使用 Myometrix 呈現兩種 normalization 型態

前文「核醫心臟影像 normalization 的實務操作」示範過的軟體操作,這次使用真實的案例來實作「series normalization」與「frame normalization」。

雖然雙和醫院核子醫學科的單光子射出電腦斷層(SPECT,非 SPECT/CT)屬於較為早期的 GE Millennium MG 機種,但是影像工作站配備主流的 GE Xeleris 2 Workstation;因此,這台電腦工作站內建的 Xeleris 2.0 影像系統平台有 Myometrix 軟體可以用來操作 myocardial perfusion imaging(MPI,心肌灌注掃瞄影像)相關分析。

底下我們來看看,使用 Myometrix 軟體實作心肌灌注掃瞄影像左心室各個切面兩種 normalization 後的實際型態。

1. Short axis(SA)view(俗稱甜甜圈切面):

Series normalization 的 SA view
Frame normalization 的 SA view

2. Vertical long axis(VLA)view:

Series normalization 的 VLA view
Frame normalization 的 VLA view

3. Horizontal long axis(HLA)view:

Series normalization 的 HLA view
Frame normalization 的 HLA view

看完兩種 normalization 型態後,再複習一次大師 Dr. Guido Germano 與 Dr. Daniel Berman 一書「Clinical Gated Cardiac SPECT」中提到關於 series normalization 與 frame normalization 的差異。摘錄書中原文如下:

As for image normalization, there are two widely used approaches. Each series (short-axis, vertical long-axis, and horizontal long-axis images) can be normalized to the pixel with the highest count in the entire series (series normalization). This approach provides the most intuitively accurate assessment of the presence, extent, and severity of perfusion defects, although it presents the drawbacks of lack of ideal display for each individual slice, sensitivity to focal hot spots, and insensitivity to basal perfusion defects. Alternatively, each tomographic slice can be normalized to the brightest pixel within that slice (“frame normalization’’). This approach provides ideal display of each individual slice, is less sensitive to the problem of basal attenuation, and is the approach that has been utilized for the last 15 years at Cedars-Sinai Medical Center.