Focal eventration
In focal eventration (focal eventration), standard radiography and computed tomography serve as the primary imaging modalities.
On chest X-rays (CXR) performed in posterior-anterior (PA) and lateral projections, eventration appears as a distinct soft-tissue density opacity. This opacity arises with a broad base directly from the diaphragmatic dome.
To accurately verify the contents of this protrusion, computed tomography (CT) is used. Tomograms reliably confirm that unchanged liver tissue is located beneath the locally elevated area of the diaphragm. In cases where a large diaphragmatic hernia forms on the left, the left hemithorax may be filled with loops of the small intestine, requiring special care when interpreting scans.
Diaphragmatic trauma: diagnostic challenges
Diagnosis of traumatic diaphragmatic injuries is a major clinical challenge. Rupture of the thoracoabdominal barrier is rarely isolated: most commonly, it accompanies severe chest or abdominal trauma. Due to the need for emergency surgical intervention for these associated injuries, many diaphragmatic tears are diagnosed intraoperatively, i.e., directly on the operating table.
If urgent surgery is not indicated for the patient, a diaphragmatic tear is easily missed. The risk of diagnostic error is especially high if the muscular dome defect is small and abdominal organs do not herniate into it (herniation).
The radiologist must maintain high vigilance and suspect a occult rupture in cases of:
- Any trauma to the lower chest.
- Severe pelvic bone fractures.
Rules of radiologic evaluation in trauma
To detect injuries, extremely careful analysis of both classical chest radiographs and multislice computed tomography (MSCT / MDCT) is required. The generation of high-quality coronal and sagittal reconstructions plays a key role.
During image interpretation, special attention should be paid to the following signs:
- Minimal contour changes of the diaphragm (irregularities, local deformations).
- Basal atelectasis of the lung (collapse of lung tissue in areas adjacent to the diaphragm).
- Areas of consolidation (opacification) of the lung tissue in the lower lobes.
The diagnostician's main rule: any post-traumatic chest images must be compared with the patient's previous (archival) radiographs, if available. This allows differentiation of fresh traumatic deformations from preexisting eventration or anatomical variants.
Phases of injury diagnosis
The algorithm for imaging examination directly depends on the phase of the traumatic disease the patient is in.
1. Acute phase (Acute phase) During this period, patients are often unstable and present with polytrauma requiring emergency surgery. Therefore, diagnostics is based on bedside examinations (bedside examinations), which include ultrasound and portable chest X-ray. Features of the radiological picture in the acute phase:
- About 25% of cases present with an absolutely normal radiograph.
- Pathological shadows of gas and fluid in the pleural cavity may be detected on the images.
- Often, the only direct sign is a local density (density) closely adjacent to the diaphragm, or an inconspicuous change in the contour of the dome itself.
2. Latent phase (Latent phase) If the patient has survived the acute period, a wider range of more complex modalities is used to clarify the nature of the injuries. These include CT, Magnetic resonance imaging (MRI), as well as specialized barium contrast studies (barium studies) that help assess gastrointestinal tract involvement.
Briefly: answers to topical questions
What are the anatomical and radiological differences between true diaphragmatic relaxation and a diaphragmatic hernia?
Anatomincal continuity of the diaphragm is preserved in true diaphragmatic relaxation, whereas a defect is present in a diaphragmatic hernia. In relaxation, part of the normal muscle tissue of the diaphragm is replaced by a thin layer of connective tissue with rare muscle fibers. Differential diagnosis of localized relaxation, small hernia, and mass lesion is performed using CT or MRI in the coronal and sagittal planes.
What are the causes of acquired diaphragmatic relaxation other than trauma?
The main cause of acquired diaphragmatic relaxation is paralysis followed by muscle atrophy. In turn, phrenic nerveparesis or paralysis can be caused by various pathological conditions, including tumor invasion, radiation therapy, and neurological diseases such as poliomyelitis, herpes zoster, and cervical spondylosis.
Which specific CT signs (symptoms) reliably indicate a diaphragmatic rupture?
Specific computed tomography signs of traumatic diaphragmatic rupture include a direct violation of its integrity with visualization of the injury as the "missing diaphragm sign" and rolling inward of the torn dome edges ("hanging diaphragm sign"). Herniation of adjacent abdominal organs, thickening of the diaphragmatic crus ("thickened crus sign"), constriction of the stomach or intestine at the defect ("collar sign"), mushroom-like liver deformation ("hump sign"), and a linear lucency along the torn edges ("band sign") are also informative.
To detect occult diaphragmatic injury, remember the triad of imaging findings: Contour (look for minimal changes) — Atelectasis (in the basal regions) — Consolidation (pulmonary parenchymal opacity).
What else to study on this topic
- Features of MDCT semiotics: coronal and sagittal reconstructions of the diaphragmatic contour
- Differential diagnosis of basal atelectasis and traumatic lung injury
- Bedside ultrasound in unstable patients with suspected diaphragmatic rupture
- Evaluation of barium contrast studies in diaphragmatic trauma
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