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Optimization of inversion time for postmortem short-tau inversion recovery (STIR) MR imaging
Tomoya Kobayashi1, Masahiko Monma, Takeshi Baba
1Department of Radiological Technology, Tsukuba Medical Center Hospital.
Purpose:
Signal intensity and image contrast differ between postmortem magnetic resonance (PMMR) images and images acquired from the living body. We sought to achieve sufficient fat suppression with short-tau inversion recovery (STIR) PMMR imaging by optimizing inversion time (TI).
Material And Methods:
We subjected 37 deceased adult patients to PMMR imaging at 1.5 tesla 8 to 60 hours after confirmation of death and measured T1 values of areas of subcutaneous fat with relaxation time maps. Rectal temperature (RT) measured immediately after PMMR ranged from 6 to 31°C. We used Pearson's correlation coefficient to analyze the relationship between T1 and relaxation time (RT). We compared STIR images from 4 cadavers acquired with a TI commonly used in the living body and another TI calculated from the linear regression of T1 and RT.
Results:
T1 values of subcutaneous fat ranged from 89.4 to 182.2 ms. There was a strong, positive, and significant correlation between T1 and RT (r = 0.91, P < 0.0001). The regression expression for the relationship was T1 = 2.6*RT + 90 at a field strength of 1.5T. The subcutaneous fat signal was suppressed more effectively with the optimized TI.
Conclusion:
The T1 value of subcutaneous fat in PMMR correlates linearly with body temperature. Using this correlation to determine TI, fat suppression with PMMR STIR imaging can be easily improved.
Insights
Postmortem MRI fat suppression is improved by optimizing inversion time (TI) based on the linear correlation between subcutaneous fat T1 values and body temperature. This enhances image quality in postmortem magnetic resonance (PMMR) imaging.
Area of Science:
- Radiology
- Medical Imaging
- Forensic Science
Background:
- Postmortem magnetic resonance (PMMR) imaging presents challenges in signal intensity and contrast compared to in-vivo imaging.
- Achieving adequate fat suppression is crucial for accurate interpretation of PMMR scans.
Purpose of the Study:
- To optimize inversion time (TI) for short-tau inversion recovery (STIR) PMMR imaging to achieve sufficient fat suppression.
- To investigate the relationship between subcutaneous fat T1 values and postmortem body temperature.
Main Methods:
- 37 deceased adult patients underwent 1.5 tesla PMMR imaging.
- Subcutaneous fat T1 values were measured and correlated with rectal temperature (RT) using Pearson's correlation coefficient.
- STIR images were acquired using both standard and optimized TI values.
Main Results:
- A strong positive correlation (r = 0.91, P < 0.0001) was found between subcutaneous fat T1 values and RT.
- The regression equation T1 = 2.6*RT + 90 was established for 1.5T.
- Optimized TI significantly improved subcutaneous fat signal suppression.
Conclusions:
- Subcutaneous fat T1 values in PMMR exhibit a linear correlation with body temperature.
- This correlation enables easy optimization of TI for improved fat suppression in PMMR STIR imaging.
