Impact of ultra-high-resolution imaging of the lungs on perceived diagnostic image quality using photon-counting CT.

OBJECTIVES: To compare clinical image quality and perceived impact on diagnostic interpretation of chest CT findings between ultra-high-resolution photon-counting CT (UHR-PCCT) and conventional high-resolution energy-integrating-detector CT (HR-EIDCT) using visual grading analysis (VGA) scores. MATERIALS AND METHODS: Fifty patients who underwent a UHR-PCCT (matrix 512 × 512, 768 × 768, or 1024 × 1024; FOV average 275 × 376 mm, 120 × 0.2 mm; focal spot size 0.6 × 0.7 mm) between November 2021 and February 2022 and with a previous HR-EIDCT within the last 14 months were included. Four readers evaluated central and peripheral airways, lung vasculature, nodules, ground glass opacities, inter- and intralobular lines, emphysema, fissures, bullae/cysts, and air trapping on PCCT (0.4 mm) and conventional EIDCT (1 mm) via side-by-side reference scoring using a 5-point diagnostic quality score. The median VGA scores were compared and tested using one-sample Wilcoxon signed rank tests with hypothesized median values of 0 (same visibility) and 2 (better visibility on PCCT with impact on diagnostic interpretation) at a 2.5% significance level. RESULTS: Almost all lung structures had significantly better visibility on PCCT compared to EIDCT (p < 0.025; exception for ground glass nodules (N = 2/50 patients, p = 0.157)), with the highest scores seen for peripheral airways, micronodules, inter- and intralobular lines, and centrilobular emphysema (mean VGA > 1). Although better visibility, a perceived difference in diagnostic interpretation could not be demonstrated, since the median VGA was significantly different from 2. CONCLUSION: UHR-PCCT showed superior visibility compared to HR-EIDCT for central and peripheral airways, lung vasculature, fissures, ground glass opacities, macro- and micronodules, inter- and intralobular lines, paraseptal and centrilobular emphysema, bullae/cysts, and air trapping. CLINICAL RELEVANCE STATEMENT: UHR-PCCT has emerged as a promising technique for thoracic imaging, offering improved spatial resolution and lower radiation dose. Implementing PCCT into daily practice may allow better visibility of multiple lung structures and optimization of scan protocols for specific pathology. KEY POINTS: • The aim of this study was to verify if the higher spatial resolution of UHR-PCCT would improve the visibility and detection of certain lung structures and abnormalities. • UHR-PCCT was judged to have superior clinical image quality compared to conventional HR-EIDCT in the evaluation of the lungs. UHR-PCCT showed better visibility for almost all tested lung structures (except for ground glass nodules). • Despite superior image quality, the readers perceived no significant impact on the diagnostic interpretation of the studied lung structures and abnormalities.

Granulomatous Lymphocytic Interstitial Lung Disease (GLILD) in Common Variable Immunodeficiency (CVID).

Teaching Point: Granulomatous lymphocytic interstitial lung disease is a non-infectious complication of common variable immunodeficiency. Computed tomography (CT) has an important diagnostic value by demonstrating pulmonary nodules, ground glass opacities, bronchiectasis, subpleural reticulations, lymphadenopathy and splenomegaly.

Insidious Onset of Pulmonary Langerhans Cell Histiocytosis During Oncological Follow-Up.

Teaching Point: Pulmonary Langerhans cell histiocytosis (PLCH) has to be included in the differential diagnosis of cystic pulmonary lesions on chest computed tomography (CT). CT has important diagnostic value by demonstrating initial centrilobular nodules that in time cavitate and transform into cysts, typically sparing the costophrenic angles.

CT-Guided Transthoracic Biopsy of Lung Lesions Using a Non-Coaxial Biopsy Needle Technique: CT Characteristics Predictive for Diagnostic Accuracy and Pneumothorax.

OBJECTIVES: To analyze computed tomography (CT) characteristics predictive for diagnostic accuracy and pneumothorax in CT fluoroscopy-guided transthoracic biopsy (CTF-TTB) of lung lesions using non-coaxial biopsy needle technique. METHODS: Retrospectively 274 lung lesion biopsies with confirmed histology were included in our study. CTF-TTB was done using an 18-gauge non-coaxial cutting needle. Diagnostic accuracy rates were calculated per lesion size and CT and procedural characteristics were evaluated for their predictive value regarding diagnostic accuracy and development of pneumothorax (maximal nodule diameter, distance to pleura, location per lung segment, nodule composition, benign versus malignant histology, and number of specimens). RESULTS: Overall diagnostic accuracy of CTF-TTB was high (93%). Diagnostic accuracy for lesions ≤10 mm was 81%. Maximal nodule diameter was the only predictive CT characteristic for diagnostic success (p = 0.03). Pneumothorax occurred in 27%. Distance of lesion to pleura was the only risk factor for pneumothorax (p < 0.00001). Pneumothorax rates were significantly lower in subpleural lesions (14%) compared to those located 1-10 mm (47%), 10-20 mm (33%), and >20 mm from pleura (29%). CONCLUSIONS: High diagnostic accuracy rates were achieved with CTF-TTB using non-coaxial biopsy technique, even for lesions ≤10 mm. Pneumothorax rates were comparable with other studies. Lesion size was the only predictive CT characteristic for diagnostic accuracy. Distance to pleura was the only risk factor for pneumothorax.

Distinct Airway Involvement in Subtypes of End-Stage Fibrotic Pulmonary Sarcoidosis.

BACKGROUND: Sarcoidosis is a systemic granulomatous disease that in most patients affects the lung. Pulmonary fibrotic sarcoidosis is clinically, radiologically, and pathologically a heterogeneous condition. Although substantial indirect evidence suggests small airways involvement, direct evidence currently is lacking. RESEARCH QUESTION: What is the role of the (small) airways in fibrotic sarcoidosis? STUDY DESIGN AND METHODS: Airway morphologic features were investigated in seven explant lungs with end-stage fibrotic sarcoidosis using a combination of CT scanning (large airways), micro-CT scanning (small airways), and histologic examination and compared with seven unused donor lungs as controls with specific attention focused on different radiologically defined sarcoidosis subtypes. RESULTS: Patients with central bronchial distortion (n = 3), diffuse bronchiectasis (n = 3), and usual interstitial pneumonia pattern (n = 1) were identified based on CT scan, showing a decrease and narrowing of large airways, a similar airway number and increased airway diameter of more distal airways, or an increase in airway number and airway diameter, respectively, compared with control participants. The number of terminal bronchioles per milliliter and the total number of terminal bronchioles were decreased in all forms of fibrotic sarcoidosis. Interestingly, the number of terminal bronchioles was inversely correlated with the degree of fibrosis. Furthermore, we identified granulomatous remodeling as a cause of small airways loss using serial micro-CT scanning and histologic examination. INTERPRETATION: The large airways are involved differentially in subtypes of sarcoidosis, but the terminal bronchioles universally are lost. This suggests that small airways loss forms an important aspect in the pathophysiologic features of fibrotic pulmonary sarcoidosis.

Histopathologic and radiologic assessment of nontransplanted donor lungs.

Donor organ shortage results in significant waiting list mortality. Donor lung assessment is currently based on donors' history, gas exchange, chest X-ray, bronchoscopy findings, and ultimately in situ inspection but remains subjective. We correlated histopathology and radiology in nontransplanted donor lungs with the clinical indications to decline the offered organ. Sixty-two donor lungs, not used for transplantation (2010-2019), were procured, air-inflated, frozen, scanned with computed tomography, systematically sampled, and histologically and radiologically assessed. Thirty-nine (63%) lungs were declined for allograft-related reasons. In 13/39 (33%) lungs, histology could not confirm the reason for decline, in an additional 8/39 (21%) lungs, histologic abnormalities were only considered mild. In 16/39 (41%) lungs, radiology could not confirm the reason for decline. Twenty-three (37%) donor lungs were not transplanted due to extrapulmonary causes, of which three (13%) lungs displayed severe histologic abnormalities (pneumonia, n = 2; emphysema, n = 1), in addition to mild emphysema in 9 (39%) lungs and minor bronchopneumonia in 1 (4%). Radiology revealed ground-glass opacities in 8/23 (35%) and emphysema in 4/23 (17%) lungs. Histopathologic and radiologic assessment of nontransplanted donor lungs revealed substantial discrepancy with the clinical reason for decline. Optimization of donor lung assessment is necessary to improve current organ acceptance rates.

Airway morphometry in COPD with bronchiectasis: a view on all airway generations.

The pathophysiological processes underlying bronchiectasis in chronic obstructive pulmonary disease (COPD) are not understood. In COPD, both small and large airways are progressively lost. It is currently not known to what extent the different airway generations of patients with COPD and bronchiectasis are involved.COPD explant lungs with bronchiectasis were compared to COPD explant lungs without bronchiectasis and unused donor lungs as controls. In order to investigate all airway generations, a multimodal imaging approach using different resolutions was conducted. Per group, five lungs were frozen (n=15) and underwent computed tomography (CT) imaging for large airway evaluation, with four tissue cores per lung imaged for measurements of the terminal bronchioles. Two additional lungs per group (n=6) were air-dried for lobar microCT images that allow airway segmentation and three-dimensional quantification of the complete airway tree.COPD lungs with bronchiectasis had significantly more airways compared to COPD lungs without bronchiectasis (p<0.001), with large airway numbers similar to control lungs. This difference was present in both upper and lower lobes. Lack of tapering was present (p=0.010) and larger diameters were demonstrated in lower lobes with bronchiectasis (p=0.010). MicroCT analysis of tissue cores showed similar reductions of tissue percentage, surface density and number of terminal bronchioles in both COPD groups compared to control lungs.Although terminal bronchioles were equally reduced in COPD lungs with and without bronchiectasis, significantly more large and small airways were found in COPD lungs with bronchiectasis.

Phenotypical diversity of airway morphology in chronic lung graft vs. host disease after stem cell transplantation.

Pulmonary graft vs. host disease is a diverse and underestimated complication following allogenic hematopoietic stem cell transplantation. We aimed to compare the airway architecture with chronic lung allograft dysfunction post lung transplantation. Inflated explant lungs from graft vs. host disease patients were compared with lungs with chronic lung allograft dysfunction following lung transplantation, and control lungs using a combination of CT, microCT, and histology (n = 6 per group) and pathology in the (small) airways was further quantified and analyzed. Following allogenic hematopoietic stem cell transplantation, three patients presented as bronchiolitis obliterans syndrome and three patients showed interstitial changes and restriction. The CT analysis demonstrated a strong similarity between bronchiolitis obliterans syndrome after lung transplantation and post allogenic hematopoietic stem cell transplantation, evidenced by severe ( > 50%) airway obstruction from generation 9, with 70.8% of the airways ending in obstruction. Further analysis indicated that the airways either collapsed or accumulated matrix along a segment of the airway. In patients with restriction and interstitial changes following allogenic hematopoietic stem cell transplantation, the degree of airway obstruction was lower compared with bronchiolitis obliterans syndrome post allogenic hematopoietic stem cell transplantation, but similar to restrictive allograft syndrome post lung transplantation, showing a lower proportion of airway obstruction (20-35%), decreased number of terminal bronchioles per lung (p < 0.01), and parenchymal fibrosis. We observed similarities in the airway and parenchymal morphometric changes in lung graft vs. host disease and with chronic lung allograft dysfunction following lung transplantation, suggesting similar pathophysiological mechanisms.

Sensitization to Aspergillus fumigatus as a risk factor for bronchiectasis in COPD.

BACKGROUND: Bronchiectasis-chronic obstructive pulmonary disease (COPD) overlap presents a possible clinical phenotype of COPD, but it is unclear why it develops in a subset of patients. We hypothesized that sensitization to Aspergillus fumigatus (A fum) is associated with bronchiectasis in COPD and occurs more frequently in vitamin D-deficient patients. METHODS: This observational study investigated sensitization to A fum in an outpatient clinical cohort of 300 COPD patients and 50 (ex-) smoking controls. Total IgE, A fum-specific IgE against the crude extract and against the recombinant antigens and A fum IgG were measured using ImmunoCAP fluoroenzyme immunoassay. Vitamin D was measured by radioimmunoassay, and computed tomography images of the lungs were scored using the modified Reiff score. RESULTS: Sensitization to A fum occurred in 18% of COPD patients compared to 4% of controls (P=0.0110). In all, 31 COPD patients (10%) were sensitized to the crude extract and 24 patients (8%) had only IgE against recombinant antigens. A fum IgG levels were significantly higher in the COPD group (P=0.0473). Within COPD, A fum-sensitized patients were more often male (P=0.0293) and more often had bronchiectasis (P=0.0297). Pseudomonas aeruginosa and Serratia marcescens were more prevalent in historical sputum samples of A fum-sensitized COPD patients compared to A fum-non-sensitized COPD patients (P=0.0436). Vitamin D levels were comparable (P=0.2057). Multivariate analysis demonstrated that sensitization to recombinant f1 or f3 had a 2.8-fold increased risk for bronchiectasis (P=0.0030). CONCLUSION: These results highlight a potential role for sensitization to A fum in COPD-related bronchiectasis.

Thin-Section CT Features of Idiopathic Pulmonary Fibrosis Correlated with Micro-CT and Histologic Analysis.

Purpose To elucidate the underlying lung changes responsible for the computed tomographic (CT) features of idiopathic pulmonary fibrosis (IPF) and to gain insight into the way IPF proceeds through the lungs and progresses over time. Materials and Methods Micro-CT studies of tissue cores obtained from explant lungs were examined and were correlated 1:1 with a CT study obtained immediately before transplantation. Samples for histologic analysis were obtained from selected cores. Results In areas with no or minimal abnormalities on CT images, small areas of increased attenuation located in or near the interlobular septa can be seen on micro-CT studies. In more involved lung areas, the number of opacities increases and opacities enlarge and approach each other along the interlobular septa, causing a fine reticular pattern on CT images. Simultaneously, air-containing structures in and around these opacities arise, corresponding with small cysts on CT images. Honeycombing is caused by a progressive increase in the number and size of these cystic structures and tissue opacities that gradually extend toward the centrilobular region and finally replace the entire lobule. At histologic analysis, the small islands of increased attenuation very likely correspond with fibroblastic foci. Near these fibroblastic foci, an abnormal adjacency of alveolar walls was seen, suggesting alveolar collapse. In later stages, normal lung tissue is replaced by a large amount of young collagen, as seen in patients with advanced fibrosis. Conclusion Fibrosis and cyst formation in patients with IPF seem to start at the periphery of the pulmonary lobule and progressively extend toward the core of this anatomic lung unit. Evidence was found that alveolar collapse might already be present in an early stage when there is only little pulmonary fibrosis. © RSNA, 2016.