| 1. |
- Renna, Maurizio, et al.
(författare)
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Remifentanil plus low-dose midazolam for outpatient sedation in transesophageal echocardiography.
- 2008
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Ingår i: International journal of cardiology. - : Elsevier BV. - 1874-1754 .- 0167-5273.
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The search for optimal sedation for transesophageal echocardiography (TEE) continues. We hypothesized that the ultra-short acting opioid remifentanil combined with very low-dose midazolam would provide a better sedation and recovery profile compared to midazolam alone. METHODS: 41 consecutive outpatients scheduled for TEE received either IV midazolam (group M, 2.5 mg bolus plus 1 mg increments repeated as needed, n=18) or a combination of a low-dose IV bolus of midazolam (0.5 mg) plus an infusion of remifentanil (group RM, 0.1 mcg/kg/min, reduced to 0.08 mcg/kg/min after probe insertion, n=23). All patients received topical pharyngeal anesthesia with 2 puffs of lidocaine 4% spray. We recorded BP, SpO(2), HR, time-to-discharge (modified Aldrete score of 13), duration of procedure, resource utilization, complications, ease of probe introduction, ease and quality of the procedure. Patients' satisfaction with sedation was assessed using the Iowa Satisfaction with Anesthesia Scale (ISAS). RESULTS: Mean dose of midazolam in group M was 3.7+/-1.3 mg. Median time-to-discharge was significantly reduced in the RM group compared with the M group (5 (5-10) vs. 30 (5-240) min, p<0.0001), with 22 of the 23 group RM patients ready for "street discharge" within 5 min of removal of the TEE probe. Ease of probe insertion (p=0.001), resource utilization (p=0.0001), patient satisfaction (p=0.03) and overall ease and quality of the procedure (p=0.0001) were significantly better in the RM group than in the M group. No episodes of desaturation were observed. CONCLUSIONS: This is the first report of the use of an ultra-short acting opioid, remifentanil, combined with a low-dose of midazolam, as a sedative technique for outpatient TEE. In this pilot, non-randomized prospective study, remifentanil plus low-dose midazolam provided better sedation than our current practice of higher bolus doses of midazolam alone. This novel approach is associated with improved procedure tolerance, faster recovery and minimal resource utilization. A randomized, controlled study is under way to verify our preliminary results.
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| 2. |
- Alcala, Yvonne, et al.
(författare)
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Qualifying CT for wrist arthroplasty : Extending techniques for total hip arthroplasty to total wrist arthroplasty
- 2005
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Ingår i: Medical Imaging 2005. - : SPIE - The International Sooceity for Optical Engineeering. - 0819457213 ; , s. 1155-1164
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Konferensbidrag (refereegranskat)abstract
- The purpose of this study was to extend previous work to detect migration of total wrist arthroplasty non-invasively, and with greater accuracy. Two human cadaverous arms, each with a cemented total wrist implant, were used in this study. In one of the arms, I mm tantalum balls were implanted, six in the carpal bones and five in the radius. Five CT scans of each arm were acquired, changing the position of the arm each time to mimic different positions patients might take on repeated examinations. Registration of CT volume data sets was performed using an extensively validated, 3D semi-automatic volume fusion tool in which co-homologous point pairs (landmarks) are chosen on each volume to be registered. Three sets of ten cases each were obtained by placing landmarks on 1) bone only (using only arm one), 2) tantalum implants only, and 3) bone and tantalum implants (both using only arm two). The accuracy of the match was assessed visually in 2D and 3D, and numerically by calculating the distance difference between the actual position of the transformed landmarks and their ideal position (i.e., the reference landmark positions). All cases were matched visually within one width of cortical bone and numerically within one half CT voxel (0.32 mm, p = 0.05). This method matched only the bone/arm and not the prosthetic component per se, thus making it possible to detect prosthetic movement and wear. This method was clinically used for one patient with pain. Loosening of the carpal prosthetic component was accurately detected and this was confirmed at surgery.
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| 3. |
- Ericson, Anne, et al.
(författare)
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Fusion of radio stereometric analysis data into computed tomography space : Application to the elbow joint
- 2007
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Ingår i: Journal of Biomechanics. - Oxford, UK : Elsevier Science Ltd. - 0021-9290 .- 1873-2380. ; 40:2, s. 296-304
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Tidskriftsartikel (refereegranskat)abstract
- Improvement of joint prostheses is dependent upon information concerning the biomechanical properties of the joint. Radiostereometric analysis (RSA) and electromagnetic techniques have been applied in previous cadaver and in vivo studies on the elbow joint to provide valuable information concerning joint motion axes. However, such information is limited to mathematically calculated positions of the axes according to an orthogonal coordinate system and is difficult to relate to individual skeletal anatomy. The aim of this study was to evaluate the in vivo application of a new fusion method to provide three-dimensional (31)) visualization of flexion axes according to bony landmarks. In vivo RSA data of the elbow joint's flexion axes was combined with data obtained by 3D computed tomography (CT). Results were obtained from five healthy subjects after one was excluded due to an instable RSA marker. The median error between imported and transformed RSA marker coordinates and those obtained in the CT volume was 0.22mm. Median maximal rotation error after transformation of the rigid RSA body to the CT volume was 0.003 degrees. Points of interception with a plane calculated in the RSA orthogonal coordinate system were imported into the CT volume, facilitating the 3D visualization of the flexion axes. This study demonstrates a successful fusion of RSA and CT data, without significant loss of RSA accuracy. The method could be used for relating individual motion axes to a 3D representation of relevant joint anatomy, thus providing important information for clinical applications such as the development of joint prostheses.
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| 4. |
- Noz, Marilyn E., et al.
(författare)
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Enhancing the utility of ProstaScint SPECT scans for patient management
- 2006
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Ingår i: Journal of medical systems. - : Springer-Verlag New York. - 0148-5598 .- 1573-689X. ; 30:2, s. 123-132
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Tidskriftsartikel (refereegranskat)abstract
- This project investigated reducing the artifact content of In-111 ProstaScint SPECT scans for use in treatment planning and management. Forty-one patients who had undergone CT or MRI scans and simultaneous Tc-99m RBC/In-111 ProstaScint SPECT scans were included. SPECT volume sets, reconstructed using Ordered Set-Expectation Maximum (OS-EM) were compared against those reconstructed with standard Filtered Back projection (FBP). Bladder activity in Tc-99m scans was suppressed within an ellipsoidal volume. Tc-99m voxel values were subtracted from the corresponding In-111 after scaling based on peak activity within the descending aorta. The SPECT volume data sets were merged with the CT or MRI scans before and after processing. Volume merging, based both on visual assessment and statistical evaluation, was not affected. Thus iterative reconstruction together with bladder suppression and blood pool subtraction may improve the interpretation and utility of ProstaScint SPECT scans for patient management.
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| 5. |
- Olivecrona, Henrik, et al.
(författare)
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A new computed tomography-based radiographic method to detect early loosening of total wrist implants
- 2007
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Ingår i: Acta Radiologica. - London, UK : Informa Healthcare. - 0284-1851 .- 1600-0455. ; 48:9, s. 997-1003
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Tidskriftsartikel (refereegranskat)abstract
- Background: Diagnosis of loosening of total wrist implants is usually late using routine radiographs. Switching modality to computed tomography (CT) should aid in early diagnosis. Purpose: To propose and evaluate the accuracy of a new CT method for assessing loosening of the carpal component in total wrist arthroplasty. Material and Methods: A protocol encompassing volume registration of paired CT scans of patients with unexplained pain in a prosthetically replaced wrist (used in clinical routine) is presented. Scans are acquired as a dynamic examination under torsional load. Using volume registration, the carpal component of the prosthesis is brought into spatial alignment. After registration, prosthetic loosening is diagnosed by a shift in position of the bones relative to the prosthesis. This study is a preclinical validation of this method using a human cadaverous arm with a cemented total wrist implant and tantalum markers. Seven CT scans of the arm were acquired. The scans were combined into 21 pairs of CT volumes. The carpal component was registered in each scan pair, and the residual mismatch of the surrounding tantalum markers and bone was analyzed both visually and numerically. Results: The detection limit for prosthetic movement was less than 1 mm. Conclusion: The results of this study demonstrate that CT volume registration holds promise to improve detection of movement of the carpal component at an earlier stage than is obtainable with plain radiography.
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| 6. |
- Olivecrona, Henrik, et al.
(författare)
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A new technique for diagnosis of acetabular cup loosening using computed tomography - Preliminary experience in 10 patients
- 2008
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Ingår i: Acta Orthopaedica. - New York, NY, USA : Informa Healthcare. - 1745-3674 .- 1745-3682. ; 79:3, s. 346-353
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Tidskriftsartikel (refereegranskat)abstract
- Background and purpose: Considerable migration of the acetabular cup is required for diagnosis of loosening by conventional radiography. We have developed a new clinically applicable method for assessment of cup loosening using computed tomography (CT). Patients and methods 10 patients scheduled for revision hip replacement due to suspected wear or loosening were scanned twice with CT under torsion loading of the prosthesis. Two independent examiners assessed each patient with respect to motion of the acetabular cup relative to the pelvis using CT volume registration. The CT measurements were compared to findings at revision surgery. Results The method was applicable in 8 of the 10 patients. 1 patient had a severe tremor. In 1 patient, surgery revealed that the hip was ankylotic due to massive ectopic bone formation. This left 8 patients that could be evaluated. 4 cups were loose at surgery, and 3 of these cups could be seen to be mobile by CT. 4 cups that were stable on revision were accurately diagnosed as not being mobile by CT. Movements of less than 1 millimeter between bone and prosthesis could not be distinguished from errors in CT acquisition and volume registration. There was good agreement between the two observers. Interpretation Movement of loose acetabular cups during torsion loading could be detected using CT volume registration. It was sensitive to cup movement in 3 out of 4 cases of loose cups. The method was specific and yielded no false positive results.
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| 7. |
- Olivecrona, Lotta, et al.
(författare)
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Assessing wear of the acetabular cup using computed tomography : an ex vivo study
- 2005
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Ingår i: Acta Radiologica. - London, UK : Informa Healthcare. - 0284-1851 .- 1600-0455. ; 46:8, s. 852-857
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To validate a clinically useful method for measuring acetabular cup wear using computed tomography (CT). Material and Methods: Eight uncemented acetabular cups were scanned twice ex vivo using CT. The linear penetration depth of the femoral component head into the cup and the thickness of the remaining polyethylene liner were measured in the CT volumes using dedicated software. Two independent examiners twice assessed each volume. The CT measurements were compared to direct measurements using a coordinate measuring device and micrometer measurements. Results: Accuracy of wear measurements expressed as penetration depth was +/- 0.6 and +/- 1.0 mm for the two examiners, respectively, with no significant differences between examiners, trials, and CT scans. Accuracy of measurements of remaining polyethylene was +/- 1.3 and +/- 1.0 mm, respectively, for the two examiners. Systematic differences between examiners were found, but no significant differences between trials and CT scans. These differences were due to different interpretations of metal artifacts in the volumes. Conclusion: The proposed CT method for evaluating wear as head penetration depth allows for reliable wear detection at a clinically relevant level. Measurements of remaining polyethylene on CT volumes are not as reliable as wear measurements owing to metal artifacts.
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| 8. |
- Olivecrona, Lotta, et al.
(författare)
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Standard orientation of the pelvis : Validation on a model and ten patients
- 2005
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Ingår i: Acta Radiologica. - London, UK : Informa Healthcare. - 0284-1851 .- 1600-0455. ; 46:1, s. 74-82
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To validate an image post-processing method for re-orienting the pelvis in CT volumes to a standardized orientation in a model and in 10 patients. Material and Methods: Twenty-four CT volumes of a pelvic model and 10 pairs of postoperative total hip arthroplasty (THA) patient CT scans were rotated to a defined pelvic standard orientation and the rotation was recorded. For precision, a test-retest procedure was used. For accuracy, three exactly represented coordinate points were used. For clinical application, the standard orientation was used for calculating the direction of acetabular cup migration from a previous model study. Results: Precision of pelvic standard orientation, calculated as maximal directional error, was better than 1degrees in the model study and better than 1.5degrees in the patient study. Accuracy, expressed as angle between ideal and measured coordinate axes, was 0.1degrees for x, y, z axes. No measurable systematic errors were found. When applied to acetabular cup migration in the model, standardization of pelvic orientation had no significant effect on the measurements. Conclusion: Reorienting the pelvis during image post-processing was shown to be accurate. It enables measurements relative to the pelvis and minimizes the dependency of patient positioning.
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| 9. |
- Starr, Vanessa, et al.
(författare)
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A potential means of improving the evaluation of deformity corrections with Taylor Spatial Frames over time by using volumetric imaging : Preliminary results
- 2009
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Ingår i: Journal of Computer-Aided Surgery. - London, UK : Informa Healthcare. - 1092-9088 .- 1097-0150. ; 14:4-6, s. 100-108
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Tidskriftsartikel (refereegranskat)abstract
- Objective: In this study we explore the possibility of accurately and cost-effectively monitoring tibial deformation induced by Taylor Spatial Frames (TSFs), using time-separated computed tomography (CT) scans and a volume fusion technique to determine tibial rotation and translation. Materials and Methods: Serial CT examinations (designated CT-A and CT-B, separated by a time interval of several months) of two patients were investigated using a previously described and validated volume fusion technique, in which user-defined landmarks drive the 3D registration of the two CT volumes. Both patients had undergone dual osteotomies to correct for tibial length and rotational deformity. For each registration, 10 or more landmarks were selected, and the quality of the fused volume was assessed both quantitatively and via 2D and 3D visualization tools. First, the proximal frame segment and tibia in CT-A and CT-B were brought into alignment (registered) by selecting landmarks on the frame and/or tibia. In the resulting "fused'' volume, the proximal frame segment and tibia from CT-A and CT-B were aligned, while the distal frame segment and tibia from CT-A and CT-B were likely not aligned as a result of tibial deformation or frame adjustment having occurred between the CT scans. Using the proximal fused volume, the distal frame segment and tibia were then registered by selecting landmarks on the frame and/or tibia. The difference between the centroids of the final distal landmarks was used to evaluate the lengthening of the tibia, and the Euler angles from the registration were used to evaluate the rotation. Results: Both the frame and bone could be effectively registered (based on visual interpretation). Movement between the proximal frame and proximal bone could be visualized in both cases. The spatial effect on the tibia could be both visually assessed and measured: 34 mm, 10 degrees in one case; 5 mm, 1 degrees in the other. Conclusion: This retrospective analysis of spatial correction of the tibia using Taylor Spatial Frames shows that CT offers an interesting potential means of quantitatively monitoring the patient's treatment. Compared with traditional techniques, modern CT scans in conjunction with image processing provide a high-resolution, spatially correct, and three-dimensional measurement system which can be used to quickly and easily assess the patient's treatment at low cost to the patient and hospital.
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| 10. |
- Svedmark, Per, et al.
(författare)
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Model studies on segmental movement in lumbar spine using a semi-automated program for volume fusion
- 2008
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Ingår i: Journal of Computer-Aided Surgery. - London, UK : Informa Healthcare. - 1092-9088 .- 1097-0150. ; 13:1, s. 14-22
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To validate a new non-invasive CT method for measuring segmental translations in lumbar spine in a phantom using plastic vertebrae with tantalum markers and human vertebrae. Material and Methods: One hundred and four CT volumes were acquired of a phantom incorporating three lumbar vertebrae. Lumbar segmental translation was simulated by altering the position of one vertebra in all three cardinal axes between acquisitions. The CT volumes were combined into 64 case pairs, simulating lumbar segmental movement of up to 3 mm between acquisitions. The relative movement between the vertebrae was evaluated visually and numerically using a volume fusion image post-processing tool. Results were correlated to direct measurements of the phantom. Results: On visual inspection, translation of at least 1 mm or more could be safely detected and correlated with separation between the vertebrae in three dimensions. There were no significant differences between plastic and human vertebrae. Numerically, the accuracy limit for all the CT measurements of the 3D segmental translations was 0.56 mm (median: 0.12; range: -0.76 to +0.49 mm). The accuracy for the sagittal axis was 0.45 mm (median: 0.10; range: -0.46 to +0.62 mm); the accuracy for the coronal axis was 0.46 min (median: 0.09; range: -0.66 to +0.69 mm); and the accuracy for the axial axis was 0.45 mm (median: 0.05; range: -0.72 to +0.62 mm). The repeatability, calculated over 10 cases, was 0.35 mm (median: 0.16; range: -0.26 to +0.30 mm). Conclusion: The accuracy of this non-invasive method is better than that of current routine methods for detecting segmental movements. The method allows both visual and numerical evaluation of such movements. Further studies are needed to validate this method in patients.
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