Magnetic resonance cholangiopancreatography with compressed sensing at 1.5 T: clinical application for the evaluation of branch duct IPMN of the pancreas

Abstract

Objectives: To evaluate magnetic resonance cholangiopancreatography (MRCP) with compressed sensing (CS) for the assessment of branch duct intraductal papillary mucinous neoplasm (BD-IPMN) of the pancreas. For this purpose, conventional navigator-triggered (NT) sampling perfection with application-optimized contrast using different flip angle evolutions (SPACE) MRCP was compared with various CS-SPACE-MRCP sequences in a clinical setting.

Methods: A total of 41 patients (14 male, 27 female, mean age 68 years) underwent 1.5-T MRCP for the evaluation of BD-IPMN. The MRCP protocol consisted of the following sequences: conventional NT-SPACE-MRCP, CS-SPACE-MRCP with long (BHL, 17 s) and short single breath-hold (BHS, 8 s), and NT-CS-SPACE-MRCP. Two board-certified radiologists evaluated image quality, duct sharpness, duct visualization, lesion conspicuity, confidence, and communication with the main pancreatic duct in consensus using a 5-point scale (1-5), with higher scores indicating better quality/delineation/confidence. Maximum intensity projection reconstructions and originally acquired data were used for evaluation. Wilcoxon signed-rank test was used to compare the intra-individual difference between sequences.

Results: BHS-CS-SPACE-MRCP had the highest scores for image quality (3.85 ± 0.79), duct sharpness (3.81 ± 1.05), and duct visualization (3.81 ± 1.01). There was a significant difference compared with NT-CS-SPACE-MRCP (p < 0.05) but no significant difference to the standard NT-SPACE-MRCP (p > 0.05). Concerning diagnostic quality, BHS-CS-SPACE-MRCP had the highest scores in lesion conspicuity (3.95 ± 0.92), confidence (4.12 ± 1.08), and communication (3.8 ± 1.06), significantly higher compared with NT-SPACE-MRCP, BHL-SPACE-MRCP, and NT-CS-SPACE-MRCP (p = <0.05).

Conclusions: MRCP with CS 3D SPACE for the evaluation of BD-IPMN at 1.5 T provides the best results using a short breath-hold sequence. This approach is feasible and an excellent alternative to standard NT 3D MRCP sequences.

Key points: • 1.5-T MRCP with compressed sensing for the evaluation of branch duct IPMN is a feasible method. • Short breath-hold sequences provide the best results for this purpose.

Keywords: Magnetic resonance imaging; Pancreas; Pancreatic intraductal neoplasms.

Fig. 1

Overview of patient inclusion criteria, visualized as a flow chart

Fig. 2

A 71-year-old female patient with multiple BD-IPMN. a Conventional NT-SPACE-MRCP providing the worst quality with the longest acquisition time (04:13 min). CS-SPACE-MRCP with breath-hold shows the best image quality (image b is BHL and image c is BHS). d NT-CS-SPACE-MRCP with 01:32-min acquisition time also provides only average image quality. Scores were as follows [image quality/duct sharpness/duct visualization/lesion conspicuity/confidence/communication]: (a) NT-SPACE [2/2/2/2/3/2]; (b) BHL-CS-SPACE [4/4/4/4/5/4]; (c) BHS-CS-SPACE [4/5/4/4/5/5]; (d) NT-CS-SPACE [3/3/2/2/2/3] (MIPs are displayed; windowing was adjusted for optimal visualization)

Fig. 3

A 56-year-old male patient with BD-IPMN. Difference between the sequences for source images (left) and MIPs (right) are shown. a Conventional NT-SPACE-MRCP; the communication between the cystic lesion and the pancreatic duct cannot be visualized (circles). It can only barely be depicted with BHL-CS-SPACE-MRCP (circles, b). c BHS-CS-SPACE-MRCP was able to illustrate the communication in the source images (arrow) which made the diagnosis of a BD-IPMN possible. d NT-CS-SPACE-MRCP showed acceptable image quality, but the communication was also hard to depict due to blurring. Scores were as follows [image quality/duct sharpness/duct visualization/lesion conspicuity/confidence/communication]: (a) NT-SPACE [4/3/3/2/2/1]; (b) BHL-CS-SPACE [3/1/2/2/3/2]; (c) BHS-CS-SPACE [4/4/4/4/4/4]; (d) NT-CS-SPACE [3/3/2/3/3/3]