Asha Kandathil

Metabolic and anatomic characteristics of benign and malignant adrenal masses on positron emission tomography/computed tomography: a review of literature

PET/CT with 18F-fluorodeoxyglucose (FDG) or using different radiocompounds has proven accuracy for detection of adrenal metastases in patients undergoing cancer staging. It can assist the diagnostic work-up in oncology patients by identifying distant metastases to the adrenal(s) and defining oligometastatic disease that may benefit from targeted intervention. In patients with incidentally discovered adrenal nodules, so-called adrenal “incidentaloma” FDG PET/CT is emerging as a useful test to distinguish benign from malignant etiology. Current published evidence suggests a role for FDG PET/CT in assessing the malignant potential of an adrenal lesion that has been ‘indeterminately’ categorized with unenhanced CT, adrenal protocol contrast-enhanced CT, or chemical-shift MRI. FDG PET/CT could be used to stratify patients with higher risk of malignancy for surgical intervention, while recommending surveillance for adrenal masses with low malignant potential. There are caveats for interpretation of the metabolic activity of an adrenal nodule on PET/CT that may lead to false-positive and false-negative interpretation. Adrenal lesions represent a wide spectrum of etiologies, and the typical appearances on PET/CT are still being described, therefore our goal was to summarize the current diagnostic strategies for evaluation of adrenal lesions and present metabolic and anatomic appearances of common and uncommon adrenal lesions. In spite of the emerging role of PET/CT to differentiate benign from malignant adrenal mass, especially in difficult cases, it should be emphasized that PET/CT is not needed for most patients and that many diagnostic problems can be resolved by CT and/or MR imaging.

Revisions to the Tumor, Node, Metastasis staging of lung cancer (8th edition): Rationale, radiologic findings and clinical implications

The Tumor, Node, Metastasis (TNM) staging system, adopted by the Union for International Cancer Control (UICC) and the American Joint Committee on Cancer (AJCC), has been recently revised, with the new 8th edition of the staging manual being published in January 2017. This edition has few but important evidence-based changes to the TNM staging system used for lung cancer. Radiologists should be aware of the updated classification system to accurately provide staging information to oncologists and oncosurgeons. In this article, we discuss the rationale, illustrate the changes with relevance to Radiology, and review the clinical implications of the 8th edition of the UICC/AJCC TNM staging system with regards to lung cancer.

Extraosseous findings on bone scintigraphy using fusion SPECT/CT and correlative imaging

OBJECTIVE Extraosseous radioactivity outside of the expected biodistribution is often encountered on (99m)Tc-methylene diphosphate (MDP) bone scintigraphy, and proper interpretation requires an understanding of the mechanisms underlying this uptake and knowledge of the possible causes, depending on the site or structure involved. CONCLUSION We present examples of extraosseous radiotracer uptake seen on (99m)Tc-MDP bone scans in which either SPECT with integrated CT or correlative imaging improved the studys interpretation.

PET/Computed Tomography and Precision Medicine: Musculoskeletal Sarcoma

Skeletal and soft tissue sarcomas need early and accurate diagnosis, staging, and treatment for optimal outcome. 18F-FDG PET/computed tomography (CT) is indicated in staging of patients with high-grade sarcomas and acts as a surrogate marker of histopathologic grade, guiding biopsy to most aggressive portion of the tumor. Pretherapy and posttherapy 18F-FDG PET/CT metabolic parameters are reliable indicators of survival in patients with sarcoma with an important role in posttreatment response assessment, enabling the treatment plan to be modified in nonresponders. 18F-FDG PET/CT is particularly useful in the evaluation of molecular targeted therapies, which induce metabolic change before structural change.

Nuclear medicine imaging of endocrine neoplasms

Endocrine tumors are hormonally active benign or malignant neoplasms arising within endocrine organs or from specialized cells of the amine precursor uptake and decarboxylation system. The detection rate of these tumors is increasing as a result of sensitive biochemical tests and high-resolution diagnostic imaging. Medical imaging has become a key component in the diagnosis and staging of endocrine malignancies; however, despite the impressive advances in computed tomography (CT) and MRI, detection of small primary tumors and metastases continues to be a challenge. Functional imaging techniques use radiopharmaceuticals targeted at unique tumor cellular processes in order to provide sensitive and highly specific whole-body imaging. Functional imaging allows prediction of the efficacy of radionuclide or receptor-based therapies and surveillance after therapy. Advances in imaging have not been limited to radiopharmaceuticals. Hybrid scanner technology in the form of PET/CT and single photon emission computed tomography (SPECT)/CT, designed to combine functional images with anatomic maps, has further improved the diagnostic accuracy. High-resolution hybrid imaging when deployed with novel PET and SPECT radiopharmaceuticals has the potential to dramatically change, individualize, and optimize imaging plans based on the histological grade, degree of differentiation, and genetic profile of each patient’s endocrine neoplasm.

Pulmonary vascular anatomy & anatomical variants

The vessels supplying the lungs include the pulmonary arteries, pulmonary veins, and bronchial arteries. The segmental and sub segmental pulmonary arteries parallel the bronchi and are named according to the bronchopulmonary segments they supply. There are however considerable anatomic variations, particularly in the upper lobes with variations in number or presence of accessory arteries from adjacent segments. The subsegmental pulmonary vein branches, run within interlobular septa and do not parallel the segmental or sub segmental pulmonary artery branches and bronchi. They converge to form right and left superior and inferior pulmonary veins which drain into the left atrium. Knowledge of normal and variant anatomy on cross-sectional and angiographic images is essential for accurate diagnosis of vascular pathology and aids planning of interventional procedures.

Pulmonary vascular pathophysiology

Knowledge of pulmonary vascular pathophysiology is crucial to understand the various disease processes and their medical management. Pulmonary vascular system constitutes the right sided circulation which is distinct from the left side circulation and facilitates unique hemodynamic properties to adapt to a multitude of external demands and circumstances. With growing prevalence and increasing ability to diagnose and treat pulmonary diseases, this review becomes more relevant.

Neuroendocrine Tumor Diagnosis and Management: 68Ga-DOTATATE PET/CT

OBJECTIVE The purpose of this article is to provide a review of the use of 68Ga tetraazacyclododecanetetraacetic acid-DPhe1-Tyr3-octreotate (DOTATATE) PET/CT, a functional imaging modality for assessment of well-differentiated neuroendocrine tumors (NETs). It has become the preferred imaging modality for initial diagnosis, selection of patients for peptide receptor radionuclide therapy, and localization of unknown primary tumors. The National Comprehensive Cancer Network guideline has added 68Ga-DOTATATE PET/CT as an appropriate test in the management of NETs. CONCLUSION In combination with FDG PET/CT, 68Ga-DOTATATE PET/CT can noninvasively assess tumor heterogeneity, especially in G2 and G3 NETs, for personalized management of patients.

Functional Oncological Imaging of the Endocrine System

Endocrine tumors are hormonally active benign or malignant neoplasms arising within endocrine organs or from specialized cells of the amine precursor uptake and decarboxylation (APUD) system that are increasing in incidence as a result of sensitive biochemical tests and high-resolution diagnostic imaging. Not unlike tumors of other systems, endocrine neoplasms are heterogenous with variable prognosis characterized by well-differentiated thyroid cancer with very favorable outcome, medullary thyroid cancer and neuroendocrine-type tumors with intermediate outcomes, and anaplastic thyroid, adrenocortical, and Merkel cell cancers with the poorest clinical outcomes. Medical imaging has become a key component in diagnosis and staging of endocrine malignancies; however, even with great advances in computed tomography and magnetic resonance imaging, detection of small primary tumors and metastases continues to be a challenge. Complimentary functional imaging targets tumor cellular processes that actively accumulate radiopharmaceuticals, allowing sensitive and highly specific oncological imaging. Surveillance of endocrine malignancies commonly combines functional imaging with tumor-specific laboratory biomarkers. Furthermore, functional imaging studies can predict efficacy of radionuclide or receptor-based therapies. The last decade has seen an increasing use of combined PET-CT and SPECT-CT scanners designed to create functional and anatomic maps with resultant incremental diagnostic capabilities. These technologies together with the development of novel PET and SPECT radiopharmaceuticals make patient-individualized functional imaging protocols possible, based on the histological grade, degree of differentiation, and genetic profile of their endocrine neoplasm.