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Volume imaging of the abdomen: three-dimensional visualisation of tubular structures in the body with CT and MRI
Linköping University, Department of Biomedicine and Surgery, Oncology. Linköping University, Department of Medicine and Care, Radiology. Linköping University, Department of Molecular and Clinical Medicine, Clinical Immunology. Linköping University, Faculty of Health Sciences.ORCID iD: 0000-0002-9446-6981
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The overwhelming amount of image-based information in modem medicine makes it crucial to develop methods to handle and analyze images and make them comprehensible for users. The aim of this thesis was to study the radiological practice of three-dimensional (3D) visualization of tubular structures in the body with CT and MRI. All the studies cancern 3D imaging of tubular structures with camputed tomography (CT) and magnetic resonance imaging (MRI). The first three studies examine the abdominal aorta; the two later ones the, bile ducts.

Study I compared measurements of aorta diameters taken from MR images presented using two visualization methods - maximum intensity projection (MlP) and volume rendering (VRT) - with invasive angiography (DSA) and CT as reference methods. Mean diameters of MR images were smaller than those from DSA and CT when MlP was used, but in general not when VRT was used.

Study II evaluated the dependence on the observer and the choice of method and settings during rendering using the same material as in Study 1. In both MlP and VRT, the choice of settings had significant influence on the results. With DSA as the reference method, VRT gave larger measurement errors than MIP when the rendering parameters were set to fixed values, but not if the user was allowed to select the settings freely.

Study III evaluated three new techniques for standardizing VRT protocols for MRA. Inter-reader variability and agreement with DSA were studied by comparing diameter measurements of the abdominal aorta obtained by the three new techniques, by VRT with freely chosen parameters and by MlP. All three new methods were significantly better than MlP and VRT with freely chosen parameters conceming inter-observer agreement. Agreement with DSA was significantly better for one of the methods. Standardized protocols seem to have a potential to make VRT a clinically useful alternative to MlP for MR angiography measurements.

Study IV evaluated CT imaging of the bile ducts after drip intravenous infusion of the contrast medium iotroxate (CT cholangiography) in terms of adverse effects and visibility. With infusion time adjusted for individual variation in serum bilirubin concentration, a total side-effect frequency of less than 1% was found. A systematic review of previously published studies indicated a frequency of 2.3%. Good contrast excretion and visualization of bile ducts even in patients with elevated bilirubin levels were noted.

Study V evaluated the diagnostic benefits of the same imaging method by comparing it with findings from surgery and endoscopic retrograde cholangiopancreatography (ERCP). The consensus sensitivity and specificity for diagnosing biliary stones was 88% and 94%, respectively. The use of VRT improved diagnostic certainty in 14% of the evaluatians, and the visualization of ductal stones was improved in 38% of the positive cases.

In conclusion, volume rendering technique with standardized parameters may become a clinically useful tool in the clinical MRI environment. DIC-CT with bilirubin-governed infusion time and volume rendering post-processing produces detailed images of the biliary tree, resulting in good sensitivity and specificity. Moreover the safety is acceptable.

Place, publisher, year, edition, pages
Linköping: Linköpings universitet , 2005. , 103 p.
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 912
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:liu:diva-29581Local ID: 14957ISBN: 91-85299-25-1 (print)OAI: oai:DiVA.org:liu-29581DiVA: diva2:250398
Public defence
2005-10-07, Berzeliussalen, plan 09, Hälsouniversitetet, Campus US, Linköpings universitet, Linköping, 13:00 (Swedish)
Opponent
Supervisors
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2013-10-21Bibliographically approved
List of papers
1. Measurements before endovascular repair of abdominal aortic aneurysms: MR imaging with MRA vs. angiography and CT
Open this publication in new window or tab >>Measurements before endovascular repair of abdominal aortic aneurysms: MR imaging with MRA vs. angiography and CT
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2003 (English)In: Acta Radiologica, ISSN 0284-1851, E-ISSN 1600-0455, Vol. 44, no 2, 177-184 p.Article in journal (Refereed) Published
Abstract [en]

Purpose: 1) To compare measurements obtained with MR imaging (MRI)/contrast-enhanced MR angiography (CE MRA) with measurements obtained with angiography (DSA) and CT, for stent-graft sizing of abdominal aortic aneurysms (AAA). 2) To compare MRA measurements obtained with the two post processing techniques MIP (maximum intensity projection) and VRT (3D volume rendering technique).

Material and Methods: The prospective study included 20 consecutive patients with AAA identified by DSA and CT as suitable for endovascular repair. For the study, MRI/CE MRA was performed. Five measurement variables for stent-graft sizing were chosen. Comparisons were made between MRI/CE MRA, DSA and CT, and between observers. Comparisons were also made between MIP and VRT.

Results: Significantly shorter lengths were obtained with MRA-MIP than with DSA. Three out of six diameter measurements were significantly smaller on MRI/CE MRA than on DSA and CT. No significant differences were found between the observers. One diameter measurement was significantly smaller on MIP than on VRT, while the other measurements showed no significant differences.

Conclusion: The length measurements obtained with MRA-MIP were probably more correct than those with DSA. For more reliable diameter measurements with CE MRA, improvements of the technique, including VRT reconstructions and a standardized determination of the vessel boundaries, are needed.

Keyword
Abdominal aortic aneurysm, Angiography, CT, Endograft sizing, MR angiography, Volume rendering technique
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-46720 (URN)10.1034/j.1600-0455.2003.00029.x (DOI)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-13Bibliographically approved
2. Volume rendering compared with maximum intensity projection for magnetic resonance angiography measurements of the abdominal aorta
Open this publication in new window or tab >>Volume rendering compared with maximum intensity projection for magnetic resonance angiography measurements of the abdominal aorta
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2004 (English)In: Acta Radiologica, ISSN 0284-1851, E-ISSN 1600-0455, Vol. 45, no 4, 453-459 p.Article in journal (Refereed) Published
Abstract [en]

Purpose: To compare the volume rendering technique (VRT) with maximum intensity projection (MIP) for aortic diameter measurements in MR angiography (MRA) data sets.

Material and Methods: Existing contrast-enhanced 3-dimensional MRA and digital subtraction angiography (DSA) data sets from 20 patients were analyzed. In each MRA data set, two aortic diameters were measured using MIP and VRT. Agreement with DSA measurements, dependence on rendering parameters, and interobserver agreement were assessed.

Results: Diameters measured on MIP with fixed parameters showed no significant difference compared with DSA and with freely selected parameters a slight overestimation relative to DSA. Diameters measured on VRT were larger than on DSA. For both MIP and VRT, the measurements depended on the chosen parameters. The error relative to DSA was larger for VRT than for MIP with fixed parameters but not with freely chosen parameters. Interobserver agreement did not differ significantly.

Conclusions: VRT is not suitable for diameter measurements of the abdominal aorta with fixed parameter settings but may be useful with user-selected settings.

Keyword
Abdominal aortic aneurysm AAA, angiography, magentic resonance angiography MRA, maximum intensity projection MIP, under dependence, volume rendering technique VRT
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-24036 (URN)10.1080/02841850410006876 (DOI)3592 (Local ID)3592 (Archive number)3592 (OAI)
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2017-12-13Bibliographically approved
3. Standardized volume rendering for magnetic resonance angiography measurements in the abdominal aorta
Open this publication in new window or tab >>Standardized volume rendering for magnetic resonance angiography measurements in the abdominal aorta
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2006 (English)In: Acta Radiologica, ISSN 0284-1851, E-ISSN 1600-0455, Vol. 47, no 2, 172-178 p.Article in journal (Refereed) Published
Abstract [en]

Purpose: To compare three methods for standardizing volume rendering technique (VRT) protocols by studying aortic diameter measurements in magnetic resonance angiography (MRA) datasets.

Material and Methods: Datasets from 20 patients previously examined with gadolinium-enhanced MRA and with digital subtraction angiography (DSA) for abdominal aortic aneurysm were retrospectively evaluated by three independent readers. The MRA datasets were viewed using VRT with three different standardized transfer functions: the percentile method (Pc-VRT), the maximum-likelihood method (ML-VRT), and the partial range histogram method (PRH-VRT). The aortic diameters obtained with these three methods were compared with freely chosen VRT parameters (F-VRT) and with maximum intensity projection (MIP) concerning inter-reader variability and agreement with the reference method DSA.

Results: F-VRT parameters and PRH-VRT gave significantly higher diameter values than DSA, whereas Pc-VRT gave significantly lower values than DSA. The highest interobserver variability was found for F-VRT parameters and MIP, and the lowest for Pc-VRT and PRH-VRT. All standardized VRT methods were significantly superior to both MIP and F-VRT in this respect. The agreement with DSA was best for PRH-VRT, which was the only method with a mean error below 1 mm and which also had the narrowest limits of agreement (95% of cases between 2.1 mm below and 3.1 mm above DSA).

Conclusion: All the standardized VRT methods compare favorably with MIP and VRT with freely selected parameters as regards interobserver variability. The partial range histogram method, although systematically overestimating vessel diameters, gives results closest to those of DSA.

Keyword
Abdominal aortic aneurysm (AAA); angiography; magnetic resonance angiography (MRA); maximum intensity projection (MIP); volume rendering technique (VRT); user dependence
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-14591 (URN)10.1080/02841850500445298 (DOI)000236669500010 ()
Available from: 2007-08-24 Created: 2007-08-24 Last updated: 2017-12-13Bibliographically approved
4. Three-dimensional drip infusion CT cholangiography in patients with suspected obstructive biliary disease: a retrospective analysis of feasibility and adverse reaction to contrast material
Open this publication in new window or tab >>Three-dimensional drip infusion CT cholangiography in patients with suspected obstructive biliary disease: a retrospective analysis of feasibility and adverse reaction to contrast material
2006 (English)In: BMC Medical Imaging, ISSN 1471-2342, E-ISSN 1471-2342, Vol. 6, no 1Article in journal (Refereed) Published
Abstract [en]

Background

Computed Tomography Cholangiography (CTC) is a fast and widely available alternative technique to visualise hepatobiliary disease in patients with an inconclusive ultrasound when MRI cannot be performed. The method has previously been relatively unknown and sparsely used, due to concerns about adverse reactions and about image quality in patients with impaired hepatic function and thus reduced contrast excretion. In this retrospective study, the feasibility and the frequency of adverse reactions of CTC when using a drip infusion scheme based on bilirubin levels were evaluated.

Methods

The medical records of patients who had undergone upper abdominal spiral CT with subsequent three-dimensional rendering of the biliary tract by means of CTC during seven years were retrospectively reviewed regarding serum bilirubin concentration, adverse reaction and presence of visible contrast media in the bile ducts at CT examination. In total, 153 consecutive examinations in 142 patients were reviewed.

Results

Contrast media was observed in the bile ducts at 144 examinations. In 110 examinations, the infusion time had been recorded in the medical records. Among these, 42 examinations had an elevated bilirubin value (>19 umol/L). There were nine patients without contrast excretion; 3 of which had a normal bilirubin value and 6 had an elevated value (25–133 umol/L). Two of the 153 examinations were inconclusive. One subject (0.7%) experienced a minor adverse reaction – a pricking sensation in the face. No other adverse effects were noted.

Conclusion

We conclude that drip infusion CTC with an infusion rate of the biliary contrast agent iotroxate governed by the serum bilirubin value is a feasible and safe alternative to MRC in patients with and without impaired biliary excretion.

In this retrospective study the feasibility and the frequency of adverse reactions when using a drip infusion scheme based on bilirubin levels has been evaluated.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-34913 (URN)10.1186/1471-2342-6-1 (DOI)24035 (Local ID)24035 (Archive number)24035 (OAI)
Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2017-12-13Bibliographically approved
5. Volume rendering of three-dimensional drip infusion CT cholangiography in patients with suspected obstructive biliary disease: a retrospective study
Open this publication in new window or tab >>Volume rendering of three-dimensional drip infusion CT cholangiography in patients with suspected obstructive biliary disease: a retrospective study
2005 (English)In: British Journal of Radiology, ISSN 0007-1285, E-ISSN 1748-880X, Vol. 78, no 936, 1078-1085 p.Article in journal (Refereed) Published
Abstract [en]

The purpose of this study was to evaluate the diagnostic potential of prolonged drip infusion CT cholangiography (DIC-CT) using meglumine iotroxate (Biliscopin®) and 3D volume rendering in patients with suspected obstructive biliary disease. From a material of 142 patients who had undergone a drip infusion CT, all cases with a verified surgical or endoscopic retrograde cholangiography (ERC) diagnosis (n=33) were selected. Age-matched controls were selected from the remaining examinations. Three radiologists reviewed all 66 examinations in retrospect, independently as well as in consensus. The image quality and the estimated diagnostic quality were rated as good or moderate in 91% of the 198 reviews. The consensus sensitivity and specificity for diagnosing biliary stones was 88% and 94%, respectively (with sensitivities ranging from 88% to 94% for individual observers, and specificities from 86% to 96%). Two out of three strictures were observed. No false positive strictures were described. The use of volume rendering technique (VRT) improved diagnostic certainty in 28/198 (14%) of the evaluations. The visualization of ductal stones was improved in 18/48 (38%). No differences in diagnostic quality between single and multislice CT were observed. We conclude that a detailed image of the biliary tree with good sensitivity and specificity can be obtained by means of bilirubin-governed infusion time DIC-CT with volume rendering reconstruction.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-30833 (URN)10.1259/bjr/14176682 (DOI)16483 (Local ID)16483 (Archive number)16483 (OAI)
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2017-12-13Bibliographically approved

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