Utility of under-sampled scans with iterative reconstruction and high-frequency preserving transform for high spatial resolution magnetic resonance cholangiopancreatography

Shota Kondo; Yuko Nakamura; Toru Higaki; Takashi Nishihara; Masahiro Takizawa; Toru Shirai; Motoshi Fujimori; Yoshitaka Bito; Keigo Narita; Dara Fonseca; Shogo Maeda; Ikuo Kawashita; Yukiko Honda; Kazuo Awai

doi:10.1007/s11604-024-01688-z

Utility of under-sampled scans with iterative reconstruction and high-frequency preserving transform for high spatial resolution magnetic resonance cholangiopancreatography

Jpn J Radiol. 2024 Nov 5. doi: 10.1007/s11604-024-01688-z. Online ahead of print.

Authors

Shota Kondo¹, Yuko Nakamura², Toru Higaki^{1

3}, Takashi Nishihara⁴, Masahiro Takizawa⁴, Toru Shirai⁴, Motoshi Fujimori⁴, Yoshitaka Bito^{4

5}, Keigo Narita¹, Dara Fonseca¹, Shogo Maeda¹, Ikuo Kawashita¹, Yukiko Honda¹, Kazuo Awai¹

Affiliations

¹ Diagnostic Radiology, Hiroshima University, 1-2-3 Kasumi, Minami-Ku, Hiroshima City, Hiroshima, 734-8551, Japan.
² Diagnostic Radiology, Hiroshima University, 1-2-3 Kasumi, Minami-Ku, Hiroshima City, Hiroshima, 734-8551, Japan. yukon@hiroshima-u.ac.jp.
³ Graduate School of Advanced Science and Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi-Hiroshima City, Hiroshima, 739-8527, Japan.
⁴ FUJIFILM Corporation, 2-1, Shintoyofuta, Kashiwa City, Chiba, 277-0804, Japan.
⁵ Department of Diagnostic Imaging, Hokkaido University Graduate School of Medicine, Kita 15 jo, Nishi 7 chome, Kita ku, Sapporo City 060-8638, Japan.

PMID: 39496864
DOI: 10.1007/s11604-024-01688-z

Abstract

Purpose: Under-sampled scans with iterative reconstruction and high-frequency preserving transform (Us-IRHF) can increase the acquisition speed without degrading the image quality by recovering image information from under-sampled data. We investigate the clinical applicability of high spatial resolution magnetic resonance cholangiopancreatography (MRCP) images without extending the scanning time using Us-IRHF.

Methods: A slit phantom was scanned with conventional- (without Us-IRHF), Us-IR- (without HF), and Us-IRHF scanning. The matrix size was 320 × 320 for Us-IR- and Us-IRHF- and 288 × 208 for conventional scanning. Modulation transfer function (MTF) focused on the 1.0 lp/cm gauge for each scanning was calculated. For clinical study we acquired respiratory-triggered 3D MRCP scans with and without Us-IRHF (U⁺-, U^-MRCP) in 41 patients. The matrix size was 320 × 320 for U⁺- and 288 × 208 for U^-MRCP. The acquisition time and the relative duct-to-periductal contrast ratios (RCs) for the right- and left intrahepatic bile-, the common bile-, and the main pancreatic duct were recorded. Visualization of each duct and overall image quality was scored on 5-point confidence scales. For visualization of each duct the score ranged from 1 (not visible) to 5 (visible with excellent details), for the image quality, it ranged from 1 (undiagnostic) to 5 (excellent). Superiority for the qualitative visualization score and non-inferiority for the RC values with prespecified margins were assessed.

Results: Phantom study showed that compared to the conventional- and Us-IR (without HF) images, the MTF for the Us-IRHF image revealed the highest response. For clinical study, the mean acquisition time was 161 s for U⁺- and 165 s for U^-MRCP. For all ducts, the RC value of U⁺MRCP was non-inferior to U^-MRCP and the qualitative visualization score assigned to U⁺MRCP was superior to U^-MRCP.

Conclusion: Us-IRHF improved the image quality of high spatial resolution MRCP without extending the scanning time.

Keywords: High-frequency preserving transform; Iterative reconstruction; Magnetic resonance cholangiopancreatography; Spatial resolution; Under-sampled scans.

Grants and funding

0G20KA7113/Fujifilm Corporation