Ultrasound-Derived Fat Fraction for Hepatic Steatosis Assessment: Prospective Study of Agreement With MRI PDFF and Sources of Variability in a Heterogeneous Population.

BACKGROUND. Metabolic dysfunction-associated steatotic liver disease is a growing global public health concern. Quantitative ultrasound measurements, such as ultrasound-derived fat fraction (UDFF), could provide noninvasive, cost-effective, and portable steatosis evaluation. OBJECTIVE. The purpose of this article was to evaluate utility of UDFF for steatosis assessment using proton density fat fraction (PDFF) as reference in patients undergoing liver MRI for heterogeneous indications and to assess UDFF variability. METHODS. This prospective study included a primary analysis of 187 patients (mean age, 53.8 years; 112 men, 75 women) who underwent 3-T liver MRI for any clinical indication from December 2020 to July 2021. Patients underwent investigational PDFF measurement, including determination of PDFFwhole-liver (mean PDFF of entire liver), and PDFFvoxel (PDFF in single voxel within right lobe, measured by MR spectroscopy), as well as investigational ultrasound with UDFF calculation (mean of five inter-costal measurements) within 1 hour after MRI. In a subanalysis, 21 of these patients underwent additional UDFF measurements 1, 3, and 5 hours after meal consumption. The study also included repeatability and reproducibility analysis of 30 patients (mean age, 26.3 years; 10 men, 20 women) who underwent clinical abdominal ultrasound between November 2022 and January 2023; in these patients, three operators sequentially performed UDFF measurements. RESULTS. In primary analysis, UDFF and PDFFwhole-liver measurements showed intra-class correlation coefficient (ICC) of 0.79. In Bland-Altman analysis, UDFF and PDFFvoxel measurements showed mean difference of 1.5% (95% CI, 0.6-2.4%), with 95% limits of agreement from -11.0% to 14.0%. UDFF measurements exhibited AUC for detecting PDFFvoxel at historic thresholds of 6.5% and greater, 17.4% and greater, and 22.1% and greater of 0.90, 0.95, and 0.95, respectively. In subanalysis, mean UDFF was not significantly different across time points with respect to meal consumption (p = .21). In repeatability and reproducibility analysis, ICC for intraoperator repeatability ranged from 0.98 to 0.99 and for interoperator reproducibility from 0.90 to 0.96. Visual assessment of patient-level data plots indicated increasing variability of mean UDFF measurements across operators and of intercostal measurements within individual patients with increasing steatosis. CONCLUSION. UDFF showed robust agreement with PDFF, diagnostic performance for steatosis grades, and intraoperator repeatability and interoperator reproducibility. Nonetheless, UDFF exhibited bias toward slightly larger values versus PDFF; intraoperator and interoperator variation increased with increasing steatosis. CLINICAL IMPACT. UDFF shows promise for steatosis assessment across diverse populations, although continued optimization remains warranted.

Endovascular Rescue Aortic Fenestration After Accidental False Lumen TEVAR in Type B Dissection.

PURPOSE: Unintended false-lumen thoracic endovascular aortic repair (TEVAR) is under-reported and often fatal. We present percutaneous endovascular rescue techniques for true-lumen reperfusion with strategies to address the peripheral artery perfusion needs unique to each case. CASE REPORT: Two patients deteriorated 24 hours after uncomplicated and complicated acute aortic type-B dissection TEVAR treatment at a tertiary community hospital. Reevaluation of index and repeated imaging studies revealed inadvertent false-lumen TEVAR with severe visceral and peripheral ischemia. Stepwise subtraction angiography was used to confirm continuous true-lumen catheterization from femoral puncture into the thoracic aorta. Retrograde fenestration distal to the misplaced TEVAR from the true- into the false-lumen allowed for snorkeling by distal stent-extension across the dissection membrane. In one case, TEVAR stent graft extension resulted in true-lumen re-expansion and in the other case, bare-metal stent-extension for stabilization of the dissection membrane resulted in true-lumen re-expansion in addition to preservation of visceral and peripheral perfusion via the false-lumen. Despite excellent acute hemodynamic results and initial signs of recovery, both patients eventually died (multiorgan failure; cerebral hemorrhagic infarction). CONCLUSION: Correct indication and prompt recognition of potential inadvertent false-lumen stenting is critical to avoid disastrous sequelae, for example, malperfusion. Endovascular salvage is feasible for restoration of correct perfusion and must be performed in a timely manner. CLINICAL IMPACT: Clinically apparent, complicated type-B dissection necessitates instantaneous treatment. Prerequisite for an endovascular approach is a true-lumen guidewire continuously from access to the ascending aorta. DSA after TEVAR and prompt clinical re-evaluation are to verify effective visceral and peripheral restoration of blood flow. Despite these measures, inadvertent false-lumen TEVAR may occur rarely. Immediate recognition may allow for timely true-lumen re-expansion using percutaneous endovascular salvage techniques e.g. retrograde fenestration from the true- into the false-lumen for distal snorkeling of the misplaced TEVAR across the dissection membrane. However, morbidity and mortality are very high, if erroneous stent graft placement is not identified early.

Diagnostic Performance of a Lower-dose Contrast-Enhanced 4D Dynamic MR Angiography of the Lower Extremities at 3 T Using Multisegmental Time-Resolved Maximum Intensity Projections.

BACKGROUND: For peripheral artery disease (PAD), MR angiography (MRA) is a well-established diagnostic modality providing morphologic and dynamic information comparable to digital subtraction angiography (DSA). However, relatively large amounts of contrast agents are necessary to achieve this. PURPOSE: To evaluate the diagnostic accuracy of time-resolved 4D MR-angiography with interleaved stochastic trajectories (TWIST-MRA) by using maximum intensity projections (MIPs) of dynamic images acquired with reduced doses of contrast agent. STUDY TYPE: Retrospective. POPULATION: Forty adult PAD patients yielding 1088 artery segments. FIELD STRENGTH/SEQUENCE: A 3.0 T, time-resolved 4D MR-angiography with TWIST-MRA and MIP of dynamic images. ASSESSMENT: DSA was available in 14 patients (256 artery segments) and used as reference standard. Three-segmental MIP reconstructions of TWIST-images after administration of 3 mL of gadolinium-based contrast agent (Gadoteridol/Prohance®, 0.5 M) per anatomical level (pelvis, thighs, and lower legs) yielded 256 artery segments for correlation between MRA and DSA. Three independent observers rated image quality (scale: 1 [nondiagnostic] to 4 [excellent]) and the degree of venous overlay (scale: 0 [none] to 2 [significant]) for all segments. Diagnostic accuracy for the detection of >50% stenosis and artery occlusion was calculated for all observers. STATISTICAL TESTS: Binary classification test (sensitivity, specificity, positive/negative predictive values, diagnostic accuracy). Intraclass correlation coefficients (ICCs), logistic regression analysis with comparison of areas under the receiver-operating-characteristics (ROC) curves (AUCs) with the DeLong method. Bland-Altman-comparison. RESULTS: High diagnostic performance was achieved for the detection of >50% stenosis (sensitivity 92.9% [84.3-99.9% (95%-CI)] and specificity 98.5% [95.7-99.8% (95%-CI)]) and artery occlusion (sensitivity 93.1% [77.2-99.2% (95%-CI)] and specificity 99.1% [96.9-99.9% (95%-CI)]). Inter-reader agreement was excellent with ICC values ranging from 0.95 to 1.0 for >50% artery stenosis and occlusion. Image quality was good to excellent for both readers (3.41 ± 0.72, 3.33 ± 0.65, and 3.38 ± 0.61 [mean ± SD]) with good correlation between observer ratings (ICC 0.71-0.81). No significant venous overlay was observed (0.06 ± 0.24, 0.23 ± 0.43 and 0.11 ± 0.45 [mean ± SD]). DATA CONCLUSION: MIPs of dynamic TWIST-MRA offer a promising diagnostic alternative necessitating only reduced amounts (50%) of gadolinium-based contrast agents for the entire runoff vasculature. EVIDENCE LEVEL: 3 TECHNICAL EFFICACY: Stage 2.

Volume-Function Analysis (LiMAx Test) in Patients with HCC and Cirrhosis Undergoing TACE-A Feasibility Study.

BACKGROUND: Transarterial chemoembolization (TACE) is an important therapy for hepatocellular carcinoma (HCC) in cirrhosis. In particular in advanced cirrhosis, post-TACE hepatic failure liver (PTHF) failure may develop. Currently, there is no standardization for the periinterventional risk assessment. The liver maximum capacity (LiMAx) test assesses the functional liver capacity, but has not been investigated in this setting. AIMS: The aim of this study was to prospectively evaluate periinterventional LiMAx and CT volumetry measurements in patients with cirrhosis and HCC undergoing repetitive TACE. METHODS: From 06/2016 to 11/2017, eleven patients with HCC and cirrhosis undergoing TACE were included. LiMAx measurements (n = 42) were conducted before and after each TACE. Laboratory parameters were correlated with the volume-function data. RESULTS: The median LiMAx levels before (276 ± 166 µg/kg/h) were slightly reduced after TACE (251 ± 122 µg/kg/h; p = 0.08). This corresponded to a median drop of 7.1%. Notably, there was a significant correlation between LiMAx levels before TACE and bilirubin (but not albumin nor albumin-bilirubin [ALBI] score) increase after TACE (p = 0.02, k = 0.56). Furthermore, a significantly higher increase in bilirubin in patients with LiMAx ≤ 150 µg/kg/h was observed (p = 0.011). LiMAx levels at different time points in single patients were similar (p = 0.2). CONCLUSION: In our prospective pilot study in patients with HCC and cirrhosis undergoing multiple TACE, robust and reliable LiMAx measurements were demonstrated. Lower LiMAx levels before TACE were associated with surrogate markers (bilirubin) of liver failure after TACE. Specific subgroups at high risk of PTHF should be investigated. This might facilitate the future development of strategies to prevent occurrence of PTHF.

Establishment of Submillisievert Abdominal CT Protocols With an In Vivo Swine Model and an Anthropomorphic Phantom.

OBJECTIVE. The purpose of this study was to evaluate radiation dose, effective dose, and image quality of different low-dose abdominal CT protocols in a swine model and an anthropomorphic phantom using a third-generation dual-source CT scanner. MATERIALS AND METHODS. Four different abdominal low-dose protocols were established using a swine model and were regarded as diagnostic by two experienced radiologists on the basis of clarity and sharpness of anatomic structures. General image conditions such as noise and spatial resolution as well as diagnostic acceptability and artifacts were evaluated. Objective image quality was determined by measuring signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) in different anatomic locations. To evaluate the effective dose, thermoluminescent dosimeter (TLD) measurements were repeated in a phantom. RESULTS. Diagnostic acceptability, spatial resolution, and noise were rated as optimal in all four protocols, which were therefore regarded as diagnostic. We found no statistically significant differences in SNR or CNR for the four low-dose protocols. Effective dose determined from the phantom measurements did not exceed 0.33 mSv for any protocol. Overall evaluation of the 86 TLD measurements for the four low-dose protocols revealed a statistically significant difference in radiation dose (p < 0.0001), showing that the dual-source protocol had the lowest radiation dose. CONCLUSION. Submillisievert abdominal CT is feasible with good image quality and doses even lower than conventional abdominal radiography. Our dual-source protocol achieved the lowest dose, which further shows that dual-source imaging is possible in the submillisievert range without additional dose.

Predictive Power of Liver Maximum Function Capacity Test in Transjugular Intrahepatic Portosystemic Shunt Patients: A Pilot Study.

BACKGROUND: Transjugular intrahepatic shunt (TIPSS) is placed in patients with variceal bleeding, refractory ascites, and for other indications. Postprocedural liver function-associated complications (LFAC), including hepatic encephalopathy (HE) and liver failure, represent a major setback. Current methods to predict complications are insufficient. OBJECTIVES: We investigated in a pilot study of patients prior TIPSS placement whether the risk of LFAC correlates with the functional reserve of the liver, as assessed by liver maximum function capacity (LiMAx) test. METHODS: Prospectively we included patients prior TIPSS placement between June 2016 and November 2017 at Saarland University Medical Center. LiMAx was conducted before and after TIPSS placement. Patients with HE prior TIPSS, as well as other factors predisposing to HE, including concomitant sedative drugs, current bacterial infections and sepsis, were excluded. Overt HE (OHE), LiMAx, and laboratory values were assessed before and after TIPSS placement. Data were analyzed in multivariate regression and AUROC models. RESULTS: Mean age was 60 ± 8 years. Patients (n = 20) were mainly men (65%), and presented predominantly with Child-Pugh class B (90%). Indications for TIPSS were most commonly refractory ascites or recurrent variceal bleeding. In total, 40% of the patients developed LFAC after TIPSS placement. Expectedly, LiMAx decreased and serum bilirubin increased after TIPSS. LiMAx drop ≥20% was the only parameter predicting the development of LFAC after TIPSS in multivariate regression and AUROC analysis. CONCLUSIONS: In multivariate regression models and AUROC analysis, a drop in LiMAx predicted the development of LFAC after TIPSS placement. Additional larger studies assessing OHE and early liver failure separately are warranted.

Percutaneous endovascular tissue sampling of endoluminal tumors using directional atherectomy.

OBJECTIVES: To evaluate technical feasibility and safety of endovascular tumor specimen sampling using an escalating endovascular biopsy strategy using a directional atherectomy device compared with forceps biopsy and catheter aspiration. MATERIALS AND METHODS: Between 2013 and 2017, a cohort of ten consecutive patients (6 male; median age 56, range 39-73 years) was referred for sampling of endovascular masses. Localizations included the abdominal aorta (n = 4), left brachiocephalic vein (n = 2), inferior vena cava (n = 1), and left pulmonary artery (n = 3). For each individual mass, all three endovascular tissue sampling approaches were applied including catheter-based aspiration, straight two-jaw biopsy forceps, and directional atherectomy during a single session. RESULTS: Aspiration and forceps biopsy did not provide sufficient material for histological analyses. In contrast, technical success for endovascular tumor sampling using directional atherectomy was 100%. After two atherectomy passages, sufficient material was available for each vessel region allowing histologic diagnosis, which revealed sarcoma and chronic inflammation for masses in the aorta, angiosarcoma for brachiocephalic vein, hepatocellular carcinoma for inferior vena cava, and angiosarcoma for pulmonary artery. In case of a histologically benign diagnosis, no malignant tumor proliferation was obvious on follow-up imaging studies after 3 months and 1 year. Thus, the rate of false-negative results was considered 0%. No procedure-associated complications, e.g., vessel perforation, were recorded. CONCLUSION: Preliminary results in a limited number of patients proved directional atherectomy beneficial as a safe and feasible technique for endoluminal tissue sampling of vascular masses. Additional large-scale studies are necessary and worthy for further evaluation in clinical practice. KEY POINTS: • Endovascular masses pose a challenge to appropriate clinical management. • Off-label directional atherectomy proved to be a safe and feasible technique for endoluminal tissue sampling of vascular masses. Furthermore, directional atherectomy was superior to aspiration or forceps biopsy in our small study cohort. • Directional atherectomy may represent the last or only option for tissue probing as a prerequisite for further treatment decisions.

Presepsin and Inflammatory Markers Correlate With Occurrence and Severity of Nonocclusive Mesenteric Ischemia After Cardiovascular Surgery.

OBJECTIVES: To prospectively evaluate the relationship of established inflammatory markers and presepsin on nonocclusive mesenteric ischemia and to correlate presepsin levels to the occurrence and severity of nonocclusive mesenteric ischemia. DESIGN: Patients were prospectively enrolled and blood samples taken, followed by a retrospective evaluation of laboratory values and angiographic findings. The study was ethics committee approved. SETTINGS: Patients with clinical suspicion of nonocclusive mesenteric ischemia underwent catheter angiography of the superior mesenteric artery. Images were assessed by two experienced radiologists on consensus basis using a previously published standardized reporting system (Homburg-Nonocclusive Mesenteric Ischemia-Score). Two groups were formed according to the severity of nonocclusive mesenteric ischemia, mild and severe, patients without clinical signs of nonocclusive mesenteric ischemia formed the reference group. These data were correlated to inflammatory blood markers assessed pre- and postoperatively: C-reactive protein, leucocytes, procalcitonin, and presepsin as well as outcome data. PATIENTS: Between January 2010 and March 2011, a total of 839 patients undergoing cardiovascular surgery participated in this study. MEASUREMENTS AND MAIN RESULTS: Mild nonocclusive mesenteric ischemia was diagnosed in 4.5%, and severe nonocclusive mesenteric ischemia in 3.2%. Median postoperative presepsin concentrations were significantly greater in mild and severe nonocclusive mesenteric ischemia than in non-nonocclusive mesenteric ischemia. Statistics showed that postoperative presepsin better discriminated mild and severe nonocclusive mesenteric ischemia than any other tested biomarker. CONCLUSIONS: Elevated postoperative plasma presepsin concentrations are an independent predictor of mild and severe nonocclusive mesenteric ischemia. The established inflammatory blood markers significantly correlate with the development and severity of nonocclusive mesenteric ischemia.

Three-dimensional ultrashort echo time MRI and Short T2 images generated from subtraction for determination of tumor burden in lung cancer: Preclinical investigation in transgenic mice.

PURPOSE: To investigate the potential of 3D ultrashort echo time MRI and short T2 images generated by subtraction for determination of total tumor burden in lung cancer. METHODS: As an animal model of spontaneously developing non-small cell lung cancer, the K-rasLA1 transgenic mouse was used. Three-dimensional MR imaging was performed with radial k-space acquisition and echo times of 20 µs and 1 ms. For investigation of the short T2 component in the recorded signal, subtraction images were generated from these data sets and used for consensus identification of tumors. Next, manual segmentation was performed on all MR images by two independent investigators. MRI data were compared with the results from histologic investigations and among the investigators. RESULTS: Tumor number and total tumor burden from imaging experiments correlated strongly with the results of histologic investigations. Intra- and interuser comparison showed highest correlations between the individual measurements for ultra-short TE MRI. CONCLUSIONS: Three-dimensional MRI protocols facilitate accurate tumor identification in mice harboring lung tumors. Ultrashort TE MRI is the superior imaging strategy when investigating lung tumors of miscellaneous size with 3D MR imaging strategies. Magn Reson Med 79:1052-1060, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Glass-Fiber-based MR-safe Guidewire for MR Imaging-guided Endovascular Interventions: In Vitro and Preclinical in Vivo Feasibility Study.

Purpose To evaluate glass-fiber-based guidewires that are safe for magnetic resonance (MR) imaging-guided endovascular interventions by using a phantom and an in vivo swine model. Materials and Methods MR imaging-safe guidewires were made from micropultruded glass and/or aramid fibers and epoxy resin with diameters of 0.89 mm (0.035 inch) for standard and stiff guidewires and 0.36 mm (0.014 inch) for micro guidewires. MR imaging visibility and mechanical properties were assessed in a pulsatile flow model. After approval was obtained from the institutional animal care and use committee, MR imaging guidewires were evaluated for standard endovascular procedures in nine pigs. Real-time steady-state free-precession sequences were used for MR imaging-guided catheterization, balloon dilation, and stent implantation into aorto-iliac/visceral arteries and the vena cava (temporal resolution, five images per second; and spatial resolution, 150-mm field of view, and 128 × 128 matrix) with a 1.5-T clinical imager. Visualization with the guidewires was rated on a four-point scale, handling was rated on a three-point scale, and catheterization times for different vessel regions were determined by two interventional radiologists. Afterward, handling ratings and catheterization times were obtained for standard nitinol guidewires during x-ray-based fluoroscopy. Cannulation times, signal intensity in each vessel region, and visualization and handling ratings were measured for the MR imaging guidewires. Bland-Altman analysis was performed for inter- and intraobserver variability of cannulation time. Spearman rank correlation was used to compare handling of MR imaging guidewires and standard nitinol guidewires. Results MR imaging guidewires were characterized by good to excellent visibility, with a continuous artifact of 2 mm in diameter and 4 × 8-mm ball-shaped tip marker. Stiffness, flexibility, and guidance reflected comparable times for all in vitro and in vivo procedures with both the MR imaging and standard nitinol guidewires. Standard and micro MR imaging guidewires were most suitable for the iliac crossover maneuver. Phantom visceral artery cannulation was easier with standard and micro MR imaging guidewires. The stiff MR imaging guidewire provided the best support for cannulation of the swine aorta and vena cava. All interventional procedures were performed successfully without complications. Conclusion Preliminary results showed that the use of glass-fiber-based guidewires for evaluation of MR imaging-guided endovascular interventions is technically feasible and safe in a swine model, and potentially, in humans. © RSNA, 2017 Online supplemental material is available for this article.

Workflow optimisation for multimodal imaging procedures: a case of combined X-ray and MRI-guided TACE.

This study presents a framework for workflow optimisation of multimodal image-guided procedures (MIGP) based on discrete event simulation (DES). A case of a combined X-Ray and magnetic resonance image-guided transarterial chemoembolisation (TACE) is presented to illustrate the application of this method. We used a ranking and selection optimisation algorithm to measure the performance of a number of proposed alternatives to improve a current scenario. A DES model was implemented with detail data collected from 59 TACE procedures and durations of magnetic resonance imaging (MRI) diagnostic procedures usually performed in a common MRI suite. Fourteen alternatives were proposed and assessed to minimise the waiting times and improve workflow. Data analysis observed an average of 20.68 (7.68) min of waiting between angiography and MRI for TACE patients in 71.19% of the cases. Following the optimisation analysis, an alternative was identified to reduce waiting times in angiography suite up to 48.74%. The model helped to understand and detect 'bottlenecks' during multimodal TACE procedures, identifying a better alternative to the current workflow and reducing waiting times. Simulation-based workflow analysis provides a cost-effective way to face some of the challenges of introducing MIGP in clinical radiology, highligthed in this study.

Influence of Respiratory Position on Contrast Attenuation in Pulmonary CT Angiography: A Prospective Randomized Clinical Trial.

OBJECTIVE: The purpose of this study was to prospectively compare the effect of inspiration and resting expiratory position on contrast enhancement in pulmonary CT angiography (CTA) in a randomized clinical trial. SUBJECTS AND METHODS: In accordance with a power analysis performed before the study, we included 28 consecutive patients referred for evaluation of suspected pulmonary embolism in this prospective study. Patients were randomly assigned to perform either inspiration (n = 14; six men, eight women; mean age [SD], 38.1 ± 9.8 years) or resting expiratory position (n = 14; six men, eight women; mean age: 42.1 ± 9.2 years). All patients were scanned in a standardized supine position and scanning parameters were kept constant. Contrast medium was injected automatically with bolus tracking. Objective pulmonary vessel attenuation was quantified with digital measurement. Results were analyzed by using the unpaired t test and chi-square test. RESULTS: Patients in the resting expiratory position showed significantly higher contrast attenuation than those who performed inspiration (302.9 ± 11.9 HU vs 221.5 ± 20.9 HU; p < 0.01). There were no significant differences in applied total volume of contrast agent (76.8 ± 1.9 mL vs 75.7 ± 1.6 mL; p = 0.6765), total volume including normal saline bolus (116.8 mL ± 2.8 mL vs 121.8 mL ± 2.3 mL; p = 0.1724) or flow rate (3.1 mL/s ± 0.1 mL/s vs 3.2 mL/s ± 0.1 mL/s). CONCLUSION: Pulmonary CTA should be performed in the resting expiratory position, and patients should be instructed to avoid inspiration to achieve the highest possible attenuation in the pulmonary arteries.

Assessment of operability by means of CTPA and perfusion SPECT in patients with chronic thromboembolic pulmonary hypertension.

BACKGROUND: Chronic thromboembolic pulmonary hypertension (CTEPH) can potentially be cured by pulmonary thrombendarterectomy (PEA), the criteria for differentiation between operable and non-operable patients are not standardized. PURPOSE: To retrospectively evaluate the value of rigidly registered computed tomography pulmonary angiography (CTPA) and single photon emission CT (SPECT) in differentiating for PEA. MATERIAL AND METHODS: Forty-nine patients with CTEPH (21 men; age, 58 ± 13 years) were evaluated by an interdisciplinary expert board using all available diagnostic information and their consensus statement as gold standard. For SPECT a lobe based perfusion score was visually assessed using the score of 0 (lack of perfusion) to 1 (normal perfusion) calculating percentage of vascular obstruction (PVO). By CTPA, vascular obstruction index (OI) of central, peripheral, and global PA-bed were determined. The accuracy of the alignment between CTPA and SPECT was determined by fusion score (FS) ranging from 1 (no alignment) to 5 (exact alignment). Angiography provided PA pressure (PAP), pulmonary vascular resistance (PVR), and PA wedge pressure (PAWP). Receiver operating characteristics (ROC) analysis was performed. RESULTS: Twenty-nine patients were considered surgically amenable, and 20 patients were inoperable. Mean PAP, PVR, and PAWP were 48 ± 11 mmHg, 868 ± 461 dynes*sec*cm(-5), and 11 ± 5 mmHg, without differences between surgical and non-surgical patients (P > 0.5). In all patients accurate registration was reached (FS = 4.1 ± 0.7; range, 2-5). PVO and central OI separated PEA-amenable patients (P ≤ 0.001) resulting in the area under the curve of 0.828 (cutoff for PVO: 37.8% with a sensitivity of 82% and specificity of 79%) and 0.755 (cutoff for central OI: 29% with a sensitivity and specificity of 86.2% and 79%) for operability. CONCLUSION: An accurate interpretation of rigidly registered CTPA and perfusion SPECT may contribute to stratification of operability in patients with CTEPH.

Local low-dose thrombolysis for safe and effective treatment of venous port-catheter thrombosis.

PURPOSE: Retrospective evaluation of local low-dose thrombolysis for treatment of venous port-catheter thrombosis. METHODS: A total of 1,031 patients with dysfunctional port systems underwent port angiography depicting 181 patients with thrombosis around the port-catheter. A total of 165 patients (male 35, female 130; age 57.3 ± 12.9 [20-83] years) underwent thrombolysis by single injection of 3 mg alteplase into the port system. Patients were followed up by clinical and angiographic/radiological port controls the next day and 12.9 ± 17.9 [1-81] months on the basis of regular oncologic staging examinations. RESULTS: Thrombosis occurred 10.1 ± 19.3 [median 2.9] months after port implantation and was clinically suspected by difficult blood aspiration in 146 of 181 (80.7 %) and high resistance to injection fluids in 75 (41.4 %) patients. A predictor for angiographically confirmed port-catheter thrombosis was a combination of both (73, 40.3 % patients) (Fisher's exact test p < 0.0001; positive predictive value 0.8977), or suboptimal (not cavoatrial) port-catheter position (92, 50.8 % patients) (p = 0.0047; positive predictive value 0.8276). The cumulative success rate of thrombolysis was 92.7 % (153 of 165 patients). Initial thrombolysis was effective in 127 (77.0 %) patients. Repeated (up to 6 times) thrombolysis was effective in 26 of 31 patients after second or third thrombolysis. Extensive central venous thrombosis (9 patients) predicted ineffective thrombolysis (p < 0.0001). Primary patency of successfully treated devices was 92.8 % at 1 month and 84.9 % at 3 months. Rethrombosis occurred in 27 patients after 4.4 ± 6.6 (median 1.8) months. Primary rethrombolysis was effective in 22 (81.5 %) patients. Cumulative patency was 100 % at 3 months. CONCLUSIONS: Difficult aspiration combined with high resistance to injection fluids or suboptimal port-catheter position are strong independent predictors for port-catheter thrombosis. Local low-dose thrombolysis or repeat thrombolysis is safe and effective in the absence of large central venous thrombosis.

Percutaneous Re-positioning of Dislocated Port-Catheters in Patients with Dysfunctional Central-Vein Port-Systems.

PURPOSE: Observational analysis of percutaneous repositioning of displaced port-catheters in patients with dysfunctional central-venous port-systems. METHODS: A total of 1061 patients with dysfunctional venous pectoral port-systems were referred for port-angiography. Dislocated port-catheters were identified in 37 (3.5 %) patients (11 males, mean age 58.1 ± 7.2 [range 48-69] years; 26 females, 57.0 ± 13.5 [range 24-75] years) 3.9 ± 6.6 months (range 1 day-26 months) after port-implantation. Percutaneous repositioning in all patients was performed by transfemoral catheter maneuvers, snaring, or wire-assisted long-loop snaring. Primary endpoint was successful repositioning. Safety endpoints included port-damage or procedure-related complications. Follow-up encompassed routine clinical and radiological controls, including chest X-ray or computed tomography for 12.9 ± 17.9 (range 1-81) months. RESULTS: Clinical signs of port-dysfunction due to dislocation of port-catheters included difficult aspiration in 23 (62.2 %), resistance or inability to inject in 17 (46.0 %), and pain during injection in 2 (5.4 %) patients. Primary technical success for repositioning displaced port-catheters was 97.3 % (36/37 patients). In 1 (2.7 %) patient, repositioning failed due to complete embedding of the port-catheter in an extensive chronic jugular vein thrombosis (Paget-von-Schroetter syndrome) that prevented endovascular access to the port-catheter. Redisplacement occurred after initial successful repositioning: immediately in two patients due to a too short port-catheter (two-tailed Fisher's exact-test, p = 0.0101), and in two patients with appropriate catheter-length after 5, resp. 7 months. No procedure-associated complications, e.g., port-catheter disconnection or disruption, occurred. CONCLUSIONS: Repositioning of dysfunctional displaced central-venous port-catheters with appropriate catheter-length is safe and effective. Even challenging conditions, e.g., wall-adherent port-catheter tip or a thrombosed catheter-bearing vein are feasible. Repositioning of too short port-catheters is ineffective.

Paclitaxel-coated balloon angioplasty for symptomatic central vein restenosis in patients with hemodialysis fistulas.

PURPOSE: To report a retrospective observational analysis of standard balloon angioplasty (BA) vs. paclitaxel-coated balloon angioplasty (PCBA) for symptomatic central vein restenoses in patients with impaired native hemodialysis fistulas. METHODS: A retrospective review was conducted of 27 consecutive patients (15 men; mean age 66 ± 13.8 years, range 39-90) with 32 central vein stenoses (CVS; 6 axillary, 11 subclavian, 12 brachiocephalic, and/or 3 superior caval veins) treated successfully using BA. Freedom from reintervention after BA of de novo lesions was 7.4 ± 7.9 months (range 1-24). Twenty-five (92.6%) patients developed symptomatic restenoses and were treated one or more times by BA (n = 32) or PCBA (n = 20) using custom-made paclitaxel-coated balloons (diameter 6-14 mm). RESULTS: Technical (< 30% residual stenosis) and clinical (functional fistula) success rates for the initial and secondary angioplasty procedures were 100%. No minor/major procedure-associated complications occurred. Mean follow-up was 18.4 ± 17.5 months. Kaplan-Meier analysis for freedom from target lesion revascularization (TLR) found PCBA superior to BA (p = 0.029). Median freedom from TLR after BA was 5 months; after PCBA, > 50% of patients were event-free during the observation period (mean freedom from TLR 10 months). Restenosis intervals were prolonged by PCBA (median 9 months) vs. BA (median 4 months; p = 0.023). CONCLUSION: Paclitaxel-coated balloon angioplasty of central vein restenosis in patients with hemodialysis shunts yields a statistically significant longer freedom from TLR compared to standard balloon angioplasty.

Effect of renal denervation on left ventricular mass and function in patients with resistant hypertension: data from a multi-centre cardiovascular magnetic resonance imaging trial.

AIMS: Sympathetic stimulation induces left ventricular hypertrophy and is associated with increased cardiovascular risk. Catheter-based renal denervation (RDN) has been shown to reduce sympathetic outflow and blood pressure (BP). The present multi-centre study aimed to investigate the effect of RDN on anatomic and functional myocardial parameters, assessed by cardiac magnetic resonance (CMR), in patients with resistant hypertension. METHODS AND RESULTS: Cardiac magnetic resonance was performed in 72 patients (mean age 66 ± 10 years) with resistant hypertension (55 patients underwent RDN, 17 served as controls) at baseline and after 6 months. Clinical data and CMR results were analysed blindly. Renal denervation significantly reduced systolic and diastolic BP by 22/8 mm Hg and left ventricular mass index (LVMI) by 7.1% (46.3 ± 13.6 g/m(1.7) vs. 43.0 ± 12.6 g/m(1.7), P < 0.001) without changes in the control group (41.9 ± 10.8 g/m(1.7) vs. 42.0 ± 9.7 g/m(1.7), P = 0.653). Ejection fraction (LVEF) in patients with impaired LVEF at baseline (<50%) significantly increased after RDN (43% vs. 50%, P < 0.001). Left ventricular circumferential strain as a surrogate of diastolic function in the subgroup of patients with reduced strain at baseline increased by 21% only in the RDN group (-14.8 vs. -17.9; P = 0.001) and not in control patients (-15.5 vs. -16.4, P = 0.508). CONCLUSIONS: Catheter-based RDN significantly reduced BP and LVMI and improved EF and circumferential strain in patients with resistant hypertension, occurring partly BP independently.

Low-dose gadobenate dimeglumine-enhanced MRI of the kidney for the differential diagnosis of localized renal lesions.

OBJECTIVE: To evaluate low-dose gadobenate dimeglumine-enhanced MRI for the differential diagnosis of malignant renal tumors. METHODS: Sixty-two consecutive patients with unclear diagnosis at MDCT/ultrasound underwent dynamic CE-MRI of the kidneys with 0.05 mmol/kg gadobenate dimeglumine. Retrospective image evaluation was performed by two blinded readers. Lesion diagnosis at CE-MRI was correlated with findings from histology following tumor resection or from imaging follow-up after at least 1 year. Assessments were performed of diagnostic quality and level of diagnostic information. RESULTS: Thirty-nine (63 %) patients were correctly diagnosed with malignant lesions (36 with RCC, 2 with renal metastases, 1 with lymphoma) while 14 (22.6 %) patients were correctly diagnosed with benign (n = 12) or no (n = 2) lesions. Eight patients were considered false positive (5 with oncocytoma, 3 with atypical AML) and 1 patient false negative (atypical RCC). The sensitivity, specificity, accuracy, PPV, and NPV for the diagnosis of malignant renal lesions were 97.5 % (39/40), 63.6 % (14/22), 85.5 % (53/62), 83.0 % (39/47), and 93.3 % (14/15), respectively. Images were excellent in 60 and good in 2 patients. Minimal artifacts that did not compromise diagnosis were noted in 4/62 patients. CONCLUSION: Low-dose gadobenate dimeglumine-enhanced MRI is effective for the differential diagnosis of malignant renal tumors.

Machine learning assisted feature identification and prediction of hemodynamic endpoints using computed tomography in patients with CTEPH.

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare but potentially curable cause of pulmonary hypertension (PH). Currently PH is diagnosed by right heart catheterisation. Computed tomography (CT) is used for ruling out other causes and operative planning. This study aims to evaluate importance of different quantitative/qualitative imaging features and develop a supervised machine learning (ML) model to predict hemodynamic risk groups. 127 Patients with diagnosed CTEPH who received preoperative right heart catheterization and thoracic CTA examinations (39 ECG-gated; 88 non-ECG gated) were included. 19 qualitative/quantitative imaging features and 3 hemodynamic parameters [mean pulmonary artery pressure, right atrial pressure (RAP), pulmonary artery oxygen saturation (PA SaO2)] were gathered. Diameter-based CT features were measured in axial and adjusted multiplane reconstructions (MPR). Univariate analysis was performed for qualitative and quantitative features. A random forest algorithm was trained on imaging features to predict hemodynamic risk groups. Feature importance was calculated for all models. Qualitative and quantitative parameters showed no significant differences between ECG and non-ECG gated CTs. Depending on reconstruction plane, five quantitative features were significantly different, but mean absolute difference between parameters (MPR vs. axial) was 0.3 mm with no difference in correlation with hemodynamic parameters. Univariate analysis showed moderate to strong correlation for multiple imaging features with hemodynamic parameters. The model achieved an AUC score of 0.82 for the mPAP based risk stratification and 0.74 for the PA SaO2 risk stratification. Contrast agent retention in hepatic vein, mosaic attenuation pattern and the ratio right atrium/left ventricle were the most important features among other parameters. Quantitative and qualitative imaging features of reconstructions correlate with hemodynamic parameters in preoperative CTEPH patients-regardless of MPR adaption. Machine learning based analysis of preoperative imaging features can be used for non-invasive risk stratification. Qualitative features seem to be more important than previously anticipated.