Flashcards in Renal imaging Deck (22)
What is a KUB used for?
- Kidney-ureter-bladder (flat plate)
- looking for stones (won't pick up uric acid stones)
- scout film for IVP (intravenous pyelogram)
- lower abdominal film so you can check out some abdominal pathology
- downside: can't pick up masses, gas in bowels may obscure kidney stones
When is U/S used? How are kidneys scanned?
- first test done in renal disease - fast and cheap, no contrast
- use in expectant mothers with pain
- Renal mass characterization: cyst (benign) vs solid (malignant most likely), size and position of kidney
- detects obstruction - hydronephrosis
- polycystic kidney disease (structural abnormality)
- chronic renal failure (functional abnormality)
- limited by body habitus
- right kidney scanning: anterior, lateral, and posterior
liver is acoustic view window, left kidney: requires a posterior approach, through the spleen
- ureters are not normally seen
- renal pelvis is black when visible
- medullary pyramids are hypoechoic
- cortex is mid-gray, less echogenic than liver or spleen
- capsule is smooth and echogenic
Changes in degrees of hydronephrosis?
- mild - to moderte calyces are dilated a small amt and in severe: dilated almost throughout the whole kidney
When is an IVP (intravenous pyelogram used?
- when there is a suspected obstruction of flow of urine and fxn of kidney (stone, papillary necrosis)
- rapid IV bolus of dye with delayed films - see where contrast stops - at location of stone
- done at intervals: get KUB at 1, 5, 10 and 15 min.
- downside: using IV contrast (can't use if you have renal disease, allergic to contrast)
Use of CT scans?
- eval renal tumors and local spread of renal malignancy
- trauma (extra-peritoneal organ)
- renal colic (helical CT with stone protocol):
small calculi easily visualized
collecting system dilation
- now GOLD std for suspected stones
- high resolution CT angiography
- can detect smaller cysts (2-3 mm in size) - US will miss these
- CT urography - can ID urothelial tumors better than IVP (downside: sensitive to contrast)
- don't ha ve to worry about gas in the colon
What component in cysts make them higher risk for cancer?
- complex cysts with calcifications
When are MRIs used?
- renal mass characterization:
usually reserved for pts with CT CIs (contrast)
- great tissue contrast (good for complex masses)
- no ionizing radiation and it is expensive
- invasion from tumors..stages kidney tumors
- THey have MRUs (magnetic renal urography): may be better study to check on anatomical renal abnormalities
When are renal arteriographies used? What is it?
- invasive with contrast
- need to know Cr
- can also show you anatomy before transplant
- GOLD std for renal artery stenosis
- doppler U/S, MRA and CTA are used as well but you can stent with the angio
When is renal venography indicated?
- useful for dx of renal vein thrombosis
When is a retrograde/anterograe pyelography indicated?
- dx urinary tract obstruction or tumors
- injects contrast into the ureter to visualize the ureter and the kidney
- helps with placement of ureteral stents
- used to evaluate trauma
- now we usually do CT or US (better view of kidneys)
When is nuclear imaging indicated? Process?
- renal perfusion and fxn (DTPA, mag3: dyes)
- obstruction (lasix renal scan) - common at UPJ
- renovascular HTN
- no side effects to dye
- pt lies still for clear pictures and radioisotope tracer is injected into the vein
- a gamma camera detects the radioactivity and images are projected onto a computer
- can find out what percentage each kidney contributes to the total kidney function
What is a voiding cystourethrogram?
- used to eval the urethra, bladder, ureters, and kidney
- pts bladder is filled with contrast via a catheter and once the bladder is full - inspect for reflux into ureters
- procedure ends with pt voiding
- this is done under fluoroscopy
- good for kids with recurrent UTIs, kidney infections - searching for vesicourectal reflux
- in males: eval for urethral abnormalities: posterior urethral valves (valves block urine output)
- pt voids under fluoro with spot films
Best initial imaging test for chronic renal failure?
- U/S of kidneys
Someone comes in with flank pain and bloating - initial imaging?
UA: 6-10 RBCs, what is best initial study prior to sending pt to specialist?
U/S main uses?
CT gold std for?
- renal stones
- dx renal tumors
What tests are reliable for dx renal vein thrombosis?
- renal venography, CT, MRI
- increasing role in suspected renovascular HTN
How can VUR and scarring be detected early?
- with radioisotope scanning with DMSA or MAG3 and voiding cystourethrogram