Guidance Of Interventional Procedures Research Articles

NICE news in the annals

NICE finds out about new procedures which are entering practice through notifications via its website; through personal contact with clinicians; and through opportunistic surveillance. Mostly, procedures are notified by clinicians and manufacturers, but managers, commissioners, private insurers and patients sometimes also notify procedures which are of interest or concern to them. I write every 1-2 years to the leaders of all professional medical organisations asking them whether new procedures are emerging in their area of work. Since 2002 there have been 1,105 notifications and these have resulted in publication of 428 pieces of Interventional Procedures guidance (66 of these were reviews). The numbers of notifications have fluctuated during the last 10 years with a recent trend to slightly lower numbers. It is unclear whether this is simply one of the fluctuations; whether fewer new procedures are being introduced; or whether there has been any decrease in awareness of the need to notify new procedures to NICE. The one mandate for notifying new procedures rests on clinicians. Shortly after the Interventional Procedures Programme started a Health Service Circular was published which stipulated that: ‘Medical practitioners intending to carry out a new interventional procedure should seek the approval of their NHS Trust’s Clinical Governance Committee. If the procedure is not listed on NICE’s website (www.nice.org.uk/ip), the Chair of the Committee should notify the procedure to NICE via the website.’ 1 Notification is done via http://www.nice.org.uk/ipsearch/index.jsp. The meaning of a ‘new procedure’ is one that a fully trained clinician has not done before (excluding, of course, a procedure which is well established and which he/she happened not to undertake during training). There is no bar to clinicians notifying NICE themselves and telling their hospital that they have done so: that is common practice. The onus to inform the hospital concerned and to notify NICE if the procedure is not already on the NICE website applies equally to introducing new procedures in the private sector. That principle was established through agreements between NICE and organisations representing both private hospitals and private insurers. Fewer than half of all notifications result in a decision for NICE to evaluate the procedure and publish guidance, based on advice from clinical specialists and deliberations which can be complex. For example, procedures may have already been notified, but with a different name, or they may be considered minor variations of established procedures. A fundamental consideration is whether the notified procedure might possibly differ in any aspect of safety or efficacy from related procedures which are established practice. Interventional procedures guidance aims to protect patients from harm, while facilitating their access to new, beneficial procedures in the best possible circumstances. It offers reassurance to clinicians and to their hospitals that they are introducing procedures in a way which would withstand critical scrutiny. It specifies uncertainties which need to be clarified by further research and /or collection of data. Identifying procedures depends on clinicians notifying them when they first contemplate their use. That does not mean that they cannot start using the procedure: until NICE publishes guidance, the kind of ‘special arrangements’ recommended when evidence is uncertain is the rule: tell your hospital; tell your patients; and audit your results with special care.

Magnetostatic focal spot correction for x-ray tubes operating in strong magnetic fields using iterative optimization.

Combining x-ray fluoroscopy and MR imaging systems for guidance of interventional procedures has become more commonplace. By designing an x-ray tube that is immune to the magnetic fields outside of the MR bore, the two systems can be placed in close proximity to each other. A major obstacle to robust x-ray tube design is correcting for the effects of the magnetic fields on the x-ray tube focal spot. A potential solution is to design active shielding that locally cancels the magnetic fields near the focal spot. An iterative optimization algorithm is implemented to design resistive active shielding coils that will be placed outside the x-ray tube insert. The optimization procedure attempts to minimize the power consumption of the shielding coils while satisfying magnetic field homogeneity constraints. The algorithm is composed of a linear programming step and a nonlinear programming step that are interleaved with each other. The coil results are verified using a finite element space charge simulation of the electron beam inside the x-ray tube. To alleviate heating concerns an optimized coil solution is derived that includes a neodymium permanent magnet. Any demagnetization of the permanent magnet is calculated prior to solving for the optimized coils. The temperature dynamics of the coil solutions are calculated using a lumped parameter model, which is used to estimate operation times of the coils before temperature failure. For a magnetic field strength of 88 mT, the algorithm solves for coils that consume 588 A∕cm(2). This specific coil geometry can operate for 15 min continuously before reaching temperature failure. By including a neodymium magnet in the design the current density drops to 337 A∕cm(2), which increases the operation time to 59 min. Space charge simulations verify that the coil designs are effective, but for oblique x-ray tube geometries there is still distortion of the focal spot shape along with deflections of approximately 3 mm in the radial and circumferential directions on the anode. Active shielding is an attractive solution for correcting the effects of magnetic fields on the x-ray focal spot. If extremely long fluoroscopic exposure times are required, longer operation times can be achieved by including a permanent magnet with the active shielding design.

Real-time magnetic resonance guidance of interventional electrophysiology procedures with passive catheter visualization and tracking

One of the key problems in interventional electrophysiology (EP) today is the inability to generate sufficient soft tissue contrast for intraprocedural visualization of the myocardium and the surrounding tissue by using conventional imaging techniques. Intraprocedural magnetic resonance imaging (MRI) has been identified as a potential solution to address this weakness of conventional EP; however, clinical adoption of MR-guided EP requires the development of EP devices that are both fully MR functional and MR safe at the same time.

Recording Database Searches for Systematic Reviews - What is the Value of Adding a Narrative to Peer-Review Checklists? A Case Study of NICE Interventional Procedures Guidance

This paper discusses the value of open and transparent methods for recording systematic database search strategies, showing how they have been applied at the National Institute for Health and Clinical Excellence (NICE) in the United Kingdom (UK).
 
 Objective – The objectives are to: 1) Discuss the value of search strategy recording methods. 2) Assess any limitations to the practical application of a checklist approach. 3) Make recommendations for recording systematic database searches.
 
 Methods – The procedures for recording searches for Interventional Procedures Guidance at NICE were examined. A sample of current methods for recording systematic searches identified in the literature was compared to the NICE processes. The case study analyses the search conducted for evidence about an interventional procedure and shows the practical issues involved in recording the database strategies.
 
 The case study explores why relevant papers were not retrieved by a search strategy meeting all of the criteria on the checklist used to peer review it. The evidence was required for guidance on non-rigid stabilisation techniques for the treatment of low back pain.
 
 Results – The analysis shows that amending the MEDLINE strategy to make it more sensitive would have increased its yield by 6614 articles. Examination of the search records together with correspondence between the analyst and the searcher reveals the peer reviewer had approved the search because its sensitivity was appropriate for the purpose of producing Interventional Procedures Guidance. The case study demonstrates the limitations of relying on a checklist to ensure the quality of a database search without having any contextual information.
 
 Conclusion – It is difficult for the peer reviewer to assess the subjective elements of a search without knowing why it has a particular structure or what the searcher intended. There is a risk that the peer reviewer will concentrate on the technical details, such as spelling mistakes, without having the contextual information. It is beneficial if the searcher records correspondence on key decisions and reports a summary alongside the search strategy. The narrative describes the major decisions that shaped the strategy and gives the peer reviewer an insight into the rationale for the search approach.

Extracorporeal membrane oxygenation for severe acute respiratory failure in adults: NICE guidance

Extracorporeal membrane oxygenation (ECMO) is a modified form of cardiopulmonary bypass that allows short-term support for potentially reversible severe acute respiratory and/or cardiac failure in critically ill adults and children....

The Place of Transabdominal Ultrasound in Acute Pancreatitis in Daily Practice

PurposeThe purpose of our study was to assess how useful is transabdominal ultrasound in acute pancreatitis and what information we can obtain using this method.Material & MethodsWe included all patients (p) admitted with acute pancreatitis in our department between 2006 and 2010, in which we assessed: patients demographics, severity of acute pancreatitis (according to Atlanta criteria), initial ultrasound examination, follow up and interventional maneuvers.Results567p were admitted during the study period with acute pancreatitis. 355(62.6%) were mild forms, while 212 (37.4%) were severe. In 431/567p(76%), we were able to visualize the pancreas at the ultrasound examination performed at admission: 126/212 (59.4%) were severe cases (140/212-66.1% of them were obese or overweight) and 305/355 (85.9%) were mild cases (p < 0.0001). In severe cases, the first ultrasound examination showed signs of severity (enlarged hyperechoic bursa omentalis, pancreatic and peripancreatic fluid collections, free abdominal fluid, pleural effusion) in 47/212 (22.2%) cases and the follow up in another 84 (39.6%) cases. The first ultrasound examination diagnosed also the biliary etiology in 227p out of 251p (90.4%) with biliary pancreatitis. In 35/567p (6.2%), we used ultrasound for guidance in percutaneous interventional procedures.ConclusionIn our study, the transabdominal ultrasound visualized the pancreas at admission in 76% of cases. Transabdominal ultrasound allowed also the diagnosis of biliary etiology in 90% of cases, showing signs of severity and was used for the guidance of interventional procedures. PurposeThe purpose of our study was to assess how useful is transabdominal ultrasound in acute pancreatitis and what information we can obtain using this method. The purpose of our study was to assess how useful is transabdominal ultrasound in acute pancreatitis and what information we can obtain using this method. Material & MethodsWe included all patients (p) admitted with acute pancreatitis in our department between 2006 and 2010, in which we assessed: patients demographics, severity of acute pancreatitis (according to Atlanta criteria), initial ultrasound examination, follow up and interventional maneuvers. We included all patients (p) admitted with acute pancreatitis in our department between 2006 and 2010, in which we assessed: patients demographics, severity of acute pancreatitis (according to Atlanta criteria), initial ultrasound examination, follow up and interventional maneuvers. Results567p were admitted during the study period with acute pancreatitis. 355(62.6%) were mild forms, while 212 (37.4%) were severe. In 431/567p(76%), we were able to visualize the pancreas at the ultrasound examination performed at admission: 126/212 (59.4%) were severe cases (140/212-66.1% of them were obese or overweight) and 305/355 (85.9%) were mild cases (p < 0.0001). In severe cases, the first ultrasound examination showed signs of severity (enlarged hyperechoic bursa omentalis, pancreatic and peripancreatic fluid collections, free abdominal fluid, pleural effusion) in 47/212 (22.2%) cases and the follow up in another 84 (39.6%) cases. The first ultrasound examination diagnosed also the biliary etiology in 227p out of 251p (90.4%) with biliary pancreatitis. In 35/567p (6.2%), we used ultrasound for guidance in percutaneous interventional procedures. 567p were admitted during the study period with acute pancreatitis. 355(62.6%) were mild forms, while 212 (37.4%) were severe. In 431/567p(76%), we were able to visualize the pancreas at the ultrasound examination performed at admission: 126/212 (59.4%) were severe cases (140/212-66.1% of them were obese or overweight) and 305/355 (85.9%) were mild cases (p < 0.0001). In severe cases, the first ultrasound examination showed signs of severity (enlarged hyperechoic bursa omentalis, pancreatic and peripancreatic fluid collections, free abdominal fluid, pleural effusion) in 47/212 (22.2%) cases and the follow up in another 84 (39.6%) cases. The first ultrasound examination diagnosed also the biliary etiology in 227p out of 251p (90.4%) with biliary pancreatitis. In 35/567p (6.2%), we used ultrasound for guidance in percutaneous interventional procedures. ConclusionIn our study, the transabdominal ultrasound visualized the pancreas at admission in 76% of cases. Transabdominal ultrasound allowed also the diagnosis of biliary etiology in 90% of cases, showing signs of severity and was used for the guidance of interventional procedures. In our study, the transabdominal ultrasound visualized the pancreas at admission in 76% of cases. Transabdominal ultrasound allowed also the diagnosis of biliary etiology in 90% of cases, showing signs of severity and was used for the guidance of interventional procedures.

SU-E-J-07: A Preliminary Study on Optimal Dose-Allocation Parameters for Low-Dose Cone-Beam CT

Purpose: Cone-beam CT (CBCT) is widely used for providing image guidance in radiotherapy and interventional procedures. Due to the patient safety concern involved in repetitive CBCT scans, significant effort has been devoted to possibly lowering imaging dose in CBCT. For a given total dose, it is also important to investigate how image quality can be affected by dose allocations over projection views and by image-reconstruction algorithms. In this work, we investigate quantitatively how image quality changes resulted from different combinations of dose-allocation parameters and some existing reconstruction algorithms. Methods: We performed simulation studies by using a numerical phantom containing structures ofdifferent contrast levels. We also acquired real data of a Catphan phantom (The Phantom Laboratory, Salem, NY) by using the on-board imaging system (Varian Medical Systems, Palo Alto, CA). At three different total dose levels, we allocated each of them to different numbers of views ranging from 120 to 650. For each allocation scheme we applied the FDK and ASD-POCS algorithms to obtain reconstructed images. A set of quantitative metrics were used to evaluate image quality based on relevant tasks. Results: Preliminary results showed that for total dose levels under study, both FDK and ASD-POCS algorithms yield images with comparable quality when a large number of views are considered and that images reconstructed by the ASD-POCS from smaller number of views generally exhibit higher quality. Overall, for each given total dose level the ASD-POCS algorithm yields images of comparable or higher quality than does the FDK algorithm. Conclusions: We demonstrated that CBCT image quality can be optimized for a fixed total dose by choosing an appropriate combination of dose- allocation parameters and reconstruction algorithm. This finding may potentially be used for improving current CBCT image quality and for designing innovative, low-dose CBCT imaging protocols.

Transcatheter valve repair/implantation

Real time 3-dimensional transesophageal echo is a relatively new technology that enables online imaging that is highly accurate and precise for evaluating cardiac structures. Moreover, this methodology allows for accurate online guidance of interventional cardiac procedures for structural heart disease. In this report, we describe the use of real time, 3D transesophageal (TEE) for aortic valve replacement with percutaneous, bioprosthetic valves as well as for transcatheter mitral repair with the MitraClip device. For each procedure, we describe 3D evaluation of valvular structures prior to the procedure, and how 3D imaging is used to guide the procedure as well as to assess the results of the procedure. Use of 3D TEE has proven to be a substantial advance for evaluating patients prior to percutaneous heart valve procedures and especially for guiding and monitoring percutaneous, transcatheter heart valve procedures.

A Registration-Based Propagation Framework for Automatic Whole Heart Segmentation of Cardiac MRI

Magnetic resonance (MR) imaging has become a routine modality for the determination of patient cardiac morphology. The extraction of this information can be important for the development of new clinical applications as well as the planning and guidance of cardiac interventional procedures. To avoid inter- and intra-observer variability of manual delineation, it is highly desirable to develop an automatic technique for whole heart segmentation of cardiac magnetic resonance images. However, automating this process is complicated by the limited quality of acquired images and large shape variation of the heart between subjects. In this paper, we propose a fully automatic whole heart segmentation framework based on two new image registration algorithms: the locally affine registration method (LARM) and the free-form deformations with adaptive control point status (ACPS FFDs). LARM provides the correspondence of anatomical substructures such as the four chambers and great vessels of the heart, while the registration using ACPS FFDs refines the local details using a constrained optimization scheme. We validated our proposed segmentation framework on 37 cardiac MR volumes on the end-diastolic phase, displaying a wide diversity of morphology and pathology, and achieved a mean accuracy of 2.14 +/- 0.63 mm (rms surface distance) and a maximal error of 4.31 mm.

Local Decision-Makers Views' of National Guidance on Interventional Procedures in the Uk

To identify how decision-makers in the NHS perceive and manage interventional procedures guidance and to determine whether additional information would be useful. Qualitative study using semi-structured interviews with seven providers, six commissioners and one policy-maker. The framework approach was used to analyse transcribed data, and emergent themes coded. Data were analysed separately for providers and commissioner organizations. Perceptions about how guidance is managed in provider organizations varied. Some decision-makers considered that guidance is handled very well whereas others think it is suboptimal and haphazard. It is unclear whether clinicians follow procedure for cautionary guidance. In commissioner organizations, guidance is not seen as a priority by most and is not considered an area that will soon enter routine clinical practice. Moreover, commissioners felt that guidance lacked relevance as there is no consideration of whether procedures are cost-effective or affordable. Despite this, respondents perceived that the content and quality of guidance is satisfactory. Useful additional information for inclusion in guidance would be: prevalence, incidence, cost, patients' views, consequences of using the new intervention, comparative information, effectiveness and cost-effectiveness. Management of interventional procedures guidance in the NHS can be improved. It is important to understand the ways in which guidance meets and fails to meet decision-makers' needs.

C-arm Fluoroscopic Cone Beam CT for Guidance of Minimally Invasive Spine Interventions

Background: Isocentric C-arm fluoroscopic cone beam CT (CBCT) is a new technique for near real time 3-D volume imaging guidance of percutaneous interventional procedures. In combination with digital flat panel detectors, CBCT has high spatial resolution with isotropic voxel size, allowing for high resolution image reconstruction in any plane, including 3D rotational reconstructions. CBCT combines the advantages of conventional CT imaging guidance with the improved spatial resolution, patient positioning, and access of fluoroscopy. Objective: The aim of this study is to demonstrate the advantages of CBCT over conventional CT and biplane fluoroscopy for imaging guidance of minimally invasive spinal and paraspinal interventional procedures. Methods: Five patients referred to the department of interventional neuroradiology for percutaneous spinal or paraspinal interventional procedures were intraoperatively evaluated with CBCT to assist in guidance of instrumentation placement. Procedures included transoral cervical vertebral biopsy, percutaneous thoracic vertebral biopsy, vertebroplasty, pelvic paraspinal/epidural abscess drainage, and paraspinal fiducial marker placement for treatment of osteoid osteoma. Results: All procedures were successfully performed with satisfactory diagnostic yield or therapeutic effect without procedure-related complications. Conclusion: Isocentric C-arm fluoroscopic cone beam CT (CBCT) is a new technique for 3D volume imaging guidance of interventional procedures of the spine with the capability to produce near real time high resolution image reconstructions in any plane. Compared to conventional CT and biplane fluoroscopy, CBCT offers improved anatomic visualization allowing high accuracy instrumentation placement, improving procedure results and minimizing risk of complications. Key words: Vertebroplasty, kyphoplasty, biopsy, computed tomography, CT, fluoroscopy, Carm, percutaneous, interventional radiology, imaging guidance

Emerging roles for transthoracic ultrasonography in pulmonary diseases

As a result of many advantages such as the absence of radiation exposure, non-invasiveness, low cost, safety, and ready availability, transthoracic ultrasonography (TUS) represents an emerging and useful technique in the management of pleural and pulmonary diseases. In this second part of a comprehensive review that deals with the role of TUS in pleuropulmonary pathology, the normal findings, sonographic artifacts and morphology of the most important and frequent pulmonary diseases are described. In particular, the usefulness of TUS in diagnosing or raising suspicion of pneumonia, pulmonary embolism, atelectasis, diffuse parenchymal diseases, adult and newborn respiratory distress syndrome, lung cancer and lung metastases are discussed, as well as its role in guidance for diagnostic and therapeutic interventional procedures. Moreover, the preliminary data about the role of contrast enhanced ultrasonography in the study of pulmonary pleural-based lesions are also reported. Finally, the limits of TUS when compared with chest computed tomography are described, highlighting the inability of TUS to depict lesions that are not in contact with the pleura or are located under bony structures, poor visualization of the mediastinum, and the need for very experienced examiners to obtain reliable results.

Online real‐time reconstruction of adaptive TSENSE with commodity CPU/GPU hardware

Adaptive temporal sensitivity encoding (TSENSE) has been suggested as a robust parallel imaging method suitable for MR guidance of interventional procedures. However, in practice, the reconstruction of adaptive TSENSE images obtained with large coil arrays leads to long reconstruction times and latencies and thus hampers its use for applications such as MR-guided thermotherapy or cardiovascular catheterization. Here, we demonstrate a real-time reconstruction pipeline for adaptive TSENSE with low image latencies and high frame rates on affordable commodity personal computer hardware. For typical image sizes used in interventional imaging (128 x 96, 16 channels, sensitivity encoding (SENSE) factor 2-4), the pipeline is able to reconstruct adaptive TSENSE images with image latencies below 90 ms at frame rates of up to 40 images/s, rendering the MR performance in practice limited by the constraints of the MR acquisition. Its performance is demonstrated by the online reconstruction of in vivo MR images for rapid temperature mapping of the kidney and for cardiac catheterization.

Three-Dimensional Ultrasound in Soft Tissue Tumor Imaging

Sonography has not been generally accepted as an imaging modality for the evaluation of soft tissue tumors. Three-dimensional ultrasonography appears to be a valuable adjunct to conventional ultrasonography because it provides previously unattainable scan planes and three-dimensional views. This new technique allows to display spatially oriented and standardized views, which reduce the operator dependence and improve the reliability of follow-up studies. 3D data processing provides life like display of anatomy and real time guidance of interventional procedures such as biopsy. 3D ultrasound-guided biopsy can be performed by using multiplanar views or a combination of cross sectional and rendered images. Large core biopsies using a vacuum assisted biopsy device (8G) achieve an accuracy in the histopathological assessment of soft tissue sarcoma that is comparable to incisional biopsy. Improved visualization and guidance of interventional procedures by 3D ultrasound may increase the acceptance of clinicians to use sonography for the evaluation of soft tissue tumors.

NICE Guidance in the Scottish Context

The UK landscape of guidance for clinical practice and public health has become increasingly complicated in recent times, and it is easy to feel confused as to what is available for what purposes, what applies where, and who does what. Within this overall picture, there is potential for uncertainty as to the applicability, or otherwise, in Scotland of guidance produced by the National Institute for Health and Clinical Excellence (NICE) in England, including NICE technology appraisals, clinical guidelines, interventional procedures guidance, and public health programme and intervention guidance. This paper is offered as a map to help health professionals and others to find their way through the Scottish landscape, with particular reference to NICE's outputs and the respective roles of NHS Quality Improvement Scotland (NHS QIS) and NHS Health Scotland (HS).

Real-time three-dimensional transoesophageal echocardiography for guidance of non-coronary interventions in the catheter laboratory

The growing need for less invasive therapies of cardiac disease creates the necessity for improved imaging guidance. Although two-dimensional transthoracic and transoesophageal echocardiography (TEE) have been shown to be essential tools for planning and execution of cardiac interventions, the benefit of three-dimensional TEE for the guidance of interventional procedures still needs to be evaluated. This review aims to describe our first experiences with real-time (RT) three-dimensional TEE for the guidance of percutaneous non-coronary interventions in the catheter laboratory. We used a matrix array TEE probe capable of generating three-dimensional images of cardiac structures in RT. We applied this innovative technique to monitor atrial septal defects or patent foramen ovale closures, valve procedures such as mitral and aortic valve interventions, and electrophysiological procedures. Our first experience using RT three-dimensional TEE for the guidance of percutaneous cardiac interventions in the catheter laboratory demonstrates that this technique is feasible to guide interventions, providing fast and complete information about the underlying pathomorphology, improving spatial orientation, and additionally allowing the online monitoring of the procedure. These benefits may accelerate the learning curve and improve confidence of the interventional cardiologist in order to increase safety, accuracy, and efficacy of interventional cardiac procedures.

Contrast-enhanced ultrasound: The evolving applications

Contrast-enhanced ultrasound (CEUS) is a major breakthrough for ultrasound imaging in recent years. By using a microbubble contrast agent and contrast-specific imaging software, CEUS is able to depict the micro- and macro-circulation of the targeted organ, which in turn leads to improved performance in diagnosis. Due to the special dual blood supply system in the liver, CEUS is particularly suitable for liver imaging. It is evident that CEUS facilitates improvement for characterization of focal liver lesions (FLLs), detection of liver malignancy, guidance for interventional procedures, and evaluation of treatment response after local therapies. CEUS has been demonstrated to be equal to contrast-enhanced computed tomography or magnetic resonance imaging for the characterization of FLLs. In addition, the applicability of CEUS has expanded to non-liver structures such as gallbladder, bile duct, pancreas, kidney, spleen, breast, thyroid, and prostate. The usefulness of CEUS in these applications is confirmed by extensive literature production. Novel applications include detecting bleeding sites and hematomas in patients with abdominal trauma, guiding percutaneous injection therapy and therefore achieving the goal of using interventional ultrasonography in managing splenic trauma, assessing the activity of Crohn's disease, and detecting suspected endoleaks after endovascular abdominal aneurysm repair. Contrast-enhanced intraoperative ultrasound (US) and intracavitary use of CEUS have been developed and clinically studied. The potential use of CEUS involves sentinel lymph node detection, drug or gene delivery, and molecular imaging. In conclusion, the advent of CEUS has greatly enhanced the usefulness of US and even changed the status of US in clinical practice. The application of CEUS in the clinic is continuously evolving and it is expected that its use will be expanded further in the future.

The case for MR‐compatible robotics: a review of the state of the art

The numerous imaging capabilities of magnetic resonance imaging (MRI) coupled with its lack of ionizing radiation has made it a desirable modality for real-time guidance of interventional procedures. The combination of these abilities with the advantages granted by robotic systems to perform accurate and precise positioning of tools has driven the recent development of MR-compatible interventional and assistive devices. The challenges in this field are presented, including the selection of suitable materials, actuators and sensors in the intense magnetic fields of the MR environment. Only a small number of developed systems have made it to the clinical level (only two have become commercial ventures), showing that the field has not yet reached maturity. A brief overview of the current state of the art is given, along with a description of the main opportunities, possibilities and challenges that the future will bring to this exciting and promising field.

Procédures interventionnelles percutanées abdominales et pelviennes sous contrôle TDM à l’aide d’un système de guidage fluoroscopique intégré à 21 mA : analyse de 99 cas

The purpose of our study was to retrospectively evaluate the efficacy, the limitations and the complications of real-time CT fluoroscopy (Carevision) as an adjunct to CT guidance for percutaneous abdominopelvic interventional procedures. Materials and methods. During a 28 month period, 99 patients (55 men, 44 women) with a mean age of 59 years had percutaneous abdominopelvic interventional procedure under CT guidance using CT fluoroscopy. Sixty-four patients had a percutaneous drainage of an abdominopelvic fluid collection with a Seldinger technique using an 8.5- to 14-F drainage catheter and 35 patients had a percutaneous biopsy using an 18-G automatic core biopsy needle. In all cases, the quality of the real-time CT fluoroscopic images allowed to securely monitor needle advancement towards the target lesion and to confirm correct position of the needle tip. The diameters of target lesions ranged from 1.5 to 10 cm, with a mean value of 4.75 cm. No immediate complications were observed. The real-time CT fluoroscopy times ranged from 25 to 242 sec, with a mean time of 117 sec. All percutaneous procedures (100%) were successfully performed. Our initial clinical experience suggests that real-time CT fluoroscopy allows to perform effective and secure percutaneous abdominopelvic interventional procedures. However, because of substantial radiation exposure, its use has to be limited to specific et selected cases.

MR systems for MRI‐guided interventions

The field of MR imaging has grown from diagnosis via morphologic imaging to more sophisticated diagnosis via both physiologic and morphologic imaging and finally to the guidance and control of interventions. A wide variety of interventional procedures from open brain surgeries to noninvasive focused ultrasound ablations have been guided with MR and the differences between diagnostic and interventional MR imaging systems have motivated the creation of a new field within MR. This review discusses the various systems that research groups and vendors have designed to meet the requirements of interventional MR and suggest possible solutions to those requirements that have not yet been met. The common requirements created by MR imaging guidance of interventional procedures are reviewed and different imaging system designs will be independently considered. The motivation and history of the different designs are discussed and the ability of the designs to satisfy the requirements is analyzed.