Methods of Imaging the Urinary Tract.pdf

Methods of Imaging the Urinary Tract 1. Plain radiography 2. Excretion urography (intravenous urogram [IVU]) 3. Ultrasound (US) 4. Computed tomography (CT): (a) CT for urological diagnosis and urological cancer staging (b) CT for characterization of renal lesion (c) CT adrenals (d) CT KUB (kidneys,...

Methods of Imaging the Urinary Tract 1. Plain radiography 2. Excretion urography (intravenous urogram [IVU]) 3. Ultrasound (US) 4. Computed tomography (CT): (a) CT for urological diagnosis and urological cancer staging (b) CT for characterization of renal lesion (c) CT adrenals (d) CT KUB (kidneys, ureters, bladder) (e) CT urography (CTU) (f) CT angiography 5. Magnetic resonance imaging (MRI): (a) MR for characterization of renal lesion (b) MR prostate (c) MR bladder (d) MR urography (e) MR adrenals (f) MR angiography 6. Micturating cystography and cystourethrography 7. Ascending urethrography 8. Retrograde pyeloureterography 9. Percutaneous renal procedures: (a) Biopsy (b) Cyst puncture (c) Antegrade pyelography (d) Nephrostomy (e) Percutaneous nephrolithotomy 10. Arteriography 11. Venography 12. Conduitogram 13. Radionuclide imaging: (a) Static renography (b) Dynamic renography (c) Radionuclide cystography—direct and indirect PLAIN FILM RADIOGRAPHY Indications Predominantly to evaluate renal tract calcifications—recognizing that CT is significantly more sensitive (>98% compared with 60% for plain films). Technique As for preliminary films for excretion urography (discussed later). INTRAVENOUS EXCRETION UROGRAPHY (IVU OR IVP) The technique is less frequently used than in the past and has now been very largely replaced by US, CT or MRI or a combination. Indications 1. Haematuria 2. Renal colic (see the section on variation) 3. Recurrent urinary tract infection 4. Loin pain 5. Suspected urinary tract pathology Contraindications General contraindications to intravenous (i.v.) watersoluble contrast media and ionizing radiation. In patients with contrast medium allergies, alternative modalities such as ultrasound or MR can be considered. Patients with impaired 43 renal function, particularly those with diabetes, should be prepared with oral or i.v. hydration, or an alternative imaging modality should be considered. Contrast Medium Low osmolar contrast material (LOCM) 300–370 mg I mL−1 Adult dose mL 50–100 Paediatric dose 1 ML kg−1 Patient Preparation 1. No food for 5 h prior to the examination. Dehydration is not necessary and does not improve image quality. 2. The routine administration of bowel preparation has been shown not to improve the diagnostic quality of the examination. Preliminary Image Supine, full-length anterior posterior (AP) of the abdomen, in inspiration. The lower border of the cassette is at the level of the symphysis pubis, and the x-ray beam is centred in the midline at the level of the iliac crests. If necessary, the location of overlying opacities may be further determined by: supine AP film of the renal areas, in expiration. The x-ray beam is centred in the midline at the level of the lower costal margin. 35° posterior oblique views (side of interest towards the film) tomography of the kidneys The examination should not proceed further until these images have been reviewed by the radiologist or radiographer and deemed satisfactory. Technique Venous access is established. The gauge of the cannula/needle should allow the injection to be given rapidly as a bolus to maximize the density of the nephrogram. Images 1. Immediate film. AP of the renal areas. This film is exposed 10–14 s after the injection (approximate ‘arm-to-kidney’ time). It aims to show the nephrogram at its most dense—i.e. the renal parenchyma opacified by contrast medium in the renal tubules. Tomography may assist in evaluation of the renal outline or possible masses (or ultrasound if subsequently available). 2. 5-min film. AP of the renal areas. This film gives an initial assessment of pathology—specifically the presence or absence of obstruction before administering compression. A compression band is then applied positioned midway between the anterior superior iliac spines—i.e. over the ureters as they cross the pelvic brim. The aim is to produce pelvicalyceal distension. Compression is, however, contraindicated: (a) after recent abdominal surgery (b) after renal trauma (c) if there is a large abdominal mass or aortic aneurysm (d) when the 5-min film shows already distended calyces indicative of obstruction 3. 10-min film. AP of the renal areas. There is usually adequate distension of the pelvicalyceal systems with opaque urine by this time. Compression is released when satisfactory demonstration of the pelvicalyceal system has been achieved. If the compression film is inadequate, the compression should be checked and repositioned if necessary and a further 50 mL of contrast medium administered and a repeat film taken after 5 min 4. Release film. Supine AP abdomen taken immediately after the release of compression. This film is taken to show the ureters. If this film is satisfactory, the patient is asked to empty the bladder. 5. After micturition film. Full-length supine AP abdomen. The aims of this film are to assess bladder emptying, to demonstrate drainage of the upper tracts, to aid the 45 diagnosis of bladder tumours, to confirm ureterovesical junction calculi, and uncommonly, to demonstrate a urethral diverticulum in females Additional Images 1. 35° posterior oblique of the kidneys, ureters or bladder—for equivocal collecting system lesions or localization of calculi 2. Tomography—if renal outlines are not well seen 3. Prone abdomen following the release film—may improve visualization of distal ureters 4. Delayed films at increasing (doubling of time intervals) up to 24 h after injection in renal obstruction Variation Renal colic—a limited study may be performed: preliminary films; 20-min full length (no compression); postmicturition full length; delayed films up to 24 h as required to show level and cause of obstruction Thank you for listening