoxidase activity and histology. Chemotactic peptide uptake in the pancreas was increased in mild and severe pancreatitis compared with controls, with higher levels in severe than in mild disease, and correlated with tissue myeloperoxidase activity (r = 0.7395, P < 0.001). Increased pulmonary uptake only in severe pancreatitis reflected pancreatitis-induced neutrophil sequestration in the lungs. Muscle uptake was unchanged compared with controls. Edema formation did not affect chemotactic peptide uptake. The data suggest that uptake of chemotactic peptides can contribute to quantitative assessment of neutrophils in localized inflammatory processes and is independent of associated edema formation or microcirculatory compromise.

Lung clearance of intratracheally instilled 99mTc-tobramycin using pulmonary surfactant as vehicle.

1. The use of pulmonary exogenous surfactant as a vehicle for intratracheally administered antibiotics to improve local antimicrobial therapy has been proposed. The present study investigated lung clearance rates in the rat of intratracheally instilled technetium labelled tobramycin with and without the addition of surfactant to the antibiotic solution. 2. The influence of surfactant on 99mTc-tobramycin lung clearance rates was studied dynamically with a gamma-camera in anaesthetized spontaneously breathing animals and in mechanically ventilated animals. 3. The results show that instillation of 99mTc-tobramycin with use of surfactant as vehicle significantly increases 99mTc-tobramycin lung clearance compared to instillation of 99mTc-tobramycin solution alone (P=0.006 between the two spontaneously breathing groups of animals and P=0.02 between the two ventilated groups of animals, ANOVA for repeated time measurements). The half life (t1/2) of composite clearance curves in spontaneous breathing animals was 147 min for animals receiving 99mTc-tobramycin versus 61 min for animals receiving 99mTc-tobramycin with surfactant. In mechanically ventilated animals this was 163 min versus 51 min, respectively. 4. It is concluded that exogenous surfactant, used as vehicle for intratracheally instilled 99mTc-tobramycin, increases lung clearance rate of 99mTc-tobramycin in rats.

In vivo stability and metabolism of 99Tcm-labelled anti-CD4 monoclonal antibodies and Fab' fragments.

In a comparative study, the in vivo metabolic profile of 99Tcm-anti-CD4 monoclonal antibodies (MAb) and Fab' fragments (direct thiol-reduction method) was investigated in rats with adjuvant arthritis. Plasma samples were obtained 1, 4 and 15 h following intravenous injection and urine was collected over 15 h. The composition of the radiolabelled molecules was analysed by gel filtration chromatography. The profile of the complete MAb was as follows. (1) Serum: a predominant peak of 150 kDa (complete MAb; approximately 80%); three minor peaks of 125, 100 and 50 kDa (presumably H2L1, H2 and H1 chains; 14%); and two small peaks of approximately 1500 and 300 Da (presumably 99Tcm-glutathione and Cys-99Tcm-Cys; 5%). (2) Urine: minor peaks of 125, 100 and 50 kDa (15%), major peaks of 1500 and 300 Da (50%), and an additional 25-kDa peak (30%). The profile of the Fab' was as follows. (1) Serum: three minor peaks of 150 kDa [conceivably F(ab')2 plus soluble-CD4], 110 kDa [F(ab')2] and 95 kDa (Fab' plus soluble-CD4; together 30%); a predominant peak of 55 kDa (Fab'; 61%); and two minor peaks of 1500 and 300 Da (8%). (2) Urine: predominantly a 55 kDa (16%) and 1500 and 300 Da peaks (74%). Also, the anti-CD4 Fab' showed higher urine excretion and lower plasma levels than the complete anti-CD4 MAb, but still more favourable tissue-to-blood ratios following scintigraphy of the arthritic joints. Thus, the complex metabolic profile of the anti-CD4 Fab' does not appear to interfere with specific targeting of the inflamed synovial membrane.

Uptake of cationic technetium complexes in cultured human carcinoma cells and human xenografts.

We evaluated lipophilicity, in vitro cell accumulation, and biodistribution of a series of 99mTc-ether isonitrile complexes to determine whether increased lipophilicity promotes extraction by tumor or enhances imaging properties of the radiopharmaceutical. Nine 99mTc-sestamibi analogs were synthesized and their lipophilicity was determined. Net cellular accumulation and membrane-potential-independent uptake were quantitatively compared in cultured human colon, breast, and lung carcinoma cells. The biodistribution of [99mTc-(2-methoxy-2-ethyl-isocyanopropane)6]+ (99mTc-MMBI) and [99mTc-(2-ethoxy-2-methyl-1-isocyanopropane)6]+ (99mTc-EIBI) was studied in nude mice using subcutaneous, subrenal capsule, and hepatic tumor xenografts. Accumulation of these compounds in colon cells correlated with increasing lipophilicity. Compared with 99mTc-sestamibi, 99mTc-EIBI exhibited (i) in colon cells both higher net accumulation and a higher specific/nonspecific uptake ratio; (ii) in all three cell lines higher membrane-potential-dependent accumulation; and (iii) in all subcutaneous tumor xenografts and in colon subrenal capsule and hepatic tumor xenografts higher tumor/background ratios.

Evaluation of 99mtechnetium-radiopharmaceutical binding to blood elements using different trichloroacetic acid concentrations.

Secure determination of the binding of 99mTc-radiopharmaceuticals to plasma (P) and blood cell (BC) constituents can help to understand the biodistribution of radiophamaceuticals. The reported precipitation studies of blood with radiopharmaceuticals have shown that the results can not be easily compared between studies. We decided to determine the "gold standard" concentration of trichloroacetic acid (TCA) to evaluate the binding to blood elements for several radiopharmaceuticals used in routine nuclear medicine. We have studied phytic (99mTc-PHY), diethylenetriaminepentaacetic (99mTc-DTPA), glucoheptonic (99mTc-GHA) and dimercaptosuccinic (99mTc-DMSA) acids. Blood was incubated with radiopharmaceuticals, centrifuged and P and BC separated. Samples of P and BC were also precipitated with TCA concentrations (20.0, 10.0, 5.0, 1.0, 0.5 and 0.1 percent) and soluble (SF) and insoluble fractions (IF) were isolated. The percent radioactivity (percent rad) in IF-P depends on TCA concentration. It varied from 36.4 to 65.0 (99mTc-PHY), from 17.9 to 32.0 (99mTc-DTPA), from 11.5 to 38.8 (99mTc-GHA) and from 52.8 to 66.2 (99mTc-DMSA). The results for the binding of 99mTc-PHY to IF-P show that there was no differences in the percent rad when TCA concentrations of 0.1 to 1.0 percent were used. For 99mTc-DTPA, 5.0 percent is the best TCA concentration. For 99mTc-GHA, low values of percent rad bound to IF-P is found with TCA concentrations of 0.1, 0.5 and 1.0. Interestingly, with 99mTc-DMSA, high values of bound radioactivity are not dependent on TCA concentrations (0.1 to 10.0). Radioactivity in IF-BC depends on TCA concentration and it varied for 99mTc-PHY (80.1 to 54.1) and for 99mTc-GHA (85.5 to 61.7). With 99mTc-DTPA and with 99mTc-DMSA the percent rad in IF-BC seems independent of TCA concentration. We suggest that the evaluation of the binding of the various 99mTc-radiopharmaceuticals to blood constituents, using only one TCA concentration, should be avoided.

Somatostatin receptor-binding peptides labeled with technetium-99m: chemistry and initial biological studies.

The synthesis of peptides which possess a high affinity for the somatostatin receptor and contain a chelator for the radionuclide technetium-99m is described. The target compounds were designed such that they would form stable, oxotechnetium(V) chelate complexes in which the Oxorhenium(V) chelate complexes of these peptides were prepared as nonradioactive surrogates for the technetium complexes. Peptide oxorhenium complexes and Tc-99m complexes eluted closely upon HPLC analysis. The receptor-binding affinities of both the free and rhenium-coordinated species were measured in vitro. The binding affinities of the free peptides (Ki's in the 0.25 - 10 nM range) compared favorably with [DTPA]octreotide (Ki = 1.6 nM), which, as the indium-111 complex, is already approved for somatostatin receptor (SSTR)-expressing tumor imaging in the United States and Europe. Furthermore, the rhenium-coordinated peptides had binding affinities which, in many cases, were higher than those of the corresponding free peptides, with several complexes having a Ki's of 0.1 nM. Some of the more potent SSTR-binding peptides were labeled with technetium-99m and assessed in an in vivo study with tumor-bearing rats. The 99m Tc-labeled peptides prepared in this study should be useful as SSTR-expressing tumor-imaging agents due to their high SSTR-binding affinities, ease of preparation, and, because they are low molecular weight peptides, expected pharmacokinetics characterized by rapid tracer excretion from the body resulting in high-contrast images.

Thrombus imaging using technetium-99m-labeled high-potency GPIIb/IIIa receptor antagonists. Chemistry and initial biological studies.

Platelet-specific compounds which are radiolabeled with gamma-emitting radionuclides may be particularly useful for the noninvasive in vivo detection of thrombi. The synthesis of peptides which are potent inhibitors of platelet aggregation and which contain a chelator for the radionuclide technetium-99m are described. The target compounds were designed such that stable, oxotechnetium(V) species could be prepared where the site of metal coordination was well defined. A strategy was employed where the pharmacophore-Arg-Gly-Asp-(RGD), or RGD mimetic, was constrained in a ring which was formed by the S-alkylation of a cysteine residue with an N-terminal chloroacetyl group. Binding affinities were enhanced by the replacement of arginine with the arginine mimetics S-(3-aminopropyl)cysteine and 4-amidinophenylalanine. Further enhancements could be obtained by the synthesis of oligomers which contained two or more rings containing receptor binding regions. The increase in binding affinity seen was more than that expected from a simple stoichiometric increase of pharmacophore. The most potent compounds described had IC50s of approximately 0.03 microM for the inhibition of human platelet aggregation. Two of the more potent peptides (P280 and P748) were labeled with technetium-99m and assessed in a canine thrombosis model. The 99m Tc complexes of the peptides prepared in this work hold promise as thrombus imaging agents due to their high receptor binding affinity, ease of preparation, and expected rapid pharmacokinetics.

Bis(dithiocarbamato) nitrido technetium-99m radiopharmaceuticals: a class of neutral myocardial imaging agents.

UNLABELLED: The synthesis and biodistribution in various animal models (rat, dog, pig and monkey) of 99mTc radiopharmaceuticals containing the Tc = N multiple bond are reported. METHODS: The complexes are represented by the general formula 99mTcN(L)2, where L is the monoanionic form of a dithiocarbamate ligand of the type [R1(R2)-N-C(=S)S]-, and R1 and R2 are variable, lateral groups. The preparations were carried out, both as a liquid and freeze-dried formulation, through a simple procedure involving the initial reaction of [99mTcO4]- with S-methyl N-methyl dithiocarbazate [H2NN(CH3)C(=S)SCH3], in the presence of tertiary phosphines or Sn2+ ion as reductants, followed by the addition of the sodium salt of the ligand (NaL) to afford the final product. The chemical identity of the resulting complexes was determined by comparing their chromatographic properties with those of the corresponding 99Tc analogs characterized by spectroscopic and x-ray crystallographic methods. The complexes are neutral and possess a distorted, square pyramidal geometry. RESULTS: No decomposition of the complexes, in physiological solution, was observed over a period of 6 hr. Imaging and biodistribution studies demonstrated that these radiopharmaceuticals localize selectively in the myocardium of rats, dogs and primates, but that they failed to visualize the pig heart. The kinetics of heart uptake and clearance were studied in rats and dogs, and found to be strongly influenced by variation of the lateral R1 and R2 groups. CONCLUSION: The high quality of myocardial images obtained in dogs and monkeys demonstrates that the derivative 99mTcN[E-t(EtO)NCS2]2 [99mTcN(NOEt)] exhibits the most favorable distribution properties for further studies in humans.