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KMID : 0861420110150020076
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Korean Journal of Nuclear Medicine Technology
2011 Volume.15 No. 2 p.76 ~ p.82
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Evaluation of Error Factors in Quantitative Analysis of Lymphoscintigraphy
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Yeon Joon-Ho
Kim Soo-Young
Choi Sung-Ook
Seok Jae-Dong
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Abstract
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Purpose:Lymphoscintigraphy is absolutely being used standard examination in lymphatic diagnosis, evaluation
after treatment, and it is useful for lymphedema to plan therapy. In case of lymphoscintigraphy of
lower-extremity lymphedema, it had an effect on results if patients had not pose same position on the
examination of 1 min, 1 hour and 2 hours after injection. So we’ll study the methods to improve confidence with
minimized quantitative analysis errors by influence factors.
Materials and Methods: Being used the Infinia of GE Co. we injected 99mTc-phytate 37 MBq (1.0 mCi) 4 sylinges into 40 people’s feet hypodermically from June to August 2010 in Samsung Medical Center. After we acquired images of fixed and unfixed condition, we confirmed the count values change by attenuation of soft tissue and bone according to different feet position. And we estimated 5 times increasing 2 cm of distance between 99mTc point source and detector each time to check counts difference according to distance change by different feet position. Finally, we compared 1 and 6
min lymphoscintigraphy images with same position to check the effect of quantitative analysis results owing to
difference of amounts of movement of the 99mTc-phytate in the lymphatic duct.
Results: Percentage difference regarding error values showed minimum 2.7% and maximum 25.8% when comparing fixed and unfixed feet position of lymphoscintigraphy examination at 1 min after injection. And count values according to distance were 173,661 (2 cm), 172,095 (4 cm), 170,996 (6 cm), 167,677 (8 cm), 169,208 counts (10 cm) which distance was increased interval of 2 cm and basal value was mean 176,587 counts, and percentage difference values were not over 2.5% such as 1.27, 1.79, 2.04, 2.42, 2.35%. Also, Assessment results about amounts of movement in
lymphatic duct within 6 min until scanning after injection showed minimum 0.15%, and maximum 2.3% which
were amounts of movement. We can recognize that error values represent over 20% due to only attenuation of
soft tissue and bone except for distance difference (2.42%) and amounts of movement in lymphatic duct (2.3%).
Conclusion: It was show that if same patients posed different feet position on the examination of 1 min, 1 hour
and 2 hours after injection in the lymphoscintigraphy which is evaluating lymphatic flow of patients with
lymphedema and analyzing amount of intake by lymphatic system, maximum error value represented 25.8% due
to attenuation of soft tissue and bone, and PASW (Predictive Analytics Software) showed that fixed and unfixed
feet position was different each other. And difference of distance between detector and feet and change of count
values by difference of examination beginning time after injection influence on quantitative analysis results
partially. Therefore, we’ll make an effort to fix feet position and make the most of fixing board in
lymphoscintigraphy with quantitative analysis.
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KEYWORD
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Lymphoscintigraphy, fixing board, quantitative analysis, attenuation by soft tissue and bone
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