Iranian Journal of Nuclear Medicine
Volume:21 Issue: 1, Winter-Spring 2013

The use of radiopharmaceuticals is a powerful tool in the management of patients with infectious or inflammatory diseases in nuclear medicine. In this study ofloxacin as a second-generation fluoroquinolone is used to design a desired infection imaging agent after labeling with 99mTc via direct labeling. Ofloxacin was radiolabeled with 99mTc using different concentrations of ligand, stannous chloride, sodium pertechnetate and at different pH. Then labeling yield, stability in saline and serum, lipophilicity, binding with Staphylococcus aureus and Escherichia coli and biodistribution in infected mice for labeled compound were studied. The final complex was characterized by TLC and HPLC and radiochemical purity of >90% was obtained when 1.5 mg ofloxacin in presence of 75 µg SnCl2 was labeled with 370 MBq sodium pertechnetate. The complex showed specific binding to Staphylococcus aureus and Escherichia coli. Biodistribution results showed that radioligand had high affinity in the infected site in mice. The uptake for Staphylococcus aureus induced infections (T/NT = 2.33 ± 0.17 at 1 h post injection) was higher than that was for Escherichia coli (T/NT = 1.96 ± 0.13 at 1 h post injection). This complex may lead to further development of a radiotracer for imaging of infections induced by gram-positive or gram-negative bacteria.

We aimed to investigate of effect of left bundle branch block (LBBB) on perfusion and functional parameters in dipyridamole Tc99m-MIBI gated myocardial perfusion SPECT which may be helpful in interpretation of myocardial perfusion imaging. We studied 70 patients with low pre-test probability of coronary artery disease in two groups: 35 patients with LBBB and 35 subjects with normal ECG. Both groups underwent two-day dipyridamole stress–rest Tc99m-MIBI GSPECT. From 35 patients with LBBB, 6, 12, and 3 patients had reversible, fixed and partially reversible defects respectively. In 35 patients with LBBB, 8 (22.9%), 6(17.1%) 15(42.9%) and 10 (28.6%) patients had perfusion defects in the apicoseptal, mid-anterior segments, mid-anteroseptal and mid-inferoseptal segments respectively. There was significant difference in TID ratio between two groups: LBBB group: 1.07±0.21 and control group: 0.96±0.14 (P=0.01). There was a significant difference in end systolic volume and ejection fraction between LBBB patients group and control group, while no significant difference was noticed in end-diastolic volume. Nineteen, 14 and 2 from 35 patients with LBBB had normal LV wall motion, paradoxical septal wall motion, and septal hypokinesia respectively. False positive septal, anterior and apicoseptal perfusion abnormalities are frequently seen on Tc99m-MIBI GSPECT, in patients with LBBB without CAD. Moreover reversible defects are frequently seen with Tc99m-MIBI. Even Tc99-MIBI and vasodilator stress do not increase diagnostic accuracy to clinically useful levels. Lower systolic performance and higher TID ratio could be seen in these patients.

Apoptosis is a major consequence of ionizing radiation in proliferative tissues and quantification of the apoptotic cells could be helpful for noninvasive assessment and estimation of the radiation absorbed dose. Annexin V conjugated with super paramagnetic iron oxide nanoparticles (ANX-SPIO) is a biological probe for detection of apoptotic cells using magnetic resonance imaging. This study aimed at assessing the biodistribution alterations of the labeled ANX-SPIO within the mice body shortly after exposure to different doses of ionizing radiation. 99mTc-EC-ANX-SPIO was prepared and its in vitro stability was tested. The binding affinity of radiocomplex to apoptotic cells was validated in vitro. Mice irradiated whole body with 2, 4 and 6 Gy (60Co gamma rays) and six hours later, radiocomplex was administrated intravenously and the biodistribution study was conducted 0.5, 1 and 2 hours later. The radiochemical purity of radiocomplex was 94% ± 3.4% and it showed a good stability in PBS and serum. The radiocomplex maintained its efficacy for in vitro binding to apoptotic cells.radiocomplex accumulated in the bone marrow of all irradiated mice (p <0.05). However, statistical analysis did not show significant correlation between the %ID/g of the femoral bones and the received radiation doses. Quantification of ANX-SPIO in bone marrow can be used as an indicator for radiation exposure but development and optimization of the assay are necessary for discrimination between different radiation doses.

Scattered photon is one of the main defects that degrade the quality and quantitative accuracy of nuclear medicine images. Accurate estimation of scatter in projection data of SPECT is computationally extremely demanding for activity distribution in uniform and non-uniform dense media. The objective of this paper is to develop and validate a scatter correction technique that use an accurate analytical model based on Klein_Nishina scatter equation and compare Klein_Nishina scatter estimation with triple energy window. In order to verify the proposed scattering model several cylindrical phantoms were simulated. The linear source in the cylindrical Phantoms was a hot rod filled with 99mTc. K factor defines as the ratio of scatter resulting from MC simulation to scatter estimated from Klein_Nishina formula. Also a SPECT/CT scan of the image quality phantom was acquired. Row data were transferred to a PC computer for scatter estimation & processing of the images using MLEM iterative algorithm in MATLAB software. The scatter and attenuation compensated images by the proposed model had better contrast than uncorrected and only attenuation corrected images. The K-factors that used in proposed model doesn’t vary with different activities & diameters of linear source and they’re just a function of depth and composition of pixels. Based on Mont Carlo simulation data, the K_N formula that used in this study demonstrates better estimation of scattered photons than TEW. Proposed scattered correction algorithm will improve 52.3% in the contrast of the attenuated corrected images of image quality phantom.

The aim of the present study was to evaluate the efficacy and safety profile of bone palliative therapy following administration of 153Sm-EDTMP in patients with intractable metastatic bone pain. Sixteen patients (9 male, 7 female) aged 29-80 years (57.3±16.7 years) with severe metastasis-related bone pain resistant to analgesic medications were enrolled in the study. All patients having multiple bone metastases, positive bone scans, and estimated life expectancy of more than 2-3 months were entered the study. All patients received intravenous injection of 1.5 mCi (56 MBq)/kg of 153Sm-EDTMP. Four subscales for the intensity of pain were recorded: one as the present pain score (PPS) and the other three as maximum pain score (Max PS), minimum pain score (Min PS) and average pain score (APS) over the last 24 hours. Also the mean value of these 4 subscales was calculated as the mean total pain score (MTPS). The pain mental interference (PMI) was also assessed in 9 separate. Seven patients with breast cancer (43.75%), seven with prostate cancer (43.75%), one with papillary thyroid carcinoma (6.25%) and one with malignant paraganglioma (6.25%) were included in the study. A significant response to therapy, i.e. 2-point reduction in pain score and/or remarkable reduction (³25%) in the equivalent narcotic dose, was observed in 11 out of 16 patients (68.7%) by the 2nd week and in 12 patients (75%) by the 8th week. Regarding the palliative response to treatment and equivalent narcotic dose reduction, no significant difference between two major types of underlying malignancies (breast and prostate cancer) was found. There was no significant difference regarding response to therapy between two genders and among different age groups. The severity of bone marrow suppression was graded ≤2 in all patients. Response to palliative treatment with 153Sm-EDTMP in prostate and breast cancers is the same at the rate of 75% at the end of 8th week post-infusion. Hematologic toxicity is mild to moderate and no life-threatening side effect is observed.

Sternal non-union is a severe complication of sternotomy closure following open heart surgeries. Healing problems typically occur in 0.3% to 5% of patients. Technetium-99m methylene diphosphonate (99mTc-MDP) bone scintigraphy has been used to assess bone nonunion to predict the healing response for proper management. In this report, we present the case of a marked sternal nonunion following coronary artery bypass graft (CABG), using radionuclide bone scintigraphy.

Deep vein thrombosis (DVT) is an important life threatening condition that is difficult to diagnose, particularly in the early stages. Looking for DVT in lower limb can be considered ancillary in suspected cases of pulmonary embolism (PE) indirectly highlighting a cause and effect relationship of a single disease (i.e cause being DVT and effect is the assault on the lung vasculature). Prompt and early identification of one or both of these pathologies calls for urgent intervention in the form of instituting anticoagulation therapy. Synthetic Tc-99m labeled peptides like apcitide, a glycoprotein (GP IIb/IIIa) receptor antagonist is increasingly used as a specific tracer in the detection of acute DVT. But due to its non availability in certain countries, one needs to resort to indirect evidence in the form of Tc-99m MAA to help in the identification of DVT. Radionuclide phlebography (RPh) combined with lung perfusion scintigraphy (LP) is a one stop shop for the rapid and non-invasive diagnostic assessment of PE due to DVT. The aim of this case report is to highlight the underutilization of nuclear techniques in the evaluation of DVT in routine clinical practice. We report a case of a young Indian male who presented with sudden onset dyspnoea. On scintigraphic evaluation by a simultaneous RPh and LP, the cause and effect of DVT could be easily established.

A nine-month old male child presented with low-grade fever, loose stools and facial puffiness. Clinically patient was otherwise normal except for a firm liver on palpation. The laboratory tests revealed hypoproteinemia (both albumin and globulin) and iron deficiency anemia. Differential diagnosis considered were: 1. Nephrotic syndrome, 2. Cystic fibrosis (in view of recurrent diarrhea and respiratory complaints) 3. Chronic liver disease, in view of firm palpable liver 4. Lastly protein losing enteropathy (PLE). As biochemically patient revealed no positive results, PLE was suspected. For confirmation 99mTc-Methylene diphosponate (MDP) scintigraphy was found to be useful in the setting of non availability of 99mTc-HSA. MDP scan revealed abnormal minimal extravasation of tracer from bowel loops in right lower abdominal quadrant suggesting a diagnosis of PLE. According to the American Gastroenterological Association (AGA) in patients with iron-deficiency anemia who do have GI symptoms, the prevalence of celiac disease is higher and ranges from 10% to 15% which may be a plausible explanation in our patient. The diagnosis of PLE is most commonly based on the determination of fecal alpha-1 antitrypsin clearance. However the localization of gastrointestinal protein (GI) protein loss is possible by scintgraphic techniques alone, as was done in our case using 99mTc-MDP instead of conventionally used 99mTc-HSA.