analysis of brain t1/t2 ratio histogram in the patients with sickle cell disease comparing with the...
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Analysis of Brain T1/T2 Ratio Histogram in the Patients with Sickle Cell Disease
Comparing with the Normal Controls
Memi Watanabe1, Karen Buch1, Hernan Jara1,Kotaro Sekiya1, and Osamu Sakai1,2,3
Departments of 1Radiology, 2Otolaryngology–Head and Neck Surgery, and 3Radiation Oncology Boston Medical Center, Boston University School of Medicine, Boston, MA
Presentation Number: EP-59
Disclosures
HJ: Activities related to the present work: disclosed no relevant relationships. Activities not related to the present work: institution received a grant from GE Healthcare.
Introduction (I)
• Cerebral complications associated with sickle cell disease (SCD) include cerebral infarction, intracranial hemorrhage, and neurocognitive impairment.• Those complications can lead to life-long disabilities and even death.• Conventional imaging techniques have limited sensitivity and specificity to identify patients at risk.
Introduction (II)
• T1 and T2 are temporal measures of equilibration of the longitudinal and transverse magnetizations respectively.• Although T1 and T2 contain different physical information, some information is common.
Introduction (III)
• Calculating the T1/T2 ratio is step towards “purifying” the physical information content of T1, thus potentially increasing its sensitivity and specificity to disease*.
T1 T2 T1/T2
(*) Farraher SW, Jara H, Chang KJ, Ozonoff A, Soto JA. Differentiation of hepatocellular carcinoma and hepatic metastasis from cysts and hemangiomas with calculated T2 relaxation times and the T1/T2 relaxation times ratio. J Magn Reson Imaging 2006;24(6):1333-1341.
Purpose
The purpose of this study was to investigate the manifestations of brain abnormalities in patients with SCD using quantitative MRI (qMRI) parameters, specifically T1/T2 ratio and T1 and T2 relaxation times.
SubjectsFollowing IRB* approval and HIPAA** compliance, 14 SCD patients and 12 age-matched patient controls without apparent abnormalities on conventional brain MRI.
SCD controlGender 5 males : 9 females 4 males : 8 females
Age 19.8 - 43 years (mean 29.3 years)
17 – 48.6 years (mean 36.6 years)
Materials and Methods
Inclusion criteria for controlsNormal brain parenchyma on MR studies, including nonspecific white matter T2 hyperintensities <5mm, <3 lesions
* IRB: internal review board* * HIPAA: Health Insurance Portability and Accountability Act guidelines of the National Institutes of Health
Image acquisition
Sequence: Institutional clinical protocol (T1WI, fat-suppressed GRASE* T2WI, FLAIR, FFE*, DWI) and mixed turbo spin echo (mixed-TSE) pulse sequence*GRASE: gradient and spin echo , *FFE: fast field echo
Key imaging parameters for mixed-TSE: effective echo time 7.142 and 100 ms, repetition time 14,882 ms, inversion time 700 and 7,441 ms, echo train length 18 (9 per echo: centric, liner)
MRI: 1.5T (Achieva or Intera, Philips Medical Systems, Cleveland, OH)
Image processing
Mixed-TSE dataset
Segmentation of the whole intracranial volume
Histogram generation:T1 and T2 relaxation times, T1/T2 ratio
Gaussian analysis: peak histogram values
Between-group comparison
SCD vs. Controls:• No significant difference in age (p=0.06)
SubjectsResults
MRI findings in SCD patients (n=14):Abnormal MRI (n=7)
Multiple old infarcts, non-specific T2 hyperintense foci, and mild atrophy
Normal MRI (n=7)
T1 histogram• bi-modal (GM and WM)• long T1 for CSF
HistogramsResults
GM
CSFWM
CSF
WM+GM
WMGM
CSF
T2 histogram• mono-modal (GM+WM)• long T2 for CSF
T1/T2 ratio histogram• bi-modal (GM and WM)
T1 (ms)
T2 (ms)
T1/T2 ratio
Pixel frequency
Pixel frequency
Pixel frequency
T1 peak values vs. Age
No significant difference between SCD and controls for T1 histograms
• GM peaks: p=0.83• WM peaks: p=0.47
Age (years)
T2 peak values vs. Age
No significant differences between SCD and controls in T2 histograms
• T2 histogram peaks: p=0.09
Age (years)
T1/T2 ratio peak values vs. Age
Significant differences between SCD and controls for T1/T2 ratio histograms
• GM peaks: p<0.0001• WM peaks: p=0.046
Age (years)
T1/T2 ratio peak values vs. Age
• Lower GM peak values in SCD subjects• Age-associated decreases in GM peak values in SCD • Slight increases in GM peaks in controls
Age (years)
Brain MR relaxometry in SCDBrain T1 measurements in SCD children vs..
controls (Steen et al, 1998 and 1999)• Significantly lower T1 in caudate, thalamus, and
cortex in SCD patients normal by conventional MRI• Significant decline in T1 with increasing disease
seventy in the cortical GM and caudate• Significant increase in WM T1 only in the later
stage of the disease
Discussion
Vulnerability of the gray matter
Diffusion studies in SCD• Decline in fractional anisotropy (FA),
increases in apparent diffusion coefficient (ADC) within brain regions, including corpus callosum, frontal WM, centrum semiovale, periventricular areas, head of the caudate nucleus, thalamus, and brainstem
• Reductions in fiber counts• Correlations of increased ADC with
deficiencies in cognitive function
Disrupted white matter integrityPossible association with cognitive impairment
T1/T2 ratio histogram analysis in SCD
• Significant differences in GM peak- Lower GM peak values- Age-associated decline in GM peak values
• Statistically significant decreases in WM peak values
• While T1 and T2 histograms did not show statistically significant differences
Suggestive of damages within GM and WMLarger differences in GM parameters
Conclusion
• This study shows significant differences between SCD and control group in GM peak values of the T1/T2 ratio histogram.
• T1 and T2 histograms did not show statistically significant differences between SCD patients and controls.
• The T1/T2 ratio of the brain may be more sensitive and useful for the quantitative assessment of the pathological conditions including SCD.
• The assessment of the association with cognitive impairment with a larger number of SDC patients including children is anticipated.
Conclusion
References
Corresponding AuthorMemi Watanabe, MD.
Department of Radiology, Boston Medical Center Boston University School of Medicine
E-mail address: [email protected]
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