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Background 99mTc-prostate-specific membrane antigen (PSMA) SPECT/CT is less expensive and readily available modality compared with 68Ga-PSMA PET/CT for imaging prostate cancer (PC). The aim of this study is to compare the value of these 2 modalities in patients confirmed or suspicious to have metastatic prostate cancer. Patients and methods Twenty-two patients with the mean age of 66.6 ± 10.1 years were studied using 99mTc-PSMA SPECT/CT and 68Ga-PSMA PET/CT, with less than 7 days interval between the 2 imaging procedures. Whole-body PET/CT was done 60 minutes after IV injection of 185 MBq (5 mCi) of 68Ga-PSMA. 99mTc-PSMA SPECT/CT was performed 3 hours after IV injection of 555 to 740 MBq (15-20 mCi) of 99mTc-PSMA. The images of each modality were interpreted independently, and the results were compared according to patient-based as well as region-based analyses. Results In patient-based evaluation, both 99mTc-PSMA SPECT/CT and 68Ga-PSMA PET/CT scans were positive in 95.45% (21/22). In region-based evaluation, 68Ga-PSMA PET/CT detected 53 regions (median of 2 regions per patient; range, 0-5), whereas 43 (median of 2 regions per patient; range, 0-5) were detected by 99mTc-PSMA SPECT/CT. Most of these differences could be explained by lower detection rate of 99mTc-PSMA SPECT/CT in prostate bed (n = 6). PET/CT detected more involved regions than SPECT/CT (P = 0.007), whereas similar frequency of extraprostatic lesions were diagnosed in both modalities (P = 0.102). Significant correlation was also demonstrated between serum prostate-specific antigen level and imaging parameters of disease extension detected by 2 modalities. Conclusions 99mTc-PSMA SPECT/CT could be a potential substitute for 68Ga-PSMA PET/CT in high-risk patients, except when evaluation of prostate bed is of major concern.

Aim: Bull's eye pattern recognition with artificial neural networks (ANNs) has the potential to assist interpretation of myocardial perfusion images (MPIs). We aimed to develop a model for interpretation of MPI based on the clinical variables and imaging data. Materials and Methods: The study included 208 patients referred to the department of nuclear medicine for 2-day stress-rest ECG-gated MPI. Several ANN models were designed with the following input variables: average count of 20 segments of the bull's eye images of stress and rest MPIs, gender, the constellation of coronary artery disease risk factors and scintigraphic cardiac ejection fraction. The procedure was repeated excluding the data of the rest phase scan. Data of 150 subjects were used for training, 21 subjects for cross-validation and 37 subjects for final operation testing. Several ANN models were examined with different hidden layers and processing elements and functions. The target output variable was the conclusion of the nuclear physician (i.e., normal vs. abnormal scan). Results: A multilayer perceptron (MLP) with two hidden layers trained with both stress and rest data demonstrated the best performance to classify the normal and abnormal MPIs. It showed an overall accuracy of 91.9%, sensitivity of 91.3% and specificity of 92.9%. The accuracy of the similar MLP trained using stress-only myocardial perfusion images reduced to 67.6%. Conclusion: The automated interpretation of MPIs with a 2 hidden layer MLP trained with stress and rest images could be an accurate support system either for the interpretation or quality assurance.

A 53-year-old man with previous history of sigmoid colon adenocarcinoma who had undergone surgical resection and adjuvant chemotherapy presented with slightly rising carcinoembryonic antigen (CEA), while anatomical imaging modalities were unremarkable. FDG PET-CT study did not identify residual tumoral disease; however, there were abnormalities in the gallbladder most likely suggestive of cholecystitis. Eight weeks after cholecystectomy, serum CEA concentration reached normal values. Final histopathology of the gallbladder was also consistent with acute on chronic cholecystitis.

Objective With respect to the equivocal value of the reverse perfusion pattern (RPP) in technetium-99m (Tc)-sestamibi myocardial perfusion imaging, a study was carried out to evaluate this pattern in association with the presence or absence of coronary artery disease (CAD) and other underlying factors, mainly the time of acquisition and the presence of intense visceral uptake. Patients and methods We prospectively studied 102 patients with a moderate risk of CAD (41 men and 61 women, mean age: 56.5±9.2 years) without a previous history of documented CAD, myocardial infarction, or revascularization. Myocardial perfusion imaging was performed using a 2-day dual-phase protocol with the stress and rest images, each obtained 15, 120, and 180 min after an injection of 666-814 MBq Tc-MIBI. According to the time of image acquisition, the following five protocols were defined, A: 15/15 min, B: 15/180 min, C: 180/180 min, D: 180/15 min, and E: 120/120 min for stress/rest images, respectively. Results The odds of RPP were higher in the cases with more intense infradiaphragmatic visceral uptake on rest-phase images of the protocols A and D (odds ratios=1.2-7.8 and 1.2-7.5, respectively). Our results showed that RPP is related to incorrect normalization. Also, diabetes, sex, and CAD did not correlate with RPP. Conclusion This study found no relationship between RPP and CAD, diabetes mellitus, and sex; however, an association was found between RPP and incorrect normalization because of the variation of visceral uptake intensity in relation to the time of acquisition at stress and rest phases favoring the artifactual base of this pattern.

Patients with diabetes have higher stress-to-rest mean left ventricular volume (SRLVV) ratio in myocardial perfusion imaging (MPI) and hyperhomocysteinemia. We studied the effect of folate therapy on SRLVV ratio and plasma homocysteine levels in patients with diabetes. Forty patients were enrolled and thirty-two completed the study. The patients underwent a 2-day pharmacological stress test and rest MPI before and 2 months after treatment with either 5 mg folic acid or placebo. SRLVV ratios were calculated, and plasma homocysteine levels were measured, before and after treatment. Among the 32 patients who completed the study, 15 received folic acid and 17 received placebo. The age of subjects (folate 51.5 ± 6.1 years; placebo 50.6 ± 8.1 years), male/female ratio (folate 6/11; placebo 9/6),or MPI findings (proportion of normal results: folate 80.0 %; placebo 94.1 %) were similar between the two groups. The baseline SRLVV ratio was similar between groups (folate: 1.00 ± 0.09 vs. placebo: 0.97 ± 0.13); however, the post-treatment SRLVV ratio was significantly lower (P

Objectives: Coronary artery disease is the leading cause of mortality worldwide. The goal of this study is to determine the prognostic value of semiquantitative parameters of electrocardiogram-gated single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) in a large Middle Eastern (Iranian) population. Materials and Methods: This study was a prospective study including all patients referred to our center for myocardial perfusion scan. The patients were followed annually up to 24 months and their survival information was collected. Results: From 1148 patients, 473 (41.2%) men and 675 (58.8%) women, 40.6% had normal MPI, 13.3% near normal and 46.1% abnormal MPI. After follow-up of 929 patients, 97.4% of patients were alive, and 2.6% succumbed to cardiac deaths. Abnormal ejection fraction was related with cardiac events (P = 0.001), but neither transient ischemic dilation (TID) (P = 0.09) nor lung/heart ratio (P = 0.92) showed such relationship. Association between summed difference score (SDS) and soft cardiac events (P < 0.001) was significant. Summed motion score (SMS) and summed thickening score (STS) showed a significant relation with hard cardiac events, including myocardial infarction and cardiac death (P < 0.001 and P = 0.001, respectively). Totally, risk of all cardiac events was significantly higher in abnormal MPI group than normal group (P < 0.001, 0.02, and 0.025, respectively). No significant relationship was found between TID and total cardiac events (P = 0.478). Conclusion: Semiquantitative variables derived from gated SPECT MPI have independent prognostic value. Rate of total cardiac events is higher in patients with higher summed stress score and SDS. Total and hard cardiac events are higher in upper scores of functional parameters (SMS and STS). Total cardiac events are higher in patients with lower left ventricular ejection fraction.

Use of radioactive iodine is an essential adjuvant treatment strategy after thyroidectomy in patients with differentiated thyroid carcinoma. Although generally safe, radioiodine therapy has some potential side effects, classified as early and late complications, which we have reviewed in this paper. Early complications include gastrointestinal symptoms, radiation thyroiditis, sialadenitis/xerostomia, bone marrow suppression, gonadal damage, dry eye, and nasolacrimal duct obstruction. The late complications include secondary cancers, pulmonary fibrosis, permanent bone marrow suppression, and genetic effects. As I is an efficacious form of treatment that can significantly decrease the rate of mortality, recurrence, and metastasis, and as the side effects are often minor and well tolerated, radioiodine therapy remains the principal mode of treatment for patients with differentiated thyroid carcinoma.

Background: Because of the increasing prevalence of both ischemic heart diseases and vitamin D deficiency and also due to recent evidences on association between these two phenomena, it is vital to clarify the association of ischemic heart disease with vitamin D deficiency and low bone mass. Objectives: The aim of the present study was to assess the relationship between low serum vitamin D and low bone mass measured by dual-energy X-ray absorptiometry (DEXA) with ischemic heart disease assessed by the functional radionuclide myocardial perfusion imaging (MPI). Patients and Methods: In this cross-sectional study, 204 consecutive patients aged older than 50 years who were candidates for MPI were included. Blood sample was extracted to measure the level of serum 25-OH vitamin D using a special kit (IDS kit). Then, the patients were assessed by MPI. Within a month of myocardial perfusion scanning, subjects underwent bone mineral density (BMD) measurements by DEXA method. Results: There was no significant difference in serum level of vitamin D between patients with normal and those with abnormal MPI results. In addition, no significant correlation was detected between BMD and myocardial ischemia. Conclusion: Coronary atherosclerosis may not be associated with the severity of low bone mass or level of vitamin D adequacy.

A 59-year-old man was admitted for fever of unknown origin. Fever was associated with chills. His medical record revealed the history of aortic valve replacement 11 years earlier, as well as enterococcal endocarditis 4 months prior to the current admission. The patient was found to have normal left ventricular size with borderline systolic function, left ventricular hypertrophy, right ventricle at the upper limit of normal size, mild systolic dysfunction and mild transvalvular aortic insufficiency on transthoracic echocardiography; while no vegetations were observed on transesophageal echocardiography. Sequential blood cultures were negative; however, a blood culture sample obtained 5 …

Parkinson disease (PD), parkinsonian syndromes (PS) and essential tremor (ET) are different types of movement disorders which share some symptoms resulting in a difficulty of certain diagnosis. This study was conducted to determine the value of 99mTc-TRODAT-1 scan to differentiate PD from ET and other PS cases. Totally, 75 patients were studied including 29 PD, 6 possible PD, 22 ET and 18 PS cases. A dual-head SPECT-CT was used to perform basal ganglia (BG) imaging following administration of 99mTc-TRODAT-1. The BG uptake values were normalized to whole brain and occipital activity. All patients were followed for 2–22 months to reach a certain diagnosis. Patients with ET and drug-induced parkinsonism show significantly higher normalized BG uptake as compared to the other subgroups; however, no significant difference was noted between PD and PS patients. The sensitivity and specificity of the findings for the differentiation between patients with the disease associated versus not associated with BG dysfunction were 80 and 83.3 %, respectively. A predictive positive value of 82.6 % was obtained using an additive scaling index defined as asymmetry and unevenness of uptake in putamen and/or caudate contralateral to the dominant side of current symptoms. 99mTc-TRODAT-1 scan is an appropriate method to differentiate PD or PS versus ET. A combination of scan pattern including asymmetry of BG uptake and unevenness of activity in caudate and putamen along with the side of dominant symptoms may be valuable for the differentiation of Parkinson’s disease from the other parkinsonian syndromes.

Non ideal collimation and detector blurring are the main causes of resolution loss in single photon computed tomography (SPECT) that affect both qualitative and quantitative interpretation of SPECT images. In this research we evaluate the importance of resolution recovery in determining the absolute amount of activity in small liver tumors by comparing three different approaches: ordered subsets expectation maximization (OSEM), OSEM with 2D resolution recovery and OSEM with 3D resolution recovery. Two different sets of projections were created. Model based projections were created by layer by layer blurring of activity phantom using known distance dependent Gaussian functions. Simple ray sum of this blurred phantom was driven to create projections. This simulates noise free projections with completely known system response. The other set of projections was created using SIMIND Monte Carlo simulator. Eight small tumors (1×1×1 cm) were considered on different parts of NCAT liver phantom in such a way that all appear in same plane in a sagittal slice. Vertical distance between each couple of tumors was varied between 1 and 4 pixels (equal to 3.3 and 13.3 mm). To evaluate the value of resolution recovery during reconstruction, OSEM with the ability of modeling both 2D and 3D system response model during reconstruction was developed and used. Both 2D and 3D resolution recovery results in better quantitative results compared to simple OSEM. 3D resolution recovery, however reconstruct images with much higher quantitative accuracy. Only in 3D resolution recovery it is possible to separate all couple of tumors in axial direction. The amount of activity recovery depends on the number of iteration. Using 8 iterations and 8 subsets in each iteration, 3D resolution recovery results in 8% better activity recovery compared to 2D and 13% compared to simple OSEM. This amount is 27% and 46% for 25 iterations.

There are few studies evaluating the effect of radioioine therapy on the lacrimal drainage system. This study reports on symptomatic and asymptomatic nasolacrimal duct obstruction (NLDO) as complications of high-dose radioiodine therapy in these patients.Eighty-one cases were randomly selected from a population of radioiodine-treated differentiated thyroid carcinoma patients and were enrolled in a historical cohort study. The patients were categorized into four subgroups on the basis of the received cumulative dose of iodine-131 (I-131). In addition, 17 age-matched and sex-matched individuals were selected as the control group. Using dacryoscintigraphy and a clinical datasheet, the patients and controls were evaluated for partial or complete and symptomatic or asymptomatic NLDO. The data on different subgroups of patients were compared with the data of the control group.Twenty-nine out of 162 exposed eyes (18%) and three out of 34 control eyes (9%) had evidence of NLDO on scintigraphic images. Among patients treated with less than 11.1 GBq of I-131 (subgroup A), six out of 78 eyes (7.7%) had partial or complete NLDO. This was evident in 23 out of 84 eyes (27.4%) among patients treated with 11.1 GBq or more (subgroup B). The frequency of complete NLDO increases significantly when the cumulative dose of radioiodine exceeds 11.1 GBq (2.9% in the control group, 3.8% in subgroup A, and 23.8% in subgroup B; P=0.006).NLDO may be considered as a side effect of I-131 therapy, especially with a cumulative dose of 11.1 GBq or more.