Functional Evaluation of an Ectopic Supernumerary Kidney in Pelvis.

BACKGROUND: Supernumerary kidney is an accessory organ with its own encapsulated parenchyma, blood vessels and ureters, either separated from the normal kidney or connected to it via fibrous tissue and ectopic kidney is a migration abnormality of the kidney. Here, we have evaluated a rare case of the supernumerary and ectopic kidney with DMSA, MAG3 and also CT fusion of the images. METHODS: The absolute divided renal function was calculated for each kidney by DMSA. The MAG3 scintigraphy showed no obstruction in the ureteropelvic junction. Furthermore, the renogram curve and Tmax and time to ½ values were assessed. Two months after the conventional scintigraphies, the patient was referred to a CT scan and the fusion of DMSA SPECT and CT data was generated on a workstation. RESULTS: The ectopic supernumerary kidney was functioning very well except a small hypoactive area, visible on DMSA, which was possibly a minimal pelvicalyceal dilatation. However, consequent CT scan did not show any pathology. CONCLUSION: It is important to evaluate particularly complicated or rare cases with multimodality systems with 3D or fusion techniques for the accurate diagnosis.

Formulation of lyophilized single vial kit of N-N-Ethylene-L-Dicysteine (EC) for labeling with 99mTc. II: Radiochemical and clinical evaluation as a renal tubular agent in comparison with 99mTc-MAG3.

A Technetium 99mTc labeled lyophilized single component kit of N-N-ethylene-I-dicysteine (EC) is developed to replace multiple step kit developed by others. The aim of study is to formulate a radionuclide that is easy to prepare, has rapid plasma clearance, produce high quality images and is an affective alternative to radioiodine labeled orthoiodohippurate, which has been remained the physiological 'gold standard' since long time. To achieve this goal, the systematically varied key parameters such as pH, the use of reducing agents, stabilizers and additives are optimized to obtain maximum radiochemical purity and optimum biodistribution in non human and human primates. Various pH levels of EC showed equally good results in animal experiments but only pH 10 was suitable for human use. Dynamic and renal Scintigraphic studies are carried out with 99mTc-EC at pH 8 in 12 volunteers and at pH 10 in 18 volunteers and compared with 99mTc-MAG3, Background ratios, renograms, relative renal function and semi quantitative parameters are available in all studies. The background ratios (mean ± SD) at 30th minute are 0229±0.024 and 0.236±0.018 for 99mTc-EC at pH 10 and 99mTc-MAG3 respectively. The mean ± standard error of mean (SEM) values of TMAX and time to half activity (T12) for 99mTc-EC (pH10) are 3.7±0.6 and 7.3±1.0 respectively while for 99mTc-MAG3, they are 4.0±0.8 and 7.9±1.4 with p values 0.001 and 0.049 respectively. The values of relative renal function (RRF) for 99mTc-EC and 99mTc-MAG3 are 50.8±3.11 and 51.2±3.4 respectively with p value of 0.822. The residual activity at 25th minute (A25 / A MAX) and renal uptake are 0. 209±12.67±2.80 for 99mTc-EC and 0.218±0.035 and 1053±2.98 for 99mTc-MAG3 (p=0.031 an 0.0003) respectively. The correlation coefficient (R2) for TMAX, T1/2, A25/AMAX and renal uptake are 0.96, 0.69, 0.93 and 0.85 respectively.

Predictors of Renal Functional Improvement After Pyeloplasty in Ureteropelvic Junction Obstruction: Clinical Value of Visually Assessed Renal Tissue Tracer Transit in 99mTc-mercaptoacetyltriglycine Renography.

OBJECTIVE: To determine the clinical value of visually assessed renal tissue transit time (TTT) in 99mTc-mercaptoacetyltriglycine (99mTc-MAG3) renography for patients undergoing pyeloplasty. MATERIALS AND METHODS: Medical records of 164 patients who underwent dismembered pyeloplasty were retrospectively reviewed. Baseline and postoperative renal ultrasonography and 99mTc-MAG3 renography were performed. Two urologists blinded to clinical data evaluated the renography and classified TTT as timely or delayed based on visualization of the tracer in the kidney pelvis between 2 and 10 minutes. Renal functional change after pyeloplasty was compared between patients in the timely and delayed groups. RESULTS: A total of 126 patients (median age, 9 months) were evaluated after excluding patients with bilateral ureteropelvic junction obstruction, a single functioning kidney, duplicated ureter, or <3 months of follow-up. There were no differences between 89 patients with timely TTT and 37 patients with delayed TTT in mean preoperative hydronephrosis grade (3.7 vs 3.8) and pelvic diameter (3.1 cm vs 3.4 cm). Although the pre- and postoperative mean values of differential renal function (DRF) were significantly higher in the timely group than in the delayed group (47.2% vs 38.3% and 47.9% vs 44.6%), DRF change was greater in the delayed group (6.3% vs 0.6%). In multivariate analysis, delayed TTT was the only significant predictor of >5% improvement in renal function after pyeloplasty. CONCLUSION: Delayed TTT in 99mTc-MAG3 renography was a significant predictor of renal functional improvement after pyeloplasty in ureteropelvic junction obstruction. Because substantial improvement of renal function is anticipated, we recommend immediate pyeloplasty in patients with delayed TTT and decreased DRF.

The impact of 177Lu-octreotide therapy on 99mTc-MAG3 clearance is not predictive for late nephropathy.

Peptide Receptor Radionuclide Therapy (PRRT) for the treatment of neuroendocrine tumors may lead to kidney deterioration. This study aimed to evaluate the suitability of 99mTc-mercaptoacetyltriglycine (99mTc--MAG3) clearance for the early detection of PRRT-induced changes on tubular extraction (TE). TE rate (TER) was measured prior to 128 PRRT cycles (7.6±0.4 GBq 177Lu-octreotate/octreotide each) in 32 patients. TER reduction during PRRT was corrected for age-related decrease and analyzed for the potential to predict loss of glomerular filtration (GF). The GF rate (GFR) as measure for renal function was derived from serum creatinine. The mean TER was 234 ± 53 ml/min/1.73 m² before PRRT (baseline) and 221 ± 45 ml/min/1.73 m² after a median follow-up of 370 days. The age-corrected decrease (mean: -3%, range: -27% to +19%) did not reach significance (p=0.09) but significantly correlated with the baseline TER (Spearman p=-0.62, p<0.001). Patients with low baseline TER showed an improved TER after PRRT, high decreases were only observed in individuals with high baseline TER. Pre-therapeutic TER data were inferior to plasma creatinine-derived GFR estimates in predicting late nephropathy. TER assessed by 99mTc-MAG3-clearance prior to and during PRRT is not suitable as early predictor of renal injury and an increased risk for late nephropathy.

A comparison of single plasma sample methods to estimate renal clearance using 99mTc-ethylenedicysteine and 99mTc-mercaptoacetyltriglycine.

Several single sample methods for determination of (99m)Tc-mercaptoacetyltriglycine (MAG3) clearance are being used clinically. Kabasakal et al. proposed a similar formula for (99m)Tc-ethylenedicysteine (EC). This study was performed to compare his method with Bubeck et al. formula for (99m)Tc-MAG3 already in use. Twenty-eight subjects divided in two groups were registered which included 22 patients with various renal diseases (group-I) and six normal volunteers (group II). All subjects were studied twice using both the radiopharmaceuticals. The images and renogram parameters, that is TMAX and T1/2 of both the agents, were similar in all the subjects. The clearance of the (99m)Tc-EC was however considerably higher than (99m)Tc-MAG3 in both the groups (mean ± SEM =279 ± 14 ml min(-1)/1.73 m(2) versus 177 ± 15 ml min(-1)/1.73 m(2) in group-I and 377 ± 11.90 ml min(-1)/1.73 m(2) versus 238 ± 8.23 ml min(-1)/1.73 m(2) in group II). This difference was more pronounced in cases with reduced renal functions. Among the Effective Renal Plasma Flow (ERPF) values determined from EC and MAG3 clearances in six normal volunteers, four cases only in MAG3 had ERPF below the lower limit. This study has demonstrated superiority of single sample method for (99 m)Tc-EC clearance over its analogous method for (99m)Tc-MAG3.

[In-vivo tumor imaging by radiolabeled RNA probe targeting telomerase].

OBJECTIVE: To explore the value of telomerase targeted radiolabeled small interference RNA (siRNA) in tumor imaging in vivo. METHODS: Human telomerase reverse transcriptase (hTERT)-targeted and human gene non-targeted siRNAs were chemically synthesized. Through the conjugation with the chelator N-hydroxysuccinimidyl derivative of S-acetylmercaptoacetyltriglycine (NHS-MAG3), the siRNAs were radiolabeled with technetium-99m ((99m)Tc). HE staining and immunohistochemical staining were used to identify their pathological characteristics. 7.4 MBq of (99m)Tc-siRNAs were injected via the tail vein of hepatocarcinoma bearing mice. At 0.5, 1, 3, and 6 h post injection, the mice were laid on a face-up detector and imaged by single-photon emission computed tomography (SPECT), respectively. The ratio of radioactive counts in tumor to that in the contralateral equivalent region was calculated by drawing regions of interest (ROI) at each time point. After the administration of 7.4 MBq of (99m)Tc-siRNAs, the biodistribution (%ID/g) of tumors and blood was measured at the end of 2, 4 and 6 h. Statistical comparisons of the variables were performed by t-test. RESULTS: The labeling efficiency reached 73.4% ± 3.0%. After purification, the radiochemical purity was no less than 92% and the specific activity was up to 25.9 GBq/µmol. HE staining showed pathological mitotic figure in the nucleus of the tumor cells. hTERT immunohistochemical staining showed deep brown dyed spots in the cell nucleus. hTERT-targeted (99m)Tc-siRNA administrated xenografts showed tumor images clearly after the administration, especially at 6 h. In contrast, (99m)Tc-control-siRNA showed no tumor image. The ratios of uptake in tumor to that in contralateral region of hTERT-targeted siRNA increased from 2.68 ± 0.21 to 5.86 ± 0.30 at 6 h, whereas those of control siRNA decreased from 1.55 ± 0.16 to 1.28 ± 0.12 (P<0.01). The biodistribution of tumors in the hTERT-targeted mice increased from 0.71 ± 0.14 to 0.97 ± 0.15 at 6 h, whereas that in the control mice decreased. CONCLUSION: (99m)Tc radiolabeled telomerase-targeted siRNA probe allows for noninvasive visualization of tumor telomerase in vivo.

Comparative evaluation of Tc-99m cystine and Tc-99m MAG3 in normals and patients with renal functional impairment.

Tc-99m cystine has been proved to be a good renal agent in animals for morphologic as well as the functional status of the kidney. In this study, we compared Tc-99m cystine with Tc-99m mercaptoacetyltriglycine, which is used for evaluation of renal function in normal patients, and those with various degrees of renal functional impairment. The clearance values and static images are compared with Tc-99m mercaptoacetyltriglycine. The results show that Tc-99m cystine has good radiopharmaceutical characteristics suitable for evaluation of both renal function as well as morphology.

[A comparison on radiochemical behavior and biological property of antisense oligonucleotide labeled with technetium-99m by two methods: NHS-MAG3 versus SHNHP].

This study was undertaken to explore and compare the radiochemical behavior and biological property of antisense oligonucleotide (ASON) labeled with Technetium-99m using two methods: N-hydroxysuccinimidyl S-acetylmercaptoacetyltriglycline (NHS-MAG3) versus hydrazino nicotinamide derivative (SHNH). After SHNH and NHS-MAG3 were synthesized, ASON was labeled with Technetium-99m using SHNH and NHS-MAG3 as a bifunctional chelator, separately. The stability in vivo and in vitro, the combination with plasma albumen of rabbit, the biodistribution in BALB/ C mice and the HT29 cellular uptake were compared between labeled compound 99mTc-SHNH-ASON, using SHNH as a bifunctional complex reagent, and 99mTc-MAG3-ASON, using NHS-MAG3 as a bifunctional chelator. The results revealed that the labeling rate and the stability of 99mTc-MAG3-ASON were evidently higher than that of 99mTc-SHNH-ASON (P < 0.05), the combination rate of 99mTc-MAG3-ASON with plasma albumen was markedly lower than that of 99mTc-SHNH-ASON (P < 0.05); the biodistribution of 99mTc-MAG3-ASON was markedly lower than that of 99mTc-SHNH-ASON in blood, heart, stomach and intestines (P < 0.05), slightly lower than that of 99mTc-SHNH-ASON in liver and spleen (P > 0.05), and markedly higher than that of 99mTc-SHNH-ASON in kidney (P < 0.05); the HT29 cellular uptake rates of 99mTc-MAG3-ASON was markedly higher than that of 99mTc-SHNH-ASON (P < 0.05). Therefore, the radiochemical behavior and biological property of 99mTc-MAG3-ASON labeled using NHS-MAG3 is better than that of 99mTc-SHNH-ASON labeled using SHNH.

123I-Metaiodobenzylguanidine accumulation in a urinoma and cortex of an obstructed kidney after surgical resection of an abdominal neuroblastoma.

Surgical ureteric injury is rare and often unsuspected for a long time. We present a child in whom an abdominal neuroblastoma was completely excised, but during surgery the left ureter was transected and anastomosed. One month later, during postoperative disease staging, abnormal (123)I-MIBG accumulation was observed in the left renal cortex and the left side of the abdomen. These findings were consistent with acute total obstruction and urinoma formation and were subsequently confirmed by renography and MRI. Despite treatment efforts, a significant amount of left renal mass and function were lost over the following months. These unusual findings are new additions to the literature regarding potential false-positive interpretations of (123)I-MIBG scans.

Noninvasive imaging of human telomerase reverse transcriptase (hTERT) messenger RNA with 99mTc-radiolabeled antisense probes in malignant tumors.

UNLABELLED: The expression of human telomerase reverse transcriptase (hTERT) is present in most malignant cells (>85%) but is undetectable in most normal somatic cells. Visualization of hTERT expression using radionuclide targeting can provide important diagnostic information in malignant tumors. The overall aim of this study was to evaluate whether (99m)Tc-radiolabeled antisense oligonucleotide (ASON) targeting hTERT messenger RNA (mRNA) can be used for imaging of hTERT expression in vivo. METHODS: One 18-mer antisense or sense uniformly phosphorothioate-modified oligonucleotide targeting hTERT mRNA was radiolabeled with (99m)Tc through the bifunctional chelator N-hydroxysuccinimidyl derivative of S-acetylmercaptoacetyltriglycine (S-acetyl NHS-MAG3). Then the radiolabeled probe was characterized in vitro. Reverse transcription-polymerase chain reaction (RT-PCR) was performed to assay the mRNA level after proliferating cells had been incubated with the antisense and sense probes. (99m)Tc-MAG3-ASON or (99m)Tc-MAG3-SON was injected intravenously in mammary tumor-bearing BALB/c nude mice. Biodistribution and in vivo imaging was performed periodically. All data were analyzed by statistical software. RESULTS: The labeling efficiencies of (99m)Tc-MAG3-ASON/SON reached 76% +/- 5% (n = 5) within 15-30 min at room temperature, the specific activity was up to 1,850 kBq/mug, and the radiochemical purity was >96% after purification. (99m)Tc-MAG3-ASON showed complete stability at room temperature and in fresh 37 degrees C human serum. In comparison with (99m)Tc-MAG3-SON, (99m)Tc-MAG3-ASON preserved the capacity to bind living hTERT-expressing cells specifically and to inhibit the expression of hTERT mRNA significantly as well as ASON. In nude mice bearing hTERT-expressing MCF-7 xenografts, tumor radioactivity uptake of (99m)Tc-MAG3-ASON after injection was significantly higher than that of (99m)Tc-MAG3-SON after injection (P < 0.05). The hTERT-expressing xenografts were clearly imaged at 4-8 h noninvasively after injection of (99m)Tc-MAG3-ASON, whereas the xenografts were not imaged at any time after injection of (99m)Tc-MAG3-SON. CONCLUSION: This in vivo study provides evidence that (99m)Tc-MAG3-ASON targeting hTERT mRNA can be used as a potential candidate for visualization of hTERT expression in carcinomas.

Incidental gallbladder visualization on nonhepatobiliary nuclear medicine studies: case series and review of the literature.

Gallbladder uptake is occasionally encountered with commonly used nonhepatobiliary radiopharmaceuticals. Identification of the biliary tract by a nonhepatobiliary agent can identify disease, such as uptake of labeled white blood cells. However, in most cases, gallbladder uptake of nonhepatobiliary tracers is not due to pathology in these cases. It is important to avoid attributing gallbladder uptake to disease in the gallbladder or adjacent anatomic structures. We present 3 cases of unexpected gallbladder tracer uptake and provide a review of the literature describing incidental gallbladder uptake on nonhepatobiliary nuclear medicine studies. The potential for misdiagnosis and the steps taken to avoid this are discussed.

Imaging of HER2-expressing tumours using a synthetic Affibody molecule containing the 99mTc-chelating mercaptoacetyl-glycyl-glycyl-glycyl (MAG3) sequence.

PURPOSE: Expression of human epidermal growth factor receptor type 2 (HER2) in malignant tumours possesses well-documented prognostic and predictive value. Non-invasive imaging of expression can provide valuable diagnostic information, thereby influencing patient management. Previously, we reported a phage display selection of a small (about 7 kDa) protein, the Affibody molecule Z(HER2:342), which binds HER2 with subnanomolar affinity, and demonstrated the feasibility of targeting of HER2-expressing xenografts using radioiodinated Z(HER2:342). The goal of this study was to develop a method for (99m)Tc labelling of Z(HER2:342) using the MAG3 chelator, which was incorporated into Z(HER2:342) using peptide synthesis, and evaluate the targeting properties of the labelled conjugate. METHODS: MAG3-Z(HER2:342) was assembled using Fmoc/tBu solid phase peptide synthesis. Biochemical characterisation of the agent was performed using RP-HPLC, ESI-MS, biosensor studies and circular dichroism. A procedure for (99m)Tc labelling in the presence of sodium/potassium tartrate was established. Tumour targeting was evaluated by biodistribution study and gamma camera imaging in xenograft-bearing mice. Biodistribution of (99m)Tc-MAG3-Z(HER2:342) and (125)I-para-iodobenzoate -Z(HER2:342) was compared 6 h p.i. RESULTS: Synthetic MAG3-Z(HER2:342) possessed an affinity of 0.2 nM for HER2 receptors. The peptide was labelled with (99m)Tc with an efficiency of about 75-80%. Labelled (99m)Tc-MAG3-Z(HER2:342) retained capacity to bind specifically HER2-expressing SKOV-3 cells in vitro. (99m)Tc-MAG3-Z(HER2:342) showed specific tumour targeting with a contrast similar to a radioiodinated analogue in mice bearing LS174T xenografts. Gamma camera imaging demonstrated clear and specific visualisation of HER2 expression. CONCLUSION: Incorporation of a mercaptoacetyl-containing chelating sequence during chemical synthesis enabled site-specific (99m)Tc labelling of the Z(HER2:342) Affibody molecule with preserved targeting capacity.

A comparative study of 99mTc-YIGSR and 99mTc-MIBI uptake in tumor cells.

To investigate a new kind of tumor tracer 99mTc-YIGSR developed from a five amino structure (YIGSR) of the Laminin -chain, which can bind to the laminin receptors of tumor specifically, and radiolabeled with MAG3. (1) Preparation of the 99mTc-YIGSR probe: with S-Acetly-NH3-MAG3 as the chelator and with proper reductants YIGSR was labeled with 99mTc; (2) Cell culture and viability measurement: EAC was maintained in RPMI 1640 supplemented with calf serum; the trypan blue exclusion was applied to calculate the cell viability; (3) Study of the cell dynamic: The EAC's uptake of 99mTc-YIGSR and 99mTc-MIBI was observed at 37 degrees C and 22 degrees C, respectively. (1) The labeling efficiencies of 99mTc-YIGSR and 99mTc-MIBI were (62 +/- 3)% and (96 +/- 2)%, respectively; (2) The cell viability was declined with time of incubation; (3) At 37 degrees C, the EAC'S uptake of 99mTc-YIGSR and 99mTc-MIBI reached the peak of (43.16 +/- 2.4) % and (24.4 +/- 1.8) % at 60 min, respectively; and at 22 degrees C, the highest uptake was (26.5 +/- 2.1) % and (9.47 +/- 1.9) % at 60 min, respectively. The in vitro study suggests that 99mTc-YIGSR is superior to 99mTc-MIBI in cell uptake and has potential value in tumor imaging.

[Detection of impaired renal function: is the modern serologic marker cystatin C more accurate than the 99mTc-MAG3 clearance?]. / Nachweis der eingeschränkten Nierenfunktion: Ist der moderne serologische Marker Cystatin C der 99mTc-MAG3-Clearance überlegen?

AIM: Renal function is usually determined by means of creatinine-clearance, and of serum Cystatin C, the latter with increasing frequency. The present study analyses, whether the diagnostic accuracy of (99m)Tc-MAG(3) clearance is comparable to that of these modern serologic methods. PATIENTS, METHODS: 71 consecutive adult Caucasian patients (42 female, 29 male; age 50 +/- 16 yrs., range 20-83) who were referred to a nuclear medicine department for determination of bilateral renal function with (99m)Tc-MAG(3) were included. Following sufficient hydration, 10 ml of blood were taken for determination of Cystatin C and creatinine in serum prior to i.v. injection of the radiotracer. According to the recommendations of the National Kidney Foundation, glomerular filtration rate (GFR) was calculated from serum creatinine using either Cockcroft & Gault and Modification of Diet in Renal Disease (MDRD) study equation. These estimates of GFR served as reference. Cystatin C is a low molecular protein produced by all nuclear cells and is eliminated to 85 % by glomerular filtration. Analysis of (99m)Tc-MAG(3) clearance was performed by means of Bubeck's formula. RESULTS: Linear regression analysis produced Pearson's correlation coefficients of r = 0.68 and r = -0.69 for the comparison of either Cystatin C and (99m)Tc-MAG(3) clearance with the Cockcroft & Gault equation. The comparison of Cystatin C and (99m)Tc-MAG(3) clearance with MDRD study equation resulted in correlation coefficients of r = 0.755 and r = -0.77. None of these differences were significant. The exclusion of renal impairment or the detection of an at least moderate renal impairment revealed again no significant differences between Cystatin C and (99m)Tc-MAG(3) clearance. CONCLUSIONS: Cystatin C and (99m)Tc-MAG(3) clearance are equally suited to exclude renal impairment or to detect a relevant renal impairment. Differences between both procedures are more likely a result of the applied reference method.

Kidney function after nephrectomy for renal cell carcinoma.

OBJECTIVES: To evaluate the function of the remaining kidney after nephrectomy for renal cell cancer by technetium-99m-mercaptoacetyltriglycine (99mTc-MAG3) renal scintigraphy. METHODS: We evaluated 30 consecutive patients who were undergoing unilateral radical nephrectomy by 99mTc-MAG3 scintigraphy. All patients underwent three consecutive 99mTc-MAG3 scintigraphy studies. The first study was performed before nephrectomy, the second 1 month after surgery, and the third 1 year after surgery. At these times, the serum creatinine levels were also evaluated. RESULTS: The mean preoperative MAG3 clearance of the remaining kidney of the 30 patients was 155.4 mL/min/1.73 m2. The mean MAG3 clearance of the remaining kidney had increased to 209.2 mL/min/1.73 m2 by 1 month after nephrectomy, and the average percentage increase was 39.5%. After 1 year, it had increased to 211.3 mL/min/1.73 m2, with a 40.5% average percentage increase. The preoperative MAG3 clearance of the remaining kidney was inversely correlated with the percentage of increase in MAG3 clearance of the remaining kidney. Abnormal serum creatinine levels (greater than 1.3 mg/dL) were more common after nephrectomy, occurring in 6 patients at 1 month and in 5 patients at 1 year postoperatively. In all 6 patients with elevated creatinine levels, the preoperative MAG3 clearance of the remaining kidney was less than 150 mL/min/1.73 m2. CONCLUSIONS: Adaptive hyperfunction occurs soon after nephrectomy that is not associated with age or sex and continues for at least 1 year. A greater compensatory response is produced in patients with more severe renal deterioration. Using 99mTc-MAG3 scintigraphy, we may be able to predict postoperative renal function.

[The radiolabeling property of oligonucleotide with 99mTc using NHS-MAG3 as a chelator].

OBJECTIVE: To explore the radiolabeling property of oligonucleotide with 99mTc using NHS-MAG3 as a bifunctional chelator. METHODS: Three 15-base single-stranded amine-derivitized oligonucleotides, which were antisense(ASON), sense(SON) and mismatched oligonucleotides(MON) of c-myc oncogene mRNA, were coupled with NHS-MAG3 and labeled with 99mTc. The labeled oligonucleotide was purified by Sephadex G25 column chromatogram, then the stability was evaluated. The labeling efficiency of ON-MAG3 was assessed 15 days, 1 month and 2 months after storage at -20 degrees C. The binding rate of 99mTc-ON with plasma protein was measured by the trichloroacetic acid precipitation method. RESULTS: The average labeling efficiency of 99mTc-ASON, 99mTc-SON and 99mTc-ON was 68.41%, 66.24% and 69.38% respectively, and the radiochemical purity was 96.98%, 95.34% and 94.62%. 99mTc-ON was stable when placed at room temperature or incubated in human serum at 37 degrees C. The labeling efficiency of ON-MAG3 did not significantly change 2 months after storage at -20 degrees C. The plasma protein binding rate of 99mTc-ON was lower than 13%. CONCLUSION: 99mTc-ON labeled with NHS-MAG3 method showed superior radiochemical characteristics. The labeling efficiency and radiochemical purity were desirable. The label was stable in serum and the binding with plasma protein was low. 99mTc-ON could be a sort of potential radiopharmaceutical for in vivo applications.

Prolonged renal parenchymal retention of 99mTc mercaptoacetyltriglycine after nephron-sparing surgery.

OBJECTIVE: Nephron-sparing surgery is a treatment in which a part of a diseased kidney is resected and some parenchyma of the kidney is spared. Impairment of spared renal parenchyma after the surgery may cause prolonged prarenchymal retention in renal scintigraphy with Tc mercaptoacetyltriglycine (Tc-MAG3). The aim of this study was to determine whether or not parenchymal retention of Tc-MAG3 is prolonged after nephron-sparing surgery. METHODS: Twenty-two patients underwent a total of 29 Tc-MAG3 studies within 1 year after nephron-sparing surgery. In 17 patients (23 examinations) who had bilateral kidneys, the presence of diffuse prolongation of parenchymal retention was determined for the operated kidney. In all patients, the presence of regional prolongation around the surgical margin was assessed. RESULTS: Diffuse prolongation was observed in four of 10 examinations performed within 1 month after surgery and in none of 13 examinations performed later than 1 month after surgery. Regional prolongation was shown in 10 of 14 examinations performed within 1 month after surgery and in three of 15 examinations performed later than 1 month after surgery. In five patients who were studied both prior to and later than 1 month after surgery, regional prolongation was noted on the first study. On the second study, regional prolongation was improved and initial renal uptake around the surgical margin was intensified. CONCLUSIONS: Renal parenchymal retention of Tc-MAG3 is frequently prolonged in the early period after nephron-sparing surgery. Renal scintigraphy with Tc-MAG3 may aid in characterizing acute renal damage after nephron-sparing surgery.

Synthesis, radiolabelling and biological characteristics of a bombesin peptide analog as a tumor imaging agent.

BACKGROUND: Several human cancers, including small cell lung, prostate, breast, gastric, colon and pancreatic cancers, express receptors for bombesin-like peptides. Bombesin (BN) peptides that bind specifically to these receptors are useful for detection of bombesin receptor-expressing cancers in vivo. A new 99mTc-labelled-BN peptide for targeting bombesin receptor-expressing cancers was prepared and characterized. MATERIALS AND METHODS: MAG3-coupled BN peptide (MAG3-BN) was prepared by solid-phase synthesis and radiolabelled with 99mTc by an exchange method. In vitro cell binding assays were conducted on human breast cancer cell lines, MDA-MB-231 and MCF-7. In vivo biodistribution studies were performed in normal and nude mice bearing bombesin receptor-positive tumors. RESULTS: Radiolabelling of MAG3-BN with 99mTc produces a single radioactive species (> 95%). In vitro cell-binding indicated the affinity and specificity of 99mTc-MAG3-BN towards bombesin receptors. In vivo biodistribution in mice demonstrated that 99mTc-MAG3-BN cleared rapidly from the blood and most non-targeted tissues and was excreted mainly via the kidneys. Uptake in bombesin receptor-positive tissues and in the tumor was low to moderate. CONCLUSION: 99mTc-MAG3-BN displays good radiolabelling together with certain favorable biological characteristics and might be a useful peptide radiopharmaceutical in the detection of bombesin receptor-expressing cancers in vivo.