Current surgical approach: Extracranial malignant germ cell tumors.

Germ cell tumors (GCT) are a complex, heterogeneous collection of tumors that may present in either gonadal or extragonadal sites. They consist of a variety of benign and malignant histologies that can occur at several locations throughout the body. An important component of treatment is surgical resection, and while the key components of resection are site specific, the universal goals of GCT resection include the complete resection of tumor without violating the tumor capsule, while preserving function of surrounding organs, minimizing morbidity, and assessing for regional spread.

A Near Miss and Salvage Management of Aortoesophageal Fistula Secondary to Cell Battery Ingestion.

We report a case of an infant surviving aortoesophageal fistula secondary to lithium cell battery ingestion. In the setting of a delayed vascular complication, computed tomography and magnetic resonance imaging are essential to establishing the correct diagnosis and surgical management. Management of children after battery ingestion must be guided by a high index of clinical suspicion.

The future of paediatric and adolescent gynaecology in Europe.

Paediatric and Adolescent Gynaecology (PAG) is a subspecialty under the umbrella of Obstetrics and Gynaecology but linked to other branches of medicine including Paediatrics, Surgery, Endocrinology and Urology. Therefore future developments in clinical care and education requires a multidisciplinary approach combining aspects of all the above medical specialties, and also with inputs from Public Health, Genetics, Radiology and Psychology. A multidisciplinary collaboration among different specialists is as important as the establishment and adoption of standards in education, training and management. PAG in Europe has evolved from its first steps and it is still growing with the aim of providing increasing protection of the gynaecological and reproductive health of female children and adolescents. In fact, without proper advice and care, inappropriate management of gynaecological issues in childhood and adolescence can be expected to have significant repercussions throughout later years, and into adulthood. The aim of this third paper in this mini-symposium is to explore how PAG should develop in Europe in the near future.

Glutathione S-transferase (GST) polymorphism could be an early marker in the development of polycystic ovary syndrome (PCOS) - an insight from non-obese and non-insulin resistant adolescents.

INTRODUCTION: It has been supposed that endocrine disturbances might be responsible for polycystic ovary syndrome (PCOS)-associated oxida-tive stress, with special emphasis on hyperandrogenism. Considering the potential relationship between hyperandrogenism and increased free radical production, parameters of oxidative stress were determined in non-obese normoinsulinemic adolescent girls newly diagnosed with PCOS. MATERIALS AND METHODS: Nitrotyrosine, thiol group concentrations, glutathione peroxidase, and superoxide dismutase activities were determined under fasting conditions and during oral glucose tolerance test (OGTT) in 35 PCOS patients and 17 controls. Insulin resistance was assessed by the homeostasis model (HOMA-IR), HOMA ß, insulinogenic index (IGI), Matsuda insulin sensitivity index (ISI), and AUC for glucose. Glutathione S-transferases (GSTs) polymorphisms were determined by PCR. RESULTS: Under fasting conditions, no significant difference of oxidative stress parameters was found between PCOS and controls. Acute hyperglycaemia during OGTT induced significant alteration in parameters of oxidative protein damage in PCOS patients. Alteration in nitrotyrosine concentrations correlated with testosterone, DHEAS, androstenediones, FAI, and LH, while changes in thiol groups cor-related with DHEAS. Significant inverse association was found between LH and ISI, as well as AUC glucose and thiol groups. PCOS girls, carriers of GSTM1-null genotype, had significantly lower testosterone in comparison to ones with GSTM1-active genotype. CONCLUSIONS: PCOS girls exhibited high free radical production together with unchanged antioxidant enzymatic capacity, independently from obesity and insulin resistance. Based on associations between oxidative stress parameters and testosterone, DHEAS, and androsten-edione, it can be suggested that increased free radical production, probably as a consequence of hyperandrogenaemia, is an early event in the development of PCOS.

Beneficial long term effect of a phosphodiesterase-5-inhibitor in cirrhotic portal hypertension: A case report with 8 years follow-up.

Non-selective beta-blockers are the mainstay of medical therapy for portal hypertension in liver cirrhosis. Inhibitors of phosphodiesterase-5 (PDE-5-inhibitors) reduce portal pressure in the acute setting by > 10% which may suggest a long-term beneficial effect. Currently, there is no available data on long-term treatment of portal hypertension with PDE-5-inhibitors. This case of a patient with liver cirrhosis secondary to autoimmune liver disease with episodes of bleeding from esophageal varices is the first documented case in which a treatment with a PDE-5-inhibitor for eight years was monitored. In the acute setting, the PDE-5-inhibitor Vardenafil lowered portal pressure by 13%. The portal blood flow increased by 28% based on Doppler sonography and by 16% using MRI technique. As maintenance medication the PDE-5-inhibitor Tadalafil was used for eight consecutive years with comparable effects on portal pressure and portal blood flow. There were no recurrence of bleeding and no formation of new varices. Influencing the NO-pathway by the use of PDE-5 inhibitors may have long-term beneficial effects in compensated cirrhosis.

Reproducibility of 24-h heart rate variability in children.

BACKGROUND: Over the last decades, time domain heart rate (HR) variability analysis has been explored in different pediatric clinical settings to obtain information on the cardiac autonomic tone. However, the consistency over time of 24 h time domain HRV measurements in children is not well-known. METHODS: We investigated the reproducibility of 24 h HRV time-domain indices (1 day apart), from 39 healthy children (9.5 ± 5.3 years, 56.4% girls). The parameters analysed included: standard deviation of all the adjacent NN intervals, standard deviation of the averages of NN intervals (the intervals between normal R-peaks) in all 5-min segments, and square root of the mean of the sum of the squares of the differences between adjacent NN intervals, uncorrected and corrected for HR. Reproducibility between two 24-h ECG recordings was evaluated by intraclass correlation coefficients, standard error of measurement, coefficients of variation and Bland-Altman plots. RESULTS: For the analyzed time-domain indices, standard deviation of all the adjacent NN intervals corrected for HR showed best reproducibility with the highest intraclass correlation coefficient (0.987), the lowest coefficients of variation (5.5%) and the best level of agreement between two recordings as assessed by Bland-Altman plots. CONCLUSIONS: Our results indicate that the standard deviation of all the adjacent NN intervals corrected for the HR parameter obtained from 24-h ambulatory recordings in children is consistent and reproducible over time, thus allowing reliable identification of cardiac autonomic tone in this age group.

JOURNAL CLUB: Four-Dimensional Flow MRI-Based Splenic Flow Index for Predicting Cirrhosis-Associated Hypersplenism.

OBJECTIVE: The objective of this study is to evaluate the ability of spleen volume, blood flow, and an index incorporating multiple measures to predict cirrhosis-associated hypersplenism. MATERIALS AND METHODS: A total of 39 patients (14 women and 25 men; mean [± SD] age, 52 ± 10 years) with cirrhosis and sequelae of portal hypertension underwent 4D flow MRI and anatomic 3-T MRI performed before and after contrast administration. Unenhanced 4D flow MRI was used to assess abdominal hemodynamics, and splenic volumes were measured on T1-weighted gradient-recalled echo MRI. Relationships among demographic characteristics, blood component counts, splenic volume, arterial flow, venous flow, and the percentage of shunted portal flow were assessed in 29 consecutive patients (i.e., the derivation group), to develop a splenic flow index. This index was assessed along with splenic volume and blood flow alone in 10 additional consecutive patients (i.e., the validation group) via ROC curve analysis, to identify platelet counts of less than 50 × 103 cells/µL, leukocyte counts of less than 3.0 × 103 cells/µL, or both. RESULTS: In the derivation cohort (platelet count, 129 ± 76 × 103 cells/µL), splenic volume, arterial flow, venous flow, and the percentage of shunted portal flow were inversely correlated with platelet counts (ρ = -0.68, -0.68, -0.56, and -0.36, respectively; p < 0.05). Adding splenic volume to arterial flow and the product of venous flow and the percentage of shunted portal flow indexed to the body surface area yielded superior correlations with platelet counts, leukocyte counts, and the degree of severity of hypersplenism (ρ = -0.75, -0.48, and -0.75, respectively; p ≤ 0.001) and predicted severe hypersplenism (sensitivity, 100%; specificity, 100%) in the validation cohort (platelet count, 93 ± 71 × 103 cells/µL). CONCLUSION: A splenic flow index that incorporates both splenic volume and blood flow is a better indicator of hypersplenism than is splenic volume alone.

Ovarian Preservation from Tumors and Torsions in Girls: Prospective Diagnostic Study.

STUDY OBJECTIVE: To develop a new decision tree system (DTS) for the management of adnexal masses in prepubertal and adolescent girls, aimed to improve the distinction between benign and malignant masses, help preserve affected ovaries during surgery, and reduce the rate of surgical management of uncomplicated functional ovarian cysts. DESIGN: A prospective diagnostic study using clinical and ultrasound data collected for all patients younger than 19 years of age with adnexal masses managed between 2006 and 2015. SETTING: Mother and Child Health Institute of Serbia 'Dr Vukan Cupic' (Belgrade, Serbia). PARTICIPANTS: Patients (N = 1499) with adnexal masses, of whom 318 were surgically treated. INTERVENTIONS AND MAIN OUTCOME MEASURES: Ultrasonographic characteristics (Ueland's Morphology Index [MI] and the ovarian crescent sign [OCS]). Patients were managed expectantly or surgically, in line with 3 rules of the DTS. Rule 1: asymptomatic patients having a mass with MI of 4 or less and OCS present, were managed expectantly. Rule 2 (emergency): malignancy was suspected if the MI was 7 or more and no edema of the OCS was present. Rule 3 (nonemergency): malignancy was suspected if the OCS was absent and MI was 5 or more. The diagnostic accuracy was assessed using sensitivity and specificity (P < .05). RESULTS: No malignancy was found in the group of 1236 patients selected according to the DTS rule 1. Torsion was confirmed in 36% of surgically treated masses (n = 115). The OCS was present in 96% of benign masses in the non-emergency group (n = 149) and in three with microscopic malignancy. In predicting malignancy, the DTS (rules 2 and 3) showed a sensitivity of 93 (95% confidence interval [C.I.]: 82-98); and a specificity of 97 (C.I.: 95-99). Ovarian tissue was preserved from benign (n = 254, 93%) and malignant tumors (n = 3, 7%). Only five (2%) uncomplicated ovarian cysts were surgically treated. CONCLUSION: The DTS with 3 rules is a very accurate diagnostic tool in the differentiation between benign and malignant ovarian masses. The DTS rule 1 reduces the number of surgical procedures on functional cysts, rules 2 and 3 are very useful in choosing the optimal treatment of adnexal masses, whether or not they are twisted.

Four-dimensional flow magnetic resonance imaging in cirrhosis.

Since its introduction in the 1970's, magnetic resonance imaging (MRI) has become a standard imaging modality. With its broad and standardized application, it is firmly established in the clinical routine and an essential element in cardiovascular and abdominal imaging. In addition to sonography and computer tomography, MRI is a valuable tool for diagnosing cardiovascular and abdominal diseases, for determining disease severity, and for assessing therapeutic success. MRI techniques have improved over the last few decades, revealing not just morphologic information, but functional information about perfusion, diffusion and hemodynamics as well. Four-dimensional (4D) flow MRI, a time-resolved phase contrast-MRI with three-dimensional (3D) anatomic coverage and velocity encoding along all three flow directions has been used to comprehensively assess complex cardiovascular hemodynamics in multiple regions of the body. The technique enables visualization of 3D blood flow patterns and retrospective quantification of blood flow parameters in a region of interest. Over the last few years, 4D flow MRI has been increasingly performed in the abdominal region. By applying different acceleration techniques, taking 4D flow MRI measurements has dropped to a reasonable scanning time of 8 to 12 min. These new developments have encouraged a growing number of patient studies in the literature validating the technique's potential for enhanced evaluation of blood flow parameters within the liver's complex vascular system. The purpose of this review article is to broaden our understanding of 4D flow MRI for the assessment of liver hemodynamics by providing insights into acquisition, data analysis, visualization and quantification. Furthermore, in this article we highlight its development, focussing on the clinical application of the technique.

Contraception for adolescents after abortion.

INTRODUCTION: Preventing repeated unplanned pregnancy among adolescents is still a challenge because many of them fail to use effective contraception after abortion. OBJECTIVE: To review currently recommended options of methods and counselling for effective prevention of repeat pregnancies in adolescents. METHODS: Review of the literature that was identified through the Medline, ScienceDirect, Google and Popline databases and relevant expert opinions. RESULTS: Counselling needs to be adapted to the needs, values and lifestyle of adolescents. The best results are achieved with nondirective or active contraceptive counselling, followed by regular check-ups and cautious and attentive approach in the management of doubts, prejudices and side effects related to the contraceptive chosen. Adolescents should initiate contraception immediately after abortion: the motivation for choosing an efficacious method is highest at that time; resumption of ovulation following induced abortion occurs on average after three weeks; more than half of these girls will resume sexual activity within two weeks after pregnancy termination. Long-acting reversible contraception use during adolescence is safe and most effective. However, achieving a high long-term continuation rate is especially challenging in adolescents; this is due to developmental and environmental characteristics that influence their contraceptive behaviour. CONCLUSION: Adolescents should immediately after abortion initiate a reliable contraceptive method, preferably one whose efficacy is not user-dependent. Providing an appropriate health care would contribute to achieving continuity in the prevention of repeat pregnancy.

Improved respiratory navigator gating for thoracic 4D flow MRI.

BACKGROUND: Thoracic and abdominal 4D flow MRI is typically acquired in combination with navigator respiration control which can result in highly variable scan efficiency (Seff) and thus total scan time due to inter-individual variability in breathing patterns. The aim of this study was to test the feasibility of an improved respiratory control strategy based on diaphragm navigator gating with fixed Seff, respiratory driven phase encoding, and a navigator training phase. METHODS: 4D flow MRI of the thoracic aorta was performed in 10 healthy subjects at 1.5T and 3T systems for the in-vivo assessment of aortic time-resolved 3D blood flow velocities. For each subject, four 4D flow scans (1: conventional navigator gating, 2-4: new implementation with fixed Seff =60%, 80% and 100%) were acquired. Data analysis included semi-quantitative evaluation of image quality of the 4D flow magnitude images (image quality grading on a four point scale), 3D segmentation of the thoracic aorta, and voxel-by-voxel comparisons of systolic 3D flow velocity vector fields between scans. RESULTS: Conventional navigator gating resulted in variable Seff=74±13% (range=56%-100%) due to inter-individual variability of respiration patterns. For scans 2-4, the new navigator implementation was able to achieve predictable total scan times with stable Seff, only depending on heart rate. Semi- and fully quantitative analysis of image quality in 4D flow magnitude images was similar for the new navigator scheme compared to conventional navigator gating. For aortic systolic 3D velocities, good agreement was found between all new navigator settings (scan 2-4) with the conventional navigator gating (scan 1) with best performance for Seff=80% (mean difference=-0.01 m/s; limits of agreement=0.23 m/s, Pearson's ρ=0.89, p<0.001). No significant differences for image quality or 3D systolic velocities were found for 1.5T compared to 3T. CONCLUSIONS: The findings of this study demonstrate the feasibility of the new navigator scheme to acquire 4D flow data with more predictable scan time while maintaining image quality and 3D velocity information, which may prove beneficial for clinical applications.

Effect of TIPS placement on portal and splanchnic arterial blood flow in 4-dimensional flow MRI.

OBJECTIVES: To assess changes in portal and splanchnic arterial haemodynamics in patients undergoing transjugular intrahepatic portosystemic shunt (TIPS) using four-dimensional (4D) flow MRI, a non-invasive, non-contrast imaging technique. METHODS: Eleven patients undergoing TIPS implantation were enrolled. K-t GRAPPA accelerated non-contrast 4D flow MRI of the liver vasculature was applied with acceleration factor R = 5 at 3Tesla. Flow analysis included three-dimensional (3D) blood flow visualization using time-resolved 3D particle traces and semi-quantitative flow pattern grading. Quantitative evaluation entailed peak velocities and net flows throughout the arterial and portal venous (PV) systems. MRI measurements were taken within 24 h before and 4 weeks after TIPS placement. RESULTS: Three-dimensional flow visualization with 4D flow MRI revealed good image quality with minor limitations in PV flow. Quantitative analysis revealed a significant increase in PV flow (562 ± 373 ml/min before vs. 1831 ± 965 ml/min after TIPS), in the hepatic artery (176 ± 132 ml/min vs. 354 ± 140 ml/min) and combined flow in splenic and superior mesenteric arteries (770 ml/min vs. 1064 ml/min). Shunt-flow assessment demonstrated stenoses in two patients confirmed and treated at TIPS revision. CONCLUSIONS: Four-dimensional flow MRI might have the potential to give new information about the effect of TIPS placement on hepatic perfusion. It may explain some unexpected findings in clinical observation studies. KEY POINTS: • 4D flow MRI, a non-invasive, non-contrast imaging technique, is feasible after TIPS. • Provides visualization and quantification of hepatic arterial, portal venous, collateral and TIPS haemodynamics. • Better understanding of liver blood flow changes after TIPS and patient management.

K-t GRAPPA-accelerated 4D flow MRI of liver hemodynamics: influence of different acceleration factors on qualitative and quantitative assessment of blood flow.

OBJECTIVE: We sought to evaluate the feasibility of k-t parallel imaging for accelerated 4D flow MRI in the hepatic vascular system by investigating the impact of different acceleration factors. MATERIALS AND METHODS: k-t GRAPPA accelerated 4D flow MRI of the liver vasculature was evaluated in 16 healthy volunteers at 3T with acceleration factors R = 3, R = 5, and R = 8 (2.0 × 2.5 × 2.4 mm(3), TR = 82 ms), and R = 5 (TR = 41 ms); GRAPPA R = 2 was used as the reference standard. Qualitative flow analysis included grading of 3D streamlines and time-resolved particle traces. Quantitative evaluation assessed velocities, net flow, and wall shear stress (WSS). RESULTS: Significant scan time savings were realized for all acceleration factors compared to standard GRAPPA R = 2 (21-71 %) (p < 0.001). Quantification of velocities and net flow offered similar results between k-t GRAPPA R = 3 and R = 5 compared to standard GRAPPA R = 2. Significantly increased leakage artifacts and noise were seen between standard GRAPPA R = 2 and k-t GRAPPA R = 8 (p < 0.001) with significant underestimation of peak velocities and WSS of up to 31 % in the hepatic arterial system (p <0.05). WSS was significantly underestimated up to 13 % in all vessels of the portal venous system for k-t GRAPPA R = 5, while significantly higher values were observed for the same acceleration with higher temporal resolution in two veins (p < 0.05). CONCLUSION: k-t acceleration of 4D flow MRI is feasible for liver hemodynamic assessment with acceleration factors R = 3 and R = 5 resulting in a scan time reduction of at least 40 % with similar quantitation of liver hemodynamics compared with GRAPPA R = 2.

4D flow imaging with MRI.

Magnetic resonance imaging (MRI) has become an important tool for the clinical evaluation of patients with cardiovascular disease. Since its introduction in the late 1980s, 2-dimensional phase contrast MRI (2D PC-MRI) has become a routine part of standard-of-care cardiac MRI for the assessment of regional blood flow in the heart and great vessels. More recently, time-resolved PC-MRI with velocity encoding along all three flow directions and three-dimensional (3D) anatomic coverage (also termed '4D flow MRI') has been developed and applied for the evaluation of cardiovascular hemodynamics in multiple regions of the human body. 4D flow MRI allows for the comprehensive evaluation of complex blood flow patterns by 3D blood flow visualization and flexible retrospective quantification of flow parameters. Recent technical developments, including the utilization of advanced parallel imaging techniques such as k-t GRAPPA, have resulted in reasonable overall scan times, e.g., 8-12 minutes for 4D flow MRI of the aorta and 10-20 minutes for whole heart coverage. As a result, the application of 4D flow MRI in a clinical setting has become more feasible, as documented by an increased number of recent reports on the utility of the technique for the assessment of cardiac and vascular hemodynamics in patient studies. A number of studies have demonstrated the potential of 4D flow MRI to provide an improved assessment of hemodynamics which might aid in the diagnosis and therapeutic management of cardiovascular diseases. The purpose of this review is to describe the methods used for 4D flow MRI acquisition, post-processing and data analysis. In addition, the article provides an overview of the clinical applications of 4D flow MRI and includes a review of applications in the heart, thoracic aorta and hepatic system.

Reproducibility study of four-dimensional flow MRI of arterial and portal venous liver hemodynamics: influence of spatio-temporal resolution.

PURPOSE: To evaluate influence of variation in spatio-temporal resolution and scan-rescan reproducibility on three-dimensional (3D) visualization and quantification of arterial and portal venous (PV) liver hemodynamics at four-dimensional (4D) flow MRI. METHODS: Scan-rescan reproducibility of 3D hemodynamic analysis of the liver was evaluated in 10 healthy volunteers using 4D flow MRI at 3T with three different spatio-temporal resolutions (2.4 × 2.0 × 2.4 mm(3), 61.2 ms; 2.5 × 2.0 × 2.4 mm(3), 81.6 ms; 2.6 × 2.5 × 2.6 mm(3), 80 ms) and thus different total scan times. Qualitative flow analysis used 3D streamlines and time-resolved particle traces. Quantitative evaluation was based on maximum and mean velocities, flow volume, and vessel lumen area in the hepatic arterial and PV systems. RESULTS: 4D flow MRI showed good interobserver variability for assessment of arterial and PV liver hemodynamics. 3D flow visualization revealed limitations for the left intrahepatic PV branch. Lower spatio-temporal resolution resulted in underestimation of arterial velocities (mean 15%, P < 0.05). For the PV system, hemodynamic analyses showed significant differences in the velocities for intrahepatic portal vein vessels (P < 0.05). Scan-rescan reproducibility was good except for flow volumes in the arterial system. CONCLUSION: 4D flow MRI for assessment of liver hemodynamics can be performed with low interobserver variability and good reproducibility. Higher spatio-temporal resolution is necessary for complete assessment of the hepatic blood flow required for clinical applications.

k-t GRAPPA accelerated four-dimensional flow MRI in the aorta: effect on scan time, image quality, and quantification of flow and wall shear stress.

PURPOSE: The purpose of this study was to evaluate the utility of k-t parallel imaging for accelerating aortic four-dimensional (4D)-flow MRI. The aim was to systematically investigate the impact of different acceleration factors and number of coil elements on acquisition time, image quality and quantification of hemodynamic parameters. METHODS: k-t accelerated 4D-flow MRI (spatial/temporal resolution = 2.1 × 2.5 × 2.5 mm/40.0 ms) was acquired in 10 healthy volunteers with acceleration factors R = 3, 5, and 8 using 12- and 32-channel receiver coils. Results were compared with conventional parallel imaging (GRAPPA [generalized autocalibrating partial parallel acquisition], R = 2). Data analysis included radiological grading of three-dimensional blood flow visualization quality as well as quantification of blood flow, velocities and wall shear stress (WSS). RESULTS: k-t GRAPPA significantly reduced scan time by 28%, 54%, and 68%, for R = 3, 5, and 8, respectively, while maintaining image quality as demonstrated by overall similar image quality grading. Significant differences in peak WSS (diff12ch = -5.9%, diff32ch = 18.5%) and mean WSS (diff32ch = 13.9%) were found at the descending aorta for both receiver coils for R = 5 (PWSS < 0.04). Peak velocity differed for R=8 at the aortic root (-7.4%) and descending aorta (-12%) with PpeakVelo < 0.03. CONCLUSION: k-t GRAPPA acceleration with a 12- or 32-channel receiver coil and an acceleration of 3 or 5 can compete with a standard GRAPPA R = 2 acceleration.

K-t GRAPPA accelerated phase contrast MRI: Improved assessment of blood flow and 3-directional myocardial motion during breath-hold.

PURPOSE: To evaluate spatiotemporal parallel imaging with R = 5 in comparison to conventional parallel imaging with R = 2 applied to phase contrast (PC) magnetic resonance imaging (MRI). This was motivated by the fact that scan times for PC imaging often exceed breath-hold capabilities of patients even with standard parallel imaging using typical reduction factors of R = 2. MATERIALS AND METHODS: K-t generalized autocalibrating partially parallel acquisition (GRAPPA) acquisition was validated in phantom measurements and then applied in 10 volunteer and three patient examinations. Due to the higher reduction factor compared to conventional GRAPPA, k-t GRAPPA measurements could be performed during breath-hold with high spatial and temporal resolution. K-t GRAPPA scans were compared to GRAPPA acquired during free-breathing with navigator respiration control. In addition, spatiotemporally accelerated PC imaging was acquired during free-breathing for comparison of k-t-accelerated breath-held scans. RESULTS: Substantial improvements in image quality for the breath-hold measurements were observed. Significantly reduced peak velocities were found for the GRAPPA protocol compared to the k-t-accelerated breath-hold scans for both flow (8%) and myocardial motion (up to 30%) measurements. CONCLUSION: Spatiotemporal acceleration allows the performance of high temporal or spatial resolution PC imaging during breath-hold while providing high image quality and robust acquisition of functional information that cannot be achieved during breath-hold with standard techniques.

A feasibility study to evaluate splanchnic arterial and venous hemodynamics by flow-sensitive 4D MRI compared with Doppler ultrasound in patients with cirrhosis and controls.

PURPOSE: To evaluate the feasibility of time-resolved flow-sensitive four-dimensional (4D) MRI for the visualization and quantification of splanchnic arterial and portal venous hemodynamics in patients with cirrhosis and in controls. MATERIALS AND METHODS: We applied flow-sensitive 4D MRI to evaluate arterial and portal venous three-dimensional blood flow in patients with advanced liver cirrhosis (n=5) and in healthy controls (n=10) using 3T MRI (spatial resolution=1.7×2.1×2.4 mm, temporal resolution=62.4 ms). The qualitative flow was analyzed using three-dimensional streamlines and time-resolved particle traces. Retrospective flow was quantified in nine predefined anatomic regions evaluating maximum and mean velocities, the flow volume, the vessel lumen area, pulsatility indices, and resistance indices. Doppler ultrasound (US) was our reference standard. RESULTS: Flow-sensitive 4D MRI visualized liver hemodynamics successfully in 91% of patients and 96% of volunteers with limitations for the patients' extrahepatic vessels (one case of splenic and superior mesenteric veins each) and intrahepatic portal vein branches (in five vessels). Healthy control individuals revealed reduced velocities and larger vessel areas in MRI than in Doppler US. We found no significant differences in the flow volume, pulsatility indices, and resistance indices on comparing MRI with US. Regional flow quantification within the splanchnic system of healthy volunteers and liver cirrhosis patients revealed an increase in the inflow (up to 65%), but a decrease in the patients' outflow (up to 37%). CONCLUSION: Flow-sensitive 4D MRI is feasible for profound evaluation of arterial and portal venous hemodynamics in liver cirrhosis patients, providing additional information on the pathophysiology of the altered splanchnic system.

Aortic wall shear stress in Marfan syndrome.

The aim of this study was to quantify changes in thoracic aortic wall shear stress (WSS) in asymptomatic patients with Marfan syndrome (MFS) compared with healthy controls. WSS in the thoracic aorta was quantified based on time-resolved 3D phase contrast MRI with three-directional velocity encoding (4D flow MRI, temporal resolution ∼44 ms, spatial resolution ∼2.5 mm) in 24 patients with confirmed MFS (age = 18 ± 12 years) and in 12 older healthy volunteers (age = 25 ± 3 years). Diameters of the thoracic aorta normalized to body surface area were similar for both groups. Peak systolic velocity, absolute WSS, time-averaged WSS, circumferential WSS, peak systolic WSS, and WSS eccentricity were calculated in eight analysis planes distributed along the thoracic aorta. Plane-wise comparison revealed significant differences between MFS patients and volunteers in the proximal ascending aorta for peak systolic velocities (1.11 ± 0.23 m/s vs. 1.34 ± 0.18 m/s, P = 0.004) and circumferential WSS (0.14 ± 0.03 N/m(2) vs. 0.11 ± 0.02 N/m(2), P = 0.007). WSS eccentricity was altered in most of the ascending aorta and proximal arch (P = 0.009-0.020). MFS patients demonstrated segmental differences in peak systolic WSS with a significantly higher WSS at the inner curvature in the proximal ascending aorta and at the anterior part in the more distal ascending aorta (P < 0.01). These findings indicate differences in WSS associated with MFS despite similar aortic dimensions compared to controls.

Evaluation of 3D blood flow patterns and wall shear stress in the normal and dilated thoracic aorta using flow-sensitive 4D CMR.

BACKGROUND: The purpose of this study was to investigate 3D flow patterns and vessel wall parameters in patients with dilated ascending aorta, age-matched subjects, and healthy volunteers. METHODS: Thoracic time-resolved 3D phase contrast CMR with 3-directional velocity encoding was applied to 33 patients with dilated ascending aorta (diameter≥40 mm, age=60±16 years), 15 age-matched normal controls (diameter≤37 mm, age=68±7.5 years) and 15 young healthy volunteers (diameter≤30 mm, age=23±2 years). 3D blood flow was visualized and flow patterns were graded regarding presence of supra-physiologic-helix and vortex flow using a semi-quantitative 3-point grading scale. Blood flow velocities, regional wall shear stress (WSS), and oscillatory shear index (OSI) were quantified. RESULTS: Incidence and strength of supra-physiologic-helix and vortex flow in the ascending aorta (AAo) was significantly higher in patients with dilated AAo (16/33 and 31/33, grade 0.9±1.0 and 1.5±0.6) than in controls (2/15 and 7/15, grade 0.2±0.6 and 0.6±0.7, P<.05) or healthy volunteers (1/15 and 0/15, grade 0.1±0.3 P<.05). Greater strength of the ascending aortic helix and vortex flow were associated with significant differences in AAo diameters (P<.05). Peak systolic WSS in the ascending aorta and aortic arch was significantly lower in patients with dilated AAo (P<.0157-.0488). AAo diameter positively correlated to time to peak systolic velocities (r=0.30-0.53, P<.04), OSI (r=0.33-0.49, P<0.02) and inversely correlated to peak systolic WSS (r=0.32-0.40, P<.03). Peak systolic WSS was significantly lower in AAo aneurysms at the right and outer curvature within the AAo and proximal arch (P<.01-.05). CONCLUSIONS: Increase in AAo diameter is significantly correlated with the presence and strength of supra-physiologic-helix and vortex formation in the AAo, as well with decrease in systolic WSS and increase in OSI.