25 years of experience with transjugular intrahepatic portosystemic shunt (TIPS): changes in patient selection and procedural aspects

Background: TIPS is an established treatment for portal hypertension. The aim was to analyze how patient selection for TIPS implantation and procedural aspects have changed over 25 years. Routinely collected demographic, clinical, laboratory, and procedural data of 835 patients treated with TIPS in a single center were used. Time trends over the observational period from 1993 to 2018 were retrospectively analyzed. Descriptive statistical analysis was performed. Results: The most common indication for TIPS implantation has changed significantly from secondary prevention of variceal hemorrhage in the early years to treatment of recurrent ascites. During the observation period, increasingly more severely ill patients became TIPS candidates. There was little change in MELD scores over this period (in total median 13.00; IQR 10.00-18.00). The proportion of patients with Child-Pugh C cirrhosis increased. The most frequent underlying diseases in total were alcohol-related liver disease (66.5%) and viral hepatitis (11.9%). However, shares of cryptogenic liver cirrhosis, autoimmune hepatitis, and NASH increased over time. The proportion of patients post liver transplant also increased. While bare metal stents were standard in the past, use of covered stents increased. The success rate of TIPS (defined by successful implantation and a decrease in the portosystemic pressure gradient <= 12 mmHg) increased significantly over time. The total success rate according to this definition was 84.9%. Conclusion: The results of our analysis reflect technical developments in TIPS, especially in terms of stent material and gains in clinical experience, particularly regarding indications and patient selection for TIPS implantation

Radiobiological restrictions and tolerance doses of repeated single-fraction hdr-irradiation of intersecting small liver volumes for recurrent hepatic metastases

<p>Abstract</p> <p>Background</p> <p>To assess radiobiological restrictions and tolerance doses as well as other toxic effects derived from repeated applications of single-fraction high dose rate irradiation of small liver volumes in clinical practice.</p> <p>Methods</p> <p>Twenty patients with liver metastases were treated repeatedly (2 - 4 times) at identical or intersecting locations by CT-guided interstitial brachytherapy with varying time intervals. Magnetic resonance imaging using the hepatocyte selective contrast media Gd-BOPTA was performed before and after treatment to determine the volume of hepatocyte function loss (called pseudolesion), and the last acquired MRI data set was merged with the dose distributions of all administered brachytherapies. We calculated the BED (biologically equivalent dose for a single dose d = 2 Gy) for different α/β values (2, 3, 10, 20, 100) based on the linear-quadratic model and estimated the tolerance dose for liver parenchyma D₉₀as the BED exposing 90% of the pseudolesion in MRI.</p> <p>Results</p> <p>The tolerance doses D₉₀after repeated brachytherapy sessions were found between 22 - 24 Gy and proved only slightly dependent on α/β in the clinically relevant range of α/β = 2 - 10 Gy. Variance analysis showed a significant dependency of D₉₀with respect to the intervals between the first irradiation and the MRI control (p < 0.05), and to the number of interventions. In addition, we observed a significant inverse correlation (p = 0.037) between D₉₀and the pseudolesion's volume. No symptoms of liver dysfunction or other toxic effects such as abscess formation occurred during the follow-up time, neither acute nor on the long-term.</p> <p>Conclusions</p> <p>Inactivation of liver parenchyma occurs at a BED of approx. 22 - 24 Gy corresponding to a single dose of ~10 Gy (α/β ~ 5 Gy). This tolerance dose is consistent with the large potential to treat oligotopic and/or recurrent liver metastases by CT-guided HDR brachytherapy without radiation-induced liver disease (RILD). Repeated small volume irradiation may be applied safely within the limits of this study.</p

MRI for Noninvasive Thermometry

MRI was recognized for its potential use as a noninvasive in vivo thermometer 30 years ago. Today, the most popular application of MR thermometry is the guidance of thermal therapies for the treatment of cancer and other pathologies. These minimally invasive operations are routinely performed on patients who are not eligible for surgery in approximately 40 medical centers globally. The aim is to deliver or abduct thermal energy in order to cause local tissue necrosis or to sensitize a lesion to chemotherapy or radiotherapy without causing harm to the surrounding healthy tissue. Here we explain the principles of operation of MR thermometry and provide a critical review of the proposed methods, highlighting remaining fundamental and technical issues as well as recent progress. Emphasis is placed on hardware advances (RF receivers) for improved signal-to-noise ratio (SNR) which would lead to better accuracy, spatiotemporal resolution, and precise calibration. We conclude with a general outlook for the field

Interfragmentäre Bewegungen und Bodenreaktionsparameter im Verlauf der Frakturheilung

Die Tibiaschaftfraktur ist eine häufig auftretende Verletzung. Der Fixateur externe findet bei der Versorgung von Tibiafrakturen große Verwendung. Die Variabilität und Anpassung an die individuelle Patientensituation stellen den Vorteil der Osteosynthese dar. Gleichzeitig ist unklar, ob und inwiefern die Montageebene die Frakturheilung beeinflusst. Interfragmentäre Bewegungen (IFM) bestimmen die Quantität und Qualität der Kallusbildung. IFM werden wiederum durch die Fixateurmontageebene bedingt. Diese Studie wurde vorgelegt, um den Einfluss der Montageebene auf die Frakturheilung zu bestimmen. Zwei identisch konfigurierte monolaterale Fixateurs externes mit medialer und anteromedialer Montageebene wurden bezüglich ihres Heilungspotentials an der Schafstibia verglichen. IFM und Bodenreaktionsparameter wurden während des neunwöchigen Heilungsverlaufs in vivo ermittelt. Die Knochenkonsolidierung wurde radiologisch und biomechanisch evaluiert. Allein die Änderung der Montageebene führte zu einer Modifikation der IFM. Der Unterschied der IFM war nur in der initialen Heilungsphase signifikant. Diese initialen Unterschiede beeinflussten jedoch bei nicht signifikant unterschiedlicher Gewichtsbelastung die Kallusbildung. Die Gruppe mit anteromedial montierten Fixateur zeigte initial höhere IFM und bewirkte einen radiologisch größeren Kallusdurchmesser und eine biomechanisch größere Kallussteifigkeit im Sinne einer weiter fortgeschrittenen Heilungsphase. Diese erzielten Heilungsergebnisse demonstrieren die Sensitivität der Montageebene und die Bedeutung der initialen biomechanischen Bedingungen, die den Kurs der Frakturheilung beeinflussen. Darum sollte der Montageebene und der dadurch bedingten initialen mechanischen Osteosynthesestabilität in der klinischen Frakturversorgung mehr Beachtung geschenkt werden.Fractures of the tibia are commonly encountered problems. One of the most common osteosyntheses used to stabilise tibial fractures are external fixators. The fixator allows great freedom in configuration, especially with regard to its mounting plane. Whether and how the mounting plane influences the healing process is still unclear. Interfragmentary movements (IFM) affect the quality and quantity of callus formation. The mounting plane of monolateral external fixators may give direction to those movements. The presented study aimed to determine the influence of the fixator mounting plane on fracture healing. Identically configured fixators were mounted either medially or anteromedially on a standardised ovine tibial diastasis model with regard to their fracture healing potential. IFM and ground reaction forces were evaluated in vivo during a nine week period. Biomechanical and radiological parameters described the bone healing process. Changing only the mounting plane led to a modification of IFM in the initial healing phase. The difference in IFM between the groups was only significant during the first post-operative period. However, these initial differences in mechanical conditions influenced callus tissue formation. The group with the anteromedially mounted fixator, initially showing significantly more IFM, ended up with a radiologically bigger callus diameter and a biomechanically higher callus stiffness as a result of advanced fracture healing. This demonstrates that the initial phase of healing is sensitive to mechanical conditions and influences the course of healing. Therefore, initial mechanical stability of an osteosynthesis should be considered an important factor in clinical fracture treatment

Minimal-invasive interventions in open 1.0 Tesla MRI

Die MRT stellt eines der wesentlichen diagnostischen Verfahren in der Medizin dar und hat sich zur Bildgebung für alle Organsysteme etabliert. Seit über 10 Jahren wird die MRT zunehmend auch zur Steuerung und Kontrolle therapeutischer Interventionen eingesetzt. Die MRT kombiniert Eigenschaften wie hoher Weichteilkontrast, freie Wahl der Schichtebene, Verzicht auf ionisierende Strahlung, mit der Fähigkeit zur funktionellen Bildgebung, wie der Darstellung von Temperaturveränderungen in Körpergeweben und physiologischen Vorgängen wie Perfusion und Diffusion. Dies prädestiniert die MRT, um Therapieverfahren von perkutanen Tumorablationen über endovaskuläre und endoskopische Interventionen bis hin zur offenen Chirurgie zu unterstützen und zu überwachen. So ist die Einführung des offen konfigurierten Hochfeld-MRT bei 1.0 Tesla eine wichtige Innovation der letzten Jahre. Dieses MRT-System unterstützt alle Optionen der modernen MRT-Bildgebung, erlaubt einen direkten Zugang zum Patienten und ermöglicht somit die Verwendung des MRT als hochwertige interventionelle Bildgebungsmodalität. In den vorliegenden Arbeiten wurden Untersuchungen zur MR Navigation, Echtzeitbildgebung (MR Fluoroskopie) und zum Artefaktverhalten innovativer MR-kompatibler Interventionsinstrumente im offenen Hochfeld-MRT durchgeführt. Weitere Arbeiten überprüften die Spin-Gitter-Relaxationszeit T1 und Protonenresonanzfrequenz PRF zur Temperaturbestimmung im Gewebe (MR Thermometrie) bei hyperthermen Laser-Therapieverfahren. Abschließend wurde nach den Prinzipien der translationalen Medizin die klinische Anwendung minimal-invasiver Interventionen - spinale Schmerztherapie, Aspiration spinaler Zysten, Diskographie/Diskoblock, Lasertherapie Osteiodosteom und LITT der Leber - im offenen Hochfeld-MRT evaluiert. Die Ergebnisse zeigen die relevanten technischen Möglichkeiten und das große Potential des offenen Hochfeld-MRT als Bildsteuerungsmodalität. Diese Techniken können supplementär zu den anderen bildgebenden Verfahren (US, Fluoroskopie, CT) angewendet werden, insbesondere bei Interventionen, die unter diesen Modalitäten aufgrund schlechter Visualsierung, limitierten Zugangs oder fehlender Monitoringeigenschaften problematisch sind. Die vorgestellten Techniken können darüber hinaus die Qualität minimal-invasiver Therapien steigern und das Indikationsspektrum erweitern. Um die interventionelle MRT weiter voranzubringen, bedarf es einer kontinuierlichen Forschung und Entwicklung durch interventionelle Radiologen, interventionell und operativ tätige Kollegen anderer Fachdisziplinen sowie durch Physiker und Ingenieure. Nur durch eine multidisziplinäre Interaktion kann es zukünftig gelingen, diese komplexe Technologie und die dadurch ermöglichten Interventionen in die klinische Routine einzuführen.Magnetic resonance imaging (MRI) is a major clinical diagnostic tool, having become an established imaging modality for all organ systems. For over a decade now, MRI has been increasingly used for guiding and monitoring therapeutic interventions. MRI combines high soft tissue contrast, multiplanar capabilities, and absence of ionizing radiation with the provision of functional information, for instance, on temperature changes in biological tissues or physiologic processes such as perfusion and diffusion. With these capabilities, MRI is an excellent candidate for assisting and monitoring a range of interventional procedures from percutaneous tumor ablation to endovascular and endoscopic interventions, to open surgery. The recent advent of open 1.0-Tesla high-field MR scanners is an important advance. Open- configuration MRI systems provide all options of state-of-the art MR imaging while at the same time enabling direct access to the patient and thereby allowing use of MRI as a sophisticated interventional imaging modality. The present studies investigated MR navigation, real-time imaging (MR fluoroscopy), and the occurrence of artifacts associated with the use of novel MR-compatible interventional instruments in an open high-field MR imager. Other studies investigated spin-lattice relaxation time, T1, and proton resonance frequency, PRF, for monitoring tissue temperatures (MR thermometry) during laser-induced hyperthermia. Finally, in accordance with the principles of translational medicine, we evaluated clinical applications of a series of minimally invasive interventions – spinal pain treatment, aspiration of spinal cysts, discography/discoblock, laser treatment of osteoid osteoma, and laser- induced thermotherapy (LITT) of the liver – in an open high-field MR system. The results outlined illustrate the major technical capabilities and the excellent potential of open high-field MRI as an image-guidance modality. MRI can be used as an adjunct to other imaging modalities (US, fluoroscopy, CT), especially when performing interventions where these modalities are limited due to poor visualization, inadequate access, or failure to ensure adequate monitoring. The techniques discussed can also improve the quality of minimally invasive interventions and expand their range of application. To further advance interventional MRI, continuous research and development activities are needed involving interventional radiologists, interventionalists and surgeons from other specialties, and physicists and engineers. This multidisciplinary effort is a prerequisite for the translation of this complex technology and the interventional options it provides to a clinical environment