Learning Needle Placement in Soft Tissue With Robot-assisted Navigation.

BACKGROUND/AIM: The aim of this phantom study was to evaluate the learning curves of novices practicing how to place a cone-beam computed tomography (CBCT)-guided needle using a novel robotic assistance system (RAS). MATERIALS AND METHODS: Ten participants performed 18 punctures each with random trajectories in a phantom setting, supported by a RAS over 3 days. Precision, duration of the total intervention, duration of the needle placement, autonomy, and confidence of the participants were measured, displaying possible learning curves. RESULTS: No statistically significant differences were observed in terms of needle tip deviation during the trial days (mean deviation day 1: 2.82 mm; day 3: 3.07 mm; p=0.7056). During the trial days, the duration of the total intervention (mean duration: day 1: 11:22 min; day 3: 07:39 min; p<0.0001) and the duration of the needle placement decreased (mean duration: day 1: 03:17 min; day 3: 02:11 min; p<0.0001). In addition, autonomy (mean percentage of achievable points: day 1: 94%; day 3: 99%; p<0.0001) and confidence of the participants (mean percentage of achievable points: day 1: 78%; day 3: 91%; p<0.0001) increased significantly during the trial days. CONCLUSION: The participants were already able to carry out the intervention precisely using the RAS on the first day of the trial. Throughout the trial, the participants' performance improved in terms of duration and confidence.

Robotic Assistance System for Cone-Beam Computed Tomography-Guided Percutaneous Needle Placement.

PURPOSE: The study aimed to evaluate a new robotic assistance system (RAS) for needle placement in combination with a multi-axis C-arm angiography system for cone-beam computed tomography (CBCT) in a phantom setting. MATERIALS AND METHODS: The RAS consisted of a tool holder, dedicated planning software, and a mobile platform with a lightweight robotic arm to enable image-guided needle placement in conjunction with CBCT imaging. A CBCT scan of the phantom was performed to calibrate the robotic arm in the scan volume and to plan the different needle trajectories. The trajectory data were sent to the robot, which then positioned the tool holder along the trajectory. A 19G needle was then manually inserted into the phantom. During the control CBCT scan, the exact needle position was evaluated and any possible deviation from the target lesion measured. RESULTS: In total, 16 needle insertions targeting eight in- and out-of-plane sites were performed. Mean angular deviation from planned trajectory to actual needle trajectory was 1.12°. Mean deviation from target point and actual needle tip position was 2.74 mm, and mean deviation depth from the target lesion to the actual needle tip position was 2.14 mm. Mean time for needle placement was 361 s. Only differences in time required for needle placement between in- and out-of-plane trajectories (337 s vs. 380 s) were statistically significant (p = 0.0214). CONCLUSION: Using this RAS for image-guided percutaneous needle placement with CBCT was precise and efficient in the phantom setting.

Computer tomography guided thoracoscopic resection of small pulmonary nodules in the hybrid theatre.

PURPOSE: Thoracic surgeons are currently asked to resect smaller and deeper lesions which are difficult to detect thoracoscopically. The growing number of those lesions arises both from lung cancer screening programs and from follow-up of extrathoracic malignancies. This study analyzed the routine use of a CT-aided thoracoscopic approach to small pulmonary nodules in the hybrid theatre and the resulting changes in the treatment pathway. METHODS: 50 patients were retrospectively included. The clinical indication for histological diagnosis was suspected metastasis in 46 patients. Technically, the radiological distance between the periphery of the lesion and the visceral pleura had to exceed the maximum diameter of the lesion for the patient to be included. A spiral wire was placed using intraoperative CT-based laser navigation to guide the thoracoscopic resection. RESULTS: The mean diameter of the lesions was 8.4 mm (SD 4.27 mm). 29.4 minutes (SD 28.5) were required on average for the wire placement and 42.3 minutes (SD 20.1) for the resection of the lesion. Histopathology confirmed the expected diagnosis in 30 of 52 lesions. In the remaining 22 lesions, 9 cases of primary lung cancer were detected while 12 patients showed a benign disease. CONCLUSION: Computer tomography assisted thoracoscopic surgery (CATS) enabled successful resection in all cases with minimal morbidity. The histological diagnosis led to a treatment change in 42% of the patients. The hybrid-CATS technique provides good access to deeply located small pulmonary nodules and could be particularly valuable in the emerging setting of lung cancer screening.

Detectability of Lung Nodules in Ultra-low Dose CT.

BACKGROUND/AIM: Investigation of the influence of different ultra-low dose computed tomography (ULDCT) protocols on the detection of solid and subsolid nodules in a phantom study. PATIENTS AND METHODS: A chest phantom with pulmonary nodules was scanned with different CT protocols ranging from ultra-low dose settings with spectral shaping to a standard low dose lung cancer screening protocol. Image analysis was performed with different reconstruction algorithms and dedicated computer aided detection (CAD), which was compared to manual readout. RESULTS: The highest sensitivity rates (83%) were achieved for the 90 mAs and 120 mAs protocols when reconstructed with ADMIRE 3 or 5 and manual readout. The only statistically significant difference was found for subsolid nodules with preference of manual readout compared to CAD (p<0.05). Dose levels for the mAs settings ranged from 0.029 to 0.2 mSv. CONCLUSION: Reliable detectability rates for solid nodules were achieved; CAD software did not prove reliable for subsolid nodules.

Cost-Effectiveness Analysis of Local Ablation and Surgery for Liver Metastases of Oligometastatic Colorectal Cancer.

BACKGROUND: Colorectal cancer is among the most prevalent cancer entities worldwide, with every second patient developing liver metastases during their illness. For local treatment of liver metastases, a surgical approach as well as ablative treatment options, such as microwave ablation (MWA) and radiofrequency ablation (RFA), are available. The aim of this study is to evaluate the cost-effectiveness of RFA, MWA and surgery in the treatment of liver metastases of oligometastatic colorectal cancer (omCRC) that are amenable for all investigated treatment modalities. METHODS: A decision analysis based on a Markov model assessed lifetime costs and quality-adjusted life years (QALY) related to the treatment strategies RFA, MWA and surgical resection. Input parameters were based on the best available and most recent evidence. Probabilistic sensitivity analyses (PSA) were performed with Monte Carlo simulations to evaluate model robustness. The percentage of cost-effective iterations was determined for different willingness-to-pay (WTP) thresholds. RESULTS: The base-case analysis showed that surgery led to higher long-term costs compared to RFA and MWA (USD 41,848 vs. USD 36,937 vs. USD 35,234), while providing better long-term outcomes than RFA, yet slightly lower than MWA (6.80 vs. 6.30 vs. 6.95 QALYs for surgery, RFA and MWA, respectively). In PSA, MWA was the most cost-effective strategy for all WTP thresholds below USD 80,000 per QALY. CONCLUSIONS: In omCRC patients with liver metastases, MWA and surgery are estimated to provide comparable efficacy. MWA was identified as the most cost-effective strategy in intermediate resource settings and should be considered as an alternative to surgery in high resource settings.

Preservation of Organ Function in Locally Advanced Non-Metastatic Gastrointestinal Stromal Tumors (GIST) of the Stomach by Neoadjuvant Imatinib Therapy.

BACKGROUND: Neoadjuvant imatinib mesylate (IM) for advanced, non-metastatic gastrointestinal stromal tumors (GIST) of stomach is recommended to downsize the tumor prompting less-extensive operations and preservation of organ function. METHODS: We analyzed the clinical-histopathological profile and oncological outcome of 55 patients (median age 58.2 years; range, 30-86 years) with biopsy-proven, cM0, gastric GIST who underwent IM therapy followed by surgery with a median follow-up of 82 months. RESULTS: Initial median tumor size was 113 mm (range, 65-330 mm) and 10 patients started with acute upper GI bleeding. After a median 10 months (range, 2-21 months) of treatment, tumor size had shrunk to 62 mm (range, 22-200 mm). According to Response Evaluation Criteria In Solid Tumors version 1.0 and version 1.1 (RECIST 1.1), 39 (75%) patients had partial response and 14 patients had stable disease, with no progressive disease. At plateau response, 50 patients underwent surgery with an R0 resection rate of 94% and pathological complete response in 24%. In 12 cases (24%), downstaging allowed laparoscopic resection. The mean recurrence-free survival (RFS) was 123 months (95%CI; 99-147) and the estimated 5-year RFS was 84%. CONCLUSIONS: Neoadjuvant IM allowed stomach preservation in 96% of our patients with excellent long-term RFS, even when starting treatment during an episode of upper GI bleeding. Preservation of the stomach provides the physiological basis for the use of oral IM in the adjuvant or metastatic setting.

Contralateral Liver Hypertrophy and Oncological Outcome Following Radioembolization with 90Y-Microspheres: A Systematic Review.

Radioembolization with 90Y-microspheres has been reported to induce contralateral liver hypertrophy with simultaneous ipsilateral control of tumor growth. The aim of the present systematic review was to summarize the evidence of contralateral liver hypertrophy and oncological outcome following unilateral treatment with radioembolization. A systematic literature search using the MEDLINE, EMBASE, and Cochrane libraries for studies published between 2008 and 2020 was performed. A total of 16 studies, comprising 602 patients, were included. The median kinetic growth rate per week of the contralateral liver lobe was 0.7% and declined slightly over time. The local tumor control was 84%. Surgical resection after radioembolization was carried out in 109 out of 362 patients (30%). Although the available data suggest that radioembolization prior to major hepatectomy is safe with a promising oncological outcome, the definitive role of radioembolization requires assessment within controlled clinical trials.

Lesion Revascularisation Subsequent to Femoropopliteal Spot Stenting Using the Multi-LOC Stent Delivery System.

BACKGROUND/AIM: Restenosis and stent fractures are well-characterised treatment failures following femoropopliteal (FP) stent-based interventions. We aimed to determine patterns of restenosis and fracture rates following focal stenting of FP arteries. PATIENTS AND METHODS: This retrospective study investigated angiographic patterns of restenosis and the occurrence of stent fractures following focal FP stenting with the multiple stent delivery system VascuFlex® Multi-LOC. RESULTS: We identified 10 patients with 10 (of 129) FP lesions (mean length 11.7±4.6 cm) and a total of 51 (of 646) Multi-LOC stents that underwent clinically driven target lesion revascularizations (TLR) after 11.5±9.2 months, due to symptomatic recurrence of stenosis. None of the Multi-LOC stents had fractured. No isolated in-stent restenosis (>50%) was observed. Median diameter lumen loss was significantly more pronounced at the inter-stent segments (27.0%) compared to in-stent segments (7.8%, p=0.023). CONCLUSION: No evidence of fracture or susceptibility to stent-related restenosis using Multi-LOC stents was observed. Focal FP stenting may be more effective when combined with strategies known to reduce restenosis in non-stented artery segments.

Clinical and Quantitative MRI Perfusion Analysis of Osteoid Osteomas Before and After Microwave Ablation.

AIM: Evaluation of osteoid osteoma (OO) perfusion characteristics pre and post microwave ablation (MWA) using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) with clinical follow-up. MATERIALS AND METHODS: Patients with OO underwent T1-weighted 3D DCE-MRI at 3.0T pre and post MWA. Signal intensity (SI) and perfusion of lesions was measured. Patients answered a questionnaire for clinical follow-up. RESULTS: A total of 24 patients were included (mean age of 28 years; nine females); 21 DCE-MRI datasets were of sufficient quality for analysis. The mean SI of lesions, plasma flow, volume of distribution and pain level all decreased statistically significantly after ablation. CONCLUSION: Quantitative MRI-perfusion analysis allows for objective treatment evaluation after MWA of OO, plasma flow and volume of distribution seem to be reliable indicators for successful thermoablation. MWA is an effective treatment option for OO with a low risk profile and significant pain reduction after treatment.