The purpose of this study is 1) to demonstrate reproducibility of spin echo‐echo planar imaging (SE‐EPI) magnetic resonance elastography (MRE) to estimate kidney stiffness; and 2) to compare SE‐EPI ...MRE and gradient recalled echo (GRE) MRE‐derived stiffness estimations in various anatomical regions of the kidney.
Kidney MRE was performed on 33 healthy subjects (8 for SE‐EPI MRE reproducibility and 25 for comparison with GRE MRE; age range: 22–66 years) in a 3 T MRI scanner. To demonstrate SE‐EPI MRE reproducibility, subjects were scanned for the first scan and then asked to leave the scan room and repositioned again for the second (repeat) scan. Similar set‐up was used for GRE MRE as well. The displacement data was then processed to obtain overall stiffness estimates of the kidney. Concordance correlation analyses were performed to determine SE‐EPI MRE reproducibility and agreement between GRE MRE and SE‐EPI MRE derived stiffness.
A high concordance correlation (ρc = 0.95; p‐value<0.0001) was obtained for SE‐EPI MRE reproducibility. Good concordance correlation was observed (ρc = 0.84; p < 0.0001 for both kidneys, ρc = 0.91; p < 0.0001 for right kidney and ρc = 0.78; p < 0.0001 for left kidney) between GRE MRE and SE‐EPI MRE derived stiffness measurements. Paired t‐test results showed that stiffness value of medulla was significantly (p < 0.0001) greater than cortex using SE‐EPI MRE as well as GRE MRE.
SE‐EPI MRE was reproducible and good agreement was observed in MRE‐derived stiffness measurements obtained using SE‐EPI and GRE sequences. Therefore, SE‐EPI can be used for kidney MRE applications.
Renal fibrosis is a common pathway among renal diseases, leading to the progression of chronic kidney disease. Magnetic resonance elastography (MRE) is used to diagnose fibrosis based on stiffness estimates. Our study showed excellent SE‐EPI MRE reproducibility and good agreement between SE‐EPI and GRE‐MRE. Hence, SE‐EPI MRE can be used to perform 3D kidney MRE, as it can significantly shorten scan time compared with GRE‐MRE.
Changes in liver magnetic resonance imaging T1 relaxation times are associated with histologic inflammation and fibrosis.
To compare liver T1 measurements obtained using a novel single-breath-hold ...3-dimensional (3D) whole-liver T1 estimation method (3D-QALAS) to standard-of-care 2-dimensional (2D) modified Look-Locker (2D-MOLLI) measurements.
With institutional review board approval, research magnetic resonance imaging examinations were performed in 19 participants at 1.5 T. T1 relaxometry of the liver was performed using a novel 3D whole-liver T1 estimation method (3D-QALAS) as well as a 2D modified Look-Locker (2D-MOLLI) method. The 3D method covered the entire liver in a single breath hold, whereas 2D imaging was performed at 4 anatomic levels in 4 consecutive breath holds. T1 measurements from parametric maps were obtained by a single operator, and region-of-interest area-weighted mean T1 values were calculated. Pearson correlation ( r ) was used to assess correlation between T1 estimation methods, and the paired t test and Bland-Altman analysis were used to compare agreement in T1 measurements.
In 18 participants (1 participant was excluded from analysis because of respiratory motion artifacts on 3D-QALAS images), 2D-MOLLI and 3D-QALAS mean T1 measurements were strongly correlated ( r = 0.95, 95% CI: 0.87-0.98; P < 0.0001). 2D-MOLLI T1 values were significantly longer than 3D-QALAS values (647.2 ± 87.3 milliseconds vs. 554.7 ± 75.8 milliseconds; P < 0.0001) with mean bias = 92.5 milliseconds (95% limits of agreement, 36.8, 148.2 milliseconds).
Whole-liver T1 measurements obtained using a novel single-breath-hold 3D T1 estimation method correlate with a standard-of-care multiple consecutive-breath-hold 2D single-slice method but demonstrate systematic bias that should be considered or corrected when used in a clinical or research setting.
This study evaluated the concordance between clinical evaluation and diagnosis by a physician associate/assistant (PA) and the preoperative and intraoperative evaluations by a pediatric urologic ...surgeon.
A retrospective chart review was performed for patients independently evaluated and scheduled for surgery by a single PA between 2017 and 2020. Concordance was measured by comparing the PA's office note with the surgeon's preoperative note and operative report.
Of the 242 patients scheduled for surgery, 11 underwent an operative report procedure change and 11 others underwent a preoperative note procedure change. Concordance increased from 89.09% in 2017 to 92.31% in 2020; this was not statistically significant ( P = .230). Urologic conditions evaluated demonstrated an increase in the variety and complexity of conditions.
A supervisory/collaborative model involving a well-trained PA yields excellent outcomes in terms of concordance with surgical scheduling and procedure performed.
Background
Innate defense regulator peptide-1018 (IDR-1018) is a 12-amino acid, synthetic, immunomodulatory host defense peptide that can reduce soft tissue infections and is less likely to induce ...bacterial resistance than conventional antibiotics. However, IDRs have not been tested on orthopaedic infections and the immunomodulatory effects of IDR-1018 have only been characterized in response to lipopolysacharide, which is exclusively produced by Gram-negative bacteria.
Questions/purposes
We sought (1) to more fully characterize the immunomodulatory effects of IDR-1018, especially in response to
Staphylococcus aureus
; and (2) to determine whether IDR-1018 decreases
S aureus
infection of orthopaedic implants in mice and thereby protects the implants from failure to osseointegrate.
Methods
In vitro effects of IDR-1018 on
S aureus
were assessed by determining minimum inhibitory concentrations in bacterial broth without and with supplementation of physiologic ion levels. In vitro effects of IDR-1018 on macrophages were determined by measuring production of monocyte chemoattractant protein-1 (MCP-1) and proinflammatory cytokines by enzyme-linked immunosorbent assay. In vivo effects of IDR-1018 were determined in a murine model of
S aureus
implant infection by quantitating bacterial burden, macrophage recruitment, MCP-1, proinflammatory cytokines, and osseointegration in nine mice per group on Day 1 postimplantation and 20 mice per group on Day 15 postimplantation.
Results
IDR-1018 demonstrated antimicrobial activity by directly killing
S aureus
even in the presence of physiologic ion levels, increasing recruitment of macrophages to the site of infections by 40% (p = 0.036) and accelerating
S aureus
clearance in vivo (p = 0.008) with a 2.6-fold decrease in bacterial bioburden on Day 7 postimplantation. In vitro immunomodulatory activity of IDR-1018 included inducing production of MCP-1 in the absence of other inflammatory stimuli and to potently blunt excess production of proinflammatory cytokines and MCP-1 induced by lipopolysaccharide. Higher concentrations of IDR-1018 were required to blunt production of proinflammatory cytokines and MCP-1 in the presence
S aureus
. The largest in vivo immunomodulatory effect of IDR-1018 was to reduce tumor necrosis factor-α levels induced by
S aureus
by 60% (p = 0.006). Most importantly, IDR-1018 reduced
S aureus
-induced failures of osseointegration by threefold (p = 0.022) and increased osseointegration as measured by ultimate force (5.4-fold, p = 0.033) and average stiffness (4.3-fold, p = 0.049).
Conclusions
IDR-1018 is potentially useful to reduce orthopaedic infections by directly killing bacteria and by recruiting macrophages to the infection site.
Clinical Relevance
These findings make IDR-1018 an attractive candidate to explore in larger animal models to ascertain whether its effects in our in vitro and mouse experiments can be replicated in more clinically relevant settings.
In pediatrics, tracheomalacia is an airway condition that causes tracheal lumen collapse during breathing and may lead to the patient requiring respiratory support. Adult patients can narrow their ...glottis to self-generate positive end-expiratory pressure (PEEP) to raise the pressure in the trachea and prevent collapse. However, auto-PEEP has not been studied in newborns with tracheomalacia. The objective of this study was to measure the glottis cross-sectional area throughout the breathing cycle and to quantify total pressure difference through the glottis in patients with and without tracheomalacia.
Do neonates with tracheomalacia narrow their glottises? How does the glottis narrowing affect the total pressure along the airway?
Ultrashort echo time MRI was performed in 21 neonatal ICU patients (11 with tracheomalacia, 10 without tracheomalacia). MRI scans were reconstructed at four different phases of breathing. All patients were breathing room air or using noninvasive respiratory support at the time of MRI. Computational fluid dynamics simulations were performed on patient-specific virtual airway models with airway anatomic features and motion derived via MRI to quantify the total pressure difference through the glottis and trachea.
The mean glottis cross-sectional area at peak expiration in the patients with tracheomalacia was less than half that in patients without tracheomalacia (4.0 ± 1.1 mm2 vs 10.3 ± 4.4 mm2; P = .002). The mean total pressure difference through the glottis at peak expiration was more than 10 times higher in patients with tracheomalacia compared with patients without tracheomalacia (2.88 ± 2.29 cm H2O vs 0.26 ± 0.16 cm H2O; P = .005).
Neonates with tracheomalacia narrow their glottises, which raises pressure in the trachea during expiration, thereby acting as auto-PEEP.
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Purpose
Multiparametric quantitative renal MRI may provide noninvasive radiologic biomarkers of chronic kidney disease (CKD) based on investigations in animal models and adults. We aimed to (1) ...obtain normative multiparametric quantitative MRI data from the kidneys of healthy children and young adults, (2) compare MRI measurements between healthy control participants and patients with CKD, and (3) determine if MRI measurements correlate with clinical and laboratory data as well as histology.
Methods
This was a prospective, case-control study of 20 healthy controls and 12 CKD patients who underwent percutaneous renal biopsy ranging from 12 to 23 years of age between October 2018 and March 2020. Kidney function was documented and pathology assessed for fibrosis/inflammation. Utilizing a field strength of 1.5T, we examined renal T1, T2, and T2* relaxation mapping, MR elastography (MRE), and diffusion-weighted imaging (DWI). A single analyst made all manual measurements for quantitative MRI pulse sequences. Independent measurements from cortex, medulla, and whole kidney were obtained by drawing regions of interest on single slices from the upper, mid, and lower kidney. A weighted average was calculated for each kidney; if two kidneys, the right and left were averaged. Continuous variables were compared with Mann–Whitney U test; bivariate relationships were assessed using Spearman rank-order correlation.
Results
Median estimated glomerular filtration rate (eGFR) was 112.3 ml/min/1.73 m
2
in controls (
n
= 20, 10 females) and 55.0 ml/min/m
2
in CKD patients (
n
= 12, 2 females) (
p
< 0.0001). Whole kidney (1333 vs. 1291 ms;
p
= 0.018) and cortical (1212 vs 1137 ms;
p
< 0.0001) T1 values were higher in CKD patients. Cortical T1 values correlated with eGFR (rho = − 0.62;
p
= 0.0003) and cystatin C (rho = 0.58;
p
= 0.0007). Whole kidney (1.87 vs. 2.02 10
–3
mm
2
/s;
p
= 0.007), cortical (1.89 vs. 2.04 10
–3
mm
2
/s;
p
= 0.008), and medullary (1.87 vs. 1.98 10
–3
mm
2
/s;
p
= 0.0095) DWI apparent diffusion coefficients (ADC) were lower in CKD patients. Whole kidney ADC correlated with eGFR (rho = 0.45;
p
= 0.012) and cystatin C (rho = − 0.46;
p
= 0.009). Cortical histologic inflammation correlated with DWI ADC (rho = − 0.71;
p
= 0.011).
Conclusion
Renal T1 relaxation and DWI ADC measurements differ between pediatric healthy controls and CKD patients, correlate with laboratory markers of CKD, and may have histologic correlates.
Purpose
Define relationships between quantitative magnetic resonance imaging (MRI) metrics and clinical/laboratory data in a pediatric and young adult cohort with autoimmune liver disease (AILD).
...Materials and methods
This prospective, cross-sectional study was institutional review board-approved. Patients enrolled in an institutional AILD registry were divided into groups: (1) autoimmune hepatitis (AIH) or (2) primary sclerosing cholangitis (PSC)/autoimmune sclerosing cholangitis (ASC). Participants underwent serum liver biochemistry testing and research MRI examinations, including 3D magnetic resonance cholangiopancreatography (MRCP), magnetic resonance elastography (MRE), and iron-corrected T1 mapping (cT1). MRCP + and LiverMultiScan (Perspectum Ltd., Oxford, UK) were used to post-process 3D MRCP and cT1 data. Multiple linear regression models were used to assess relationships.
Results
58 patients, 35 male, median age 16 years were included; 30 in the AIH group, 28 in the PSC/ASC group. After statistical adjustments for patient age, sex, presence of inflammatory bowel disease (IBD), specific diagnosis (PSC/ASC vs. AIH), and time from diagnosis to MRI examination, left hepatic bile duct maximum diameter was a statistically significant predictor of whole liver mean cT1, cT1 interquartile range (IQR), and MRE liver stiffness (
p
= 0.01–0.04). Seven laboratory values were significant predictors of whole liver cT1 IQR (
p
< 0.0001–0.04). Eight laboratory values and right hepatic bile duct median and maximum diameter were significant predictors of liver stiffness (
p
< 0.0001–0.03).
Conclusions
Bile duct diameters and multiple laboratory biomarkers of liver disease are independent predictors of liver stiffness and cT1 IQR in pediatric patients with AILD.
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