فهرست مطالب

Iranian Journal of Nuclear Medicine
Volume:17 Issue: 2, Summer-Autumn 2009

  • تاریخ انتشار: 1388/12/01
  • تعداد عناوین: 9
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  • Mohamadreza Nouri Mahdavi Pages 6-11
    Neuroendocrine tumors (NETs) constitute a heterogeneous group of neoplasms including carcinoids, pancreatic neuroendocrine tumors, pituitary tumors, medullary thyroid carcinoma and phaeochromocytomas. The symptoms and the outcome of NETs differ considerably between patients depending on several factors. By labelling tracers with a radioisotope, the tracer acts as a carrier to deliver the radioactivity to tissues expressing somatostatin receptors (SSTRs) and may be used for diagnosis and treatment. Several factors influence the selection of an appropriate therapeutic radioisotope. A longer physical half-life and low dose rate may be more effective for relatively indolent malignancies such as NETs. Radiolabelled targeted therapy is a fairly recent and promising modality for the management of patients with inoperable or disseminated NETs when conventional therapies fail.
  • Ali Bahrami, Samani, Mohammad Ghannadi, Maragheh, Amir Reza Jalilian, Moein Meftahi, Simindokht Shirvani, Arani, Sedigheh Moradkhani Pages 12-19
    Introduction
    Nowadays various bone pain palliative therapeutic agents have been developed for bone metastases. Among those, 153Sm-ethylenediamine tetramethylene phosphonic acid (153Sm-EDTMP) is the major therapeutic agent which is widely used in the world. In this study, production, quality control and biodistribution studies of this therapeutic radiopharmaceutical have been presented and followed by imaging studies in a wild-type rabbit for the first time in order to make preparations for this agent to be officially approved in the country.
    Methods
    153Sm-EDTMP was produced using 153Sm-SmCl3, prepared by neutron activation of an enriched 152Sm sample (purity >98%), and in-house synthesized EDTMP in 4h at 100°C. The analytical data for the structure determination and purity of the ligand was obtained and shown to be identical to an authentic sample from a European vendor. The Radiochemical purity of 153Sm-EDTMP was checked by RTLC and ITLC. The biodistribution of 153Sm-EDTMP in wild-type rodents was checked and SPECT imaging as well as following sacrificing the animal.
    Results
    The radiolabeled Sm complex was prepared in high radiochemical purity (>99%, RTLC) followed by initial biodistribution data with the significant bone accumulation (>70%) of the tracer in 48h which is comparable with the reported methods.
    Conclusion
    The produced 153Sm-EDTMP properties suggest good potential for efficient use of this radiopharmaceutical for bone pain palliation and as substitute for other agents, such as 89SrCl2 and 32P, currently used in the country.
  • Enayatollah Nemat Khorasani, Fariba Mansouri Pages 20-25
    Introduction
    Early differentiation of biliary atresia from neonatal hepatitis is of utmost importance, since on time surgery of biliary atresia significantly improves the outcome. Hepatobiliary scintigraphy is an integral part of diagnosis work-up of these patients; however its specificity for diagnosis of biliary atresia is suboptimal. In this study we evaluated the value of ursodeoxycholic acid pre-treatment for improvement of hepatobiliary scintigraphy specificity.
    Methods
    Thirty consecutive infants with direct heperbilirubinemia were included into the study. All infants underwent hepatobiliary scintigraphy with 99mTc-bromo iminodiacetic acid (99mTc-BRIDA) twice (first after pre-treatment with phenobarbital and the other time after pre-treatment with ursodeoxycholic acid).
    Results
    Of 30 patients included into our study 13 had final diagnosis of extrahepatic biliary atresia and 17 had neonatal hepatitis. Bowel was visualized in 11 patients with neonatal hepatitis after phenobarbital pre-treatment and in 16 after ursodeoxycholic acid pretreatment which amounts to 80 % and 96.6 % specificity for diagnosis of biliary atresia with phenobarbital and ursodeoxycholic acid respectively. All patients had complications of phenobarbital administration (lethargy, poor feeding, irritability, hypotonia, etc) to some extent. These findings decreased significantly after discontinuation of phenobarbital and were not present with ursodeoxycholic acid.
    Conclusion
    Ursodeoxycholic acid is a safe and efficient drug for pre-treatment of patients with neonatal cholestasis syndrome who are going to undergo hepatobiliary scintigraphy. Compared to phenobarbital, this drug has fewer complications and is more efficient.
  • Parham Geramifar, Mohammad Reza Ay, Mojtaba Shamsaie Zafarghandi, George Loudos, Arman Rahmim Pages 26-33
    Combined PET/CT scanners now play a major role in medicine for in vivo imaging in oncology, cardiology, neurology, and psychiatry. As the performance of a scanner depends not only on the scintillating material but also on the scanner design, with regards to the advent of newer scanners, there is a need to optimize acquisition protocols as well as to compare scanner performances on an objective basis. In this study we evaluate and compare the performance of 4 Commercial GE PET/CT cameras, the (i) BGO-based Discovery LS PET/CT (DLS), (ii) the BGO-based Discovery ST PET/CT (DST), (iii) the BGO-based Discovery STE PET/CT (DSTE) and finally (iv) the LYSO-based Discovery RX PET/CT (DRX) scanner using the Geant4 Application for Tomographic Emission (GATE). GATE is an open source Monte Carlo simulation platform developed for PET and SPECT studies and is supported by the OpenGATE collaboration. In accordance with the National Electrical Manufactures Association (NEMA) NU 2-2001 protocols, the validation of models is carried out against actual published measurements and the performance comparison is done for sensitivity, scatter fraction and count rate performance, showing very similar performance compared with published results, thus enabling investigations to better model system performance (e.g. resolution degradation) within the reconstruction task.. The simulated results demonstrate highest sensitivity performance with the DST (though with the highest scatter fraction), and highest NECR performance for the LYSO-based DRX, The results also show that DRX, DLS and DSTE PET/CT cameras have nearly the same amount of scatter fraction.
  • Amir R. Jalilian, Aytak Novinrooz, Farahnaz Motamedi, Sedeh, Sedigheh Moradkhani, Amir A. Rajamand, Jalal Solati Pages 34-41
    Introduction
    Gallium-67 citrate has been known as a good infection agent in nuclear medicine for decades. In this work the value of 67Ga-citrate has been investigated in infected animal models using SPECT imaging at optimized/standardized conditions.
    Methods
    The bacterial (Staphylococcus aureus; S.a. and Escherichia coli; E.c.) and fungal (Candidae albicans; C.a.) species from standard sources were cultured according to the standard procedures and wild-type NMRI rats were inoculated by the injection of 5x107 microorganisms (MO) into their thighs and animals incubated for infection site formation for 2 and 3 days followed by iv injection of freshly prepared 67Ga-citrate (45-50 µCi) and SPECT imaging performed at 2, 4 and 24 hours post injection in parallel with control groups.
    Results
    In S.a.-infected rats 67Ga-citrate demonstrated hot spot foci at all time intervals esp. 24h post injections in contrast with normal animal scans. In case of C.a., the infected animals also demonstrated significant accumulation foci being most significant after 24h. In E.c.-infected animals however weak positive scans were obtained even after 24 hours.
    Conclusion
    Our animal models developed for the evaluation of new infection-targeting agents were successfully positive using 67Ga scan. These models can also be used in the evaluation of newly developed antibiotics in animal models for in vivo studies. The efficacy of 67Ga-scan in our microorganism infection models can be summarized as S.A.>C.a.>E.c..
  • Behnoosh Teimourian, Mohammad Reza Ay, Mojtaba Shamsaei Zafarghandi, Hossein Ghadiri Pages 42-49
    In present PET/CT scanners, PET attenuation correction is performed by relying on the information given by CT scan. In the CT-based attenuation correction methods, dual-energy technique (DECT) is the most accurate approach, which has been limited due to the increasing patient dose. In this feasibility study, we have introduced a new method that can implement dual-energy technique with only a single energy CT scan. The implementation was done by CT scans of RANDO phantom at tube voltages of 80 kVP and 140 kVP. The acquired data was used to obtain conversion curves (which scale CT numbers at different kVP to each other), in three regions including lung tissue (HU<-100), soft tissue (-100200) for the combination of 80 kVP /140 kVP. Therefore, with having the CT image in one energy, we generate the CT image at the second energy (from now we call it virtual dual-energy technique) using these kVP conversion curves. The attenuation map at 511 keV was generated using bilinear (the most commonly used method in commercially available PET/CT scanners), real dual-energy and virtual dual-energy technique in a polyethylene phantom. In the phantom study, the created attenuation map using mentioned methods are compared to the theoretical values calculated using XCOM cross section library. The results in the phantom data show 10.1 %, 4.2 % and 4.3 % errors for bilinear, dual-energy and virtual dual-energy techniques respectively. Further evaluation using a larger patient data is underway to evaluate the potential of the technique in a clinical setting.
  • Maria M. Dsouza, Rajnish Sharma, Madhavi Tripathi, Abhinav Jaimini, Dinesh Singh, Anupam Mondal Pages 50-54
    We report an unusual case of a young male with cerebellar hemangioblastoma treated previously for medullary carcinoma of thyroid, whose PET/CT scans revealed a constellation of findings that suggested the rare Von Hippel Lindau syndrome. The diagnosis was clinched by confirming the findings on whole body contrast enhanced computed tomography (CECT) and contrast enhanced magnetic resonance imaging (CEMR). The report highlights the need to carefully evaluate subtle findings on PET/CT that could be missed or misinterpreted as other diagnoses. It also adds to the existing literature of two cases with Von Hippel Lindau syndrome and medullary carcinoma of thyroid.
  • Mehdi Momennezhad, Seyed Rasoul Zakavi, Vahid Reza Dabbagh Kakhki, Ramin Sadeghi Pages 55-57