Case 47 cont'd
This is a Heat-Damaged Red Blood Cell (RBC) Scan, requested by a surgeon to investigate the possibility of splenogonadal fusion.
Normal distribution of damaged RBC is noted in the spleen, blood pool, liver , bone marrow and genitourinary system, with no evidence of ectopic splenic tissue. Accumulation of damaged RBCs is noted in the pubic area, corresponding to activity in the penis on SPECT-CT images (not shown).
In nuclear medicine imaging, particularly during gastrointestinal bleeding scintigraphy using 99mTc-labeled red blood cells (RBCs), increased activity can sometimes be observed in the penile region.
This uptake is typically due to the rich vascularity of the penis and can be mistaken for rectal bleeding. To differentiate between penile activity and rectal bleeding, obtaining lateral images or repositioning the penis can be helpful.
Similar principles may apply to heat-damaged RBC scans.
Discussion:
Heat-damaged red blood cell scan
Radiopharmaceutical, Dose, & Technique of Administration
Radiopharmaceutical: 99mTc-labeled red blood cells
Activity: 370MBq (10 mCi)
We use the Ultra Tag labeling protocol
Using the Ultra Tag protocol, 7 mL of blood is drawn, labeled, and heat-damaged in a 49.5°C water bath for 20 minutes with frequent agitation. Labeling efficiency is tested, requiring a minimum of 90% for use. After cooling for 10 minutes, a 370 MBq (10 mCi) dose is withdrawn, assayed, and injected. Imaging is performed 1 hour post-injection to ensure optimal splenic uptake.
Imaging with heat or chemically damaged Tc-99m RBCs is useful to detect accessory spleens or splenosis.
Splenogonadal fusion:
Splenogonadal fusion is a rare congenital malformation characterized by an abnormal connection between the spleen and the gonad. This connection forms between weeks 5 and 8 of gestation, prior to gonadal descent, when gastric rotation brings splenic and gonadal tissues into close proximity.
Chu, Jia, et al. "Splenogonadal Fusion." RadioGraphics 44.4 (2024) : e230224. DOI :10.1186/s12894-021-00781-z
Splenogonadal fusion has two variants: the continuous type, with a direct connection between the spleen and gonad (usually upper poles), and the discontinuous type, where ectopic splenic tissue is attached to the gonad without a direct connection. The condition is much more common in males, with a male-to-female ratio of 15:1.
References:
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Chu, Jia, et al. "Splenogonadal Fusion." RadioGraphics 44.4 (2024): e230224.
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Chen, Guangjie, et al. "Splenogonadal fusion: a case report and review of the literature." BMC urology 21 (2021): 1-10.
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Dam, Hung Q., et al. "The SNMMI procedure standard/EANM practice guideline for gastrointestinal bleeding scintigraphy 2.0." Journal of nuclear medicine technology 42.4 (2014): 308-317.