Retrograde pyelography was first described by Friedrich Voelcker and Alexander Von Lichtenberg in 1906 using a silver colloid solution, collargol, as contrast. In 1925, William Braasch, a urologist, and Russell Carman, a radiologist, described findings of renal tumors in retrograde pyelography. The secondary signs of renal masses included elongation, shortening, obliteration or distortion of the calyces, renal pelvis, or ureteropelvic junction [2]. They described features that could narrow the differential between inflammatory and neoplastic processes, but often the final diagnosis relied on pathology after surgical resection. Retrograde pyelography was invasive with the risk of infection and perforation by instrumentation. There was additional risk of local toxicity from the heavy metal contrast agents available at the time.

Earl Osborne described the potential for excretory urography after intravenous injection of sodium iodide for the treatment of syphilis in 1923. Opacification of the renal parenchyma as well as the collecting system, ureter, and bladder was seen in some patients [3] (Fig. 13.2). This was forward progress on direct visualization of the renal parenchyma, but the contrast agents remained suboptimal and had multiple side effects limiting their use. Experimentation with multiple compounds to find a practical intravenous urographic contrast agent lead Moses Swick to discover Uroselectan in 1929 [1]. Uroselectan had fewer side effects than the previous iodine based contrast agents, was water soluble, and almost entirely excreted in the urine. Intravenous urography eliminated the need for invasive diagnostic instrumentation of the bladder and ureters. The method also provided information regarding renal function, since Uroselectan required functioning nephrons for excretion.

For the next several decades, renal excreted contrast agents were improved. During this period, intravenous excretory urography (also commonly referred to as intravenous pyelography, or IVP ) and retrograde pyelography were the mainstays of renal imaging, but serendipitous discovery that injection of these iodinated contrast agents directly into the aorta was generally tolerated opened up the evaluation of kidneys by angiography. In 1957, Arthur Evans reported the angiographic findings of renal cell carcinoma. He describes the procedure using up to an 18-gauge needle to directly puncture the aorta above the celiac axis and inject the same contrast agent used for intravenous urography at that time [4]. With careful technique, angiography was able to differentiate between avascular cysts and vascular masses. The pattern of vasculature seen in renal cell carcinoma was enlarged, disorganized vessels with areas of pooling, but the interpretation could be complicated by necrosis (Fig. 13.3). In his series of 236 cases, Evans reported an accuracy of 95% in detecting malignant renal masses [4]. With the development of the Seldinger technique in 1953, selective angiography became more widely accepted [5]. It was during this period that diagnostic imaging of renal disease moved from the realm of the urologist to the radiologist [1].

Even with the advances in these techniques, aspiration was frequently required to definitively diagnose a cyst versus a solid neoplasm. Cross-sectional imaging removed the dependence on the invasive cyst puncture technique. In 1968, a group from Albert Einstein Medical Center in Philadelphia described the use of amplitude modulation sonography to confidently differentiate between solid and cystic renal masses [6]. The advent of computed tomography (CT) by Godfrey Hounsfield in 1972 rapidly changed the field of uroradiology as CT became the imaging modality of choice for the detection and characterization of renal masses. There was less user variability and multiple post-contrast phases of renal enhancement could be acquired to more accurately characterize renal masses (Fig. 13.4). In 1986, Morton Bosniak published the well-known renal cyst classification that is still in use today using both CT and US [7] (Figs. 13.5 and 13.6). Now, the Bosniak cyst classification has been optimized for CT with the accumulation of data since that time [8].

Magnetic resonance imaging (MRI) took longer to gain prominence in the field of uroradiology. First developed in the late 1970’s, due to its expense and the length of time for an examination, it did not become readily available for imaging of renal masses until almost a decade later [9]. MRI demonstrated usefulness in the evaluation of renal vein and inferior vena cava involvement by renal cell carcinoma [10]. MRI is typically used as complementary to CT for renal cell carcinoma diagnosis but is preferred for establishing vascular involvement, and is also indicated if the patient has contraindications for iodinated contrast (Fig. 13.7).

The future of renal cell carcinoma imaging likely includes the addition of contrast enhanced ultrasound (CEUS) in its armamentarium (Fig. 13.8). In the spring of 2016, the United States Food and Drug Administration (FDA) approved an ultrasound contrast agent for the evaluation of liver masses. With the recent FDA approval, the United States will continue to evaluate the diagnosis and characterization of renal lesions using CEUS . The lack of ionizing radiation and the ability to monitor enhancement in real-time, make CEUS an attractive alternative to explore. This technique may also prove useful to guide percutaneous biopsy of renal masses, which is now being performed more commonly.