Epicardial adipose tissue dispersion at CT and recurrent atrial fibrillation after pulmonary vein isolation.

OBJECTIVES: Epicardial adipose tissue (EAT) remodeling is associated with atrial fibrillation (AF). Left atrial (LA) EAT dispersion on cardiac CT is a non-invasive imaging biomarker reflecting EAT heterogeneity. We aimed to investigate the association of LA EAT dispersion with AF recurrence after pulmonary vein isolation (PVI). METHODS: In a prospective registry of consecutive patients undergoing first PVI, mean EAT attenuation values were measured on contrast-enhanced cardiac CT scans in Hounsfield units (HU) within low (- 195 to - 45 HU) and high (- 44 to - 15 HU) threshold EAT compartments around the left atrium (LA). EAT dispersion was defined as the difference between the mean HU values within the two EAT compartments. Continuous variables were compared between groups using the Mann-Whitney U test and cox proportional hazard models were used to calculate hazard ratios of predictors of 1-year AF recurrence. RESULTS: A total of 208 patients were included, 135 with paroxysmal AF and 73 with persistent AF. LA EAT dispersion was significantly larger in patients with persistent compared to paroxysmal AF (52.6 HU vs. 49.9 HU; p = 0.001). After 1 year of follow-up, LA EAT dispersion above the mean (> 50.8 HU) was associated with a higher risk of AF recurrence (HR 2.3, 95% CI 1.5-3.6; p < 0.001). It retained its predictive value when corrected for age, sex, body mass index, LA volume, and AF type (HR 2.8, 95% CI 1.6-4.6; p < 0.001). CONCLUSION: A larger LA EAT dispersion on contrast-enhanced cardiac CT scans, reflecting EAT heterogeneity, is independently associated with AF recurrence after PVI. CLINICAL RELEVANCE STATEMENT: Based on LA EAT dispersion assessment, a more accurate risk stratification and patient selection may be possible based on a pre-procedural cardiac CT when planning PVI. KEY POINTS: • Epicardial adipose tissue (EAT) remodeling is associated with atrial fibrillation (AF). • A larger left atrial EAT dispersion in a pre-procedural cardiac CT was associated with a higher 1-year AF recurrence risk after pulmonary vein isolation. • A pre-procedural cardiac CT with left atrial EAT dispersion assessment may provide a more accurate risk stratification and patient selection for PVI.

The Relationship between Enhancing Left Atrial Adipose Tissue at CT and Recurrent Atrial Fibrillation.

Background The association of epicardial adipose tissue (EAT) and its metabolic activity with atrial fibrillation (AF) is an area of active investigation. Left atrial (LA) enhancing EAT (e-EAT) at cardiac CT may be a noninvasive surrogate marker for the metabolic activity of EAT. Purpose To determine the relationship between LA e-EAT and recurrence after AF ablation. Materials and Methods In a secondary analysis of a prospective registry of consecutive patients (from July 2018 to December 2019) undergoing first AF ablation, total and LA EAT were segmented on preprocedural noncontrast- and contrast-enhanced cardiac CT scans. LA e-EAT volume fraction was defined as the LA EAT volume difference between the noncontrast- and contrast-enhanced scan divided by the total LA EAT volume on the noncontrast-enhanced scan (threshold values, -15 HU to -195 HU). Continuous variables were compared between groups by using the Mann-Whitney U test. Cox proportional hazard models were used to calculate hazard ratios of predictors of 1-year AF recurrence. Results A total of 212 patients (mean age, 64 years; 159 men) who underwent a first AF ablation were included (paroxysmal AF, 64%; persistent AF, 36%). The LA EAT volume was higher in patients with persistent versus paroxysmal AF (50 cm3 [IQR, 37-72] vs 37 [IQR, 27-49]; P < .001), but no difference was found for LA e-EAT (P = .09). After 1 year of follow-up, AF recurrence rate was 77 of 212 (36%). LA e-EAT above the mean (>33%) was associated with a higher risk of AF recurrence (hazard ratio [HR], 2.1; 95% CI: 1.3, 3.3; P < .01). In a multivariable Cox regression analysis, LA e-EAT retained its predictive value when corrected for sex, age, AF phenotype, LA volume index, and LA EAT volume (HR, 1.9; 95% CI: 1.1, 3.1; P = .02). Conclusion Left atrial enhancing epicardial adipose tissue was independently associated with recurrence after atrial fibrillation ablation. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Stojanovska in this issue.

Radial self-navigated native magnetic resonance angiography in comparison to navigator-gated contrast-enhanced MRA of the entire thoracic aorta in an aortic patient collective.

BACKGROUND: The native balanced steady state with free precession (bSSFP) magnetic resonance angiography (MRA) technique has been shown to provide high diagnostic image quality for thoracic aortic disease. This study compares a 3D radial respiratory self-navigated native MRA (native-SN-MRA) based on a bSSFP sequence with conventional Cartesian, 3D, contrast-enhanced MRA (CE-MRA) with navigator-gated respiration control for image quality of the entire thoracic aorta. METHODS: Thirty-one aortic native-SN-MRA were compared retrospectively (63.9 ± 10.3 years) to 61 CE-MRA (63.1 ± 11.7 years) serving as a reference standard. Image quality was evaluated at the aortic root/ascending aorta, aortic arch and descending aorta. Scan time was recorded. In 10 patients with both MRA sequences, aortic pathologies were evaluated and normal and pathologic aortic diameters were measured. The influence of artifacts on image quality was analyzed. RESULTS: Compared to the overall image quality of CE-MRA, the overall image quality of native-SN-MRA was superior for all segments analyzed (aortic root/ascending, p < 0.001; arch, p < 0.001, and descending, p = 0.005). Regarding artifacts, the image quality of native-SN-MRA remained superior at the aortic root/ascending aorta and aortic arch before and after correction for confounders of surgical material (i.e., susceptibility-related artifacts) (p = 0.008 both) suggesting a benefit in terms of motion artifacts. Native-SN-MRA showed a trend towards superior intraindividual image quality, but without statistical significance. Intraindividually, the sensitivity and specificity for the detection of aortic disease were 100% for native-SN-MRA. Aortic diameters did not show a significant difference (p = 0.899). The scan time of the native-SN-MRA was significantly reduced, with a mean of 05:56 ± 01:32 min vs. 08:51 ± 02:57 min in the CE-MRA (p < 0.001). CONCLUSIONS: Superior image quality of the entire thoracic aorta, also regarding artifacts, can be achieved with native-SN-MRA, especially in motion prone segments, in addition to a shorter acquisition time.

Beyond Single-Cell Analysis of Metallodrugs by ICP-MS: Targeting Cellular Substructures.

Platinum compounds such as cisplatin (cisPt) embody the backbone of combination chemotherapy protocols against advanced lung cancer. However, their efficacy is primarily limited by inherent or acquired platinum resistance, the origin of which has not been fully elucidated yet, although of paramount interest. Using single cell inductively coupled plasma mass spectrometry (SC-ICP-MS), this study quantifies cisPt in single cancer cells and for the first time in isolated nuclei. A comparison of cisPt uptake was performed between a wild type (wt) cancer cell line and related resistant sublines. In both, resistant cells, wt cells, and their nuclei, cisPt uptake was measured at different incubation times. A lower amount of cisPt was found in resistant cell lines and their nuclei compared to wt cells. Moreover, the abundance of internalized cisPt decreased with increasing resistance. Interestingly, concentrations of cisPt found within the nuclei were higher than compared to cellular concentrations. Here, we show, that SC-ICP-MS allows precise and accurate quantification of metallodrugs in both single cells and cell organelles such as nuclei. These findings pave the way for future applications investigating the potency and efficacy of novel metallodrugs developed for cancer treatment.

1H HR-MAS NMR Based Metabolic Profiling of Lung Cancer Cells with Induced and De-Induced Cisplatin Resistance to Reveal Metabolic Resistance Adaptations.

Cisplatin (cisPt) is an important drug that is used against various cancers, including advanced lung cancer. However, drug resistance is still a major ongoing problem and its investigation is of paramount interest. Here, a high-resolution magic angle spinning (HR-MAS) NMR study is presented deciphering the metabolic profile of non-small cell lung cancer (NSCLC) cells and metabolic adaptations at different levels of induced cisPt-resistance, as well as in their de-induced counterparts (cells cultivated in absence of cisPt). In total, fifty-three metabolites were identified and quantified in the 1H-HR-MAS NMR cell spectra. Metabolic adaptations to cisPt-resistance were detected, which correlated with the degree of resistance. Importantly, de-induced cell lines demonstrated similar metabolic adaptations as the corresponding cisPt-resistant cell lines. Metabolites predominantly changed in cisPt resistant cells and their de-induced counterparts include glutathione and taurine. Characteristic metabolic patterns for cisPt resistance may become relevant as biomarkers in cancer medicine.

Ex vivo performance comparison of three percutaneous biopsy needle systems.

PURPOSE: The aim of this study is to identify the micro-mechanical characteristics that define biopsy performance in normal ex vivo animal organs. MATERIALS AND METHODS: Three biopsy systems with differences of needle external diameter, tray height and effective tray length were assessed. Sampling was performed in porcine liver and kidneys with commercially labelled 14G, 16G and 18G, using 2-cm throw needle systems. Five samples were obtained per needle size and per organ, and the experiment was repeated twice for a total of 90 biopsy cores. Samples were analysed and compared in terms of macroscopic aspect, sample length, weight and tissue architecture. RESULTS: The system with the longest effective needle tray (system A) has shown significant superiority (p < 0.001) versus the other systems regarding the mean weight of tissue obtained for all needle sizes. Furthermore, the 14G needle of system A has shown superiority regarding the number of portal spaces and the 16G regarding the length of kidney fragments obtained. CONCLUSION: The outcomes obtained with the different biopsy systems were not equal. The micro-mechanical characteristic that appears to influence the quantity and quality of the obtained tissue is the effective needle tray length and not the needle external diameter or the needle tray height. This information should be taken into account in the future design of biopsy needle systems, particularly when potentially used in the assessment of biomarkers and the characterisation of tumour micro-environment. KEY POINTS: • The amount of obtained tissue mass is not the same among percutaneous biopsy needle systems. • There are different micro-mechanical characteristics that condition the amount of obtained tissue. • The micro-mechanical characteristic that offers more tissue mass for the same calibre is the effective length of the needle tray.

Feasibility of cardiovascular magnetic resonance to detect oxygenation deficits in patients with multi-vessel coronary artery disease triggered by breathing maneuvers.

BACKGROUND: Hyperventilation with a subsequent breath-hold has been successfully used as a non-pharmacological vasoactive stimulus to induce changes in myocardial oxygenation. The purpose of this pilot study was to assess if this maneuver is feasible in patients with multi-vessel coronary artery disease (CAD), and if it is effective at detecting coronary artery stenosis > 50% determined by quantitative coronary angiography (QCA). METHODS: Twenty-six patients with coronary artery stenosis (QCA > 50% diameter stenosis) underwent a contrast-free cardiovascular magnetic resonance (CMR) exam in the time interval between their primary coronary angiography and a subsequent percutaneous coronary intervention (PCI, n = 24) or coronary artery bypass (CABG, n = 2) revascularization procedure. The CMR exam involved standard function imaging, myocardial strain analysis, T2 mapping, native T1 mapping and oxygenation-sensitive CMR (OS-CMR) imaging. During OS-CMR, participants performed a paced hyperventilation for 60s followed by a breath-hold to induce a vasoactive stimulus. Ten healthy subjects underwent the CMR protocol as the control group. RESULTS: All CAD patients completed the breathing maneuvers with an average breath-hold duration of 48 ± 23 s following hyperventilation and without any complications or adverse effects. In comparison to healthy subjects, CAD patients had a significantly attenuated global myocardial oxygenation response to both hyperventilation (- 9.6 ± 6.8% vs. -3.1 ± 6.5%, p = 0.012) and apnea (11.3 ± 6.1% vs. 2.1 ± 4.4%, p < 0.001). The breath-hold maneuver unmasked regional oxygenation differences in territories subtended by a stenotic coronary artery in comparison to remote territory within the same patient (0.5 ± 3.8 vs. 3.8 ± 5.3%, p = 0.011). CONCLUSION: Breathing maneuvers in conjunction with OS-CMR are clinically feasible in CAD patients. Furthermore, OS-CMR demonstrates myocardial oxygenation abnormalities in regional myocardium related to CAD without the use of pharmacologic vasodilators or contrast agents. A larger trial appears warranted for a better understanding of its diagnostic utility. TRIAL REGISTRATION: Clinical Trials Identifier: NCT02233634 , registered 8 September 2014.

How Precise Are Preinterventional Measurements Using Centerline Analysis Applications? Objective Ground Truth Evaluation Reveals Software-Specific Centerline Characteristics.

PURPOSE: To evaluate different centerline analysis applications using objective ground truth from realistic aortic aneurysm phantoms with precisely defined geometry and centerlines to overcome the lack of unknown true dimensions in previously published in vivo validation studies. METHODS: Three aortic phantoms were created using computer-aided design (CAD) software and a 3-dimensional (3D) printer. Computed tomography angiograms (CTAs) of phantoms and 3 patients were analyzed with 3 clinically approved and 1 research software application. The 3D centerline coordinates, intraluminal diameters, and lengths were validated against CAD ground truth using a dedicated evaluation software platform. RESULTS: The 3D centerline position mean error ranged from 0.7±0.8 to 2.9±2.5 mm between tested applications. All applications calculated centerlines significantly different from ground truth. Diameter mean errors varied from 0.5±1.2 to 1.1±1.0 mm among 3 applications, but exceeded 8.0±11.0 mm with one application due to an unsteady distortion of luminal dimensions along the centerline. All tested commercially available software tools systematically underestimated centerline total lengths by -4.6±0.9 mm to -10.4±4.3 mm (maximum error -14.6 mm). Applications with the highest 3D centerline accuracy yielded the most precise diameter and length measurements. CONCLUSION: One clinically approved application did not provide reproducible centerline-based analysis results, while another approved application showed length errors that might influence stent-graft choice and procedure success. The variety and specific characteristics of endovascular aneurysm repair planning software tools require scientific evaluation and user awareness.

Self Made Xeno-pericardial Aortic Tubes to Treat Native and Aortic Graft Infections.

OBJECTIVES: The most appropriate material for reconstruction of the aorta for native or graft infection remains a matter for debate. This study examines the mid-term outcome of patients and graft durability after in situ aortic reconstruction with self made bovine pericardial tube grafts. METHODS: This was a retrospective analysis of all patients who underwent in situ aortic reconstruction using self made bovine pericardial tube grafts between January 2008 and December 2015 at a tertiary referral centre. Peri-operative and mid-term outcomes including mortality and re-infection were analysed at the end of January 2017. Available follow-up imaging was reviewed to assess graft durability. RESULTS: Bovine pericardial aortic tube grafts were used in 35 patients (86% male) with a median age of 69 years (range 38-84) to reconstruct the ascending aorta or the aortic arch (7), the descending (7), the thoraco-abdominal (7), or the abdominal (14) aorta. Twelve patients (34%) were treated for infection of the native aorta and 23 (66%) for prosthetic graft infection. Twenty-two patients (63%) underwent emergency surgery. Thirty day mortality was 31% (n = 11). Additionally, six patients died during follow-up after a median of 33 months (range 3-70). For the remaining patients, mean follow-up was 48 months (± 26) with a mean Follow-Up Index of 0.98 ± 0.08. There were no readmissions or re-operations for re-infection or graft related complications. Follow-up imaging showed no signs of graft degeneration after a median of 15 months (range 3-68). CONCLUSIONS: Surgical treatment of native and aortic graft or endograft infection remains high risk. Self made bovine pericardial tube grafts for in situ reconstruction are a promising option offering many advantages. Despite high early mortality rates, early radiological and mid-term clinical results are good. Definitive eradication of the infection seems feasible after in situ insertion of xeno-pericardial material for aortic repair.

Dynamic Contrast-Enhanced Magnetic Resonance Imaging of Ocular Melanoma as a Tool to Predict Metastatic Potential.

PURPOSE: This study explores the capability of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to differentiate tumor characteristics of metastatic and nonmetastatic choroidal melanoma as a potential tool for patient management. MATERIALS AND METHODS: A total of 13 patients (69 ± 9 years) with choroidal melanoma were imaged using DCE-MRI on a 3-T MRI system with a 16-channel head coil. The Tofts 2-compartment model was chosen for quantification, and parameters K (the transfer constant from the blood plasma to the extracellular space) and Kep (the transfer constant from the extracellular space to the blood plasma) were calculated and compared. Metastasis was excluded by subsequent clinical work-up or confirmed by histology after targeted biopsy. RESULTS: Six patients were diagnosed with metastatic melanoma and 7 without. All orbital tumors were at least larger than 2 mm. A significant difference was identified in K between patients with (0.73 ± 0.18/min) and without (1.00 ± 0.21/min) metastatic melanoma (P = 0.03), whereas the difference was not significantly shown in Kep (2.58 ± 1.54/min of metastatic patients vs 2.98 ± 1.83/min of nonmetastatic patients, P = 0.67). CONCLUSIONS: Dynamic contrast-enhanced magnetic resonance imaging has the potential to differentiate orbital melanomas with metastatic and nonmetastatic spread. Thus, DCE-MRI has the potential to be an in vivo imaging technique to predict early which patients are prone to metastatic disease.

Single-center experience in the management of spontaneous isolated abdominal aortic dissection.

OBJECTIVE: This study aims to report the management of patients with spontaneous isolated dissection of the abdominal aorta (sIAAD). METHODS: A cohort of 18 consecutive patients (12 male, mean age 58 years) with sIAAD was treated between 1990 and 2009. Dissection was asymptomatic in ten and symptomatic in eight patients. Retrospective data analysis from patient charts was performed. Follow-up included clinical examination, ultrasound, and/or CT-angiography. Mean follow-up was 54 months (range 1-211). RESULTS: In total, eight out of 18 received invasive treatment. All asymptomatic patients initially underwent conservative treatment and surveillance. Spontaneous false lumen thrombosis occurred in four (40 %), and three patients showed relevant aneurysmatic progression and underwent elective invasive treatment (open n = 2, endovascular n = 1), representing a crossover rate of 30 %. Late mortality was 20 % (n = 2) in this group. In symptomatic patients, five underwent urgent treatment due to persistent abdominal or back pain (n = 4) or contained rupture (n = 1); one was treated for claudication. The remaining two patients presented with irreversible spinal cord ischemia and were treated conservatively. Three patients were treated by open surgery and three by endovascular interventions (two stentgrafts, one Palmaz XXL stent). Early and late morbidity and mortality was 0 % in this group. There were no reinterventions CONCLUSION: The majority of patients with sIADD require invasive treatment, with EVAR being the preferable treatment option today. In asymptomatic IADD, primary surveillance is justifiable, but close surveillance due to expansion is necessary.

Treatment allocation in hepatocellular carcinoma: Assessment of the BCLC algorithm.

BACKGROUND AND AIMS: The Barcelona Clinic Liver Cancer (BCLC) staging system is the algorithm most widely used to manage patients with hepatocellular carcinoma (HCC). We aimed to investigate the extent to which the BCLC recommendations effectively guide clinical practice and assess the reasons for any deviation from the recommendations. MATERIAL AND METHODS: The first-line treatments assigned to patients included in the prospective Bern HCC cohort were analyzed. RESULTS: Among 223 patients included in the cohort, 116 were not treated according to the BCLC algorithm. Eighty percent of the patients in BCLC stage 0 (very early HCC) and 60% of the patients in BCLC stage A (early HCC) received recommended curative treatment. Only 29% of the BCLC stage B patients (intermediate HCC) and 33% of the BCLC stage C patients (advanced HCC) were treated according to the algorithm. Eighty-nine percent of the BCLC stage D patients (terminal HCC) were treated with best supportive care, as recommended. In 98 patients (44%) the performance status was disregarded in the stage assignment. CONCLUSION: The management of HCC in clinical practice frequently deviates from the BCLC recommendations. Most of the curative therapy options, which have well-defined selection criteria, were allocated according to the recommendations, while the majority of the palliative therapy options were assigned to patients with tumor stages not aligned with the recommendations. The only parameter which is subjective in the algorithm, the performance status, is also the least respected.

Frequency of abdominal aortic expansion after thoracic endovascular repair of type B aortic dissection.

PURPOSE: To determine abdominal aortic expansion after thoracic endovascular aortic repair (TEVAR) in patients with aortic dissection type B and 36 months minimum follow-up. METHODS: Retrospective study of 18 TEVAR patients with follow-up >36 months. Abdominal aortic diameters at celiac trunk (location B) and infrarenal aorta (location C) were recorded on the first and last imaging after TEVAR. False lumen thrombosis was determined at level of endograft (A) and at B and C. Aortic expansion was defined as diameter increase of 5 mm or 15%. Correlation analyses were performed to investigate potential determinants of expansion. RESULTS: Median follow-up was 75.2 months. Sixteen of 18 patients (88.9%) demonstrated abdominal expansion. Mean expansion was 9.9 ± 6.1 mm at B and 11.7 ± 6.5 mm at C, without a difference between acute and chronic dissections. Critical diameters of 55 mm were reached in two patients treated for chronic dissection (11.1%). Annual diameter increase was significantly greater at locations with baseline diameters >30 mm (2.1 ± 1.1 mm vs. 1.0 ± 0.6 mm, p = 0.009). Baseline diameters were greater in patients with chronic dissections. CONCLUSION: Abdominal aortic expansion can be frequently recognized after TEVAR for aortic dissection type B and occurs independently from thoracic false lumen thrombosis. Clinical significant abdominal aortic expansion may occur more frequently in patients treated with TEVAR for chronic dissection.

Aortic morphometry at endograft position as assessed by 3D image analysis affects risk of type I endoleak formation after TEVAR.

PURPOSE: The purpose of this study was to identify morphologic factors affecting type I endoleak formation and bird-beak configuration after thoracic endovascular aortic repair (TEVAR). METHODS: Computed tomography (CT) data of 57 patients (40 males; median age, 66 years) undergoing TEVAR for thoracic aortic aneurysm (34 TAA, 19 TAAA) or penetrating aortic ulcer (n = 4) between 2001 and 2010 were retrospectively reviewed. In 28 patients, the Gore TAG® stent-graft was used, followed by the Medtronic Valiant® in 16 cases, the Medtronic Talent® in 8, and the Cook Zenith® in 5 cases. Proximal landing zone (PLZ) was in zone 1 in 13, zone 2 in 13, zone 3 in 23, and zone 4 in 8 patients. In 14 patients (25%), the procedure was urgent or emergent. In each case, pre- and postoperative CT angiography was analyzed using a dedicated image processing workstation and complimentary in-house developed software based on a 3D cylindrical intensity model to calculate aortic arch angulation and conicity of the landing zones (LZ). RESULTS: Primary type Ia endoleak rate was 12% (7/57) and subsequent re-intervention rate was 86% (6/7). Left subclavian artery (LSA) coverage (p = 0.036) and conicity of the PLZ (5.9 vs. 2.6 mm; p = 0.016) were significantly associated with an increased type Ia endoleak rate. Bird-beak configuration was observed in 16 patients (28%) and was associated with a smaller radius of the aortic arch curvature (42 vs. 65 mm; p = 0.049). Type Ia endoleak was not associated with a bird-beak configuration (p = 0.388). Primary type Ib endoleak rate was 7% (4/57) and subsequent re-intervention rate was 100%. Conicity of the distal LZ was associated with an increased type Ib endoleak rate (8.3 vs. 2.6 mm; p = 0.038). CONCLUSIONS: CT-based 3D aortic morphometry helps to identify risk factors of type I endoleak formation and bird-beak configuration during TEVAR. These factors were LSA coverage and conicity within the landing zones for type I endoleak formation and steep aortic angulation for bird-beak configuration.

State-of-the-art aortic imaging: Part II - applications in transcatheter aortic valve replacement and endovascular aortic aneurysm repair.

Transcatheter aortic valve replacement (TAVR) as well as thoracic and abdominal endovascular aortic repair (TEVAR and EVAR) rely on accurate pre- and postprocedural imaging. This review article discusses the application of imaging, including preprocedural assessment and measurements as well as postprocedural imaging of complications. Furthermore, the exciting perspective of computational fluid dynamics (CFD) based on cross-sectional imaging is presented. TAVR is a minimally invasive alternative for treatment of aortic valve stenosis in patients with high age and multiple comorbidities who cannot undergo traditional open surgical repair. Given the lack of direct visualization during the procedure, pre- and peri-procedural imaging forms an essential part of the intervention. Computed tomography angiography (CTA) is the imaging modality of choice for preprocedural planning. Routine postprocedural follow-up is performed by echocardiography to confirm treatment success and detect complications. EVAR and TEVAR are minimally invasive alternatives to open surgical repair of aortic pathologies. CTA constitutes the preferred imaging modality for both preoperative planning and postoperative follow-up including detection of endoleaks. Magnetic resonance imaging is an excellent alternative to CT for postoperative follow-up, and is especially beneficial for younger patients given the lack of radiation. Ultrasound is applied in screening and postoperative follow-up of abdominal aortic aneurysms, but cross-sectional imaging is required once abnormalities are detected. Contrast-enhanced ultrasound may be as sensitive as CTA in detecting endoleaks.

Uptake of Gadolinium-Based Contrast Agents by Blood Cells During Contrast-Enhanced MRI Examination.

OBJECTIVES: Gadolinium-based contrast agents (GBCAs) are routinely used in magnetic resonance imaging (MRI) examinations. However, there is limited knowledge about the interaction with and distribution of the drug in human cells. This lack of knowledge is surprising, given that the first interaction of the drug occurs with blood cells. Moreover, recent studies reported gadolinium (Gd) deposition within organs, such as the brain. Hence, this study is aiming to determine the uptake of GBCA in blood cells of patients undergoing contrast-enhanced MRI (ce-MRI) examination. MATERIALS AND METHODS: Human blood was exposed to either gadoterate meglumine (Gd-DOTA) or Eu-DOTA in vitro or was collected from patients undergoing ce-MRI with Gd-DOTA. Uptake of contrast agents (CAs) by blood cells was quantified by Gd measurements using single-cell inductively coupled plasma mass spectrometry (SC-ICP-MS) or, to confirm Gd-DOTA uptake, by a complementary method using Eu-DOTA by time-resolved fluorescence spectroscopy, respectively. RESULTS: Uptake of Gd-DOTA or Eu-DOTA into white blood cells (WBCs) ex vivo was detectable by SC-ICP-MS and time-resolved fluorescence spectroscopy. The intracellular concentrations were estimated to be in the range of 1-3 µM. However, no CA uptake into erythrocytes was detected with either method. In total, 42 patients between 30 and 84 years old (24 men, 18 women) were enrolled. White blood cells' uptake of Gd was measured by SC-ICP-MS. Isolated WBCs from patients who underwent ce-MRI examination showed substantial Gd uptake; however, the studied patient group showed an inhomogeneous distribution of Gd uptake. Measurements immediately after MRI examination indicated 21-444 attogram/WBC, corresponding to an intracellular Gd concentration in the range from 0.2 to 5.5 µM. CONCLUSIONS: This study confirms the ex vivo uptake of GBCA by WBCs and provides the first evidence that GBCA is indeed taken up by WBCs in vivo by patients undergoing ce-MRI examination. However, the observed Gd uptake in WBCs does not follow a log-normal distribution commonly observed in the fields of environmental studies, biology, and medicine. Whether cellular uptake of GBCA is linked to the observed deposition of Gd remains unclear. Therefore, studying the interaction between GBCA and human cells may clarify crucial questions about the effects of Gd on patients after MRI examinations.

Direct comparison of whole heart quantifications between different retrospective and prospective gated 4D flow CMR acquisitions.

Introduction: 4D flow cardiovascular magnetic resonance (CMR) is a versatile technique to non-invasively assess cardiovascular hemodynamics. With developing technology, choice in sequences and acquisition parameters is expanding and it is important to assess if data acquired with these different variants can be directly compared, especially when combining datasets within research studies. For example, sequences may allow a choice in gating techniques or be limited to one method, yet there is not a direct comparison investigating how gating selection impacts quantifications of the great vessels, semilunar and atrioventricular valves and ventricles. Thus, this study investigated if quantifications across the heart from contemporary 4D flow sequences are comparable between two commonly used 4D flow sequences reliant on different ECG gating techniques. Methods: Forty participants (33 healthy controls, seven patients with coronary artery disease and abnormal diastolic function) were prospectively recruited into a single-centre observational study to undergo a 3T-CMR exam. Two acquisitions, a k-t GRAPPA 4D flow with prospective gating (4Dprosp) and a modern compressed sensing 4D flow with retrospective gating (4Dretro), were acquired in each participant. Images were analyzed for volumes, flow rates and velocities in the vessels and four valves, and for biventricular kinetic energy and flow components. Data was compared for group differences with paired t-tests and for agreement with Bland-Altman and intraclass correlation (ICC). Results: Measurements primarily occurring during systole of the great vessels, semilunar valves and both left and right ventricles did not differ between acquisition types (p > 0.05 from t-test) and yielded good to excellent agreement (ICC: 0.75-0.99). Similar findings were observed for the majority of parameters dependent on early diastole. However, measurements occurring in late diastole or those reliant on the entire-cardiac cycle such as flow component volumes along with diastolic kinetic energy values were not similar between 4Dprosp and 4Dretro acquisitions resulting in poor agreement (ICC < 0.50). Discussion: Direct comparison of measurements between two different 4D flow acquisitions reliant on different gating methods demonstrated systolic and early diastolic markers across the heart should be compatible when comparing these two 4D flow sequences. On the other hand, late diastolic and intraventricular parameters should be compared with caution.

A patient-specific study of type-B aortic dissection: evaluation of true-false lumen blood exchange.

BACKGROUND: Aortic dissection is a severe pathological condition in which blood penetrates between layers of the aortic wall and creates a duplicate channel - the false lumen. This considerable change on the aortic morphology alters hemodynamic features dramatically and, in the case of rupture, induces markedly high rates of morbidity and mortality. METHODS: In this study, we establish a patient-specific computational model and simulate the pulsatile blood flow within the dissected aorta. The k-ω SST turbulence model is employed to represent the flow and finite volume method is applied for numerical solutions. Our emphasis is on flow exchange between true and false lumen during the cardiac cycle and on quantifying the flow across specific passages. Loading distributions including pressure and wall shear stress have also been investigated and results of direct simulations are compared with solutions employing appropriate turbulence models. RESULTS: Our results indicate that (i) high velocities occur at the periphery of the entries; (ii) for the case studied, approximately 40% of the blood flow passes the false lumen during a heartbeat cycle; (iii) higher pressures are found at the outer wall of the dissection, which may induce further dilation of the pseudo-lumen; (iv) highest wall shear stresses occur around the entries, perhaps indicating the vulnerability of this region to further splitting; and (v) laminar simulations with adequately fine mesh resolutions, especially refined near the walls, can capture similar flow patterns to the (coarser mesh) turbulent results, although the absolute magnitudes computed are in general smaller. CONCLUSIONS: The patient-specific model of aortic dissection provides detailed flow information of blood transport within the true and false lumen and quantifies the loading distributions over the aorta and dissection walls. This contributes to evaluating potential thrombotic behavior in the false lumen and is pivotal in guiding endovascular intervention. Moreover, as a computational study, mesh requirements to successfully evaluate the hemodynamic parameters have been proposed.