Aortorenal & Selective Renal Arteriography

• performed by – percutaneous needle puncture – Catheterization of common femoral arteries

• Indications for renal arteriography include – Suspected renal artery stenosis (renovascular hypertension)– Vascular malformations– tumor embolization to minimize surgical– blood loss or treat bleeding tumors– Trauma

• Diagnostic renal angiography to demonstrate renal vascular anatomy

• Complications from conventional catheter angiography include– bleeding at the puncture site– contrast allergy or nephrotoxicity – renal or distal emboli.

Normal abdominal aortogram Bilateral renal artery stenoses

3D coronal CT angiography image demonstrates

an inferior accessory left renal artery (posterior view)

The left accessory renal artery origin(*) is better demonstrated rotating the model

in the axial plane

Inferior Venacavography & SelectiveVenography

• Risks of bleeding and emboli present in arterial studies are virtually eliminated

• Venography – rarely used today since theinformation can be

obtained at cross-sectional imaging• (CT or MRI) in almost all cases• Adrenal and renal venography

– performed occasionally in the setting of venous sampling to localize hormone secretion in patients with indeterminate noninvasive imaging studies

Normal inferior vena cava (C) Unusual retrogradefilling of morphologically normal renal veins (arrows) from antegrade injection into the inferior vena cavaB = retained contrast materialin the cecum from previous barium enema examination

Inferior vena cava obstruction

Double inferior vena cava (R, L). Persistent leftsupracardinal vein anomaly

Exampleof duplicated IVC on IV contrast enhanced axia

Angiography: renal venography.

Normal left renal vein Tumor thrombus

Miscellaneous Urologic Angiography

• Although angiography has little or no value in examination of the ureter, bladder, adrenals, and prostate, angiograms of these structures may be indicated in particular clinical situations, in which case the studies are usually “tailored” to the clinical problem

• Rarely used• Corpus cavernosograms are made by direct injection of

suitable contrast material into the corpora cavernosa of the penis– useful in examining for Peyronie’s disease, – impotence, priapism, and traumatic penile lesions– but these also are not commonly performed

SONOGRAPHY• Ultrasound waves for imaging are generated by

transducers, devices that convert electrical energy to sound energy and vice versa

• Special piezoelectric crystals that emit ultrasonic waves when they are deformed by an electrical voltage and, conversely, generate an electrical potential when struck by reflected sound waves

• act as both sonic transmitters and detectors• Ultrasound images are reflection images formed when part

of the sound that was emitted by the transducer bounces back from tissue interfaces to the transducer

• A more sensitive method of detecting flow, called – Power mode Doppler

Clinical Uses• evaluation of the kidney, urinary bladder,

prostate, testis, and penis• assessing renal size and growth• triaging patients with renal failure• detection and characterization of renal masses • provides an effective method of distinguishing

benign cortical cysts from potentially malignant solid renal lesions

• used to follow up mildly complicated cysts detected on CT

Doppler sonography

• is useful for the evaluation of renal vessels, vascularity of renal masses, and complications following renal transplant

• detect – renal vein thrombosis– renal artery stenosis– ureteral obstruction prior to the development of

hydronephrosis– arteriovenous fistulas– pseudoaneurysms

ADVANTAGE DISADVANTAGEease of use relatively low signal-to-

noise levelHigh patient tolerance tissue nonspecificity

noninvasiveness limited field of viewlack of ionizing radiation dependence on the

operator’s skill and the patient’s habitus

low relative costwide availability

Renal calculi and the consequence of obstruction

Renal Neoplasms

COMPUTED TOMOGRAPHY SCANNING

• thin, collimated beam of x-rays is passed through the patient and captured by an array of solid-state or gas detectors

• Spiral (or helical) CT uses a slip-ring gantry that rotates continuously while the patient moves constantly through the collimated x-ray beam– ability to image during specific phases of contrast bolus enhancement– allows improved image reformations

• Multidetector, or multislice, helical CT scanners have an array of multiple rows of detectors in a helical scanner such that multiple scan images can be acquired per gantry rotation, and as a by-product thinner sections and higher resolution achieved

Clinical Uses

• used in the evaluation of:– acute flank pain– Hematuria– renal infection (search for abscess) – renal trauma– characterization and staging of renal neoplasm

• evaluation of renal anatomy and pathology• Contrast media is usually administered

ADVANTAGES DISADVANTAGESwide field of view Restriction to the transaxial

plane for direct imaging

ability to detect subtle differences in the x-ray

attenuation properties of various tissues

tissue nonspecificity

good spatial resolution low soft-tissue contrast resolution

anatomical cross-sectional images

Need for contrast media

operator independence

Normal adrenal glands

CT densitometry. Thin section CT of incidental right adrenal mass

Bilateral adrenal lymphoma

Left adrenal carcinoma

Axial CT image reveals a predominant solid mass (arrow) abutting the left kidney,with areas of cystic change

Coronal oblique reformatted image from the same patient shows themass (arrow) to be inseparable from the inferior left adrenal limb

CT scans: kidneys

Simple renal cyst New Hydronephrosis

MAGNETIC RESONANCE IMAGING

• Widely used in assesing/ ealuating renal masses and its potential for non invasive vascular imaging

Clinical Uses

• Demonstration of congenital anomalies• diagnosis of renal vein thrombosis • diagnosis and staging of renal cell carcinoma• MR angiography

– useful in evaluating renal transplant vessels– renal vein tumor or thrombosis– renal artery stenosis

• primarily to stage bladder tumors and to differentiate between benign bladder wall hypertrophy and infiltrating malignant neoplasm

• principally used to stage patients with prostate cancer

Indication

• Evaluation – Renal masses– Renal vasculature– Prostate Cancer– Adrenal Masses

Contraindication

• Presence of ferromagnetic intracranial vascular clips, cardiac pacemaker, and certain prosthetic heart valves

• Severe claustrophobia and the patient’s inability to lie still 30-45 minutes of imaging(relative contraindication)

ADVANTAGE DISADVANTAGEdirect imaging in any

plane desiredscanning time is relatively slow

and as aresult image clarity is often

inferior compared withCT

choice of large or small field of view

excellent soft-tissue contrasimaging without

exposure to ionizing radiationImage blood vessels and the

urinary tract without contrast Material

Gadolinium-enhanced renal magnetic resonance angiography

• As new imaging methods have been developed, changes have occurred in patterns of use for each type of imagin

• increased familiarity with and confidence in sonography and CT scanning have resulted in a decrease in the use of some long-established conventional uroradiologic studies such as EU.

COMPARISON OF IMAGING METHODS

• Several factors are involved in these changes:– (1) the increased effectiveness of newer imaging

methods over older ones for some aspects of urodiagnosis

– (2) the availability of equipment, trained technical personnel to operate it, and physicians to interpret the results

– (3) increased awareness of the hazards of ionizing radiation

– (4) the desire to use noninvasive examinations if possible

Comparison of imaging methods in the evaluation of renal cell carcinoma

Computedtomography (CT) scan

Angiogram

MRI scans MRI scans

Comparison of imaging methods

Excretory urogramRight femoral arteriogram

CT scan CT scan