The main symptom is severe sharp pain that starts suddenly, usually in your belly or one side of your back, and it may go away just as quickly. Some divide the excretory phase into the early excretory phase (contrast mainly confined to the kidney) and late excretory phase (contrast in the ureters). Figure 18-24 Normal magnetic resonance imaging appearance of the kidneys. Static-fluid (T2-weighted) MR urography and phase-contrast MR angiography are useful techniques that do not require intravenous contrast material. The cortex of a normal kidney is usually less echogenic than the adjacent normal liver. It is important to remember this order of vessels and ducts since this is the only thing that will make you able to orient the kidney and differentiate the left one from the right when they are outside of the cadaver. The posterior branch supplies the posterior part of the kidney, whereas the anterior branch arborizes into five segmental arteries, each supplying a different renal segment. Figure 18-6 Frontal image of the left kidney from an intravenous urogram demonstrating an aberrant renal papilla in the lower pole infundibulum. Kim Bengochea, Regis University, Denver. They are branches of the abdominal aorta and all together are called the extrahilar renal arteries. Aggressive tumors form, grow and spread very quickly. CT is occasionally used to evaluate patients with renal failure. The kidney is a very important organ in regards to body homeostasis. When multiple clefts in the renal cortex are present throughout the kidney, it is described as fetal lobulation. This can cause varicocele of the left testicle because gravity works against the column of the blood in the left testicular vein. Coronal computed tomographic image in the corticomedullary phase shows normal corticomedullary differentiation along the lobulated contour, consistent with fetal lobulation. The kidneys are a pair of bean-shaped organs located below the rib cage, one on each side of the spine. Bilateral echogenic kidneys with renal hypertrophy can be seen associated with human immunodeficiency virus disease (see Fig. All rights reserved. When echogenicity of the renal cortex equals that of the liver, renal function is abnormal in approximately 38% of cases. Table 18-1 provides a quick guide itemizing key imaging findings in the potential renal donor. When this happens, the stones can block the flow of urine out of your kidneys. Kidney cysts can occur with disorders that may impair kidney function. Urine from the calyces flows to the renal sinus via tributaries called infundibula. On ultrasound, the renal cortex is usually echogenic in this setting. Diabetes, hypertension, acute tubular necrosis, Increased echogenicity has high association with parenchymal disease, Acute tubular necrosis usually results in an increased RI, whereas prerenal causes usually do not have an increased RI; postrenal causes often increase the RI, but hydronephrosis should be present in those cases, If present, suspect neurogenic bladder or outlet obstruction, Often severe aortic disease or fibromuscular dysplasia. The region where the renal pelvis joins the ureter is called the, If the renal pelvis is entirely within the confines of the renal sinus, it is considered intrarenal. The urinary system comprises the upper urinary tracts (kidneys and ureters), the urinary bladder, and the urethra. The early excretory phase begins as early as 120 seconds after injection. Note that the left renal vein receives blood from the left suprarenal and left testicular veins. Ultrasound It can be seen as a triangular echogenic cortical defect, frequently seen in upper lobe parenchyma. The adrenal cortex directly influences renal function through the production of the hormone aldosterone to stimulate sodium reabsorption. The calyces, however, will have a normal appearance with an unobstructed extrarenal pelvis but will be dilated in cases of urinary obstruction. So the pyramids represent the functional tissue that creates urine, whereas the calyces are the beginning of the ureter and transport the urine to it. Figure 18-16 Coronal reformation from contrast-enhanced computed tomography performed for renal donation demonstrates a retroaortic left renal vein crossing the aorta well inferior to the level of the renal hila. Look for duplication, large extrarenal pelvis. This article will discuss the anatomy and major functions of the kidney. The kidneys are bilateral organs placed retroperitoneally in the upper left and right abdominal quadrants and are part of the urinary system. For that reason, we got you covered with this topic nicely and concisely. The glomerulus is actually a web of arterioles and capillaries, with a special filter which filters the blood that runs through the capillaries, the glomerular membrane. February 12, 2018 - 2:17pm This phenomenon is due to T2-shortening and susceptibility (T2*) effects caused by concentrated gadolinium, and can potentially obscure filling defects and urothelial lesions. Blood in the urine, or dark urine. Note that there is no contrast in the aorta. The bilateral small smooth kidney pattern describes most of what is often diagnosed on sonography as medical renal disease, although the authors prefer the term renal parenchymal disease. Table 18-5 Checklist Approach to Ultrasound for Renal Failure. chronic obstruction, or severe or repeated urinary infections. Differential diagnosis General imaging considerations include: renal cortical defect duplex kidney 18-16). When echogenicity of the renal cortex equals that of the liver, renal function is abnormal in approximately 38% of cases. The center of the minor concavity is marked as the hilum of the kidney where the renal artery enters the kidney, and the renal vein and ureter leave the kidney. The ureter and calyces were not dilated (not shown), helping to differentiate this anatomic variant from obstruction. Around 40% of kidney cancers are localized renal masses. Read more. Lets start with the right kidney anterior surface. Fetal lobulation is best differentiated from renal scars during the corticomedullary phase of enhancement on computed tomography (CT) or magnetic resonance imaging (MRI) because cortex can be followed into the indentation that occurs between calyces (Fig. Overview. People with unilateral agenesis often are unaware that they lack one kidney until an accidental discovery, since the one kidney that they have is able to functionally compensate for the other. Right-sided pain was related to crossed renal ectopia. Diagnostic ultrasound uses sound wave technology to look at parts of your body, including: Brain Heart and blood vessels Breast Abdominal Organs Eyes Thyroid Skin and muscles Types of Ultrasound. The kidneys are positioned retroperitoneally, meaning that they are not wrapped with the peritoneal layers the way most abdominal organs are, but rather are placed behind it. Calculation of the estimated renal volume is considered by some to be the most accurate assessment of renal size available with ultrasound, although renal length alone is more commonly reported. Since they are located deep retroperitoneally, the easiest way to examine them is from the patients back. The kidneys are highly vascular (contain a lot of blood vessels) and are divided into three main regions: the renal cortex (outer region which contains about 1.25 million renal tubules), renal medulla (middle region which acts as a collecting chamber), and renal pelvis (inner region which receives urine through the major calyces). Creatinine is a breakdown product of creatine, found within muscle. Some forms of congenital UPJ obstruction are now treated with transureteroscopic endopyelotomy in which an incision is made from within the ureter using a ureteroscope. Despite different methods of accumulation, each is sequestered by the renal cortex, providing an opportunity to quantify the volume of renal parenchymal tissue in each kidney. The renal fascia which besides the kidneys also encloses the suprarenal gland and its surrounding fat. Figure 18-27 T2-weighted maximum intensity projection image from a magnetic resonance urogram performed to evaluate urinary obstruction identified in a patient with an obstructing soft tissue mass in the pelvis on unenhanced computed tomography (CT). Differential diagnosis General imaging considerations include: renal cortical defect duplex kidney Most radiologists consider 10 to 12 cm to be an approximate reference range for renal length in adults, allowing for an additional 1 cm in either direction for patients at the extremes of height. The left kidney appeared unremarkable. The medulla consists of multiple pyramidal tissue masses, called the renal pyramids, which are triangle structures that contain a dense network of nephrons. The patient had right flank pain but had a solitary calcification in the left pelvis on plain radiograph (not shown). 18-4). Table 18-7 Causes of Unilateral Small Smooth Kidney, Only gold members can continue reading. In most cases, unenhanced CT is performed when the duration and cause of renal failure are unknown because exposure to iodinated contrast media could impair recovery of renal function. Figure 18-19 Sagittal ultrasound image of the right kidney demonstrates increased size and echogenicity of the kidney, findings typical of human immunodeficiency virus nephropathy. The stones can move into the ureter and literally get stuck there because the lumen of the ureter is much smaller compared to the calyces, which is very painful for the patient. Ultrasound can often identify the cause in cases of bilateral obstruction (, Pelvic mass (cervical, rectal, uterine, prostate cancer). 18-27). Ultrasound to get images of your kidneys. 18-18). Use of MR contrast agents in renal failure poses a lower risk than iodinated contrast material for exacerbating renal failure, but there is evidence that gadolinium-based MR contrast media pose some risk for systemic complications (nephrogenic systemic fibrosis) and should be used with caution in patients with severe or acute renal insufficiency. Figure 18-15 Relation between the right renal artery and the inferior vena cava (IVC). 18-4). These are chronic processes that lead to a loss of renal cortex gradually and uniformly. Arterial stenosis was confirmed by magnetic resonance angiography. Anterior components of circumaortic vein can be small. The left kidney (not shown) had a similar appearance. 18-3). Extraaortic origin of the renal arteries and accessory renal arteries are common. An acute change in renal cortical echogenicity is occasionally seen with pyelonehritis. So in the filtered fluid that goes to the renal tubule, we have both necessary and unnecessary substances. Due to the segmental vascular supply of the kidney it is often feasible to ligate the relative arteries and veins and remove the tumour with a safe zone of healthy surrounding parenchyma ( partial nephrectomy) without removing the entire kidney or compromising its total vascular supply by ischaemia. Unenhanced MRI can also be used to diagnose obstruction and identify the source (Fig. T2-weighted maximum intensity projection image from a magnetic resonance urogram performed to evaluate urinary obstruction identified in a patient with an obstructing soft tissue mass in the pelvis on unenhanced computed tomography (CT). Pancake kidney describes a more severe fusion anomaly with a single, flat kidney positioned low in the pelvis with an anterior collecting system drained by either one or two ureters. A second similar finely granular mass was present in the interpolar region, and it also contained . 18-7). Coronal maximum intensity projection image from a contrast-enhanced computed tomographic scan demonstrates a dilated and tortuous lumbar veins joining the left renal vein. Medullary cystic disease is encountered only rarely, and in addition to the echogenic atrophic cortex, the medullary pyramids are particularly hypoechoic. However, you may have symptoms related to the condition that's causing it. 18-6). Because an extrarenal pelvis is not confined by the renal parenchyma, there is a tendency for it to expand. There are 8-18 renal pyramids in each kidney, that on the coronal section look like triangles lined next to each other with their bases directed toward the cortex and apex to the hilum. (Courtesy of Karl T. Rew, MD) Introduction Synonyms Epidemiology The defect is the extension of sinus fat into the cortex, usually at the border of the upper pole and interpolar region of the kidney. Coronal reformation from contrast-enhanced computed tomography performed for renal donation demonstrates a retroaortic left renal vein crossing the aorta well inferior to the level of the renal hila. Duplication of the urinary tract is discussed in detail in Chapter 19. 18-25). In clinical practice, it is probably best to categorize the renal cortex as hypoechoic, isoechoic, or hyperechoic compared with normal liver, and then state a correlative risk for associated renal parenchymal disease (Table 18-2). Calcifications and renal calculi are notoriously poorly demonstrated with MRI. Computed Tomographic Appearance of the Kidneys, Utility of Different Phases of Renal Contrast Enhancement. Table 18-7 lists causes of unilateral smooth renal atrophy. In order to understand the functions of the kidney, we must first learn its anatomy. Note origin of inferior accessories near inferior poles on each side. The kidneys are innervated by the renal plexus. The nephrons within the cortex comprise some of the most highly perfused parenchymal tissue in the body. Note that there is no contrast in the aorta. 18-28). Poorly functioning kidneys with little residual parenchymal volume may be removed because preservation offers opportunities for future complications (infection, hypertension) without contributing significantly to renal function. In this region, the anterior and posterior. The anteromedial aspect of the interpolar region is interrupted by the renal hilum to make a C shape. Author: Urine that is concentrated in the renal papilla is subsequently excreted into a lumen lined with transitional epithelium. Parasympathetic innervation enhances the peristalsis while sympathetic innervation inhibits it. Figure 18-21 Axial images from contrast-enhanced computed tomography demonstrate transient enhancement of a small renal cell carcinoma. Unenhanced CT can identify hydronephrosis and hydroureter, urinary stones, and some masses. Enlargement of a congenitally unilateral kidney is typical and presumed to be compensatory. Pain that radiates to the lower abdomen and groin. Let's see what is nephron and how it is structured,so you can remember it for good. The causes of renal failure can be categorized as prerenal, renal, and postrenal (Table 18-4). The initiation is caused by the increase in volume that stretches the walls of the calyces. Size disparity greater than 1.5 cm between kidneys should raise suspicion that one kidney is abnormal. Size disparity greater than 1.5 cm between kidneys should raise suspicion that one kidney is abnormal. Many clinical laboratories now provide computer-generated calculations of estimated creatinine clearance or eGFR using patient data in the medical information system. This apical projection is called the renal papilla and it opens to the minor calyx. C, More severe hydronephrosis results in more pronounced shortening of the papilla. a bifid renal pelvis, ultimately drained by a common ureter. Each pyramid creates urine and terminates into a renal papilla. Perhaps of even greater importance, serum creatinine is not a sensitive test for minor insults to the kidney in otherwise healthy individuals. Some tumors can be slow to grow while some can be aggressive. 18-24). Size and Contour of Diffuse Renal Disease, The bilateral small smooth kidney pattern describes most of what is often diagnosed on sonography as medical renal disease, although the authors prefer the term, Global insult to one kidney may result in unilateral atrophy that is uniform and smooth. The main parts of your kidney anatomy include: Kidney capsule (renal capsule) The renal capsule consists of three layers of connective tissue or fat that cover your kidneys. Some forms of congenital UPJ obstruction are now treated with transureteroscopic endopyelotomy in which an incision is made from within the ureter using a ureteroscope. IVC, Inferior vena cava. Table 18-7 lists causes of unilateral smooth renal atrophy. The vascularity of some tumors may be most apparent during this phase (Fig. The axes of the renal moeities are abnormal with the inferior poles angled medially. Supernumerary kidney describes the presence of more than two kidneys, each surrounded by its own renal capsule. Each segmental branch of the renal artery divides into multiple interlobar arteries that course along the periphery of the medullary pyramids and causes small interlobular branches (Fig. Renal size and cortical thickness can be assessed in a manner similar to ultrasound. Also, in situations with notable blood losses, kidneys release a hormone called erythropoietin, which stimulates bone marrow to produce more blood cells. 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