Role of PET/MRI in CCA

At the 5th annual CCA Summit meeting, Nadine Mallak, MD, discussed the role of positron emission tomography/magnetic resonance imaging (PET/MRI) in cholangiocarcinoma (CCA). Advantages of PET/MRI are simultaneous acquisition, with better motion correction and less misregistration artifact, and long (15-20 min) PET acquisition on area of interest; however, it has limited use in lung and mesentery evaluation.¹

Computed tomography (CT) was found to be inadequate for preoperative diagnosis of the known negative prognostic factor multiple tumor foci; liver-protocol MRI was recommended as the standard preoperative imaging modality in nonmetastatic intrahepatic cholangiocarcinoma (iCCA).²

F-18 fludeoxyglucose (FDG) PET/CT is an important imaging tool in the nodal staging and detection of distant metastases in patients with CCA in certain situations, such as if identification of occult sites of disease may alter management or to identify relapse if suspicion remains following standard imaging.¹ However, a high proportion of fibrous stroma may decrease the degree of FDG avidity. Sensitivity depends on morphology and location, with sensitivity higher in nodular forms and peripherally located lesions versus infiltrating and hilar lesions.¹

Combination of PET/MRI was found to be more effective in CCA. In 100 patients with CCA, PET/MRI showed higher sensitivity in detection of metastatic disease compared with multiphase CT and was able to differentiate local recurrence post–surgical resection from postoperative changes (fibrosis or biliary stricture).³ In 37 patients with treatment-naïve iCCA, PET/MRI modified clinical management in 29.7% of patients, with surgery cancelled due to identification of additional disease or significant change in operative plan based on PET/MRI results.⁴

Dr Mallak proposed that a future direction will be evaluation of the performance of PET/MRI for the detection and assessment of treatment response of hepatic arterial infusion (HAI) therapy in the HELIX 2 trial, which combines HAI therapy with first-line gemcitabine/cisplatin and durvalumab for unresectable liver-only iCCA.¹

Sources:

1. Mallak N. Role of PET/MRI in cholangiocarcinoma. Presented at: 5th Annual CCA Summit Meeting, October 19-21, 2023; Scottsdale, AZ.
2. Sutton TL, Billingsley KG, Walker BS, et al. Detection of tumor multifocality in resectable intrahepatic cholangiocarcinoma: defining the optimal pre-operative imaging modality. J Gastrointest Surg. 2021;25:2250-2257.
3. Yoo J, Lee JM, Yoon JH, Joo I, Lee DH. Additional value of integrated 18F-FDG PET/MRI for evaluating biliary tract cancer: comparison with contrast-enhanced CT. Korean J Radiol. 2021;22(5):714-724.
4. Ferrone C, Goyal L, Qadan M, et al. Management implications of fluorodeoxyglucose positron emission tomography/magnetic resonance in untreated intrahepatic cholangiocarcinoma. Eur J Nucl Med Mol Imaging. 2020;47(8):1871-1884.