Urinary tract•The four basic examination of the urinary

tract:ultrasound,IVU,CT,radionuclide examinations

•MRI and arteriography:limited to selected patients

(•FDG-PET)CT is still under investigations •Ultrasound,CT,MRI are essentially used

for anatomical information •Radionuclide examintaions provide

functional information •IVU provides both functional and

anatomical information

Imaging techniquesUltrasound:is the first-line investigation in most patients,providing anatomical information without requiring ionizing radiation or the intravenous contrast medium

The main uses: •Investigate patients with symptoms through to

arise from the urinary tract •Demonstrate the size of the kidneys,exclude

hydronephrosis in patients with renal failure •Diagnose hydronephrosis,renal

tumours,abscesses and cysts •Assess the follow-up renal size and scarring in

children with urinary tract infection •Assess the bladder and prostate

tumors

calcifications

hydronephrosis

Normal kidney

Cont..

Urography:imaging of the renal tract using intrvenous iodinated contrast medium.IVU has largely been replaced by a combination of ultrasound and CT urography

Advantages of the CT:

•Highly sensitive for the detection of stones •Allow the characterization of renal lesions

•Detection of ureteric lesions •Demonstrate the surrounding

retroperitoneal and abdominal tissues•Overcome the overlap of superimposed

tissues

Intravenous urography or CT urography

CT urography

When detailed demonstration of the pelvicaliceal system and ureters are required

Investigation of renal calculi

Suspected ureteric injury,e.g.following pelvic surgery or trauma

Investigation of haematuria

Assessment of acute ureteric colic

Characterization of a renal mass

Staging and follow-up of renal carcinoma

To delinate renal vascular anatomy

to diagnose or exclude renal trauma

Cont..

MRI: gives similar anatomical to information to CT ,with the advantages of:

•Being able able to obtain scans directly in the coronal,sagittal and oblique planes in addition to the axial plane

•Used in selected circumstances,e.g.renal artery stenosis or inf vena caval extension of renal tumors or to clarify problems not solved by ultrasound or CT

•Assess the extent of bladder or prostate cancer prior to consideration for surgeryDisadvantages:calcification is not visible on MRI

Duplicated collecting system by ultrasound(A),MR(B,C)

Cont..Radionuclide examintion:Radionuclide techniques for studying the kidneys include:

•The renogram wich measures renal function •Scans of renal morphology The presence of

reflux in •children may be diagnosed using the technique of indirect voiding cystography.Renogram:The main indications:

•Measurement of relative renal function in each kidney

•Investigation of urinary tract obstruction •Investigation of renal transplants

Retrograde and antegrade pyelography:The indications are limited to those situations where the information can not be achieved by less invasive means,e.g.IVU,CT or MRI to confirm a possible transitional cell carcinoma in the renal pelvis or ureter

Urethrography:The indications:indications of urethral strictures and to demonstrate extravasation from the urethra or bladder neck following trauma

Renal artetriography:It is mainly used to confirm the CT or MRI findings and to confirm renal artery stenosis.

Renal arteriograohy

urethrography Antegrade Pyelography

Urinary tract disorders:

Urinary calculi: plain film examination of the urinary tract is more sensitive than ultrasound for detecting opaque renal and ureteric calculi.

CT,when performed without intravenous contrast medium,is exquisitely sensitive for the detection of calculi.It is used in place of IVU for the detection and precise anatomical localization of stones prior to treatment in most centres.

nephrocalcinosisIs the term used to describe focal or diffuse calcification within the renal paranchyma

Urinary tract obstruction

Ultrasound and urographic examination play major roles when evaluating urinary tract obstruction and CT urography has overtaken IVU for the investigation of obstruction.radionuclide studies show typical changes,but are rarely the primary imaging procedures.

ultrasound:It is often not possible to determine the cause of urinary tract obstruction at ultrasound examination.ultrasound may demonstrate a pelvic mass,such as a uterine or ovarian mass,causing external compression of the collecting system .

Puj obstruction

Duplex left collecting system with a puj obstruction in lower pole moiety

MRI.puj obstruction

Cont.

IVU:in some centres,the ivu remains the primary imaging modality in patients with suspected acute obstruction,wich is usually caused by a calculus.

CT:is now widely used to evaluate urinary tract obstruction.in acute obstruction ,non-contrast enhanced CT sensitively demonstrates calculi and unopacified,dilated collecting system can frequently be traced down to the point of obstruction.non-contrast CT is often used in acute ureteric colic,as an alternative to IVU ,in patients with an allergy to intravenous contrast medium.CT also has the advantage of demonstrating possible alternative causes of acute abdominal pain,such as appendicitis.chronic obstruction by tumour either within the renal collecting system or by an external tumour causing compression ,may be visualized directly on CT or MRI and staging of the tumour can be performed during the same investigation.

Congenital intrinsic pelviuretericjunction(PUJ)obstruction

In this disorder,peristalsis is not transmitted across the pelviureteric junction.the diagnosis depends on identifying the dilatation of the pelvis and calices,with an abrupt change in caliber at the pelviureteric at all.Puj obstruction can be difficult to distinguish on IVU from otherwise normal.(see figs in slide 17)

Extrinsic causes of obstructionTumours.carcinoma of the cervix,ovary and rectosigmoid colon and malignant lymph node enlargement are frequent causes in category of ureteric obstructionCT is the ideal method of diagnosis because it shows the tumour mass as well as the level of obstruction.

Cont.

Retroperitoneal fibrosisIn most cases,no cause can be found for this benign fibrotic condition,which encases the ureters and causes obstruction

CT is the best diagnostic method of choice.

Retroperitoneal fibrosis Carcinoma of Rectosigmoid

colon

Renal parenchymal masses

Almost all solitary masses arising within the renal parenchyma are either mailgnant tumours or simple cysts.

Multiple renal masses include:•multiple simple cysts

•Polycystic disease •Malignant lymphoma

•Metastases Inflammatory masses

Cont.

Ultrasound:When the ultrasonographer is sure that the diagnosis is a simple cyst,no further investigation is needed.indeterminate lesions with both cystic and solid components need further evaluation with CT.Angiomyolipomas are a fairly frequent incidental finding at ultrasound ,appearing as small echogenic masses.CT or MRI may be used to confirm the diagnosis.

angiomyolimpomas

IVU.cont.The initial diagnosis of a renal mass is now rarely made on IVU,as ultrasound and CT are the usual primary modalities.Once a mass is seen or suspected at IVU ,the next step is to diagnose it’s nature using ultrasound or CT.

CT and MRI of renal massesCT has proved very useful for characterizing indeterminate renal masses identified on ultrasound.CT may be used to differentiate cysts from tumours,to diagnose angiomyolipomas,and to stage renal carcinoma.renal masses may be characterized on MRI,but MRI is usually reserved for solving specific problems.Angiomyolipomas are usually incidental findings.they are benign tumours ,which rarely cause problems,although,on occasion,they cause significant retroperitonal haemmorrhage.at CT and MRI ,their fat content allows a confident diagnosis.The CT diagnosis of renal carcinoma is usually sufficiently accurate so that preoperative biopsy is rarely performed.Staging of renal cell carcinoma is usually undertaken with CT,the current method of choice,CT, shows local direct spread,can demonstrate enlargement of draining lymph nodes in the retroperitoneum,diagnose live,adrenal and pancreatic metastases and show tumour growing along the renal vein in to the infrior vena cava.

Urethelial tumorsAlmost all tumours that arise within the collecting systems of the kidneys are transitional cell carcinomas.In some centres,the IVU plays an important role in demonstrating the upper tract.

it is easy to confuse tumors with overlying gas shadows on an IVU,and tomograohy or ultrasound may be required to solve the problem.CT plays an important role in confirming or ruling out radiolucent calculi .

CT urography demonstrates thickening of the wall of the ureter at the site of a uothelial tumour.the ureter is often obstructed at the level of a TCC.

Acute pyelonephritisIs usually due to bacterial infection from that organisms that enter the urinary system via the urethra.anatomical abnormalities such as stones,deplex,..predispose to infection.in patients presenting with signs of infection associated with pain,if the symptoms are not settling with antibiotics,ultrasound and plain films may diagnose underlying stones,obstruction or abscess formation.in some cases if the pain is severe,an IVU or CT KUB may be done to demonstrate or rule out acute ureteric colic.ultrasound of the kidneys may demonstrate underlying obstruction or stones.many hospitals do a DMSA to demonstrate scarring.

Renal and perinephric abscesses

Ultrasound is the initial imaging investigation in most suspected renal abscesses,although in patients who are very unwell CT is often the first imaging investigation.With CT,it is possible to see enhancement of the wall of the abscess following intravenous contrast injection.

pyonephrosisPyonephrosis only occurs in collecting systems that are obstructed.ultrasound is the most useful imaging modality for pyonephrosis.in addition to showing the dilated collecting system,it may demonstrate multiple echoes within the collecting system from infected debris.

tuberculosis

Follows blood-borne spread of mycobacterium tuberclosis,usually from a focus of infection in the lung.in the early stages of the disease,the ultrasound and IVU may be normal.Ultrasound may demonstrate calcifications and pelvicaliceal dilataion and cavities,but the appearances are non-specific.CT can sensivitively demonstrate early calcifications,small cavities and external spread.