Context: Multiple myeloma and extensive lytic skeletal metastases may appear similar on positron-emission tomography and computed tomography (PET-CT) in the absence of an obvious primary site or occult malignancy. Radiomic analysis extracts a large number of quantitative features from medical images with the potential to uncover disease characteristics below the human visual threshold. Aim: This study aimed to evaluate the diagnostic capability of PET and CT radiomic features to differentiate skeletal metastases from multiple myeloma. Settings and Design: Forty patients (20 histopathologically proven cases of multiple myeloma and 20 cases of a variety of bone metastases) underwent staging 18F-fluorodeoxyglucose PET-CT at our institute. Methodology: A total of 138 PET and 138 CT radiomic features were extracted by manual semi-automatic segmentation and standardized. The original dataset was subject separately to receiver operating curve analysis and correlation matrix filtering. The former showed 16 CT and 19 PET parameters to be significantly related to the outcome at 5%, whereas the latter resulted in 16 CT and 14 PET features. Feature selection was done with 7 evaluators with stratified 10-fold cross-validation. The selected features of each evaluator were subject to 14 machine-learning algorithms. In view of small sample size, two approaches for model performance were adopted: The first using 10-fold stratified cross-validation and the second using independent random training and test samples (26:14). In both approaches, the highest area under the curve (AUC) values were selected for 5 CT and 5 PET features. These 10 features were combined and the same process was repeated. Statistical Analysis Used: The quality of the performance of the models was assessed by MSE, RMSE, kappa statistic, AUC, area under the precision-recall curve, F-measure, and Matthews correlation coefficient. Results: In the first approach, the highest AUC = 0.945 was seen with 5 CT parameters. In the second approach, the highest AUC = 0.9538 was seen with 4 CT and one PET parameter. CT neighborhood gray-level different matrix coarseness and CT gray-level run-length matrix LGRE were common parameters in both approaches. Comparison of AUC of the above models showed no significant difference (P = 0.9845). Feature selection by principal components analysis and feature classification by the multilayer perceptron machine-learning model using independent training and test samples yielded the overall highest AUC. Conclusions: Machine-learning models using CT parameters were found to differentiate bone metastases from multiple myeloma better than models using PET parameters. Combined models using PET and CECT data showed better overall performance than models using only either PET or CECT data. Machine-learning models using independent training and test sets were performed on par with those using 10-fold stratified cross-validation with the former incorporating slightly more PET features. Certain first- and second-order CT and PET texture features contributed in differentiating these two conditions. Our findings suggested that, in general, metastases were finer in CT and PET texture and myelomas were more compact.

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Purpose: Evaluation of fluorescein along with blue dye as an affordable tracer for sentinel node biopsy in comparison with technetium + methylene blue. A randomized trial was conducted with the following objectives: (1) to demonstrate that the identification of sentinel lymph node by fluorescein + methylene blue is not inferior to the identification by Tc-99 m sulfur colloid + methylene blue and (2) to evaluate the cost-effectiveness of sentinel node biopsy by above two tracers. Subjects and Methods: One-thirty patients above age 18 years presenting with early breast cancer T1, T2, N0 breast carcinoma were randomized to undergo sentinel node biopsy by either fluorescein + methylene blue or Tc-99 m sulfur colloid + methylene blue. Results: The sentinel lymph nodes were identified in 89% in Fluorescein + methylene blue group and 90.9% with Tc-99 m sulfur colloid + methylene blue group. The trial demonstrated noninferiority of fluorescein + methylene blue as compared to isotope + methylene blue with effect size = 1; 95% confidence interval- 9.54 to + 11.54. The fluorescein + methylene blue was more cost-effective than isotope guided sentinel node biopsy. Conclusion: Fluorescein-guided sentinel node biopsy is noninferior and more cost-effective than isotope-guided sentinel node biopsy.

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Purpose: Adrenocortical carcinoma (ACC) is a rare primary malignancy of the adrenal gland. The present study was aimed to compare the performance of fluoro-2-deoxyglucose-positron emission tomography–computed tomography (FDG-PET-CT) compared to contrast-enhanced computed tomography (CECT) in diagnosis and management of ACC. Materials and Methods: A retrospective analysis of the PET-CT studies from January 2010 to October 2020 was performed. Patients with adrenal lesions suspicious of ACC and diagnosed cases of ACC who underwent PET-CT for staging, restaging, and surveillance were reanalyzed. The PET-CT parameters were compared with the clinical, biochemical, histopathological, and CECT parameters. Results: The study included 96 scans performed in 77 patients (36 males, aged 40.4 ± 17.9 years). Of these, 55 scans were performed to diagnose and stage suspected ACC (30 of them diagnosed as ACC), 31 for restaging, and 10 scans for surveillance of ACC. PET/CT revealed metastases from an extra-adrenal primary in 5/55 patients. FDG-PET-CT had a sensitivity and specificity of 100% and 70% to diagnose ACC. Standardized uptake value-peak more than 5.4 had a sensitivity of 90.9% and specificity of 91.7% for differentiating ACC from non-ACC lesions, while tumor-to-liver ratio peak (TLRpeak) of 3.3 was most specific. PET-CT changed the staging in 23.3% of the patients with an accuracy of 100%. PET-CT changed the management plan in 25.8% of the patients during restaging with a sensitivity and specificity of 95.6% and 100%, respectively. For surveillance, CECT was as sensitive as PET-CT; however, PET-CT was more specific (100% vs. 97.9%). Conclusion: FDG-PET-CT performs better than CECT in the diagnosis, staging, restaging, and surveillance of ACC.

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Introduction: The objective of this study was to see the effect of fuzzy intensification (INT) operator on enhancement of scintigraphic image. Materials and Methods: Nuclear medicine physician (NMP) provided 25 scintigraphic images that required enhancement. The image pixels value was converted into fuzzy plane and was subjected to contrast INT operator with parameters of INT operator i.e., cross-over = 0.5 and number of iterations = 1 and 2. The enhanced image was again brought back into spatial domain (de-fuzzification) whose intensity value was in the range 0–255. NMP compared the enhanced image with its input image and labeled it as acceptable or unacceptable. The quality of enhanced image was also accessed objectively using four different image metrics namely: Entropy, edge content, absolute mean brightness error and saturation metrics. Results: Most of the enhanced images (18 out of 25 images) obtained at cross-over = 0.5 and number of iterations = 1 are acceptable and found to have overall better contrast compared to the corresponding input image. Four images (two brain positron emission tomography scan and two I-131 scan) obtained at cross-over = 0.5 and with iteration = 2 are acceptable. Three input images (one dimercaptosuccinic acid (DMSA), one I-131 and one I-131- metaiodo-benzyl-guanidine (MIBG) scan) were better than their enhanced images. Conclusions: The enhancement produced by fuzzy INT operator was encouraging. Majority of enhanced images were acceptable at cross-over = 0.5 and number iterations = 1.

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Extracranial metastases of glioblastoma multiforme (GBM) are very rare. The estimated incidence is <2%. We report a case of a 49-year-old woman, who was a known case of GBM in the left temporo-occipital lobe. She was operated and had received radiotherapy and adjuvant chemotherapy for the same. Subsequently, the patient underwent bone scan. On 99 m-Tc methylene diphosphonate (MDP) bone scan, homogenously increased tracer uptake was noted in the axial and appendicular skeletal system, suggesting metastatic skeletal superscan.

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Background: Imaging of gliomas/glioblastomas has always been challenging. Many magnetic resonance imaging (MRI) techniques are available for imaging glioblastomas. MRI cannot always differentiate tumor from nonspecific changes and postoperative changes in brain tissue. Among the new positron emission tomography–computed tomography (PET-CT) tracers, gallium-68 prostate-specific membrane antigen (Ga-68 PSMA-11 PET-CT) appears to be the most promising one. The absence of uptake by normal brain parenchyma leads to high tumor-to-background ratio leading to better visualization of the tumor. Objective: The aim of this study was to assess the correlation of target volumes on MRI and PSMA brain scans in the treatment planning of glioblastomas. Materials and Methods: Twenty-four patients in the age group of 5–75 years with histologically proven glioblastoma were included in the study following maximum safe resection. Simulation for treatment planning was done with Ga-68 PSMA PET-CT brain with IV iodine-based contrast. The pre- and postoperative MRI images were fused with PSMA simulation images. Gross tumor volumes (GTVs) contoured on T1-contrast MRI and on PSMA scans were compared. Results: GTV contoured on MRI and PSMA brain scans showed complete overlap in 17 patients. In seven patients, the target volumes drawn on Ga-68 PSMA brain scans were slightly smaller than the target volumes drawn on MRI brain scans. This difference in volumes could be due to postoperative changes which showed enhancement on the MRI scan. Conclusion: Ga-68 PSMA PET-CT shows good correlation with MRI brain in the evaluation and RT planning in glioblastomas. Tumor necrosis and postoperative changes did not show PSMA uptake. Precise target delineation on PSMA PET-CT can potentially result in smaller and more accurate GTVs, which in turn would result in less RT-induced side effects.

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We report a patient with multiple myeloma (MM) and polyarthritis of large joints. During the staging of the disease, bone marrow diffusely involved by MM was clearly demonstrated by 99mTc-2-methoxy-isobutyl-isonitrile (MIBI) single-photon emission computed tomography/computed tomography (SPECT/CT) but not by 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/CT images. On the other hand, a very intense uptake of 18F-FDG was detected in periarticular tissues of multiple joints, with nonabnormal 99mTc-MIBI accumulation. Rheumatology tests were negative. A subsequent bone scintigraphy demonstrated radiolabeled bisphosphonate accumulation in periarticular tissues, suggesting amyloid arthropathy.

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Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is an unusual subtype of cutaneous lymphoma and clinically appears as erythematous, subcutaneous infiltrates, and recurrent papulonodules. It is defined as a rare cytotoxic a/b T-cell lymphoma characterized by primary involvement of subcutaneous tissue-mimicking panniculitis and a predominant CD3+/CD4/CD8+ phenotype in (2005) the World Health Organization-European Organization for Research and Treatment of Cancer classification for cutaneous lymphomas. On metabolic imaging, these lesions are invariably fluorodeoxyglucose (FDG) avid. SPTCL which presents as a breast mass is a rare entity. Here, we present a case of SPTCL presents as FDG avid breast mass and subcutaneous nodules.

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Positron emission tomography/computed tomography (PET/CT) is increasingly becoming a mainstay in diagnosis and management of many malignant disorders. However, its role in the assessment of gastro-intestinal lesions is still evolving. The aim of this review was to demonstrate the areas, where PET/CT is impactful and where it has limitations. This will allow for us to reduce unnecessary investigations and develop methods to overcome the limitations.

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A 46-year-old female with Sjögren's syndrome previously treated with corticosteroids was referred to our department for suspicious humeral head osteonecrosis. Dual-phase bone scan showed an increased radiotracer distribution in the head of the left humerus. Nevertheless, whole-body scan revealed multiple sites of heterogeneous skeletal uptake. As lymphoproliferative disorder was hypothesized, also based on laboratory examination, F-18 fluorodeoxyglucose positron-emission tomography/computed tomography was performed and showed increased uptake in several osseous structures and in the subcutaneous nodules. Finally, bone marrow biopsy confirmed the diagnosis of acute myeloid leukemia as well as skin nodule biopsy revealed infiltration by malignant cells.

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Hepatobiliary involvement is a less common manifestation of abdominal tuberculosis. We present the case of a 42-year-old female who presented with fever, abdominal pain, and jaundice of 2 months duration. ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography done for disease evaluation suggested the likely possibility of cholangiocarcinoma but excision biopsy from periportal lymph node later confirmed a granulomatous etiology and she was successfully treated with antitubercular therapy.

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Nasopharyngeal carcinoma is a rare malignancy of the head-and-neck region. It is associated with Epstein–Barr virus infection and smoking. Its association with breast cancer is also infrequent. Chemokine receptor (CXCR)-4 imaging is a newer agent for imaging many malignancies with a good diagnostic value. We present a case of a young female diagnosed with left breast carcinoma in whom Ga-68 CXCR-4 PET/CT demonstrated tracer avid lesion in the nasopharynx. Biopsy of the nasopharyngeal lesion revealed Schminke type of lymphoepithelial cancer, indicating CXCR-4 PET/CT as a potential imaging modality for lymphoepithelial malignancy.

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Modalities for in vivo imaging of Mycobacterium tuberculosis are limited and inadequately studied. One such modality is ^99mTc-ethambutol scintigraphy which has shown promising results for diagnosis of tuberculosis (TB). Ethambutol, one of the primary antitubercular drugs, is bacteriostatic which acts on the mycolic acid cell wall synthesis of the M. tuberculosis. However, literature on its utility is scarce. The few studies that exist have reported its sensitivity and specificity between 90%– 95% and 71%–85%. We present here a case demonstrating the role of ^99mTc-ethambutol scan in knee joint TB.

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We present a case of a 23-year-old male patient with complaints of fever, cough, and persistent anemia for the past 6 months and with a known history of hereditary spherocytosis. Computed tomography (CT) thorax demonstrated multiple paravertebral lesions in the bilateral thoracic cavities, suggestive of lymphadenopathy; subsequently, ¹⁸Flurodeoxyglucose PET/CT was done with suspicion of lymphoma, which showed no significant metabolic activity in those lesions. Thus, in view of clinical and metabolic status, lesions were considered extramedullary hematopoiesis (EMH). This case highlights the importance of considering EMH, while interpreting suspicious lymphadenopathy in cases of chronic anemia and also possible scan findings in the same.

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Bone infections are a common problem, and early diagnosis and intervention can lead to better clinical outcomes and prognoses. Here, we compare the well-known tracers Gallium-67 (Ga-67) citrate versus Ga-68 citrate in the diagnosis of infections.

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Hemangioblastomas are rare vascular tumors of the central nervous system usually related to other pathological conditions, such as Von Hippel Lindau Syndrome (VHLS) and polycythemia. We describe a case of a 65-year-old man with a neuroendocrine tumor of the ileum presenting with cervical pain who underwent a ⁶⁸Ga-DOTATOC positron emission tomography/computed tomography (PET/CT) scan that incidentally underlines the presence of hemangioblastoma of the cervical spinal cord. The patient does not have a family history of VHLS nor does he suffer from polycythemia and he is currently waiting for genetic testing. Despite being rare, hemangioblastomas could be possible findings of central nervous system incidentaloma at ⁶⁸Ga-DOTATOC PET/CT scan, especially in patients with anamnesis with possible related condition.

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A 53-year-old man was investigated for ongoing right ankle pain and lateral malleolus swelling following a traumatic inversion injury 12 weeks prior. The initial ankle radiograph was normal with no evidence of fracturing. The follow-up radiograph showed bridging ossification in the distal tibiofibular syndesmosis. As the pain did not subside, posttraumatic heterotopic ossification (HO) was suspected, and triple-phase dynamic bone imaging with technetium 99m-methylene diphosphonate was performed to guide further management. The bone scan revealed intense focal tracer activity centered on the HO of the tibiofibular syndesmosis, with no evidence of occult fracturing confirming HO as a pain generator.

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Fluorine-18 prostate-specific membrane antigen (PSMA) positron emission tomography-computed tomography scan is widely used for restaging of prostate cancer. We present a case where false-positive PSMA uptake was seen in metachronous carcinoma breast during restaging workup of carcinoma prostate.

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Corticomedullary mixed tumor (CMT) is a single adrenal tumor mass composed histologically by an admixture of adrenal cortical and medullary cells. It is a rare condition, with approximately 20 cases reported to date. To our knowledge, the positron emission tomography (PET) imaging findings of this mostly benign tumor have not been reported in the literature. We present a case of CMT who was evaluated with both ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) and ⁶⁸Ga-DOTATATE. The hypermetabolic tumor seen on ¹⁸F-FDG PET/computed tomography scan showed no abnormal uptake by ⁶⁸Ga-DOTATATE.

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Erdheim‒Chester disease (ECD) is a rare non-Langerhans' cell histiocytic proliferative disorder of unknown origin with multisystemic predilection. It commonly affects adults in the fifth–seventh decades of life, with male preponderance, and has nonspecific clinical manifestations. Presence of characteristic radiological findings and demonstration of CD68 positive xanthogranulomatous infiltrates in histology clinches the diagnosis. Nevertheless, being a nonmalignant condition, it might be fatal due to multiorgan dysfunction. Hence, timely diagnosis and initiation of treatment with corticosteroids, immunosuppressants, or tyrosine kinase inhibitors are of paramount importance. We present a case of ECD with multisystemic involvement, who was initially evaluated for the left lung mass and treated as tuberculosis, where fluorine-18-labeled fluorodeoxyglucose positron emission tomography/computed tomography aided in targeting the metabolically active site for biopsy as well as assessing the multisystemic involvement.

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Mantle cell lymphoma (MCL) is a rare subtype of B-cell non-Hodgkin's lymphoma with an annual incidence of 5%, common in men with a median age of 60–70 years. Renal involvement is seen in about 0.7% of the extranodal lymphomas. The bilateral presentation is seen in 10%–20% of cases. There have been many case reports of MCL with renal involvement; however, primary renal involvement by MCL is extremely rare. We hereby describe the ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomographic findings in primary MCL involving the bilateral kidneys.

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The limbic encephalitis is an autoimmune disorder which characterized by inflammation of the brain with rapidly progressing dementia either due to paraneoplastic or nonparaneoplastic etiology which requires definitive neurological and whole-body evaluation. We describe both clinical and nuclear medicine imaging and radiological findings in a case of limbic encephalitis using positron emission tomography and magnetic resonance imaging.

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Tertiary hyperparathyroidism (TH) is a rare condition that develops from secondary hyperparathyroidism in cases when the secretion becomes autonomous. Brown tumors (BTs) are rare skeletal lesions of hyperparathyroidism that may mimic cancer metastasis. We report a case of a patient who was diagnosed with TH with multiple BTs which mimics osteolytic/osteoblastic metastases that were evaluated with two fluorodeoxyglucose positron emission tomography scans with an interval of 23 months in the preoperative and postoperative period.

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