Side Effects of Oncologic Treatment in the Chest: Manifestations at FDG PET/CT.

Fluorodeoxyglucose (FDG) PET/CT is a vital imaging technique used for staging, assessing treatment response, and restaging following completion of therapy in patients who are undergoing or have completed oncologic treatment. A variety of adverse effects from chemotherapy, targeted therapy, immunotherapy, and radiation therapy are commonly encountered in oncologic patients. It is important to be aware of the manifestations of these adverse effects seen on FDG PET/CT images to avoid misinterpreting these findings as disease progression. Furthermore, early identification of these complications is important, as it may significantly affect patient management and even lead to a change in treatment strategy. The authors focus on the FDG PET/CT manifestations of a broad spectrum of oncologic therapy-related adverse effects in the thorax, as well as some treatment-related changes that may potentially mimic malignancy. Online supplemental material is available for this article. ©RSNA, 2021.

Ventilation-Perfusion Scan: A Primer for Practicing Radiologists.

Lung scintigraphy, or ventilation-perfusion (V/Q) scan, is one of the commonly performed studies in nuclear medicine. Owing to variability in clinical applications and different departmental workflows, many trainees are not comfortable interpreting the results of this study. This article provides a simplified overview of V/Q imaging, including a review of its technique, interpretation methods, and established and emerging clinical applications. The authors review the role of V/Q imaging in evaluation of acute and chronic pulmonary embolism, including the role of SPECT/CT and comparing V/Q scan with CT angiography. In addition, a variety of other applications of pulmonary scintigraphy are discussed, including congenital heart disease, pretreatment planning for lung cancer and emphysema, posttransplant imaging for bronchiolitis obliterans, and less common vascular and nonvascular pathologic conditions that may be detected with V/Q scan. This article will help radiologists and residents interpret the results of V/Q scans and understand the various potential clinical applications of this study. Online supplemental material is available for this article. ©RSNA, 2021.

Risk Stratification of 18F-Fluorodeoxyglucose-Avid Thyroid Nodules Based on ACR Thyroid Imaging Reporting and Data System.

OBJECTIVE: Fine needle aspiration (FNA) of thyroid nodules is often requested based on 18F-fluorodeoxyglucose (FDG) uptake regardless of sonographic features. The purpose of this study is to determine the risk of malignancy in FDG-avid thyroid nodules when stratified according to the ACR Thyroid Imaging Reporting and Data System (TI-RADS). METHODS: This retrospective study included patients who underwent ultrasound-guided FNA between January 1, 2010, and November 19, 2018, and PET/CT within 1 year before the FNA. In all, 170 nodules in 166 patients (65 men, 101 women, age 60.2 ± 14.3 years) were eligible for inclusion, of which 151 had a clearly benign or malignant histology. PET images were reviewed for maximum standardized uptake value and nodule location. Sonographic features and TI-RADS category were determined by three radiologists. Patient charts were reviewed for histology. Statistical analyses included risk of malignancy in FDG-avid nodules within each TI-RADS category. RESULTS: Of the 151 nodules, 52 were malignant (34.4%). Malignancy risk was 0% in 1 TR1 nodule (compared with 0.3% in the published TI-RADS study), 16.7% in 6 TR2 nodules (compared with 1.5%), 13.2% in 38 TR3 nodules (compared with 4.8%), 23.7% in 59 TR4 nodules (compared with 9.1%), and 68.1% in 47 TR5 nodules (compared with 35.0%). DISCUSSION: The majority (71%, 121 of 170) of FDG-avid thyroid nodules are TR4 and TR5, with rates of malignancy greater than those in the general TI-RADS population. ACR TI-RADS is helpful in stratification of FDG-avid nodules; the risk of malignancy in sonographically low-suspicion nodules (13.3%, 6 of 45) is significantly lower than high-suspicion nodules (43.4%, 46 of 106, P < .001).