Imaging of the Urinary Tract

Question 1

What does KUB stand for in medical imaging?

Answer 1

KUB stands for kidneys, ureters, and bladder. It refers to an X-ray imaging technique that allows visualization of these structures.

Question 2

How is a KUB different from an AXR (abdominal X-ray)?

Answer 2

A KUB is essentially the same as an AXR but includes the symphysis pubis at the bottom of the X-ray image. This positioning is important for proper visualization of the urinary tract structures.

Question 3

What can be visualized on a KUB X-ray?

Answer 3

A KUB X-ray, depending on the bowel contents (gas or feces), allows visualization of the kidneys and bladder. It can also be used to identify stones in the urinary tract.

Question 4

What does IVU stand for in medical imaging?

Answer 4

IVU stands for intravenous urography. It is a radiographic technique that uses a contrast agent injected intravenously to visualize the urinary tract.

Question 5

How is the IVU technique commonly used now in clinical practice?

Answer 5

The use of IVU is limited in current clinical practice, as it has been largely replaced by CT (computed tomography) imaging.

Question 6

What is the purpose of using contrast agent in IVU and CT?

Answer 6

Both IVU and CT imaging techniques use contrast agents to enhance the visualization of structures. Contrast agents help highlight specific areas or organs of interest in the images.

Question 7

Why is CT preferred over IVU for general overview of abdominal organs?

Answer 7

CT provides a more comprehensive and detailed overview of the abdominal organs compared to IVU. It offers better visualization and can detect a wide range of abnormalities or conditions.

Question 8

According to NICE guidelines, when should low-dose non-contrast CT be offered?

Answer 8

NICE guidelines recommend offering urgent (within 24 hours of presentation) low-dose non-contrast CT to adults with suspected renal colic. Renal colic refers to severe pain caused by the passage of kidney stones.

Question 9

Why is CT considered the best imaging modality for detecting stones in the urinary tract?

Answer 9

CT imaging is highly sensitive and accurate in detecting stones in the urinary tract. It provides detailed and precise information about the location, size, and composition of the stones, which aids in treatment planning and management.

Question 10

What are the advantages of CT imaging for the urinary tract compared to plain X-ray?

Answer 10

CT imaging is more sensitive in detecting small calculi (stones) in the urinary tract compared to plain X-ray. Calculi may not be visible on a plain X-ray but can be clearly seen on a CT scan.

Question 11

What is a CT urogram or CT IVU used for?

Answer 11

A CT urogram or CT IVU (intravenous urogram) is a contrast-enhanced CT scan used to assess and review masses, stage renal tumors, evaluate renal trauma, and assess the renal vasculature. It provides detailed images of the kidneys, renal medulla and cortex, ureters, and surrounding abdominal organs.

Question 12

How is contrast administered in a CT urogram?

Answer 12

Contrast is administered via an injector pump through veins in the antecubital fossa during a CT urogram.

Question 13

What does a CT urogram enhance and demonstrate?

Answer 13

A CT urogram enhances the kidneys via contrast agent and demonstrates the renal medulla, cortex, and ureters. It also allows for assessment of surrounding abdominal organs and can produce a set of 3D images.

Question 14

What is shown in an axial CT slice through the kidneys?

Answer 14

In an axial CT slice through the kidneys, the slice is at the level of the hilum of the left kidney. The left renal vein is seen entering the inferior vena cava. The renal hila (the indented part where vessels enter or exit) face anteriorly and medially. The renal cortex appears bright due to the contrast agent.

Question 15

How is the left kidney oriented in a sagittal CT slice?

Answer 15

In a sagittal CT slice of the left kidney, the kidney has an oblique orientation. The upper pole of the kidney lies more posteriorly than the lower pole.

Question 16

Why is MRI of the urinary tract less commonly undertaken compared to other imaging modalities?

Answer 16

MRI of the urinary tract is less commonly undertaken due to cost and availability factors. It may not be as readily accessible as other imaging modalities

Question 17

What are the clinical applications of renal MRI?

Answer 17

Renal MRI is useful for assessing masses that are indeterminate on CT or ultrasound (US). It can also be used to stage bladder cancers, prostate cancers, or to assess narrowing of renal arteries. It is particularly beneficial for patients with reduced kidney function or contrast allergies.

Question 18

What are the clinical applications of MRI of the prostate?

Answer 18

MRI of the prostate is primarily used to detect prostate cancer. It can also help stage prostate cancer once it has been diagnosed and check for recurrence of cancer. The detailed imaging provided by MRI allows for precise evaluation of the prostate gland, surrounding soft tissues, and bones.

Question 19

How is renal MR angiography (MRA) used and what are its advantages?

Answer 19

Renal MRA is used to look for narrowing of the renal arteries, which can cause hypertension. It can be performed as a contrast-enhanced or non-enhanced technique. The advantages of renal MRA include being minimally invasive, radiation-free, and providing 3D acquisition for detailed visualization of the renal arteries.

Question 20

What is percutaneous nephrostomy, and when is it used?

Answer 20

Percutaneous nephrostomy is a procedure in which the kidney is accessed through the skin using a percutaneous approach. It is performed when other access to the kidney is unsuccessful due to obstruction of the urinary tract. It allows drainage of urine through a catheter.

Question 21

What is a micturating cystogram and its purpose?

Answer 21

A micturating cystogram is a procedure where the bladder is filled with a contrast medium, and the patient is then asked to void (urinate) while undergoing fluoroscopy screening. This procedure is used to check for reflux of urine into the ureters and can also assess for urethral abnormalities.

Question 22

What is the role of ultrasound in imaging the urinary tract?

Answer 22

Ultrasound is frequently used as the first-line investigation for imaging the urinary tract. It allows for the visualization of various structures within the kidneys, as different tissues have different echogenicity (ability to reflect ultrasound waves). It is particularly useful for detecting kidney stones, which appear as an acoustic shadow. However, it is worth noting that small stones may not always be clearly demonstrated on ultrasound.

Question 23

What are the advantages of ultrasound in imaging the urinary tract?

Answer 23

Some advantages of ultrasound in imaging the urinary tract include its non-invasive nature, absence of ionizing radiation, and real-time imaging capabilities. It is also widely available and relatively cost-effective.

Question 24

Besides the kidneys, what other structures can be visualized using ultrasound in the urinary tract?

Answer 24

In addition to the kidneys, ultrasound can visualize structures such as the bladder, ureters, and prostate gland (in males). It can provide valuable information about the size, shape, and position of these structures.

Question 25

How does ultrasound help in evaluating kidney stones?

Answer 25

Ultrasound can identify the presence of kidney stones by visualizing their acoustic shadow. However, it is important to note that small stones may not be clearly visible on ultrasound, and additional imaging techniques like CT or intravenous urography may be necessary for a more comprehensive evaluation.

Question 26

What are some limitations of ultrasound in imaging the urinary tract?

Answer 26

Although ultrasound is useful for initial assessment, it has some limitations. It may not provide detailed visualization of the entire urinary tract, and small or non-obstructing stones may be missed. In certain cases, additional imaging modalities such as CT or MRI may be required for a more comprehensive evaluation.