Renal imaging Flashcards
flank pain evaluation: goals
- establish presence of ureteral obstruction and determine if stone disease is cause
- if stone present, provide info to assist with therapy (stone location, size, composition, complicating features)
- if no stone present, provide an alternative diagnosis
definition: urolithiasis
excessive excretion and precipitation of salts in the urine or a lack of inhibiting substances
what sign should you look for in a CT for suspected ureteral obstruction?
soft tissue “rim” sign
when is US appropriate for flank pain?
- pregnant woman where stones are suspected
what is the initial imaging modality for flank pain?
non contrast CT
what is the first line indication for flank US?
- unexplained hematuria or renal dysfunction
- many renal lesions are often discovered incidentally
what is a soft tissue “rim” sign?
rim of tissue around the stone at the impaction site on CT = ureteral wall edema
what are secondary CT signs of ureteral obstruction from stones?
- perinephric stranding / fluid
- collecting system dilation
- ureteral dilation nephromegaly
- decreased enhancement
there is a 96% positive predictive value for stones when which two signs present alongside acute flank pain? what is the negative predictive value when these signs are absent?
- hydroureter
- perinephric stranding
- when absent: negative predictive value 93%
what is the first line imaging test in patients with unexplained hematuria or renal dysfunction?
US
what is the major method of imaging and characterizing cystic and solid renal lesions?
CT
what is the most common renal mass?
simple cyst
what is the most cost effective method of defining and confirming a benign cyst?
US
what is “enhanced through transmission”
when an US beam passes through fluid, the intensity of the sound energy is not diminished - therefore tissues behind the fluid are more echogenic (brighter) than tissues not behind the fluid
hounsfield unit for water
0
hounsfield unit for air
-1000
bosniak classification of cystic masses
cat 1: simple benign, thin walls
cat 2: benign, may contain thin septa with calcification
cat 2F: increased septa and thicker calcification
cat 3: indeterminate, thick, irregular walls
cat 4: malignant, thick irregular enhancing walls
what is the most common solid renal mass?
RCC
what does tumefactive mean?
ball-shaped
angiomyolipomas occur spontaneously with 30-50% occurring in patients with what condition?
tuberous sclerosis
what neoplasms have an infiltrative epicenter in the renal sinus?
- transitional cell carcinoma
- squamous cell carcinoma
what neoplasms have an infiltrative epicenter in the parenchyma?
- lymphoma
- infiltrating RCC
- metastases
an adrenal mass of ____ cm has a risk of malignancy of up to 85%
how are these managed?
- 6 cm
- surgery
benign adenomas contain microscopic ________
lipid
what is the single best test for determining whether an incidental adrenal mass is an adenoma?
CT scan with pre and post contrast delayed imaging
