Impact of Lung Parenchymal-Only Failure on Overall Survival in Early-Stage Lung Cancer Patients Treated With Stereotactic Ablative Radiotherapy.

INTRODUCTION: The impact of lung parenchymal-only failure on patient survival after stereotactic ablative body radiotherapy (SABR) for early-stage non-small-cell lung cancer (NSCLC) remains unclear. PATIENTS AND METHODS: The study population included 481 patients with early-stage NSCLC who were treated with 3- to 5-fraction SABR between 2000 and 2016. The primary study objective was to assess the impact of out-of-field lung parenchymal-only failure (OLPF) on overall survival (OS). RESULTS: At a median follow-up of 5.9 years, the median OS was 2.7 years for all patients. Patients with OLPF did not have a significantly different OS compared to patients without failure (P = .0952, median OS 4.1 years with failure vs. 2.6 years never failure). Analysis in a 1:1 propensity score-matched cohort for Karnofsky performance status, comorbidity score, and smoking status showed no differences in OS between patients without failure and those with OLPF (P = .8). In subgroup analyses exploring the impact of time of failure on OS, patients with OLPF 6 months or more after diagnosis did not have significantly different OS compared to those without failure, when accounting for immortal time bias (P = .3, median OS 4.3 years vs. 3.5 years never failure). Only 7 patients in our data set experienced failure within 6 months of treatment, of which only 4 were confirmed to be true failures; therefore, limited data are available in our cohort on the impact of OLPF for ≤ 6 months on OS. CONCLUSION: OLPF after SABR for early-stage NSCLC does not appear to adversely affect OS, especially if occurring at least 6 months after SABR. More studies are needed to understand if OLPF within 6 months of SABR is associated with adverse OS. These data are useful when discussing prognosis of lung parenchymal failures after initial SABR.

PET and SPECT Imaging of the Brain: History, Technical Considerations, Applications, and Radiotracers.

Advances in nuclear medicine have revolutionized our ability to accurately diagnose patients with a wide array of neurologic pathologies and provide appropriate therapy. The development of new radiopharmaceuticals has made possible the identification of regional differences in brain tissue composition and metabolism. In addition, the evolution of 3-dimensional molecular imaging followed by fusion with computed tomography and magnetic resonance imaging have allowed for more precise localization of pathologies. This review will introduce single photon emission computed tomography and positron emission tomographic imaging of the brain, including the history of their development, technical considerations, and a brief overview of pertinent radiopharmaceuticals and their applications.

PET/MRI vs PET/CT in Head and Neck Imaging: When, Why, and How?

The increasing availability of hybrid PET/MRI systems has led to a breadth of new publications and opportunities for use of PET/MRI. While PET/CT has been a valuable tool for oncologic staging, including head and neck malignancy, there are several theoretical and practical advantages a PET/MRI system would have over PET/CT in head and neck imaging. This review article discusses the established role of PET/CT, early evidence for the role of PET/MRI, and protocol considerations for both PET/CT and PET/MRI as they apply to head and neck imaging.

Using radiology to teach physiology.

BACKGROUND: Radiology is well poised to play an important role in the teaching of physiology, one of the core disciplines of medicine. Physiology is an absolutely foundational medical discipline that informs every diagnostic test and therapy physicians prescribe, and radiology teaches a deep understanding. METHODS: Radiologic case studies using pairs of radiologic cases, one illustrating normal physiology and the second illustrating pathophysiology, are presented. The presentation uses the 2 radiologic images (normal and pathophysiology) to focus on 4 broad physiologic principles that apply across all organ systems. These principles are (1) homeostasis, (2) biologic energy use, (3) structure-function relationships, and (4) communication. Two examples are given for each of the principles. RESULTS: Radiologic case studies teach the integrating principles. A demonstration of the first integrated principle, homeostasis, is given. For example, cerebral perfusion scintigraphy measures blood flow to the brain and can determine if flow is disrupted. Normal results will demonstrate the tracer in the arteries and veins during the flow phase and accumulation of the tracer within the brain during the delayed imaging. A second clinical example of homeostasis is erythropoiesis. Two radiologic examples of each principle (normal and pathologic) support the use of radiology to teach physiology. CONCLUSION: Radiologic case studies can illustrate physiologic principles in ways that can enhance students' grasp of both the physiology and its role in helping physicians take better care of patients. Working with actual images brings physiology to life; the learning is relevant and practical.