AI-assisted compressed sensing and gadoxetic acid-enhanced MRI for evaluating colorectal liver metastases in complex...

The detection of colorectal liver metastases (CRLMs) in complex hepatic backgrounds due to chemotherapy-associated liver injury (CALI) and prior local CRLM treatment is challenging and requires advanced imaging modalities capable of providing both precise lesion detection and CALI assessments. This study aimed to evaluate the diagnostic performance of 5 Tesla (T) multimodal magnetic resonance imaging (MRI) for detecting CRLMs while accurately assessing the hepatic background.

A total of 35 post-chemotherapy patients with suspected CRLMs and a combined total of 118 MRI-identified lesions were prospectively enrolled. Participants underwent 5T liver multimodal MRI with acquisition of: T1-weighted (T1W) in/out-of-phase imaging and proton density fat fraction (PDFF), susceptibility-weighted imaging with fast technique (uSWIFT), and standard hepatic gadoxetic acid-enhanced MRI (EOB-MRI) with three-dimensional (3D) isotropic T1W fast spoiled gradient-recalled echo (FSPGR) hepatobiliary phase imaging and artificial intelligence (AI)-assisted compressed sensing (ACS-HBP) (acquisition voxel size 1.2 mm³, reconstructed voxel size 0.6 mm³, 300 slices). Image analysis was performed by two readers, blinded and randomized, who assessed CALI and CRLM diagnostic performance. Statistical analyses included inter-rater agreement (Cohen's kappa), diagnostic metrics-sensitivity, positive predictive value (PPV), and area under the receiver operating characteristic (ROC) curve (AUC)-and generalized estimating equations (GEEs) for identifying factors associated with CRLM detection and for comparing diagnostic performance.

The combination of ACS-HBP and diffusion-weighted imaging (DWI) demonstrated excellent diagnostic performance in detecting CRLMs, yielding the highest sensitivity (97.2%) and PPV (94.6-95.5%), whereas for small lesions (≤10 mm), the combination yielded a sensitivity of 95.7%, outperforming DWI alone (66.0%). Neither CALI nor a prior history of local CRLM treatment had a significant impact on diagnostic performance (all P>0.05). On ACS-HBP imaging, 86.1% (93/108) of all lesions and 71.7% (33/46) of lesions ≤10 mm presented with a target sign (central hyperintensity with a hypointense rim), or reverse target sign (central hypointensity with a hyperintense rim).

The combination of ACS and 5T EOB-MRI demonstrates excellent diagnostic performance for CRLMs, including for ≤10 mm lesions, with high sensitivity and PPV across diverse hepatic backgrounds. On HBP imaging, CRLMs characteristically display target and reverse-target signs, especially in lesions ≤10 mm, facilitating differentiation from hepatic cysts.