Assessing the Effect of Weight-Based Protocol Modifications to Lower Dose for CT-Guided Hepatic and Renal Tumor Radiofrequency Ablations

Implementation of AI image reconstruction in CT-how is it validated and what dose reductions can be achieved

CT reconstruction has undergone a substantial change over the last decade with the introduction of iterative reconstruction (IR) and now with deep learning reconstruction (DLR). In this review, DLR will be compared to IR and filtered back-projection (FBP) reconstructions. Comparisons will be made using image quality metrics such as noise power spectrum, contrast-dependent task-based transfer function, and non-prewhitening filter detectability index (dNPW'). Discussion on how DLR has impacted CT image quality, low-contrast detectability, and diagnostic confidence will be provided. DLR has shown the ability to improve in areas that IR is lacking, namely: noise magnitude reduction does not alter noise texture to the degree that IR did, and the noise texture found in DLR is more aligned with noise texture of an FBP reconstruction. Additionally, the dose reduction potential for DLR is shown to be greater than IR. For IR, the consensus was dose reduction should be limited to no more than 15-30% to preserve low-contrast detectability. For DLR, initial phantom and patient observer studies have shown acceptable dose reduction between 44 and 83% for both low- and high-contrast object detectability tasks. Ultimately, DLR is able to be used for CT reconstruction in place of IR, making it an easy "turnkey" upgrade for CT reconstruction. DLR for CT is actively being improved as more vendor options are being developed and current DLR options are being enhanced with second generation algorithms being released. DLR is still in its developmental early stages, but is shown to be a promising future for CT reconstruction.

Radiofrequency ablation guided by cone beam computed tomography for hepatocellular carcinoma: a comparative study of clinical results with the conventional spiral computed tomography-guided procedure

Objective

To compare the outcomes of cone beam computed tomography (CBCT)-guided radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC) with those of traditional spiral computed tomography (s-CT)-guided RFA.

Methods

This retrospective study analysed data from patients with HCC that underwent RFA guided by either CBCT or s-CT. A number of preoperative and postoperative characteristics, including operation time, ablation time, radiation dose and hospital stay were recorded for all patients. The incidence of intraoperative and postoperative complications was recorded. The therapeutic effect was evaluated at 1, 3 and 6 months after RFA.

Results

A total of 47 patients with HCC (12 females and 35 males) underwent successful RFA: 21 underwent CBCT-guided RFA and 26 underwent s-CT-guided RFA. Except for one case of pneumothorax in the s-CT group, no serious complications occurred. The objective response rate and disease control rate at 1, 3 and 6 months after RFA showed no significant differences between the two groups. Throughout the 6-month follow-up period, the complete ablation rate was 19 of 21 patients (90.5%) in the CBCT group and 19 of 26 patients (73.1%) in the s-CT group.

Conclusions

CBCT was a safe and effective guiding modality for RFA in patients with HCC.