Radiology Flashcards
What is one of the most useful imaging modalities for assessment of the kidneys and collecting systems?
Intravenous urogram (IVP)
What is the most common current indication for IVP?
Evaluation of obstruction
What are 3 things that might cause obstruction?
- Stone
- Blood clot
- Tumor
What can IVP/IVU identify with regards to obstruction?
It’s level and the nature of the obstruction
What can distortion of the collecting systems be?
A secondary indication of a renal mass
Is a IVP good to identify a renal mass?
No, it is more effectively evaluated with other imaging modalities: CT and US
What is the initial screening exam for a patient with suspected renal pathology?
Abdominal plain film (KUB)
What are renal contours relatively well defined by in a KUB?
Adjacent fatty tissue in the perinephric space
True or False: KUB can help identify the contour of the urinary bladder?
FALSE
What is the prime utility of plain film radiography?
To identify calcifications or stones
What % of urinary tract calculi are calcified and generally visualized with plain film radiograph?
85%
What are calcification in pelvis typically?
They are frequently of vascular origin (phleboliths)
When is a retrograde pyelogram performed and who does it?
This is usually done in conjunction with cystoscopy and this is performed by a urologic surgeon
What is done in a retrograde pyelogram?
The distal portion of the ureter is catheterized and contrast is administered in a retrograde manner
When is a retrograde pyelogram particularly useful?
In the evaluation of kidneys which are non-functional or completely obstructed
What is a useful non-inasive imaging modality that uses high frequency sound waves to produce images of internal structures of the body?
Sonography
True or False: Kidneys are typically well demonstrated by US?
True
What part of the kidneys is US the most useful in evaluating?
The collecting systems
What is US helpful for screening?
Obstruction (hydronephrosis)
What is US an excellent assessment for?
Evaluation of renal mass (cyst v. solid)
What is the single most helpful examination of the kidney?
CT
When you do CT for a kidney, do you give IV contrast?
You usually do the scan before and after the administration of IV contrast
What is quite useful in the acute setting for evaluating the patient with suspected urinary obstruction secondary to a stone or calculi?
An unenhanced CT with helical aquisition
What is enhanced CT critical for?
The evaluation of renal masses, trauma, or infection
What can be utilized for guidance for subsequent interventional procedures such as drainage and biopsy?
US and CT
What is the exam that utilizes radioactive agents injected into the blood stream and subsequently accumulated by the kidney?
Nuclear Medicine (Scintigraphy)
What kind of exam is nuclear medicine?
It is primarily a functional exam
What is an invasive exam that is most useful for the evaluation of the renal arteries (and less commonly the veins)?
Renal angiography
Why are applications of MRI limited?
Cost
True or False: MRI is no more specific than CT in regards to evaluating a renal mass?
True
What does MRI have some potentially broader applications in?
Staging a renal mass with potential vascular involvement
What are the major components of the urinary system?
- Kidneys
- Intrarenal collecting structures
- Renal pelvis
- Ureters
- Urinary bladder
- Urethra
What are the kidneys located within?
A cone of renal fascia (Gerota’s fascia) surrounded by the fat in the perirenal space
What makes up the kidney?
Lobes that consist of pyramidal shaped medulla surrounded by cortex
What does the cortex consist of?
Proximal and distal convoluted tubules and the accompanying blood vessels
Where are the peripheral and septal cortex located?
- The peripheral cortex is immediately beneath the renal capsule
- The septal cortex extends down between the pyramids as the columns of Bertin
What can occasionally simulate a renal mass?
The columns of Bertin
What do the medullary pyramids consist of?
Collecting tubules and the long, straight portions of the loops of Henle as well as the accompanying blood vessels
What is the apex of the pyramids directed at?
The renal sinus (ant is projects into the calyces)
Are renal arteries single or multiple?
Either
What vertebral level to the renal pedicles lie at?
L1-L2 (adjacent to spine)
What is the typical sagittal diameter of an adult kidney?
9-12 cm
What does the collecting system in each kidney consist of?
Calyces and renal pelvis
How many calyces per kidney?
Usually 8-12
What shape are the calyces?
Cup-shaped
What do the ureters do?
Conduct urine from the renal pelvis to the urinary bladder
Where do the ureters lie?
In the retroperitoneal space medially, anterior to the psoas muscle
How many ureters per kidney?
Usually 1, but duplications can occur
What can result in a dilation or ureterocele?
Abnormal insertion of the distal ureter into the urinary bladder
(These can occur in aberrant locations and lead to obstruction or reflux
What do the kidneys derive from?
Metanephros and the ureteric bud
What kind of abnormalities are the kidneys subject to?
Migration, rotation, fusion
What is the most common renal anomaly?
Horseshoe kidney (occurs in less than 1% of the population)
What does horseshoe kidney result in?
Abnormal orientation with fusion of the lower poles across the midline
What is it called when both kidneys lie on one side of the abdomen with one ureter typically coursing across the midline?
Cross-fused ectopia
What is it called when a kidney is located in the upper pelvis, typically in iliac fossa?
Pelvic kidney
What are 2 other anomalies mentioned with the kidney?
Agenesis and hypoplasia
What % of renal stones contain calcium?
85%
How are a vast majority of stones detected?
On plain film or CT
What is the favored imaging modality for stones?
Helical CT
What does helical CT do?
It serves to identify the stones as well as associated obstruction
What testing needs to be done for uric acid stones?
CT, they are radiolucent on plain film
What is a deposit of precipitated calcium which fills all or part of the collecting system of the kidney?
Stag-horn calculus
What do stag-horn calculi result from?
Chronic infection or low grade to moderate obstruction
What is a disorder where there is dilatation of the renal tubules (ectasia) and tiny calculi form in these tubules and can be discharged into the collecting system causing intermittent obstruction or pain
Medullary sponge kidney
In medullary sponge kidney, whit size stones may not pass through the UV junction without intervention?
Stones larger than 4-5mm
What do stones need to pass spontaneously?
Good hydration and analegesia
What is a method of fragmenting calculi nonsurgically?
Extracorporal Shock Wave Lithotripsy
How does ESWL work?
A shock wave is created outside of the body and focused onto the stone using parabolic reflectors and targeting device…this may disrupt the stone into smaller pieces that can pass spontaneously
What can cause increased pressure within the collecting system and ultimately result in impaired renal function?
Obstruction of the ureter
What needs to be done to preserve renal function with obstruction?
Relieve it ASAP!
How is an obstruction typically relieved?
By the urologist using a retrograde approach from the urinary bladder
How are percutaneous approaches for relieving obstruction done?
- By a radiologist with US or CT guidance
- Catheter is placed into the collecting system and ultimately can be directed through the obstructed segment of the ureter into the urinary bladder to provide for contained internal drainage
What are the most common causes of obstruction?
Stones and neoplasm
What can occur as a result of prior surgical intervention?
Iatrogenic obstruction
What occurs typically as the result of atherosclerosis?
Stenosis or obstruction of the renal arteries
What is an alternative cause of stenosis or obstruction of the renal arteries?
Fibromuscular dysplasia
What is the most sensitive modality for evaluation of renal artery stenosis?
Angiography
What is angiography typically performed with?
MR and CT (MRA or CTA)
What happens if a functional stenosis is identified on angiography?
Interventionally is can be relieved with either a balloon catheter or metallic stent
What happens of a renal artery stenosis cannot be relieved?
It will ultimately lead to continued, impaired renal function and atrophy
Why are the kidneys prone to infection?
Because of their filtering function
What can be involved in infection in the renal system?
They kidney itself or the perinephric space
What can be done if a focal collection occurs (abscess)
It can be drained percutaneously
How are renal infections normally treated?
With medical (antibiotic treatment)
What can chronic, long standing infections lead to?
Impaired renal function…it can spread to other spaces in the abdomen
What are the 2 types of renal trauma?
Blunt or pentrating
Where can damage from trauma occur?
To the kidney itself, as well as the collecting system or vessels
What is the most useful imaging modality in the acute setting for the kidney?
CT
What is of less use in kidney trauma?
Angiography
What is really common in the kidney, occurring in 50% of the adult population over 50?
Renal masses (especially cysts) -The cysts can become quite large
When is intervention indicated in renal masses?
Only if there are symptoms such as pain or clinical findings
What can renal masses occasionally lead to?
HTN
What is the most useful imaging modality in the initial setting for renal masses?
US
What else can be helpful in discriminating renal masses?
CT
What is an AD inherited condition in which many of the DCT end blindly and aren’t connected to the collecting system?
Adult polycystic kidney disease
What is the result of adult polycystic kidney disease?
Gradual formation of multiple cysts of variable size throughout the kidney
What other organs can be involved in adult polycystic kidney disease?
Liver and pancreas
What occurs later in life in adult polycystic kidney disease?
Renal failure
What do adult polycystic kidney disease patients have an increased incidence of?
Other conditions like intacranial aneurysm
What is problematical in the kidney?
Solid and complex cystic masses
What is the most malignant lesion?
Renal cell carcinoma
What can kidney tumors present with?
Pain and hematuria
When do you ideally want to identify renal tumors?
When they are small and resectable
What kind of lesion is renal cell carcinoma?
An aggressive lesion
What can renal cell carcinoma spread to?
Other organs, the renal vein, and IVC
What is a relatively benign neoplasm which typically has fatty elements within it and can bleed spontaneously?
Angiomyolipoma
If metastatic disease to the kidney common?
No
What kind of infiltrative tumors can occur in the kidney?
Lymphoma or leukemia
What is a benign renal neoplasm which may demonstrate a central scar?
Oncocytoma
What must be excluded in acute renal failure and how is this best done?
Obstruction, sonographically
What is another test that can prove useful in evaluating the level of renal function?
Scintigraphy (nuclear medicine)
With renal failure, what does imaging have to offer?
Little other than excluding readily treatable causes (it can be a mechanism to direct renal biopsy)
What is renal imaging done in conjunction with?
Clinical findings and laboratory data
What is renal imaging a tool in?
The armamentarium of diagnosis
What is the primary goal of imaging and intervention?
To prevent renal function and direct patient care
