Qian Li

Background: Stack-of-spirals ultrashort echo time (spiral-UTE) has been reported to be feasible for lung imaging; however, the performance of free-breathing contrast-enhanced and unenhanced spiral-UTE (UTEe and UTEu) is still unknown. Therefore, this study aimed to evaluate their performance of lung imaging in patients with malignant tumors. Methods: A total of 76 patients with malignancies suspected of pulmonary metastatic nodules were enrolled in free-breathing UTEe, UTEu and routine contrast-enhanced T1-weighted imaging [volumetric interpolated breath-hold examination (VIBE)] for lung follow-up. Two radiologists independently assessed the image quality, and qualitative analysis was scored via a 5-point scale (4, excellent; 0, unreadable) with respect to the visibility of fissures, airways and vessels; signal homogeneity; motion artifacts; lesion conspicuity; and overall image quality. Quantitative analysis included measurements of the apparent contrast-to-noise ratio (CNR) and apparent signal-to-noise ratio (SNR). Pulmonary nodules detected via magnetic resonance (MR) images were compared with those by computed tomography (CT) as the reference standard. Results: Both UTEu and UTEe outperformed VIBE in all the qualitative metrics (P0.05) in those metrics. UTEe exhibited the best performance in depicting pulmonary vessels, achieving the highest apparent SNR and apparent CNR values. Among the 130 pulmonary nodules identified via CT, spiral-UTE had a sensitivity of 76.9% and a positive predictive value (PPV) of 99.0%, significantly outperforming VIBE (sensitivity of 47.7% and PPV of 95.4%). The detection rates for spiral-UTE were 90.0% for nodules larger than 5 mm, 98.5% for nodules larger than 7 mm and 100.0% for nodules larger than 10 mm. Conclusions: Spiral-UTE demonstrated superior image quality and greater sensitivity for pulmonary nodule detection than breath-hold VIBE did. Both unenhanced and enhanced spiral-UTE showed comparable performance in nodule detection, highlighting its potential as a reliable imaging modality for patients with malignant tumors during follow-up imaging.

To investigate morphofunctional chest MRI for the detection and management of incidental pulmonary nodules in participants with chronic obstructive pulmonary disease (COPD). In this prospective study, 567 participants (mean age, 66 years ± 9 [SD]; 340 men) underwent same-day contrast-enhanced MRI and nonenhanced low-dose CT (LDCT) in a nationwide multicenter trial (clinicaltrials.gov: NCT01245933). Nodule dimensions, morphologic features, and Lung Imaging Reporting and Data System (Lung-RADS) category were assessed at MRI by two blinded radiologists, and consensual LDCT results served as the reference standard. Comparisons were performed using the Student t test, and agreements were assessed using the Cohen weighted κ. A total of 525 nodules larger than 3 mm in diameter were detected at LDCT in 178 participants, with a mean diameter of 7.2 mm ± 6.1 (range, 3.1–63.1 mm). Nodules were not detected in the remaining 389 participants. Sensitivity and positive predictive values with MRI for readers 1 and 2, respectively, were 63.0% and 84.8% and 60.2% and 83.9% for solid nodules (n = 495), 17.6% and 75.0% and 17.6% and 60.0% for part-solid nodules (n = 17), and 7.7% and 100% and 7.7% and 50.0% for ground-glass nodules (n = 13). For nodules 6 mm or greater in diameter, sensitivity and positive predictive values were 73.3% and 92.2% for reader 1 and 71.4% and 93.2% for reader 2, respectively. Readers underestimated the long-axis diameter at MRI by 0.5 mm ± 1.7 (reader 1) and 0.5 mm ± 1.5 (reader 2) compared with LDCT (P < .001). For Lung-RADS categorization per nodule using MRI, there was substantial to perfect interreader agreement (κ = 0.75–1.00) and intermethod agreement compared with LDCT (κ = 0.70–1.00 and 0.69–1.00). In a multicenter setting, morphofunctional MRI showed moderate sensitivity for detection of incidental pulmonary nodules in participants with COPD but high agreement with LDCT for Lung-RADS classification of nodules. Clinical trial registration no. NCT01245933 and NCT02629432 Keywords: MRI, CT, Thorax, Lung, Chronic Obstructive Pulmonary Disease, Screening © RSNA, 2023 Supplemental material is available for this article.

(1) Background: To assess the efficacy of the quantitative parameters of intravoxel incoherent motion (IVIM) diffusion-weighted imaging for hepatocellular carcinoma (HCC) diagnosis after transarterial chemoembolization (TACE). (2) Methods: Fifty HCC patients after TACE were included and underwent MRI. All of the patients were scanned with the IVIM-DWI sequence and underwent TACE retreatment within 1 week. Referring to digital subtraction angiography (DSA) and MR enhanced images, two readers measured the f, D, and D* values of the tumor active area (TAA), tumor necrotic area (TNA), and adjacent normal hepatic parenchyma (ANHP). Then, the distinctions of the TAA, TNA, and ANHP were compared and we analyzed the differential diagnosis of the parameters in three tissues. (3) Results: For values of f and D, there were significant differences between any of the TAA, TNA, and ANHP (p < 0.05). The values of f and D were the best indicators for identifying the TAA and TNA, with AUC values of 0.959 and 0.955, respectively. The values of f and D performed well for distinguishing TAA from ANHP, with AUC values of 0.835 and 0.753, respectively. (4) Conclusions: Quantitative IVIM-DWI was effective for evaluating tumor viability in HCC patients treated with TACE and may be helpful for non-invasive monitoring of the tumor viability.