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Keywords:
Computer applications, Liver, Interventional vascular, MR-Functional imaging, Image manipulation / Reconstruction, Segmentation, Radioembolisation, Computer Applications-General, Cancer
Authors:
S. Thoduka1, P. Schilling1, G. Chlebus2, A. Schenk2, N. Abolmaali1; 1Dresden/DE, 2Bremen/DE
DOI:
10.1594/ecr2017/C-2917
Conclusion
Our study showed good correlations in computer-assisted interactive segmentation of liver volumes between experienced and inexperienced observers,
whereas the segmentation of liver tumours showed lower agreement.
The average tumour to liver volume calculated by the expert as well as the novice were 18.1% and 20.4%,
both below the maximum recommended tumour-load of 50% in patients considered for SIRT [8].
We conclude that with adequate interactive segmentation tools,
liver volumetry can be effectively performed by a novice; however,
the accurate identification and segmentation of liver tumours requires a higher degree of expertise.
This is relevant for SIRT planning since the optimal dose calculation is a prerequisite for improved patient prognosis which cannot be accomplished using rough estimates since the application of modern,
dose calculation algorithms is primarily dependent on accurate liver segmentations.
In planning therapy location in SIRT,
it is essential to calculate the normal liver volume as well as the tumour load in the separate lobes to estimate the delivered radioactivity,
as well as in planning appropriate catheter position for delivery of the microspheres.
The border between the left and right liver lobes accounts for the highest variability in segmentation of the liver.
Contrast-enhanced CT acquired in the venous phase and MRI in the hepatobiliary phase using contrast agents specific for hepatocytes provide good contrast allowing easy identification of the hepatic veins.
The vascular bed of the liver provides the greatest information required in planning accurate catheter position.
In severely altered livers,
e.g.
in cirrhotic livers,
the hepatic veins might be difficult to identify in all imaging methods.
Contrast-agent enhanced CT scans in the arterial phase and angiographic images provide high contrasted views of the hepatic arteries,
even allowing the identification of the tumour-feeding arteries.
Therefore,
it may be possible to use CT and MRI registered images for efficient liver segmentation in order to reduce inter-observer variability,
which will result in more accurate dose calculation and precise catheter position planning,
and thus assist in standardising and optimising this innovative SIRT procedure.