High Prevalence and Clinical Relevance of Intrapulmonary Vascular Dilatations in Patients Undergoing TIPS Implantation.

BACKGROUND & AIMS: Considerate patient selection is vital to ensure the best possible outcomes after transjugular intrahepatic portosystemic shunt (TIPS) insertion. However, data regarding the impact of intrapulmonary vascular dilatations (IPVDs) or hepatopulmonary syndrome (HPS) on the clinical course after TIPS implantation is lacking. Hence, this study aimed to investigate the relevance of IPVD and HPS in patients undergoing TIPS implantation. METHODS: Contrast enhanced echocardiography and blood gas analysis were utilized to determine presence of IPVD and HPS. Multivariable competing risk analyses were performed to evaluate cardiac decompensation (CD), hepatic decompensation (HD), and liver transplant (LTx)-free survival within 1 year of follow-up. RESULTS: Overall, 265 patients were included, of whom 136 had IPVD and 71 fulfilled the HPS criteria. Patients with IPVD had lower Freiburg index of post-TIPS survival (FIPS) scores, lower creatinine, and more often received TIPS because of variceal bleeding. Presence of IPVD was associated with a significantly higher incidence of CD (hazard ratio [HR], 1.756; 95% confidence interval [CI], 1.011-3.048; P = .046) and HD (HR, 1.841; 95% CI, 1.255-2.701; P = .002). However, LTx-free survival was comparable between patients with and without IPVD (HR, 1.081; 95% CI, 0.630-1.855; P = .780). Patients with HPS displayed a trend towards more CD (HR, 1.708; 95% CI, 0.935-3.122; P = .082) and HD (HR, 1.458; 95% CI, 0.934-2.275; P = .097) that failed to reach statistical significance. LTx-free survival did not differ in those with HPS compared with patients without HPS, respectively (HR, 1.052; 95% CI, 0.577-1.921; P = .870). CONCLUSION: Screening for IPVD before TIPS implantation could help to further identify patients at higher risk of CD and HD.

Fully Integrated Laser Guidance for CT-Based Punctures: A Study in Phantoms and Patients.

PURPOSE: To test the hypothesis of equal or even superior applicability and accuracy of a fully integrated, laser-based computed tomography (CT) navigation system compared with conventional CT guidance for percutaneous interventions. MATERIALS AND METHODS: CT-guided punctures were first performed in phantoms. Four radiologists with different experience levels (2 residents (L.B., C.D.) and 2 board-certified radiologists (B.M., K.R.) performed 48 punctures using both conventional image-guided and laser-guided approaches. Subsequently, 12 punctures were performed in patients during a clinical pilot trial. Phantom targets required an in-plane or a single-/double-angulated, out-of-plane approach. Planning and intervention time, control scan number, radiation exposure, and accuracy of needle placement (measured by deviation of the needle tip to the designated target) were assessed for each guidance technique and compared (Mann-Whitney U test and t test). Patient interventions were additionally analyzed for applicability in a clinical setting. RESULTS: The application of laser guidance software in the phantom study and in 12 human patients in a clinical setting was both technically and clinically feasible in all cases. The mean planning time (P = .009), intervention time (P = .005), control scan number (P < .001), and radiation exposure (P = .013) significantly decreased for laser-navigated punctures compared with those for conventional CT guidance and especially in punctures with out-of-plane-trajectories. The accuracy significantly increased for laser-guided interventions compared with that for conventional CT (P < .001). CONCLUSIONS: Interventional radiologists with differing levels of experience performed faster and more accurate punctures for out-of-plane trajectories in the phantom models, using a new, fully integrated, laser-guided CT software and demonstrated excellent clinical and technical success in initial clinical experiments.

RAS-challenge as a first-look test for detection of primary aldosteronism in patients with treatment-resistant hypertension.

PURPOSE: Primary aldosteronism (PA), characterised by low-renin hypertension, confers a high cardiovascular risk and is the most common cause of secondary hypertension, with an increased prevalence in patients with treatment-resistant hypertension. However, it is estimated that only a small percentage of affected patients are identified in routine clinical practice. Inhibitors of the renin-angiotensin system cause an increase in renin levels in patients with intact aldosterone regulation, and inadequate low renin with concurrent RAS inhibition (RASi) may therefore indicate PA, which could serve as a first look screening test for selection for formal work-up. METHODS: We analysed patients between 2016-2018 with treatment-resistant hypertension who had inadequate low renin in the presence of RASi (i. e. at risk for PA) and who were offered systematic work-up with adrenal vein sampling (AVS). RESULTS: A total of 26 pts were included in the study (age 54.8 ± 11, male 65%). Mean office blood pressure (BP) was 154/95 mmHg on 4.5 antihypertensive drug classes. AVS had a high technical success rate (96%) and demonstrated unilateral disease in the majority of patients (57%), most of which (77%) were undetected by cross-sectional imaging. CONCLUSION: In patients with resistant hypertension, low renin in the presence of RASi is a strong indicator for autonomous aldosterone secretion. It may serve as an on-medication screening test for PA to select for formal PA work up.

What is the context? Primary aldosteronism (PA) is associated with an uncontrolled secretion of the hormone aldosterone and often causes severe forms of high blood pressure. PA is considered the most common cause of high blood pressure which is caused by another medical condition. Medical societies have issued precise recommendations for the screening of this disease, which includes the determination of aldosterone and its main regulator renin. However, it is estimated that only a small percentage of affected patients are identified in routine clinical practice.What is the problem? In clinical studies, the determination of renin, aldosterone and its ratio (ARR) proved to be a valid screening tool. Nevertheless, in everyday life assessing and interpreting these results can be challenging for the clinician. The ARR is influenced by all first-line antihypertensives and in case of doubt, an extensive change in medication is recommended. Especially patients with resistant hypertension may require intensive medical care when medication is changed.What is important? In this study, we analysed patients at risk for PA who had inadequate low renin in presence of RASi (ACE inhibitors, Angiotensin receptor blockers). This study suggests that in patients with severe hypertension, the determination of renin in presence of RASi can provide further information on the presence of autonomic aldosterone secretion at a glance. However, this approach cannot and should not replace the algorithm proposed by current guidelines. In contrast, this approach should be an easy-to-implement concept that should prime the initiation of further appropriate diagnostics.

Intraarterial embolizations in life-threatening spontaneous retroperitoneal and rectus sheath hemorrhage (SRRSH): a three-center experience.

PURPOSE: To retrospectively evaluate the technical and clinical success of interventional treatments employed in three University medical centers and to develop work-flow recommendations for intra-arterial embolizations in patients with life-threatening spontaneous retroperitoneal and rectus sheath hemorrhage (SRRSH). MATERIALS AND METHODS: Retrospective evaluation of all patients with contrast-enhanced CT and digital subtraction angiography (DSA) for SRRSH from 01/2018 to 12/2022, amounted to 91 interventions in 83 patients (45f, 38m) with a mean age of 68.1 ± 13.2 years. Analysis of the amount of bleeding and embolized vessels, choice of embolization material, technical success, and 30-day mortality was performed. RESULTS: Pre-interventional contrast-enhanced CT demonstrated active contrast extravasation in 79 cases (87%). DSA identified a mean of 1.4 ± 0.88 active bleeds in all but two interventions (98%), consisting of 60 cases with a singular and 39 cases of >1 bleeding artery, which were consecutively embolized. The majority of patients underwent embolization with either n-butyl-2-cyanoacrylate (NBCA; n=38), coils (n=21), or a combination of embolic agents (n=23). While the technical success rate was documented at 97.8%, 25 patients (30%) died within 30 days after the initial procedure, with mortality rates ranging from 25 to 86% between the centers, each following different diagnostic algorithms. CONCLUSION: Embolotherapy is a safe therapy option with high technical success rates in patients with life-threatening SRRSH. To maximize clinical success and survival rates, we propose a standardized approach to angiography as well as a low threshold for re-angiography.

The impact of the field of view (FOV) on image quality in MDCT angiography of the lower extremities.

OBJECTIVES: To evaluate the impact of the reconstructed field-of-view (FOV) on image quality in computed-tomography angiography (CTA) of the lower extremities. METHODS: A total of 100 CTA examinations of the lower extremities were acquired on a 2 × 192-slice multidetector CT (MDCT) scanner. Three different datasets were reconstructed covering both legs (standard FOV size) as well as each leg separately (reduced FOV size). The subjective image quality was evaluated for the different vessel segments (femoral, popliteal, crural, pedal) by three readers using a semi-quantitative Likert scale. Additionally, objective image quality was assessed using an automated image quality metric on a per-slice basis. RESULTS: The subjective assessment of the image quality showed an almost perfect interrater agreement. The image quality of the small FOV datasets was rated significantly higher as compared to the large datasets for all patients and vessel segments (p < 0.05) with a tendency towards a higher effect in smaller vessels. The difference of the mean scores between the group with the large FOV and small FOV was 0.68 for the femoral level, 0.83 for the popliteal level, 1.12 for the crural level, and 1.08 for the pedal level. The objective image quality metric also demonstrated a significant improvement of image quality in the small FOV datasets. CONCLUSIONS: Side-separated reconstruction of each leg in CTA of the lower extremities using a small reconstruction FOV significantly improves image quality as compared to a standard reconstruction with a large FOV covering both legs. KEY POINTS: • In CT angiography of the lower legs, the side-separated reconstruction of each leg using a small field-of-views improves image quality as compared to a standard reconstruction covering both legs. • The side-separated reconstruction can be readily implemented at every commercially available CT scanner. • There is no need for additional hardware or software and no additional burden to the patient.

Predictors of response to intra-arterial vasodilatory therapy of non-occlusive mesenteric ischemia in patients with severe shock: results from a prospective observational study.

BACKGROUND: Non-occlusive mesenteric ischemia (NOMI) is a life-threatening condition occurring in patients with shock and is characterized by vasoconstriction of the mesenteric arteries leading to intestinal ischemia and multi-organ failure. Although minimal invasive local intra-arterial infusion of vasodilators into the mesenteric circulation has been suggested as a therapeutic option in NOMI, current knowledge is based on retrospective case series and it remains unclear which patients might benefit. Here, we prospectively analyzed predictors of response to intra-arterial therapy in patients with NOMI. METHODS: This is a prospective single-center observational study to analyze improvement of ischemia (indicated by reduction of blood lactate > 2 mmol/l from baseline after 24 h, primary endpoint) and 28-day mortality (key secondary endpoint) in patients with NOMI undergoing intra-arterial vasodilatory therapy. Predictors of response to therapy concerning primary and key secondary endpoint were identified using a) clinical parameters as well as b) data from 2D-perfusion angiography and c) experimental biomarkers of intestinal injury. RESULTS: A total of 42 patients were included into this study. At inclusion patients had severe shock, indicated by high doses of norepinephrine (NE) (median (interquartile range (IQR)) 0.37 (0.21-0.60) µg/kg/min), elevated lactate concentrations (9.2 (5.2-13) mmol/l) and multi-organ failure. Patients showed a continuous reduction of lactate following intra-arterial prostaglandin infusion (baseline: (9.2 (5.2-13) mmol/l vs. 24 h: 4.4 (2.5-9.1) mmol/l, p < 0.001) with 22 patients (52.4%) reaching a lactate reduction > 2 mmol/l at 24 h following intervention. Initial higher lactate concentrations and lower NE doses at baseline were independent predictors of an improvement of ischemia. 28-day mortality was 59% in patients with a reduction of lactate > 2 mmol/l 24 h after inclusion, while it was 85% in all other patients (hazard ratio 0.409; 95% CI, 0.14-0.631, p = 0.005). CONCLUSIONS: A reduction of lactate concentrations was observed following implementation of intra-arterial therapy, and lactate reduction was associated with better survival. Our findings concerning outcome predictors in NOMI patients undergoing intra-arterial prostaglandin therapy might help designing a randomized controlled trial to further investigate this therapeutic approach. Trial registration Retrospectively registered on January 22, 2020, at clinicaltrials.gov (REPERFUSE, NCT04235634), https://clinicaltrials.gov/ct2/show/NCT04235634?cond=NOMI&draw=2&rank=1 .

CO2-based C-arm computed tomography (CACT) of the pelvic arteries: feasibility and diagnostic performance in comparison to CO2-angiography in patients with peripheral arterial disease.

BACKGROUND: Patients with substantially impaired kidney function and peripheral arterial disease (PAD) underwent comparative CO2-based depiction of the pelvic arteries (PAs). PURPOSE: To evaluate the feasibility and diagnostic performance of CO2-based C-arm computed tomography (CACT) and compare its depiction of PAs with CO2-digital subtraction angiography (DSA). MATERIAL AND METHODS: Fifteen patients (10 men, mean age 70 ± 11 years) with PAD received CO2-DSA and CO2-CACT of the PAs, depicted from the aorta to femoral arteries. These were divided into nine segments (135 in total) and graded by two independent readers for image quality (IQ; 1 = sufficient, 2 = minimal impairments, 3 = insufficient, 4 = outside field of view) and subsequent stenosis grading (SG; grade 1: normal to grade 4: occlusion), under exclusion of all segments with insufficient IQ. Inter-observer and inter-modality agreement calculation and subsequent consensus reading were performed and correlated to a standard of reference (StOR), representing a modality consensus. RESULTS: Of 135 segments, 117 showed sufficient IQ, excluding 18 segments (10 CACT, 8 DSA). Inter-observer agreement for IQ and consecutive SG demonstrated good to excellent agreement: IQDSA: κ = 0.83, IQCACT: κ = 0.76; StenosisDSA: κ = 0.71, StenosisCACT: κ = 0.84. Inter-modality agreement for SG lay at κ = 0.76 and κ = 0.65, respectively. More stenoses could be detected by CACT, and analysis of pooled consensus values of SG in CACTcons versus StOR showed an excellent agreement (κ = 0.96) that proved considerably higher than the moderate agreement between consensus values in DSAcons versus StOR (κ = 0.43). CONCLUSION: CO2-CACT proved feasible, and has the potential to optimize angiographic work-up of PAD in patients with contraindications for other contrast media.

A Retrospective Analysis of Nonocclusive Mesenteric Ischemia in Medical and Surgical ICU Patients: Clinical Data on Demography, Clinical Signs, and Survival.

BACKGROUND: To analyze demography, clinical signs, and survival of intensive care patients diagnosed with nonocclusive mesenteric ischemia (NOMI) and to evaluate the effect of a local intra-arterial prostaglandin therapy. METHODS: Retrospective observational study screening 455 intensive care patients with acute arterial mesenteric perfusion disorder in a tertiary care hospital within the past 8 years. Lastly, 32 patients with NOMI were enrolled, of which 11 received local intra-arterial prostaglandin therapy. The diagnosis of NOMI was based on the clinical presentation and established biphasic computed tomography criteria. Clinical and biochemical data were obtained 24 hours before, at the time, and 24 hours after diagnosis. RESULTS: Patients were 60.5 (49.3-73) years old and had multiple comorbidities. Most of them were diagnosed with septic shock requiring high doses of norepinephrine (NE: 0.382 [0.249-0.627] µg/kg/min). The Sequential Organ Failure Assessment (SOFA) score was 18 (16-20). A decrease in oxygenation (Pao 2/Fio 2), pH, and bicarbonate and an increase in international normalized ratio, lactate, bilirubin, leucocyte count, and NE dose were early indicators of NOMI. Median SOFA score significantly increased in the last 24 hours before diagnosis of NOMI (16 vs 18, P < .0001). Overall, 28-day mortality was 75% (81% nonintervention vs 64% intervention cohort; P = .579). Median SOFA scores 24 hours after intervention increased by +5% in the nonintervention group and decreased by 5.5% in the intervention group (P = .0059). CONCLUSIONS: Our data suggest that NOMI is a detrimental disease associated with progressive organ failure and a high mortality. Local intra-arterial prostaglandin application might hold promise as a rescue treatment strategy. These data encourage future randomized controlled trials are desirable.

Nonocclusive Mesenteric Ischemia and Interventional Local Vasodilatory Therapy: A Meta-Analysis and Systematic Review of the Literature.

BACKGROUND: Intensive care patients with nonocclusive mesenteric ischemia (NOMI) show mortality rates of 70% to 90%. Besides emergency surgery, different interventional local vasodilatory treatment (LVT) attempts have been described. We performed a systematic review and a meta-analysis to evaluate feasibility, efficacy, and tolerability of LVT in patients with life-threatening NOMI. METHODS: Searches of PubMed, EMBASE, Web of Science, and Cochrane Library databases were performed until February 2019. Measured outcomes included immediate technical success rates (as indicated by mesenteric vasodilation on angiography or clinical improvement) and adverse events (AEs). Therapeutic efficacy was measured by the assessment of overall mortality. RESULTS: Twelve studies (335 patients, 245 received LVT) from 1977 to 2018 were included. All studies were retrospective (4 comparative and 8 noncomparative). Different intra-arterial vasodilators (4× papaverine, 6× prostaglandin E1, 1× tolazoline/heparin, 1× tolazoline + iloprost) were reported. Initial technical success rate was 75.9% (95% confidence interval [CI], 55.1%-89%, P = .017) with an AE rate of 2.9% (95% CI: 1.3%-6.6%; P = .983). Overall mortality in LVT patients was 40.3% (95% CI: 28.7%-53%, P = .134). In 4 studies, outcomes were compared between patients receiving LVT to those who received standard of care (odds ratio for death in LVT patients was 0.261 [95% CI: 0.095-0.712, P = .009]). CONCLUSIONS: Local vasodilatory treatment appears to be safe in patients with NOMI and might have the potential to at least partially reverse mesenteric vasoconstriction features in control angiographies. However, with no randomized and prospective studies available yet, the overall quality of published studies has to be considered as low; therefore, it is not possible to draw generalizable conclusions from the present data concerning clinical end points. Its application might hold promise as a rescue treatment strategy and deserves further evaluation in randomized controlled trials.

C-Arm computed tomography (CACT)-guided balloon pulmonary angioplasty (BPA): Evaluation of patient safety and peri- and post-procedural complications.

AIM: To assess the frequency and severity of complications of balloon pulmonary angioplasty (BPA) using C-arm computed tomography (CACT) guidance. MATERIAL AND METHODS: 266 consecutive interventions in 67 patients (42 females, mean age 66 ± 13 years) were included. Selective CACT was acquired prior to the intervention for three-dimensional (3D) guidance and to select appropriate balloon size based on the measured vessel diameter. Complications during and after the procedure, the need for further interventions and the impact on patient safety and outcome were assessed and categorised according to the SIR Classification System to Complications by Outcome (Grade A-F). RESULTS: Overall, 237 interventions were conducted without any complications (89.1%). Minor complications not requiring additional treatment occurred during or after 25 procedures (9.4%), including recurring dry cough in four patients during a total of 11 interventions (4.1%) (Grade A), three focal dissections of the targeted pulmonary artery (1.1%), four cases of pulmonary haemorrhage (1.5%), one case of reperfusion oedema (0.4%) and six cases of post-interventional short-term hemoptysis (2.3%) (Grade B). Four cases of major complications requiring additional treatment were observed (1.5%): one case of pulmonary haemorrhage (0.4%) and two cases of post-interventional haemoptysis (0.8%), all resolved after medical therapy without requiring further intervention, and one case of atrial tachycardia induced during catheterisation, subsequently requiring pharmacological cardioversion (0.4%) (Grade C). No fatal or life-threatening peri- or post-interventional complications or mortality were observed (Grade D-F). CONCLUSION: BPA performed under CACT guidance appears to be a safe procedure with a low risk of severe complications. KEY POINTS: • CACT guidance of BPA is safe and successful. • CACT-guided BPA procedures have a low complication profile. • CACT guidance is a valuable tool to navigate BPA.

Cardio-pulmonary MRI for detection of treatment response after a single BPA treatment session in CTEPH patients.

OBJECTIVES: Chronic thromboembolic pulmonary hypertension (CTEPH) can be treated with balloon pulmonary angioplasty (BPA) in inoperable patients. Sensitive non-invasive imaging methods are missing to detect treatment response after a single BPA treatment session. Therefore, the aim of this study was to measure treatment response after a single BPA session using cardio-pulmonary MRI. MATERIALS AND METHODS: Overall, 29 patients with CTEPH were examined with cardio-pulmonary MRI before and 62 days after their initial BPA session. Pulmonary blood flow (PBF), first-pass bolus kinetic parameters, and biventricular mass and function were determined. Multiple linear regression analysis was implemented to estimate the relationship of PBF change in the treated lobe with treatment change of full width at half maximum (FWHM), cardiac output (CO), ventricular mass index (VMI), pulmonary transit time (PTT) and PBF change in the non-treated lobes. Paired Wilcoxon rank sum test and Spearman rho correlation were used. RESULTS: After BPA regional PBF increased in the treated lobe (p < 0.0001) as well as in non-treated lobes (p = 0.015). PBF treatment changes in the treated lobe were significantly larger compared with the non-treated lobes (p = 0.0049). Change in NT proBNP, MRI-derived mean pulmonary artery pressure (mPAP), PTT, FWHM, right ventricular (RV) ejection fraction, RV stroke volume, CO, VMI and PBF in the non-treated lobes correlated with PBF change in the treated lobe (p < 0.05). PBF changes in the treated lobe were independently predicted by PTT as well as PBF change in the non-treated lobes. CONCLUSION: Cardio-pulmonary MRI detects and quantifies treatment response after a single BPA treatment session. KEY POINTS: • Two months after BPA regional parenchymal pulmonary perfusion (PBF) increased in the total lung parenchyma (p = 0.005), the treated lobes (p < 0.0001) and non-treated lobes (p = 0.015). • The PBF treatment changes in the treated lobe were significantly larger than in the non-treated lobes (p = 0.0049). • Change in NT proBNP, MRI-derived mean pulmonary artery pressure, pulmonary transit time, full width at half maximum, right ventricular (RV) ejection fraction, RV stroke volume, cardiac output, ventricular mass index and PBF in the non-treated lobes correlated with PBF change in the treated lobe (p < 0.05).

Balloon pulmonary angioplasty for inoperable patients with chronic thromboembolic pulmonary hypertension: the initial German experience.

Balloon pulmonary angioplasty (BPA) is an emerging treatment for patients with inoperable chronic thromboembolic pulmonary hypertension (CTEPH).We report on a prospective series of 56 consecutive patients who underwent 266 BPA interventions (median, five per patient) at two German institutions. All patients underwent a comprehensive diagnostic work-up including right heart catheterisation at baseline and 24 weeks after their last intervention.BPA resulted in improvements in WHO functional class, 6 min walk distance (mean change, +33 m), right ventricular function and haemodynamics, including a decline in mean pulmonary artery pressure by 18% and in pulmonary vascular resistance by 26%. Procedure-related adverse events occurred in 9.4% of the interventions. The most common complications were related to pulmonary vascular injury and consecutive pulmonary bleeding. Most of these events were asymptomatic and self-limiting, but one patient died from pulmonary bleeding, resulting in a mortality rate of 1.8%.BPA resulted in haemodynamic and clinical improvements but was also associated with a considerable number of complications, including one fatal pulmonary bleeding. As the effects of BPA on survival are unknown, randomised controlled outcome trials comparing BPA with approved medical therapies in patients with inoperable CTEPH are required to allow for appropriate risk-benefit assessments.

Chronic thromboembolic pulmonary hypertension: Evaluation of 2D-perfusion angiography in patients who undergo balloon pulmonary angioplasty.

OBJECTIVE: To evaluate the feasibility of 2D-perfusion angiography (2D-PA) in order to quantify perfusion changes of the lung parenchyma pre- and post-balloon pulmonary angioplasty (BPA). METHODS: Thirty consecutive interventions in 16 patients with 99 treated pulmonary artery segments were included. To quantify changes in pulmonary blood flow using 2D-PA, the acquired digital subtraction angiographies (DSA) pre- and post-BPA were post-processed. A reference ROI in the treated pulmonary artery and a distal target ROI in the lung parenchyma were placed in corresponding areas on DSA pre- and post-BPA. Time to peak (TTP), peak density (PD) and area under the curve (AUC) were assessed. The ratios reference ROI to target ROI (TTPparenchyma/TTPinflow; PDparenchyma/PDinflow; AUCparenchyma/AUCinflow) were calculated. Relative differences of the 2D-PA parameters were correlated to changes in the pulmonary-flow-grade-score. RESULTS: The pulmonary-flow-grade-score improved after BPA (p<0.0001). Likewise, the ratio TTPparenchyma/TTPinflow shortened by 10% (p=0.0002), the PDparenchyma/PDinflow increased by 46% (p<0.0001) and the AUCparenchyma/AUCinflow increased by 36% (p<0.0001). A significant correlation between changes in the pulmonary-flow-grade-score and changes in PDparenchyma/PDinflow (ρ=0.48, p<0.0001) and AUCparenchyma/AUCinflow (ρ=0.31, p=0.0018) was observed. CONCLUSION: Quantification of pulmonary perfusion pre- and post-BPA using 2D-PA is feasible and has the potential to improve monitoring of BPA. KEY POINTS: • Quantification of BPA results by use of 2D-PA is feasible. • 2D-PA allows objective assessment of changes in lung parenchymal perfusion. • 2D-PA has the potential to optimize BPA.

Balloon pulmonary angioplasty: applicability of C-Arm CT for procedure guidance.

PURPOSE: To investigate the feasibility of and compare two C-Arm CT (CACT) guidance methods during balloon pulmonary angioplasty (BPA). MATERIAL AND METHODS: Forty-two BPAs [27 CTEPH patients (nine males, 70 ± 14y)] targeting 143 pulmonary arteries were included. Twenty-two BPAs were guided by contrast-enhanced CACT acquired immediately before BPA (G3D). In another 20 BPAs (G2D), two orthogonal fluoroscopy images of the chest where acquired to compute a registration of a previously acquired CACT. Volume rendering-based graphic representations (VRT guidance) were generated indicating the origin and course of the vessels. Based on VRT guidance, the intervention was planned. Procedure durations and radiation exposure data were compared between the two groups (Wilcoxon test). RESULTS: The overall intervention time was approximately 2 h in both groups (p = 0.31). BPA was successfully performed in G3D 91 % and G2D 94 %. No significant difference was found concerning the mean dose area product (DAP) related to fluoroscopy (p = 0.38), while DAP related to DSA was slightly higher in G3D (p = 0.048). Overall, DAP was significantly higher in G3D (p = 0.002). CONCLUSIONS: The use of CACT for procedure guidance in patients undergoing BPA is feasible and accurate. Image fusion of a pre-acquired CACT can be used to decrease radiation exposure due to multiple BPA sessions. KEY POINTS: • BPA guidance by CACT overlay is feasible and safe. • 2D3D image fusion for BPA guidance is accurate. • Image fusion can reduce patient radiation dose due to repeated BPA sessions.

Parametric response mapping of contrast-enhanced biphasic CT for evaluating tumour viability of hepatocellular carcinoma after TACE.

OBJECTIVES: To determine the feasibility and role of parametric response mapping (PRM) for quantitative assessment of regional contrast-enhancement patterns in hepatocellular carcinoma (HCC). METHODS: Biphasic CT of 19 patients receiving repetitive conventional transarterial chemoembolisation (cTACE) for intermediate stage HCC were retrospectively analysed at baseline and follow-up at 3, 6, and 9 months. Voxel-based registration of arterial and porto-venous phases, with segmentation of the largest target lesion was performed. Frequency distribution plots of density-pairs of segmented voxels were generated. To differentiate necrotic, hypervascular and non-hypervascular tumour, and lipiodol/calcification, thresholds of 30, 100, and 300 HU were applied. Changes in density frequency plots over time were analysed and compared to response and assessment criteria (WHO, RECIST, EASL, mRECIST) and survival. RESULTS: PRM was feasible in all cases. Tumour volumes and hypervascular/non-hypervascular volume ratio showed significant longitudinal decrease (p < 0.05). Hypervascular volume at baseline was inversely correlated to survival (R = -0.57, p = 0.005). The only predictive parameter following cTACE to show significant survival difference was the change of the viable/non-viable ratio (p = 0.044), whereas common response assessment criteria showed no significant difference in survival. CONCLUSIONS: PRM allows a quantitative and more precise assessment of regional tumour vascularisation patterns and may be helpful for TACE treatment planning and response assessment. KEY POINTS: • PRM allows more precise assessment of tumour vascularisation compared to conventional evaluation • PRM is beneficial for cTACE treatment planning and response assessment • PRM allows a quantitative assessment of regional contrast enhancement patterns.

Pulmonary Artery Imaging in Patients with Chronic Thromboembolic Pulmonary Hypertension: Comparison of Cone-Beam CT and 64-Row Multidetector CT.

PURPOSE: To compare the depiction of pulmonary arteries in pulmonary arterial catheter-based contrast-enhanced cone-beam CT with peripheral intravenous contrast-enhanced multidetector CT in patients with suspected chronic thromboembolic pulmonary hypertension. MATERIAL AND METHODS: In 20 patients (15 men and 5 women, 63.4 y ± 16.3), cone-beam CT using a catheter placed in the main pulmonary artery and 64-row multidetector CT using an appropriate venous access were performed. Contrast enhancement was measured in the main pulmonary artery, the right and left pulmonary arteries, and the left atrium. The amount of peripheral vessel conspicuity adjacent to the pleural surface (distance from vessel-to pleura) was measured. Two readers (R1, R2) independently evaluated the pulmonary arteries for image quality and pathologic findings in both modalities. RESULTS: Contrast density was higher in the main pulmonary artery and right and left pulmonary arteries (P < .002) and lower in the left atrium (P = .001) on cone-beam CT. The smallest distance between clearly delineated vessels and the pleura was significantly lower on cone-beam CT images (P < .0001). Interobserver agreement was good for cone-beam CT (κ = 0.79) and multidetector CT (κ = 0.78), whereas intermodality agreement was moderate (R1, κ = 0.60; R2, κ = 0.59). Both readers detected more weblike stenoses with cone-beam CT (76; 22%) compared with multidetector CT (25; 7%). CONCLUSIONS: Cone-beam CT shows improved contrast between pulmonary arteries and the left atrium and allows a more detailed depiction of the pulmonary arteries.

Gadoxetate disodium in patients with primary sclerosing cholangitis: an analysis of hepatobiliary contrast excretion.

PURPOSE: To assess hepatobiliary excretion of gadoxetate disodium in patients with primary sclerosing cholangitis (PSC) over time and to determine a possible correlation with severity of the disease. MATERIALS AND METHODS: A total of 111 patients (36 females, 75 males, mean age 41.5 yr) with confirmed diagnosis of PSC who underwent gadoxetate disodium enhanced hepatic MRI were included in this retrospective institutional review board-approved study. Hepatocyte phase images (10-493 min post injection [p.i.]) were evaluated by one radiologist for the presence of contrast agent in the intrahepatic bile ducts (IBD), common bile duct (CBD), gallbladder (GB), and duodenum. In 54 patients, in whom hepatocyte phase scans were acquired within 10-20 min p.i., hepatobiliary excretion was compared with data collected in a previous study from patients without liver disease (controls; Mann-Whitney U-test). Excretion was further correlated with liver function tests (Kruskal-Wallis test). RESULTS: Compared with controls, excretion was significantly delayed in patients with PSC: 20 min p.i. gadoxetate disodium could be detected in the IBD in 55.6% (controls:100%), CBD 53.7% (controls:100%), GB 39.6% (controls:87%), duodenum 13% (controls:66%), respectively. Contrast appearance in different bile duct sections increased over time and correlated significantly with serum bilirubin and AP levels (P < 0.05). CONCLUSION: Hepatobiliary excretion of gadoxetate disodium in PSC patients is significantly delayed. Excretion correlates with bilirubin levels, and thus indirectly with severity of disease.

Image Quality and Radiation Exposure in Abdominal Angiography: A Head-to-Head Comparison of Conventional Detector-Dose-Driven Versus Contrast-to-Noise Ratio-Driven Exposure Control at Various Source-to-Image Receptor Distances and Collimations in a Pilot Phantom and Animal Study.

OBJECTIVES: This phantom and animal pilot study aimed to compare image quality and radiation exposure between detector-dose-driven exposure control (DEC) and contrast-to-noise ratio (CNR)-driven exposure control (CEC) as functions of source-to-image receptor distance (SID) and collimation. MATERIALS AND METHODS: First, an iron foil simulated a guide wire in a stack of polymethyl methacrylate and aluminum plates representing patient thicknesses of 15, 25, and 35 cm. Fluoroscopic images were acquired using 5 SIDs ranging from 100 to 130 cm and 2 collimations (full field of view, collimated field of view: 6 × 6 cm). The iron foil CNRs were calculated, and radiation doses in terms of air kerma rate were obtained and assessed using a multivariate regression. Second, 5 angiographic scenarios were created in 2 anesthetized pigs. Fluoroscopic images were acquired at 2 SIDs (110 and 130 cm) and both collimations. Two blinded experienced readers compared image quality to the reference image using full field of view at an SID of 110 cm. Air kerma rate was obtained and compared using t tests. RESULTS: Using DEC, both CNR and air kerma rate increased significantly at longer SID and collimation below the air kerma rate limit. When using CEC, CNR was significantly less dependent of SID, collimation, and patient thickness. Air kerma rate decreased at longer SID and tighter collimation. After reaching the air kerma rate limit, CEC behaved similarly to DEC. In the animal study using DEC, image quality and air kerma rate increased with longer SID and collimation (P < 0.005). Using CEC, image quality was not significantly different than using longer SID or tighter collimation. Air kerma rate was not significantly different at longer SID but lower using collimation (P = 0.012). CONCLUSIONS: CEC maintains the image quality with varying SID and collimation stricter than DEC, does not increase the air kerma rate at longer SID and reduces it with tighter collimation. After reaching the air kerma rate limit, CEC and DEC perform similarly.