Investigative Radiology最新文献

Background: Photon-counting CT (PCD-CT) provides spectral imaging in every clinical scan through virtual monoenergetic image (VMI) reconstruction. However, because conventional iodine-based contrast medium has a low k-edge, image contrast in the VMIs decreases at high energies. Contrast media with higher k-edges may improve contrast in high-energy VMIs. Therefore, this study investigates BAY3685750, a novel iodine-gadolinium hybrid contrast medium.

Materials and methods: In vitro experiments compared BAY3685750 with conventional iodine-based and gadolinium-based contrast agents in an anthropomorphic abdominal phantom. Relaxivity (r1) of BAY3685750 was measured at 1.41 T in water and human plasma to assess its potential for both MRI and CT applications. Next, 3 Göttingen minipigs underwent multiphasic contrast-enhanced upper abdominal CT on a first-generation PCD-CT. In 2 animals, BAY3685750 was administered for the first scan, followed by a 60-minute washout and a second multiphasic scan with a standard iodine-based contrast medium. In the third animal, the order was reversed. VMIs were reconstructed for all scans, enabling intraindividual comparison of the 2 contrast agents.

Results: In the phantom study, BAY3685750 produced higher attenuation than the iodine-based contrast medium and lower attenuation than the gadolinium-based medium. Relative to the iodine medium, BAY3685750 attenuation increased continuously with energy, reaching ~20% (70 keV), 36% (100 keV), and 78% (140 keV) higher values. In vivo, all measured structures (aorta, inferior vena cava, portal vein, liver) had higher attenuation with BAY3685750 than with iodine at all phases and VMIs. The r1 relaxivity of BAY3685750 in human plasma (1.41 T) was 8.95 L mmol -1 s -1 compared with 5.93 L mmol -1 s -1 for gadobutrol.

Conclusion: The hybrid iodine-gadolinium contrast medium BAY3685750 provides higher attenuation than conventional iodine-based CT contrast, suggesting improved image quality in high-energy VMIs.

Objectives: MR neurography (MRN) is a modern technique for visualizing peripheral nerves and quantifying microstructural pathology, yet its use in pediatric populations remains largely unexplored. This study evaluates the applicability and diagnostic performance of MRN in children and adolescents with genetically confirmed long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD) and mitochondrial trifunctional protein deficiency (MTPD), in which peripheral neuropathy is a known long-term complication.

Materials and methods: In a prospective cross-sectional study, 15 patients (LCHADD n = 6; MTPD n = 9) and 14 age-matched controls underwent high-resolution mid-thigh MRN of the sciatic nerve to assess (1) T2-based lesion burden for tibial (SNTib) and peroneal (SNPer) fascicles, (2) functional nerve integrity of the tibial fascicles using diffusion tensor metrics, including fractional anisotropy (FA) and radial diffusivity (RD), and (3) tibial fascicle-based T2 relaxometry parameters. In addition, clinical and electrophysiological data were obtained. Age-adjusted linear regression, ROC analyses, and linear discriminant analyses (LDA) quantified group effects and classification performance.

Results: Overall, patients showed higher T2 lesion burden compared with controls (SNTib: +2.75%, P = 0.001; SNPer: +1.94%, P = 0.001), reduced tibial fascicle FA (Δ: -0.098, P = 0.001), and increased tibial fascicle RD (Δ: +147.4×10-6 mm2/s, P = 0.011). Subgroup comparisons between LCHADD and MTPD revealed no significant differences. Of the 15 patients, 7 exhibited signs of clinical neuropathy. Neuropathic individuals showed pronounced abnormalities (SNTib: +4.22%, P < 0.001; SNPer: +2.29%, P = 0.002; ΔFA: -0.138, P < 0.001), while even those without clinical neuropathy exhibited elevated SNPer lesion burden (+1.64%; P = 0.018) and reduced tibial fascicle FA (Δ: -0.062, P = 0.03), compared with controls, indicating subclinical involvement. SNTib lesion burden showed excellent discrimination (AUC: 95.2%), and FA performed well (AUC: 81.2%). Multiparametric LDA achieved 93% apparent in-sample accuracy for patients versus controls, 86% for LCHADD versus MTPD, and 90% for classifying neuropathic, non-neuropathic, and control groups.

Conclusions: MRN can be readily applied in children and adolescents and sensitively detects both clinically manifest and subclinical peripheral nerve involvement in long-chain fatty acid oxidation disorders. Extending this capability, exploratory LDA suggests that combining multiple MRN metrics may provide complementary diagnostic and phenotypic information beyond individual parameters.

Objectives: The diagnostic value of conventional T1 mapping for noninvasive assessment of liver fibrosis is limited in the presence of hepatic steatosis. To evaluate the diagnostic value of water T1 (wT1) with continuous inversion-recovery Look-Locker (CIR-LL) method, integrating spiral readout, Dixon, and dictionary-based processing, for the fat-corrected assessment of hepatic fibrosis in patients with chronic liver disease (CLD).

Materials and methods: In this prospective study, consecutive participants with CLD underwent liver magnetic resonance imaging (MRI), which included assessment of MR-elastography (MRE)-derived liver stiffness, proton density fat fraction (PDFF), T1 relaxation times using modified Look-Locker inversion recovery (T1-MOLLI) and extracellular volume fraction (ECV), and wT1 relaxation times. MRE served as the reference standard to evaluate the diagnostic performance of MRI-based mapping parameters. Significant fibrosis (≥F2) was defined as MRE-derived liver stiffness >3.66 kPa in patients with PDFF≤5%, or >3.14 kPa in patients with PDFF>5%. Statistical analysis included Student t test, receiver operating characteristic (ROC) analysis, and Spearman correlation coefficient.

Results: A total of 81 CLD patients (mean age, 50±14 y; 32 female; 40 patients with PDFF>5%) were included. All measured mapping values were significantly higher in patients with significant fibrosis compared with those without (eg, wT1: 628±82 vs. 546±41 ms, P <0.001). wT1 showed a strong correlation with MRE-derived liver stiffness, outperforming T1-MOLLI and ECV mapping [whole cohort: r =0.67 (wT1) vs. 0.53 (T1-MOLLI) vs. 0.48 (ECV); cohort with PDFF>5%: r =0.69 (wT1) vs. 0.44 (T1) vs. 0.49 (ECV); P <0.05 in each case, respectively]. wT1 had a superior diagnostic performance for the detection of significant fibrosis [whole cohort, area under the curve (AUC): 0.82 (wT1); 0.77 (T1-MOLLI); 0.73 (ECV), P <0.001 in each case; cohort with PDFF>5%, AUC: 0.84, P =0.002 (wT1), 0.70, P =0.04 (T1-MOLLI), 0.70, P =0.04 (ECV)].

Conclusion: Compared with T1-MOLLI and ECV mapping, the proposed fat-corrected CIR-LL wT1 method proved to be a more robust marker of hepatic fibrosis in CLD, also in the presence of hepatic steatosis.

Purpose: To evaluate PANCANAI, a previously developed AI model for pancreatic cancer (PC) detection, on a longitudinal cohort of patients. In particular, aiming for PC detection on scans acquired before histopathologic diagnosis was assessed.

Materials and methods: The model has been previously trained to predict PC suspicion on 2134 portal venous CTs. In this study, the algorithm was evaluated on a retrospective cohort of Danish patients with biopsy-confirmed PC and with CT scans acquired between 2006 and 2016. The sensitivity was measured, and bootstrapping was performed to provide median and 95% CI.

Results: The study included 1083 PC patients (mean age: 69 y ± 11, 575 men). CT scans were divided into 2 groups: (1) concurrent diagnosis (CD): 1022 CT scans acquired within 2 months around histopathologic diagnosis, and (2) prediagnosis (PD): 198 CT scans acquired before histopathologic diagnosis (median 7 months before diagnosis). The sensitivity was 91.8% (938 of 1022; 95% CI: 89.9-93.5) and 68.7% (137 of 198; 95% CI: 62.1-75.3) on the CD and PD groups, respectively. Sensitivity on CT scans acquired 1 year or more before diagnosis was 53.9% (36 of 67; 95% CI: 41.8-65.7). Sensitivity on CT scans acquired at stage I was 82.9% (29 of 35; 95% CI: 68.6-94.3).

Conclusion: PANCANAI showed high sensitivity for automatic PC detection on a large retrospective cohort of biopsy-confirmed patients. PC suspicion was detected in more than half of the CT scans that were acquired at least a year before histopathologic diagnosis.

Objectives: Quantitative proton density fat fraction (PDFF) and R2* estimation at lower field strengths, such as 0.55 T, is challenging due to lower signal-to-noise ratio, reduced fat water chemical shift, and increased T2* relaxation times. In this study, we propose a 3D hybrid technique for abdominal imaging at 0.55 T that enables the simultaneous acquisition of T2-weighted and T1-weighted images and quantification of fat fraction and R2* parameters.

Materials and methods: Numerical simulations were performed to optimize a prototype radial hybrid turbo spin echo gradient echo (TSE-GRE) acquisition scheme for improved PDFF and R2* estimation accuracy. Phantom imaging experiments with and without motion were performed to evaluate the sensitivity of the estimation to external motion. Eleven volunteers were imaged on a prototype 0.55 T system. Data were acquired using the proposed technique under free-breathing conditions, and motion-compensated reconstruction was performed using the respiratory signal from a pilot-tone device. Image contrast and estimation performance were compared with conventional acquisition schemes in vitro and in vivo.

Results: Numerical simulations indicated R2* estimation accuracy was more sensitive to the choice of echo time compared with PDFF. Performing motion compensation reduced the mean error in R2* from 24 to 5 s -1 while the mean error in PDFF only reduced from 2.7% to 1.6%. The proposed technique generated T2-weighted images with comparable relative liver-spleen contrast as conventional imaging and there were no significant differences ( P >0.05) in the PDFF and R2* values estimated from the hybrid technique compared with conventional multi-echo GRE. Further, the free-breathing acquisition allowed improved slice coverage while overcoming breath-hold limitations of conventional acquisition schemes.

Conclusions: The use of a hybrid TSE-GRE acquisition technique can allow simultaneous morphological and quantitative PDFF and R2* estimation at 0.55 T under free-breathing conditions.

Background and aims: There is scarcity of data on the prevalence of abnormal pancreaticobiliary junction (APBJ) in children. This study aimed to determine the frequency and clinical significance of APBJ including pancreas divisum (PD) and common channel (CC) using magnetic resonance cholangiopancreatography (MRCP).

Materials and methods: Single-center, retrospective study of MRCPs in children aged 0 to 18 years from 2012 to 2022. Two independent readers assessed PBJ visibility, abnormalities (PD, CC, other), and CC length. Findings were correlated with presenting diagnoses of choledochal cyst, biliary lithiasis, and pancreatitis.

Results: A total of 631 MRCPs were included (46.8% females; mean age: 12 ± 5 y). The PBJ was visible in 85.7% of cases. APBJ was observed in 114/631 (18.1%) children, with PD in 47 (7.4%) cases and CC in 61 (9.7%) cases, with an average length of 9 mm (range, 3 to 22 mm). There was a significant inverse association between PD and biliary lithiasis ( P = 0.02). There was no association between PD and pancreatitis. CC was significantly associated with choledochal cyst ( P < 0.0001), pancreatitis ( P = 0.004) and biliary lithiasis ( P < 0.0001), with 21/61 (34.4%) of CC demonstrating stones within (median age: 3.8 y). The CC length was also significantly associated with complications ( P = 0.014), with complication-free cases having a median length of 7 mm (range, 4 to 8) compared with 11 mm (range, 3 to 25) in complicated cases.

Conclusion: APBJ is a frequent finding on pediatric MRCP. CC is significantly associated with choledochal cyst, pancreatitis and lithiasis, and may show stones within them, particularly in small children. PD is inversely associated with biliary lithiasis. Careful PBJ assessment is important in children.

Objectives: Contrast-enhanced MR lymphangiography (CE-MRL) with pedal interstitial injection of a gadolinium-based contrast agent is increasingly employed in patients with lymphedema (off-label use). However, data on short-term tolerability and possible long-term adverse effects are limited. This study aimed to report clinical experiences regarding the tolerability and long-term safety of CE-MRL.

Materials and methods: A total of 168 patients (36 male; mean age 49.1±16.4 y) with clinically diagnosed lymphedema underwent clinically indicated CE-MRL. A total of 8 mL of diluted MR contrast agent (6 mL 1.0 mmol/mL Gadobutrol, 2 mL saline solution) was prepared. After intradermal administration of 0.2 mL local anesthetic, 1 mL of this contrast agent solution was injected intradermally into each interdigital space. To assess tolerability, patients were asked after the examination about their experience regarding remaining motionless during the examination, confinement in the MRI scanner, interdigital contrast injection, and the overall experience [5-point Likert scale (1: very easy/well tolerable, 5: very difficult/intolerable)]. Adverse events were systematically recorded during a clinical follow-up visit (≥3 mo after CE-MRL) through direct patient inquiry and inspection of the injection sites.

Results: CE-MRL was technically successful in all cases. Mean clinical follow-up was 36±19 months (range: 3 to 81 mo). The ease of remaining motionless was rated as very easy or mostly easy in 98.2% of cases, the tolerability of confinement in the MRI scanner as well as tolerable or mostly tolerable in 97.6%, the contrast injection in 85.1%, and the overall experience in 97.6%. In addition, 95.8% of patients would recommend CE-MRL under similar conditions. Five patients reported transient irritation of the skin (n=3, 1.8%) and/or light interdigital pain (n=3, 1.8%) for 1 or 2 days at the injection site. No other adverse events were observed.

Conclusion: CE-MRL is well tolerated and safe. Intradermal interdigital contrast injection was the most uncomfortable part of the examination, but was still well tolerated by most patients without any long-term adverse events.