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Aims Anterior cruciate ligament (ACL) rupture commonly leads to post-traumatic osteoarthritis, regardless of surgical reconstruction. This study uses standing MRI to investigate changes in contact area, contact centroid location, and tibiofemoral alignment between ACL-injured knees and healthy controls, to examine the effect of ACL reconstruction on these parameters. Methods An upright, open MRI was used to directly measure tibiofemoral contact area, centroid location, and alignment in 18 individuals with unilateral ACL rupture within the last five years. Eight participants had been treated nonoperatively and ten had ACL reconstruction performed within one year of injury. All participants were high-functioning and had returned to sport or recreational activities. Healthy contralateral knees served as controls. Participants were imaged in a standing posture with knees fully extended. Results Participants’ mean age was 28.4 years (SD 7.3), the mean time since injury was 2.7 years (SD 1.6), and the mean International Knee Documentation Subjective Knee Form score was 84.4 (SD 13.5). ACL injury was associated with a 10% increase (p = 0.001) in contact area, controlling for compartment, sex, posture, age, body mass, and time since injury. ACL injury was associated with a 5.2% more posteriorly translated medial centroid (p = 0.001), equivalent to a 2.6 mm posterior translation on a representative tibia with mean posteroanterior width of 49.4 mm. Relative to the femur, the tibiae of ACL ruptured knees were 2.3 mm more anteriorly translated (p = 0.003) and 2.6° less externally rotated (p = 0.010) than healthy controls. ACL reconstruction was not associated with an improvement in any measure. Conclusion ACL rupture was associated with an increased contact area, posteriorly translated medial centroid, anterior tibial translation, and reduced tibial external rotation in full extension. These changes were present 2.7 years post-injury regardless of ACL reconstruction status. Cite this article: Bone Joint J 2021;103-B(9):1505–1513.

Given the increasing use of MRI in the pediatric population, the need for sedation in MRI performed in young children is a topic of growing importance. Although sedation is generally tolerated well by children, the financial and operational impacts of anesthesia on MRI workflow, as well as potential adverse effects of anesthetic medications, highlight the need to perform MRI in children without sedation whenever possible. This review focuses on current techniques to facilitate non-sedation MRI in children, including exam preparation with MRI simulation; asleep but not sedated techniques; awake and relaxed techniques using certified child life specialists, animal-assisted therapy, a child-friendly environment and in-scan entertainment; and non-sedated MRI protocol modifications such as shorter scan time, prioritizing sequences, reducing motion artifact, noise reduction, limiting use of gadolinium, employing an open MRI and modifying protocols.

Background Image-guided surgery with an open magnetic resonance imaging (MRI) system is applied for brain tumors in the neurosurgery field, but has rarely been reported in pediatric surgery. We report our initial experience of intraoperative confirmation of precision rectal pull-through during laparoscopically assisted anorectoplasty (LAARP) in an open MRI operating theater for pediatric patients with anorectal malformation (ARM). Case presentation A 3.0 kg term male neonate was delivered with anorectal malformation. An invertogram revealed the intermediate type. Transverse colostomy was made on the left upper abdomen. The recto-bulbar urethral fistula (RBUF) was diagnosed by a distal colostogram and voiding cystourethrogram. LAARP was planned at 6 months of age. Because this was the first procedure in which the pediatric abdomen had been scanned in an open MRI operating theater in our institution, we scanned his pelvic floor under sedation 3 weeks before the operation using the open MRI system in our operation room. We performed the operation with 4 trocars. The peritoneal reflection was carefully incised and the rectum was dissected. The RBUF was resected. The center of the muscle complex was detected at the perineal skin with an electrical nerve stimulator, and a 7-mm longitudinal skin incision was made on the perineal lesion for anoplasty. The muscle complex and the pubo-rectal sling were confirmed laparoscopically using a 3.5-mm bipolar forceps connected to the electrical nerve stimulator. Anoplasty was performed between the rectal stump and perineal skin. After anoplasty, the patient was scanned with open MRI under general anesthesia. We attached the quadrature-detection (QD) head coil around the patient’s pelvis and inserted him in the gantry. A 0.45-T open MRI clearly revealed that the pulled through rectum was located in the center of the muscle complex on T2-weighted images. The postoperative course was uneventful. Oral intake was started on post-operative day 1. Postoperative dynamic urography showed no complication (e.g., leakage or residual fistula). Conclusions We successfully performed LAARP for ARM, with intraoperative confirmation of precision rectal pull-through in an open MRI operating theater. Further cases are required to evaluate the application of open MRI systems in pediatric surgery.

In this study, the radio-frequency (RF) energy exposure of patient assistants was assessed for an open magnetic resonance imaging (MRI) system based on numerical computations of the head and body RF coil. Various poses of the patient assistants were defined to see how poorly they affected the RF energy exposure. For the assessments, the peak spatial-averaged specific absorption rate (SAR) levels were carefully compared with each patient assistant pose based on the finite-difference time domain calculations of RF coil models when the patient was placed in such coils in a 0.3 Tesla open MRI system. Overall, the SAR levels of the patient assistant were much lower than those of the patient. However, significantly increased SAR levels were observed under specific conditions, including a larger loop size of the patient assistants’ arms and a closer distance to the RF coils. A comparably high level of SAR to the patient’s body was also found. More careful investigations are needed to prevent the increase of SAR in patient assistants for open MRI systems at higher field strengths.

BACKGROUND: The purpose of this study was to evaluate the flexion-gap of the native knees in the normal population and to assess any gender-specific variations in the flexion gap of the knees. METHODS: A total of 50 normal asymptomatic volunteers with normal knee radiographs were selected for MRI of the knee. The left knee was scanned in an open MRI using a T1-weighted sequence. Imaging was performed in neutral, passive varus and valgus stress at 90° of knee flexion by placing custom-made blocks on a special board consecutively below the distal part of the leg. RESULTS: The study population consisted of 26 males and 24 females with a mean age of 25.77 years. Under varus stress, the mean lateral flexion gap increased to 9.28 ± 1.53 mm and under valgus stress, the mean medial flexion gap increased to 2.75 ± 1.22 mm from neutral. The increase in the flexion gap on the lateral side was 5.28 ± 1.79 mm, which was significantly higher compared to that on the medial side. In gender-specific analysis, the mean lateral flexion gap was 10.21 mm in females and 8.46 mm in males under varus stress. CONCLUSION: The findings of the study indicate that the lateral soft tissues are more lax compared to the medial soft tissue structures and this laxity is higher in females as compared to males. The study provides evidence of the existing physiological variations of these soft tissue structures resulting in a trapezoidal flexion gap in the native knees rather than the recommended rectangular gap.

Pelvic floor disorders are a major healthcare problem, which frequently present with nonspecific symptoms such as constipation or incontinence making a correct diagnosis through clinical evaluation alone difficult. In recent years evaluation of the pelvic floor with magnetic resonance imaging (MRI) has become an integral part of the multidisciplinary workup of patients with functional disorders of the pelvic floor. The high-quality multiplanar soft tissue contrast of MRI is used to depict anatomical alterations, and dynamic cine acquisitions allow a real-time functional evaluation of the pelvic floor mobility at the same time. However, correct acquisition of dynamic pelvic floor MRI remains challenging as availability of open MRI systems are limited and several factors need to be taken into account while performing MRD in a closed configuration MRI system. This chapter gives information about patients’ preparation, positioning, and an overview on how to perform and interpret dynamic pelvic floor MRI.

Medial patellofemoral ligament (MPFL) reconstruction has become a common form of treatment for recurrent patellar dislocation. This study was performed using open-MRI to compare the length change pattern of MPFL in patients with a history of patellar dislocation to that in healthy subjects.The subjects comprised 10 knees of 8 males and 13 knees of 12 females with a history of one or more patellar dislocations. The length of the MPFL was measured using open-MRI in both the leg-extended position and knee-flexed positions to analyse the length change pattern.The average MPFL lengths were 58.6 ± 6.5 mm and 52.0 ± 4.6 mm for males and females in the extended knee position, respectively. The length change pattern of the MPFL showed slight variation up to a flexion angle of 30° and a clear decrease above 30°. This pattern differed from that of normal MPFL. In terms of morphology, the fibre bundle of the damaged MPFL followed a convex course towards the side of the patellofemoral joint surface at a knee flexion angle of 60°, whereas that of the normal MPFL followed a straight course.The in vivo damaged MPFL length change pattern was specific and differed distinctly from that of normal MPFL. The results of the present study suggested that MPFL fibres with a history of patellar dislocation lack sufficient tension at knee flexion angles of 0°-60°. However, further studies are needed to obtain a better understanding of cases with a patellar dislocation or postsurgical cases of MPFL reconstruction.III.

Background: Low-field (LF) magnetic resonance imaging (MRI) is a technology that is widely used in resource-limited settings for clinical imaging. The images produced, even though of low resolution with noise and artefacts, provide valuable information and guidance for patient assessment and treatment. This study shows a spectrum of MRI artefacts that affect image quality during routine clinical neuroradiology practice using LF MRI in a Nigerian hospital and suggests ways to avoid them. Materials and Methods: We retrospectively reviewed brain and spine MRI studies performed on a 0.36T MagSense 360 (Mindray, China) open MRI at our hospital over a 2-year period to identify image artefacts. About 90% of MRI studies performed at our facility during the study period were neuroimaging. The pattern and distribution of artefacts that featured during imaging were described and illustrative cases demonstrated highlighting their causes and ways to avoid or limit them. Results: Of 936 brain and spine cases evaluated, 506 (54.1%) had artefacts with 369 (72.9%) seen in the brain. Truncation/Gibbs (37.6%) and motion (20.6%) were the most common artefacts in the series, seen most commonly in T2-weighted images. There was no significant difference in the proportion of artefacts between adults and children (P = 0.736). Conclusion: Artefacts are relatively common in neuroimaging with LF MRI and may potentially degrade image quality and interfere with accurate radiological reporting and diagnosis. Improving the recognition of LF MRI artefacts may assist imaging practitioners to avoid or limit their effect on image quality and interpretation.

Place: Germany; Recent anatomical and radiological studies of the anterior cruciate ligament (ACL) suggest the ACL length and orientation change during knee flexion, and an open MRI sequencing during knee flexion enables a dynamic ACL analysis. This study's goal is to describe a normal ACL using a 1T open MRI and, in particular, variations in length and insertion angles at different degrees of flexion. Twenty-one volunteers with clinically healthy knees received a dynamic MRI with their knees in hyperextension, neutral position, and flexed at 45° and 90° angles. For each position, two radiologists measured the ACL lengths and angles of the proximal insertion between the ACL's anterior edge and the roof of the inter-condylar notch. Additionally, we measured the ACL's and the tibial plateau's distal angle insertion between their anterior edges and then compared these with the nonparametric Wilcoxon test. The ACL had a significant extension between the 90° flexion and all other positions (hyperextension: 31.75 ± 2.5 mm, neutral position: 32.5 ± 2.6 mm, 45°: 35.6 ± 1.6 mm, 90°: 35.6 ± 1.6 mm). There was also a significant increase of the angle insertion between the proximal 90° flexion and all other positions, as well as between hyperextension and bending to 45° (hyperextension: 2.45° ± 3.7°, neutral: 13.4° ± 9.7°, 45°: 33 25 ± 9.3, 90: 51.85° ± 9.3°). Additionally, there is a significant increase in the distal angle insertion for all positions (hyperextension: 133.2° ± 5.4°, neutral position: 134.95° ± 4.4°, 45°: 138.35° ± 5.9°, 90°: 149.15° ± 8.6°). Our study is the first to exhibit that a dynamic MRI has a significant ACL extension in vivo during bending. This concept opens the way for further studies to improve the diagnosis of traumatic ACL injuries using a dynamic MRI.

Recurrent patellar dislocation is currently treated with anatomical reconstruction of the medial patellofemoral ligament (MPFL), and favourable postoperative outcomes have been reported. However, it is uncertain if healthy MPFL function is restored by anatomical reconstruction. The hypothesis in this study was that stabilization of the patella following MPFL reconstruction would be improved compared with that before surgery, but that function of the grafted tendon would differ from that of a healthy MPFL. The objective was to analyse the length change patterns of the MPFL before surgery and the grafted tendon after surgery in patients with recurrent patellar dislocation treated with anatomical MPFL reconstruction. The subjects were 12 patients (13 knees) in whom recurrent patellar dislocation was treated with anatomical MPFL reconstruction. The length change patterns of the MPFL and reconstructed ligament were analysed at extension and flexion of the knee joint using open MRI. The postoperative grafted tendon length was significantly shorter than that of the preoperative MPFL at knee extension, and significantly longer at 90° and 120° of knee flexion. The postoperative length of the grafted tendon only changed slightly from 0° to 30° of knee flexion, and then significantly decreased at flexion of 30° or more. The morphology of the grafted tendon was linear until 60° knee flexion, but became convex toward the extraarticular side at flexion of 90° or more. The grafted tendon length at knee extension was shorter than that of the preoperative MPFL, but there was no significant difference at 30° flexion. These findings suggest that the effect of damping of the patella with a grafted tendon after MPFL reconstruction may differ from that in a healthy knee. In addition, the morphology at 60° knee flexion was improved to linear after surgery, suggesting that ligament morphology at this flexion was normalized by MPFL reconstruction. III.

Purpose: T1WI (T1 weighted image) was acquired in order to grade bone fusion following the studies by FIFA (Federation Internationale de Football Associations). Research using images other than T1WI has not been reported. The aim of this study is to evaluate the grade of epiphyseal fusion by T2* weighted images (T2*WI) and to investigate new findings on T2*WI as compared with T1WI. Methods: A total of 87 subjects, all junior football players between the ages of 12 and 17 years old, were examined. T1 and T2* WI were obtained using a 1.2T Open type MR system. The T1WI and T2*WI were rated twice randomly by four radiologists using the FIFA grading system. Results: The intra-rater reliability for grading was higher in T1WI (The Intraclass Correlation Coefficient (ICC)=0.949-0.985) than in T2*WI (ICC=0.917-0.943). The inter-rater reliability for grading was also higher in T1WI (ICC=0.923) than in T2*WI (ICC=0.867). Conclusions: This research showed that T1WI is a better sequence than T2*WI to evaluate bone fusion following FIFA protocol. It was speculated that the reason for this is that T1WI has higher tissue contrast resolution and enables clearer images of the epiphyseal fusion than T2*WI and the grading system by T1WI was not suitable for T2*WI.

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 T1-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 T1-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. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.

Aim: In the assessment of meniscal tears, diagnostic accuracy of 0.2 Tesla (T) magnetic resonance imaging (MRI) was investigated and compared with arthroscopy as standard of reference. Method: 340 patients suspected with meniscal tears were examined by 0.2 Tesla open MRI unit. 47 of the patients underwent arthroscopy. The arthroscopy results were compared with interpretations of MRI retrospectively. Result: In detecting meniscal tears with 0.2 T MRI, sensitivity, specificity and diagnostic accuracy were 90%, 88,2%, 89,4% for medial meniscal tears and 91%, 91,6%, 91,5% for lateral meniscal tears, respectively. Conclusion: O.2 T MRI is effective in detecting meniscal tears and can be safely use in detecting the meniscal pathologies.

Purpose: This study was performed to introduce and evaluate the potential of kinematic magnetic resonance imaging (KMRI) using a high-field openmagnet magnetic resonance (MR) system. Methods: We attempted to perform KMRI of healthy volunteers’ lumbar spine and knee in the lateral position and ankle in the supine position utilizing the superconducting, horizontally opened, 1.2 T MR system (OASIS, HITACHI, Tokyo, Japan). For the KMRI of the lumbar spine, the volunteer had to lie on one side while maintaining maximally anteflexed, neutral, and maximally retroflexed positions and remain still for the duration of the acquisition time for each posture. In the same way, KMRI of the knee was performed with the volunteer’s knee flexed at 0o, 30o, 60o, 90o, and 120o in the lateral position, and KMRI of the ankle was performed with the volunteer’s ankle in maximally dorsiflexed, neutral, and maximally plantarflexed positions while lying in the supine position. Results: We could acquire higher quality kinematic MR images than those acquired using low-field MR systems. The spinal canal, intervertebral discs and foramina, and facet joints in lumbar spine KMRI; the ligaments, menisci and patellofemoral joint in knee KMRI; and the tibiotalar articulation and peroneal tendon in ankle KMRI were clearly depicted. Conclusion: The results of our pilot trial indicated that a superconducting horizontally opened, 1.2 T MR system offers high-quality KMRI images and can be utilized for the kinematic diagnosis and evaluation of sports injuries.

To evaluate the feasibility and safety of a novel LITT applicator for thermal ablation of liver malignancies in 1.0-T high-field open MRI.A miniaturised 6-F double-tubed protective catheter with a closed cooling circuit was used with a flexible laser fibre, connected to a 1,064-nm Nd:YAG laser and evaluated in non-perfused porcine livers (18-30 W for 10-20 min, 2-W and 2-min increments; n = 210/applicator) in reference to an established 9-F system. As a proof of concept, MR-guided LITT was performed in two healthy domestic pigs in high-field open MRI.Ex-vivo, the coagulation volumes induced by the 6-F system with maximum applicable power of 24 W for 20 min (33.0 ± 4.4 cm(3)) did not differ significantly from those set with the 9-F system at 30 W for 20 min (35.8 ± 4.9 cm(3)) (p = 0.73). A flow-rate of 15 ml/min of the cooling saline solution was sufficient. MR navigation and thermometry were feasible.The miniaturised 6-F applicator can create comparable coagulation sizes to those of the 9-F system. Applicator guidance and online-thermometry in high-field open MRI are feasible.

Hip ganglion is considered a cause of persistent hip pain, but there have been few reports about therapy for hip ganglion. We report two patients with hip ganglion who underwent aspiration using interactive imaging monitoring with open magnetic resonance imaging (MRI). This procedure facilitated accurate aspiration, and allowed us to confirm volume reduction of the ganglion. One year after the aspiration, there has been no re-accumulation of the ganglion on MRI, and the patients have achieved complete pain relief. The present procedure with open MRI shows promise as a conservative treatment for hip ganglion.

Purpose: To describe the in vivo appearance of magnetic resonance imaging (MRI) diskograms of normal and degenerated lumbar intervertebral disks, and to evaluate the differences in imaging findings between sequential diagnostic MRI and MRI diskography. Material and Methods: Nine consecutive patients underwent MRI-guided diskography in order to determine possible pain provocation during puncture and contrast medium injection. All patients had preceding clinical suspicion of lumbar diskogenic pain and findings of lumbar disk degeneration in diagnostic (MRI, computed tomography (CT), plain radiography). A 0.23T open MRI scanner with interventional tools was used for imaging and instrument guidance. On all patients, a complementary diagnostic MRI study of the lumbar spine before and after the MRI-guided disk injection was performed, and subsequent axial MRI diskograms were obtained. Results: A total of 25 disk punctures were initialized, and 25 MRI diskograms were obtained and their expression described. There was a correlation between the degenerative disk findings visualized by diagnostic MRI and MRI diskograms. Conclusion: The use of gadolinium contrast media in MRI-guided diskography enables the evaluation of MRI diskograms. Our results suggest that MRI-guided diskography can be used to substitute conventional diskography or CT-diskography and as an augmenting method to assess diagnostic information upon degenerative processes of the lumbar spine.

The purpose of this study was to develop a new technique for diffusion-weighted MRI (DWI) with a low-field scanner. DWI is becoming important for assessment of acute stroke. Until recently DWI required expensive technology. We developed multishot-DWI sequence for 0.3T open type MR imager. We prospectively studied forty patients on this 0.3T MRI and compared this DWI to single-shot-DWI by 1.5T-MRI. Group A: Twenty-four patients with acute cerebral infarctions detected by 1.5T-DWI were re-examined using 0.3T-DWI within 24 hours. Sixteen patients with acute cerebral infarctions detected by 0.3T-DWI were re-examined using 1.5T-DWI within 24 hours. In 22 (92%) of 24 cases, 0.3T-DWI showed high signal. In the other two patients, motion artifact distorted 0.3T-DWI. Group B: In all 16 patients, all infarctions detected by 0.3T-DWI showed high signal on 1.5T-DWI. These preliminary data show that, as long as the patient is able to keep still, multishot-DWI can be acquired successfully on a 0.3T open type MRI system.

When performing surgery for malignant brain tumor that is close to pyramidal tract, it is an important issue how to preserve motor function. While diffusion tensor (DT) imaging on magnetic resonance imaging (MRI) can visualize course of nerve bundle, surgical navigation based on preoperative image may have considerable position error because of brain shift. We visualized pyramidal tract by intraoperative diffusion weighted (DW) imaging using 0.3T open MRI in tumor removal close to the fiber and performed surgery using the navigation based on the image. The surgeon was able to perform surgery confirming pyramidal tract localization corresponding to brain shift demonstrated on the navigation image.

Malignant brain tumors vary among patients and are characterized by their irregular shapes and infiltration. Localization of functional areas in the brain also differs among patients, and excess removal of tumor near eloquent areas may increase the risk of damage of function, such as motor paresis and speech disturbance. Recent progress in magnetic resonance (MR) imaging technology has enabled acquisition of intraoperative images and totally changed the neurosurgery of malignant brain tumors. Before, surgeons could merely speculate about the results of surgical manipulation and have no certainty about procedure outcomes until postoperative examination. Because intraoperative MR images allow visualization of the size of residual tumor(s) and the positional relationship between the tumor(s) and eloquent areas, surgeons are now able to achieve safe and reliable surgery. As an example, positional error on preoperative MR images caused by shifting of the brain (brain shift), a long-standing annoyance for surgeons, has been resolved using intraoperative MR images for surgical navigation, allowing precise resection. Two types of open-MR imaging scanner, a 0.2- or 0.3-tesla hamburger-type scanner with a horizontal gap and a 0.12- or 0.5-tesla double doughnut-type scanner with a vertical gap, are now available in the operating theater, and 1.5-tesla bore-type scanners are available. A 3.0-tesla bore-type scanner is planned. Intraoperative MR imaging includes diffusion-tensor and diffusion-weighted imaging, which allows visualization of nerve fibers in the white matter, especially the pyramidal tract. Such images are valuable aids in the precise resection of residual lesions of malignant brain tumors near eloquent areas without injuring motor function.

Varus and valgus joint laxity of the normal living knee in flexion was assessed using MRI. Twenty knees were flexed to 90° and were imaged in neutral and under a varus-valgus stress in an open MRI system. The configuration of the tibiofemoral joint gap was studied in slices which crossed the epicondyles of the femur. When a varus stress was applied, the lateral joint gap opened by 6.7 ± 1.9 mm (mean ± sd; 2.1 to 9.2) whereas the medial joint gap opened by only by a mean of 2.1 ± 1.1 mm (0.2 to 4.2). These discrepancies indicate that the tibiofemoral flexion gap in the normal knee is not rectangular and that the lateral joint gap is significantly lax. These results may be useful for adequate soft-tissue balancing and bone resection in total knee arthroplasty and reconstruction surgery on ligaments.

In surgical removal of a malignant brain tumor, which is close to a pyramidal tract, diffusion tensor images obtained by preoperative magnetic resonance imaging (MRI) can display the spatial relationship between the tumor and the pyramidal tract. This image, however, is not appropriate to navigate the surgery because of brain shift due to surgical manipulation. We developed a navigation system employing intraoperative diffusion weighted imaging (DWI) using open MRI, which is the first trial with a 0.3 T scanner to aim at complete removal of cerebral tumors. A newly developed surgical coil has both functions of head fixation in surgery and a receiver coil in scan. The DWI of volunteers could display nerve fibers such as pyramidal tracts and corpus callosum under the optimized scan parameters. By refining navigation software, a physical position directed by the pointing device could be displayed correctly on three cross-sectional T1 (or T2) weighted images and three-dimensional (3D) DWI. Initial clinical evaluation of this system revealed that the spatial relationship between the tumor, the pyramidal tract, and the treatment position could be displayed correctly. Furthermore, the surgeons could recognize these positions intraoperatively and visually. The navigation system employing intraoperative DWI for a tumor and nerve fibers helped the surgeons remove the tumor and obviated postoperative disturbance such as motor paralysis.

Fragestellung: Ziel der experimentellen Studie war die quantitative Evaluierung der Meniskusbewegung und -verformung in vivo unter Gewichtsbelastung. Methode: Sagittale T1-gewichtete MRT-Bilder von 15 gesunden Kniegelenken wurden ausgewertet. In einem offenen MR wurden die Probanden so platziert, dass eine Messung unter Belastung und in verschiedenen Beugegraden moglich war. Es wurden Bilderserien vom Innen- und Ausenmeniskus ohne Belastung, mit halbem und vollem Korpergewicht angefertigt. Alle Aufnahmen erfolgten in voller Streckung und in 30°-Beugung. Zwei Untersucher masen je zweimal die Hohe des Hinterhorns und den inneren und auseren Abstand zwischen Vorder- und Hinterhorn der Menisken. Ergebnisse: Die Hohe des Innen- und Ausenmeniskushinterhorns nahm unter zunehmender Gewichtsbelastung ab. Innen- und Ausenabstand nahmen unter Gewichtsbelastung zu. Hierbei nahm der Innenabstand starker zu als der Ausenabstand, was eine Kompression der Peripherie bedeutet. Zunehmende Flexion von 0 auf 30° hatte nur auf den Ausenabstand signifikanten Einfluss. Schlussfolgerungen: Die Methode kann in Zukunft zur funktionellen, postoperativen Nachkontrolle bei verschiedenen meniskuserhaltenden oder -ersetzenden Therapieverfahren eingesetzt werden. Die nachgewiesene Kompression der Meniskusperipherie von innen nach ausen bei Belastung in voller Extension erlaubt die fruhe postoperative Mobilisation nach Meniskusnaht. Aim: The aim of this experimental study was a quantitative evaluation of meniscal movement and deformation in vivo under load bearing conditions. Methods: Sagittal T1-weighted MRI pictures of 15 healty knees were evaluated. The subjects were placed in an open MRI, that enabled measurements under load bearing and in different flexion grades. Series of pictures of the medial and lateral meniscus without load, with half and full body weight load and in full extension and 30° flexion were taken. Two examiners measured twice the height of the posterior horn, and the inner and outer distance between the anterior and posterior horns of the menisci. Results: The height of the posterior horns of the medial and lateral menisci decreased with increasing load. The inner and outer distance increased with load, the inner distance more than the outer, resulting in a compression of the periphery. Increase of flexion from 0° to 30° significantly influenced only the outer distance of both menisci. Conclusion: This method can be used in future to functionally evaluate the postoperative result after meniscus saving or replacing therapies. The compression of meniscal periphery from the inside to the outside under load in full extension allows early postoperative mobilisation after meniscal sutures.

We would propose a novel mechanism of a surgical manipulator, which works in Open MRI guided surgery and assists surgeon (s) in precise positioning and handling of surgical devices. This mechanism can transmit 3 translational and 3 rotational motions from the outside to the inside of MR imaging area by using leverage and parallelogram mechanism. Such a remote actuation is significantly helpful because the strong and sensitive magnet of MR denies the accessibility of magnetic and electric devices and materials to the imaging area. In this paper, the basic ideas of mechanism were introduced and its forward and inverse kinematics was formulated firstly. Secondly, a non-MR-compatible prototype was made to reveal mechanical problems. Thirdly, the workspace of the prototype was numerically analyzed. Fourthly, the stiffness of the prototype was experimentally evaluated. These results concluded trade-off between stiffness and workspace. Fifthly, our new idea of workspace control for mechanical safety was preliminary discussed.

Solid tumors are being treated using radiofrequency (RF) ablation under interventional magnetic resonance imaging (MRI) guidance. We are investigating the ability of MRI to monitor ablation treatments by comparing MR images of thermal lesions to histologically assayed tissue damage.An open MRI system was used to guide an ablation electrode into five rabbit thigh muscles and acquire post-ablation MR image volumes. We developed a methodology using a 3D computer registration to make spatial correlations. After MR and histology images were registered with an accuracy of 1.32+/-0.39 mm (mean+/-SD), a boundary of necrosis identified in the histology was compared with the outer boundary of the hyperintense region in MR images.For 14 T2-weighted MR images, the absolute distance between boundaries was 0.96+/-0.34 mm (mean+/-SD). Since the small discrepancy between boundaries is comparable to our registration accuracy, the boundaries may match exactly. Similar correlations to histology were obtained with a deformable model segmentation method.This is good evidence that MR thermal lesion images can be used during RF ablation treatments to accurately localize the zone of necrosis at the lesion margin.

AIM There are only a few diagnostic or therapeutic procedures where MR imaging is applied during pediatric interventions. This study will describe indications, complications as well as the advantages and disadvantages of MRI-guided interventions based on a case study in an open MRI scanner. MATERIALS AND METHODS 14 procedures were performed in an open MRI scanner (Signa SP/i, GEMS) on 13 children (1 - 16 yr) with bone, soft tissue and brain lesions (1 - 4 cm diameter). Localization of the pathology, targeting and final control of the result were based on images acquired with SE-, 3D-, GE-sequences pre- and post-contrast as well as FSE-sequences. Interactive MRI-guided instrument navigation was performed using a multiplanar T1w GE-sequence. RESULTS Eight biopsies (incl. 1 rebiopsy), two tumor resections, one removal of a free joint mouse and three tumor-markings were performed without complications. Five biopsies provided appropriate sample quality for a histological diagnosis while two samples were too fragmented requiring a second biopsy (one of them MRI-guided). Surgical progress during tumor resection and marking could be controlled during the intervention without repositioning the patient. DISCUSSION MR image guided pediatric interventions combine the advantage of an imaging system without ionizing radiation and the high soft-tissue contrast. The low number of these kinds of procedures can be explained by the relatively high costs for the intervention, the increased duration for each procedure and the limited availability of open MRI systems. The integrated localization-system helps during planning of the access path when facing complex anatomical structures and provides safe navigation in sensitive regions like the epiphyseal cartilage. Recent and expected developments of the required MR-compatible biopsy instruments could provide higher efficiency for appropriate sample size and quality. Summarizing, MRI-guided pediatric interventions have shown to be a promising method at the beginning of its development.

BACKGROUND: It is currently recommended that helmet and shoulder pads remain in place during the initial clinical and radiographic evaluation of the helmeted athlete with a potential cervical spine injury. The objective of this prospectively designed, single-subject study was to determine whether MRI may play a role in the initial evaluation and management of the helmeted football player with a cervical spine injury. METHODS: One male athlete was fitted using equipment (football helmet [Riddell], shoulder pads [Douglas]) worn during the collegiate season at Lehigh University. Standard MRI using a routine clinical 0.7 T high field open MRI scanner (GE Signa System, Milwaukee, WI) was employed for the evaluation using standard clinical parameters (sagittal T1, fast spin echo [FSE] T2, STIR, and axial FSE T2 series). A single board-certified, fellowship-trained neuroradiologist reviewed all series. Studies were evaluated for image clarity and diagnostic capability in this clinical setting. RESULTS: All standard MRI series were of extremely limited quality, even using sequences and slice selection designed to minimize artifact associated with metals (FSE T2-weighted series). When all MRI series were reviewed as a whole, sufficient evidence was not available to allow clinical decision making. CONCLUSIONS: The amount and type of metal within the standard football helmet and shoulder pads result in sufficient field inhomogeneity and SKEW artifact to preclude adequate evaluation of the cervical structures, rendering MRI evaluation in this setting not clinically useful. This study shows that current MRI techniques play no role in the clearance of the cervical spine (with currently available brands of helmet and shoulder pads in place) without prior equipment removal or manipulation. Language: en

Summary A new device has been developed for planning, guiding and performing image guided stereotactic procedures. The burr hole mounted device is made of biocompatible composite (polyacetal) and consists of a probe holder within a ball-and-socket joint, to which a light-emitting diode reference stage is attached. In combination with intraoperative, near real-time imaging, this system aids in targeting burr hole entry points and trajectories. The open intraoperative MR (Signa SP, General Electric) used in this series fuses the anatomical space with imaging space and time space and transforms a “blind” stereotactic procedure into a visually controlled one. Planning and performing stereotactic interventions become a single step procedure without using registration, frames and fiducials. The snapper-stereoguide has been evaluated in more than 300 stereotactic procedures including biopsies, evacuations of cysts, abscesses, hematomas, insertion of laser fibres for laser induced interstitial thermotherapy (LITT) and guiding endoscopes. Although evaluated in an open MRI unit, this system could be used in all image guided procedures involving direction of a stereotactic instrument. On the basis of this clinical series this artefact free and frameless device for near real time stereotactic procedures proved to be easy to use, fast, accurate and safe. Taking into account the amount of brain and target shift observed in 30% of the procedures in this series, the dynamic accuracy of near real time MR imaging is not surpassed by any other system. The combination of the snapper-stereoguide and the OIMR was found to be a very helpful alternative to all currently used direct and indirect, frame-based and frameless systems.

Background and study aims. MRI-guided procedures combine high-quality imaging with lack of radiation. Percutaneous transhepatic cholangiodrainage under real-time MRI guidance (MRI-PTCD) seems promising, allowing targeted puncture and avoiding multiple blind passes and use of contrast, which are associated with standard PTCD’s heaviest complications. Patients and methods. Aim of this study was to investigate the feasibility of MRI-PTCD in three outbred piglets. Obstructive cholestasis was induced by common bile duct ligation. Two days later, MRI-PTCD was performed (open MRI, 1.0 Tesla) with prototype MRI-compatible accessories. Visualization was achieved with a balanced steady-state free precession real-time sequence (bSSFP: 0.75 frames/s, TR/TE [ms]: 7.2/3.6; flip angle: 45; 200 200 matrix size; resolution: 1.3 1.3 mm 2 , slice thickness: 7 mm). Cannulation of the bile ducts was followed by placement of Yamakawa drainages. Results. Twelve punctures were performed (four per animal, 10/12 successful); in 2/10 the bile ducts could not be cannulated. Animal survival was 100% and no significant complications occurred. Conclusions. Initial data show that MRI-PTCD can be successfully performed. This may lead to establishment of a new optimized PTCD technique compared to the standard approach under fluoroscopy.

The evaluation of the glenohumeral joint laxity requires the estimate of displacements of the humeral head centre (HHC) with respect to the glenoid. To the authors׳ knowledge, several studies have been conducted to estimate HHC translations in vivo but data under anterior loading conditions has not been collected yet. Aim of this study was to develop a non-invasive experimental methodology based on magnetic resonance (MR) imaging for the in vivo evaluation of the HHC translations due to an anteriorly directed force. Fourteen asymptomatic shoulders were acquired using a horizontal open MR scanner with the subjects in the supine position both at 15° and 90° of arm abduction with and without an anterior force of 20 N applied at the HHC level. When no load was applied, from 15° to 90° of arm abduction, the HHC moved, anteriorly (1.5±1.3 mm) and superiorly (1.8±1.3 mm) while smaller displacements were observed medio-laterally (0.4±0.7 mm). Under the application of the anterior force the 3D displacement of the HHC with respect to the glenoid was 1.6±1.2 mm and 1.3 ±0.7 mm, respectively at 15° and 90° of arm abduction. The level of precision associated to the GHJ translation was less than 0.33 mm along all directions i.e. one order of magnitude smaller than the relevant translations. In conclusion, the MRI-based methodology allowed for the analysis of HHC displacements under conditions of anterior loads within an acceptable level of reliability.

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, signalto-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 MRguided 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.

Summary Introduction: Extratruncular, infiltrating congenital vascular malformations (CVM) are found in all organ systems. Large substance defects and diffuse blood loss may occur during surgical removal. Thus, conservative and interventional procedures are also applied, one of them being interstitial laser therapy (ILT). Patients and methods: Forty children with deep CVM underwent interstitial laser therapy with open MRI. The laser light guide was introduced into the malformation with a titan puncture needle and the tissue was thermically damaged by adequate selection of the physical parameters of the Nd:YAG 1064-nm laser. Beside the high soft-tissue contrast, MRI has the advantage of thermosensibility. For online thermomonitoring, we used 3 time-optimized MR sequences with a maximal velocity of 1 image in 3 seconds. Results: Positioning of the puncture needle was excellent in all applications and thermomonitoring was successful in 89%. A reduction of the tumor volume was observed in 36 patients at the 6-week follow-up. The volume of the malformations was reduced to 76%, on the average. Clinical improvement was seen in 78% of the cases. One fifth of the children are presently without symptoms. Thermic skin damage in 2 cases and intracorporal bare fiber tip loss in 1 case was found to be a complication. Discussion: Process control is decisive for successful interstitial laser therapy. Beside the high soft tissue contrast, MRI is characterized by a thermosensibility which does not allow invasive registration of temperature changes provoced by ILT inside the body. Summary: The introduction of open MR systems has enabled access to patients and interactive management directly in the magnetic field. MR-controlled interstitial laser therapy has to be included in the differential treatment of complicated congenital vascular malformations.

Information-guided stereotaxis, assisted by visualization of medical information, will become the next generation of neurosurgical systems. We performed 76 open MRI surgeries at Tokyo Women’s Medical University between March 3, 2000 and April 12, 2001. Of them, comparisons of pre- and post-operative MR images for malignant gliomas in 21 cases revealed an average resection rate of 90.3% (the maximum 100%, the minimum 55%). In this article we describe real time updated navigation, augmented reality navigation, three-dimensional navigation, chemical navigation, information-guided navigation system (High definition visual Computer Aided Surgery System: HivisCAS), and open MRI-guided surgery that we are developing.

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 T 1 -weighted gradient echo sequences in the breath-holding technique. In the first follow up after 24-48 hours, a contrast-enhanced T 1 -weighted gradient-echo sequence was performed in an MRI scanner at 1.5 T. The pre-, intra- and post-interventional 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.

OBJECTIVE: A new, artifact-free, nonobstructive device was required for planning, guiding, and performing stereotactic procedures in an open magnetic resonance imaging (MRI) system (Signa SP; General Electric, Milwaukee, WI). DESCRIPTION OF INSTRUMENTATION: We devised an MRI-compatible instrument set that was adapted to an optical triangulation system (FlashPoint System; Image Guided Technologies, Boulder, CO) and consisted of a Pathfinder for planning burr holes and trajectories and a Snapper-Stereoguide for guiding minimally invasive instruments such as biopsy cannulae, endoscopes, and laser fibers. The instruments were composed of biocompatible plastic (polyacetal). During evaluation, special attention was paid to safety, accuracy, operation times, and susceptibility artifacts of the system. RESULTS: The first 20 stereotactic procedures performed in the open MRI scanner included 15 biopsies, 1 cyst and 3 abscess evacuations, and 1 endoscopic procedure for treatment of multiseptate hydrocephalus. There were no adverse outcomes, and all biopsies were diagnostic. The frameless stereotactic system in combination with the FlashPoint System proved to be accurate, with a mean error of 1.5 mm. The biopsy devices did not cause any susceptibility artifacts. Highly vascularized structures were clearly visible and were included in the trajectory planning. With experience, the procedure time was reduced to less than 1 hour. CONCLUSION: This device was found to be quite helpful for planning and guiding stereotactic procedures in the open MRI scanner. Nearly real-time planning and monitoring of stereotactic procedures and the positional accuracy of the system make the open MRI system a definite improvement, compared with conventional stereotactic systems.

One of the questions on the IMS 2005 Quiz, is related to the magnetic fields used in magnetic resonance imaging (MRI) machines. In particular, it asked: an MRI (magnetic resonance imaging) machine uses: a) high-intensity static magnetic fields; b) time-varying magnetic fields in the kHz range; c) radio-frequency (RF) fields in the MHz range; and d) All of the above. The correct answer, d) All of the above, highlights the fact that an MRI machine employs all three types of fields in order to accomplish three-dimensional imaging for medical diagnostics. Therefore, in terms of safety, electromagnetic field exposure to patients and medical personnel needs to be assessed for all three types of fields. This is a much greater concern for open MRI systems, where the magnet surrounds the patient only partially in order to allow the medical personnel to perform procedures on the patient, guided by the MRI images. The IEEE Committee on Man and Radiation (COMAR) is in the final stages of preparing a technical information statement (TIS) on the subject.

PURPOSE: We aimed to detect possible differences in microwave ablation (MWA) volumes after different fluid preinjections using magnetic resonance imaging (MRI). MATERIALS AND METHODS: MWA volumes were created in 50 cuboid ex vivo bovine liver specimens (five series: control [no injection], 10 mL water, 10 mL 0.9% NaCl, 10 mL 6% NaCl, and 10 mL 12% NaCl preinjections; n=10 for each series). The operating frequency (915 megahertz), ablation time (7 min), and energy supply (45 watts) were constant. Following MWA, two MR sequences were acquired, and MR volumetry was performed for each sequence. RESULTS: For both sequences, fluid preinjection did not lead to significant differences in MWA ablation volumes compared to the respective control group (sequence 1: mean MWA volumes ranged from 7.0±1.2 mm [water] to 7.8±1.3 mm [12% NaCl] vs. 7.3±2.1 mm in the control group; sequence 2: mean MWA volumes ranged from 4.9±1.4 mm [12% NaCl] to 5.5±1.9 mm [0.9% NaCl] vs. 4.7±1.6 mm in the control group). The ablation volumes visualized with the two sequences differed significantly in general (P < 0.001) and between the respective groups (control, P ≤ 0.001; water, P < 0.001; 0.9% NaCl, P < 0.001; 6% NaCl, P ≤ 0.001; 12% NaCl, P < 0.001). The volumes determined with sequence 1 were closer to the expected ablation volume of 8 mL compared to those determined with sequence 2. CONCLUSION: For the fluid qualities and concentrations assessed, there is no evidence that fluid preinjection results in larger coagulation volumes after MWA. Because ablation volumes determined by MRI vary with the sequence used, interventionalists should gain experience in how to interpret postinterventional imaging findings (with the MR scanner, sequences, and parameters used) to accurately estimate the outcome of the interventions they perform.

Objectives The purpose of this study was to evaluate the diagnostic performance of magnetic resonance imaging (MRI) guided musculoskeletal biopsy and the value of fine needle aspiration biopsy (FNAB) when combined with histologic biopsy. Materials and methods A total of 172 biopsies were performed under MRI guidance, 170 were histologic biopsies. In 112 cases, a fine needle aspiration biopsy was also performed. In two cases, a stand-alone FNAB was performed. The diagnostic performance was evaluated retrospectively by comparing the histopathologic and cytologic diagnosis with the current or final diagnosis after at least one year of clinical and imaging follow-up. A 0.23 T open MRI scanner with an interventional stereotactic guidance system was used. Results The overall diagnostic accuracy of MRI guided biopsy was 0.95, sensitivity 0.91, specificity 0.98, positive predictive value (ppv) 0.97 and negative predictive value (npv) 0.93. The diagnostic accuracy of trephine biopsy alone was 0.93, sensitivity 0.89, specificity 0.98, ppv 0.97 and npv 0.91 and accuracy for FNAB alone was 0.85, sensitivity 0.80, specificity 0.90, ppv 0.89 and npv 0.82. Conclusions MRI guidance is a feasible and accurate tool in percutaneous musculoskeletal biopsies. Fine needle biopsy is a useful low-cost supplement to histologic biopsy.

High-field open (HFO) MRI is an emerging and promising modality in the guidance of various minimally invasive interventions because of the high tissue contrast, the absence of ionizing radiation and unrestricted multi-planar imaging options. The ongoing development of powerful MRI techniques and instruments allows for advanced possibilities to guide, monitor and control minimally invasive interventions. Moreover, open MR systems provide better patient access, which improves the interventional workflow. In this chapter, the basics and current status of interventional HFO MRI is described. Essential clinical procedures for high-field open MRI-guided interventions and innovative research findings are discussed.

The authors have developed a quantitative method to evaluate rotatory laxity of the anterior cruciate ligament (ACL)-deficient knee using an open MRI. In this study, we evaluated the correlation between the pivot-shift test grading and values measured with this method. Furthermore, the articular contact area in the lateral compartment during the pivot shift was examined. Ninety-two subjects were evaluated in this study. Among them, 36 subjects were evaluated before the ACL reconstruction, and 56 subjects were evaluated 1 year after the ACL reconstruction. Subjects were placed in the open MRI scanner in the posture based on the Slocum’s ALRI test. Anterior translation of the tibia was measured in the lateral and medial compartments in the sagittal images of the MRI. The correlation between the grading of the pivot-shift test and either anterior translation of the lateral compartment, or the difference between translation of the medial compartment and the lateral compartment, was evaluated by logistic analysis. Furthermore, we examined the contact area of the articular surface in the lateral compartment with variation in the pivot-shift grading. The anterior translation of the lateral compartment had a significant correlation with the pivot-shift grading. A discriminant analysis showed that the lateral translation could predict the grade of the pivot-shift test more accurately than the lateral minus medial translation (84.8% vs. 70.7%, P

Objectives: During labor, transperineal sonography is increasingly used to evaluate fetal head descent. The aim of the present study was to compare the angle of progression assessed by open magnetic resonance imaging (MRI) versus transperineal ultrasound. Methods: 31 pregnant women at term (>37 weeks), who were not in labor, underwent a MRI in an open 1.0 Tesla system. A midsagittal plane of the maternal pelvis was stored. Immediately after, without changing the supine position, a transperineal ultrasound was performed. The angle of progression was measured off-line by transperineal ultrasound and MRI. Results The angles of progression measured by transperineal ultrasound (mean 79.05°, SD 11.44) and MRI (mean 80.48°, SD 11.06) correlated significantly (p

To evaluate the feasibility of minimally invasive magnetic resonance imaging (MRI)-guided free-hand aspiration of symptomatic nerve route compressing lumbosacral cysts in a 1.0-Tesla (T) open MRI system using a tailored interactive sequence.Eleven patients with MRI-evident symptomatic cysts in the lumbosacral region and possible nerve route compressing character were referred to a 1.0-T open MRI system. For MRI interventional cyst aspiration, an interactive sequence was used, allowing for near real-time position validation of the needle in any desired three-dimensional plane.Seven of 11 cysts in the lumbosacral region were successfully aspirated (average 10.1 mm [SD ± 1.9]). After successful cyst aspiration, each patient reported speedy relief of initial symptoms. Average cyst size was 9.6 mm (±2.6 mm). Four cysts (8.8 ± 3.8 mm) could not be aspirated.Open MRI systems with tailored interactive sequences have great potential for cyst aspiration in the lumbosacral region. The authors perceive major advantages of the MR-guided cyst aspiration in its minimally invasive character compared to direct and open surgical options along with consecutive less trauma, less stress, and also less side-effects for the patient.

The aim of this study was to investigate whether the combination of cisplatin-eluting gelatin microspheres (GMSs) and flavopiridol enhances anti-tumour effects in a rabbit VX2 liver tumour model. Tumour-bearing rabbits (n = 21) were divided into five groups and infused from the proper hepatic artery. Group 1 (n = 5) received cisplatin-eluting GMSs (1 mg kg(-1)) and flavopiridol (3 mg kg(-1)), group 2 (n = 5) cisplatin-eluting GMSs alone (1 mg kg(-1)), Group 3 (n = 5) flavopiridol (3 mg kg(-1)), Group 4 (n = 3) GMSs alone (1 mg kg(-1)), and Group 5 (n = 3) was the control group receiving physiological saline (1 ml kg(-1)). On days 0 and 7 after procedures the liver tumour volume was measured using a horizontal open MRI system and the relative tumour volume growth rates for 7 days after treatment were calculated. On T(1) weighted images, the tumours were visualised as circular, low-intensity areas just below the liver surface. After treatment, the signals remained similar. The relative tumour volume growth rate for 7 days after treatment was 54.2+/-22.4% in Group 1, 134.1+/-40.1% in Group 2,166.7+/-48.1% in Group 3, 341.8+/-8.6% in Group 4 and 583.1+/-46.9% in Group 5; the growth rate was significantly lower in Group 1 than the other groups (p0.05). We concluded that in our rabbit model of liver tumours the combination of cisplatin-eluting GMSs and flavopiridol was effective.

Laparoscopic liver surgery is a safe and feasible technique for the treatment of benign and malignant liver tumors and has been well established at many specialized centers. Many different techniques of tissue dissection have been developed. As an alternative various lasers have been applied to conventional liver resections. Laser surgery is potentially beneficial for laparoscopic liver resection, allowing parenchymal dissection and vessel coagulation. A second advantage is the non-ferromagnetic character of this instrument, which facilitates magnetic resonance (MR)-guided interventions. In this study two different Nd:YAG lasers were evaluated for laparoscopic liver resection in a porcine model. In other studies this technique will be transferred into an interventional open MRI for image-guided liver resection.We used 1064-nm and 1318-nm Nd:YAG lasers for laparoscopic wedge, segmental, and left lateral liver lobe resection. During the intervention blood loss, resection time, and cardiopulmonary parameters were quantified. The resected specimen underwent histomorphometric analysis for thermal tissue effects, including parenchymal carbonization, necrosis, and vessel coagulation.The resected volume showed a positive correlation with intraoperative blood loss, which increased from wedge resection (245 mL, SD +/- 71 mL) and segment resection (325 mL), to left lateral resection (455 mL). Total parenchymal dissection was slightly faster with the 1064-nm Nd:YAG laser (9 min, SD +/- 5 min) compared with the 1318-nm Nd:YAG laser (11 min, SD +/- 4 min). Thermally-induced vessel sealing was shown for liver veins and arteries to a maximum diameter of 2 mm.Laparoscopic liver resection with both Nd:YAG lasers is a safe and feasible technique, allowing parenchymal dissection and coagulation. The 1064-nm Nd:YAG laser showed increased tissue damage with more effective coagulation capability than the 1318-nm Nd:YAG laser. Because of its non-ferromagnetic characteristics, laser-based laparoscopic liver resection is potentially useful for image-guided surgery in an open MRI.

OBJECTIVE. The purpose of our study is to present a real-time interactive continuous fluoroscopy MRI technique for vesicoureteral reflux (VUR) diagnosis.CONCLUSION. MR voiding cystography with a real-time interactive MR fluoroscopic technique on an open MRI magnet is feasible for the evaluation of VUR in children.