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Coronary Arterial Imaging

1 What are some noninvasive methods of coronary artery imaging? Imaging the coronary arteries is an important part of evaluating ischemic heart disease. Traditionally, this imaging has been performed using cardiac catheterization, an invasive procedure that requires arterial puncture. Newer technologies promise noninvasive, cross-sectional imaging of coronary artery patency and offer the potential to characterize coronary artery plaque. Coronary magnetic resonance imaging (MRI), using bright blood,…

Aortic Imaging

1 What is the normal imaging appearance of the aorta on computed tomography (CT) and magnetic resonance imaging (MRI)? The normal aorta on imaging can be divided into the following five parts: the aortic root, the ascending aorta, the proximal (anterior) aortic arch, the distal (posterior) aortic arch, and the descending thoracic aorta. The proximal segment of the ascending aorta is the aortic root, which begins…

Cardiac and Pericardiac Imaging

1 What forms the borders of the heart on the frontal posteroanterior (PA) or anteroposterior (AP) chest radiograph? The chest radiograph represents an important first step in the imaging workup of cardiovascular disease. On a PA frontal view of the chest, a cardiothoracic ratio (cardiac width : thoracic width) of less than 1 : 2 is considered normal in adults. Analysis of the cardiac silhouette can yield valuable information about…

Breast MRI

1 What are the indications for breast magnetic resonance imaging (MRI)? General indications for breast MRI include: Establish the extent of disease in the setting of a newly diagnosed breast cancer. Further evaluate an imaging finding that is incompletely characterized by diagnostic mammography and/or breast ultrasonography (US). Evaluate for residual disease in the setting of positive margins after lumpectomy or other operative procedure. Evaluate a patient…

Diagnostic Mammography

1 What are the indications for a diagnostic mammogram? Some indications for a diagnostic mammogram include a history of breast cancer, breast lump, nipple discharge, focal breast pain, breast implants, history of breast biopsy, history of an abnormal mammogram, and follow-up for a previously evaluated mammographic finding (BI-RADS category 3 lesion). 2 What views are performed for diagnostic mammography? How are patients who have undergone diagnostic…

Screening Mammography

1 What is a screening mammogram? A screening mammogram is a radiographic examination of the breasts performed to detect clinically occult breast cancer in asymptomatic women. 2 When should an average woman start getting mammograms? This is currently a topic of debate. The American College of Radiology (ACR) recommends that a woman get a baseline mammogram at age 40 and annual screening mammograms thereafter. The American…

Radiation Dose and Safety Considerations in Imaging

1 What is the terminology for radiation dose? Absorbed dose, equivalent dose, and effective dose are all used to describe the effects of radiation on tissue. Absorbed dose specifically refers to the energy transferred to a quantity of tissue by ionizing radiation. Equivalent dose can be derived from absorbed dose by applying a weighting factor that describes the type of radiation, in order to account for…

Introduction to Contrast Agents

1 What is a radiographic contrast agent? A radiographic contrast agent is a substance that is administered to a patient during an imaging examination to improve its diagnostic performance. Contrast agents are most often administered via the intravenous (IV) and oral routes for computed tomography (CT) and magnetic resonance imaging (MRI) examinations. However, other routes of contrast administration may be utilized, depending on the particular imaging…

Computers in Radiology

1 What is PACS? PACS stands for Picture Archiving and Communication System. On the most basic level, PACS integrates image acquisition modalities, workstation displays, the image archiving system, and the underlying network. 2 How are PACS images stored? The PACS archive traditionally has been composed of short-term and long-term storage. Short-term storage is usually composed of redundant arrays of inexpensive (or independent) discs (RAID) arrays that…

Introduction to Image Processing, Visualization, and Analysis

1 What is a digital image? A digital image is an image discretized in spatial coordinates and in brightness. It can be represented by a multidimensional array of integers. 2 What is the difference between a pixel and a voxel? A pixel, or picture element, is the smallest element of a 2D digital image that can be individually processed, whereas a voxel, or volume element, is…

Introduction to Nuclear Medicine and Molecular Imaging

1 What is molecular imaging? Molecular imaging is the visualization, characterization, and measurement of biologic processes at the molecular and cellular levels in humans and other living systems. It is essentially a noninvasive means to study in vivo biochemistry and cell biology and is useful to optimize diagnosis and therapy of disease in individualized patients. Nuclear medicine techniques and optical imaging techniques are most commonly used…

Introduction to Ultrasonography, CT, and MRI

Ultrasonography (US) 1 What is ultrasonography (US), and how does it work? US is a structural imaging technique that uses high-frequency mechanical ultrasound waves (with frequencies greater than audible sound waves) to create real-time tomographic (cross-sectional) images. A hand-held transducer is applied to a part of the body to transmit ultrasound waves into the patient. Reflected ultrasound waves (echoes) are then detected by the transducer and…

Introduction to Radiography, Fluoroscopy, and Tomosynthesis

Radiography 1 What is radiography? Radiography is an imaging technique that uses x-rays to create projectional (2D) images of a region of interest in the body. It is performed by shining x-rays on a film or other image detector with a patient placed in front of it in a certain orientation. Different types of tissues in the patient attenuate x-rays to different degrees, leading to formation…

Internet, Social Media, and Applications

Introduction The Digital Revolution began in the latter half of the 20th century with the first uses of digital computers and data storage. The 1970s saw the development of the first microprocessor, Intel’s 4004, which marked the advent of the rapidly doubling processor speeds predicted by Moore’s Law. These exponential increases in computing power have since drastically changed how businesses and individuals interact by leading to…

Leadership: A Manifesto for the Nonclinical Education of Radiologists Looking to Succeed in Difficult Times

Introduction Historically, to be successful in their professional careers, radiologists must train intensively for years. They must master a daunting amount of clinical material, pass comprehensive tests, and meet a wide array of challenges in their training. That has not changed during my own career (now around a quarter-century in length) and, if anything, the amount of material that radiologists are expected to master keeps increasing…

Malpractice and Radiology: A Hapless Relationship

Prologue To gain a more meaningful understanding of the current state of affairs with regard to medical malpractice litigation in the United States, we begin by looking back at certain events that have brought us to the present. England, 1765 British legal scholar Sir William Blackstone published Commentaries on the Laws of England, in which “neglect or unskillful management of a physician or surgeon” was referred…

Emergency Radiology

Communication in Emergency Radiology Physician-to-Patient Communication Physician-to-patient communication is a unique challenge for radiologists. Radiologists and patients often have isolated encounters, without any prior patient-physician relationship established. Most radiology services, including an emergency radiology service, do not schedule dedicated clinic time, and therefore meeting with patients may not be a set priority in the daily workflow. Additionally, radiologists often do not have enough information from the…

Quality Considerations in Children

Although many of the quality and safety discussions throughout this volume are applicable to all aspects of radiology including the imaging of children, there are several topics that are especially critical or unique to pediatric patients including radiation reduction, sedation, and selection of the optimal study. Radiation Reduction In recent years, medical imaging has become a major source of ionizing radiation exposure, with the most significant…