Emmanuel Mbalisike

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

AbstractObjectiveRadiation dose and image quality estimation of three X-ray volume imaging (XVI) systems.MethodsA 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.ResultsMean 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.ConclusionA 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.

Liver metastases of pancreatic cancer: role of repetitive transarterial chemoembolization (TACE) on tumor response and survival.

Objective: To evaluate the effect of chemoembolization on pancreatic cancer liver metastases. Method: Thirty-two patients with pancreatic cancer liver metastases retrospectively underwent chemoembolization (4- to 8-week intervals). Size-based evaluation (response evaluation criteria in solid tumors [RECIST]) and survival indexes were assessed overall and for sex and number of lesions. Results: Of the patients, 71.87% showed stable disease, 9.37% partial response (PR) and 18.75% progressive disease (PD). Survival rate for 1, 3, and 5 years from first TACE was 60%, 25%, and 11%, respectively. Median survival time was 16 months and for stable disease group was 20 months. Progression-free survival for 6 months and 1, 3, and 5 years was 84%, 57.3%, 20%, and 10%, respectively. There was significant difference between men and women in response. Survival rates for 1 and 5 years for the men were 80% and 14% and for the women were 47% and 0%. There was no significant difference between oligonodular liver lesion (n < 5) and multinodular (n > 5) groups. Survival rates for 1 and 5 years for oligonodular were 84% and 14%, and for multinodular was 50% and 0%. Conclusion: Repetitive TACE resulted in a relevant response for the control of liver metastases of pancreatic cancer with respectable median survival time. Interestingly, the number of lesions, statistically, was not an effective factor.

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.

Leiomyoma Volume Changes at Follow-up after Uterine Artery Embolization: Correlation with the Initial Leiomyoma Volume and Location

PURPOSE To study the changes in uterine leiomyoma volume after uterine artery embolization (UAE) and to correlate these changes with the initial tumor volume and location within the uterus. MATERIALS AND METHODS The study was performed retrospectively on 28 consecutive patients (age, 37-57 years; mean, 48 y +/- 4.81) with 84 uterine leiomyomas. UAE was performed between June 2006 and August 2007. All tumors in all patients were evaluated. Magnetic resonance imaging was performed before UAE and 3 months and 1 year after UAE. The volume and location of each tumor were evaluated in consensus by two radiologists. RESULTS The mean pre-UAE volume of the leiomyomas was 51.6 cm(3) (range, 0.72-371.1 cm(3); SD, 79.3). Seven tumors were submucous, 28 intramural, and 49 subserous. At 3-month follow-up, 83 tumors (98.8%) showed volume reduction (mean, 52.62% +/- 21.85%; range, 12.79%-96.67%) and one (1.2%) increased in volume. At 1-year follow-up, five tumors (6%) were undetectable, 72 (85.7%) showed a further volume reduction of 20.5% +/- 11.92% (range, 2.52%-58.72%) relative to the 3-month volume, and seven (8.3%) increased in volume. A statistically significant difference (P = .026 at 3 months and P = .0046 at 1 year) in percentage of volume change was observed based on tumor location; submucous tumors showed the greatest volume reduction and subserous tumors the least reduction. The initial tumor volume showed a weak negative correlation (Spearman correlation coefficients, -0.35 at 3 months and -0.36 at 1 year) with tumor volume change. CONCLUSIONS UAE results in leiomyoma volume reduction at 3-month and 1-year follow-up. The tumor location plays an important role in volume changes and the initial tumor volume plays a minor role. Further studies with larger numbers of submucous leiomyomas are needed.

Oncological applications of dual-energy computed tomography imaging.

Abstract 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.

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

ObjectiveTo evaluate the radiation dose received by procedural personnel and patients from an X-ray volume imaging (XVI) system during interventional procedures.MethodsForty 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.ResultsDoses (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.ConclusionMore 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.Key Points• Interventional radiological procedures inevitably impart relatively high radiation doses• Little is known about the doses imparted by cone-beam CT (CBCT)-guided procedures.• During interventional radiological procedures the hands of personnel receive high doses.• Catheter angiography delivered lower doses compared with CBCT and digital subtraction angiography (DSA).• Nevertheless the use of CBCT to delineate lesions is advantageous for patients.

CT chest and gantry rotation time: does the rotation time influence image quality?

Background Computed tomography (CT) gantry rotation time is one factor influencing image quality. Until now, there has been no report investigating the influence of gantry rotation time on chest CT image quality. Purpose To investigate the influence of faster gantry rotation time on image quality and subjective and objective image parameters in chest CT imaging. Material and Methods Chest CT scans from 160 patients were examined in this study. All scans were performed using a single-source mode (collimation, 128 × 0.6 mm; pitch, 1.2) on a dual-source CT scanner. Only gantry rotation time was modified, while other CT parameters were kept stable for each scan (120 kV/110 reference mAs). Patients were divided into four groups based on rotation time: group 1, 1 s/ rotation (rot); group 2, 0.5 s/rot; group 3, 0.33 s/rot; group 4, 0.28 s/rot. Two blinded radiologists subjectively compared CT image quality, noise, and artifacts, as well as radiation exposure, from all groups. For objective comparison, all image datasets were analyzed by a radiologist with 5 years of experience concerning objective measurements as well as signal-to-noise ratio (SNR). Results We found that faster gantry rotation times (0.28 s/rot and 0.33 s/rot) resulted in more streak artifacts, image noise, and decreased image quality. However, there was no significant difference in radiation exposure between faster and slower rotation times (P > 0.7). Conclusion Faster CT gantry rotation reduces scan time and motion artifacts. However, accelerating rotation time increases image noise and streak artifacts. Therefore, a slower CT gantry rotation speed is still recommended for higher image quality in some cases.

Transarterielle Chemoperfusion und -embolisation thorakaler Neoplasmen mittels C-Arm CT

PURPOSE To evaluate the role of C-arm CT for on-line fluoroscopy in regional transarterial chemoperfusion (TACP) and chemo-embolization (TPCE) of primary and secondary malignant thoracic lesions. MATERIALS AND METHODS From September 2008 to March 2009 a total of 31 patients (20 males and 11 females, average age: 61.7 years, range 22-84 years) with 53 thoracic malignant lesions from different origins (primary or secondary pulmonary carcinoma n=37, pleural mesothelioma n=16) were treated with TACP or TPCE using flat-detector CT (FD-CT). C-arm CT of the latest generation was used to localize the lesion before local chemotherapy (Artis Zeego, Siemens, Erlangen). For TACP a 220 degrees rotation and a volume of 150 ml (ratio of 1:2 contrast/normal saline), delay 2 s and flow 12 ml/s was used. For TPCE a volume of 75 ml (ratio of 1:2 contrast/normal saline), delay 2 s and flow 3 ml/s was used. RESULTS TPCE C-arm CT allowed the evaluation of the degree of perfusion of the tumor and the geographic areas of enhancement correlated with the post-interventional lipiodol uptake in MSCT. In TACP the intercostal arteries involved could be visualized and in 30% of interventions the catheter had to be repositioned for the following intervention. CONCLUSION C-arm CT provides additional information on the vascular characteristics and perfusion of pulmonary lesions resulting in a change of interventional strategy in a relevant number of patients.

[C-arm computed tomography for transarterial chemoperfusion and chemo-embolization of thoracic lesions].

PURPOSE To evaluate the role of C-arm CT for on-line fluoroscopy in regional transarterial chemoperfusion (TACP) and chemo-embolization (TPCE) of primary and secondary malignant thoracic lesions. MATERIALS AND METHODS From September 2008 to March 2009 a total of 31 patients (20 males and 11 females, average age: 61.7 years, range 22-84 years) with 53 thoracic malignant lesions from different origins (primary or secondary pulmonary carcinoma n=37, pleural mesothelioma n=16) were treated with TACP or TPCE using flat-detector CT (FD-CT). C-arm CT of the latest generation was used to localize the lesion before local chemotherapy (Artis Zeego, Siemens, Erlangen). For TACP a 220 degrees rotation and a volume of 150 ml (ratio of 1:2 contrast/normal saline), delay 2 s and flow 12 ml/s was used. For TPCE a volume of 75 ml (ratio of 1:2 contrast/normal saline), delay 2 s and flow 3 ml/s was used. RESULTS TPCE C-arm CT allowed the evaluation of the degree of perfusion of the tumor and the geographic areas of enhancement correlated with the post-interventional lipiodol uptake in MSCT. In TACP the intercostal arteries involved could be visualized and in 30% of interventions the catheter had to be repositioned for the following intervention. CONCLUSION C-arm CT provides additional information on the vascular characteristics and perfusion of pulmonary lesions resulting in a change of interventional strategy in a relevant number of patients.

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.