Evaluation of postoperative lung volume and perfusion changes by dual-energy computed tomography in patients with lung cancer

Dual-Energy CT in Oncologic Imaging

Dual-energy CT (DECT) is an innovative technology that is increasingly widespread in clinical practice. DECT allows for tissue characterization beyond that of conventional CT as imaging is performed using different energy spectra that can help differentiate tissues based on their specific attenuation properties at different X-ray energies. The most employed post-processing applications of DECT include virtual monoenergetic images (VMIs), iodine density maps, virtual non-contrast images (VNC), and virtual non-calcium (VNCa) for bone marrow edema (BME) detection. The diverse array of images obtained through DECT acquisitions offers numerous benefits, including enhanced lesion detection and characterization, precise determination of material composition, decreased iodine dose, and reduced artifacts. These versatile applications play an increasingly significant role in tumor assessment and oncologic imaging, encompassing the diagnosis of primary tumors, local and metastatic staging, post-therapy evaluation, and complication management. This article provides a comprehensive review of the principal applications and post-processing techniques of DECT, with a specific focus on its utility in managing oncologic patients.

Patterns of Postoperative Changes in Lung Volume and Perfusion Assessed by Dual-Energy CT: Comparison of Lobectomy and Limited Resection

BACKGROUND. Pulmonary function tests (PFTs) and perfusion scintigraphy have limited utility for evaluating postoperative changes in regional pulmonary function after lung cancer resection surgery. OBJECTIVE. The purpose of this study is to compare postoperative changes in lung volume and perfusion, as assessed by dual-energy CT (DECT), between patients undergoing surgical resection of lung cancer by lobectomy versus limited resection as well as to assess associations between such changes and the lobar location of the resected tumor. METHODS. This study entailed a retrospective post hoc analysis of a prospective study that enrolled patients awaiting lung cancer resection surgery between March 2019 and February 2020. Eighty-one patients (38 men and 43 women; mean age, 60.5 ± 8.9 [SD] years), 43 of whom underwent lobectomy and 38 of whom underwent limited resection, were included. Patients underwent thoracic DECT and PFT evaluation preoperatively and at 6 months postoperatively. Pulmonary lobes were segmented. Lobar lung volume and lung perfusion ratios (both relative to whole-lung values) were computed. Perfusion measures reflected DECT-derived iodine content. Patients completed 6-month postoperative quality-of-life (QOL) questionnaires. RESULTS. Patients undergoing lobectomy, compared with those undergoing limited resection, had greater increases in the lung volume ratio of the ipsilateral nonresected lobe(s) (mean, 42.3% ± 24.2% [SD] vs 22.9% ± 13.2%, p < .001) and the contralateral lung (mean, 14.6% ± 14.0% vs 6.4% ± 6.9%, p = .002) as well as greater increases in the lung perfusion ratio of the ipsilateral nonresected lobe(s) (mean, 39.9% ± 20.7% [SD] vs 22.8% ± 17.8%, p < .001) and the contralateral lung (mean, 20.9% ± 9.4% vs 4.3% ± 5.6%, p < .001). In patients with right lower lobe tumors, the largest postoperative increases in the lung volume ratio were in the right middle lobe in those undergoing lobectomy (mean, 44.1% ± 21.0%) and limited resection (mean, 24.6% ± 14.5%), whereas the largest postoperative increase in the lung perfusion ratio was in the left lower lobe in those undergoing lobectomy (mean, 53.9% ± 8.6%) and in the right middle lobe in those undergoing limited resection (mean, 32.5% ± 24.1%). Otherwise, the largest increases in lung volume and perfusion ratios occurred in the ipsilateral nonresected lobes (vs the contra-lateral lobes), regardless of the operative approach used and the lobar location. Changes in the lung volume and perfusion ratios in the ipsilateral lobe(s) and the contralateral lung showed weak correlations with certain quality-of-life scores (e.g., for role functioning: ρ = 0.234-0.279 [volume] and -0.233 to -0.284 [perfusion]). CONCLUSION. DECT depicts patterns of lung volume and perfusion changes after lung cancer surgery, depending on the surgical approach (lobectomy vs limited resection) used and the lobar location of the tumor. CLINICAL IMPACT. DECT-derived metrics can help understand variable physiologic impacts of lung cancer resection surgeries.

A fully automatic segmentation pipeline of pulmonary lobes before and after lobectomy from computed tomography images

BACKGROUND AND OBJECTIVE

Lobectomy is a curative treatment for localized lung cancer. The study aims to construct an automatic pipeline for segmenting pulmonary lobes before and after lobectomy from CT images.

MATERIALS AND METHODS

Six datasets (D1 to D6) of 865 CT scans were collected from two hospitals and public resources. Four nnU-Net-based segmentation models were trained. A lobectomy classification was proposed to automatically recognize the category of the input CT images: before lobectomy or one of five types after lobectomy. Finally, the lobe segmentation before and after lobectomy was realized by integrating the four models and lobectomy classification. The dice similarity coefficient (DSC), 95% Hausdorff distance (HD₉₅) and average symmetric surface distance (ASSD) were used to evaluate the segmentations.

RESULTS

The pre-operative model achieved an average DSC of 0.964, 0.929, 0.934, and 0.891 in the four datasets. In D1 and D2, the average HD₉₅ was 4.18 and 7.74 mm and the average ASSD was 0.86 and 1.32 mm, respectively. The lobectomy classification achieved an accuracy of 100%. After lobectomy, an average DSC of 0.973 and 0.936, an average HD₉₅ of 2.70 and 6.92 mm, an average ASSD of 0.57 and 1.78 mm were obtained in D1 and D2, respectively. The postoperative segmentation pipeline outperformed other counterparts and training strategies.

CONCLUSIONS

The proposed pipeline can automatically segment pulmonary lobes before and after lobectomy from CT images and be applied to manage patients with lung cancer after lobectomy.

Complication and lung function impairment prediction using perfusion and computed tomography air trapping (CLIPPCAIR): protocol for the development and validation of a novel multivariable model for the prediction of post-resection lung function

Background

Recent advancements in computed tomography (CT) scanning and post processing have provided new means of assessing factors affecting respiratory function. For lung cancer patients requiring resection, and especially those with respiratory comorbidities such as chronic obstructive pulmonary disease (COPD), the ability to predict post-operative lung function is a crucial step in the lung cancer operability assessment. The primary objective of the CLIPPCAIR study is to use novel CT data to develop and validate an algorithm for the prediction of lung function remaining after pneumectomy/lobectomy.

Methods

Two sequential cohorts of non-small cell lung cancer patients requiring a pre-resection CT scan will be recruited at the Montpellier University Hospital, France: a test population (N=60) on which predictive models will be developed, and a further model validation population (N=100). Enrolment will occur during routine pre-surgical consults and follow-up visits will occur 1 and 6 months after pneumectomy/lobectomy. The primary outcome to be predicted is forced expiratory volume in 1 second (FEV1) six months after lung resection. The baseline CT variables that will be used to develop the primary multivariable regression model are: expiratory to inspiratory ratios of mean lung density (MLD_e/i for the total lung and resected volume), the percentage of voxels attenuating at less than ‒950 HU (PVOX_‒950 for the total lung and resected volume) and the ratio of iodine concentrations for the resected volume over that of the total lung. The correlation between predicted and real values will be compared to (and is expected to improve upon) that of previously published methods. Secondary analyses will include the prediction of transfer factor for carbon monoxide (TLCO) and complications in a similar fashion. The option to explore further variables as predictors of post-resection lung function or complications is kept open.

Discussion

Current methods for estimating post-resection lung function are imperfect and can add assessments (such as scintigraphy) to the pre-surgical workup. By using CT imaging data in a novel fashion, the results of the CLIPPCAIR study may not only improve such estimates, it may also simplify patient pathways.

Trial registration

Clinicaltrials.gov (NCT03885765).

A preliminary study identifies early postoperative lung volume changes in patients with non-small cell lung cancer following video-assisted thoracic surgery using CT volumetry

The present study aimed to investigate the changes in early postoperative lung volume in patients with non-small cell lung cancer (NSCLC) following video-assisted thoracic surgery (VATS) and to analyze the effects of the clinical characteristics on the lung volume of the patients. Therefore, 38 patients with NSCLC, who planned to undergo VATS at the Department of Thoracic Surgery, The Affiliated Hospital of Guizhou Medical University in June 2019, were enrolled into the present study. The clinical and computed tomography (CT) scan data from the patients was prospectively collected within 1 week preoperatively, and at 1, 3 and 6 months following surgery, then subsequently analyzed. A total of 34 patients successfully completed follow-up and were included in the datasets. The results showed that the volume of the right lung was larger compared with that in the left one, at each observational time point. The whole, right and left lung held the same trendline of volume changes, which was sharply decreased during the first postoperative month, increased quickly over the next 3 months, and slowly increased from months 3 to 6. There were 7 patients, whose whole lung volume was increased at 6 months following surgery compared with that preoperatively. In addition, significant differences were observed between males and females in the whole, right and left lung volume. However, the differences on the postoperative net expansion volume of the whole lung were not significant among sex, age, body mass index (BMI), smoking status and surgical side subgroups. The early changes of the postoperative lung volume were not linear, since the lung volume was significantly reduced during the first postoperative month, quickly increased in the next 3 months, and slowly increased from months 3 to 6. Sex, age, BMI, smoking status and surgical sides was not found to affect the postoperative volume and net expansion of the whole lung following VATS lobectomy.

How preserved regional pulmonary function after thoracoscopic segmentectomy in clinical stage I non-small cell lung cancers in right upper lobe

OBJECTIVE

To investigate the efficacy of regional respiratory preservation after pulmonary resection for clinical stage I non-small cell lung cancer (NSCLC) in right upper lobe.

METHODS

This retrospective study analysed patients with clinical stage I NSCLC who underwent open thoracotomy lobectomy (OTL, n = 45), thoracoscopic lobectomy (TSL, n = 137), and thoracoscopic segmentectomy (TSS, n = 37) in right upper lobe. The forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) were examined at 3 and 6-12 months after the operation. The pre- and post-operative lung volumes were evaluated by three-dimensional reconstructed computed tomography. The rates of post- and pre-operative FVC, FEV1, and lung volumes were compared amongst the three groups.

RESULTS

Significant differences were found in both FVC and FEV1 at 6-12 months between TSL and OTL (p < 0.01 and p = 0.02, respectively). The respiratory recovery rates of FVC and FEV1 at 6-12 months were significantly higher in TSS (98.6% ± 1.52% and 96.5% ± 1.66%) than in TSL (93.4% ± 0.79% and 90.4% ± 0.86%) (FVC: p < 0.01 and FEV1: p < 0.01). The volumetric changes were greater in TSL than in TSS for the right middle lobe (19.6% ± 2.39% and 9.59% ± 4.66%; p = 0.06) and right lower lobe (48.3% ± 2.84% and 27.9% ± 5.47%; p < 0.01) CONCLUSION: TSS might be superior to TSL or OTL depending on the moderate expansion of the remaining right lobes.

Preoperative assessment of lung nodules and lobar function by spectral detector computed tomography

Conventional computed tomography (CT) plays an important role in detection of lung nodules. However, further characterization is usually limited requiring additional imaging and invasive work up. Spectral Detector CT (SDCT) is an upcoming novel modality that not only allows morphological evaluation but also provides insight into prediction of malignant behavior of lung nodules. Additional quantification capabilities available from the same scan make it a more comprehensive imaging option in oncology patients. This is a first case report demonstrating the potential of single SDCT to provide necessary information for lung cancer diagnosis and preoperative planning, comparable to standard of care imaging.

Structural and functional alterations of the tracheobronchial tree after left upper pulmonary lobectomy for lung cancer

Background

Pulmonary lobectomy has been a well-established curative treatment method for localized lung cancer. After left upper pulmonary lobectomy, the upward displacement of remaining lower lobe causes the distortion or kink of bronchus, which is associated with intractable cough and breathless. However, the quantitative study on structural and functional alterations of the tracheobronchial tree after lobectomy has not been reported. We sought to investigate these alterations using CT imaging analysis and computational fluid dynamics (CFD) method.

Methods

Both preoperative and postoperative CT images of 18 patients who underwent left upper pulmonary lobectomy are collected. After the tracheobronchial tree models are extracted, the angles between trachea and bronchi, the surface area and volume of the tree, and the cross-sectional area of left lower lobar bronchus are investigated. CFD method is further used to describe the airflow characteristics by the wall pressure, airflow velocity, lobar flow rate, etc.

Results

It is found that the angle between the trachea and the right main bronchus increases after operation, but the angle with the left main bronchus decreases. No significant alteration is observed for the surface area or volume of the tree between pre-operation and post-operation. After left upper pulmonary lobectomy, the cross-sectional area of left lower lobar bronchus is reduced for most of the patients (15/18) by 15–75%, especially for 4 patients by more than 50%. The wall pressure, airflow velocity and pressure drop significantly increase after the operation. The flow rate to the right lung increases significantly by 2–30% (but there is no significant difference between each lobe), and the flow rate to the left lung drops accordingly. Many vortices are found in various places with severe distortions.

Conclusions

The favorable and unfavorable adaptive alterations of tracheobronchial tree will occur after left upper pulmonary lobectomy, and these alterations can be clarified through CT imaging and CFD analysis. The severe distortions at left lower lobar bronchus might exacerbate postoperative shortness of breath.

Prediction of postoperative lung function in lung cancer patients using perfusion scintigraphy

BACKGROUND

Predicting postoperative lung function is critical in lung cancer patients. Perfusion scintigraphy has been used to estimate postoperative function after lung resection.

PURPOSE

To evaluate the usefulness of the posterior oblique method in relation to other conventional processing methods for predicting postoperative lung function using lung perfusion scintigraphy.

MATERIAL AND METHODS

Fifty-five patients with non-small-cell lung cancer who underwent lobectomy were enrolled. Forced expiratory volume in 1 s (FEV1) values were obtained from preoperative and postoperative pulmonary function tests. After performing lung perfusion scintigraphy, predicted FEV1 values were calculated using the segment, conventional, posterior, and posterior oblique methods. Postoperative FEV1 values were compared with predicted FEV1 values.

RESULTS

The mean value of the preoperative FEV1 was 2.29 L and that of the postoperative FEV1 was 1.89 L. The mean values of the predicted postoperative FEV1 values for the segment, conventional, posterior, and posterior oblique were 1.83 L, 1.94 L, 1.88 L, and 1.89 L, respectively. Between the observed and predicted FEV1 values, there was a strong correlation without significant difference except for conventional method. Bland-Altman analysis showed that segment and posterior methods underestimated the FEV1, whereas conventional and posterior oblique methods overestimated the FEV1.

CONCLUSION

Predictions with each processing method of lung perfusion scintigraphy showed nearly similar results to the actual postoperative lung function. The posterior oblique method of lung perfusion scintigraphy showed a very small difference to such an extent as to be equal to the observed FEV1, implying that this method may be applied for predicting postoperative lung function in lung cancer patients.

Gadolinium-Based Blood Volume Mapping From MRI With Ultrashort TE Versus CT and SPECT for Predicting Postoperative Lung Function in Patients With Non-Small Cell Lung Cancer

OBJECTIVE

The purpose of this study is to directly compare the capability of gadolinium-based blood volume (BV) mapping from MRI (BV-MRI) with ultrashort TE (UTE) with that of CT and perfusion SPECT in predicting the postoperative lung function of patients with non-small cell lung cancer (NSCLC).

SUBJECTS AND METHODS

Unenhanced and contrast-enhanced MRI with UTE, thin-section CT, and perfusion SPECT examinations and measurements of the percentage of forced expiratory volume in 1 second (FEV₁) before and after lung resection were performed for 29 patients with NSCLC (16 men [mean age, 66 years] and 13 women [mean age, 66 years]). BV-MRI with UTE was generated as a percentage of the signal change between unenhanced and contrast-enhanced MRI. The postoperative percentage of FEV₁ was predicted from perfusion fractions derived from BV-MRI with UTE and from SPECT. Quantitatively and qualitatively predicted postoperative percentages of FEV₁ from CT were calculated from the functional lung volumes and the number of segments. Each predicted postoperative percentage of FEV₁ was then correlated with the actual postoperative percentage of FEV₁, and the limits of agreement for each actual and predicted postoperative percentage of FEV₁ were evaluated by Bland-Altman analysis.

RESULTS

Correlations between actual and predicted postoperative percentages of FEV₁ for all methods were strong and significant (0.88 ≤ r ≤ 0.95). The limits of agreement (mean ± 1.96 × SD) for BV-MRI with UTE (4.2% ± 6.5%) and quantitatively assessed CT (4.1% ± 6.5%) were smaller than those for qualitatively assessed CT (4.2% ± 9.8%) and perfusion SPECT (5.7% ± 8.7%).

CONCLUSION

BV-MRI with UTE has the potential to predict the postoperative lung function of patients with NSCLC more accurately than qualitatively assessed CT and SPECT, and it can be considered to be at least as useful as quantitatively assessed CT.

The Role of Dual-Energy Computed Tomography in Assessment of Abdominal Oncology and Beyond

The added value and strength of dual energy computed tomography for the evaluation of oncologic patients revolve around the use of lower energy reconstructed images and iodine material density images. Lower keV simulated monoenergetic images optimize soft tissue tumor to nontumoral attenuation differences and increase contrast to noise ratios to improve lesion detection. Iodine material density images or maps are helpful from a qualitative standpoint for image interpretation because they result in improved detection and characterization of tumors and lymph node involvement, and from a quantitative assessment by enabling interrogation of specific properties of tissues to predict and assess therapeutic response.

CT Radiomics in Thoracic Oncology: Technique and Clinical Applications

Precision medicine offers better treatment options and improved survival for cancer patients based on individual variability. As the success of precision medicine depends on robust biomarkers, the requirement for improved imaging biomarkers that reflect tumor biology has grown exponentially. Radiomics, the field of study in which high-throughput data are generated and large amounts of advanced quantitative features are extracted from medical images, has shown great potential as a source of quantitative biomarkers in the field of oncology. Radiomics provides quantitative information about the morphology, texture, and intratumoral heterogeneity of the tumor itself as well as features related to pulmonary function. Hence, radiomics data can be used to build descriptive and predictive clinical models that relate imaging characteristics to tumor biology phenotypes. In this review, we describe the workflow of CT radiomics, types of CT radiomics, and its clinical application in thoracic oncology.