Concurrent Benign Iodine-Avid Thymic and Liver Cysts Mimicking Metastatic Disease on 131I Whole-Body Scintigraphy.

ABSTRACT: A 57-year-old woman received radioiodine therapy post total thyroidectomy for pT3aNxMx follicular thyroid carcinoma. Posttherapy 131I whole-body scan showed 131I concentration in the chest, mediastinum, and left upper thigh with stimulated thyroglobulin (Tg) of 89 µg/L. Subsequent radioiodine therapies showed persistent 131I accumulation in the anterior mediastinal soft tissue lesions and a hypodense segment VII liver lesion visualized on SPECT/CT, suggestive of iodine-avid metastatic disease despite the undetectable serum Tg (<1.0 µg/L) with no Tg antibody interference. Biopsy of the liver lesion revealed liver cyst, and consequent removal of the mediastinal lesions showed benign thymic cysts.

Metabolic Superscan on 18 F-FDG PET/CT in a Patient With Secondary Hyperparathyroidism.

ABSTRACT: Superscan on PET/CT has been reported in the literature and mainly involved metastatic diseases. We report an uncommon case of a metabolic superscan on 18 F-FDG PET/CT in a 56-year-old man with end-stage renal disease on hemodialysis who presented with secondary hyperparathyroidism. Parathyroid scintigraphy showed 2 lesions posteroinferior to both thyroid lobes, suggestive of parathyroid adenoma/hyperplasia. FDG PET/CT performed to assess for pulmonary nodules revealed diffuse FDG hypermetabolism involving the visualized skull, mandible, spine, sternum, ribs, and appendicular skeleton without corresponding CT lesion with no urinary radiotracer excretion, consistent with metabolic superscan secondary to renal osteodystrophy.

Myocardial Perfusion Scintigraphy in a Patient With Transposition of Great Arteries Post-Atrial Switch Surgery.

ABSTRACT: We report a case of a 33-year-old woman who underwent stress and rest myocardial perfusion scintigraphy (MPS) to exclude coronary artery disease. MPS images showed an apparent dextrocardia with a right-sided septal wall uptake. The electrocardiograph showed a right axis deviation with dominant R waves at leads aVR and V1. Upon retrieval of the patient's medical records, she had an underlying transposition of great arteries and underwent a Senning atrial switch surgery. Hence, the MPS images demonstrated a prominent right ventricular wall due to its function as the "systemic" ventricle with minimal uptake in the "pulmonary" left ventricle.

Value of Baseline Post-Transplant MAG3 Renal Scintigraphy in the Evaluation of Graft Function.

INTRODUCTION: Accurate assessment of renal graft function in the early post-transplant period is crucial, as it influences clinical management and graft prognostication. However, there are limitations in current available modalities. MAG3 scintigraphy could contribute vital information on graft function. OBJECTIVES: This study aimed to determine the predictive value of parameters derived from MAG3 performed within 72 hours post transplant in detecting graft function. Delayed graft function (DGF), which is defined as dialysis requirement within the first week post transplant, is chosen as a surrogate measure of graft function. METHODOLOGY: All renal transplant recipients who underwent MAG3 within 72 hours post transplant from 2017 to 2019 were enrolled. Three MAG3 parameters, renogram grade, tubular injury severity score, and R20:3, were evaluated. RESULTS: A total of 117 patients were enrolled. The overall incidence of DGF was 16.2% with a significantly higher incidence amongst cadaveric graft recipients (53.6%) compared with living graft recipients (4.5%). Renogram grade ≥2, tubular injury severity score ≥4, and R20:3 > 1.31 significantly predicted DGF, P < .05 with high area under the curve for R20:3 of 0.97. Grafts with parameters above the cutoffs also showed significantly worse GFR at 1- and 3-months post-transplant. On multivariate analysis, prolonged cold ischemia time was associated with a higher risk of DGF, odds ratio 1.005 (95% confidence interval 1.003-1.007), P < .05. CONCLUSION: Baseline MAG3 accurately depicts early graft function and was also predictive of GFR at 1- and 3- months post-transplant. These baseline MAG3 scans could be particularly useful amongst deceased donor graft recipients owing to the higher risk of poor graft function.

Incidental Finding of Endometrioid Adenocarcinoma of the Ovary on 131I Whole-Body Scan.

ABSTRACT: A 57-year-old woman was referred for radioactive iodine therapy 12 weeks after completion thyroidectomy and left modified radical neck dissection for pT2N1Mx follicular variant papillary thyroid carcinoma. After 4 weeks of l-thyroxine withdrawal, stimulated serum thyroglobulin level was less than 0.1 ng/mL with positive thyroglobulin antibody. Posttherapy 131I scintigraphy with SPECT/CT of the head and abdominopelvic region showed thyroid residual in the neck, occipital bone metastasis, and heterogenous tracer uptake in a large peritoneal mass, likely arising from the left ovary. Left salpingo-oophorectomy was performed, and histopathologic examination revealed endometrioid carcinoma of left ovary.

Bone single-photon emission computed tomography/computed tomography in cancer care in the past decade: a systematic review and meta-analysis as well as recommendations for further work.

Skeletal whole-body scintigraphy (WBS), although widely used as a sensitive tool for detecting metastatic bone disease in oncology cases, has relatively low specificity. Indeterminate bone lesions (IBLs) detected by WBS cause a diagnostic dilemma, which hampers further management plans. In the advent of hybrid imaging, single-photon emission computed tomography/computed tomography (SPECT/CT) has been gaining popularity as a tool to improve the characterisation of IBLs detected by WBS. As yet, there has not been a systematic review to objectively evaluate the diagnostic capabilities of SPECT/CT in this area. We conducted a systematic review of relevant electronic databases up to 30 August 2020. The outcomes of interest were the reporting of SPECT/CT to identify benign and malignant IBLs and the calculation of the sensitivity and specificity of the index test, based on histopathological examination or clinical and imaging follow-up as the reference standard. After the risk of bias and eligibility assessment, 12 articles were identified and synthesised in the meta-analysis. The pooled sensitivity and specificity of SPECT/CT for diagnosing IBLs are 93.0% [95% confidence interval (CI) 0.91-0.95] and 96.0% (95% CI 0.94-0.97), respectively. There was heterogeneity of the articles due to variable imaging protocols, duration of follow-up and scoring methods for interpreting the SPECT/CT results. The heterogeneity poses a challenge for accurate interpretation of the true diagnostic capability of SPECT/CT. In conclusion, targeted SPECT/CT improves the specificity of diagnosing bone metastases, but efforts need to be made to standardise the thresholds for SPECT/CT, methodology, as well as harmonising the reporting and interpretation criteria. We also make some recommendations for future works.

Giant Liver Hemangioma Mimicking a Hydronephrotic Kidney on 99mTc-DTPA Scintigraphy.

We report a case of a 56-year-old woman who underwent Tc-DTPA renal scintigraphy for the evaluation of a right pelviureteric junction calculi, which incidentally showed radiotracer uptake in a giant liver hemangioma. The initial scintigraphic images showed a large lobulated lesion with peripheral uptake of radiotracer at the right abdominal region, resembling a large hydronephrotic kidney. However, the pattern of progression of the radiotracer, coupled with the clinical history and available corresponding radiologic images, confirmed the uptake to be that of a giant liver hemangioma.