Thoracic Insufficiency Syndrome: An Overview

Interactive Segmentation of Lung Tissue and Lung Excursion in Thoracic Dynamic MRI Based on Shape-guided Convolutional Neural Networks

Purpose

Lung tissue and lung excursion segmentation in thoracic dynamic magnetic resonance imaging (dMRI) is a critical step for quantitative analysis of thoracic structure and function in patients with respiratory disorders such as Thoracic Insufficiency Syndrome (TIS). However, the complex variability of intensity and shape of anatomical structures and the low contrast between the lung and surrounding tissue in MR images seriously hamper the accuracy and robustness of automatic segmentation methods. In this paper, we develop an interactive deep-learning based segmentation system to solve this problem.

Material & Methods

Considering the significant difference in lung morphological characteristics between normal subjects and TIS subjects, we utilized two independent data sets of normal subjects and TIS subjects to train and test our model. 202 dMRI scans from 101 normal pediatric subjects and 92 dMRI scans from 46 TIS pediatric subjects were acquired for this study and were randomly divided into training, validation, and test sets by an approximate ratio of 5:1:4. First, we designed an interactive region of interest (ROI) strategy to detect the lung ROI in dMRI for accelerating the training speed and reducing the negative influence of tissue located far away from the lung on lung segmentation. Second, we utilized a modified 2D U-Net to segment the lung tissue in lung ROIs, in which the adjacent slices are utilized as the input data to take advantage of the spatial information of the lungs. Third, we extracted the lung shell from the lung segmentation results as the shape feature and inputted the lung ROIs with shape feature into another modified 2D U-Net to segment the lung excursion in dMRI. To evaluate the performance of our approach, we computed the Dice coefficient (DC) and max-mean Hausdorff distance (MM-HD) between manual and automatic segmentations. In addition, we utilized Coefficient of Variation (CV) to assess the variability of our method on repeated dMRI scans and the differences of lung tidal volumes computed from the manual and automatic segmentation results.

Results

The proposed system yielded mean Dice coefficients of 0.96±0.02 and 0.89±0.05 for lung segmentation in dMRI of normal subjects and TIS subjects, respectively, demonstrating excellent agreement with manual delineation results. The Coefficient of Variation and p-values show that the estimated lung tidal volumes of our approach are statistically indistinguishable from those derived by manual segmentations.

Conclusions

The proposed approach can be applied to lung tissue and lung excursion segmentation from dynamic MR images with high accuracy and efficiency. The proposed approach has the potential to be utilized in the assessment of patients with TIS via dMRI routinely.

The impact of scoliosis surgery on pulmonary function in spinal muscular atrophy: a systematic review

Scoliosis often occurs coincident with pulmonary function deterioration in spinal muscular atrophy but a causal relationship has not yet been reliably established. A systematic literature review was performed, with pulmonary function testing being the primary outcome pre- and post-scoliosis surgery. Levels of evidence were determined and GRADE recommendations made. Ninety studies were identified with only 14 meeting inclusion criteria. Four studies were level III and the rest were level IV evidence. The average age at surgical intervention was 11.8 years (follow-up 6.1 years). Post-operative pulmonary function progressively declined for the majority of studies. Otherwise, pulmonary function: improved (two studies), were unchanged (two studies), had a decreased rate of decline (three studies), declined initially then returned to baseline (two studies). Respiratory and spine-based complications were common. Given the available evidence, the following GRADE C recommendations were made: (1) surgery is most often associated with decreases in pulmonary function; (2) the impact of surgery on pulmonary function is variable, but does not improve over pre-operative baseline; (3) surgery may result in a decreased rate of decline in pulmonary function post-operatively. Given this lack of evidence-based support, the risk-benefit balance should be taken into consideration when contemplating scoliosis surgery.

Spondylocostal Dysostosis: A Literature Review and Case Report with Long-Term Follow-Up of a Conservatively Managed Patient

Introduction

Patients with spondylocostal dysostosis (SCD) have congenital spine and rib deformities associated with frequently severe thoracic insufficiency and respiratory compromise. The literature is largely composed of case reports and small cohorts, and there is little information regarding adults with this condition. In this report, we describe the natural history of a conservatively treated patient and include quality-of-life issues such as childbearing, athletic participation, and occupational selection.

Case Presentation

We present a patient with SCD who was conservatively treated by a single physician from birth for 31 years. Our patient was capable of a reasonably good quality of life through adulthood, including participation in gymnastics and employment. At age 18, she became pregnant and subsequently terminated the pregnancy due to obstetrical concerns for compromised respiration. She has had intermittent respiratory complaints and occasionally experiences dyspnea with exertion, but this only has limited her during certain activities in the past three years. Currently, she takes naproxen for chronic back pain with periodic exacerbations.

Discussion

Other cases in the literature have described adult SCD patients who have received nonoperative treatment and achieved a wide range of functional outcomes. This provides some limited evidence to suggest that select patients with SCD may be treated conservatively and achieve a reasonable quality of life. However, close clinical follow-up with these patients is recommended, particularly early on, considering the high rates of infant morbidity and mortality. Chest physiotherapy and early pulmonary care have been associated with favorable outcomes in infancy. Surgery to increase thoracic volume and correct scoliosis has been shown in some cases to improve respiratory function. Treatment depends on the degree of thoracic insufficiency and quality of life. The natural history of SCD remains largely unknown, but some patients are capable of relatively favorable life spans, employment, and participation in athletics.