Impact of deep learning image reconstruction on volumetric accuracy and image quality of pulmonary nodules with different morphologies in low-dose CT.

BACKGROUND: This study systematically compares the impact of innovative deep learning image reconstruction (DLIR, TrueFidelity) to conventionally used iterative reconstruction (IR) on nodule volumetry and subjective image quality (IQ) at highly reduced radiation doses. This is essential in the context of low-dose CT lung cancer screening where accurate volumetry and characterization of pulmonary nodules in repeated CT scanning are indispensable. MATERIALS AND METHODS: A standardized CT dataset was established using an anthropomorphic chest phantom (Lungman, Kyoto Kaguku Inc., Kyoto, Japan) containing a set of 3D-printed lung nodules including six diameters (4 to 9 mm) and three morphology classes (lobular, spiculated, smooth), with an established ground truth. Images were acquired at varying radiation doses (6.04, 3.03, 1.54, 0.77, 0.41 and 0.20 mGy) and reconstructed with combinations of reconstruction kernels (soft and hard kernel) and reconstruction algorithms (ASIR-V and DLIR at low, medium and high strength). Semi-automatic volumetry measurements and subjective image quality scores recorded by five radiologists were analyzed with multiple linear regression and mixed-effect ordinal logistic regression models. RESULTS: Volumetric errors of nodules imaged with DLIR are up to 50% lower compared to ASIR-V, especially at radiation doses below 1 mGy and when reconstructed with a hard kernel. Also, across all nodule diameters and morphologies, volumetric errors are commonly lower with DLIR. Furthermore, DLIR renders higher subjective IQ, especially at the sub-mGy doses. Radiologists were up to nine times more likely to score the highest IQ-score to these images compared to those reconstructed with ASIR-V. Lung nodules with irregular margins and small diameters also had an increased likelihood (up to five times more likely) to be ascribed the best IQ scores when reconstructed with DLIR. CONCLUSION: We observed that DLIR performs as good as or even outperforms conventionally used reconstruction algorithms in terms of volumetric accuracy and subjective IQ of nodules in an anthropomorphic chest phantom. As such, DLIR potentially allows to lower the radiation dose to participants of lung cancer screening without compromising accurate measurement and characterization of lung nodules.

COVID-19 pneumonia imaging follow-up: when and how? A proposition from ESTI and ESR.

This document from the European Society of Thoracic Imaging (ESTI) and the European Society of Radiology (ESR) discusses the role of imaging in the long-term follow-up of COVID-19 patients, to define which patients may benefit from imaging, and what imaging modalities and protocols should be used. Insights into imaging features encountered on computed tomography (CT) scans and potential pitfalls are discussed and possible areas for future review and research are also included. KEY POINTS: • Post-COVID-19 pneumonia changes are mainly consistent with prior organizing pneumonia and are likely to disappear within 12 months of recovery from the acute infection in the majority of patients. • At present, with the longest series of follow-up examinations reported not exceeding 12 months, the development of persistent or progressive fibrosis in at least some individuals cannot yet be excluded. • Residual ground glass opacification may be associated with persisting bronchial dilatation and distortion, and might be termed "fibrotic-like changes" probably consistent with prior organizing pneumonia.

PULMONARY NODULE DETECTION IN CHEST CT USING A DEEP LEARNING-BASED RECONSTRUCTION ALGORITHM.

This study's aim was to assess whether deep learning image reconstruction (DLIR) techniques are non-inferior to ASIR-V for the clinical task of pulmonary nodule detection in chest computed tomography. Up to 6 (range 3-6, mean 4.2) artificial lung nodules (diameter: 3, 5, 8 mm; density: -800, -630, +100 HU) were inserted at different locations in the Kyoto Kagaku Lungman phantom. In total, 16 configurations (10 abnormal, 6 normal) were scanned at 7.6, 3, 1.6 and 0.38 mGy CTDIvol (respectively 0, 60, 80 and 95% dose reduction). Images were reconstructed using 50% ASIR-V and a deep learning-based algorithm with low (DL-L), medium (DL-M) and high (DL-H) strength. Four chest radiologists evaluated 256 series by locating and scoring nodules on a five-point scale. No statistically significant difference was found among the reconstruction algorithms (p = 0.987, average across readers AUC: 0.555, 0.561, 0.557, 0.558 for ASIR-V, DL-L, DL-M, DL-H).

Lung imaging in bronchopulmonary dysplasia: a systematic review.

BACKGROUND: Bronchopulmonary dysplasia (BPD) remains a common complication of preterm birth. Both historically and in current practice, radiologic evaluation of the lungs has an important role in assessing disease severity and complications. AIM: To provide an overview of imaging techniques for detecting lung abnormalities in patients with BPD in all age ranges. METHODS: A systematic literature search was conducted in PubMed, Web of Science and the Cochrane Library. Records were screened by title and abstract and then by full text. A total of 37 records were selected and included in this qualitative literature overview. RESULTS: Computed tomography (CT) was the most commonly used imaging modality, followed by chest radiography and magnetic resonance imaging (MRI). Several qualitative and quantitative scoring systems were presented and most showed good correlation with BPD severity. The association with functional and clinical outcomes was only rarely reported, showing varying correlation with spirometry results and respiratory exacerbations. MRI is an upcoming imaging technique for BPD that is technically feasible, showing clear differences in the lung parenchyma of patients with BPD. CONCLUSION: Several imaging and scoring methods indicate that lung imaging continues to play a role in BPD care. Standardization and correlation with functional and clinical outcomes will become increasingly important for further research.

Lesion detection on a combined "All-in-One" window compared to conventional window settings in thoracic oncology chest CT examinations.

PURPOSE: The purpose of this study was to investigate if lesion detection using a single "All-in-One" (AIO) window was non-inferior to lesion detection on conventional window settings in thoracic oncology chest computed tomography (CT) examinations. MATERIALS AND METHODS: In a retrospective study, 50 consecutive chest CT examinations of 50 patients (31 men, 19 women; mean age 64±10 [SD] years, range: 35-82 years) containing 417 lesions, were reviewed by 6 radiologists, subdivided into 2 groups of 3 radiologists each, with similar levels of expertise in each group (senior staff member, junior staff member and radiology resident). All examinations were reviewed in conventional or AIO window settings by one of the groups. A 'lesion' was defined as any abnormality seen on the chest CT examination, including both benign and malignant lesions, findings in chest and upper abdomen, and measurable and non-measurable disease. Lesions were listed as 'missed' when they were not seen by at least two out of three observers. F-tests were used to evaluate the significance of the variables of interest within a mixed model framework and kappa statistics to report interobserver agreement. RESULTS: On a reader level, 54/417 lesions (12.9%) were not detected by the senior staff member reading the studies in conventional window settings and 45/417 (10.8%) by the senior staff member reading the AIO images. For the junior staff member and radiology resident this was respectively 55/417 (13.2%) and 67/417 (16.1%) for the conventional window settings and 43/417 (10.3%) and 61/417 (14.6%) for the AIO window. On a lesion level, 68/417 (16.3%) were defined as 'missed' lesions (lesions not detected by at least 2 readers): 21/68 (30.9%) on the AIO-window, 30/68 (44.1%) on conventional views and 17/68 (25.0%) on both views. The use of the AIO window did not result in an increase of missed lesions (P>0.99). Interobserver agreement in both groups was similar (P=0.46). Regarding lesions that were categorized as 'missed' on the AIO window or on conventional window settings, there was no effect of location (chest or upper abdomen) (P=0.35), window (P=0.97) and organ (P=0.98). CONCLUSIONS: A single AIO-window is non-inferior to multiple conventional window settings for lesion detection on chest CT examinations in thoracic oncology patients.

Imaging of the spleen: what the clinician needs to know.

The spleen is considered 'the forgotten organ' among radiologists and clinicians, although it is well visualised on abdominal computed tomography and magnetic resonance imaging. Moreover, the spleen is commonly involved in a wide range of pathologic disorders. These include congenital anomalies, infectious and inflammatory diseases, vascular disorders, benign and malignant tumours, and systemic disorders. In this review, we focus on the key imaging findings of the normal spleen, its variants, as well as relevant congenital and acquired abnormalities. It is of utmost importance to recognise and correctly interpret the variable spectrum of abnormalities that may involve the spleen, in order to avoid unnecessary invasive procedures and to guide adequate treatment.

Lithium-Induced Nephropathy.

BACKGROUND: A 59-year-old man was referred for CT scan of the abdomen after repair of an eventrated appendectomy wound. The man had a known history of bipolar affective disorder, for which he had been on lithium therapy for many years. As an incidental finding, CT scan showed numerous small hypodense renal lesions. Subsequently a MRI examination was performed to further characterize these renal abnormalities.

Septic Thrombophlebitis of the Right Ovarian Vein.

BACKGROUND: A 26-year-old woman presented at the emergency department with a painful abdomen and fever up to 39°C, despite antibiotics. She had given prematurely birth by caesarian section to a twin 8 days earlier. On clinical examination she had a diffuse painful and tender abdomen, especially on the right side and suprapubic region. Laboratory findings showed an increased c-reactive protein of 24 mg/dL (normal < 0,3) and increased white blood cell count of 13 Å~ 10E9/L (normal 4,3-10 Å~ 10E9/L). There was also a decreased hemoglobin level of 8,4 g/dL (normal 12-15 g/dL). An ultrasonography was performed by the gynecologist and revealed a large heterogeneous fluid collection anteriorly of the uterus.

Ileocolic intussusception due to lipomatosis of the ileum: a common complication of a rare clinical entity.

We report a case of intestinal ileal lipomatosis in a 56-year-old Caucasian male complicated with small bowel obstruction due to ileocolic intussusception with a lipoma serving as lead point. This rare disease is often only discovered incidentally as a consequence of mechanical complications and not well reported in the international literature, compared to intussusception due to an isolated lipoma. Computed tomography is the imaging modality of choice to depict complications of this distinct clinicopathological entity. Density measurements can confirm the fatty content and homogeneity analysis of the lesions can guide the radiologist in the differential diagnosis.

Update in non small-cell lung cancer staging.

Significant progress has been made with the introduction of the TNM-7 staging system for non-small cell lung cancer (NSCLC). Constituting the first major revision in 12 years, the seventh edition of NSCLC TNM (TNM-7) is based on the recommendations from the International Association for the Study of Lung Cancer (IASLC) Lung Cancer Staging Project of 2007. This new TNM iteration includes a subset analysis on SCLC and carcinoid tumors. A thorough understanding of its principles by the radiologist is helpful to increase efficiency and to improve communication with the referring clinicians.

Excessive eosinophilia as paraneoplastic syndrome in a patient with non-small-cell lung carcinoma: a case report and review of the literature.

Hypereosinophilia is a phenomenon which is associated with a broad variety of allergic, infectious, paraneoplastic and systemic diseases. Depending on the aetiology, these disorders differ in severity from self-limiting to life-threatening. Although it is well known that hypereosinophilia can occur in association with a solid tumour, exact numbers of incidence are lacking. We describe a patient with respiratory insufficiency and an elevated level of eosinophils in the peripheral blood. A diagnostic work-up revealed the presence of a disseminated non-small-cell carcinoma of the lung; an association not frequently described.

Post-traumatic hepatic arterial pseudoaneurysm and arterioportal shunt.

The authors report the case of a 21-year-old man who suffered from a blunt abdominal trauma. Initial imaging revealed a liver laceration at the right lobe, a perirenal hematoma of the right kidney and a hematoma of the right adrenal gland. Follow-up MDCT-scan on day 10 after admission showed at the arterial-phase contrast-enhanced study perfusion alterations and two hepatic pseudoaneurysms. The diagnosis of pseudoaneurysm was confirmed and treated angiographically with superselective coil embolization. A follow-up CT-scan on day 17 showed at a nontreated area an arterioportal shunt and a wedge-shaped transient hepatic parenchymal enhancement. This was confirmed angiographically and subsequently treated with coil embolization.

Asymptomatic pneumatosis intestinalis in AIDS.

Pneumatosis intestinalis is an unusual entity in which subserosal or submucosal collections of gas occur in the bowel wall. We present a case of asymptomatic linear pneumatosis intestinalis and free abdominal air in a 67-year-old man with acquired immunodeficiency syndrome (AIDS) who improved spontaneously following conservative management. Pneumatosis intestinalis is a late-stage phenomenon in patients with AIDS that characteristically involves the cecum, ascending and transverse colon or the rectum with sparing of the descending colon and the sigmoid. For these patients, non-operative management is appropriate.

Nonthrombotic pulmonary embolism.

Nonthrombotic pulmonary embolism (NTPE) is defined as embolisation to the pulmonary circulation of different cell types (adipocytes, haematopoietic, amniotic, trophoblastic or tumour), bacteria, fungi, foreign material or gas. The purpose of this article is to describe the clinical signs, pathogenesis, diagnosis and treatment of the different NTPE subtypes. The complex and diverse pathogenesis of different subtypes of emboli is subject to continuing speculation and is certainly far more complex than "simple" mechanical obstruction after embolisation of vascular thrombi. Nonthrombotic emboli may also lead to a severe inflammatory reaction both in the systemic and pulmonary circulation, as well as in the lung. NTPE presents a formidable diagnostic challenge, as the condition often presents with very unusual and peculiar clinical signs that are frequently overlooked. They range from very dramatic acute presentations such as acute respiratory distress syndrome to signs observed late in the disease course. Pathological observations play a key role in the exact diagnosis, and sometimes carefully aspirated blood from the pulmonary artery or specific staining of cells recovered from bronchoalveolar lavage fluid may be helpful. Frequently, lung biopsies revealing severe granulomatous reaction or unfortunate post-mortem pathological investigations of pulmonary tissue are necessary to confirm the diagnosis. Here, we also aim to familiarise the reader with the atypical radiological features of NTPE. Thin-section computed tomography of the lungs showing peculiar radiographic findings, such as a feeding vessel, the so-called tree-in-bud pattern or the appearance of micronodules distributed at the termination of bronchovascular bundles, may be observed in certain forms of NTPE. Increased awareness of NTPE as an underestimated cause of acute and chronic embolism, which may result in acute and chronic pulmonary hypertension, is needed. Despite the fact that detailed descriptions of several forms of NTPE have existed for nearly 100 years, well-designed trials have never been performed to evaluate therapy in the different subsets of these patients.