Case Report of a Hemangioblastoma Originating from the T1 Spinal Nerve Treated with in Toto Resection, Hemicorporectomy and Pedicle Screw Stabilization.

Introduction: Previously, only 40 cases with extradural hemangioblastoma at the spinal nerve (none at the T1 nerve root) have been described in the medical literature. In toto, resection of this hypervascular tumor is essential to avoid bleeding complications. Surgery for hemangioblastoma at the cervicothoracic junction is complex and nerve resection of the T1 results in specific neurodeficits of the hand muscles which are not well known. Case Report: A 34-year-old woman was diagnosed with a slowly growing tumor located at the left foramen T1/T2. Pressure from the tumor resulted in Horner's syndrome and pain and paresthesia in the upper extremity. The tumor was resected in toto through a posterior midline approach and rib resection and transection of the left T1 and T2 spinal nerves. T2 hemicorporectomy and spinal stabilization were performed to gain access to and mobilize the tumor ventrally. Ptosis decreased after surgery and no neurodeficit was observed except the expected deficit (no deficit was present preoperatively) caused by the T1 resection specifically a small decrease in strength of the abductor and flexor pollicis brevis and opponens pollicis and the lateral two lumbricals. Histological examination of the tumor demonstrated a hemangioblastoma. von Hippel-Lindau disease was ruled out by genetic testing of the patient's blood. Eight-month postoperatively, all pre-operative symptoms had decreased considerably and the radiographic examination shoved unchanged pedicle screw/rod stabilization of the cervicothoracic junction. Conclusion: Hemangioblastoma is a rare hypervascular tumor very rarely located at the spinal nerve. The tumor should be resected in toto to avoid recurrence and bleeding. In the current case, the location was at the T1 root necessitating complex surgery with laminectomies and hemicorporectomy of T2 and a posterior rib resection/thoracotomy. Spinal stabilization is mandatory. Preferably embolization should be performed preoperatively. T1 transection results in a specific neurodeficit which should be explained to the patient preoperatively. The patients should undergo genetic testing for Hippel-Lindau disease.

Dose optimisation for intraoperative cone-beam flat-detector CT in paediatric spinal surgery.

BACKGROUND: During surgery for spinal deformities, accurate placement of pedicle screws may be guided by intraoperative cone-beam flat-detector CT. OBJECTIVE: The purpose of this study was to identify appropriate paediatric imaging protocols aiming to reduce the radiation dose in line with the ALARA principle. MATERIALS AND METHODS: Using O-arm® (Medtronic, Inc.), three paediatric phantoms were employed to measure CTDI(w) doses with default and lowered exposure settings. Images from 126 scans were evaluated by two spinal surgeons and scores were compared (Kappa statistics). Effective doses were calculated. The recommended new low-dose 3-D spine protocols were then used in 15 children. RESULTS: The lowest acceptable exposure as judged by image quality for intraoperative use was 70 kVp/40 mAs, 70 kVp/80 mAs and 80 kVp/40 mAs for the 1-, 5- and 12-year-old-equivalent phantoms respectively (kappa = 0,70). Optimised dose settings reduced CTDI(w) doses 89-93%. The effective dose was 0.5 mSv (91-94,5% reduction). The optimised protocols were used clinically without problems. CONCLUSIONS: Radiation doses for intraoperative 3-D CT using a cone-beam flat-detector scanner could be reduced at least 89% compared to manufacturer settings and still be used to safely navigate pedicle screws.

Microdialysis of paraspinal muscle in healthy volunteers and patients underwent posterior lumbar fusion surgery.

Paraspinal muscle damage is inevitable during conventional posterior lumbar fusion surgery. Minimal invasive surgery is postulated to result in less muscle damage and better outcome. The aim of this study was to monitor metabolic changes of the paraspinal muscle and to evaluate paraspinal muscle damage during surgery using microdialysis (MD). The basic interstitial metabolisms of the paraspinal muscle and the deltoid muscle were monitored using the MD technique in eight patients, who underwent posterior lumbar fusion surgery (six male and two female, median age 57.7 years, range 37-74) and eight healthy individuals for different positions (five male and three female, age 24.1 +/- 0.8 years). Concentrations of glucose, glycerol, and lactate pyruvate ratio (L/P) in both tissues were compared. In the healthy group, the glucose and glycerol concentrations and L/P were unchanged in the paraspinal muscle when the body position changed from prone to supine. The glucose concentration and L/P were stable in the paraspinal muscle during the surgery. Glycerol concentrations increased significantly to 243.0 +/- 144.1 microM in the paraspinal muscle and 118.9 +/- 79.8 microM in the deltoid muscle in the surgery group. Mean glycerol concentration difference (GCD) between the paraspinal muscle and the deltoid tissue was 124.1 microM (P = 0.003, with 95% confidence interval 83.4-164.9 microM). The key metabolism of paraspinal muscle can be monitored by MD during the conventional posterior lumbar fusion surgery. The glycerol concentration in the paraspinal muscle is markedly increased compared with the deltoid muscle during the surgery. It is proposed that GCD can be used to evaluate surgery related paraspinal muscle damage. Changing body position did not affect the paraspinal muscle metabolism in the healthy subjects.

Determination of wall tension in cerebral artery aneurysms by numerical simulation.

BACKGROUND AND PURPOSE: Cerebral artery aneurysms rupture when wall tension exceeds the strength of the wall tissue. At present, risk-assessment of unruptured aneurysms does not include evaluation of the lesions shape, yet clinical experience suggests that this is of importance. We aimed to develop a computational model for simulation of fluid-structure interaction in cerebral aneurysms based on patient specific lesion geometry, with special emphasis on wall tension. METHODS: An advanced isogeometric fluid-structure analysis model incorporating flexible aneurysm wall based on patient specific computed tomography angiogram images was developed. Variables used in the simulation model were retrieved from a literature review. RESULTS: The simulation results exposed areas of high wall tension and wall displacement located where aneurysms usually rupture. CONCLUSIONS: We suggest that analyzing wall tension and wall displacement in cerebral aneurysms by numeric simulation could be developed into a novel method for individualized prediction of rupture risk.

Integrating segmentation methods from the Insight Toolkit into a visualization application.

The Insight Toolkit (ITK) initiative from the National Library of Medicine has provided a suite of state-of-the-art segmentation and registration algorithms ideally suited to volume visualization and analysis. A volume visualization application that effectively utilizes these algorithms provides many benefits: it allows access to ITK functionality for non-programmers, it creates a vehicle for sharing and comparing segmentation techniques, and it serves as a visual debugger for algorithm developers. This paper describes the integration of image processing functionalities provided by the ITK into VolView, a visualization application for high performance volume rendering. A free version of this visualization application is publicly available and is available in the online version of this paper. The process for developing ITK plugins for VolView according to the publicly available API is described in detail, and an application of ITK VolView plugins to the segmentation of Abdominal Aortic Aneurysms (AAAs) is presented. The source code of the ITK plugins is also publicly available and it is included in the online version.

[Teleradiologic follow up of patients treated with aortic stent grafting]. / Teleradiologisk oppfølging av pasienter behandlet med stentgraft i aorta.

BACKGROUND: A study has confirmed the possibility of follow up in the local hospital of patients who have undergone endovascular repair. We present a cost analysis of such a regimen compared to follow up at a university hospital. MATERIAL AND METHODS: By using discharge data from the Norwegian Patient Register we identified a group of patients which could have been followed up at their local hospital for their stent-grafted abdominal aortic aneurysm and estimated the cost effects of performing follow ups locally. RESULTS: The cost analysis showed a potential for cost savings from local follow ups, especially from moving from inpatient care at the university hospital to outpatient care locally. The result of this cost analysis differs from other Norwegian studies of teleradiology by identifying a possibility for more cost-effective treatment. INTERPRETATION: Using teleradiology to follow up these patients will free up capacity in the university hospital. Most probably, other groups of patients can also be followed up by teleradiology. The university hospitals can use this freed-up capacity for new patients. Teleradiology could lead to more efficient use of health care facilities, which should be in the interest of the health authorities.

Three-dimensional teleradiology for surveillance following endovascular aortic aneurysm repair: a feasibility study.

PURPOSE: To study the feasibility of 3-dimensional (3D) teleradiology in surveillance of patients treated with stent-grafts for abdominal aortic aneurysm (AAA). METHODS: Between April 2002 and November 2003, 8 AAA patients (7 men; median age 73 years, range 62-84) with stent-grafts had follow-up computed tomograms (CT) performed at their local hospital and transmitted without loss across a broadband connection to the university hospital. On both monitors, the radiologists were presented with the complete CT axial dataset, sagittal and coronal reformatted slices, and a 3D volume-rendered reconstruction. The two radiologists were then able to simultaneously perform measurements and real-time manipulations of the axial and 3D pictures, which were discussed over the telephone or using a videoconferencing unit. Patient satisfaction, the radiologists' evaluation of the method, and the potential cost savings were explored. RESULTS: Twelve follow-up CT scans were performed on the 8 patients. The time for transmission over the teleradiological network averaged 5 minutes, and the evaluation required 15 minutes at the university hospital. The overall technical quality of the images was rated as good by the university radiologist. In 11 studies, the stent-grafts were satisfactory, but a type III endoleak was detected in one 5.5-year-old stent-graft. Neither radiologist had a problem identifying the endoleak. Patients had confidence that the examination at the local hospital was of good quality; they all felt that they received good care and were pleased with avoiding travel to the university hospital. From the economic analysis, an annual savings of 40,000 Euros (USD 52,304) was projected, mostly due to avoiding hospital stays and outpatient consultations at the university hospital. CONCLUSIONS: The experiences from this study are encouraging, but a larger series will be necessary for a thorough evaluation of 3D teleradiology as a surveillance method for aortic stent-graft patients.

[3-D navigation in laparoscopic surgery]. / Tredimensjonal navigasjon i laparoskopisk kirurgi.

BACKGROUND: The main drawback with the laparoscopic approach is that the surgeon lacks the possibility to palpate vessels, tumours and organs during surgery. Furthermore, the laparoscope only provides a surface view of organs. There is a need for more advanced visualization that enhances the view to include information below the surface of the organs when the procedure is planned and for control and guidance during treatment. MATERIAL AND METHODS: We propose 3-D navigation technology based on preoperatively acquired MR or CT data used in combination with a laparoscopic navigation pointer. The pointer has an attached position tracker which enables the surgeon to interactively control the display of images prior to and during surgery. RESULTS: We have used this technology during treatment of four patients with adrenal tumours. Preoperative registration of images of the patients was performed within two minutes with an average accuracy of 7.1 mm. 2-D and 3-D visualizations interactively controlled by the pointer were used both for planning and for guidance of the surgical procedures. INTERPRETATION: The pointer was a useful tool in image guidance of laparoscopic surgery in the reported cases both for planning the approach in detail and for guidance. We believe abdominal 3-D image guidance using a laparoscopic navigation pointer has a large potential for improving laparoscopic surgery, especially in cases where vessels and anatomical relations might be difficult to identify using only a laparoscope. Accordingly, this new technology will increase safety and facilitate successful laparoscopic surgery.

A new method for analysis of motion of carotid plaques from RF ultrasound images.

Motion of carotid artery plaques during the cardiac cycle may contribute to plaque disruption and embolism. We have developed a computerized method that objectively analyzes such motion from a sequence of ultrasound (US) radiofrequency (RF) images. A displacement vector map is obtained by 2-D correlation of local areas in consecutive images. From this map, motion dynamics can be quantified and presented as function of time, spatial (image) coordinates or as single numbers. Correct functionality has been verified on laboratory data. Applied to patient data, the method gives temporal results that correlate well with ECG data and the calculated peak systolic velocities of typically 10 mm/s agree well with values reported in the literature. The spatial analysis demonstrates that different plaque regions may exhibit different motion patterns that may cause internal stress, leading to fissures and plaque disruption. Thus, the motion analysis method may provide new and important information about the plaque characteristics and the prospective risk of cerebrovascular events.

Multimodal image fusion in ultrasound-based neuronavigation: improving overview and interpretation by integrating preoperative MRI with intraoperative 3D ultrasound.

OBJECTIVE: We have investigated alternative ways to integrate intraoperative 3D ultrasound images and preoperative MR images in the same 3D scene for visualizing brain shift and improving overview and interpretation in ultrasound-based neuronavigation. MATERIALS AND METHODS: A Multi-Modal Volume Visualizer (MMVV) was developed that can read data exported from the SonoWand neuronavigation system and reconstruct the spatial relationship between the volumes available at any given time during an operation, thus enabling the exploration of new ways to fuse pre- and intraoperative data for planning, guidance and therapy control. In addition, the mismatch between MRI volumes registered to the patient and intraoperative ultrasound acquired from the dura was qualified. RESULTS: The results show that image fusion of intraoperative ultrasound images in combination with preoperative MRI will make perception of available information easier by providing updated (real-time) image information and an extended overview of the operating field during surgery. This approach will assess the degree of anatomical changes during surgery and give the surgeon an understanding of how identical structures are imaged using the different imaging modalities. The present study showed that in 50% of the cases there were indications of brain shift even before the surgical procedure had started. CONCLUSIONS: We believe that image fusion between intraoperative 3D ultrasound and preoperative MRI might improve the quality of the surgical procedure and hence also improve the patient outcome.