Coronary artery disease (CAD) is the leading cause of morbidity and mortality worldwide. Invasive coronary angiography (ICA) is the gold standard for the evaluation of epicardial CAD. In the pathogenesis of the CAD, myocardial perfusion abnormalities are the first changes that appear followed by wall motion abnormalities, electrocardiogram changes, and angina. Myocardial perfusion imaging (MPI) demonstrates the cumulative effect of pathology at epicardial coronary arteries, small vessels, and endothelium. Thus, it evaluates the overall burden of ischemic heart disease (IHD). MPI is used noninvasively to diagnose early asymptomatic CAD or to know the functional significance of known CAD. There are evidence that early detection of myocardial perfusion abnormalities followed by aggressive intervention against cardiovascular risk factors may restore myocardial perfusion. This may lead to reduce morbidity and mortality. Various MPI modalities have been used to diagnose and define the severity of CAD. Cardiac myocardial perfusion single-photon emission computed tomography (myocardial perfusion scintigraphy [MPS]) has been in use since decades. Several newer modalities such as positron emission tomography, cardiac magnetic resonance imaging, computed tomography perfusion, and myocardial contrast echocardiography are developing utilizing the similar principle of MPS. We shall be reviewing briefly these modalities, their performance, comparison to each other, and with ICA.

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Early diagnosis is imperative for adequate management of patients with osmotic demyelination syndrome (ODS), which is usually a result of rapid shifts of osmolality secondary to rapid correction of hyponatremia. Magnetic resonance imaging (MRI) with its special sequences is the investigation of choice for early detection of the osmotic changes in the brain. We report a case of clinically suspected ODS with noncontributory MRI and positive fluoro-2-deoxy-d-glucose positron emission tomography (FDG PET) scan with statistical parametric mapping (SPM) analysis, which localized the focal hypermetabolism in the basal ganglia, thalamus, pons, and cerebellum.

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Graves' ophthalmopathy (GO) involves autoimmune activation of fibroblasts, resulting in chronic inflammatory reaction. Somatostatin receptors are expressed in the cells associated with chronic inflammation. We hereby present patients with active GO, with delayed response to the standard treatment regimen, in whom⁶⁸Ga-DOTANOC positron emission tomography/computed tomography (PET/CT) was planned to evaluate the orbital inflammation.⁶⁸Ga-DOTANOC PET/CT shows no physiological orbital muscle uptake. It can provide information which may possibly of utility in response assessment and also screening patients who fail to respond to conventional treatment, for newer therapies such as long-acting somatostatin analogs.

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Purpose: The aim of this study was to evaluate the accuracy of dual-time point in differentiating benign from malignant local recurrent lesions in pancreatic cancer. Patients and Methods: Thirty-four patients with pancreatic cancer (22 males and 12 females, mean age: 58.3 ± 10.3) who presented with soft-tissue lesions at the operative bed. Early whole-body positron emission tomography/computed tomography (PET/CT) and delayed imaging on the abdomen were performed. The maximum standardized uptake value (SUVmax) of the initial image (SUVmax E) and the delayed image (SUVmax D) were determined. A Retention Index (RI) was also calculated. These indices were correlated with histopathology and follow-up as reference criteria. Results: No significant statistical difference in SUVmaxE was found between benign and malignant lesions, while SUVmaxD and RI of the malignant lesions (mean 8.6 ± 2.7 and 35.8 ± 18.3, respectively) were significantly higher than those of benign ones (mean 3.3 ± 1.4 and-6.2 ± 15.2, respectively) (P < 0.005). With SUVmaxD 4.9, malignancy could be predicted with the highest sensitivity (95.8%) and accuracy (94.1%) between the whole parameters. The estimated negative and positive predictive values (PPVs) were 90.0% and 95.8%, respectively. A cutoff point 16 for RI showed higher specificity and PPV (100% and 100%, respectively). Forty-seven total (11 benign and 36 malignant) lesions were identified. Increased SUVmax is noted on delayed images in most of malignant lesions, except for two that maintained stationary. Conclusion: Dual-time-point 18F fluorodeoxyglucose-PET/CT seems to be a reliable additional method to differentiate between malignant and benign postoperative local soft-tissue lesions in patients with pancreatic cancer.

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Introduction: Breast cancer is the most common malignancy among women all over the world, which accounts to 25% of all cancers. In known cases of breast cancer, the risk of developing another denovo malignancy is more when compared to low risk groups, which might be due to common environmental risk factors, treatment induced risk factors, Genetic susceptibility for mutations, presence of cancer syndromes or better detection due to close surveillance. Objective: To study the profile of Metachronous 2^nd primary malignancies suspected on 18F-FDG PET CT in known Breast cancer patients. In this Retrospective study from January 2014 to April 2018, all the consecutive patients with known Breast cancer, who were referred to Nuclear Medicine department for 18F- FDG PET CT for follow up evaluation were included. Suspected 2^nd primary malignancies were correlated with Histopathological examination (HPE). Results: During the study period, a total of 233 Breast cancer patients (all are females), with a mean age of 54.2+13.4 years were studied. On 18F-FDG PET CT scan, suspicion for 2^nd primary malignancy was observed in 37 patients. HPE was done in 28/37 patients at the site of suspected lesions. 15/28 were positive for second malignancy, and remaining 13/28 were either a benign pathology or a part of metastatic disease from the primary breast cancer. The sites of 2^nd primary malignancies included Contralateral breast in 8/15 (53.3%), Ovary in 2/15 (13.3%), Endometrium in 2/15 (13.3%), Lung in 1/15 (6.6%), Stomach in 1/15 (6.6%) and Urinary bladder in 1/15 (6.6%) patients respectively. The incidence of metachronous 2^nd primaries in breast cancer is 67.3 per 1000 breast cancer patients. Conclusion: Metachronous second primary cancers in breast cancer patients are not very rare. A high imaging suspicion on 18F-FDG PET CT helps in early detection of 2^nd primary cancer, thereby facilitating early and appropriate management.

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Immunoglobulin G4-related disease (IgG4) is an immune-mediated fibro-inflammatory entity which affects multiple organs, most frequently the pancreas. Although extrapancreatic inflammations are commonly seen in ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography of majority of these patients at follow-up, simultaneous involvement of the gastric/biliary tract at presentation is rare. Here, we present imaging findings of a patient who presented with obstructive jaundice and initially thought to be due to cholangiocarcinoma, but was subsequently diagnosed as an IgG4-related inflammation.

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Syringomyelia is a rare degenerative disease affecting the spinal cord and brain stem causing progressive neurological dysfunction. The presence of gastrointestinal symptoms in these patients is common, although references related to nuclear medicine imaging procedures in this pathology are limited, focusing on the study of gastric emptying. We present a 47-year-old male patient diagnosed with syringomyelia and persistent digestive symptoms who underwent gastrointestinal transit scintigraphy to assess the extent of dysmotility. Liquid gastric emptying and small-bowel transit were normal. Large bowel showed poor activity in descending and rectosigmoid colon, being compatible with generalized slow colon transit.

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Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome is a rare clinical entity involving musculoskeletal and dermatologic systems. Its main features are prominent inflammatory cutaneous and articular manifestations. Anterior chest wall pain, more commonly at sternoclavicular and sternocostal joints, along with palmoplantar pustulosis and acne can point to this uncommon syndrome. Here, we report a case of a 15-year-old female, who presented with swelling at the anterior chest wall, was referred for the bone scan. Bone scintigraphy and single-photon emission computed tomography (SPECT/CT) detected classical “bull-head” sign, and further physical examination, for skin lesions, confirmed the diagnosis.

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Purpose of the study: The purpose of this study was to evaluate the potential value of gallium-68 (Ga-68)-DOTATATE positron emission tomography/computed tomography (PET/CT) in predicting the risk of progression in nonbenign meningioma after definite irradiation. We retrospectively reviewed our patients with meningiomas who had the highest risk of progression: WHO histological Grade II and III tumors and with macroscopic disease as identified in Ga-68-DOTATATE PET/CT. Materials and Methods: Thirteen patients were included in this study. For each tumor, the following quantifiers were measured: maximum and mean standardized uptake volume (SUV), standard deviation, metabolic tumor volume (MTV), total lesion activity, and coefficient of variation. Each of the quantifiers except for maximum SUV was obtained with three different SUV thresholds: muscle based (_ms), liver based (_liv), and gradient based (_gb). The quantifiers were analyzed in univariate Cox model for their prognostic value for progression-free survival (PFS) and overall survival (OS). Results: Mean follow-up of the patients was 28.2 months. The 2-year PFS and OS was 28.1% and 76.9%, respectively. The MTV_gbwas a significant predictor for PFS (risk of progression of disease above vs. below the 34 cm³ threshold: 100% vs. 28.3%,P = 0.0003). Clinically, the male sex also influenced PFS (Hazard ratio =13.06; 95% confidence interval: 1.56–109.25;P = 0.018). The mean SUV_ms(P = 0.041) and SUV_gb(P = 0.048) had a prognostic value for predicting the risk of death. Conclusion: Ga-68-DOTATATE PET/CT has potential to predict disease progression in nonbenign meningioma patients. Further prospective studies for validating and standardizing these findings are indicated.

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Solid pseudopapillary neoplasm (SPN) is a rare histopathologic variant of pancreatic tumors. Franz first described this tumor as a “papillary tumor of the pancreas, benign or malignant.” In 1996, the World Health Organization named this tumor as SPN of the pancreas. It has a female preponderance with a male-to-female ratio of 1:9. A 30-year-old female who is a known case of lymphocyte-rich classic Hodgkin's lymphoma underwent ¹⁸F-fluoro-2-deoxy-D-glucose (FDG) positron-emission tomography/computed tomography (PET/CT) for initial staging which showed intense metabolic activity in bilateral enlarged cervical and splenic hilar lymph nodes. Furthermore, intense metabolic activity was noted in hypodense lesion in the tail of the pancreas, and she was reported to be having Stage IIIE disease. Post chemotherapy, ¹⁸F-FDG PET/CT showed disappearance of all previously metabolically active lymph nodes but persisting metabolically active lesion in tail of the pancreas. Hence, we reported as complete metabolic response of Hodgkin's lymphoma as per the Lugano criteria with suspected synchronous primary in the tail of the pancreas. Post distal pancreatectomy, histopathological examination and immunohistochemistry revealed the pancreatic lesion as SPN. SPN of the pancreas itself is a rare tumor and the presence of SPN in a patient with Hodgkin's lymphoma as synchronous primary is very rare. Due to the high density of mitochondria and the hypervascular nature of the tumor, there is an accumulation of ¹⁸F-FDG in SPN tumor cells. Patients with SPN usually have a very good prognosis after surgery. The five-year survival rate is as high as 95%–97%.

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Krukenberg tumors described by Friedrich Ernst Krukenberg are still fascinating for their mysterious origin. It is known to be a rare entity and commonly originates from adenocarcinoma of stomach. We present three interestingly rare cases of this entity, revealed by ¹⁸F-fluorodeoxyglucose-positron emission tomography/computed tomography (F-18 FDG-PET/CT) scan and discuss how F-18 FDG-PET/CT can prognosticate, alter the course of treatment in such patients. Ovarian metastatic deposits were detected in patients with renal cell, duodenal, and gall bladder carcinoma. Three visits were possible in patient with duodenal cancer (favorable response to therapy), two visits in renal cell cancer (progressive disease pattern) and only single visit for gall bladder cancer. Potentials of F-18 FDG-PET/CT scan for Krukenberg disease is still in exploratory phase, but it's applications in diagnosis, disease monitoring, therapeutic response monitoring, and prognosticating are unparalleled with other imaging modalities.

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Rosai–Dorfman disease (RDD) is an uncommon proliferative histiocytic disorder. Patients usually present with painless massive cervical lymphadenopathy with fever and leukocytosis. Isolated extranodal disease is rare and more severe fibrosis, fewer histiocytosis in lesions make diagnosis more difficult as compared to nodal disease. Here, we report a case of isolated extranodal RDD on fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) scan. FDG-avidity of RDD lesions is attributable to the intense glucose dependence of the proliferating histiocytes. PET-CT scan not only demonstrates the complete staging of the disease but also provide functional information about the disease activity to guide biopsy.

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Background: The present study aims to explore the role of sentinel lymph node biopsy (SLNB) with intraoperative frozen section in the management of early-staged oral tongue cancers. Materials and Methods: Fifty-two patients with clinical stages cT1/2N0 oral tongue cancers were included in the present study. The curative surgery was preceded by the performance of an SLNB using a dual technique. Results: The identification rate of sentinel lymph node (SLN) in this study was 98.07%. The sensitivity, specificity, positive predictive value (PPV), and the negative predictive value (NPV) of SLNB were 88.2%, 100%, 100%, and 94.5%, respectively. Further, the sensitivity, specificity, PPV, and the NPV of intraoperative frozen section of the SLN were 70.5%, 100%, 100%, and 87.5%, respectively. Conclusions: The addition of intraoperative frozen section could identify 70.5% of patients with occult metastasis. An intraoperative frozen section assessment of sentinel node has the potential to change the overall management of patients with early-oral tongue cancers.

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18F flurodeoxyglucose positron emission tomography-computed tomography (18F FDG PET-CT) is widely used in the evaluation of patients with lung mass suspicious for malignancy. In addition to malignancy, a variety of benign neoplasms and inflammatory lesions can arise in the lungs, many of which show increased FDG concentration, thereby mimicking malignancy. Awareness of the common mimics of lung cancer and a thorough understanding of their key imaging characteristics on CT as well as FDG PET is helpful in narrowing the differential diagnosis, eventually leading to appropriate therapy. In this article, we enlist these mimics and discuss their metabolic and morphologic characteristics and provide a pathophysiological basis for their FDG uptake.

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Thyroiditis is a very rare cause of fever of unknown origin (FUO). Thyroiditis presenting as only fever and weight loss is very rare. We present a case of FUO, which was later on confirmed as thyroiditis on thyroid scintigraphy.

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Bone scans are the most commonly used imaging technique to rule out local recurrence or metastasis during surveillance of malignant bone tumors after treatment. Although bone scans are very sensitive in detecting recurrence or metastasis, they are less specific. There are many nonmalignant conditions which can mimic either recurrence or metastasis on a Tc-99m bone scan. Therefore, physicians must be aware of such conditions to avoid unnecessary workup and invasive procedures. We present such an interesting case where chronic venous insufficiency mimicked either osteomyelitis or regional metastasis on a Tc-99m bone scan done for osteosarcoma surveillance.

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Pelvic insufficiency fractures (IFs) are frequently diagnosed on technetium-99m methylene diphosphonate bone scan (BS), where it remains an important diagnostic imaging modality. Involvement of iliac bone in pelvic IFs is very rare. Differentiation from metastases is crucial where BS shows characteristic appearance obviating the need for further investigations for confirmation. There are many diagnostic appearances reported on BS for the diagnosis of IFs at various sites. We present a patient with cervical carcinoma who was previously treated with external beam radiotherapy to pelvis and now presented with pelvic pain. BS was performed to rule out skeletal metastases, however, the findings were diagnostic for iliac IF.

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Extramedullary plasmacytoma is an unusual manifestation in multiple myeloma (MM). It can present as a solitary bone lesion and/or soft-tissue mass. Plasmacytoma can be presented at any location, but it is more common in the head and neck, usually without systemic involvement. The presence of plasmacytoma in MM is a predictor of rapidly progressive disease. The value of fluorine-18-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (PET-FDG) is increasing, in the diagnosis, detection of occult lesions, and therapeutic monitoring. We describe a patient with rapidly-progressive, refractory, left pectoral muscle plasmacytoma and MM. A PET-FDG guided the therapy and allowed to identify the presence of disease relapse.

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A 41-year-old lady presented with headache and ophthalmoplegia of the left eye for 1 week and underwent magnetic resonance imaging (MRI) of the brain, which showed homogeneously enhancing nodular thickening of meninges in the left anterior and middle cranial fossa with perilesional white matter edema of the left fronto-temporal lobes which appeared suspicious for neurosarcoidosis. She subsequently underwent 18F-fluorodeoxyglucose positron emission tomography–computed tomography (18F-FDG PET/CT) to determine the disease extent and to target the optimal biopsy site. Coregistration of 18F-FDG PET–CT brain to MRI was done for better characterization of the brain lesions.

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A 50-year-old man with beta-thalassemia major underwent Tc-99m sestamibi parathyroid scintigraphy due to elevated parathyroid hormone and calcium serum levels. Single-photon emission computed tomography imaging of neck and thorax revealed a parathyroid adenoma, as well as increased tracer uptake in a paraspinal region in the right hemithorax, where X-ray and computed tomography of the thorax had shown previously a mass compatible with extramedullary hematopoietic tissue.

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A 65-year-old patient with acute lymphoblastic leukemia presented for an ¹⁸fluoro-2-deoxy-d-glucose positron emission tomography computed tomography (¹⁸FDG PET) after several courses of chemotherapy for metastatic evaluation. Unexpectedly, on ¹⁸FDG PET scan, no discernible uptake was observed in the visceral organs, but instead, the skeleton/bone marrow showed homogenously intense metabolic activity. The distribution of ¹⁸FDG observed on the scan was remarkably similar to that on the NaF PET scan, indicating a superscan appearance.

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Lymphadenitis, due to typical or atypical Mycobacterium, is a clinical condition frequently associated with human immunodeficiency virus (HIV) infection. Differential diagnosis between benign and malignant causes may be a challenge for clinicians. In this regard, the role of positron emission tomography (PET) with ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) has still not been fully explored. We describe a case of 30-year-old male, infected by HIV, with mycobacterial lymphadenitis, in which ¹⁸FDG-PET and PET-derived parameters resulted useful for guiding diagnosis and monitoring the response to treatment.

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This case is a very good example of how a multimodality approach was taken in diagnosis and management of patient with suspected uterine sarcoma, which turned out to be uterine leiomyoma with parasitic leiomyoma mimicking the pararenal deposit. There has been an increased use of fluorodeoxyglucose avid positron emission tomography-computed tomography in pelvic malignancies, especially in the cases where there is suspected extrapelvic spread. It was an interesting finding of parasitic leiomyoma, which can be easily thought to be as deposit/mass in a patient with pelvic malignancy.

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Abnormal Pertechnetate distribution can occur due to many reasons such as retrosternal extension of eutopic thyroid gland, ectopic functioning thyroid gland, physiological uptake in esophagus, teratoma having functioning thyroid tissue component, metastatic lymph nodes and sequestered thyroid nodule. We present a case of thyrotoxicosis with hyper functioning thyroid gland and two abnormal foci of uptake in the mediastinum in a linear fashion that mimcked esophageal activity. These foci persisted even after consuming water. SPECT localised these foci in retrosternal and likely to be ectopic functioning thyroid. Retrosternal ectopic thyroid tissue may not usually be detected on Tc-99m scan due to attenuation of low-energy gamma rays by sternal bone. However, hyperfunctioning tissue enabled visualization of the retrosternal ectopic thyroid.

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