CT Perfusion Imaging Can Predict Patients' Survival and Early Response to Transarterial Chemo-Lipiodol Infusion for Liver Metastases from Colorectal Cancers

Abstract

Objective: To prospectively evaluate the performance of computed tomography perfusion imaging (CTPI) in predicting the early response to transarterial chemo-lipiodol infusion (TACLI) and survival of patients with colorectal cancer liver metastases (CRLM).

Materials and methods: Computed tomography perfusion imaging was performed before and 1 month after TACLI in 61 consecutive patients. Therapeutic response was evaluated on CT scans 1 month and 4 months after TACLI; the patients were classified as responders and non-responders based on 4-month CT scans after TACLI. The percentage change of CTPI parameters of target lesions were compared between responders and non-responders at 1 month after TACLI. The optimal parameter and cutoff value were determined. The patients were divided into 2 subgroups according to the cutoff value. The log-rank test was used to compare the survival rates of the 2 subgroups.

Results: Four-month images were obtained from 58 patients, of which 39.7% were responders and 60.3% were non-responders. The percentage change in hepatic arterial perfusion (HAP) 1 month after TACLI was the optimal predicting parameter (p = 0.003). The best cut-off value was -21.5% and patients who exhibited a ≥ 21.5% decrease in HAP had a significantly higher overall survival rate than those who exhibited a < 21.5% decrease (p < 0.001).

Conclusion: Computed tomography perfusion imaging can predict the early response to TACLI and survival of patients with CRLM. The percentage change in HAP after TACLI with a cutoff value of -21.5% is the optimal predictor.

Keywords: Colorectal cancer; Computed tomography perfusion imaging; Liver; Metastatic carcinoma; Transarterial chemo-lipiodol infusion.

Fig. 1. Flowchart of patient enrollment and study design.

CRLM = colorectal cancer liver metastases, CTPI = computed tomography perfusion imaging, TACLI = transarterial chemo-lipiodol infusion

Fig. 2. CTPI manifestations of hypervascular lesion before and after TACLI.

Patient is 59-year-old male at 10 months after resection of colonic cancer. Conventional CT plain scan of liver discloses well-defined heterogeneous hypodense mass in Segment IV (A, arrows), and enhanced CT image shows early wash-in during hepatic arterial phase (B, arrows) and early wash-out during portal venous phase (C, arrows). On CTPI before TACLI, target lesion is present as hyperperfusion in HBF (D, arrows) and HAF (E, arrows) maps. After TACLI, conventional CT plain scan of liver shows lipiodol retention in partial pattern (F, arrows), enhanced CT discloses enhancement of residual lesion during arterial phase (G, arrow) and portal venous phase (H, arrow). On CTPI after TACLI, HBF (I, arrow) and HAF (J, arrow) maps reveal significant decrease in perfusion relative to those before TACLI. CTPI = computed tomography perfusion imaging, HAF = hepatic arterial fraction, HBF = hepatic blood flow, TACLI = transarterial chemo-lipiodol infusion

Fig. 3. CTPI manifestations of hypovascular lesion before TACLI.

Patient is 65-year-old male, at 2 months after detecting CRLM. Conventional CT plain scan of liver discloses 2 hypodense masses in Segment IV and VIII (A, arrows), enhanced CT image shows no obvious enhancement during hepatic arterial phase (B, arrows) and portal venous phase (C, arrows). On CTPI, lesions are present as hypoperfusion in HBF (D, arrows), HBV (E, arrows), and PS (F, arrows) maps, meanwhile, HAF map (G, arrows) displays slight hyperperfusion feature. CRLM = colorectal cancer liver metastases, CTPI = computed tomography perfusion imaging, HAF = hepatic arterial fraction, HBF = hepatic blood flow, HBV = hepatic blood volume, PS = permeability surface, TACLI = transarterial chemo-lipiodol infusion

Fig. 4. Kaplan-Meier estimates of overall survival period from start of transarterial chemo-lipiodol infusion (TACLI).

Kaplan-Meier curves for percentage changes in hepatic arterial perfusion (HAP) 1 month after TACLI reveal that Subgroup A (decrease of ≥ 21.5% in percentage changes in HAP) has significantly higher overall survival than Subgroup B (with decrease of < 21.5%) (log-rank test, p < 0.001).