Soluble mannose receptor CD206 and von Willebrand factor are early biomarkers to identify patients at risk for severe or necrotizing acute pancreatitis.

BACKGROUND: In acute pancreatitis (AP), microcirculatory dysfunction and leukocyte activation contribute to organ damage, inflammation, and mortality. Given the role of macrophage activation, monocyte recruitment, and microthrombus formation in the early pathogenesis of AP, we examined the macrophage activation marker soluble mannose receptor (sCD206) and the endothelial function marker von Willebrand factor (vWF) in patients admitted for AP. METHODS: In an exploratory analysis, serum sCD206 and plasma vWF were prospectively analyzed on day 1 and day 3 in 81 patients with AP admitted to the hospital. In addition, blood samples from 59 patients with early AP admitted to the intensive care unit and symptom onset < 24 h were retrospectively analyzed. Patients were dichotomized as per study protocol into two groups: (i) "non-severe edematous AP" including patients with mild AP without organ failure and patients with transient organ failure that resolves within 48 h and (ii) "severe/necrotizing AP" including patients with severe AP and persistent organ failure > 48 h and/or patients with local complications. RESULTS: In the prospective cohort, 17% developed severe/necrotizing pancreatitis compared with 56% in the ICU cohort. Serum concentrations of sCD206 on admission were higher in patients with severe/necrotizing AP than in patients with non-severe edematous AP (prospective: 1.57 vs. 0.66 mg/l, P = 0.005; ICU: 1.76 vs. 1.25 mg/l, P = 0.006), whereas other inflammatory markers (leukocytes, C-reactive protein, procalcitonin) and disease severity (SOFA, SAPS II, APACHE II) did not show significant differences. Patients with severe/necrotizing AP had a greater increase in sCD206 than patients with non-severe edematous AP at day 3 in the prospective cohort. In contrast to routine coagulation parameters, vWF antigen levels were elevated on admission (prospective cohort: 375 vs. 257%, P = 0.02; ICU cohort: 240 vs. 184%, P = 0.03). When used as continuous variables, sCD206 and VWF antigen remained predictors of severe/necrotizing AP after adjustment for etiology and age in both cohorts. CONCLUSIONS: sCD206 identifies patients at risk of severe AP at earlier timepoints than routine markers of inflammation and coagulation. Prospective studies are needed to investigate whether incorporating early or repeated measurements into the existing scoring system will better identify patients at increased risk for complications of AP.

CT-based thermometry with virtual monoenergetic images by dual-energy of fat, muscle and bone using FBP, iterative and deep learning-based reconstruction.

OBJECTIVES: The aim of this study was to evaluate the sensitivity of CT-based thermometry for clinical applications regarding a three-component tissue phantom of fat, muscle and bone. Virtual monoenergetic images (VMI) by dual-energy measurements and conventional polychromatic 120-kVp images with modern reconstruction algorithms adaptive statistical iterative reconstruction-Volume (ASIR-V) and deep learning image reconstruction (DLIR) were compared. METHODS: A temperature-regulating water circuit system was developed for the systematic evaluation of the correlation between temperature and Hounsfield units (HU). The measurements were performed on a Revolution CT with gemstone spectral imaging technology (GSI). Complementary measurements were performed without GSI (voltage 120 kVp, current 130-545 mA). The measured object was a tissue equivalent phantom in a temperature range of 18 to 50°C. The evaluation was carried out for VMI at 40 to 140 keV and polychromatic 120-kVp images. RESULTS: The regression analysis showed a significant inverse linear dependency between temperature and average HU regardless of ASIR-V and DLIR. VMI show a higher temperature sensitivity compared to polychromatic images. The temperature sensitivities were 1.25 HU/°C (120 kVp) and 1.35 HU/°C (VMI at 140 keV) for fat, 0.38 HU/°C (120 kVp) and 0.47 HU/°C (VMI at 40 keV) for muscle and 1.15 HU/°C (120 kVp) and 3.58 HU/°C (VMI at 50 keV) for bone. CONCLUSIONS: Dual-energy with VMI enables a higher temperature sensitivity for fat, muscle and bone. The reconstruction with ASIR-V and DLIR has no significant influence on CT-based thermometry, which opens up the potential of drastic dose reductions. KEY POINTS: • Virtual monoenergetic images (VMI) enable a higher temperature sensitivity for fat (8%), muscle (24%) and bone (211%) compared to conventional polychromatic 120-kVp images. • With VMI, there are parameters, e.g. monoenergy and reconstruction kernel, to modulate the temperature sensitivity. In contrast, there are no parameters to influence the temperature sensitivity for conventional polychromatic 120-kVp images. • The application of adaptive statistical iterative reconstruction-Volume (ASIR-V) and deep learning-based image reconstruction (DLIR) has no effect on CT-based thermometry, opening up the potential of drastic dose reductions in clinical applications.

MRI following scoliosis surgery? An analysis of implant heating, displacement, torque, and susceptibility artifacts.

OBJECTIVES: The implant constructs used in scoliosis surgery are often long with a high screw density. Therefore, it is generally believed that magnetic resonance imaging (MRI) should not be carried out after scoliosis surgery, with the result that computed tomography is often preferred despite the ionizing radiation involved. The objective of this study was to evaluate the MRI compatibility of long pedicle-screw-rod constructs at 1.5 T and 3 T using standardized methods of the American Society for Testing and Materials (ASTM). METHODS: Constructs between 130 and 430 mm long were systematically examined according to the ASTM standards F2182 (radio frequency-induced heating), F2119 (susceptibility artifacts), F2213 (magnetically induced torque), and F2052 (magnetically induced displacement force). RESULTS: The maximum heating in the magnetic field was 1.3 K. Heating was significantly influenced by magnetic field strength (p < 0.001), implant length (p = 0.048), and presence of cross-links (p = 0.001). The maximum artifact width for different lengths of the anatomically bent titanium rods with CoCr alloy ranged between 14.77 ± 2.93 mm (TSE) and 17.49 ± 1.82 mm (GRE) for 1.5 T and between 23.67 ± 2.39 mm (TSE) and 27.77 ± 2.37 mm (GRE) for 3 T. TiCP and TiAl showed the smallest and CoCr and CoCr Plus the largest artifact widths. The magnetically induced torque and displacement force were negligible. CONCLUSIONS: MRI following scoliosis surgery with long implant constructs is safe with the patient in supine position. Although susceptibility artifacts can severely limit the diagnostic value, the examination of other regions is possible. KEY POINTS: • Large spinal implants are not necessarily a contraindication for MRI; MR conditional status can be examined according to the ASTM standards F2182, F2119, F2213, and F2052. • A metallic pedicle-screw-rod system could be reliably and safely examined in all combinations of length (130 to 430 mm), configuration, and material in a B0 at 1.5 T and 3 T. • According to ASTM F2503, the examined pedicle-screw-rod system is MR conditional and especially the young patients can benefit from a non-ionizing radiation MRI examination.

Systematic evaluation of particle loss during handling in the percutaneous transluminal angioplasty for eight different drug-coated balloons.

Paclitaxel drug coated balloons (DCBs) should provide optimal drug transfer exclusively to the target tissue. The aim of this study was to evaluate the particle loss by handling during angioplasty. A robotic arm was developed for systematic and reproducible drug abrasion experiments. The contact force on eight different commercially available DCB types was gradually increased, and high-resolution microscopic images of the deflated and inflated balloons were recorded. Three types of DCBs were classified: no abrasion of the drug in both statuses (deflated and inflated), significant abrasion only in the inflated status, and significant abrasion in both statuses. Quantitative measurements via image processing confirmed the qualitative classification and showed changes of the drug area between 2.25 and 45.73% (13.28 ± 14.29%) in the deflated status, and between 1.66 and 40.41% (21.43 ± 16.48%) in the inflated status. The structures and compositions of the DCBs are different, some are significantly more susceptible to drug loss. Particle loss by handling during angioplasty leads to different paclitaxel doses in the target regions for same DCB types. Susceptibility to involuntary drug loss may cause side effects, such as varying effective paclitaxel doses, which may explain variations in studies regarding the therapeutic outcome.

Automatic human identification based on dental X-ray radiographs using computer vision.

A person may be identified by comparison between ante- and post-mortem dental panoramic radiographs (DPR). However, it is difficult to find reference material if the person is unknown. This is often the case when victims of crime or mass disaster are found. Computer vision can be a helpful solution to automate the finding of reference material in a large database of images. The purpose of the present study was to improve the automated identification of unknown individuals by comparison of ante- and post-mortem DPR using computer vision. The study includes 61,545 DPRs from 33,206 patients, acquired between October 2006 and June 2018. The matching process is based on the Speeded Up Robust Features (SURF) algorithm to find unique corresponding points between two DPRs (unknown person and database entry). The number of matching points found is an indicator for identification. All 43 individuals (100%) were successfully identified by comparison with the content of the feature database. The experimental setup was designed to identify unknown persons based on their DPR using an automatic algorithm system. The proposed tool is able to filter large databases with many entries of potentially matching partners. This identification method is suitable even if dental characteristics were removed or added in the past.

Improvement of olfactory function after sinus surgery correlates with white matter properties measured by diffusion tensor imaging.

Impaired olfaction is associated with a volume decrease in the olfactory bulb as well as in the gray matter of cortical olfactory areas. On the other hand, restitution of an impaired olfaction results in a regain of volume in these regions. Studies investigating similar changes in the cerebral white matter are virtually not existent. The aim of this prospective study therefore was to investigate cerebral white matter using magnetic resonance diffusion tensor imaging (DTI). 31 patients (54±13years) with olfactory impairment (chronic rhinosinusitis) and planned functional endoscopic sinus surgery (FESS) were included. Magnetic resonance imaging (MRI) data sets were acquired pre-operatively and 3months after surgery. Pre- and postoperative olfactory testing was performed to assess the olfactory threshold, discrimination, and identification (TDI) score. A significant postoperative TDI improvement by 9.06±8.81 points was observed. Two groups were subsequently formed - one with relevant postoperative olfactory gain (ΔTDI≥10 points, 12 patients) and one without gain (ΔTDI<10 points, 19 patients). DTI parameter showed a significant correlation with the TDI score in the left anterior cingulate cortex and the right amygdala. In the group with relevant olfactory improvement higher values of fractional anisotropy and apparent diffusion coefficient were found in the right parahippocampal area and in the white matter below the left inferior temporal sulcus. Tract-specific diffusion property analysis revealed significant group differences in the cingulate cortex in spatial relationship to the perisplenial cortex. Overall, this prospective study indicates structural changes in white matter after postoperative restoration of olfaction.

In vitro stent assessment by MRI: visibility of lumen and artifacts for 27 modern stents.

PURPOSE: The purpose of this study was to measure artifacts and visibility of lumen for modern and most commonly used stents in vascular interventions according to a standardized test method of the American Society for Testing and Materials (ASTM). MATERIALS AND METHODS: Twenty-four peripheral self-expanding nitinol stents and three stainless steel stents with diameters between 5 and 8 mm and lengths between 30 and 250 mm from seven different manufacturers were compared on a 1.5T and a 3T magnetic resonance (MR) scanner. The visualization of lumen and artifacts was measured according to ASTM F2119 for a turbo spin echo (TSE) [repetition time(TR)/echo time (TE) 500/26 ms] and a gradient echo (GRE) (TR/TE 100/15 ms) sequence. The stents were placed parallel and perpendicular to the radio frequency field (B1). RESULTS: There were large differences in visibility of the lumen for the stent models. The visualization of the lumen varies between 0% and 93% (perpendicular to B1), and 0% and 78% (parallel to B1), respectively. The maximum signal loss beyond the actual diameter was 6 mm (TSE) and 10 mm (GRE) for stents made of stainless steel, and lower than 1 mm (TSE) and 4 mm (GRE) for nitinol stents. CONCLUSION: Reliable stent lumen visualization is possible for Misago, Supera, Tigris, and Viabahn stents, if their axis is perpendicular to B1, and independent of the orientation with respect to B1 for short Tigris stents at 1.5T.

MR guidance and thermometry of percutaneous laser disc decompression in open MRI: an ex vivo study.

PURPOSE: To assess the feasibility of guidance and thermometry by open 1.0 T magnetic resonance (MR) imaging during percutaneous laser disc decompression (PLDD). METHODS: A fluoroscopic proton-density-weighted turbo spin echo sequence was used for positioning a laser fiber and a reference thermosensor within the targeted spinal disc. In 30 lumbar discs from human donors, nonspoiled gradient-echo (GRE) sequences with different echo times (TE) were compared to monitor thermal laser effects (Nd:YAG laser, 1,064 nm). Temperature distribution was visualized in real time on the basis of T1-weighted images and the proton resonance frequency (PRF) technique. Image quality, temperature accuracy, and correlation with macroscopic lesion sizes were analyzed. Image quality was confirmed in healthy volunteers. RESULTS: MR-guided placement of the laser fiber in the center of the targeted disk was precise. Best overall PLDD results-considering image quality (contrast-to-noise ratio), temperature accuracy (R (2) = 0.96), and correlation between the macroscopic and MR lesions (R (2) = 0.63)-were achieved with TE at 7 ms. The same TE value also gave the best image quality with healthy volunteers. CONCLUSION: Instrument guidance and PRF-based thermometry of PLDD in the lumbar spine are feasible and accurate. Open 1.0 T MR imaging with fast spin-echo and GRE sequence designs may render laser discectomies more effective and controllable.

Initial clinical experience with a quadrupole butterfly coil for spinal injection interventions in an open MRI system at 1.0 tesla.

PURPOSE: To report our initial clinical experience with a new magnetic resonance imaging (MRI) quadrupole coil that allows interventions in prone position. MATERIALS AND METHODS: Fifteen patients (seven women, eight men; average age, 42.8 years) were treated in the same 1.0-Tesla Panorama High Field Open (HFO) MRI system (Panorama HFO) using a quadrupole butterfly coil (Bfly) and compared with 15 patients matched for sex, age, and MR intervention using the MultiPurposeL coil (MPL), performed in conventional lateral decubitus position (all, Philips Medical Systems, Best, The Netherlands). All interventions were performed with a near-real-time proton density turbo spin echo (PD TSE) sequence (time to repeat/time to echo/flip angle/acquisition time, 600 ms/10 ms/90°/3 s/image). Qualitative and quantitative image analyses were performed, including signal intensity, signal-to-noise and contrast-to-noise ratio (SNR, CNR), contrast, and full width at half maximum (FWHM) measurements. RESULTS: Contrast differed significantly between the needle and muscles (Bfly 0.27/MPL 0.17), as well as the needle and periradicular fat (0.13/0.24) during the intervention (both, p=0.029), as well as the CNR between muscles and the needle (10.61/5.23; p=0.010), although the FWHM values did not (2.4/2.2; p=0.754). The signal intensity of the needle in interventional imaging (1152.9/793.2; p=0.006) and the postinterventional SNR values of subcutaneous fat (15.3/28.6; p=0.007), muscles (6.6/11.8; p=0.011), and the CNR between these tissues (8.7/17.5; p=0.004) yielded significant differences. CONCLUSION: The new coil is a valid alternative for MR-guided interventions in an open MRI system at 1.0 tesla, especially if patients cannot (or prefer not to) be in a lateral decubitus position or if prone positioning yields better access to the target zone.

Ankle laxity: stress investigation under MRI control.

OBJECTIVE: The purpose of this study was to examine the advantages of MRI-guided ankle stress examinations in the detection of chronic ankle instability. SUBJECTS AND METHODS: An MRI-compatible stress device was developed and tested for MRI safety. Bilateral MRI stress examinations were performed on 50 volunteers with and without clinically evident subjective instability of the ankle joints (72 subjective stable ankle joints in 37 subjects, 28 ankles in 15 subjects with chronic ankle instability). Both the inversion test and the anterior drawer test were performed under axial, coronal, 45° paraxial, and sagittal T2-weighted fast spin-echo image control. MR images were assessed for talar tilt, subtalar tilt, anterior talus translation, anterior calcaneus translation, medial talocalcaneal translation, and the diameters of the lateral ankle ligaments (anterior talofibular ligament, calcaneofibular ligament, and posterior talofibular ligament). RESULTS: The MRI stress device was found suitable and safe for use in the MRI environment. The talocrural and subtalar joints could be assessed simultaneously. Significant differences between groups A and B (p≤0.05) were found in talar tilt, subtalar tilt, anterior talus translation, anterior calcaneus translation, medial talocalcaneal translation, and decrease in diameters of calcaneofibular and posterior talofibular ligaments. Also found were sex differences in talar tilt, subtalar tilt, anterior talus translation, and diameters of the anterior talofibular, calcaneofibular, and posterior talofibular ligaments. Significant relations were found between talar tilt and anterior talus translation, subtalar tilt and anterior calcaneus translation, subtalar tilt and medial talocalcaneal translation, and between anterior calcaneus translation and medial talocalcaneal translation in groups A and B. CONCLUSION: Stress examination under MRI control has advantages in the assessment of mechanical ankle instability. Additional diagnostic and clinically relevant information is obtained through direct imaging of the ligaments and assessment of additional parameters of ankle laxity (subtalar tilt, anterior calcaneus translation, medial talocalcaneal translation). The main advantages are objective imaging and measurement of abnormal looseness of the lower ankle joint and its direct simultaneous comparison with the upper ankle joint.

MR-guided facet joint injection therapy using an open 1.0-T MRI system: an outcome study.

OBJECTIVES: To evaluate the accuracy, safety and efficacy of magnetic resonance imaging (MRI)-guided facet joint injection therapy using a 1.0-T open MRI. METHODS: One hundred and sixty-six facet joint blocks in 45 patients with lower back pain were performed under MR fluoroscopic guidance using a proton-density-weighted turbo-spin-echo sequence. An in-room monitor, wireless MR-mouse for operator-controlled multiplanar navigation, a flexible surface coil and MR-compatible 20-G needle were used. Clinical outcome was evaluated by questionnaire before intervention and after 1 week, 3, 6 and 12 months using a numerical visual analogue scale (VAS). RESULTS: All facet joint blocks were considered technically successful with distribution of the injectant within and/or around the targeted facet joint. No major complications occurred. The final outcome analysis included 38 patients. An immediate effect was reported by 63 % of the patients. A positive mid-/long-term effect was seen in 13 patients (34 %) after 6 months and in 9 patients (24 %) after 12 months. Mean VAS was reduced from 7.1 ± 1.7 (baseline) to 3.5 ± 2.2, 4.1 ± 3.0, 3.8 ± 2.9 and 4.6 ± 2.9 at 1 week, 3, 6 and 12 months (P < 0.01). CONCLUSIONS: MR-guided facet joint injection therapy of the lumbosacral spine is accurate, safe and efficient in the symptomatic treatment of lower back pain.

MR guidance and thermometry of percutaneous laser disc decompression in open MRI: an initial clinical investigation.

OBJECTIVES: To assess the feasibility, safety and efficacy of real-time MR guidance and thermometry of percutaneous laser disc decompression (PLDD). METHODS: Twenty-four discs in 22 patients with chronic low-back and radicular pain were treated by PLDD using open 1.0-T magnetic-resonance imaging (MRI). A fluoroscopic proton-density-weighted turbo spin-echo (PDw TSE) sequence was used to position the laser fibre. Non-spoiled gradient-echo (GRE) sequences were employed for real-time thermal monitoring based on proton resonance frequency (PRF). Radicular pain was assessed over 6 months with a numerical rating scale (NRS). RESULTS: PLDD was technically successful in all cases, with adequate image quality for laser positioning. The PRF-based real-time temperature monitoring was found to be feasible in practice. After 6 months, 21 % reported complete remission of radicular pain, 63 % at least great pain relief and 74 % at least mild relief. We found a significant decrease in the NRS score between the pre-intervention and the 6-month follow-up assessment (P < 0.001). No major complications occurred; the single adverse event recorded, moderate motor impairment, resolved. CONCLUSIONS: Real-time MR guidance and PRF-based thermometry of PLDD in the lumbar spine under open 1.0-T MRI appears feasible, safe and effective and may pave the way to more precise operating procedures. KEY POINTS: • Percutaneous laser disc decompression (PLDD) is increasingly used instead of conventional surgery. • Open 1.0-T MRI with temperature mapping seems technically successful in monitoring PLDD. • Pain relief was at least 'great' in 64 % of patients. • No major complications occurred. • Open 1.0-T MRI appears a safe and effective option for patient-tailored PLDD.

Image guided placement of extracorporeal life support through bi-caval dual lumen venovenous membrane oxygenation in an interventional radiology setting--initial experience.

PURPOSE: To report our initial results of venovenous ECMO placement of a novel bicaval dual lumen catheter in six consecutive patients with severe respiratory failure. METHODS: [corrected] The dual lumen catheters (Avalon elite, Avalon Laboratories, Rancho Dominguez, CA, USA; available in 13, 16, 19, 20, 23, 27, and 31 French) were inserted with ultrasound-guided puncture via the right internal jugular vein. The devices were placed with the proximal drainage inlet in the SVC, with the distal drainage inlet tip in the IVC, and with the return outlet in the right atrium under fluoroscopy. RESULTS: All catheter placements (1 x 19, 1 x 23, 1 x 27 and 3 x 31 French) were performed successfully: after insertion, adequate flows and gas exchange were obtained in all patients. Median support time was 9.5 days (range 3-41). We did not observe any cannulation-related events, especially no cannula displacement, no cannula thrombosis, no necessary repositioning, and no device failure. Decannulation and extubation was attained in 4/6 (66.7%) patients. 2/6 (33.3%) patients died (on day 3 and on day 10) while still under ECMO because of disease progression not controllable by medical means undertaken. The overall survival and hospital discharge rate in our small sample volume was 66.7% (4/6 patients). CONCLUSIONS: Our initial results suggest that single cannulation dual lumen venovenous ECMO catheter placement can be performed successfully and safely in an Interventional Radiology setting. The technique reported is feasible, easy to use, and the outcome seems to be comparable to other performing implanting specialties.

Evaluation of a MR-quadrupole imaging coil for spinal interventions in a vertical 1.0 T MRI.

The in vivo pain treatment was successfully performed with the patient in a prone position. The PD-weighted TSE with echo time = 10 ms rendered contrast-to-noise-ratio values of 27 ± 10 for needle/fat, 1.6 ± 5 for needle/muscle, and 4 ± 4.7 for needle/nerve tissue. The mean diameter of the needle artifact was 1.2 ± 0.2 mm. In the T(1)-weighted gradient echo, the needle's artifact diameter was 6 ± 2 mm; the needle's contrast-to-noise ratio relative to muscle tissue was 4 ± 2, 7.6 ± 1.5 for needle/fat, and 5 ± 1 for needle/nerve tissue. With the PD-weighted TSE (echo time = 10 ms) and the T(1)-weighted gradient echo, the needle was imaged reliably throughout the intervention. The butterfly surface coil is feasible for the guidance of spinal interventions in a prone patient.

Clinical benefit of power-injectable port systems: a prospective observational study.

OBJECTIVE: To prospectively evaluate the clinical benefit of a central venous port system, which is approved for contrast media injection during contrast enhanced computed tomography. MATERIALS AND METHODS: At a university teaching hospital, 98 patients (59 female, 39 male; median age 61.7 years; range 23-83) had a power-injectable central venous port catheter system implanted. All implantations were performed under ultrasonographic and fluoroscopic guidance by interventional radiologists. Procedure related immediate (up to 24 h after implantation), early (<30 days after implantation) and late complications were documented. The frequency of port system use for contrast enhanced computed tomography scans was also considered. Any port capsule migration was assessed indirectly by determining the catheter tip position. The intended follow-up period was 180 days. RESULTS: An overall complication rate of 0.69 for 1,000 catheter days in 78 evaluated ports was recorded (12 ports affected, 15.4%). During the observational period, 40 of 104 contrast enhanced computed tomography scans were performed utilizing the port for contrast media administration (38.5%). 30 catheter tip retractions of more than 3 cm were observed in 82 patients (36.6%). Overall, tip dislocations were statistically more frequent in the female subgroup. CONCLUSION: The complication rate found in this study is comparable to those, which have been published for standard port systems. The utilization of the device for contrast media injection during contrast enhanced computed tomography scans should be increased. Finally, the port capsule has to be carefully positioned and fixed to prevent migration.

A signal-inducing bone cement for magnetic resonance imaging-guided spinal surgery based on hydroxyapatite and polymethylmethacrylate.

The aim of this study was to develop a signal-inducing bone cement for magnetic resonance imaging (MRI)-guided cementoplasty of the spine. This MRI cement would allow precise and controlled injection of cement into pathologic lesions of the bone. We mixed conventional polymethylmethacrylate bone cement (PMMA; 5 ml methylmethacrylate and 12 g polymethylmethacrylate) with hydroxyapatite (HA) bone substitute (2-4 ml) and a gadolinium-based contrast agent (CA; 0-60 µl). The contrast-to-noise ratio (CNR) of different CA doses was measured in an open 1.0-Tesla scanner for fast T1W Turbo-Spin-Echo (TSE) and T1W TSE pulse sequences to determine the highest signal. We simulated MRI-guided cementoplasty in cadaveric spines. Compressive strength of the cements was tested. The highest CNR was (1) 87.3 (SD 2.9) in fast T1W TSE for cements with 4 µl CA/ml HA (4 ml) and (2) 60.8 (SD 2.4) in T1W TSE for cements with 1 µl CA/ml HA (4 ml). MRI-guided cementoplasty in cadaveric spine was feasible. Compressive strength decreased with increasing amounts of HA from 46.7 MPa (2 ml HA) to 28.0 MPa (4 ml HA). An MRI-compatible cement based on PMMA, HA, and CA is feasible and clearly visible on MRI images. MRI-guided spinal cementoplasty using this cement would permit direct visualization of the cement, the pathologic process, and the anatomical surroundings.

Evaluation of radiologically implanted central venous port systems explanted due to complications.

PURPOSE: The aim of this study was to evaluate explantations of central venous port systems that were implanted by interventional radiologists in cases where complications demanded the removal of the port device. METHODS: In this retrospective single-center study, explantation rates of central venous port catheter systems (CVPS) associated with complications were investigated over a 10-year period. All CVPS were implanted and explanted in our radiology department's interventional suite. Port catheter dysfunctions were divided into early and late complications, as well as into nonthrombotic and thrombotic events. Indications for implantation and explantation as well as clinical demographics were considered. RESULTS: One hundred and ninety-three CVPS were removed from 182 patients, due to complications. The total indwelling time of all CVPS was 55,132 catheter-days (mean 285.7; range 1-2,704). The most common diagnoses were gastrointestinal cancers 77 (39.9%) and hematological malignancies 32 (16.6%). Bloodstream infections 134 (69.4%) were the most common indication for the explantation procedure. These were followed by catheter-related thrombosis 28 (14.5%), nonthrombotic CVPS dysfunction 18 (9.3%), port pocket infections 9 (4.7%), and others 4 (2.1%). The highest percentages of explantations related to bloodstream infections were observed in patients with malabsorption (81.8%) and hematological malignancies (81.3%). CONCLUSION: Bloodstream infections were the most common cause for port explantation, followed by catheter-related thrombosis. Complication-related explantations were mainly for late-onset complications. Prevention and management strategies should be applied regarding care and usage of port systems to reduce the rate of complication-related explantations.

Outcome analysis in 3,160 implantations of radiologically guided placements of totally implantable central venous port systems.

OBJECTIVES: In this retrospective study the success and complication rates after radiologically guided port catheter implantation were evaluated. METHODS: Between 2000 and 2008, 3,160 port catheter systems were implanted in our interventional suite. All interventions were imaging guided. The puncture of the preferably right internal jugular vein (IJV) was ultrasound-assisted and the catheter tip position was controlled with fluoroscopy. Catheter indwelling time and rates of periprocedural, early and late complications were evaluated. RESULTS: 922,599 catheter days (mean, 292 days; range, 0-2,704 days) were documented. The implantation was successful in 3,153 (99.8%) cases. A total of 374 (11.8%; 0.41/1,000 catheter days) adverse events were recorded. Of these, 42 (1.33%) were periprocedural complications. 86 (3.3%; 0.09/1,000 catheter days) early and 246 (9.4%; 0.27/1,000 catheter days) late onset complications occurred after port implantation. The most common complications were blood stream infection (n = 134; 5.1%; 0.15/1,000 catheter days), catheter-induced venous thrombosis (n = 97; 3.7%; 0.11/1,000 catheter days) and catheter migration (n = 34; 1.3%; 0.04/1,000 catheter days). A total of 193 (6.1%) port explantations were required. CONCLUSION: Ultrasound guided port implantation via the IJV results in low periprocedural complication rates.

The impact of imaging speed of MR-guided punctures and interventions in static organs--a phantom study.

PURPOSE: Verification of MR-guidance with image acquisitions slower than 1 image per second as it is inevitable for some interventions. Therefore, we quantified solely the effect of acquisition-time on the efficiency of MR-guided interventions in a static phantom study. MATERIALS AND METHODS: We measured the duration, accuracy and error rate of simulated interventions for different acquisition-times using a simplified interventional setup. All measurements were performed in a 1.0 T open MRI scanner. Imaging was performed with a gradient-echo sequence (flipangle=20°; TR/TE=12/6 ms; voxelsize=1 mm×1 mm; slicethickness=5 mm; FOV=230 mm×200 mm; acquisition-time=1 s). Variable acquisition times were simulated with intermediate pauses of 0, 1, 2, 3, 4 and 5 s. The interventions were performed by a total of 20 volunteers including 7 experienced interventionalists. RESULTS: The mean duration of the intervention was 2 min. Significant differences between experienced and unexperienced volunteers were limited to the localization of the image plane and corrections made. The mean accuracy was 5.6 mm. The time to localize the image plane increased with deceleration of imaging from 24 s to 49 s. A similar increase was observed for the intervention time (55-108 s). A significant influence of the acquisition-time on durations and corrections was only found with acquisition-times greater than 4s per image. CONCLUSION: Even image rates of several seconds per image are sufficient enough for efficient interventions in static organs. Thus, the main attention has to be turned on the visibility of the needle when sequences are optimized for MR-guidance. The minimization of imaging speed is rather of secondary interest.