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Della Corte et al. Hepatoma Res 2022;8:5 https://dx.doi.org/10.20517/2394-5079.2021.103 Page 3 of 15

In this short review, we will describe the current state of art diagnostic methods and the prognostic value of
imaging in ICC and peCC, as well as the loco-regional therapeutic strategies for unresectable ICC.

DIAGNOSTIC IMAGING
Imaging choice is essential for correct tumor assessment and for the best patient management prior to,
during, and after therapy. A multimodality approach, which includes CT, MRI with MRCP and PET, is
usually necessary to reach a final diagnosis and correctly identify and select patients who may undergo
surgery [Figures 1-3]. Imaging has a high negative predictive value with respect to resectability [20,21] .
Additional information may be collected using endoscopic retrograde cholangiopancreatography for
completion of histological diagnosis if not already available.

Multidetector computerd tomography
Multiphasic contrast-enhanced CT scan has a well-documented role in diagnosis, tumor staging, and
preoperative assessment of both peCC and ICC [9,22,23] . It also offers clinical information regarding local
staging (e.g., relationship with hepatic ducts and vessels) and assessment of metastatic disease. The scan(s)
should be obtained in the four phases: pre-contrast, arterial, portal, and delayed (3-5 min) post-contrast
phases for evaluating enhancement patterns of the mass. The pre-contrast phase is useful in identifying
[24]
predisposing peCC conditions such as intrahepatic stones, while post-contrast imaging is useful for
differential diagnosis of ICC given its abundance in fibrous stroma.

CT is generally the most commonly used imaging for upfront staging, and it is the modality used to describe
vascular and intrahepatic involvement such as relationship with hepatic ducts and vessels. Fusion imaging
techniques and three-dimensional CT angiography are useful in planning surgery, reducing time of
[25]
intervention .

MRI - MRCP
Currently, MRI is the most common imaging method used to diagnose perihilar CC. Two-dimensional and
three-dimensional (3D) MR cholangiography is considered to be the best non-invasive modality to evaluate
the biliary system and correctly assess intraductal lesions. Heavily T2-weighted sequences, such as half-
Fourier acquisition single-shot turbo spin echo or single-shot fast spin echo, can be used to distinguish the
hyperintense signal in the bile ducts from the remaining suppressed signal when performing MRCP. MRI
protocol should include axial and coronal T2-weighted sequences, dynamic study using T1-fat suppressed
sequences such as DIXON, and diffusion imaging. MRI is more sensitive than CT for the detection of
intrahepatic metastasis and extremely useful in pre-operative assessment [26,27] . Gadoxetic acid-enhanced
MRI, in particular, is particularly sensitive in the hepatobiliary phase [28,29] , due to hepatocyte uptake leading
to clear parenchymal enhancement. In addition, diffusion-weighted (DWI) sequences, performed using 0-
100 s/mm and 800-1000 s/mm for low- and high-b values, increases sensitivity of detection .
[30]
2
2
Preoperative MRI is commonly performed in patients with CC in order to assess the extent, resectability,
and vascular involvement of the tumor. It is also used to map hepatic vessels and identify vascular anatomic
variants since an accurate preoperative assessment of liver vasculature has been shown to significantly affect
[31]
the surgical outcome in patients with CC .

Park et al. nearly two decades ago compared the diagnostic performance of MRCP with that of combined
[32]
MDCT-angiography and found comparable results between the two techniques. MRCP sequences are
usually acquired using both (radial) thick-slab- and thin 3D T2 sequences; the former provides a
comprehensive overview of the biliary system with a good suppression of the surrounding tissue. Thin T2