Primary lung cancers <1 cm found with MR screening appeared larger with half-Fourier sequences than with three-dimensional acquisition techniques.

PURPOSE

The purpose was to objectively evaluate image quality characteristics of half-Fourier single-shot turbo spin-echo (HASTE) and three-dimensional volumetric interpolated breath-hold examination (3D-VIBE) for small (<1 cm) lung cancers found by magnetic resonance imaging (MRI) screening.

METHODS

From 2000 to 2009, 19,000 normal subjects were screened by MRI, and 15 cases were found to have lung cancers <1 cm. Those nodules were analyzed by image quality indices such as the signal to noise ratio, signal difference to noise ratio, percent contrast, percent contrast to noise ratio, and signal ratio of tumor to normal lung parenchyma. The area of the tumors measured by the two MR sequences and the computed tomography (CT) was compared.

RESULTS

The lung cancers showed significantly higher percent contrast, percent contrast to noise, and the signal ratio of tumor to normal lung parenchyma by 3D-VIBE as compared to HASTE. Tumor area estimated by HASTE was significantly larger than that estimated by VIBE. There was no significant difference in the signal to noise ratio and signal difference to noise ratio between the two MR sequences.

CONCLUSIONS

The 3D acquisition technique offers high contrast and contrast to noise ratios, while HASTE is associated with closer approximation of area estimation as compared to CT. Both sequences have similar signal to noise ratios and signal difference to noise ratios. The HASTE sequence is considered to be an essential part of imaging protocol in MR screening of lung especially for small nodules.