131 I Uptake in a Left Cerebral Infarct on Posttherapy Whole-Body Scan.

ABSTRACT: A 75-year-old woman with papillary thyroid carcinoma who underwent 131 I radioiodine treatment was incidentally found to have an established left cerebral infarct demonstrating 131 I uptake on posttherapy whole-body scan. False-positive iodine accumulation can occur in benign processes and other malignancies, necessitating awareness among nuclear medicine physicians to avoid misdiagnosing metastatic disease. SPECT/CT can be utilized to enhance diagnostic accuracy when needed.

"Seeing Is Believing": Additive Utility of 68Ga-PSMA-11 PET/CT in Prostate Cancer Diagnosis.

Widespread adoption of mpMRI has led to a decrease in the number of patients requiring prostate biopsies. 68Ga-PSMA-11 PET/CT has demonstrated added benefits in identifying csPCa. Integrating the use of these imaging techniques may hold promise for predicting the presence of csPCa without invasive biopsy. A retrospective analysis of 42 consecutive patients who underwent mpMRI, 68Ga-PSMA-11 PET/CT, prostatic biopsy, and radical prostatectomy (RP) was carried out. A lesion-based model (n = 122) using prostatectomy histopathology as reference standard was used to analyze the accuracy of 68Ga-PSMA-11 PET/CT, mpMRI alone, and both in combination to identify ISUP-grade group ≥ 2 lesions. 68Ga-PSMA-11 PET/CT demonstrated greater specificity and positive predictive value (PPV), with values of 73.3% (vs. 40.0%) and 90.1% (vs. 82.2%), while the mpMRI Prostate Imaging Reporting and Data System (PI-RADS) 4-5 had better sensitivity and negative predictive value (NPV): 90.2% (vs. 78.5%) and 57.1% (vs. 52.4%), respectively. When used in combination, the sensitivity, specificity, PPV, and NPV were 74.2%, 83.3%, 93.2%, and 51.0%, respectively. Subgroup analysis of PI-RADS 3, 4, and 5 lesions was carried out. For PI-RADS 3 lesions, 68Ga-PSMA-11 PET/CT demonstrated a NPV of 77.8%. For PI-RADS 4-5 lesions, 68Ga-PSMA-11 PET/CT achieved PPV values of 82.1% and 100%, respectively, with an NPV of 100% in PI-RADS 5 lesions. A combination of 68Ga-PSMA-11 PET/CT and mpMRI improved the radiological diagnosis of csPCa. This suggests that avoidance of prostate biopsy prior to RP may represent a valid option in a selected subgroup of high-risk patients with a high suspicion of csPCa on mpMRI and 68Ga-PSMA-11 PET/CT.

Ipsilateral Upper-Limb Lymphedema After COVID-19 Vaccine Booster.

ABSTRACT: Recent data suggest that protective immunity from COVID-19 vaccine may wane after a period, with booster doses becoming increasingly deployed in many countries. An 84-year-old woman presents with a 6-month history of left upper-limb swelling; the only history of note was an intramuscular Pfizer-BioNTech mRNA vaccine booster in the ipsilateral deltoid just 1 week before the onset of the swelling. Upper-extremity lymphoscintigraphy after the administration of 99m Tc-nanocolloid into the interstitial space of the hands showed left upper-limb lymphatic dysfunction.

Semi-quantitative indices of 2-[18F]FDG PET/CT in assessing cardiovascular and non-cardiovascular manifestations of IgG4-related disease and treatment response.

BACKGROUND: IgG4-related disease (IgG4-RD) is a heterogeneous autoimmune disorder characterised by inflammatory lesions. Diagnostic imaging, such as 2-[18F]FDG PET/CT, is critical in evaluation of the disease, especially for potentially lethal cardiovascular manifestations. This retrospective study examines the usefulness of semi-quantitative parameters of 2-[18F]FDG PET/CT in monitoring IgG4-RD in patients with and without cardiovascular manifestations. METHODS: Patients diagnosed with IgG4-RD who underwent a 2-[18F]FDG PET/CT scan were identified and classified based on presence or absence of cardiovascular disease. Clinical and laboratory data were extracted and compared to three 2-[18F]FDG PET/CT semi-quantitative parameters: maximum standardised uptake value (SUVmax), metabolic tumour volume (MTV), and total lesion glycolysis (TLG). Tissue-to-background blood (TBR) values were also evaluated for cardiovascular manifestations. These data were also compared in patients before and after receiving immunosuppressive therapy. RESULTS: Forty-six patients identified were divided into an eight member subgroup of patients with cardiovascular manifestations, and a thirty-eight member subgroup of patients without. Patients with cardiovascular lesions were most frequently identified incidentally on imaging evaluation for other diseases (37.5%), with none presenting with chest pain or other cardiovascular symptoms. Ten patients with pre-treatment and post-treatment 2-[18F]FDG PET/CT scans demonstrated significant decreases in all semi-quantitative parameters, with no significant decrease in total IgG or ESR. The decrease in SUVmax, MTV, TLG following therapy was replicated in patients with and without cardiovascular manifestations. CONCLUSION: 2-[18F]FDG PET/CT is an important investigation to determine all sites of involvement in this multisystemic disease and to rule out life-threatening cardiovascular manifestations even in the absence of symptoms. Semi-quantitative parameters such as SUVmax, MTV, TLG, and TBR are useful in assessing treatment response in patients. There are no serological substitutes that can quantify the extent of disease involvement like 2-[18F]FDG PET/CT.

Safety and efficacy of peptide receptor radionuclide therapy in patients with advanced pheochromocytoma and paraganglioma: A single-institution experience and review of the literature.

INTRODUCTION: Despite advances in diagnosis and management, patients with advanced pheochromocytomas and paragangliomas (PPGL) face limited treatment options. This study aims to evaluate the safety and efficacy of peptide receptor radionuclide therapy (PRRT) in patients with advanced PPGL, based on a single-institution experience and provide a comprehensive review of the literature. METHODS: A retrospective analysis was conducted on patients with advanced pheochromocytoma and paraganglioma who received PRRT at a single institution from April 2012 to March 2022. Clinical characteristics, treatment response, adverse events, and survival outcomes were assessed. A systematic literature review was also performed. RESULTS: A total of 15 patients with advanced PPGL were included, the majority of whom had both metastatic and functional disease. Most patients received four infusions of 177Lu-DOTATATE (73%). The median therapeutic 177Lu-DOTATATE radioactivity for each infusion was 7.4 GBq. Only one patient was treated with one infusion of 90Y-DOTATATE (4.2 GBq) in addition to three infusions of Lu-177 DOTATATE. Overall, PRRT suggests a promising efficacy with disease control rate of 63.6% by RECIST v1.1. The median overall survival (OS) was not reached and the median progression free survival (PFS) was 25.9 months. In terms of safety, PRRT was well tolerated. Review of the literature revealed consistent findings, supporting the efficacy and safety of PRRT in PPGL. CONCLUSION: This study suggests that PRRT is a safe and effective therapeutic option for patients with PPGL. Our findings align with the existing literature, providing additional evidence to support the use of PRRT in this challenging patient population.

Optimization of Bayesian penalized likelihood reconstruction for 68 Ga-prostate-specific membrane antigen-11 PET/computed tomography.

OBJECTIVE: The objective of this study is to determine the optimal ß value for clinical use in digital 68 Ga-prostate-specific membrane antigen (PSMA-11) PET/computed tomography (CT) imaging. METHODS: 68 Ga PSMA PET/CT of 21 patients with prostate cancer were reconstructed using block-sequential regularized expectation maximization ( ß value of 400-1600) and ordered subsets expectation maximization. Nine independent blinded readers evaluated each reconstruction for overall image quality, noise level and lesion detectability. Maximum standardized uptake value (SUVmax) of the most intense lesion, liver SUVmean and liver SUV SD were recorded. Lesions were then subdivided according to uptake and size; the SUVmax of these lesions were analyzed. RESULTS: There is a statistically significant correlation between improvement in image quality and ß value, with the best being ß 1400. This trend was also seen in image noise ( P  < 0.001), with the least image noise reported with ß 1400. Lesion detectability was not significantly different between the different ß values ( P  =  0.6452). There was no statistically significant difference in SUVmax of the most intense lesion ( P  = 0.9966) and SUVmean of liver background between the different ß values ( P  = 0.9999); however, the SUV SD of the liver background showed a clear trend, with the lowest with ß 1400 ( P  = 0.0008). There was a decreasing trend observed in SUVmax when ß values increased from 800 to 1400 for all four subgroups, and this decrease was greatest in small and low uptake lesions. CONCLUSION: Bayesian penalized likelihood reconstruction algorithms improve image quality without affecting lesion detectability. A ß value of 1400 is optimal.

Expect the Unexpected: Artifacts From Lodged 124I Capsule in Esophagus on PET/CT.

ABSTRACT: A 61-year-old woman with well-differentiated thyroid cancer underwent 124I-PET/CT imaging. A 124I capsule was administered orally, and the patient was imaged 90 minutes after from the skull vertex to feet. The 124I capsule was unexpectedly lodged in the esophagus. We illustrate attenuation and scatter correction artifacts from 124I capsule unexpectedly lodged in the esophagus and the usefulness of nonattenuation correction images in such circumstances. This also highlights the importance of drinking adequate amounts of water following the ingestion of iodine capsules (123I, 124I, or 131I) to reduce the resulting radiation dose to the esophagus.

18F-FDG PET/CT Manifestations of IgG4-related Disease.

Immunoglobulin G4-related disease (IgG4-RD) was not recognised as a systemic condition until 2003, when extra pancreatic manifestations were identified in patients with autoimmune pancreatitis. Since then, IgG4-RD has been described to involve virtually every organ system. It is highly responsive to immunosuppressants but can have detrimental effects if left untreated. Early recognition of the disease is, therefore, critical. The diagnosis of IgG4-RD is frequently challenging owing to its non-specific clinical manifestations, indolent nature and broad differential diagnoses. Although histopathological examination remains the cornerstone of diagnosis, imaging plays an important role in establishing extent of disease and identifying areas suitable for biopsy. 18F-Fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) has been demonstrated to be useful in assessing organ involvement, guiding biopsy and monitoring disease response. The 18F-FDG PET/CT scan is highly sensitive and able to evaluate multiorgan involvement in a single examination, a key advantage over conventional imaging modalities. A potential pitfall is its low specificity. As such, detailed knowledge of the imaging findings in IgG4-related disease is required to avoid misdiagnosis. This pictorial review aims to depict the diverse spectrum of imaging findings of IgG4-RD and the key imaging features to distinguish it from other important differential diagnoses.

Recombinant human thyrotropin versus thyroid hormone withdrawal in an Asian population.

CONTEXT: To prepare for radioactive iodine therapy in post total thyroidectomy patients with well-differentiated thyroid cancer (WDTC), either thyroid hormone withdrawal (THW) or administration of recombinant human thyrotropin (rhTSH) can be performed. OBJECTIVE: Our objective is to compare quality of life (QoL) parameters using the SF-36v2 questionnaire (Short Form health survey) and a self-evaluated item, and the hypothyroid status using modified Billewicz scores in an Asian population undergoing either THW or rhTSH for remnant ablation or adjuvant treatment following total thyroidectomy for WDTC. We will also assess the proportion of patients achieving TSH level of >30 mU/L after 4 weeks of thyroid hormone withdrawal. RESULTS: Patients in the rhTSH group were better in the QoL domains of physical functioning, role functioning/physical and bodily pain, while patients in THW group were better in mental health. This was however, not statistically significant. Modified Billewicz scores were higher in patients in THW group as compared with rhTSH group and statistically significant. A total of 96.3% of patients achieved TSH level >30 mU/L after 4 weeks of THW. CONCLUSION: Clinical symptoms and signs of hypothyroidism as assessed with modified Billewicz scores were statistically significantly higher in the THW group. However, there was no statistically significant difference in QoL in the rhTSH group.

Current Status and Growth of Nuclear Theranostics in Singapore.

The concept of theranostics, where individual patient-level biological information is used to choose the optimal therapy for that individual, has become more popular in the modern era of 'personalised' medicine. With the growth of theranostics, nuclear medicine as a specialty is uniquely poised to grow along with the ever-increasing number of concepts combining imaging and therapy. This special report summarises the status and growth of Theranostic Nuclear Medicine in Singapore. We will cover our experience with the use of radioiodine, radioiodinated metaiodobenzylguanidine, peptide receptor radionuclide therapy, prostate specific membrane antigen radioligand therapy, radium-223 and yttrium-90 selective internal radiation therapy. We also include a section on our radiopharmacy laboratory, crucial to our implementation of theranostic principles. Radionuclide theranostics has seen tremendous growth and we hope to be able to grow alongside to continue to serve the patients in Singapore and in the region.