Related Experiment Video
Updated: Jul 15, 2026
Multi-modal Pulmonary Imaging: Using Complementary Information from CT and Hyperpolarized 129Xe MRI to Evaluate Lung Structure-Function
Published on: April 12, 2024
Prevalence and characteristics of minimal pleural fluid on screening chest MRI
Kensuke Fukuda1, Hirotaka Matsuzaki2, Takuya Kawahara3
1Department of Respiratory Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.
Background:
Minimal pleural fluid is often seen incidentally on chest MRI. However, its prevalence and clinical characteristics remain unknown.
Methods:
This retrospective observational study included 2726 participants who underwent comprehensive medical check-ups for screening, including chest CT and MRI, and transthoracic echocardiography between March 2018 and February 2019. Pleural fluid on MRI was manually measured for maximum thickness. Its distribution, change over time, and relevance to participant characteristics were analyzed. The pulmonary function data of 82 participants and their associations with fluid were also analyzed.
Results:
Of the 2726 participants (mean age ± standard deviation, 59 ± 11 years), 2009 (73.7%) had minimal pleural fluid (thickness, 1-9 mm) on either side, with right-sided fluid being more frequent than left-sided fluid (P < 0.001). Negligible changes in fluid thickness were observed one year later. The following parameters were associated with less fluid: age, ≥65 years (P < 0.001); male sex (P = 0.006); current smoking (P < 0.001); body mass index, ≥25 kg/m2 (P < 0.001); and mean arterial pressure, ≥100 mmHg (P = 0.01), whereas a ratio between early mitral inflow velocity and mitral annular early diastolic velocity>14 was associated with more fluid (P = 0.01). The presence of fluid was an independent explanatory variable for a higher percentage of predicted vital capacity (P = 0.048).
Conclusions:
MRI was highly sensitive in detecting minimal pleural fluid. Pleural fluid found on MRI for health screening was assumed to be physiological and fluid thickness at the steady state might be variable among participants depending on age, sex, smoking habits, body shape, blood pressure, and cardiac diastolic capacity.
Insights
Minimal pleural fluid is commonly detected on chest MRI scans. Its presence and thickness are influenced by factors like age, sex, smoking, body mass index, blood pressure, and cardiac function.
Area of Science:
- Radiology
- Pulmonology
- Cardiology
Background:
- Minimal pleural fluid is frequently observed incidentally during chest MRI examinations.
- The prevalence and clinical significance of this finding are not well-established.
Purpose of the Study:
- To determine the prevalence and clinical characteristics of minimal pleural fluid detected on chest MRI.
- To investigate the association of pleural fluid with participant demographics, physiological parameters, and pulmonary function.
Main Methods:
- A retrospective observational study analyzed data from 2726 participants undergoing medical screening with chest CT, MRI, and echocardiography.
- Pleural fluid on MRI was manually measured for thickness, distribution, and changes over time.
- Associations with participant characteristics and pulmonary function were statistically analyzed.
Main Results:
- 73.7% of participants exhibited minimal pleural fluid (1-9 mm thickness) on MRI, with right-sided prevalence.
- Fluid thickness showed negligible changes over one year.
- Factors associated with less fluid included older age, male sex, current smoking, higher BMI, and higher mean arterial pressure. Higher mitral inflow velocity to annular velocity ratio was associated with more fluid.
- Pleural fluid presence independently predicted higher predicted vital capacity.
Conclusions:
- Chest MRI is highly sensitive for detecting minimal pleural fluid.
- Minimal pleural fluid detected during health screening is likely physiological.
- Fluid thickness varies based on age, sex, smoking status, body habitus, blood pressure, and cardiac diastolic function.
Related Concept Videos
01:24Magnetic Resonance Imaging
01:30Pleural Disorders: Types and Brief Description
01:25Pleural Effusion I: Introduction
There are two main types of pleural effusion: transudative and exudative. They are differentiated using Light's criteria,...
01:28Pleural Effusion II: Symptoms and Management
A pleural effusion is the abnormal collection of fluid between the parietal and visceral pleura layers of tissue that form the lining of the lungs and chest cavity. It can occur independently or due to surrounding parenchymal diseases, such as infection, malignancy, or inflammatory conditions.
Clinical Manifestations:
01:30Radiological Investigation II: MRI and Ventilation Perfusion Scan
Magnetic Resonance Imaging (MRI) and Ventilation Perfusion Scans are two radiological investigations that offer detailed diagnostic images of the body, particularly lung structures.
MRI
MRI uses magnetic fields and radiofrequency signals to distinguish between normal and abnormal tissues. This technology provides a more detailed diagnostic image than CT scans, enabling it to characterize pulmonary nodules, stage bronchogenic carcinoma, and evaluate inflammatory activity in...
01:14Imaging Studies I: CT and MRI
Description of the Procedures
Computed Tomography (CT) scan:
Computed Tomography (CT) scans use X-ray technology to generate detailed images of bones, organs, and tissues. During the scan, the patient lies on a moving table...