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- Sometimes a lesion will be hypovascular compared to the normal tissue and in some cases a lesion will be hypervascular to the surrounding tissue in a certain phase of enhancement.. -[r]

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THE TECHNICAL FACTORS AFFECTING THE QUALITY OF DIAGNOSIS IN ABDOMEN OF

CONTRAST – ENHANCED CT

CN: Phạm VănĐiệp CN: Nguyễn Quang Trung

Radiology Department–Hanoi Medical University Hospital

OVERVIEW

• CT scan of the abdomen with an injection of contrast is a method of high diagnostic value in abdominal pathologyg g p gy

• The diagnostic value after the visit depends on the image quality obtained after the scan

• Requirements: Optimal image quality and ensure the lowest di ti d d d

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- The purpose of contrast-enhanced CT (CECT) is to find pathology by enhancing the contrast between a lesion and the normal

CONTRAST

y g

surrounding structures.

- Sometimes a lesion will be hypovascular compared to the normal tissue and in some cases a lesion will be hypervascular to the surrounding tissue in a certain phase of enhancement.

- So it is important to know in which phase a CT should be performed depending on the pathology of patient

THE PHASES OF CECT

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3 Purpose:

NON- ENHANCED CT (NECT)

Purpose:

• Detection of stones in kidney, ureter • Detection of calcifications in liver,

pancreas • Fat inlivertumors • Fat in adrenal adenoma

http://www.radiologyassistant.nl/en/p52c04470dbd5c/ct-contrast-injection-and-protocols.html

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Timing:

EARLY ARTERIAL PHASE

15-20 sec pre injection or immediately after bolustracking

Purpose:

• Detection of dissection of aorta, arterial bleeding

• Insulinoma

http://www.radiologyassistant.nl/en/p52c04470dbd5c/ct‐contrast‐injection‐and‐protocols.html

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5 Timing:

• 35-40 sec p.i or 15-20 sec after

LATE ARTERIAL PHASE

p bolustracking

Purpose:

Detection of

• Liver: HCC-FNH-Adenoma

• Pancreas : Adenocarcinoma, insulinoma

• Bowel ischemia

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6 Timing:

HEPATIC PHASE

• 70-80 sec p.i or 50-60 sec after bolustracking

Purpose:

• Enhancement of the hepatic parenchyma

• Detection of hypovascular liver lesions: cysts, abscess, most metastases

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7 Timing:

NEPHROGENIC PHASE

Timing:

• 100 sec p.i or 80 sec after bolustracking

Purpose :

• Enhancement of all renal parenchyma

• Detection of renal cell carcinoma

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8 Timing:

DELAYED PHASE

• After 6-10 minutes p.i

Purpose:

• Enhancement of fibrotic lesions

• Enhancement of kidney and urinary

collecting system

• Detection of cholangiocarcinoma, transitional cell carcinoma

cell carcinoma

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9 TIMING OF CT-SERIES THE FACTORS TOTAL AMOUNT OF CONTRAST INJECTION RATE ANOTHER FACTORS

-In many protocols a standard dose is given related to the weight of

Total amount of

contrast

the patient:

Weight < 75kg : 100cc Weight 75-90kg: 120cc Weight > 90kg : 150cc

In some protocols we always want to give the maximum dose of - In some protocols we always want to give the maximum dose of

150cc, like when you are looking for a pancreatic carcinoma or liver

metastases

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10

CREATININE CLEARANCE

https://www.mdcalc.com/creatinine‐clearance‐cockcroft‐gault‐equation

• Recommended injection rate of 5cc/sec using G18 I.V

h l ti th ki ti f l i

INJECTION RATE

when evaluating the kinetics of lesions

• Unneccessary in case just focus at hepatic phase or having problem with machine, line,

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INJECTION RATE

Patient with liver cirrhosis and multifocal HCC injected at 2.5 ml/sec and at 5ml/sec

INJECTION RATE

Food and Drug Administration (FDA)-approved devices for power/pressure injection as below:

Injection rates for 24G catheters up to ml/s Injection rates for 22G catheters up to ml/s Injection rates for 20G catheter up to ml/s Injection rates for 18G catheter up to ml/s

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TIMING OF CT-SERIES

 Timing of CT-series is important in order to grab the right moment of maximal contrast differences between a lesion and the normal parenchyma

 The protocol we choose to visit depends very much on the clinical diagnosis

 CT generation

 Supply of heart and body condition of patients

LIVER

The phases :

 NECT (non-enhanced CT)  Arterial phase (35 sec)  Hepatic phase (70 sec)  Delayed phase (3 - mins)

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13

LIVER

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14 https://www.acr.org/‐/media/ACR/Files/RADS/LI‐RADS/LI‐RADS‐2018‐Core.pdf?la=en

PANCREAS

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PANCREAS

a: pre- contrast b: 35s c: 55s d: 80s

PANCREAS

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16

URINARY

Kidney injury with delayed phase

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INJURY

Spleen injury with arterial phase

HEMORRHAGIC

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18

BLOOD VESSEL

Dissection of superior mesenteric artery

 Depending on machines, equipment, medical facility.

ANOTHER FACTORS

 Factors of age, weight, heart disease, vascular.

 Experience of doctor and technicians.

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19 The delay time of post injection should be determined by

ANOTHER FACTORS

considering three factors:

● Time of contrast injection

● Arrival time of contrast medicine

● Scanning time (depending on the type of CT machine)

 CECT is a valuable diagnostic method, especially in emergency medical conditions

CONCLUDE

 For good diagnostic results, the image quality after scan is very important

 Equipment and experience of technicians is very important  Collaboration between doctors and technicians

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20 •

http://www.radiologyassistant.nl/en/p52c04470dbd5c/ct-contrast-i j thttp://www.radiologyassistant.nl/en/p52c04470dbd5c/ct-contrast-i d t l ht l

References

injection-and-protocols.html

• https://www.radiologyinfo.org/en/info.cfm?pg=safety-radiation • Split-Bolus MDCT Urography with Synchronous Nephrographic and

Excretory Phase Enhancement

• How Much Dose Can Be Saved in Three-Phase CT Urography? •

https://www.acr.org/-/media/ACR/Files/RADS/LI-RADS/LI-RADS-2018-Core.pdf?la=enp

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21 THANK YOU !