Bei MRT-Kontrastmitteluntersuchungen der Leber müssen im Allgemeinen die Patienten wiederholt den Atem anhalten, um fokale Läsionen ausreichend gut erkennen und charakterisieren zu können. Vielen der Untersuchten fällt das aber schwer, und in der Folge kommt es durch Atembewegungen zu Artefakten, die die Bildinterpretation erschweren bis unmöglich machen.
Background/Objectives: To assess free-breathing, dynamic radial magnetic resonance angiography (MRA) for detecting endoleaks post-endovascular aortic repair (EVAR) in cases with inconclusive computed tomography angiography (CTA). Methods: This prospective single-center study included 17 participants (mean age, 70 ± 9 years; 13 males) who underwent dynamic radial MRI (Golden-angle RAdial Sparse Parallel-Volumetric Interpolated BrEath-hold, GRASP-VIBE) after inconclusive multiphasic CT for the presence of endoleaks during the follow-up of EVAR-treated abdominal aortic aneurysms. CT and MRI datasets were independently assessed by two radiologists for image quality, diagnostic confidence, and the presence/type of endoleak. Statistical analyses included interrater and intermethod agreement, and diagnostic performance (sensitivity, specificity, area under the curve (AUC)). Results: Subjective image analysis demonstrated good image quality and interrater agreement (k ≥ 0.6) for both modalities, while diagnostic confidence was significantly higher in MRA (p = 0.03). There was significantly improved accuracy for detecting type II endoleaks on MRA (AUC 0.97 [95% CI: 0.87, 1.0]) compared to CTA (AUC 0.66 [95% CI: 0.41, 0.91]; p = 0.03). Although MRA demonstrated higher values for sensitivity, specificity, AUC, and interrater agreement, none of the other types nor the overall detection rate for endoleaks showed differences in the diagnostic performance over CT (p ≥ 0.12). CTA and MRA revealed slight to moderate intermethod concordance in endoleak detection (k = 0.3–0.64). Conclusions: The GRASP-VIBE MRA characterized by high spatial and temporal resolution demonstrates clinical feasibility with good image quality and superior diagnostic confidence. It notably enhances diagnostic performance in detecting and classifying endoleaks, particularly type II, compared to traditional multiphase CTA with inconclusive findings.
Off-resonance radiofrequency saturation pulses applied prior to regular excitation in MR sequences can be used to modify signal contrast based on magnetization transfer and direct saturation effects. Clinical applicability and value of ultrashort echo time sequences combined with off-resonance saturation pulses was tested in 16 healthy and 14 tendinopathic as well as paratendinopathic Achilles tendons in vivo at 3 T. A 3D ultrashort echo time sequence in combination with a gaussian off-resonance saturation pulse (frequency offset: 1000-5000 Hz) was used to modify the detectable MR signal intensity from the Achilles tendon. Off-resonance saturation ratio was calculated as the relative reduction in signal intensity under selective off-resonance saturation in relation to a reference measurement without any saturation pulse. Off-resonance saturation ratio in tendons of healthy volunteers ranged from 0.52 ± 0.06 (1000 Hz) to 0.24 ± 0.02 (5000 Hz), whereas symptomatic tendinopathic tendons (0.35 ± 0.04 to 0.17 ± 0.02) and asymptomatic tendinopathic tendons (0.41 ± 0.06 to 0.21 ± 0.02) showed significantly lower mean off-resonance saturation ratio values. Off-resonance saturation ratio values might provide a sensitive and quantitative marker for assessment of pathological microstructure alterations of the Achilles tendon.
To increase precision of radiation treatment (RT) delivery in prostate cancer, MRI-based RT as well as the use of fiducials like gold markers (GMs) have shown promising results. Their combined use is currently under investigation in clinical trials. Here, we aimed to evaluate a workflow of image registration based on GMs between CT and MRI as well as weekly MRI-MRI adaption based on T2 TSE sequence.A gel-phantom with two inserted GMs was scanned with CT and three different MR-scanners of 1.5 and 3 T (T2 TSE and T1 VIBE-Dixon, isotropic, voxel size 2 × 2 × 2 mm). After image fusion, deviations for fiducial and gel match were measured and artifacts were evaluated. Additionally, CT-MRI-match deviations and MRI-MRI-match deviations of 10 Patients from the M-basePro study using GMs were assessed.GMs were visible in all imaging modalities. The outer gel contours were matched with <1 mm deviation, contour volumes varied between 0 and 1%. The deviations of the GMs were less than 2 mm in any direction of MRI/CT. Shifts of peripherally or centrally located GMs were randomly distributed. The average MRI-CT-match precision of 10 patients with GMs was 1.9 mm (range 1.1-3.1 mm).Match inaccuracies for GMs between reference CT and voxel-isotropic T2-TSE sequences are small. Spatial deviations of CT- and MR-contoured fiducials were less than 2 mm, i.e., below SLT of the applied modalities. In patients, the average CT-MRI-match precision for GMs was 1.9 mm supporting their use in MR-guided high precision RT.
The objective of this study was to assess the ability of a quantitative software-aided approach to improve the diagnostic accuracy of 18F FDG PET for Alzheimer's dementia over visual analysis alone. Twenty normal subjects (M:F-12:8; mean age 80.6 years) and twenty mild AD subjects (M:F-12:8; mean age 70.6 years) with 18F FDG PET scans were obtained from the ADNI database. Three blinded readers interpreted these PET images first using a visual qualitative approach and then using a quantitative software-aided approach. Images were classified on two five-point scales based on normal/abnormal (1-definitely normal; 5-definitely abnormal) and presence of AD (1-definitely not AD; 5-definitely AD). Diagnostic sensitivity, specificity, and accuracy for both approaches were compared based on the aforementioned scales. The sensitivity, specificity, and accuracy for the normal vs. abnormal readings of all readers combined were higher when comparing the software-aided vs. visual approach (sensitivity 0.93 vs. 0.83 P = 0.0466; specificity 0.85 vs. 0.60 P = 0.0005; accuracy 0.89 vs. 0.72 P<0.0001). The specificity and accuracy for absence vs. presence of AD of all readers combined were higher when comparing the software-aided vs. visual approach (specificity 0.90 vs. 0.70 P = 0.0008; accuracy 0.81 vs. 0.72 P = 0.0356). Sensitivities of the software-aided and visual approaches did not differ significantly (0.72 vs. 0.73 P = 0.74). The quantitative software-aided approach appears to improve the performance of 18F FDG PET for the diagnosis of mild AD. It may be helpful for experienced 18F FDG PET readers analyzing challenging cases.
Background Bronchial artery embolization (BAE) can be a challenging intervention due to variations of the vascular anatomy. Purpose To evaluate the utility of C-arm cone-beam computed tomography (CBCT) for BAE in patients with hemoptysis and indefinite bronchial artery (BA) anatomy on pre-interventional CT imaging. Material and Methods From November 2016 to July 2017, 17 patients (mean age = 64.3 ± 14.7 years) with hemoptysis underwent BAE including pre-interventional CT, aortography, and CBCT during the procedure. CBCT, angiography, and CT were independently evaluated by readers A and B (with one and three years of experience in interventional radiology) with regard to number and origin of detected BA, image quality, and diagnostic confidence for BA detection (using a Likert scale). Consensus reading by two experienced interventional radiologists served as gold standard (GS). Seventeen consecutive patients who underwent BAE before the installation of the CBCT in October 2016 served as control group. Spearman rank correlation and Wilcoxon signed-rank test were conducted. Results Both readers showed a statistically significant increase in diagnostic confidence for CBCT compared to pre-procedural CT (A: P = 0.003; B: P = 0.03) and for CBCT compared to aortography (A+B: P < 0.001). Correlation coefficient between GS and CBCT regarding the number of detected BA was: r = 0.855 (A), r = 0.877 (B); GS and CT: r = 0.250 (A), r = 0.317 (B); GS and aortography: r = 0.290 (A); r = 0.429 (B). Time to BA catheterization was 32.6 ± 12.5 min (control group 38.5 ± 24.6 min; P = 0.72). Significantly less angiographic series were acquired until BA catheterization after CBCT (1.3 ± 0.7; control group: 3.6 ± 2.9; P = 0.003). Conclusion CBCT supports the assessment of the BA anatomy during BAE in patients with hemoptysis.
