Chest / Cardiac for Thursday, June 4th, 2026

Contributed by Cincinnati Children's Hospital Medical Center
Liz England, and Paul Guillerman.

History

6-year-old with pectus excavatum and history of recurrent pneumonias with right upper lobe hyperinflation and right middle lobe and right lower lobe volume loss on imaging. Referring clinical service considering endoscopic lung volume reduction surgery or lobectomy.

Images (Click any image to enlarge)

CT Chest: Pre-procedural imaging
Xenon-129 MRI Chest #1: Pre-procedural imaging
129Xe MRI Chest #2: S/p Bronchoscopy and right upper lobe endobronchial valve placement. Patient underwent bronchoscopy after this MRI exam and the endobronchial valve found to be non-obstructing. The right upper lobe endobronchial valve was replaced.
Chest radiograph and 129Xe MRI chest #3 s/p right upper lobe endobronchial valve replacement.

Question

1. After technically successful endobronchial valve replacement, some gas still gets into the right upper lobe. What is the most likely explanation? 2. What anatomical pathways contribute to collateral ventilation?

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Correct answer

  1. Collateral ventilation
  2. Pores of Kohn and canals of Lambert

Discussion

Hyperpolarized Xenon-129 (129Xe) ventilation MRI is a functional lung imaging technique in which the patient inhales hyperpolarized 129Xe gas, allowing MRI to directly map regional ventilation. Inhaled 129Xe follows the path of oxygen from the alveolar air spaces across the interstitium into the capillaries and red blood cells, allowing gas exchange to also be assessed. The rbc-to-gas ratio expresses the ratio of 129Xe dissolved in the rbc phase to the gas phase, reflecting transfer of 129Xe to rbc’s in the pulmonary capillaries, and may be reduced when the capillary network is deficient compared to the alveolar spaces, such as in this case with enlarged simplified alveoli.  Diffusion-weighted 129Xe MRI exploits the inherent diffusion of 129Xe within the airspaces to reveal airspace microstructure.  Elevated ADC is observed in the setting of airspace enlargement, such as in this case.  A major advantage of 129Xe is its ability to provide physiologic information without ionizing radiation, making it well suited for children who may require repeated evaluation. Additionally, it is valuable in disease where there may be regional heterogeneity, where global tests such as spirometry may be normal despite an anatomic abnormality. Clinical uses of 129Xe ventilation MRI include evaluation of patients with cystic fibrosis, bronchiolitis obliterans, and other obstructive lung diseases.

Congenital lobar overinflation (congenital lobar emphysema) is a lung malformation with intrinsic or extrinsic bronchus obstruction and progressive air trapping from ball-valve effect, resulting in overexpansion of a lobe or portion of a lobe and enlarged simplified alveoli, dilated bronchioles and mucostasis.  Although most often presenting in the neonatal period or infancy with respiratory distress, it may present later in childhood or adulthood. The left upper lobe is most commonly affected (40%), followed by the right middle lobe (35%), right upper lobe (20%), and lower lobes (5%). A hyperlucent hyperexpanded lobe with mass effect on adjacent lung, diaphragm and mediastinum is characteristic. Treatment options include observation, endoscopic lung volume reduction, or lobectomy after bronchoscopy excludes endobronchial lesions.

Endobronchial valves are designed as one-way devices to allow air to exit, but not enter the targeted lobe, thereby inducing lobar deflation. However, when collateral ventilation is present, air can bypass the occluded bronchus through these interconnections, maintaining aeration of the lobe despite proper valve placement. Recognizing this is important, as further bronchoscopic intervention attempts are unlikely to succeed and management may shift toward definitive surgical options in a symptomatic patient.

References

  • 1. Demir OF, Hangul M, Kose M. Congenital lobar emphysema: diagnosis and treatment options. Int J Chron Obstruct Pulmon Dis 2019;14:921–928. 2. Nelson ND, Pogoriler J. Congenital cystic lung lesions: An update on clinical and pathologic correlates. Surg Pathol Clin 2025;18:383-396 3. Kunisaki SM, Saito JM, Fallat ME, St. Peter SD, Kim AG, Johnson KN et al. Current operative management of congenital lobar emphysema in children: A report from the Midwest Pediatric Surgery Consortium. J Pediatr Surg 2019;54: 1138-1142 4. El-Ali AM, Strubel NA, Lala SV. Congenital lung lesions: a radiographic pattern approach. Pediatr Radiol 2022;52(4):622-636 5. Schmidt A, Liggins JA, Bhutta H, Dell SD, Leung JM, Sin DD, et al. Hyperpolarized 129Xe MRI and spectroscopy: Quantitative measurements, results and emerging opportunities. Radiology: Cardiothoracic Imaging 2025;7:e240562