Ruediger E. Schernthaner

A Novel Inherently Radiopaque Bead for Transarterial Embolization to Treat Liver Cancer - A Pre-clinical Study

Purpose: Embolotherapy using microshperes is currently performed with soluble contrast to aid in visualization. However, administered payload visibility dimishes soon after delivery due to soluble contrast washout, leaving the radiolucent beads location unknown. The objective of our study was to characterize inherently radiopaque beads (RO Beads) in terms of physicomechanical properties, deliverability and imaging visibility in a rabbit VX2 liver tumor model. Materials and Methods: RO Beads, which are based on LC Bead® platform, were compared to LC Bead. Bead size (light microscopy), equilibrium water content (EWC), density, X-ray attenuation and iodine distribution (micro-CT), suspension (settling times), deliverability and in vitro penetration were investigated. Fifteen rabbits were embolized with either LC Bead or RO Beads + soluble contrast (iodixanol-320), or RO Beads+dextrose. Appearance was evaluated with fluoroscopy, X-ray single shot, cone-beam CT (CBCT). Results: Both bead types had a similar size distribution. RO Beads had lower EWC (60-72%) and higher density (1.21-1.36 g/cc) with a homogeneous iodine distribution within the beads interior. RO Beads suspension time was shorter than LC Bead, with durable suspension (>5 min) in 100% iodixanol. RO Beads ≤300 µm were deliverable through a 2.3-Fr microcatheter. Both bead types showed similar penetration. Soluble contrast could identify target and non-target embolization on fluoroscopy during administration. However, the imaging appearance vanished quickly for LC Bead as contrast washed-out. RO Beads+contrast significantly increased visibility on X-ray single shot compared to LC Bead+contrast in target and non-target arteries (P=0.0043). Similarly, RO beads demonstrated better visibility on CBCT in target arteries (P=0.0238) with a trend in non-target arteries (P=0.0519). RO Beads+dextrose were not sufficiently visible to monitor embolization using fluoroscopy. Conclusion: RO Beads provide better conspicuity to determine target and non-target embolization compared to LC Bead which may improve intra-procedural monitoring and post-procedural evaluation of transarterial embolization.

Texture-based classification of different gastric tumors at contrast-enhanced CT

PURPOSEnTo determine the feasibility of texture analysis for the classification of gastric adenocarcinoma, lymphoma, and gastrointestinal stromal tumors on contrast-enhanced hydrodynamic-MDCT images.nnnMATERIALS AND METHODSnThe arterial phase scans of 47 patients with adenocarcinoma (AC) and a histologic tumor grade of [AC-G1, n=4, G1, n=4; AC-G2, n=7; AC-G3, n=16]; GIST, n=15; and lymphoma, n=5, and the venous phase scans of 48 patients with AC-G1, n=3; AC-G2, n=6; AC-G3, n=14; GIST, n=17; lymphoma, n=8, were retrospectively reviewed. Based on regions of interest, texture analysis was performed, and features derived from the gray-level histogram, run-length and co-occurrence matrix, absolute gradient, autoregressive model, and wavelet transform were calculated. Fisher coefficients, probability of classification error, average correlation coefficients, and mutual information coefficients were used to create combinations of texture features that were optimized for tumor differentiation. Linear discriminant analysis in combination with a k-nearest neighbor classifier was used for tumor classification.nnnRESULTSnOn arterial-phase scans, texture-based lesion classification was highly successful in differentiating between AC and lymphoma, and GIST and lymphoma, with misclassification rates of 3.1% and 0%, respectively. On venous-phase scans, texture-based classification was slightly less successful for AC vs. lymphoma (9.7% misclassification) and GIST vs. lymphoma (8% misclassification), but enabled the differentiation between AC and GIST (10% misclassification), and between the different grades of AC (4.4% misclassification). No texture feature combination was able to adequately distinguish between all three tumor types.nnnCONCLUSIONnClassification of different gastric tumors based on textural information may aid radiologists in establishing the correct diagnosis, at least in cases where the differential diagnosis can be narrowed down to two histological subtypes.

Coronary artery stent imaging with 128-slice dual-source CT using high-pitch spiral acquisition in a cardiac phantom: comparison with the sequential and low-pitch spiral mode

ObjectiveTo evaluate coronary stents in vitro using 128-slice-dual-source computed tomography (CT).MethodsTwelve different coronary stents placed in a non-moving cardiac/chest phantom were examined by 128-slice dual-source CT using three CT protocols [high-pitch spiral (HPS), sequential (SEQ) and conventional spiral (SPIR)]. Artificial in-stent lumen narrowing (ALN), visible inner stent area (VIA), artificial in-stent lumen attenuation (ALA) in percent, image noise inside/outside the stent and CTDIvol were measured.ResultsMean ALN was 46% for HPS, 44% for SEQ and 47% for SPIR without significant difference. Mean VIA was similar with 31% for HPS, 30% for SEQ and 33% for SPIR. Mean ALA was, at 5% for HPS, significantly lower compared with −11% for SPIR (pu2009=u20090.024), but not different from SEQ with −1%. Mean image noise was significantly higher for HPS compared with SEQ and SPIR inside and outside the stent (pu2009<u20090.001). CTDIvol was lower for HPS (5.17xa0mGy), compared with SEQ (9.02xa0mGy) and SPIR (55.97xa0mGy), respectively.ConclusionThe HPS mode of 128-slice dual-source CT yields fewer artefacts inside the stent lumen compared with SPIR and SEQ, but image noise is higher. ALN is still too high for routine stent evaluation in clinical practice. Radiation dose of the HPS mode is markedly (less than about tenfold) reduced.

The skull unfolded: a cranial CT visualization algorithm for fast and easy detection of skull fractures.

PURPOSEnTo retrospectively assess the rate of detection of skull fractures at cranial computed tomography (CT) achieved with the use of curved maximum intensity projections (MIPs) compared with that achieved by reading transverse sections only.nnnMATERIALS AND METHODSnThe institutional review board approved this research and waived informed consent. A curved thin (3-mm) MIP of the skull cap and a curved thick (50-mm) MIP of the skull base were obtained from the cranial CT data in 200 consecutive patients with head trauma. Four radiologists (two residents without experience in cranial CT and two consultants) independently evaluated all cases. Each radiologist reported findings in 100 patients by using transverse sections only and findings in the other 100 patients by using the unfolded view. The radiologists were blinded to patient names, and patient and group orders were randomized. The results were compared with a standard of reference established by two experts from all prior reading results, all reconstructions, and high-spatial-resolution multiplanar reformats. Logistic regression with repeated measurements was used for statistical analysis.nnnRESULTSnThe experts found 63 fractures in 30 patients. When transverse sections only were used, the mean patient-based fracture detection rate was 43% (13 of 30) for inexperienced and 70% (21 of 30) for experienced readers; with curved MIPs, the rates were 80% (24 of 30) and 87% (26 of 30), respectively. Overall sensitivity was higher with curved MIPs (P < .001); specificity was higher with transverse sections (P < .001).nnnCONCLUSIONnCurved MIPs enable a significantly higher fracture detection rate than transverse sections. They also considerably close the experience gap in fracture detection rate between residents and experts.

Dose modulated retrospective ECG-gated versus non-gated 64-row CT angiography of the aorta at the same radiation dose: Comparison of motion artifacts, diagnostic confidence and signal-to-noise-ratios

PURPOSEnTo compare ECG-gated and non-gated CT angiography of the aorta at the same radiation dose, with regard to motion artifacts (MA), diagnostic confidence (DC) and signal-to-noise-ratios (SNRs).nnnMATERIALS AND METHODSnSixty consecutive patients prospectively randomized into two groups underwent 64-row CT angiography, with or without dose-modulated ECG-gating, of the entire aorta, due to several pathologies of the ascending aorta. MA and DC were both assessed using a four-point scale. SNRs were calculated by dividing the mean enhancement by the standard deviation. The dose-length-product (DLP) of each examination was recorded and the effective dose was estimated.nnnRESULTSnDose-modulated ECG-gating showed statistically significant advantages over non-gated CT angiography, with regard to MA (p<0.001) and DC (p<0.001), at the aortic valve, at the origin of the coronary arteries, and at the dissection membrane, with a significant correlation (p<0.001) between MA and DC. At the aortic wall, however, ECG-gated CT angiography showed statistically significant fewer MA (p<0.001), but not a statistically significant higher DC (p=0.137) compared to non-gated CT angiography. At the supra-aortic vessels and the descending aorta, the ECG-triggering showed no statistically significant differences with regard to MA (p=0.861 and 0.526, respectively) and DC (p=1.88 and 0.728, respectively). The effective dose of ECG-gated CT angiography (23.24mSv; range, 18.43-25.94mSv) did not differ significantly (p=0.051) from that of non-gated CT angiography (24.28mSv; range, 19.37-29.27mSv).nnnCONCLUSIONnECG-gated CT angiography of the entire aorta reduces MA and results in a higher DC with the same SNR, compared to non-gated CT angiography at the same radiation dose.

Advanced-stage hepatocellular carcinoma with portal vein thrombosis: conventional versus drug-eluting beads transcatheter arterial chemoembolization

AbstractObjectivesOur study sought to compare the overall survival in patients with hepatocellular carcinoma (HCC) and portal venous thrombosis (PVT), treated with either conventional trans-arterial chemoembolization (cTACE) or drug-eluting beads (DEB) TACE.MethodsThis retrospective analysis included a total of 133 patients, treated without cross-over and compared head-to-head by means or propensity score weighting. Mortality was compared using survival analysis upon propensity score weighting. Adverse events and liver toxicity grade ≥3 were recorded and reported for each TACE. In order to compare with historical sorafenib studies, a sub-group analysis was performed and included patients who fulfilled the SHARP inclusion criteria.ResultsThe median overall survival (MOS) of the entire cohort was 4.53xa0months (95xa0% CI, 3.63–6.03). MOS was similar across treatment arms, no significant difference between cTACE (Nu2009=u200995) and DEB-TACE (Nu2009=u200938) was observed (MOS of 5.0 vs. 3.33xa0months, respectively; pu2009=u20090.157). The most common adverse events after cTACE and DEB- TACE, respectively, were as follows: post-embolization syndrome [Nu2009=u200957 (30.0xa0%) and Nu2009=u200938 (61.3xa0%)], diarrhea [Nu2009=u20093 (1.6xa0%) and Nu2009=u20093 (4.8xa0%)], and encephalopathy [Nu2009=u200911 (5.8xa0%) and Nu2009=u20092 (3.2xa0%)].ConclusionOur retrospective study could not reveal a difference in toxicity and efficiency between cTACE and DEB-TACE for treatment of advanced stage HCC with PVT.Key Points• Conventional TACE (cTACE) and drug-eluting-beads TACE (DEB-TACE) demonstrated equal safety profiles.n • Survival rates after TACE are similar to patients treated with sorafenib.n • Child-Pugh class and tumor burden are reliable predictors of survival.

Lossy 3D JPEG2000 Compression of Abdominal CT Images in Patients with Acute Abdominal Complaints: Effect of Compression Ratio on Diagnostic Confidence and Accuracy

PURPOSEnTo retrospectively assess the effect of lossy three-dimensional (3D) Joint Photographic Experts Group 2000 (JPEG2000) compression on diagnostic confidence and diagnostic accuracy at emergency abdominal computed tomography (CT).nnnMATERIALS AND METHODSnIn this institutional review board-approved study, transverse images from 104 consecutive multidetector CT examinations (section thickness, 3 mm; reconstruction interval, 2 mm) in patients with acute abdominal complaints were subjected to lossy 3D JPEG2000 compression by using three compression ratios (10:1, 12.5:1, and 15:1, with reference to 384 kB [12 bits] as original image size). Three radiologists independently read the original and compressed CT studies. Patient order and compression ratios were randomized, and readers were blinded to that information. For each organ, the presence of compression artifacts, the diagnosis, the confidence in the diagnosis according to a five-point scale, and the confidence about negative findings were noted. All diagnoses were compared with a standard of reference constructed by an abdominal CT expert by using the original images, surgical reports, and patient follow-up data. Logistic regressions, the Friedman test, and analysis of variance were used for statistical analysis.nnnRESULTSnPrimary diagnoses were correct in 91.3% (463 of 507), 90.5% (459 of 507), 89.0% (451 of 507) and 90.1% (457 of 507) of the total number of primary diagnoses at 1:1, 1:10, 1:12.5 and 15:1, respectively. These values did not vary significantly (P = .456) with compression ratios. The radiologists mean confidence about the primary diagnoses was also almost identical at different compression ratios (4.83, 4.87, 4.77, and 4.84 at 1:1, 1:10, 1:12.5 and 15:1, respectively). However, the radiologists mean confidence about negative findings in the liver was reduced in 50.3% (157 of 312) of studies at 15:1.nnnCONCLUSIONnDiagnostic accuracy was not impaired at compression ratios up to 15:1. However, because of the significant reduction of the confidence about negative findings at 15:1, compression ratios no higher than 12.5:1 are recommended.

Three-dimensional fracture visualisation of multidetector CT of the skull base in trauma patients: comparison of three reconstruction algorithms

The purpose of this study was to retrospectively assess the detection rate of skull-base fractures for three different three-dimensional (3D) reconstruction methods of cranial CT examinations in trauma patients. A total of 130 cranial CT examinations of patients with previous head trauma were subjected to 3D reconstruction of the skull base, using solid (SVR) and transparent (TVR) volume-rendering technique and maximum intensity projection (MIP). Three radiologists independently evaluated all reconstructions as well as standard high-resolution multiplanar reformations (HR-MPRs). Mean fracture detection rates for all readers reading rotating reconstructions were 39, 36, 61 and 64% for SVR, TVR, MIP and HR-MPR respectively. Although not significantly different from HR-MPR with respect to sensitivity (Pu2009=u20090.9), MIP visualised 18% of fractures that were not reported in HR-MPR. Because of the relatively low detection rate using HR-MPRs alone, we recommend reading MIP reconstructions in addition to the obligatory HR-MPRs to improve fracture detection.

Systematic review of catheter-based intra-arterial therapies in hepatocellular carcinoma: state of the art and future directions

Intra-arterial therapies (IATs) play a pivotal role in the management of patients with primary and secondary liver malignancies. The unique advantages of these treatments are their ability to selectively deliver a high dose of anticancer treatment while preserving healthy liver tissue. The proven efficacy of these catheter-based locoregional therapies in a highly systemic chemoresistant cancer such as hepatocellular carcinoma (HCC), along with the minimally invasive nature of these treatments, quickly yielded wide acceptance in the medical community and revolutionized the field of Interventional Oncology. In this article, we describe the clinical rationale and background of catheter-based IATs. We provide an overview of clinical achievements of these treatments alone and in combination with sorafenib in patients with HCC.

Delayed-Phase Cone-Beam CT Improves Detectability of Intrahepatic Cholangiocarcinoma During Conventional Transarterial Chemoembolization

PurposeTo evaluate the detectability of intrahepatic cholangiocarcinoma (ICC) on dual-phase cone-beam CT (DPCBCT) during conventional transarterial chemoembolization (cTACE) compared to that of digital subtraction angiography (DSA) with respect to pre-procedure contrast-enhanced magnetic resonance imaging (CE-MRI) of the liver.MethodsThis retrospective study included 17 consecutive patients (10 male, mean age 64) with ICC who underwent pre-procedure CE-MRI of the liver, and DSA and DPCBCT (early-arterial phase (EAP) and delayed-arterial phase (DAP)) just before cTACE. The visibility of each ICC lesion was graded by two radiologists on a three-rank scale (complete, partial, and none) on DPCBCT and DSA images, and then compared to pre-procedure CE-MRI.ResultsOf 61 ICC lesions, only 45.9xa0% were depicted by DSA, whereas EAP- and DAP-CBCT yielded a significantly higher detectability rate of 73.8xa0% and 93.4xa0%, respectively (pxa0<xa00.01). Out of the 33 lesions missed on DSA, 18 (54.5xa0%) and 30 (90.9xa0%) were revealed on EAP- and DAP-CBCT images, respectively. DSA depicted only one lesion that was missed by DPCBCT due to streak artifacts caused by a prosthetic mitral valve. DAP-CBCT identified significantly more lesions than EAP-CBCT (pxa0<xa00.01). Conversely, EAP-CBCT did not detect lesions missed by DAP-CBCT. For complete lesion visibility, DAP-CBCT yielded significantly higher detectability (78.7xa0%) compared to EAP (31.1xa0%) and DSA (21.3xa0%) (pxa0<xa00.01).ConclusionDPCBCT, and especially the DAP-CBCT, significantly improved the detectability of ICC lesions during cTACE compared to DSA. We recommend the routine use of DAP-CBCT in patients with ICC for per-procedure detectability and treatment planning in the setting of TACE.