Post-processing applications in thoracic computed tomography

How Artificial Intelligence in Imaging Can Better Serve Patients with Bronchial and Parenchymal Lung Diseases?

With the rapid development of computing today, artificial intelligence has become an essential part of everyday life, with medicine and lung health being no exception. Big data-based scientific research does not mean simply gathering a large amount of data and letting the machines do the work by themselves. Instead, scientists need to identify problems whose solution will have a positive impact on patients’ care. In this review, we will discuss the role of artificial intelligence from both physiological and anatomical standpoints, starting with automatic quantitative assessment of anatomical structures using lung imaging and considering disease detection and prognosis estimation based on machine learning. The evaluation of current strengths and limitations will allow us to have a broader view for future developments.

Computer-aided analysis in evaluation and grading of interstitial lung diseases in correlation with CT-based visual scoring and pulmonary function tests

Background

Interstitial lung diseases (ILDs) represent a large group of more than 200 different entities. High resolution computed tomography (HRCT) is accepted as the gold standard imaging modality in the diagnosis of ILD. The visual-based scoring offers an advantage in finding a specific type of ILD. Computer-aided CT attenuation histogram is another way of characterizing and quantifying diffuse lung disease. The histogram analysis (HIST) consists of calculating skewness, kurtosis, and mean lung density to quantify lung disease and monitor progression. The aim of our study was to investigate the value of computer-aided analysis of HRCT for interstitial lung diseases in correlation with scoring and pulmonary function tests.

Results

This prospective study included 50 patients with suspected ILD. The mean age of patients was 46.7 years ± 12.5. Mean forced expiratory volume FEV1 was 63.6 ± 20.9. HRCT examination was done for all patients followed by CT-based visual scaling. Most of the studied patients (43.3%) had a CT visual semi-quantitative scoring ranged between 40 and 64. CT-based lung density histograms (LDH) were obtained for all patients using the 3D Slicer Software (Chest Imaging Platform). There was a significant difference between patient’s groups of different (mild, moderate, and severe) grades of ILD according to FEV1 regarding MLD, skewness, and kurtosis of corresponding CT-based density histograms (p values < 0.001). More significant and higher correlation was observed between computerized aided CT quantified mean lung densities (MLD) and (FEV1) (p value < 0.001 and r = − 0.570). The ROC curve analysis demonstrated good performance for CT visual scoring with PFT (AUC = 0.71); a cutoff scoring 15 or higher was associated with best sensitivity (75%) and specificity (100%). Meanwhile, ROC curve analysis for MLD and FEV1 demonstrated an excellent performance for computer-based CT quantification (AUC = 0.85) with a value of − 769 HU which increased sensitivity to 65% and specificity to 100%.

Conclusion

Visual-based scoring techniques offer an advantage in finding a specific type of ILD. Computer-based quantification system could be a means for accurately monitoring the disease progression or response to therapy.

Initial diagnosis and successful treatment of pulmonary tumor embolism manifesting as the first clinical sign of prostatic adenocarcinoma

Although pulmonary tumor embolism (PTE) is a well-recognized end-stage form of pulmonary metastases at postmortem examination, the entity is rarely the first clinical sign of prostate cancer. Diagnosis of this condition in patients who have no previous history of malignancy is a challenge. Herein, we reported a 79-year-old man presented with progressive, unexplained dyspnea on exertion. Microscopic PTE coinciding with pulmonary lymphangitic carcinomatosis were readily recognized based on the presence of multifocal dilatation and beading of the peripheral pulmonary arteries with thickening of the bronchial walls and interlobular septa on the initial thin-section chest CT images. Pathologic examination of the transbronchial lung biopsy specimen revealed tumor emboli occluding both the small muscular pulmonary arteries and lymphatic vessels. These tumor cells were positive for prostatic specific antigen on immunohistochemical staining. The final diagnosis of prostatic adenocarcinoma was confirmed. Remarkable clinical and radiographic improvement was achieved following bilateral orchiectomies and anti-androgen treatment.

•

Pulmonary tumor embolism (PTE) can be the first clinical sign of advanced prostatic adenocarcinoma.

•

CT findings of dilated, beaded peripheral pulmonary arteries should raise a concern of microscopic PTE.

•

Dilated, beaded pulmonary arteries should not be mistaken for tree-in-bud opacities caused by bronchiolar disease on CT.

•

Prostate cancer should always be considered in the differential diagnosis of adenocarcinoma of unknown origin in men.

Operative Planning in Thoracic Surgery: A Pilot Study Comparing Imaging Techniques and Three-Dimensional Printing

BACKGROUND

Careful preoperative planning in thoracic surgery is essential for positive outcomes, especially in video-assisted thoracic surgery (VATS), where palpation and 3-dimensional (3D) imaging is restricted. This study evaluated the ability of different imaging techniques, such as computed tomography (CT) scanning, maximal intensity projection imaging, 3D reconstruction, and 3D printing, to define the anatomy of the hilar structures before anatomical lung resection.

METHODS

All patients undergoing elective lung resections by VATS for cancer under a single surgeon were identified over a 3-month period. The surgeon was asked to record the number of pulmonary artery branches supplying the lobe to be resected by using the preoperative CT scans, maximal intensity projection images, and 3D-reconstructed CT images. The lung hilum in 3 patients was printed. These were then compared with the intraoperative findings.

RESULTS

The preoperative imaging of 16 patients was analyzed. The lung hilum was printed in a further 3 patients. Although not statistically significant, the 3D prints of the hilum were the most accurate measurement, with a correlation of 0.92. CT, 3D-reconstructed CT, and maximal intensity projection images tended to underrecognize the number of arterial branches and therefore scored between 0.26 and 0.39 in absolute agreement with the number of arteries found at operation.

CONCLUSIONS

3D printing in the planning of thoracic surgery may suggest a benefit over contemporary available imaging modalities, and the use of 3D printing in practicing operations is being established.

Pulmonary quantitative CT imaging in focal and diffuse disease: current research and clinical applications

The frenetic development of imaging technology-both hardware and software-provides exceptional potential for investigation of the lung. In the last two decades, CT was exploited for detailed characterization of pulmonary structures and description of respiratory disease. The introduction of volumetric acquisition allowed increasingly sophisticated analysis of CT data by means of computerized algorithm, namely quantitative CT (QCT). Hundreds of thousands of CTs have been analysed for characterization of focal and diffuse disease of the lung. Several QCT metrics were developed and tested against clinical, functional and prognostic descriptors. Computer-aided detection of nodules, textural analysis of focal lesions, densitometric analysis and airway segmentation in obstructive pulmonary disease and textural analysis in interstitial lung disease are the major chapters of this discipline. The validation of QCT metrics for specific clinical and investigational needs prompted the translation of such metrics from research field to patient care. The present review summarizes the state of the art of QCT in both focal and diffuse lung disease, including a dedicated discussion about application of QCT metrics as parameters for clinical care and outcomes in clinical trials.

Airway Evaluation with Multidetector Computed Tomography Post-Processing Methods in Asthmatic Patients

Asthma is a chronic inflammatory obstructive airways disease. The disease occurs regardless of age and manifests with cough, attacks of breathlessness, and tightness in the chest. The pathophysiology of asthma is complex and still not fully understood. It is essential to find answers concerning the role of each part of the bronchial tree in asthma, especially the role of small bronchioles. With the development of newer generations of multidetector computed tomography (MDCT) and advanced post-processing methods it is possible to obtain more detailed images and gain insight into further aspects of asthma. MDCT post-processing methods can be divided into two-dimensional (2D) and three-dimensional (3D). In 2D projections, visualized hypodense regions correspond to the airway flow limitations. With the more advanced methods, such as multi planar reconstructions (MPR), images in different planes (axial, coronal, or sagittal) can be created. In the MPR technique only the voxels which are adjacent to each other in the predetermined plane can be extracted from the data set. Using the minimal/maximal intensity projections and shaded surface display, the volume of interest (VOI) can be extracted. High resolution CT scans can be used to create a more advanced imaging tool - the virtual bronchoscopy (VB). Using the VB makes it possible to visualize regions of obturation in the bronchi of up to the 5-8th generation. The MDCT with advanced post-processing methods is likely to assume an important role in the differential diagnosis of asthma, particularly when the diagnosis is dubious or hard to settle due to accompanying other lung diseases.

CT Imaging of Interstitial Lung Diseases

Until today, computed tomography (CT) is the most important and valuable radiological modality to detect, analyze, and diagnose diffuse interstitial lung diseases (DILD), based on the unsurpassed morphological detail provided by high-resolution CT technique.

In the past decade, there has been a shift from an isolated histopathological diagnosis to a multidisciplinary acquired diagnosis consensus that is nowadays regarded to provide the highest level of diagnostic accuracy in patients with diffuse interstitial lung diseases. The 2002 ATS/ERS statement on classification of idiopathic interstitial pneumonias assigned a central role to high-resolution CT (HRCT) in the diagnostic workup of idiopathic interstitial pneumonias (ATS/ERS consensus classification 2002). The more recent 2013 ERS/ATS statement reinforced that combined clinical data (presentation, exposures, smoking status, associated diseases, lung function, and laboratory findings) and radiological findings are essential for a multidisciplinary diagnosis (Travis et al., Am J Respir Crit Care Med 188(6):733–748, 2013).

The traditional HRCT consisted of discontinuous 1 mm high-resolution axial slices. The primary focus was on visual pattern analysis demanding for the highest possible spatial resolution. Because of the intrinsic high structural contrast of the lung, it has been possible to substantially reduce dose without losing diagnostic information. This development has been supported by new detection and reconstruction techniques. Not only detection of subtle disease and visual comparison of disease stage but also disease classification and quantification nowadays take advantage of continuous volumetric data acquisition provided by multidetector row (MD) CT technique. The following book chapter will focus on acquisition technique with special emphasis on dose and reconstruction, advantages, and new diagnostic options of volumetric MDCT technique for interstitial lung diseases. Based on evidence from the literature, certain diseases will be covered more specifically, but it has to be noted that for the pattern analysis of the various interstitial lung diseases, the plethora of other publications and books is recommended.

The Wonderful World of the Windpipe: A Review of Central Airway Anatomy and Pathology

A variety of pathologic processes can involve the central airways. Abnormalities may either diffusely or focally involve the tracheal or mainstem bronchial walls. Diseases that diffusely involve the tracheal wall can be subclassified as sparing the membranous trachea or circumferentially involving the tracheal wall. Focal diseases of the trachea and mainstem bronchi include benign and malignant causes. Additionally, congenital and acquired morphologic abnormalities of the trachea will be reviewed.

Oncological applications of dual-energy computed tomography imaging

Dual-energy computed tomography (DECT) imaging is a promising method used in oncology for accurate detection/diagnosis of malignant and benign lesions. Use of dual-energy spectral, weighted average, color-coded map, and virtual unenhanced images provides increased visual detection and easy lesion delineation. Lesion detectability, sensitivity, and conspicuity are significantly improved using DECT. Material characterization and decomposition are promising using DECT. Both anatomical and functional information related to oncology can be provided by DECT using single contrast-enhanced CT.

Role of imaging in diagnosis, staging and follow-up of lung cancer

PURPOSE OF REVIEW

Primary lung cancer is still the number one cause of cancer death worldwide. Screening, detection and staging of lung cancer are important because the only potentially curative therapy today is surgical resection of early-stage lung cancer.

RECENT FINDINGS

Different imaging techniques can be used in these different processes. Recent advances in computed tomography (CT) technology have allowed investigation of novel methods for the evaluation of lung cancer. Recent advances in magnetic resonance technology and administration of contrast media have further improved the image quality and diagnostic capability of magnetic resonance. Positron emission tomography (PET)/CT has been shown to be superior to stand-alone PET or CT in the evaluation of lymph nodes and in the detection of distant metastases.

SUMMARY

The current recommended imaging required for lung cancer staging is CT of the thorax and PET/CT from skull base to mid-thigh. However, with the recent developments in the armamentarium of imaging techniques, the choice of one of these techniques can be directed by the presence of a technique in a local hospital and/or by the presence of an experienced person at that time.

Modern diagnostic and therapeutic interventional radiology in lung cancer

Imaging has an important role in the multidisciplinary management of primary lung cancer. This article reviews the current state-of-the-art imaging modalities used for the evaluation, staging and post-treatment follow-up and surveillance of lung cancers, and image-guided percutaneous techniques for biopsy to confirm the diagnosis and for local therapy in non-surgical candidates.