Image quality evaluation of diffusion-weighted imaging in bladder cancer: a comparison between integrated slice-specific dynamic shimming and single-shot echo-planar imaging

Yiqian Wang; Shaobin Chen; Wei Zhang; Weixiong Xiao; Jiawei Su; Ruochen Zhang; Yongbao Wei; Min Luo

doi:10.21037/qims-22-851

Image quality evaluation of diffusion-weighted imaging in bladder cancer: a comparison between integrated slice-specific dynamic shimming and single-shot echo-planar imaging

Quant Imaging Med Surg. 2023 Apr 1;13(4):2526-2537. doi: 10.21037/qims-22-851. Epub 2023 Feb 17.

Authors

Yiqian Wang^#^{1

2}, Shaobin Chen^#^{1

2}, Wei Zhang^{1

2}, Weixiong Xiao^{1

2}, Jiawei Su^{1

2}, Ruochen Zhang^{1

3}, Yongbao Wei^{1

3}, Min Luo^{1

2}

Affiliations

¹ Shengli Clinical Medical College of Fujian Medical University, Fuzhou, China.
² Department of Radiology, Fujian Provincial Hospital, Fuzhou, China.
³ Department of Urology, Fujian Provincial Hospital, Fuzhou, China.

^# Contributed equally.

Abstract

Background: Diffusion-weighted imaging (DWI) image quality will affect how well radiologists detect lesions and judge muscular invasion. This study qualitatively and quantitatively compared the image quality of DWI with integrated slice-specific dynamic shimming (iShim) and single-shot echo-planar imaging (SS-EPI) in the diagnosis of bladder cancer (BC) using 3.0 T magnetic resonance imaging (MRI). We also investigated the application value of iShim DWI in BC.

Methods: This retrospective study enrolled 97 patients with BC who underwent a preoperative MRI examination, including iShim and SS-EPI DWI. Two radiologists, blinded to the type of DWI, independently rated DWIs on a 5-point Likert scale regarding image quality features (anatomical details, distortion, lesion conspicuity, artifacts, and overall image quality) and evaluated tumor muscular invasion. Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), apparent diffusion coefficient (ADC) values, and tumor numbers were manually recorded by another 2 radiologists. Pathologists recorded tumor numbers and sizes in a standard manner.

Results: The inter- and intraobserver consistency of image quality features scoring was good to excellent (κ >0.75; P<0.001). The scores of iShim DWI were higher than those of SS-EPI DWI in terms of distortion, artifacts, and overall image quality (P<0.001). The SNR and CNR of iShim DWI were higher than those of SS-EPI DWI (P<0.001), but there was no significant difference in ADC values between the 2 sequences (P>0.05). Based on pathological findings, the sensitivity of iShim and SS-EPI DWI in diagnosing tumor that diameter less than 1 cm was 100% (79/79) and 93.7% (74/79), respectively. The specificity and accuracy (95.2% and 90.2%, respectively) of iShim DWI in diagnosing tumor muscular invasion were significantly higher than those of SS-EPI DWI (76.2% and 80.4%, respectively). The area under the receiver operating characteristic curve of iShim DWI was significantly higher than that of SS-EPI DWI in diagnosing tumor muscular invasion (P=0.017).

Conclusions: Compared with SS-EPI DWI, iShim DWI provided higher image quality. iShim DWI effectively detected BC and better identified muscular invasion. This finding can guide the clinical selection of appropriate treatments for patients with BC.

Keywords: Bladder cancer (BC); diffusion-weighted imaging (DWI); image quality; integrated slice-specific dynamic shimming (iShim); magnetic resonance imaging (MRI).