Measured versus estimated total liver volume to preoperatively assess the adequacy of the future liver remnant: Which method should we use?

OBJECTIVES: To determine which method of liver volumetry is more accurate in predicting a safe resection. BACKGROUND: Before major or extended hepatectomy, assessment of the future liver remnant (FLR) is crucial to reduce the risk of postoperative hepatic insufficiency. The FLR volume is usually expressed as the ratio of FLR to nontumorous total liver volume (TLV), which can be measured directly by computed tomography (mTLV) or estimated (eTLV) on the basis of correlation existing with the body surface area. To date, these 2 methods have never been compared. METHODS: All consecutive, noncirrhotic patients who underwent resection of 3 or more liver segments between April 2000 and April 2012 and for whom (i) preoperative computed tomographic scans and (ii) body surface area were available entered the study. The mTLV (calculated as TLV - tumor volume) was compared with the eTLV (calculated as -794.41 + 1267.28 × body surface area) using volumetric data (cm) and clinical outcome measures (specifically, hepatic insufficiency and 90-day mortality). Definition of hepatic insufficiency was peak postoperative serum total bilirubin level of more than 7 mg/dL or, in jaundiced patients, an increasing bilirubin level on day 5 or thereafter. RESULTS: Two-hundred forty-three patients who had undergone major (n = 135) or extended (n = 108) hepatectomies met the inclusion criteria. Twenty-eight patients (11.5%) developed hepatic insufficiency, whereas 7 patients (2.9%) died postoperatively. Compared with the eTLV, the mTLV underestimated the liver volume in 60.1% of the patients (P < 0.01). Forty-seven and 73 patients had an inadequate FLR based on mTLV and eTLV, respectively. Portal vein occlusion (PVO) was used in 44 patients. In patients (n = 162) in whom both methods did not evidence the need for PVO, postoperative hepatic insufficiency and mortality were 4.9% and 0.6%, respectively. Conversely, in patients (n = 27) in whom the eTLV but not the mTLV evidenced the need for PVO, and thus PVO was not performed, hepatic insufficiency (22.2%; P = 0.001) and mortality (3.7%; P = ns) were higher. CONCLUSIONS: The use of eTLV identifies a subset of patients (∼11%) in whom liver volumetry with the mTLV underestimates the risk of hepatic insufficiency.