Sebastian Kos

Lymphangiography: Forgotten Tool or Rising Star in the Diagnosis and Therapy of Postoperative Lymphatic Vessel Leakage

Since the advent of computed tomography, numbers and expertise in Lymphangiography (LAG) have markedly dropped. The intention of our study was to demonstrate the persisting diagnostic and therapeutic impact of LAG on the postoperative patient with known or suspected lymphatic vessel leakage. Between May 1, 1999, and April 30, 2006, we investigated pedal lipiodol-LAGs (18 monopedal, 2 bipedal) on 22 patients (16 male, 6 female) with known or suspected postoperative chylothorax, chylaskos, lymphocele, or lymphatic fistula. Ages varied from 26 to 81 years. The spectrum of operative procedures was broad: 6 thoracic, 5 abdominal, and 11 peripheral operations were performed. In 20 patients who underwent mono- or bipedal LAG for lymphatic vessel injury, we were able to demonstrate the specific site of leakage in 15 cases (75%) and found signs of extravasation in 5 patients (25%). Furthermore, in 11 patients (55%) we were able to avoid surgery because of closure of the leak after LAG. As the conservative therapeutic approach usually takes 2–3 weeks to reveal its therapeutic effects, 73.3% (11/15) of the patients who were not reoperated before this hallmark was passed did not need any further operation. Our study clearly demonstrates that even in the decades of modern cross-sectional imaging, classic LAG is a powerful and highly reliable tool to visualize and even assist occlusion of the postoperatively damaged lymphatic vessel and may thereby avoid the need for reoperation.

Simultaneous dynamic blood oxygen level-dependent magnetic resonance imaging of foot and calf muscles : aging effects at ischemia and postocclusive hyperemia in healthy volunteers

Purpose:To demonstrate the feasibility of simultaneous blood oxygen level-dependent (BOLD) magnetic resonance imaging of calf and foot muscles and investigate age-related changes of BOLD signal changes during ischemia and postocclusive hyperemia in healthy volunteers. Material and Methods:In this study, 15 healthy elderly volunteers (mean age: 69.0 ± 7.4 years) and 15 healthy young volunteers (mean age: 26.1 ± 3.9 years) were enrolled. In both legs, simultaneous BOLD imaging of calf and foot muscles was performed at 1.5 Tesla. Short-term ischemia and consecutive reactive hyperemia were provoked by a cuff-compression paradigm. T2*-weighted signal time courses were obtained from foot and calf muscles simultaneously. Ischemia was assessed by T2* minimum ischemic value (MIV) and the time to half ischemic minimum (THIM). Reperfusion was assessed by the time to reach T2* half hyperemia peak (THHP). Reactive hyperemia was characterized by hyperemia peak value (HPV), time to peak (TTP), and relative T2* change from end of ischemia to HPV (δS). Parameter differences were assessed using a 2-sided Student t test. Results:Dynamic BOLD measurement of foot and calf muscles was techniqually feasible and successful in all volunteers.In comparison, THIM was significantly longer in elderly than in young volunteers for calf (P < 0.01) muscles (young: 28.9 ± 3.7 seconds; elderly: 57.8 ± 31.4 seconds) and foot (P = 0.01) muscles (young: 36.8 ± 25.5 seconds; elderly: 56.6 ± 31.7 seconds). MIV relative to baseline T2*-signal was significantly (P < 0.01) lower in the elderly for calf (young: 96.0% ± 2.6%; elderly: 91.3% ± 4.4%) and foot (young: 95.8% ± 2.5%; elderly: 91.1% ± 8.2%) muscles. TTP was significantly (calf: P = 0.01; foot: P = 0.02) delayed in the elderly (elderly calf: 103.0 ± 92.7 seconds and foot: 157.1 ± 109.9 seconds vs. young calf: 54.8 ± 42.1 seconds and foot: 95.1 ± 77.6 seconds). HPV was significantly (calf: P < 0.01 and foot: P = 0.03) higher in (young calf: 114.1% ± 7.2% and foot: 105.8% ± 3.3% vs. elderly calf: 104.0% ± 2.1% and foot: 103.9% ± 3.2% seconds) young volunteers.In a muscle-group comparison, no significant differences in THIM and MIV were observed between calf and foot.THHP was significantly (P = 0.02) longer in foot muscles (foot young: 32.5 ± 29.8 seconds and elderly: 34.1 ± 25.0 seconds vs. calf young: 16.8 ± 14.1 seconds and elderly: 23.6 ± 14.1 seconds) of both age groups. TTP was significantly (P = 0.01 and 0.02) longer in foot muscles (foot young: 95.1 ± 77.6 seconds and elderly: 157.1 ± 109.9 seconds vs. calf young: 54.8 ± 42.1 seconds and elderly: 103.0 ± 92.7 seconds) of both age groups. HPV was lower (P < 0.01) in foot muscles of the young (calf: 114.1% ± 7.2% vs. foot: 105.8 ± 3.3%). Conclusion:Simultaneous BOLD-imaging of calf and foot muscles is feasible and reveals statistically significant age-related differences during ischemia and postocclusive hyperemia in healthy volunteers.

First magnetic resonance imaging-guided aortic stenting and cava filter placement using a polyetheretherketone-based magnetic resonance imaging-compatible guidewire in swine: proof of concept.

The purpose of this study was to demonstrate feasibility of percutaneous transluminal aortic stenting and cava filter placement under magnetic resonance imaging (MRI) guidance exclusively using a polyetheretherketone (PEEK)-based MRI-compatible guidewire. Percutaneous transluminal aortic stenting and cava filter placement were performed in 3 domestic swine. Procedures were performed under MRI-guidance in an open-bore 1.5-T scanner. The applied 0.035-inch guidewire has a PEEK core reinforced by fibres, floppy tip, hydrophilic coating, and paramagnetic markings for passive visualization. Through an 11F sheath, the guidewire was advanced into the abdominal (swine 1) or thoracic aorta (swine 2), and the stents were deployed. The guidewire was advanced into the inferior vena cava (swine 3), and the cava filter was deployed. Postmortem autopsy was performed. Procedural success, guidewire visibility, pushability, and stent support were qualitatively assessed by consensus. Procedure times were documented. Guidewire guidance into the abdominal and thoracic aortas and the inferior vena cava was successful. Stent deployments were successful in the abdominal (swine 1) and thoracic (swine 2) segments of the descending aorta. Cava filter positioning and deployment was successful. Autopsy documented good stent and filter positioning. Guidewire visibility through applied markers was rated acceptable for aortic stenting and good for venous filter placement. Steerability, pushability, and device support were good. The PEEK-based guidewire allows either percutaneous MRI-guided aortic stenting in the thoracic and abdominal segments of the descending aorta and filter placement in the inferior vena cava with acceptable to good device visibility and offers good steerability, pushability, and device support.

Feasibility of Real-Time Magnetic Resonance-Guided Angioplasty and Stenting of Renal Arteries in Vitro and in Swine, Using a New Polyetheretherketone-Based Magnetic Resonance-Compatible Guidewire

Objectives:Demonstrate the usability of a new polyetheretherketone (PEEK)-based MR-compatible guidewire for renal artery catheterization, angioplasty, and stenting under MR-guidance using MR-visible markers, in vitro and in vivo. Material and Methods:The new 0.035″ guidewire with fiber-reinforced PEEK core, a soft tip, and a hydrophilic coating was used. Paramagnetic markings were coated on the wire and nonbraided catheters for passive visualization. Bending stiffness of the guidewire was compared with available hydrophilic guidewires (Terumo Glidewire Stiff and Standard). A human aortic silicon phantom and 2 pigs were used. The study was animal care and use approved by the committee. Under MR-guidance, renal arteries were catheterized, balloon angioplasty was performed, and balloon expandable renal artery stents were deployed in vivo. Post mortem autopsy was performed. Guidewire visibility, pushability, steerability, and device-support capabilities of the marked guidewire were qualitatively assessed. Procedure times were recorded. Results:Bending stiffness of the new PEEK-based wire was comparable with Standard Glidewire. In vitro and in vivo guidewire guidance, catheter configuration, renal artery catheterization, and balloon angioplasty were successful. In pigs, stent deployments were successful in both renal arteries. Autopsy revealed acceptable stent positioning. Guidewire visibility through applied markers was acceptable. Steerability, pushability, and device support were good in vitro and in vivo. Conclusions:The PEEK-based guide allows percutaneous MR-guided renal artery angioplasty and stenting with sufficient visibility, good steerability, pushability, and device support.

Pedal Angiography in Peripheral Arterial Occlusive Disease: First-Pass IV Contrast-Enhanced MR Angiography with Blood Pool Contrast Medium Versus Intraarterial Digital Subtraction Angiography

OBJECTIVE The purpose of this study was to prospectively evaluate first-pass i.v. gadofosveset-enhanced MR angiography in patients with peripheral arterial occlusive disease for visualization of the pedal arteries and stenosis or occlusion of those arteries with intraarterial digital subtraction angiography as the reference standard. SUBJECTS AND METHODS Twenty patients with peripheral arterial occlusive disease (nine women, 11 men; age-range 58-83 years) were prospectively enrolled. Gadofosveset first-pass contrast-enhanced MR angiography was performed with a 1.5-T system, a dedicated foot coil, and cuff compression to the calf. Arterial segments were assessed for degree of arterial stenosis, arterial visibility, diagnostic utility, and venous contamination. Detection of vessel stenosis or occlusion was evaluated in comparison with findings at digital subtraction angiography. The unpaired Students t test was used to test arterial visibility with the two techniques. RESULTS First-pass MR angiography with gadofosveset had good diagnostic utility in 83.9% of all segments and no venous contamination in 96.8% of all segments. There was no difference between the performance of intraarterial digital subtraction angiography and that of i.v. contrast-enhanced MR angiography in arterial visibility overall (p = 0.245) or in subgroup analysis of surgical arterial bypass targets (p = 0.202). The overall sensitivity, specificity, and accuracy of i.v. gadofosveset-enhanced MR angiography for characterization of clinically significant stenosis and occlusion were 91.4%, 96.1%, and 93.9%. In the subgroup analysis, the sensitivity, specificity, and accuracy were 85.5%, 96.5%, and 92.1%. CONCLUSION Gadofosveset-enhanced MR angiography of the pedal arteries in patients with peripheral arterial occlusive disease has arterial visibility equal to that of digital subtraction angiography and facilitates depiction of clinically significant stenosis and occlusion.

MR-compatible polyetheretherketone-based guide wire assisting MR-guided stenting of iliac and supraaortic arteries in swine: Feasibility study

The purpose of this study was to demonstrate first magnetic resonance (MR)-guided stenting of iliac and supraaortic arteries using a polyetheretherketone-based (PEEK) MR-compatible guide wire. In vitro and animal experiments were performed in a short magnet wide-bore scanner (1.5 Tesla, Espree®, Siemens Healthcare, Erlangen, Germany). For all experiments, a 0.035″ MR-compatible guide wire prototoype was used. This wire had a compound core of PEEK with reinforcing fibres, a soft and atraumatic tip and a hydrophilic coating. For its passive visualization, paramagnetic markings were attached. All experiments were performed through a vascular introducer sheath under MR-guidance. In vitro repetitive selective over the wire catheterizations of either the right carotid artery and the left subclavian artery were performed. In vivo, selective catheterization and over-the-wire stenting of the brachiocephalic trunc and the left subclavian artery were performed. The common iliac arteries were catheterized retrogradely (left) and cross-over (right). Angioplasty and stenting were performed over-the-wire. All procedures were successful. Visibility of the PEEK-based guide-wire was rated good in vitro and acceptable in vivo. Guide wire pushability and endovascular device support were good. The PEEK-based MR-compatible guide wire is well visible and usable under MR-guidance. It supports over-the-wire treatment of iliac arteries and supraaortic arteries.

A review of conventional and drug-eluting chemoembolization in the treatment of colorectal liver metastases: principles and proof

The management of colorectal liver metastasis has undergone a significant change since the development of novel ablation and embolization. Drug-eluting microsphere platforms, designed to deliver targeted concentrations of systemic therapy directly into the tumor via its arterial vasculature, have garnered interest and gained in popularity in recent years. Based on in vitro and in vivo data, multiple factors contribute to locoregional exposure including carrier base, smaller particle size (larger surface area), chemotherapeutic and chemotherapeutic intensity. Based on the current published clinical data, therapy appears well tolerated but the questions remain as to the ideal technique, patient population and overall efficacy. The purpose of this article is to provide a perspective on the scientific basis, and clinical review of the current data supporting the use of this platform in the setting of metastatic colorectal carcinoma.

CT-guided robotically-assisted infiltration of foot and ankle joints

It was our aim to describe a CT-guided robotically-assisted infiltration technique for diagnostic injections in foot and ankle orthopaedics. CT-guided mechatronically-assisted joint infiltration was performed on 16 patients referred to the orthopaedic department for diagnostic foot and ankle assessment. All interventions were performed using an INNOMOTION-assistance device on a multislice CT scanner in an image-guided therapy suite. Successful infiltration was defined as CT localization of contrast media in the target joint. Additionally, pre- and post-interventional VAS pain scores were assessed. All injections (16/16 joints) were technically successful. Contrast media deposit was documented in all targeted joints. Significant relief of pain was noted by all 16 patients (p<0.01). CT-guided robotically-assisted intervention is an exact, reliable and safe application method for diagnostic infiltration of midfoot and hindfoot joints. The high accuracy and feasibility in a clinical environment make it a viable alternative to the commonly used fluoroscopic-guided procedures.

Diagnosis and Therapy of Acute Hemorrhage in Patients with Pelvic Fractures

Within the past 15 years, significant advances in the imaging of multiorgan and complex trauma primarily due to the improvement of cross-sectional imaging have resulted in the optimization of the expedient diagnosis and management of the polytrauma patient. At the forefront, multidetector computed tomography (MDCT) has become the cornerstone of modern emergency departments and trauma centers. In many institutions, MDCT is the de facto diagnostic tool upon trauma activation. In the setting of pelvic imaging, MDCT (with its high spatial resolution and sensitivity as well as short acquisition times) allows for rapid identification and assessment of pelvic hemorrhage leading to faster triage and definitive management. In trauma centers throughout the world, angiography and minimally invasive catheter-based embolization techniques performed by interventional radiologists have become the standard of care for patients with acute pelvic trauma and related multiorgan hemorrhage. In an interdisciplinary setting, embolization may be performed either alone or as an adjunct procedure with open or closed reduction and stabilization techniques. A team-based approach involving multiple disciplines (e.g., radiology, traumatology, orthopedic surgery, intensive care medicine) is crucial to monitor and treat the actively bleeding patient appropriately.

A Practical Guide to Magnetic Resonance Vascular Imaging: Techniques and Applications

Magnetic resonance angiography is a technique used to image both central and peripheral arteries using contrast and noncontrast techniques. These techniques are similar in that a bright signal, which appears white within blood vessels, is generated and the background tissues, veins, and stationary tissues are dark. This allows for assessment of anatomy and vascular disease. Extracellular gadolinium-based contrast agents allow for excellent visualization of both central and peripheral arteries. Acquiring images during first pass is required for high-contrast images within arteries, thereby limiting contamination with contrast enhancement of veins and soft tissue. Contrast-enhanced techniques using time-resolved angiography and blood pool contrast agents minimize this temporal limitation. Noncontrast techniques eliminate the uncommon but potentially fatal complications associated with gadolinium contrast agents, such as nephrogenic systemic fibrosis. These techniques including phase contrast and time-of-flight sequences have inferior contrast resolution compared with contrast-enhanced techniques and are susceptible to artifacts, which can limit interpretation. The advantage, however, is the ability to assess vascular disease in patients with severe renal failure without the added risks of gadolinium contrast media. The aim of this review is to outline the different techniques available for imaging both the arterial and venous systems, their advantages and disadvantages, and the indications in vascular disease.