<p>In Vitro Intraductal MRI and T2 Mapping of Cholangiocarcinoma Using Catheter Coils</p>

Abstract

Aim Diagnostic imaging of early-stage cholangiocarcinoma is challenging. A previous in vitro study of fixed-tissue liver resection specimens investigated T2 mapping as a method of exploiting the locally increased signal-to-noise ratio (SNR) of duodenoscope coils for improved quantitative magnetic resonance imaging (MRI), despite their non-uniform sensitivity. This work applies similar methods to unfixed liver specimens using catheter-based receivers. Methods Ex vivo intraductal MRI and T2 mapping were carried out at 3T on unfixed resection specimens obtained from cholangiocarcinoma patients immediately after surgery using a catheter coil based on a thin-film magneto-inductive waveguide, inserted directly into an intrahepatic duct. Results Polypoid intraductal cholangiocarcinoma was imaged using fast spin-echo sequences. High-resolution T2 maps were extracted by fitting of data obtained at different echo times to mono-exponential models, and disease-induced changes were correlated with histopathology. An increase in T2 was found compared with fixed specimens and differences in T2 allowed the resolution of tumour tissue and malignant features such as polypoid morphology. Conclusion Despite their limited field of view, useful data can be obtained using catheter coils, and T2 mapping offers an effective method of exploiting their local SNR advantage without the need for image correction.

Modification of the AJCC/UICC 8th edition staging system for intrahepatic cholangiocarcinoma: proposal for an alternative staging system from cholangiocarcinoma-prevalent Northeast Thailand

“…It is hoped that after validation is completed, the KKU staging system will employed in clinical staging and for pre-operative detection of pre-invasive neoplasms of the bile ducts in conjunction with radiological studies. 46,47 In 2017, Luvira V. and Eurboonyanun K (co-authors in our study) investigated intraductal papillary neoplasms of the bile duct (IPNB) with survival correlation of CCA patients via radio-pathological staging. Their study showed that IPNB correlated with early stage and predicted survival very well 48,49 In the future, this study will be modified for incorporation into the KKU staging system in guiding planning of surgical procedures.…”

Intraductal magnetic resonance imaging of cholangiocarcinoma - a practical possibility

“…Parametric mapping of liver disease has already been demonstrated with external coils ( 19 , 20 ), and we have previously reported methodology for intraductal MRI. Work has focused on duodenoscope modification for MR environments ( 21 ), the production of catheter-based receivers ( 22 ), the verification of the local SNR advantage of catheter receivers over torso array coils ( 23 ) and initial ex vivo imaging studies of surgical specimens ( 24 ).…”

“…Technical challenges included developing the design concept, simulating electro-magnetic performance, integrating flexible circuits on catheters, connecting receivers to auxiliary coil interfaces, and performing initial assessments of RF heating potential. Imaging has been carried out using a clinically available whole-body 3T Philips Achieva™ (Philips, Best, the Netherlands) MRI system in Khon Kaen in North-East Thailand, the epicenter of liver fluke-associated cholangiocarcinoma ( 24 ). Clinical challenges included synchronizing imaging with surgery in a busy hospital, identifying specimens suitable for cannulation, and correlating T2 maps of CCA with histopathology for the first time.…”

“…Figure 2 shows data from an ex vivo resection specimen from a Thai patient with polypoid intraductal CCA, adapted and modified from a previous publication ( 24 ). Imaging was carried out at 3T using a catheter receiver on a resection specimen immediately post-surgery.…”

“…Figure 2E shows corresponding T2 maps, obtained from five excitations with TE between 9 ms and 95 ms . The tissue is well differentiated, and the assigned T 2 values were verified by histopathology ( 24 ). Resolution is high, and CCA-induced thickening of the duct wall is apparent; with the exclusion of T2 values below 45 ms ( Figure 2F ), the tumor boundary is clear and correlated well with Figure 2C .…”