Indian Journal of Nuclear Medicine最新文献

Nuclear medicine has transformed healthcare delivery and played a crucial role in improving the quality of life of patients. Although nuclear medicine has multiple applications, its usage and acceptance among the general population is being influenced by the prevailing myths and misinformation. The need of the hour is that we must take targeted interventions to address these myths with information to augment the confidence of the general population, including its life-saving potential. In conclusion, nuclear medicine has a broad scope in healthcare delivery but the presence of myths and misconceptions about nuclear medicine has limited its utilization. This calls for organizing public health campaigns, empowering healthcare professionals, and facilitating transparent communication for optimal utilization.

Introduction: Amyloidosis is characterized by the extracellular deposition of fibrillar proteins, leading to tissue damage and dysfunction. Cardiac amyloidosis (CA) occurs when these fibrils accumulate in the heart's extracellular matrix, causing infiltrative cardiomyopathy, heart failure, and potentially death. Early diagnosis is imperative in accurate management. Transthyretin amyloidosis, either hereditary or age-related, is a common cause of CA, often presenting with left ventricular hypertrophy (LVH) and heart failure with preserved ejection fraction (HFpEF). This study investigates the utility of Tc-99 m Pyrophosphate (Tc-99 m PYP) imaging in diagnosing Transthyretin Amyloidosis ((ATTR)-CA) in patients with unexplained LVH.

Materials and methods: This prospective observational study, conducted between January 2023 and June 2024, involved 52 patients with clinical suspicion of CA and left ventricular wall thickness >12 mm. Patients underwent Tc-99 m PYP scintigraphy, and the results were categorized as positive, negative, or equivocal.

Results: The study population's mean age was 64.6 years, with a male predominance (69%). Of the 52 patients, 9 (17.3%) had positive, 28 (53.8%) negative, and 15 (28.8%) equivocal Tc-99 m PYP scan results. Echocardiographic features, such as septal hypertrophy and granular speckled appearance, were significantly associated with positive scan findings. Comorbidities such as coronary artery disease and dyslipidemia were also common. Cardiac biomarkers NT-proBNP and troponin I showed elevated levels in patients with positive scan results.

Conclusion: Tc-99 m PYP imaging is an effective noninvasive tool for diagnosing ATTR CA, particularly in patients with unexplained LVH. The presence of HFpEF, abnormal ECG, and restrictive features on echocardiography should prompt further investigation for CA. Early diagnosis allows for timely management, improving patient outcomes.

Besides tumor imaging, ¹⁸fluorine-fluorodeoxyglucose (FDG) is equally useful for the detection of inflammatory diseases such as polymyalgia rheumatica and large vessel vasculitis. Critical incidental findings might be observed with FDG positron emission tomography/computed tomography (PET/CT) needing urgent medical attention and intervention. We present a case of an 81-year-old patient with a history of polymyalgia rheumatica. Cardiac activity representing an evolving non-ST segment elevation myocardial infarction was detected incidentally by FDG PET/CT.

^99mTc-methylene diphosphonate bone scintigraphy is a cornerstone imaging modality for skeletal assessment; however, extraosseous radiotracer uptake may signal underlying systemic metabolic derangements. Diffuse pulmonary uptake, classically linked to metastatic calcification, is commonly observed in chronic kidney disease patients with calcium-phosphate homeostasis disruption. We present an uncommon case of bilateral pulmonary ^99mTc-Methylene diphosphonate (MDP) uptake in a 48-year-old female with advanced cervical carcinoma, renal insufficiency, and severe hypercalcemia accompanied by paradoxically normal parathyroid hormone levels. While thoracic computed tomography showed no structural abnormalities, bone scintigraphy demonstrated diffuse pulmonary radiotracer accumulation, consistent with metastatic calcification secondary to calcium-phosphate deposition within alveolar walls. This case underscores the critical need for vigilant monitoring of metabolic complications in oncology patients, especially those with renal impairment, and highlights the diagnostic value of bone scintigraphy in identifying occult extraskeletal pathologies, even when conventional imaging appears unremarkable. The findings advocate for integrating metabolic profiling with functional imaging to better understand atypical tracer uptake patterns in high-risk populations.

Positron emission tomography (PET) with ¹⁸F-fluorodeoxyglucose for detection of active inflammation is well documented; however, the in vivo visualization of immune-mediated tissue remodeling has not been possible till date. With the recent development of ⁶⁸Ga-fibroblast activation protein inhibitors (FAPI), which specifically binds to the activated fibroblasts located around the synovium allowing for the visualization of mesenchymal and stromal activation process in vivo, it is possible to use this modality to use as an objective indicator of disease activity. We observed increased FAPI uptake around all the large joints of the bilateral upper and lower limbs of a chronic polyarthralgia patient. In view of the specificity of FAPI for the activated fibroblasts, the possibility of future therapeutic approach using FAPI must, therefore, be kept in mind.

Struma ovarii (SO) is a rare ovarian teratoma with predominant thyroid tissue. Malignant SO (MSO) occurs in 5%-10% of cases, with papillary and follicular thyroid carcinomas being the most common malignant types. The disease is typically diagnosed in women aged 40-60 years, and management protocols are not well defined due to its rarity. We report the case of a 37-year-old female who initially presented with vague abdominal pain and a complicated right ovarian cyst and who underwent right oophorectomy. Histopathology confirmed SO. Two years later, she experienced a recurrence with elevated cancer antigen 125 levels and a new left adnexal mass. The surgical intervention included total abdominal hysterectomy, with left Salpingo-ophorectomy and laparotomy revealing disseminated disease. A total thyroidectomy showed no malignancy, and the patient required multiple doses of radioactive iodine (RAI). Over 20 years, she received a cumulative dose of 1250 mCi of RAI and remains asymptomatic with stable disease. MSO is a rare tumor that often requires a combination of surgical intervention and RAI therapy for effective management. This case highlights the importance of a multidisciplinary approach, including surgery and RAI, in managing extensive or recurrent MSO, and provides insights into long-term management and outcomes.

A 77-year-old male presented with pyrexia of unknown origin. Chest computed tomography (CT) showed adrenal lesions, a suspicion of neoplasia was raised, and Fluorodeoxyglucose Positron Emission Tomography (FDG PET-CT) was recommended. Since the patient had uncontrolled diabetes (Fasting Blood Sugar - 326 mg/dL), FDG-PET was not feasible. The patient, therefore, underwent Ga68-Fibroblast Activating Protein Inhibitor - 46 PET-CT (FAPI PET-CT). Scan showed high-grade Fibroblast Activating Protein (FAP) expression in bilateral enlarged adrenals. Findings appeared atypical for malignancy and the possibility of chronic inflammatory/infectious condition was raised. Biopsy proved adrenal histoplasmosis (AH). Although FDG avidity in AH is known and previously reported, this is best to our knowledge the first literature documentation of FAP expression in AH.

Mucosal melanomas (MMs) represent a rare subset of melanomas arising from melanocytes in noncutaneous sites such as mucosal membranes of the head-and-neck, gastrointestinal, and genitourinary tracts. Unlike cutaneous melanomas, MMs often present late due to their occult nature, leading to a poor prognosis. Fluorine-18 fludeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) is widely utilized for staging and monitoring melanomas, leveraging their characteristic high FDG avidity. Recently, fibroblast activation protein inhibitor (FAPI)-based PET/CT imaging has become a popular modality in the evaluation of various cancers. Here, we present a case of MM where FDG avidity was notably absent and mild FAPI avidity, despite the lesion's typical anatomical location and clinical suspicion. This case highlights an uncommon scenario within the literature and underscores the variability in radiotracer uptake observed in MMs, challenging conventional imaging expectations and potentially impacting clinical management decisions.

The interpretation of F-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) scans can be confounded by incidental findings, as illustrated in this case of a 47-year-old woman with a history of breast carcinoma. Following neoadjuvant chemotherapy and mastectomy, she underwent FDG PET/CT for disease evaluation, revealing unexpected hypermetabolic activity in the right iliac fossa corresponding to acute appendicitis. Thus, FDG PET/CT has the potential to uncover treatable conditions beyond cancer and imaging findings need clinical correlation.

Langerhans Cell Histiocytosis (LCH) is a rare neoplasm of the hematopoietic system, characterized by the clonal proliferation of Langerhans cells and it is more common in children. We present two interesting adult cases of LCH, diagnosed with the help of FDG PET-CT imaging which is often challenging to diagnose due to its rarity and nonspecific clinical presentation.