State-of-the-art MR Imaging for Thoracic Diseases

Recent trends in scientific research in chest radiology: What to do or not to do? That is the critical question in research

Hereby inviting young rising stars in chest radiology in Japan for contributing what they are working currently, we would like to show the potentials and directions of the near future research trends in the research field. I will provide a reflection on my own research topics. At the end, we also would like to discuss on how to choose the themes and topics of research: What to do or not to do? We strongly believe it will stimulate and help investigators in the field.

Dynamic perfusion area-detector CT in non-small cell lung cancer with progressive fibrosing interstitial lung disease

OBJECTIVES

To determine the capability of dynamic contrast-enhanced (CE-) perfusion area-detector CT (ADCT) for detecting pathological structural changes in stage I non-small cell lung cancer (NSCLC) patients.

MATERIALS AND METHODS

Sixty-three consecutive stage I NSCLC patients with progressive fibrosing interstitial lung disease (PF-ILD) underwent dynamic CE-perfusion ADCT analyzed by dual-input maximum slope (DMS) methods for total, pulmonary arterial and systemic arterial perfusion (TPDMS, PAPDMS and SAPDMS) maps, surgical treatment and pathological examination. Multicentric ROIs were then placed over sites assessed as normal lung, pulmonary emphysema, GGO or reticular pattern without traction bronchiectasis, reticular pattern with traction bronchiectasis and honeycombing in the resected lung. Next, an analysis of variance (ANOVA) followed by Tukey's honest significant difference (HSD) multiple comparison test was performed for a comparison of each of the perfusion parameters for five groups. Finally, discrimination accuracy for evaluation of lung parenchymal change was compared for all indexes and combined methods.

RESULTS

PAPDMSs of abnormal lungs were significantly lower than that of normal lungs (p < 0.0001). SAPDMSs of normal or emphysematous lungs were significantly lower than those of others (p < 0.0001). SAPDMS of GGO or reticular pattern without traction bronchiectasis was significantly lower than that for reticular pattern with traction bronchiectasis and honeycombing (p < 0.0001). Discrimination accuracy of combined perfusion index was significantly higher than that of each index (p < 0.0001).

CONCLUSION

Dynamic CE-perfusion ADCT is useful for detecting pathological structural changes in stage I NSCLC patients with PF-ILD.

KEY POINTS

Question Can dynamic first-pass contrast-enhanced perfusion matrices evaluate parenchymal lung changes and disease severity of parenchymal diseases in stage I non-small cell lung cancer (NSCLC) patients? Findings Perfusion indexes differentiated significantly among normal lung, emphysema, GGO or reticular pattern without traction bronchiectasis, reticular pattern with traction bronchiectasis and honeycombing and significantly improved discrimination accuracy by combined methods. Clinical relevance Dynamic first-pass contrast-enhanced perfusion area-detector CT has the potential to assess underlying pathologies and pulmonary functional changes in stage I non-small cell carcinoma patients with progressive fibrosing interstitial lung disease.

Recent advancements in lung cancer research: a narrative review

Background and Objective

Lung cancer remains the leading cause of cancer-related mortality worldwide, with a 5-year survival rate ranging from 10% to 20%. The majority of cases are categorized as non-small cell lung cancer (NSCLC) (80%) and small cell lung cancer (SCLC) (20%), with NSCLC being the more prevalent type. Tobacco use, particularly cigarette smoking, is a significant contributor to over 80% of lung cancer cases. Early diagnosis is challenging due to limitations in screening methods, resulting in many cases being identified only in advanced stages. Moreover, current treatment options often exhibit low efficacy, partly due to an inadequate understanding of the disease's pathogenesis. This narrative review aims to summarize recent discoveries and advancements in lung cancer research, focusing on improvements in diagnosis, treatment, and understanding of the disease.

Methods

A comprehensive literature review was performed utilizing the PubMed Central database to identify recent studies relevant to lung cancer. This review synthesizes findings from various research articles to provide a cohesive summary of advancements in the field.

Key Content and Findings

In the past decade, notable progress has been achieved in lung cancer research, particularly concerning diagnostics and treatment strategies. Novel therapeutic approaches, including immunotherapy and genomic-targeted therapies, have demonstrated promising results. Understanding the tumor microenvironment (TME) and the role of T lymphocytes has become crucial for developing effective treatments. Additionally, advancements in immune checkpoint inhibitors (ICIs) have shown potential in enhancing patient outcomes. Improvements in tumor detection technologies are also anticipated to facilitate earlier diagnosis, ultimately contributing to better survival rates.

Conclusions

Significant strides have been made in lung cancer research over the last ten years, particularly in diagnostics and treatment methodologies. Future research should prioritize exploring the TME, the function of T lymphocytes, and the efficacy of ICIs while continuing to innovate in tumor detection technologies. Such efforts are essential for enhancing treatment outcomes and improving the overall quality of life for lung cancer patients.

Unlocking the Potential of Chest MRI: Strategies for Establishing a Successful Practice

Chest MRI is a valuable tool for assessing chest structures, particularly when CT produces inconclusive results. MRI provides exceptional soft-tissue resolution and enables the determination of lesion location, size, and invasion into neighboring structures. Its applications span various clinical scenarios, including the differentiation of non-tumorous and tumorous conditions in the mediastinum or pleura, planning of surgical interventions and treatments for such tumors, evaluation of post-treatment recurrence, staging of lung cancer, and diagnosis of progressive massive fibrosis. Despite the technical hurdles posed by cardiac and respiratory motion, advancements in sequence and scan techniques have enabled high-quality chest MRI examinations to be conducted across diverse clinical settings. This pictorial essay aims to offer comprehensive resources and strategies for radiologists to integrate chest MRI into clinical practice and to overcome its present challenges.

A clinically-recommended MR whole lung imaging protocol using free-breathing 3D isotropic zero echo time sequence

RATIONALE AND OBJECTIVES

This study aimed to assess the feasibility and image quality of free-breathing 3D isotropic zero echo time (ZTE) whole-lung imaging and explore a clinically appropriate protocol for MR lung imaging.

MATERIALS AND METHODS

The study was approved by the local ethics committee. A total of thirty healthy volunteers were enrolled in this study from October 2022 to May 2023. Free-breathing pulmonary 3D isotropic ZTE scans were implemented with various acquisition planes and the number of excitations (NEX). ZTE images were evaluated by two radiologists for the overall Image quality and visibility of intrapulmonary structures as well as the signal-to-noise ratio (SNR) of the lung parenchyma. ZTE images with different acquisition parameters were compared. For preliminary clinical visual assessment, three patients with interstitial lung disease underwent both ZTE imaging and computed tomography (CT).

RESULTS

The overall image quality of the lung in healthy subjects was good to excellent. The visibilities of pulmonary arteries and bronchus were up to the 7th and 5th generation, respectively. The display of lung fissures was poor. The overall image quality, the visibility of the pulmonary artery, and lung fissures in the axial acquisition were better than in the coronal acquisition (P = 0.011, 0.008, 0.010, respectively) but not statistically different from those in the sagittal acquisition (all P > 0.05).

CONCLUSION

The free-breathing pulmonary ZTE is feasible and may serve as an alternative method in chest imaging. Either axial or sagittal ZTE image acquisition would be preferred in clinical practice.

Chest Magnetic Resonance Imaging: Advances and Clinical Care

Many promising study results as well as technical advances for chest magnetic resonance imaging (MRI) have demonstrated its academic and clinical potentials during the last few decades, although chest MRI has been used for relatively few clinical situations in routine clinical practice. However, the Fleischner Society as well as the Japanese Society of Magnetic Resonance in Medicine have published a few white papers to promote chest MRI in routine clinical practice. In this review, we present clinical evidence of the efficacy of chest MRI for 1) thoracic oncology and 2) pulmonary vascular diseases.

New developments in the imaging of lung cancer

Radiological and nuclear medicine methods play a fundamental role in the diagnosis and staging of patients with lung cancer. Imaging is essential in the detection, characterisation, staging and follow-up of lung cancer. Due to the increasing evidence, low-dose chest computed tomography (CT) screening for the early detection of lung cancer is being introduced to the clinical routine in several countries. Radiomics and radiogenomics are emerging fields reliant on artificial intelligence to improve diagnosis and personalised risk stratification. Ultrasound- and CT-guided interventions are minimally invasive methods for the diagnosis and treatment of pulmonary malignancies. In this review, we put more emphasis on the new developments in the imaging of lung cancer.

Lung Magnetic Resonance Imaging: Technical Advancements and Clinical Applications

ABSTRACT

Since lung magnetic resonance imaging (MRI) became clinically available, limited clinical utility has been suggested for applying MRI to lung diseases. Moreover, clinical applications of MRI for patients with lung diseases or thoracic oncology may vary from country to country due to clinical indications, type of health insurance, or number of MR units available. Because of this situation, members of the Fleischner Society and of the Japanese Society for Magnetic Resonance in Medicine have published new reports to provide appropriate clinical indications for lung MRI. This review article presents a brief history of lung MRI in terms of its technical aspects and major clinical indications, such as (1) what is currently available, (2) what is promising but requires further validation or evaluation, and (3) which developments warrant research-based evaluations in preclinical or patient studies. We hope this article will provide Investigative Radiology readers with further knowledge of the current status of lung MRI and will assist them with the application of appropriate protocols in routine clinical practice.

Area-Detector Computed Tomography for Pulmonary Functional Imaging

An area-detector CT (ADCT) has a 320-detector row and can obtain isotropic volume data without helical scanning within an area of nearly 160 mm. The actual-perfusion CT data within this area can, thus, be obtained by means of continuous dynamic scanning for the qualitative or quantitative evaluation of regional perfusion within nodules, lymph nodes, or tumors. Moreover, this system can obtain CT data with not only helical but also step-and-shoot or wide-volume scanning for body CT imaging. ADCT also has the potential to use dual-energy CT and subtraction CT to enable contrast-enhanced visualization by means of not only iodine but also xenon or krypton for functional evaluations. Therefore, systems using ADCT may be able to function as a pulmonary functional imaging tool. This review is intended to help the reader understand, with study results published during the last a few decades, the basic or clinical evidence about (1) newly applied reconstruction methods for radiation dose reduction for functional ADCT, (2) morphology-based pulmonary functional imaging, (3) pulmonary perfusion evaluation, (4) ventilation assessment, and (5) biomechanical evaluation.

State of the Art MR Imaging for Lung Cancer TNM Stage Evaluation

Since the Radiology Diagnostic Oncology Group (RDOG) report had been published in 1991, magnetic resonance (MR) imaging had limited clinical availability for thoracic malignancy, as well as pulmonary diseases. However, technical advancements in MR systems, such as sequence and reconstruction methods, and adjustments in the clinical protocol for gadolinium contrast media administration have provided fruitful results and validated the utility of MR imaging (MRI) for lung cancer evaluations. These techniques include: (1) contrast-enhanced MR angiography for T-factor evaluation, (2) short-time inversion recovery turbo spin-echo sequences as well as diffusion-weighted imaging (DWI) for N-factor assessment, and (3) whole-body MRI with and without DWI and with positron emission tomography fused with MRI for M-factor or TNM stage evaluation as well as for postoperative recurrence assessment of lung cancer or other thoracic tumors using 1.5 tesla (T) or 3T systems. According to these fruitful results, the Fleischner Society has changed its position to approve of MRI for lung or thoracic diseases. The purpose of this review is to analyze recent advances in lung MRI with a particular focus on lung cancer evaluation, clinical staging, and recurrence assessment evaluation.

Magnetic Resonance Imaging for Guidance and Follow-up of Thoracic Needle Biopsies and Thermal Ablations

Magnetic resonance imaging (MRI) is used for the guidance and follow-up of percutaneous minimally invasive interventions in many body parts. In the thorax, computed tomography (CT) is currently the most used imaging modality for the guidance and follow-up of needle biopsies and thermal ablations. Compared with CT, MRI provides excellent soft tissue contrast, lacks ionizing radiation, and allows functional imaging. The role of MRI is limited in the thorax due to the low hydrogen proton density and many air-tissue interfaces of the lung, as well as respiratory and cardiac motion. Here, we review the current experience of MR-guided thoracic needle biopsies and of MR-guided thermal ablations targeting lesions in the lung, mediastinum, and the chest wall. We provide an overview of MR-compatible biopsy needles and ablation devices. We detail relevant MRI sequences and their relative advantages and disadvantages for procedural guidance, assessment of complications, and long-term follow-up. We compare the advantages and disadvantages of CT and MR for thoracic interventions and identify areas in need of improvement and additional research.