Five years is a long time in radiology, and the pace of change in imaging has even quickened since the prior edition of this text. The increasing availability and technical capability of cross-sectional modalities such computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound (US) now dominate imaging of the urinary system with multidetector (spiral) CT having the greatest impact. In our department, CT is called the “temple of truth” for good reason. These cross-sectional modalities have essentially eliminated the intravenous pyelogram (IVP), which after 70 years of being the backbone of urinary tract imaging, has had its epitaph written, and has little if any role in modern-day urinary imaging. The result of these progressive advances in imaging continues to be improved, earlier, and more accurate diagnosis of genitourinary tract disease.
This chapter introduces the basic concepts in imaging of the urinary tract. First, the imaging modalities currently in clinical practice and principles of their interpretation are discussed, especially regarding normal anatomy and its variants. The importance of choosing the most appropriate study for a given clinical scenario cannot be overemphasized, and the next section of the chapter reviews technique selection. A series of clinical exercises and case examples follow, demonstrating important imaging concepts and diseases of the urinary tract. Finally, suggested readings is provided at the end of the chapter.
This section introduces the common radiologic techniques used in evaluation of the urinary tract, with emphasis on an overview of each technique as it applies to the urinary tract. A discussion of normal anatomy and some important fundamental concepts of interpretation are included. A basic knowledge of the gross anatomy is assumed, with emphasis placed on the radiographic anatomic correlations.
Conventional radiographs, or “plain films,” are an inexpensive, quick overview of the abdomen and can occasionally provide useful diagnostic information for selected urinary tract indications. A radiograph of the abdomen when used to evaluate the urinary tract is often referred to as a KUB (kidney, ureter, and bladder). “Gas, mass, bones, stones” can be used as a reminder of main areas to examine on the abdominal radiograph. On the normal abdominal radiograph, the renal outline may be visible adjacent to the upper lumbar spine and should be bilaterally symmetric and measure between 3 and 4 lumbar vertebrae in length. The ureters are not discernable, although knowledge of their normal course, between the tips of lumbar transverse process tips and pedicles, along the mid sacral ala, and finally gently coursing laterally below the sacrum to enter the bladder, allows for potential stone identification. The distended bladder may also be visible, if outlined by fat, on the KUB. The most common genitourinary findings seen on abdominal radiography will be in the form of urinary tract calcifications (Figure 9-1). Unfortunately, the KUB suffers from poor sensitivity and specificity regarding urinary tract calcifications. In the past, it was reported that 80% of ...