| 1. |
- Alshamari, Muhammed, 1975-, et al.
(författare)
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Impact of iterative reconstruction on image quality of low-dose CT of the lumbar spine
- 2017
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Ingår i: Acta Radiologica. - London : Sage Publications. - 0284-1851 .- 1600-0455. ; 58:6, s. 702-709
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Tidskriftsartikel (refereegranskat)abstract
- Background: Iterative reconstruction (IR) is a recent reconstruction algorithm for computed tomography (CT) that can be used instead of the standard algorithm, filtered back projection (FBP), to reduce radiation dose and/or improve image quality.Purpose: To evaluate and compare the image quality of low-dose CT of the lumbar spine reconstructed with IR to conventional FBP, without further reduction of radiation dose.Material and Methods: Low-dose CT on 55 patients was performed on a Siemens scanner using 120 kV tube voltage, 30 reference mAs, and automatic dose modulation. From raw CT data, lumbar spine CT images were reconstructed with a medium filter (B41f) using FBP and four levels of IR (levels 2-5). Five reviewers scored all images on seven image quality criteria according to the European guidelines on quality criteria for CT, using a five-grade scale. A side-by-side comparison was also performed.Results: There was significant improvement in image quality for IR (levels 2-4) compared to FBP. According to visual grading regression, odds ratios of all criteria with 95% confidence intervals for IR2, IR3, IR4, and IR5 were: 1.59 (1.39-1.83), 1.74 (1.51-1.99), 1.68 (1.46-1.93), and 1.08 (0.94-1.23), respectively. In the side-by-side comparison of all reconstructions, images with IR (levels 2-4) received the highest scores. The mean overall CTDIvol was 1.70 mGy (SD 0.46; range, 1.01-3.83 mGy). Image noise decreased in a linear fashion with increased strength of IR.Conclusion: Iterative reconstruction at levels 2, 3, and 4 improves image quality of low-dose CT of the lumbar spine compared to FPB.
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| 3. |
- Alshamari, Muhammed, 1975-, et al.
(författare)
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Low dose CT of the lumbar spine compared with radiography : a study on image quality with implications for clinical practice
- 2016
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Ingår i: Acta Radiologica. - London, United Kingdom : Sage Publications. - 0284-1851 .- 1600-0455. ; 57:5, s. 602-611
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Tidskriftsartikel (refereegranskat)abstract
- Background: Lumbar spine radiography is often performed instead of CT for radiation dose concerns.Purpose: To compare image quality and diagnostic information from low dose lumbar spine CT at an effective dose of about 1 mSv with lumbar spine radiography.Material and Methods: Fifty-one patients were examined by both methods. Five reviewers scored all examinations on eight image quality criteria using a five-graded scale and also assessed three common pathologic changes.Results: Low dose CT scored better than radiography on the following: sharp reproduction of disc profile and vertebral end-plates (odds ratio [OR], 1.8; 95% confidence interval [CI], 1.3-2.5), intervertebral foramina and pedicles (OR, 4.3; 95% CI, 3.1-5.9), intervertebral joints (OR, 139; 95% CI, 59-326), spinous and transverse processes (OR, 7.0; 95% CI, 4.3-11.2), sacro-iliac joints (OR, 4.2; 95% CI, 3.2-5.7), reproduction of the adjacent soft tissues (OR, 2.9; 95% CI, 2.1-4.0), and absence of any obscuring superimposed gastrointestinal gas and contents (OR, 188; 95% CI, 66-539). Radiography scored better on sharp reproduction of cortical and trabecular bone (OR, 0.3; 95% CI, 0.2-0.4). The reviewers visualized disk degeneration, spondylosis/diffuse idiopathic skeletal hyperostosis (DISH) and intervertebral joint osteoarthritis more clearly and were more certain with low dose CT. Mean time to review low dose CT was 204 s (95% CI, 194-214 s.), radiography 152 s (95% CI, 146-158 s.). The effective dose for low dose CT was 1.0-1.1 mSv, for radiography 0.7 mSv.Conclusion: Low dose lumbar spine CT at about 1 mSv has superior image quality to lumbar spine radiography with more anatomical and diagnostic information.
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| 4. |
- Andersson, Karin M., 1989-, et al.
(författare)
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Visual grading evaluation of commercially available metal artefact reduction techniques in hip prosthesis computed tomography
- 2016
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Ingår i: British Journal of Radiology. - London, United Kingdom : British Institute of Radiology. - 0007-1285 .- 1748-880X. ; 89:1063
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To evaluate metal artefact reduction (MAR) techniques from four computed tomography (CT) vendors in hip prosthesis imaging.Methods: Bilateral hip prosthesis phantom images, obtained by using MAR algorithms for single energy CT data or dual energy CT (DECT) data and by monoenergetic reconstructions of DECT data, were visually graded by five radiologists using ten image quality criteria. Comparisons between the MAR images and a reference image were performed for each scanner separately. Ordinal probit regression analysis was used.Results: The MAR algorithms in general improved the image quality based on the majority of the criteria (up to between 8/10 and 10/10) with a statistically improvement in overall image quality (P<0.001). However, degradation of image quality, such as new artefacts, was seen in some cases. A few monoenergetic reconstruction series improved the image quality (P<0.004) for one of the DECT scanners, but it was only improved for some of the criteria (up to 5/10). Monoenergetic reconstructions resulted in worse image quality for the majority of the criteria (up to 7/10) for the other DECT scanner.Conclusions: The MAR algorithms improved the image quality of the hip prosthesis CT images. However, since additional artefacts and degradation of image quality were seen in some cases, all algorithms should be carefully evaluated for every clinical situation. Monoenergetic reconstructions were in general concluded to be insufficient for reducing metal artifacts. Advances in knowledge: Qualitative evaluation of the usefulness of several MAR techniques from different vendors in CT imaging of hip prosthesis.
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| 5. |
- Alshamari, Muhammed, 1975-, et al.
(författare)
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Diagnostic accuracy of low-dose CT compared with abdominal radiography in non-traumatic acute abdominal pain : prospective study and systematic review
- 2016
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Ingår i: European Radiology. - New York : Springer. - 0938-7994 .- 1432-1084. ; 26:6, s. 1766-1774
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Forskningsöversikt (refereegranskat)abstract
- Objectives: Abdominal radiography is frequently used in acute abdominal non-traumatic pain despite the availability of more advanced diagnostic modalities. This study evaluates the diagnostic accuracy of low-dose CT compared with abdominal radiography, at similar radiation dose levels.Methods: Fifty-eight patients were imaged with both methods and were reviewed independently by three radiologists. The reference standard was obtained from the diagnosis in medical records. Sensitivity and specificity were calculated. A systematic review was performed after a literature search, finding a total of six relevant studies including the present.Results: Overall sensitivity with 95 % CI for CT was 75 % (66-83 %) and 46 % (37-56 %) for radiography. Specificity was 87 % (77-94 %) for both methods. In the systematic review the overall sensitivity for CT varied between 75 and 96 % with specificity from 83 to 95 % while the overall sensitivity for abdominal radiography varied between 30 and 77 % with specificity 75 to 88 %.Conclusions: Based on the current study and available evidence, low-dose CT has higher diagnostic accuracy than abdominal radiography and it should, where logistically possible, replace abdominal radiography in the workup of adult patients with acute non-traumatic abdominal pain.Key points: • Low-dose CT has a higher diagnostic accuracy than radiography. • A systematic review shows that CT has better diagnostic accuracy than radiography. • Radiography has no place in the workup of acute non-traumatic abdominal pain.
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| 6. |
- Alshamari, Muhammed, 1975-, et al.
(författare)
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Low-dose computed tomography of the lumbar spine: a phantom study on imaging parameters and image quality
- 2014
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Ingår i: Acta Radiologica. - : SAGE Publications. - 1600-0455 .- 0284-1851. ; 55:7, s. 824-832
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Tidskriftsartikel (refereegranskat)abstract
- Background: Lumbar spine radiography has limited diagnostic value but low radiation dose compared with computed tomography (CT). The average effective radiation dose from lumbar spine radiography is about 1.1 mSv. Low-dose lumbar spine CT may be an alternative to increase the diagnostic value at low radiation dose, around 1 mSv. Purpose: To determine the optimal settings for low-dose lumbar spine CT simultaneously aiming for the highest diagnostic image quality possible. Material and Methods: An ovine lower thoracic and lumbar spine phantom, with all soft tissues around the vertebrae preserved except the skin, was placed in a 20 L plastic container filled with water. The phantom was scanned repeatedly with various technical settings; different tube potential, reference mAs, and with different convolution filters. Five radiologists evaluated the image quality according to a modification of the European guidelines for multislice computed tomography (MSCT) quality criteria for lumbar spine CT 2004. In a visual comparison the different scans were also ranked subjectively according to perceived image quality. Image noise and contrast were measured. Results: A tube potential of 120 kV with reference mAs 30 and medium or medium smooth convolution filter gave the best image quality at a sub-millisievert dose level, i.e. with an effective dose comparable to that from lumbar spine radiography. Conclusion: Low-dose lumbar spine CT thus opens a possibility to substitute lumbar spine radiography with CT without obvious increase in radiation dose.
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| 7. |
- Dreifaldt, Mats, 1959-, et al.
(författare)
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Pedicled versus skeletonized internal thoracic artery grafts : a randomized trial
- 2021
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Ingår i: Asian cardiovascular & thoracic annals. - : Medikaru Toribyun. - 1816-5370 .- 0218-4923. ; 29:6, s. 490-497
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Concerns have been raised regarding whether skeletonization of the internal thoracic artery could damage the graft and thereby reduces its patency. The objective of this study was to compare patency rates at mid- and long-term follow-up between pedicled and skeletonized left internal thoracic artery grafts.METHODS: This randomized controlled trial included 109 patients undergoing coronary artery bypass surgery. The patients were assigned to receive either one pedicled or one skeletonized left internal thoracic artery graft to the left anterior descending artery. Follow-up was performed at 3 years with conventional angiography, and at 8 years with computed tomography angiography. Differences between patency rates were analyzed with Fisher's exact test and a generalized linear model.RESULTS: The patency rates for pedicled and skeletonized left internal thoracic artery grafts were 46/48 (95.8%) versus 47/52 (90.4%), p = 0.44 at 3 years, and 40/43 (93.0%) versus 37/41 (90.2%), p = 0.71 at 8 years, respectively. The difference in patency rates for pedicled and skeletonized grafts was 5.4% (95% confidence interval: -4.2-14.5) at 3 years and 2.8% (95% confidence interval: -9.9-14.1) at 8 years. All failed grafts, except for one with a localized stenosis, were anastomosed to native coronary arteries with a stenosis less than 70%. Three patients suffered sternal wound infections (two in the pedicled group, one in the skeletonized group).CONCLUSIONS: The skeletonization technique can be used without jeopardizing the patency of the left internal thoracic artery. The most important factor in graft failure was target artery stenosis below 70%.
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| 8. |
- Dreifaldt, Mats, 1959-, et al.
(författare)
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The no-touch saphenous vein is an excellent alternative conduit to the radial artery 8 years after coronary artery bypass grafting : A randomized trial
- 2021
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Ingår i: Journal of Thoracic and Cardiovascular Surgery. - : Elsevier. - 0022-5223 .- 1097-685X. ; 161:2, s. 624-630
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Tidskriftsartikel (refereegranskat)abstract
- Background: In 2004, a prospective randomized trial demonstrated that after 3 years, saphenous veins (SVs) harvested with a no touch (NT) technique had a greater patency than radial grafts for coronary bypass surgery. Here we report the 8-year follow-up data of this trial.Methods: The trial included 108 patients undergoing coronary artery bypass grafting (CABG). Each patient was assigned to receive 1 NT SV and 1 radial artery (RA) graft to either the left or right coronary territory to complement the left internal thoracic artery (LITA). Sequential grafting was common, so overall graft patency as well as the patency of each anastomosis were assessed.Results: Angiography was performed in 84 patients (78%) at mean of 97 months postoperatively. Graft patency were high and similar for both NT and RA: 86% for NT versus 79% for RA (P = .22). The patency of coronary anastomoses was significantly higher with the NT SV grafts (91% vs 81%; P = .046). The NT grafts also had excellent patency in coronary arteries with <90% stenosis (93% patency) and in coronary arteries of small diameter (87% patency) or with mild calcification (88% patency). Patency for the LITA was 92%.Conclusions: NT SV grafts have excellent patency similar to that of RA grafts after 8 years. In addition, NT SV grafts can be used in situations that are not ideal for RA grafts.
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| 10. |
- Geijer, Håkan, 1961-, et al.
(författare)
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Added value of double reading in diagnostic radiology, a systematic review
- 2018
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Ingår i: Insights into Imaging. - : Springer. - 1869-4101. ; 9:3, s. 287-301
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Forskningsöversikt (refereegranskat)abstract
- OBJECTIVES: Double reading in diagnostic radiology can find discrepancies in the original report, but a systematic program of double reading is resource consuming. There are conflicting opinions on the value of double reading. The purpose of the current study was to perform a systematic review on the value of double reading.METHODS: A systematic review was performed to find studies calculating the rate of misses and overcalls with the aim of establishing the added value of double reading by human observers.RESULTS: The literature search resulted in 1610 hits. After abstract and full-text reading, 46 articles were selected for analysis. The rate of discrepancy varied from 0.4 to 22% depending on study setting. Double reading by a sub-specialist, in general, led to high rates of changed reports.CONCLUSIONS: The systematic review found rather low discrepancy rates. The benefit of double reading must be balanced by the considerable number of working hours a systematic double-reading scheme requires. A more profitable scheme might be to use systematic double reading for selected, high-risk examination types. A second conclusion is that there seems to be a value of sub-specialisation for increased report quality. A consequent implementation of this would have far-reaching organisational effects.KEY POINTS: • In double reading, two or more radiologists read the same images. • A systematic literature review was performed. • The discrepancy rates varied from 0.4 to 22% in various studies. • Double reading by sub-specialists found high discrepancy rates.
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