Differentiation of central lung cancer from atelectasis: comparison of diffusion-weighted MRI with PET/CT

Feasibility of Multiparameter MRI-Guided Percutaneous Biopsy for Central Lung Lesions With Atelectasis

OBJECTIVE

To prospectively evaluate the feasibility, accuracy, and safety of multiparameter MRI-guided percutaneous biopsy using a 1T open MRI scanner for evaluating suspicious centrally located lung lesions with associated post-obstructive atelectasis.

MATERIALS AND METHODS

In this single-center study, MRI-guided percutaneous coaxial cutting biopsy was performed for 107 suspicious central lung lesions with associated post-obstructive atelectasis in 107 patients between July 2015 and December 2020. A fast T2-weighted imaging (T2WI)-turbo spin echo (TSE) sequence and an enhanced fast T1-weighted imaging (T1WI)-TSE sequence were used to identify, localize, and biopsy lung lesions, and diffusion-weighted imaging (DWI) was used as a supplementary sequence for identifying the lesion location. The final diagnosis was confirmed by surgical histopathology or clinical follow-up for a minimum of 24 months. The sensitivity, specificity, and accuracy for diagnosing lung malignancies were calculated, and the complications were recorded for each case.

RESULTS

Using multiparameter MRI, central lung lesions could be clearly distinguished from post-obstructive atelectasis in 96 patients (89.7%). The sensitivity, specificity, and accuracy of MRI-guided percutaneous biopsy for diagnosing lung malignancy was 97.0% (98/101), 100% (6/6), and 97.2% (104/107), respectively. Self-limited hemoptysis occurred in three patients. Pneumothorax occurred in five patients, of which none required pleural drainage. No serious procedure-related complications were observed.

CONCLUSION

As a technology that does not involve ionizing radiation, multiparameter MRI-guided percutaneous coaxial cutting biopsy is a safe and accurate diagnostic technique for evaluating centrally located lung lesions associated with post-obstructive atelectasis.

Evaluation of chest CT-scans following lung stereotactic ablative radiotherapy: Challenges and new insights

Stereotactic ablative radiotherapy (SABR) is increasingly used for the treatment of early-stage non-small cell lung cancer (ES-NSCLC) and for pulmonary metastases. In patients with ES-NSCLC, SABR is highly successful with reported 5-year local control rates of approximately 90%. However, the assessment of local control following lung SABR can be challenging as radiological changes arising from radiation-induced lung injury (RILI) can be observed in up to 90% of patients. These so-called 'benign' radiological changes evolve with time and are often asymptomatic. Several radiological and metabolic features have been explored to help distinguish RILI from local recurrences (LR). These include the Response Evaluation Criteria for Solid Tumors (RECIST), high-risk features (HRF's) and maximum standardized uptake value (SUVmax) on FDG-PET-CT. However, use of some of these approaches have poor predictive values and low specificity for recurrence. A proposed new workflow for the evaluation of post-lung SABR radiological changes will be reviewed which uses the presence of so-called 'actionable radiological features' to trigger changes to imaging schedules and identifies the need for a multidisciplinary board review. Furthermore, this critical review of post-lung SABR imaging will highlight current challenges, new insights, and unknowns in this field.

The Value of Contrast-Enhanced Ultrasound (CEUS) in the Evaluation of Central Lung Cancer with Obstructive Atelectasis

Purpose: To assess the diagnostic performance of contrast-enhanced ultrasound (CEUS) alongside contrast-enhanced computed tomography (CECT) in evaluating central lung cancer (CLC). Materials and Methods: From 2006 to 2022, 54 patients with CLC and obstructive atelectasis (OAT) underwent standardized examinations using CEUS in addition to CECT. The ability to differentiate CLC from atelectatic tissue in CECT and CEUS was categorized as distinguishable or indistinguishable. In CEUS, in distinguishable cases, the order of enhancement (time to enhancement) (OE; categorized as either an early pulmonary arterial [PA] pattern or a delayed bronchial arterial [BA] pattern of enhancement), the extent of enhancement (EE; marked or reduced), the homogeneity of enhancement (HE; homogeneous or inhomogeneous), and the decrease in enhancement (DE; rapid washout [<120 s] or late washout [≥120 s]) were evaluated. Results: The additional use of CEUS improved the diagnostic capability of CECT from 75.9% to 92.6% in differentiating a CLC from atelectatic tissue. The majority of CLC cases exhibited a BA pattern of enhancement (89.6%), an isoechoic reduced enhancement (91.7%), and a homogeneous enhancement (91.7%). Rapid DE was observed in 79.2% of cases. Conclusions: In cases of suspected CLC with obstructive atelectasis, the application of CEUS can be helpful in differentiating tumor from atelectatic tissue and in evaluating CLC.

Machine-Learning-Aided Prediction of Brain Metastases Development in Non-Small-Cell Lung Cancers

PURPOSE

Non-small-cell lung cancer (NSCLC) shows a high incidence of brain metastases (BM). Early detection is crucial to improve clinical prospects. We trained and validated classifier models to identify patients with a high risk of developing BM, as they could potentially benefit from surveillance brain MRI.

METHODS

Consecutive patients with an initial diagnosis of NSCLC from January 2011 to April 2019 and an in-house chest-CT scan (staging) were retrospectively recruited at a German lung cancer center. Brain imaging was performed at initial diagnosis and in case of neurological symptoms (follow-up). Subjects lost to follow-up or still alive without BM at the data cut-off point (12/2020) were excluded. Covariates included clinical and/or 3D-radiomics-features of the primary tumor from staging chest-CT. Four machine learning models for prediction (80/20 training) were compared. Gini Importance and SHAP were used as measures of importance; sensitivity, specificity, area under the precision-recall curve, and Matthew's Correlation Coefficient as evaluation metrics.

RESULTS

Three hundred and ninety-five patients compromised the clinical cohort. Predictive models based on clinical features offered the best performance (tuned to maximize recall: sensitivity∼70%, specificity∼60%). Radiomics features failed to provide sufficient information, likely due to the heterogeneity of imaging data. Adenocarcinoma histology, lymph node invasion, and histological tumor grade were positively correlated with the prediction of BM, age, and squamous cell carcinoma histology were negatively correlated. A subgroup discovery analysis identified 2 candidate patient subpopulations appearing to present a higher risk of BM (female patients + adenocarcinoma histology, adenocarcinoma patients + no other distant metastases).

CONCLUSION

Analysis of the importance of input features suggests that the models are learning the relevant relationships between clinical features/development of BM. A higher number of samples is to be prioritized to improve performance. Employed prospectively at initial diagnosis, such models can help select high-risk subgroups for surveillance brain MRI.

Magnetic resonance imaging for prospective assessment of local recurrence of non-small cell lung cancer after stereotactic body radiation therapy

OBJECTIVES

To evaluate multi-parametric MRI for distinguishing stereotactic body radiation therapy (SBRT) induced pulmonary fibrosis from local recurrence (LR).

MATERIALS AND METHODS

SBRT treated non-small cell lung cancer (NSCLC) patients suspected of LR by conventional imaging underwent MRI: T2 weighted, diffusion weighted imaging, dynamic contrast enhancement (DCE) with a 5-minute delayed sequence. MRI was reported as high or low suspicion of LR. Follow-up imaging ≥12 months or biopsy defined LR status as proven LR, no-LR or not-verified.

RESULTS

MRI was performed between 10/2017 and 12/2021, at a median interval of 22.5 (interquartile range 10.5-32.75) months after SBRT. Of the 20 lesions in 18 patients: 4 had proven LR, 10 did not have LR and 6 were not verified for LR due to subsequent additional local and/or systemic therapy. MRI correctly identified as high suspicion LR in all proven LR lesions and low suspicion LR in all confirmed no-LR lesions. All proven LR lesions (4/4) showed heterogeneous enhancement and heterogeneous T2 signal, as compared to the proven no-LR lesions in which 7/10 had homogeneous enhancement and homogeneous T2 signal. DCE kinetic curves could not predict LR status. Although lower apparent diffusion coefficient (ADC) values were seen in proven LR lesions, no absolute cut-off ADC value could determine LR status.

CONCLUSION

In this pilot study of NSCLC patients after SBRT, multi-parametric chest MRI was able to correctly determine LR status, with no single parameter being diagnostic by itself. Further studies are warranted.

Measurements of target volumes and organs at risk using DW‑MRI in patients with central lung cancer accompanied with atelectasis

Accurate imaging-based tumor delineation is crucial for guiding the radiotherapy treatments of various solid tumors. Currently, several imaging procedures, including diffusion-weighted magnetic resonance imaging (DW-MRI), intensified computed tomography and positron emission tomography are routinely used for targeted tumor delineation. However, the performance of these imaging procedures has not yet been comprehensively evaluated. In order to address this matter, the present study was conducted in an aim to assess the use of DW-MRI in guiding radiotherapy treatments, by comparing its performance to that of other imaging procedures. Specifically, the exposure dosages to organs at risk, including the lungs, heart and spinal mencord, were evaluated using various radiotherapy regimes. The findings of the present study demonstrated that DW-MRI is a non-invasive and cost-effective imaging procedure that can be used to reduce lung exposure doses, minimizing the risk of radiation pneumonitis. The data further demonstrate the immense potential of the DW-MRI procedure in the precision radiotherapy of lung cancers.

Reduction of inter-observer variability using MRI and CT fusion in delineating of primary tumor for radiotherapy in lung cancer with atelectasis

Purpose

To compare the difference between magnetic resonance imaging (MRI) and computed tomography (CT) in delineating the target area of lung cancer with atelectasis.

Method

A retrospective analysis was performed on 15 patients with lung cancer accompanied by atelectasis. All positioning images were transferred to Eclipse treatment planning systems (TPSs). Six MRI sequences (T1WI, T1WI+C, T1WI+C Delay, T1WI+C 10 minutes, T2WI, DWI) were registered with positioning CT. Five radiation oncologists delineated the tumor boundary to obtain the gross tumor volume (GTV). Conformity index (CI) and dice coefficient (DC) were used to measure differences among observers.

Results

The differences in delineation mean volumes, CI, and DC among CT and MRIs were significant. Multiple comparisons were made between MRI sequences and CT. Among them, DWI, T2WI, and T1WI+C 10 minutes sequences were statistically significant with CT in mean volumes, DC, and CI. The mean volume of DWI, T2WI, and T1WI+C 10 minutes sequence in the target area is significantly smaller than that on the CT sequence, but the consistency is higher than that of CT sequences.

Conclusions

The recognition of atelectasis by MRI was better than that by CT, which could reduce interobserver variability of primary tumor delineation in lung cancer with atelectasis. Among them, DWI, T2WI, T1WI+C 10 minutes may be a better choice to improve the GTV delineation of lung cancer patients with atelectasis.

Therapy response assessment of non-small cell lung cancer using dual-energy computed tomography iodine map

OBJECTIVE

To investigate feasibility of the quantitative parameters of dual-energy computed tomography (DECT) to assess therapy response in advanced non-small cell lung cancer (NSCLC) compared with the traditional enhanced CT parameters based on the Response Evaluation Criteria in Solid Tumors (RECIST) guidelines.

METHODS

Forty-five patients with unresectable locally advanced NSCLC who underwent DECT before and after chemotherapy or concurrent chemoradiotherapy (cCRT) were prospectively enrolled. By comparing baseline studies with follow-up, patients were divided into two groups according to RECIST guidelines as follows: disease control (DC, including partial response and stable disease) and progressive disease (PD). The diameter (D), attenuation, iodine concentration and normalized iodine concentration of arterial and venous phases (ICA, ICv, NICA, NICv) and the percentage of these changes pre- and post-therapy were measured and calculated. The Pearson correlation was used to analyze correlation between various quantitative parameters. The receiver operating characteristic (ROC) curves were used to evaluate accuracy of therapy response prediction.

RESULTS

The change percentages of Attenuation (Δ-Attenuation-A and Δ-Attenuation-V), IC (ΔICA and ΔICV) and NIC (ΔNICA and ΔNICV) pre- and post-therapy correlate with the change percentage of D (ΔD). Among these, ΔICA strongly correlates with ΔD (r = 0.793, P < 0.001). The areas under ROC curves generated using Δ-Attenuation-A, ΔICA, and ΔNICA are 0.796, 0.900, and 0.880 with the corresponding cutoff value of 9.096, -15.692, and -4.7569, respectively, which are significantly different (P < 0.001).

CONCLUSIONS

The quantitative parameters of DECT iodine map, especially iodine concentration, in arterial phase provides a new quantitative image marker to predict therapy response of patients diagnosed with advanced NSCLC.

Differentiating Central Lung Tumors from Atelectasis with Contrast-Enhanced CT-Based Radiomics Features

Objectives

To evaluate the utility of radiomics features in differentiating central lung cancers and atelectasis on contrast-enhanced computed tomography (CT) images. This study is retrospective.

Materials and Methods

In this study, 36 patients with central pulmonary cancer and atelectasis between July 2013 and June 2018 were identified. A total of 1,653 2D and 2,327 3D radiomics features were extracted from segmented lung cancers and atelectasis on contrast-enhanced CT. The refined features were investigated for usefulness in classifying lung cancer and atelectasis according to the information gain, and 10 models were trained based on these features. The classification model is trained and tested at the region level and pixel level, respectively.

Results

Among all the extracted features, 334 2D features and 1,507 3D features had an information gain (IG) greater than 0.1. The highest accuracy (AC) of the region classifiers was 0.9375. The best Dice score, Hausdorff distance, and voxel AC were 0.2076, 45.28, and 0.8675, respectively.

Conclusions

Radiomics features derived from contrast-enhanced CT images can differentiate lung cancers and atelectasis at the regional and voxel levels.

Geometric and Dosimetric Changes in Tumor and Lung Tissue During Radiotherapy for Lung Cancer With Atelectasis

Background and Purpose

This article retrospectively characterized the geometric and dosimetric changes in target and normal tissues during radiotherapy for lung cancer patients with atelectasis.

Materials and Methods

A total of 270 cone beam computed tomography (CBCT) scans of 18 lung patients with atelectasis were collected. The degree and time of resolution or expansion of the atelectasis were recorded. The geometric, dosimetric, and biological changes in the target and lung tissue were also quantified.

Results

There were two patients with expansion, four patients with complete regression, six patients with partial regression, and six patients with no change. The time of resolution or expansion varied. The tumor volume increased by 3.8% in the first seven fractions, then decreased from the 9th fraction, and by 33.4% at the last CBCT. In the LR direction, the average center of mass (COM), boundaries of the tumors gradually shifted mediastinally. In the AP direction, the COM of the tumors was shifted slightly in the posterior direction and then gradually shifted to the anterior direction; the boundaries of the tumors all moved mediastinally. In the SI direction, the COM of the tumors on the right side of the body was substantially shifted toward the head direction. The boundaries of the tumors varied greatly. D₂, D₉₈, D_mean, V₉₅, V₁₀₇, and TCP of the PTV were reduced during radiotherapy and were reduced to their lowest values during the last two fractions. The volume of the ipsilateral lung tended to increase gradually. The V₅, V₁₀, V₂₀, V₃₀, V₄₀, and NTCP of the total lung gradually increased with the fraction.

Conclusions

For most patients, regression of the atelectasis occurred, and the volume of the ipsilateral lung tended to increase while the tumor volume decreased, and the COM and boundary of the tumors shifted toward mediastinum, which caused an insufficient dose to the target and an overdose to the lungs. Regression or expansion may occur for any fraction, and it is therefore recommended that CBCT be performed at least every other day.

Mouse lung automated segmentation tool for quantifying lung tumors after micro-computed tomography

Unlike the majority of cancers, survival for lung cancer has not shown much improvement since the early 1970s and survival rates remain low. Genetically engineered mice tumor models are of high translational relevance as we can generate tissue specific mutations which are observed in lung cancer patients. Since these tumors cannot be detected and quantified by traditional methods, we use micro-computed tomography imaging for longitudinal evaluation and to measure response to therapy. Conventionally, we analyze microCT images of lung cancer via a manual segmentation. Manual segmentation is time-consuming and sensitive to intra- and inter-analyst variation. To overcome the limitations of manual segmentation, we set out to develop a fully-automated alternative, the Mouse Lung Automated Segmentation Tool (MLAST). MLAST locates the thoracic region of interest, thresholds and categorizes the lung field into three tissue categories: soft tissue, intermediate, and lung. An increase in the tumor burden was measured by a decrease in lung volume with a simultaneous increase in soft and intermediate tissue quantities. MLAST segmentation was validated against three methods: manual scoring, manual segmentation, and histology. MLAST was applied in an efficacy trial using a Kras/Lkb1 non-small cell lung cancer model and demonstrated adequate precision and sensitivity in quantifying tumor growth inhibition after drug treatment. Implementation of MLAST has considerably accelerated the microCT data analysis, allowing for larger study sizes and mid-study readouts. This study illustrates how automated image analysis tools for large datasets can be used in preclinical imaging to deliver high throughput and quantitative results.

Diffusion-weighted MRI improves response assessment after definitive radiotherapy in patients with NSCLC

Background

Computed tomography (CT) is the standard procedure for follow-up of non-small-cell lung cancer (NSCLC) after radiochemotherapy. CT has difficulties differentiating between tumor, atelectasis and radiation induced lung toxicity (RILT). Diffusion-weighted imaging (DWI) may enable a more accurate detection of vital tumor tissue. The aim of this study was to determine the diagnostic value of MRI versus CT in the follow-up of NSCLC.

Methods

Twelve patients with NSCLC stages I-III scheduled for radiochemotherapy were enrolled in this prospective study. CT with i.v. contrast agent and non enhanced MRI were performed before and 3, 6 and 12 months after treatment. Standardized ROIs were used to determine the apparent diffusion weighted coefficient (ADC) within the tumor. Tumor size was assessed by the longest longitudinal diameter (LD) and tumor volume on DWI and CT. RILT was assessed on a 4-point-score in breath-triggered T2-TSE and CT.

Results

There was no significant difference regarding LD and tumor volume between MRI and CT (p ≥ 0.6221, respectively p ≥ 0.25). Evaluation of RILT showed a very high correlation between MRI and CT at 3 (r = 0.8750) and 12 months (r = 0.903). Assessment of the ADC values suggested that patients with a good tumor response have higher ADC values than non-responders.

Conclusions

DWI is equivalent to CT for tumor volume determination in patients with NSCLC during follow up. The extent of RILT can be reliably determined by MRI. DWI could become a beneficial method to assess tumor response more accurately. ADC values may be useful as a prognostic marker.

Diffusion-Weighted Imaging in Oncology: An Update

To date, diffusion weighted imaging (DWI) is included in routine magnetic resonance imaging (MRI) protocols for several cancers. The real additive role of DWI lies in the "functional" information obtained by probing the free diffusivity of water molecules into intra and inter-cellular spaces that in tumors mainly depend on cellularity. Although DWI has not gained much space in some oncologic scenarios, this non-invasive tool is routinely used in clinical practice and still remains a hot research topic: it has been tested in almost all cancers to differentiate malignant from benign lesions, to distinguish different malignant histotypes or tumor grades, to predict and/or assess treatment responses, and to identify residual or recurrent tumors in follow-up examinations. In this review, we provide an up-to-date overview on the application of DWI in oncology.

A primary analysis on measuring repeatability of the maximum diameter between CT and MR imaging for lung cancers

OBJECTIVE

To investigate the measurement reproducibility of the maximum diameter on MRI routine sequence (T1WI, T2WI, DWI) and CT in peripheral and central lung cancer, and to provide reference standard for evaluating treatment responses for lung cancer.

METHODS

53 patients with lung cancer underwent CT and 3.0T MR scanning. The maximum diameter was measured according to the RECIST1.1 standard on images of CT (lung and enhanced mediastinal window), MRI T2-BLADE, axial T1-VIBE and DWIb0, DWIb300, DWIb800, respectively. The reproducibility of the diameters was analyzed with intraclass correlation coefficient (ICC), and the distribution of measurement points with the Bland-Altman method. The difference analysis was assessed by paired samples t-test and nonparametric rank sum test, P < 0.05 is considered statistically significant.

RESULTS

Reproducibility of diameters derived from routine MRI and CT was good (ICC > 0.75). For peripheral lung cancer, there was no significant difference in diameters between CT and MRI. While for central lung cancer, there was significant difference in diameters measured between using CT and each MRI sequence. However, the diameters derived from T1-VIBE and T2-BLADE were not significantly different from all DWI sequences.

CONCLUSIONS

For peripheral lung cancer, the measurement on CT and routine MRI sequences can potentially replace each other after comprehensive consideration of examination purposes, but for central lung cancer, alternative use of CT and MRI in evaluating treatment responses for lung cancer should needs extra attention. The diameter measurement of lung cancer on DWI is consistent with that on T1WI and T2WI, suggesting that DWI can provide functional and morphological information.

Pulmonary Function Diagnosis Based on Respiratory Changes in Lung Density With Dynamic Flat-Panel Detector Imaging: An Animal-Based Study

OBJECTIVES

The aims of this study were to address the relationship between respiratory changes in image density of the lungs and tidal volume, to compare the changes between affected and unaffected lobes, and to apply this new technique to the diagnosis of atelectasis.

MATERIALS AND METHODS

Our animal care committee approved this prospective animal study. Sequential chest radiographs of 4 pigs were obtained under respiratory control with a ventilator using a dynamic flat-panel detector system. Porcine models of atelectasis were developed, and the correlation between the tidal volume and changes in pixel values measured in the lungs were analyzed. The mean difference in respiratory changes in pixel values between both lungs was tested using paired t tests. To facilitate visual evaluation, respiratory changes in pixel values were visualized in the form of a color display, that is, as changes in color scale.

RESULTS

Average pixel values in the lung regions changed according to forced respiration. High linearity was observed between changes in pixel values and tidal volume in the normal models (r = 0.99). Areas of atelectasis displayed significantly reduced changes in pixel values (P < 0.05). Of all atelectasis models with air trapping and air inflow restriction, 92.7% (19/20) were visualized as color-defective or color-marked areas on functional images, respectively.

CONCLUSION

Dynamic chest radiography allows for the relative evaluation of tidal volume, the detection of ventilation defects in the lobe unit, and a differential diagnosis between air trapping and air inflow restriction, based on respiratory changes in image density of the lungs, even without the use of contrast media.

Lung cancer imaging methods in China from 2005 to 2014: A national, multicenter study

BACKGROUND

The study was conducted to examine changes in diagnostic and staging imaging methods for lung cancer in China over a 10-year period and to determine the relationships between such changes and socioeconomic development.

METHODS

This was a hospital-based, nationwide, multicenter retrospective study of primary lung cancer cases. The data were extracted from the 10-year primary lung cancer databases at eight tertiary hospitals from various geographic areas in China. The chi-squared test was used to assess the differences and the Cochran-Armitage trend test was used to estimate the trends of changes.

RESULTS

A total of 7184 lung cancer cases were analyzed. Over the 10-year period, the utilization ratio of diagnostic imaging methods, such as chest computed tomography (CT) and chest magnetic resonance imaging (MRI), increased from 65.79% to 81.42% and from 0.73% to 1.96%, respectively, while the utilization ratio of chest X-ray declined from 50.15% to 30.93%. Staging imaging methods, such as positron emission tomography-CT, neck ultrasound, brain MRI, bone scintigraphy, and bone MRI increased from 0.73% to 9.29%, 22.95% to 47.92%, 8.77% to 40.71%, 42.40% to 62.22%, and 0.88% to 4.65%, respectively; abdominal ultrasound declined from 83.33% to 59.9%. These trends were more notable in less developed areas than in areas with substantial economic development.

CONCLUSION

Overall, chest CT was the most common radiological diagnostic method for lung cancer in China. Imaging methods for lung cancer tend to be used in a diverse, rational, and regionally balanced manner.

Optimizing diffusion-weighted magnetic resonance imaging for evaluation of lung tumors: A comparison of respiratory triggered and free breathing techniques

Purpose

The aim of this study was to compare respiratory-triggered (RT) and free breathing (FB) diffusion weighted imaging (DWI) techniques regarding apparent diffusion coefficient (ADC) measurements and repeatability in non-squamous non-small cell lung cancer (NSCLC) measuring the total tumor volume.

Material and Methods

A total of 57 magnetic resonance imaging (MRI) examinations were analyzed. DWI was obtained by a single-shot spin-echo echo-planar imaging sequence, and for each MRI examination 2 consecutive RT and 2 consecutive FB DWI sequences were performed. Two radiologists independently read the images and made measurements. For each tumor the mean ADC value of the whole tumor volume was calculated. The difference in mean ADCs between FB and RT DWI was evaluated using the paired-sample t-test. The repeatability of ADC measurements related to imaging method was evaluated by intra class correlations (ICC) for each of the FB and RT DWI pairs.

Results

There were no significant differences in mean ADCs between FB and RT (Reader 1 p = 0.346, Reader 2 p = 0.583). The overall repeatability of ADC measurement was good for both acquisition methods, with ICCs > 0.9. Subgroup analysis showed somewhat poorer repeatability in small tumors (50 ml or less) and tumors in the lower lung zones for the RT acquisition, with ICC as low as 0.72.

Conclusions

No difference in ADC measurement or repeatability between FB and RT DWI in whole lesion ADC measurements of adenocarcinomas in the lung was demonstrated. The results imply that in this setting the FB acquisition method is accurate and possibly more robust than the RT acquisition technique.

Imaging of Radiation Treatment of Lung Cancer

Radiation therapy is an important modality in the treatment of patients with lung cancer. Recent advances in delivering radiotherapy were designed to improve loco-regional tumor control by focusing higher doses on the tumor. More sophisticated techniques in treatment planning include 3-dimensional conformal radiation therapy, intensity-modulated radiotherapy, stereotactic body radiotherapy, and proton therapy. These methods may result in nontraditional patterns of radiation injury and various radiologic appearances that can be mistaken for recurrence, infection and other lung diseases. Knowledge of radiological manifestations, awareness of new radiation delivery techniques and correlation with radiation treatment plans are essential in order to correctly interpret imaging in these patients.

Contrast-enhanced ultrasound for needle biopsy of central lung cancer with atelectasis

PURPOSE

Contrast-enhanced ultrasound (CEUS) can distinguish between central lung cancer and atelectatic lung tissue. The aim of this study was to explore the clinical value of CEUS for biopsy in patients with central lung cancer with obstructive atelectasis.

METHODS

One hundred and twelve patients were selected and CEUS was performed to display central lung cancer and atelectatic lung tissue. The front edge of central lung cancer was punctured with a needle, avoiding the necrotic area, under the guidance of CEUS.

RESULTS

All of the 112 lesions were diagnosed with a clear central lung cancer mass and atelectatic lung tissue. In 104 cases, the central lung cancer mass presented with a "slow-in and fast-out" pattern compared to atelectatic lung tissue. In eight cases, the central lung cancer mass presented with a "fast-in and fast-out" pattern compared to atelectatic lung tissue. The mean number of punctures was 2.6, and the success rate of puncture biopsy was 98%. Of the 112 patients, six cases had hemoptysis during the procedure and 10 patients had bloody sputum in the postoperative period. No complications were found in the other cases.

CONCLUSION

CEUS has important clinical value for needle biopsy of central lung cancer with atelectasis.

Implementation of diffusion-weighted magnetic resonance imaging in target delineation of central lung cancer accompanied with atelectasis in precision radiotherapy

Radiotherapy, particularly the target delineation of cancer based on scanned images, plays a key role in the planning of cancer treatment. Recently, diffusion-weighted magnetic resonance imaging (DW-MRI) has emerged as a prospective superior procedure compared with intensified computed tomography (CT) and positron emission tomography (PET) in the target delineation of cancer. However, the implication of DW-MRI in lung cancer, the leading cause of cancer-associated mortality worldwide, has not been extensively evaluated. In the present study, the gross target volumes of lung cancer masses delineated using the DW-MRI, CT and PET procedures were compared in a pairwise manner in a group of 27 lung cancer patients accompanied with atelectasis of various levels. The data showed that compared with CT and PET procedures, DW-MRI has a more precise delineation of lung cancer while exhibiting higher reproducibility. Together with the fact that it is non-invasive and cost-effective, these data demonstrate the great application potential of the DW-MRI procedure in cancer precision radiotherapy.

Current Controversies in Lung Cancer Staging

Lung cancer remains the leading cause of cancer-related mortality in the United States, and accurate staging of disease plays an important role in the formulation of treatment strategies and optimization of patient outcomes. The International Association for the Study of Lung Cancer has recently proposed changes to the upcoming eighth edition of the tumor, node, and metastasis (TNM-8) staging system used for lung cancer. This revised classification is based on significant differences in patient survival identified on analysis of a new large international database of lung cancer cases. Key changes include: further modifications to the T descriptors based on 1 cm increments in tumor size; grouping of tumors resulting in partial or complete lung atelectasis/pneumonitis; grouping of tumors involving a main bronchus with respect to distance from the carina; reassignment of diaphragmatic invasion; elimination of mediastinal pleural invasion as a descriptor; and further subdivision of metastatic disease into distinct descriptors based on the number of extrathoracic metastases and involved organs. Because of these changes, several new stage groups have been developed, and others have shifted. Although TNM-8 represents continued improvement upon modifications previously made to the staging system, reflecting an evolving understanding of tumor behavior and patient management, several limitations and unaddressed issues persist. Understanding the proposed revisions to TNM-8 and awareness of key limitations and potential controversial issues still unaddressed will allow radiologists to accurately stage patients with lung cancer and optimize treatment decisions.

Is it better to include necrosis in apparent diffusion coefficient (ADC) measurements? The necrosis/wall ADC ratio to differentiate malignant and benign necrotic lung lesions: Preliminary results

PURPOSE

To determine whether the use of necrosis/wall apparent diffusion coefficient (ADC) ratios in the differentiation of necrotic lung lesions is more reliable than measuring the wall alone.

MATERIALS AND METHODS

In this retrospective study, a total of 76 patients (54 males and 22 females, 71% vs. 29%, with a mean age of 53 ± 18 years, range, 18-84) were enrolled, 33 of whom had lung carcinoma and 43 had a benign necrotic lung lesion. A 3T scanner was used. The calculation of the necrosis/wall ADC ratio was based on ADC values measured from necrosis and the wall of the lesions by diffusion-weighted imaging (DWI). Statistical analyses were performed with the independent samples t-test and receiver operating characteristic analysis. Intraobserver and interobserver reliability were calculated for ADC values of wall and necrosis.

RESULTS

The mean necrosis/wall ADC ratio was 1.67 ± 0.23 for malignant lesions and 0.75 ± 0.19 for benign lung lesions (P < 0.001). To estimate malignancy the area under the curve (AUC) values for necrosis ADC, wall ADC, and the necrosis/wall ADC ratio were 0.720, 0.073, and 0.997, respectively. A wall/necrosis ADC ratio cutoff value of 1.12 demonstrated a 100% sensitivity and 98% specificity in the estimation of malignancy. Positive predictive value was 100%, and negative predictive value 98% and diagnostic accuracy 99%. There was a good intraobserver and interobserver reliability for wall and necrosis.

CONCLUSION

The necrosis/wall ADC ratio appears to be a reliable and promising tool for discriminating lung carcinoma from benign necrotic lung lesions than measuring the wall alone.

LEVEL OF EVIDENCE

4 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2017;46:1001-1006.

Magnetic resonance (MR) imaging for tumor staging and definition of tumor volumes on radiation treatment planning in nonsmall cell lung cancer: A prospective radiographic cohort study of single center clinical outcome

We investigate the impact of magnetic resonance (MR) on the staging and radiotherapy planning for patients with nonsmall cell lung cancer (NSCLC).A total of 24 patients with NSCLC underwent MRI, which was fused with radiotherapy planning CT using rigid registration. Gross tumor volume (GTV) was delineated not only according to CT image alone (GTVCT), but also based on both CT and MR image (GTVCT/MR). For each patient, 2 conformal treatment plans were made according to GTVCT and GTVCT/MR, respectively. Dose-volume histograms (DVH) for lesion and normal organs were generated using both GTVCT and GTVCT/MR treatment plans. All patients were irradiated according to GTVCT/MR plan.Median volume of the GTVCT/MR and GTVCT were 105.42 cm and 124.45 cm, respectively, and the mean value of GTVCT/MR was significantly smaller than that of GTVCT (145.71 ± 145.04 vs 174.30 ± 150.34, P < 0.01). Clinical stage was modified in 9 patients (37.5%). The objective response rate (ORR) was 83.3% and the l-year overall survival (OS) was 87.5%.MR is a useful tool in radiotherapy treatment planning for NSCLC, which improves the definition of tumor volume, reduces organs at risk dose and does not increase the local recurrence rate.

Magnetic resonance imaging in lung: a review of its potential for radiotherapy

MRI has superior soft-tissue definition compared with existing imaging modalities in radiation oncology; this has the added benefit of functional as well as anatomical imaging. This review aimed to evaluate the current use of MRI for lung cancer and identify the potential of a MRI protocol for lung radiotherapy (RT). 30 relevant studies were identified. Improvements in MRI technology have overcome some of the initial limitations of utilizing MRI for lung imaging. A number of commercially available and novel sequences have shown image quality to be adequate for the detection of pulmonary nodules with the potential for tumour delineation. Quantifying tumour motion is also feasible and may be more representative than that seen on four-dimensional CT. Functional MRI sequences have shown correlation with flu-deoxy-glucose positron emission tomography (FDG-PET) in identifying malignant involvement and treatment response. MRI can also be used as a measure of pulmonary function. While there are some limitations for the adoption of MRI in RT-planning process for lung cancer, MRI has shown the potential to compete with both CT and PET for tumour delineation and motion definition, with the added benefit of functional information. MRI is well placed to become a significant imaging modality in RT for lung cancer.

Performance of DWI in the Nodal Characterization and Assessment of Lung Cancer: A Meta-Analysis

OBJECTIVE

The purpose of this study is to assess the diagnostic performance of DWI in the N stage assessment of patients with lung cancer.

MATERIALS AND METHODS

The PubMed, EMBASE, Cochrane Library, Web of Science, and EBSCO English-language databases and two Chinese-language databases were searched for eligible studies. On the basis of the data extracted from included studies, we determined the pooled sensitivity and specificity, calculated the positive and negative likelihood ratios, and constructed summary ROC curves. In addition, we also performed threshold effect analysis, metaregression analysis, subgroup analysis, and publication bias analysis to explain the source of heterogeneity.

RESULTS

A total of 18 articles involving 1116 patients met the inclusion criteria. On a per-patient basis, the pooled sensitivity and specificity estimates of DWI were 0.68 (95% CI, 0.63-0.73) and 0.92 (95% CI, 0.90-0.94), respectively. On a per-lesion basis, the corresponding estimates were 0.72 (95% CI, 0.69-0.75) for sensitivity and 0.96 (95% CI, 0.95-0.96) for specificity. Only the analysis method (quantitative vs qualitative) affected the diagnostic accuracy on the basis of subgroup and metaregression analysis.

CONCLUSION

Current evidence suggests that DWI is beneficial in the nodal assessment of patients with lung cancer, and it is necessary to conduct high-quality prospective studies regarding the use of DWI in detecting metastatic lymph nodes of lung cancer to determine its true value.

A Case of Apparent Lung Adenocarcinoma Size Reduction During Steroid Therapy

Spontaneous regression of lung cancer is a rare phenomenon. We described a case of lung adenocarcinoma size reduction during steroid therapy. In this case, histopathologic findings showed a lung adenocarcinoma surrounded by obstructive pneumonia and inflammatory cell infiltration. Steroid use might have diminished the inflammatory response around the lung cancer, resulting in the apparent shrinkage of the lung cancer. This phenomenon is a potential pitfall in lung cancer diagnosis.

Apparent diffusion coefficient values of diffusion-weighted imaging for distinguishing focal pulmonary lesions and characterizing the subtype of lung cancer: a meta-analysis

OBJECTIVES

The potential performance of apparent diffusion coefficient (ADC) values for distinguishing malignant and benign pulmonary lesions, further characterizing the subtype of lung cancer was assessed.

METHODS

PubMed, EMBASE, Cochrane Library, EBSCO, and three Chinese databases were searched to identify eligible studies on diffusion-weighted imaging (DWI) of focal pulmonary lesions. ADC values of malignant and benign lesions were extracted by lesion type and statistically pooled based on a linear mixed model. Further analysis for subtype of lung cancer was also performed. The methodological quality was assessed using the quality assessment of diagnostic accuracy studies tool.

RESULTS

Thirty-four articles involving 2086 patients were included. Malignant pulmonary lesions have significantly lower ADC values than benign lesions [1.21 (95% CI, 1.19-1.22) mm(2)/s vs. 1.76 (95% CI, 1.72-1.80) mm(2)/s; P < 0.05]. There is a significant difference between ADC values of small cell lung cancer and non-small cell lung cancer (P < 0.05), while the differences were not significant among histological subtypes of lung cancer. The methodological quality was relatively high, and the data points from Begg's test indicated that there was probably no obvious publication bias.

CONCLUSIONS

The ADC value is helpful for distinguishing malignant and benign pulmonary lesions and provides a promising method for differentiation of SCLC from NSCLC.

KEY POINTS

• This meta-analysis assesses the role of DWI in pulmonary lesions. • Differentiation and classification subtype of lung cancer is essential for treatment decision-making. • ADC values can help distinguish between malignant and benign lesions. • ADC values might help characterize the subtype of lung cancer.

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.

Lung cancer imaging

Lung cancer remains the leading cause of cancer-related deaths in the US. Imaging plays an important role in the diagnosis, staging, and follow-up evaluation of patients with lung cancer. With recent advances in technology, it is important to update and standardize the radiological practices in lung cancer evaluation. In this article, the authors review the main clinical applications of different imaging modalities and the most common radiological presentations of lung cancer.

Diffusion-weighted magnetic resonance imaging for assessment of lung lesions: repeatability of the apparent diffusion coefficient measurement

PURPOSE

To establish repeatability of apparent diffusion coefficients (ADCs) acquired from free-breathing diffusion-weighted magnetic resonance imaging (DW-MRI) in malignant lung lesions and investigate effects of lesion size, location and respiratory motion.

METHODS

Thirty-six malignant lung lesions (eight patients) were examined twice (1- to 5-h interval) using T1-weighted, T2-weighted and axial single-shot echo-planar DW-MRI (b = 100, 500, 800 s/mm(2)) during free-breathing. Regions of interest around target lesions on computed b = 800 s/mm(2) images by two independent observers yielded ADC values from maps (pixel-by-pixel fitting using all b values and a mono-exponential decay model). Intra- and inter-observer repeatability was assessed per lesion, per patient and by lesion size (> or <2 cm) or location.

RESULTS

ADCs were similar between observers (mean ± SD, 1.15 ± 0.28 × 10(-3) mm(2)/s, observer 1; 1.15 ± 0.29 × 10(-3) mm(2)/s, observer 2). Intra-observer coefficients of variation of the mean [median] ADC per lesion and per patient were 11% [11.4%], 5.7% [5.7%] for observer 1 and 9.2% [9.5%], 3.9% [4.7%] for observer 2 respectively; inter-observer values were 8.9% [9.3%] (per lesion) and 3.0% [3.7%] (per patient). Inter-observer coefficient of variation (CoV) was greater for lesions <2 cm (n = 20) compared with >2 cm (n = 16) (10.8% vs 6.5% ADCmean, 11.3% vs 6.7% ADCmedian) and for mid (n = 14) vs apical (n = 9) or lower zone (n = 13) lesions (13.9%, 2.7%, 3.8% respectively ADCmean; 14.2%, 2.8%, 4.7% respectively ADCmedian).

CONCLUSION

Free-breathing DW-MRI of whole lung achieves good intra- and inter-observer repeatability of ADC measurements in malignant lung tumours.

KEY POINTS

• Diffusion-weighted MRI of the lung can be satisfactorily acquired during free-breathing • DW-MRI demonstrates high contrast between primary and metastatic lesions and normal lung • Apparent diffusion coefficient (ADC) measurements in lung tumours are repeatable and reliable • ADC offers potential in assessing response in lung metastases in clinical trials.