Image-guided microwave thermoablation of hepatic tumours using novel robotic guidance: an early experience.

OBJECTIVE: To evaluate and compare novel robotic guidance and manual approaches based on procedural accuracy, procedural time, procedural performance, image quality as well as patient dose during image-guided microwave thermoablation. METHOD: The study was prospectively performed between June 2013 and December 2013 using 70 patients. Forty randomly selected patients (group 1) were treated with manual guidance and 30 patients (group 2) were treated using a novel robotic guidance. Parameters evaluated were procedural accuracy, total procedural time, procedural performance, quantitative/qualitative image quality and patient dose. Two-sided Student's t test and Wilcoxon rank-sum test were used to test the significance of the data and p values less than 0.05 were considered statistically significant. RESULT: Accuracy parameters were significantly higher in group 2 (all p < 0.05). Total procedural time showed a mean time difference of 3 min (group 2 > group 1; p = 0.0008). Volume CT dose index and dose-length product were significantly lower for group 2 compared to group 1 (all p < 0.05) for CT fluoroscopy imaging. Total procedural performance score was higher for group 2 compared to group 1 (p = 0.0001). Image quality parameters were insignificant between examined groups. CONCLUSION: The novel robotic guided approach improved the accuracy of targeting the target tumour, reduced patient dose and increased procedural performance (which influences the procedural safety) during ablation. KEY POINTS: • Few reports are available in the literature regarding robotic-assisted liver microwave ablation. • The robotic guided approach improved accuracy of localizing the target tumour. • Radiation dose on patients was reduced with the robotic guidance. • Numbers of insertions and readjustments were reduced, lowering chances of complications.

Ultrafast cone-beam computed tomography imaging and postprocessing data during image-guided therapeutic practice.

OBJECTIVE: Our objective was to evaluate ultrafast cone-beam computed tomography (u-CBCT) image data using cross-sectional images, perfusion blood volume (PBV), and image fusion during tumour detection at the course of transarterial chemoembolization. METHODS: One hundred and fifty patients (63 ± 20 years; 33-82) were examined from February to October 2013 with u-CBCT. Tumour delineation and conspicuity were determined using u-CBCT cross-sectional PBV and u-CBCT-magnetic resonance imaging (MRI) fused data sets for hyperenhanced (HYET), heterogeneously enhanced (HEET), and unenhanced (UET) tumour categories. Catheter localisation and tumour feeding vessels were assessed using all data sets. Quantitative and qualitative analyses were performed using appropriate statistical tests. RESULT: Qualitative and quantitative tumour delineation showed significant difference (all P < 0.05) among tumour categories. Mean tumour-liver-contrast was higher in HYET than in HEET, and UET; moreover, differences between tumour categories were statistically significant (all P < 0.0001). Fused data showed higher value with statistical significance (P < 0.05) compared with other data sets during catheter localisation and feeding-vessel identification. CONCLUSION: Tumour delineation was clearly possible using u-CBCT cross sections with contrast material. PBV uses color-coded images to increase detection and produces good tumour differentiation. Image fusion helps accurately identify tumour and feeding vessels and locate contrast material injection sites and catheter tips without additional data acquisition. KEY POINTS: • Ultrafast CBCT cross-sectional data provide good tumour delineation with contrast material • Postprocessed PBV using u-CBCT increased detectability and tumour differentiation • u-CBCT cross-sectional PBV and u-CBCT-MRI data helps image guidance during chemoembolization • u-CBCT-MRI can identify tumours and feeding vessels and locate catheter tip accurately.

Oncological applications of dual-energy computed tomography imaging.

Dual-energy computed tomography (DECT) imaging is a promising method used in oncology for accurate detection/diagnosis of malignant and benign lesions. Use of dual-energy spectral, weighted average, color-coded map, and virtual unenhanced images provides increased visual detection and easy lesion delineation. Lesion detectability, sensitivity, and conspicuity are significantly improved using DECT. Material characterization and decomposition are promising using DECT. Both anatomical and functional information related to oncology can be provided by DECT using single contrast-enhanced CT.

Cone-beam computed tomography imaging: therapeutic staff dose during chemoembolisation procedure.

Cone-beam computed tomography (CBCT) imaging is an important requirement to perform real-time therapeutic image-guided procedures on patients. The purpose of this study is to estimate the personal-doseequivalent and annual-personal-dose from CBCT imaging during transarterial chemoembolisation (TACE). Therapeutic staff doses (therapeutic and assistant physician) were collected during 200 patient (65 ± 15 years, range: 40­86) CBCT examinations over six months. Absorbed doses were assessed using thermo-luminescent dosimeters during patient hepatic TACE therapy. We estimated personal-dose-equivalent (PDE) and annual-personal-dose (APD) from absorbed dose based oninternational atomic energy agency protocol. APD for therapeutic procedure was calculated (therapeutic physician: 5.6 mSv; assistant physician: 5.08 mSv) based on institutional work load. Regarding PDE, the hands of the staff members received a greater dose compared to other anatomical locations (therapeutic physician: 56 mSv, 72 mSv; assistant physician: 12 mSv, 14 mSv). Annual radiation doses to the eyes and hands of the staff members were lower compared to the prescribed limits by the International Commission on Radiological Protection (ICRP). PDE and APD of both therapeutic staff members were within the recommended ICRP-103 annual limit. Dose to the assistant physician waslower than the dose to the therapeutic physician during imaging. Annual radiation doses to eye-lenses and hands of both staff members were lower than prescribed limits.

Radiation dose to procedural personnel and patients from an X-ray volume imaging system.

OBJECTIVE: To evaluate the radiation dose received by procedural personnel and patients from an X-ray volume imaging (XVI) system during interventional procedures. METHODS: Forty patients were examined using catheter angiography (group A), digital subtraction angiography (group B) and cone-beam CT (CBCT, group C). Doses to procedural personnel (using thermo-luminescent dosimeters, TLDs) and patients were estimated. Image quality and lesion delineation were assessed using objective and subjective methods. Shapiro-Wilk, two-sided Student's t and Wilcoxon matched-pairs tests were used to test statistical significance. RESULTS: Doses (milligrays) measured in the hands and left knee of the interventionist were higher than those in an assistant physician (P < 0.05). Doses (dose-area product and skin entry dose) were lower in group A and higher in C compared with other groups; moreover, comparison among the groups were significant (all P = 0.0001). Subjective and objective lesion delineation showed significant results (all P < 0.05) among the tumour types considered. Image quality estimation showed the opposite results for objective and subjective analysis. CONCLUSION: More doses were obtained for hands of the procedural personnel compared to other anatomical regions measured. Catheter angiography showed lower dose compared with other imaging groups examined. Lesion delineation was clearly possible using CBCT. Objective and subjective analysis showed the opposite results regarding image quality because of higher noise levels and artefacts.

Dual-source 128-slice MDCT neck: radiation dose and image quality estimation of three different protocols.

PURPOSE: To estimate the radiation dose and image quality of single-source (SSCT), high-pitch (HPCT), and dual-energy (DECT) protocols of a dual-source CT (DSCT) system for the examination of neck. MATERIALS AND METHODS: 180 patients were randomized to one of the three protocols: 60 patients (age: 55.4 ± 12 years; range: 44-84 years) were examined with a SSCT, other 60 (59.5 ± 16.4 years; R: 40-85) with HPCT, and the last 60 (61.1 ± 14.9 years; R: 47-84) were examined with a DECT protocol. All examinations were performed using a DSCT system. The used protocols: Group-1 (SSCT: 120 kV; effective mAs: 185.4 ± 17.7), Group-2 (HPCT: 120 kV; eff. mAs: 97.7 ± 11.8), and Group-3 (DECT: 80 kV/140 kV with tin-filter; eff. mAs: 248.5 ± 25.7; 187 ± 21.2). A 100ml iomeprol non-ionic contrast material was injected in to the patients during examination. RESULTS: Insignificant results were yielded regarding SNR and CNR between the groups (group-1 vs. 2: 0.3125, group-1 vs. 0.6 W: 0.6875, group-2 vs. 0.6 W: 0.3125), except DECT-80 (group-1 vs. 80 kV: 0.04289, group-2 vs. 80 kV: 0.025, group-0.6 W vs.80 kV: 0.04567) and 140 kV data, moreover, qualitative analysis yielded the same results. Mean effective-dose was significantly lower (p<0.05) in group-2 (1.06 ± 0.16 mSv) compared to group-1 (2.05 ± 0.22 mSv) or group-3 (1.76 ± 0.2 mSv). Single- and dual-energy comparison showed a significant difference (group-1 vs. 3: p=0.00001 and group-2 vs. 3: p=0.00001) for CTDIvol (percent difference: 16%, 64%) or DLP (PD: 15.5%, 50.5%). CONCLUSION: Quantitative and qualitative analysis showed similar results for SSCT, HPCT, and DECT-0.6 W datasets regarding quality. HPCT yielded lower dose compared to other groups, however, the DECT achieved a lower and significant dose difference from the SSCT protocol. HPCT and DECT can be used with similar image quality and lower radiation dose compared to SSCT for the scans and can be utilized to various clinical advantages.

Nonselective transarterial chemoperfusion: a palliative treatment for malignant pleural mesothelioma.

PURPOSE: To evaluate tumor response by means of volumetric assessment, survival, and changes in patient symptoms after the treatment of unresectable and/or recurrent pleural mesothelioma by using regional nonselective transarterial chemoperfusion as a palliative treatment option. MATERIALS AND METHODS: This retrospective study was approved by the hospital ethical committee, and all patients signed an informed consent prior to treatment. Thirty-nine patients (mean age, 64.0 years; 10 women and 29 men) with unresectable pleural mesothelioma were treated with repetitive transarterial chemoperfusion between March 2007 and March 2010, with a mean of 2.9 sessions per patient at 4-week intervals. Transarterial chemoperfusion was performed by using mitomycin C, cisplatin, and gemcitabine. Computed tomography findings and patient symptoms were evaluated. Tumor response was evaluated by using Response Evaluation Criteria in Solid Tumors guidelines, and survival was assessed with the Kaplan-Meier method. The change in volume for the partial-response group was tested by using the Wilcoxon signed-rank test. RESULTS: In 36% of treated tumors (14 of 39), partial response was achieved, and tumor volume decreased from a mean value ± standard deviation of 839.6 mL ± 590.3 (range, 3.9-1972.2 mL) to 137 mL ± 399.8 (range, 0.88-1131.4; P = .00012). In 49% of tumors (19 of 39), stable disease was noted. In 15% of tumors (six of 39), progressive disease was seen. Mean specific growth rate of the tumor was 0.00158% per day. The mean survival time was 14.2 months (range, 2.1-33.1 months) from the start of treatment. For patients with tumors that responded to treatment, mean survival time was 15 months (range, 4.5-33.1 months). Mean time to disease progression was 2.6 months for all tumors, 1.5 months for stable disease, and 1.3 months for progressive disease. CONCLUSION: Transarterial chemoperfusion may have the potential to yield positive results and response in the treatment of recurrent and/or unresectable pleural mesothelioma. © RSNA, 2012.

Radiation dose and image quality of X-ray volume imaging systems: cone-beam computed tomography, digital subtraction angiography and digital fluoroscopy.

OBJECTIVE: Radiation dose and image quality estimation of three X-ray volume imaging (XVI) systems. METHODS: A total of 126 patients were examined using three XVI systems (groups 1-3) and their data were retrospectively analysed from 2007 to 2012. Each group consisted of 42 patients and each patient was examined using cone-beam computed tomography (CBCT), digital subtraction angiography (DSA) and digital fluoroscopy (DF). Dose parameters such as dose-area product (DAP), skin entry dose (SED) and image quality parameters such as Hounsfield unit (HU), noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were estimated and compared using appropriate statistical tests. RESULTS: Mean DAP and SED were lower in recent XVI than its previous counterparts in CBCT, DSA and DF. HU of all measured locations was non-significant between the groups except the hepatic artery. Noise showed significant difference among groups (P < 0.05). Regarding CNR and SNR, the recent XVI showed a higher and significant difference compared to its previous versions. Qualitatively, CBCT showed significance between versions unlike the DSA and DF which showed non-significance. CONCLUSION: A reduction of radiation dose was obtained for the recent-generation XVI system in CBCT, DSA and DF. Image noise was significantly lower; SNR and CNR were higher than in previous versions. The technological advancements and the reduction in the number of frames led to a significant dose reduction and improved image quality with the recent-generation XVI system. KEY POINTS: • X-ray volume imaging (XVI) systems are increasingly used for interventional radiological procedures. • More modern XVI systems use lower radiation doses compared with earlier counterparts. • Furthermore more modern XVI systems provide higher image quality. • Technological advances reduce radiation dose and improve image quality.