Ga-citrate vs In-WBC

	67Ga-citrate	111In-WBC
Half-life	3 days	3 days
Basics	Nonspecific marker for inflammation, infection, and tumor.	Goes where the white cells go
Imaging	24-48 hours	12-24 hours
Immunocompromised patients	Great (since doesn't need inflammatory response).	OK for acute pyogenic infections. May give false negative results in viral, fungal, TB, and parasitic infections.
Uncomplicated osteomyelitis	Triple-phase bone scan is usually diagnostic. Good for following treated osteomyelitis.	Triple-phase bone scan is usually diagnostic. 111In scan with or without sulfur colloid scan can help in equivocal cases. Combined marrow (sulfur colloid)/Indium imaging. Positive: Distribution of the two tracers is spatially incongruent. Negative: Distribution of the two tracers is spatially congruent (e.g., aseptic joint loosening).
Spinal osteomyelitis/diskitis	Combined bone (diphosphonate)/Gallium imaging improves specificity. Positive: Distribution of the two tracers is spatially incongruent Positive: Distribution of the two tracers is spatially congruent and the relative intensity of gallium uptake is greater than that of diphosphonate. Negative: Distribution of the two tracers is spatially congruent and the relative intensity of gallium uptake is less than that of diphosphonate. Negative: Normal gallium scan regardless of bone scan findings Equivocal: Distribution of the two tracers is congruent both spatially and in intensity.	50% of spinal osteomyelitis are photopenic
Infected prosthesis	Combined bone (diphosphonate)/Gallium imaging has an accuracy of about 65-80%, offering modest improvement over bone scintigraphy alone.	Combined marrow (sulfur colloid)/Indium imaging sensitive and specific for osteomyelitis in cases of infected prostheses.
Post-Traumatic infection	~60% sensitivity and specificity	> 90% sensitivity and specificity
Sarcoidosis	Lambda pattern of hilar and right paratracheal adenopathy suggestive. Lambda plus panda signs together highly specific (panda=uptake in lacrimal, parotid, and salivary glands)	N/A
FUO	Chronic phase	Acute phase
Endocarditis	Not great.	Not great.
Abdominal	Not great since lots of normal bowel uptake. But good for splenic abscess, since there isn't a lot of baseline splenic activity.	Good for abdominal infections, including infected abdominal aortic grafts. Bad for splenic abscesses, since lots of baseline splenic activity (see image)
Neuropathic joint infections		In combination with bone scan. Positive early 111In images are nonspecific. Fading activity on 24-hour scans suggests sterile disease. Intense focal, incongruent activity is suggestive of infection.
Sinusitis	Not good, since there is normal nasopharyngeal uptake.	Good since no interfering nasopharyngeal uptake.

References

• Love C, Marwin SE, Palestro CJ. Nuclear medicine and the infected joint replacement. Semin Nucl Med. 2009 Jan;39(1):66-78.
• Mettler FA and Guiberteau MJ. Chapter 10. In Essentials of Nuclear Medicine Imaging. Fifth Edition. Saunders, Philadelphia. 2006. pp 294-295.