Magnetic Resonance Imaging of Lung Perfusion

"Lung perfusion" in the context of imaging conventionally refers to the delivery of blood to the pulmonary capillary bed through the pulmonary arteries originating from the right ventricle required for oxygenation. The most important physiological mechanism in the context of imaging is the so-called hypoxic pulmonary vasoconstriction (HPV, also known as "Euler-Liljestrand-Reflex"), which couples lung perfusion to lung ventilation. In obstructive airway diseases such as asthma, chronic-obstructive pulmonary disease (COPD), cystic fibrosis (CF), and asthma, HPV downregulates pulmonary perfusion in order to redistribute blood flow to functional lung areas in order to conserve optimal oxygenation. Imaging of lung perfusion can be seen as a reflection of lung ventilation in obstructive airway diseases. Other conditions that primarily affect lung perfusion are pulmonary vascular diseases, pulmonary hypertension, or (chronic) pulmonary embolism, which also lead to inhomogeneity in pulmonary capillary blood distribution. Several magnetic resonance imaging (MRI) techniques either dependent on exogenous contrast materials, exploiting periodical lung signal variations with cardiac action, or relying on intrinsic lung voxel attributes have been demonstrated to visualize lung perfusion. Additional post-processing may add temporal information and provide quantitative information related to blood flow. The most widely used and robust technique, dynamic-contrast enhanced MRI, is available in clinical routine assessment of COPD, CF, and pulmonary vascular disease. Non-contrast techniques are important research tools currently requiring clinical validation and cross-correlation in the absence of a viable standard of reference. First data on many of these techniques in the context of observational studies assessing therapy effects have just become available. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 5.

Elexacaftor/tezacaftor/ivacaftor improves chronic rhinosinusitis detected by magnetic resonance imaging in children with cystic fibrosis on long-term therapy with lumacaftor/ivacaftor

INTRODUCTION

Previous studies using magnetic resonance imaging (MRI) demonstrated early onset and progression of chronic rhinosinusitis (CRS) from infancy to school age, and response to lumacaftor/ivacaftor (LUM/IVA) therapy in children with cystic fibrosis (CF). However, the effect of elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA) on CRS detected by MRI in children with CF and at least one F508del mutation, and potential incremental effects of ELX/TEZ/IVA compared to LUM/IVA in F508del homozygous children have not been studied.

METHODS

30 children with CF with at least one F508del mutation underwent three longitudinal paranasal sinus MRI before (MRI1), without (n = 16) or with LUM/IVA therapy (n = 14, MRI2), and with ELX/TEZ/IVA therapy (MRI3, mean age at therapy initiation 11.1 ± 3.4y, range 6-16y). MRI were evaluated using the CRS-MRI score.

RESULTS

After therapy initiation with ELX/TEZ/IVA, the prevalence and in maxillary and sphenoid sinuses the dominance of mucopyoceles decreased (35% vs. 0 %, p<0.001 and 26% vs. 8 %, p < 0.05, respectively). This leads to a reduction in mucopyocele subscore (-3.4 ± 1.9, p < 0.001), and sinus subscores in MRI3 (maxillary sinus: -5.3 ± 3.1, p < 0.001, frontal sinus: -1.0 ± 1.9, p < 0.01, sphenoid subscore: -2.8 ± 3.5, p < 0.001, ethmoid sinus: -1.7 ± 1.9, p < 0.001). The CRS-MRI sum score decreased after therapy initiation with ELX/TEZ/IVA by -9.6 ± 5.5 score points (p < 0.001). The strength in reduction of mucopyoceles subscore and CRS-MRI sum score was independent of a pretreatment with LUM/IVA from MRI1-MRI2 (p = 0.275-0.999).

CONCLUSIONS

ELX/TEZ/IVA therapy leads to improvement of CRS in eligible children with CF. Our data support the role of MRI for comprehensive monitoring of CRS disease severity and response to therapy in children with CF.

Magnetic Resonance Imaging of Pulmonary and Paranasal Sinus Abnormalities in Children with Primary Ciliary Dyskinesia Compared to Children with Cystic Fibrosis

Rationale: Primary ciliary dyskinesia (PCD) and cystic fibrosis (CF) are characterized by inherited impaired mucociliary clearance leading to chronic progressive lung disease as well as chronic rhinosinusitis (CRS). The diseases share morphological and functional commonalities on magnetic resonance imaging (MRI) of the lungs and paranasal sinuses, but comparative MRI studies are lacking. Objectives: To determine whether PCD shows different associations of pulmonary and paranasal sinus abnormalities on MRI and lung function test results in children (infants to adolescents) compared with children with CF. Methods: Eighteen children with PCD (median age, 9.5 [IQR, 3.4-12.7] yr; range, 0-18 yr) and 36 age-matched CF transmembrane conductance regulator modulator-naive children with CF (median age, 9.4 [3.4-13.2] yr; range, 0-18 yr) underwent same-session chest and paranasal sinus MRI as well as spirometry (to determine forced expiratory volume in 1 s percent predicted) and multiple-breath washout (to determine lung clearance index z-score). Pulmonary and paranasal sinus abnormalities were assessed using previously validated chest MRI and CRS-MRI scoring systems. Results: Mean chest MRI global score was similar in children with PCD and CF (15.0 [13.5-20.8] vs. 15.0 [9.0-15.0]; P = 0.601). Consolidations were more prevalent and severe in children with PCD (56% vs. 25% and 1.0 [0.0-2.8] vs. 0.0 [0.0-0.3], respectively; P < 0.05). The chest MRI global score correlated moderately with forced expiratory volume in 1 second percent predicted in children with PCD and children with CF (r = -0.523 and -0.687; P < 0.01) and with lung clearance index in children with CF (r = 0.650; P < 0.001) but not in PCD (r = 0.353; P = 0.196). CRS-MRI sum score and mucopyocele subscore were lower in children with PCD than in children with CF (27.5 [26.3-32.0] vs. 37.0 [37.8-40.0] and 2.0 [0.0-2.0] vs. 7.5 [4.8-9.0], respectively; P < 0.01). CRS-MRI sum score did not correlate with chest MRI score in PCD (r = 0.075-0.157; P = 0.557-0.788) but correlated moderately with MRI morphology score in CF (r = 0.437; P < 0.01). Conclusions: MRI detects differences in lung and paranasal sinus abnormalities between children with PCD and those with CF. Lung disease does not correlate with CRS in PCD but correlates in CF.

[Chronic rhinosinusitis in people with cystic fibrosis-an up-to-date review from the perspective of otorhinolaryngology]

BACKGROUND

Cystic fibrosis (CF) is a complex systemic disease involving numerous organ systems. With improved treatment options and increasing life expectancy of persons with CF (PwCF), extrapulmonary manifestations are coming increasingly into the focus. From birth, almost all PwCF have radiologically detectable pathologies in the upper airways attributable to CF-associated chronic rhinosinusitis (CF-CRS).

OBJECTIVE

The aim of this work is to provide an up-to-date overview of CF-CRS from the otorhinolaryngology perspective and to provide the reader with background knowledge and current developments.

PATHOPHYSIOLOGY

The cystic fibrosis transmembrane conductance regulator (CFTR) gene defect leads to increased viscosity of sinonasal secretions and reduced mucociliary clearance, causing chronic infection and inflammation in the upper airway segment and, consequently, to CF-CRS.

CLINICAL PICTURE AND DIAGNOSTICS

The clinical picture of CF-CRS comprises a wide spectrum from asymptomatic to symptomatic courses. CF-CRS is diagnosed clinically and radiologically.

THERAPY

Sinonasal saline irrigation is recommended as a conservative treatment measure. Topical corticosteroids are also commonly used. Surgical therapy is reserved for highly symptomatic treatment-refractory patients without a sufficient response to conservative treatment including CFTR modulator (CFTRm) therapies. Depending on the CFTR mutation, CFTRm therapies are the treatment of choice. They not only improve the pulmonary and gastrointestinal manifestations in PwCF, but also have positive effects on CF-CRS.

CONCLUSION

The ENT specialist is part of the interdisciplinary team caring for PwCF. Depending on symptom burden and treatment responsiveness, CF-CRS should be treated conservatively and/or surgically. Modern CFTRm have a positive effect on the clinical course of CF-CRS.

Characterization of transient and progressive pulmonary fibrosis by spatially correlated phase contrast microCT, classical histopathology and atomic force microscopy

Pulmonary fibrosis (PF) is a severe and progressive condition in which the lung becomes scarred over time resulting in pulmonary function impairment. Classical histopathology remains an important tool for micro-structural tissue assessment in the diagnosis of PF. A novel workflow based on spatial correlated propagation-based phase-contrast micro computed tomography (PBI-microCT), atomic force microscopy (AFM) and histopathology was developed and applied to two different preclinical mouse models of PF - the commonly used and well characterized Bleomycin-induced PF and a novel mouse model for progressive PF caused by conditional Nedd4-2 KO. The aim was to integrate structural and mechanical features from hallmarks of fibrotic lung tissue remodeling. PBI-microCT was used to assess structural alteration in whole fixed and paraffin embedded lungs, allowing for identification of fibrotic foci within the 3D context of the entire organ and facilitating targeted microtome sectioning of planes of interest for subsequent histopathology. Subsequently, these sections of interest were subjected to AFM to assess changes in the local tissue stiffness of previously identified structures of interest. 3D whole organ analysis showed clear morphological differences in 3D tissue porosity between transient and progressive PF and control lungs. By integrating the results obtained from targeted AFM analysis, it was possible to discriminate between the Bleomycin model and the novel conditional Nedd4-2 KO model using agglomerative cluster analysis. As our workflow for 3D spatial correlation of PBI, targeted histopathology and subsequent AFM is tailored around the standard procedure of formalin-fixed paraffin-embedded (FFPE) tissue specimens, it may be a powerful tool for the comprehensive tissue assessment beyond the scope of PF and preclinical research.

Echo time-dependent observed T1 and quantitative perfusion in chronic obstructive pulmonary disease using magnetic resonance imaging

Introduction

Due to hypoxic vasoconstriction, perfusion is interesting in the lungs. Magnetic Resonance Imaging (MRI) perfusion imaging based on Dynamic Contrast Enhancement (DCE) has been demonstrated in patients with Chronic Obstructive Pulmonary Diseases (COPD) using visual scores, and quantification methods were recently developed further. Inter-patient correlations of echo time-dependent observed T1 [T1(TE)] have been shown with perfusion scores, pulmonary function testing, and quantitative computed tomography. Here, we examined T1(TE) quantification and quantitative perfusion MRI together and investigated both inter-patient and local correlations between T1(TE) and quantitative perfusion.

Methods

22 patients (age 68.0 ± 6.2) with COPD were examined using morphological MRI, inversion recovery multi-echo 2D ultra-short TE (UTE) in 1-2 slices for T1(TE) mapping, and 4D Time-resolved angiography With Stochastic Trajectories (TWIST) for DCE. T1(TE) maps were calculated from 2D UTE at five TEs from 70 to 2,300 μs. Pulmonary Blood Flow (PBF) and perfusion defect (QDP) maps were produced from DCE measurements. Lungs were automatically segmented on UTE images and morphological MRI and these segmentations registered to DCE images. DCE images were separately registered to UTE in corresponding slices and divided into corresponding subdivisions. Spearman's correlation coefficients were calculated for inter-patient correlations using the entire segmented slices and for local correlations separately using registered images and subdivisions for each TE. Median T1(TE) in normal and defect areas according to QDP maps were compared.

Results

Inter-patient correlations were strongest on average at TE2 = 500 μs, reaching up to |ρ| = 0.64 for T1 with PBF and |ρ| = 0.76 with QDP. Generally, local correlations of T1 with PBF were weaker at TE2 than at TE1 or TE3 and with maximum values of |ρ| = 0.66 (from registration) and |ρ| = 0.69 (from subdivision). In 18 patients, T1 was shorter in defect areas than in normal areas, with the relative difference smallest at TE2.

Discussion

The inter-patient correlations of T1 with PBF and QDP found show similar strength and TE-dependence as those previously reported for visual perfusion scores and quantitative computed tomography. The local correlations and median T1 suggest that not only base T1 but also the TE-dependence of observed T1 in normal areas is closer to that found previously in healthy volunteers than in defect areas.

Simultaneous T1, T2 and T2⁎ mapping of the liver with multi-shot MI-SAGE

PURPOSE

To apply multi-shot high-resolution multi inversion spin and gradient echo (MI-SAGE) acquisition for simultaneous liver T1, T2 and T2* mapping.

METHODS

Inversion prepared spin- and gradient-echo EPI was developed with ascending slice order across measurements for efficient acquisition with T1, T2, and T2⁎ weighting. Multi-shot EPI was also implemented to minimize distortion and blurring while enabling high in-plane resolution. A dictionary-matching approach was used to fit the images to quantitative parameter maps, which were compared to T1 measured by modified Look-Locker (MOLLI), T1 measured by variable flip angle (VFA), T2 measured by multiple echo time-based Half Fourier Single-shot Turbo spin-Echo (HASTE), T2 measured by radial turbo-spin-echo (rTSE) and T2⁎ measured by multiple gradient echo (MGRE) sequences.

RESULTS

The multi-shot variant of the sequence achieved higher in-plane resolution of 1.7 × 1.7 mm2 with good image quality in 28 s. Derived quantitative maps showed comparable values to conventional mapping methods. As measured in phantom and in vivo, MOLLI, MESE and MGRE give closest values to MISAGE. VFA, HASTE and rTSE show obvious overestimation.

CONCLUSIONS

The proposed multi-shot inversion prepared spin- and gradient-echo EPI sequence allows for high-resolution quantitative T1, T2 and T2 liver tissue characterization in a single breath-hold scan.

Reanalysis of N2-lung clearance index and the comparison to SF6-lung clearance index and magnetic resonance imaging

Since the finding and correction of an error in previous spiroware software versions commonly used with the Exhalyzer D for multiple-breath washout (MBW) analysis, there has been an ongoing discussion about its impact on MBW results. In this study, we reanalyzed previously published findings with the corrected spiroware version 3.3.1. In total, 31 infants and preschool children with cystic fibrosis (CF) (mean age 2.3 ± 0.8 years) and 20 healthy controls (mean age 2.3 ± 1.1 years) underwent consecutive sulfure hexafluoride (SF6)- and nitrogen (N2)-MBW. In addition, children with CF underwent chest magnetic resonance imaging (MRI) on the same day. After reanalysis of MBW data, the corrected N2-lung clearance index (LCI) decreased by 10-15% in both groups (P = 0.001) but remained significantly higher than the SF6-LCI (P<0.01). Diagnostic agreement between the MBW results remained moderate with a persistent correlation between SF6- and N2-MBW. The corrected upper limit of normal of the N2-LCI changed classification of nine children with CF, eight of which were within the normal range after correction. The correlation between the different LCI values and the chest MRI scores remained significant with strongest correlation with the MRI perfusion score. Consequently, the corrected N2-LCI is significantly lower than the previous N2-LCI, but key results published before are not affected by the reanalysis.

Elexacaftor/Tezacaftor/Ivacaftor Improves Bronchial Artery Dilatation Detected by Magnetic Resonance Imaging in Patients with Cystic Fibrosis

Rationale: Magnetic resonance imaging (MRI) detects improvements in mucus plugging and bronchial wall thickening, but not in lung perfusion in patients with cystic fibrosis (CF) treated with elexacaftor/tezacaftor/ivacaftor (ETI). Objectives: To determine whether bronchial artery dilatation (BAD), a key feature of advanced lung disease, indicates irreversibility of perfusion abnormalities and whether BAD could be reversed in CF patients treated with ETI. Methods: A total of 59 adults with CF underwent longitudinal chest MRI, including magnetic resonance angiography twice, comprising 35 patients with CF (mean age, 31 ± 7 yr) before (MRI1) and after (MRI2) at least 1 month (mean duration, 8 ± 4 mo) on ETI therapy and 24 control patients with CF (mean age, 31 ± 7 yr) without ETI. MRI was assessed using the validated chest MRI score, and the presence and total lumen area of BAD were assessed with commercial software. Results: The MRI global score was stable in the control group from MRI1 to MRI2 (mean difference, 1.1 [-0.3, 2.4]; P = 0.054), but it was reduced in the ETI group (-10.1 [-0.3, 2.4]; P < 0.001). In the control and ETI groups, BAD was present in almost all patients at baseline (95% and 94%, respectively), which did not change at MRI2. The BAD total lumen area did not change in the control group from MRI1 to MRI2 (1.0 mm2 [-0.2, 2.2]; P = 0.099) but decreased in the ETI group (-7.0 mm2 [-8.9, -5.0]; P < 0.001). This decrease correlated with improvements in the MRI global score (r = 0.540; P < 0.001). Conclusions: Our data show that BAD may be partially reversible under ETI therapy in adult patients with CF who have established disease.

[Magnetic resonance imaging of the lung : State of the art]

Due to the low proton density of the lung parenchyma and the rapid signal decay at the air-tissue interfaces, for a long time the lungs were difficult to access using magnetic resonance imaging (MRI); however, technical advances could address most of these obstacles. Pulmonary alterations associated with tissue proliferation ("plus pathologies"), can now be detected with high diagnostic accuracy because of the locally increased proton density. Compared to computed tomography (CT), MRI provides a comprehensive range of functional imaging procedures (respiratory mechanics, perfusion and ventilation). In addition, as a radiation-free noninvasive examination modality, it enables repeated examinations for assessment of the course or monitoring of the effects of treatment, even in children. This article discusses the technical aspects, gives suggestions for protocols and explains the role of MRI of the lungs in the routine assessment of various diseases.

Influence of CT dose reduction on AI-driven malignancy estimation of incidental pulmonary nodules

OBJECTIVES

The purpose of this study was to determine the influence of dose reduction on a commercially available lung cancer prediction convolutional neuronal network (LCP-CNN).

METHODS

CT scans from a cohort provided by the local lung cancer center (n = 218) with confirmed pulmonary malignancies and their corresponding reduced dose simulations (25% and 5% dose) were subjected to the LCP-CNN. The resulting LCP scores (scale 1-10, increasing malignancy risk) and the proportion of correctly classified nodules were compared. The cohort was divided into a low-, medium-, and high-risk group based on the respective LCP scores; shifts between the groups were studied to evaluate the potential impact on nodule management. Two different malignancy risk score thresholds were analyzed: a higher threshold of ≥ 9 ("rule-in" approach) and a lower threshold of > 4 ("rule-out" approach).

RESULTS

In total, 169 patients with 196 nodules could be included (mean age ± SD, 64.5 ± 9.2 year; 49% females). Mean LCP scores for original, 25% and 5% dose levels were 8.5 ± 1.7, 8.4 ± 1.7 (p > 0.05 vs. original dose) and 8.2 ± 1.9 (p < 0.05 vs. original dose), respectively. The proportion of correctly classified nodules with the "rule-in" approach decreased with simulated dose reduction from 58.2 to 56.1% (p = 0.34) and to 52.0% for the respective dose levels (p = 0.01). For the "rule-out" approach the respective values were 95.9%, 96.4%, and 94.4% (p = 0.12). When reducing the original dose to 25%/5%, eight/twenty-two nodules shifted to a lower, five/seven nodules to a higher malignancy risk group.

CONCLUSION

CT dose reduction may affect the analyzed LCP-CNN regarding the classification of pulmonary malignancies and potentially alter pulmonary nodule management.

CLINICAL RELEVANCE STATEMENT

Utilization of a "rule-out" approach with a lower malignancy risk threshold prevents underestimation of the nodule malignancy risk for the analyzed software, especially in high-risk cohorts.

KEY POINTS

• LCP-CNN may be affected by CT image parameters such as noise resulting from low-dose CT acquisitions. • CT dose reduction can alter pulmonary nodule management recommendations by affecting the outcome of the LCP-CNN. • Utilization of a lower malignancy risk threshold prevents underestimation of pulmonary malignancies in high-risk cohorts.

Qualitative and quantitative evaluation of computed tomography changes in adults with cystic fibrosis treated with elexacaftor-tezacaftor-ivacaftor: a retrospective observational study

Introduction: The availability of highly effective triple cystic fibrosis transmembrane conductance regulator (CFTR) modulator combination therapy with elexacaftor-tezacaftor-ivacaftor (ETI) has improved pulmonary outcomes and quality of life of people with cystic fibrosis (pwCF). The aim of this study was to assess computed tomography (CT) changes under ETI visually with the Brody score and quantitatively with dedicated software, and to correlate CT measures with parameters of clinical response. Methods: Twenty two adult pwCF with two consecutive CT scans before and after ETI treatment initiation were retrospectively included. CT was assessed visually employing the Brody score and quantitatively by YACTA, a well-evaluated scientific software computing airway dimensions and lung parenchyma with wall percentage (WP), wall thickness (WT), lumen area (LA), bronchiectasis index (BI), lung volume and mean lung density (MLD) as parameters. Changes in CT metrics were evaluated and the visual and quantitative parameters were correlated with each other and with clinical changes in sweat chloride concentration, spirometry [percent predicted of forced expiratory volume in one second (ppFEV1)] and body mass index (BMI). Results: The mean (SD) Brody score improved with ETI [55 (12) vs. 38 (15); p < 0.001], incl. sub-scores for mucus plugging, peribronchial thickening, and parenchymal changes (all p < 0.001), but not for bronchiectasis (p = 0.281). Quantitatve WP (p < 0.001) and WT (p = 0.004) were reduced, conversely LA increased (p = 0.003), and BI improved (p = 0.012). Lung volume increased (p < 0.001), and MLD decreased (p < 0.001) through a reduction of ground glass opacity areas (p < 0.001). Changes of the Brody score correlated with those of quantitative parameters, exemplarily WT with the sub-score for mucus plugging (r = 0.730, p < 0.001) and peribronchial thickening (r = 0.552, p = 0.008). Changes of CT parameters correlated with those of clinical response parameters, in particular ppFEV1 with the Brody score (r = -0.606, p = 0.003) and with WT (r = -0.538, p = 0.010). Discussion: Morphological treatment response to ETI can be assessed using the Brody score as well as quantitative CT parameters. Changes in CT correlated with clinical improvements. The quantitative analysis with YACTA proved to be an objective, reproducible and simple method for monitoring lung disease, particularly with regard to future interventional clinical trials.

[Patient-centered, value-based management of incidental findings in radiology]

As a byproduct of the increased use of high-resolution radiological imaging, the prevalence of incidental findings (IFs) has been increasing for years. The discovery of an incidental finding can allow early treatment of a potentially health-threatening disease and thus decisively change the course of the disease. However, many incidental findings are of low risk with little or no health impact, and yet their discovery often leads to a cascade of additional investigations. It is undisputed that incidental findings can have a direct impact on the life of the person and that not only psychosocial aspects such as worries and anxiety due to false-positive findings play a role, but that insurance, legal or professional problems can also occur under certain circumstances, which is why the correct handling of incidental findings and the accompanying ethical challenges that apply to them regularly give rise to discussions. General principles to consider when managing incidental findings are responsibility for the well-being of the patient/study participant and of society. In order to avoid overdiagnosis and overtreatment and to achieve high patient benefit, radiologists and clinicians must know how to properly deal with IFs. In recent years, various national and international societies have published important guidelines ("white papers") on how to deal with the management of IFs. It is important that radiologists are fully aware of and follow these guidelines and are also available to referring physicians for further discussions and advice. The most important fact is that the well-being of the patient must always be at the center of all decisions.

"Will I change nodule management recommendations if I change my CAD system?"-impact of volumetric deviation between different CAD systems on lesion management

OBJECTIVES

To evaluate and compare the measurement accuracy of two different computer-aided diagnosis (CAD) systems regarding artificial pulmonary nodules and assess the clinical impact of volumetric inaccuracies in a phantom study.

METHODS

In this phantom study, 59 different phantom arrangements with 326 artificial nodules (178 solid, 148 ground-glass) were scanned at 80 kV, 100 kV, and 120 kV. Four different nodule diameters were used: 5 mm, 8 mm, 10 mm, and 12 mm. Scans were analyzed by a deep-learning (DL)-based CAD and a standard CAD system. Relative volumetric errors (RVE) of each system vs. ground truth and the relative volume difference (RVD) DL-based vs. standard CAD were calculated. The Bland-Altman method was used to define the limits of agreement (LOA). The hypothetical impact on LungRADS classification was assessed for both systems.

RESULTS

There was no difference between the three voltage groups regarding nodule volumetry. Regarding the solid nodules, the RVE of the 5-mm-, 8-mm-, 10-mm-, and 12-mm-size groups for the DL CAD/standard CAD were 12.2/2.8%, 1.3/ - 2.8%, - 3.6/1.5%, and - 12.2/ - 0.3%, respectively. The corresponding values for the ground-glass nodules (GGN) were 25.6%/81.0%, 9.0%/28.0%, 7.6/20.6%, and 6.8/21.2%. The mean RVD for solid nodules/GGN was 1.3/ - 15.2%. Regarding the LungRADS classification, 88.5% and 79.8% of all solid nodules were correctly assigned by the DL CAD and the standard CAD, respectively. 14.9% of the nodules were assigned differently between the systems.

CONCLUSIONS

Patient management may be affected by the volumetric inaccuracy of the CAD systems and hence demands supervision and/or manual correction by a radiologist.

KEY POINTS

• The DL-based CAD system was more accurate in the volumetry of GGN and less accurate regarding solid nodules than the standard CAD system. • Nodule size and attenuation have an effect on the measurement accuracy of both systems; tube voltage has no effect on measurement accuracy. • Measurement inaccuracies of CAD systems can have an impact on patient management, which demands supervision by radiologists.

Effects of Lumacaftor/Ivacaftor on Cystic Fibrosis Disease Progression in Children 2 through 5 Years of Age Homozygous for F508del-CFTR: A Phase 2 Placebo-controlled Clinical Trial

Rationale: Lumacaftor/ivacaftor (LUM/IVA) was shown to be safe and well tolerated in children 2 through 5 years of age with cystic fibrosis (CF) homozygous for F508del-CFTR in a Phase 3 open-label study. Improvements in sweat chloride concentration, markers of pancreatic function, and lung clearance index2.5 (LCI2.5), along with increases in growth parameters, suggested the potential for early disease modification with LUM/IVA treatment. Objective: To further assess the effects of LUM/IVA on CF disease progression in children 2 through 5 years of age using chest magnetic resonance imaging (MRI). Methods: This Phase 2 study had two parts: a 48-week, randomized, double-blind, placebo-controlled treatment period in which children 2 through 5 years of age with CF homozygous for F508del-CFTR received either LUM/IVA or placebo (Part 1) followed by an open-label period in which all children received LUM/IVA for an additional 48 weeks (Part 2). The results from Part 1 are reported. The primary endpoint was absolute change from baseline in chest MRI global score at Week 48. Secondary endpoints included absolute change in LCI2.5 through Week 48 and absolute changes in weight-for-age, stature-for-age, and body mass index-for-age z-scores at Week 48. Additional endpoints included absolute changes in sweat chloride concentration, fecal elastase-1 levels, serum immunoreactive trypsinogen, and fecal calprotectin through Week 48. The primary endpoint was analyzed using Bayesian methods, where the actual Bayesian posterior probability of LUM/IVA being superior to placebo in the chest MRI global score at Week 48 was calculated using a vague normal prior distribution; secondary and additional endpoints were analyzed using descriptive summary statistics. Results: Fifty-one children were enrolled and received LUM/IVA (n = 35) or placebo (n = 16). For the change in chest MRI global score at Week 48, the Bayesian posterior probability of LUM/IVA being better than placebo (treatment difference, <0; higher score indicates greater abnormality) was 76%; the mean treatment difference was -1.5 (95% credible interval, -5.5 to 2.6). Treatment with LUM/IVA also led to within-group numerical improvements in LCI2.5, growth parameters, and biomarkers of pancreatic function as well as greater decreases in sweat chloride concentration compared with placebo from baseline through Week 48. Safety data were consistent with the established safety profile of LUM/IVA. Conclusions: This placebo-controlled study suggests the potential for early disease modification with LUM/IVA treatment, including that assessed by chest MRI, in children as young as 2 years of age. Clinical trial registered with www.clinicaltrials.gov (NCT03625466).

MRI Compared with Low-Dose CT for Incidental Lung Nodule Detection in COPD: A Multicenter Trial

Purpose

To investigate morphofunctional chest MRI for the detection and management of incidental pulmonary nodules in participants with chronic obstructive pulmonary disease (COPD).

Materials and Methods

In this prospective study, 567 participants (mean age, 66 years ± 9 [SD]; 340 men) underwent same-day contrast-enhanced MRI and nonenhanced low-dose CT (LDCT) in a nationwide multicenter trial (clinicaltrials.gov: NCT01245933). Nodule dimensions, morphologic features, and Lung Imaging Reporting and Data System (Lung-RADS) category were assessed at MRI by two blinded radiologists, and consensual LDCT results served as the reference standard. Comparisons were performed using the Student t test, and agreements were assessed using the Cohen weighted κ.

Results

A total of 525 nodules larger than 3 mm in diameter were detected at LDCT in 178 participants, with a mean diameter of 7.2 mm ± 6.1 (range, 3.1-63.1 mm). Nodules were not detected in the remaining 389 participants. Sensitivity and positive predictive values with MRI for readers 1 and 2, respectively, were 63.0% and 84.8% and 60.2% and 83.9% for solid nodules (n = 495), 17.6% and 75.0% and 17.6% and 60.0% for part-solid nodules (n = 17), and 7.7% and 100% and 7.7% and 50.0% for ground-glass nodules (n = 13). For nodules 6 mm or greater in diameter, sensitivity and positive predictive values were 73.3% and 92.2% for reader 1 and 71.4% and 93.2% for reader 2, respectively. Readers underestimated the long-axis diameter at MRI by 0.5 mm ± 1.7 (reader 1) and 0.5 mm ± 1.5 (reader 2) compared with LDCT (P < .001). For Lung-RADS categorization per nodule using MRI, there was substantial to perfect interreader agreement (κ = 0.75-1.00) and intermethod agreement compared with LDCT (κ = 0.70-1.00 and 0.69-1.00).

Conclusion

In a multicenter setting, morphofunctional MRI showed moderate sensitivity for detection of incidental pulmonary nodules in participants with COPD but high agreement with LDCT for Lung-RADS classification of nodules.Clinical trial registration no. NCT01245933 and NCT02629432Keywords: MRI, CT, Thorax, Lung, Chronic Obstructive Pulmonary Disease, Screening© RSNA, 2023 Supplemental material is available for this article.

High resolution propagation-based lung imaging at clinically relevant X-ray dose levels

Absorption-based clinical computed tomography (CT) is the current imaging method of choice in the diagnosis of lung diseases. Many pulmonary diseases are affecting microscopic structures of the lung, such as terminal bronchi, alveolar spaces, sublobular blood vessels or the pulmonary interstitial tissue. As spatial resolution in CT is limited by the clinically acceptable applied X-ray dose, a comprehensive diagnosis of conditions such as interstitial lung disease, idiopathic pulmonary fibrosis or the characterization of small pulmonary nodules is limited and may require additional validation by invasive lung biopsies. Propagation-based imaging (PBI) is a phase sensitive X-ray imaging technique capable of reaching high spatial resolutions at relatively low applied radiation dose levels. In this publication, we present technical refinements of PBI for the characterization of different artificial lung pathologies, mimicking clinically relevant patterns in ventilated fresh porcine lungs in a human-scale chest phantom. The combination of a very large propagation distance of 10.7 m and a photon counting detector with [Formula: see text] pixel size enabled high resolution PBI CT with significantly improved dose efficiency, measured by thermoluminescence detectors. Image quality was directly compared with state-of-the-art clinical CT. PBI with increased propagation distance was found to provide improved image quality at the same or even lower X-ray dose levels than clinical CT. By combining PBI with iodine k-edge subtraction imaging we further demonstrate that, the high quality of the calculated iodine concentration maps might be a potential tool for the analysis of lung perfusion in great detail. Our results indicate PBI to be of great value for accurate diagnosis of lung disease in patients as it allows to depict pathological lesions non-invasively at high resolution in 3D. This will especially benefit patients at high risk of complications from invasive lung biopsies such as in the setting of suspected idiopathic pulmonary fibrosis (IPF).

Reproducibility of pulmonary magnetic resonance angiography in adults with muco-obstructive pulmonary disease

BACKGROUND

Recent studies support magnetic resonance angiography (MRA) as a diagnostic tool for pulmonary arterial disease.

PURPOSE

To determine MRA image quality and reproducibility, and the dependence of MRA image quality and reproducibility on disease severity in patients with chronic obstructive pulmonary disease (COPD) and cystic fibrosis (CF).

MATERIAL AND METHODS

Twenty patients with COPD (mean age 66.5 ± 8.9 years; FEV1% = 42.0 ± 13.3%) and 15 with CF (mean age 29.3 ± 9.3 years; FEV1% = 66.6 ± 15.8%) underwent morpho-functional chest magnetic resonance imaging (MRI) including time-resolved MRA twice one month apart (MRI1, MRI2), and COPD patients underwent non-contrast computed tomography (CT). Image quality was assessed visually using standardized subjective 5-point scales. Contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) were measured by regions of interest. Disease severity was determined by spirometry, a well-evaluated chest MRI score, and by computational CT emphysema index (EI) for COPD.

RESULTS

Subjective image quality was diagnostic for all MRA at MRI1 and MRI2 (mean score = 4.7 ± 0.6). CNR and SNR were 4 43.8 ± 8.7 and 50.5 ± 8.7, respectively. Neither image quality score nor CNR or SNR correlated with FEV1% or chest MRI score for COPD and CF (r = 0.239-0.248). CNR and SNR did not change from MRI1 to MRI2 (P = 0.434-0.995). Further, insignificant differences in CNR and SNR between MRA at MRI1 and MRI2 did not correlate with FEV1% nor chest MRI score in COPD and CF (r = -0.238-0.183), nor with EI in COPD (r = 0.100-0.111).

CONCLUSION

MRA achieved diagnostic quality in COPD and CF patients and was highly reproducible irrespective of disease severity. This supports MRA as a robust alternative to CT in patients with underlying muco-obstructive lung disease.

Magnetic resonance imaging-based scoring of the diseased lung in the preterm infant with bronchopulmonary dysplasia: UNiforme Scoring of the disEAsed Lung in BPD (UNSEAL BPD)

Neonatal chronic lung disease lacks standardized assessment of lung structural changes. We addressed this clinical need by the development of a novel scoring system [UNSEAL BPD (UNiforme Scoring of the disEAsed Lung in BPD)] using T2-weighted single-shot fast-spin-echo sequences from 3 T MRI in very premature infants with and without bronchopulmonary dysplasia (BPD). Quantification of interstitial and airway remodeling, emphysematous changes, and ventilation inhomogeneity was achieved by consensus scoring on a five-point Likert scale. We successfully identified moderate and severe disease by logistic regression [area under the curve (AUC), 0.89] complemented by classification tree analysis revealing gestational age-specific structural changes. We demonstrated substantial interreader reproducibility (weighted Cohen's κ 0.69) and disease specificity (AUC = 0.91). Our novel MRI score enables the standardized assessment of disease-characteristic structural changes in the preterm lung exhibiting significant potential as a quantifiable endpoint in early intervention clinical trials and long-term disease monitoring.

Magnetic Resonance Imaging Detects Onset and Association with Lung Disease Severity of Bronchial Artery Dilatation in Cystic Fibrosis

Rationale

Bronchial artery dilatation (BAD) is associated with haemoptysis in advanced cystic fibrosis (CF) lung disease. Our aim was to evaluate BAD onset and its association with disease severity by magnetic resonance imaging (MRI).

Materials and Methods

188 CF patients (mean age 13.8±10.6 y, range 1.1–55.2 y) underwent annual chest MRI (median three exams, range one to six), contributing a total of 485 MRI examinations incl. perfusion MRI. Presence of BAD was evaluated by two radiologists in consensus. Disease severity was assessed using the validated MRI score and spirometry (ppFEV1).

Results

MRI demonstrated BAD in 71 (37.8%) CF patients consistently from the first available examination, and further ten (5.3%) patients first developed BAD during surveillance. Mean MRI global score in patients with BAD was 24.5±8.3 compared to 11.8±7.0 without BAD (p<0.001), and ppFEV1was lower in BAD compared to patients without (60.8versus82.0%, respectively, p<0.001). BAD was more prevalent in patients with chronicP. aeruginosainfectionversusin patients without (63.6%versus28.0%, p<0.001). In the ten patients who newly developed BAD the MRI global score increased from 15.1±7.8 before to 22.0±5.4 at first detection of BAD (p<0.05). Youden indices for presence of BAD were 0.57 for age (cut-off 11.2 y), 0.65 for ppFEV1(cut-off 74.2%), and 0.62 for MRI global score (cut-off 15.5) (p<0.001).

Conclusion

MRI detects BAD in patients with CF without radiation exposure. Onset of BAD is associated with increased MRI scores, worse lung function, and chronicP. aeruginosainfection, and may serve as a marker of disease severity.

Long-term effects of lumacaftor/ivacaftor on paranasal sinus abnormalities in children with cystic fibrosis detected with magnetic resonance imaging

Introduction: Chronic rhinosinusitis (CRS) usually presents with nasal congestion, rhinorrhea and anosmia impacts quality of life in cystic fibrosis (CF). Especially mucopyoceles pathognomonic for CRS in CF may cause complications such as spread of infection. Previous studies using magnetic resonance imaging (MRI) demonstrated early onset and progression of CRS from infancy to school age in patients with CF, and mid-term improvements of CRS in preschool and school-age children with CF treated with lumacaftor/ivacaftor for at least 2 months. However, long-term data on treatment effects on paranasal sinus abnomalities in preschool and school-age children with CF are lacking. Methods: 39 children with CF homozygous for F508del (mean age at baseline MRI 5.9 ± 3.0 years, range 1-12 years) underwent MRI before (MRI1) and about 7 months after starting lumacaftor/ivacaftor and then annually (median 3 follow-up MRI, range 1-4) (MRI2-4). MRI were evaluated using the previously evaluated CRS-MRI score with excellent inter-reader agreement. For intraindividual analysis ANOVA mixed-effects analysis including Geisser-Greenhouse correction and Fisher's exact test, and for interindividual group analysis Mann-Whitney test were used. Results: The CRS-MRI sum score at baseline was similar in children starting lumacaftor/ivacaftor in school age and children starting therapy at preschool age (34.6 ± 5.2 vs.32.9 ± 7.8, p = 0.847). Mucopyoceles were the dominant abnormality in both, especially in maxillary sinus (65% and 55%, respectively). In children starting therapy in school age the CRS-MRI sum score decreased longitudinally from MRI1 to MRI2 (-2.1 ± 3.5, p < 0.05), MRI3 (-3.0 ± 3.7, p < 0.01) and MRI4 (-3.6 ± 4.7, p < 0.01), mainly due to a decrease in the mucopyoceles subscore (-1.0 ± 1.5, p = 0.059; -1.2 ± 2.0, p < 0.05; -1.6 ± 1.8, p < 0.01; and -2.6 ± 2.8, p = 0.417, respectively). In children starting lumacaftor/ivacaftor in preschool age, the CRS-MRI sum score remained stable under therapy over all three follow-up MRI (0.6 ± 3.3, p = 0.520; 2.4 ± 7.6, p = 0.994; 2.1 ± 10.5, p > 0.999 and -0.5 ± 0.5, p = 0.740; respectively). Conclusion: Longitudinal paranasal sinus MRI shows improvements in paranasal sinus abnormalities in children with CF starting lumacaftor/ivacaftor therapy at school age. Further, MRI detects a prevention of an increase in paranasal sinus abnormalities in children with CF starting lumacaftor/ivacaftor therapy at preschool age. Our data support the role of MRI for comprehensive non-invasive therapy and disease monitoring of paranasal sinus abnormalities in children with CF.

MDCT-based longitudinal automated airway and air trapping analysis in school-age children with mild cystic fibrosis lung disease

OBJECTIVES

Quantitative computed tomography (QCT) offers some promising markers to quantify cystic fibrosis (CF)-lung disease. Air trapping may precede irreversible bronchiectasis; therefore, the temporal interdependencies of functional and structural lung disease need to be further investigated. We aim to quantify airway dimensions and air trapping on chest CT of school-age children with mild CF-lung disease over two years.

METHODS

Fully-automatic software analyzed 144 serial spirometer-controlled chest CT scans of 36 children (median 12.1 (10.2-13.8) years) with mild CF-lung disease (median ppFEV1 98.5 (90.8-103.3) %) at baseline, 3, 12 and 24 months. The airway wall percentage (WP_5-10), bronchiectasis index (BEI), as well as severe air trapping (A3) were calculated for the total lung and separately for all lobes. Mixed linear models were calculated, considering the lobar distribution of WP_5-10, BEI and A3 cross-sectionally and longitudinally.

RESULTS

WP_5-10 remained stable (P = 0.248), and BEI changed from 0.41 (0.28-0.7) to 0.54 (0.36-0.88) (P = 0.156) and A3 from 2.26% to 4.35% (P = 0.086) showing variability over two years. ppFEV1 was also stable (P = 0.276). A robust mixed linear model showed a cross-sectional, regional association between WP_5-10 and A3 at each timepoint (P < 0.001). Further, BEI showed no cross-sectional, but another mixed model showed short-term longitudinal interdependencies with air trapping (P = 0.003).

CONCLUSIONS

Robust linear/beta mixed models can still reveal interdependencies in medical data with high variability that remain hidden with simpler statistical methods. We could demonstrate cross-sectional, regional interdependencies between wall thickening and air trapping. Further, we show short-term regional interdependencies between air trapping and an increase in bronchiectasis. The data indicate that regional air trapping may precede the development of bronchiectasis. Quantitative CT may capture subtle disease progression and identify regional and temporal interdependencies of distinct manifestations of CF-lung disease.

Validation of the ISGLS classification of bile leakage after pancreatic surgery: A rare but severe complication

INTRODUCTION

Hepaticoenterostomy is an important step of reconstruction during hepatopancreatobiliary (HPB) surgery with a subsequent bile leakage rate of up to 5%. The International Study Group of Liver Surgery (ISGLS) proposed a severity grading system for defining bile leakage after HPB surgery, which has not been validated after pancreatic surgery in a large patient cohort. The present study aimed to validate the ISGLS definition for bile leakage in pancreatic surgery and to investigate the postoperative outcomes of bile leakage after pancreatic resections.

MATERIALS AND METHODS

Data from the prospectively maintained database for pancreas surgery were extracted for any type of pancreatectomy with hepaticoenterostomy between 2006 and 2019. The severity of bile leakage was graded according to the ISGLS definition. The influence of our standardized hepaticoenterostomy technique and of the complexity of the surgical procedure on the rate of clinically relevant bile leakages (B and C) were assessed in three different timeframes.

RESULTS

Bile leakage was detected in 152 of 5,300 patients (2.9%). Clinically relevant bile leakages included seventy patients with grade B and eighty-two patients with grade C bile leakages (46.1% and 53.9%, respectively). During the study period, the overall rate of bile leakage showed to be stable (from 3.5% to 2.4%). Patients with grade C bile leakage had a higher rate of postoperative wound infection (P < 0.001) and longer ICU stays and hospital stays compared to patients with grade B bile leakage (P = 0.03 and P < 0.001 respectively). These parameters were significantly higher in patients with late grade C bile leakage but were similar between patients with grade B bile leakage and early grade C bile leakage (<5th day POD). In the whole patients' cohort, the 90-day mortality rate was 3.2% (174/5,300), with a rate of 25% in patients with bile leakage (38/152).

CONCLUSION

The ISGLS classification is a valid method for classifying postoperative bile leak after pancreas surgery. Standardization of our hepaticoenterostomy technique resulted in a stable rate of bile leakage. Although rare, bile leakage following pancreas surgery is a severe complication that has a major impact on patient outcomes and contributes significantly to morbidity and mortality, even in the absence of POPF.

AI-Supported Comprehensive Detection and Quantification of Biomarkers of Subclinical Widespread Diseases at Chest CT for Preventive Medicine

Automated image analysis plays an increasing role in radiology in detecting and quantifying image features outside of the perception of human eyes. Common AI-based approaches address a single medical problem, although patients often present with multiple interacting, frequently subclinical medical conditions. A holistic imaging diagnostics tool based on artificial intelligence (AI) has the potential of providing an overview of multi-system comorbidities within a single workflow. An interdisciplinary, multicentric team of medical experts and computer scientists designed a pipeline, comprising AI-based tools for the automated detection, quantification and characterization of the most common pulmonary, metabolic, cardiovascular and musculoskeletal comorbidities in chest computed tomography (CT). To provide a comprehensive evaluation of each patient, a multidimensional workflow was established with algorithms operating synchronously on a decentralized Joined Imaging Platform (JIP). The results of each patient are transferred to a dedicated database and summarized as a structured report with reference to available reference values and annotated sample images of detected pathologies. Hence, this tool allows for the comprehensive, large-scale analysis of imaging-biomarkers of comorbidities in chest CT, first in science and then in clinical routine. Moreover, this tool accommodates the quantitative analysis and classification of each pathology, providing integral diagnostic and prognostic value, and subsequently leading to improved preventive patient care and further possibilities for future studies.

Unsupervised clustering algorithms improve the reproducibility of dynamic contrast-enhanced magnetic resonance imaging pulmonary perfusion quantification in muco-obstructive lung diseases

Background

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) allows the assessment of pulmonary perfusion, which may play a key role in the development of muco-obstructive lung disease. One problem with quantifying pulmonary perfusion is the high variability of metrics. Quantifying the extent of abnormalities using unsupervised clustering algorithms in residue function maps leads to intrinsic normalization and could reduce variability.

Purpose

We investigated the reproducibility of perfusion defects in percent (QDP) in clinically stable patients with cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD).

Methods

15 CF (29.3 ± 9.3y, FEV1%predicted = 66.6 ± 15.8%) and 20 COPD (66.5 ± 8.9y, FEV1%predicted = 42.0 ± 13.3%) patients underwent DCE-MRI twice 1 month apart. QDP, pulmonary blood flow (PBF), and pulmonary blood volume (PBV) were computed from residue function maps using an in-house quantification pipeline. A previously validated MRI perfusion score was visually assessed by an expert reader.

Results

Overall, mean QDP, PBF, and PBV did not change within 1 month, except for QDP in COPD (p < 0.05). We observed smaller limits of agreement (± 1.96 SD) related to the median for QDP (CF: ± 38%, COPD: ± 37%) compared to PBF (CF: ± 89%, COPD: ± 55%) and PBV (CF: ± 55%, COPD: ± 51%). QDP correlated moderately with the MRI perfusion score in CF (r = 0.46, p < 0.05) and COPD (r = 0.66, p < 0.001). PBF and PBV correlated poorly with the MRI perfusion score in CF (r =−0.29, p = 0.132 and r =−0.35, p = 0.067, respectively) and moderately in COPD (r =−0.57 and r =−0.57, p < 0.001, respectively).

Conclusion

In patients with muco-obstructive lung diseases, QDP was more robust and showed a higher correlation with the MRI perfusion score compared to the traditionally used perfusion metrics PBF and PBV.

Lung function impairment in the German Lung Cancer Screening Intervention Study (LUSI): prevalence, symptoms, and associations with lung cancer risk, tumor histology and all-cause mortality

Background

Lung cancer screening may provide a favorable opportunity for a spirometry examination, to diagnose participants with undiagnosed lung function impairments, or to improve targeting of computed tomography (CT) screening intensity in view of expected net benefit.

Methods

Spirometry was performed in the CT screening arm (n=2,029) of the German Lung Cancer Screening Intervention Study (LUSI)—a trial examining the effects of annual CT screening on lung cancer mortality, in 50–69-year-old long-term smokers. Participants were classified as having chronic obstructive pulmonary disease (COPD) [forced expiration in one second (FEV₁)/forced vital lung capacity (FVC) <0.7], preserved ratio impaired spirometry (PRISm; FEV₁/FVC ≥0.7 and FEV₁% predicted <80%), or normal spirometry. Descriptive statistics were used to examine associations of COPD or PRISm with respiratory symptoms, and self-reported medical diagnoses of respiratory and other morbidities. Logistic regression and proportional hazards regression were used to examine associations of COPD and PRISm, as well as their self-reported medical diagnoses, with risks of lung cancer and all-cause mortality.

Results

A total of 1,987 screening arm participants (98%) provided interpretable spirometry measurements; of these, 34.3% had spirometric patterns consistent with either COPD (18.6%) or PRISm (15.7%). Two thirds of participants with COPD or PRISm were asymptomatic, and only 23% reported a previous medical diagnosis concordant with COPD. Participants reporting a diagnosis tended to be more often current and heavier smokers, and more often had respiratory symptoms, cardiovascular comorbidities, or more severe lung function impairments. Independently of smoking history, moderate-to-severe (GOLD 2–4) COPD (OR =2.14; 95% CI: 1.54–2.98), and PRISm (OR =2.68; 95% CI: 1.61–4.40), were associated with increased lung cancer risk. Lung cancer patients with PRISm less frequently had adenocarcinomas, and more often squamous cell or small cell tumors, compared to those with normal spirometry (n=45), and both PRISm and COPD were associated with more advanced lung cancer tumor stage for screen-detected cancers. PRISm and COPD, depending on GOLD stage, were also associated with about 2- to 4-fold increases in risk of overall mortality, which to 87 percent had causes other than lung cancer.

Conclusions

About one third of smokers eligible for lung cancer screening in Germany have COPD or PRISm. As these conditions were associated with detection of lung cancer, spirometry may help identify populations at high risk for death of lung cancer or other causes, and who might particularly benefit from CT screening.

COVID-19 pneumonia: Prediction of patient outcome by CT-based quantitative lung parenchyma analysis combined with laboratory parameters

Objectives

To evaluate the prognostic value of fully automatic lung quantification based on spectral computed tomography (CT) and laboratory parameters for combined outcome prediction in COVID-19 pneumonia.

Methods

CT images of 53 hospitalized COVID-19 patients including virtual monochromatic reconstructions at 40-140keV were analyzed using a fully automated software system. Quantitative CT (QCT) parameters including mean and percentiles of lung density, fibrosis index (FIBI_-700, defined as the percentage of segmented lung voxels ≥-700 HU), quantification of ground-glass opacities and well-aerated lung areas were analyzed. QCT parameters were correlated to laboratory and patient outcome parameters (hospitalization, days on intensive care unit, invasive and non-invasive ventilation).

Results

Best correlations were found for laboratory parameters LDH (r = 0.54), CRP (r = 0.49), Procalcitonin (r = 0.37) and partial pressure of oxygen (r = 0.35) with the QCT parameter 75^th percentile of lung density. LDH, Procalcitonin, 75^th percentile of lung density and FIBI-₇₀₀ were the strongest independent predictors of patients’ outcome in terms of days of invasive ventilation. The combination of LDH and Procalcitonin with either 75^th percentile of lung density or FIBI_-700 achieved a r² of 0.84 and 1.0 as well as an area under the receiver operating characteristic curve (AUC) of 0.99 and 1.0 for the prediction of the need of invasive ventilation.

Conclusions

QCT parameters in combination with laboratory parameters could deliver a feasible prognostic tool for the prediction of invasive ventilation in patients with COVID-19 pneumonia.

Effects of Elexacaftor/Tezacaftor/Ivacaftor Therapy on Lung Clearance Index and Magnetic Resonance Imaging in Patients with Cystic Fibrosis and One or Two F508del Alleles

RATIONALE

We recently demonstrated that triple combination CFTR modulator therapy with elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA) improves CFTR function in airway and intestinal epithelia to 40 to 50% of normal in patients with cystic fibrosis (CF) with one or two F508del alleles. In previous studies, this improvement of CFTR function was shown to improve clinical outcomes, however, effects on the lung clearance index (LCI) determined by multiple breath washout and abnormalities in lung morphology and perfusion detected by magnetic resonance imaging (MRI) have not been studied.

OBJECTIVES

To examine the effect of ELX/TEZ/IVA on LCI and lung MRI scores in patients with CF and one or two F508del alleles aged 12 years and older.

METHODS

This prospective, observational, multicenter, post-approval study assessed LCI and lung MRI scores before and 8-16 weeks after initiation of ELX/TEZ/IVA.

MEASUREMENTS AND MAIN RESULTS

A total of 91 patients with CF including 45 heterozygous for F508del and a minimal function mutation (MF) and 46 homozygous for F508del were enrolled in this study. Treatment with ELX/TEZ/IVA improved LCI in F508del/MF (-2.4;IQR, -3.7 - -1.1;P<0.001) and F508del homozygous (-1.4;IQR, -2.4 - -0.4;P<0.001) patients. Further, ELX/TEZ/IVA improved the MRI global score in F508del/MF (-6.0;IQR, -11.0 - -1.3;P<0.001) and F508del homozygous (-6.5;IQR, -11.0 - -1.3;P<0.001) patients.

CONCLUSIONS

Our data demonstrate that improvement of CFTR function by ELX/TEZ/IVA improves lung ventilation and abnormalities in lung morphology including airway mucus plugging and wall thickening in adolescent and adult patients with CF and one or two F508del alleles in a real-world, post-approval setting.

[Chest X-ray: implementation and indication : Recommendations of the thoracic imaging working group of the German Radiological Society]

BACKGROUND

Even after more than 100 years, the chest X‑ray is still an important technique to detect important pathological changes of lungs, heart and vessels in a fast and low-dose manner. For the German-speaking regions, there are only recommendations available published by the "Ständigen Strahlenschutzkommission (SSK)" regarding the indication. These recommendations are not updated on a regular basis and more recent developments are only integrated with delayed.

METHODS

The chest division of the German Radiological Society has summarized their expertise for the usage and indication of the chest X‑ray. Especially within the field of oncology the usage of chest X‑ray is evaluated differently to the aforementioned recommendations; here chest computed tomography (CT) is much more sensitive for evaluation of metastasis and local invasion of tumors. Also, within the area of infectious diseases in non-immunocompetent patients, CT is the method of choice. Based on the structure of the current recommendations, many current guidelines and indications are summarized and presented within the context of the usage of chest X‑ray.

Quantification of pulmonary perfusion abnormalities using DCE-MRI in COPD: comparison with quantitative CT and pulmonary function

Objectives

Pulmonary perfusion abnormalities are prevalent in patients with chronic obstructive pulmonary disease (COPD), are potentially reversible, and may be associated with emphysema development. Therefore, we aimed to evaluate the clinical meaningfulness of perfusion defects in percent (QDP) using DCE-MRI.

Methods

We investigated a subset of baseline DCE-MRIs, paired inspiratory/expiratory CTs, and pulmonary function testing (PFT) of 83 subjects (age = 65.7 ± 9.0 years, patients-at-risk, and all GOLD groups) from one center of the “COSYCONET” COPD cohort. QDP was computed from DCE-MRI using an in-house developed quantification pipeline, including four different approaches: Otsu’s method, k-means clustering, texture analysis, and 80^th percentile threshold. QDP was compared with visual MRI perfusion scoring, CT parametric response mapping (PRM) indices of emphysema (PRM_Emph) and functional small airway disease (PRM_fSAD), and FEV1/FVC from PFT.

Results

All QDP approaches showed high correlations with the MRI perfusion score (r = 0.67 to 0.72, p < 0.001), with the highest association based on Otsu’s method (r = 0.72, p < 0.001). QDP correlated significantly with all PRM indices (p < 0.001), with the strongest correlations with PRM_Emph (r = 0.70 to 0.75, p < 0.001). QDP was distinctly higher than PRM_Emph (mean difference = 35.85 to 40.40) and PRM_fSAD (mean difference = 15.12 to 19.68), but in close agreement when combining both PRM indices (mean difference = 1.47 to 6.03) for all QDP approaches. QDP correlated moderately with FEV1/FVC (r = − 0.54 to − 0.41, p < 0.001).

Conclusion

QDP is associated with established markers of disease severity and the extent corresponds to the CT-derived combined extent of PRM_Emph and PRM_fSAD. We propose to use QDP based on Otsu’s method for future clinical studies in COPD.

Key Points

• QDP quantified from DCE-MRI is associated with visual MRI perfusion score, CT PRM indices, and PFT.

• The extent of QDP from DCE-MRI corresponds to the combined extent of PRM_Emph and PRM_fSAD from CT.

• Assessing pulmonary perfusion abnormalities using DCE-MRI with QDP improved the correlations with CT PRM indices and PFT compared to the quantification of pulmonary blood flow and volume.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00330-021-08229-6.

Magnetic Resonance Imaging Detects Progression of Lung Disease and Impact of Newborn Screening in Preschool Children with Cystic Fibrosis

RATIONALE

Previous cross-sectional studies demonstrated that chest magnetic resonance imaging (MRI) is sensitive to detect early lung disease in infants and preschool children with cystic fibrosis (CF) without radiation exposure. However, the ability of MRI to detect progression of lung disease and the impact of early diagnosis in preschool children with CF remains unknown.

OBJECTIVES

To investigate the potential of MRI to detect progression of early lung disease and impact of early diagnosis by CF newborn screening (NBS) in preschool children with CF.

METHODS

Annual MRI was performed from diagnosis over four years in a cohort of 96 preschool children with CF (age 0-4 yr) that were concurrently diagnosed based on NBS (n=28) or clinical symptoms (n=68). MRI scans were evaluated using a dedicated morphofunctional score and the relationship between longitudinal MRI scores and respiratory symptoms, pulmonary exacerbations, upper airway microbiology and mode of diagnosis were determined.

MEASUREMENTS AND MAIN RESULTS

The MRI global score increased in the total cohort of children with CF during preschool years (P<0.001) which was associated with cough, pulmonary exacerbations (P<0.0001), and detection of Staphylococcus aureus and Haemophilus influenzae (P<0.05). MRI-defined abnormalities in lung morphology, especially airway wall thickening/bronchiectasis, were lower in NBS compared to clinically diagnosed children with CF throughout the observation period (P<0.01).

CONCLUSIONS

MRI detected progression of early lung disease and benefits of early diagnosis by NBS in preschool children with CF. These findings support MRI as sensitive outcome measure for diagnostic monitoring and early intervention trials in preschool children with CF.

Consolidated lung on contrast-enhanced chest CT: the use of spectral-detector computed tomography parameters in differentiating atelectasis and pneumonia

Objectives

To investigate the value of spectral-detector computed tomography (SDCT) parameters for the quantitative differentiation between atelectasis and pneumonia on contrast-enhanced chest CT.

Material and methods

Sixty-three patients, 22 clinically diagnosed with pneumonia and 41 with atelectasis, underwent contrast-enhanced SDCT scans during the venous phase. CT numbers (Hounsfield Units [HU]) were measured on conventional reconstructions (CON_120kVp) and the iodine concentration (C_iodine, [mg/ml]), and effective atomic number (Z_eff) on spectral reconstructions, using region-of-interest (ROI) analysis. Receiver operating characteristics (ROC) and contrast-to-noise ratios (CNRs) were calculated to assess each reconstruction's potential to differentiate between atelectasis and pneumonia.

Results

On contrast-enhanced SDCT, the difference between atelectasis and pneumonia was significant on CON_120kVp, C_iodine, and Z_eff images (p < 0.001). On CON_120kVp images, a threshold of 81 HU achieved a sensitivity of 93 % and a specificity of 95 % for identifying pneumonia, while C_iodine and Z_eff images reached the same sensitivity but lower specificities of 85 % and 83 %. CON_120kVp images showed significantly higher CNRs between normal lung and atelectasis or pneumonia with 30.63 and 27.69 compared to C_iodine images with 3.54 and 1.27 and Z_eff images with 4.22 and 7.63 (p < 0.001). None of the parameters could differentiate atelectasis and pneumonia without contrast media.

Conclusions

Contrast-enhanced SDCT can differentiate atelectasis and pneumonia based on the spectral parameters C_iodine, and Z_eff. However, they had no added value compared to CT number measurement on CON_120kVp images. Furthermore, contrast media is still needed for a differentiation based on quantitative SDCT parameters.

Echo Time-Dependent Observed Lung T1 in Patients With Chronic Obstructive Pulmonary Disease in Correlation With Quantitative Imaging and Clinical Indices

BACKGROUND

There is a clinical need for imaging-derived biomarkers for the management of chronic obstructive pulmonary disease (COPD). Observed pulmonary T₁ (T₁ (TE)) depends on the echo-time (TE) and reflects regional pulmonary function.

PURPOSE

To investigate the potential diagnostic value of T₁ (TE) for the assessment of lung disease in COPD patients by determining correlations with clinical parameters and quantitative CT.

STUDY TYPE

Prospective non-randomized diagnostic study.

POPULATION

Thirty COPD patients (67.7 ± 6.6 years). Data from a previous study (15 healthy volunteers [26.2 ± 3.9 years) were used as reference.

FIELD STRENGTH/SEQUENCE

Study participants were examined at 1.5 T using dynamic contrast-enhanced three-dimensional gradient echo keyhole perfusion sequence and a multi-echo inversion recovery two-dimensional UTE (ultra-short TE) sequence for T₁ (TE) mapping at TE_1-5  = 70 μsec, 500 μsec, 1200 μsec, 1650 μsec, and 2300 μsec.

ASSESSMENT

Perfusion images were scored by three radiologists. T₁ (TE) was automatically quantified. Computed tomography (CT) images were quantified in software (qCT). Clinical parameters including pulmonary function testing were also acquired.

STATISTICAL TESTS

Spearman rank correlation coefficients (ρ) were calculated between T₁ (TE) and perfusion scores, clinical parameters and qCT. A P-value <0.05 was considered statistically significant.

RESULTS

Median values were T₁ (TE_1-5 ) = 644 ± 78 msec, 835 ± 92 msec, 835 ± 87 msec, 831 ± 131 msec, 893 ± 220 msec, all significantly shorter than previously reported in healthy subjects. A significant increase of T₁ was observed from TE₁ to TE₂ , with no changes from TE₂ to TE₃ (P = 0.48), TE₃ to TE₄ (P = 0.94) or TE₄ to TE₅ (P = 0.02) which demonstrates an increase at shorter TEs than in healthy subjects. Moderate to strong Spearman's correlations between T₁ and parameters including the predicted diffusing capacity for carbon monoxide (DLCO, ρ < 0.70), mean lung density (MLD, ρ < 0.72) and the perfusion score (ρ > -0.69) were found. Overall, correlations were strongest at TE₂ , weaker at TE₁ and rarely significant at TE₄ -TE₅ .

DATA CONCLUSION

In COPD patients, the increase of T₁ (TE) with TE occurred at shorter TEs than previously found in healthy subjects. Together with the lack of correlation between T₁ and clinical parameters of disease at longer TEs, this suggests that T₁ (TE) quantification in COPD patients requires shorter TEs. The TE-dependence of correlations implies that T₁ (TE) mapping might be developed further to provide diagnostic information beyond T₁ at a single TE.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY: Stage 1.

Improved detection of air trapping on expiratory computed tomography using deep learning

BACKGROUND

Radiologic evidence of air trapping (AT) on expiratory computed tomography (CT) scans is associated with early pulmonary dysfunction in patients with cystic fibrosis (CF). However, standard techniques for quantitative assessment of AT are highly variable, resulting in limited efficacy for monitoring disease progression.

OBJECTIVE

To investigate the effectiveness of a convolutional neural network (CNN) model for quantifying and monitoring AT, and to compare it with other quantitative AT measures obtained from threshold-based techniques.

MATERIALS AND METHODS

Paired volumetric whole lung inspiratory and expiratory CT scans were obtained at four time points (0, 3, 12 and 24 months) on 36 subjects with mild CF lung disease. A densely connected CNN (DN) was trained using AT segmentation maps generated from a personalized threshold-based method (PTM). Quantitative AT (QAT) values, presented as the relative volume of AT over the lungs, from the DN approach were compared to QAT values from the PTM method. Radiographic assessment, spirometric measures, and clinical scores were correlated to the DN QAT values using a linear mixed effects model.

RESULTS

QAT values from the DN were found to increase from 8.65% ± 1.38% to 21.38% ± 1.82%, respectively, over a two-year period. Comparison of CNN model results to intensity-based measures demonstrated a systematic drop in the Dice coefficient over time (decreased from 0.86 ± 0.03 to 0.45 ± 0.04). The trends observed in DN QAT values were consistent with clinical scores for AT, bronchiectasis, and mucus plugging. In addition, the DN approach was found to be less susceptible to variations in expiratory deflation levels than the threshold-based approach.

CONCLUSION

The CNN model effectively delineated AT on expiratory CT scans, which provides an automated and objective approach for assessing and monitoring AT in CF patients.

Current state of the art MRI for the longitudinal assessment of cystic fibrosis

Pulmonary MRI can now provide high-resolution images that are sensitive to early disease and specific to inflammation in cystic fibrosis (CF) lung disease. With specificity and function limited via computed tomography (CT), there are significant advantages to MRI. Many of the modern MRI techniques can be performed throughout life, and can be employed to understand changes over time, in addition to quantification of treatment response. Proton density and T1 /T2 contrast images can be obtained within a single breath-hold, providing depiction of structural abnormalities and active inflammation. Modern radial and/or spiral ultrashort echo-time (UTE) techniques rival CT in resolution for depiction and quantification of structure, for both airway and parenchymal abnormalities. Contrast perfusion MRI techniques are now utilized routinely to visualize changes in pulmonary and bronchial circulation that routinely occur in CF lung disease, and noncontrast techniques are moving closer to clinical translation. Functional information can be obtained from noncontrast proton images alone, using techniques such as Fourier decomposition. Hyperpolarized-gas MRI, increasingly using 129 Xe, is now becoming more widespread and has been demonstrated to have high sensitivity to early airway obstruction in CF via ventilation MRI. The sensitivity of 129 Xe MRI promises future use in personalized medicine, management of early CF lung disease, and in future clinical trials. By combining structural and functional techniques, with or without hyperpolarized gases, regional structure-function relationships can be obtained, giving insight into the pathophysiology of disease and improved clinical management. This article reviews the modern MRI techniques that can routinely be employed for CF lung disease in nearly any large medical center. Level of Evidence: 4 Technical Efficacy Stage: 5 J. Magn. Reson. Imaging 2019.

[Microvascular changes in COVID-19]

BACKGROUND

Clinically, coronavirus disease 2019 (COVID-19) is associated with a wide range of symptoms, which can range from mild complaints of an upper respiratory infection to life-threatening hypoxic respiratory insufficiency and multiorgan failure.

OBJECTIVE

The initially identified pulmonary damage patterns, such as diffuse alveolar damage in acute lung failure, are accompanied by new findings that draw a more complex scenario. These include microvascular involvement and a wide range of associated pathologies of multiple organ systems. A back-scaling of microstructural vascular changes is possible via targeted correlation of pathological autopsy results with radiological imaging.

MATERIAL AND METHODS

Radiological and pathological correlation as well as microradiological imaging to investigate microvascular involvement in fatal COVID-19.

RESULTS

The cases of two COVID-19 patients are presented. Patient 1 showed a relative hypoperfusion in lung regions that did not have typical COVID-19 infiltrates; the targeted post-mortem correlation also showed subtle signs of microvascular damage even in these lung sections. Patient 2 showed both radiologically and pathologically advanced typical COVID-19 destruction of lung structures and the case illustrates the damage patterns of the blood-air barrier. The perfusion deficit of the intestinal wall shown in computed tomography of patient 2 could not ultimately clearly be microscopically attributed to intestinal microvascular damage.

CONCLUSION

In addition to microvascular thrombosis, our results indicate a functional pulmonary vasodysregulation as part of the pathophysiology during the vascular phase of COVID-19. The clinical relevance of autopsies and the integration of radiological imaging findings into histopathological injury patterns must be emphasized for a better understanding of COVID-19.

Mesopolysaccharides: The extracellular surface layer of visceral organs

The mesothelium is a dynamic and specialized tissue layer that covers the somatic cavities (pleural, peritoneal, and pericardial) as well as the surface of the visceral organs such as the lung, heart, liver, bowel and tunica vaginalis testis. The potential therapeutic manipulation of visceral organs has been complicated by the carbohydrate surface layer-here, called the mesopolysaccharide (MPS)-that coats the outer layer of the mesothelium. The traditional understanding of MPS structure has relied upon fixation techniques known to degrade carbohydrates. The recent development of carbohydrate-preserving fixation for high resolution imaging techniques has provided an opportunity to re-examine the structure of both the MPS and the visceral mesothelium. In this report, we used high pressure freezing (HPF) as well as serial section transmission electron microscopy to redefine the structure of the MPS expressed on the murine lung, heart and liver surface. Tissue preserved by HPF and examined by transmission electron microscopy demonstrated a pleural MPS layer 13.01±1.1 um deep-a 100-fold increase in depth compared to previously reported data obtained with conventional fixation techniques. At the base of the MPS were microvilli 1.1±0.35 um long and 42±5 nm in diameter. Morphological evidence suggested that the MPS was anchored to the mesothelium by microvilli. In addition, membrane pits 97±17 nm in diameter were observed in the apical mesothelial membrane. The spatial proximity and surface density (29±4.5%) of the pits suggested an active process linked to the structural maintenance of the MPS. The striking magnitude and complex structure of the MPS indicates that it is an important consideration in studies of the visceral mesothelium.

Optimizing airway wall segmentation and quantification by reducing the influence of adjacent vessels and intravascular contrast material with a modified integral-based algorithm in quantitative computed tomography

Introduction

Quantitative analysis of multi-detector computed tomography (MDCT) plays an increasingly important role in assessing airway disease. Depending on the algorithms used, airway dimensions may be over- or underestimated, primarily if contrast material was used. Therefore, we tested a modified integral-based method (IBM) to address this problem.

Methods

Temporally resolved cine-MDCT was performed in seven ventilated pigs in breath-hold during iodinated contrast material (CM) infusion over 60s. Identical slices in non-enhanced (NE), pulmonary-arterial (PA), systemic-arterial (SA), and venous phase (VE) were subjected to an in-house software using a standard and a modified IBM. Total diameter (TD), lumen area (LA), wall area (WA), and wall thickness (WT) were measured for ten extra- and six intrapulmonary airways.

Results

The modified IBM significantly reduced TD by 7.6%, LA by 12.7%, WA by 9.7%, and WT by 3.9% compared to standard IBM on non-enhanced CT (p<0.05). Using standard IBM, CM led to a decrease of all airway parameters compared to NE. For example, LA decreased from 80.85±49.26mm² at NE, to 75.14±47.96mm² (-7.1%) at PA (p<0.001), 74.96±48.55mm² (-7.3%) at SA (p<0.001), and to 78.95±48.94mm² (-2.4%) at VE (p = 0.200). Using modified IBM, the differences were reduced to -3.1% at PA, -2.9% at SA and -0.7% at VE (p<0.001; p<0.001; p = 1.000).

Conclusions

The modified IBM can optimize airway wall segmentation and reduce the influence of CM on quantitative CT. This allows a more precise measurement as well as potentially the comparison of enhanced with non-enhanced scans in inflammatory airway disease.