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UNLABELLED Tissue factor (TF), a transmembrane glycoprotein that acts as an essential cofactor to factor VII/VIIa, initiates the exogenous blood coagulation cascade leading to thrombin generation and subsequent thrombus formation in vivo. TF expression is closely related to plaque vulnerability, and high TF expression is shown in macrophage-rich atheromatous lesions, making TF a potential target for detecting atheromatous lesions in vivo. Thus, we prepared (99m)Tc-labeled anti-TF-monoclonal antibody (TF-mAb) IgG as a molecular probe and evaluated its usefulness to achieve TF-specific imaging using myocardial infarction-prone Watanabe heritable hyperlipidemic (WHHLMI) rabbits. METHODS Anti-TF-mAb was created using a standard hybridoma technique and was labeled by (99m)Tc with 6-hydrazinonicotinic acid (HYNIC) as a chelating agent to obtain (99m)Tc-TF-mAb. The immunoreactivity of HYNIC-TF-mAb was estimated by flow cytometry. WHHLMI and control rabbits were injected intravenously with (99m)Tc-TF-mAb. Twenty-four hours after the injection, the aorta was removed and radioactivity was measured. Autoradiography and histologic studies were performed using serial aorta sections. Subclass matched antibody (IgG(1)) was used as a negative control. RESULTS HYNIC-TF-mAb showed 93% immunoreactivity of the anti-TF-mAb. The radioactivity accumulation in WHHLMI aortas was 6.1-fold higher than that of control rabbits. Autoradiograms showed a heterogeneous distribution of radioactivity in the intima of WHHLMI aortas. Regional radioactivity accumulation was positively correlated with TF expression density (R = 0.64, P < 0.0001). The highest radioactivity accumulation in percentage injected dose × body weight/mm(2) × 10(2) was found in atheromatous lesions (5.2 ± 1.9) followed by fibroatheromatous (2.1 ± 0.7), collagen-rich (1.8 ± 0.7), and neointimal lesions (1.8 ± 0.6). In contrast, (99m)Tc-IgG(1) showed low radioactivity accumulation in WHHLMI aortas that was independent of the histologic grade of lesions. CONCLUSION The TF-detecting ability and preferential accumulation in atheromatous lesions of (99m)Tc-TF-mAb were demonstrated, indicating its potential for selective imaging of macrophage-rich atheromatous lesions in vivo.

Nanobodies are a novel type of immunoglobulinlike, antigen-binding protein with beneficial pharmacologic and pharmacokinetic properties that are ideally suited to targeting cellular antigens for molecular imaging or therapeutic purposes. However, because of their camelid, nonhuman origin, the possible immunogenicity of Nanobodies when used in the clinic is a concern. Here we present a new strategy to quickly generate humanized Nanobodies for molecular imaging purposes. METHODS: We genetically grafted the antigen-binding loops of NbCEA5, a Nanobody with specificity for the colon carcinoma marker carcinoembryonic antigen (CEA), onto the framework of a humanized Nanobody scaffold. This scaffold has been previously characterized in our laboratory as a stable Nanobody that can serve as a universal loop acceptor for antigen-binding loops from donor Nanobodies and has been additionally mutated at about 10 crucial surface-exposed sites to resemble the sequence of human variable immunoglobulin domains. The 3 recombinant Nanobodies (NbCEA5, humanized scaffold, and humanized CEA5 graft) were produced in bacteria and purified. Unlabeled and (99m)Tc-labeled Nanobodies were biochemically characterized in vitro and tested as probes for SPECT/CT of xenografted tumors. RESULTS: The success of loop-grafting was confirmed by comparing these Nanobodies for their capacity to recognize soluble CEA protein in enzyme-linked immunosorbent assay and by surface plasmon resonance and to bind to CEA-positive LS174T colon carcinoma cells and CEA-transfected but not untransfected Chinese hamster ovary cells in flow cytometry. Specificity of binding was confirmed by competition studies. All Nanobodies were heat-stable, could be efficiently labeled with (99m)Tc, and recognized both soluble and membrane-bound CEA protein in binding studies. Finally, biodistribution experiments were performed with intravenously injected (99m)Tc-labeled Nanobodies in LS174T tumor-bearing mice using pinhole SPECT/micro-CT. These in vivo experiments revealed specificity of tumor targeting and rapid renal clearance for all Nanobodies, with low signals in all organs besides the kidneys. CONCLUSION: This study shows the potency of antigen-binding loop-grafting to efficiently generate humanized Nanobodies that retain their targeting capacities for noninvasive in vivo imaging of tumors.

This study on a rat model of grade II chondrosarcoma aimed to determine whether the radiotracer N-(triethylammonium)-3-propyl-[15]ane-N5 radiolabeled with 99mTc (99mTc-NTP 15-5), which binds to cartilage proteoglycans, has pathophysiologic validity for in vivo imaging of cartilage tumoral tissue. Methods: We used 2 experimental approaches with the Swarm chondrosarcoma rat model: that is, a primary paratibial location and local recurrence after intralesional curettage. 99mTc-NTP 15-5 scintigraphy and 99mTc-hydroxymethylenediphosphonate (99mTc-HMDP) scanning were performed at regular intervals during 50 d after tumor implantation in a paratibial location (primary model; n = 12 animals) and after intralesional curettage in a femoral condyle location (recurrence model; n = 9 animals). For each animal, positive scans were analyzed at each time point using the target-to-background ratio (TBR), with the target region of interest delineated over the tumor and the background region of interest over muscle. In each model, the TBR time course was followed against primary tumoral growth or recurrence. Tumor volume was monitored for 2 mo by measuring the 2 perpendicular diameters. At study end, animals were sacrificed for histopathologic analysis. Results: For both models, 99mTc-NTP 15-5 scans showed tracer accumulation at the site of implantation or curettage. For the primary tumor model, the mean TBR was 1.6 ± 0.14 by day 4 after implantation and increased over time as the disease progressed, with a mean TBR of 4.25 ± 0.25 on day 45. For the recurrence model, mean TBR was 3.27 ± 0.24 by day 4 after curettage and increased with recurrence, with a mean value of 5.25 ± 0.49 on day 50. 99mTc-HMDP bone scans were negative for both models throughout the study; at a later stage of the study, an area of 99mTc-HMDP accumulation was seen in the diaphysis of the bone adjacent to the tumor and was attributed to remodeling. Conclusion: These experimental results in 2 preclinical models of grade II chondrosarcoma bring forward data in favor of 99mTc-NTP 15-5 radiotracer for imaging primary growth of chondrosarcoma and its local recurrence after surgery.

Studies have demonstrated that the bivalent (111)In-labeled leukotriene B4 (LTB4) antagonist DPC11870 reveals infectious and inflammatory lesions in various rabbit models. The radioactive tracer accumulates quickly at the site of infection and clears rapidly from the circulation, resulting in high-quality images. In this study, 2 new hydrazinonicotinamide (HYNIC)-conjugated compounds that are structurally related to DPC11870 were studied to further improve image quality.A bivalent HYNIC-conjugated LTB4 antagonist (MB81) and a monovalent one (MB88) were labeled with (99m)Tc. The radiolabeled compounds were intravenously injected into New Zealand White rabbits with E. coli infection in the left thigh muscle. The imaging characteristics of both compounds were compared with those of the bivalent (111)In-labeled LTB4 antagonist.Both (99m)Tc-labeled LTB4 antagonists revealed the abscess from 2 h after injection onward. Abscess uptake at 8 h after injection was similar for both compounds (0.22 +/- 0.08 percentage injected dose per gram [%ID/g] and 0.36 +/- 0.13%ID/g for the bivalent and monovalent compounds, respectively). However, visualization of the abscess and the quality of the images were better after injection of MB88 than after injection of either of the bivalent LTB4 antagonists. The excellent delineation of the abscess by MB88 was mainly due to the more rapid clearance of this compound from nontarget organs.The (99m)Tc-labeled HYNIC conjugated LTB4 antagonists MB88 and MB81 revealed infectious foci in rabbits within a few hours after injection. Imaging characteristics of monovalent (99m)Tc-MB88 were superior to those of the bivalent LTB4 antagonists DPC11870 and MB81. Therefore, of the 3 LTB4 antagonists, the monovalent LTB4 antagonist MB88 is the most potent and promising agent for visualizing and evaluating infection and inflammation in patients.

In tumors the process of apoptosis occurs over an interval of time after chemotherapy. To determine the best timing for detecting apoptosis in vivo with (99m)Tc-annexin V after chemotherapy, we examined the changes in (99m)Tc-annexin V accumulation over time in comparison with those of caspase-3 and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) expression level after cyclophosphamide treatment in an experimental model.Hydrazinonicotinamide (HYNIC)-annexin V was labeled with (99m)Tc ((99m)Tc-annexin V). Rats were inoculated with allogenic hepatoma cells (KDH-8) into the left calf muscle. Eleven days after the inoculation, the rats were randomly divided into the group receiving a single dose of cyclophosphamide (150 mg/kg intraperitoneally) and the control group. (99m)Tc-Annexin V (18.5 MBq [0.5 mCi] per rat) was injected intravenously in the rats 4, 12, and 20 h after the treatment and also to the control rats (n = 5 in each group). Radioactivity in tissues was determined 6 h after (99m)Tc-annexin V injection. Immunostaining of caspase-3 and TUNEL were performed to detect apoptosis, and the rates of positively stained cells were calculated.(99m)Tc-Annexin V accumulation in tumors significantly increased at 20 h (0.077 +/- 0.007 [%ID/g] x kg, where %ID/g = percentage injected dose per gram) but not at 4 or 12 h (0.048 +/- 0.008 and 0.052 +/- 0.014 [%ID/g] x kg, respectively) after cyclophosphamide treatment. (99m)Tc-Annexin V accumulation in tumors and the rate of apoptotic cells determined by caspase-3 immunostaining and TUNEL were significantly higher in treated rats 20 h after cyclophosphamide treatment as compared with control rats.The effective detection of apoptotic tumor response with (99m)Tc-annexin V required 20 h after cyclophosphamide treatment in an experimental model. The present results provide an important basis for determining the best timing of annexin V imaging after the start of chemotherapy in a clinical setting.

Detection of a new or recurrent breast cancer lesion relies on physical examination and imaging studies, primarily mammography, followed by histopathologic evaluation of biopsy tissue for morphologic confirmation. Approximately 66%-85% of detected lesions are not malignant. Therefore, biopsies are unnecessary for at least two thirds of patients. Human estrogen receptor-positive breast cancer cells typically display an elevated level of cyclin D1 protein because of the overexpression of CCND1 messenger RNA (mRNA) and an elevated level of insulin-like growth factor 1 (IGF1) receptor (IGF1R) because of the overexpression of IGF1R mRNA. We hypothesized that scintigraphic detection of CCND1 peptide nucleic acid (PNA) hybridization probes with a (99m)Tc-chelating peptide on the N terminus and an IGF1 peptide loop on the C terminus could detect CCND1 mRNA in human MCF7 breast cancer xenografts in nude mice from outside the body.We prepared the CCND1 probes as well as mismatched controls by solid-phase synthesis. We used fluorescence microscopy to detect the cellular uptake of fluoresceinyl probes and quantitative reverse transcription-polymerase chain reaction to detect the hybridization of probes to mRNA. We imaged (99m)Tc-probes in MCF7 xenografts scintigraphically and measured distribution by scintillation counting of dissected tissues.IGF1R-overexpressing MCF7 cells internalized the fluorescein-chelator-CCND1 PNA-IGF1 peptide but not the mismatched control peptide. The chelator-CCND1 PNA-IGF1 peptide but not the control peptide lowered the level of cyclin D1 protein in IGF1R-overexpressing MCF7 xenografts in nude mice after intratumoral injection. IGF1R-overexpressing MCF7 xenografts in nude mice were visualized at 4, 12, and 24 h after tail vein administration of the (99m)Tc-CCND1 antisense probe but not the control probe. (99m)Tc-chimeras were distributed normally in the kidneys, liver, tumors, and other tissues.Cancer gene activity can be detected from outside the body by probing with radionuclide-chelator-PNA-peptide chimeras.

99mTc-Labeled white cell scintigraphy (WCS) has been used for the investigation of inflammatory bowel disease (IBD) in adults, but data on children are limited. The most common agent used is (99m) Tc-hexamethylpropyleneamine oxime (HMPAO); however, this agent has limitations. In a retrospective study, we assessed the use of (99m)Tc-stannous colloid WCS for the initial evaluation of children with suspected IBD.Diagnostic, endoscopic, and contrast radiography results were retrospectively collected from the medical records. Two experienced nuclear physicians unaware of the patient data interpreted the WCS results, with agreement reached by consensus. Statistical analysis was performed on the ability of WCS to detect active disease and localize it topographically and on a comparison of diagnostic methods, using a combination of clinical features and endoscopy as the reference standard.Between 1996 and 1999, 64 patients (35 male and 29 female; mean age, 12.5 y; age range, 2-19 y) had WCS performed, with IBD subsequently diagnosed in 34 patients. (99m)Tc-Stannous colloid WCS had an 88% sensitivity, 90% specificity, and 8.8 likelihood ratio for initial investigation of IBD. Agreement was poor for topographic localization of disease. Small-bowel series had a 75% sensitivity, 50% specificity, and 1.5 likelihood ratio for detecting endoscopic disease of the terminal ileum and proximal colon.Our results confirm that WCS is a useful imaging technique for the initial evaluation of patients with suspected IBD. (99m)Tc-Stannous colloid had results at least comparable to those of other WCS agents, and in children, (99m)Tc-stannous colloid WCS should be preferred in view of lower cost, shorter preparation time, and the smaller blood volumes required.

Lymphoscintigraphy allows functional assessment of lymphatic transport and depiction of regional lymph nodes, is fast and nontraumatic and has no known side effects. We retrospectively analyzed lymphoscintigraphic studies to determine their efficacy in the investigation of chyluria, chyloperitoneum and chylothorax.Twenty-one whole-body lymphoscintigrams using 99mTc-antimony sulfide colloid or dextran were acquired in 18 patients with chyluria, chyloperitoneum and/or chylothorax. The images were reviewed to assess the rate of tracer transport and number, size and distribution of lymph vessels and nodes as well as the presence of collateral, fistula or lymph reflux.Lymphoscintigraphy was normal (5 of 11 patients) or showed lymphatic obstruction (6 of 11 patients) in chyluria associated with filariasis. Lymphatic obstruction was demonstrated in chyloperitoneum and/or chylothorax associated with liver cirrhosis (2 patients), postoperative (1 patient) or congenital (1 patient) lymphatic dysplasia, inferior vena cava obstruction (1 patient) and nephrotic syndrome (1 patient). Enhanced lymph flow was seen in systemic lupus erythematosus (1 patient). Follow-up lymphoscintigrams showed patency of lymphovenous anastomosis (1 patient), improvement (1 patient) or no change (1 patient) in lymphatic drainage after treatment.Lymphoscintigraphy can demonstrate abnormal lymphatic drainage in chyluria, chyloperitoneum and chylothorax. It is useful for selecting patients for surgery and assessing the effect of treatment.

Lymphoscintigraphy with 99mTc-antimony sulphide colloid was performed on patients with cutaneous melanoma of the back to define draining node fields and sentinel nodes before surgery.One patient was found to have drainage from the back to sentinel lymph nodes in the triangular intermuscular spaces bilaterally, above and lateral to the scapula. Subsequently, drainage to this node field has been found in 26% of 42 consecutive patients who have had lymphoscintigraphy performed for melanoma on the back.When performing lymphoscintigraphy to locate draining node fields and sentinel nodes in patients with melanoma on the back, it is important to look for drainage to the triangular intermuscular space node field by obtaining posterior and lateral scans. Any sentinel lymph nodes found in this field should be marked prior to surgery in the same way as nodes in other node fields are delineated so that they may be removed at surgery.

We present a case in which a patient with primary intestinal lymphangiectasia demonstrated abnormal intestinal accumulation of tracer during 99mTc-methylene diphosphonate (MDP) skeletal scintigraphy. Early intestinal leakage with gradual colonic migration and concentration was confirmed by repeat bone scan with serial acquisitions. The mechanism for the intestinal localization of 99mTc-MDP seen in this patient is not clear. Thus, intestinal lymphangiectasia can be a cause for extra-osseous localization of bone scan agents in the intestine.

Several 99mTc-labeled radiopharmaceuticals have been developed for lymphoscintigraphy of the extremities. In the United States, however, these agents are not widely used clinically. This study evaluates the use of smaller particle sizes (0.1 micron) of 99mTc-sulfur colloid (99mTc-SC) for lymphoscintigraphy.The 99mTc-SC was prepared by kit, and the final preparation was filtered through a sterile 0.1-micron filter. The radiochemical purity (RCP) of the filtered 99mTc-SC was determined before administration. Nineteen patients with suspected lymphedema were injected with 18.5 MBq (500 muCi) filtered 99mTc-SC intradermally in each foot, and whole-body images were obtained immediately and 1, 3, 6 and 24 hr later. Local views over the inguinal or axillary lymph nodes were also obtained every 5 min for the first hour.The average RCP value was 93.4% +/- 4.2% (n = 19), and the RCP difference pre- and postfiltration of the 99mTc-SC preparation was -1.7% +/- 1.4% (n = 40). Evaluation of the particle size with the polycarbonate filter showed that 89.9% +/- 4.5% (n = 28) of particles were less than 50 nm, and the particle size was further determined by electron microscopy to be 38.0 +/- 3.3 nm (n = 202). The mean particle sizes of two peaks measured by laser light scattering techniques were 7.5 and 53.9 nm (major peak). Clinical studies with filtered 99mTc-SC demonstrated similar lymphoscintigrams compared with those obtained with 99mTc antimony sulfide colloid (99mTc-ATC). Filtered 99mTc-SC showed a faster transport rate to the inguinal lymph nodes and lower radiation dosimetry for liver, spleen and whole body compared with 99mTc-ATC.Filtered 99mTc-SC can be easily prepared and is readily available for routine clinical use in lymphoscintigraphic studies.

Lymphoscintigraphy has previously been used to define lymph drainage patterns and locate sentinel lymph nodes, prior to surgery, in patients with cutaneous melanoma. The aim of this study was to apply this technique to patients with breast cancer using intramammary injections placed around the primary tumor in the breast.Lymphoscintigraphy using 99mTc-labeled antimony sulphide colloid was performed in 34 patients with a suspected primary breast cancer. Images were recorded immediately and at 2.5 hr using a LFOV digital gamma camera. Sentinel lymph node location was marked when possible.Lymphatic drainage patterns were successfully recorded in all but three patients. Lymph drainage was to the axillary, internal mammary, supraclavicular and, in one patient, infraclavicular node fields in various combinations but always on the same side of the body as the breast tumor. There was unexpected drainage across the center line of the breast to axillary or internal mammary nodes in 32% of patients with inner or outer quadrant lesions. Direct drainage to supraclavicular or infraclavicular nodes occurred in 20% of upper quadrant lesions. Drainage to the ipsilateral axilla occurred in 85% of patients, where a single sentinel node was seen in all cases.Intramammary lymphoscintigraphy can be used to define the lymphatic drainage patterns of individual breast cancers. The surface location of sentinel lymph nodes in the draining node fields can be marked and in the axilla their depth can be measured. It should therefore be possible to use lymphoscintigraphy, along with a blue dye injection technique or the gamma probe at surgery, to locate sentinel lymph nodes in patients with breast cancer.

Interpretation of the radionuclide hip arthrogram may present difficulty because of a lack of anatomical reference information. Additional transmission images to determine tracer localization may facilitate scan interpretation.Isotope arthrography (20 MBq 99mTc-tin colloid and 57Co transmission imaging) was prospectively performed on 21 patients with painful hip prostheses and suspected stem loosening.The radionuclide arthrogram was positive in 10 patients and negative in 9 patients. Extravasation of tracer, confirmed by transmission images, resulted in two nondiagnostic studies. Surgery was undertaken in 10 patients and loosening was confirmed in 6 patients. In this surgical subgroup, the scan was true-positive in six patients, true-negative in two patients, false-positive in one patient and nondiagnostic in one patient.The combination of radionuclide arthrography and transmission imaging facilitates scan interpretation and is a recommended method for investigating suspected loosening of the femoral stem.

The synthesis and biodistribution in various animal models (rat, dog, pig and monkey) of 99mTc radiopharmaceuticals containing the Tc = N multiple bond are reported.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.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.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.

A 9 cm-lesion of telangiectatic focal nodular hyperplasia was incidentally identified in a 31-yr-old female. Despite a typical appearance by X-ray computed tomography and ultrasonography, scintigraphy with technetium-99m-(99mTc) colloid, 99mTc-diethyliminodiacetic acid, and 99mTc-labeled red cells failed to demonstrate any abnormalities. These findings are felt to reflect the relative lack of architectural disruption that histologically characterizes this particular lesion. The present report described the imaging characteristics of the telangiectatic form of focal nodular hyperplasia.

We present the case of an infant with a cystic hygroma investigated by lymphoscintigraphy. The source of lymph flowing into the hygroma was identified as were some ectatic lymphatics feeding it. Lymph flow was very rapid. The implications for therapy are discussed. Lymphoscintigraphy can assess many aspects of lymph flow not accessible by other means.

Sixty-six percent of 54 patients with neuroblastoma demonstrated uptake of bone-seeking radioagents by the primary tumor. This is a higher incidence than previously reported. Uptake was slightly more common in abdominal than thoracic tumors. There was a significant correlation between the size of the tumor and tracer uptake. Calcification was demonstrated in the primary tumor in almost 90% of the 54 patients. This is a much higher incidence of calcification than previously reported. Microscopy shows that the calcification is not always due to tumor necrosis; it also occurs in areas of viable tumor cells. Tracer uptake is believed to be related to calcium metabolism. The rate of metabolic activity rather than the total amount of calcium present within the tumor may be the most important factor in determining the amount of uptake. No significant relationship was found between tracer uptake and tumor stage or homovanillic acid and vanillylmandelic acid metabolic activity.

Three sets of thoraco-omphalopagous conjoined twins were investigated. The clinical findings indicated a complex shared heart in two sets, and separate cardiovascular systems in the other. These assessments were confirmed by dynamic imaging after bolus injection of Tc-99m(Sn)colloid or Tc-99m millimicrospheres. Static images were then used to establish the configurations of the shared livers. The results of these studies were in keeping with the angiographic and autopsy findings in the two sets with complex cardiac anomalies and with the surgical findings during successful separation of the third set.

Triple density gradients of metrizamide in plasma (MP) were used to characterize label distribution in human leukocyte preparations incubated with 99mTc tin colloids. Less than 50% of the cell-associated radioactivity was specifically bound to leukocytes when heparinized blood was rotated with stannous fluoride colloid ([Tc]SFC). Labeling efficiency in leukocyte rich plasma (LRP) averaged 44%, of which greater than 90% was specifically bound to leukocytes. MP-gradient analysis also revealed that leukocyte labeling did not occur with stannous chloride colloid, nor when citrate was present during rotation with [Tc]SFC. When citrate was added after labeling to "solubilize" unbound [Tc]SFC, radiocolloid was removed from the leukocytes, indicating that the mechanism of [Tc]SFC labeling is adherence rather than phagocytosis. Technetium-labeled neutrophils exhibited normal in vitro chemotaxis and no lung uptake in vivo. Technetium-labeled mononuclear leukocytes, on the other hand, exhibited prolonged lung transit in vivo. Neither [Tc]SFC cell preparation showed signs of in vivo reoxidation to pertechnetate.

A technique is described for the anterior and lateral imaging of the thorax during internal mammary lymphoscintigraphy. It permits reliable estimates of lymph-node location to within 3 mm of the actual location. Use of the results from these measurements can be directly applied to radiation portal planning.

Twenty-four-hour measurements of whole-body retention (WBR) of Tc-99m diphosphonate (a sensitive measure of skeletal metabolism) have been obtained in 250 healthy volunteer subjects. WBR values were found to fall from the age of 20 yr until 35 yr and then in men to rise linearly thereafter. Women showed a similar pattern initially but there was a marked rise in WBR corresponding to the menopausal years. Our results lend support to the belief that skeletal metabolism increases with age. It is suggested that some imbalance must always exist between resorption and formation in bone, with net loss of bone mineral, and increasing levels of skeletal metabolism will exaggerate this imbalance and accelerate the rate of bone loss.

A comparison of stannous phytate and antimony sulfide colloid, both labeled with Tc-99m, was conducted during the performance of internal mammary lymphoscintigraphy in 46 patients. Thirteen of these patients were randomized to receive both radiotracers in two consecutive studies. The results indicated a statistical difference between agents; Tc-99m antimony sulfide allowed visualization of a greater number of more intense nodes, better delineation of the total length of the internal mammary lymph-node chain, and a more consistent visualization of supraclavicular nodes. Although previously published animal data suggest utility of Tc-99m stannous phytate for lymph-node imaging, Tc-99m antimony sulfide was shown in this clinical comparison to provide a more reliable representation of lymph-node anatomy.

Radionuclide bone scan findings are described and correlated with pathology in 23 patients with giant cell tumor (GCT) of the bone. The degree of radionuclide activity was markedly increased in 20 (87%), minimally increased in three (13%), and decreased in none of the patients. Of the 23 patients with increased radioactivity, the pattern was diffuse in 11 (48%) and doughnut in 12 (52%). Extended patterns of radioactivity were present in 19 of 22 patients; however, none were associated with true tumor extension. Bone scanning did not aid in the detection of GCT, was nonspecific, and did not differentiate benign from malignant GCT. Although radioactivity extended beyond the radiographic abnormality in the majority of patients, this was most likely secondary to other bony abnormalities or local and/or regional hyperemia, and caution should be taken in ascribing this extension to either tumor or metastasis.

Uptake of Tc-99m di-isopropyliminodiacetic acid (DISIDA) by hepatocellular carcinoma was assessed in 30 patients showing obvious liver defects on a Tc-99m tin colloid image. In none of these patients was there complete "filling in" of the defects, and even partial "filling in" occurred in only 11 (36.7%). There was no uptake of Tc-99m DISIDA by the primary tumor in the remaining 19 patients (63.3%). In 19 of the 30 patients an attempt was made to correlate the degree of histologic differentiation of the tumor with the uptake of DISIDA by the tumor. No difference in uptake could be demonstrated between well, moderately, and poorly differentiated tumors. Tc-99m DISIDA was not taken up by pulmonary metastases in the only two patients tested. We conclude that imaging with Tc-99m DISIDA in conjunction with Tc-99m colloid is of no value in the specific diagnosis of hepatocellular carcinoma.

The role of lymphoscintigraphy, performed with 99mTc-labeled antimony sulfur colloid, in the diagnosis of lymphedema and as a test for selection of patients for microvascular operation was evaluated in 32 patients with primary and secondary lymphedema and four patients with other causes of leg edema. Lymphoscintigraphy clearly demonstrated if edema was of lymphatic origin. Five different image patterns were identified; abnormal image patterns could not be predicted from clinical history or physical findings. Quantitative evaluation of removal of the radioactive colloid from the injection site and appearance in lymph node sites and liver was of limited usefulness. Nine patients underwent various surgical procedures before or after lymphoscintigraphy. Lympho-venous anastomoses were possible only in patients who had patent lymph channels visible on lymphoscintigrams. Based on initial experience, lymphoscintigraphy seems to be useful to select patients for microvascular operation.

A quantitative kinetic technique using a scintillation camera has been developed for investigating lymph drainage and the uptake in the lymph nodes of 99mTcSb2S3 colloid injected subcutaneously. Twenty-two patients with primary malignant melanoma were examined. Lymph-node dissection was performed and 185 lymph nodes were individually measured for radioactivity. The kinetics of colloid uptake in individual nodes can be expressed by a simple two-compartment model. The outflow of colloid from the injection site was found to be monoexponential, and the tissue volume containing the injected colloid at the injection site increased asymptotically with time. A model has been developed for calculating absorbed doses at the injection site and in organs with colloid uptake. The following absorbed doses were estimated (muGy/MBq): whole body 0.7-4.5, gonads 0-22, liver 1.0-3.9, lymph nodes up to 1000 and injection site about 10,000. Possible biological effects in the skin and effective dose equivalents have been estimated when using other lymphoscintigraphic agents.

To determine the clinical significance of splenic uptake in bone scintigraphy and functional asplenia on the radionuclide liver-spleen image, bone and spleen scintigrams of 38 patients with sickle cell disease were reviewed. Eighteen underwent bone and liver-spleen studies, 15 had only bone images, and five had only liver-spleen studies. Sixteen of 33 who had bone scintigraphy showed splenic uptake, but the frequency of homozygous sickle cell (SS) disease was not greater than heterozygous sickle cell disease (S-hetero) in this group. SS patients with splenic uptake of Tc-99m diphosphonate had significantly fewer painful crises of the abdomen and extremities, and fewer inpatient and outpatient hospital visits than SS patients whose bone imaging did not visualize the spleen. Functional asplenia on liver-spleen images (16 cases) was seen only in SS disease. One SS patient, age 8, still had a spleen capable of phagocytizing colloid.

Stannous fluoride colloid (SFC) kits for instant radiolabeling with 99mTc were prepared and evaluated for suitability as a leukocyte radiolabeling agent. Technetium-99m labeling for kits stored at -15 degrees C for up to 3 mo was greater than 95% as determined by instant thin layer chromatography while colloid particles of 1-3 microns were measured by electron microscope for these preparations. Canine leukocyte preparations labeled with [99mTc]SFC and characterized by triple density gradients of metrizamide in plasma demonstrated an 83% leukocyte association. Analysis of labeled cell preparation for up to 3 hr demonstrated label stability. Labeled leukocytes, when readministered in normal dogs, demonstrated bi-exponential blood clearance with uptake and subsequent clearance from lung. There was increasing uptake of labeled leukocytes by the liver until steady state was achieved. Furthermore, when whole blood samples were analyzed by the triple density gradient method, an increasing monocyte-to-granulocyte ratio was observed to occur with time. By 3 hr 95% of the whole blood activity was associated with the leukocyte fraction. Dogs in which a 24-hr sterile abscess was created demonstrated elevated blood-pool activity as compared to control with localization of the labeled cells at inflammatory sites within 3 hr following cell readministration.

Technetium-99m antimony colloid was prepared in our laboratory for bone-marrow imaging. Optimal production of colloid particles of size range 1-13 nm was achieved by the use of polyvinylpyrrolidone of mol. wt. 44,000. Electron microscopy was used to size the particles. Studies in rabbits showed exclusive concentration in the subendothelial dendritic phagocytes of the bone marrow. Pseudopods from these cells were found to traverse interendothelial junctions and concentrate colloid from the sinusoids. Imaging studies of bone marrow in rabbits showed the superiority of the Tc-99m antimony colloid over the much larger colloidal particles of Tc-99m sulfur colloid. Tissue distribution studies in the rat confirmed that bone-marrow uptake of Tc-99m antimony colloid was greater than that of Tc-99m sulfur colloid, although blood clearance was much slower.

Imaging of the spleen of 10 patients who had been hematologically diagnosed with sickle-cell anemia (SCA) was studied with [99mTc]tin colloid and heat denatured [99mTc]RBCs. In all ten patients, there was faint or nonvisualization of the spleen with [99mTc]tin colloid. However, with heat denatured [99mTc]RBCs, nine spleens were well visualized, and the uptake was homogenous. One spleen had two patchy areas of uptake. The results indicate that when splenic phagocytic function is impaired as reflected by nonvisualization of the spleen with [99mTc]tin colloid, it is still possible to image such a spleen with heat denatured [99mTc]RBCs.

Intraoperative lymph scintigraphy during radical surgery for cervical cancer was developed in the course of a program covering three periods. During the last period technetium-99m antimony sulfide has been used to visualize pelvic lymph nodes. Surgery is done with a modified gamma camera serving as an operating table. This ensures intraoperative monitoring and greater thoroughness of lymphadenectomy. The introduction of the technique has improved the rate of total lymphadenectomies and has increased both the yields of involved nodes and the 3-yr survival rates.

Axillary lymphoscintigraphy (AxLS) with bilateral interdigital injection of [99mTc]antimony sulfide colloid carried out concurrently with internal mammary lymphoscintigraphy in 488 patients with breast carcinoma was evaluated. Patterns of radiocolloid distribution within the ipsilateral axilla and supraclavicular fossa were compared with similar features on the contralateral side to determine whether image characteristics are significantly disrupted by prior surgery, reflect the presence of metastases, and can predict treatment failure. Interpretive criteria for AxLS were refined after correlation of the identified image components with clinical parameters including axillary surgery, lymph node histology and relapse within a follow-up period of 2 years from the study. Results indicate that AxLS is at least as accurate as clinical assessment and provides data predictive of relapse to complement axillary lymph node status although the technique cannot presently replace lymph node sampling for patient staging.

The isolated in vivo intestinal segment is a popular experimental preparation for the investigation of intestinal function, but its value has been limited because no method has been available for measuring changes in intraluminal volume under experimental conditions. We report a scintigraphic technique for measuring intraluminal volume and assessing intestinal motility. Between 30 and 180 ml, the volume of a 75-cm segment of canine jejunum, perfused with Tc-99m-labeled tin colloid, was found to be proportional to the recorded count rate. This method has been used to monitor the effects of the hormone vasopressin on intestinal function.

To achieve the visualization of regional lymph nodes using lymphoscintigraphy, 100 preoperative patients with breast cancer were studied, with [99mTc]rhenium colloid having been injected into the periosteum of their ribs. In order to identify the exact location of the visualized nodes, the obtained lymphoscintigram was superimposed onto the patient's chest roentgenogram. The visibility of the internal mammary region was 91% on the affected side, and 93% on the healthy side, whereas the visibility of the axillary region was 85% and 86%, respectively. The injection resulted in simultaneous visualization of both the internal mammary and the axillary nodes: in our series, it meant the visualization of 82 patients (82%) on the affected side and 83 patients (83%) on the healthy side. Our technique appears to be a rather efficient method for imaging the regional lymph nodes in breast cancer patients.

Recent studies suggest that 99mTc-labeled radiocolloid (SC) compounded with hydrogen sulfide can be used to visualize lymph channels and nodes. Our study prospectively compared SC with 99mTc antimony sulfide (SbS) colloid, in 28 patients undergoing internal mammary lymphoscintigraphy. Images were recorded on a scintillation camera and computer at 0.5, 1.0, and 3.0 hr. Quantitative analysis included assessment of percent (%) injected dose in nodes, the percent remaining at the injection site, and the relative intensity of the most cephalad node compared to a 57Co standard. The mean (means) % injected dose of both radiocolloids within visualized nodes was less than 1% at each time interval, with no significant differences between means's. The means % injected dose remaining at the injection site at 3.0 hr was 83 for SbS and 76 for SC not statistically significant (N.S.). The means of the ratio of counts within the most cephalad node at 3.0 hr to counts within a 57Co standard was 0.98 for SbS and 1.03 for SC (N.S.). Clinical assessment of number of nodes visualized and extent of radiocolloid migration showed no difference between the two agents. The biological and clinical parameters for the two colloids appear similar when used for internal mammary lymphoscintigraphy.

A catheter technique for injection of radiolabeled colloids into the myocardium was developed and tested in a series of 15 dogs. A multipurpose angiographic catheter was modified to permit an inner core of PE-50 polyethylene tubing, tipped with a 23-gage needle, to pass through the lumen for intra-myocardial injection of radiocolloids. For injection of the left ventricle, the catheter is introduced through the femoral artery: for the right ventricle, the femoral vein. The catheter advanced under fluoroscopy until the desired surface for injection is reached. The inner core is then extended to lodge the needle in the endocardium. A mixture of Renografin (to confirm the endocardial injection site) and radiolabeled colloid was injected in 13 animals. Ten minutes after injection, scintigraphy was begun and continued for up to 6 hr. In three dogs the procedure was repeated 3 or 4 times. From two to five nodes were visible in all animals, irrespective of whether the right or left ventricular myocardium was injected. In two animals the injection was given intravenously, and no nodes were seen. These data suggest that cardiac lymphatic drainage can be studied with a catheter injection method.