Radiology Of The Urinary System

Urinary tract Radiological department of the first affiliated hospital, ZZU

Zhang YongGao

Methods of examination （ 1） Plain film: Intravenous urography or intravenous pyelography(IVUorIVP) Retrograde pyelography

Methods of examination （ 2） Cystography Urethrography Angiography CT ,MRI and Ultrasonography

Intravenous urography or intravenous pyelography (IVU or IVP) Dose Type After rapid intravenous administration, radiographs of the kidneys at 1,5,7,15,25 minutes are obtained.

IVU will demonstrate most lesions affecting the normal anatomy of the pyelocalycal system. It can also give some information of excretory function of the kidney.

Normal X-ray Anatomy Kidney Ureters Bladder Urethra

Kidney Renal outline Size of kidneys Position of the kidneys

Basic X-ray findings in diseases of urinary tract Change in density: The normal kidney is homogeneous in density. Increase of density might be due to calcification as seen in renal stone, TB of kidney and nephrocalcinosis.

Renal stone

Change in size, contour and position of the kidney Decrease in size of one kidney might be due to hypoplasia, pyelonephritis and renal ischemia. Increase in size of one kidney might be due to unilateral hydronephrosis, tumor growth or renal cyst.

Change of position of the kidney might be due to pressure of adjacent tumor growth or ectopic kidney

Destruction, filling defect and displacement TB Tumor Pyelonephritis

Varieties of calculus Calcium oxalate calculi Phosphatic calculi Urate calculi Calcium carbonate calculi Uric acid calculi

Radiologic features When you are going to make a diagnosis of renal stone, the following questions should be considered:

If a shadow is present, is it intra or extrarenal? If it is intrarenal, is it due to a calculus? If no shadow is evident, is an invisible calculus present? THE EVIDENCE IS------

Intrinsic characters There are certain characteristics which if present indicate a shadow to be cast by a renal calculus. Some of these, such as coral or staghorn shape, are pathognomonic;

Site of the opacity--- within the renal shadow The shape of the opacity--- mulberry ,round The texture of the opacity--- homogeneous , laminated, stippling

The second diagnostic question How do you work out that an intrarenal opacity is due to calculus? If the plain film fails to give any idea, either intravenous or retrograde urography will settle the problem.

The third diagnostic question

This unusual cases where a transparent stone causes a negative shadow. Even then it may be impossible to differentiate it from a neoplastic filling defect. However, invisible stone causing obstruction of ureter may show hold-up or hold-down of the contrast medium. This is a reliable sign.

Ureteric calculus In the main, ureteric stone are formed in the kidney. Therefore the varieties found are similar to those found in the kidney, with the limitation in size imposed by the lumen or ureter.

Intrinsic character of ureteric calculi Ureteric calculi, if recently descended from the kidney, may be round, oval , or angular, and the surface may be smooth. Lamination is occasionally visible.

If the calculus has been impacted for some time in the ureter, it tends to become more oval or considerably elongated in shape. The long axis of the stone is always along that of the ureter.

Coralliform

Bladder stone Etiology: the formation of bladder stone may be primary or secondary. True primary bladder stone may either arise in aseptic or infected urine, by deposition of salts on a nucleus, which may be renal calculus, blood clot or foreign body. Infection an stagnation of the urine are important causative factors.

Secondary calculi are merely calculi which have passed down from the kidney.

Tuberculosis of urinary tract Renal tuberculosis more commonly arises from the lungs. Tuberculous ureteritis and cystitis are almost always secondary to renal TB.

The initial focus of TB in the kidney is in the region of the corticomedullary junction; Several foci in the kidney sometimes can be seen.

The initial lesion may be contain and go on to heal, with no evidence of renal TB. On the other hand, an initial TB may enlarge and rupture into a nephron, producing TB bacilluria without a radiographic lesion; or the tubercle may enlarge, with destruction of parenchyma and formation of a caseous mass(a tuberculoma), with displacement of the calyces but not communication with the pelvicalyceal system.

The enlarging initial tubercles may also form a tuberculous abscess that ruptures into a calyx, with destruction of the calyx and formation of an open draining, active tuberculous cavity. Parenchymal calcification occurs in longstanding renal TB, although only in about 20 percent of all patients.

Radiological feature Plain film pyelography

Plain film Lobular opacities, sometimes described as cumulus clouds, are found in caseo-cavenous tuberculosis. They may replace the whole kidney and ureter, this condition is then known as tuberculous autonephrectomy.

Other form of calcification found in tuberculosis of kidney are multiple small deposit which may be streaky and faint or punctate and well defined. They are usually limited to one pole of the kidney.

Ulcero-cavernous and pyenephrotic types. This will cause erosion and mouth-eaten appearance of one or more calyces. In the early stage of the disease it may show no change at all.

Cortical abscess– if the cavity is empty or partially empty the contrast medium may collect within and produce a rounded shadow lying in the cortical zone. The wall is slightly irregular. It may communicate with calyx.

Non-functioning kidney.

Non-function of one kidney might be due to TB or tumor growth.

Involvement of ureter may show rigidity of ureter and irregular outline.

With the development of tuberculous cystitis, the bladder may contract and become very small with irregular margins due to ulceration and trabeculation.

The left kidney TB

Cyst and neoplasm of the urinary tract The cysts of the kidney may be classified as: Simple cyst. Polycystic disease hydatic cyst Calyceal cyst

Cyst and neoplasm of the urinary tract The cysts of the kidney may be classified as: Simple cyst. Polycystic disease hydatic cyst Calyceal cyst

Renal neoplasm may be classified as: Arising in renal parenchyma. Arising in renal pelvis. Arising in adrenals. Arising in perirenal tissue. Arising in prerenal tissue.

Radiological features Plain film: Deformity of renal outline Enlargement of the renal outline Displacement of adjacent viscera. calcification.

IVU signs of tumor growth may be enumerated as follows Obliteration, partial or complete, of calyces and pelvis. Elongation of calyces, with compression or dilatation (so called “spider leg” deformity) Displacement of calyces. Encroachment on the renal pelvis. Displacement of the renal pelvis and upper port of the ureter. Non-functioning kidney.

Neoplasm of the renal pelvis: Comprising papilloma and papillocarcinoma are found in 15% of renal neoplasm

Filling defect in pyelography. May induce hydronephrosis depending upon the amount of obstruction at the pelvis-ureteric junction

When, in carcinoma of the renal pelvis, the obstructive hydronephrosis becomes very marked, it may be impossible to show the tumor either by the intravenous or retrograde pyelography, because in the former case the contrast medium is not concentrated adequately to demonstrate and in the latter the contrast medium can not be injected into the pelvis.

CT of kidney Technique: Patients are routinely given oral contrast agent 30 to 60 min prior to the examination in order to opacify all bowel segments. The examination begins with the identification of the renal margin on a preliminary digital scout radiography of the abdomen.

Scanning with slice thickness of 8-10mm in an adjacent slice sequence. Every CT examination of the kidney should include contrast-enhanced images

Disease of the kidney Calculus of urinary tract Solitary benign renal cysts Renal cell carcinoma

Calculus of urinary tract CT is a exquisite tool for the detection of urinary calculus.

Urinary calculi are identified as high density objects with the calcium-containing showing the highest CT numbers (over 100HU). In order to accurately exclude calculi, the area of interesting should be carefully scanned with helical CT or overlapping sections before the administration of contrast material that might easily obscure these high density objects.

Disease of the kidney Calculus of urinary tract Solitary benign renal cysts Renal cell carcinoma

Solitary benign renal cysts Benign renal cysts fulfill the following criteria: Smooth border Thin walls that are not recognized. Density of the cystic contents near that of water with attenuation coefficient no greater than 15HU Absence of contrast enhancement

Disease of the kidney Calculus of urinary tract Solitary benign renal cysts Renal cell carcinoma

CT is a superior tool for diagnosing the presence of solid masses, of which renal cell carcinoma is not only the most common but is also the one of most clinical concern.

Typically, carcinoma presents as a solid mass with irregular infiltrating margins and with attenuation coefficients similar of less than unenhanced renal parenchyma (30 to 60 HU). A consistent feature of these tumors however, is the presence of necrotic or hemorrhagic areas within the tumor, which cause considerable inhomogeneous density. Areas of necrosis and hemorrhage produce lower CT values (15 to 45 HU) than normal renal parenchyma, although fresh hemorrhage may have higher CT values (60 to 79 HU)

Calcification may also be present within the mass.

Bladder carcinoma Bladder carcinoma is the most frequent malignancy of the urinary tract. Most patients range in age from 50 to 70 years. Gross hematuria and bladder irritability, with urinary frequency and dysuria, are the most common signs and symptoms.

The tumor metastasizes either by a lymphatic route to regional lymph nodes or by a hematogenous route to liver, lung, and bone.