interpolar region of kidney anatomy

Axial image from unenhanced computed tomography of the kidneys performed 2 days after an angiographic procedure demonstrates stasis of contrast in the renal cortex, resulting in a persistent corticomedullary phase of enhancement. In adults, the normal kidney is 10-14 cm long in males and 9-13 cm long in females, 3-5 cm wide, 3 cm in antero-posterior thickness and weighs 150-260 g. The left kidney is usually slightly larger than the right. Always include unenhanced computed tomographic images to look for renal stones. Although each kidney is about the size of a fist, the approximately one million nephrons per kidney require nearly 20% of the total cardiac output to perform this multitude of functions. Usually, there are two to three major calyces in the kidney (superior, middle, and inferior), which again unite to form the renal pelvis from which the ureter emerges and leaves the kidney through the hilum. 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. When abnormal echogenicity is detected, it is important to note whether it is unilateral or bilateral. B, Axial CT image from a different patient demonstrates the more common location of the right renal artery posterior to the IVC. Besides blood volume and pressure regulation, kidneys also participate in the production of calcitriol (the active form of vitamin D). The left kidney (not shown) had a similar appearance. When echogenicity of the renal cortex equals that of the liver, renal function is abnormal in approximately 38% of cases. Ultrasound to get images of your kidneys. Learning a quickmnemonic'VAD' can help you remember these structures (renal Vein, renal Artery, Duct a.k.a ureter). This phenomenon is due to T2-shortening and susceptibility (T2*) effects caused by concentrated gadolinium, and can potentially obscure filling defects and urothelial lesions. The ureters are the tubes that carry urine from the renal pelvis to the bladder. Thus, any upward trend in the serum creatinine value should be viewed with concern when considering the administration of potentially nephrotoxic or renally excreted intravenous contrast media. Localized means that the tumor has not spread out from where it first started. Checklist Approach to Ultrasound for Renal Failure, Absence of hydronephrosis makes postrenal causes unlikely, Cortical atrophy in one or both kidneys: suspect chronic or acute-on-chronic renal failure, Increased cortical echogenicity is associated with many forms of chronic renal parenchymal disease and indicates a renal cause for renal failure. The patient had acute renal failure; therefore, contrast-enhanced CT was not performed. Size disparity greater than 1.5 cm between kidneys should raise suspicion that one kidney is abnormal. Ultrasound It can be seen as a triangular echogenic cortical defect, frequently seen in upper lobe parenchyma. 18-25). The patient had acute renal failure; therefore, contrast-enhanced CT was not performed. In this region, the anterior and posterior hilar lip is identified (Fig. MR angiography can be useful for the diagnosis of renal vascular abnormalities. The renal fascia which besides the kidneys also encloses the suprarenal gland and its surrounding fat. It is notable that the kidney has a very rich blood supply. Illustration demonstrating basic intrarenal arterial anatomy. Obstruction can cause renal failure if it is bilateral (Box 18-3) or if there is preexisting disease in the unobstructed kidney. Although this dilatation of the renal pelvis may occasionally mimic hydronephrosis, delicate and sharply defined calyces and thin infundibula can be used to differentiate an extrarenal pelvis from obstruction. Chronic obstruction, however, results in damage to the papilla, evident in the clubbed calyx of papillary necrosis (Fig. Axial image of the left kidney from a contrast-enhanced computed tomographic scan demonstrates an extrarenal pelvis. Table 18-3 Utility of Different Phases of Renal Contrast Enhancement. Eliminating toxic metabolites through urine, regulation of blood homeostasis and blood pressure, production of some hormones, Positioned retroperitoneally, consists of the cortex and medulla, empties urine into the ureter (which carries urine to the urinary bladder), Renal artery (branch of the abdominal aorta), Renal vein (drains to the inferior vena cava), Third kidney, horseshoe kidney, kidney agenesis, kidney stones, acute kidney failure, Regulates the amount of fluid in the body by increasing or decreasing the urine production, Maintain the pH of blood at 7.4 by decreasing or increasing the excretion of hydrogen ions, Medial part of the lower half of superior pole, Lateral part of the lower half of superior pole, Lateral part of inferior half of anterior surface, Medial part of inferior half of anterior surface, The perinephric fat (perirenal fat capsule). 18-15). Figure 18-26 Ultrasound performed for acute renal failure demonstrates bilateral hydronephrosis caused by a bladder tumor. Chronic obstruction, however, results in damage to the papilla, evident in the clubbed calyx of papillary necrosis (Fig. Each nephron contains a renal corpuscle, which is the initial component that filters the blood, and a renal tubule that processes and carries the filtered fluid to the system of calyces. Figure 18-12 Axial sections of the right kidney from contrast-enhanced computed tomography demonstrate a bar of renal parenchyma separating renal hila in the superior and inferior poles, consistent with duplication. 18-26). One of the most commonly used (and least complicated) equations is shown in Box 18-1. Axial images from contrast-enhanced computed tomography demonstrate transient enhancement of a small renal cell carcinoma. Medullary cystic disease is encountered only rarely, and in addition to the echogenic atrophic cortex, the medullary pyramids are particularly hypoechoic. Figure 18-25 Sagittal ultrasound image of the left kidney demonstrates a unilateral small, smooth, echogenic kidney in a patient with renal artery stenosis. Unlike the excretory phase of enhanced CT, signal intensity within the renal collecting systems is reduced on T1- and T2-weighted MR images once excreted gadolinium-based contrast media becomes sufficiently concentrated. 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. Frequent urination (having to go the bathroom often). Jana Vaskovi MD The kidneys are bilateral organs placed retroperitoneally in the upper left and right abdominal quadrants and are part of the urinary system. Anatomy Where is the renal cortex? chronic obstruction, or severe or repeated urinary infections. In general, the amount of blood in the body is 5 liters. Figure 18-4 Illustration demonstrating the relation between the renal papilla and calyx. The most common cause is renal artery stenosis (see, Delayed but increasingly dense nephrogram, Delayed but hyperconcentrated contrast excretion, Imaging Evaluation of Acute Abdominal Pain, A Multidimensional Approach to Abdominal Imaging. Curated learning paths created by our anatomy experts, 1000s of high quality anatomy illustrations and articles. Unlike the excretory phase of enhanced CT, signal intensity within the renal collecting systems is reduced on T1- and T2-weighted MR images once excreted gadolinium-based contrast media becomes sufficiently concentrated. Figure 18-24 Normal magnetic resonance imaging appearance of the kidneys. The visible contrast seen in the excretory phase has been concentrated many-fold. Figure 18-6 Frontal image of the left kidney from an intravenous urogram demonstrating an aberrant renal papilla in the lower pole infundibulum. Extraaortic origin of the renal arteries and accessory renal arteries are common. Copyright On axial sections, the polar regions of the kidney typically form a closed circle or donut shape, with the hole formed by renal sinus fat. However, sometimes ureteroscopy is required to confirm the diagnosis in patients with hematuria. The right kidney has a normal appearance (not shown). Luckily, the kidneys also feel this increase of pressure, and in cases when this happens, they increase the filtration rate of blood and production of urine, which subsequently leads to the increase fluid excretion and decrease of blood pressure. 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. The pyramids contain the functional units of the kidney, the nephrons, which filter blood in order to produce urine which then is transported through a system of the structures called calyces which then transport the urine to the ureter. On ultrasound, the renal cortex is usually echogenic in this setting. The parenchyma of the kidney consists of the outer renal cortex, and inner renal medulla. Some centers use diuretics or fluid bolus, or both, during CT urography to dilute the excreted contrast to improve assessment of the urothelium. Illustration demonstrating the relation between the renal papilla and calyx. The uniform high attenuation of the nephrographic phase provides an optimal background for detecting small, low-attenuation lesions in the renal parenchyma (Fig. The phases of nephrogram development and contrast excretion parallel those seen on contrast-enhanced CT with one notable exception (Fig. Differential diagnosis General imaging considerations include: renal cortical defect duplex kidney Since the abdominal organs are not paired, the left kidney is not related to the same organs as the right kidney. This plexus provides input from: The sensory nerves from the kidney travel to the spinal cord at the levels T10-T11, which is why the pain in the flank region always rises suspicions that something is wrong with the corresponding kidney. 18-24). Estimated creatinine clearance may be calculated using serum creatinine with adjustments made for sex, age, and body weight. Increasing pressure within the lumen initially distends the fornices (acutely angled portions of the calyx along the sides of the papillae), whereas the central portion of the papillary impression is preserved. Axial image of the left kidney obtained in the excretory phase of a computed tomographic urogram demonstrates the effects of window settings on visualizing structures near excreted contrast. Because the interlobular arteries form an arch overlying the pyramid, they are called the arcuate arteries. This phenomenon is due to T2-shortening and susceptibility (T2*) effects caused by concentrated gadolinium, and can potentially obscure filling defects and urothelial lesions. Urine that is concentrated in the renal papilla is subsequently excreted into a lumen lined with transitional epithelium. 18-3). Overview. Global insult to one kidney may result in unilateral atrophy that is uniform and smooth. The calyces, however, will have a normal appearance with an unobstructed extrarenal pelvis but will be dilated in cases of urinary obstruction. Figure 18-23 Axial image of the left kidney obtained in the excretory phase of a computed tomographic urogram demonstrates the effects of window settings on visualizing structures near excreted contrast. Figure 18-2 Annotated axial image of the right kidney from a contrast-enhanced computed tomographic scan demonstrates hilar anatomy of the kidney. They extend from lumbar vertebra T12-L3. Technetium 99m-mercaptoacetyltriglycin (MAG3) is excreted by the kidneys (mainly through secretion by proximal tubules) and provides evaluation of renal function, particularly in cases of suspected obstruction. 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 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). Renal function is better evaluated by measured creatinine clearance, which takes into account not only the amount of creatinine in the blood but also the amount of creatinine within a specified volume of urine over a given period. The isthmus connecting the kidneys is variable, ranging from normal renal cortex to a thin fibrous band. This layer sits posteriorly and posterolaterally to each kidney and separates it from the muscles of the abdominal wall. Bilateral echogenic kidneys with renal hypertrophy can be seen associated with human immunodeficiency virus disease (see. Urine that is concentrated in the renal papilla is subsequently excreted into a lumen lined with transitional epithelium. Each end of the kidney is commonly called a. Annotated three-dimensional volume rendering of the left kidney acquired using a combined nephrographic phase and excretory phase during computed tomographic urography demonstrates regional anatomy of the kidney. Note diameter of arteries because small accessory arteries may be sacrificed in many cases. Grounded on academic literature and research, validated by experts, and trusted by more than 2 million users. So in the filtered fluid that goes to the renal tubule, we have both necessary and unnecessary substances. Renal size can be measured in several ways. It is also permeable for the products of the metabolism, such are creatinine and drug metabolites. Table 18-5 summarizes a checklist approach to the ultrasound examination. 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. Both renal arteries, left and right, arise just below the superior mesenteric artery, with the left renal artery positioned slightly superiorly to the right one. Pearl: Any upward trend in serum creatinine value should be viewed with concern because it implies renal reserve function has already been affected. Sagittal ultrasound image of the right kidney demonstrates increased size and echogenicity of the kidney, findings typical of human immunodeficiency virus nephropathy. Pitfall: An extrarenal pelvis may be mistaken for hydronephrosis. Other symptoms can include abnormal urine color, blood in your urine, fever, chills, nausea, and vomiting. Urine from the calyces flows to the renal sinus via tributaries called infundibula. Made. 18-1). 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). The upper pelvis is the most common ectopic location for the kidney; most cases are also associated with abnormalities of rotation. Their shape resembles a bean, where we can describe the superior and inferior poles, as well as the major convexity pointed laterally, and the minor concavity pointed medially. The fused kidneys can have a variety of orientations, including side by side, in-line, or perpendicular. Sagittal ultrasound image of the left kidney demonstrates a unilateral small, smooth, echogenic kidney in a patient with renal artery stenosis. Arterial stenosis was confirmed by magnetic resonance angiography. Each time a professor says 'nephron', a student gets a headache. Kim Bengochea, Regis University, Denver. Table 18-2 Association between Renal Cortical Echogenicity and Renal Parenchymal Disease. During the 6th to 9th weeks of life, the kidneys begin to ascend from their position in the pelvis to the level of T12-L1, inferior to the adrenal glands. RENAL ANATOMY Renal Parenchyma The kidneys can be divided into three main regions from cranial to caudal. The muscular relations of the inferior half are easy to remember by dividing the kidney surface into three vertical stripes, where the medial stripe represents the impression of the psoas major muscle, the central stripe the quadratus lumborum, and the lateral stripe the transversus abdominis muscle. Internal Anatomy. Chronic glomerulonephritis usually causes bilateral increased renal echogenicity with smooth atrophy, whereas renal artery stenosis usually causes a similar but unilateral appearance (Fig. 18-14). 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