Pediatric brain MRI: Is axial T2-weighted imaging enough for a diagnosis?

Matthias W. Wagner ¹, Marinos Kontzialis ¹, Daniel Seeburg ¹, Steven E. Stern 2, Alexander Oshmyansky 1,2, Andrea Poretti ¹,

Thierry A.G.M. Huisman ¹¹Section of Pediatric Neuroradiology, Division of Pediatric Radiology, Russell H. Morgan

Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; ²School of Mathematical Sciences, Faculty of Science and

Engineering, Queensland University of Technology, Brisbane, QLD, Australia

EP-144

ASNR 53rd Annual Meeting, Chicago, April 25-30, 2015

Disclosure

We have nothing to disclose No relevant financial relations interfering

with the presentation

Introduction↑ financial constraints in health care

need for rapid imaging protocols Our experience: T2w images most helpful in

children: ↑ water content of pediatric brain ↑ signal/noise + contrast/noise ratio↑ anatomical resolution + ↑ high sensitivity for

many pediatric brain diseases Consequently: T2w images ↑ potential for an

initial screening tool in pediatric neuroradiology

Purpose

To determine the sensitivity and specificity of axial T2 weighted images in the evaluation of pediatric brain MRI studies

Axial T2 Full studyversus

Inclusion criteria

1. Age at MRI < 18 years

2. Consecutively acquired head MRIs at the Johns Hopkins Hospital only

3. Studies with final diagnoses confirmed by neuroimaging, laboratory tests, genetic analysis, and/or pathology

Methods 1

1. Evaluation of axial T2 weighted images alone first diagnosis noted

2. Without time lapse: Evaluation of the full study second diagnosis notedDiagnoses noted as “normal” or “abnormal”Calculation of sensitivity and specificity for abnormal studies

Methods 2 Standard of reference: final report of neuroradiology

attendings as available in the PACS

Three readers with different levels of experience Reader 1: 20 years pediatric neuroradiology Reader 2: neuroradiology fellow Reader 3: 4th year radiology resident

Readers were blinded for clinical diagnoses and study indication

161 children (6 children scanned twice) 167 studies per reader

Results 1

Mean age of children: 7.44 ± 5.71 years

Standard of reference: 91 studies “abnormal” 76 studies “normal” Normal study: absence of any pathology

except sinus / mastoid effusion

Results 2

All readers T2 Full study p-Value

Specificity 92.1% 90.4% 0.343

Sensitivity 83.2% 92.3% <0.001

NPV 82.0% 90.7%

PPV 92.7% 92.0%

Results 3Individually T2 Full study p-Value

Reader 1(20 years)

Specificity 92.1% 93.4% 1.00

Sensitivity 87.9% 94.5% 0.041NPV 86.4% 93.4%

PPV 93.0% 94.5%

Reader 2(2 years)

Specificity 92.1% 92.1% 1.00

Sensitivity 84.6% 93.4% 0.013NPV 83.3% 92.1%

PPV 92.8% 93.4%

Reader 3(4th year resident)

Specificity 92.1% 85.5% 0.131

Sensitivity 76.9% 89.0% 0.003NPV 76.9% 86.7%

PPV 92.1% 88.0%

Results 4

3 groups of false negative studies:

1. Group 1: lack of an additional plane Sagittal: Chiari 1 / hypoplastic corpus callosum

2. Group 2: lack of additional sequences DWI: acute stroke SWI/T2*: blood products

3. Group 3: limited reader experience

False negatives on axial T2 Group 1: additional plane

Chiari malformation type 1Sagittal T1w

Tonsillar herniationAxial T2w

“Unremarkable”

False negatives on axial T2 Group 2: additional sequences

Hemorrhagic diffuse axonal injuryAxial T2*w

Hypointense lesionsAxial T2w

Unremarkable

False negatives on axial T2 Group 3: reader experience

Axial T2w: moyamoya disease

Axial T2w: systemic lupus with cerebral atrophy

Results 5

Classification of 14 clinical indications in 2 groups: Group 1: acute clinical findings potentially immediate

consequences for patient care Group 2: non-acute clinical indications

4 false negative diagnoses in Group 1 (acute stroke, diffuse axonal injury, intraaxial hemorrhage)

2 non-acute clinical indications without misread on axial T2-screening (including >1 study):

1. Question of malformation 2. Follow-up for hypoxic-ischemic encephalopathy (HIE)

Studies divided by indicationNumber of

studiesFalse negative studies on axial T2 only

Reader 1 Reader 2 Reader 3

Group 1: Acute clinical indication 191. Question of stroke 8 0 0 12. Question of tumor 7 0 0 03. Trauma 4 3 1 2

Group 2: Non-acute clinical indication 1484. Non-acute neurological findings 34 0 1 35. Tumor follow-up 26 3 4 46. Seizure correlate 19 1 3 37. Question of malformation 18 0 0 08. Malformation follow-up 18 2 2 49. Phakomatosis follow-up 12 2 2 210. Developmental delay 11 1 1 111. HIE follow-up 7 0 0 012. Infectious disease follow-up 1 0 0 013. Question of phakomatosis 1 0 0 014. Stroke follow-up 1 0 0 0

Conclusion 1

1a. Axial T2-weighted images alone can identify abnormal studies with high reliability

1b. High level of experience further increases sensitivity and specificity

Conclusion 22a. False negative results make introduction of

solitary axial T2-screening currently unfeasible

2b. Additional DWI + SWI sequences to a 3D- T2w sequence: ↑ imaging time, but still faster than standard protocols possible new screening tool in children with neurologic symptoms (as alternative to CT)