Deep learning enabled near-isotropic CAIPIRINHA VIBE in the nephrogenic phase improves image quality and renal lesion conspicuity

Abstract

Background: Deep learning (DL) accelerated controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA)-volumetric interpolated breath-hold examination (VIBE), provides high spatial resolution T1-weighted imaging of the upper abdomen. We aimed to investigate whether DL-CAIPIRINHA-VIBE can improve image quality, vessel conspicuity, and lesion detectability compared to a standard CAIPIRINHA-VIBE in renal imaging at 3 Tesla.

Methods: In this prospective study, 50 patients with 23 solid and 45 cystic renal lesions underwent MRI with clinical MR sequences, including standard CAIPIRINHA-VIBE and DL-CAIPIRINHA-VIBE sequences in the nephrographic phase at 3 Tesla. Two experienced radiologists independently evaluated both sequences and multiplanar reconstructions (MPR) of the sagittal and coronal planes for image quality with a Likert scale ranging from 1 to 5 (5 =best). Quantitative measurements including the size of the largest lesion and renal lesion contrast ratios were evaluated.

Results: DL-CAIPIRINHA-VIBE compared to standard CAIPIRINHA-VIBE showed significantly improved overall image quality, higher scores for renal border delineation, renal sinuses, vessels, adrenal glands, reduced motion artifacts and reduced perceived noise in nephrographic phase images (all p < 0.001). DL-CAIPIRINHA-VIBE with MPR showed superior lesion conspicuity and diagnostic confidence compared to standard CAIPIRINHA-VIBE. However, DL-CAIPIRINHA-VIBE presented a more synthetic appearance and more aliasing artifacts (p < 0.023). The mean size and signal intensity of renal lesions for DL-CAIPIRINHA-VIBE showed no significant differences compared to standard CAIPIRINHA-VIBE (p > 0.9).

Conclusions: DL-CAIPIRINHA-VIBE is well suited for kidney imaging in the nephrographic phase, provides good image quality, improved delineation of anatomic structures and renal lesions.

Keywords: Deep learning; Image quality; Magnetic resonance imaging; Multi-planar reconstructions; Renal lesions.

Fig. 1

Nephrographic phase MRI of a 68-year-old male patient with malignant epithelioid angiomyolipoma. The standard CAIPIRINAHA-VIBE axial (a), with MPR coronal (b) sagittal plane (c) in the top row show worse image quality, lesion delineation and vessel conspicuity compared to DL-CAIPIRINAHA-VIBE with MPR imaging (the bottom row; d: axial, e: MPR coronal, f: MPR sagittal).

Fig. 2

Nephrographic enhanced phase MRI of a 65-year-old female patient with cystic renal lesions (Bosniak I-IIF). The standard CAIPIRINAHA-VIBE axial (a), with MPR coronal (b) sagittal plane (c) in the top row show worse image quality, lesion delineation and septal conspicuity compared to DL-CAIPIRINAHA-VIBE with MPR imaging (the bottom row; d: axial, e: MPR coronal, f: MPR sagittal).

Fig. 3

Both standard CAIPIRINAHA-VIBE (a) and DL-CAIPIRINAHA-VIBE (d) showed excellent (Likert score: 5) image quality and conspicuity of the adrenal gland (with an adenoma) on nephrographic phase imaging. In addition, standard CAIPIRINAHA-VIBE MPR (coronal: b; sagittal: c) showed worse adrenal gland conspicuity compared to and DL-CAIPIRINAHA-VIBE MPR (e: MPR coronal, f: MPR sagittal).

Fig. 4

CAIPIRINAHA-VIBE demonstrated showed more pronounced respiratory motion artifacts (a) compared to DL-CAIPIRINAHA-VIBE (b). In the other hand, aliasing artifacts were observed more frequently in the DL-CAIPIRINHA-VIBE (d vs. c). These artifacts were typically mild and did not affect kidney assessment (arrow).

Fig. 5

Bland-Altman plot of maximum measured diameters in DL-CAIPIRINAHA-VIBE compared with CAIPIRINAHA-VIBE by two readers.