CORE - Urinary Flashcards
Nephrographic phase
100 seconds
Excretory phase
15 minutes
“Too small to characterize”
less than twice the slice thickness
Definition of enhancement on CT
> 20 HU
Definition of enhancement on MRI
> 20% increase in signal intensity
Soft tissue rim sign
small rim of soft tissue (ureter) surrounding an obstructing stone, distinguishing it from a phelobolith
Corduroy appearance of the ureter
leukoplakia (squamous metaplasia); premalignant
Enlarged echogenic kidneys
ARPKD in peds, HIV nephropathy in adults
Young adult with hypertension and renal mass
juxtaglomerular cell tumor; secrete renin => hypertension + hypokalemia
Calcifications in RCC correlates with a better or worse prognosis?
better prognosis
Hyperechoic renal mass with posterior acoustic shadowing
AML; RCCs rarely demonstrate posterior acoustic shadowing
Hyperacute rejection
ABO incompatibility
Acute rejection timing
<3 months
Chronic rejection timing
> 3 months
Multifocal ureteral stenoses
ureteral TB
Total volume for CT cystogram
350 cc or as much as tolerated, instilled by gravity (bag 40 cm above bladder); dilute water soluble contrast (50 cc contrast + 500 cc warm saline)
Blood at the meatus, painful urination, or inability to void after trauma
perform RUG before cystogram
Prostatic utricle
mullerian duct derivative, blind ending male homologue to the uterus and vagina; located at verumontanum
Inflammed glands of Littre (RUG)
urethritis
Most common site of urethral injury
disruption at the urogenital diaphragm and rupture of bulbomembranous urethra
Pyelonephritis on US and CT
decreased perfusion => decreased Doppler flow and hypoenhancing
Another term for renal pyramids
renal medulla (or medullary pyramids)
What are the renal papilla?
tips of the medullary pyramids
Echogenicity of cortex vs. pyramids (adult)
normal pyramids are hypoechoic relative to cortex
Echogenicity of cortex vs. pyramids (neonate)
hyperechoic pyramids; due to Tamm-Horsfall proteinuria
Dromedary hump
normal variant; focal bulge on left kidney related to adjacent spleen
Unilateral renal agenesis associations
unicornuate uterus (females); absent vas deferens/epididymis, seminal vesicle cysts (males)
Mayer-Rokitansky-Kuster-Hauser syndrome
congenital absence of uterus and upper vagina +/- fallopian tube/ovarian abnormalities; assoc. with renal anomlies
Most common renal fusion anomaly
horseshoe kidney
Complications of horseshoe kidney
increases risk of traumatic injury, stasis (infection, stones, TCC), Wilms, UPJ obstruction
Horseshoe kidney associations
Turner’s, Wilm’s
Complications of crossfused renal ectopia
stones, infection, hydronephrosis
Characteristics of RCC mets in liver and brain
hypervascular; enhancing in liver, hemorrhagic in brain
Risk factors for RCC
tobacco, VHL, dialysis-associated kidney disease, family history, tuberous sclerosis (younger age)
Renal mass with macroscopic fat and no calcifications
AML
Renal mass with macroscopic fat and calcifications
RCC (very rare); AMLs do not contain calcification
Renal mass with signal loss on out-of-phase
RCC (clear cell); AMLs do NOT contain microscopic fat
Renal mass with etching artifact on out-of-phase
represents macroscopic fat (that may not be resolvable on other sequences); suggests AML
T2 dark renal mass DDx
papillary RCC, lipid-poor AML, hemorrhagic cyst
Multiple renal masses DDx
RCCs (VHL), RCCs + oncocytomas (Birt-Hogg-Dube), AMLs (tuberous sclerosis)
Most sensitive phase of contrast for RCC
nephrographic (80-100 seconds)
RCC subtype assoc. with VHL
clear cell
RCC subtype assoc. with sickle cell trait
medullary
Hereditary RCC subtype
papillary (may also be related to chronic dialysis)
RCC subtype assoc. with Birt-Hogg-Dube
chromophobe (best prognosis of all subtypes)
Multiple bilateral renal cysts with increased risk of RCC
dialysis-associated cystic kidney disease
Renal mass(es) with preservation of reniform shape
lymphoma (often bilateral)
AML size assoc. with increased risk of hemorrhage
> 4 cm
2nd most common benign renal tumor
oncocytoma
Enhancing renal mass with central “scar” on CT/MR
suggestive of oncocytoma
Oncocytoma vs. RCC on PET
oncocytoma is PET hot, RCC is PET cold
Treatment of oncocytoma
typically resected; if obvious features of oncocytoma, may elect to watch
Bosniak 1
simple cyst, no septa or enhancement; no follow-up
Bosniak 2
hairline septations, fine calcificationl; also homogeneously hyperdense cysts <3 cm; no follow-up
Bosniak 2F
several septations, thick calcification; also homogeneously hyperdense cysts >3 cm; imaging follow-up
Bosniak 3
nodular spetal thickening, enhancing septa/wall; surgical
Bosniak 4
enhancing nodule; surgical
ADPKD associations
liver cysts, Berry aneurysms, seminal vesicle cysts, biliary hamartomas; end result is renal failure
Seminal vesicle cyst DDx
ipsilateral renal agenesis, ADPKD
ARPKD associations
congenital hepatic fibrosis, Caroli disease
Lithium nephropathy
small to normal-sized kidneys with numerous tiny cysts; may cause diabetes insipidus and renal insufficiency
MCDK on renal scintigraphy
no excretory function
Cyst originating from renal parenchyma, may compress collecting system
parapelvic
Cyst originating from renal sinus, mimics hydronephrosis
peripelvic (lymphatic origin); small and multiple
Striated nephrogram DDx
pyelonephritis, acute urinary obstruction, renal vein thrombosis, contusion, post-radiation, ATN (bilateral)
Renal abscess size needing drainage
> 3 cm
Emphysematous pyelonephritis vs. pyelitis
gas in the renal parenchyma vs. gas in the collecting system; both are seen in diabetics
Causes of pyonephrosis
stones, tumor, sloughed papilla (due to pyelonephritis)
Fluid-fluid level in renal collecting system (US)
pyonephrosis; Tx emergent PCN
Bear paw appearance of kidney on CT
xanthogranulomatous pyelonephritis; staghorn calculus, recurrent infection, fibrofatty parenchymal replacement
Papillary necrosis DDx
POSTCARD - Pyelonephritis, Obstruction, Sickle cell, TB, Cirrhosis, Analgesics (NSAIDs), Renal vein thrombosis, Diabetes
Ball-on-tee sign
papillary necrosis
Lobster claw sign
papillary necrosis
Signet ring sign (renal)
papillary necrosis
Most common cause of papillary necrosis
diabetes
Small, calcified kidney
“putty kidney” (sequela of TB)
Kerr kink sign
sharp kink at the UPJ; due to scarring from renal TB
Scattered punctate renal cortical calcifications
disseminated PCP (similar findings in spleen and liver involvement)
T/F - contrast allergy is a risk factor for contrast-induced nephropathy
FALSE
Risk factors for contrast-induced nephropathy
renal insufficiency, diabetes, CHF, dehydration, myeloma
Prevention of contrast-induced nephropathy in renal insufficiency
IVF 6-12 hours before and 4-12 hours after (NOT oral)
Renal stone associated with UTI
struvite
Renal stone(s) not seen on x-ray
uric acid, indinavir, cystine, xanthine
Renal stone(s) not seen on CT
indinavir
Most common renal stone
calcium oxalate
Treatment for uric acid stones
medically, with sodium bicarbonate or potassium citrate (increase pH)
Renal cortical necrosis
hypoenhancing renal cortex +/- very thin enhancing rim; affects entire kidney
Causes of renal cortical necrosis
severe hemodynamic shock, hemolytic uremic syndrome, renal transplantation
Cortical nephrocalcinosis DDx
renal cortical necrosis, chronic transplant rejection, Alport syndrome, hyperoxaluria, chronic glomerulonephritis
Medullary nephrocalcinosis DDx
medullary sponge kidney, hyperparathyroidism (hypercalcemia), sarcoidosis (hypercalcemia), type 1 RTA, furosemide (child)
Medullary sponge kidney associations
Caroli disease, Ehlers-Danlos, Beckwith-Wiedemann
Page kidney
subcapsular hematoma => secondary hypertension (takes several months to develop)
Unilateral delayed nephrogram
acute ureteral obstruction, renal vein thrombosis, renal artery stenosis
Bilateral delayed nephrograms
systemic hypotension, ATN, contrast-induced nephropathy, bilateral obstruction, myeloma kidneys
Cortical rim sign
subacute renal infarct; hypoenhancing area of infarction with thin enhancing rim
Causes of renal vein thrombosis
dehydration, nephrotic syndrome, sickle cell
Renal trauma with suspicion of collecting system injury - NEXT STEP
delayed phase to assess for urine leak
Normal renal artery waveform
low resistance, brisk upstroke, forward flow throughout diastole; for native and transplant kidneys
Post-renal transplant collections
hematoma (immediate), urinoma (1-2 weeks), abscess (3-4 weeks), lymphocele (>4 weeks)
Most common post-transplant fluid collection to cause hydronephrosis
lymphocele
Ipsilateral lower extremity edema in a post-renal transplant patient
lymphocele; causes femoral vein compression
Findings in acute renal transplant rejection
swollen kidney, echogenic pyramids, elevated RIs, urothelial thickening
ATN vs. acute rejection (post-transplant)
both occur within first week; on MAG3 study, ATN demonstrates normal perfusion, while acute rejection demonstrates delayed perfusion; both show delayed excretion
Reversal of diastolic flow in transplant main renal artery
renal vein thrombosis; occurs <1 week following transplant; renal vein would show no flow
Most common vascular complication of renal transplantation
renal artery stenosis; occurs at the anastomosis
Findings in transplant renal artery stenosis
PSV >200-300 cm/s or PSV ratio >2; high resistance waveform with elevated PSV pre-stenosis; parvus et tardus post-stenosis
Findings in renal transplant AVF
tissue vibration artifact, elevated PSV (in artery), pulsatile venous waveform
Post-renal biopsy complications
AVF, pseudoaneurysm
Cyclophosphamide association
increased risk of TCC
Causes of primary megaureter
idiopathic, distal adynamic segment, reflux at UVJ
Causes of pseudoureterocele
impacted stone, recently passed stone, bladder malignancy
Ureterocele vs. pseudoureteocele
pseudoureterocele has loss or thickening of the normal thin lucent halo surrounding a ureterocele
Ureteral wall calcifications
schistosomiasis, TB
Ureteritis cystica
numerous tiny subepithelial cysts, due to chronic inflammation (diabetics with recurrent UTIs)
Multiple small ureteral outpouchings
ureteral diverticulosis; often bilateral, due to chronic inflammation
Premalignant -plakia
leukoplakia (risk of SCC); both are due to chronic irritation and occur in bladder > ureter
-plakia seen in immunocompromised patients
malakoplakia (not premalignant)
Ormond disease
idiopathic retroperitoneal fibrosis
Medial deviation of ureters
retroperitoneal fibrosis, psoas hypertrophy, retrocaval ureter (right side), pelvic lipomatosis
Lateral deviation of ureters
retroperitoneal lymphadenopathy, aortic anuerysm
Nuclear medicine findings of retroperitoneal fibrosis
gallium avid, PET hot
Risk factors for TCC
smoking, cyclophosphamide, horseshoe kidney, nephrolithiasis, HNPCC
Location of TCC
bladder > collecting system > lower ureter > upper ureter
Balkan nephropathy
increased risk of upper tract TCC; assoc with aristolochic acid ingestion in plant seeds
Smooth long segment ureteral filling defect
ureteral fibroepithelial polyp; most common benign tumor of ureter
Treatment of multilocular cystic nephroma
resection (cannot be distinguished from cystic RCC or cystic Wilms)
Eagle-Barrett syndrome
a.k.a. prune belly syndrome; abdominal muscle deficiency, hydroureteronephrosis, cryptorchidism
Bladder diverticulum associations
chronic outlet obstruction, Ehlers-Danlos
Hutch diverticulum
congenital, occurs near UVJ; associated with VUR
Anterior-superior bladder diverticulum
likely a urachal diverticulum
Lateral protrusion of the bladder into the inguinal canal
bladder ears; transient
Confluence of rectum, vagina, and urethra into a single common channel
cloacal malformation; females only, assoc. with imperforate anus
Schistosomiasis
calcified bladder and/or ureters; increased risk of SCC
Leiomyoma (bladder)
most common at the trigone; most common mesenchymal bladder tumor
Most common early complication of urinary diversion (<30 days)
adynamic ileus > urine leak
Emphysematous cystitis association
diabetes
Causes of bladder fistula
diverticulitis, Crohn’s, rectal cancer; men > women (no lady parts to interfere)
Pine cone bladder
neurogenic bladder (stasis => stones/infection/cancer)
Bladder outlet obstruction sequelae
diverticulae; stasis => stones/infection/cancer
Pear-shaped bladder
pelvic hematoma, pelvic lipomatosis, lymphocele(s), psoas hypertrophy
Suspected bladder rupture - NEXT STEP
CT cystogram (contrast infused into bladder via foley)
Most common type of bladder rupture
extraperitoneal; Tx is foley placement (vs. intraperitoneal rupture, which is surgical)
Molar tooth sign
extravasated contrast in the space of Retzius (extraperitoneal rupture)
Extraperitoneal bladder rupture association
pelvic fracture (almost 100% of the time)
Urethral injury type - stretching/elongation without extravasation
type 1
Urethral injury type - extravasation above the urogenital diaphragm only
type 2
Urethral injury type - extravasation below the urogenital diaphragm
type 3; may extend to the pelvis or perineum; bladder neck is intact
Urethral injury type - extraperitoneal extravasation
type 4; bladder neck is disrupted
Urethral injury type - periurethral extravasation
type 4a; bladder base is disrupted
Urethral injury type - extravasation extending into the anterior urethra
type 5
Short segment stricture of bulbous urethra
straddle injury
Long segment stricture of bulbous urethra with irregularity
gonococcal
Location of iatrogenic urethral injury
at the penile-bulbous (or penile-scrotal) junction
Multiple small filling defects on retrograde urethrogram
condyloma acuminata; RUG not recommended if suspected due to seeding
Urethrorectal fistula associations
post-brachytherapy, post-radiation
Urethral diverticulum (male)
due to long-term foley placement
Most common malignancy of urethra (male)
SCC (distal) > TCC (proximal); cancer in a urethral diverticulum is likely adenocarcinoma
Urethral diverticulum (female)
assoc. with repeated UTIs and urinary incontinence; increased risk of adenocarcinoma
Stuff located at the verumontanum
paired ejaculatory ducts, prostatic utricle, PUVs (if present)
Urethral stuff located at the urogenital diaphragm (male)
membranous urethra, external urethral sphincter, Cowper’s glands (drain into bulbous segment)
Glands of Littre
small mucous glands in the penile urethra; opacification on RUG suggests urethritis
Skene glands
secrete mucus into female urethra; equivalent of male prostate
Best study to visualize anterior urethra
retrograde urethrogram (RUG)
Best study to visualize posterior urethra
voiding cystourethrogram (VCUG)
Medullary sponge kidney
tubular ectasia + medullary calcification
Dual energy ratios for uric acid, calcium oxalate, and cystine stones
uric acid = 1.1, calcium oxalate = 1.25, cystine = 1.25; ratio of low energy HU to high energy HU
> 50% renal artery stenosis (ultrasound)
acceleration time >70 msec (tardus) or acceleration index <3.0 m/s
Resistive index (RI) formula
(PSV - EDV) / PSV
Elevated RI in native kidney (>0.7)
acute obstruction; or difference >0.1 between kidneys
Intrarenal arteries (from big to small)
segmental»_space; interlobar»_space; arcuate