Contrast-enhanced Cone-beam CT Research Articles

Intraoperative contrast-enhanced cone beam CT allows visualization of the ‘dark side’ of the clot and improves mechanical thrombectomy performance

BackgroundVisualization of the clot is key to the endovascular treatment of ischemic stroke, but identification of the distal part of the clot and distal arteries during mechanical thrombectomy (MT) remains...

Intraprocedural C-arm dual-phase cone-beam enhancement patterns correlate with tumor absorbed dose after radioembolization.

Recent studies have shown a clear relationship between absorbed dose and tumor response to treatment after hepatic radioembolization. These findings help to create more personalized treatment planning and dosimetry. However, crucial to this goal is the ability to predict the dose distribution prior to treatment. The microsphere distribution is ultimately determined by (i) the hepatic vasculature and the resulting blood flow dynamics and (ii) the catheter position. To show that pretreatment, intra-procedural imaging of blood flow patterns, as quantified by catheter-directed intra-arterial contrast enhancement, correlate with posttreatment microsphere accumulation and, consequently, absorbed dose. Patients who participated in a clinical trial (NCT01177007) and for whom both a pretreatment dual-phase contrast-enhanced cone-beam CT (CBCT) and a posttreatment 90Y PET/CT scan were available were included in this retrospective study. Tumors and perfused volumes were manually delineated on the CBCT by an experienced radiologist. The mean, sum, and standard deviation of the voxels in each volume were recorded. The delineations were transferred to the PET-based absorbed dose maps by coregistration of the corresponding CTs. Linear multiple regression was used to correlate pretreatment CBCT enhancement to posttreatment 90Y PET/CT-based absorbed dose in each region. Leave-one-out cross-validation and Bland-Altman analyses were performed on the predicted versus measured absorbed doses. Nine patients, with a total of 23 tumors were included. All presented with hepatocellular carcinoma (HCC). Visually, all patients had a clear correspondence between CBCT enhancement and absorbed dose. The correlation between CBCT enhancement and posttherapy absorbed tumor dose based was strong (R2=0.91), and moderate for the non-tumor liver tissue (R2=0.61). Limits of agreement were approximately ±55 Gray for tumor tissue. There is a linear relationship between pretreatment blood dynamics in HCC tumors and posttreatment absorbed dose, which, if shown to be generalizable, allows for pretreatment tumor absorbed dose prediction.

Cone-beam breast CT-guided surface location facilitates breast-conserving surgery in breast cancer patients with extensive calcifications: A pilot study.

Extensive malignant-appearing calcifications have traditionally been considered a contraindication for breast-conserving surgery. The evaluation of calcifications largely depends on mammography, which is limited by tissue superimposition and is unable to reveal spatial information about extensive calcifications. Three-dimensional imaging modality is needed to reveal the architecture of extensive calcifications. In the present study, a novel cone-beam breast CT-guided surface location technique was investigated to facilitate breast-conserving surgery in breast cancer patients with extensive malignant breast calcifications. Biopsy-proved early breast cancer patients with extensive malignant-appearing breast calcifications were included. A patient will be considered suitable for breast-conserving surgery if the spatial segmental distribution of calcifications is found by 3D images of cone-beam breast CT. Then, the margins of the calcifications were located in contrast-enhanced cone-beam breast CT images. Next, skin markers were located using radiopaque materials, and cone-beam breast CT was reperformed to confirm the accuracy of surface location. During breast-conserving surgery, lumpectomy was performed according to the previous surface location, and an intraoperative specimen x-ray was applied to double-check that the entire lesion was removed. Margin assessment was made for both intraoperative frozen section and postoperative pathology examination. From May 2019 to Jun 2022, 11 eligible breast cancer patients in our institution were included. Breast-conserving surgery was performed successfully in all patients using the surface location approach mentioned before. All patients achieved negative margins and satisfied cosmetic results. This study proved the feasibility of cone-beam breast CT-guided surface location for facilitating breast-conserving surgery in breast cancer patients with extensive malignant breast calcifications.

Angioarchitecture of the Normal Lateral Spinal Artery and Craniocervical Junction Arteriovenous Fistula Using Contrast-enhanced Cone-beam CT.

The lateral spinal artery (LSA) perfuses the dorsolateral part of the spinal cord at the craniocervical junction (CCJ). We analyzed the angioarchitecture of the normal LSA and CCJ arteriovenous fistula (AVF). The first study included 26patients with acerebral aneurysm of the posterior circulation. Using slab maximum intensity projection (MIP) images from three-dimensional rotational angiography (3D-RA) and contrast-enhanced cone-beam CT (CE-CBCT), we analyzed the origin of the LSA, its anastomosis with the posterior inferior cerebellar artery (PICA), the point where it reaches the spinal cord, and the visualized range. In the second study, we analyzed the angioarchitecture and treatment results of 7 CCJAVF lesions treated in our department between 2016 and 2021. We visualized the normal LSA for all patients. In 23patients with an intradural origin PICA, all LSAs originated from the C1 or C2 radicular artery, and 8 patients had an anastomosis with the PICA. In three patients with aC1 level origin PICA, all LSAs originated from the PICA. All LSAs reached the dorsolateral part of the spinal cord. The mean visualized range of the LSA was 27.4 mm. The LSA was involved in five of seven CCJAVF lesions (71%). There was one lesion with aspinal infarction after LSA embolization. Other lesions were treated by direct interruption of the AVF, and the ASA and LSA were preserved. This is the first report that visualized the LSA's normal anatomy using slab MIP images from 3D-RA and CE-CBCT. Knowledge of LSA anatomy is critical to avoid complications during the treatment of CCJAVF.

Distinguishing benign and malignant lesions on contrast-enhanced breast cone-beam CT with deep learning neural architecture search

PurposeTo utilize a neural architecture search (NAS) approach to develop a convolutional neural network (CNN) method for distinguishing benign and malignant lesions on breast cone-beam CT (BCBCT). Method165 patients with 114 malignant and 86 benign lesions were collected by two institutions from May 2012 to August 2014. The NAS method autonomously generated a CNN model using one institution’s dataset for training (patients/lesions: 71/91) and validation (patients/lesions: 20/23). The model was externally tested on another institution’s dataset (patients/lesions: 74/87), and its performance was compared with fine-tuned ResNet-50 models and two breast radiologists who independently read the lesions in the testing dataset without knowing lesion diagnosis. ResultsThe lesion diameters (mean ± SD) were 18.8 ± 12.9 mm, 22.7 ± 10.5 mm, and 20.0 ± 11.8 mm in the training, validation, and external testing set, respectively. Compared to the best ResNet-50 model, the NAS-generated CNN model performed three times faster and, in the external testing set, achieved a higher (though not statistically different) AUC, with sensitivity (95% CI) and specificity (95% CI) of 0.727, 80% (66–90%), and 60% (42–75%), respectively. Meanwhile, the performances of the NAS-generated CNN and the two radiologists’ visual ratings were not statistically different. ConclusionsOur preliminary results demonstrated that a CNN autonomously generated by NAS performed comparably to pre-trained ResNet models and radiologists in predicting malignant breast lesions on contrast-enhanced BCBCT. In comparison to ResNet, which must be designed by an expert, the NAS approach may be used to automatically generate a deep learning architecture for medical image analysis.

Optimal acquisition time to discriminate between breast cancer subtypes with contrast-enhanced cone-beam CT

PurposeTo identify the optimal acquisition time to best discriminate between benign and malignant breast lesions on contrast-enhanced cone beam CT (CE-CBCT) and evaluate the potential of CE-CBCT to differentiate between breast cancer subtypes. Material and methodA total of 98 women with a mean age of 49±10 (SD) years (range: 29–77 years) with 100 BI-RADS 4 or 5 breast lesions were prospectively included. CE-CBCT images were obtained at 1- and 2-min after intravenous administration of iodinated contrast material. Contrast enhancement of breast lesions on CE-CBCT were evaluated and compared between different subtypes. Cut-off values for best discriminating between benign and malignant breast lesions with CE-CBCT were obtained from receiver operating characteristic curves. ResultsMalignant breast lesions showed greater enhancement than benign ones at 1-min (67.28±39.79 [SD] HU vs. 42.27±40.31 [SD] HU, respectively; P=0.007) and 2-min (70.93±38.05 [SD] HU vs. 48.94±41.83 [SD] HU, respectively; P=0.016) after intravenous administration of contrast material. At 1-min after intravenous administration of contrast material, an optimal cut-off value of 54.43 HU was found to best discriminate between malignant and benign breast lesions (AUC=0.681; 95%CI: 0.558–0.805; P=0.006) yielding 69.0% sensitivity (95%CI: 56.9–79.5%) and 69.2% specificity (95% CI: 48.2–85.7%). At 2-min, an optimal cut-off value of 72.65 HU was found to best discriminate between malignant and benign breast lesions (AUC=0.654; 95%CI: 0.535–0.774; P=0.020) yielding 50.7% sensitivity (95%CI: 38.6–62.8%) and 80.8% specificity (95%CI: 60.6–93.4%). CE-CBCT helped differentiate between immunohistochemical subtypes of breast lesions with lowest enhancement for triple negative lesions. No differences in enhancement were found among histopathological subtypes lesions at 1-min (P=0.478) and 2-min (P=0.625). ConclusionCE-CBCT helps discriminate between malignant and benign breast lesions, with best capabilities obtained at 1-min after intravenous administration of contrast material. For malignant lesions, quantitative analysis of enhancement on CE-CBCT helps differentiate between immunohistochemical subtypes.

Contrast-enhanced, conebeam CT-based, fractionated radiotherapy and follow-up monitoring of orthotopic mouse glioblastoma: a proof-of-concept study

BackgroundDespite aggressive treatment regimens comprising surgery and radiochemotherapy, glioblastoma (GBM) remains a cancer entity with very poor prognosis. The development of novel, combined modality approaches necessitates adequate preclinical model systems and therapy regimens that closely reflect the clinical situation. So far, image-guided, fractionated radiotherapy of orthotopic GBM models represents a major limitation in this regard.MethodsGL261 mouse GBM cells were inoculated into the right hemispheres of C57BL/6 mice. Tumor growth was monitored by contrast-enhanced conebeam CT (CBCT) scans. When reaching an average volume of approximately 7 mm3, GBM tumors were irradiated with daily fractions of 2 Gy up to a cumulative dose of 20 Gy in different beam collimation settings. For treatment planning and tumor volume follow-up, contrast-enhanced CBCT scans were performed twice per week. Daily repositioning of animals was achieved by alignment of bony structures in native CBCT scans. When showing neurological symptoms, mice were sacrificed by cardiac perfusion. Brains, livers, and kidneys were processed into histologic sections. Potential toxic effects of contrast agent administration were assessed by measurement of liver enzyme and creatinine serum levels and by histologic examination.ResultsTumors were successfully visualized by contrast-enhanced CBCT scans with a detection limit of approximately 2 mm3, and treatment planning could be performed. For daily repositioning of the animals, alignment of bony structures in native CT scans was well feasible. Fractionated irradiation caused a significant delay in tumor growth translating into significantly prolonged survival in clear dependence of the beam collimation setting and margin size. Brain sections revealed tumors of similar appearance and volume on the day of euthanasia. Importantly, the repeated contrast agent injections were well tolerated, as liver enzyme and creatinine serum levels were only subclinically elevated, and liver and kidney sections displayed normal histomorphology.ConclusionsContrast-enhanced, CT-based, fractionated radiation of orthotopic mouse GBM represents a versatile preclinical technique for the development and evaluation of multimodal radiotherapeutic approaches in combination with novel therapeutic agents in order to accelerate translation into clinical testing.

Clinical impact of a new cone beam CT angiography respiratory motion artifact reduction algorithm during hepatic intra-arterial interventions.

To assess the impact of recently developed respiratory motion correction software on contrast-enhanced cone beam CT angiography (CBCT-a) for intraprocedural image guidance during intra-arterial liver-directed therapy. From 2015 to 2017, two groups of patients who underwent intra-arterial liver-directed therapy with (breathing, n = 30) or without (still, n = 30) significant respiratory motion artifacts were retrospectively included. All CBCT-a were processed with and without dedicated respiratory motion correction software. Four readers independently assessed the following in both reconstructions (motion correction ON and OFF): (1) overall image quality on a 0-to-5 point scale, and (2) presence of relevant peri-procedural information on tumor and vasculature (overall vessel geometry, visibility of extrahepatic vessels, target tumor conspicuity, visibility of tumor feeders). Motion correction increased the average image quality in the breathing group from 2.0 ± 0.9 to 2.9 ± 1.0 (p < 0.01). The visibility of vessel geometry, extrahepatic vessels, and tumor feeders was significantly improved for all readers, and tumor conspicuity was improved for three readers. The average image quality was not significantly different between reconstructions in the still group (motion correction ON and OFF), for any of the readers (4.0 ± 0.6 vs 4.2 ± 0.6; p = 0.12). There was no change in the visibility of vessel geometry, extrahepatic vessels, tumor feeders, or tumor conspicuity for the four readers using the respiratory motion correction software in this group. Using the dedicated respiratory motion correction software during intra-arterial liver-directed procedures increases the visualization of relevant peri-procedural information and image quality in CBCT-a corrupted by respiratory motion artifacts without affecting these elements in still CBCT-a. • The use of respiratory motion correction software could reduce the need for cone beam CT angiography acquisition retake. • Motion correction software significantly increases the visibility of vessel geometry, extrahepatic vessels, and tumor feeders, as well as tumor conspicuity in cone beam CT angiography corrupted by respiratory motion artifacts. • The use of respiratory motion correction software on cone beam CT angiography uncorrupted by respiratory motion artifact does not result in decreased image quality.

Iliac artery deformation during EVAR.

Objectives To quantify the deformation of the common iliac artery caused by stiff guide wires and delivery systems during abdominal endovascular aortic repair (EVAR). Methods Twenty-two patients treated with abdominal EVAR were included. The following three image data-sets were acquired for each patient: (1) a preoperative computed tomography angiography (CTA), (2) an intraoperative contrast-enhanced cone beam CT (CBCT) obtained after the main trunk of the bifurcated stent graft was released and both iliac limbs were engaged with stiff guide wires, and (3) the first postoperative CTA. These data-sets were merged and compared in an image analysis work station. The length and the tortuosity index of the common iliac artery, the Euclidian displacement of the aortic and the iliac bifurcations, and the optimal C-arm angulation for projection of the iliac bifurcation were computed. Results The common iliac artery was on average 6.4 mm shorter ( p &lt; 0.001) and tortuosity index was lower ( p = 0.003) in the intraoperative images compared to preoperative. Some of the foreshortening was reversed postoperatively, remaining mean length difference was 2.9 mm ( p = 0.007) compared to preoperative. Intraoperatively, the aortic bifurcation was mostly displaced in a cranial direction (100%) and the iliac bifurcation in a ventral direction (93%). The optimal lateral C-arm angulation for projection of the iliac bifurcation changed. Anterior contralateral angle increased from median 42° (IQR, 27–63) in the preoperative CTA to 62 (49–74) in the intraoperative CBCT ( p = 0.02). Optimal cranio-caudal angulation did not change. Conclusion Stiff guide wires and delivery systems cause significant deformation of the common iliac arteries during EVAR. The aortic bifurcation is more cranial, the common iliac arteries are shorter, and optimal C-arm angulation is more contralateral oblique when the iliac limbs are to be deployed compared to baseline measurements from preoperative CTA. This affects image fusion accuracy and stent graft selection.

The Efficacy of Cone-Beam CT–Based Liver Perfusion Mapping to Predict Initial Response of Hepatocellular Carcinoma to Transarterial Chemoembolization

PurposeTo evaluate efficacy of cone-beam CT–based liver perfusion mapping obtained immediately following conventional transarterial chemoembolization of hepatocellular carcinoma (HCC) for assessing tumor vascularity, technical success of chemoembolization, and treatment response. Materials and MethodsFrom July 2015 to June 2016, 35 patients with 57 HCCs who underwent cone-beam CT with post-processing software via conventional transarterial chemoembolization for HCC and follow-up examination were included. Three reviewers evaluated technical success on angiography, unenhanced cone-beam CT, contrast-enhanced cone-beam CT, and cone-beam CT–based liver perfusion mapping after transarterial chemoembolization per tumor and per patient. Parenchymal blood volume (PBV) was measured. Treatment response was determined on follow-up CT, MR imaging, or histopathology according to modified Response Evaluation Criteria In Solid Tumors. Diagnostic performance for detection of a viable tumor was evaluated using multiple logistic regression with C-statistics. ResultsTreatment response was 38, 17, 2, and 0 for complete response, partial response, stable disease, and progressive disease per tumor and 18, 15, 2, and 0 per patient. In multiple logistic regression, unenhanced cone-beam CT, contrast-enhanced cone-beam CT, cone-beam CT–based liver perfusion mapping, mean value of PBV, and maximum value of PBV of tumor were significant in response assessment for per tumor and per patient (per tumor, all P < .001; per patient, P = .015, P = .001, P < .001, P = .020, and P = .032). Mean value of PBV of tumor was excellent for evaluating technical success with the highest C-statistic (0.880 and 0.920 for per tumor and per patient), followed by that of visual assessment of cone-beam CT–based liver perfusion mapping (0.864 and 0.908). ConclusionsCone-beam CT–based liver perfusion mapping provided reliable images to evaluate technical success after transarterial chemoembolization of HCC by qualitative visual assessment and quantitative perfusion values.

Diluted Contrast-enhanced Cone-beam CT during Acute-phase Recanalization Therapy for Occlusion of the Middle Cerebral Artery

Objective: We here report the methods for and efficacy of C-arm cone-beam CT (CBCT) with diluted contrast medium during the recanalization therapy in acute ischemic stroke patients with middle cerebral artery occlusion.

Optimizing contrast-enhanced cone-beam CT protocol to facilitate simultaneous visualization of neurovascular pathologies and surrounding structures of interest.

Contrast-enhanced cone-beam computed tomography (CBCT) imaging is commonly used for evaluating neurovascular stents and their relationship to the parent artery or vascular pathologies such as arteriovenous malformations (AVMs) and dural arteriovenous fistulas (dAVFs) in the context of surrounding anatomical structures. The purpose of this study was to understand the effects of varying concentrations of contrast medium used in CBCT imaging for optimal visualization of various endovascular devices and anatomical pathologies. Thirty-five patients with various neurovascular pathologies were included in the study. Contrast-enhanced CBCT images (20 s DR, Siemens syngo DynaCT, Siemens AG, Forchheim, Germany) were acquired in all cases, with varying dilutions of contrast medium, from 1% to 30%. The injection rate was kept constant at 3 cc/sec with an X-ray delay of two sec, and a total volume of 66 cc of diluted contrast was administered. Results from visual and quantitative analysis were reported. Ten percent dilution of contrast medium resulted in the best image differentiation between flow-diverter devices and the parent artery. Concentrations as low as 2.5% contrast medium also resulted in identifying AVMs in the context of the surrounding brain parenchyma, whereas 20% to 30% dilution provided the best visualization of residual AVMs with prior Onyx embolization and dAVFs in the presence of bony structures. Simultaneous visualization of brain parenchyma, bony structures, devices, and pathological anatomy using contrast-enhanced CBCT imaging is feasible with appropriate doses of iodinated contrast, and should be tailored to the individual case based on the goals of CBCT.

Ultrasound and cone beam CT fusion for liver ablation: technical note

Purpose: To assess the feasibility of fusion imaging between intraprocedural ultrasound (US) and contrast-enhanced cone-beam CT (CBCT) for small (< 2 cm) hepatocellular carcinoma (HCC).Materials and methods: Six patients (five males, one female, age range 58–80, mean 69 years), with small (mean diameter 16.8 mm) HCC poorly visible at US underwent percutaneous microwave ablation under US/CBCT fusion guidance. During general anesthesia with apnea control, a contrast- enhanced CBCT was acquired with an active tracker. Subsequently, real time US images were fused with CBCT images, and treatment performed under fusion imaging guidance. Feasibility of fusion imaging and percutaneous ablation were assessed, correct targeting (distance from center of tumor and center of ablation area <5 mm) and one-month primary technical efficacy were evaluated. Major and minor complications as well as overall procedural time were recorded.Results: US/CBCT fusion was feasible in all cases, allowing for completion of the treatment as previously planned (technical success 100%). Correct targeting was achieved in 4/6 cases (66%), while in two cases, center of tumor and center of ablated area were respectively 7 and 8 mm distant. At 1 month CT scan, all tumors were completely ablated (primary technical efficacy 100%). No major or minor complications occurred. Mean overall procedure time was 127 min.Conclusions: US/CBCT fusion is a feasible technique for liver ablation, and might represent a useful tool to increase the correct targeting of poorly US-visible HCC nodules in the angio suite.

Novel Breast Imaging and Machine Learning: Predicting Breast Lesion Malignancy at Cone-Beam CT Using Machine Learning Techniques.

The purpose of this study is to evaluate the diagnostic performance of machine learning techniques for malignancy prediction at breast cone-beam CT (CBCT) and to compare them to human readers. Five machine learning techniques, including random forests, back propagation neural networks (BPN), extreme learning machines, support vector machines, and K-nearest neighbors, were used to train diagnostic models on a clinical breast CBCT dataset with internal validation by repeated 10-fold cross-validation. Two independent blinded human readers with profound experience in breast imaging and breast CBCT analyzed the same CBCT dataset. Diagnostic performance was compared using AUC, sensitivity, and specificity. The clinical dataset comprised 35 patients (American College of Radiology density type C and D breasts) with 81 suspicious breast lesions examined with contrast-enhanced breast CBCT. Forty-five lesions were histopathologically proven to be malignant. Among the machine learning techniques, BPNs provided the best diagnostic performance, with AUC of 0.91, sensitivity of 0.85, and specificity of 0.82. The diagnostic performance of the human readers was AUC of 0.84, sensitivity of 0.89, and specificity of 0.72 for reader 1 and AUC of 0.72, sensitivity of 0.71, and specificity of 0.67 for reader 2. AUC was significantly higher for BPN when compared with both reader 1 (p = 0.01) and reader 2 (p < 0.001). Machine learning techniques provide a high and robust diagnostic performance in the prediction of malignancy in breast lesions identified at CBCT. BPNs showed the best diagnostic performance, surpassing human readers in terms of AUC and specificity.

3D Deep Learning Angiography (3D-DLA) from C-arm Conebeam CT.

Deep learning is a branch of artificial intelligence that has demonstrated unprecedented performance in many medical imaging applications. Our purpose was to develop a deep learning angiography method to generate 3D cerebral angiograms from a single contrast-enhanced C-arm conebeam CT acquisition in order to reduce image artifacts and radiation dose. A set of 105 3D rotational angiography examinations were randomly selected from an internal data base. All were acquired using a clinical system in conjunction with a standard injection protocol. More than 150 million labeled voxels from 35 subjects were used for training. A deep convolutional neural network was trained to classify each image voxel into 3 tissue types (vasculature, bone, and soft tissue). The trained deep learning angiography model was then applied for tissue classification into a validation cohort of 8 subjects and a final testing cohort of the remaining 62 subjects. The final vasculature tissue class was used to generate the 3D deep learning angiography images. To quantify the generalization error of the trained model, we calculated the accuracy, sensitivity, precision, and Dice similarity coefficients for vasculature classification in relevant anatomy. The 3D deep learning angiography and clinical 3D rotational angiography images were subjected to a qualitative assessment for the presence of intersweep motion artifacts. Vasculature classification accuracy and 95% CI in the testing dataset were 98.7% (98.3%-99.1%). No residual signal from osseous structures was observed for any 3D deep learning angiography testing cases except for small regions in the otic capsule and nasal cavity compared with 37% (23/62) of the 3D rotational angiographies. Deep learning angiography accurately recreated the vascular anatomy of the 3D rotational angiography reconstructions without a mask. Deep learning angiography reduced misregistration artifacts induced by intersweep motion, and it reduced radiation exposure required to obtain clinically useful 3D rotational angiography.

An evaluation on novel application of cone-beam CT imaging with multi-volume technique in carotid body tumor.

Due to the high risk of vascular and nerve damage during surgery, precise pre-operative evaluation of carotid body tumor (CBT) is important. We aim to apply intra-operative contrast-enhanced cone-beam CT (CBCT) with multi-volume technique in CBT evaluation, where the tumor, patent carotid arteries, and skull are demonstrated in three different colors, and to compare this novel technique with traditional computed tomography angiography (CTA). Seven CBT patients scheduled for traditional surgical removal were enrolled in this study between October 2013 and March 2016. For each patient, two CBCT scans were performed on the carotid region both pre- and post-operatively, with contrast injected into the common carotid artery directly. CT-like cross-sectional slices were then reconstructed with a dedicated workstation, and a novel multi-volume technique was further applied for advanced image post-processing. For all seven patients, the anatomic relationship between tumor and surrounding vessels was clearly demonstrated by reconstructed CBCT images with multiple fused volumes. Carotid was either completely or partially incarcerated by tumors. Interestingly, two sets of draining vein systems of CBT were found feeding into the internal jugular vein and the anterior vertebral venous plexus, respectively, which have not been revealed in pre-operative CTA. Post-operative CBCT confirmed the thorough removal of the tumor with an intact preservation of the internal carotid artery. CBCT with multi-volume technique outperforms CTA in discovering fine structures and revealing tumor-vessel relationship for CBT. This emerging imaging technique would offer more accurate diagnosis of CBT and assist in the decision of surgical plan.

The Role of Dual-Phase Cone-Beam CT in Predicting Short-Term Response after Transarterial Chemoembolization for Hepatocellular Carcinoma

PurposeTo identify computational and qualitative features derived from dual-phase cone-beam CT that predict short-term response in patients undergoing transarterial chemoembolization for hepatocellular carcinoma (HCC). Materials and MethodsThis retrospective study included 43 patients with 59 HCCs. Six features were extracted, including intensity of tumor enhancement on both phases and characteristics of the corona on the washout phase. Short-term response was evaluated by modified Response Evaluation Criteria in Solid Tumors on follow-up imaging, and extracted features were correlated to response using univariate and multivariate analyses. ResultsUnivariate and multivariate analyses did not reveal a correlation between absolute and relative tumor enhancement characteristics on either phase with response (arterial P = .21; washout P = .40; ∆ P = .90). On multivariate analysis of qualitative characteristics, the presence of a diffuse corona was an independent predictor of incomplete response (P = .038) and decreased the odds ratio of objective response by half regardless of tumor size. ConclusionsComputational features extracted from contrast-enhanced dual-phase cone-beam CT are not prognostic of response to transarterial chemoembolization in patients with HCC. HCCs that demonstrate a diffuse, patchy corona have reduced odds of achieving complete response after transarterial chemoembolization and should be considered for additional treatment with an alternative modality.

Contrast media-assisted in-treatment cone beam CT during single-isocentre volumetric-modulated arc therapy for multiple brain metastases: a case study

A direct visualization technique for verifying intrafractional localization accuracy of multiple brain metastases during single-isocentre volumetric-modulated arc therapy has been proposed using contrast media-assisted in-treatment cone beam CT (CBCT). Contrast-enhanced planning CT images were acquired immediately after intravenous bolus administration of iodized contrast media at a dose of 2 ml kg–1. Out of 41 nodules detected on the images, 8 lesions were contoured as high-risk gross tumour volumes (GTVs). Prior to each treatment, CBCT imaging was performed to match the skull structures with the planning CT images. Immediately after another intravenous bolus injection of the iodized contrast media at the same dose as administered for the planning CT imaging, contrast-enhanced CBCT images were acquired during volumetric-modulated arc therapy delivery, thereby providing direct verification of time-averaged tumour position during treatment. The planning target volume contours were overlaid with the in-treatment CBCT images, thereby allowing us to directly visualize the localization accuracy of each GTV when the beam delivery was completed. It was visually confirmed that each GTV was accurately localized inside each planning target volume during beam delivery.

TH‐EF‐207A‐04: A Dynamic Contrast Enhanced Cone Beam CT Technique for Evaluation of Renal Functions

Purpose:To develop a simple but robust method for the early detection and evaluation of renal functions using dynamic contrast enhanced cone beam CT technique.Methods:Experiments were performed on an integrated imaging and radiation research platform developed by our lab. Animals (n=3) were anesthetized with 20uL Ketamine/Xylazine cocktail, and then received 200uL injection of iodinated contrast agent Iopamidol via tail vein. Cone beam CT was acquired following contrast injection once per minute and up to 25 minutes. The cone beam CT was reconstructed with a dimension of 300×300×800 voxels of 130×130×130um voxel resolution. The middle kidney slices in the transvers and coronal planes were selected for image analysis. A double exponential function was used to fit the contrast enhanced signal intensity versus the time after contrast injection. Both pixel‐based and region of interest (ROI)‐based curve fitting were performed. Four parameters obtained from the curve fitting, namely the amplitude and flow constant for both contrast wash in and wash out phases, were investigated for further analysis.Results:Robust curve fitting was demonstrated for both pixel based (with R2&gt;0.8 for &gt;85% pixels within the kidney contour) and ROI based (R2&gt;0.9 for all regions) analysis. Three different functional regions: renal pelvis, medulla and cortex, were clearly differentiated in the functional parameter map in the pixel based analysis. ROI based analysis showed the half‐life T1/2 for contrast wash in and wash out phases were 0.98±0.15 and 17.04±7.16, 0.63±0.07 and 17.88±4.51, and 1.48±0.40 and 10.79±3.88 minutes for the renal pelvis, medulla and cortex, respectively.Conclusion:A robust method based on dynamic contrast enhanced cone beam CT and double exponential curve fitting has been developed to analyze the renal functions for different functional regions. Future study will be performed to investigate the sensitivity of this technique in the detection of radiation induced kidney dysfunction.

3:00 PMAbstract No. 178 - Improved liver lesion detectability using a split-bolus single-phase contrast-enhanced cone-beam CT (CBCT) before transarterial chemoembolization (TACE)

3:00 PMAbstract No. 178 - Improved liver lesion detectability using a split-bolus single-phase contrast-enhanced cone-beam CT (CBCT) before transarterial chemoembolization (TACE)