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KMID : 0861420110150020065
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Korean Journal of Nuclear Medicine Technology
2011 Volume.15 No. 2 p.65 ~ p.71
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Usability of Multiple Confocal SPECT SYSTEM in the Myocardial Perfusion SPECT Using 99mTc
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Shin Chae-Ho
Pyo Seong-Jae
Kim Bong-Soo
Jo Yong-Gwi
Cho Jin-Woo
Kim Chang-Ho
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Abstract
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Purpose: The recently adopted multiple confocal SPECT SYSTEM (hereinafter called IQ SPECTTM) has a high
difference from the conventional myocardial perfusion SPECT in the collimator form, image capture method,
and image reconstruction method. This study was conducted to compare this novice equipment with the
conventional one to design a protocol meeting the IQ SPECT, and also determine the characteristics and
usefulness of IQ SPECT.
Materials and Methods: 1. For the objects of LEHR (Low energy high resolution)
collimator and Multiple confocal collimator, 99mTc 37MBq was put in the acrylic dish then each sensitivity
(cpm/μCi) was measured at the distance of 5 cm, 10 cm, 20 cm, 30 cm, and 40 cm respectively. 2. Based on the
sensitivity measure results, IQ SPECT Protocol was designed according to the conventional general myocardial
SPECT, then respectively 278 kBq/mL, 7.4 kBq/mL, and 48 kBq/mL of 99mTc were injected into the myocardial
and soft tissues and liver site by using the anthropomorphic torso phantom then the myocardial perfusion SPECT
was run. 3. For the comparison of FWHMs (Full Width at Half Maximum) resulted from the image
reconstruction of LEHR collimator, the FWHMs (mm) were measured with only algorithms changed, in the case
of the FBP (Filtered Back projection) method- a reconstruction method of conventional myocardial perfusion
SPECT, and the 3D OSEM (Ordered subsets expectation maximization) method of IQ SPECT, by using 99mTc
Line source.
Results:1. The values of IQ SPECT collimator sensitivity (cpm/μCi) were 302, 382, 655, 816,
1178, and those of LEHR collimator were measured as 204, 204, 202, 201, 198, both at the distance of 5 cm, 10
cm, 20 cm, 30 cm, and 40 cm respectively. It was found the difference of sensitivity increases up to 4 times at the
distance of 30 cm in the cases of IQ SPECT and LEHR. 2. The myocardial perfusion SPECT Protocol was
designed according to the geometric characteristics of IQ SPECT based on the sensitivity results, then the
phantom test for the aforesaid protocol was conducted. As a result, it was found the examination time can be
reduced 1/4 compared to the past. 3. In the comparison of FWHMs according to the reconstructed algorithm in
the FBP method and 3D OSEM method followed after the SEPCT test using a LEHR collimator, the result was
obtained that FWHM rose around twice in the 3D OSEM method.
Conclusion:The IQ SPECT uses the Multiple
confocal collimator for the myocardial perfusion SPECT to enhance the sensitivity and also reduces
examination time and contributes to improvement of visual screen quality through the myocardial-specific
geometric image capture method and image reconstruction method. Due to such benefits, it is expected patients
will receive more comfortable and more accurate examinations and it is considered a further study is required
using additional clinical materials.
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KEYWORD
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Myocardial perfusion SPECT , IQ SPECTTM , Multiple confocal collimator , LEHR collimator , FWHM
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