Optimising diffusion-weighted MR imaging for demonstrating pancreatic cancer: a comparison of respiratory-triggered, free-breathing and breath-hold techniques

Objectives

To compare respiratory-triggered, free-breathing, and breath-hold DWI techniques regarding (1) image quality, and (2) signal intensity (SI) and ADC measurements in pancreatic ductal adenocarcinoma (PDAC).

Methods

Fifteen patients with histopathologically proven PDAC underwent DWI prospectively at 1.5?T (b?=?0, 50, 300, 600 and 1,000?s/mm²) with the three techniques. Two radiologists, independently and blindly, assigned total image quality scores [sum of rating diffusion images (lesion detection, anatomy, presence of artefacts) and ADC maps (lesion characterisation, overall image quality)] per technique and ranked them. The lesion SI, signal-to-noise ratio, mean ADC and coefficient of variation (CV) were compared.

Results

Total image quality scores for respiratory-triggered, free-breathing and breath-hold techniques were 17.9, 16.5 and 17.1 respectively (respiratory-triggered was significantly higher than free-breathing but not breath-hold). The respiratory-triggered technique had a significantly higher ranking. Lesion SI on all b-values and signal-to-noise ratio on b300 and b600 were significantly higher for the respiratory-triggered technique. For respiratory-triggered, free-breathing and breath-hold techniques the mean ADCs were 1.201, 1.132 and 1.253?×?10^-3?mm²/s, and mean CVs were 8.9, 10.8 and 14.1?% respectively (respiratory-triggered and free-breathing techniques had a significantly lower mean CV than the breath-hold technique).

Conclusion

In both analyses, respiratory-triggered DWI showed superiority and seems the optimal DWI technique for demonstrating PDAC.

Key Points

? Diffusion-weighted magnetic resonance imaging is increasingly used to detect pancreatic cancer ? Images are acquired using various breathing techniques and multiple b-values ? Breathing techniques used: respiratory-triggering, free-breathing and breath-hold ? Respiratory-triggering seems the optimal breathing technique for demonstrating pancreatic cancer