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Shyn, Paul

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Shyn

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Paul

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Shyn, Paul
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    Estimated effective dose of CT-guided percutaneous cryoablation of liver tumors
    (Elsevier BV, 2012) Park, Byung Kwan; Morrison, Paul; Tatli, Servet; Govindarajulu, Usha; Tuncali, Kemal; Judy, Philip Frank; Shyn, Paul; Silverman, Stuart
    Purpose: To estimate effective dose during CT-guided cryoablation of liver tumors, and to assess which procedural factors contribute most to dose. Materials and methods: Our institutional review board approved this retrospective, HIPAA-compliant study. A total of 20 CT-guided percutaneous liver tumor cryoablation procedures were performed in 18 patients. Effective dose was determined by multiplying the dose length product for each CT scan obtained during the procedure by a conversion factor (0.015 mSv/mGy-cm), and calculating the sum for each phase of the procedure: planning, targeting, monitoring, and post-ablation survey. Effective dose of each phase was compared using a repeated measures analysis. Using Spearman correlation coefficients, effective doses were correlated with procedural factors including number of scans, ratio of targeting distance to tumor size, anesthesia type, number of applicators, performance of ancillary procedures (hydrodissection and biopsy), and use of CT fluoroscopy. Results: Effective dose per procedure was 72 ± 18 mSv. The effective dose of targeting (37.5 ± 12.5 mSv) was the largest component compared to the effective dose of the planning phase (4.8 ± 2.2 mSv), the monitoring phase (25.5 ± 6.8 mSv), and the post-ablation survey (4.1 ± 1.9 mSv) phase (p < 0.05). Effective dose correlated positively only with the number of scans (p < 0.01). Conclusions: The effective dose of CT-guided percutaneous cryoablation of liver tumors can be substantial. Reducing the number of scans during the procedure is likely to have the greatest effect on lowering dose.
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    Multimodality Non-rigid Image Registration for Planning, Targeting and Monitoring During CT-Guided Percutaneous Liver Tumor Cryoablation
    (Elsevier BV, 2010) Elhawary, Haytham; Oguro, Sota; Tuncali, Kemal; Morrison, Paul; Tatli, Servet; Shyn, Paul; Silverman, Stuart; Hata, Nobuhiko
    Rationale and Objectives: To develop non-rigid image registration between pre-procedure contrast enhanced MR images and intra-procedure unenhanced CT images, to enhance tumor visualization and localization during CT-guided liver tumor cryoablation procedures. Materials and Methods: After IRB approval, a non-rigid registration (NRR) technique was evaluated with different pre-processing steps and algorithm parameters and compared to a standard rigid registration (RR) approach. The Dice Similarity Coefficient (DSC), Target Registration Error (TRE), 95% Hausdorff distance (HD) and total registration time (minutes) were compared using a two-sided Student’s t-test. The entire registration method was then applied during five CT-guided liver cryoablation cases with the intra-procedural CT data transmitted directly from the CT scanner, with both accuracy and registration time evaluated. Results: Selected optimal parameters for registration were section thickness of 5mm, cropping the field of view to 66% of its original size, manual segmentation of the liver, B-spline control grid of 5×5×5 and spatial sampling of 50,000 pixels. Mean 95% HD of 3.3mm (2.5x improvement compared to RR, p<0.05); mean DSC metric of 0.97 (13% increase); and mean TRE of 4.1mm (2.7x reduction) were measured. During the cryoablation procedure registration between the pre-procedure MR and the planning intra-procedure CT took a mean time of 10.6 minutes, the MR to targeting CT image took 4 minutes and MR to monitoring CT took 4.3 minutes. Mean registration accuracy was under 3.4mm. Conclusion: Non-rigid registration allowed improved visualization of the tumor during interventional planning, targeting and evaluation of tumor coverage by the ice ball. Future work is focused on reducing segmentation time to make the method more clinically acceptable.
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    Publication
    Unusual tumour ablations: report of difficult and interesting cases
    (Cancer Intelligence, 2017) Mauri, Giovanni; Nicosia, Luca; Varano, Gianluca Maria; Shyn, Paul; Sartori, Sergio; Tombesi, Paola; Di Vece, Francesca; Orsi, Franco; Solbiati, Luigi
    Image-guided ablations are nowadays applied in the treatment of a wide group of diseases and in different organs and regions, and every day interventional radiologists have to face more difficult and unusual cases of tumour ablation. In the present case review, we report four difficult and unusual cases, reporting some tips and tricks for a successful image-guided treatment.