Radiation dose and image quality evaluation relative to different contrast media using cone-beam CT

Detectability of hepatic tumors during 3D post-processed ultrafast cone-beam computed tomography

To evaluate hepatic tumor detection using ultrafast cone-beam computed tomography (UCBCT) cross-sectional and 3D post-processed image datasets. 657 patients were examined using UCBCT during hepatic transarterial chemoembolization (TACE), and data were collected retrospectively from January 2012 to September 2014. Tumor detectability, diagnostic ability, detection accuracy and sensitivity were examined for different hepatic tumors using UCBCT cross-sectional, perfusion blood volume (PBV) and UCBCT-MRI (magnetic resonance imaging) fused image datasets. Appropriate statistical tests were used to compare collected sample data. Fused image data showed the significantly higher (all P  <  0.05) diagnostic ability for hepatic tumors compared to UCBCT or PBV image data. The detectability of small hepatic tumors (<5 mm) was significantly reduced (all P  <  0.05) using UCBCT cross-sectional images compared to MRI or fused image data; however, PBV improved tumor detectability using a color display. Fused image data produced 100% tumor sensitivity due to the simultaneous availability of MRI and UCBCT information during tumor diagnosis. Fused image data produced excellent hepatic tumor sensitivity, detectability and diagnostic ability compared to other datasets assessed. Fused image data is extremely reliable and useful compared to UCBCT cross-sectional or PBV image datasets to depict hepatic tumors during TACE. Partial anatomical visualization on cross-sectional images was compensated by fused image data during tumor diagnosis.

Ultrafast cone-beam computed tomography: a comparative study of imaging protocols during image-guided therapy procedure

Objective. To evaluate two ultrafast cone-beam CT (UF-CBCT) imaging protocols with different acquisition and injection parameters regarding image quality and required contrast media during image-guided hepatic transarterial chemoembolization (TACE). Methods. In 80 patients (male: 46, female: 34; mean age: 56.8 years; range: 33–83) UF-CBCT was performed during TACE for intraprocedural guidance. Imaging was performed using two ultrafast CBCT acquisition protocols with different acquisition and injection parameters (imaging protocol 1: acquisition time 2.54 s, and contrast 6 mL with 3 s delay; imaging protocol 2: acquisition time 2.72 s, and contrast 7 mL with 6 s delay). Image evaluation was performed with both qualitative and quantitative methods. Contrast injection volume and dose parameters were compared using values from the literature. Results. Imaging protocol 2 provided significantly better (P < 0.05) image quality than protocol 1 at the cost of slightly higher contrast load and patient dose. Imaging protocol 1 provided good contrast perfusion but it mostly failed to delineate the tumors (P < 0.05). On the contrary, imaging protocol 2 showed excellent enhancement of hepatic parenchyma, tumor, and feeding vessels. Conclusion. Tumor delineation, visualization of hepatic parenchyma, and feeding vessels are clearly possible using imaging protocol 2 with ultrafast CBCT imaging. A reduction of required contrast volume and patient dose were achieved due to the ultrafast CBCT imaging.

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: 40–86) 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.

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.