Page 13 - ARNM-3-1

Advances in Radiotherapy
& Nuclear Medicine Diagnostics gude of biliary tract cancer

MR imaging for HCC. LI-RADS emerges as an essential arterial MRI enhancement may also serve as a prognostic
tool in the management of liver tumors. CT remains one of marker in the pre-operative evaluation of patients with
the primary tools in cancer diagnostics, particularly useful resectable intrahepatic mass-forming bile duct cancer, as
for imaging bone structures. This examination enables the demonstrated by Min et al. 73
detection of tumors and metastases, precise planning of On dynamic MR images, biliary tract cancer shows
radiotherapy (allowing for focused radiation delivery), and moderate peripheral enhancement, followed by progressive
monitoring of treatment response, including the reduction and concentric filling of the tumor with contrast material.
or growth of tumors. 60
Contrast accumulation within the tumor on delayed MRI
64
2.3. MRI phases suggests peripheral bile duct cancer. Massive
intraductal lesions may appear hypointense or isointense
MRI is the non-invasive method of choice for detection, on T1-weighted (T1W) images relative to the liver
pre-operative staging, and follow-up on biliary tract parenchyma. On T2-weighted (T2W) images, tumors
cancer. 61-64 When combined with MRCP, MRI is optimal may show variable hyperintensity, as the signal intensity
for evaluating bile ducts both above and below their depends on the severity of necrosis, hemorrhage, fibrosis,
strictures. It also allows the identification of intrahepatic and mucinous material within the tumor. Central
61
mass lesions. The primary role of MRI in biliary tract hypointensity may correspond to fibrosis. The degree of
64
cancer is to confirm or establish the diagnosis, assess the tumor hyperintensity also depends on the tumor subtype:
possibility of resection, and aid in differential diagnosis. 64-66 adenocarcinoma is characterized by higher signal intensity,
MRCP is considered one of the most advanced imaging especially when well-differentiated, while squamous cell
technologies and offers several advantages over CT. carcinomas are characterized by lower signal intensity. In
63
Due to their high tissue contrast and multifaceted some cases, the tumor may appear as an isointense mass
capabilities, MRI and MRCP are effective in detecting and on both T1W and T2W images. pCCAs exhibit similar
74
preoperatively evaluating patients with biliary tract cancer, signal intensity patterns to peripheral tumors on both
allowing detailed examination of all involved structures, T1W and T2W images. On MRCP images, pCCA appears
such as the bile ducts, vessels, and liver parenchyma. as moderately irregular thickening of the bile duct wall
64
MRCP has demonstrated the highest sensitivity and (≥5 mm) with symmetric widening of the intrahepatic bile
specificity (92% and 76%, respectively) in identifying the ducts. The typical appearance of massive iCCA consists
64
64
extension of pCCA. The role of MRI in diagnosing CCA of irregular annular enhancement in the arterial phase,
has been well-established through numerous studies. For followed by progressive central enhancement in the portal
example, Xu et al. showed that MRI could differentiate vein and delayed phase. An atypical presentation, such as
67
CCA from metastatic colorectal cancer. Moreover, as hypervascular massive iCCA, can also occur and may be
demonstrated in a study by Zhang et al., MRI texture attributed to different pathological features. 75
68
signatures can serve as a potential predictive biomarker
for immunophenotyping and overall survival in patients The quality of MRCP imaging is largely independent
with iCCA. The utility of MRI in predicting therapeutic of the operator, but careful technique is required to obtain
68
response was also tested by Sheng et al., who found that accurate results. MRCP imaging can be compromised by
69
contrast-enhanced MRI performed before treatment could previous biliary drainage, as this procedure may lead to the
predict therapeutic response in advanced iCCA to systemic collapse of the biliary tree. The combination of MRCP and
therapy. They also determined that the best predictive MR angiography can provide valuable information on the
value was achieved by a combined model incorporating involvement of vascular structures at the hilum. Compared
key MRI features. Similar findings were reported by Koh to ERCP, MRCP is a more sophisticated and commonly
et al., who showed that hepatobiliary phase MRI images used technique for identifying tumor location and
70
could serve as a prognostic factor after surgery for massive assessing the resectability of a pCCA. However, the use of
63
intrahepatic bile duct carcinomas, likely due to the fibrous MRI in standard diagnostic protocols has some limitations.
component of the tumor stroma. MRI can also predict These limitations include the high cost of the examination,
survival and prognosis in patients with eCCA. In a study failure to detect microcalcifications, and the possibility of
involving 78 patients with histopathologically confirmed false-positive results, often due to difficulty distinguishing
cancer, Wang et al. demonstrated that MRI could be malignant from benign tumors. Other problems include
71
used to predict survival and prognosis in these patients. patient-related issues, such as claustrophobia (which can
In addition, Xin et al. showed that high-resolution be problematic for both children and adults), various
72
MRI images have excellent capability in assessing the contraindications, such as metal implants or permanent
extent of pCCA and its vascular invasion. The pattern of makeup, and potential allergic reactions to contrast agents.

Volume 3 Issue 1 (2025) 5 doi: 10.36922/arnm.4557