Investigative Radiology最新文献

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.

Objectives: To compare the performance of conventional CT (conv-CT) and spectral CT (spectral-CT) for the detection and characterization of communications between the true (TL) and false lumen (FL) in aortic dissections, using 4D flow MRI as the reference.

Materials and methods: Eighteen patients with type A and type B aortic dissection who underwent 4D flow MRI, conv-CT and spectral-CT were retrospectively analyzed. For each patient, the examinations closest in time, without any intervention in-between, were retrieved and subjectively analyzed by 2 observers, independently for conv-CT and in consensus for MRI and spectral-CT. Communications between the two lumina were identified as: focal alterations in velocities corresponding to jet flows on 4D flow; both intimal tears and/or focal changes of contrast concentration corresponding to jet flows on conv-CT and spectral-CT. The number and location of communications were noted. The direction of the flow was assessed whenever the jet flow was visible. The performance of conventional and spectral-CT was calculated.

Results: Of the 176 communications detected with 4D flow, spectral-CT allowed visualization of 122(69%) compared with 58 (33%) for observer-1 and 38 (22%) for observer-2 for conv-CT, yielding an accuracy twice as high (63% vs 29% to 30%).Only jet flows, without visible intimal tears, were detected in 0 and 77 (63%) cases for conv-CT and spectral-CT, respectively.The flow was unidirectional FL-TL in 2 cases for MRI and spectral-CT and 1 case for conv-CT, bidirectional in 5 and 3 cases for MRI and spectral-CT, respectively. In all other cases, the direction was TL-FL.

Conclusion: Spectral-CT outperformed conv-CT for the detection of communications between TL and FL in aortic dissections. Spectral-CT allowed for direct visualization of flow jets, and their direction, through intimal tears.

Background and objectives: Following endovascular repair of an aortic aneurysm, patients need regular surveillance using CT to exclude endoleaks. The optimal technical parameters for photon-counting detector CT (PCD-CT) have not yet been established in this clinical context. This study examines the impact of the ultra-high resolution (UHR) mode and monoenergetic reconstructions at various keV on the detection of small endoleaks in experimental settings.

Materials and methods: An aneurysm phantom model mimicking medium- and large-sized patients was scanned using PCD-CT. Monoenergetic images (MEIs) were reconstructed with standard resolution at 40, 45, 50, 55, and 60 keV and with UHR at 45, 50, and 55 keV. Three independent blinded radiologists assessed 80 CT series containing 2880 simulated endoleaks with diameters of 2, 4, and 6 mm. The observers' ratings were analyzed and compared with the jackknife alternative free-response operational characteristics (JAFROC1) method by calculating a figure-of-merit for the performance ( A1 ). The Spearman R was calculated for the correlation between A1 and objective image quality.

Results: The best readers' performance was achieved with the 50 keV UHR, 55 keV standard, 55 keV UHR, and 60 keV standard series ( A1 =0.66 to 0.72) in the medium and with the 55 keV standard, 55 keV UHR, and 60 keV standard reconstructions ( A1 = 0.40 to 0.49) in the large phantom. UHR provided higher A1 than the standard reconstruction at 50 keV for 4 to 6 mm endoleaks ( A1 , 0.82 vs. 0.72; P =0.015 in medium and 0.42 vs. 0.30; P =0.028 in large phantom) and for 6 mm endoleaks ( A1 , 0.93 vs. 0.83; P =0.002 in medium and 0.53 vs. 0.36; P =0.013 in large phantom). In both phantoms, readers' performance correlated negatively with image noise (Spearman R =-0.83; P =0.01 in the medium and Spearman R =-0.98; P <0.001 in the large phantom) and showed no correlation with the contrast-to-noise ratio of endoleaks ( P =0.91 and 0.73).

Conclusions: The 55 keV standard or UHR and 60 keV standard reconstructions yielded the best performance for detecting small endoleaks with PCD-CT. The UHR mode improved performance at 50 keV for 4 to 6 mm and 6 mm endoleaks.

Background: Despite the increasing use of MARS (metal artifact reduction sequence) MRI to investigate painful total hip arthroplasties (THA), no validated criteria exist for diagnosing femoral stem loosening.

Purpose: To evaluate MARS MRI for the diagnosis of aseptic stem loosening and determine its diagnostic accuracy.

Materials and methods: One hundred fourteen consecutive cases with THA revision surgery and MARS MRI of the hip were retrospectively included. Two blinded musculoskeletal radiologists independently assessed periprosthetic bone resorption (PPBR), bone marrow edema (BME), periosteal reaction (PR), and periprosthetic osteolysis (PO) in 14 Gruen zones (GZ). Intraoperative findings at revision surgery served as the ground truth. A predictive model was created using binomial logistic regression models to predict the probability of a loose stem with maximizing positive predictive value (PPV) and accuracy. Interobserver reliability was assessed with absolute agreement, Cohen κ and Gwet AC1.

Results: During surgery, 66 stems were fixed and 48 loose. PPBR occurred significantly more frequently in loose stems across all GZs except GZ11. Proximal PPBR was also observed in fixed stems (up to 23%), whereas middle and distal PPBR were rare (≤3%). BME was most prevalent proximally in all stems (fixed/loose: 39%/60%) with significant differences medially and distally. PR was significantly more frequent in loose stems in the middle and distal GZs. PO were rare, most occurred in GZ7. The predictive model considering proximal PPBR, mid-distal PPBR, mid-distal PR, and distal BME performed with a sensitivity of 0.708, specificity of 0.970, PPV 0.944, negative predictive value 0.821. Interobserver agreement (Gwet AC1) in the considered zones was for PPBR between 0.80 and 0.98, BME 0.91 to 0.99, PR 0.87 to 0.97.

Conclusions: MARS MRI is reproducible and accurate for assessing stem loosening. PPBR, BME, and PR can also be found in fixed THA in the proximal region, whereas they indicate loosening in the middle and distal stem region.