Clinical Presentation

Fig. 156.1

Fig. 156.2

Fig. 156.3

• To block thyroid uptake, potassium perchlorate (400 mg) is administered by mouth 15 minutes before^99mTc-pertechnetate.

• Indwelling catheters with subcutaneous chambers (such as those of the Port-A-Cath) need to be accessed with sterile technique.

• With the patient lying supine, butterfly needles are attached to a three-way stopcock connected to the accessed central line ports and also placed into a vein in each upper extremity.

• Connected to the stopcocks are 1-mL syringes containing approximately 5 mCi of ^99mTc-pertechne-tate in a volume of 0.1 to 0.3 mL and 10-mL syringes containing 10 mL of normal saline.

• Gamma camera with a large field of view

• Low-energy, parallel-hole, high-resolution collimator

• Energy window 20% centered at 140 keV

• The camera is positioned over the anterior chest and shoulders with the heart in the center of the field of view.

• The tracer is administered as a bolus injection, followed by the infusion of 10-mL flushes of normal saline in rapid sequence: first into the upper extremity ipsilateral to the central line, then the contralateral arm, and finally the central line.

• Digital dynamic images are obtained in a 64 × 64 matrix at 1 frame per second for 120 seconds. At the completion of the study, the central line is flushed with 5 mL of heparin lock flush solution.

• Data are reviewed in a cine format as well as 1 second per frame digital images.

Image Interpretation