Yue Zhao1, Xiuhong Guan1, Yongzhou Xu2, Xinqing Jiang1, and Ruimeng Yang1
1Department of Radiology, Guangzhou First People’s Hospital, Guangzhou, China, 2Philips Healthcare, Guangzhou, China
Synopsis
Keywords: Liver, Liver, Hepatocellular carcinoma; T1 mapping.
Cytokeratin 19 (CK19) is well acknowledged
as a progenitor cell marker and tumor stem cell marker that plays an
important role in promoting the malignant property of HCC. If the preoperative CK19 expression status in HCC can be accurately
predicted noninvasively, it may provide important information for clinical decision-making. T1
mapping is useful for preoperative prediction of CK19 expression and early recurrence of HCC. The
clinical-quantitative model combining alpha-fetoprotein and quantitative
features showed good performance and robustness in predicting CK19 expression. T1
relaxation time on hepatobiliary phase was an independent predictor of CK19
expression and recurrence-free survival.
Introdution
CK19 is well acknowledged as a biliary/progenitor cell marker and tumor
stem cell marker that plays an important role in promoting the malignant
property of HCC [1]. Compared with patients with CK19-negative HCCs,
CK19-positive HCCs are associated with clinical aggressiveness due to more
tumor invasion, a higher rate of intrahepatic recurrence, and poorer prognosis
after resection and liver transplantation [2, 3]. If the preoperative CK19 expression status in HCC can be accurately
predicted noninvasively, it may provide important information for clinical decision-making
and interpretation of prognosis.
The imaging findings associated with poor
prognosis for CK19-positive HCCs have been assessed. For instance, rim arterial
phase hyperenhancement (APHE), lower tumor-to-liver ADC ratio, and lower
tumor-to-liver signal intensity ratio on hepatobiliary phase (HBP) imaging are
significant independent variables for potentially predicting the CK19
expression status [4–6]. In addition, the radiomic score can be used as a
reliable imaging biomarker to determine the expression of CK19 [7, 8];
however, the complexity of the process and the poor generalization and
resolvability of the model are not conducive to the clinical application [9,
10]. T1 mapping is a non-invasive method for quantitative analysis of T1 values
in tissues. Currently, T1 mapping has
important applications in the histological grading of liver fibrosis [11, 12],
degree of HCC differentiation [13, 14], and microvascular invasion [15].
However, to the best of our knowledge, the quantitative evaluation of CK19
expression in HCC using T1 mapping and the correlation between T1 mapping and
the prognosis of HCC after hepatectomy have not been well established.
Therefore, the purpose of this study was to preoperatively identify the CK19
expression status of HCC and to assess early recurrence after hepatectomy with
T1 mapping on gadoxetic acid-enhanced magnetic resonance imaging (MRI).Materials and methods
This retrospective study included 158 patients with surgically-proven
HCC who underwent preoperative T1 mapping on gadoxetic acid-enhanced MRI from
two institutions. Patients from institution I (n = 102) and institution II (n =
56) were assigned to training and test sets, respectively. This retrospective study
was approved by the Institutional Ethics Review Board; the patients were
exempted from signing informed consent.
MRI
examinations in all patients from institution I and institution II were
performed using a 1.5T (Magnetom Aera; Siemens Healthcare, Erlanger, Germany)
and 3.0T (Magnetom Trio A Tim; Siemens Healthcare) MR scanner, respectively.
The region of interest (ROI) was placed as far as
possible in the area with enhancement in lesions to avoid necrosis, hemorrhage,
fat, and artifacts. The area of ROI was approximately 1.0~1.5cm2;
the same lesion was measured three times with the same ROI, and then average
amounts were calculated.
Precontrast
and postcontrast T1 relaxation times were measured before and 20 min after the
contrast medium administration (recorded as T1rt-Pre and T1rt-HBP,
respectively), and the reduction rate of T1 relaxation time (rrT1rt) was
calculated. In addition, quantitative parameters also included the
tumor-to-liver contrast ratio (TLR), tumor enhancement index (TEI), relative
tumor enhancement (RTE), relative enhancement ratio (RER), and tumor-to-liver
ADC values (recorded as relative ADC, rADC).
Univariable and
multivariable logistic regression analyses were performed to investigate the
association of clinicoradiological variables and CK19. Prognostic factors
associated with early recurrence after surgical resection were identified using
Cox proportional hazard regression analyses. The R software (version 4.1.0) was used for the
analysis. All differences were considered statistically significant with a p-value
of <0.05.Results
For predicting CK19 expression, multivariable
logistic regression analysis showed AFP>400ng/ml (OR=4.607, 95%CI:
1.098-19.326; p=0.037), relative apparent diffusion coefficient (rADC)≤0.71 (OR=3.450, 95%CI: 1.126-10.567; p=0.030),
T1 relaxation time in the 20-minute hepatobiliary phase (T1rt-HBP)>797msec
(OR=4.509, 95%CI: 1.301-15.626; p=0.018) were significant independent
predictors of CK19 expression, and pre-enhanced T1 relaxation time (T1rt-Pre)>1437msec
(OR=2.974, 95%CI :0.957-9.235; p=0.059) was marginally significant as a
predictor of CK19 expression. The clinical-quantitative model (CQ-Model)
constructed based on these significant variables had the best predictive
performance with an area under the ROC curve of 0.844, an area under the precision-recall curve of 0.785 and an F1 score of 0.778. The nomogram constructed based on
CQ-model demonstrated satisfactory performance with C index of 0.844 (95%CI:
0.759-0.908) and 0.818 (95%CI: 0.693-0.902) in the training and test sets,
respectively.
For predicting early recurrence of HCC, multivariable Cox
analysis showed AFP>400ng/ml (HR:2.32, 95%CI: 1.07-5.06; p=0.034),
peritumoral hypointensity on hepatobiliary phase (HR:2.69, 95%CI: 1.31-5.54; p=0.007)
and T1rt-HBP>797msec (HR:6.15, 95%CI: 1.42-26.50; p=0.015) were
independent risk factors for early recurrence. Based on the independent risk
factors of early recurrence, a nomogram was developed to predict 6-month, 12-month,
and 24-month recurrence-free survival probabilities for HCC patients, and the C
index was 0.757 (95%CI: 0.686-0.828) and 0.685 (95%CI: 0.568-0.773) in the
training and test sets, respectively. Conclusion
T1 mapping based on gadoxetic acid-enhanced MRI exhibits
good predictive efficacy for preoperative prediction of CK19 expression and
early recurrence of HCC, which can improve individualized risk stratification
and further treatment decisions of HCC patients.Acknowledgements
We gratefully acknowledge all the members of
Department of Radiology, Guangzhou First People’s Hospital, for continuous
assistance. References
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