Long COVID is more than just lingering symptoms—it may have a hidden biological basis that standard medical tests fail to detect.

A groundbreaking study using advanced MRI technology has uncovered significant lung abnormalities in children and adolescents suffering from long COVID, particularly in blood flow and air movement. These findings help explain persistent symptoms like chronic fatigue and shortness of breath, offering a new path for diagnosing and managing this condition.

MRI Reveals Lung Abnormalities in Children with Long COVID

A new study published today (February 25) in Radiology, the journal of the Radiological Society of North America (RSNA), reveals that an advanced type of MRI has detected significant lung abnormalities in children and adolescents with long COVID.

Long COVID, or post-COVID-19 condition, occurs when symptoms persist for more than 12 weeks after a COVID-19 infection. While children and teens generally experience a milder form of the condition, symptoms like chronic fatigue, headaches, and difficulty concentrating can interfere with school and social activities.

A Need for Better Testing

In adults, chest CT scans are commonly used to assess lung function in long COVID cases. However, this method is not usually recommended for children due to radiation exposure and the potential need for contrast agents.

Instead, young patients suspected of having long COVID are typically evaluated through pulmonary function tests, echocardiography, and medical history reviews. Unfortunately, these standard tests often show normal lung and heart function, even in children experiencing ongoing symptoms.

"Parents should understand that their children's persistent symptoms after COVID-19 may have a measurable physiological basis, even when standard medical tests appear normal," said lead study author Gesa H. Pöhler, M.D., a senior physician in the Department of Diagnostic and Interventional Radiology at Hannover Medical School in Germany.

The researchers employed phase-resolved functional lung (PREFUL) MRI. This advanced MRI technology can analyze lung ventilation (air movement in and out of the lungs) and perfusion (blood flow through the lungs). PREFUL MRI doesn't require the use of radiation or intravenous contrast agents and can be done while the patient breathes freely, making it a suitable procedure for children.Exemplary Coronal Sections of Phase Resolved Functional Lung MRI Ventilation and Perfusion Maps COVID 19

Images show exemplary coronal sections of phase-resolved functional lung MRI ventilation and perfusion maps in a 15-year-old female participant with post-COVID-19 condition (PCC) and in a sex- and age-matched healthy control participant. (A, B) Images show regional ventilation, with values of (A) 0.1 mL/mL in the participant with PCC and (B) 0.5 mL/mL in the healthy control participant. Regarding dynamic ventilation (C, D), images show the flow-volume loop correlation metric, with (C) the participant with PCC at 0.98 arbitrary units (au) and (D) the healthy control participant at 0.99 au. (E, F) Images show perfusion maps depicting a median quantified perfusion of 27 mL/min per 100 mL for the participant with PCC and 89 mL/min per 100 mL for the healthy control participant. Credit: Radiological Society of North America (RSNA)

First Evidence of Lung Perfusion Abnormalities

"Our research provides the first comprehensive evidence of measurable regional lung perfusion abnormalities in pediatric post-COVID-19 condition using radiation-free, contrast-free lung imaging," Dr. Pöhler said.

For the prospective study, conducted between April 2022 and 2023, the researchers enrolled 54 patients ranging in age from 11 to 17 years. Half of the patients were diagnosed with long COVID, and the other half were healthy controls. A self-reported assessment called the bell score was used to assess symptom severity in patients with long COVID.

Functional Lung MRI Defect Maps Pediatric COVID 19
Images show exemplary coronal sections of phase-resolved functional lung MRI defect maps in a pediatric participant with post-COVID-19 condition (PCC) and cardiopulmonary symptoms and a healthy control patient. (A) Images in a 17-year-old male participant with PCC show a ventilation defect percentage (VDP) of 17%, a perfusion defect percentage (QDP) of 16%, a ventilation/perfusion (V/Q) match healthy (VQM [H]) percentage of 64%, and a V/Q mismatch defect (VQM [D]) of 3%. (B) Images in a healthy control participant, with a ventilation defect percentage of 9%, a perfusion defect percentage of 5%, a V/Q match healthy percentage of 86%, and no V/Q mismatch defect. Credit: Radiological Society of North America (RSNA)

Blood Flow Reduction and Fatigue Connection

Compared to healthy controls, children and adolescents with long COVID had significantly reduced blood flow in the lungs. A reduction in blood flow patterns in organs or other areas of the body can result in a lack of sufficient oxygen and nutrients.

The most prevalent symptom of fatigue affected all but one patient with long COVID.

"Importantly, the severity of fatigue symptoms correlated with these blood flow changes, suggesting a possible biological basis for the patients' ongoing symptoms," Dr. Pöhler said.

In addition to poor blood flow, a subgroup of long COVID patients with cardiopulmonary symptoms, such as shortness of breath, also showed a reduction of air movement and reach in the lungs.

Functional Lung MRI Perfusion Maps Bell Score COVID 19
Dorsal, medial, and ventral phase-resolved functional lung MRI perfusion maps show distinct perfusion phenotypes related to the severity of chronic fatigue assessed with the Bell score in three participants with post-COVID-19 condition and in a healthy control participant. The top row shows maps from a 17-year-old male healthy control participant with a median quantified perfusion of 81 mL/min per 100 mL. The second row from the top shows maps from a 17-year-old male participant with a Bell score of 90 and a quantified perfusion of 59 mL/min per 100 mL. The second row from the bottom shows maps from a 16-year-old female participant with a Bell score of 60 with a quantified perfusion of 48 mL/min per 100 mL. The bottom row shows maps from a 15-year-old male participant with a Bell score of 30 and a quantified perfusion of 32 mL/min per 100 mL. Credit: Radiological Society of North America (RSNA)

Future Implications for Long COVID Monitoring

The researchers suggest that continuous monitoring of lung abnormalities in children with long COVID at various stages of the condition could help guide therapeutic interventions and monitoring strategies.

"Quantitative lung MRI establishes a potential imaging biomarker profiling and helps to enable disease severity follow-up for this complex condition in the future," Dr. Pöhler said.

Reference: "Phase-resolved Functional Lung MRI Reveals Distinct Lung Perfusion Phenotype in Children and Adolescents with Post–COVID-19 Condition" by Gesa H. Pöhler, Andreas Voskrebenzev, Marc-Luca Heinze, Valentina Skeries, Filip Klimeš, Julian Glandorf, Jan Eckstein, Nigar Babazade, Marius Wernz, Alexander Pfeil, Gesine Hansen, Frank K. Wacker, Jens Vogel-Claussen, Martin Wetzke and Diane Miriam Renz, 25 February 2025, Radiology.
DOI: 10.1148/radiol.241596

Collaborating with Dr. Pöhler were Andreas Voskrebenzev, Ph.D., Marc-Luca Heinze, Valentina Skeries, M.D., Filip Klimeš, Ph.D., Julian Glandorf, M.D., Jan Eckstein, M.D., Nigar Babazade, Marius Wernz, B.S., Alexander Pfeil, M.D., Gesine Hansen, M.D., Frank K. Wacker, M.D., Jens Vogel-Claussen, M.D., Martin Wetzke, M.D., and Diane Miriam Renz, M.D.

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