Radiation exposure during TACE procedures using additional cone-beam CT (CBCT) for guidance: safety and precautions.

Background During transarterial chemoembolization (TACE), cone-beam computed tomography (CBCT) can be used for tumor and feeding vessel detection as well as postembolization CT imaging. However, there will be additional radiation exposure from CBCT. Purpose To evaluate the additional dose raised through CBCT-assisted guidance in comparison to TACE procedures guided with pulsed digital subtraction angiography (DSA) alone. Material and Methods In 70 of 140 consecutive patients undergoing TACE for liver cancer, CBCT was used to facilitate the TACE. Cumulative dose area product (DAP), cumulative kerma(air), DAP values of DSA, total and cine specific fluoroscopy times (FT) of 1375 DSA runs, and DAP of 91 CBCTs were recorded and analyzed using Spearman's correlation, Mann-Whitney U-test, and Kruskal-Wallis test. P values < 0.05 were considered significant. Results Additional CBCT increased DAP by 2% ( P = 0.737), kerma(air) by 24.6% ( P = 0.206), and FT by 0.02% ( P = 0.453). Subgroup analysis revealed that postembolization CBCT for detection of ethiodized oil deposits added more DAP to the procedure. Performing CBCT-assisted TACE, DSA until first CBCT contributed about 38% to the total DAP. Guidance CBCT acquisitions conduced to 6% of the procedure's DAP. Additional DSA for guidance after CBCT acquisition required approximately 46% of the mean DAP. The last DSA run for documentation purposes contributed about 10% of the DAP. Conclusion CBCT adds radiation exposure in TACE. However, the capability of CBCT to detect vessels and overlay in real-time during fluoroscopy facilitates TACE with resultant reduction of DAPs up to 46%.

Activity-based cost analysis of hepatic tumor ablation using CT-guided high-dose rate brachytherapy or CT-guided radiofrequency ablation in hepatocellular carcinoma.

PURPOSE: To analyse and compare the costs of hepatic tumor ablation with computed tomography (CT)-guided high-dose rate brachytherapy (CT-HDRBT) and CT-guided radiofrequency ablation (CT-RFA) as two alternative minimally invasive treatment options of hepatocellular carcinoma (HCC). MATERIALS AND METHODS: An activity based process model was created determining working steps and required staff of CT-RFA and CT-HDRBT. Prorated costs of equipment use (purchase, depreciation, and maintenance), costs of staff, and expenditure for disposables were identified in a sample of 20 patients (10 treated by CT-RFA and 10 by CT-HDRBT) and compared. A sensitivity and break even analysis was performed to analyse the dependence of costs on the number of patients treated annually with both methods. RESULTS: Costs of CT-RFA were nearly stable with mean overall costs of approximately 1909 €, 1847 €, 1816 € and 1801 € per patient when treating 25, 50, 100 or 200 patients annually, as the main factor influencing the costs of this procedure was the single-use RFA probe. Mean costs of CT-HDRBT decreased significantly per patient ablation with a rising number of patients treated annually, with prorated costs of 3442 €, 1962 €, 1222 € and 852 € when treating 25, 50, 100 or 200 patients, due to low costs of single-use disposables compared to high annual fix-costs which proportionally decreased per patient with a higher number of patients treated annually. A break-even between both methods was reached when treating at least 55 patients annually. CONCLUSION: Although CT-HDRBT is a more complex procedure with more staff involved, it can be performed at lower costs per patient from the perspective of the medical provider when treating more than 55 patients compared to CT-RFA, mainly due to lower costs for disposables and a decreasing percentage of fixed costs with an increasing number of treatments.

Can early computed tomography angiography after endovascular aortic aneurysm repair predict the need for reintervention in patients with type II endoleak?

PURPOSE: This study was designed to identify parameters on CT angiography (CTA) of type II endoleaks following endovascular aortic aneurysm repair (EVAR) for abdominal aortic aneurysm (AAA), which can be used to predict the subsequent need for reinterventions. METHODS: We retrospectively identified 62 patients with type II endoleak who underwent early CTA in mean 3.7 ± 1.9 days after EVAR. On the basis of follow-up examinations (mean follow-up period 911 days; range, 373-1,987 days), patients were stratified into two groups: those who did (n = 18) and those who did not (n = 44) require reintervention. CTA characteristics, such as AAA, endoleak, as well as nidus dimensions, patency of the inferior mesenteric artery, number of aortic branch vessels, and the pattern of endoleak appearance, were recorded and correlated with the clinical outcome. RESULTS: Univariate and receiver operating characteristic curve regression analyses revealed significant differences between the two groups for the endoleak volume (surveillance group: 1391.6 ± 1427.9 mm(3); reintervention group: 3227.7 ± 2693.8 mm(3); cutoff value of 2,386 mm(3); p = 0.002), the endoleak diameter (13.6 ± 4.3 mm compared with 25.9 ± 9.6 mm; cutoff value of 19 mm; p < 0.0001), the number of aortic branch vessels (2.9 ± 1.2 compared with 4.2 ± 1.4 vessels; p = 0.001), as well as a "complex type" endoleak pattern (13.6 %, n = 6 compared with 44.4 %, n = 8; p = 0.02). CONCLUSIONS: Early CTA can predict the future need for reintervention in patients with type II endoleak. Therefore, treatment decision should be based not only on aneurysm enlargement alone but also on other imaging characteristics.

Unresectable colorectal liver metastases: percutaneous ablation using CT-guided high-dose-rate brachytherapy (CT-HDBRT).

PURPOSE: To evaluate the clinical outcome of CT-guided high-dose-rate brachytherapy (CT-HDRBT) of unresectable colorectal liver metastases (CRLMs). MATERIALS AND METHODS: Retrospective analysis of all consecutive patients with unresectable CRLMs treated with CT-HDRBT between January 2008 and November 2012. Treatment was performed by CT-guided catheter placement and high-dose-rate brachytherapy with an iridium-192 source. MRI follow-up was performed after 6 weeks and then every 3 months post-intervention. The primary endpoint was local tumor control (LTC); secondary endpoints included time to progression (TTP) and overall survival (OS). RESULTS: 80 heavily pretreated patients with 179 metastases were available for MRI evaluation for a mean follow-up time of 16.9 months. The mean tumor diameter was 28.5 mm (range: 8 - 107 mm). No major complications were observed. A total of 23 (12.9 %) local tumor progressions were observed. Lesions ≥ 4 cm in diameter showed significantly more local progression than smaller lesions (< 4 cm). 50 patients (62.5 %) experienced systemic tumor progression. The median TTP was 6 months. 28 (43 %) patients died during the follow-up period. The median OS after ablation was 18 months. CONCLUSION: CT-HDRBT is an effective technique for the treatment of unresectable CRLMs and warrants promising LTC rates compared to thermal ablative techniques. A combination with other local and systemic therapies should be evaluated in patients with lesions > 4 cm in diameter, in which higher progression rates are expected. KEY POINTS: • CT-HDRBT enables a highly cytotoxic irradiation of colorectal liver metastases with simultaneous conservation of important neighboring structures (eg liver parenchyma, bile ducts and bowel)• The local tumor control rates obtained by CT-HDRBT in patients with colorectal liver metastases are promising, also compared to the local tumor control rates after RFA• Metastases with a diameter of 4 cm or abow, display a higher local progression rate after CT-HDRBT, therefor a combination therapy with other locoregional or systemic treatments should be investigated in prospective studies.

Differentiation of myxoid liposarcoma by magnetic resonance imaging: a histopathologic correlation.

BACKGROUND: Myxoid liposarcomas represent a heterogeneous group of soft tissue tumors in which prognosis is dependent on differentiation. PURPOSE: To identify magnetic resonance imaging (MRI) criteria to distinguish low-grade from high-grade myxoid liposarcomas. MATERIAL AND METHODS: MR images of 30 histologically proven myxoid liposarcomas were retrospectively reviewed. Tumors were evaluated according to size, localization, tumor border, and structure as well as tumor composition. These imaging criteria were correlated with histopathological findings. RESULTS: Nineteen myxoid liposarcomas were histologically classified as low-grade myxoid liposarcomas, whereas 11 were considered high-grade myxoid liposarcomas. Mean tumor volume of low-grade myxoid liposarcomas (710.1 ± 960.1 ccm) was significantly smaller as compared to high-grade myxoid liposarcomas (2737.0 ± 3423.7 ccm; P = 0.04). In addition to necrotic areas, three tumor components - fatty, myxoid, as well as contrast-enhancing non-fatty, non-myxoid - could be identified. The mean fraction of fatty tumor areas in low-grade myxoid liposarcomas was 10 ± 11% as compared to 6 ± 4% for high-grade myxoid liposarcomas (P = 0.66). Myxoid components accounted for 88 ± 16% in low-grade myxoid liposarcomas, but only for 45 ± 25% in high-grade myxoid liposarcomas (P < 0.0001). The non-fatty, non-myxoid tumor fraction was significantly higher in high-grade myxoid liposarcomas (50 ± 25%) as compared to low-grade myxoid liposarcomas (2 ± 9%; P < 0.0001). A proportion of > 5% of this tumor fraction was found to be a precise unique predictor for high-grade myxoid liposarcomas with a sensitivity of 100% and a specificity of 95%. CONCLUSION: Tumor components with contrast-enhancing non-fatty, non-myxoid imaging features were predominantly found in high-grade myxoid liposarcomas, which may histologically resemble round cell clusters.

Percutaneous ablation of lymph node metastases using CT-guided high-dose-rate brachytherapy.

OBJECTIVE: To assess the technical feasibility, safety and clinical outcome of CT-guided high-dose-rate brachytherapy (CT-HDRBT) for achieving local tumour control (LTC) in isolated lymph node metastases. METHODS: From January 2008 to December 2011, 10 patients (six males and four females) with isolated nodal metastases were treated with CT-HDRBT. Five lymph node metastases were para-aortic, three were at the liver hilum, one at the coeliac trunk and one was a left iliac nodal metastasis. The mean lesion diameter was 36.5 mm (range 12.0-67.0 mm). Patients were followed up by either contrast-enhanced CT or MRI 6 weeks and then every 3 months after the end of treatment. The primary end point was LTC. Secondary end points included primary technical effectiveness rate, adverse events and progression-free survival. RESULTS: The first follow-up examination after 6 weeks revealed complete coverage of all nodal metastases treated. There was no peri-interventional mortality or major complications. The mean follow-up period was 13.2 months (range 4-20 months). 2 out of 10 patients (20%) showed local tumour progression 9 and 10 months after ablation. 5 out of 10 patients (50%) showed systemic tumour progression. The mean progression-free interval was 9.2 months (range 2-20 months). CONCLUSION: CT-HDRBT is a safe and effective technique for minimally invasive ablation of nodal metastases. ADVANCES IN KNOWLEDGE: CT-HDRBT of lymph node metastases is feasible and safe. CT-HDRBT might be a viable therapeutic alternative to obtain LTC in selected patients with isolated lymph node metastases.

[Percutaneous CT-guided high-dose brachytherapy (CT-HDRBT) ablation of primary and metastatic lung tumors in nonsurgical candidates]. / Perkutane CT-gesteuerte Hochdosis-Brachytherapie (CT-HDRBT) von primären und metastatischen Lungentumoren in nicht chirurgischen Kandidaten.

PURPOSE: To evaluate the safety and efficacy of CT-guided high-dose brachytherapy (CT-HDRBT) ablation of primary and metastatic lung tumors. MATERIALS AND METHODS: Between November 2007 and May 2010, all consecutive patients with primary or metastatic lung tumors, unsuitable for surgery, were treated with CT-HDRBT. Imaging follow-up after treatment was performed with contrast-enhanced CT at 6 weeks, 3 months and every 6 months after the procedure. The endpoints of the study were local tumor control and time to progression. The Kaplan-Meier method was used to estimate survival functions and local tumor progression rates. RESULTS: 34 procedures were carried out on 33 lesions in 22 patients. The mean diameter of the tumors was 33.3 mm (SD = 20.4). The first contrast-enhanced CT showed that complete ablation was achieved in all lesions. The mean minimal tumor enclosing dose was 18.9 Gy (SD = 2). Three patients developed a pneumothorax after the procedure. The mean follow-up time was 13.7 (3 - 29) months. 2 of 32 lesions (6.25 %) developed a local tumor progression. 8 patients (36.3 %) developed a distant tumor progression. After 17.7 months, 13 patients were alive and 9 patients had died. CONCLUSION: CT-HDRBT ablation is a safe and attractive treatment option for patients with lung malignancies and allows targeted destruction of tumor tissue with simultaneous preservation of important lung structures. Furthermore, CT-HDRBT is independent of the size of the lesion and its location within the lung parenchyma.

Computed tomographic criteria for the discrimination of subcentimeter lung nodules in patients with soft-tissue sarcomas.

The aim of this study was to identify criteria for nodule characterization on chest computed tomography in patients with soft tissue sarcomas. In 195 patients, a total of 194 benign and 117 malignant subcentimeter lung nodules were retrospectively analyzed according to lesion size, shape, margins, density, and localization. Benign lesions more frequently displayed complex shape and were of ground-glass density (P<.0001, respectively). In contrast, round shape and solid density were more frequently found in malignant lesions (P<.0001, respectively).

Low-dose computed tomography to detect body-packing in an animal model.

OBJECTIVE: To assess the possible extent of dose reduction for low-dose computed tomography (CT) in the detection of body-packing (ingested drug packets) as an alternative to plain radiographs in an animal model. MATERIALS AND METHODS: Twelve packets containing cocaine (purity >80%) were introduced into the intestine of an experimental animal (crossbred pig), which was then repeatedly examined by abdominal CT with stepwise dose reduction (tube voltage, 80 kV; tube current, 10-350 mA). Three blinded readers independently evaluated the CT datasets starting with the lowest tube current and noted the numbers of packets detected at the different tube currents used. In addition, 1 experienced reader determined the number of packets detectable on plain abdominal radiographs and ultrasound. RESULTS: The threshold for correct identification of all 12 drug packets was 100 mA for reader 1 and 125 mA for readers 2 and 3. Above these thresholds all 3 readers consistently identified all 12 packets. The effective dose of a low-dose CT scan with 125 mA (including scout view) was 1.0 mSv, which was below that of 2 conventional abdominal radiographs (1.2 mSv). The reader interpreting the conventional radiographs identified a total of 9 drug packets and detected 8 packets by abdominal ultrasound. CONCLUSIONS: Extensive dose reduction makes low-dose CT a valuable alternative imaging modality for the examination of suspected body-packers and might replace conventional abdominal radiographs as the first-line imaging modality.

Volume measurement of liver metastases using multidetector computed tomography: comparison of lesion diameter and volume segmentation - a phantom study.

PURPOSE: To compare lesion volume determination by applying diameter measurement and three different segmentation algorithms at different slice thicknesses reconstructed from computed tomography (CT) of a phantom model for hepatic colorectal metastases. MATERIALS AND METHODS: Based on CT attenuation measurements obtained retrospectively from 20 patients with colorectal liver metastases, a phantom model was designed with a sponge soaked with a dilution of contrast agent and 6 embedded polyamide spheres (diameter, 8 - 30 mm) to simulate the contrast behavior of liver metastases. CT scans were obtained and reconstructed at different slice thicknesses (0.625/1.25/2.5/3.75 mm; increment, 1). One observer performed software-aided volume determination using the maximum diameter, manual segmentation, seed point method, and threshold method six times for each lesion in a randomized order. Statistical analysis revealed the absolute and relative differences from the actual lesion volumes and the intraobserver differences as well as the influence of slice thickness for each method. RESULTS: The mean relative differences of the seed point method (1.2 - 5.9%) and manual segmentation (2.6 - 4.9%) were significantly lower than the threshold method (5.4 - 12.8%) and diameter measurement (12.3 - 18.5%; p < 0.01). Volume determination by manual segmentation and the seed point method benefited from the use of thin-slice CT datasets. The intraobserver variation was lowest when using the manual segmentation (1.5 - 3.3%) and the seed point method (2.2 - 3.9%; p < 0.001). CONCLUSION: Manual segmentation and the seed point method for thin CT slices were the methods with the lowest volume differences and intraobserver variation.

Improvement of skills and knowledge by a hands-on cardiac CT course: before and after evaluation with a validated questionnaire and self-assessment.

PURPOSE: Cardiac computed tomography (CT) is becoming increasingly important in noninvasive imaging. To meet this demand, there are a growing number of short training courses for cardiac CT. Whether such courses improve the knowledge and skills of participants is not known. MATERIALS AND METHODS: The concept of a two-day cardiac CT course consisting of introductory lectures, live patient examinations, and hands-on exercises for interpreting cardiac CT scans on workstations was analyzed using participant evaluations (scales from 1=excellent to 6=very poor). Participants rated their increase in knowledge and completed a validated questionnaire with 20 questions. RESULTS: A total of 102 participants attended the courses. There were significant differences in the number of correctly answered test questions between cardiac CT experts and participants at the beginning of the course (91.5+/-6.3 % vs. 62.4+/-16.1% p<0.001). The number of questions answered correctly by the participants increased significantly after completion of the course (mean increase of 4 correctly answered questions, 81.8+/-11.4%. vs. 62.4+/-16.1% p<0.001). This objective increase in knowledge was in good agreement with participant self-assessments (76.4+/-12.6% vs. 81.8+/-11.4%). The quality of the course received good to very good scores, ranging from 1.8+/-0.7 for speed of presentation to 1.4+/-0.5 for lecturer competence. The score for overall course quality was 1.4+/-0.6. CONCLUSION: A relatively short cardiac CT course can significantly improve the quantifiable knowledge of participants. The overall quality of the course was rated as very good.

Comparison between the image quality of multisegment and halfscan reconstructions of non-invasive CT coronary angiography.

The purpose of this study was to compare the image quality of multisegment and halfscan reconstructions of multislice computed tomography (MSCT) coronary angiography. 126 patients with suspected coronary artery disease and uninfluenced heart rates were examined by 16-slice CT before they underwent invasive coronary angiography. Multisegment and halfscan reconstructions were performed in all patients, and subjective image quality, overall vessel length, vessel length free of motion artefacts and contrast-to-noise ratios (CNRs) were compared for both techniques. The diagnostic accuracy of both approaches was compared with the results of invasive coronary angiography. Overall image quality scores of multisegment reconstruction were superior to those of halfscan reconstruction (13.3+/-2.1 vs 11.9+/-2.9; p<0.001). Multisegment reconstruction depicted significantly longer overall coronary vessel lengths (p<0.001) and larger vessel proportions free of motion artefacts in three of the four main coronary arteries. CNRs in the left main, left anterior descending and left circumflex coronary arteries were significantly higher when multisegment reconstruction was used (p<0.001). Overall accuracy was higher for multisegment reconstruction compared with halfscan reconstruction (87% vs 62%). In conclusion, multisegment reconstruction significantly improves image quality and diagnostic accuracy of MSCT coronary angiography compared with standard halfscan reconstruction, resulting in vessel lengths depicted free of motion comparable to those of CT performed in patients given beta-blockers to lower heart rates.

Multislice CT coronary angiography: evaluation of an automatic vessel detection tool.

PURPOSE: To investigate the potential of a new detection tool for multislice CT (MSCT) coronary angiography with automatic display of curved multiplanar reformations and orthogonal cross-sections. MATERIALS AND METHODS: Thirty-five patients were consecutively enrolled in a prospective intention-to-diagnose study and examined using a MSCT scanner with 16 x 0.5 mm detector collimation and 400 ms gantry rotation time (Aquilion, Toshiba). A multisegment algorithm using up to four segments was applied for ECG-gated reconstruction. Automatic and manual detection of coronary arteries was conducted using the coronary artery CT protocol of a workstation (Vitrea 2, Version 3.3, Vital Images) to detect significant stenoses (> or = 50 %) in all segments of > or = 1.5 mm in diameter. Each detection tool was used by one reader who was blinded to the results of the other detection method and the results of conventional coronary angiography. RESULTS: The overall sensitivity, specificity, nondiagnostic rate, and accuracy of the automatic and manual approach were 90 vs. 94 %, 89 vs. 84 %, 6 vs. 6 %, and 89 vs. 88 %, respectively (p = n. s.). The vessel length detected with the automatic and manual approach were highly correlated for the left main/left anterior descending (143 +/- 30 vs. 146 +/- 24 mm, r = 0.923, p < 0.001), left circumflex (94 +/- 35 vs. 93 +/- 33 mm, r = 0.945, p < 0.001), and right coronary artery (145 +/- 36 vs. 144 +/- 37 mm, r = 0.925, p < 0.001). The time required to create reformations along the coronary arteries was significantly shorter with the automatic tool compared to the manual approach (203 +/- 77 vs. 391 +/- 104 sec, p < 0.005). In 90 % of the coronary branches automatic detection required less time than the manual approach. CONCLUSION: Automatic coronary vessel detection is feasible and reduces the time required to create reformations by a factor of approximately two without deteriorating the diagnostic accuracy.