[Improved Conspicuity of Subtle Contrast Enhancement Using 3D Phase-sensitive Inversion Recovery]

Evaluation of glioblastoma (GBM) with weak contrast enhancement and small metastatic brain tumors can be challenging. This study aimed to optimize imaging parameters for three-dimensional phase-sensitive inversion recovery (3D-PSIR) and compare its performance with a conventional method using a phantom experiment.

MRI was performed using a 1.5-T Achieva system (Philips, Best, the Netherlands). Phantoms were prepared to simulate white matter, gray matter, and low-level gadolinium contrast enhancement. PSIR was combined with a 3D T1 turbo field echo sequence. The TFE factor, shot interval (SI), and TI delay were varied, and the contrast-to-noise ratio (CNR) was evaluated.

The TFE factor of 10 yielded high CNR values. The CNR tended to increase with increasing shot interval, although the rate of increase became smaller at shot intervals of 2000 ms or longer. High CNR values were also obtained at TI delay times of 600-1000 ms. Compared with conventional 3D fast field echo (3D-FFE), 3D-PSIR achieved more than twice the CNR.

Under appropriate imaging conditions, 3D-PSIR demonstrated higher CNR than conventional 3D-FFE in a phantom simulating subtle contrast enhancement. These findings may provide fundamental evidence for the potential clinical application of 3D-PSIR in improving the visualization of brain tumors with subtle contrast enhancement.