NP-002 Impact of blood sample handling during 99mTc-ceretec leukocyte labelling on image quality and interpretation

<h3>Context and Objective</h3> In vitro labelling of leukocytes with 99mTc-HMPAO is a haematological test performed and optimised in specialised radiopharmacies in some university hospitals. It is used to differentiate between infection on implanted devices and inflammation in cases of pain. However, it requires high-quality biological samples. Several factors, including those related to the patient and healthcare professionals, affect the outcome. This study aims to establish a link between sample quality and image quality to improve our practices and patient care. <h3>Materials and Methods</h3> We first established criteria to assess blood sample quality, such as the duration of collection, the type of equipment used, the puncture site, sedimentation time, hemolysis, and cell viability tests, alongside an associated score (≤2: excellent, 3≤ score ≤5: average, ≥6: poor). We then defined image quality criteria in the early phase, based on spleen/liver (S/L) activity ratios measured during imaging (a ratio &lt;130% indicating good image quality, 130%–150% moderate quality, and &gt;150% poor quality). Lastly, we statistically compared S/L ratios between two groups: good vs. average/poor samples. <h3>Results</h3> Out of 23 samples, 18 were rated ‘excellent,’ two ‘average,’ and three ‘poor.’ Among the ‘excellent’ samples, 17 had S/L ratios &lt;130%, corresponding to good image quality, while one had a ratio &gt;150%. Among the five ‘average/poor’ samples, one had an S/L ratio &lt;130%, one between 130%–150%, and three &gt;150%. A significant difference (P&lt;0.05) was found between the good and average/poor sample groups. <h3>Conclusion/Discussion</h3> Our results suggest that sample quality affects image quality. However, certain biases, such as the small sample size and the low proportion of ‘average/poor’ samples (5/23), should be considered. The choice of quality criteria and scoring system may need refinement. Additionally, the patient’s cell condition at the time of testing and the proximity of the suspected infection to organs like the liver and spleen may influence the results. A larger, long-term study could help develop optimal sampling recommendations.