Cone-beam CT during TACE: a useful tool!

Clinical History

Male patient, 62 years old. Well-compensated exotoxic chronic liver disease. Diabetes mellitus. In December 2015 a CT scan revealed a 2.3 cm HCC nodule on the fourth segment (Fig. 1a-c). Due to low visibility at US investigation and to the unfavourable site for thermal ablation (Fig. 1d) a TACE treatment was scheduled.

Imaging Findings

Preliminary selective angiography of left hepatic artery confirmed the nodule (Fig. 2). After advancement of microcatheter (Prowler Plus, Johnson&Johnson) and microguidewire (Phatom, Boston) the segmental branch for segment 4 was catheterized (Fig. 3) and the correct position confirmed (Fig. 4). Cone-beam CT was performed with Integris Allura FD20Xper system (Philips Medical Systems, The Netherlands), during hand-injection of 5 ml of contrast media through the microcatheter and the correct position was confirmed, showing a dense opacification of segment 4 and of the nodule (Fig. 5). Thus drug eluting beads (DCbeads Biocompatibles) precharged with doxorubicin were slowly injected. A single-shot film at the end of drug injection confirmed the good filling of the nodule (Fig. 6) and for this reason CBCT was not repeated. A CT scan after 30 days confirmed the complete response using MRECIST criteria of the treated lesion (Fig. 7).

Discussion

CBCT has proved to be a useful tool in different angiographic and interventional procedures, mainly in the neurointerventions [1-3], but also for extracranial treatments such as embolization procedures in the pelvic arteries [4]. Some authors have focused on CBCT in liver TACE for the treatment of HCC, proving that it provides sufficient information for subsegmental chemoembolization by depicting tumours and their feeders in the majority of patients, and therefore helps to evaluate treatment success during the procedure [5-7].
Superselective catheterization with microcatheters does not always allow a good visualization of HCC nodules, especially when they are small and with poor enhancement and located in critical areas (i.e. subdiaphragmatic region). In these cases emerges the ability of CBCT to confirm the correct enhancement of the nodule and of the hepatic segment, which must match the previous axial imaging obtained with CT or MR scan. Sometimes, though, if the tip of the microcatheter is not in the correct feeding artery the CBCT acquisition does not confirm the nodule, therefore a second or even a third rotational angiography after superselective catheterization of another segmental branch is needed.
Moreover, CBCT supplies a more precise and faster identification also of nodules to treat that are not immediately visible with the conventional seriography, and sometimes even with the CBCT images (especially those nodules localized immediately below the diaphragm), thanks to a tool called "imaging fusion", that allows to merge the CBCT images with those of the diagnostic CT or MR obtained before the procedure. Thanks to this technique also nodules that appeared to be barely identifiable can be treated more easily and precisely. In our preliminary experience the routine use of CBCT during TACE has significantly improved the number of complete response using the mRECIST criteria, compared to what we obtained in the past with standard-TACE procedures.
The main limitations of this technique are given by the fact that a rotational acquisition in very obese patients cannot be performed and that the field of view of the rotational scan of the angiography cannot go over 28 cm of diameter, making it sometimes difficult to acquire the whole volume of the liver in a single scan.
Concerning radiation dose with CBCT, an inferior value in the dose/area product (DAP) was observed compared to the standard-TACE and we explain this result due to the inferior number of seriographies necessary to detect and catheterize the nodule.

Differential Diagnosis List

Final Diagnosis

Hepatocellular carcinoma

URL:	https://eurorad.org/case/13594
DOI:	10.1594/EURORAD/CASE.13594
ISSN:	1563-4086