Positron Emission Tomography Radiopharmaceuticals in Differentiated Thyroid Cancer.

Differentiated thyroid cancer (DTC), arising from thyroid follicular epithelial cells, is the most common type of thyroid cancer. Despite the well-known utilization of radioiodine treatment in DTC, i.e., iodine-131, radioiodine imaging in DTC is typically performed with iodine-123 and iodine-131, with the current hybrid scanner performing single photon emission tomography/computed tomography (SPECT/CT). Positron emission tomography/computed tomography (PET/CT) provides superior visualization and quantification of functions at the molecular level; thus, lesion assessment can be improved compared to that of SPECT/CT. Various types of cancer, including radioiodine-refractory DTC, can be detected by 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG), the most well-known and widely used PET radiopharmaceutical. Several other PET radiopharmaceuticals have been developed, although some are limited in availability despite their potential clinical utilizations. This article aims to summarize PET radiopharmaceuticals in DTC, focusing on molecular pathways and applications.

Precision and Effects of a Small Meal on DXA-Derived Visceral Adipose Tissue, Appendicular Lean Mass, and Other Body Composition Estimates In Nonobese Elderly Men.

BACKGROUND: Information on precision errors and the least significant change (LSC) of dual energy X-ray absorptiometry (DXA)-derived body composition estimates is scarce, particularly for the appendicular lean mass (ALM) and appendicular lean mass index (ALMI). Overnight fasting is recommended for body composition measurements but has not been well tolerated by some elderly patients. This study aimed to establish precision errors and LSC values of body composition estimates in all regions-including visceral adipose tissue (VAT) and ALM-and the ALMI to assess the effect of a small meal on body composition and to estimate the changes it incurred. METHODOLOGY: Our institutional review board approved the study protocol. Altogether, 36 non-obese men aged ≥60 years, having given written informed consent, underwent body composition assessment after fasting overnight except for water. They underwent DXA scans three times, each time with repositioning (to simulate the clinical setting), the last after consuming a standardized meal (210-250 g and 200 cc of water). RESULTS: Precision errors and LSC values of DXA-derived body composition estimates in these elderly men tended to be higher than those in reports on younger subjects. Coefficients of variation (CVs (%)) of total bone mass (Tb.BMC) and total lean mass (Tb.LM) were <1%, whereas those of total fat mass (Tb.FM) and total %fat mass (Tb.%FM) were <2%, with LSCs of 45.8 g, 706.52 g, 731.4 g, and 1.15%, respectively. The CVs (LSC) of VAT, ALM, and ALMI were 8.9% (150.65 g), 0.93% (501 g), and 0.94% (0.19), respectively. After meal consumption, the mean changes in Tb.FM, Tb.BMC, and Tb.LM were -100, -8.2, and 440 g, respectively. CONCLUSIONS: Effects of a small meal on most parameters were trivial, including those for VAT, ALM, and ALMI, where changes were not statistically significant. None exceeded the LSC of ALM and ALMI, suggesting that a small meal is allowable before these measurements.

Errors in Patient Positioning for Bone Mineral Density Assessment by Dual X-Ray Absorptiometry: Effect of Technologist Retraining.

Improper positioning is one of the factors that can lead to incorrect bone mineral density (BMD) results. This study aimed to assess the frequencies of erroneous positioning during three periods: before retraining of the technologists (BR), after retraining (AR), and at the current timepoint 8 years after retraining (C). The BMD images of the first 150 consecutive patients who underwent DXA of the lumbar spine and hip during each of the three periods were retrospectively reviewed. Patients were excluded if they had severe scoliosis, rendering proper positioning impossible. Each BMD image was assessed by an International Society of Clinical Densitometry certified clinical densitometrist who was blinded to the date of the initial examination. For the lumbar spine in the BR group, the criteria frequently not met were inclusion of both iliac crests (33.8%), straightness (30.3%), and midline positioning (20.4%); the respective frequencies were significantly reduced to 0.8%-5.6%, 2.1%-3.0%, and 0%-2.8% in the AR and C groups (p < 0.05). For the hip in the BR group, the criteria frequently not met were straightness (52.8%) and internal rotation (21.8%); the respective frequencies were significantly reduced to 0%-4.2% and 8.3%-8.4% in the AR and C groups (p < 0.05). Overall improper positioning in the BR group was 49.3% and 57.3% at the lumbar spine and the hip, respectively; the respective frequencies were reduced to 9.3% and 12.7% in the AR group, and to 2.7% and 7.3% in the C group. The least significant change values for the lumbar spine, femoral neck, and total hip also became smaller after retraining. Retraining the technologists improved patient positioning, as evidenced by the decreased frequencies of erroneous positioning and the improved least significant change values after the retraining.

Simulated increased soft tissue thickness artefactually decreases trabecular bone score: a phantom study.

BACKGROUND: Trabecular bone score (TBS), which has been proposed to be used in complementary with bone mineral density (BMD) to improve the assessment of fracture risk, is negatively associated with body mass index (BMI). The effect of soft tissue, which is expected to be thicker in subjects with high BMI, on TBS was studied using three scan types: Hologic with fast array mode (Hfa), Hologic with high definition mode (Hhd), and GE-Lunar iDXA. METHODS: A spine phantom provided by Hologic for routine quality control procedure was scanned using three scan types: Hfa, Hhd, and iDXA. The phantom was scanned with an overlying soft tissue equivalent material (bolus used in radiotherapy) of 0 (without), 1, 2.5, 3.5, 5 and 7.5 cm thick. For each setting, 30 acquisitions were performed in the same way as for the quality control procedure. TBS was calculated using TBS iNsight® software version 2.1 on the same regions of interest as those used for lumbar spine BMD. RESULTS: Mean ± SD TBS of the phantom (without overlying soft tissue) were 1.379 ± 0.018, 1.430 ± 0.009, and 1.423 ± 0.005 using Hfa, Hhd, and iDXA, respectively. A one-way repeated measures ANOVA showed that there were statistically differences in TBS due to different thicknesses of soft tissue equivalent materials for all three scan types (p < 0.001). A Tukey post-hoc test revealed that the decrease in TBS was statistically significant (p < 0.001) when the soft tissue thickness was 1 cm (-0.0246 ± 0.0044, -0.0319 ± 0.0036, and -0.0552 ± 0.0015 for Hfa, Hhd, and iDXA, respectively). Although to a lesser degree, the effects were also statistically significant for BMD (p < 0.05): an increase for Hfa and Hhd but a decrease for iDXA. However, these changes did not exceed the least significant change (LSC) derived from patients. CONCLUSIONS: Increased soft tissue thickness results in lower TBS value. Although BMD is also affected, it is unlikely to pose a clinical problem because the change is unlikely to exceed the patient-derived LSC.

131I-rituximab treatment in patient with relapsed non-Hodgkin's lymphoma: the first case report in Thailand.

Radioimmunotherapy (RIT) with 131-rituximab is a safe and effective treatment in patients with relapsed, refractory follicular lymphoma. The authors demonstrated the first case of 131-rituximab treatment in the patient with relapsed non-Hodgkin's lymphoma (NHL) in Thailand. There was no immediate complication after treatment. Impressive treatment response occurred.

Cutaneous Management after Extravasation of High-Concentrated Amino Acid Solution Administered for Renal Protection in PRRT.

High-concentrated amino acid solution is used to protect the kidneys during peptide receptor radionuclide therapy (PPRT) in patients with neuroendocrine tumors (NETs). Extravasation of the solution can cause cutaneous complications. In this study, we described a 66-year-old man with metastatic medullary thyroid cancer and a 32-year-old woman with metastatic pancreatic NET who developed cutaneous lesions caused by the extravasation of an amino acid solution (25 g of lysine and 25 g of arginine in 1 L of normal saline) during PRRT with [177Lu]Lu-DOTA-TATE. Both were treated conservatively, and these cutaneous lesions gradually improved. The patient with metastatic pancreatic NET rejected the amino acid infusion in subsequent cycles of PRRT and therefore received [177Lu]Lu-DOTA-TATE alone, and her serum creatinine level and estimated glomerular filtration rate (eGFR) remained normal for 2 months after the last treatment. These two cases revealed cutaneous complications resulting from high-concentrated amino acid solution during PRRT because of hyperosmolarity. Health care providers should be aware of this complication to ensure its prevention and appropriate management. Preserved renal function was demonstrated after [177Lu]Lu-DOTA-TATE treatment in the absence of the infusion of a high-concentrated amino acid solution. However, long-term follow-up of renal function is suggested.

Risk-stratified papillary thyroid microcarcinoma: post-operative management and treatment outcome in a single center.

PURPOSE: This article aims to review and assess the post-operative management and treatment outcomes of papillary thyroid microcarcinoma (PTMC) in risk-stratified patients. METHODS: We retrospectively analyzed the data of PTMC patients who underwent thyroid surgery with or without radioactive iodine treatment (RAI) in a single center between January 2011 and December 2017. Demographic and clinicopathologic data were collected. Risk stratification according to the 2015 American Thyroid Association guideline was applied. RESULTS: Three hundred forty PTMC patients were included. Post-operative RAI was performed in 216/340 (63.53%) patients. In the non-RAI scenario, there were 122 low-risk and two intermediate-risk patients. In total, 261 (76.77%), 57 (16.76%), and 22 (6.47%) patients were classified as low, intermediate, and high risk, respectively. With a median follow-up time of 36 months (interquartile range: 23, 52), we found unfavorable outcomes (evidenced by imaging or out-of-range serum tumor marker levels: high thyroglobulin [Tg] or rising Tg antibody [TgAb] levels) in 8/340 (2.35%) patients, all of which received RAI. PTMC patients with unfavorable outcomes were stratified as low risk (4/261 [1.53%]), intermediate risk (1/57 [1.75%]), or high risk (3/22 [13.64%]). One death occurred in a patient with initial distant metastasis in the high-risk group. Initial high-risk stratification and initial stimulated Tg (of at least 10 ng/mL) were demonstrated as independent predictors for PTMC unfavorable outcomes (persistent or recurrent disease). Five patients with unfavorable outcomes (four with persistent disease and one with recurrent disease) had abnormal Tg or TgAb values despite unremarkable imaging findings. Moreover, 79/124 (63.71%) patients in the non-RAI scenario were only followed up with neck ultrasound. CONCLUSIONS: In general, at least 98% of low-risk and intermediate-risk PTMC patients showed favorable outcomes without persistent or recurrent disease, defined by either imaging or serum tumor markers. Nevertheless, aggressive disease could occur in few PTMC patients. Decisions on post-operative management and follow-up may be guided by initial high-risk stratification and initial stimulated Tg levels (≥10 ng/mL) as independent predictors for PTMC unfavorable outcomes. Monitoring using both imaging and serum tumor markers is crucial and should be implemented for patients with PTMC.

Biopsy versus FDG PET/CT in the initial evaluation of bone marrow involvement in pediatric lymphoma patients.

PURPOSE: The objective is to assess the role of (18)F-2-fluoro-2-deoxy-D: -glucose (FDG) positron emission tomography (PET)/CT versus bone marrow biopsy (BMB) in the initial evaluation of bone marrow (BM) involvement in pediatric lymphoma patients. METHODS: Fifty-four pediatric patients with pathologically proven lymphoma [31 Hodgkin's disease (HD), 23 non-Hodgkin's lymphoma (NHL)] were included in this study. All patients had soft tissue biopsy and BMB and had FDG PET/CT scans within 2 weeks of biopsy. RESULTS: Among the 31 HD patients, FDG PET/CT revealed positive BM involvement in 4 patients, while BMB revealed BM involvement in 2 patients who were also positive on FDG PET/CT imaging. Among the 23 NHL patients, FDG PET/CT revealed positive BM involvement in 8 patients, while biopsy revealed BM involvement in 5 patients on initial studies (4 of them were also positive on FDG PET/CT, and 1 was BMB positive but was negative on FDG PET/CT), plus 1 false-negative BMB study initially but positive on repeat biopsy after FDG PET/CT. The overall sensitivity of detecting BM involvement by lymphoma was 92 and 54% (p < 0.05) for FDG PET/CT and BMB, respectively. It is noted that there were more positive BMB findings in patients with abnormal FDG activities seen in the biopsy sites on PET/CT. CONCLUSION: Our study demonstrates that FDG PET/CT has high sensitivity and accuracy and a substantial complementary value to BMB in the initial diagnosis of pediatric lymphoma, and should be employed as a first-line study.

Myxedema Psychosis after Levothyroxine Withdrawal in Radioactive Iodine Treatment of Differentiated Thyroid Cancer: A Case Report.

Neuropsychiatric symptoms, especially acute psychosis (often referred to as myxedema madness or psychosis), are rare but possible clinical presentations of patients with hypothyroidism. A 42-year-old woman with papillary thyroid carcinoma and recent total thyroidectomy had developed flat affect, paranoid delusion, and visual and auditory hallucination during inpatient admission for elective radioactive iodine treatment. On admission, her history and physical exam did not reveal symptoms and signs of significant hypothyroidism. Other medical causes of acute psychosis were excluded, and the patient was immediately treated with thyroid hormone replacement therapy. Subsequently, her thyroid function normalized, and her psychotic symptoms gradually improved. Although there is a lack of classic signs and symptoms of hypothyroidism, myxedema madness should be recognized as one of the potentially treatable causes of acute psychosis.

Thai National Guideline for Nuclear Medicine Investigations in Epilepsy.

Epilepsy is a disorder of the brain, which is characterized by recurrent epileptic seizures. These patients are generally treated with antiepileptic drugs. However, more than 30% of the patients become medically intractable and undergo a series of investigations to define candidates for epilepsy surgery. Nuclear Medicine studies using Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET) radiopharmaceuticals are among the investigations used for this purpose. Since available guidelines for the investigation of surgical candidates are not up-to-date, The Nuclear Medicine Society of Thailand, The Neurological Society of Thailand, The Royal College of Neurological Surgeons of Thailand, and The Thai Medical Physicist Society has collaborated to develop this Thai national guideline for Nuclear Medicine study in epilepsy. The guideline focuses on the use of brain perfusion SPECT and F-18 fluorodeoxyglucose PET (FDG-PET), the mainly used methods in day-to-day practice. This guideline aims for effective use of Nuclear Medicine investigations by referring physicians e.g. epileptologists and neurologists, radiologists, nuclear medicine physicians, medical physicists, nuclear medicine technologists and technicians.

PET/Computed Tomography in the Evaluation of Fever of Unknown Origin and Infectious/Inflammatory Disease in Pediatric Patients.

Fever in children is common. If it persists and its cause cannot be identified in a reasonable time, along with laboratory and conventional imaging investigations, it is defined as fever of unknown origin (FUO). 18F-fluorodeoxyglucose (FDG) PET/computed tomography (CT) is well established in the evaluation of malignancy, which is a possible cause of FUO. FDG often locates inflammatory and infectious lesions considered nonspecific or false-positive for oncology; however, these findings are beneficial in FUO evaluation because infectious and inflammatory diseases are important FUO causes. FDG-PET/CT is being increasingly used for investigation of FUO as well as infectious/inflammatory disease.

Incidental breast lesion detected by technetium-99m sestamibi scintigraphy in a patient with primary hyperparathyroidism.

Nuclear scintigraphy is functional imaging and can be combined with anatomical imaging to improve diagnostic yield. Detection of parathyroid lesion by technetium-99m methoxyisobutylisonitrile (Tc-99m MIBI) can facilitate an appropriate operative approach in a patients with primary hyperparathyroidism. Tc-99m MIBI is concentrated in highly cellular or metabolically active tissues, which have abundant mitochondria. False-positive scintigraphic findings could be from head-and-neck carcinomas, thyroid neoplasm, and multinodular goiter. In addition, multiple organs outside of the neck region, such as lung and breast, can take up the Tc-99m MIBI. Herein, we report the occurrence of abnormal focal uptake in the breast region during the preoperative localization of parathyroid adenoma and later discovered breast carcinoma.

Cost-effectiveness analysis of epilepsy surgery in children and adolescents with drug resistant focal epilepsy at three years in a tertiary care epilepsy center in Thailand.

Epilepsy surgery is proven as a cost-effective treatment in developed countries, especially in adults with drug resistant epilepsy (DRE). This study is aimed to demonstrate the cost-effectiveness of epilepsy surgery in children and adolescents with DRE at three years compared with those who were eligible for surgery but received medical treatment. This study was conducted from January 2014 to December 2018. Clinical data were obtained from a retrospective chart review. Direct medical costs, including epilepsy surgery, inpatient and outpatient treatment were retrieved from the finance department. Direct non-medical costs were collected from the family interview. The effectiveness was determined by percent seizure reduction and quality of life assessed by EQ-5D scores. Decision tree analysis using TreeAge Pro® 2018 was deployed to determine the cost-effectiveness. Seventeen patients had epilepsy surgery and 19 were in the medical group. Seizure freedom was noted in 52% and 16% in the surgical and medical groups, respectively. Incremental cost-effectiveness ratio (ICER) was 743,040 THB (22,793 USD) per 1 QALY and 3302 THB (101 USD) per 1% seizure reduction. The study did not demonstrate cost-effectiveness of epilepsy surgery in the short term compared with Thailand's threshold (160,000 THB (4908 USD) per 1 QALY). Epilepsy surgery may be cost-effective if evaluated beyond three years.

Iodine-131 metaiodobenzylguanidine (131I-mIBG) treatment in relapsed/refractory neuroblastoma.

BACKGROUND: I-meta-iodo-benzylguanidine (I-mIBG) therapy has been used in treatment of for advanced neuroblastoma for many years with promising results. There are several studies regarding predictors and outcomes of I-mIBG therapies in relapsed/refractory neuroblastoma patients. OBJECTIVE: To identify the predictors and outcomes of I-mIBG treatment in relapsed/refractory neuroblastoma. METHODS: This study was a retrospective review of 22 patients with high risk stage IV relapsed/refractory neuroblastoma who received at least one cycle of I-mIBG therapy. Patient' characteristics, hematologic toxicity, scintigraphic semi-quantitative scoring, and overall survival were recorded. Factors predicting survival were analyzed. RESULTS: Twenty-two patients (50% male) with mean age of 3.7 years (4.8 months to 8.3 years) received I-mIBG therapies at an average of 3.8 and mean dose of 136 mCi (5032 MBq) per treatment. Most common acute hematologic toxicity was thrombocytopenia. Overall 5-year survival rate was 37% (95% confidence interval: 16.3-58.0) and median survival time was 2.8 year (95% confidence interval: 1.38-6.34). Patients with rising Curie score of ≥25% upon the second therapy were major determinants of overall survival with poorer response to treatment. At least three treatments of I-mIBG were needed to identify some degrees of survival prolongation (crude hazard ratio: P-value = 0.003). Age, sex, metastatic status, and baseline Curie scoring system were good predictors associated with survival. Seven patients (32%) demonstrated objective responses. CONCLUSION: Despite multimodality therapy, high risk neuroblastoma had a propensity of treatment failure in terms of relapsed or refractory, with some objective responses after I-mIBG treatments. The declined or non-rising Curie score upon second post-treatment total body scan was an important predictor of survival and aided a decision whether or not to proceed with bone marrow transplantation.

Usefulness of non attenuation corrected 18F-FDG-PET images for optimal assessment of disease activity in patients with lymphoma.

This study aimed at determining whether non attenuation corrected (NAC) positron emission tomography (PET) images, in addition to the attenuation corrected (AC) PET images, should be included in the interpretation of fluoro-18 fluorodeoxyglucose ((18)F-FDG-PET) images in patients with lymphoma. The study included 58 patients, 35 males 23 females, mean age 55+/-16 years. There were 64 superficial and 170 deep lymph node (LN) lesions. Lesion detection, uptake intensity using a three-point scale (1-mild, 2-moderate, 3- intense) and overall clarity of each lesion were compared on both PET images. Our results showed that the detection rate for superficial LN was 100% for NAC-PET and 98.4% for AC-PET images. The degree of (18)F-FDG uptake (intense, moderate and mild uptake) was 56.3%, 31.3% and 12.5% for NAC-PET images and 23.4%, 34.4% and 40.6% for AC-PET images, respectively. The overall image clarity was significantly in favor of NAC compared to AC-PET images (89% vs 20%, P<0.01). For deep LN, lesions, detection rate was for NAC and AC-PET images 95.3% and 99.4%, respectively. (18)F-FDG uptake intensity (intense, moderate and mild uptake) was 42.4%, 27.1% and 25.9% for NAC and 52.4%, 43% and 4.1% for AC-PET images, respectively. The overall image clarity for AC-PET images was superior to NAC-PET images (81.8% vs 53% P=0.01). In conclusion, NAC-PET images appeared to be superior to AC-PET images in detecting superficial LN lesions. AC-PET images are superior to NAC-PET images with regard to the deep-seated LN lesions. Therefore, AC and NAC-PET images are complimentary to each other and require to be reviewed together in the evaluation of patients with lymphoma.

Age-related changes in the metabolic activity and distribution of the red marrow as demonstrated by 2-deoxy-2-[F-18]fluoro-D-glucose-positron emission tomography.

OBJECTIVES: The objective of the study was to determine age-related changes occurring in red marrow with regard to its distribution and the degree of its metabolic activity by whole-body 2-deoxy-2-[F-18]fluoro-D-glucose (FDG)-positron emission tomography (PET). METHODS: This retrospective study included 112 patients (56 male, 56 female, mean age 40 years, range 2-85) who underwent whole-body FDG-PET scans for assessment of disorders that were determined not to affect red marrow activity. These patients were categorized into the following groups with equal gender distribution: 0-15 years (12 individuals), 16-25 years (20), 26-35 years (10), 36-45 years (20), 46-55 years (14), 56-65 years (16), 66-75 years (14), and 76-85 years (6). Whole-body FDG-PET images were performed at 60 min after the intravenous administration of 0.14 mCi/kg of FDG. By employing a dedicated whole-body PET scanner. Maximal standardized uptake value (SUV(max)) was calculated from three consecutive transverse sections of the upper thirds of the humeri and femora, manubrium of the sternum, 12th thoracic and 5th lumbar vertebra and anterior superior iliac crests of the pelvis. All available results from other imaging examinations [magnetic resonance imaging (MRI), computed tomography (CT), and conventional radiolography], laboratory data, biopsies, and the clinical course of these subjects were reviewed to make certain that the bone marrow sites examined were free of any known pathologies. RESULTS: SUV(max) in the extremities showed significant decline with aging (correlation coefficient of -0.60 to -0.67, p < 0.01). In contrast, a weak correlation was noted in the axial skeletal activity with advancing age (correlation coefficient of -0.28 to -0.48, p < 0.05). CONCLUSIONS: These data suggest that FDG metabolic activity of the red marrow in the extremities decline significantly with normal aging, while that of the axial skeleton show minimal decrease related to this biologic phenomenon. These findings are of value in assessing the effects of hematological and other disorders in the distribution and the metabolic activity of this important tissue and testing therapeutic interventions that are employed for treating such maladies.

Quantitative assessment of the atherosclerotic burden of the aorta by combined FDG-PET and CT image analysis: a new concept.

INTRODUCTION: Our objective was to develop a technique for quantifying the extent of atherosclerosis in the aorta by combining standard uptake values (SUVs) in the aortic wall with volumetric data provided by computed tomography (CT). METHODS: Eighteen patients who had both 18-fluorodeoxyglucose (FDG)-positron emission tomography (PET) and contrast-enhanced CT of the chest and abdomen were selected. All had homogeneous diffuse FDG wall uptake in four segments of the aorta. We divided the patients into three groups according to their age and measured FDG uptake in all four segments of the aorta by calculating the mean SUV for each segment. On each axial CT image, region-of-interest tracings along the inner and outer wall contours of the aorta were generated. The inner surface area was subtracted from the outer surface area. The net area values for each segment were subsequently multiplied by slice thickness to calculate arterial wall volume. By multiplying SUV with wall volume, we were able to calculate the atherosclerotic burden (AB) for each segment of the aorta. We compared the aortic wall volumes, SUVs and AB values in each arterial segment for each age group. RESULTS: In each aortic wall segment, AB values, SUVs and wall volumes increased with age (P<.05). CONCLUSION: AB can be used as an indicator of the extent of the atherosclerotic process in the aorta through the use of both metabolic and morphologic data provided by FDG-PET and CT, respectively. This may allow for the optimal screening, diagnosis and management of patients with this common and potentially lethal disorder.

Malignant lesions can mimic gastric uptake on FDG PET.

Gastric FDG uptake is a common observation on positron emission tomography (PET), which is most frequently caused by a nonmalignant etiology. However, a malignant lesion in the region of the stomach must not be overlooked. A 48-year-old woman with a history of melanoma in the esophagus and status postesophagectomy underwent FDG PET to evaluate for tumor recurrence. The images demonstrated hypermetabolism in the region of the location of the stomach. However, considering that the patient had a history of a stomach pullthrough procedure, we felt that this activity was nongastric and represented tumor recurrence, which was subsequently confirmed by computed tomography scan and histopathologic examination.

Incidental Gallbladder Cancer Visualized From Posttreatment 131I Whole-Body Scan.

A 72-year-old woman with papillary thyroid cancer post-total thyroidectomy was referred for post-I treatment whole-body scan. Images revealed focal uptake within the gallbladder. Cholecystectomy was subsequently performed, and the pathology report showed well-differentiated adenocarcinoma. Given a history of papillary thyroid cancer, the iodine uptake was reasonably explained as metastasis; however, gallbladder metastasis was extremely infrequent. Literature described the incidental radioiodine retention in the gallbladder as false-positive findings, which can be normal variants or benign hepatobiliary conditions. Primary gallbladder malignancy could be counted for another possibility despite controversial mechanism of uptake.