Neoadjuvant treatment of colorectal liver metastases is associated with altered contrast enhancement on computed tomography

Abstract

Neoadjuvant systemic therapy may induce steatosis or sinusoid obstruction syndrome in the liver. The aim of this study was to investigate the influence of systemic therapy with irinotecan, oxaliplatin and cetuximab on conspicuity of liver metastases on computed tomography (CT). CT scans of 48 patients with initial unresectable colorectal liver metastases which were treated in a Europe-wide, opened, randomized phase II trial receiving oxaliplatin or irinotecan combined with folinic acid and cetuximab were analysed. The density of the metastases and the liver parenchyma before and after systemic therapy were analysed by region-of-interest technique and the tumour-to-liver difference (dHU TLD). The mean density of liver parenchyma and liver metastases did not vary significantly before and after neoadjuvant therapy on plain (56.3 ± 8.1 HU, 54.8 ± 13.5 HU) and arterial enhanced CT (76.0 ± 15.7 HU, 70.5 ± 20.4 HU). There was a significant reduction (105.6 ± 17.3 HU, 93.3 ± 18.2 HU) in the density of liver parenchyma on portal venous scans after systemic therapy (p < 0.0001) and a reduction of dHU TLD, consecutively. In patients with colorectal liver metastases, neoadjuvant chemotherapy may have a toxic impact on liver parenchyma resulting in reduced tumour-to-liver contrast in contrast-enhanced CT. This may lead to underestimation of real lesion size.

Figure 1

Measurement in right liver lobe: evaluation of density of liver parenchyma by placement of defined ROIs on selected regions in liver avoiding pathological structures or vessels. Measurement in left liver lobe: evaluation of density of metastasis by circulating ROI.

Figure 2

Box plot showing the density of liver parenchyma in plain CT (p) and in portal venous phase (pv) in baseline and follow-up in HU; decreasing densities from baseline to follow-up in portal venous phase is significant. In plain CT the same tendency is recognizable but not significant.

Figure 3

CT of portal venous phase. Top: images without measurements, baseline (left) and follow-up (right). Bottom: same images with measurements, baseline (left) and follow-up (right); the difference in density of liver parenchyma is clearly recognizable (baseline 75.4 HU, follow-up 41.6 HU).

Figure 4

Top: plain CT of one patient; baseline (left), follow-up (right); note the less decreased density of liver parenchyma; baseline 54.3 HU, follow-up 61.4 HU. Bottom: same patient portal venous phase; baseline (left), follow-up (right); note the significantly decreased contrast, baseline 126.6 HU, follow-up 89.2 HU.

Figure 5

CT of the arterial phase; baseline (left), follow-up (right); note the decreased density of liver parenchyma, not significant; metastasis no longer identifiable.

Figure 6

Box plot showing alteration of tumour-to-liver difference between baseline and follow-up in portal venous phase; note the decrease in contrast, significant.