Pitfalls of Iodine-131 Whole-Body Scan Mimicking Metastases in Differentiated Thyroid Carcinoma: A Case Series.

Thyroid cancer is the most common endocrine malignant tumor and accounts for 1% of all cancers. Management of differentiated thyroid carcinoma is total thyroidectomy, followed by iodine-131 (I-131) radioactive iodine (RAI) therapy for thyroid remnant tissue. I-131 whole-body scan helps in the follow-up evaluation in remnant, residual, and recurrence cases. Principle of uptake of I-131 is through sodium-iodide symporter expression on the cells. Physiological uptake of iodine is usually seen in salivary glands and gastrointestinal tract, and false-positive uptakes are seen in lesions such as mucinous cystadenoma, struma ovarii, hepatic, renal, thymic, and meibomian cysts. Here, we present the review of literature of series of cases observed in our department presenting with false-positive uptake of RAI in vertebral hemangioma, lipoma, sinusitis, teratoma, and uterine leiomyoma.

Technetium-99m Methoxyisobutyl Isonitrile Stress MPI in Suspected Coronary Artery Disease Patients: A Prospective Study to Evaluate Clinical Significance of Adenosine-induced ECG Changes.

Purpose: The purpose of this study is to evaluate the adenosine pharmacological stress-induced electrocardiogram (ECG) changes and their association with stress-induced ischemic defects on myocardial perfusion scintigraphy (MPS) in the evaluation of coronary artery disease (CAD) and to evaluate event-free survival among patients with positive and negative ECG/MPS image findings. Methods: A total of 100 patients were examined using stress MPS from March 2020 to August 2021. Stress-induced ECG changes during adenosine infusion were evaluated. The summed stress score (SSS) was evaluated to identify ischemic defects in myocardium. Association of stress ECG changes and scintigraphic results was evaluated. Results: Out of 100 patients, stress ECG changes during adenosine infusion were seen among 34 patients, whereas 66 patients had normal ECG findings. Positive stress MPS findings with SSS >3 were seen in 22 patients, whereas 78 patients had SSS ≤3. There was no agreement between stress ECG changes and MPS findings with Cohen's kappa coefficient (κ) = -0.023, whereas there was mild agreement between stress ECG changes and SSS >7 with κ = 0.105. Median follow-up of 11 months showed more events among patients with positive ECG changes than negative ECG changes. Conclusion: Adenosine, pharmacological stress is safe to use, but few patients might experience some minor and transient symptoms. Adenosine may induce ECG changes in patients with or without positive MPS findings. Patients with concordant positive findings need aggressive cardiac care, whereas patients with small or no defects on MPS need close monitoring.

Assessment of Gastric Dysmotility Using Standardized Tc-99m Sulfur Colloid-Labeled Rice Cakes in Diabetic Patients.

Background: Diabetes mellitus is a common lifestyle disease where patients suffer from gastric dysmotility, which is usually underdiagnosed. The aim of this study was to evaluate the utility of Tc-99m sulfur colloid-labeled meal gastric emptying scintigraphy in Type 2 diabetic patients. Methods: A total of 43 patients and 30 controls, satisfying the inclusion criteria from March 2019 to August 2020, were included. Serial planar images were acquired in both anterior and posterior projections for an iso-time of 1 min at 1 min, 60 min (1 h), 120 min (2 h), and 240 min (4 h) after consumption of Tc-99m SC-labeled idly (rice cakes). The gastric emptying was considered delayed if there was <10% emptying at 1 h, <70% emptying at 2 h, and <94% emptying at 4 h. Results: The mean T1/2 was similar among cases (44.11 ± 10.52 min) and controls (49.56 ± 13.44 min, P = 0.056) while the mean gastric emptying at 1 h was slower in cases compared to controls, P = < 0.01. Two cases (4.6%) had delayed gastric emptying while none of the controls had delayed gastric emptying. T1/2 showed no association with duration of diabetes or HbA1c levels (P = 0.76, 0.45) and a weak correlation with fasting blood sugar (FBS) on the day of scan (R value = 0.18). Conclusion: In comparison to controls, diabetic patients had faster gastric emptying with no association with duration of diabetes or HbA1c levels and a weak correlation with FBS on the day of scan.

Preparation of 177Lu-PSMA-617 in Hospital Radiopharmacy: Convenient Formulation of a Clinical Dose Using a Single-Vial Freeze-Dried PSMA-617 Kit Developed In-House.

OBJECTIVE: In the recent time, endoradionuclide therapy for metastatic castration-resistant prostate carcinoma employing 177Lu-PSMA-617 has yielded encouraging results and several clinical trials with the agent are currently ongoing. Routine preparation of 177Lu-PSMA-617 patient doses can be made simpler and convenient, if the ingredients essential for radiolabeling are made available in a ready-to-use lyophilized form. METHODS: PSMA-617 freeze-dried kit was formulated and used for the preparation of 177Lu-PSMA-617 clinical dose with high radiochemical purity using low/medium specific activity 177Lu. Detailed radiochemical studies were performed to determine the maximum activity and volume of 177LuCl3, which can be added in the kit for the formulation of 177Lu-PSMA-617. Studies were also performed to determine the shelf life of the kit to ensure its long-term usage. Studies were performed in buffer as well as human serum medium to determine the stability of the 177Lu-PSMA-617 complex after storing in respective media up to 7 days postpreparation. About ten patient doses of 177Lu-PSMA-617 were administered, and posttherapy scans were acquired. RESULTS: The formulated freeze-dried kit of PSMA-617 could be radiolabeled with an average percentage radiochemical purity > 98.53 ± 0.38. The freeze-dried kit was found suitable for tolerating up to 0.5 mL of 177LuCl3 (in 0.01 N HCl) and specific activity of 555 MBq/µg (15 mCi/µg) for the preparation of the patient dose of 177Lu-PSMA-617. The 177Lu-PSMA-617 complex prepared using the freeze-dried kit of PSMA-617 was observed to maintain % radiochemical purity (RCP) of 96.74 ± 0.87 and 94.81 ± 2.66, respectively, even after storing up to 7 days in buffer and human serum, respectively. 177Lu-PSMA-617 prepared using the in-house formulated freeze-dried kit of PSMA-617 exhibited accumulation in metastatic lesions picked up in a pretherapy PET scan. Reduction in number as well as size of lesions was observed in posttherapy scans acquired after two months of administering the first therapeutic dose of 177Lu-PSMA-617. CONCLUSIONS: The freeze-dried kit of PSMA-617 could be used for the preparation of 177Lu-PSMA-617 with high radiochemical purity (>98%) in a reproducible manner. 177Lu-PSMA-617 prepared using the developed kit was successfully evaluated in patients suffering from metastatic prostate cancer.

Utility of Short-Acting Intravenous Insulin Therapy in Preparation of F-18 Fluorodeoxyglucose Positron Emission Tomography Computed Tomography Scan in Cancer Patients Incidentally Detected with High Blood Glucose Levels on the Day of Test.

BACKGROUND: In diabetic (DM) patients, hyperglycemia degrades image quality in F-18 FDG PET CT by altering bio-distribution of FDG in the body and augmenting soft tissue and muscular uptake. We intend to evaluate the use of short acting I.V insulin in minimising the rescheduling of patients detected with FBG>160 mg/dL on the day of scan. AIM AND OBJECTIVES: To show the utility of short acting IV insulin therapy in preparation of cancer patients incidentally detected with high blood glucose levels for F-18 FDG PET CT scan, (>160mg/dL) and to compare the obtained image quality with patients detected with fasting blood glucose level (FBG) <100mg/dL and <160 mg/dL, using visual and semi quantitative methods. MATERIAL AND METHODS: 613 cancer patients referred for PET CT were divided into 3 groups, Group I (n=30): known diabetics (DM) or incidentally diagnosed with FBG >160 mg/dL, Group II (n=349): DM patients with FBG <160 mg/dL (100-160mg/dL), Group III (n=234): Non DM patients FBG <100mg/dL. In Group I short acting insulin was given intravenously using a sliding scale, post insulin after 90 minutes F-18 FDG (radiotracer) injection was given and PETCT scan was obtained 60 mins post radiotracer injection. Qualitative image analysis was done using biodistribution score and quantitative analysis was done by chi square test, ANOVA (analysis of variance) and paired t-test. RESULTS: In group I patients post insulin there was significant decrease in FBG levels (216±22.2 to 136±13.4mg/dL) and acceptable image quality. Comparison of quantitative parameters (mean and maximum SUV calculated by drawing ROI around brain, heart, liver, muscle, subcutaneous fat) among the 3 groups showed significant intergroup difference with p value <0.05. CONCLUSION: This short acting I.V insulin protocol is safe and can be used to obtain optimal quality F-18 FDG PET CT scan images by alleviating the need for rescheduling patients though they present with high glucose levels.

Papillary Carcinoma Thyroid Metastases Presenting as Thyrotoxicosis Post Thyroidectomy - A Case Report.

Thyrotoxicosis can occur in the setting of differentiated thyroid cancer due to functioning metastases. Here, we report a case of a 63 year old woman with papillary carcinoma thyroid who underwent total thyroidectomy and defaulted for further scheduled treatment with high dose radioactive iodine therapy. 2 years after total thyroidectomy, she presented with signs and symptoms of thyrotoxicosis and a scalp swelling on the right side of frontal region. Excision biopsy revealed metastatic deposits of papillary carcinoma thyroid. Even after withdrawal of thyroxine, her serum thyrotropin did not rise and thyroglobulin levels were high, raising the suspicion of high volume tumour burden. I-131 whole body scan was done and it revealed radio iodine avid cervical lymph nodes along with functioning lung and skeletal metastases.