Yasemin Parlak

Synthesis, radiolabeling and in vivo biodistribution of diethylstilbestrol phosphate derivative (DES-P)

Diethylstilbestrol (DES) is a well known, nonsteroidal estrogen with high affinity for the estrogen receptor (ER). Today DES is used to treat breast and prostate cancers. A phosphate derivative of DES [Diethylstilbestrol diphosphate (DES-P)] which is specific to tumor cells consisting alkaline phosphatase enzyme was synthesized and labeled with 99mTc using tin chloride as reducing agent. In vivo biological activity of 99mTc labeled diethylstilbestrol phosphate compound (99mTc-DES-P) was examined by biodistribution studies on Wistar Albino rats. Statistical evaluation was performed using SPSS 13 program. The percentage (%) radiolabeling yield of 99mTc-DES-P and quality control studies were done by Thin Layer Radio Chromatography (TLRC). Results showed that, 99mTc-DES-P may be proposed as an imaging agent for ER enriched tumors such as uterus and prostate and their metastases in bones.

Effects of 99mTc-MIBI and 99mTc-MDP administration on dual-energy X-ray absorptiometry bone mineral density measurements.

ObjectiveNuclear medicine procedures are often performed in close-time proximity to bone densitometry studies. The purpose of this study was to determine the effects of 99mTc-hexakis-2-methoxyisobutyl isonitrile (MIBI) and 99mTc-methylene diphosphonate (MDP) on the accuracy of bone mineral density (BMD) measurements performed using dual-energy X-ray density. MethodsThe effect of a diagnostic dose of 99mTc-MIBI on BMD estimations in the lumbar spine and the left total hip was assessed in 30 patients (19 female, 11 male; mean age: 55.5±10.5 years) by using a Lunar DPX-NT scanner. Thirty patients, admitted to the nuclear medicine department for bone scintigraphy (15 female, 15 male; mean age: 56±15.92 years), were included into the study. Each patient underwent dual-energy X-ray density assessment for which a Lunar DPX-NT scanner was used before and 2 h after intravenous injection of 99mTc-MDP (925 MBq) and 99mTc-MIBI (1110 MBq). BMD measurements were calculated from lumbar spine (including L2–4) and left hip (including femoral neck, trochanter, and total hip). For statistical analysis, the Wilcoxon test was used and a P value of less than 0.05 was accepted as statistically significant. ResultsAccording to Wilcoxons statistical test, we found extremely significant changes on the measured BMD, T-score, before and 2 h after the injection of 99mTc-MIBI for lumbar spine and left hip in 30 patients. We found statistically significant decrement on measured BMD from lumbar spine and trochanter before and 2 h after the injection of 99mTc-MDP. Although MDP BMD values in femoral neck and total hip were decreased after the injection of Tc-99m, they did not reach a statistically significant value. The comparison of pre-T-score and post-T-score values showed a statistically significant decrease after the injection for only L2–4 lumbar spine (P = 0.002), but left hip of pre-T-score and post-T-score values did not reach a statistically significant value. ConclusionIn this study, it was determined that measured BMD values are decreased in lumbar spine for all patients. The magnitude of the effect is dependent on the location of the activity. We assume that some radioactivity from 99mTc is counted by the densitometers detector, thus resulting in a decrease in the measured BMD. Scintigraphy and bone densitometry should be performed on different days to avoid artifactual reduction in BMD measurements.

The evaluation of urine activity and external dose rate from patients receiving radioiodine therapy for thyroid cancer

The aim of this study was to determine the external dose rate of iodine retention as a function of time in the bodies of thyroid cancer patients during their isolation period in the hospital. Urine samples were collected at 6th, 12th, 18th, 24th h and 2nd, 3rd, 4th, 5th d from 83 patients after oral administration of (131)I and counted. The external dose rates were also simultaneously determined at the same time points. Then, it was expressed as retained radioiodine body activity versus dose rate. Effective half life calculated from urine sample measurements was found as 18.4±1.8 h within the first 24 h and 64±2.7 h between 48 and 120 h. According to this results, the external dose rate (<20 µSv h(-1)), which patients could be discharged, was achieved after 48 h for 3700 and 5550 MBq, and after 72 h for 7400 MBq of (131)I treatments.

Synthesis, characterization and radiolabeling of folic acid modified nanostructured lipid carriers as a contrast agent and drug delivery system

Nanostructured lipid carriers (NLCs) are the new generation of solid lipid drug delivery systems. Their suitability as contrast agents for gamma scintigraphy is an attracting major attention. The aim of current study was to prepare surface modified nanostructured lipid carrier system for paclitaxel (PTX) with active targeting and imaging functions. In accordance with the purpose of study, PTX loaded nanostructured lipid carriers (NLCs) prepared, modified with a folate derivative and radiolabeled with technetium-99m tricarbonyl complex (99mTc(CO)3+). Cellular incorporation ratios of radiolabeled nanoparticles (99mTc(CO)3-PTX-NLC) were investigated in vitro on three cancer cell lines. Additionally in vivo animal studies conducted to evaluate biological behavior of 99mTc(CO)3-PTX-NLC on female Wistar Albino rats. Biodistribution results showed that the folate derivative modified 99mTc(CO)3-PTX-NLC had considerably higher uptake in folate receptor positive organs. The data obtained from present study could be useful in the design of biodegradable drug carriers of PTX and folate receptor based tumor imaging agents.

Samarium-153 therapy for prostate cancer: the evaluation of urine activity, staff exposure and dose rate from patients

The aim of this study was to determine the excretion of Samarium-153-ethylenediaminetetramethylphosphonic acid ((153)Sm-EDTMP) in urine and to calculate the dose rate of its retention in the body as a function of time and the dose received by the skin of laboratory staffs finger. Urine samples were collected from 11 patients after intravenous injection of (153)Sm-EDTMP. The measurements of dose rate were performed. Thermoluminescent dosemeters were used for absorbed dose measurements. Effective half-lives that were calculated from urine sample measurements were found as 7.1±3 h within the first 24 h. Whole body dose rates before collecting urine of patients were 60.0 ± 15.7 µSv h(-1) for within 1 h following (153)Sm-EDTMP administration. The highest finger radiation dose is to the right-hand thumb (3.8 ± 2 mGy). The results of the study imply that patients who recieved (153)Sm-EDTMP therapy should be kept a minumum of 8 h in an isolated room at hospital and that one staff should give therapy at most two patients per week.

Cytogenetic effects of 99technetium on meristematic cells of root tips of Vicia faba L. andstatistical comparison

In this study, cytogenetic effects of 99technetium (99Tc) on meristematic cells of root tips belonging to Vicia faba L. have been investigated. Seeds of the plant were prepared and kept in 99Tc standard for different time periods: 1/12, 1/4, 1/2, 1, 2, 3, 4, 5, 6 and 12 h. Seeds treated with 99Tc were sprouted and the root tips obtained were prepared for microscopic examination. Some abnormalities e.g. chromosome breaking, chromosome dispersion, bridge chromosomes, chromosome adherence and ring chromosomes were observed. Abnormalities seen for each treatment depended on the time period. The variety and number of abnormalities usually increased with increased treatment time. The results obtained were evaluated statistically.

Radiosynthesis and biodistribution of 99mTc-Sulfamethoxazole: a novel molecule for in-vivo infection imaging

The aim of this study was to prepare 99mTc-Sulfamethoxazole complex and evaluate its efficiency as an infection imaging agent. The Sulfamethoxazole was labeled with 99mTc and its biological efficacy as a potential radio tracer for Staphylococcus aureus infection was investigated in bacterially infected Albino Wistar rats. The radiolabeling yield was found to be 95 ± 3.07% and remained constant at more than 93 ± 0.1% even in serum for 240 min after radiolabeling. 99mTc-Sulfamethoxazole prepared with high yield localized well in the bacterially infected muscle of the rats. 99mTc-Sulfamethoxazole may be developed as a radiopharmaceutical agent to distinguish infection from inflammation by nuclear imaging.

Samarium-153 Therapy and Radiation Dose for Prostate Cancer

Prostate cancer (PC) is one of the most frequent malignancies in Western countries. At initial diagnosis, bone metastases are present in 15–30% of cases. These metastases cause some complications including bone fracture, hypercalcemia, and bone pain, which significantly affect patients’ quality of life. Radionuclide treatment was created as an alternative to external palliative radiotherapy in the treatment of bone pain arising from bone metastasis of PC. The basic principle of the radionuclide treatment of pain is that the uptake of radioactive material is kept in a high amount that is enough to consti‐ tute a proper clinical impact in the tumor, and it is kept at a low dose enough to avoid the occurrence of significant adverse effects in other organs (commonly in the bone marrow). Samarium-153 ethylenediaminetetramethylenephosphonic acid (153SmEDTMP) is a radiopharmaceutical compound that has an affinity for skeletal tissue and concentrates in areas of increased bone turnover, localizes in the skeleton, and is excreted via glomerular filtration. Medical staff preparing and administering radio‐ pharmaceuticals in nuclear medicine, whether for diagnostic imaging or for therapeu‐ tic application, may receive significant radiation doses to their hands, particularly the fingers. Sm-153 treatment can be used as an effective and safe treatment alternative in the management of metastatic bone pain. Radiation protection of the public and the environment after Sm-153 EDTMP therapy is important.

Influence of Arm Movement on Lesion Detection in PET/CT Imaging: Case Report

Arm movement after the CT scan is a common artifact in PET/CT scanning. Motion artifacts may lead to difficulties in interpreting PET/CT images accurately. We report a 66 year old male patient with gastric cancer who underwent PET/CT for primary staging. He had a previous history of papillary thyroid cancer. In PET scan, there were striking cold artifacts at the level of arms. This is a classical sign of an accidental arm motion. A second scan was performed with the arms down due to the history of papillary thyroid cancer. The results were discussed.