Abdominal cross-sectional imaging of the associating liver partition and portal vein ligation for staged hepatectomy procedure

Table 1 Institutional multiphasic multidetector computed tomography protocol for evaluating associating liver partition and portal vein ligation for staged hepatectomy patients before and after surgery (LightSpeed HD, General Electrics, Milwaukee, United States)

Scan phase (timing from contrast injection)	Scal lenght	Scanning parameters	Rationale in the preoperative phase	Rationale in the postoperative phases
Unenhanced	Upper abdomen	KVp 120 mA modulated between 200-450 Tube rotation 0.6 s Pitch 0.984 Noise index 16.10 Collimation 1.25 mm (0.625 for the angiographic phase) Image reconstruction thickness 1.25 mm	Identifying potential confounders in image interpretation (e.g., lesion’s or vascular calcifications). Measuring baseline attenuation of target lesions (e.g., fat-containing HCC) or in diffuse liver disease (e.g., steatosis)	Identifying potential confounders in image interpretation (e.g., surgical clips). Measuring the attenuation of intra-abdominal collections (biloma vs hematoma)
			This phase is not required if recent prior imaging is available.	This phase in not mandatory in repeated follow-up examinations
Angiographic phase (20)	Upper abdomen		Assessing the patency and anatomic variants of the hepatic artery and its branches, both on source images and MIP reconstructions	Assessing the sources of suspicious active postoperative bleeding
Delayed arterial (35-40 s)	Upper abdomen		Assessing hypervascular focal liver lesions (malignant and benign ones)	Assessing the patency of the hepatic artery and its branches. Identifying the recurrence of hypervascular tumors in the delayed post-operative period
Venous (70 s)	Whole abdomen		Assessing lesions’ enhancement pattern for the purpose of identification/characterization. Assessing the patency and anatomic variants of the portal trunk and intrahepatic branches, both on source images and MIP reconstructions. Identifying additional abdominal findings potentially contraindicating ALPSS. Assessing for signs of chronic liver disease (including splenomegaly, venous collaterals and ascites)	Assessing the portal status (absence of flow in the ligated portal branch and patency of the FLR branch). Assessing successful tumor cleaning up in the FLR before surgical stage 2. Ruling out thrombosis of the portal braches, hepatic veins and inferior vena cava. Identifying tumor relapse
Delayed (3-5 min)	Upper or whole abdomen, depending on findings on previous scans		Assessing lesions’ enhancement pattern for the purpose of identification/characterization. Identifying additional findings potentially contraindicating ALPSS (e.g., peritoneal carcinosis). This phase is not mandatory	Assessing venous bleeding. This phase in not mandatory

MIP: Maximum intensity projection; FLR: Future liver remnant; ALPPS: Associating liver partition and portal vein ligation for staged hepatectomy; HCC: Hepatocellular carcinoma.

Table 2 Institutional magnetic resonance imaging protocol with i.v. administration gadoxetic acid (0.025 mmol/kg at an injection rate of 1 mL/s) for evaluating associating liver partition and portal vein ligation for staged hepatectomy patients before and after surgery

Sequence	Weightening	Acquisition plane	Technical clues	Rationale in the preoperative phase	Rationale in the postoperative phase
Half fourier acquisition single-shot turbo spin echo/single shot fast spin echo	T2	Coronal, transverse	-	Ruling out signs of chronic liver disease, including splenomegaly and/or ascites. Detection of parenchymal low signal intensity in iron accumulation	Detection of perihepatic/abdominal collection and/or ascites
GE in-phase/out of-phase	T1	Transverse	Dual echo, breath hold sequence with slice thickness 6 mm	Characterization of fat-containing lesions. Detection of signal intensity patterns of liver steatosis or hemochromatosis	Evaluation of the postoperative status of liver parenchyma. Characterization of tumor recurrence
MRCP	T2	Radial coronal acquisition (2D) or oblique coronal (3D)	2D and/or 3D technique	Evaluation of anatomic variants complicating or contraindicating surgery. Assessing the Bismuth category of hilar cholangiocarcinoma	Assessment of biliary strictures (site, extent) and biliary dilation upstream
Dynamic study with fat saturated 3D GE	T1	Transverse	Thin slice thickness (3 mm). Baseline acquisition followed by early arterial, late arterial, venous and delayed phases	Detection and characterization of liver lesions	Detection and characterization of parenchymal abnormalities, including tumor recurrence
Single-shot echoplanar imaging	Diffusion	Transverse	b values 50 and 400 and 800 s/mm2 (1.5T) or 50 and 800 and 1200 s/mm2 (3.0T). Nominal acquisition time about 3 min (1.5T) and 4 min (3T)	Detection and characterization of smaller lesions (< 1 cm in size)	Detection of parenchymal/periportal edema. Detection and characterization of smaller lesions (< 1 cm in size)
Fat saturated Turbo spin echo	T2	Transverse	Respiratory triggered, with slice thickness 6 mm. Nominal acquisition time 1.50 min	Detection and characterization of liver lesions.	Detection of parenchymal/periportal edema. Detection and characterization of liver lesions. Assessment of collections
GE in-phase/out of-phase	T1	Transverse	Same sequence as (2), acquired in the hepatobiliary phase (15-20 min after contrast injection)	Detection and characterization of liver lesions	Detection and characterization of liver abnormalities
Fat saturated 3D GE	T1	Transverse	Same sequence as (4), with modified flip angle (35°) to increase lesion-to-parenchyma conspicuity. Acquired in the hepatobiliary phase
Contrast-enhanced	T1	Oblique coronal	Thin-slice (1 mm) fat saturated 3D fast low angle shot (FLASH) sequence acquired	Functional evaluation of biliary obstruction (if present)	Detection of active bile leakage. Functional assessment of bile duct strictures and patency of bilioenteric anastomosis
MRCP

GE: Gradient echo; MRCP: Magnetic resonance cholangiopancreatography.

Table 3 Overview of normal and abnormal findings after surgical stages 1 and 2

	Normal findings		Abnormal findings
Postoperative phase	Goals of ALPPS	Findings not to be confused with pathological aspects	prompting intervention
After surgical stage 1	Hypertrophic FLR (≥ 40% of baseline preoperative volume)	Thin rim of free fluid around both FLR and DH	Large, persisting collections (hematoma, bilomas, infected collections)
		Air bubbles within the perihepatic fluid, especially on the hepatectomy line	Bleeding
			Biliary dilation
		Mild periportal edema	Bile leakage/fistula
		Hypertrophy of hepatic artery for the DH	Portal vein thrombosis
After surgical stage 2	Uncomplicated appearance of the FLR (e.g., no relapsing focal liver lesions)	Thin rim of free fluid around FLR	Early complications
		Air bubbles	see surgical stage 1
		Hypoattenuating linear band adjacent to liver raw surface	Late complications (3-6 mo)
			Biliary stricture
		Rotation of hypertrophic FLR	Biliary fistula
		Transitory splenomegaly	Tumor recurrence

ALPPS: Associated liver partition and portal vein ligation for staged hepatectomy; FLR: Future liver remnant; DH: Diseased hemiliver.