Adjuvant holmium-166 radioembolization after radiofrequency ablation in early-stage hepatocellular carcinoma patients: a dose-finding study (HORA EST HCC trial)

PURPOSE

The aim of this study was to investigate the biodistribution of (super-)selective trans-arterial radioembolization (TARE) with holmium-166 microspheres (166Ho-MS), when administered as adjuvant therapy after RFA of HCC 2-5 cm. The objective was to establish a treatment volume absorbed dose that results in an absorbed dose of ≥ 120 Gy on the hyperemic zone around the ablation necrosis (i.e., target volume).

METHODS

In this multicenter, prospective dose-escalation study in BCLC early stage HCC patients with lesions 2-5 cm, RFA was followed by (super-)selective infusion of 166Ho-MS on day 5-10 after RFA. Dose distribution within the treatment volume was based on SPECT-CT. Cohorts of up to 10 patients were treated with an incremental dose (60 Gy, 90 Gy, 120 Gy) of 166Ho-MS to the treatment volume. The primary endpoint was to obtain a target volume dose of ≥ 120 Gy in 9/10 patients within a cohort.

RESULTS

Twelve patients were treated (male 10; median age, 66.5 years (IQR, [64.3-71.7])) with a median tumor diameter of 2.7 cm (IQR, [2.1-4.0]). At a treatment volume absorbed dose of 90 Gy, the primary endpoint was met with a median absorbed target volume dose of 138 Gy (IQR, [127-145]). No local recurrences were found within 1-year follow-up.

CONCLUSION

Adjuvant (super-)selective infusion of 166Ho-MS after RFA for the treatment of HCC can be administered safely at a dose of 90 Gy to the treatment volume while reaching a dose of ≥ 120 Gy to the target volume and may be a favorable adjuvant therapy for HCC lesions 2-5 cm.

TRIAL REGISTRATION

Clinicaltrials.gov NCT03437382 . (registered: 19-02-2018).

MRI in patients with a cerebral aneurysm clip; review of the literature and incident databases and recommendations for the Netherlands

BACKGROUND

In the past ferromagnetic cerebral aneurysm clips that are contraindicated for Magnetic Resonance Imaging (MRI) have been implanted. However, the specific clip model is often unknown for older clips, which poses a problem for individual patient management in clinical care.

METHODS

Literature and incident databases were searched, and a survey was performed in the Netherlands that identified time periods at which ferromagnetic and non-ferromagnetic clip models were implanted. Considering this information in combination with a national expert opinion, we describe an approach for risk assessment prior to MRI examinations in patients with aneurysm clips. The manuscript is limited to MRI at 1.5 T or 3 T whole body MRI systems with a horizontal closed bore superconducting magnet, covering the majority of clinical Magnetic Resonance (MR) systems.

RESULTS

From the literature a list of ferromagnetic clip models was obtained. The risk of movement or rotation of the clip due to the main magnetic field in case of a ferromagnetic clip is the main concern. In the incident databases records of four serious incidents due to aneurysm clips in MRI were found. The survey in the Netherlands showed that from 2000 onwards, no ferromagnetic clips were implanted in Dutch hospitals.

DISCUSSION

Recommendations are provided to help the MR safety expert assessing the risks when a patient with a cerebral aneurysm clip is referred for MRI, both for known and unknown clip models. This work was part of the development of a guideline by the Dutch Association of Medical Specialists.

Study Protocol: Adjuvant Holmium-166 Radioembolization After Radiofrequency Ablation in Early-Stage Hepatocellular Carcinoma Patients-A Dose-Finding Study (HORA EST HCC Trial)

PURPOSE

To investigate the biodistribution of holmium-166 microspheres (¹⁶⁶Ho-MS) when administered after radiofrequency ablation (RFA) of early-stage hepatocellular carcinoma (HCC). The aim is to establish a perfused liver administration dose that results in a tumoricidal dose of holmium-166 on the hyperaemic zone around the ablation necrosis (i.e. target volume).

MATERIALS AND METHODS

This is a multicentre, prospective, dose-escalation study in HCC patients with a solitary lesion 2-5 cm, or a maximum of 3 lesions of ≤ 3 cm each. The day after RFA patients undergo angiography and cone-beam CT (CBCT) with (super)selective infusion of technetium-99 m labelled microalbumin aggregates (^99mTc-MAA). The perfused liver volume is segmented from the CBCT and ¹⁶⁶Ho-MS is administered to this treatment volume 5-10 days later. The dose of holmium-166 is escalated in a maximum of 3 patient cohorts (60 Gy, 90 Gy and 120 Gy) until the endpoint is reached. SPECT/CT is used to determine the biodistribution of holmium-166. The endpoint is met when a dose of ≥ 120 Gy has been reached on the target volume in 9/10 patients of a cohort. Secondary endpoints include toxicity, local recurrence, disease-free and overall survival.

DISCUSSION

This study aims to find the optimal administration dose of adjuvant radioembolization with ¹⁶⁶Ho-MS after RFA. Ultimately, the goal is to bring the efficacy of thermal ablation up to par with surgical resection for early-stage HCC patients.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT03437382.

Dosimetric feasibility of MRI-guided external beam radiotherapy of the kidney

At our institution a treatment for kidney tumours with an MRI-Linac is under development. In order to set inclusion criteria for this treatment the anatomical eligibility criteria and the influence of the motion compensation strategy on the delivered dose should be known. Twenty patients with a renal lesion underwent an MR-scan to image the kidney. Static treatment plans were made and the doses to the organs at risk were evaluated. Furthermore, to calculate the influence of remnant motion in a gated treatment, a convolution of the static dose plan with the residual motion in a gating window was done. For ten patients (50%) a static plan within the dose constraints could be obtained. For all patients where the kidney constraint was obeyed in the static plan, the dose to the gross tumour volume (GTV) and the ipsilateral kidney remained within limits for residual motion in a gating window up to and including 12 mm. For four patients (20%) no static plan without violation of the constraint to the ipsilateral kidney could be made. One of these patients had a tumour of 73 mm in the upper pole and the other patients had a tumour of at least 30 mm in the mid pole. In 6 patients (30%), where the bowels were within the planning target volume, the maximum dose to the bowels was above the limit used. Patient specific assessment might degrade this violation. For tumours smaller than 30 mm a clinically acceptable plan could be created. For other patients the feasibility depends on the geometry of the GTV and kidney. Neither the GTV coverage nor the ipsilateral kidney dose is compromised by breathing motion for gating with a gating window up to and including 12 mm.

Navigators for motion detection during real-time MRI-guided radiotherapy

An MRI-linac system provides direct MRI feedback and with that the possibility of adapting radiation treatments to the actual tumour position. This paper addresses the use of fast 1D MRI, pencil-beam navigators, for this feedback. The accuracy of using navigators was determined on a moving phantom. The possibility of organ tracking and breath-hold monitoring based on navigator guidance was shown for the kidney. Navigators are accurate within 0.5 mm and the analysis has a minimal time lag smaller than 30 ms as shown for the phantom measurements. The correlation of 2D kidney images and navigators shows the possibility of complete organ tracking. Furthermore the breath-hold monitoring of the kidney is accurate within 1.5 mm, allowing gated radiotherapy based on navigator feedback. Navigators are a fast and precise method for monitoring and real-time tracking of anatomical landmarks. As such, they provide direct MRI feedback on anatomical changes for more precise radiation delivery.