CT PA PULMONARY ANGIOGRAPHY

CTPA (COMPUTERISED TOMOGRAPHY PULMONARY ANGIOGRAM)

 

WHY SHOULD DO CT PULMONARY ANGIOGRAM/ ANGIOGRAPHY?

   A CT pulmonary angiogram examines the blood vessels in your lungs (pulmonary artery) to see any blockage or narrowing.

What can a pulmonary angiogram diagnose?

1. • Pulmonary emboli (PE) – blood clots in the lung
2. • AV avascular malformations of the lung – abnormal connections between arteries and veins
3. • Congenital abnormalities – narrowing of the pulmonary vessels (present from birth)
4. • Pulmonary artery aneurysms – a weakening and bulging of the pulmonary artery
5. • Pulmonary hypertension – high blood pressure in the arteries of the lungs.

What happens during the procedure?

   During the test, dye will be injected into a vein in your arm which travels to your pulmonary arteries. This dye makes the arteries appear bright and white on the test pics. your medical doctor can then see if there are any blockages or blood clots.

Technique

There are two technique

1. Bolus tracking

2. Test bolus

1. Bolus tracking

• patient position

            o supine with their arms above their head

• scout

           o apices to diaphragm

• scan extent

           o apices to diaphragm

• scan direction

          o caudocranial

• contrast injection considerations

          o monitoring slice (region of interest)

          o below the carina at the level of the pulmonary trunk with an ROI on the pulmonary artery

          o threshold

          100 HU

o volume

         60 mL of non-ionic contrast with a 100 mL saline chaser at 4.5/5 mL/s

• scan delay

         o minimal scan delay

• respiration phase

         o inspiration

2. Test bolus

• patient position

         o supine with their arms above their head

• scout

         o apices to diaphragm

• scan extent

         o apices to diaphragm

• scan direction

          o caudocranial

• contrast injection considerations

• test bolus

o contrast volume

          20 mL of non-ionic contrast with a 10 mL saline chaser at 4.5/5 mL/s

o monitoring slice (region of interest)

           below the carina at the level of the pulmonary trunk with an ROI on the pulmonary artery

           monitor contrast enhancement peak over time via a time-enhancement curve

• calculating scan delay

          o as the time-enhancement curve will only begin recording after the scan delay; a widely               accepted formula for calculating the scan delay is 1

          peak contrast enhancement (time-enhancement curve) + scanner's diagnostic scan delay

• contrast volume (diagnostic scan)

         o 60 mL of non-ionic contrast with a 100 mL saline chaser at 4.5/5 mL/s

• scan delay

         o peak contrast enhancement (time-enhancement curve) + scanner's diagnostic scan delay

• respiration phase

         o inspiration