Fast T2-weighted imaging by PSIF at 0.2 T for interventional MRI

Yiu Cho Chung, Elmar M. Merkle, Jonathan S. Lewin, Jason R. Shonk, Jeffrey L. Duerk

Research output: Contribution to journalArticlepeer-review


Rapid T2 weighted (T2W) images would facilitate physicians being able to distinguish normal tissues, vessels, tumors, and thermal lesions from therapeutic devices throughout interventional MRI procedures commonly performed in open low-field scanners (e.g., 0.2 T). Conventional diagnostic MRI techniques have not been successful at low-field strength for fast T2W imaging during the guidance phase of interventional MRI (I-MRI) procedures. FISP and true-FISP methods yield T1/T2-weighted images and do not always provide sufficient contrast for device guidance or lesion assessment. As such, a variant of PSIF (a gradient reversed form of FISP) which collects the T2-weighted spin echo of the SSFP signal was developed and implemented at 0.2 T for use in I-MRI procedures. The sequence has a balanced readout gradient to reduce motion sensitivity. Asymmetric sampling toward the end of the TR cycle reduces T*/2 decay of the one image in 5-7 s in vivo with adequate SNR and T2 contrast for PSIF sequence variant demarcates many tumors not detectable by either FISP or true-FISP. Results from animal experiments suggested that it has potential to monitor thermal lesions during interstitial thermal ablation procedures.

Original languageEnglish (US)
Pages (from-to)335-344
Number of pages10
JournalMagnetic resonance in medicine
Issue number2
StatePublished - 1999


  • Interventional MRI
  • Low- field imaging
  • Steady-state free precession(SSFP)
  • TW imaging

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging


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