Lectures of genitourinary systems Fifth year Collage of medicine Dr . Nasrin Alatrushi

Urinary system

Imaging Techniques

Imaging Technique

1- ultrasound.2- intravenous urography ( IVU ).3- computed tomography ( CT ).4- radionuclide examination.5- magnetic resonance imaging ( MRI ).6- arteriography.7- studies need catheterization .8- direct puncture .

Urinary tract

Us Us is the first line investigation in most patients , it is non invasive, easy to perform , need no preparation & not costly.The main uses of US are 1- investigation patients with symptoms thought to be arise from urinary tract .2- demonstrate the size of the kidneys and exclude hydronephrosis in patients with renal failure .3-diagnos hydronephrosis , renal tumours, abscesses and cysts including polycystic diseases .4- assess and follow up renal size and scaring in children with repeated urinary tract infection 5 – assess the bladder and the prostate

Urinary tract Normal renal us

At US the kidneys should be smooth in out line . The parenchyma surrounded a central echodense region known as echo complex ( also called the renal sinus ), the renal sinus consisting of renal pelvicaliceal system, together with surrounding fat and blood vessels .The renal cortex is homogenous low echogenic , it is less reflective than the adjacent liver or spleen and the renal pyramids seen as triangular hypoechoic areas adjacent to the renal sinus . During the first two months of life cortical echoes are relatively more prominent and the renal pyramids are disproportionately large and hypoechoic .The normal adult kidney length is about 9 – 12 cm . Renal length varies with age being maximum in young adult . There may be a difference between the two kidneys , normally less than 1,5 cm but the kidney with bifid collecting system usually one to two cm larger than the normal kidney .Normal ureter are not usually visualized due to over lying gas bowel .The bladder should be examined in the distended state and the wall should be smooth and sharply defined . The bladder should be assessed following micturation to assess post voiding volume of urine , .

Urinary tract

• There are some conditions causing small kidneys .

• These conditions are • Unilateral may be bilateral small kidneys • 1- Chronic pyelonephritis .• 2- Obstructive atrophy• 3- Tuberculosis• 4- Renal artery stenosis ( occlusion)• 5- Hypoplastic kidney• 6- Radiation atrophy

Small kidneys

• Always bilateral small kidneys

• 1- Chronic glomeriolonephritis

• 2- Hypertensive nephropathy

• 3- Diabetes mellitus

• 4- Collagen vascular diseases .

• 5- Analgesic nephropathy

• There are some conditions causing enlarged kidneys .

Enlarged kidneys

• Always unilateral in compensatory hypertrophy• May be unilateral or bilateral• 1- Bifid collecting system• 2- Renal mass • 3- Hydronephrosis• 4- Lymphomatous infiltration• 5- Renal vein thrombosis .• Always bilateral • 1- Polycystic disease• 2- Acute glomeriolonephritis • 3- Amylodosis

Intravenous urography The IVU as a standard technique has now been largely replaced by ultrasound .The main current indications for IVU are .1 – when detailed demonstration of the pelvicaliceal system and ureter is required .2 – the assessment of suspected acute ureteric colic .3 – the investigation of renal calculi .4 – the investigation of haematuria .

Intravenous urography• Urographic contrast media are highly concentrated solutions of organically

bound iodine a large volume e.g.50—100 ml used is injected IV.. • It carried in the blood to the kidneys when it passes to the glomerular filtrate

the contrast medium within the glomeriolar filtrate is concentrated in the renal tubules then pass to PCS

• Adverse reaction • a - Mild reaction • Feeling of warmth spreading all over the body . . , • Articarial rashes usually subsides spontaneously .• b - More sever • Bronchospasm , laryngeal edema , hypotension develop and may be so

severe as to be life threatening .• c - Very sever reaction causes cardiac stand still ( death )• Patients with allergic manifestation particularly asthmatic patients or those

with previous allergic reaction should be given non-ionic organs & premedicated with steroids

• Patients are allowed to drink 500 ml of fluid in the 4 hours before IVU but should not eat.

IVU• It is particularly important not to fluid restrict patients with impaired

renal function before they are given contrast medium this may predispose to contrast medium induced nephrotoxicity .

• Before IVU a plain film ( KUB ) is indicated to see preparation of the pateint and identify calcification & to look for other structure and bone.. Calcification seen in the line of the ureters or bladder most be review with post contrast scan or with oblique view if necessary to determine wether the calcification lie in the renal tract . ,

• The major causes of UT calcification are • 1- Urinary calculi • 2- Diffuse nephrocalinosis .• 3- Localized nephrocalcinosis for e.g.( TB , tumor )• 4- Prostate calcification • Note that the calcification can be obscured by contrast medium..

IVU

• After injection look for the kidneys position, out line , normal length is 10 – 16 cm , normal cortical thickness is 2 – 2,5 cm , local bulging may be due to ,fetal lobulations,& scars.

• Look for calices should be evenly distributed & symmetrical .

• Normal shape of minor calyx is cupped shape • Clubbed ( dilated ) calices are due to • 1 – obstruction .• 2 – distraction of papillae .• a. reflux nephropathy .b .papillary necrosis.c .TB

IVU

• Renal pelvis & ureters • Shape , dilatation .due to (obst, cong,vasicoureteric

reflux) , filling defect ,• The commonest congenital variation in the pelvis is bifid

renal pelvis .• Some time the hole length of the ureter cannot be seen

because of the peristalsis • Bladder • Upper indentation due to uterus and sigmoid colon . • The lower indentation due to pelvic floor muscle• In post micturation film normally a little contrast trapped

in the mucosal fold ..

CT

• The role of CT in urinary tract imaging is expanding like US

• CT can characterize masses , in addition can show retroperitoneal structures & is very sensitive to detecting calculi .

• The main indication of CT are :• 1- To demonstrate renal masses & staging renal tumors .• 2- To delineate renal vascular anatomy .• 3- To diagnose or exclude renal traumas. • 4- To demonstrate renal radiolucent stones .• 5- In some center to assess acute ureteric colic .

CT scan

Haw to perform CT scan.CT is initially performed without using intravenous contrast medium ( non contrast CT to identify calcification).then images are obtained following intravenous administration of the contrast medium usually during the early renal cortical enhancement phase, which occurs at 40 seconds after the contrast injection ( the corticomedullary phase ) . then further scan is obtained several minutes later to demonstrate the homogenous nephrogram phase and the collecting systems , with using a new multidetector CT images may be reformatted in the coronal or sagittal plane, for surgical planning .

CT

• Normal CT • The renal parenchyma should have a smooth outline the

renal sinus fat is seen as very low attenuation tissue in the central part of he kidney ..there should be no calcification in any part of the renal tract

• Following IV injection of the contrsat medium the renal cortex opscified befor renal medulla in the coticomedullary phase , so in this phase the medulla show a low attenuation . later images demonstrate uniform opacification of the renal parenchyma & contrast medium seen in the renal pelvis and ureteres , the PCS show cupped shape calices with uniform width of renal parenchyma from calix to renal edge ..

CT scanThe ureters are seen in cross section as a dotes laying on the psoas muscles . they will not necessarily be seen at all levels because of peristalsisThe bladder has smooth out line and stands out against the pelvic fat the wall is thin and uniform diameter .The contrast medium appear more dense than urine and because the contrast medium is heavier than the urine so it collect in the depending portion so the depending portion appear more densely opacified . .

MRI • MRI give the same anatomical information as CT with the advantage of

being able to obtain scans directly in the coronal ,sagittal & oblique planes ,it is generally only used in selected cases e,g. to a – demonstrate renal artery stenosis b - IVC extension of the renal tumours or c – to clarify problems not solved by US or CT .

• Calcification is not visible on MRI, which is one of the main disadvantages of the technique for renal tract imaging .. .

• Normal MRI • As in the CT & US the renal counters should be smooth. Corticomedullary

differentiation is best seen on T1-weighted images and immediately following IV contrast enhancement with ( gadolinium ) , the renal collecting systems and the uretes are best seen on T2- weighted images as the fluid return a high signal , normal variants are well demonstrate on MRI , fetal lobulation seen as an undulating renal contour on coronal image with uniform cortical thickness .

• The column of Bertin may be distinguished from a mass as it has the same signal characteristic as the rest of the kidney in all sequences..

• Renal vasculature is best demonstrated following IV contrast .

radionuclide examination• Radionuclide examination : there are two main radionuclide techniques for studiyng

the kidneys • 1– the renogram which measure the renal function .• 2– scan for study the morphology ( DMSA scan)• The advent of CT scan & US has reduced the need for such scan .• They are now mainly used for evaluating renal scaring .• In renogram IV radionuclide substance injected there passages through the kidneys

can be observed with a gamma camera , which is positioned posteriorly over the kidneys and after a rapid injection of the radionuclide substance , early images show the blood vessels & the kidneys and by 5 min the collecting systems should be visible , serial images over 20 min show progressive excretion & clearance of activity from the kidneys. Quantitative assessment with computer enables a renogram curve to be produced & relatively function of each kidney to be calculated .

• The main indication for renogram are • 1– measurement of relative renal function and this may help the surgeon to decide

between nephrectomy or conservative surgery .• 2– investigation of urinary tract obstruction , particularly PUJ obstruction .• 3– investigation of renal transplant .

Special techniques

• 1- Retrograde & antegrade pyolography indications are limited used when no information in IVU, CT & MRI .

• 2- Micturating cystourothrography . Used fo diagnosis of• a- Vasicoureteric reflux,b- bladder , c- urethral

stricture,& post urethral valve .• Vidiourodynamics combines voiding cystourothrography

with bladder pressure measurements it is useful a – stress incontinence to distinguish detrusor instability from sphincter weakness . B – the test helpful in patients with obstructive symptoms , mainly elderly men to differentiate true obstruction from bladder instability & with neurogenic bladder .

• 3- urethrography.• 4- renal arteriography .