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Objective: To test the feasibility and safety of the laser-induced thermotherapy (LITT) for liver metastases in open MR imaging system operating at 0.2 Tesla., Method: Laser therapy using the Nd:YAG laser was performed on 25 patients with a total of 41 liver metastases. An open low-field MRI scanner was used for puncture, positioning of the laser applicator, and monitoring the therapy. A true FISP sequence was used to track the puncture in close to real-time. Localization diagnostics and temperature monitoring were aided by T1-weighted gradient echo sequences in the breath-holding technique. In the first follow up after 24-48 hours, a contrast-enhanced T1-weighted gradient-echo sequence was performed in an MRI scanner at 1.5T. The pre-, intra- and postinterventional volumes of the liver metastases as well as the thermolesions and the thermonecroses were determined., Results: LITT in an open MRI system was technically feasible in all patients with no clinically relevant complications. The mean volumes of the thermolesions measured during intervention in low-field MRI were lower than the volumes of the thermonecroses measured after intervention in high-field MRI., Conclusion: The technique presented here of laser-induced thermotherapy for liver metastases in an open MRI system is technically feasible and safe.

Purpose: The aim of this study is to introduce a fast, T2 weighted true FISP keyhole sequence implemented on an open C arm low field magnetic resonance (MR) scanner for interventional procedure guidance., Method: Following the acquisition of a reference data set using a true FISP (fast Imaging with Steady Precision) sequence, only the 32 central raw data lines (keyhole) are acquired in a fluoroscopic-like mode enabling continuous image reconstruction and update. The keyhole true-FISP sequence was tested in animal experiments and used in MR-guided interventions in 10 patients., Results: The described true FISP keyhole sequence is characterized by an image frame rate of 2.5 images per second and a T2-like contrast. Due to system constraints with respect to the reconstruction, the actual displaying of images was delayed by up to 180 ms., Conclusions: The use of the described keyhole sequence enabled a fluoroscopy-like guidance of interventional devices in an open, low-field system.

Purpose: An animal model is used to investigate whether MR angiography combined with super-paramagnetic particles of iron oxide (SPIO) is suitable for detecting thromboses., Methods: 42 rats in groups of 7 each were examined on days 1, 3, 5, 7, 9 and 11, respectively, after mechanical/chemical thrombus induction in a 1.5 Tesla magnet with a FISP sequence (TR/TE/FA 50 ms/6 ms/40 degrees). Imaging was performed before and up to 90 minutes after intravenous injection of 30 mumol FE/kg BW of the experimental SPIO (hydrodynamic diameter, 34 +/- 17 nm LLS; R1 and R2 relaxivity at 0.47 T, 31 and 57 L/(mmol*s)). MIP reconstructions of MR angiographies were submitted to consensus assessment by two examiners. using histology as the gold standard., Results: The image quality of MIP reconstructions was rated as good in 38 of 42 cases. With regard to thrombotic vessel occlusion, MR angiography coincided with histology in 17 of 42 cases and differed in 25, lumen narrowing being overestimated by MRI in 4 cases and underestimated in 21. In these 21 cases, the histologically observed recanalization could not be detected by MR angiography., Conclusions: SPIO-enhanced MR angiography achieves adequate vessel contrast and reliable thrombus detection in animal experiments. Partial volume effects prevent microscopically observed recanalization from being detected by clinical MRI.

Purpose: The use of mini-laparoscopy scissors to remove a central venous catheter inadvertently fixed to the wall of the brachiocephalic vein is described., Patient and Methods: During a rethoracotomy in a 15-year-old female patient, a central venous catheter preoperatively introduced in the left subclavian vein was inadvertently trapped by a suture and fixed to the wall of the left brachiocephalic vein. The foreign body was removed by use of a transjugularly introduced venous sheath, a catheter wire snare, and mini-laparoscopy scissors., Results: The fixed catheter was freed from the wall of the vein under fluoroscopic control with the help of a mini-laparoscopy scissors. Since the intravasal end of the catheter had already been grasped during mobilization with the wire snare it could be completely removed subsequently without any problem., Conclusions: The percutaneous, intravascular use of mini-laparoscopy instruments may be considered for foreign body removal in special cases.

Purpose: To investigate interactive MR-assisted bile duct drainage in pigs with the passive visualization technique using near real-time imaging., Methods: 8 bile duct drainages were placed in an open low-field MR system (0.2 Tesla) in 4 pigs with surgically induced cholestasis. After planning the intervention with magnetic resonance cholangiography (MRC), both the puncture and catheter placement were interactively guided using a fast T2-weighted true FISP sequence., Results: MRC enabled interventional planning in all puncture attempts. Punctures were unproblematic in all attempts, the bile ducts were punctured 6 times after the first and twice after the second attempt. Placement of the passively visible catheter was successful in all animals. The applied sequence enables interactive fluoroscopy-like positioning of the devices., Conclusion: The procedure introduced here enables reliable and fast placement of a bile duct drainage in an animal model using a low-field MR system.

Aim: To evaluate MR cholangio-pancreatography (MRCP) using an open low magnetic field apparatus in normals and in patients with mechanical cholestasis., Methods: MRCP was performed on five normals and on 30 patients, using both an 0.2 Tesla and 1.5 Tesla apparatus. With the low field system, rapid acquisition by relaxation enhancement was used, for the high field system, half Fourier acquisition single shot turbo spin-echo sequences were used. In all patients, sonography and ERCP or PTC was performed; 23 underwent surgery., Results: In all normals it was possible to show the bile duct, hepatic duct, gall bladder and intrahepatic ducts of the first order. Using the high field system, second order ducts could be shown and sometimes third order ducts. In the patients, MRCP, using either system, demonstrated all 21 obstructive sites due to tumours or stenoses. Stones were shown in 69% by the low field system and in 88% by the high field system., Conclusion: MRCP can be successfully carried out using the low field system. In the presence of mechanical cholestasis, image quality is adequate for the localisation of stenoses and occlusions, and, using an open magnet, is suitable for planning further intervention.

Unlabelled: The aim of this prospective MRI study was the analysis of the post-operative signals derived from two techniques for cruciate ligament reconstruction., Patients and Methods: Group 1 consisted of 15 patients who had undergone conventional plastic repair by patellar tendon transplant and group 2 was made up of 15 patients with arthroscopic reconstruction with semitendinosus grafts. They were examined at 6 weeks and 6 months post-operatively., Results: Typical appearances of normal transplants were found in 19 patients. After 6 months 8 of the patellar tendon transplants and three of the semitendinosus transplants could not be clearly defined. At this time there was a significant increase in signal intensity in the middle third of the transplant in group 1., Conclusion: Bearing in mind the different operative techniques, there was a higher impingement rate in group 1. The post-operative MRI findings at 6 months after surgery allowed differentiation between pathological changes (impingement) and revascularisation (remodelling).

The aim of this study was to demonstrate metabolic changes in the small joints of the hand due to rheumatoid arthritis by means of 31-phosphorus spectroscopy. Suitable measurements were developed and 11 normals and 12 patients were then examined during the course of treatment. Relative concentration of low energy phosphorus metabolites was increased in arthritic joints. The phospholipid quotient (phosphomonoester/phosphodiester) and the relationship of inorganic phosphate and beta-nucleoside triphosphate were significant factors during the course of individual treatments.

In a prospective study, the right knee of 21 symptom free juvenile footballers was examined by MRT (group I) and the results were compared with 12 juveniles of similar age but who did not take part in any special sporting activities (group II). A 1.5 Tesla Magnetome with an extremity coil was used. There were no abnormal changes in either group in the cruciate ligaments. The hyaline cartilage medially was about 10% thicker than laterally in both groups but in group I it was, on average, 24.8% thicker than in group II. Increased signals in the centre of the menisci were observed in 8 members of group I and two in group II. 5 of the 8 in group I, but none in group II, also showed an increase in the joint fluid.