CT Perfusion for Early Response Evaluation of Radiofrequency Ablation of Focal Liver Lesions: First Experience.
OBJECTIVE
To investigate the value of perfusion CT (P-CT) for early assessment of treatment response in patients undergoing radiofrequency ablation (RFA) of focal liver lesions.


METHODS
20 consecutive patients (14 men; mean age 64 ± 14) undergoing P-CT within 24 h after RFA of liver metastases (n = 10) or HCC (n = 10) were retrospectively included. Two readers determined arterial liver perfusion (ALP, mL/min/100 mL), portal liver perfusion (PLP, mL/min/100 mL), and hepatic perfusion index (HPI, %) in all post-RFA lesions by placing a volume of interest in the necrotic central (CZ), the transition (TZ), and the surrounding parenchymal (PZ) zone. Patients were classified into complete responders (no residual tumor) and incomplete responders (residual/progressive tumor) using imaging follow-up with contrast-enhanced CT or MRI after a mean of 57 ± 30 days. Prediction of treatment response was evaluated using the area under the curve (AUC) from receiver operating characteristic analysis.


RESULTS
Mean ALP/PLP/HPI of both readers were 4.8/15.4/61.2 for the CZ, 9.9/16.8/66.3 for the TZ and 20.7/29.0/61.8 for the PZ. Interreader agreement of HPI was fair for the CZ (intraclass coefficient 0.713), good for the TZ (0.813), and excellent for the PZ (0.920). For both readers, there were significant differences in HPI of the CZ and TZ between responders and nonresponders (both, P < 0.05). HPI of the TZ showed the highest AUC (0.911) for prediction of residual tumor, suggesting a cut-off value of 76 %.


CONCLUSIONS
Increased HPI of the transition zone assessed with P-CT after RFA might serve as an early quantitative biomarker for residual tumor in patients with focal liver lesions.
Department of Diagnostic and Interventional Radiology, Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, 8091, Zurich, Switzerland. hermanpaulo.marquezmasquiaran@usz.ch.
Herman P
HP
Marquez
Department of Diagnostic and Interventional Radiology, Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, 8091, Zurich, Switzerland.
Gilbert
G
Puippe
Department of Diagnostic and Interventional Radiology, Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, 8091, Zurich, Switzerland.
Rishi Philip
RP
Mathew
Department of Diagnostic and Interventional Radiology, Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, 8091, Zurich, Switzerland.
Hatem
H
Alkadhi
Department of Diagnostic and Interventional Radiology, Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, 8091, Zurich, Switzerland.
Thomas
T
Pfammatter
Department of Diagnostic and Interventional Radiology, Institute of Diagnostic and Interventional Radiology, University Hospital Zurich, 8091, Zurich, Switzerland.
Michael A
MA
Fischer
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006528:Carcinoma, Hepatocellular / Q000098:blood supply / Q000000981:diagnostic imaging* / Q000601:surgery*; D017115:Catheter Ablation / Q000379:methods*; D005260:Female; D006801:Humans; D008099:Liver / Q000098:blood supply / Q000000981:diagnostic imaging / Q000601:surgery; D008113:Liver Neoplasms / Q000098:blood supply / Q000000981:diagnostic imaging* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*
Computed tomography; Hepatocellular carcinoma; Liver metastasis; Perfusion imaging; Radiofrequency ablation