Volumetric Tissue Imaging of Surgical Tissue Specimens Using Micro-Computed Tomography: An Emerging Digital Pathology Modality for Nondestructive, Slide-Free Microscopy-Clinical Applications of Digital Pathology in 3 Dimensions

OBJECTIVES

Micro-computed tomography (micro-CT) is a novel, nondestructive, slide-free digital imaging modality that enables the acquisition of high-resolution, volumetric images of intact surgical tissue specimens. The aim of this systematic mapping review is to provide a comprehensive overview of the available literature on clinical applications of micro-CT tissue imaging and to assess its relevance and readiness for pathology practice.

METHODS

A computerized literature search was performed in the PubMed, Scopus, Web of Science, and CENTRAL databases. To gain insight into regulatory and financial considerations for performing and examining micro-CT imaging procedures in a clinical setting, additional searches were performed in medical device databases.

RESULTS

Our search identified 141 scientific articles published between 2000 and 2021 that described clinical applications of micro-CT tissue imaging. The number of relevant publications is progressively increasing, with the specialties of pulmonology, cardiology, otolaryngology, and oncology being most commonly concerned. The included studies were mostly performed in pathology departments. Current micro-CT devices have already been cleared for clinical use, and a Current Procedural Terminology (CPT) code exists for reimbursement of micro-CT imaging procedures.

CONCLUSIONS

Micro-CT tissue imaging enables accurate volumetric measurements and evaluations of entire surgical specimens at microscopic resolution across a wide range of clinical applications.

Prospective Radiologic-Pathologic Correlation of Macroscopic Volume and Microscopic Extension of Nonsolid Lung Nodules on Thin-section CT Images for Sublobar Resection and Stereotactic Radiotherapy Planning

INTRODUCTION

The objective of this study was to determine whether computed tomography (CT) could be a useful tool for nonsolid lung nodule (NSN) treatment planning, surgery or stereotactic body radiation therapy (SBRT), by assessing the macroscopic and microscopic extension of these nodules.

METHODS

The study prospectively included 23 patients undergoing anatomic resection at the Foch Hospital in 2020/2021 for NSN with a ground-glass component of more than 50%. Firstly, for each patient, both the macroscopic dimensions of the NSN were assessed on CT and during pathologic analysis. Secondly, the microscopic extension was assessed during pathologic examination. Wilcoxon sign rank tests were used to compare these dimensions. Spearman correlation test and Bland-Altman analysis were used to evaluate the agreement between radiological and pathologic measurements.

RESULTS

On CT, the median largest diameter and volume of NSN were 21 mm and 3780 cc, while on pathologic analysis, they were 15 mm and 1800 cc, respectively. Therefore, the largest diameter and volume of the NSN were significantly higher on CT than on pathological analysis. For microscopic extension, the median largest diameter and volume of NSN were 17 mm and 2040 cc, respectively. No significant difference was observed between the macroscopic size and the microscopic extension assessed during pathologic analysis. Moreover, correlation analysis and Bland-Altman plots showed that radiological and pathologic measurements could provide equivalent precision.

CONCLUSION

Our study showed that CT did not underestimate the macroscopic size and microscopic extension of NSN and confirmed that CT can be used for NSN treatment planning.

Volumetric Imaging of Lung Tissue at Micrometer Resolution: Clinical Applications of Micro-CT for the Diagnosis of Pulmonary Diseases

Micro-computed tomography (micro-CT) is a promising novel medical imaging modality that allows for non-destructive volumetric imaging of surgical tissue specimens at high spatial resolution. The aim of this study is to provide a comprehensive assessment of the clinical applications of micro-CT for the tissue-based diagnosis of lung diseases. This scoping review was conducted in accordance with the PRISMA Extension for Scoping Reviews, aiming to include every clinical study reporting on micro-CT imaging of human lung tissues. A literature search yielded 570 candidate articles, out of which 37 were finally included in the review. Of the selected studies, 9 studies explored via micro-CT imaging the morphology and anatomy of normal human lung tissue; 21 studies investigated microanatomic pulmonary alterations due to obstructive or restrictive lung diseases, such as chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis, and cystic fibrosis; and 7 studies examined the utility of micro-CT imaging in assessing lung cancer lesions (n = 4) or in transplantation-related pulmonary alterations (n = 3). The selected studies reported that micro-CT could successfully detect several lung diseases providing three-dimensional images of greater detail and resolution than routine optical slide microscopy, and could additionally provide valuable volumetric insight in both restrictive and obstructive lung diseases. In conclusion, micro-CT-based volumetric measurements and qualitative evaluations of pulmonary tissue structures can be utilized for the clinical management of a variety of lung diseases. With micro-CT devices becoming more accessible, the technology has the potential to establish itself as a core diagnostic imaging modality in pathology and to enable integrated histopathologic and radiologic assessment of lung cancer and other lung diseases.

A simplified model for determining the cutting plane during thoracoscopic anatomical partial lobectomy of the right lower lobe

Background

Few studies have examined the use of two-dimensional computed tomography (2D CT) and three-dimensional (3D) reconstruction images to determine the intersegmental plane (ISP) for pulmonary segmentectomy, but a systematic approach and nomenclature are currently lacking. This current study used 3D reconstruction of CT imaging to analyze variations in the right lower lobe’s pulmonary ISP and created a simplified model to determine the optimum cutting plane (CP) for clinical application for operative planning and use during thoracoscopic anatomical partial lobectomy (APL).

Methods

Between January 2018 and October 2019, 325 patients with pulmonary lesions were identified who underwent thin-slice CT scans of the chest. The ISPs were identified by analyzing the 2D CT scans and 3D reconstruction images and the anatomical characteristics segmental boundary. The CP for the thoracoscopic procedure was then determined within the safe surgical margins, and a simplified CP model was created.

Results

The boundary between adjacent lung segment A and segment B was be expressed as “ISP: Sa-Sb”. The ISP was divided into venous ISP (VISP), arterial ISP (AISP), and bronchial ISP (BISP). The proposed model of the CP can be expressed as follows: CP (f) = (V/A/B) ISP (x) + (V/A/B) sub ISP (y) + (V/A/B) sub-sub ISP (z).

Conclusions

This report is a first attempt to provide a nomenclature for identifying the ISP, and create a simplified model for determining the CP for thoracoscopic partial lobectomy.

Demarcation of arteriopulmonary segments: a novel and effective method for the identification of pulmonary segments

Objective

Each pulmonary segment is an anatomical and functional unit. However, it is fundamentally difficult to precisely distinguish every pulmonary segment using the conventional pulmonary intersegmental planes from computed tomography images. Building arteriopulmonary segments is likely to be an effective way to identify pulmonary segments.

Methods

The thoracic computed tomography images of 40 patients were collected. The anatomic structures of interest were extracted in the transverse, sagittal, and coronal planes using the semi-automated segmentation tools provided by Amira software. The intrapulmonary vessels were subsequently segmented and reconstructed. The distributions of the pulmonary arteries, veins, and bronchi were observed. In patients with pulmonary masses, the mass was also reconstructed.

Results

The three-dimensional reconstructed images showed the branches of the pulmonary artery ramified up to their eighth order covering the entire lung as well as evident intersegmental gaps without pulmonary arteries. The segmental artery was closely accompanied by the segmental bronchi in 486 pulmonary segments (90% of total number of segments). The size and spatial location of the pulmonary mass within a pulmonary segment were also clearly visible.

Conclusions

Demarcation of arteriopulmonary segments can be used to precisely distinguish every pulmonary segment and provide its detailed anatomical structure before pulmonary segmentectomy.

[Advances in Identification of Intersegmental Plane during Pulmonary Segmentectomy]

With the popularity of computed tomography (CT) scan in recent years, early stage lung cancer has been discovered in large numbers of patients and pulmonary segmentectomy has been widely used clinically. Identification of the intersegmental plane is one of the key steps in pulmonary segmentectomy, and current methods for identifying the intersegmental plane are numerous and have their own advantages and disadvantages. We will review relevant methods to help the clinical practice.
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CT imaging and pathological basis of linear shadow connecting pulmonary segmental artery to horizontal fissure

To investigate the computed tomography (CT) imaging and pathological basis of the linear shadows connecting pulmonary segmental arteries to horizontal fissure (hereinafter referred to as "linear shadow") on thin-slice CT.Collect 127 clinical cases to analyze the display and morphology of linear shadows on the thin-slice CT and to measure their length, thickness, and angle. Collect 11 autopsy specimens of coal worker's pneumoconiosis to conduct an imaging and pathology basis control study for the linear shadows.There is no correlation between the linear shadow and gender, age, and smoking history. Linear shadows are observed in 54.33% of patients. 93.33% of those linear shadows are straight lines. Generally, the lengths are less than 10 mm, the thicknesses are around 1 mm, and the scopes of angles are wide, range from acute angles to obtuse angles. The linear shadow is a banded structure consisting of loose connective tissue, small blood vessels, and small lymphatic vessels due to the visceral pleura recessed and fused into the lung.Linear shadows are intrinsic to the lung. The linear shadows consist of loose connective tissue, small blood vessels, and small lymphatic vessels.

Linear shadows that connect oblique fissures and costal pleurae on the superior segments of lower lobes: evaluating the imaging findings on thin-slice lung CT

OBJECTIVE

To retrospectively analyse the imaging findings of the linear shadows that connect the oblique fissures and the costal pleurae on the superior segments of the lower lobes on thin-slice lung CT.

MATERIALS AND METHODS

Thin-slice CT scans of 221 cases of normal lungs and 86 abnormal lungs were collected. The parameters of the imaging observations included the existence of the superior segmental linear shadow, its morphology, length, and starting position, bird-beak sign, and adjacent structures on the pleural end.

RESULTS

The linear shadows were more common on the left lower lobe (43.44%) than on the right side (19.46%). The pleural origins of the linear shadows were mainly located above the carina (69.78%); the adjacent structure on the left lung was the descending aorta (70.83%), and for the right lung, it was next to the thoracic vertebrae (60.47%). In the presence of pulmonary lobectomy or atelectasis, the linear shadows could be extended, which could pull the oblique fissures and costal pleurae to form the bird-beak sign.

CONCLUSION

The linear shadows on the superior segments of the lower lobes are common structures fixing the oblique fissures. Recognition of the linear shadows can help radiologists distinguish normal structures from abnormal ones.

Kohn's pores are not responsible for collateral ventilation between inflated and deflated segments: a microscopic study of pulmonary intersegmental septa in the human lung

The composition of the pulmonary intersegmental septum has not been clearly identified by thoracic surgeons who regard Kohn's pores as the main channel that causes air leakage when determining the intersegmental septum by segmental ventilation. In this study, we aimed to examine this possible misinterpretation by focusing on a detailed description of the microscopic anatomy of the intersegmental septum. To accomplish this aim, 50 lung samples of the intersegmental septum from fresh cadavers without emphysema were studied by histological and electron microscopy. The findings of light microscopy and electron microscopy showed that the intersegmental septum is composed of three layers. The alveolar walls of adjacent segments serve as the superficial layer. They are integral, and no Kohn's pores were identified. The deep layer contains collagen fibres. As shown by our findings, Kohn's pores are absent within the intersegmental septum. Therefore, they could not be the main channel for the collateral ventilation between inflated and deflated lung segments during a pulmonary segmentectomy.