Virtual CT sonography using magnetic navigation provides cross sectional images of CT volume data corresponding to the angle of the transducer in the magnetic field in real-time. The purpose of this study was to clarify the value of this virtual CT sonography for treatment response of radiofrequency ablation for hepatocellular carcinoma.
Sixty-one patients with 88 HCCs measuring 0.5-1.3 cm (mean±SD, 1.0±0.3 cm) were treated by radiofrequency ablation. For early treatment response, dynamic CT was performed 1-5 days (median, 2 days). We compared early treatment response between axial CT images and multi-angle CT images using virtual CT sonography.
Residual tumor stains on axial CT images and multi-angle CT images were detected in 11.4% (10/88) and 13.6% (12/88) after the first session of RFA, respectively (P=0.65). Two patients were diagnosed as showing hyperemia enhancement after the initial radiofrequency ablation on axial CT images and showed local tumor progression shortly because of unnoticed residual tumors. Only virtual CT sonography with magnetic navigation retrospectively showed the residual tumor as circular enhancement. In safety margin analysis, 10 patients were excluded because of residual tumors. The safety margin more than 5 mm by virtual CT sonographic images and transverse CT images were determined in 71.8% (56/78) and 82.1% (64/78), respectively (P=0.13). The safety margin should be overestimated on axial CT images in 8 nodules.
Virtual CT sonography with magnetic navigation was useful in evaluating the treatment response of radiofrequency ablation therapy for hepatocellular carcinoma.
"Remote virtual sonography (RVS) involves fusion of US and CT/MRI images and is often achieved by tracking the US probe using EM technology . This technique is sometimes used for guidance of punctures without tracking the puncture needle itself, but instead using conventional US-guidance for needle insertion. "
[Show abstract][Hide abstract] ABSTRACT: Object tracking is a key enabling technology in the context of computer-assisted medical interventions. Allowing the continuous localization of medical instruments and patient anatomy, it is a prerequisite for providing instrument guidance to subsurface anatomical structures. The only widely used technique that enables real-time tracking of small objects without lineof- sight restrictions is electromagnetic (EM) tracking. While EM tracking has been the subject of many research efforts, clinical applications have been slow to emerge. The aim of this review paper is therefore to provide insight into the future potential and limitations of EM tracking for medical use. We describe the basic working principles of EM tracking systems, list the main sources of error, and summarize the published studies on tracking accuracy, precision and robustness along with the corresponding validation protocols proposed. State-of-the-art approaches to error compensation are also reviewed in depth. Finally, an overview of the clinical applications addressed with EM tracking is given. Throughout the paper, we report not only on scientific progress, but also provide a review on commercial systems. Given the continuous debate on the applicability of EM tracking in medicine, this paper provides a timely overview of the state-of-the-art in the field.
IEEE Transactions on Medical Imaging 05/2014; DOI:10.1109/TMI.2014.2321777 · 3.39 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Contrast enhanced ultrasound has recently been introduced and is recommended in daily practice in many circumstances, mainly for the detection and characterization of focal liver lesions. Also, contrast enhanced ultrasound has the potential of becoming the primary liver-imaging modality, preceding CT or MR, for the diagnosis of hepatocellular carcinoma in patients with cirrhosis, detection of liver metastases in oncology patients and guidance and assessment of the outcome of percutaneous tumor ablation procedure. Recently, a new imaging technique that combines in real-time, transabdominal ultrasound with CT or MR, has been introduced in clinical practice. Real-time virtual sonography uses a magnetic positioning system attached to the ultrasound probe in order to calculate the spatial position and to display both imaging methods in real-time. Benefits include an increased diagnostic confidence, direct comparison of the lesions using different imaging modalities, more precise monitoring of interventional procedures and reduced radiation exposure. We describe the role of real-time contrast-enhanced and real-time virtual sonography in the assessment of malignant liver lesions.
Journal of gastrointestinal and liver diseases: JGLD 04/2009; 18(1):103-8. · 2.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This study aimed to elucidate the efficacy of contrast-enhanced ultrasonography (CEUS) with perfluorobutane (Sonazoid(®)) in the diagnosis of hepatocellular carcinomas (HCCs), particularly small HCCs, by comparing the results with dynamic computed tomography (Dy-CT). Seventy-nine nodules in 69 patients with chronic liver disease, suspected as HCCs were studied. The nodules were selected based on the results of B-mode ultrasonography and/or Dy-CT conducted between January and August 2007. The nodules were divided into two groups: the S-group with tumors ≤2 cm (49 nodules), and the L-group with tumors >2 cm (30 nodules). Typical HCCs were defined, and the nodules were enhanced and shown as defects in the arterial and late phase of Dy-CT, respectively. Target lesions were scanned using CEUS, and the results were compared with those of Dy-CT. The L-group nodules diagnosed as HCCs using Dy-CT were also diagnosed as HCCs using CEUS. In the S-group, the diagnostic sensitivity of CEUS was 94.7% and the specificity was 81.8%. We diagnosed two liver tumors that were detected by CEUS but not by Dy-CT; biopsies revealed one tumor to be a well-differentiated HCC and the other to be an atypical adenomatous hyperplasia. The sensitivity and specificity of CEUS against HCC were high even in the small-size HCCs. Thus, Sonazoid is useful in the screening for small HCCs.
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