This significantly affects the testicle, since an obstruction of drainage causes an obstruction of fresh arterial blood inflow, which can result in the infarction of testicular tissue. Note diameter of arteries because small accessory arteries may be sacrificed in many cases. The anteromedial, aspect of the interpolar region is interrupted by the renal hilum to make a C shape. When the renal cortex is more echogenic than the adjacent liver, there is a high correlation with renal disease, although sensitivity is relatively low, according to Platt and colleagues (Fig. When simple kidney cysts do cause symptoms, they might include: Pain in the side between the ribs and hip, stomach or back. Static-fluid (T2-weighted) MR urography and phase-contrast MR angiography are useful techniques that do not require intravenous contrast material. Weve mentioned that the most important functions of the kidney are the regulation of the blood homeostasis and blood pressure, so acute kidney failure can lead to a quick fall of blood pressure which presents as a state of shock. Table 18-7 lists causes of unilateral smooth renal atrophy. This can cause varicocele of the left testicle because gravity works against the column of the blood in the left testicular vein. The adrenal cortex directly influences renal function through the production of the hormone aldosterone to stimulate sodium reabsorption. The anterior surface faces towards the anterior abdominal wall, whereas the posterior surface is facing the posterior abdominal wall. Coronal computed tomographic image in the corticomedullary phase shows normal corticomedullary differentiation along the lobulated contour, consistent with fetal lobulation. Urine that is concentrated in the renal papilla is subsequently excreted into a lumen lined with transitional epithelium. Figure 18-6 Frontal image of the left kidney from an intravenous urogram demonstrating an aberrant renal papilla in the lower pole infundibulum. The causes of renal failure can be categorized as prerenal, renal, and postrenal (Table 18-4). February 12, 2018 - 2:17pm 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. This phenomenon is due to T2-shortening and susceptibility (T2*) effects caused by concentrated gadolinium, and can potentially obscure filling defects and urothelial lesions. 18-18). If the renal pelvis extends out of the renal sinus, it is considered to be an. When. Axial maximum intensity projection image from the arterial phase of a contrast-enhanced computed tomographic scan from a prospective renal donor demonstrates early prehilar branching of the left renal artery. As the lobules of metanephric blastema coalesce to form each kidney, they do not always result in a smooth, uniform band of cortex. The segmental arteries then branch into the interlobar arteries, which further branch into the arcuate arteries. Table 18-5 Checklist Approach to Ultrasound for Renal Failure. The corticomedullary phase is prolonged in the presence of ureteral or venous obstruction and can persist for days in cases of acute tubular necrosis (ATN; Fig. A, Enhancement of the mass is conspicuous in the corticomedullary phase. Figure 18-26 Ultrasound performed for acute renal failure demonstrates bilateral hydronephrosis caused by a bladder tumor. 18-12). In some cases, two separate kidneys drain into a bifid renal pelvis, ultimately drained by a common ureter. Several calyces drain into each infundibulum, an elongated transition from the polygonal calyces to the saclike renal pelvis. chronic obstruction, or severe or repeated urinary infections. 18-1). 18-27). The ureter and calyces were not dilated (not shown), helping to differentiate this anatomic variant from obstruction. However, sometimes ureteroscopy is required to confirm the diagnosis in patients with hematuria. 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. Crossed ectopia on intravenous pyelogram. Renal size can be measured in several ways. The anterior surface of the left kidney, has the following anatomical relations: The posterior surfaces of both kidneys are related to certain neurovascular structures and muscles: You can easily remember these with the mnemonic: 1-2-3-4 All Boys Need Muscle. Retrograde urogram shows a calculus in the left ureter. If, however, a vessel crosses the UPJ at the level of obstruction, a blind incision made from the inside of the ureteral lumen can result in severe hemorrhage. The renal cortex is part of your kidney, which itself is part of the urinary tract. Many clinical laboratories now provide computer-generated calculations of estimated creatinine clearance or eGFR using patient data in the medical information system. The genital system consists of the testes, epididymides, deferent ducts, seminal vesicles, ejaculatory ducts, the prostate, and the penis in males; and the ovaries, uterine tubes, uterus, and vagina in females. Copyright The kidneys are located between the transverse processes of T12-L3 vertebrae, with the left kidney typically positioned slightly more superiorly than the right. In most kidneys, the renal hilum faces more anteromedial in the upper half of the kidney and more directly medial in the lower half. Size disparity greater than 1.5 cm between kidneys should raise suspicion that one kidney is abnormal. 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. Author: On the other hand, kidneys do have relations with peritoneum, or precisely with the specific organs that are covered with peritoneum which are placed directly adjacent to the kidneys. The small portion of the lumen surrounding the papilla is called the calyx. Medullary cystic disease is encountered only rarely, and in addition to the echogenic atrophic cortex, the medullary pyramids are particularly hypoechoic. Imaging must provide detailed images of the renal parenchyma and a survey of arterial, venous, and ureteral anatomy. 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. 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. Always include unenhanced computed tomographic images to look for renal stones. These surfaces are separated by the edges of the kidney, which are the major convexity laterally, and minor concavity medially. The vascularity of some tumors may be most apparent during this phase (Fig. 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 initiation is caused by the increase in volume that stretches the walls of the calyces. 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. 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. The cortex of a normal kidney is usually less echogenic than the adjacent normal liver. 18-4). Internal Anatomy. Table 18-3 Utility of Different Phases of Renal Contrast Enhancement. The interpolar region is the middle of the kidney. Perhaps of even greater importance, serum creatinine is not a sensitive test for minor insults to the kidney in otherwise healthy individuals. In this case, the right kidney had more favorable anatomy for laparoscopic donor nephrectomy. 18-7). 18-5). A. Junctional cortical line seen on a long-axis ultrasound image of the right kidney. These kidney functions can sure seem overwhelming, especially if you have to memorise them! 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. However, T1-weighted images provide good corticomedullary differentiation. 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. The most common indication for cortical scintigraphy is to evaluate kidneys that have been injured by vesicoureteral reflux, chronic obstruction, or severe or repeated urinary infections. more lateral and anterior than the superior poles. Figure 18-4 Illustration demonstrating the relation between the renal papilla and calyx. Anatomical Position of the Kidneys Kidney Structure At that point, you may experience these symptoms: Severe, sharp pain in the side and back, below the ribs. Simple kidney cysts aren't cancer and rarely cause problems. Illustration demonstrating basic intrarenal arterial anatomy. The nephrons of the kidney are responsible for maintaining balance between fluids and electrolytes, regulating levels of amino acids, overall acid-base balance, as well as removing toxins from the blood. The left testicular vein must ascend higher and it drains to the left renal vein at a right angle, unlike the right testicular vein which joins the inferior vena cava directly. 18-14). 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. 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. The apex of the pyramid projects medially toward the renal sinus. The region where the renal pelvis joins the ureter is called the ureteropelvic junction (UPJ). The kidney is a very important organ in regards to body homeostasis. Kidney stones are most often treated by ultrasound shock therapy, during which high-frequency radio waves break the stone into smaller pieces that can be passed naturally into the urine. Differential diagnosis General imaging considerations include: renal cortical defect duplex kidney Some tumors can be slow to grow while some can be aggressive. Figure 18-7 Axial image of the left kidney from a contrast-enhanced computed tomographic scan demonstrates an extrarenal pelvis. The main function of the kidney is to eliminate excess bodily fluid, salts and byproducts of metabolism this makes kidneys key in the regulation of acid-base balance, blood pressure, and many other homeostatic parameters. Some of them are congenital, such as a third kidney, which is usually atrophic. Ultrasound permits real-time optimization of imaging relative to the axis of each kidney. Calcifications and renal calculi are notoriously poorly demonstrated with MRI. For most people, obstruction of a single ureter does not induce renal failure. When echogenicity of the renal cortex equals that of the liver, renal function is abnormal in approximately 38% of cases. The presence of significant renal parenchyma may justify surgical repair to maximize the functional contribution of that kidney. The solid renal parenchyma consists of the peripheral renal cortex and more central renal medulla. Learning a quickmnemonic'VAD' can help you remember these structures (renal Vein, renal Artery, Duct a.k.a ureter). On the other hand, babies with bilateral agenesis cannot survive without an immediate kidney transplant. Although less accurate than measured creatinine clearance, such methods provide an estimated creatinine clearance that is a better predictor of renal function than the serum creatinine alone. In this way, the consistency of blood is preserved and no important substances are lost. 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). Figure 18-11 Three-dimensional volume rendering from contrast-enhanced multidetector computed tomography examination of the kidneys demonstrates typical orientation of a horseshoe kidney. Cells in our body constantly produce hydrogen ions. The renal cortex and medulla both have high signal intensity on T2-weighted images resulting in poor corticomedullary differentiation. Angiomyolipoma or AML for short, is a benign tumor that arises in the kidney. Creatinine is a breakdown product of creatine, found within muscle. This is called the nutcracker phenomenon. Because the interlobular arteries form an arch overlying the pyramid, they are called the. Normal magnetic resonance imaging appearance of the kidneys. The superior half of each kidney is covered by the diaphragm, which is why the kidneys move up and down during respiration. If a kidney stone becomes lodged in the ureters, it may block the flow of urine and cause the kidney to swell and the ureter to spasm, which can be very painful. The presence or absence of intravenous contrast media, as well as the phase of contrast enhancement, are key factors that determine the appearance of the renal parenchyma on CT (Table 18-3). 18-4 ) function is abnormal shows normal corticomedullary differentiation the interpolar region is the middle of the left kidney an. In some cases, two separate kidneys drain into a lumen lined with transitional epithelium a single ureter not. 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