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Imaging in Idiopathic Normal Pressure Hydrocephalus: The value of structured radiological evaluation
Umeå University, Faculty of Medicine, Department of Clinical Sciences, Neurosciences.ORCID iD: 0000-0002-4686-0941
2020 (English)Doctoral thesis, comprehensive summary (Other academic)Alternative title
Bilddiagnostik vid idiopatisk normaltryckshydrocephalus : Värdet av strukturerad radiologisk utvärdering (Swedish)
Abstract [en]

Background: Idiopathic normal pressure hydrocephalus (iNPH) is a neurological condition where the symptoms include disturbed gait, balance, cognition and continence. The diagnostic guidelines are based on typical symptoms combined with imaging showing enlarged ventricles. Several scales for evaluating symptoms exist, but no corresponding tool is in use for imaging. The aim of this thesis was to construct a radiological scoring system, the iNPH Radscale, to facilitate radiological evaluation and systematic reporting of changes. Further, to test the reliability and accuracy of the scale and evaluate the usefulness for longitudinal monitoring.

Methods: In paper I 168 individuals over 65 years of age from the general population underwent computed tomography (CT) of the brain and a neurological examination, and the same cohort was followed up 2 years later in paper IV. The iNPH Radscale was developed in these papers and further validated in papers II and III. Papers II and III included surgically treated iNPH patients with preoperative imaging of the brain. Thirty-five patients were included in paper II comparing preoperative CT and magnetic resonance imaging (MRI) using the iNPH Radscale. Paper III included 75 shunt responsive patients and 55 asymptomatic controls to evaluate the accuracy of the iNPH Radscale.

Results: In paper I, seven parameters summarized as a total iNPH Radscale score were significantly associated with clinical iNPH symptoms (r = 0.55, p < 0.001). In paper II, the agreement between CT and MRI was substantial to almost perfect (kappa and intraclass correlation, 0.60–0.91, p < 0.001) for all parameters except periventricular white matter changes. In paper III the iNPH Radscale score was significantly higher in the iNPH group than the control group (p <0.001). Receiver operating characteristics analysis yielded an area under the curve of 99.7 %, and an iNPH Radscale score £ 4 identified those without iNPH (sensitivity 100 %, specificity 96 % and overall accuracy 98.5 %). In paper IV, symptomatic participants had significantly higher iNPH Radscale scores at baseline and follow-up.

Conclusions: The iNPH Radscale summarizes seven imaging features from the diagnostic guidelines and is applicable to both CT and MRI. INPH is very likely in patients with an iNPH Radscale score ³ 8 and corresponding clinical symptoms. On the other hand, the diagnosis should be questioned when the iNPH Radscale score is less than the cut-off of 4. In summary, the iNPH Radscale may become a relevant diagnostic tool for standardized evaluation in the workup of patients with suspected iNPH, as a diagnostic checklist and as a screening tool for detection with the potential for ruling out the disease.

Place, publisher, year, edition, pages
Umeå: Umeå Universitet , 2020. , p. 67
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 2074
Keywords [en]
normal pressure hydrocephalus, gait disorder, computed tomography, magnetic resonance imaging
National Category
Radiology, Nuclear Medicine and Medical Imaging
Research subject
Diagnostic Radiology
Identifiers
URN: urn:nbn:se:umu:diva-169521ISBN: 978-91-7855-216-0 (electronic)ISBN: 978-91-7855-215-3 (print)OAI: oai:DiVA.org:umu-169521DiVA, id: diva2:1427869
Public defence
2020-05-29, Hörsalen Snäckan, Östersunds sjukhus, Östersund, 09:00 (Swedish)
Opponent
Supervisors
Note

Hörsalen är stängd för allmänheten så länge Corona-pandemin fortgår. Med anledning av disputationen 29 maj, öppnas Hösalen tillfälligt för de personer som absolut måste närvara fysiskt, för att disputationsakten ska godkännas. Allmänheten kommer kunna delta vid livesändning via länken: https://m.youtube.com/watch?feature=youtu.be&v=k2gw3eOyYxE

Available from: 2020-05-08 Created: 2020-05-03 Last updated: 2020-05-29Bibliographically approved
List of papers
1. The idiopathic normal-pressure hydrocephalus Radscale: a radiological scale for structured evaluation
Open this publication in new window or tab >>The idiopathic normal-pressure hydrocephalus Radscale: a radiological scale for structured evaluation
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2018 (English)In: European Journal of Neurology, ISSN 1351-5101, E-ISSN 1468-1331, Vol. 25, no 3, p. 569-576Article in journal (Refereed) Published
Abstract [en]

Background and purpose: Despite the important role of imaging in diagnosing idiopathic normal‐pressure hydrocephalus (iNPH), a structured overall assessment of radiological signs is still lacking. The purpose of this study was to construct a radiological scale, composed of morphological signs of iNPH, and compare it with clinical symptoms.

Methods: In this prospective, population‐based study of iNPH, 168 individuals (93 females) [mean age 75 (range 66–92) years] underwent computed tomography of the brain and a neurological examination with assessment of clinical symptoms according to Hellström's iNPH scale. Two radiologists, blinded to clinical data, independently evaluated and measured eight radiological parameters, i.e. Evans’ index, callosal angle, size of temporal horns, narrow high‐convexity sulci, dilated Sylvian fissures, focally dilated sulci, peri‐ventricular hypodensities and bulging of the lateral ventricular roof.

Results: In a linear regression model, all parameters except ventricular roof bulging were significantly associated with clinical iNPH symptoms. The seven remaining parameters were summarized into a total iNPH Radscale score ranging from 0 to 12. There was a significant correlation (r = 0.55, < 0.001) between the total iNPH Radscale score and clinical symptoms. The inter‐rater agreement for the included radiological parameters was high (intraclass correlation, 0.74–0.97).

Conclusion: The iNPH Radscale may become a valuable diagnostic screening tool, allowing a structured radiological assessment. A high iNPH Radscale score together with clinical symptoms should raise suspicion of iNPH, motivating further evaluation for shunt surgery.

Keywords
computed tomography, neurologic gait disorders, normal pressure hydrocephalus, memory disorders
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:umu:diva-145580 (URN)10.1111/ene.13555 (DOI)000425631500025 ()29281156 (PubMedID)
Available from: 2018-03-22 Created: 2018-03-22 Last updated: 2020-05-03Bibliographically approved
2. Standardized image evaluation in patients with idiopathic normal pressure hydrocephalus: consistency and reproducibility
Open this publication in new window or tab >>Standardized image evaluation in patients with idiopathic normal pressure hydrocephalus: consistency and reproducibility
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2019 (English)In: Neuroradiology, ISSN 0028-3940, E-ISSN 1432-1920, Vol. 61, no 12, p. 1397-1406Article in journal (Refereed) Published
Abstract [en]

Purpose: Assess the agreement for two investigators between computed tomography (CT) and magnetic resonance imaging (MRI) for seven imaging features included in the iNPH Radscale, a radiological screening tool.

Methods: The study included 35 patients with idiopathic normal pressure hydrocephalus (iNPH) who were treated surgically from 2011 to 2015 at Uppsala University Hospital with preoperative CT and MRI performed with maximum 3 months between scans. Seven features were assessed: Evans’ index, temporal horn size, callosal angle, periventricular white matter changes, narrow high convexity sulci, focally enlarged sulci, and enlarged Sylvian fissures. All scans were assessed by two investigators who were blinded to each other’s results and to clinical data.

Results: The agreement between CT and MRI was almost perfect for Evans’ index, temporal horns, narrow sulci, and Sylvian fissures (kappa and intraclass correlation, 0.84–0.91, p ≤ 0.001). There was substantial to almost perfect agreement for callosal angle and focally enlarged sulci. The concordance between modalities was fair for changes in periventricular white matter.

Conclusion: CT and MRI are equally good for assessing radiological signs associated with iNPH except for periventricular white matter changes, as MRI has superior soft tissue contrast. The other imaging features can be evaluated consistently, and assessments are reproducible independent of modality. Therefore, the iNPH Radscale is applicable to both CT and MRI and may become an important tool for standardized evaluation in the workup in patients with suspected iNPH.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
Hydrocephalus, normal pressure, Magnetic resonance imaging, Tomography, x-ray computed, Observer variation
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:umu:diva-165745 (URN)10.1007/s00234-019-02273-2 (DOI)000495810200006 ()31399851 (PubMedID)
Available from: 2019-12-10 Created: 2019-12-10 Last updated: 2020-05-05Bibliographically approved
3. Diagnostic accuracy of the iNPH Radscale in idiopathic normal pressure hydrocephalus
Open this publication in new window or tab >>Diagnostic accuracy of the iNPH Radscale in idiopathic normal pressure hydrocephalus
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2020 (English)In: PLoS ONE, E-ISSN 1932-6203, Vol. 15, no 4, article id e0232275Article in journal (Refereed) Published
Abstract [en]

Background and purpose: The idiopathic normal pressure hydrocephalus (iNPH) Radscale was developed to standardize the evaluation of radiological signs in iNPH. The purpose of this study was to estimate the diagnostic accuracy of the iNPH Radscale in a sample of “true positive” and “true negative” cases.

Methods: Seventy-five patients with definite iNPH, i.e. who had improved at clinical follow-up one year after ventriculoperitoneal shunt surgery, were compared with 55 asymptomatic individuals from the general population. A radiologist assessed the seven radiological features of the iNPH Radscale in computed tomography of the brain in the patients (preoperatively) and controls.

Results: The iNPH Radscale score was significantly higher in the iNPH group (Median = 10, interquartile range 9–11) than in the control group (Median = 1, interquartile range 1–2) (p <0.001). Receiver operated characteristics analysis yielded an area under the curve of 99.7%, and an iNPH Radscale score ≤ 4 identified those without iNPH, with a sensitivity of 100%, specificity of 96% and overall accuracy of 98.5%.

Conclusions: In this study, iNPH Radscale could accurately discriminate between patients with definite iNPH and asymptomatic individuals over 65 years old. According to the results, a diagnosis of iNPH is very likely in patients with an iNPH Radscale score above 8 and corresponding clinical symptoms. On the other hand, the diagnosis should be questioned when the iNPH Radscale score is below the cut-off level of 4. We conclude that the iNPH Radscale could work as a diagnostic screening tool to detect iNPH. Whether the scale also can be used to predict shunt outcome needs further studies.

Place, publisher, year, edition, pages
San Francisco: Public Library of Science, 2020
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:umu:diva-169522 (URN)10.1371/journal.pone.0232275 (DOI)32330190 (PubMedID)
Available from: 2020-04-03 Created: 2020-04-03 Last updated: 2020-05-05Bibliographically approved
4. Imaging in idiopathic Normal Pressure Hydrocephalus: longitudinal changes in radiological signs
Open this publication in new window or tab >>Imaging in idiopathic Normal Pressure Hydrocephalus: longitudinal changes in radiological signs
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(English)Manuscript (preprint) (Other academic)
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:umu:diva-169523 (URN)
Available from: 2020-04-03 Created: 2020-04-03 Last updated: 2020-05-05

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