Kidney flashcards
Bright fluid helpful in identifying T2 sequence
CSF, Stomach, GB, “Perinephric sweat” (fluid around kidneys)
Delayed nephrogram
Defines obstruction. Kidney not enhancing like it should on nephrogram.
Ddx for bilateral delayed nephrogram (4)
bilateral obstruction, contrst nephropathy, systemic hypotension, myeloma kidney
Persistent nephrogram
Kidney is still enhancing long after contrast was given. Likely renal failure.
Renal mass protocol phases
Unenhanced. Nephrographic (100 seconds), pyelographic (excretory) phase (15 minture delay)
What can be seen on pyelographic phase
hyronephrosis vs. renal sinus cyst. Dilated calyces from reflux nephropathy (rather than cystic mass), calyceal diverticulum
CT enhancement quant
<10 HU: no enhancement. 10-19 HU: equivical. >20; enhancement
MR enhacement quant
<15%;none. 15-19; equivical, >20% enhancement
When are lesions “too small to characterize?”
If they are smaller than twice the slice thickness
Indications for renal mass biopsy (5)
Mets vs. RCC in known primary. Renal infection vs. cystic neoplasm. AML vs. RCC. To ensure correct tissue dx prior to ablation. To definitively diagnose suspcious renal mass in pt who is high risk for nephrectomy
Solid renal masses (6)
RCC, AML, Oncocytoma, lymphoma, non-neplastic masses (infection, AVM), renal pseudotumors (hypertrophied column of bertin, persistent fetal lobation
RCC risk factors
smoking, acquired cystic kidney disease, VHL, tuberous sclerosis
Types of RCC (5)
Clear cell, Papillary, chromophobe, collecting duct carcinoma, medullary carcinoma
Clear Cell RCC
Most common RCC, enhances avidly (equal to cortex), bilateral in VHL
Papillary RCC
2nd most common type. Hypovascular, enhances less than clear cell (enhancement is less than cortex). T2 dark
Chromophobe. a/w what?
A/w Birt Hoge Dube, Best prognosis.
Collecting duct RCC
rare, poor prognosis
Medullary RCC. Effects who?
Effects men w/ Sickle Cell TRAIT. Terrible prognosis
describe Robson staging of RCC
I; w/in renal renal capsule. II; out of capsule, but still in Gerota’s fascia. III; vascular or lymph node involvement (A; Renal vein or IVC, B; lymph nodes, C; venous and lymph nodes. IVa; through gerota’s fascia, Ivb; distant mets
Robson staging of RCC, which are rescectable?
Stages I-III are resectable
Bland thrombus vs. tumor thrombus
Enhancement, flow on u/s
Which is worse? RCC in renal vein, or RCC in adrenal gland
In Adrenal gland is worse (stage 4). Renal vein is just Stage 3
Fatty mass w/ calcification in the kidney is concerning for ___, in the retroperitoneum is concerning for ___
RCC, Liposarcoma
AML Pathognomonic imaging finding
macroscopic fat in a noncalcified renal lesion
AML; association. Treatment.
Tuberous sclerosis. Embolize if >4cm, due to risk of hemorrhage
Type of fat in AML?
Macroscopic. Will not drop out on dual phase MRI.
Hyperechoic kidney lesion on u/s (what is it most likely? What is next step in management?)
Its most likely an AML, but next step in management is to get a CT or MR w/ contrast to differentiate from RCC (especially papillary subtype,which is hyperechoic)
Ddx; T2 hypointense lesion in kidney (3)
Lipid poor AML, hemorrhagic cyst, papillary RCC
Oncocytoma
Look like RC, but have a central scar/spoke wheel. a/w Birt Hogg Dube. These are still resected, because it may be RCC.
Homogenous mass in kidneys is likely __
lymphoma. Usually B-cell. Homogenous, hypovascular, PET Avid
Renal lymphoma patterns (4)
Multiple lymphomatous masses. Solitary renal mass. Diffuse lymphomatous infiltration causeing nephromegaly, direct extension of rp disease
Non-neoplastic solid renal masses (2)
Infection (focal nephritis, abscess), AVM (avid enhancement)
Renal pseudotumors
Hypertophied column of Bertin. Persistant fetal lobuation (indentation of cortex. Presence of septa of Bertin on either side).
Birt Hogg Dube. Inheritance, 3 systems effected?
Aut. D. syndrome. Dermatologic lesions. Cystic lung disease, multiple renal oncocytomas, and RCCs.
Tuberous sclerosis features. Type of mutation. Findings (3 categories)
Aut D. Tumor suppressor gene mutation. Seizures, developmental delay, mostly benign tumors. Renal cysts, AMLs, slight increase risk of RCC, Cerebral hamartomas. Cardiac rhabdomyomas(sarcomas). Skeletel osteomas. Pulmonary lymphangioleiomyomatosis.
Tuberous sclerosis tumor locations (3 kidney, 1 in brain, heart, bones, lungs)
Renal cysts, AMLs, slight increase risk of RCC, Cerebral hamartomas. Cardiac rhabdomyomas(sarcomas). Skeletel osteomas. Pulmonary lymphangioleiomyomatosis.
Neoplastic differential of a cystic renal mass (3)
Cystic RCC. Multilocular cystic nephroma (enhancing septa. Baby boys and middle age women). Mixed epithelial stromal tumor (MEST); Middle aged women
Non-neoplastic differential for cystic renal mass
Renal abscess, Hemorrhagic renal cyst
Types of renal cysts (3)
Simple renal cyst, Renal sinus cyst (parapelvic, peripelvic), hyperdense (>70HU, likely secondary to prior hemorrhage)
Renal sinus cyst (Para vs. peri)
Parapelivic is a normal renal cotical cyst herniating into pelvis. PERIpelvic cyst; lymphatic in origin, due to lymphatic obstruction, small, multiple.
Bosniak CT classification?
Category I: simple cyst. II: three of fewer septa, maybe small calcs. also includes small (<3cm) high density cyst w/o enhancement. IIF: may have thick and nodular mural calcifications. walls may slightly enhance. Also includes large (>3cm) hyperattenuating cysts w/o enhancement III: thick, irregular wall, enhancement. Class IV: Enhancing nodular component
Bosniak cystic renal mass categories?
Category I Benign simple cyst Category 2 Benign Complicated (Iif has a small risk of malignancy) Category 3 Indeterminate cystic lesions Category 4 Malignant cystic tumors (enhancing soft tissue)
2 Questions to ask when assessing cystic kidney disease
Size of kidneys? Are other organs involved?
Cystic kidney disease (3 + a rare cause)
APCKD, VHL, dialysis related cystic disease. Lithium kidney is a rare cause
ADPCKD. How do they present
Adult, normal at birth, presents w/ HTN, hematuria, upper abdominal pain. Big cysts, liver involved.renal failure by middle age, berry aneurysms are deadly
ARPKD
Abnormal at birth. Lots of little cysts. Hepatic fibrosis (inverse to degree of renal disease)
Polycystic kidney disease relationship w/ RCC
Cystic kidney diesase does not increase risk of RCC. But it will cause renal failure, and dialysis does increase risk of RCC
Lithium kidney
Microcysts, normal sized kidneys, renal failure
CT findings of pyelonephritis?
Renal enlargement. Multifocal wedge-shaped hetergeneous areas. Parenchymal striations. Decreased enhancement. Perinephric stranding. Thick urothelium.
In reflux nephropathy scarring first develops where?
At renal poles.
DDx for unilateral enlarged kidney (4)
Pyelonephritis, acute ureteral obstruction, renal vein thrombosis, compensatory hypertophy.
DDx for striated nephrogram (7)
Pyelonephritis, renal infarct, renal veinthrombosis/vasculitis, renal contusion, acute urinary obstruction, renal tumor, radiation nephritis.
focal lobar nephronia
Old name for focal pyelonephritis
Pyelonephritis can have mild hydronephrosis. Explain this
This is thought to be due to bacterial endotoxin causing reduced peristalsis. Should not be confused w/ obstructive uropathy.
Pyonephrosis
Infection of an obstructed collecting system. Tx is emergent perc neph
Renal abscess treatment
<3cm; abx. >3cm - drainage.
Ddx small scarred kidneys. (unilateral, bilateral)
Reflux nephropathy, Previous renal surgery, renal infarcts, analgesic nephropathy
Emphysematous pyelonephritis versus emphysematous pyelitis?
Emphysematous pyelonephritis: diabetes, infection, gas in renal parynchema, emergency nephrectomy. Emphysematous pyelitis: gas in pelvis and calyces (trauma, iatragenic, infection), not a surgical urgency.
xanthogranulomatous pyelonephritis?
Chronic infection due to obstructing calculi, leading to replacement of renal parenchyma w/ fibrofatty inflammatory tissue. Middle-aged females with UTIs and constitutional symptoms, anemia, hematuria.
XGP common organisms. CT findings
Proteus mirabilis, E. coli. Fatty replacement. Perinephric inflammatory stranding, staghorn calculi. Bear paw sign of hypoattenuating fibrofatty masses arranged in a radial pattern.
XGP treatment
nephrectomy
HIV nephropathy.
Enlarged hyperechoic kidneys. a/w Focal segmental glomerulosclerosis (FSGS)