Investigative Radiology最新文献

Objectives: Clinical experience regarding the use of dedicated photon-counting breast CT (PC-BCT) for diagnosis of breast microcalcifications is scarce. This study systematically compares the detection and classification of breast microcalcifications using a dedicated breast photon-counting CT, especially designed for examining the breast, in comparison with digital breast tomosynthesis (DBT).

Materials and methods: This is a prospective intraindividual study on women with DBT screening-detected BI-RADS-4/-5 microcalcifications who underwent PC-BCT before biopsy. PC-BCT images were reconstructed with a noninterpolated spatial resolution of 0.15 × 0.15 × 0.15 mm (reconstruction mode 1 [RM-1]) and with 0.3 × 0.3 × 0.3 mm (reconstruction mode 2 [RM-2]), plus thin-slab maximum intensity projection (MIP) reconstructions. Two radiologists independently rated the detection of microcalcifications in direct comparison with DBT on a 5-point scale. The distribution and morphology of microcalcifications were then rated according to BI-RADS. The size of the smallest discernible microcalcification particle was measured. For PC-BCT, the average glandular dose was determined by Monte Carlo simulations; for DBT, the information provided by the DBT system was used.

Results: Between September 2022 and July 2023, 22 participants (mean age, 61; range, 42-85 years) with microcalcifications (16 malignant; 6 benign) were included. In 2/22 with microcalcifications in the posterior region, microcalcifications were not detectable on PC-BCT, likely because they were not included in the PC-BCT volume. In the remaining 20 participants, microcalcifications were detectable. With high between-reader agreement (κ > 0.8), conspicuity of microcalcifications was rated similar for DBT and MIPs of RM-1 (mean, 4.83 ± 0.38 vs 4.86 ± 0.35) ( P = 0.66), but was significantly lower ( P < 0.05) for the remaining PC-BCT reconstructions: 2.11 ± 0.92 (RM-2), 2.64 ± 0.80 (MIPs of RM-2), and 3.50 ± 1.23 (RM-1). Identical distribution qualifiers were assigned for PC-BCT and DBT in 18/20 participants, with excellent agreement (κ = 0.91), whereas identical morphologic qualifiers were assigned in only 5/20, with poor agreement (κ = 0.44). The median size of smallest discernible microcalcification particle was 0.2 versus 0.6 versus 1.1 mm in DBT versus RM-1 versus RM-2 ( P < 0.001), likely due to blooming effects. Average glandular dose was 7.04 mGy (PC-BCT) versus 6.88 mGy (DBT) ( P = 0.67).

Conclusions: PC-BCT allows reliable detection of in-breast microcalcifications as long as they are not located in the posterior part of the breast and allows assessment of their distribution, but not of their individual morphology.

Objectives: Fibrosis is the final common pathway for chronic kidney disease and the best predictor for disease progression. Besides invasive biopsies, biomarkers for its detection are lacking. To address this, we used hyperpolarized 13 C-pyruvate MRI to detect the metabolic changes associated with fibrogenic activity of myofibroblasts.

Materials and methods: Hyperpolarized 13 C-pyruvate MRI was performed in 2 pig models of kidney fibrosis (unilateral ureteral obstruction and ischemia-reperfusion injury). The imaging data were correlated with histology, biochemical, and genetic measures of metabolism and fibrosis. The porcine experiments were supplemented with cell-line experiments to inform the origins of metabolic changes in fibrogenesis. Lastly, healthy and fibrotic human kidneys were analyzed for the metabolic alterations accessible with hyperpolarized 13 C-pyruvate MRI.

Results: In the 2 large animal models of kidney fibrosis, metabolic imaging revealed alterations in amino acid metabolism and glycolysis. Conversion from hyperpolarized 13 C-pyruvate to 13 C-alanine decreased, whereas conversion to 13 C-lactate increased. These changes were shown to reflect profibrotic activity in cultured epithelial cells, macrophages, and fibroblasts, which are important precursors of myofibroblasts. Importantly, metabolic MRI using hyperpolarized 13 C-pyruvate was able to detect these changes earlier than fibrosis-sensitive structural imaging. Lastly, we found that the same metabolic profile is present in fibrotic tissue from human kidneys. This affirms the translational potential of metabolic MRI as an early indicator of fibrogenesis associated metabolism.

Conclusions: Our findings demonstrate the promise of hyperpolarized 13 C-pyruvate MRI for noninvasive detection of fibrosis development, which could enable earlier diagnosis and intervention for patients at risk of kidney fibrosis.

Objectives: To investigate the signal-enhancement properties of the tetrameric gadolinium-based contrast agent (GBCA) gadoquatrane in relation to the administered dose and compare its properties to those of a standard dose of gadobutrol, as a representative of the currently established macrocyclic GBCAs for magnetic resonance imaging.

Materials and methods: In this randomized, single-blind, 4 × 4 crossover study, 43 healthy adults (19-50 years of age) received 3 single IV injections of gadoquatrane (0.01, 0.03, and 0.06 mmol gadolinium/kg body weight) and 1 injection of gadobutrol (0.1 mmol gadolinium/kg body weight) in randomized sequence with 1-week washout periods between administrations. The relative signal enhancement (RSE) was determined in predefined areas of interest in magnetic resonance image sets of the head-neck region. RSE-vs-dose curves (dose-response curves) were established by linear regression, and comparator-equivalent doses were determined by Bayesian inverse regression analysis. Further, 3 blood samples were taken after each injection for pharmacokinetic analyses, and safety data were assessed.

Results: The RSE increased with gadoquatrane dose. A linear function adequately fitted this relationship. In line with the more than 2-fold higher r1 relaxivity of gadoquatrane per gadolinium ion, gadobutrol-equivalent RSE was achieved with gadoquatrane at less than half the gadolinium dose and less than one eighth of the molecule dose.Administration of gadoquatrane and gadobutrol resulted in very similar dose-normalized gadolinium concentrations in plasma, indicating that the pharmacokinetic profiles are essentially the same. Both contrast agents were well tolerated. Adverse events were rare and not dependent on the dose administered.

Conclusions: Gadoquatrane has the potential to be an effective GBCA that can be used at substantially lower doses in clinical routine than the currently established macrocyclic GBCAs.

Objectives: To evaluate the detectability of non-contrast-enhanced and contrast-enhanced spiral breast computed tomography ([non]-CE-SBCT) compared with mammography. Secondary objectives are to determine detectability depending on breast density and to evaluate appearance of breast malignancies according to BI-RADS descriptors.

Methods: This retrospective institutional review board-approved study included 90 women with 105 biopsy-proven malignant breast lesions. Breast density, BI-RADS descriptors, and detectability were evaluated by 2 independent readers. Diagnostic confidence was rated on a 4-point Likert scale.

Results: For readers 1 and 2, detectability was 83.8% and 80.0% for mammography, 99.1% and 99.1% for CE-SBCT ( P < 0.05), and 66.7% and 61.9% for non-CE-SBCT ( P < 0.05). With both readers, detectability in CE-SBCT was high for density A/B/C/D (both 100%/100%/100%/87.5%). Detectability of readers declined with increasing density for mammography (density A = 100%, B = 89.1% and 95.1%, C = 73.1%, D = 50.0% and 71.4%; P < 0.05) and for non-CE-SBCT (density A = 87.5% and 90.7%, B = 65.5% and 69.1%, C = 54.8% and 60.0%, D = 37.5%; P < 0.05). Mass lesions were detected with CT as often as with mammography, whereas architectural distortions and microcalcifications were detected less often with SBCT. Diagnostic confidence was very high or high in 97.2% for CE-SBCT, in 74.1% for non-CE-SBCT, and in 81.4% for mammography.

Conclusions: Detectability and diagnostic confidence were very high in CE-SBCT, regardless of breast density. The detectability of non-CE-SBCT was lower than that of mammography and declined with increasing breast density.

Objectives: Deep learning (DL) studies for the detection of clinically significant prostate cancer (csPCa) on magnetic resonance imaging (MRI) often overlook potentially relevant clinical parameters such as prostate-specific antigen, prostate volume, and age. This study explored the integration of clinical parameters and MRI-based DL to enhance diagnostic accuracy for csPCa on MRI.

Materials and methods: We retrospectively analyzed 932 biparametric prostate MRI examinations performed for suspected csPCa (ISUP ≥2) at 2 institutions. Each MRI scan was automatically analyzed by a previously developed DL model to detect and segment csPCa lesions. Three sets of features were extracted: DL lesion suspicion levels, clinical parameters (prostate-specific antigen, prostate volume, age), and MRI-based lesion volumes for all DL-detected lesions. Six multimodal artificial intelligence (AI) classifiers were trained for each combination of feature sets, employing both early (feature-level) and late (decision-level) information fusion methods. The diagnostic performance of each model was tested internally on 20% of center 1 data and externally on center 2 data (n = 529). Receiver operating characteristic comparisons determined the optimal feature combination and information fusion method and assessed the benefit of multimodal versus unimodal analysis. The optimal model performance was compared with a radiologist using PI-RADS.

Results: Internally, the multimodal AI integrating DL suspicion levels with clinical features via early fusion achieved the highest performance. Externally, it surpassed baselines using clinical parameters (0.77 vs 0.67 area under the curve [AUC], P < 0.001) and DL suspicion levels alone (AUC: 0.77 vs 0.70, P = 0.006). Early fusion outperformed late fusion in external data (0.77 vs 0.73 AUC, P = 0.005). No significant performance gaps were observed between multimodal AI and radiologist assessments (internal: 0.87 vs 0.88 AUC; external: 0.77 vs 0.75 AUC, both P > 0.05).

Conclusions: Multimodal AI (combining DL suspicion levels and clinical parameters) outperforms clinical and MRI-only AI for csPCa detection. Early information fusion enhanced AI robustness in our multicenter setting. Incorporating lesion volumes did not enhance diagnostic efficacy.

Objectives: The aim of this study was to compare the image quality of 7 T turbo spin echo (TSE) knee images acquired with varying factors of parallel-imaging acceleration reconstructed with deep learning (DL)-based and conventional algorithms.

Materials and methods: This was a prospective single-center study. Twenty-three healthy volunteers underwent 7 T knee magnetic resonance imaging. Two-, 3-, and 4-fold accelerated high-resolution fat-signal-suppressing proton density (PD-fs) and T1-weighted coronal 2D TSE acquisitions with an encoded voxel volume of 0.31 × 0.31 × 1.5 mm 3 were acquired. Each set of raw data was reconstructed with a DL-based and a conventional Generalized Autocalibrating Partially Parallel Acquisition (GRAPPA) algorithm. Three readers rated image contrast, sharpness, artifacts, noise, and overall quality. Friedman analysis of variance and the Wilcoxon signed rank test were used for comparison of image quality criteria.

Results: The mean age of the participants was 32.0 ± 8.1 years (15 male, 8 female). Acquisition times at 4-fold acceleration were 4 minutes 15 seconds (PD-fs, Supplemental Video is available at http://links.lww.com/RLI/A938 ) and 3 minutes 9 seconds (T1, Supplemental Video available at http://links.lww.com/RLI/A939 ). At 4-fold acceleration, image contrast, sharpness, noise, and overall quality of images reconstructed with the DL-based algorithm were significantly better rated than the corresponding GRAPPA reconstructions ( P < 0.001). Four-fold accelerated DL-reconstructed images scored significantly better than 2- to 3-fold GRAPPA-reconstructed images with regards to image contrast, sharpness, noise, and overall quality ( P ≤ 0.031). Image contrast of PD-fs images at 2-fold acceleration ( P = 0.087), image noise of T1-weighted images at 2-fold acceleration ( P = 0.180), and image artifacts for both sequences at 2- and 3-fold acceleration ( P ≥ 0.102) of GRAPPA reconstructions were not rated differently than those of 4-fold accelerated DL-reconstructed images. Furthermore, no significant difference was observed for all image quality measures among 2-fold, 3-fold, and 4-fold accelerated DL reconstructions ( P ≥ 0.082).

Conclusions: This study explored the technical potential of DL-based image reconstruction in accelerated 2D TSE acquisitions of the knee at 7 T. DL reconstruction significantly improved a variety of image quality measures of high-resolution TSE images acquired with a 4-fold parallel-imaging acceleration compared with a conventional reconstruction algorithm.

Objectives: Inflammatory bowel disease (IBD) subdivides into Crohn disease (CD) and ulcerative colitis (UC), and is characterized by unpredictable periods of inflammation and results in significant patient suffering and even death. Conventional diagnostic methods, for example, colonoscopy, computed tomography, or magnetic resonance imaging, have limitations such as invasiveness, patient discomfort, and limited sensitivity and accuracy. Therefore, we propose ultrasound molecular imaging (USMI) to detect and characterize IBD. First, we evaluated integrin-αvβ3 as a biomarker of IBD in human samples and then used clinically translatable cyclic Arg-Gly-Asp-D-Phe-Lys (cRGDfK)-coupled poly(butyl)cyanoacrylate microbubbles (cRGD-MB) to assess IBD in mice.

Materials and methods: Vascular integrin-αvβ3 expression in human colon tissue samples (healthy, CD and UC, n = 10 per group) was analyzed by immunofluorescence staining. In mice, acute colitis was induced by administration of 4% dextran sodium sulfate in drinking water for 5 days. On day 7, USMI with cRGD-MB was performed in colitis (n = 6) and healthy (n = 5) mice. The signal of bound cRGD-MB was assessed by the destruction-replenishment method. Ex vivo analysis of mouse colon tissue was performed to assess the degree of colitis by hematoxylin-eosin staining and the vascular expression of integrin-αv by immunofluorescence.

Results: Human samples showed a significantly higher vascular integrin-αvβ3 expression in CD and UC tissue, when compared with healthy samples (P < 0.005). In mice, a higher binding of cRGD-MB to inflamed colon was detected by USMI compared with healthy controls (P < 0.005). Immunofluorescence staining confirmed these findings, showing stronger integrin-αv expression in acute colitis, with a good correlation between USMI signal intensity and integrin-αv expression (r = 0.8, P = 0.0016).

Conclusions: Integrin-αvβ3 on vessels is a suitable marker for IBD. USMI using cRGD-MB accurately detects this marker and correlates well with histology. These encouraging results support clinical translation of this imaging method as a noninvasive and cost-effective monitoring tool.

Objectives: Nonenhanced T1-w sequences such as magnetization-prepared 2 rapid acquisition gradient echo (MP2RAGE) and derived fluid and white matter suppression (FLAWS) have demonstrated high performance for detecting brain parenchymal and cervical spine demyelinating lesions in multiple sclerosis. However, their potential for identifying optic nerve (ON) demyelination remains unexplored. The aim of this study was to evaluate the performance of compressed sensing-accelerated (CS) MP2RAGE-FLAWS imaging for detection of ON demyelination lesions compared with T2-w fat-saturated (FS) TSE imaging in a clinical setting.

Materials and methods: We conducted a retrospective study of magnetic resonance scans acquired on patients with central nervous system demyelinating disorders between January and December 2022. Inclusion criteria were the acquisition in the same session of a brain CS-MP2RAGE-FLAWS imaging and a combination of axial + coronal T2-w FS orbital sequences. A 4-step radiological analysis-including blinded and consensus readings-assessed ON lesion detection. The reference standard was the final reading session of radiologists using the entire patient file. Sensitivities and specificities of both sequences were computed and compared using McNemar χ2 tests.

Results: Thirty-nine patients (mean age: 43 ± 14 years; 25 women) were analyzed, including 34 with multiple sclerosis, 2 with MOGAD (myelin oligodendrocyte glycoprotein antibody-associated disease), 1 with NMOSD (neuromyelitis optica spectrum disorder), and 2 with indeterminate demyelinating disease. Among the 78 ONs analyzed, 64 lesions were detected with CS-MP2RAGE-FLAWS as opposed to 37 with 2D T2-w FS imaging, corresponding to a total of 41 and 27 affected nerves, respectively. CS-MP2RAGE-FLAWS exhibited higher sensitivity for overall detection of ON lesions compared with 2D T2-w FS imaging (97.5% vs 67.5%, P = 0.001) without reducing the specificity. Improved lesion detectability with CS-MP2RAGE-FLAWS was significant compared with 2D T2-w FS in intraorbital and intracanalicular segments (respectively, 92.3% vs 50% and 96.3% vs 66.7%; P < 0.05). There was no difference in sensitivity (P = 0.69) or specificity (P = 0.99) regarding the intracranial segment analysis.

Conclusions: CS-MP2RAGE-FLAWS sequence improves ON lesion detection compared with conventional 2D T2-w FS, especially in the intraorbital segment, while simultaneously providing whole-brain and cervical spinal cord imaging at no additional time cost.

Abstract: Gadopiclenol is a novel, macrocyclic high-relaxivity gadolinium-based contrast agent recently approved for use in magnetic resonance imaging of the central nervous system and body organs at a dose of 0.05 mmol/kg body weight. Postmarketing surveillance of its first year of clinical use in the United States of America showed no serious adverse events (AEs) following over 882,550 administrations and a very low rate of nonserious AEs (1 case every 27,580 exposures). The types of observed AEs were similar to those reported for other gadolinium-based contrast agents in clinical use. Safety data from postmarketing surveillance of gadopiclenol further confirm its positive benefit-risk profile demonstrated in preapproval clinical studies.

Background: Ultrashort echo time (UTE) allows imaging of tissues with short relaxation times, but it comes with the expense of long scan times. Magnitude images of UTE magnetic resonance imaging (MRI) are widely used in pulmonary imaging due to excellent parenchymal signal, but have insufficient contrast for other anatomical regions of the thorax. Our work investigates the value of UTE phase images (UTE-Ps)-generated simultaneously from the acquired UTE signal used for the magnitude images-for the detection of thoracic lymph nodes based on water-fat contrast. It employs an advanced imaging sequence and reconstruction allowing isotropic 3D UTE MRI in clinically acceptable scan times.

Methods: In our prospective study, 42 patients with 136 lymph nodes had undergone venous computed tomography and pulmonary MRI scans with UTE within a 14-day interval. 3D isotropic UTE images were acquired using FLORET (fermat looped, orthogonally encoded trajectories). Background-corrected phase images (UTE-P) and magnitude images were reconstructed simultaneously from the UTE-Signal. Three radiologists performed a blinded reading in which all lymph nodes with a short-axis diameter (SAD) of at least 0.5 cm were detected. Detection rates and performance metrics of UTE-P for all lymph node regions and for pathologic (SAD ≥10 mm) and nonpathologic lymph nodes (SAD <10 mm) were calculated using computed tomography as a reference. The interreader agreement defined as the presence or absence of lymph nodes based on patient and region was calculated using Fleiss kappa (κ).

Findings: In the phase images, pathologic lymph nodes in the mediastinal and hilar region were detected with a high diagnostic confidence due to the achieved water-fat contrast (average sensitivity, specificity, positive predictive value, and negative predictive value of 95.83% [confidence interval (CI), 92.76%-98.91%], 100%, 100%, and 99.32% [CI, 98.08%-100%]). Stepwise inclusion of all lymph node regions and nonpathologic lymph nodes was associated with a moderate decrease resulting in an average sensitivity, specificity, positive predictive value, and negative predictive value of 77.9% (CI, 70.9%-84.7%), 99.4% (CI, 98.7%-99.9%), 97.0% (CI, 93.4%-99.7%), and 94.7% (CI, 92.8%-96.4%) for the inclusion of all lymph nodes sizes and regions. Interreader agreement was almost perfect (κ = 0.92).

Conclusions: Pathological lymph nodes in the mediastinal and hilar region can be detected in phase-images with high diagnostic confidence, thanks to the ability of the phase images to depict water-fat contrast in combination with high spatial 3D resolution, extending the clinical applicability of UTE into the simultaneous assessment of lung parenchyma and lymph nodes.