Chapter 9: Respiratory System Scintigraphy

In general how many capillaries are blocked when a perfusion lung scan using Tc-99m is performed?

Both

Which of the following should be considered when injecting MAA?

All of the above

The distribution of aerosol particles in the lungs is influenced by all of the following except:

Amount of technetium added

During the equilibrium phase of a ventilation study, the patient:

Inhales and exhales a mixture of 133Xe and O₂

What best describes the normal blood flow to the lungs in a supine patient?

Largely uniform

What best describes the normal blood flow to the lungs in an erect patient?

Decreased flow to apices relative to bases

During a lung perfusion study, activity is noted in the head and in the area of the kidneys. This represents:

Right to left shunt

What is the method of localization for a perfusion lung study?

Capillary blockade

Hot spots in the lungs on a perfusion study indicate:

Blood was withdrawn into injection syringe

Which of the following describes the correct order in which air would pass through the respiratory anatomy?

Trachea, right bronchus, right upper lobe bronchus, bronchioles, alveoli

Which radiopharmaceutical will be most useful in detecting delayed washout in a patient with COPD?

Xe-133

On lung ventilation images, activity is seen in the trachea and the stomach. This indicates:

That the study was performed with Tc-99m DTPA

Which of the following describes the correct procedure for injection of Tc-99m MAA for a perfusion lung study?

Patient should be in the supine position.

Advantages of using 8 K r for ventilation lung scans include:

All of the above

It is advisable to wait one-half hour following injection of Tc-99m MAA before scanning to allow time for radiopharmaceutical clearance from the circulation.

False

Increased risk of pulmonary embolism is associated with

All of the above

The number of particles injected during a perfusion lung scan should be decreased for:

Patients with severe pulmonary hypertension

Which dose would be the best choice to administer for a ventilation scan with Tc-99m DTPA aerosol?

20 mCi

Lung quantitation is often used to assist physicians in the diagnosis of pulmonary embolism.

False

A patient with lung cancer is scheduled to undergo resection of the right lower lobe. Given the counts obtained by ROI for each lung segment below, what percentage of respiratory function will be lost?

21%

A perfusion lung scan shows a cold defect in the right base. If the ventilation study for the same patient is normal, what is the most probable explanation for the defect?

Pulmonary embolism

If a 5,000,000-particle MAA kit is reconstituted with 70 mCi of Tc-99m in 4 ml, how many particles will be in 2 ml of the reconstituted kit?

2,500,000

Regarding the reconstituted kit in question 22, approximately how many particles will be administered to a patient who receives a 4 mCi dose?

285,700

A patient with pulmonary embolism can have a negative chest X-ray.

True

An MAA kit has an average of 8,000,000 particles and is reconstituted using 90 mCi of Tc-99m in 5 ml at 8:00 a.m. Can the kit be used at 2 p.m. without injecting the patient with more than 800,000 particles?

Yes

Over time, the number of particles per ml in a reconstituted MAA kit will change

False

A perfusion lung scan is being quantified. If counts from an ROI around the left lung are 142,857 and counts within the ROI about the right lung are 195,246, what percentage of perfusion is directed to the right lung?

58%

The capillaries surrounding alveoli have a diameter of:

7.0–10.0 µm

When Tc-99m MAA breaks down after injection into a patient, what happens to the particle fragments?

They are removed from the blood by the liver and spleen.

Ventilation images are usually performed:

Posteriorly to reduce soft tissue attenuation and decrease distance to detector

The use of a nebulizer is required with which of the following radiopharmaceuticals during lung imaging?

Tc-99m DTPA

Perfusion and ventilation lung imaging removes the need for a chest X-ray.

False

When performing a V/Q lung study with Tc-99m MAA and Xe-133, which portion of the exam should be performed first?

Ventilation

Trapping systems for Xe-133 should be installed at the level of the _____, because Xe-133 is _____ than air.

Floor, heavier

Stomach visualization on a ventilation scan performed using Tc-99m DTPA aerosol indicates:

The patient swallowed some of the radiopharmaceutical.

The radiopharmaceutical used for ventilation scanning with the highest administered dose is:

Tc-99m DTPA aerosol

Only half of the administered dose of Tc-99m DTPA aerosol is delivered to the patient.

False

Patient education prior to a ventilation scan may:

Improve image quality and reduce the radiation dose to the technologist

The liver may be seen in the washout phase of a ventilation study because:

Xe-133 gas is fat soluble.

An advantage of Xe-127 over Xe-133 is that:

It can be used after a Tc-99m MAA perfusion study.

When used in conjunction with Tc-99m, Kr-81m can be used to perform ventilation imaging:

All of the above

Xe-133 can be used to perform ventilation scans with a portable camera in the intensive care unit.

False

A V/Q scan can be used:

All of the above

When performing an aerosol Tc-99m DTPA aerosol V/Q scan, which of the following is correct:

Tc-99m DTPA aerosol ventilation imaging can be performed before or after perfusion imaging.

When performing a Xe-133 V/Q scan, which of the following is not correct:

The number of MAA particles should no less than 500,000.

When performing a Tc-99m DTPA aerosol V/Q scan, which of the following is not correct:

The lower dose is always administered first, no matter if the rest or stress is performed first.

Advantages of V/Q scan over CTA include the following except:

Can be performed in patients with pregnancy

When performing a Tc-99 m MAA lung perfusion scan to evaluate possible right-to-left shunting, which of the following is correct:

Images must include the brain.