Transmission Imaging in Lymphoscintigraphy with a 153Gd Flood Source

Area of Science:

• Nuclear medicine imaging
• Radiopharmaceutical science

Background:

• Lymphoscintigraphy uses technetium-99m (Tc-99m) tracers for lymph node imaging.
• Anatomic information is limited in Tc-99m images, often necessitating a cobalt-57 (Co-57) flood source for transmission imaging.
• Co-57 flood sources introduce background noise, reducing signal-to-noise ratio (SNR) and potentially hindering lymph node detection.

Purpose of the Study:

• To evaluate the effectiveness of a gadolinium-153 (Gd-153) flood source as an alternative to Co-57 for lymphoscintigraphy.
• To determine if Gd-153 can reduce background noise and improve SNR compared to Co-57 and no flood source.

Main Methods:

• Phantom studies were conducted comparing Gd-153, Co-57, and no flood source in simulated lymphoscintigraphy.
• Signal-to-noise ratio (SNR) was measured in Tc-99m emission images using a water phantom and point sources.
• The Gd-153 flood source was subsequently used in clinical breast lymphoscintigraphy, melanoma lymphoscintigraphy, and lymphedema studies.

Main Results:

• SNR was highest with no flood source, lowest with Co-57, and comparable to no flood source with Gd-153 on anterior views.
• Gd-153 showed reduced crosstalk and allowed for usable posterior views with anatomic shadowing, unlike Co-57.
• Clinical images acquired with Gd-153 were of high quality, with improved interpretation flexibility through fused emission and transmission data.

Conclusions:

• Gd-153 flood source offers advantages over Co-57 for lymphoscintigraphy by providing fused images with reduced crosstalk and improved quality.
• Higher SNR in emission images with Gd-153 suggests a likely improvement in clinical lymph node detection.
• Separate acquisition windows for emission and transmission data enhance image display flexibility for physicians.