Phantom study for comparison between computed tomography- and C-Arm computed tomography-guided puncture applied by residents in radiology. / Phantomstudie zum Vergleich zwischen Computertomografie- und C-Arm-Computertomografie-gesteuertem Punktionsverfahren bei Anwendung durch Weiterbildungsassistenten in der Radiologie.

PURPOSE: Comparison of puncture deviation and puncture duration between computed tomography (CT)- and C-arm CT (CACT)-guided puncture performed by residents in training (RiT). METHODS: In a cohort of 25 RiTs enrolled in a research training program either CT- or CACT-guided puncture was performed on a phantom. Prior to the experiments, the RiT's level of training, experience playing a musical instrument, video games, and ball sports, and self-assessed manual skills and spatial skills were recorded. Each RiT performed two punctures. The first puncture was performed with a transaxial or single angulated needle path and the second with a single or double angulated needle path. Puncture deviation and puncture duration were compared between the procedures and were correlated with the self-assessments. RESULTS: RiTs in both the CT guidance and CACT guidance groups did not differ with respect to radiologic experience (p = 1), angiographic experience (p = 0.415), and number of ultrasound-guided puncture procedures (p = 0.483), CT-guided puncture procedures (p = 0.934), and CACT-guided puncture procedures (p = 0.466). The puncture duration was significantly longer with CT guidance (without navigation tool) than with CACT guidance with navigation software (p < 0.001). There was no significant difference in the puncture duration between the first and second puncture using CT guidance (p = 0.719). However, in the case of CACT, the second puncture was significantly faster (p = 0.006). Puncture deviations were not different between CT-guided and CACT-guided puncture (p = 0.337) and between the first and second puncture of CT-guided and CACT-guided puncture (CT: p = 0.130; CACT: p = 0.391). The self-assessment of manual skills did not correlate with puncture deviation (p = 0.059) and puncture duration (p = 0.158). The self-assessed spatial skills correlated positively with puncture deviation (p = 0.011) but not with puncture duration (p = 0.541). CONCLUSION: The RiTs achieved a puncture deviation that was clinically adequate with respect to their level of training and did not differ between CT-guided and CACT-guided puncture. The puncture duration was shorter when using CACT. CACT guidance with navigation software support has a potentially steeper learning curve. Spatial skills might accelerate the learning of image-guided puncture. KEY POINTS: · The CT-guided and CACT-guided puncture experience of the RiTs selected as part of the program "Researchers for the Future" of the German Roentgen Society was adequate with respect to the level of training.. · Despite the lower collective experience of the RiTs with CACT-guided puncture with navigation software assistance, the learning curve regarding CACT-guided puncture may be faster compared to the CT-guided puncture technique.. · If the needle path is complex, CACT guidance with navigation software assistance might have an advantage over CT guidance.. CITATION FORMAT: · Meine TC, Hinrichs JB, Werncke T et al. Phantom study for comparison between computed tomography- and C-Arm computed tomography-guided puncture applied by residents in radiology. Fortschr Röntgenstr 2022; 194: 272 - 280.

Arterial attenuation in individualized computed tomography pulmonary angiography injection protocol adjusted based on the patient's body mass index.

BACKGROUND: The aim of this study was to optimize computed tomography pulmonary angiography (CTPA) protocols with regard to improve vascular attenuation without increasing contrast media (CM) volumes. Therefore, we compared the standard CTPA protocol to an individualized contrast media injection protocols adjusted for the patient's body mass index (BMI). MATERIALS AND METHODS: Two groups of 295 patients with suspected pulmonary embolism (PE) have been receiving CTPA. Group 1 received a standard protocol without taking patient's BMI into account. Group 2 received a CTPA scan, where dose and flow rate of CM injections were adjusted for the patient's BMI. Images were retrospectively analyzed by drawing regions of interests in defined positions in the superior vena cava, descending aorta, the pulmonary main trunk as well as the left and right lower lobe arteries. Intravascular attenuation, contrast volumes, and flow rates were compared using unpaired t-tests. Furthermore, a qualitative image analysis was performed by two experienced readers blinded for the protocol used for image acquisition to evaluate the image quality and arterial attenuation. RESULTS: Patient's BMI was similar in both the groups (27.5 ± 1.5 kg/m2 vs. 28.4 ± 2.1 kg/m2; P = 0.67). Contrast volumes were lower (54.2 ± 4.8 ml vs. 55 ml; P < 0.05), and flow rates (4.1 ± 0.3 ml/s vs. 3.5 ml/s; P < 0.05) were significantly higher in the individualized protocol. The qualitative image analysis yielded an agreement on diagnostic interpretability in the individualized and standard group of 49% and 51% (95% Wilson confidence interval for mean), respectively. CONCLUSION: An individualized CTPA protocol based on the patient's BMI reduced the contrast media volume and led to an increased pulmonary artery enhancement improving image quality, particularly in the evaluation of the peripheral pulmonary arteries. Thus, contrast media volumes in CTPA should be adjusted for the patient's BMI.

Gd-EOB-DTPA-enhanced MRI for quantitative assessment of liver organ damage after partial hepatic ischaemia reperfusion injury: correlation with histology and serum biomarkers of liver cell injury.

OBJECTIVE: To evaluate Gd-EOB-DTPA-enhanced MRI for quantitative assessment of liver organ damage after hepatic ischaemia reperfusion injury (IRI) in mice. METHODS: Partial hepatic IRI was induced in C57Bl/6 mice (n = 31) for 35, 45, 60 and 90 min. Gd-EOB-DTPA-enhanced MRI was performed 1 day after surgery using a 3D-FLASH sequence. A subgroup of n = 9 animals with 60 min IRI underwent follow-up with MRI and histology 7 days after IRI. The total liver volume was determined by manual segmentation of the entire liver. The volume of functional, contrast-enhanced liver parenchyma was quantified by a region growing algorithm (visual threshold) and an automated segmentation (Otsu's method). The percentages of functional, contrast-enhanced and damaged non-enhanced parenchyma were calculated according to these volumes. MRI data was correlated with serum liver enzyme concentrations and histologically quantified organ damage using periodic acid-Schiff (PAS) staining. RESULTS: The percentage of functional (contrasted) liver parenchyma decreased significantly with increasing ischaemia times (control, 94.4 ± 3.3%; 35 min IRI, 89.3 ± 4.1%; 45 min IRI, 87.9 ± 3.3%; 60 min IRI, 68 ± 10.5%, p < 0.001 vs. control; 90 min IRI, 55.9 ± 11.5%, p < 0.001 vs. control). The percentage of non-contrasted liver parenchyma correlated with histologically quantified liver organ damage (r = 0.637, p < 0.01) and serum liver enzyme elevations (AST r = 0.577, p < 0.01; ALT r = 0.536, p < 0.05). Follow-up MRI visualized recovery of functional liver parenchyma (71.5 ± 8.7% vs. 84 ± 2.1%, p < 0.05), consistent with less histological organ damage on day 7. CONCLUSION: We demonstrated the feasibility of Gd-EOB-DTPA-enhanced MRI for non-invasive quantification of damaged liver parenchyma following IRI in mice. This novel methodology may refine the characterization of liver disease and could have application in future studies targeting liver organ damage. KEY POINTS: • Prolonged ischaemia times in partial liver IRI increase liver organ damage. • Gd-EOB-DTPA-enhanced MRI at hepatobiliary phase identifies damaged liver volume after hepatic IRI. • Damaged liver parenchyma quantified with MRI correlates with histological liver damage. • Hepatobiliary phase Gd-EOB-DTPA-enhanced MRI enables non-invasive assessment of recovery from liver injury.

Assessment of liver ischemia reperfusion injury in mice using hepatic T2 mapping: Comparison with histopathology.

BACKGROUND: Liver ischemia reperfusion injury (IRI) occurs during liver surgery or transplantation resulting in an inflammatory response, tissue damage, and functional impairment of the organ. PURPOSE: To assess the feasibility of T2 mapping for noninvasive quantification of liver edema after partial liver IRI in mice. STUDY TYPE: Prospective, experimental study. ANIMAL MODEL: Partial liver IRI was induced in C57BL/6-mice by transient clamping of the left lateral and median liver lobes for 35 (n = 8), 45 (n = 6), 60 (n = 17), or 90 minutes (n = 5). For comparison, healthy C57BL/6-mice were examined as controls (n = 9). FIELD STRENGTH/SEQUENCE: Functional liver MRI was performed on a 7T scanner using a respiratory-triggered multiecho spin-echo sequence. ASSESSMENT: Healthy control mice and mice with partial liver IRI on day 1 after surgery, and additionally on day 7 in a subgroup with 60 minutes IRI (n = 8) were examined. Maps of T2 relaxation time of liver tissue were used to assess distribution, severity of tissue edema (mean T2 time), and the percentage of edematous liver tissue. STATISTICAL TEST: One-way analysis of variance (ANOVA) with Tukey's honest significant difference (HSD), paired t-tests, Pearson's test for correlation of MRI parameters with levels of liver enzymes, and histopathology, receiver operating characteristic (ROC) analysis. RESULTS: Significant tissue edema induced by liver IRI as compared to the control group was detected by increased mean T2 times in groups with 60 minutes (P < 0.001) and 90 minutes IRI (P < 0.001). The percentage of edematous liver tissue significantly increased with longer ischemia times (controls 3.4 ± 0.4%, 35 minutes 5.3 ± 0.6%, 45 minutes 23.3 ± 7.6%, 60 minutes 39.7 ± 3.6%, 90 minutes 51.3 ± 4.5%). Mean T2 times and the percentage of edematous liver tissue significantly correlated with elevation of liver enzymes (P < 0.001), histological evidence of liver injury (r = 0.80 and r = 0.82, P < 0.001), and neutrophil infiltration (r = 0.70 and r = 0.74, P < 0.001). In the subgroup with follow-up, the severity (P < 0.01) and extent of liver edema decreased significantly over time (P < 0.01). DATA CONCLUSION: T2 mapping allows quantification and follow-up of liver injury in mice. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;48:1586-1594.

Correlation of size-dependent conversion factor and body-mass-index using size-specific dose estimates formalism in CT examinations.

PURPOSE: The aim of this investigation is to establish the relationship between the size-dependent conversion factor (fsize) and the body-mass-index (BMI) and to test whether BMI can be substituted for the conventionally used patients' anterior-posterior (AP) and lateral (LAT) dimensions for calculation of fsize. By calculating fsize on the basis of BMI instead of the AP and LAT measurements, size-specific dose estimates (SSDE) could be determined prior to image acquisition. METHODS: Our institute utilizes a dose monitoring software to record radiation exposure during CT examinations. The datasets gathered during each examination contain information regarding the scan protocol, the volumetric computed tomography dose index (CTDIvol), SSDE and BMI. fsize is traditionally calculated through measurement of AP and LAT dimensions. In this work, the dose monitoring system calculates AP and LAT diameters at the middle of scout views. For purpose of this investigation, we used data from 13544 patients who underwent CT examinations of the torso, head or knee (both) to compare fsize as calculated from the AP and LAT dimensions to fsize calculated as a function of BMI. RESULTS: In the examinations of the torso, we observed an exponentially decreasing correlation between fsize and BMI. In the examinations of the head and knee (both), fsize reflected an almost independent behavior to BMI. CONCLUSION: This study demonstrates that it is possible to estimate fsize by using the patients' BMI for the torso as well as the head and knee CT, thereby enabling calculation of the probable SSDE prior to image acquisition on the basis of the presumed CTDIvol provided by the scanner. By providing information on the expected patient dose prior to image acquisition, this method is advantageous over the traditional calculation of fsize via the AP and LAT dimensions.

The chemokine receptor CX3CR1 coordinates monocyte recruitment and endothelial regeneration after arterial injury.

Regeneration of arterial endothelium after injury is critical for the maintenance of normal blood flow, cell trafficking, and vascular function. Using mouse models of carotid injury, we show that the transition from a static to a dynamic phase of endothelial regeneration is marked by a strong increase in endothelial proliferation, which is accompanied by induction of the chemokine CX3CL1 in endothelial cells near the wound edge, leading to progressive recruitment of Ly6Clo monocytes expressing high levels of the cognate CX3CR1 chemokine receptor. In Cx3cr1-deficient mice recruitment of Ly6Clo monocytes, endothelial proliferation and regeneration of the endothelial monolayer after carotid injury are impaired, which is rescued by acute transfer of normal Ly6Clo monocytes. Furthermore, human non-classical monocytes induce proliferation of endothelial cells in co-culture experiments in a VEGFA-dependent manner, and monocyte transfer following carotid injury promotes endothelial wound closure in a hybrid mouse model in vivo Thus, CX3CR1 coordinates recruitment of specific monocyte subsets to sites of endothelial regeneration, which promote endothelial proliferation and arterial regeneration.

Usability of Functional MRI in Clinical Studies for Fast and Reliable Assessment of Renal Perfusion and Quantification of Hemodynamic Effects on the Kidney.

The purpose of this study was to evaluate contrast-media-free arterial spin labeling, a technique of functional magnetic resonance imaging (MRI), for assessment of kidney perfusion in a clinical study. We examined renal perfusion by arterial spin labeling in 15 healthy adults using a clinical 1.5-T MRI system, twice under baseline conditions and 60 minutes after a single oral dose of 50 mg captopril. Data evaluation included assessment of interstudy and interrater reproducibility in addition to the pharmacological effect of captopril on kidney perfusion and a sample size calculation for potential application of the technique in pharmacological intervention studies. Interstudy reproducibility of cortical and medullary kidney perfusion was excellent (intraclass correlation coefficients 0.77 and 0.83, respectively). Interrater reproducibility was excellent in the cortex and good in the medulla (intraclass correlation coefficients 0.97 and 0.66, respectively). Ingestion of 50 mg captopril was associated with an 11% drop of systolic blood pressure and a rise in kidney perfusion by 22% in the cortex (369 ± 48 vs 452 ± 56 mL/[min·100 g], P < .001) and 26% in the medulla (157 ± 39 to 198 ± 45 ml/[min·100 g]; P < .01). Statistical power analysis revealed that a small sample size of only 6 participants is needed in a clinical trial to capture an equal change in kidney perfusion to the one induced by 50 mg captopril with a statistical power of 82% and an α error of 0.05. In conclusion, funtional MRI with arterial spin labeling is a reliable method for quantification of kidney perfusion and for fast assessment of pharmacologically induced renal perfusion changes, allowing low case numbers.