Naming the bronchopulmonary segments and the development of pulmonary surgery

Identification of anatomical types of segmental bronchi in left superior and lingular lobes using multi-slice CT

PURPOSE

The objectives of this study were to evaluate various branching patterns of segmental bronchi in the left superior and lingular lobes and to survey the anatomical diversity and sex-related differences of these branches in a large sample of the study population.

MATERIALS AND METHODS

Overall, 10,000 participants (5428 males, and 4572 females, mean age 50 ± 13.5 years [SD] years; age range: 3-91 years) who underwent multi-slice CT (MSCT) scans between September 2019 and December 2021 were retrospectively included. Using the syngo.via post-processing workstation, the data were applied to generate three-dimensional (3D) and virtual bronchoscopy (VB) simulations of a bronchial tree. The reconstructed images were then interpreted to identify and categorize distinct bronchial patterns in the left superior and lingular lobes. Cross-tabulation analysis and the Pearson Chi-square (χ2) test were used to calculate the constituent ratios of bronchial branch types and determine their significance between male and female groups.

RESULTS

Our results revealed mainly four distinct types for the left superior lobe (LSL) bronchial tree, i.e., (B1 + 2, B3, 76.13%); (B1 + 2 + 3, 17.32%); (B1 + 3, B2, 5.74%); (B1a + B3, B1b + B2, 0.81%) and two types for the left lingular lobe (LLL) bronchial tree, i.e., (B4, B5, 91.05%); (B4, B5, B*, 8.95%). There were no significant sex-related differences in the proportion of bronchial branches in LLL (P > 0.05). However, sex-related differences were significant in the proportion of bronchial branches in LSL (P < 0.05).

CONCLUSION

The current study has validated the presence of segmental bronchial variations in the left superior and lingular lobes. These findings may have a crucial effect on the diagnosis of symptomatic patients, as well as in carrying out procedures such as lung resections, endotracheal intubation, and bronchoscopies.

Diagnostic accuracy of perfusion-weighted phase-resolved functional lung magnetic resonance imaging in patients with chronic pulmonary embolism

Purpose

This study aimed to evaluate the diagnostic performance of perfusion-weighted phase-resolved functional lung (PW-PREFUL) magnetic resonance imaging (MRI) in patients with chronic pulmonary embolism (CPE).

Materials and methods

This study included 86 patients with suspected chronic thromboembolic pulmonary hypertension (CTEPH), who underwent PREFUL MRI and ventilation/perfusion (V/Q) single-photon emission computed tomography/computed tomography (SPECT/CT). PREFUL MRI was performed at 1.5 T using a balanced steady-state free precession sequence during free breathing. Color-coded PW images and quantitative parameters were obtained by postprocessing. Meanwhile, V/Q SPECT/CT imaging was performed as a reference standard. Hypoperfused areas in the lungs were scored for each lobe and segment using V/Q SPECT/CT images and PW-PREFUL MR images, respectively. Normalized perfusion (QN) and perfusion defect percentage (QDP) were calculated for all slices. For intra- and interobserver variability, the MRI images were analyzed 2 months after the first analysis by the same radiologist and another radiologist (11 years of lung MRI experience) blinded to the results of the first reader.

Results

Of the 86 enrolled patients, 77 met the inclusion criteria (36 diagnosed with CPE using V/Q SPECT/CT and 41 diagnosed with non-CPE etiology). For the PW-PREFUL MRI, the sensitivity, specificity, accuracy, and positive and negative predictive values for the diagnosis of CPE were 97, 95, 96, 95, and 98% at the patient level; 91, 94, 93, 91, and 94% at the lobe level, and 85, 94, 92, 88, and 94% at the segment level, respectively. The detection of segmental and subsegmental hypoperfusion using PW-PREFUL MRI revealed a moderate agreement with V/Q SPECT/CT (κ = 0.65; 95% confidence interval: 0.61-0.68). The quantitative results indicated that the QN was lower in the CPE group than in the non-CPE group [median score (interquartile range, IQR) 6.3 (2.8-9.2) vs. 13.0 (8.8-16.7), p < 0.001], and the QDP was higher [median score (IQR) 33.8 (15.7-51.7) vs. 2.2 (1.4-2.9), p < 0.001].

Conclusion

PREFUL MRI could be an alternative test to detect CPE without requiring breath-hold, contrast agents, or ionizing radiation.

Identification of anatomical types of segmental bronchi in right middle lobe using multi-slice CT

PURPOSE

The objectives of this study were to evaluate the various branching patterns of segmental bronchi in the right middle lobe (RML) and to survey the anatomical diversity and sex-related differences of these branches in a large sample of the study population.

MATERIALS AND METHODS

In this retrospective board-approved study with informed consent, 10,000 participants (5428 males and 4,572 females, mean age 50 ± 13.5 years [SD]; age range: 3-91 years) who underwent multi-slice CT (MSCT) scans from September 2019 to December 2021 were retrospectively included. The data were applied to generate three-dimensional (3D) and virtual bronchoscopy (VB) simulations of a bronchial tree using the syngo.via post-processing workstation. The reconstructed images were then interpreted to locate and classify distinct bronchial patterns in the RML. Cross-tabulation analysis and the Pearson chi-square test were used to calculate the constituent ratios of bronchial branch types and determine their significance between male and female groups.

RESULTS

Our results revealed that the segmental bronchial ramifications of the RML were classified into two types mainly, i.e., bifurcation (B4, B5, 91.42%) and trifurcation (B4, B5, B*, 8.58%). There were no significant sex-related differences in the proportion of bronchial branches in the RML (P > 0.05).

CONCLUSION

The current study has confirmed the presence of segmental bronchial variations in the RML lobe using 3D reconstruction and virtual bronchoscopy. These findings may have significant implications for the diagnosis of symptomatic patients and for carrying out specific procedures like bronchoscopy, endotracheal intubation, and lung resection.

A comparison between manual and artificial intelligence-based automatic positioning in CT imaging for COVID-19 patients

Objective

To analyze and compare the imaging workflow, radiation dose, and image quality for COVID-19 patients examined using either the conventional manual positioning (MP) method or an AI-based automatic positioning (AP) method.

Materials and methods

One hundred twenty-seven adult COVID-19 patients underwent chest CT scans on a CT scanner using the same scan protocol except with the manual positioning (MP group) for the initial scan and an AI-based automatic positioning method (AP group) for the follow-up scan. Radiation dose, patient positioning time, and off-center distance of the two groups were recorded and compared. Image noise and signal-to-noise ratio (SNR) were assessed by three experienced radiologists and were compared between the two groups.

Results

The AP operation was successful for all patients in the AP group and reduced the total positioning time by 28% compared with the MP group. Compared with the MP group, the AP group had significantly less patient off-center distance (AP 1.56 cm ± 0.83 vs. MP 4.05 cm ± 2.40, p < 0.001) and higher proportion of positioning accuracy (AP 99% vs. MP 92%), resulting in 16% radiation dose reduction (AP 6.1 mSv ± 1.3 vs. MP 7.3 mSv ± 1.2, p < 0.001) and 9% image noise reduction in erector spinae and lower noise and higher SNR for lesions in the pulmonary peripheral areas.

Conclusion

The AI-based automatic positioning and centering in CT imaging is a promising new technique for reducing radiation dose and optimizing imaging workflow and image quality in imaging the chest.

Key Points

• The AI-based automatic positioning (AP) operation was successful for all patients in our study.

• AP method reduced the total positioning time by 28% compared with the manual positioning (MP).

• AP method had less patient off-center distance and higher proportion of positioning accuracy than MP method, resulting in 16% radiation dose reduction and 9% image noise reduction in erector spinae.

Using structured progress to measure competence in flexible bronchoscopy

Background

Flexible bronchoscopy is a core invasive procedure in pulmonary medicine and training in the procedure is mandatory. Diagnostic completeness and procedure time have been identified as useful measures of competence. No outcome measures have been developed regarding navigational path in bronchoscopy to assess whether the bronchial segments have been identified in an arbitrary or structured order. We investigated whether a new outcome measure for structured progression could be used to assess competency in flexible bronchoscopy.

Methods

The study was designed as a prospective comparative study. Twelve novices, eleven intermediates, and ten expert bronchoscopy operators completed three full bronchoscopies in a simulated setting on a phantom. The following outcome measures were collected through a checklist evaluation by a trained rater: Diagnostic Completeness as amount of visualized bronchial segments, Structured Progress between the bronchial segments in ascending order, and average intersegmental time (AIT).

Results

The ability to follow a structured ascending path through the bronchial tree correlated with a higher amount of identified bronchial segments (Pearson’s correlation, r=0.62, P<0.001) and a lower AIT (Pearson’s correlation, r=−0.52, P<0.001).

Conclusions

Operators should advance through the bronchial tree in a structured ascending order to ensure systematic progress with the highest level of diagnostic yield and the lowest procedure time. Structured progression is a useful measure to evaluate competency in flexible bronchoscopy.

Anatomical Labeling of Human Airway Branches using a Novel Two-Step Machine Learning and Hierarchical Features

Chronic obstructive pulmonary disease (COPD) is a common inflammatory disease associated with restricted lung airflow. Quantitative computed tomography (CT)-based bronchial measures are popularly used in COPD-related studies, which require both airway segmentation and anatomical branch labeling. This paper presents an algorithm for anatomical labeling of human airway tree branches using a novel two-step machine learning and hierarchical features. Anatomical labeling of airway branches allows standardized spatial referencing of airway phenotypes in large population-based studies. State-of-the-art anatomical labeling methods are associated with mandatory manual reviewing and correction for mislabeled branches-a time-consuming process susceptible to inter-observer variability. The new method is fully automated, and it uses hierarchical branch-level features from the current as well as ancestral and descendant branches. During the first machine learning step, it differentiates candidate anatomical branches from insignificant topological branches, often, responsible for variations in airway branching patterns. The second step is designed for lung lobe-based classification of anatomical labels for valid candidate branches. The machine learning classifiers has been designed, trained, and validated using total lung capacity (TLC) CT scans (n = 350) from the Iowa cohort of the nationwide COPDGene study during their baseline visits. One hundred TLC CT scans were used for training and validation, and a different set of 250 scans were used for testing and evaluative experiments. The new method achieved labeling accuracies of 98.4, 97.2, 92.3, 93.4, and 94.1% in the right upper, right middle, right lower, left upper, and left lower lobe, respectively, and an overall accuracy of 95.9%. For five clinically significant segmental branches, the method has achieved an accuracy of 95.2%.

Pulmonary vascular anatomy & anatomical variants

The vessels supplying the lungs include the pulmonary arteries, pulmonary veins, and bronchial arteries. The segmental and sub segmental pulmonary arteries parallel the bronchi and are named according to the bronchopulmonary segments they supply. There are however considerable anatomic variations, particularly in the upper lobes with variations in number or presence of accessory arteries from adjacent segments. The subsegmental pulmonary vein branches, run within interlobular septa and do not parallel the segmental or sub segmental pulmonary artery branches and bronchi. They converge to form right and left superior and inferior pulmonary veins which drain into the left atrium. Knowledge of normal and variant anatomy on cross-sectional and angiographic images is essential for accurate diagnosis of vascular pathology and aids planning of interventional procedures.

Impact of image quality, radiologists, lung segments, and Gunnar eyewear on detectability of lung nodules in chest CT

BACKGROUND

Despite the increasingly higher spatial and contrast resolution of CT, nodular lesions are prone to be missed on chest CT. Tinted lenses increase visual acuity and contrast sensitivity by filtering short wavelength light of solar and artificial origin.

PURPOSE

To test the impact of Gunnar eyewear, image quality (standard versus low dose CT) and nodule location on detectability of lung nodules in CT and to compare their individual influence.

MATERIAL AND METHODS

A pre-existing database of CT images of patients with lung nodules >5 mm, scanned with standard does image quality (150 ref mAs/120 kVp) and lower dose/quality (40 ref mAs/120 kVp), was used. Five radiologists read 60 chest CTs twice: once with Gunnar glasses and once without glasses with a 1 month break between. At both read-outs the cases were shown at lower dose or standard dose level to quantify the influence of both variables (eyewear vs. image quality) on nodule sensitivity.

RESULTS

The sensitivity of CT for lung nodules increased significantly using Gunnar eyewear for two readers and insignificantly for two other readers. Over all, the mean sensitivity of all radiologist raised significantly from 50% to 53%, using the glasses (P value = 0.034). In contrast, sensitivity for lung nodules was not significantly affected by lowering the image quality from 150 to 40 ref mAs. The average sensitivity was 52% at low dose level, that was even 0.7% higher than at standard dose level (P value = 0.40). The strongest impact on sensitivity had the factors readers and nodule location (lung segments).

CONCLUSION

Sensitivity for lung nodules was significantly enhanced by Gunnar eyewear (+3%), while lower image quality (40 ref mAs) had no impact on nodule sensitivity. Not using the glasses had a bigger impact on sensitivity than lowering the image quality.

Tracheobronchial variations in Turkish population

The tracheobronchial tree exhibits highly individualistic features and many variations. As the anatomic variations among Turkish population have not been studied previously, we aimed to evaluate the type and frequency of tracheobronchial variations (TBVs) in our bronchoscopy population. In a 3-year period, 1,114 patients underwent flexible bronchoscopy (FB). Among these, 780 (70%) were male. The mean age of the patients was 51.3 +/- 15.1 (range: 17-84) years. In 639 cases, no TBV were detected. A total of 999 TBV were observed in 475 patients. Of all, 71.3% (713) of the total TBV were detected in males. Forty-nine and six-tenths percent (49.6%) of the TBV were observed on the right bronchial system, 49.2% on the left, and 1.2% in the trachea. The five most frequently observed TBV were right lower lobe basal orifice with two subsegments, left lower lobe basal orifice with two subsegments, left upper lobe with three segments, right upper lobe with two segments, and right lower lobe with a subapical segment. In the same lobe bronchus, single variation and two different TBV were seen in 85% and 15% of patients, respectively. Number of TBV increased linearly with the number of lobes involved. The availability and popularity of FB in recent years has led to the increase in identification and reporting of TBV. TBV should be correctly identified and documented. This information is invaluable during follow-up bronchoscopies as well as lung resection.

Lobes, fissures, and bronchopulmonary segments

The clinical practice of thoracic surgery requires the surgeon to have intimate knowledge of pulmonary anatomy and of its variations. Attempts to perform thoracic procedures without this knowledge can only result in incomplete operations or technical mishaps. Proper understanding of the anatomy of the pulmonary lobes, segments, and fissures allows the surgeon to correlate imaging, pathologic processes, and possible resectional procedures, thus insuring that each patient gets the best possible operation.

How Accurately Can We Predict Forced Expiratory Volume in One Second after Major Pulmonary Resection?

Standard formulas for predicting postoperative forced expiratory volume in 1 second (po-FEV1) do not consider bronchi obstructed by tumor or chronic obstructive pulmonary disease, e.g., Formula 1 [ppo-FEV1 = (pre-opFEV1) x (# segments remaining)/(# of total segments)] whereas Formula 2 [ppo-FEV1 = (pre-opFEV1) x (# segments remaining)/(# of total unobstructed segments)] does. A retrospective chart review was conducted to determine accuracy of predicting po-FEV1, at a comprehensive cancer center. Predicted po-FEV1 was calculated using different formulas and analyzed using regression analysis and Pearson correlation. We found good correlation between po-FEV1 and predicted po-FEV1 using Formulas 1 and 2. In patients with tumor airway obstruction or chronic obstructive pulmonary disease, predictive accuracy decreased for both formulas. Prediction of FEV1 in patients undergoing pulmonary resection was generally accurate, but major errors were observed in some cases; therefore, better predictive formulas are needed in patients with airway obstruction by tumor or chronic obstructive pulmonary disease.