(1) Background: Percutaneous microwave ablation (MWA) is an accepted treatment of non-operative liver cancer. This study compares the ablation zones of four commercially available 2.45 GHz MWA systems (Emprint, Eco, Neuwave, and Solero) in an ex vivo porcine liver model. (2) Methods: Ex vivo porcine livers (n = 85) were obtained. Two ablation time setting protocols were evaluated, the manufacturer’s recommended maximum time and a 3 min time, performed at the manufacturer-recommended maximum power setting. A total of 236 ablation samples were created with 32 (13.6%) samples rejected. A total of 204 samples were included in the statistical analysis. (3) Results: For single-probe protocols, Emprint achieved ablation zones with the largest SAD. Significant differences were found in all comparisons for the 3 min time setting and for all comparisons at the 10 min time setting except versus Neuwave LK15 and Eco. Emprint produced ablation zones that were also significantly more spherical (highest SI) than the single-probe ablations from all other manufacturers. No statistical differences were found for ablation shape or SAD between the single-probe protocols for Emprint and the three-probe protocols for Neuwave. (4) Conclusions: The new Emprint HP system achieved large and spherical ablation zones relative to other 2.45 GHz MWA systems.
Presence of microvascular invasion (MVI) indicates poorer prognosis post-curative resection of hepatocellular carcinoma (HCC), with an increased chance of tumour recurrence. By present standards, MVI can only be diagnosed post-operatively on histopathology. Texture analysis potentially allows identification of patients who are considered 'high risk' through analysis of pre-operative magnetic resonance imaging (MRI) studies. This will allow for better patient selection, improved individualised therapy (such as extended surgical margins or adjuvant therapy) and pre-operative prognostication.This study aims to evaluate the accuracy of texture analysis on pre-operative MRI in predicting MVI in HCC.Retrospective review of patients with new cases of HCC who underwent hepatectomy between 2007 and 2015 was performed. Exclusion criteria: No pre-operative MRI, significant movement artefacts, loss-to-follow-up, ruptured HCCs, previous hepatectomy and adjuvant therapy. Fifty patients were divided into MVI (n = 15) and non-MVI (n = 35) groups based on tumour histology. Selected images of the tumour on post-contrast-enhanced T1-weighted MRI were analysed. Both qualitative (performed by radiologists) and quantitative data (performed by software) were obtained. Radiomics texture parameters were extracted based on the largest cross-sectional area of each tumor and analysed using MaZda software. Five separate methods were performed. Methods 1, 2 and 3 exclusively made use of features derived from arterial, portovenous and equilibrium phases respectively. Methods 4 and 5 made use of the comparatively significant features to attain optimal performance.Method 5 achieved the highest accuracy of 87.8% with sensitivity of 73% and specificity of 94%.Texture analysis of tumours on pre-operative MRI can predict presence of MVI in HCC with accuracies of up to 87.8% and can potentially impact clinical management.
Background: Chest radiography (CXR) is performed more widely and readily than CT for the management of coronavirus disease (COVID-19), but there remains little data on its clinical utility. This study aims to assess the diagnostic performance of CXR, with emphasis on its predictive value, for severe COVID-19 disease. Methods: A retrospective cohort study was conducted, 358 chest radiographs were performed on 109 COVID-19 patients (median age 44.4 years, 58 males and 30 with comorbidities) admitted between 22 January 2020 and 15 March 2020. Each CXR was reviewed and scored by three radiologists in consensus using a 72-point COVID-19 Radiographic Score (CRS). Disease severity was determined by the need for supplemental oxygen and mechanical ventilation. Results: Patients who needed supplemental oxygen (n=19, 17.4%) were significantly older (P<0.001) and significantly more of them had co-morbidities (P=0.011). They also had higher C-reactive protein (CRP) (P<0.001), higher lactate dehydrogenase (LDH) (P<0.001), lower lymphocyte count (P<0.001) and lower hemoglobin (Hb) (P=0.001). Their initial (CRSinitial) and maximal CRS (CRSmax) were higher (P<0.001). Adjusting for age and baseline hemoglobin, the AUROC of CRSmax (0.983) was as high as CRPmax (0.987) and higher than the AUROC for lymphocyte countmin (0.897), and LDHmax (0.900). The AUROC for CRSinitial was slightly lower (0.930). CRSinitial ≥5 had a sensitivity of 63% and specificity of 92% in predicting the need for oxygen, and 73% sensitivity and 88% specificity in predicting the need for mechanical ventilation. CRS between the 6th and 10th day from the onset of symptoms (CRSD6-10) ≥5 had a sensitivity of 89% and specificity of 95% in predicting the need for oxygen, and 100% sensitivity and 86% specificity in predicting the need for mechanical ventilation. Conclusions: Adjusting for key confounders of age and baseline Hb, CRSmax performed comparable to or better than laboratory markers in the diagnosis of severe disease. CXR performed between the 6th and 10th days from symptom onset was a better predictor of severe disease than CXR performed earlier at presentation. A benign clinical course was seen in CXR that were normal or had very mild abnormalities.
Objective To explore various microwave (MW) time/power combinations to achieve maximum single-probe system performance in a live pig liver model.Methods Fifty-one microwave ablations performed in 12 female pigs using the following time/power combinations: 65 W for 10 min (65W 10MIN), ramped from 20 to 65 W (RAMPED), 95 W pulses with cooling periods (95W PULSED), 40 W for 16 min 15 s (LOW POWER), 1 min 95 W pulse then 8 min 65 W then a second 1 min 95 W pulse (BOOKEND 95W) and 65 W for 15 min (65W 15MIN). Temperatures 1.5 cm from the antenna were measured. Livers were excised, and ablations were measured and compared.Results At fixed overall energy, LOW POWER produced ablation zones with the smallest volume compared to 65W 10MIN, RAMPED and 95W PULSED. At a fixed time of 10-min, BOOKEND 95W protocol achieved wider and larger ablation zones than 65W 10MIN (p = 0.038, p = 0.008) and 95W PULSED (p = 0.049, p = 0.004). The 65W 15MIN combination had significantly larger diameters (p = 0.026), larger lengths (p = 0.014) and larger volumes (p = 0.005) versus 65W 10MIN. Maximum temperatures were highest with BOOKEND 95W (62.9 °C) and 65 W 15 MIN (63.0 °C) and lowest with LOW POWER (45.9 °C), p = 0.009.Conclusions Low power ablations, even if controlled for total energy delivery, create small ablation zones. High peak powers are associated with larger ablation zones and high margin temperatures if cooling pauses are avoided. Ramping and pulsing protocols with interleaved cooling appear to be of no benefit versus continuous 65 W for creating large ablation zones.
Coronavirus disease 2019 (COVID-19) is caused by the severe acute respiratory syndrome coronavirus 2 and was declared a global pandemic by the World Health Organization on 11 March 2020. A definitive diagnosis of COVID-19 is made after a positive result is obtained on reverse transcription-polymerase chain reaction assay. In Singapore, rigorous contact tracing was practised to contain the spread of the virus. Nasal swabs and chest radiographs (CXR) were also taken from individuals who were suspected to be infected by COVID-19 upon their arrival at a centralised screening centre. From our experience, about 40% of patients who tested positive for COVID-19 had initial CXR that appeared “normal”. In this case series, we described the temporal evolution of COVID-19 in patients with an initial “normal” CXR. Since CXR has limited sensitivity and specificity in COVID-19, it is not suitable as a first-line diagnostic tool. However, when CXR changes become unequivocally abnormal, close monitoring is recommended to manage potentially severe COVID-19 pneumonia. Key words: Diagnostic Radiology, Infectious Diseases, Pulmonary
Percutaneous ablation is an accepted treatment modality for primary hepatocellular carcinoma (HCC) and liver metastases. The goal of curative ablation is to cause the necrosis of all tumour cells with an adequate margin, akin to surgical resection, while minimising local damage to non-target tissue. Aside from the ablative modality, the proceduralist must decide the most appropriate imaging modality for visualising the tumour and monitoring the ablation zone. The proceduralist may also employ protective measures to minimise injury to non-target organs. This review article discusses the important considerations an interventionalist needs to consider when performing the percutaneous ablation of liver tumours. It covers the different ablative modalities, image guidance, and protective techniques, with an emphasis on new and advanced ablative modalities and adjunctive techniques to optimise results and achieve satisfactory ablation margins.
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