Neuroendocrine neoplasms (NENs) are a very diverse group of tumors with a worldwide rise in incidence. Systemic therapy remains the mainstay treatment for unresectable and/or metastatic NENs. ¹⁷⁷Lu-DOTATATE, a radiopharmaceutical which emits beta particles, has emerged as a promising therapy for metastatic gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs). However, limited treatment options are available particularly after the failure of ¹⁷⁷Lu-DOTATATE therapy. This review aims to identify and summarize the available evidence for, and potential adverse events of, targeted alpha-particle therapy (TAT) in the treatment of metastatic NENs, specifically GEP-NENs. The MEDLINE, EMBASE, SCOPUS, and Cochrane Library databases were searched. Two articles which met the inclusion criteria were identified and included in the review. Putative radiopharmaceuticals that can be considered for metastatic NEN treatment include ²²⁵Actinium (²²⁵Ac)-DOTATATE and ²¹³Bismuth (²¹³Bi)-DOTATOC. There was evidence of partial response using both radiopharmaceutical agents without significant hematological, renal, or hepatotoxicity. Future studies should consider longer term, randomized controlled trials investigating the role of TAT, in particular, ²²⁵Ac-DOTATATE, in the treatment of metastatic NENs.

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The ventilation/perfusion (V/Q) single-photon emission computed tomography is the first method of diagnosis for pulmonary embolism in pregnant women. This study aimed to calculate the fetal absorbed dose and compare to recommended values in V/Q scan at three trimesters of pregnancy by Monte Carlo simulation (code MCNPX) using simulated phantoms, based on the adult female MIRD phantom. The collection of pregnant women phantoms (that of Stabin) was designed with changes in the MIRD phantom. Source organs were defined for each of the radiopharmaceuticals used in two scans, ¹³³Xe and ^81mKr for the lung and bladder and technetium diethylene-triamine-pentaacetate (^99mTc-DTPA) aerosol for lung ventilation scan. Also, technetium macroaggregated albumin (^99mTc-MAA) for lung ventilation scan, lung, bladder, and liver. Fetal absorbed dose was calculated and evaluated for the administration radiopharmaceuticals using the MCNP simulation output. For 200 MBq ^99mTc-MAA, fetal absorbed dose was 1.01–1.97 mGy, which is higher than the values recommended by International Commission on Radiological Protection (ICRP). The same fetal absorbed dose was found for activities of 54 and 70 MBq in the third trimester. For ^99mTc-DTPA-aerosol, fetal absorbed dose as a ventilation tracer was within the permitted range. For ¹³³Xe and ^81mKr, it was negligible. It is concluded that the fetus received the highest absorbed dose in the third trimester of pregnancy. For this reason, in this period of pregnancy, it is recommended to use the lower administration activity and her awareness must be done.

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Aims: The aim of this study is to evaluate the efficacy of a fixed 30 mCi (1110 MBq) ¹³¹I-iodine dose for the treatment of hyperthyroidism due to uninodular or multinodular toxic goiter and identify predictors of success. Materials and Methods: Fifty-nine patients diagnosed with nonautoimmune toxic goiter were treated with a fixed 30 mCi dose of ¹³¹I-iodine and were followed at a tertiary service between 2000 and 2016. The therapy was considered successful if the patient reached euthyroidism or hypothyroidism without needing an extra ¹³¹I-iodine dose or antithyroid drugs for at least 1 year after the radioiodine therapy (RIT). Results: Patients with a single toxic nodule were younger at diagnosis (52 vs. 63 years; P = 0.007), presented a shorter disease duration until RIT (2 vs. 3.5 years; P = 0.007), smaller total thyroid volume (20 vs. 82 cm³; P = 0.044), and lower pre-RIT thyroid uptake (P = 0.043) than patients with multinodular goiter. No significant difference was seen with antithyroid drug use, thyroid-stimulating hormone and free thyroxine level, and follow-up after RIT. After RIT, 47 patients (79.66%) met the success criteria, and 12 (20.33%) remained hyperthyroid. Among the success group, 32 (68.08%) reached euthyroidism, while 31.92% developed hypothyroidism after 1 year. Patients with single toxic nodules who achieved success after RIT presented smaller nodules (2.8 vs. 5.75 cm; P = 0.043), while the pre-RIT thyroid uptake was higher among patients with multinodular toxic goiter who achieved success after RIT (5.5% vs. 1.5%; P = 0.007). A higher success rate was observed among patients with a single toxic nodule than those with a toxic multinodular goiter (92.3% vs. 55%; P = 0.001), and a single toxic nodule presentation was found to be an independent predictor of success (P = 0.009). Conclusions: The fixed 30 mCi ¹³¹I-iodine dose was particularly effective in the group of patients with single autonomously functioning nodule rather than the group with multiple nodules. A single toxic nodule was an independent predictor of treatment success.

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Insufficiency fractures (IFs) can be challenging to diagnose due to varied presentations, and sometimes, it changes the course of treatment, as in cancer patients in whom it has to be differentiated with metastatic disease. We present the role of Technetium 99m methylene diphosphonate (^99mTc-MDP) bone scan, which is a low-cost, simple to perform, whole body diagnostic investigation in the diagnosis of IFs. This is a retrospective analysis of all patients who underwent a ^99mTc-MDP bone scan in a tertiary care teaching hospital during 2013–2017 and were diagnosed as having an IF on bone scan. The bone scans were performed on a dual-head gamma camera using low-energy high-resolution collimators. Of all the bone scan performed during 2013–2017, a total of 138 patients with a mean age of 57.5 ± 14.7 years were diagnosed as having IFs based on bone scan and final clinical diagnosis. Among them, the most common complaint was regional bony pain in 62% of patients, while the most common cause was osteoporosis in 47% of patients, both postmenopausal and senile osteoporosis. In all, 265 sites of fractures were identified with a fracture average of 1.9/patient, the most common site being dorsolumbar vertebrae, followed by ribs and lower limb bones. Many unusual sites were also identified such as talus, sternum, clavicle, and scapula. ^99mTc-MDP bone scan, being noninvasive whole-body imaging, is a useful investigation for evaluation of IFs and in correlation with biochemical analysis and other imaging can be used to determine the etiology of IF.

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The aim of this study was to evaluate the effect of glycemic control as estimated by glycated hemoglobin A1c (HbA1c) on gastric emptying in patients with type 2 diabetes mellitus (DM) using gastric emptying scintigraphy (GES). This was a cross-sectional study conducted at a tertiary health care center in Northern India. The study included 44 patients who underwent GES using a radiolabeled solid Idli meal containing 1 mCi of Tc-99 m Sulfur Colloid. Patients were divided into three groups based on glycemic control as Group A, B, and C with HbA1c <7%, 7%–9%, and >9%. Statistical analysis was performed using the IBM® SPSS® Statistics Version 23.0 The comparison of proportions was done using the Chi-square test and Fisher's exact test. Means were compared using the independent t-test and one-way analysis of variance. P < 0.05 was considered statistically significant. No statistically significant correlation was found between delayed gastric emptying and glycemic control (P = 0.09), gender (P = 0.228), dietary patterns (P = 0.91), symptoms of gastroparesis (P = 0.06), body mass index (BMI) (P = 0.267), and duration of type 2 DM (P = 0.565). No statistically significant association was also found between glycemic control and time taken for half gastric emptying (t1/2) (P = 0.225). Scintigraphy using Tc-99m Sulfur Colloid radiolabeled Idli meal can be effectively used for the assessment of gastric emptying. There is no significant correlation of delayed gastric emptying with glycemic control, gender, BMI, type of diet, and duration of diabetes mellitus.

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Rendu–Osler–Weber syndrome or hereditary hemorrhagic telangiectasia (HHT) is a rare systemic disease. Its primary pathogenic expression is multiple arteriovenous malformations (AVM) and severe hypoxia. A case of suspected pulmonary embolism in a 49-year-old male with intestinal, cardiac, and pulmonary HHT affection is reported. Pulmonary AVM could create an apparent mismatch perfusion defect evident upon ventilation and perfusion scan (V/Q scan), leading to misinterpretation. It reinforces the importance between clinics, anatomy, and functional evaluation. Care must be taken when interpreting V/Q scan and the reporting physician must be alert to the possible sources of errors.

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“Hot” patella sign is a less commonly seen finding in bone scintigraphy defined as increased tracer activity in the patella greater than the ipsilateral distal femur and ipsilateral proximal tibia. We present a case of suprapatellar knee bursitis manifesting as unilateral “hot” patella sign on three-phase ^99mTc-methylene diphosphonate bone scintigraphy. This case portrays the image findings of suprapatellar bursitis on three-phase bone scintigraphy.

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As COVID-19 vaccination rates continue to rise, it is becoming increasingly important to understand diagnostic imaging associations' resultant from the vaccines. Here, we report a case of a 59-year-old female who was in remission for gastrointestinal neuroendocrine carcinoma and presented for standard follow-up imaging evaluation. Positron-emission tomography (PET) images from a ⁶⁸Ga-DOTATATE PET (NETSPOT) demonstrated moderate focal radiotracer uptake in the right axilla. Interestingly, this uptake localized to several normal-sized lymph nodes on the corresponding computed tomography (CT). A medical history revealed the patient received both doses of an ipsilateral COVID-19 messenger ribonucleic acid vaccine injection at 17 and 38 days before the PET/CT study. Subsequent scans 2 months later revealed no radiotracer uptake.

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A 35-year-old female with a 15-week period of gestation was detected with locally advanced cancer of the left breast. She was suggested to undergo a medical termination of pregnancy (MTP) followed by invasive Oncological imaging - Contrast enhanced computed tomography (CECT) chest–abdomen–pelvis/fluorodeoxyglucose positron emission tomography-CT (FDG PET-CT) for staging the disease. However, to avoid the risk of iatrogenic novel coronavirus 2019 infection to the patient, on her request, the hospital admission was carried out after the oncological workup and thus PET-CT was conducted before the MTP. FDG PET-CT revealed FDG avid primary in the left breast along with extensive metastases to liver and skeletal lesions. The developing fetus also showed physiological FDG uptake. The patient has undergone an MTP and is presently under treatment for metastatic breast cancer. The case report illustrates the radiation safety guidelines on fetal radiation exposure, steps to decrease fetal radiation exposure, and illustration of fetal FDG uptake.

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We present a case of sporadic Creutzfeldt–Jakob disease with profoundly abnormal 18fluoro-deoxy-glucose positron emission tomography with computed tomography (FDG PET-CT) at an early stage, and correlate this with the clear findings at magnetic resonance imaging and also postmortem histology. Prion diseases are rare but important causes of cognitive impairment. The role of FDG PET-CT is discussed, along with other investigations such as electroencephalography and cerebro-spinal fluid analyses.

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Marine-Lenhart Syndrome is a rare entity, described as Graves' disease with coexisting functioning thyroid nodules. It is often diagnosed on thyroid scintigraphy as a cold nodule with surrounding extranodular hyperactivity initially and postradioiodine ablation, they regain function on the follow-up thyroid scintigraphy due to endogenous thyroid-stimulating hormone (TSH) stimulation. We retrospectively reviewed all thyroid scintigraphy database performed between January 2018 and March 2020 in our institute. We searched patients with Graves' disease with the following criteria to suggest Marine-Lenhart Syndrome: (a) initial thyroid scintigraphy showing features of Graves' disease with coexistent poorly functioning nodules (b) There is normalization of uptake within the nodule on thyroid scan after radioiodine ablation suggestive of endogenous TSH stimulation (this also indirectly proves nodules are TSH dependent), (c) nodule(s) is/are benign on fine-needle aspiration cytology. Four patients (1.46%) were confirmed as Marine-Lenhart Syndrome as per the criteria. Three patients were female, and one was male. The eye signs were present in two of four patients. Two patients had two hypofunctioning nodules, whereas the remaining two had a single nodule and required re-ablation with radioiodine. Marine-Lenhart Syndrome requires special attention as these patients are relatively radioiodine resistant, require higher activity for iodine-131; however, it is curable with radioiodine treatment.

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Management of differentiated thyroid carcinoma (DTC) patients with thyroglobulin (Tg) elevation and negative iodine scintigraphy (TENIS) and negative neck ultrasound scan causes considerable diagnostic and therapeutic dilemma, especially in resource-poor settings. The aim of this study was to evaluate clinicopathological features and outcome of TENIS patients with negative neck US attending a thyroid cancer clinic in India. From a DTC database of 722 containing 193 TENIS patients, subjects with negative neck US and negative Tg antibody (TgAb) were selected retrospectively and analyzed using appropriate statistical methods. The study group included 64 patients (male – 17, female – 47, mean age – 44.7 ± 12.8 years) with 54 papillary and 10 follicular thyroid carcinomas, American Thyroid Association (ATA) recurrence risk categorization (2009) – low – 16, intermediate – 28, and high – 2 0. Most of the patients became TENIS within 1 year of diagnosis with median Tg level of 6.5 ng/mL (1.2–996 ng/mL) and mean follow-up of 7.8 years. On follow-up, Tg dropped spontaneously in 27 patients, more among the low and intermediate-risk categories. For those with high or increasing Tg level, further imaging (fluorodeoxyglucose positron emission tomography/computed tomography) was done and 14 out of 18 were positive. Treatment included empiric radioactive iodine therapy-16, external beam radiation therapy (EBRT)-7, and lymph node dissection (LND)-10. A favorable outcome was seen in 36 patients and unfavorable in 28. Distant metastases were associated with unfavorable outcome and poor survival. Progression-free survival was significantly better in the Tg group of <10 at the time of TENIS (111 months) compared to the Tg group >10 (72 months). Tg level dropped spontaneously in nearly half the patients, especially if levels were <10 and more so among the low-risk category. Distant metastasis was predictive of unfavorable outcomes. Along with Tg level, the ATA risk category might help to predict clinical course and reduce unnecessary expensive imaging in resource-poor settings.

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Encephaloceles, also known as meningoencephaloceles, are a group of neurological disorders characterized by herniation of the cerebral parenchyma along with overlying meninges through openings in the skull bone. They can be seen following congenital defect in neural tube closure or acquired defect in the skull bone. We report a case of acquired frontoethmoidal encephalocele presenting with drug-refractory epilepsy. Interictal FDG PET-computed tomography done for lateralization and localization of seizure focus showed right-sided frontoethmoidal encephalocele associated with hypometabolism in the adjacent right frontopolar cortex, concordant with ictal onset on electroencephalogram.

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Carcinoma penis is a rare malignancy accounting 0.5%–1% of cases in the developed countries with a slightly higher incidence in the developing nations. Slow locoregional progression is characteristic of penile carcinoma (PC) and distant metastases are very uncommon. We hereby report a case of highly aggressive squamous cell PC in a 46-year-old male with fulminant upfront distant dissemination to left supraclavicular lymph nodes (LNs) without involving the inguinal and pelvic nodes detected by whole-body ¹⁸F-fluorodeoxyglucose positron-emission tomography scan. The scan also detected lytic destructive lesion involving the pelvic and adjacent bones with infiltration of skeletal muscles. He was treated with palliative radiotherapy to the wight-bearing sites followed by systemic chemotherapy. A thorough review of literature reveals that our case may be one of the rarest cases ever reported in world literature where an asymptomatic PC presents with upfront supraclavicular LN metastasis bypassing the inguinal, pelvic, and retroperitoneal LN chains.

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Wilms' tumor also called as nephroblastoma is commonly seen extracranial solid tumor involving kidneys in children. Rarely, Wilms' tumor can arise from ectopic nephrogenic remnants located outside the kidneys. Extrarenal Wilms' tumor comprises 3% of total Wilms' tumor with its incidence even less common in adults. We report the staging and restaging fluorodeoxyglucose positron emission tomography-computed tomography findings in a case of locally advanced metastatic extrarenal adult Wilms' tumor involving the retroperitoneum.

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Goiter with an intrathoracic component is relatively common; however, it is less common to see extent outside the anterior or posterior mediastinum. We present a case of intrathoracic goiter of significant size and abnormal placement which is examined using both ^99mTc-pertechnetate and iodine-123 single-photon emission computed tomography/computed tomography.

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¹⁸F-2-fluoro-2-deoxy-D-glucose ([¹⁸F]-FDG) positron emission tomography (PET) CT has proven useful in the evaluation of high-grade glioma and is also useful as a predictor of the degree of malignancy in newly diagnosed brain tumors. It is commonly accepted that high-grade gliomas are characterized by increased FDG uptake, whereas the low-grade glioma demonstrates reduced or absent FDG uptake. [¹⁸F]-FDOPA is an amino acid PET tracer which is a marker of the proliferative activity of brain tumors and demonstrates positive uptake in all grades of brain tumors; however, the degree of tracer uptake is significantly higher in high-grade tumors as compared to low-grade tumors. Here, we discuss a case where both FDG and DOPA PET/CT scans raised suspicion of low-grade glioma; however, the final histopathology report confirmed WHO grade IV Glioblastoma.

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Congenital hyperinsulinism (CHI) is responsible for hyperinsulinemic hypoglycemia which needs aggressive treatment in order to prevent neurological damages. Recent advances in genetics have linked CHI to mutations in many different genes that play a key role in regulating insulin secretion from pancreatic ß-cells. Furthermore, histopathological lesions, diffuse and focal, have been associated with these different genetic alterations. This short manuscript describes how the advent of fluorine-18-labeled L-dihydroxyphenylalanine-positron emission tomography/computed tomography (¹⁸F-DOPA-PET/CT) scanning has changed the management of patients with CHI. ¹⁸F-DOPA PET/CT imaging differentiates focal from diffuse disease and is 100% accurate in localizing the focal lesion. In these patients, the lesion can be surgically removed allowing complete resolution of clinical alterations. We report a case in which clinical experience together with rapid genetic analysis and imaging with ¹⁸F-DOPA-PET/CT, were able to guide the correct clinical management of this condition. We confirm that advances in molecular genetics, imaging methods (¹⁸F-DOPA PET-CT), medical therapy, and surgical approach have completely changed the management and improved the outcome of these children.

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COVID-19 is a viral respiratory disease associated with neurologic complications such as encephalitis or stroke in a minority of patients. The wide variety of neurologic manifestations with often unclear etiology may confound diagnosis and management. We present a young man admitted following an 8-day onset of self-resolving episodes of left hemiplegia and hemifacial droop. Diagnostic work up for seizures and stroke was largely negative. “Intra-ictal” ECD-single-photon emission computerized tomography/computerized tomography was consistent with right middle cerebral artery ischemia. Subsequent diagnostic work up revealed positive COVID-19 screening and newly-elevated antiphospholipid antibodies. Antiepileptic medications were discontinued, and the patient was successfully treated as an outpatient with corticosteroids leading to resolution of symptoms.

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Multiple primary malignancies in a cancer patient are not a rare occurrence. The most common presentation of multiple primary malignancies is dual malignancies. The usefulness of different positron emission tomography (PET)/computed tomography (CT) tracers in the evaluation of dual synchronous primary malignancies is not well documented. Here, we present a case series, where two patients, referred for PET/CT, after being diagnosed with one primary malignancy were found to be having a second primary malignancy, diagnosed incidentally in PET/CT, further validated by PET/CT with another tracer.

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