The Prognostic Power of Preablation Stimulated Thyroglobulin in Children With Differentiated Thyroid Cancer.

OBJECTIVE: To analyze prognostic factors in children with differentiated thyroid carcinoma (DTC) who have been treated in a single center in the last 27 years. METHODS: We studied 126 children (≤18 years old) who have been treated with near-total thyroidectomy followed by radioiodine therapy and thyroid hormone replacement. Follow-up of the patients was done 2, 6, and 12 months after treatment and then by yearly evaluation. Response to treatment was defined according to the American Thyroid Association guidelines. RESULTS: Papillary thyroid cancer was the main pathology (93.7%), and 52.4% of the patients had lymph node metastasis at presentation, which was extensive (>5) in 30% of the patients. Distant metastasis was seen in 8.8%. The mean initial dose of I-131 was 74 ± 42.2 MBq/kg. The median follow-up was 59 months and the median time to achieve an excellent response was 29 months. The preablation stimulated thyroglobulin (psTg) level was 202.4 ± 301.8 ng/mL in patients with first-year incomplete response compared with 11.2 ± 17.5 ng/mL in others (P =.001). Furthermore, using logistic regression, the psTg level was found to be the only significant predictor of distant metastasis, and psTg ≥ 13.75 ng/mL was the most powerful predictor of first-year incomplete response. Moreover, distant metastasis was more common in boys than in girls, and it took longer time for boys to achieve an excellent response. CONCLUSION: The psTg level was the only significant predictor of distant metastases in children with DTC, and psTg ≥ 13.75 ng/mL was the most powerful predictor of first-year incomplete response.

Unilateral Chronic Parotitis With 68 Ga-DOTA-FAPI-04 PET/CT and 18 F-FDG PET/CT Imaging in a Case of a Patient With Papillary Thyroid Carcinoma.

ABSTRACT: The 68 Ga-FAPI (fibroblast activation protein inhibitor) radiotracer is a novel and versatile tool in nuclear medicine, exhibiting potential for use in various conditions due to its significant upregulation in cancerous and inflammatory conditions, particularly those involving fibrotic and infectious processes. In this report, we present the case of a patient with papillary thyroid carcinoma who underwent total thyroidectomy and iodine therapy. He was referred because of high thyroglobulin despite negative diagnostic radioiodine imaging (TENIS syndrome). The patient underwent 18 F-FDG and 68 Ga-DOTA-FAPI-46 PET/CT imaging for metastatic workup and treatment planning. FAPI uptake was observed in the right parotid gland (with no FDG uptake), prompting a 99m TcO 4- salivary scintigraphy. Subsequently, a diagnosis of chronic sialadenitis was made.

Impact of [18F]FDG PET/CT in the Assessment of Immunotherapy-Induced Arterial Wall Inflammation in Melanoma Patients Receiving Immune Checkpoint Inhibitors.

We aimed to investigate the role of [18F]FDG positron emission tomography/computed tomography (PET/CT) in the early detection of arterial wall inflammation (AWI) in melanoma patients receiving immune checkpoint inhibitors (ICIs). Our retrospective study enrolled 95 melanoma patients who had received ICIs. Inclusion criteria were ICI therapy for at least six months and at least three [18F]FDG PET/CTs, including one pretreatment session plus two scans three and six months after treatment initiation. AWI was assessed using quantitative and qualitative methods in the subclavian artery, thoracic aorta, and abdominal aorta. We found three patients with AWI visual suspicion in the baseline scan, which increased to five in the second and twelve in the third session. Most of these patients' treatments were terminated due to either immune-related adverse events (irAEs) or disease progression. In the overall population, the ratio of arterial-wall maximum standardized uptake value (SUVmax)/liver-SUVmax was significantly higher three months after treatment than the pretreatment scan in the thoracic aorta (0.83 ± 0.12 vs. 0.79 ± 0.10; p-value = 0.01) and subclavian artery (0.67 ± 0.13 vs. 0.63 ± 0.12; p-value = 0.01), and it remained steady in the six-month follow-up. None of our patients were diagnosed with definite clinical vasculitis on the dermatology follow-up reports. To conclude, our study showed [18F]FDG PET/CT's potential to visualise immunotherapy-induced subclinical inflammation in large vessels. This may lead to more accurate prediction of irAEs and better patient management.

AOJNMB enters the Second Decade of Publication.

No Abstract is available.

Thyroid Ultrasound-Image Dataset.

Thyroid Computer-Aided Diagnosis (CAD) systems have been developed to assist radiologists in improving efficiency, reliability, and diagnosis performance. Often the performance of these CAD systems is evaluated with different datasets that make it incomparable. A valuable thyroid ultrasound (US) dataset is presented in this work. This dataset consists of 2450 thyroid US images from 2018 to 2020 in Prospective Epidemiological Research Studies in Mashhad, Iran (PERSIAN), a large national cohort study. These US images have the ROI of thyroid nodules and the associated American College of Radiology (ACR) Thyroid Imaging Reporting and Data System (TIRADS) features by expert physicians provided in XML format. Dataset's images are categorized into five groups based on the ACR-TIRADS (Tirads1-Tirads5). The presented dataset is expected to be a valuable resource to develop and assess thyroid CAD systems to help radiologists better diagnose.

Bone scan with technetium 99m-methyl diphosphonate, the missing link in the initial staging of muscle-invasive bladder carcinoma.

BACKGROUND: Accurate staging is crucial to determine the type of treatment for patients with bladder cancer (BCa), especially in high-risk cases. We aimed to assess the role of bone scan in the initial staging of muscle-invasive bladder carcinoma (MIBC). MATERIAL AND METHODS: Forty-five patients with MIBC were referred to our tertiary clinic to perform a technetium 99m-methyl diphosphonate (Tc99m-MDP) bone scan from January 2019 to March 2020. The patients underwent bone scintigraphy with pelvic SPECT/CT before radical cystectomy. Whole-body scanning was performed 4 hours after Tc99m-MDP injection in both anterior and posterior views. Since the most common bone involvement site in these patients is the pelvic bones and the spine, pelvic SPECT/CT was performed in all patients. RESULTS: Frequency of skeletal metastasis was 26.7%. Only 19% of the metastases were detected by previous pelvic CT/MRI images performed for routine staging. All the reported skeletal metastases by previous anatomical imaging methods were detected in the bone scan. There was no statistically significant correlation between bone metastasis and the patient's age, lymph nodes metastasis (LNM), hydronephrosis, and muscle-invasive type. The mean serum calcium level was 8.7 ± 0.57 in patients with bone metastasis and 8.87 ± 0.99 in patients without bone metastasis, which was not statistically significant. CONCLUSION: Bone scan has higher diagnostic performance than conventional imaging methods for detecting bone metastases. It changed the management plan in 8.8% of our patients, so we conclude that performing a whole-body bone scan in the initial staging of MIBC would be helpful.

Observation Variation in Ultrasonography Assessment of Thyroid Nodules.

OBJECTIVES: Accurate detection and competent management of thyroid nodules, as a common disease, basically depends on the reliability of the ultrasonography (US) report. In this research, we evaluated inter and intra-observer variation among ultrasonography reporters, based on ACR-TIRADS. METHODS: In this retrospective study, 345 thyroid US images of 150 patients were reviewed. Three clinicians with at least 6-year experience in thyroid US reviewed the images twice at 6-8 weeks' intervals. Composition, echogenicity, shape, margin, and echogenic foci based on ACR-TIRADS were reported, independently. Inter and intra-observer variations were calculated based on Cohen's Kappa statistics. RESULTS: 345 ultrasonography images of 150 patients with thyroid nodules (83 women and 67 men) with a mean age of 65 years were reviewed. Moderate to the substantial intra-observer agreement was achieved with the highest Kapa value in the category of shape (k=0.61-0.77). For TIRADS level, the moderate intra-observer agreement was observed (k=0.42-0.46). Inter-observer agreement for the US category of thyroid nodules was obtained slightly to moderate. Composition (k=0.42 and 0.51) and echogenicity (k=0.45 and 0.46) showed the highest overall agreement and margin showed the lowest overall agreement (k=0.18 and 0.19). In assessing TIRADS level of nodules, a fair agreement was obtained (k=0.23 and 0.29). CONCLUSION: Moderate to substantial intra-observer agreement and slight to moderate inter-observer variation for evaluation of thyroid nodules; shows the need for a computer-aided diagnosis system based on artificial intelligence to assist our physicians in differentiating thyroid nodule characteristics based on explicit image features. An additional training course based on ACR-TIRADS for physicians can be another useful recommendation.

Bone metastasis from noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP); a case report.

BACKGROUND: The term non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) was recently proposed as a non-malignant thyroid lesion with indolent behavior that does not require post-operative radio-iodine treatment. We are reporting a case of NIFTP with bone metastasis that is the second case reported so far. CASE PRESENTATION: We describe a 38-year-old woman who presented with an indeterminate thyroid nodule and underwent total thyroidectomy with the finding of NIFTP on careful pathologic examination. However, her initial follow-up evaluation revealed a serum thyroglobulin level of > 300 ng/ml and a diagnostic whole body 131I scan demonstrated a focus of increased uptake in the left hemipelvis, confirmed on CT scan to be a lytic lesion in the left iliac bone. She was treated with 7.4GBq (200 mCi) of 131I and her follow-up 1 year later revealed an undetectable serum thyroglobulin and a negative whole body 131I scan with no visible uptake in the iliac bone indicating an excellent response. CONCLUSION: This case presentation reminds us to be alert to the rare occurrence of distant metastasis in NIFTP and the need for a case by case analysis and continuing post-operative follow-up for detection of residual or recurrent disease.

Incidental finding of a dermoid cyst in a whole-body iodine scan: importance of using [131I]SPECT/CT in the differentiated thyroid carcinoma.

A 33-year-old female with a history of total thyroidectomy for papillary thyroid carcinoma was referred to the nuclear medicine department for ablative radioiodine therapy. Post ablation scan showed an area of intense iodine uptake on the left side of the pelvic region, corresponding to the large well-defined heterogeneous mass in the left ovary in the SPECT/CT images. The radiologic features of this lesion were compatible with a dermoid cyst, previously unrecognized. Eventually, the lesion was laparoscopically removed, and a typical dermoid cyst was confirmed through histopathologic assessment.

Longer Time to Reach Excellent Response to Treatment in Familial Versus Sporadic Non-medullary Thyroid Cancer (NMTC): A Matched Case-Control Study.

BACKGROUND: Familial non-medullary thyroid cancer (NMTC) are supposed to be more aggressive and require more frequent treatment compared to non-familial thyroid cancer. OBJECTIVES: This matched case-control study aimed to compare the response to treatment between the matched case-control groups of familial and sporadic NMTC. METHODS: This is a retrospective study in patients with familial NMTC (at least one other first-degree relative involved) who were treated with surgery, followed by radio-iodine therapy (RIT) without consideration of its familial origin. Response to treatment was compared between familial NMTC and age, sex, and TNM stage-matched non-familial NMTC (control group). Response to treatment was assessed one and two years after RIT, and time to excellent response was identified. RESULTS: Out of 2,944 NMTC patients, 81 (2.75%) patients had familial NMTC. We compared 66 patients with familial NMTC and 66 sporadic NMTC patients. There was no significant difference in first thyroglobulin, initial and accumulative iodine dose, and additional treatments (additional surgery and radiotherapy) between patients and controls. Although no significant difference was noted in one and two years' responses to treatment between the case and control groups, familial NMTC patients required more time to achieve excellent response (26.7 ± 24.9 versus 15.9 ± 9.0 months, P = 0.01). No significant difference was noted between familial NMTC patients with two or more than two involved relatives. CONCLUSIONS: Our study showed that if patients with familial NMTCs were treated in the same way as non-familial patients, the time to excellent response would be significantly longer, even when they have only one other involved relative.

The burden and predisposing factors of non-communicable diseases in Mashhad University of Medical Sciences personnel: a prospective 15-year organizational cohort study protocol and baseline assessment.

BACKGROUND: The rising burden of premature mortality for Non-Communicable Diseases (NCDs) in developing countries necessitates the institutionalization of a comprehensive surveillance framework to track trends and provide evidence to design, implement, and evaluate preventive strategies. This study aims to conduct an organization-based prospective cohort study on the NCDs and NCD-related secondary outcomes in adult personnel of the Mashhad University of Medical Sciences (MUMS) as main target population. METHODS: This study was designed to recruit 12,000 adults aged between 30 and 70 years for 15 years. Baseline assessment includes a wide range of established NCD risk factors obtaining by face-to-face interview or examination. The questionnaires consist of demographic and socioeconomic characteristics, lifestyle pattern, fuel consumption and pesticide exposures, occupational history and hazards, personal and familial medical history, medication profile, oral hygiene, reproduction history, dietary intake, and psychological conditions. Examinations include body size and composition test, abdominopelvic and thyroid ultrasonography, orthopedic evaluation, pulse wave velocity test, electrocardiography, blood pressure measurement, smell-taste evaluation, spirometry, mammography, and preferred tea temperature assessment. Routine biochemical, cell count, and fecal occult blood tests are also performed, and the biological samples (i.e., blood, urine, hair, and nail) are stored in preserving temperature. Annual telephone interviews and repeated examinations at 5-year intervals are planned to update information on health status and its determinants. RESULTS: A total of 5287 individuals (mean age of 43.9 ± 7.6 and 45.9% male) were included in the study thus far. About 18.5% were nurses and midwives and 44.2% had at least bachelor's degree. Fatty liver (15.4%), thyroid disorders (11.2%), hypertension (8.8%), and diabetes (4.9%) were the most prevalent NCDs. A large proportion of the population had some degree of anxiety (64.2%). Low physical activity (13 ± 22.4 min per day), high calorie intake (3079 ± 1252), and poor pulse-wave velocity (7.2 ± 1.6 m/s) highlight the need for strategies to improve lifestyle behaviors. CONCLUSION: The PERSIAN Organizational Cohort study in Mashhad University of Medical Sciences is the first organizational cohort study in a metropolitan city of Iran aiming to provide a large data repository on the prevalence and risk factors of the NCDs in a developing country for future national and international research cooperation.

Effect of Different 131I Dose Strategies for Treatment of Hyperthyroidism on Graves' Ophthalmopathy.

PURPOSE: The study aims to define the effect of different dose strategies on ophthalmic complications in patients with Graves' disease (GD). METHODS: All the patients with GD and no or inactive ophthalmopathy (clinical activity score; CAS < 3) underwent Snellen chart examination, measurement of proptosis, thyroid volume, and radioactive iodine uptake, and randomized into 1 of 3 groups. In group 1, all the patients received fixed low dose (FLD) of 259 MBq of I, whereas in group 2, all the patients received fixed high dose (FHD) of 555 MBq, and in group 3, calculated dose (CD) was administered to deliver 5.55 MBq/g (thyroid weight) of I. All examinations were repeated 6 months after treatment. The measurement of thyroid function tests and clinical examination were repeated after 12 months. RESULTS: We studied 92 patients (58 female and 34 male) with mean age of 38.2 ± 12.0 years. Overall, 29, 32, and 31 patients were studied in FLD, FHD, and CD groups, respectively. The patients in CD received a mean activity of 240.5 MBq. The 3 groups were not significantly different regarding age, sex ratio, radioactive iodine uptake, smoking, visual acuity, and proptosis. The response rate 12 months after radioactive iodine therapy was 66.7%, 94.4%, and 92.9% in FLD, FHD, and CD groups, respectively (P = 0.05). Overall, CAS was increased significantly after treatment. Delta proptosis and delta CAS were increased significantly in FHD group compared with other groups (P < 0.05). The highest increment in proptosis was seen in FHD group. CONCLUSIONS: The administration of 5.55 MBq/g of I has fewer ophthalmic complications compared with high fixed dose model and is more effective than low fixed dose strategy.

Direct comparison of 99mTc-PSMA SPECT/CT and 68Ga-PSMA PET/CT in patients with prostate cancer.

OBJECTIVES: 99mTc-PSMA SPECT/CT is a cost effective alternative for 68Ga-PSMA PET/CT. The aim of this study was to directly compare these two techniques in patients with prostate cancer. METHODS: 28 man with prostate cancer were studied using 99mTc-PSMA SPECT/CT and 68Ga-PSMA PET/CT in a short time period (<60 days). No intervention was done between the studies. Whole body PET/CT was done 60 minutes after IV injection of 2 MBq/Kg of 68Ga-PSMA. 99mTc-PSMA kit (PSMA I+S) was used for SPECT/CT and whole body imaging was performed 4 hours after IV injection of 740 MBq of 99mTc-PSMA. Images were interpreted independently and the results of each imaging were recorded. RESULTS: The mean age of the patients was 64.7±9.6 years old and the mean time difference between two sets of images was 16.6±13.5 days. Abnormal uptake was seen in 25 (89.2%) patients by 68Ga-PSMA PET/CT and 20 (71.4%) patients with 99mTc-PSMA SPECT/CT. No patients with positive 99mTc-PSMA SPECT/CT had negative 68Ga-PSMA PET/CT. The mean number of detected lesions was 26.07±27.5 by 68Ga-PSMA PET/CT and 10.52±10.99 by 99mTc-PSMA SPECT/CT (P<0.001). Detection of lymph nodes and bone metastases were not significantly different between two sets of imaging (P>0.05), however 68Ga-PSMA PET/CT were more successful in detection of prostate bed lesions compared to 99mTc-PSMA scan. Interestingly, no patient with PSA level of >2.1 ng/ml had discordant result between two sets of images. CONCLUSION: 99mTc-PSMA SPECT/CT is as accurate as 68Ga-PSMA PET/CT in M staging, however 68Ga-PSMA PET/CT detected more lesions compared to 99mTc-PSMA SPECT/CT. Detection rate was not significantly different between two techniques in patients with PSA levels>2.1 ng/ml.

Investigating the prevalence of risk factors of papillary thyroid carcinoma recurrence and disease-free survival after thyroidectomy and central neck dissection in Iranian patients.

Background: Papillary thyroid carcinoma (PTC) is considered the most frequent thyroid malignancy (85-90%) with a good prognosis. However, its frequent recurrence increases mortality and morbidity. In this inquiry we investigated the prevalence of risk factors of PTC recurrence and disease free survival after thyroidectomy and central neck dissection. Method: In this retrospective study, all patients with confirmed PTC who underwent total thyroidectomy and central neck dissection in Imam Reza and Omid hospitals of Mashhad University of Medical Sciences from 2004 to 2011 were included. Total locoregional and distant recurrence rate, 5-year disease free survival rate (DFS) and contributing factors of recurrence were investigated after at least 5 years. Results: In this study 289 patients were included with a mean follow-up of 72.90 ± 11.02 months. 70.6% were female and 29.4% were male. Recurrence occurred in 58 cases from which 10 were distant and 48 were loco-regional. 5-year DFS was 80% and total-survival-rate was 99%. Our analysis showed that primary tumor size, vascular-invasion, extra-thyroid extension, and lymph node ratio (LNR) were significantly related to DFS.

Major dietary patterns and differentiated thyroid cancer.

BACKGROUND: Differentiated Thyroid Cancer (DTC) is the most common endocrine cancer with an increasing trend worldwide. Dietary pattern as a modifiable factor may be associated with DTC. OBJECTIVE: The present study aimed to evaluate the association between major dietary patterns and risk of DTC. METHODS: A case control study was conducted among 309 clinic-based participants in northeast of Iran. Dietary data were then collected by a validated Food Frequency Questionnaire (FFQ). Further, codified data were analyzed by factor analysis and logistic regression analysis to identify the dietary patterns and to examine the association between dietary patterns and DTC, respectively. RESULTS: According to our results, four major dietary patterns including western dietary pattern, traditional dietary pattern, transitional dietary pattern, and healthy dietary pattern were identified. The western dietary pattern was associated with increased odds of DTC after adjustment for potential confounders (OR = 2.79, 95% CI: 1.01-7.74). However, there was no association between other dietary patterns and DTC after adjustment. CONCLUSIONS: In conclusion, the findings showed that western dietary pattern might be associated with DTC. Further studies are recommended to provide more conclusive evidences about the association between dietary patterns and DTC.

The assessment of radio-adaptive response in graves' hyperthyroidism patients following radioactive iodine uptake.

Low doses of radiation affect the response of cells to higher doses; this phenomenon is called radio-adaptive response, which leads to increased resistance to subsequent higher doses. We have investigated the adaptive response using 0.37 MBq priming dose of I-131 followed by 296-444 MBq challenging dose in peripheral human lymphocyte cells. The study was performed on 42 patients with Graves' disease and 29 healthy adult persons as a control group. The patients were divided into two groups. In the first group, patients were referred for radioactive iodine therapy with a specific dose, and iodine was given to them on the day of referral. In the second group, patients were referred for radioactive iodine uptake and radioactive iodine therapy, and iodine uptake was initially performed, then 24 h later, iodine therapy was done. In both groups, 1 month after treatment, blood samples were taken to cytokinesis-block micronucleus (MN) assay. The number of MN in binuclear lymphocyte cells was counted as an end point test. The mean frequency of MN in first, second, and control groups was 75.86 ± 12.68, 71.45 ± 12.56, and 20.06 ± 7.30, respectively. Our results showed that the frequency of total chromosome aberration in both radiation groups was higher than controls. However, in the first group was higher than another group, but their difference was not statistically significant. According to the results, we cannot approve the hypothesis that 0.37 MBq I-131 administration before iodine therapy could induce a radio-adaptive response in lymphocytes of Graves' patients.

Comparison of Treatment Response Achieved by Tablet Splitting Versus Whole Tablet Administration of Levothyroxine in Patients with Thyroid Cancer.

OBJECTIVES: TSH suppression by Levothyroxine consumption is a mainstay of thyroid cancer treatment. Tablet-splitting is a worldwide approach in dose adjustment in patients. However, it is highly recommended to evaluate the validity of tablet splitting for each distinctive drug by clinical trials before routinely using tablet halves in clinical practice. In this study we compared the effect of 150 µg dose of Levothyroxine by use of a100 and a 50 µg tablets or one and half 100 µg tablets in Differentiated thyroid cancer (DTC) patients. METHODS: One hundred DTC patients treated with one and half 100 µg Levothyroxine tablets were randomly divided into two groups. The first group continued taking medication as before and the second group received the same daily dose by taking one 100 and one 50 microgram Levothyroxine tablets. The mean changes in TSH and T3 levels and patients weight were compared between the groups. RESULTS: 91 patients completed the study. Levothyroxine consumption pattern, age, gender distribution, weight and TSH levels were comparable between groups at the beginning of the study. The mean change of body weights, serum levels of T3 and TSH showed no significant difference between groups in different time points during the study (P>0.05). CONCLUSION: This study showed similar efficacy of tablet splitting and two tablets administration for Levothyroxine; however, patients preferred two tablets at the end of the study. It can be concluded that tablet splitting can be used as an alternative way when the 50 µg tablet is not available.

Specific Absorbed Fractions of Internal Photon and Electron Emitters in a Human Voxel-based Phantom: A Monte Carlo Study.

The specific absorbed fraction (SAF) of energy is an essential element of internal dose assessment. Here reported a set of SAFs calculated for selected organs of a human voxel-based phantom. The Monte Carlo transport code GATE version 6.1 was used to simulate monoenergetic photons and electrons with energies ranging from 10 keV to 2 MeV. The particles were emitted from three source organs: kidneys, liver, and spleen. SAFs were calculated for three target regions in the body (kidneys, liver, and spleen) and compared with the results obtained using the MCNP4B and GATE/GEANT4 Monte Carlo codes. For most photon energies, the self-irradiation is higher, and the cross-irradiation is lower in the GATE results compared to the MCNP4B. The results show generally good agreement for photons and high-energy electrons with discrepancies within - 2% ±3%. Nevertheless, significant differences were found for cross-irradiation of photons of lower energy and electrons of higher energy due to statistical uncertainties larger than 10%. The comparisons of the SAF values for the human voxel phantom do not show significant differences, and the results also demonstrated the usefulness and applicability of GATE Monte Carlo package for voxel level dose calculations in nonuniform media. The present SAFs calculation for the Zubal voxel phantom is validated by the intercomparison of the results obtained by other Monte Carlo codes.

A 3D Monte Carlo Method for Estimation of Patient-specific Internal Organs Absorbed Dose for (99m)Tc-hynic-Tyr(3)-octreotide Imaging.

Single-photon emission computed tomography (SPECT)-based tracers are easily available and more widely used than positron emission tomography (PET)-based tracers, and SPECT imaging still remains the most prevalent nuclear medicine imaging modality worldwide. The aim of this study is to implement an image-based Monte Carlo method for patient-specific three-dimensional (3D) absorbed dose calculation in patients after injection of (99m)Tc-hydrazinonicotinamide (hynic)-Tyr(3)-octreotide as a SPECT radiotracer. (99m)Tc patient-specific S values and the absorbed doses were calculated with GATE code for each source-target organ pair in four patients who were imaged for suspected neuroendocrine tumors. Each patient underwent multiple whole-body planar scans as well as SPECT imaging over a period of 1-24 h after intravenous injection of (99m)hynic-Tyr(3)-octreotide. The patient-specific S values calculated by GATE Monte Carlo code and the corresponding S values obtained by MIRDOSE program differed within 4.3% on an average for self-irradiation, and differed within 69.6% on an average for cross-irradiation. However, the agreement between total organ doses calculated by GATE code and MIRDOSE program for all patients was reasonably well (percentage difference was about 4.6% on an average). Normal and tumor absorbed doses calculated with GATE were slightly higher than those calculated with MIRDOSE program. The average ratio of GATE absorbed doses to MIRDOSE was 1.07 ± 0.11 (ranging from 0.94 to 1.36). According to the results, it is proposed that when cross-organ irradiation is dominant, a comprehensive approach such as GATE Monte Carlo dosimetry be used since it provides more reliable dosimetric results.