1. Parenchyma Nulling T1 Weighted Inversion Recovery: Improving the Detection of Brain Tumors
Ali Batouli1
Dennis Monks1
Sobia Mirza1
Michael Goldberg1
Emanuel Kanal2
Michael Spearman1
1Allegheny Health Network
2University of Pittsburgh
eP-103

2. Disclosures
The authors have no disclosures

3. Purpose
Compare the effectiveness of a novel parenchyma nulling T1 weighted inversion recovery sequence (PNIR) to that of spin echo magnetization transfer (SEMT) in detecting enhancing brain tumors.

4. Materials and Methods
PNIR sequence parameters were developed to reduce signal from gray matter (GM), white matter (WM) and CSF in a healthy adult volunteer.

5. Sequence Parameters PNIR (test) SEMT (standard) TR (ms) 700 445
TE (ms) 11 17
Excitations 2 1
Concatenations 5
Flip Angle
150
Acquisition time (mins)
04:38
02:35
Sections 23
Matrix
256 x 192
Field of View (mm)
230
Slice thickness (mm)
Gap (mm)
1.5

6. Sample and Design
41 patients with known or suspected brain tumors underwent PNIR (test) and SEMT (standard of care) imaging after the administration of intravenous gadobenate dimeglumine.
Patients ranged from 21 to 74 years old (mean 51)
14 of the patients had enhancing brain tumors, with a total of 23 tumors analyzed
Tumor pathology included GBM, meningoma, grade 3 astrocytoma, ganglioglioma and metastases

7. Outcomes Tested
In patients with tumors, the following comparisons were made:
Tumor-to-WM, Tumor-to-GM, Tumor-to-CSF contrast ratios (CR)
Contrast Ratio = (Tumor Signal – Background Tissue Signal)/ Background Tissue Signal
Calculations were done for the maximum and average values found within the tumor

8. Outcomes Tested
In patients with tumors, comparisons were made in regards to
Radiologist rated subjective conspicuity
Two neuroradiologists independently reviewed each tumor on both sequences

9. Results: Normal Patients
PNIR SEMT

10. Signal of Tissues Comparison of absolute signal by tissue type
PNIR (95% CI)
SEMT (95% CI)
Ratio PNIR/SEMT GM
85 (77-93)
329 ( )
0.26 WM
169 ( )
380 ( )
0.44
CSF
22 (19-25)
165 ( )
0.13
Tumor Maximum
440 ( )
709 ( )
0.62
Tumor Average
299 ( )
577 ( )
0.52

11. Improved Contrast Ratio
Contrast Ratio (CR) improved in PNIR sequence in all background tissue types and all tumor types
The greatest improvement in CR was seen with tumor-to-CSF, followed by tumor-to-GM and then tumor-to-WM.

12. Improved Contrast Ratio
Comparison of CR by background tissue
Contrat Ratio
PNIR
SEMT
PNIR / SEMT
P-Value
Average Signal
Tumor-to-GM
2.63
0.73
3.60
0.0001
Tumor-to-WM
0.76
0.58
1.31
0.0435
Tumor-to-CSF
13.03
3.45
3.78
<0.0001
Maximum Signal
4.37
1.16
3.77
1.56
0.88
1.77
0.0007
20.55
3.32
6.19

13. Improved Contrast
Example: Improved conspicuity of occipital lobe metastasis on PNIR
SEMT
PNIR

14. Unanticipated PNIR Effects
PNIR decreased signal from subacute T1 hyperintense hemorrhage
Pre contrast Fast Spin Echo
SEMT + contrast
PNIR + contrast

15. Unanticipated PNIR Effects
Reduced signal in non-enhancing portions of tumors
SEMT
PNIR

16. Shortcomings of PNIR
Detection of lesions in posterior fossa on PNIR somewhat limited by pulsation artifact, which is accentuated by inversion recovery technique
SEMT
PNIR

17. Subjective Conspicuity
Subjective conspicuity was not consistently improved by PNIR
PNIR More Conspicuous
PNIR Less Conspicuous
Equal Conspicuity
PNIR More Artifacts
Radiologist 1
26% (6)
61% (14)
13% (3)
100%
Radiologist 2
48% (11)
43% (10)
9% (2)

18. Subjective Conspicuity
Possible reasons for lack of improvement in subjective conspicuity
Radiologists not accustomed to appearance of PNIR
Increased Artifacts on PNIR
Decreased signal of nonenhancing portions of tumor

19. Conclusions
PNIR provides superior contrast ratio of enhancing tumors to background WM, GM and CSF.
PNIR does not consistently improve radiologist determined lesion conspicuity when compared to SEMT.
PNIR can potentially help differentiate between hemorrhage and enhancement by reducing signal from T1 hyperintense hemorrhage

20. Future Research Improve PNIR through artifact reduction techniques
Improve resolution
Directly test ability of PNIR to help differentiate enhancement from T1 hyperintense hemorrhage

21. References
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Wattjes MP, Lutterbey GG, Gieseke J, et al. Double inversion recovery brain imaging at 3T: Diagnostic value in the detection of multiple sclerosis lesions. AJNR Am J Neuroradiol 2007;28:54-59.
Hori M, Okubo T, Uozumi K, et al. T1-weighted fluid-attenuated inversion recovery at low field strength: a viable alternative for T1-weighted intracranial imaging. AJNR Am J Neuroradiol 2003;24:648–51.
Hou P, Hasan KM, Sitton CW, et al. Phase-Sensitive T1 inversion recovery imaging: A time-efficient interleaved technique for improved tissue contrast in neuroimaging. AJNR Am J Neuroradiol :

22. Thank You