A New Technique for CT/MR Fusion For Skull Base Imaging

This paper presents our initial experience utilizing a new technique which allows CT and MR image fusion in patients with skull base lesions. Eleven patients with a variety of skull base lesions underwent CT and MR imaging prior to surgery. Both sets of images were coregistered using customized software. The CT and MR data sets were then combined and viewed in a single interactive image formar using a high-speed graphic computing system. Image fusion allowed simultaneous visualization of the bony skull base anatomy (CT) and detailed soft tissue anatomy (MR) using a single image format. Combining both modalities was felt to provide a better assessment of the extent of lesions and improve understanding of their relationship to adjacent bony and neurovascular anatomy. Specifically, image fusion enhanced awareness of location of skill base lesions with respect to the cavernous sinuses. Gasserian ganglia, carotid arteries, and jugular foramina. For tumors arising within the internal auditory canal (IAC), fused images allowed better delineation of the lateral aspect of the lesion with respect to the fundus of the IAC. Thus, fusion of CT and MR studies provides a unique image format which has advantages over single modality display. We believe image fusion is beneficial for surgical planning and for treatment planning of complex skull base malignancies treated with radiotherapy.     

Image fusion for skull base neuronavigation. Technical note

An automatic image fusion module (BrainLab, Munich, Germany) is used for the fusion of the magnetic resonance (MR) imaging and computed tomography (CT) data sets. The procedure of image fusion takes 5 minutes prior to surgery. The image fusion of CT and MR imaging data visualizes the skull base and tumor margins clearly. Color display of the different data sets allows the tumor and the skull base to be distinguished easily. The fused CT data in bone window mode provides useful additional information on the osseous skull base.     

Efficacy of navigation in skull base surgery using composite computer graphics of magnetic resonance and computed tomography images

The efficacy of a neurosurgical navigation system using three-dimensional composite computer graphics (CGs) of magnetic resonance (MR) and computed tomography (CT) images was evaluated in skull base surgery. Three-point transformation was used for integration of MR and CT images. MR and CT image data were obtained with three skin markers placed on the patient's scalp. Volume-rendering manipulations of the data produced three-dimensional CGs of the scalp, brain, and lesions from the MR images, and the scalp and skull from the CT. Composite CGs of the scalp, skull, brain, and lesion were created by registering the three markers on the three-dimensional rendered scalp images obtained from MR imaging and CT in the system. This system was used for 14 patients with skull base lesions. Three-point transformation using three-dimensional CGs was easily performed for multimodal registration. Simulation of surgical procedures on composite CGs aided in comprehension of the skull base anatomy and selection of the optimal approaches. Intraoperative navigation aided in determination of actual spatial position in the skull base and the optimal trajectory to the tumor during surgical procedures.     

CT-MR image fusion for the management of skull base lesions.

OBJECTIVE: Image fusion software creates composite images from computed tomography (CT) and magnetic resonance (MR) images. STUDY DESIGN AND SETTING: CT-MR fusion studies between August 2004 to July 2005 were reviewed. CT scan images (1-mm axial) were obtained on a multi-detector CT scanner. MR images (1-mm axial) were obtained with a T1-weighted, volume acquisition technique. CT-MR fusion images were created on the Instatrak 3500 Plus or CBYON Suite. RESULTS: A total of 25 patients had 27 CT-MR image fusion studies. CT-MR fusion accuracy was 2 mm or better. During preoperative planning and intraoperative navigation, CT-MR fusion facilitated the delineation of the anatomic relationships between the lesion and the skull base. CONCLUSIONS: CT-MR image fusion yields composite images that combine features of each component imaging modality. Image fusion, when combined with surgical navigation, further enhances potential skull base applications for minimally invasive endoscopic surgery.     

Advanced image-guided skull base surgery

BACKGROUND

Tumors of the skull base frequently encase or extend into normal neural and vascular structures. Preoperative planning and intraoperative identification of anatomic landmarks is especially important in complex tumors since it helps avoid or minimize surgical morbidity.

METHODS

By creating a surgical plan the image guidance software offers help in the establishment of a surgical approach. During surgery, the neuronavigation system displays the location of anatomic landmarks of the skull base regardless of any erosion or displacement.

RESULTS

A series of 10 patients with complex tumors in various skull base locations is reported. Osseous structures are easily identified using the CT-based image guidance since these landmarks do not shift due to CSF loss. Image fusion of CT and MRI data gives additional information on the displacement of soft tissue structures. Image fusion in a substraction mode is helpful when a tumor has invaded bony structures or when the encasement of major vessels has to be visualized.

CONCLUSION

The preoperative data preparation (planning of the approach, image fusion) plays a vital role in modern neuronavigation and contributes useful information during surgery for complex skull base tumors. Such advanced neuronavigation increases the efficacy and safety of intraoperative maneuvers. Eroded and distorted anatomic landmarks are not subject to a significant amount of intraoperative shift throughout the surgical procedure.     

Intraoperative acquisition of three-dimensional imaging for frameless stereotactic guidance during transsphenoidal pituitary surgery using the Arcadis Orbic System

OBJECT: Intraoperative fluoroscopy has long been used for anatomical localization in transsphenoidal pituitary surgery. More recently, frameless stereotaxy has been used to supplement 2D sagittal radiographs with 3D multiplanar reconstructions. Use of Arcadis Orbic allows both conventional fluoroscopic views and multiplanar reconstructions to be acquired intraoperatively without need for preoperative planning studies. The authors report their initial experience using Arcadis Orbic during transsphenoidal pituitary surgery. METHODS: To test the system, the authors placed a dehydrated human skull in a radiolucent head holder, and obtained standard 2D fluoroscopic images of the skull base and sella turcica. Arcadis Orbic was then used with frameless stereotaxy to register 3D multiplanar reconstructed images of skull base anatomy. The authors then used Arcadis Orbic in 26 transsphenoidal pituitary tumor resections and compared image quality, accuracy, and ease-of-use to standard techniques. Results: Arcadis Orbic 2D fluoroscopic images matched or exceeded the quality of images acquired by standard C-arm machines. Arcadis Orbic multiplanar reconstructions provided excellent images of the skull base when compared with preoperative Stealth computed tomography (CT) studies. Intraoperative frameless stereotactic navigation using Arcadis Orbic was highly accurate and more reliable than registering preoperative CT images. CONCLUSIONS: Arcadis Orbic provides excellent quality 2- and 3D images during transsphenoidal pituitary surgery, and intraoperative frameless navigation using these images is highly accurate. Arcadis Orbic is easy to use, even in patients with large body habitus, and image acquisition takes no longer than registration during a frameless stereotactic case. Based upon our preliminary experience, Arcadis Orbic precludes the need for preoperative CT studies in patients with pituitary lesions requiring frameless stereotactic navigation.     

Transparent imaging of CT angiography for the delineation of cerebral aneurysms]

Transparent imaging with volume rendering of CT angiography (CTA) was used to delineate cerebral aneurysms. Five unruptured cerebral aneurysms discovered incidentally on MR angiography were delineated as transparent CTA images and compared with routine three-dimensional CTA images. Reconstructing the volume data sets by adjusting the opacity level and range of CT values allowed transparent visualization of the aneurysm with its related vessels through the bony structures of the cranial base. Transparent imaging of CTA may be a useful adjunct for the evaluation of an aneurysm adjacent to the bony structure.     

Pneumocephalus associated with ethmoidal sinus osteoma--case report

A 35-year-old female suffered sudden onset of severe headache upon blowing her nose. No rhinorrhea or signs of meningeal irritation were noted. Computed tomography (CT) with bone windows clearly delineated a bony mass in the right ethmoid sinus, extending into the orbit and intracranially. Conventional CT demonstrated multiple air bubbles in the cisterns and around the mass in the right frontal skull base, suggesting that the mass was associated with entry of the air bubbles into the cranial cavity. T1- and T2-weighted magnetic resonance (MR) imaging showed a low-signal lesion that appeared to be an osteoma but did not show any air bubbles. Through a wide bilateral frontal craniotomy, the cauliflower-like osteoma was found to be protruding intracranially through the skull base and the overlying dura mater. The osteoma was removed, and the dural defect was covered with a fascia graft. Histological examination confirmed that the lesion was an osteoma. The operative procedure resolved the problem of air entry. CT is superior to MR imaging for diagnosing pneumocephalus, by providing a better assessment of bony destruction and better detection of small amounts of intracranial air.     

Three-dimensional reconstructed computed tomography-magnetic resonance fusion image-based preoperative planning for surgical procedures for spinal lipoma or tethered spinal cord after myelomeningocele repair

Surgical procedures for spinal lipoma or tethered spinal cord after myelomeningocele (MMC) repair are often difficult and complicated, because the anatomical structures can be deformed in complex and unpredictable ways. Imaging helps the surgeon understand the patient's spinal anatomy. Whereas two-dimensional images provide only limited information for surgical planning, three-dimensional (3D) reconstructed computed tomography (CT)-magnetic resonance (MR) fusion images produce clearer representations of the spinal regions. Here we describe simple and quick methods for obtaining 3D reconstructed CT-MR fusion images for preoperative planning of surgical procedures using the iPlan(?) cranial (BrainLAB AG, Feldkirchen, Germany) neuronavigation software. 3D CT images of the vertebral bone were combined with heavily T(2)-weighted MR images of the spinal cord, lipoma, cerebrospinal fluid (CSF) space, and nerve root through a process of fusion, segmentation, and reconstruction of the 3D images. We also used our procedure called "Image Overlay" to directly project the 3D reconstructed image onto the body surface using an LED projector. The final reconstructed 3D images took 10-30 minutes to obtain, and provided the surgeon with a representation of the individual pathological structures, so enabled the design of effective surgical plans, even in patients with bony deformity such as scoliosis. None of the 19 patients treated based on our 3D reconstruction method has had neurological complications, except for CSF leakage. This 3D reconstructed imaging method, combined with Image Overlay, improves the visual understanding of complicated surgical situations, and should improve surgical efficiency and outcome.     

The effective application of segmental image fusion in spinal radiosurgery for improved targeting of spinal tumours

Purpose  As a result of experiences of failed image fusion, an improved protocol for effective CT and MRI image fusion was developed. Image fusion is a critical part of image-guided stereotactic radiosurgery (IG-SRS) and greatly influences the accurate measurement of gross tumour volume (GTV) and optimal dosimetry. Avoidance of any positional discrepancy is vital for optimal image fusion and results in improved targeting, which improves clinical results. This paper describes a protocol for effective image fusion and how it impacted on the clinical outcome of stereotactic radiosurgery for spinal tumours. Methods  Fused MRI/CT images from 20 patients were examined and compared. A protocol for fusing images from thin slice MR images and CTs was developed for improved identification and measurement of tumour volume. Differences in individual GTV values both before and after image fusion were evaluated. The effectiveness of tumour targeting was also assessed by comparing discrepancies in individual and overall GTV values. Results  Differences in mean GTVs using either CT or MRI alone compared with the mean found through combined CT/MR image fusion showed a difference of 30.5 ± 4.8% and 14.5 ± 3.3% respectively. Additionally, the median GTV values from CT- and MR-based imaging were 11.64 ± 7.8 cm³ and 11.72 ± 6.6 cm³ vs 14.06 ± 8.0 cm³. Median GTV from CT–MR fusion was 14.06 ± 8.0 cm³. Improved information provided by the fused images enabled us to prescribe more effective dosages, as the fused images gave more accurate information about tumour se due to better delineation of tumour perimeters. Conclusions  This protocol provides improved visualisation of spinal tumours and enables better treatment planning. Segmented image fusion was shown to provide significant advantages for planning stereotactic radiosurgery. Fused images provided more precise and accurate data and allowed better targeting of tumours, with improved tumour coverage that resulted in better clinical outcomes.     

Comparison of Scientific Calipers and Computer-Enabled CT Review for the Measurement of Skull Base and Craniomaxillofacial Dimensions

Traditionally, cadaveric studies and plain-film cephalometrics provided information about craniomaxillofacial proportions and measurements; however, advances in computer technology now permit software-based review of computed tomography (CT)-based models. Distances between standardized anatomic points were measured on five dried human skulls with standard scientific calipers (Geneva Gauge, Albany, NY) and through computer workstation (StealthStation 2.6.4, Medtronic Surgical Navigation Technology, Louisville, CO) review of corresponding CT scans. Differences in measurements between the caliper and CT model were not statistically significant for each parameter. Measurements obtained by computer workstation CT review of the cranial skull base are an accurate representation of actual bony anatomy. Such information has important implications for surgical planning and clinical research.     

Virtual Reality Augmentation in Skull Base Surgery

Objective: Skull base anatomy is complex and subject to individual variation. Understanding the complexity of surgical anatomy is faster and easier with virtual models created from primary imaging data of the patient. This study was designed to investigate the usefulness of virtual reality in image guidance for skull base procedures. Design: Primary volumetric image data from 110 patients was acquired using magnetic resonance, computed tomography (CT), and CT angiography. Pathologies included lesions in the anterior, middle, and posterior skull base. The data were transferred to an infrared-based image-guidance system for creation of a virtual operating field (VOF) with translucent surface modulation and optional "fly-through" video mode. During surgery, the target registration error for anatomical landmarks was assessed and the VOF was compared with the patient's anatomy in the operative field. Results: Complex structures like the course of the sigmoid sinus, the carotid artery, and the outline of the paranasal sinuses were well visualized in the VOF and were recognized by the surgeon instantly. Perception was greatly facilitated as compared with routine mental reconstruction of triaxial images. Accurate assessment of the depth of field and very small objects was not possible in VOF images. Conclusion: Supported by sound anatomical knowledge, creation of a virtual operating field for a surgical approach in an individual patient offers a déjà vu experience that can enhance the capabilities of a surgical team in skull base approaches. In addition, application of this technique in image-guided procedures assists in targeting or avoiding hidden anatomical structures.     

Advanced neuronavigation in skull base tumors and vascular lesions.

OBJECTIVE: The purpose of this study was to describe the usefulness of recent advances of neuronavigational technology in the management of skull base tumors and of vascular lesions, treated via a skull base approach. METHODS: In 16 patients (skull base meningioma n = 9, petrous apex epidermoid n = l, craniopharyngeoma n = 1, giant internal carotid artery aneurysm n = 1, basilar/vertebral artery aneurysm n = 2, brain stem cavernoma n = 2), "advanced" neuronavigation was used. In contrast to "conventional" neuronavigation, the information for the neurosurgeon was enhanced by the intraoperative screen display of 3-dimensional reconstructions of the lesion, vessels, nerves and fiber tracts at risk. The 3-dimensional reconstructions were obtained by preoperative manual or automated segmentation processes. In addition, different imaging modalities (computed tomography [CT] with magnetic resonance imaging [MRI], CT with CT angiography, T (l)- with diffusion-weighted MRI) were fused and shown on the screen. RESULTS: In the cases of tumors, "advanced" neuronavigation facilitated the approach (n = 4), contributed to tailor the approach (n = 2) and helped to identify hidden neurovascular structures (n = 9). In the cases of aneurysms, "advanced" neuronavigation allowed us to reduce the skull base approach to the needs of safe aneurysm clipping (n = 3). In both cases of brain stem cavernoma, "advanced" neuronavigation was deemed useful for definition of the best surgical approach in relation to the pyramidal tract and brain stem nuclei. CONCLUSION: The authors' experiences suggest that neuronavigation, which displays 3-dimensional reconstructions of lesion, vessels, nerves and fiber tracts during surgery and makes use of image fusion techniques, is an important tool in the neurosurgical management of skull base lesions.     

Evaluation of CT-MR image registration methodologies for 3D preoperative planning of forearm surgeries

Computerized surgical planning for forearm procedures that considers both soft and bony tissue, requires alignment of preoperatively acquired computed tomography (CT) and magnetic resonance (MR) images by image registration. Normalized mutual information (NMI) registration techniques have been researched to improve efficiency and to eliminate the user dependency associated with manual alignment. While successfully applied in various medical fields, the application of NMI registration to images of the forearm, for which the relative pose of the radius and ulna likely differs between CT and MR acquisitions, is yet to be described. To enable the alignment of CT and MR forearm data, we propose an NMI-based registration pipeline, which allows manual steering of the registration algorithm to the desired image subregion and is, thus, applicable to the forearm. Successive automated registration is proposed to enable planning incorporating multiple target anatomical structures such as the radius and ulna. With respect to gold-standard manual registration, the proposed registration methodology achieved mean accuracies of 0.08 ± 0.09 mm (0.01-0.41 mm range) in comparison with 0.28 ± 0.23 mm (0.03-0.99 mm range) associated with a landmark-based registration when tested on 40 patient data sets. Application of the proposed registration pipeline required less than 10 minutes on average compared with 20 minutes required by the landmark-based registration. The clinical feasibility and relevance of the method were tested on two different clinical applications, a forearm tumor resection and radioulnar joint instability analysis, obtaining accurate and robust CT-MR image alignment for both cases.     

Practical and technical aspects of trans-sphenoidal surgery

Trans-sphenoidal surgery was first described more than a century ago. Today, this approach occupies a crucial place in the armamentarium of the neurosurgeon for the management of sellar, suprasellar, and parasellar pathological conditions. Over the years, the procedure has witnessed multiple modifications, benefitting from technological advances and from innovative ideas of pioneering neurosurgeons and otolaryngologists. The introduction of the microscope and then the endoscope allowed progressive improvement of visualization, illumination, and magnification in this restricted surgical corridor. With enhanced knowledge and understanding of the surgical anatomy of the skull base, the application of extended transsphenoidal approaches became possible, thus widening significantly the anatomical area that can be reached through this approach. In addition, the continuous improvement in imaging, image guidance, and microinstruments allowed better planning and precision during surgery. In sum, thanks to recent technological advance, trans-sphenoidal surgery can now be applied to a large area of the skull base and for a wide range of pathological conditions. With growing experience, the procedure is performed with enhanced safety and greater efficacy. In this paper, we review the historical evolution of trans-sphenoidal surgery and describe the modern applications and modifications of the procedure.     

A case report detailing the use of 3D printing technology in surgical planning and decision making in ENT surgery-an axial 3D first in Northern Ireland

Introduction and importanceThis case report details the first use of Axial 3D printing technology in Northern Ireland for surgical planning and decision making in ENT skull base surgery.Case presentation39 year old male seen at ENT clinic with nasal congestion. CT showed multi-sinus mucosal thickening. Histology reported inverted papilloma polyp. The surgical options were modified Lothrops endoscopic sinus surgery or an open approach of frontal sinuses with osteoplastic flap and septorhinoplasty. A model 3D skull was created by Axial 3D using stereolithography 3D printing technology with photopolymer resin. The tumour was printed in a contrasting colour, which allowed clear visualisation and appreciation of tumour borders and relations to surrounding structures. The patient underwent FESS with modified Lothrops approach, achieving good clearance of polyp.Clinical discussionThe use of a 3D model allowed for visualisation of tumour size and relation to surrounding anatomy, particularly the absence of dural involvement within the fontal sinus. It assisted in surgical planning. The use of the 3D skull was beneficial for patient as it allowed less invasive surgery and therefore shorter recovery. It was beneficial for the hospital organisation as it lowered resource requirements of theatre time, hospital bed days and staff resources. One limitation of the 3D printed skull was that the fine lamellae ethmoid air cells were not shown due to the manufacturing process.ConclusionThe use of 3D printing is becoming increasingly popular as a surgical aid. We found the use of the 3D skull to be useful in individualised surgical planning for endoscopic sinus surgery.     

High-resolution three-dimensional T2-weighted sequence for neuronavigation: a new setup and clinical trial

OBJECT: Conventional imaging for neuronavigation is performed using high-resolution computerized tomography (CT) scanning or a T1-weighted isovoxel magnetic resonance (MR) sequence. The extension of some lesions, however, is depicted much better on T2-weighted MR images. A possible fusion process used to match low-resolution T2-weighted MR image set with a referenced CT or T1-weighted data set leads to poor resolution in the three-dimensional (3D) reconstruction and decreases accuracy, which is unacceptable for neuronavigation. The object of this work was to develop a 3D T2-weighted isovoxel sequence (3D turbo-spin echo [TSE]) for image-guided neuronavigation of the whole brain and to evaluate its clinical application. METHODS: The authors performed a phantom study and a clinical trial on a newly developed T2-weighted isovoxel sequence, 3D TSE, for image-guided neuronavigation using a common 1.5-tesla MR imager (Siemens Sonata whole-body imager). The accuracy study and intraoperative image guidance were performed with the aid of the pointer-based Medtronic Stealth Station Treon. The 3D TSE data set was easily applied to the navigational setup and demonstrated a high registration accuracy during the experimental trial and during an initial prospective clinical trial in 25 patients. The sequence displayed common disposable skin fiducial markers and provided convincing delineation of lesions that appear hyperintense on T2-weighted images such as low-grade gliomas and cavernomas in its clinical application. CONCLUSIONS: Three-dimensional TSE imaging broadens the spectrum of navigational and intraoperative data sets, especially for lesions that appear hyperintense on T2-weighted images. The accuracy of its registration is very reliable and it enables high-resolution reconstruction in any orientation, maintaining the advantages of image-guided surgery.     

In vivo accuracy of image guidance performed using optical tracking and optimized registration

OBJECT: Image guidance systems involving the use of frameless referencing of surgical space to compile volumetric imaging data sets recently have come into widespread use. Few studies have addressed the true intraoperative surgical accuracy (that is, the application accuracy) of these systems except in a subjective manner. Calculated accuracies given by the systems do not necessarily reflect true intraoperative accuracy. METHODS: To objectively assess the stereotactic accuracy of a frameless image guidance system using optical spatial referencing, the author analyzed postoperative magnetic resonance (MR) images after placement of depth electrodes for the investigation of epilepsy. Preoperative planning for the treatment of seven patients included implanting skull fiducial screws and obtaining computed tomography/MR fusion images by using ImMerge image fusion software on the StealthStation (Medtronic, Inc.). A total of 42 electrodes were placed. Postoperative volumetric MR images were fused with preoperative study images. The difference between the planned electrode trajectories and targets and the visualized electrodes was measured in stereotactic space. CONCLUSIONS: The mean distance between the distal electrode contact and the distal end of the planned trajectory for the 42 targets was 3 +/- 1.5 mm. The most common error was in depth. The author's technique did not involve rigid skull fixation of electrodes because they were subsequently tunneled subcutaneously and later removed at the bedside of the patient. Errors in depth were known to be due to traction at the time of tunneling and not due to stereotactic factors. Correcting for depth along the electrode trajectory, the mean accuracy was found to be 2.4 +/- 1 mm.     

Stereotaxic surgery with a magnetic resonance- and computerized tomography-compatible system

Modern stereotaxic surgery is dependent upon compatible advanced imaging tools, including computerized tomography (CT) scanning and magnetic resonance (MR) imaging. The authors describe three cases in which the patients underwent stereotaxic surgery for mass lesions identified by both MR imaging and CT scans. Identical target coordinates were defined by both techniques, and accuracy was confirmed by intraoperative CT. In comparison to stereotaxic CT, MR provided superior contrast resolution, allowed direct multiplanar imaging and target determination, and permitted accurate correlation of the image with histological features. The operative set-up and technique are described. Stereotaxic surgery with MR imaging may permit more accurate histopathological definition of tumor margins and ultimately lead to better dosimetry for therapeutic procedures such as interstitial brachytherapy.     

Multi-Slice 3D-CTA – An Improvement Over Single Slice Helical CTA for Cerebral Aneurysms

Summary. Summary.   Background and Objective: The aim of this study was to demonstrate the utility of volume rendered multi-slice helical three-dimensional CT angiography in patients with cerebral aneurysm when compared with single slice CT angiography and formal digital subtraction angiography.   Methods: A prototype Toshiba Aquilon multi-slice CT scanner was employed with the following scan conditions: voltage 135 kV; current 300 mA; slice thickness 0.8 mm; scan speed 0.75 sec/cycle; couch speed 1 mm/sec; range 50 mm from foramen magnum; scan pitch 3; three dimensional images were reconstructed using multiple image projections and integral volume rendering algorithms on a Xlink/Xtension workstation. 80 cases of multi-slice CTA for cerebral aneurysm carried out at Fujita University from January 1999 to January 2001 were reviewed.   Results: The advantages of multi-slice imaging are illustrated with representative cases of cerebral aneurysm – good demonstration of three dimensional anatomy, appreciation of perforators down to 1 mm in size, delineation of the vessels around the aneurysm complex, relationship between the aneurysm and skull base, information on calcification, thrombus and blebs in the wall and eleven routine views for perusal.   Conclusion: Multi-slice CTA is a significant improvement over single slice CTA for cerebral aneurysms. It is our experience the superior and precise images produced by multi-slice technology displays anatomical information not readily available from standard DSA. Multislice 3D-CTA is relatively non-invasive and provides better and adequate detail for surgical planning. The basis of multi-slice CT angiography is described. Multi slice CTA is changing the way cerebral aneurysms are being managed nowadays. New advances in the technology of multi-slice CTA resulting in increased image resolution are outlined. Published online July 18, 2002