Between October 2004 and November 2011,
a total of 183 consecutive patients with HCC underwent LT at our hospital.
8 patients were excluded because of a short follow up period (≤2 months),
as a result of perioperative mortality.
The remaining 175 patients (151 men,
who had a follow-up period longer than 2 months and had undergone dymanic-imaging evaluation at least 3 months before transplantation,
Table 1 summarizes clinical characteristics of the included patients.
The preoperative dynamic-imaging examination performed closest to the time of transplant and within 3 months prior to LT was contrast-enhanced multiphase MDCT in 138 patients and contrast-enhanced MRI in 37 patients.
The mean interval between the last imaging examination and LT was 42 days with a range of 1-75 days.
MDCT examinations were performed using a 64-slice CT scanner (GE Medical Systems,
USA) with contrast enhancement and bolus-tracking technique to obtain a multiphase (arterial,
portal and hepatic venous phases) examination after an unenhanced scan. Dynamic MRI studies were conducted on a 1.5-T high field magnet (Achieva,
Philips Medical System,
The Netherlands) with a Phased Array coil.
The protocol included axial T1- and T2-weighted sequences with and without fat suppression and axial dynamic three-dimensional T1-weighted GRE sequences with fat suppression obtained before and after a bolus injection of gadopentetate dimeglumine (Gd-DOTA) with bolus-tracking technique in arterial,
portal and hepatic venous phases.
Pretransplantation imaging examinations were retrospectively reviewed by consensus by two experienced radiologists,
collecting data about the presence of viable tumor and HCC enhancement pattern,
in particular the presence of wash-in,
defined as present when the lesion was hyperattenuating compared to the surrounding hepatic parenchyma during the arterial phase. The lesions were then divided in hypervascular and hypovascular.
When no viable tumor was detectable at the imaging examination performed closest to the LT,
previous available imaging examination performed within 6 months to the LT were evaluated to collect data about enhancement pattern.
Histopathology of the explanted liver.
A pathologist experienced with liver pathologies reviewed all pathologic reports of the explanted livers.
The collected pathologic data were: presence of viable tumor,
histological subtype (HCC or combined hepatocellular-cholangiocarcinoma) and differentiation degree,
scored according to the World Health Organization criteria (6).
Recurrence analysis: Imaging and Histopathology.
All available postoperative imaging examinations (MDCT or MRI) were retrospectively reviewed for evidence of recurrent HCC.
Proof of recurrence was made on the basis of biopsy or growth of new lesions with appropriate radiologic features,
combined with rising AFP levels or with negative work-up for another primary malignancy.
In patients with recurrent HCC,
imaging patterns of recurrence were described based on the examination performed at the moment of the first recurrence,
extrahepatic and both intrahepatic and extrahepatic recurrence.
Based on recurrence timing,
recurrence cases were divided into early (<2 years after LT) and late recurrence (≥2 years after LT).
Follow-up imaging examinations performed after the first recurrence were reviewed for evidence of late intrahepatic recurrence.
In all patients with intrahepatic recurrence (early and late),
dynamic-imaging examination (MDCT or MRI) were retrospectively reviewed,
collecting data about the enhancement pattern,
in particular the presence of wash-in,
classifying lesions in hypervascular and hypovascular.
In patients who underwent biopsy of the recurred HCC,
histopathological characteristics (histological subtype and differentiation degree) were obtained by a review of the pathological reports.
The association between pretransplantation HCC enhancement pattern (hypervascular or hypovascular) and explanted liver HCC differentiation degree was evaluated by using the Fisher exact test.
Recurrence rate was calculated.
The presence of variation in imaging features (enhancement pattern) and histopathological characteristics (differentiation degree) between the primary and the intrahepatic recurred HCC was evaluated and the association between imaging and histopatholgical variations was estimated by using the χ2 test.
For all statistical analyses,
a p<0.05 was considered to indicate a statistically significant difference.