IRANIAN JOURNAL OF NUCLEAR MEDICINE
Year:2017 | Volume:25 | Issue:2 (SERIAL NUMBER 49)|Papers Count:9

Introduction: In this work, 153Sm-zoledronate (153Sm-ZLD) was studied using computational chemistry methods and prepared for possible use in bone pain palliation therapy.Methods: The Sm (ZLD) 2.7H2O complex was synthesized and characterized in solid state using computational chemistry methods followed by153Sm-ZLD complex production, stablity, hydroxyapatite (HA) tests and also biodictribution studies in animals were studied and used for absorbed dose determination in critical organs.Results: The Sm (ZLD) 2.7H2O complex was synthesized and characterized in solid state and computational chemistry methods showed that 1: 1, 1: 2 and 1: 3 complex formation are possible in aqueous solution.153Sm-ZLD complex was prepared with> 99% radiochemical purity (ITLC, HPLC) and specific activity of 4.4 GBq/mmol. It was stable for 24h with>95% binding to HA with accumulation in rat bones and kidneys. Absorbed dose showed kidney and osteogenic tissue as critical organs.Conclusion: The 153Sm-ZLD complex data were compared to 153Sm-EDTMP and 153Sm-BPAMD.

Introduction: Omeprazole (OP) is one the proton pump inhibitor (PPI) agents, and available over the counter in generic formulations. Epidemiological investigations have been confirmed a relationship between long term use of PPI agents and bone metabolism. Bone scintigraphy is commonly used for analysing the bone metabolism in clinical practice. This study was conducted to assess the effect of omeprazole on the sensitivity of bone imaging to distinguish simulated closed fracture in the rat’s foot.Methods: A total number of 32 adult, male NMRI were chosen. The animals were divided into two principle groups equally for four and eight weeks experiment. Each group was equally divided into four groups. These subgroups included the standard or control rats (4W S and 8W S) not receiving omeprazole and the others that received 25 (4W OP 25 and 8W OP 25), 50 (4W OP 50 and 8W OP 50), 100 (4W OP 100 and 8W OP 100) mg/kg of the drug. Reproducible closed fracture was created in the rat’s foot after 4 and 8 weeks of experiments. Radioisotope studies have been undertaken.Results: All closed fractures created in the feet of animals were visualized by images. The radiotracer uptake ratio at affected foot (target) versus contralateral healthy foot (non-target) was not influenced by omeprazole in the different animal groups.The quantitative investigation indicated that biodistribution of radiotracer was not affected by omeprazole in the other parts of the skeleton.Conclusion: Radioisotope imaging by 99mTc-MDP is sensitive modality to identify the occult fracture and is not affected by omeprazole.

Introduction: In an ideal parallel-hole collimator, thickness of septal material should be sufficient to stop more than 95% of incident photons. However, some photons pass the septa without interaction or experience scattering before they reach the detector. In this study, we determined different contribution of collimator responses consist of geometrical response, septal penetration (SP) and scattering (SC) for low, medium and high energy collimators.Methods: A point source of activity with common energies in diagnostic nuclear medicine and three different collimators were simulated using SIMIND Monte Carlo code.Results: For Low Energy High Resolution (LEHR) collimator, SP was increased from 7% in 140 keV to 30% in 167keV and more than 75% in energies higher than 296keV. SC also was increased from 4% in 98keV to more than 15% in energies higher than 167keV and reached to its maximum (26%) in 296keV. For Medium Energy All Purpose (MEAP) collimator, SP was suddenly increased from 6% in 186keV to 28% for 296keV and more than 50% for higher energies. SC was also increased from 4% in energies below 186keV to 15% in 296keV and about 30% for higher energies. For High Energy (HE) collimator, SP was about 20% for 364keV photons. SC was 15% for 364keV photons and only 65% of photons were geometrically collimated.Conclusion: Our results showed that even by using nominally suitable collimators, there are considerable SC and SP that influence the quantitative accuracy of planar and SPECT images. The magnitude of geometrical response, SC and SP depend on collimator geometric structure and photons energy.

Introduction: The maximum tolerable activity (MTA) of I-131 in radioiodine therapy is an established surrogate quantity to ensure that the therapeutic activity does not produce severe damages to the bone marrow and lung. The aim of this study was to estimate the MTAs for high-risk patients using I-124 pre-therapy dosimetry and to compare the results with published literature.Methods: A total of 15 thyroid cancer patients, who received I-124 pre-therapy dosimetry procedure, had underwent serial blood sampling and whole-body external measurements at approximately 1–2, 4, 24, 48, and 96 h or longer after I-124 administration. The blood sampling and whole-body external measurements were used to calculate the MTA for each individual using published dosimetry procedures.Results: The estimated MTAs ranged from 14 to 34 GBq. The range of blood residence and whole-body residence times were 2.6 h and 22.4 h, respectively; the 48-h whole-body retention value ranged from 2% - 14%. An overall good MTA agreement can be found between our centre and the results of the well-established centre (Essen, Germany) that included 108 patients.Conclusion: I-124 pre-therapy dosimetry provides toxicity levels similar to published values. Further prospective studies are warranted to assess the benefits of I-124 pre-therapy dosimetry for the individual patient and, in particular, the patient outcome.

Introduction: The optimal imaging time of a radionuclide scintigraphy is the time at which the organ of interest has the maximum uptake of the injected radionuclide. This study was performed to investigate the maximum uptake time of 99mTc-DMSA in rat renal scan.Methods: Renal scintigraphy was performed with 3 mCi of 99mTc-DMSA. Planar images were acquired every 20 minutes for 8 hours post-injection using a small-animal SPECT.Results: Activity and the count rate per pixel (CRPP) of the kidneys peaked 1 h post-injection, plateaued for about 1 h, and declined time-dependently. Kidney to background ratio (KBR) reached to 61.7% at 1 h after injection and remained almost constant afterwards.Conclusion: The kidneys had maximum emission and CRPP between 1 to 2 h after 99mTc-DMSA injection, whereas there was no significant difference between the KBRs after 1 h. Our results showed that image acquisition of 1-2 h post-injection is recommended for renal scintigraphy with DMSA in rat.

Introduction: Gated myocardial perfusion SPECT has diagnostic and prognostic values in coronary artery disease (CAD). We tried to determine prognostic values of the left ventricular perfusion & functional indices as well as transient left ventricular dilation (TID) derived from gated myocardial perfusion SPECT.Methods: 1820 patients who underwent gated myocardial perfusion SPECT (Gated SPECT) were studied. The summed stress score (SSS), summed rest score (SRS) and summed difference score (SDS) were calculated. Cardiac events considered as nonfatal myocardial infarction, cardiac death, Coronary Care Unit admission and revascularization. Mean follow-up period after Gated SPECT was 23±10 months.Results: 1599 patients didn’t have any events, while from remaining 221, six patients had an acute MI, 90 patients had CCU admission, 42 patients underwent revascularization and 84 patients died. There was statistically significant difference in the cardiac events based on age, sex, SSS, SRS, SDS, TPD, TID, left ventricular volumes and LVEF. Multivariable Cox regression analysis showed the most and independent predictors of cardiac events are age (P=0.001), SSS (P=0.01) and history of coronary angiography (CA) (P=0.01). History of CA had a greater than 4.4 fold increased incidence of a cardiac event. With increase in SSS for 1 score, 1.4 times and with increase one year in age 1.4 fold increase in future cardiac event were seen.Conclusion: There was a strong association between future cardiac events and clinical history, SSS, SRS, SDS, TPD, TID, left ventricular volumes and LVEF. The most and independent predictors were age, SSS and history of CA.

Introduction: Diethylenetriaminepentaacetic acid (DTPA) is a chelating agent used as a radiopharmaceutical compound, 99mTc-DTPA, for renography. Doxorubicin (DOX) on the other hand is an effective chemotherapy drug used to treat a variety of solid malignancies. Both 99mTc-DTPA and DOX may be used in close succession in patients undergoing DOX based chemotherapy to evaluate renal function. This study aims to investigate the possible alteration in the biodistribution of99mTc-DTPA when given in combination with DOX in rats.Methods: The study was divided in two arms; a control group (n=10) where 99mTc-DTPA alone and the experimental group (n=30) where DOX was injected prior to 99mTc-DTPA administration. The experimental group was further divided into six subgroups (n=5 each) based on the time intervals (4, 8, 18, 36, 72, 96 hours) between DOX and 99mTc-DTPA administration. In each group, the subjects were sacrificed 2 hours post99mTc-DTPA injection, the organs isolated and counted for radioactivity.Results: The results revealed that the percent total retained dose (%TRD) significantly (p<0.001) decreased in urinary tract while significantly (p<0.001) increased in liver and biliary tree as compared to the experimental group.Conclusion: The results of this pre-clinical study put the accuracy of renal scintigraphy in question in patients receiving DOX based chemotherapy. However, human studies are proposed for validity of results with regards to clinical practice.

Introduction: In the nuclear medicine departments, staff exposure to radiation is inevitable during patient positioning and radiopharmaceutical preparation. There is controversy regarding the use of usual lead aprons with respect to penetrating gamma rays used in nuclear medicine departments as well as production of characteristic lead x-ray from aprons.Methods: This research compares the shielding properties of poly vinyl alcohol reinforced by lead acetate, with lead shield based on biological damage to blood cells from the Technetium-99m source. All computations have been carried out by using the WinXcom program. In addition, the alkaline comet assay has been used to estimate DNA damage at the single cell level. Statistical comparisons were analyzed by using the T-test.Results: Calculated value of μm is 0.7616 (cm2/ g), HVL is 7.4 mm and density is 1.224 g/cm3. A significant difference in reducing the amount of DNA damage by 0.5mm sheet of lead was not found.Conclusion: Considering the effects of distance and time on lead acetate composite, results showed that increasing the distance has a significant impact on harm reduction. Even at a distance of 100 cm from the source at all exposure times, the damage is much reduced, compared to the groups with and without a lead shield.

We presented a 30 year-old woman presented with symmetrical swelling of the lower limbs since 5 years ago with sparing of the feet. She was highly suspicious of having lipoedema and was referred for lower limb lymphoscintigraphy to rule out possible lymphedema. Lymphoscintigraphy images showed asymmetrical injection sites and unusually high liver and spleen uptake. Inguinal nodes was not visualized on the right side. With the suspicion of inadvertent intra-vascular injection, another injection was done on the right side. Repeated imaging showed inguinal nodes with normal uptake. In conclusion, in case of any suspicion of intra-vascular injection of the radiotracer in limb lymphoscintigraphy, re-injection of the tracer can be of especial use to avoid false positive results.