Clinical Presentation

A 43-year-old woman presents with acute shortness of breath.

Fig. 51.1

Lung Perfusion Scan

• A 3.0 mCi dose of ^99mTc-MAA is administered intravenously with the patient supine.

• The patient should cough and take several deep breaths before administration of the MAA to clear any areas of resting atelectasis.

• The patient should breathe normally during tracer injection.

• Use a low-energy, all-purpose collimator.

• Energy window 20% centered at 140 keV.

• Imaging time is 500,000 counts per view.

• Matrix size is 128 × 128.

• Views are anterior, right anterior oblique, left anterior oblique, posterior, right posterior oblique, and left posterior oblique. Lateral views can also be obtained, although it is important to remember that counts from the contralateral lung will contribute to these views.

Lung Ventilation Scan

• A 20.0 mCi dose of ¹³³Xe is breathed in via mask with the patient sitting up.

• Use a low-energy, all-purpose collimator.

• Energy window 20% centered at 80 keV.

• Matrix size is 128 × 128.

• Imaging time

Initial breath image: one 15-second image

Equilibrium phase: 15 images, 15 seconds per image