Impact of 3D Rotational Angiography on Liver Embolization Procedures: Review of Technique and Applications

Angiography with cone-beam CT versus contrast-enhanced MRI for living donor transplant imaging: Is MRI enough?

The purpose of this study is to compare the subjective and objective quality and confidence between conventional angiography with cone-beam computed tomography (CBCT) and magnetic resonance imaging (MRI) for the preoperative evaluation of potential donors for living donor liver transplant. Seventeen patients undergoing preoperative donor evaluation for living donor liver transplantation that underwent angiography with CBCT and contrast-enhanced MRI for evaluation of hepatic vascular anatomy were included in the study. Four attending radiologists interpreted anonymized, randomized angiography with CBCT images and MRIs, rating the diagnostic quality and confidence of their interpretation (on a 3-point scale) for each element, as well as clinically relevant measurements. Overall, the readers rated the quality of angiography with CBCT to be higher than that of MRI (median [interquartile range] = 3 (2, 3) vs. 2 (1-3), p < 0.001) across all patients. Readers of angiography with CBCT had more confidence in their interpretations as an average of all elements evaluated than the MRI readers (3 (3) vs. 3 (2, 3), p < 0.001). When the same reader interpreted both MRI and CBCT, the right hepatic artery diameter (3.8 mm ± 0.72 mm vs. 4.5 mm ± 1.2 mm, p < 0.005) and proper hepatic artery diameter (4.43 mm ± 0.98 mm vs. 5.4 mm ± 1.05 mm, p < 0.003) were significantly different between MRI and CBCT. There was poor interrater reliability for determining segment IV arterial supply for both modalities (κ < 0.2). Angiography with CBCT provides higher subjective diagnostic quality and greater radiologist confidence than MRI. The difference in measurements between CBCT and MRI when the same reader reads both studies suggests CBCT adds additional information over MRI evaluation alone.

Assessment of abdominal organ dose and image quality in varying arc trajectory interventional C-arm cone beam CT

PURPOSE

The aim of this study was to investigate the effect of varying arc exposure trajectory on radiation dose to radiosensitive organs and to assess image quality in abdominal C-arm cone beam computed tomography (CBCT) interventional procedures using a latest generation system.

METHODS

An anthropomorphic phantom that simulates the average adult individual was used. Individual-specific Monte Carlo (MC) simulation dosimetry was performed to estimate organ doses (OD) in abdominal C-arm CBCT. Seven examination protocols prescribed by the system for vascular and soft tissue CBCT, were simulated. These protocols are differentiated in the range of the arc exposure trajectory and the level of radiation dose delivered to the patient. OD was estimated for liver, adrenals, kidneys, pancreas, stomach, gall bladder, spleen, bone and skin. Image noise, signal to noise ratio (SNR), contrast to noise ratio (CNR) and in-plane spatial resolution were assessed using CT-specific image quality assessment phantoms.

RESULTS

OD was found to depend on the range of arc trajectory and was higher for posterior located organs. In vascular protocols OD ranged from 4.75 mGy for skin to 0.60 mGy for bone. Image noise was higher in vascular protocols than in soft tissue ones. SNR and CNR were significantly modified among different soft tissue protocols (P < 0.05). In-plane spatial resolution was found 0.80 lp/mm in vascular as opposed to 0.41 lp/mm in soft tissue protocols.

CONCLUSIONS

The current results may be used to estimate OD for different examination protocols and enable operators choose the appropriate acquisition protocol on the preprogrammed interventional task.

THE EFFECTS OF CONE-BEAM COMPUTED TOMOGRAPHY IMAGING GUIDANCE ON PATIENT RADIATION EXPOSURES IN TRANS-ARTERIAL CHEMOEMBOLISATION FOR HEPATOCELLULAR CARCINOMA

This study investigated the effects of cone-beam computed tomography (CBCT) guidance in trans-arterial chemoembolisation (TACE) procedures on the number of digital subtraction angiography (DSA) runs acquired and total patient radiation exposure in patients with hepatocellular carcinoma (HCC). A retrospective, analytical cross-sectional, single institution, study was conducted. Dose data were compared across the control (DSA guidance alone) and study (DSA and CBCT guidance) groups. A total of 122 procedures were included within the study. There was a significant reduction in the number of DSA runs (3 vs 5, p < 0.001) and DSA air kerma-area product (PKA) (3077.3 vs 4276.6 μGym2, p = 0.042) for the study group when compared to the control group. Total procedural PKA and total procedural reference air kerma (Ka,r) were shown to be 50 and 73% higher, respectively, for the study group when compared to the control group. CBCT imaging guidance does reduce the number of DSA runs and DSA PKA required to complete the TACE procedure for patients diagnosed with HCC; however, a substantial increase in total procedural PKA is to be expected and it is thus important that this increased dose is carefully considered and justified.

Portal Vein Embolization Using N-Butyl Cyanoacrylate-Glue: What Impact Does a Central Vascular Plug Have?

Purpose

To examine if the addition of a central vascular plug (CVP) to portal vein embolization (PVE) with N-butyl cyanoacrylate-glue (NBCA) increases future liver remnant (FLR) growth.

Material and Methods

This is a single-center retrospective study of 115 consecutive patients with colorectal liver metastases undergoing PVE in 2013–2019. All patients were embolized with NBCA as the main embolic agent. In 2017–2019 NBCA was combined with a CVP in the central part of the right portal vein. Growth of the FLR and standardized FLR (sFLR) including degree of hypertrophy (DH) and kinetic growth rate (KGR) were analyzed, as well as procedure data such as use of cone-beam CT (CBCT), dose area product (DAP), fluoroscopy time and contrast dose.

Results

A total of 40 patients (35%) underwent PVE with a combination of CVP and NBCA. The DH was higher in these patients after 4 weeks, mean 13.6% (SD 7.8) vs. 10.5% (SD 6.4; p = 0.022), verified in multivariate analysis (coefficient 4.1, p = 0.015). A CVP did not significantly increase the resection rate (90% vs 82%, p = 0.4). Cone beam CT was used in 65 patients (57%). Use of CBCT did not affect FLR growth, and fluoroscopy time and contrast doses were not different in patients having a CBCT or not. Slightly lower DAP (median 3375 vs. 4499 cGy*cm²; p = 0.09) was seen in procedures where CBCT was used.

Conclusion

A CVP in addition to NBCA embolization was associated with increased growth of the FLR compared to NBCA alone.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00270-021-03014-w.

CIRSE Standards of Practice on Hepatic Transarterial Chemoembolisation

This CIRSE Standards of Practice document is aimed at interventional radiologists and provides best practices for performing transarterial chemoembolisation. It has been developed by an expert writing group under the guidance of the CIRSE Standards of Practice Committee. It will encompass all technical details reflecting European practice of different TACE procedures (Lp-TACE, DEM-TACE, DSM-TACE, b-TACE) as well as revising the existing literature on the various clinical indications (HCC, mCRC, ICC, NET). Finally, new frontiers of development will also be discussed.

Natural History of Incidental Enhancing Nodules on Cone-Beam Computed Tomography during Transarterial Therapy of Hepatocellular Carcinoma

PURPOSE

To evaluate the natural history of incidental enhancing nodules (IENs) on contrast-enhanced cone-beam computed tomography (CT) during transarterial treatment of hepatocellular carcinoma (HCC).

MATERIAL AND METHODS

A single-center retrospective analysis of 100 patients with HCC who underwent contrast-enhanced cone-beam CT prior to transarterial treatment from August 2015 to June 2019 was performed. Inclusion criteria were patients with segmental distribution sublobar HCC, contrast-enhanced cone-beam CT of the target lesion and nontarget liver parenchyma, and follow-up cross-sectional imaging. Patients with IENs ≥3 mm that did not meet imaging criteria for HCC were analyzed. Exclusion criteria included biphenotypic tumors and IEN present inside the treated area of the liver.

RESULTS

Fifty-six patients demonstrated 154 IENs on contrast-enhanced cone-beam CT, of which 13 IENs (8.5%) progressed to HCC. The mean primary tumor size was 29 mm (range: 10.2-189 mm). Ten patients had ≥4 IENs, and 46 patients had 1-3 IENs. The mean IEN size was 6.8 mm (range: 3.0-16.3 mm). The median follow-up interval after contrast-enhanced cone-beam CT was 282 days (interquartile range: 143-522). Increased alpha-fetoprotein before treatment (≥15.5 ng/mL, P = .035), having ≥4 IENs (P = .020), and hepatitis C virus (P = .015) were significantly correlated with IEN progression to HCC. No statistically significant differences were identified in baseline neutrophil-to-lymphocyte ratio, targeted HCC characteristics (size, macrovascular invasion, infiltrative pattern, enhancement pattern, and satellite lesions), and IEN size between those with IEN progression to HCC and those without.

CONCLUSIONS

Most IENs of ≥3 mm on contrast-enhanced cone-beam CT in patients with segmental distribution sublobar HCC do not progress to HCC. Patients with segmental distribution sublobar HCC with ≥4 IENs, alpha-fetoprotein elevation (≥15.5 ng/mL), or hepatitis C virus have an increased risk of IEN progression to HCC.

Role of Fusion Imaging in Image-Guided Thermal Ablations

Thermal ablation (TA) procedures are effective treatments for several kinds of cancers. In the recent years, several medical imaging advancements have improved the use of image-guided TA. Imaging technique plays a pivotal role in improving the ablation success, maximizing pre-procedure planning efficacy, intraprocedural targeting, post-procedure monitoring and assessing the achieved result. Fusion imaging (FI) techniques allow for information integration of different imaging modalities, improving all the ablation procedure steps. FI concedes exploitation of all imaging modalities’ strengths concurrently, eliminating or minimizing every single modality’s weaknesses. Our work aims to give an overview of FI, explain and analyze FI technical aspects and its clinical applications in ablation therapy and interventional oncology.

Efficacy and Safety of Supplemental Transarterial Chemoembolization Through Extrahepatic Collateral Arteries with Drug-eluting Beads: Treatment for Unresectable Hepatocellular Carcinoma

Purpose

To evaluate the therapeutic efficacy and safety of supplement transarterial chemoembolization (TACE) with drug-eluting beads TACE (DEB-TACE) through extrahepatic collateral (EHC) arteries for the treatment of hepatocellular carcinoma (HCC).

Patients and Methods

In this retrospective study, 61 unresectable HCC patients with treatment-naïve EHC blood supplies who received TACE from January 2016 to March 2019 were enrolled; of these patients, 42 (68.9%) received DEB-TACE, and 19 (31.1%) received cTACE. The hepatic tumor feeding arteries were treated in the same TACE session if it presented. The tumor response, time-to-progression (TTP), and overall survival (OS) were analyzed. Safety was assessed based on the occurrence of liver function deterioration and major complications within three months after TACE.

Results

DEB-TACE showed better efficacy than cTACE in the disease control rate (p=0.001), overall response rate (p=0.005), the TTP (eight months vsthree months, p=0.002) and the OS (23.8 months vs nine months, p=0.045). Nine patients in the DEB-TACE group and one patient in the cTACE group were downstaged to resection or liver transplantation (21.4% vs 5.3%, p=0.151). DEB-TACE and cTACE have no difference in the acute and chronic liver toxicity. With regard to complications, there was no significant difference in the occurrence of both major (16.7% vs 21.1%, p=0.72) and minor (57.1% vs 47.4%, p=0.48) complications between DEB-TACE and cTACE.

Conclusion

DEB-TACE through EHC arteries has a potential therapeutic effect in the treatment of unresectable HCC, with comparable safety compared with cTACE.

Intra-procedural dual phase cone beam computed tomography has a better diagnostic accuracy over pre-procedural MRI and MDCT in detection and characterization of HCC in cirrhotic patients undergoing TACE procedure

PURPOSE

This study was directed to compare diagnostic accuracy of dual-phase cone beam computed tomography (DP-CBCT) vs pre-procedural second line imaging modality (SLIM [multidetector computed tomography and magnetic resonance imaging]) to detect and characterize hepatocellular carcinoma (HCC) in cirrhotic patients with indication for trans-arterial chemoembolization (TACE).

METHODS

This is a single centre, retrospective, and observational study. Exclusion criteria were not-assisted DP-CBCT TACE, and unavailable follow-up SLIM. We evaluated 280 consecutive patients (January/2015-Febraury/2019). Seventy-two patients were eligible. Three radiologists in consensus reviewed: pre-procedural SLIM, DP-CBCT, and SLIM at follow-up, with 4 months of interval between each reading. Hyper-vascular foci (HVF) were detected and characterized. Diameter was recorded. Radiological behaviour, according to LI-RADS criteria, of HFV throughout follow-up time was the reference standard. Diagnostic accuracy was calculated for pre-procedural SLIM and DP-CBCT and evaluated through receiver operating characteristic curve. HVF only visible on DP-CBCT (defined as occult) were analysed. Tumour diameters were compared.

RESULTS

Median time between pre-procedural SLIM and DP-CBCT and between DP-CBCT and definitive radiological diagnosis of HVF were 46.0 days (95%CI 36.5-55.0) and 30.5 days (95%CI 29.0-33.0), respectively. DP-CBCT had a better diagnostic performance than pre-examination SLIM (sensitivity 99%vs78%; specificity 89%vs85%; PPV 99%vs99%; NPV 92%vs30%; and accuracy 94%vs79%). DP-CBCT diagnosed 63 occult HVF. Occult HCC were 54/243 (22.2%). Six were occult angiomas. Three were false positive. Mean diameter was significantly higher in DP-CBCT vs pre-procedural SLIM (+7.5% [95%CI 3.7-11.3], p < 0.05).

CONCLUSIONS

DP-CBCT has a better diagnostic accuracy and NPV than pre-procedural SLIM in cirrhotic patients with indication for TACE.

CBCT-Based Image Guidance for Percutaneous Access: Electromagnetic Navigation Versus 3D Image Fusion with Fluoroscopy Versus Combination of Both Technologies-A Phantom Study

PURPOSE

We set out to compare three types of three-dimensional CBCT-based imaging guidance modalities in a phantom study: image fusion with fluoroscopy (IF), electromagnetic navigation (EMN) and the association of both technologies (CEMNIF).

MATERIALS AND METHODS

Four targets with a median diameter of 11 mm [first quartile (Q1): 10; third quartile (Q3): 12] with acute angle access (z-axis < 45°) and four targets of 10 mm [8-15] with large angle access (z-axis > 45°) were defined on an abdominal phantom (CIRS, Meditest, Tabuteau, France). Acute angle access targets were punctured using IF, EMN or CEMNIF and large angle access targets with EMN by four operators with various experiences. Efficacy (target reached), accuracy (distance between needle tip and target center), procedure time, radiation exposure and reproducibility were explored and compared.

RESULTS

All targets were reached (100% efficacy) by all operators. For targets with acute angle access, procedure times (EMN: 265 s [236-360], IF: 292 s [260-345], CEMNIF: 320 s [240-333]) and accuracy (EMN: 3 mm [2-5], IF: 2 mm [1-3], CEMNIF: 3 mm [2-4]) were similar. Radiation exposure (EMN: 0; IF: 708 mGy.cm² [599-1128]; CEMNIF: 51 mGy.cm² [15-150]; p < 0.001) was significantly higher with IF than with CEMNIF and EMN. For targets with large angle access, procedure times (EMN: 345 s [259-457], CEMNIF: 425 s [340-473]; p = 0.01) and radiation exposure (EMN: 0, CEMIF: 159 mGy.cm² [39-316]; p < 0.001) were significantly lower with EMN but with lower accuracy (EMN: 4 mm [4-6] and CEMNIF: 4 mm [3, 4]; p = 0.01). The operator's experience did not impact the tested parameters regardless of the technique.

CONCLUSION

In this phantom study, EMN was not limited to acute angle targets. Efficacy and accuracy of puncture for acute angle access targets with EMN, IF or CEMNIF were similar. CEMNIF is more accurate for large angle access targets at the cost of a slightly higher procedure time and radiation exposure.

Sequential dual-phase cone-beam CT is able to intra-procedurally predict the one-month treatment outcome of multi-focal HCC, in course of degradable starch microsphere TACE

OBJECTIVE

To evaluate the prognostic value of sequential dual-phase CBCT (DP-CBCT) imaging performed during degradable starch microsphere TACE (DSM-TACE) session in predicting the HCC's response to treatment, evaluate with modify response evaluation criteria in solid tumours (mRECIST) at 1-month multi-detector CT (MDCT) follow-up.

MATERIALS AND METHODS

Between January and May 2018, 24 patients (68.5 ± 8.5 year [45-85]) with HCC lesions (n = 96 [average 4/patient]) were prospectively enrolled. Imaging assessment included: pre-procedural MDCT, intra-procedural DP-CBCT performed before first and second DSM-TACEs and 1-month follow-up MDCT. Lesions' attenuation/pseudo-attenuation was defined as average value measured on ROIs (HU for MDCT; arbitrary unit called HU* for CBCT). Lesions' attenuation modification was correlated with the post-procedural mRECIST criteria at 1-month MDCT.

RESULTS

Eighty-two DSM-TACEs were performed. Lesion's attenuation values were: pre-procedural MDCT arterial phase (AP) 107.00 HU (CI 95% 100.00-115.49), venous phase (VP) 85.00 HU (CI 95% 81.13-91.74); and lesion's pseudo-attenuation were: first CBCT-AP 305.00 HU* (CI 95% 259.77-354.04), CBCT-VP 155.00 HU* (CI 95% 135.00-163.34). For second CBCT were: -AP 210.00 HU* (CI 95% 179.47-228.58), -VP 141.00 HU* (CI 95% 125.47-158.11); and for post-procedural MDCT were: -AP 95.00 HU (CI 95% 81.35-102.00), -VP 83.00 HU (CI 95% 78.00-88.00). ROC curve analysis showed that a higher difference pseudo-attenuation between first and second DP-CBCTs is related to treatment response. The optimal cut-off value of the difference between first and second CBCT-APs to predict complete response, objective response (complete + partial response) and overall disease control (objective response + stable disease) were > 206 HU* (sensitivity 80.0%, specificity 81.7%), > 72 HU* (sensitivity 79.5%, specificity 83.0%) and > - 7 HU* (sensitivity 91.6%, specificity 65.4%), respectively.

CONCLUSIONS

DP-CBCT can predict intra-procedurally, by assessing lesion pseudo-attenuation modification, the DSM-TACE 1-month treatment outcome.

Predictors of Prostatic Artery Embolization Technical Outcomes: Patient and Procedural Factors

PURPOSE

To identify technical factors that significantly change prostatic artery embolization (PAE) technical outcomes and to derive and test technical outcome predictive models.

MATERIALS AND METHODS

Retrospective analysis of PAEs performed by 2 operators (OPs) was performed: OP1, between April 2014 and May 2017 (n = 150); OP2, between February 2017 and December 2017 (n = 67). Multivariate analysis with mixed-effects modeling was used to test significance and derive predictive models. Mean difference was used to analyze prediction accuracy.

RESULTS

Moderate versus none subjective iliac tortuosity grade (SITG) and the presence of internal iliac atherosclerosis (PIIAA) versus none were associated with the following respective technical outcome increases: procedure time (PT): 43% (P < .01), 16% (P < .01); fluoroscopy time (FT): 47% (P < .01), 25% (P < .01); contrast volume (CV): 25.6 mL (P < .001), 13.7 mL (P = .01); and dose area product (DAP) 52% (P < .01), 20% (P = 0.03). Prostatic artery origin left obturator versus left superior vesical was associated with a 24% (P = .01) DAP decrease. For every 1 cc that prostate volume increased, CV decreased on average by 0.1 mL (P = .05). For every 1-cm decrease in patient height and 1-kg increase in weight, DAP increased on average by 0.02% (P < .01) for each. Unilateral versus bilateral versus 3-vessel embolization resulted in a 16.3-mL CV decrease on average for each additional vessel embolized (P = .03). The mean absolute differences between predicted and measured technical outcome values were: PT: 16 minutes, FT: 7 minutes, CV: 25 mL, and DAP: 44 Gy·cm².

CONCLUSIONS

In this study, higher SITGs and PIIAA most likely contributed to higher technical outcomes when controlling for the 2 OPs.

Is dual-phase C-arm CBCT sufficiently accurate for the diagnosis of colorectal cancer liver metastasis during liver intra-arterial treatment?

PURPOSE

This study aimed to estimate the accuracy of dual-phase C-arm cone beam computed tomography (CBCT) for the detection of colorectal cancer liver metastases, as compared with multidetector computed tomography (MDCT).

MATERIALS AND METHODS

Between March 2014 and December 2016, 49 consecutive patients referred for intra-arterial treatment for colorectal cancer liver metastases were enrolled in a single-center observational study. All patients were examined with MDCT and with dual-phase C-arm cone beam computed tomography performed after iodine injection in the proper hepatic artery before intra-arterial treatment. Two blinded observers independently reviewed all examinations. Diagnostic accuracy was determined using both a six-cell matrix method and a "worst-case scenario."

RESULTS

Readers identified at MDCT 264 colorectal liver metastases and 43 other liver lesions. The early and late arterial phase showed 240 and 277 liver lesions respectively. A certainty of the diagnosis was obtained in 63% and 85% at the early (EAP) and late arterial phase (LAP), respectively. Streak artifacts or liver segment truncation, or inadequate enhancement was responsible for the inability to see or to correctly adjudicate a lesion to a diagnosis in 27% and 15% of the cases at the EAP and LAP. The "worst-case scenario" yielded a Se and Sp of 58% and 51%, respectively, at EAP and 84% and 70%, respectively, at LAP.

CONCLUSION

On CBCT, EAP showed limited accuracy. LAP provided the best tumor detectability.

KEY POINTS

• The early arterial phase (EAP) yielded poor accuracy: Se = 58% and Sp = 51% (p < 0.0001). • The late arterial phase (LAP) phase yielded good accuracy: Se = 84% and Se = 70% (p = 0.02). • The probability of a correct diagnosis at the EAP was 60%.

Evaluation of three-dimensional iterative image reconstruction in C-arm-based interventional cone-beam CT: A phantom study in comparison with customary reconstruction technique

We compared images obtained using a three-dimensional iterative image reconstruction (3D-IIR) algorithm for C-arm-based interventional cone-beam computed tomography (CBCT) with that using the customary reconstruction technique to quantify the effect of reconstruction techniques on image quality.We scanned 2 phantoms using an angiography unit with digital flat-panel system-an elliptical cylinder acrylic phantom to evaluate spatial resolution and a Catphan phantom to evaluate CT number linearity, image noise, and low-contrast resolution. Three-dimensional imaging was calculated using Feldkamp algorithms, and additional image sets were reconstructed using 3D-IIR at 5 settings (Sharp, Default, Soft+, Soft++, Soft+++). We evaluated quality of images obtained using the 6 reconstruction techniques and analyzed variance to test values of the 10% value of each MTF, mean CT number, and contrast-to-noise ratio (CNR), with P < .05 considered statistically significant.Modulation transfer function curves and CT number linearity among images obtained using the customary technique and the 5 3D-IIR techniques showed excellent agreement. Noise power spectrum curves demonstrated uniform noise reduction across the spatial frequency in the iterative reconstruction, and CNR obtained using all but the Sharp 3D-IIR technique was significantly better than that using the customary reconstruction technique (Sharp, P = .1957; Default, P = .0042; others, P < .0001). Use of 3D-IIR, especially the Soft++ and Soft+++ settings, improved visualization of low-contrast targets.Use of a 3D-IIR can significantly improve image noise and low-contrast resolution while maintaining spatial resolution in C-arm-based interventional CBCT, yielding higher quality images that may increase safety and efficacy in interventional radiology.

State of the art of prostatic arterial embolization for benign prostatic hyperplasia

Prostatectomy via open surgery or transurethral resection of the prostate (TURP) is the standard treatment for benign prostatic hyperplasia (BPH). Several patients present contraindication for standard approach, individuals older than 60 years with urinary tract infection, strictures, post-operative pain, incontinence or urinary retention, sexual dysfunction, and blood loss are not good candidates for surgery. Prostatic artery embolization (PAE) is emerging as a viable method for patients unsuitable for surgery. In this article, we report results about technical and clinical success and safety of the procedure to define the current status.

Single injection dual phase CBCT technique ameliorates results of trans-arterial chemoembolization for hepatocellular cancer

Cone-beam CT (CBCT) application to the field of trans-arterial chemoembolization has been recently the focus of several researches. This imaging modality is performed with a rotation of the C-arm around the patient, without needs of patient repositioning. Datasets are immediately processed, obtaining volumetric CT-like images with the possibility of post-processing and reconstruction of images. Dual phase CBCT recently introduced in clinical practice consists in a first arterial acquisition followed by a delayed acquisition corresponding to a venous phase. The introduction of this feature has overcome the limit of single-phase acquisitions, allowing lesions characterization. Moreover these recent advantages have several intra-procedural implications. Detailed technical and acquisition parameters will be widely exposed in this review with particular attention to: catheter positioning, acquisition delay, injection parameters, patient positioning and contrast dilution. Comparison with standard of practice second line imaging [multidetector computer tomography (MDCT) and MDCT/arteriography] demonstrate the capability of detecting occult nodules providing some clinical implications thus potentially identifying a sub set of patients with aggressive disease behaviour. Other intra-procedural advantages of dual phase CBCT usage consist in a better tumor feeder visualization, reduction of proper DSA and fluoroscopic time, suggestion the presence of an extrahepatic parasitic feeder thus resulting in a more accurate treatment. Finally, the volumetrical intraprocedural evaluation of accumulation of embolic agent has proved to be correlate with treatment response if compared with MRI.

C-Arm Cone Beam CT for Intraprocedural Image Fusion and 3D Guidance in Portal Vein Embolization (PVE)

PURPOSE

Portal vein embolization (PVE) is applied in patients with extended oncologic liver disease to induce hyperplasia of the future liver remnant and make resection feasible. Ultrasound (US) guidance is the gold standard for percutaneous portal vein access. This study evaluated feasibility and safety of C-arm cone beam computed tomography (CBCT) for needle guidance.

MATERIALS AND METHODS

In 10 patients, puncture was performed under 3D needle guidance in a CBCT data set. Contrast-enhanced (CE) CBCT was generated (n = 7), or native CBCT was registered to pre-examination CE-CT via image fusion (n = 3). Technical success, number of punctures, puncture time (time between CBCT acquisition and successful portal vein access), dose parameters and safety were evaluated. For comparison, 10 patients with PVE under US guidance were analyzed retrospectively. Study and control group were matched for age, BMI, INR, platelets, portal vein anatomy.

RESULTS

All interventions were technically successful without intervention-related complications. In the study group, the mean number of puncture attempts was 3.1 ± 2.5. Mean puncture time was 12 min (±10). Mean total dose area product (DAP) was 288 Gy cm² (±154). The mean relative share of CBCT-related radiation exposure was 6% (±3). Intervention times and DAP were slightly higher compared to the control group without reaching significance.

CONCLUSION

CBCT-guided PVE is feasible and safe. The relative dose of CBCT is low compared to the overall dose of the intervention. This technique may be a promising approach for difficult anatomic situations that limit the use of US for needle guidance.

Advanced cone-beam CT venous angiographic imaging

OBJECTIVE The evaluation of the venous neurovasculature, especially the dural venous sinuses, is most often performed using MR or CT venography. For further assessment, diagnostic cerebral angiography may be performed. Three-dimensional rotational angiography (3D-RA) can be applied to the venous system, producing 3D rotational venography (3D-RV) and cross-sectional reconstructions, which function as an adjunct to traditional 2D digital subtraction angiography. METHODS After querying the database of Baylor St. Luke's Medical Center in Houston, Texas, the authors reviewed the radiological and clinical data of patients who underwent 3D-RV. This modality was performed based on standard techniques for 3D-RA, with the catheter placed in the internal carotid artery and a longer x-ray delay calculated based on time difference between the early arterial phase and the venous phase. RESULTS Of the 12 cases reviewed, 5 patients had neoplasms invading a venous sinus, 4 patients with idiopathic intracranial hypertension required evaluation of venous sinus stenosis, 2 patients had venous diverticula, and 1 patient had a posterior fossa arachnoid cyst. The x-ray delay ranged from 7 to 10 seconds. The 3D-RV was used both for diagnosis and in treatment planning. CONCLUSIONS Three-dimensional RV and associated cross-sectional reconstructions can be used to assess the cerebral venous vasculature in a manner distinct from established modalities. Three-dimensional RV can be performed with relative ease on widely available biplane equipment, and data can be processed using standard software packages. The authors present the protocol and technique used along with potential applications to venous sinus stenosis, venous diverticula, and tumors invading the venous sinuses.

Comparison of Image Quality and Diagnostic Performance of Cone-Beam CT during Drug-Eluting Embolic Transarterial Chemoembolization and Multidetector CT in the Detection of Hepatocellular Carcinoma

PURPOSE

To compare image quality and diagnostic performance of cone-beam computed tomography (CT) and multidetector CT in the detection of hypervascular hepatocellular carcinoma (HCC) in patients with cirrhosis undergoing transarterial chemoembolization with drug-eluting embolic agents.

MATERIALS AND METHODS

Fifty-five consecutive patients referred for chemoembolization of hypervascular HCC were prospectively enrolled. Imaging included preprocedural multidetector CT within 1 month before planned treatment, intraprocedural cone-beam CT, and 1-month follow-up multidetector CT. Analysis of image quality was performed with calculations of lesion-to-liver contrast-to-noise ratio (LLCNR) and lesion-to-liver signal-to-noise-ratio (LLSNR). One-month follow-up multidetector CT was considered the reference standard for the detection of HCC nodules.

RESULTS

Median LLCNR values were 3.94 (95% confidence interval [CI], 3.06-5.05) for preprocedural multidetector CT and 6.90 (95% CI, 5.17-7.77) for intraprocedural cone-beam CT (P < .0001). Median LLSNR values were 11.53 (95% CI, 9.51-12.44) for preprocedural multidetector CT and 9.36 (95% CI, 8.12-10.39) for intraprocedural cone-beam CT (P < .0104). Preprocedural multidetector CT detected 115 hypervascular nodules with typical HCC behavior, and cone-beam CT detected 15 additional hypervascular nodules that were also visible on 1-month follow-up multidetector CT.

CONCLUSIONS

Cone-beam CT has a significantly higher diagnostic performance compared with preprocedural multidetector CT in the detection of HCCs and can influence management of patients with cirrhosis by identifying particularly aggressive tumors.

Benign Prostatic Hyperplasia: Cone-Beam CT in Conjunction with DSA for Identifying Prostatic Arterial Anatomy

Purpose To describe findings in prostatic arteries (PAs) at digital subtraction angiography (DSA) and cone-beam computed tomography (CT) that allow identification of benign prostatic hyperplasia and to determine the value added with the use of cone-beam CT. Materials and Methods This retrospective single-institution study was approved by the institutional review board, and the requirement for written informed consent was waived. From February 2009 to December 2014, a total of 148 patients (mean age ± standard deviation, 70.5 years ± 14.5) underwent DSA of the internal iliac arteries and cone-beam CT with a flat-detector angiographic system before they underwent prostate artery embolization. Both the DSA and cone-beam CT images were evaluated by two interventional radiologists to determine the number of independent PAs and their origins and anastomoses with adjacent arteries. The exact McNemar test was used to compare the detection rate of the PAs and the anastomoses with DSA and with cone-beam CT. Results The PA anatomy was evaluated successfully by means of cone-beam CT in conjunction with DSA in all patients. Of the 296 pelvic sides, 274 (92.6%) had only one PA. The most frequent PA origin was the common gluteal-pudendal trunk with the superior vesicular artery in 118 (37.1%), followed by the anterior division of the internal iliac artery in 99 (31.1%), and the internal pudendal artery in 77 (24.2%) pelvic sides. In 67 (22.6%) pelvic sides, anastomoses to adjacent arteries were documented. The numbers of PA origins and anastomoses, respectively, that could be identified were significantly higher with cone-beam CT (301 of 318 [94.7%] and 65 of 67 [97.0%]) than with DSA (237 [74.5%] and 39 [58.2%], P < .05). Cone-beam CT provided essential information that was not available with DSA in 90 of 148 (60.8%) patients. Conclusion Cone-beam CT is a useful adjunctive technique to DSA for identification of the PA anatomy and provides information to help treatment planning during prostatic arterial embolization. ^© RSNA, 2016.

Imaging of HCC-Current State of the Art

Early diagnosis of hepatocellular carcinoma (HCC) is crucial for optimizing treatment outcome. Ongoing advances are being made in imaging of HCC regarding detection, grading, staging, and also treatment monitoring. This review gives an overview of the current international guidelines for diagnosing HCC and their discrepancies as well as critically summarizes the role of magnetic resonance imaging (MRI) and computed tomography (CT) techniques for imaging in HCC. The diagnostic performance of MRI with nonspecific and hepatobililiary contrast agents and the role of functional imaging with diffusion-weighted imaging will be discussed. On the other hand, CT as a fast, cheap and easily accessible imaging modality plays a major role in the clinical routine work-up of HCC. Technical advances in CT, such as dual energy CT and volume perfusion CT, are currently being explored for improving detection, characterization and staging of HCC with promising results. Cone beam CT can provide a three-dimensional analysis of the liver with tumor and vessel characterization comparable to cross-sectional imaging so that this technique is gaining an increasing role in the peri-procedural imaging of HCC treated with interventional techniques.