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

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).

Potential clinical feasibility of synthetic MRI in bladder tumors: a comparative study with conventional MRI

“…Magnetic resonance imaging (MRI) has been widely used in the preoperative staging evaluation for BC in recent years, especially since the introduction of the bladder Vesical Imaging-Reporting and Data System (VI-RADS) in 2018, in which a standardized image acquisition and reporting system were recommended ( 2 ). Conventionally, multiparametric MRI, including T1-weighted imaging (T1W), T2-weighted imaging (T2W), diffusion-weighted imaging (DWI), and dynamic contrast-enhanced images, has been applied in preoperative evaluations for staging and postoperative follow-up ( 3 , 4 ). Contrastingly, conventional MRI, especially T1W and T2W images, only supplies qualitative information based on signal intensity, not objective and quantitative data for diagnosis.…”