Virtual hepatic resection using three-dimensional reconstruction of helical computed tomography angioportograms

Abstract

Objective: To establish the accuracy of virtual hepatic resection using three-dimensional (3D) models constructed from computed tomography angioportography (CTAP) images in determining the liver volume (LV) resected during resectional liver surgery.

Summary background data: The ability to measure LV before surgery could be useful in determining the extent and nature of hepatic resection. Accurate assessment of LV and an estimate of liver function may also allow prediction of postoperative liver failure in patients undergoing resection, assist in volume-enhancing embolization procedures, help with the planning of staged hepatic resection for bilobar disease, and aid in selection of living-related liver donors.

Methods: A retrospective study was conducted involving 27 patients scheduled for liver resection. Using mapping technology, 3D models were constructed from helical CTAP images. From these 3D models, tumor volume, total LV, and functional LV were calculated and were compared with body weight. The 3D liver models were subjected to a virtual hepatectomy along established anatomical planes, and the resected LV was calculated. The resected volume predicted by radiologists (unaware of the actual weight) was compared with the specimen weight measured after actual surgical resection.

Results: A significant correlation was found between body weight and functional LV but not total LV. The computer prediction of resected LV after virtual hepatectomy of 3D models compared well with resected liver weight.

Conclusion: Virtual hepatectomy of 3D CTAP reconstructed images provides an accurate prediction of liver mass removed during subsequent hepatic resection. The authors intend to combine this technology with an assessment of liver function to attempt to predict patients at risk for liver failure after hepatic resection.

Figure 1. Computed tomography angioportography (CTAP) images and three-dimensional (3D) models of the liver and tumor of a representative patient with a right lobe hepatic metastasis who underwent extended right hepatectomy, showing the techniques used to calculate liver volumes and virtual hepatic resection. (A) Coronal CTAP image showing a large tumor in the right lobe of the liver encroaching on the middle hepatic vein. (B) Mapping the liver. The hatched area represents segments 1, 2, and 3, which would be preserved if the patient underwent extended right hepatectomy. (C) 3D model of whole liver (volume 1,717 mL). The dotted line represents the plane of section for an extended right hepatectomy. (D) 3D model of tumor (volume 576 mL). (E) 3D model of residual liver (segments 1, 2, 3) after virtual hepatic resection (residual volume 309 mL).

Figure 2. Correlation between functional (nontumor) liver volume and body weight.

Figure 3. Correlation between the volume of resected liver predicted by three-dimensional computed tomography reconstruction and virtual hepatectomy and the actual weight of resected liver (R² = 0.94, P < .0001).

Figure 4. Liver tissue remaining as a percentage of preoperative functional liver tissue (total liver volume minus tumor volume) after hepatic resection in patients who had clinical evidence of postoperative liver insufficiency (column 1) and in those with an uncomplicated postoperative course (column 2).