ct urology ppt

1. CT UROGRAPHY & MR
UROGRAPHY
Presentor : Dr. Vijmohanreddy (Jr-1)
Date:05.04.2024

2. INTRODUCTION
• Computed Tomography Urography (CTU) is defined as an abdominal multiphase
CT examination optimized for imaging kidneys, ureter, and bladder, including
post-contrast excretory phase imaging.
• CT urography has emerged as the primary imaging modality for evaluating the
urinary tract in various clinical settings.
• CT urography not only allows detailed assessment of the urinary tract but also
enables direct visualization of adjacent structures and comprehensive evaluation of
the abdomen and pelvis.

3. INDICATIONS
1. Evaluation of Hematuria.
2. Staging and follow-up for urothelial malignancy.
3. Urinary calculus disease.
4. Suspected pelvis or ureteral obstruction.
5. Congenital anomalies of kidney and ureter.
6. Urinary tract trauma.
7. Pre operative assessment in kidney donors.
8. Post operative urinary tract anatomy.

4. CONTRAINDICATIONS
The patients in whom this procedure is contraindicated are as follows:
1. Allergy to contrast agents.
2. Renal insufficiency.
3. Pregnant patients.

5. IMAGING PROTOCOL
• There are different acquisition and contrast administration protocols for CT
urography. These include –
1. Triple phase single bolus technique.
2. Dual-phase split bolus technique.
3. Single-phase triple bolus technique.
4. Single-phase Dual-Energy CT

6. Triple phase single bolus technique
• This is the most widely used scanning protocol for CT urography.
• This study technique includes following steps –
1. Acquisition of a non-contrast phase.
2. Intravenous contrast injection as a single bolus.
3. Acquisition of the cortico-medullary phase 30 to 40 s after bolus (optional).
4. Acquisition of the nephrographic phase 80 to 120 s after bolus.
5. Acquisition of delayed excretory phase 5 to 15 min after bolus.

7. Triple phase single bolus technique

8. Corticomedullary phase
• The advantages of the acquiring corticomedullary phase are –
1. Precise vascular and perfusion information.
2. Better characterization of renal cortical masses.
3. Detection of hyper vascular metastases.
• Corticomedullary phase is also characterized by a higher sensitivity for the
detection of bladder tumors than either the nephrographic or excretory phases
alone.
• However this phase is usually omitted because the small added benefit does not
justify the increased dose.

9. Nephrographic phase
• The nephrographic phase, also known as the nephrogenic phase or the renal
parenchymal phase, is a post contrast injection time range in which there is an
optimal enhancement of the renal parenchyma including the medulla.
• Nephrogenic enhanced images are useful for the evaluation of renal parenchyma
especially in detection and evaluation of renal neoplasm, parenchymal scarring
and renal inflammatory disease.

10. Excretory phase
• The excretory phase also known as the urographic phase is a post contrast
injection time range in which there is an optimal enhancement of the renal
collecting systems.
• Excretory phase imaging allows the detection of urothelial cancer , Para pelvic
cysts, calyceal diverticula and urinary extravasation after renal trauma.

11. Limitations of single bolus technique
• Since three or four distinct image acquisitions are performed, this technique results in the
highest ionizing dose to the patient.
• The acquisition timing can vary for each phase, particularly for the nephrographic and
delayed excretory phases. Images acquired too early, before the cortex and medulla are
uniformly opacified can limit image interpretation, whereas images acquired too late will
detect the early excretion of contrast into the collecting system, hiding mucosal
enhancement within the renal pelvis.
• A timing delay should be considered in patients with impaired renal function and known
dilatation of the excretory system. In these cases, an excretory phase performed in a
prone position can help the distension and opacification of the urinary tract.

12. Dual-phase split bolus technique
• This study technique includes following steps –
1. Acquisition of a non-contrast phase.
2. First intravenous contrast agent injection (first bolus)
3. Second intravenous contrast agent injection after 5–15 min (second bolus)
4. Acquisition of a combined nephrogenic and excretory phase (2–5 min after the
second bolus)

13. Dual-phase split bolus technique

14. Limitations of split bolus technique
• The main disadvantage of split bolus technique is a lower contribution of contrast
medium to kidney enhancement and to distension and opacification of the urinary
collecting system, which may reduce image quality and sensitivity for the
detection of small renal cell carcinomas and subtle transitional cell carcinomas.

15. Single phase triple bolus technique
• This study technique includes following steps -
1. First intravenous contrast agent injection (first bolus).
2. Second intravenous contrast agent injection after 5–15 min (second bolus).
3. Third intravenous contrast agent injection after 100 s (third bolus).
4. Combined cortico-medullary, nephrogenic, and excretory phase acquired 25 s
after the third bolus

16. Single phase triple bolus technique

17. Single-phase Dual-Energy CT
• This study technique includes following steps –
1. Single bolus (or split bolus) contrast agent injection
2. Single excretory phase (often 80 and 140 kVp)
3. Post processing to generate virtual non contrast enhanced image
• DECT reduces the radiation exposure due to decomposition analysis which generates
virtual non-contrast CT images by separating iodine from soft tissue and water.
• DECT also allows the reduction of the contrast medium dose by using low-energy mono
energetic beams. This is especially useful in patients with a pre-existing renal impairment
and a higher risk of contrast-induced nephropathy.

18. Optimization of excretory phase
• To achieve adequate distension and whole opacification of the urinary tract in a
single excretory phase, ancillary techniques have been proposed. These techniques
include –
1. oral or intravenous hydration before the acquisition.
2. intravenous furosemide administered before the intravenous contrast material.
3. use of abdominal compression devices (belts).
4. prone patient positioning.

19. INTRODUCTION
• MR Urography (MRU) is a specialized MRI study used to evaluate the renal parenchyma,
pelvi-calyceal system, and the entire urinary tract in a single imaging session. It is a non-
invasive imaging technique that provides detailed anatomical and functional information
about the kidneys and urinary system.
• MR Urography has evolved into a comprehensive evaluation tool that combines
anatomical imaging with quantitative functional parameters to assess renal function and
detect abnormalities such as congenital anomalies, urinary tract obstructions, and renal
malformations.

20. This imaging modality utilizes dynamic contrast-enhanced MR acquisitions to visualize the
perfusion, concentration, and excretion of contrast agents, allowing for both qualitative and
quantitative assessment of renal function.
MR Urography plays a crucial role in diagnosing renal diseases, monitoring disease
progression, guiding treatment decisions, and evaluating the response to interventions in both
adults and children.

21. There are two types of MR urography:
1. Static fluid urography:- In the dilated or obstructed urinary tract there is presence
of hydronephrosis and hydro-ureter. As there is presence of fluid, heavily T2 weighted
sequences will b helpful in visualizing the fluid containing parts, viz., kidney, ureter and
bladder.
2. Excretory MR Urography: In this procedure an intravenous injection of MR contrast
media is given. The kidney then starts excreting the contrast. MR imaging of kidney,
ureter and bladder is obtained as per the excretion period. This technique requires
normally functioning kidney, hence if renal functions are deteriorated this technique can
not be used.
Diuretic administration is an important factor for MR urography to get better visualization

22. PRINCIPLE
• Urinary tract can be evaluated in two ways: by T2-w images with high TE and by T1-
w images with excreted contrast in the collecting system.
• T2-w imaging is useful in visualisation of a dilated system though visualisation of a
normal collecting system can be improved by intravenous hydration and diuretic
injection.
• For non-dilated collecting, excreted IV contrast is useful but requires functioning
renal system.
• A complete MRU is usually combination if both T1 and T2-w imaging and functional
evaluation on dynamic post-contrast images.

23. INDICATIONS
1. Demonstrating the Urinary System: MR Urography is utilized to visualize and assess
the urinary system comprehensively, providing detailed anatomical information.
2. Urolithiasis and Urinary Tract Obstruction Unrelated to Urolithiasis [Benign
strictures of the ureter may complicate abdominal and pelvic inflammatory processes
(eg, appendicitis, Crohn disease, endometriosis), infection (eg, tuberculosis), radiation
therapy, surgical or interventional procedures, or stone disease).
3. Detecting Congenital Abnormalities: MR urography can be used to evaluate patients
with absent kidney, abnormally positioned or rotated kidney, renal duplication, renal
dysplasia, ectopic ureter, retrocaval ureter, primary megaureter, or UPJ obstruction.

24. 4. Evaluation of Renal Transplant Donors: This imaging modality can be used to assess
potential renal transplant donors, providing crucial information about the renal anatomy and
function.
5. Paediatric Applications: In paediatric patients, MR Urography is valuable for evaluating
urinary tract issues, congenital anomalies, and monitoring disease progression.
6. Haematuria.
7. Renal insufficiency.
8.Pre and Post operative assessment.

25. PATIENT PREPARATION
• Having patients void prior to entering the imager improves their
comfort and prevents interruption of the study at an inopportune time.
If no contraindications (eg, fluid restriction, congestive heart failure)
exist, our patients are given 250 mL of normal saline solution
intravenously at the start of imaging. Bowel contents are often bright
with the T1- and T2-weighted sequences used for MR urography. Use
of oral negative contrast agents are helpful in reducing the signal
intensity of bowel contents, although the use of such agents is not
required for MR urography. In most cases, imaging can be performed
successfully with the patient supine.

26. TECHNIQUE
• Patient is started on intravenous ringer lactate (10 ml/ kg) 30 minutes before the scan.
Intravenous furosemide (1 mg/Kg) is injected approximately 15 minutes before the
gadolinium injection.
• During these 15 minutes routine anatomical T1- and T2-w images of the kidneys and bladder
are acquired followed by 3D MRU (a heavily T2-w 3D FSE same as 3D MRCP) covering
kidneys, ureters and the bladder.
• Next, multiple runs of coronal oblique (along long axis of kidneys and ureters) T1-w 3D GRE
(VIBE/THRIVE/LAVA) are acquired during dynamic intravenous injection of routine dose of
gadolinium-based contrast media. The dynamic runs are continued till complete opacification
of distal ureters and the bladder.

27. POST-PROCESSING
• The 3D MRU and post-contrast T1-w images can be reformatted in
various planes using methods like MIP, MPR and VRT. The post-
contrast images can be processed using various functional assessment
software that are available free of cost on the internet.
• The functional information obtained includes differential renal
function, renal transit time, time to excrete and symmetry between two
kidneys.

28. ADVANTAGE OVER CT-UROGRAM
• Non-Invasive Nature: MRU is a non-invasive technique that does not
involve exposure to ionizing radiation, making it safer for patients,
especially those at risk for kidney damage.
• Contrast Administration: MRU can be performed without contrast
administration using static-fluid T2-weighted sequences or with
contrast for excretory imaging, providing flexibility in imaging
options.

29. • Detection Accuracy: MRU has shown higher accuracy in detecting
obstruction and hydroureteronephrosis compared to CTU, making it a
preferred choice for evaluating these conditions.
• Visualization of Pathology: MRU is better at visualizing the excretory
tract in obstructed and impaired kidneys, offering detailed images of
both non-dilated and obstructed collecting systems.

30. CONTRAINDICATIONS
• Allergy to Contrast Media: A history of allergic-like reactions to
contrast media can significantly increase the risk of adverse reactions
during MR Urography.
• Asthma: Patients with a history of asthma may have a higher
likelihood of developing a contrast reaction during the procedure.
• Cardiac Status: Patients with specific cardiac conditions may have
contraindications to the use of contrast material during MR Urography.

31. Pregnancy: A positive pregnancy test is an absolute contraindication to MR Urography due to
potential risks associated with contrast agents and imaging procedures.
Risk vs Benefit Assessment: Patients with a predisposition to allergic reactions or those at
higher risk of severe anaphylaxis related to contrast media should carefully consider the risks
versus benefits before undergoing MR Urography.
Pre-existing Conditions: Individuals with certain medical conditions or risk factors that may
be exacerbated by contrast agents or specific imaging techniques should be evaluated for
suitability before proceeding with MR Urography.

32. INTRAVENOUS CONTRAST MATERIAL:
• In MR Urography (MRU), intravenous contrast material is used to enhance
imaging of the upper urinary tract, providing detailed images of the kidneys,
ureters, and bladder.
• Gadolinium-based contrast material is commonly used in MR exams, altering
the magnetic properties of nearby water molecules to enhance organ
visualization.
• The procedure involves inserting an intravenous (IV) line into a vein in your
hand or arm to administer the contrast material.

33. The contrast material helps in obtaining superior anatomic detail of the urinary tract and
surrounding structures compared to other imaging tests.
MRU and CT Urography (CTU) are effective in detecting urinary tract issues and
abnormalities, providing valuable information about abdominal and pelvic structures.