Purpose: To systematically review all current evidence into the dose-response relation of yttrium-90 and holmium-166 selective internal radiation therapy (SIRT) in primary and secondary liver cancer. Methods: A standardized search was performed in PubMed (MEDLINE), Embase, and the Cochrane Library in order to identify all published articles on dose-response evaluation in SIRT. In order to limit the results, all articles that investigated SIRT in combination with other therapy modalities (such as chemotherapy) were excluded. Results: A total of 3038 records were identified of which 487 were screened based on the full text. Ultimately, 37 studies were included for narrative analysis. Meta-analysis could not be performed due to the large heterogeneity in study and reporting designs. Out of 37 studies, 30 reported a ‘mean dose threshold’ that needs to be achieved in order to expect a response. This threshold appears to be higher for hepatocellular carcinoma (HCC, 100–250 Gy) than for colorectal cancer metastases (CRC, 40–60 Gy). Reported thresholds tend to be lower for resin microspheres than when glass microspheres are used. Conclusion: Although the existing evidence demonstrates a dose-response relationship in SIRT for both primary liver tumours and liver metastases, many pieces of the puzzle are still missing, hampering the definition of standardized dose thresholds. Nonetheless, most current evidence points towards a target mean dose of 100–250 Gy for HCC and 40–60 Gy for CRC. The field would greatly benefit from a reporting standard and prospective studies designed to elucidate the dose-response relation in different tumour types.

After a lesion has been assessed adequately on multiparametric magnetic resonance imaging (mpMRI), magnetic resonance (MR)-guided biopsy (MRGB) is the logical next step. The choice of the MRGB technique, however, is difficult. To show the advantages and disadvantages of the three commonly used MRGB techniques-MRI-ultrasound fusion MRGB (fus-MRGB), direct in-bore MRGB (inbore-MRGB), and cognitive MRGB (cog-MRGB), and to determine when each of the techniques can be used. Based on expert opinion and literature overview, the advantages, disadvantages, and challenges of fus-MRGB, inbore-MRGB, and cog-MRGB are evaluated. Further, the clinical setting of each biopsy strategy is assessed. Based on expert opinion and literature data, the three biopsy procedures are evaluated, and the important pros and cons are determined. The basic concept of each biopsy technique is reviewed, which would result in a clinical recommendation. This will be shown in individual patients. The accompanying video shows how fus-MRGB and inbore-MRGB are performed in our hospital. An important advantage of fus-MRGB is its generally availability; however, it has fusion-error limitations. Although not supported by evidence, inbore-MRGB seems to be better suited for smaller lesions, but is rather expensive. Cog-MRGB is easy to use and inexpensive, but is more operator dependent as it requires knowledge about both ultrasound and MR images. Readers should be aware that our MRGB approach is largely based on expert opinion and, where possible, supported by evidence. This article and the accompanying video show different MRGB techniques. The advantages and disadvantages of the three biopsy techniques, as well as the clinical setting in which each biopsy strategy is being used in our hospital, are discussed. Fus-MRGB is our first choice for prostate biopsy. Direct inbore-MRGB is used in difficult lesions but is mainly used as a "problem solver" (eg, a negative biopsy with a high suspicion for clinically significant prostate cancer). In our opinion, cog-MRGB is best for sampling larger and diffuse lesions. This third surgery in motion contribution shows our approach in magnetic resonance (MR)-guided biopsy (MRGB). Fusion MRGB is our first choice for prostate biopsy. In-bore MRGB is used in selected, difficult cases, mainly as a problem solver. In our point of view, cognitive MRGB seems to be best for sampling larger lesions and diffuse processes.

Purpose: To assess the association between minimal ablative margin (MAM) and local tumor progression (LTP) following CT-guided thermal ablation of colorectal liver metastases (CRLM) in a multicenter cohort and across two confirmation software. Materials and methods: This multicenter retrospective study included patients who underwent CT-guided radiofrequency or microwave ablation for CRLM between 2009 and 2021 in three institutions. Three-dimensional (3D) MAM was retrospectively assessed using dedicated ablation confirmation software by automatic non-rigid (Ablation-fit) or semi-automatic rigid co-registration (SAFIR) of intraprocedural pre- and post-ablation contrast-enhanced CT scans by two independent reader teams blinded to patient outcomes. LTP was assessed on a per-tumor basis. Factors associated with LTP-free survival were assessed using multivariable Cox regression analysis. Results: Overall, 113 patients (mean age: 67 ± 10 years; 78 men) who underwent thermal ablation for 189 CRLM (mean diameter: 1.9 ± 1.1 cm) met the inclusion criteria. 173/189 (92%) CRLM could be successfully analyzed using both software. Over a median follow-up of 31 months (IQR: 22–47), 21 of 173 CRLM (12.1%) developed LTP. On multivariable analysis, 3D MAM was independently associated with LTP in both software (Ablation-fit: HR 0.47, 95% CI: 0.36–0.61, p < 0.001; SAFIR: HR 0.42, 95% CI: 0.32–0.55, p < 0.001). No LTP was observed in CRLM ablated with MAM ≥ 4 mm (Ablation-fit) and ≥ 5 mm (SAFIR). The per-tumor median absolute difference in MAM quantification between both software was 2 mm (IQR: 1–3). Conclusion: MAM was independently associated with LTP after thermal ablation of CRLM across multicenter data and two confirmation software. Ablations achieving a MAM ≥ 5 mm were associated with local control in both software. Clinical relevance statement: MAMs from intraprocedural contrast-enhanced CT were independently associated with LTP after thermal ablation of CRLM across multicenter data and two confirmation software, with a margin ≥ 5 mm associated with local control in both software. Key Points: Sufficient ablative margins are critical for local control following thermal ablation of CRLM. Intraprocedural CT-derived MAM was the only independent factor associated with LTP across two confirmation software. No LTP was observed in CRLM ablated with a MAM ≥ 5 mm.