Iranian Journal of Nuclear Medicine
Volume:25 Issue: 1, Winter-Spring 2017

Brain single-photon emission computerized tomography (SPECT), in particular, with perfusion agents or with neuroreceptor imaging radiopharmaceuticals, is rapidly becoming a clinical tool in many neurologic and psychiatric conditions. This imaging modality has been used for diagnosis, prognosis assessment, evaluation of response to therapy, risk stratification, detection of benign vs. malignant viable tissue, and the choice of medical or surgical therapy. We will present our institutional experience in this area, formatting a pictorial review of brain perfusion SPECT on more than 20 types of different neurologic and psychiatric diseases, such as dementia, epilepsy, cerebral palsy, head injury, brain tumor, herpes encephalitis, hypoxic brain damage, vacuities, depression, carbon monoxide (CO) poisoning, and cocaine abuse. This is a demanding procedure as far as the need for trained and experienced physicians and personnel as well as advanced equipment are concerned. However, extraordinary useful clinical information achieved by this technology outweighs the existing challenge. More routine use of this procedure which is unfortunately underutilized in many countries including ours should be encouraged.

Holmium-166 radionuclide is one of the most effective radionuclides used for targeted therapy with theranostic properties. One method to produce this radioisotope is via the decay of its parent (indirect method). In this study applicability of extraction chromatography (EXC) for separation of no carrier added 166Ho from neutron-irradiated natural dysprosium target followed by quality control procedures have been demonstrated.
166Dy was produced by thermal neutron bombardment (5×1013n/cm2.s) of natural 164Dy target through 164Dy (n,γ) 165Dy (n,γ) 166Dy process in a nuclear reactor. The generator-produced 166Ho was separated from 166Dy by extraction chromatographic method. The extractant used in resin was 2-ethylhexyl 2-ethylhexylphosphonic acid (HEH[EHP]). The final solution went through radionuclide, chemical and radiochemical purity tests.
Using 1.5 M HNO3 as eluent at 25 °C, and flow rate of 1.5 mL/min, quantitative separation between Ho and Dy was achieved using LN2 resin in 1.5 h to yield in no carrier added 166HoCl3 (radionuclide purity >99.9%; separation yield; 76% and radiochemical purity >99% ITLC).
High specific activity 166HoCl3 produced in this study is highly suitable for metal sensitive labeling of monoclonal antibodies, fragments and especially peptides to yield efficient therapeutic doses for human applications.

The external beam radiation therapy for patients with left breast cancer at the mastectomy site may cause myocardial perfusion abnormalities. We intended to study the change of these abnormalities at short and long term post radiotherapy follow up.
Twenty patients with left and 20 patients with right breast cancer comprised the exposed and control groups, respectively. The patients had low risk for coronary disease. They underwent myocardial perfusion scans (MPS) 3 years after the external beam radiation therapy at the bed of modified radical mastectomy. These subjects were recruited from two bigger cohorts with previously reported data of scans at 6 months. The scans were acquired after injections of about 20 mCi MIBI at peak pharmacologic stress and at rest. The change of the perfusion abnormalities by both visual assessment and quantifications (Autoquant) at the baseline and 3 years follow up time are compared between exposed and control patients.
The exposed patients had more visual perfusion abnormality scores compared to control subjects (1.1±1.3 vs. 0.3±1.0; p=0.03). The indices of perfusion abnormality normalized in control subjects from baseline to follow up scans (p= 0.05 for summed difference score and p=0.04 for summed stress score). The difference of the perfusion abnormalities between the exposed and unexposed subjects remained unchanged along the 3 years of follow up.
The radiation induced myocardial perfusion abnormalities in patients with left breast cancer could cause permanent coronary disease over time.

It is well-recognized that collimator-detector response (CDR) is the main image blurring factor in SPECT. In this research, we compensated the images for CDR in molecular SPECT by using STIR reconstruction framework.
To assess resolution recovery capability of the STIR, a phantom containing five point sources along with a micro Derenzo phantom were investigated. Influence of the lesion size on SPECT quantification was addressed by calculating recovery coefficients (RCs) as well as spill-over ratios (SORs) for reconstructed NEMA image-quality phantom. Impact of the resolution modeling on noise properties was also studied. The RCs were then compared with those of experimentally obtained. In all cases, the images were iteratively reconstructed using an OSEM algorithm with 4 subsets and 32 subiterations.
CDR compensation gives rise to a significant drop in tomographic resolution from 2.45 mm to 1.55 mm. RC for hot rods of the NEMA IQ phantom monotonically grows as rod diameter increases, and results in an improvement of the RC up to a factor of 1.24 for the 5-mm rod diameter. PSF modeling also leads to a reduction in SOR from 0.24 to 0.16 averaged for the two cold cylinders. As a consequence of resolution recovery, a 15.5% overshoot near sharp edges imposing Gibbs ringing artifact occurs. In addition, a blobby noise texture is also observed. Furthermore, STIR results are consistent with the experimental ones.
Our findings demonstrate that resolution recovery is required for quantitative molecular SPECT imaging, and CDR compensation by the STIR framework offers superior SPECT image quality.

We evaluated the performance of muscle perfusion scan (MPS) to assess muscle perfusion reserve (MPR) for prediction of incident diabetic foot ulcerations (DFU).
We recruited 41 diabetic patients without any history of DFU. Five mCi 99mTc-MIBI was injected intravenously during repetitive dorsal and plantar right foot flexions. Then posterior calves were imaged and the counts of the region of interests (ROI) over the right and left calves were collected. MPR was calculated as the percentage of counts of right calf ROI–counts of left calf ROI / counts of left calf ROI. Six patients did not complete the study, 3 of them due to technical errors. Patients were followed for possible occurrence of DFU for at least 12 months.
During the 563±84 (range: 309-633) days follow up period, 2 patients developed DFU (5.7%). MPR was insignificantly lower in patients who developed foot ulceration in comparison to those without foot ulceration (11.3±0.6 % vs. 63.4±40.8 %; p=0.08). The cutoff at first decile of MPR values (i.e. 16%) discriminated the patients with and without future DFU with accuracy of 92% (OR= 3; p-Value=0.005).
MPS is useful to detect patients with diabetes at risk for future DFU.

The use of beta emitters is one of the effective methods for palliation of bone metastasis. The risk of normal tissue toxicity should be evaluated in the bone pain palliation treatment.
In this study, the Monte Carlo simulation code MCNPX was used for simulation a bone phantom model consisted of bone marrow, bone and soft tissue. Specific absorbed fractions were calculated for monoenergetic electrons, photons and eight betaemitters: 32P, 89Sr, 90Y, 153Sm, 166Ho, 177Lu, 186Re and 188Re. Beta and gamma S-factor, absorbed dose and cumulative dose of mentioned radionuclides were obtained to the selection of radionuclides with optimal radiation characteristics.
The results show 177Lu gives a higher local dose to source organ. 177Lu has fewer side effects on critical organ including bone marrow in comparison with other radionuclides such as 89Sr, 32P and 90Y. Cumulative dose versus time shows after a long time, long half-life radionuclides delivering a higher dose in comparison with the short-half radionuclides.
According to the results, low energy β-emitters177Lu, 153Sm and 186Re can be used for bone pain palliation especially in vertebra. Different combination of these radionuclides can be used to improving therapeutic effects for tumors with different size.

Amphetamines are central nervous system (CNS) stimulant substances and amphetamine abuse is considered a growing problem in our country. Previous studies revealed destructive effects of amphetamines on metabolism, perfusion and structure of brain. The aim of current study was evaluating regional cerebral blood flow (rCBF) disturbances in methamphetamine (MA) abusers using brain perfusion SPECT.
This case control study was carried out on 15 MA abusers and 10 healthy volunteers. All 15 MA abusers had a history of MA abuse for at least one year, positive qualitative urinary test for amphetamine. All cases were substance dependent based on Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV) criteria. Patients with opioid and other substance abuse except nicotine and caffeine, positive history of head trauma, loss of consciousness more than 30 minutes and also pregnant women were excluded. All subjects underwent brain perfusion Single-photon emission computed tomography (SPECT).
Of 15 MA users 11 and 4 cases were males and females respectively. Mean age was 42/46±12.08 (range: 22-65) years old. Mean age of control group was 39.56±10.10 (range: 25-63) years old. All MA abusers were currently on using MA. Mean dose of MA use was 0.7 gram per day and mean duration of consumption was 4.86 (1-12) years. Significant differences were observed in scan results (normal or abnormal scan) between two groups (p˂0.05). Of all 15 MA abusers, global decreased tracer uptake was observed in 4 patients (26.7%), global decrease uptake except for the cerebellum was detected in 6 cases (40%), and decreased tracer uptake in fronto-temporal lobes was observed in 2 cases (13.3%), decreased uptake was detected only in the temporal lobe in 2 patients (13.3%) and in temporo-occipital lobes in one case (6.7%). In patients group, decrease in perfusion was more prominent in right frontal, superior frontal and parietal lobes compared with left hemisphere. SPM (Statistical Parametric Mapping) analysis showed significant difference in rCBF between MA abusers and normal volunteers throughout the cerebral cortex with nonhomogeneous decreased tracer uptake.
In this study, we showed that amphetamine abuse can induce diffuse and nonhomogeneous disorders of brain perfusion which was more prominent in the right hemisphere.

Myocardial 18F-FDG uptake is highly variable in oncologic whole body 18F-FDG PET/CT studies, ranging from quite intense to minimal distribution. Intense or heterogeneous myocardial 18F-FDG uptake is undesirable as it may interfere with the visual or quantitative evaluation of tumoral invasion and metastases in pericardium, myocardium or adjacent mediastinal structures. The diet, as well as many other factors, is assumed to influence the myocardial 18F-FDG uptake. Using a multivariate model, we tried to identify and predict the main factors influencing cardiac 18F-FDG uptake in patients referred for oncologic PET/CT evaluation.
A total of 214 patients referred for oncologic 18F-FDG PET/CT scan were enrolled in our study. Patients were randomly allocated into two groups according to the diet they were instructed to follow during 24-hour period before imaging. One hundred and seven cases with a routine diet (RD) and the same number of patients with a low carbohydrate, high fat (LCHF) diet were included. All patients were fast 6 hours before imaging. Weight, height, blood glucose, heart rate, systolic and diastolic blood pressure were measured before radiotracer injection. Visual and quantitative analysis were done after imaging and the pattern of 18F-FDG uptake, as well as standardized quantitative value of cardiac uptake was determined for each case.
The frequency of undesirable cardiac 18F-FDG uptake in the LCHF group was significantly less than RD group (17% vs. 72%, p=30 as well as consumption of cardiotoxic chemotherapeutic agents, benzodiazepines and β blockers were significantly associated with higher intensity of myocardial 18F-FDG uptake, while this undesirable finding was less evident in cases with diabetes mellitus. A multivariate logistic regression model including all of the mentioned variables revealed the diet was the only significant independent factor that predicted undesirable myocardial 18F-FDG uptake (p LCHF diet 24 hours before PET/CT imaging is the only controllable independent factor influencing the intensity and pattern of myocardial 18F-FDG uptake and is recommended as an optimal preparation to suppress cardiac 18F-FDG uptake.

A 63-year-old woman presented with a history of hyperthyroidism symptoms over two years, referred for thyroid scintigraphy. In the hospital archives we have met her previous thyroid scintigraphy showing a hot nodule in the upper part of right thyroid lobe. However, her recent thyroid scintigraphy was showing only cold nodules but no hot nodule, giving an impression that she had some treatment to her hot nodule. Even though she was advised to medical treatment and also referred for radioactive 131I therapy, she refused all the treatment and she only had some branches of dill (Anethum graveolens) as home remedies whenever she had her symptoms, letting us to think, if it is the dill effect.

A 10-year-old boy was referred to us for evaluation of FUO accompanied with bone pain in both calves. Three hours after intravenous injection of 13 mCi of 99mTc-MDP, whole body scan in multiple spot views was performed. The scan showed symmetrical areas of diffusely increased tracer uptake in multiple long bones. Histopathologic evaluation confirmed osteosclrosis and fibrotic changes without any bacterial growth in the specimen culture. Based on patient’s history, lab results, bone scan and histopathologic findings, chronic recurrent multifocal osteomyelitis (CRMO) was considered as the most likely diagnosis. Dramatic response to NSAIDs and pamidronate therapy confirmed the diagnosis of CRMO.