Korean J Radiol.  2015 Dec;16(6):1216-1225. 10.3348/kjr.2015.16.6.1216.

Reduced Field-of-View Diffusion-Weighted Magnetic Resonance Imaging of the Pancreas: Comparison with Conventional Single-Shot Echo-Planar Imaging

• Kim H
• Lee JM
• Yoon JH
• Jang JY
• Kim SW
• Ryu JK
• Kannengiesser S
• Han JK
• Choi BI

• KMID: 2344275
• DOI: http://doi.org/10.3348/kjr.2015.16.6.1216

Abstract

OBJECTIVE
To investigate the image quality (IQ) and apparent diffusion coefficient (ADC) of reduced field-of-view (FOV) di-ffusion-weighted imaging (DWI) of pancreas in comparison with full FOV DWI.
MATERIALS AND METHODS
In this retrospective study, 2 readers independently performed qualitative analysis of full FOV DWI (FOV, 38 × 38 cm; b-value, 0 and 500 s/mm²) and reduced FOV DWI (FOV, 28 × 8.5 cm; b-value, 0 and 400 s/mm²). Both procedures were conducted with a two-dimensional spatially selective radiofrequency excitation pulse, in 102 patients with benign or malignant pancreatic diseases (mean size, 27.5 ± 14.4 mm). The study parameters included 1) anatomic structure visualization, 2) lesion conspicuity, 3) artifacts, 4) IQ score, and 5) subjective clinical utility for confirming or excluding initially considered differential diagnosis on conventional imaging. Another reader performed quantitative ADC measurements of focal pancreatic lesions and parenchyma. Wilcoxon signed-rank test was used to compare qualitative scores and ADCs between DWI sequences. Mann Whitney U-test was used to compare ADCs between the lesions and parenchyma.
RESULTS
On qualitative analysis, reduced FOV DWI showed better anatomic structure visualization (2.76 ± 0.79 at b = 0 s/mm² and 2.81 ± 0.64 at b = 400 s/mm²), lesion conspicuity (3.11 ± 0.99 at b = 0 s/mm² and 3.15 ± 0.79 at b = 400 s/mm²), IQ score (8.51 ± 2.05 at b = 0 s/mm² and 8.79 ± 1.60 at b = 400 s/mm²), and higher clinical utility (3.41 ± 0.64), as compared to full FOV DWI (anatomic structure, 2.18 ± 0.59 at b = 0 s/mm² and 2.56 ± 0.47 at b = 500 s/mm²; lesion conspicuity, 2.55 ± 1.07 at b = 0 s/mm² and 2.89 ± 0.86 at b = 500 s/mm²; IQ score, 7.13 ± 1.83 at b = 0 s/mm² and 8.17 ± 1.31 at b = 500 s/mm²; clinical utility, 3.14 ± 0.70) (p < 0.05). Artifacts were significantly improved on reduced FOV DWI (2.65 ± 0.68) at b = 0 s/mm² (full FOV DWI, 2.41 ± 0.63) (p < 0.001). On quantitative analysis, there were no significant differences between the 2 DWI sequences in ADCs of various pancreatic lesions and parenchyma (p > 0.05). ADCs of adenocarcinomas (1.061 × 10⁻³ mm²/s ± 0.133 at reduced FOV and 1.079 × 10⁻³ mm²/s ± 0.135 at full FOV) and neuroendocrine tumors (0.983 × 10⁻³ mm²/s ± 0.152 at reduced FOV and 1.004 × 10⁻³ mm²/s ± 0.153 at full FOV) were significantly lower than those of parenchyma (1.191 × 10⁻³ mm²/s ± 0.125 at reduced FOV and 1.218 × 10⁻³ mm²/s ± 0.103 at full FOV) (p < 0.05).
CONCLUSION
Reduced FOV DWI of the pancreas provides better overall IQ including better anatomic detail, lesion conspicuity and subjective clinical utility.

Keyword

Reduced field-of-view; Image quality; Apparent diffusion coefficient; Diffusion-weighted imaging; Magnetic resonance imaging; Pancreas

MeSH Terms

Adult
Aged
Artifacts
Diagnosis, Differential
*Diffusion Magnetic Resonance Imaging
*Echo-Planar Imaging
Female
Humans
Male
Middle Aged
Pancreas/*radiography
Pancreatic Diseases/pathology/*radiography
Pancreatic Neoplasms/pathology/radiography
Retrospective Studies