Radionuclide Evaluation of the Genitourinary System

Play an AI-generated podcast conversation about this lesson

Which of the following is NOT a primary mechanism of the excretory function of the kidneys?

Passive filtration through the glomeruli

Ultrafiltration across the Bowman's capsule (correct)

Reabsorption of substances by the tubules

Active secretion by the tubules

According to the passage, what percentage of renal plasma flow is cleared by glomerular filtration?

20% (correct)

40%

10%

30%

Based on the information provided, which of the following imaging techniques is primarily used for evaluating renal anatomy?

Angiography

Computed tomography (CT)

Magnetic resonance imaging (MRI) (correct)

Radionuclide scanning

Which of the following is NOT mentioned as an indication for radionuclide scanning in the text?

Evaluation of renal artery stenosis Signup and view all the answers

According to the passage, what percentage of renal plasma flow is cleared by tubular secretion?

80% Signup and view all the answers

Which of the following imaging modalities is NOT mentioned in the passage as being widely used for evaluating renal anatomy?

Positron emission tomography (PET) Signup and view all the answers

Which of the following is NOT a reason for omitting the renal perfusion phase of the renal scan?

To contribute more to the functional assessment Signup and view all the answers

What is the typical duration of the renal parenchymal function phase imaging?

20-30 minutes Signup and view all the answers

What is the purpose of administering the diuretic furosemide (Lasix) during the collecting system phase of the renal scan?

To facilitate transit of activity from the renal pelvis and ureters to the bladder Signup and view all the answers

What is the purpose of obtaining postvoid or postambulation images during the collecting system phase of the renal scan?

To enhance collecting system drainage Signup and view all the answers

What is the typical time frame for the classic renogram curve using tubular secretion radiopharmaceuticals like 99mTc-MAG3?

0-30 minutes Signup and view all the answers

What is the purpose of the aortic region of interest in the renogram analysis?

To assess the discreteness and adequacy of the injected bolus, as well as relative renal perfusion Signup and view all the answers

What is the typical duration of the initial renal perfusion or vascular transit phase of the renogram curve?

30-60 seconds Signup and view all the answers

Which of the following is NOT a typical finding in the normal renogram curve using a tubular secretion radiopharmaceutical like 99mTc-MAG3?

The kidneys appear larger on the early images compared to the later images Signup and view all the answers

Which of the following is NOT one of the three phases of the normal computer-generated renogram curve using a tubular radiopharmaceutical?

Bladder filling phase Signup and view all the answers

What is the purpose of the background subtraction regions of interest in the renogram analysis?

To subtract the activity in the surrounding tissues from the kidney regions of interest Signup and view all the answers

What is the purpose of scaling the graphical axes differently during renography?

To evaluate the renal peak activity during the perfusion phase Signup and view all the answers

Which phase of renography is characterized by a down slope of the curve due to excretion of the radiopharmaceutical from the kidney?

Clearance or excretion phase Signup and view all the answers

What may occur in a renogram curve if a patient is dehydrated during the renography?

Delayed peak activity Signup and view all the answers

What is a common indicator used for quantitative assessment of renal function in radionuclide techniques?

Half-time excretion Signup and view all the answers

In normal renograms, what is considered a normal value for the time to peak activity (Tmax)?

Within 5 minutes after injection Signup and view all the answers

What renal function measure involves expresssing clearances as volume of plasma?

$GFR$ and $ERPF$ Signup and view all the answers

Why should patients be well hydrated before a functional renal imaging examination?

To enhance the visualization of renal excretion during the procedure Signup and view all the answers

What is the purpose of administering furosemide during functional renal imaging?

To induce diuresis and overcome fixed anatomic obstructions Signup and view all the answers

Why is it important to empty the bladder before administering furosemide during the examination?

To reduce the risk of a false appearance of obstruction Signup and view all the answers

In patients who cannot empty their bladders, what intervention may be used during the examination?

Perform a bladder catheterization Signup and view all the answers

What is the role of real-time visual inspection in functional renal imaging?

Identifying when the collecting systems are full Signup and view all the answers

Why is the timing of furosemide injection considered critical during functional renal imaging?

To determine when the collecting systems are full Signup and view all the answers

Which of the following radiopharmaceuticals is primarily excreted through tubular secretion?

99mTc-DMSA Signup and view all the answers

What percentage of the injected dose of 99mTc-glucoheptonate remains bound to the renal tubules?

15% Signup and view all the answers

Which of the following statements about 99mTc-DMSA is NOT true?

It is primarily excreted in the urine during the first several hours. Signup and view all the answers

What is the primary purpose of using 99mTc-DTPA in renal evaluation?

Evaluating glomerular filtration function Signup and view all the answers

Which of the following statements about 99mTc-glucoheptonate is true?

It is stable and may be used for up to 5 hours after preparation. Signup and view all the answers

What is the approximate percentage of the injected dose of 99mTc-DMSA concentrated in the renal cortex at 6 hours?

40% Signup and view all the answers

Which of the following radiopharmaceuticals requires delayed images 1 to 3 hours after injection in patients with poor renal function?

99mTc-DMSA Signup and view all the answers

What is the primary advantage of using 99mTc-glucoheptonate over 99mTc-DMSA for renal imaging?

It allows for the assessment of renal perfusion and evaluation of the renal collecting systems and ureters. Signup and view all the answers

Which of the following statements about the glomerulus is true?

It acts as a semipermeable membrane, allowing only small molecules to pass through. Signup and view all the answers

What is the typical adult administered activity of 99mTc-glucoheptonate for renal evaluation?

8 mCi (296 MBq) Signup and view all the answers

What is the main purpose of diuretic renography?

To distinguish obstructive from nonobstructive conditions Signup and view all the answers

Why is 99mTc-MAG3 preferred over 99mTc-DTPA in renography?

It excretes primarily by tubular secretion Signup and view all the answers

What characterizes a classic acute or sub-acute high-grade obstructive renogram curve?

Steeply rising continuous arched curve with well-defined excretion downsloping Signup and view all the answers

In patients with nonobstructive hydronephrosis, which part of the urinary system might not reach sufficient pressures during imaging?

Ureteropelvic junction Signup and view all the answers

What type of activity curve is expected in post-diuretic renography for a patient with functional obstruction?

Continuous rising curve Signup and view all the answers

What does the peak aortic activity represent in renography?

Renal blood flow during the first minute Signup and view all the answers

What radiopharmaceutical is the agent of choice for renography in suspected obstructive hydronephrosis?

^99^mTc-MAG3 Signup and view all the answers

What is the main benefit of using diuretic renography?

Measuring ureteral pressure Signup and view all the answers

Which imaging technique is used to distinguish obstructive collecting system dilatation from nonobstructive hydronephrosis?

^99^mTc-MAG3 scan Signup and view all the answers

What is the normal 20-minute maximal cortical ratio for 99mTc-MAG3?

0.19 Signup and view all the answers

Which radiopharmaceutical is primarily used for the calculation of PAH clearance and ERPF?

99mTc-MAG3 Signup and view all the answers

How is the GFR defined using radiopharmaceutical analogs?

By the clearance of insulin Signup and view all the answers

What is used to estimate ERPF for tubular agents like 99mTc-MAG3?

Single, timed blood sample obtained about 45 minutes after injection Signup and view all the answers

Which method of determining GFR and ERPF involves plasma sample-based clearances?

Plasma sample-based clearances Signup and view all the answers

Why are camera-based clearances not as accurate as plasma sample-based clearances?

Because they don't use blood or urine samples Signup and view all the answers

Which radiopharmaceutical is used for insulin clearance and GFR estimation?

^99mTc-DTPA Signup and view all the answers

What role do computer-derived clearance values play in camera-based clearances?

They simplify corrections for patient and acquisition variables Signup and view all the answers

'Effective' in the term 'effective renal plasma flow' means what?

Different from PAH clearance Signup and view all the answers

How is MAG3 clearance expressed as a renal functional measurement?

Through both single plasma sample-based and camera-based techniques Signup and view all the answers

Which of the following imaging techniques is primarily used for evaluating space-occupying lesions, functioning pseudotumors, or edema/scarring associated with acute or chronic pyelonephritis in the renal cortex?

Renal cortical imaging with 99mTc-DMSA or glucoheptonate Signup and view all the answers

In patients with acute tubular necrosis (ATN), what pattern is typically observed on a renogram with 99mTc-MAG3?

Bilateral persistent nephrograms with rising renogram curves Signup and view all the answers

Which of the following statements regarding acute renal vein thrombosis is true?

There is decreased or absent perfusion and delayed, diminished accumulation and excretion of 99mTc-MAG3 Signup and view all the answers

What is the primary advantage of radionuclide imaging techniques over structural imaging methods like ultrasonography in evaluating urinary tract obstruction?

Radionuclide imaging can depict urodynamics and functional information Signup and view all the answers

In cases of acute high-grade urinary tract obstruction, what pattern is typically observed on a routine radionuclide renogram?

A rising renogram curve with persistent nephrogram Signup and view all the answers

Which of the following imaging modalities is considered the procedure of choice for evaluating renal artery occlusion, avulsion, or stenosis?

Computed tomography (CT) Signup and view all the answers

In the evaluation of diffuse renal diseases like acute pyelonephritis or chronic glomerulonephritis, what is the typical finding on radionuclide imaging?

Unilaterally or bilaterally poor vascular perfusion and poor radiopharmaceutical excretion Signup and view all the answers

Which of the following imaging findings in acute tubular necrosis (ATN) is associated with a favorable prognostic outcome?

Reasonably good visualization of the kidneys Signup and view all the answers

What is the purpose of using a pinhole or high-resolution collimator, or single-photon emission computed tomography (SPECT) in renal cortical imaging?

To improve spatial resolution and visualization of the renal cortex Signup and view all the answers

In the evaluation of acute pyelonephritis, what is the typical finding on a posterior perfusion image obtained after intravenous administration of technetium-99m mertiatide?

Decreased perfusion to the affected kidney Signup and view all the answers

Which of the following statements about the glomerular filtration rate (GFR) and DTPA is correct?

The normal GFR is 125 mL/min, and DTPA tends to underestimate the GFR slightly due to 5-10% protein binding. Signup and view all the answers

What is the primary mechanism of clearance for the radiopharmaceutical agent MAG3 (mercaptoacetyltriglycine)?

Tubular secretion (>95%) Signup and view all the answers

Which of the following statements about the extraction fraction of DTPA and MAG3 is true?

MAG3 has a higher extraction fraction than DTPA, allowing for better renal visualization. Signup and view all the answers

Which of the following statements about the typical administered activity for DTPA and MAG3 in adults is correct?

For both DTPA and MAG3, the typical administered activity is 10 mCi (370 MBq) or less. Signup and view all the answers

Which of the following statements about the renal perfusion phase of functional renal imaging is correct?

Renal perfusion is evaluated from the posterior projection for native kidneys and the anterior projection for transplant kidneys. Signup and view all the answers

Which of the following statements about the imaging agent used for the renal perfusion phase is correct?

A small bolus of high-activity (10 mCi [370 MBq]) 99mTc-labeled radiopharmaceutical (99mTc-DTPA or 99mTc-MAG3) is injected intravenously. Signup and view all the answers

Which of the following is a potential pitfall in interpreting the renal perfusion phase?

The spleen may overlie the left kidney, giving a false impression of asymmetrically increased left renal perfusion or a 'phantom kidney' in patients with prior left nephrectomy. Signup and view all the answers