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Table 2 Regions to be segmented in complex situations of marked mismatch between radiological and nuclear medicine images, like Figs. 2B, C and D. Use a contrast-enhanced CT co-registered with CT of SPECT if necessary (see also Numerical example section in the Appendix)

From: EANM dosimetry committee series on standard operational procedures: a unified methodology for 99mTc-MAA pre- and 90Y peri-therapy dosimetry in liver radioembolization with 90Y microspheres

Region number Tissue region VOI name Segmentation aim and strategy
1 Whole liver VOICT(whole liver) CT-based, to quantify volume. Exclude cysts or necrosis from previous treatments.
2 Targeted lesions VOICT(#1)
CT-based, including low-perfusion region to quantify volume.
Derive respective counts from perfused lesion regions.
3 Non targeted lesion VOICT (non-targeted lesions) CT-based, including low-perfusion region
4 Perfused liver VOISPECT(PL) SPECT-based, to determine counts
5 Perfused liver VOICT(PL) To determine PL volume. To obtain this VOI, Crop 4 within 1
6 Perfused lesion regions VOISPECT(#1)
SPECT-based (aided by CT), excluding low-perfusion region , to determine SPECT lesion volume and counts
7 Perfused non-tumoural liver VOISPECT(PNTL) To obtain the number of counts N. 4 minus 6: N{VOISPECT(PL)} − N{∑iVOISPECT(#i)}
8 Perfused non-tumoural liver VOICT(PNTL) To obtain volume. 5 minus 2: VOISPECT(PL) − ΣVOICT(#i), limited within 1
9 Non-tumoural whole liver (includes also non-perfused liver) VOICT(NTL) Non-tumoural whole liver volume is obtained by subtraction:
Volume 1 minus (Volume 2 + Volume 3)
Non-tumoural whole liver counts 4 subtracted of counts in 6 identical to 7
Record the non-tumoural liver-treated volume fraction Vf
\( {\boldsymbol{V}}_{\boldsymbol{f}}=\frac{{\mathbf{VOI}}_{\mathbf{CT}}\left(\mathbf{PNTL}\right)}{{\mathbf{VOI}}_{\mathbf{CT}}\left(\mathbf{NTL}\right)} \)
10 Lung (in case of substantial LSF) VOICT(Lung) CT-based, to determine volume and counts.