When Free Air Means Emergency: Imaging Diagnosis of Pneumoperitoneum in Glioblastoma Patients

 

Introduction

When a Single Line of Air Determines Life or Death

The emergency department is filled with countless patients presenting with abdominal pain, distension, nausea, and vague discomfort. Most ultimately prove to have benign, self-limited conditions. Yet among these seemingly routine presentations lies one radiologic finding that instantly changes the course of clinical care: pneumoperitoneum.

For radiologists and emergency physicians, the detection of free intraperitoneal air represents one of the most critical imaging diagnoses in medicine. A subtle crescent of gas beneath the diaphragm on an upright chest radiograph may be the only early clue to catastrophic gastrointestinal perforation. Failure to recognize this sign can delay surgical intervention, leading to overwhelming sepsis, multiorgan failure, and death.

The presented case exemplifies this diagnostic challenge. A 70-year-old woman with advanced glioblastoma multiforme arrived at the emergency department after experiencing three days of progressively worsening abdominal distension and pain. Her medical history included chronic dexamethasone therapy for cerebral edema associated with glioblastoma. Physical examination revealed abdominal tympany, cachexia, and shallow respirations without classic signs of generalized peritonitis.

At first glance, the clinical presentation appeared deceptively nonspecific. However, the imaging findings immediately transformed the differential diagnosis. Upright posteroanterior and lateral chest radiographs demonstrated extensive subdiaphragmatic free air outlining both the inferior surface of the liver and the spleen—classic evidence of pneumoperitoneum highly suggestive of gastrointestinal perforation.

This case serves as a powerful reminder that conventional radiography, despite the rapid evolution of advanced cross-sectional imaging and artificial intelligence, continues to play a pivotal role in emergency diagnosis. In many institutions worldwide, the upright chest radiograph remains the fastest, most accessible, and most cost-effective method for identifying life-threatening free intraperitoneal air.

Furthermore, the case illustrates an often-overlooked complication of prolonged corticosteroid therapy. Dexamethasone, a cornerstone medication for managing cerebral edema in patients with glioblastoma, significantly increases the risk of gastrointestinal ulceration and bowel perforation, particularly in elderly or medically fragile patients.

Beyond the individual patient, this scenario highlights broader themes shaping contemporary radiology:

• Early detection through imaging
• Integration of artificial intelligence into emergency workflows
• Clinical decision support systems
• AI-assisted triage in emergency departments
• Precision medicine guided by imaging biomarkers
• Human-AI collaboration in diagnostic radiology

As healthcare increasingly embraces intelligent imaging technologies, understanding both classic radiographic signs and emerging AI applications becomes essential for every radiologist.

---

Clinical Background

Pneumoperitoneum: A Radiologic Emergency

Pneumoperitoneum refers to the abnormal presence of free gas within the peritoneal cavity. In approximately 90% of cases, it indicates perforation of a hollow abdominal viscus and therefore constitutes a surgical emergency.

The most common causes include:

• Perforated peptic ulcer
• Diverticulitis
• Colonic malignancy
• Ischemic bowel disease
• Inflammatory bowel disease
• Traumatic bowel injury
• Iatrogenic perforation after endoscopy
• Anastomotic leak following surgery

In oncology patients, additional risk factors include:

• Corticosteroid therapy
• Chemotherapy
• Radiation enteritis
• Immunosuppression
• Malnutrition
• Tumor invasion of the bowel

Among these, corticosteroid-associated gastrointestinal perforation is particularly insidious because steroids may blunt the inflammatory response, masking the typical clinical signs of peritonitis and delaying diagnosis.

---

Why Glioblastoma Patients Are at Higher Risk

Glioblastoma multiforme is the most aggressive primary brain tumor in adults. Patients commonly require prolonged corticosteroid therapy to control vasogenic edema surrounding the tumor.

Dexamethasone remains the preferred corticosteroid because of its potent anti-inflammatory effects and minimal mineralocorticoid activity. However, chronic administration carries substantial risks, including:

• Gastric ulcer formation
• Duodenal ulceration
• Delayed tissue healing
• Immunosuppression
• Gastrointestinal hemorrhage
• Bowel perforation

In this patient, dexamethasone likely contributed to occult gastrointestinal ulceration that ultimately progressed to perforation and massive pneumoperitoneum.

The absence of anti-angiogenic therapy further supports corticosteroid exposure as the principal pharmacologic risk factor.

---

Imaging Findings

Figure 1. Upright Chest PA Radiograph

Radiology Interpretation

The upright posteroanterior chest radiograph demonstrates a large volume of subdiaphragmatic free intraperitoneal air beneath the right hemidiaphragm. Gas extends inferiorly to outline the liver margin and gallbladder fossa, creating a striking radiographic appearance strongly suggestive of pneumoperitoneum secondary to bowel perforation.

Teaching Points

• Crescent-shaped subdiaphragmatic lucency
• Visualization of both diaphragms
• Abnormally sharp hepatic border
• Large volume free intraperitoneal air
• Surgical emergency

---

Figure 2. Lateral Chest Radiograph

Radiology Interpretation

The lateral projection confirms extensive free intraperitoneal gas surrounding the spleen and anterior upper abdomen. This orthogonal view eliminates uncertainty regarding bowel gas overlap and significantly increases diagnostic confidence for free peritoneal air.

Key Radiologic Signs

• Splenic outlining
• Free anterior abdominal gas
• Elevated diaphragms
• Massive pneumoperitoneum
• Confirmation of perforated viscus

---

Figure 3. Coronal Non-Contrast CT

Radiology Interpretation

Coronal CT images demonstrate diffuse free intraperitoneal gas distributed throughout the upper and lower abdomen without evidence of physiologic postoperative air. CT confirms extensive pneumoperitoneum and allows localization of the suspected gastrointestinal perforation while evaluating associated complications such as ascites, abscess formation, bowel ischemia, or pneumatosis intestinalis.

Major CT Findings

• Massive free intraperitoneal air
• Extensive anterior abdominal gas
• Coronal visualization improves lesion conspicuity
• Strong evidence of bowel perforation
• Immediate surgical consultation indicated

Advanced Radiologic Interpretation

Why Every Radiologist Should Carefully Examine the Diaphragm

In emergency radiology, the diaphragm is far more than an anatomic boundary between the thoracic and abdominal cavities—it is one of the most important "search areas" on every upright chest radiograph.

Although clinicians often focus on pulmonary infiltrates, pleural effusions, or cardiac enlargement, an experienced radiologist routinely inspects the subdiaphragmatic regions before evaluating the lungs. This systematic approach frequently leads to the earliest diagnosis of life-threatening abdominal emergencies.

The current case illustrates this principle perfectly. Rather than subtle pulmonary pathology, the most striking abnormality was a large crescent of free gas beneath the right hemidiaphragm extending inferiorly to outline the liver and gallbladder fossa, an appearance highly characteristic of pneumoperitoneum.

Recognition of this finding immediately shifts clinical priorities from evaluating abdominal discomfort to initiating emergency surgical consultation.

---

Figure 1 Interpretation: Upright Chest PA

Diagnostic Impression

The posteroanterior chest radiograph demonstrates:

• Massive subdiaphragmatic free air
• Continuous radiolucency beneath the right hemidiaphragm
• Sharp visualization of the hepatic margin
• Air outlining the gallbladder fossa
• No evidence of postoperative change

These findings strongly indicate perforation of a hollow abdominal viscus until proven otherwise.

Why the Right Side Is Easier

Radiologists generally identify pneumoperitoneum beneath the right hemidiaphragm more readily because:

• the liver provides a homogeneous soft-tissue background,
• even a small amount of free air becomes conspicuous,
• bowel gas normally occupies the left upper quadrant, making interpretation more challenging.

As little as 1–2 mL of free intraperitoneal gas may be detected on an upright chest radiograph when image quality and patient positioning are optimal.

---

Figure 2 Interpretation: Lateral Chest Radiograph

The lateral chest projection is often underappreciated in emergency practice.

In this patient, the lateral view demonstrates extensive anterior free intraperitoneal gas outlining the spleen and upper abdomen, confirming that the lucency observed on the frontal radiograph represents true free air rather than overlapping bowel loops.

Advantages of the lateral view include:

• improved detection of small anterior gas collections,
• differentiation from gastric fundal air,
• confirmation of subdiaphragmatic free gas,
• increased diagnostic confidence.

Modern emergency imaging protocols increasingly rely on CT; however, upright PA plus lateral chest radiographs remain highly valuable, particularly in resource-limited settings or when CT availability is delayed.

---

Figure 3 Interpretation: Coronal CT

Computed tomography remains the gold standard for evaluating pneumoperitoneum.

The coronal non-contrast CT image demonstrates:

• extensive free air throughout the abdomen,
• accumulation beneath the anterior abdominal wall,
• diffuse intraperitoneal gas,
• findings highly suggestive of bowel perforation.

Compared with conventional radiography, CT provides several critical advantages:

✔ Detection of minute gas collections

✔ Localization of the perforation site

✔ Identification of bowel wall defects

✔ Assessment of ischemia

✔ Detection of associated abscess

✔ Evaluation of ascites

✔ Surgical planning

---

CT Signs Every Radiologist Must Know

1. Extraluminal Free Air

The hallmark sign.

Gas is visualized outside the bowel lumen and often accumulates:

• beneath the diaphragm,
• around the liver,
• around the spleen,
• within the lesser sac,
• beneath the anterior abdominal wall.

---

2. Falciform Ligament Sign

Large amounts of free air may outline the falciform ligament, making it visible on CT or radiography.

Normally this ligament cannot be seen.

---

3. Rigler Sign

Also called the double-wall sign.

Both sides of the bowel wall become visible because gas is present inside the bowel and within the peritoneal cavity.

This finding indicates substantial pneumoperitoneum.

---

4. Football Sign

Massive free intraperitoneal gas outlines the abdominal cavity.

The abdomen resembles an American football.

Although more common in pediatric patients, adults with severe perforation may also demonstrate this sign.

---

5. Cupola Sign

Gas accumulates beneath the central tendon of the diaphragm.

Often overlooked.

May represent one of the earliest indicators of free intraperitoneal air.

---

Differential Diagnosis

Although free subdiaphragmatic air usually indicates bowel perforation, several conditions can mimic pneumoperitoneum.

---

1. Chilaiditi Sign

Interposition of colon between:

• liver
• diaphragm

Radiographic clues:

✔ visible haustral folds

✔ bowel wall markings

✔ stable appearance

No surgical emergency.

---

2. Subphrenic Abscess

May produce gas beneath the diaphragm.

However,

CT typically demonstrates

• fluid collection
• enhancing wall
• inflammatory fat stranding.

---

3. Basal Lung Disease

Lower lobe atelectasis or large pulmonary bullae may occasionally mimic subdiaphragmatic gas.

Orthogonal imaging eliminates confusion.

---

4. Gastric Fundus

The gastric bubble normally lies beneath the left hemidiaphragm.

Recognition of its typical morphology prevents false-positive interpretation.

---

5. Postoperative Pneumoperitoneum

Free intraperitoneal air may persist:

• 3–7 days after laparotomy,
• occasionally longer after laparoscopy.

Clinical history is essential.

---

Why Did This Patient Develop Pneumoperitoneum?

The patient had multiple risk factors:

✓ Advanced age

✓ Malnutrition

✓ Cachexia

✓ Chronic corticosteroid therapy

✓ Malignancy

✓ Immunosuppression

The manuscript specifically notes that she had been receiving dexamethasone for cerebral edema related to glioblastoma and had not undergone anti-angiogenic therapy, making corticosteroid-associated gastrointestinal perforation the most likely contributing factor.

---

Steroid-Induced Gastrointestinal Perforation

Dexamethasone is indispensable in neuro-oncology because it rapidly reduces vasogenic edema and intracranial pressure.

However, prolonged exposure may produce:

• impaired mucosal regeneration,
• reduced prostaglandin synthesis,
• delayed ulcer healing,
• suppression of inflammatory responses,
• increased susceptibility to ulcer formation and perforation.

An important clinical consequence is that corticosteroids can mask the classic manifestations of peritonitis. Patients may present with relatively mild abdominal findings despite catastrophic bowel perforation, making imaging the decisive diagnostic tool.

---

Imaging–Clinical Correlation

This case demonstrates why radiologists should integrate imaging findings with the patient's medical history.

The combination of:

• glioblastoma,
• chronic dexamethasone therapy,
• progressive abdominal distension,
• cachexia,
• extensive subdiaphragmatic free air on chest radiography,

strongly supports a perforated gastrointestinal ulcer leading to massive pneumoperitoneum rather than a benign cause of intraperitoneal gas.

Furthermore, the patient's goals of care favored comfort-directed management rather than emergency surgery. Bedside decompression was performed for symptom relief, and she died shortly thereafter, underscoring the severity of the underlying pathology and the importance of timely diagnosis in similar patients.

---

Clinical Pearl

Never dismiss free air beneath the diaphragm as an incidental finding. In an elderly patient receiving chronic corticosteroids—particularly one with cancer—even subtle subdiaphragmatic gas should prompt immediate evaluation for occult gastrointestinal perforation. Rapid recognition on chest radiography can dramatically alter clinical management and may be life-saving.

Why Artificial Intelligence Matters in Emergency Radiology

Emergency radiology operates under immense time pressure. Every minute counts when diagnosing life-threatening conditions such as bowel perforation, intracranial hemorrhage, pulmonary embolism, or tension pneumothorax. Delayed recognition of pneumoperitoneum can rapidly lead to diffuse peritonitis, septic shock, multiorgan failure, and death.

Although experienced radiologists recognize free intraperitoneal air with high accuracy, increasing imaging volumes, overnight staffing shortages, and physician fatigue contribute to perceptual errors. AI is emerging as a critical second reader that helps identify urgent findings, prioritize worklists, and reduce diagnostic delays.

The presented case underscores this opportunity. The patient's upright chest radiograph demonstrated extensive subdiaphragmatic free air, a finding that an AI-enabled triage system could immediately flag as critical, accelerating communication with emergency physicians and surgeons.

---

AI-Powered Emergency Imaging Workflow

A modern AI-assisted emergency imaging pathway may proceed as follows:

This workflow does not replace the radiologist. Instead, it augments clinical efficiency by ensuring that critical examinations are reviewed first and by reducing the likelihood of overlooked abnormalities.

---

Computer Vision for Pneumoperitoneum Detection

Computer vision models analyze chest radiographs and CT scans by learning complex imaging patterns associated with disease. In pneumoperitoneum, these algorithms are trained to recognize:

• Crescent-shaped subdiaphragmatic lucency
• Abnormal gas outlining the liver or spleen
• Rigler sign
• Falciform ligament sign
• Cupola sign
• Free anterior abdominal air
• Extraluminal gas on CT
• Bowel wall discontinuity

Unlike traditional rule-based systems, deep learning algorithms extract thousands of imaging features simultaneously, allowing them to detect subtle abnormalities that may be difficult for human observers during high-workload periods.

---

Deep Learning in Chest Radiography

Deep convolutional neural networks (CNNs) have revolutionized chest radiograph interpretation. Originally developed for detecting pulmonary nodules, pneumonia, and pneumothorax, these models are increasingly being adapted to identify abdominal emergencies visible on chest imaging.

For pneumoperitoneum detection, a CNN typically processes the image through multiple layers:

Heatmaps generated by explainable AI (XAI) techniques visually highlight the regions that influenced the model's prediction, improving transparency and clinician confidence.

---

Explainable AI (XAI): Building Trust

One of the challenges in clinical AI adoption is the "black box" nature of deep learning. Explainable AI addresses this issue by providing visual and quantitative explanations for AI predictions.

In pneumoperitoneum detection, XAI can:

• Highlight subdiaphragmatic free air
• Delineate suspicious regions
• Display confidence scores
• Compare current images with prior studies
• Explain why a case was flagged as urgent

This transparency enhances clinician trust and supports regulatory approval for AI-assisted diagnostic systems.

---

Foundation Models in Radiology

Foundation models represent the next generation of medical AI. Unlike task-specific algorithms, foundation models are trained on millions of images and can perform multiple functions using a shared architecture.

Potential applications include:

• Detection of pneumoperitoneum
• Identification of bowel obstruction
• Recognition of pneumatosis intestinalis
• Localization of perforation
• Structured report generation
• Differential diagnosis suggestions
• Clinical question answering
• Image summarization

These models integrate vision and language, enabling them to interpret images while generating clinically meaningful narrative reports.

---

Generative AI for Radiology Reporting

Large language models (LLMs) are increasingly being incorporated into radiology workflows to assist with structured reporting.

For the present case, a generative AI system might draft the following report:

Findings: Upright chest radiographs demonstrate a large volume of free subdiaphragmatic air beneath the right hemidiaphragm extending to outline the inferior hepatic margin. Lateral radiographs confirm anterior free intraperitoneal gas. Coronal CT images reveal diffuse pneumoperitoneum consistent with perforation of a hollow viscus.

Impression: Massive pneumoperitoneum highly suspicious for gastrointestinal perforation. Immediate surgical consultation is recommended.

The radiologist remains responsible for reviewing, editing, and approving the final report, ensuring accuracy and accountability.

---

Clinical Decision Support Systems (CDSS)

Clinical Decision Support Systems integrate imaging findings with electronic health records, laboratory data, and medication histories to provide context-aware recommendations.

In this case, the system could combine:

• Imaging evidence of free intraperitoneal air
• History of glioblastoma
• Chronic dexamethasone therapy
• Cachexia
• Progressive abdominal pain

to generate an alert:

High Risk: Suspected steroid-associated gastrointestinal perforation. Recommend urgent surgical evaluation.

Such integrated systems help prioritize patients who require immediate intervention and reduce the risk of missed diagnoses.

---

AI Integration with PACS

Modern Picture Archiving and Communication Systems (PACS) increasingly incorporate AI modules that automatically analyze incoming studies.

An AI-enabled PACS workflow includes:

Benefits include:

• Faster turnaround times
• Improved emergency prioritization
• Reduced reporting delays
• Enhanced communication with clinical teams
• Lower risk of missed critical findings

---

Enterprise AI Platforms and Cloud Infrastructure

Large healthcare networks are increasingly deploying enterprise AI platforms hosted on secure cloud infrastructure. These platforms enable:

• Real-time image analysis across multiple hospitals
• Centralized AI model updates
• Scalable deployment without local hardware limitations
• Integration with hospital information systems
• Continuous performance monitoring and quality assurance

Cloud-based AI also facilitates multicenter collaboration, allowing institutions to benefit from shared algorithms and larger training datasets while maintaining patient privacy through secure data governance.

---

Human–AI Collaboration: The Future Standard

Despite rapid technological advances, AI is not a replacement for radiologists. Instead, the most effective model is one of collaboration.

Radiologists contribute:

• Clinical judgment
• Contextual interpretation
• Correlation with patient history
• Communication with referring physicians
• Ethical decision-making

AI contributes:

• Rapid image screening
• Quantitative analysis
• Detection of subtle abnormalities
• Workflow prioritization
• Report drafting assistance

Together, this partnership enhances diagnostic accuracy, efficiency, and patient safety.

---

AI Pearl

Artificial intelligence is most valuable not when it replaces human expertise, but when it amplifies it. In emergency imaging, AI can rapidly identify critical findings such as pneumoperitoneum, but definitive diagnosis still depends on the radiologist's integration of imaging, clinical history, and patient-specific factors.

From Image to Intervention: Diagnostic Workflow for Pneumoperitoneum

The diagnosis of pneumoperitoneum extends far beyond simply identifying free air on an image. Once free intraperitoneal gas is recognized, clinicians must rapidly determine the underlying cause, assess the patient's physiological status, and initiate appropriate management. Every hour of delay in treating a perforated viscus increases the risk of septic shock, multiple organ dysfunction, and mortality.

The presented patient arrived with progressive abdominal distension and pain over three days, accompanied by cachexia and chronic dexamethasone therapy for glioblastoma-related cerebral edema. Imaging revealed extensive pneumoperitoneum, strongly suggesting gastrointestinal perforation. Because of the patient's advanced malignancy and previously established goals of care, comfort-directed treatment rather than emergency surgery was chosen.

This case highlights an essential principle in emergency medicine: the imaging diagnosis is only the beginning of a broader clinical decision-making process.

---

Comprehensive Diagnostic Workflow

This structured workflow emphasizes that radiologists are not merely image interpreters but central participants in multidisciplinary emergency care.

---

Imaging-Based Management Algorithm

Once pneumoperitoneum is identified, clinicians should rapidly evaluate:

Step 1. Confirm Free Intraperitoneal Air

Use:

• Upright chest radiography
• Left lateral decubitus abdominal radiography (if necessary)
• CT abdomen and pelvis

CT remains the definitive imaging modality for confirming free air and identifying the perforation site.

---

Step 2. Determine the Cause

Possible etiologies include:

• Perforated peptic ulcer
• Colonic diverticulitis
• Colon cancer
• Small bowel ischemia
• Inflammatory bowel disease
• Traumatic perforation
• Iatrogenic injury
• Steroid-associated ulcer perforation
• Chemotherapy-related bowel injury

Clinical history and imaging findings should always be interpreted together.

---

Step 3. Assess Clinical Stability

Evaluate:

• Blood pressure
• Heart rate
• Respiratory status
• Lactate
• White blood cell count
• Signs of septic shock
• Peritoneal irritation

Not all patients with pneumoperitoneum require surgery, but all require urgent evaluation.

---

Step 4. Select Appropriate Management

Treatment options include:

Emergency Surgery

• Exploratory laparotomy
• Laparoscopic repair
• Bowel resection
• Peritoneal lavage

Nonoperative Management

Reserved for selected patients with:

• Minimal symptoms
• Sealed perforation
• High surgical risk
• Advanced terminal illness

In the present case, palliative decompression was performed in accordance with the patient's wishes.

---

Key Imaging Pearls Every Radiologist Should Know

Pearl 1: Always inspect beneath both hemidiaphragms before evaluating the lungs.

---

Pearl 2: Even 1–2 mL of free air may be visible on an upright chest radiograph.

---

Pearl 3: The right hemidiaphragm is generally easier to assess because the liver provides a uniform soft-tissue background.

---

Pearl 4: The lateral chest radiograph can confirm subtle anterior free air when the frontal projection is equivocal.

---

Pearl 5: CT is substantially more sensitive than radiography for detecting minimal pneumoperitoneum.

---

Pearl 6: Steroid therapy may suppress inflammatory signs, making imaging findings disproportionately severe compared with the physical examination.

---

Pearl 7: Do not confuse the Chilaiditi sign with pneumoperitoneum.

---

Pearl 8: Rigler sign indicates gas on both sides of the bowel wall and usually reflects significant free intraperitoneal air.

---

Pearl 9: Coronal CT reconstructions improve visualization of free air distribution and potential perforation sites.

---

Pearl 10: Clinical history remains indispensable. In this case, chronic dexamethasone therapy markedly increased suspicion for steroid-associated gastrointestinal perforation.

---

Pearl 11: Always compare with prior imaging when available to distinguish new free air from expected postoperative findings.

---

Pearl 12: Massive pneumoperitoneum may occasionally produce the "football sign," particularly in severe perforations.

---

Pearl 13: In elderly oncology patients, subtle abdominal symptoms may conceal catastrophic intra-abdominal pathology.

---

Pearl 14: Early communication with the treating physician is as important as the written report. Critical findings should be conveyed immediately.

---

Pearl 15: Artificial intelligence can accelerate detection, but final responsibility for diagnosis rests with the interpreting radiologist.

---

Common Diagnostic Pitfalls

Even experienced clinicians can encounter challenges when interpreting suspected pneumoperitoneum.

Pitfall 1: Mistaking Chilaiditi Sign for Free Air

Interposed colon between the liver and diaphragm can mimic pneumoperitoneum. Identification of haustral folds prevents misdiagnosis.

---

Pitfall 2: Ignoring Small Crescentic Lucencies

Minimal subdiaphragmatic gas may represent the earliest stage of perforation. Small findings should never be dismissed without clinical correlation.

---

Pitfall 3: Assuming a Normal Physical Examination Excludes Perforation

Patients receiving corticosteroids may have surprisingly mild abdominal tenderness despite severe gastrointestinal perforation.

---

Pitfall 4: Overlooking the Lateral Radiograph

The lateral projection can reveal free anterior intraperitoneal air not readily apparent on the frontal image.

---

Pitfall 5: Delayed Communication

Critical imaging findings lose value if they are not promptly communicated. Immediate verbal notification of the clinical team is often warranted.

---

Future Perspectives: The Next 5–10 Years

Emergency radiology is undergoing a profound transformation driven by artificial intelligence, cloud computing, and precision medicine.

Over the next decade, several developments are expected to shape the field:

• Fully integrated AI-assisted emergency triage
• Multimodal foundation models combining imaging and clinical data
• Real-time structured reporting
• Automated perforation localization
• Predictive analytics for patient deterioration
• Federated learning across hospital networks
• Continuous AI quality monitoring
• Personalized imaging pathways based on individual risk profiles

These innovations will enhance—not replace—the expertise of radiologists, enabling faster diagnosis and more informed clinical decision-making.

---

Integrating High-Value Healthcare Technologies

As healthcare organizations modernize their imaging infrastructure, several technologies are becoming increasingly important:

• Enterprise AI Platforms streamline the deployment of validated algorithms across hospital systems, ensuring consistent performance and centralized governance.
• Clinical Decision Support Systems (CDSS) integrate imaging, laboratory, medication, and clinical data to provide context-aware recommendations, particularly valuable in complex emergency cases such as suspected bowel perforation.
• PACS Solutions with embedded AI modules can automatically prioritize studies containing critical findings, reducing turnaround times for emergency cases.
• Cloud Healthcare Infrastructure enables secure image sharing, remote consultation, scalable AI deployment, and multicenter collaboration without the need for extensive on-premises hardware.
• AI Diagnostic Software continues to evolve from simple abnormality detection toward comprehensive workflow assistance, including image interpretation, structured reporting, and quality assurance.

These technologies not only improve patient care but also align with the increasing demand for efficient, scalable, and data-driven radiology services in modern healthcare systems.

---

Conclusion.

This case illustrates how a seemingly routine chest radiograph can reveal a life-threatening abdominal emergency. The combination of vigilant image interpretation, awareness of steroid-associated gastrointestinal complications, and timely clinical communication remains the cornerstone of successful diagnosis.

At the same time, advances in artificial intelligence, enterprise imaging platforms, and clinical decision support are reshaping emergency radiology. The future lies in human–AI collaboration, where technology enhances the radiologist's ability to detect subtle findings rapidly while preserving the indispensable role of clinical judgment.

Key Takeaways

1. Pneumoperitoneum is a Radiologic Emergency

Free intraperitoneal air should always be considered evidence of gastrointestinal perforation until proven otherwise. Prompt recognition can significantly influence patient outcomes.

---

2. Chest Radiography Remains Highly Valuable

Despite widespread CT availability, the upright chest radiograph continues to be one of the fastest and most cost-effective methods for detecting free subdiaphragmatic air.

---

3. CT is the Gold Standard

CT provides:

• Highest sensitivity
• Precise perforation localization
• Surgical planning
• Detection of associated complications
• Assessment of bowel ischemia

---

4. Steroid Therapy Can Mask Perforation

Patients receiving dexamethasone may have minimal abdominal tenderness despite catastrophic gastrointestinal perforation. Imaging frequently establishes the diagnosis before clinical deterioration becomes obvious.

---

5. AI Will Transform Emergency Imaging

Artificial intelligence is rapidly improving:

• Emergency triage
• Chest X-ray detection
• Structured reporting
• Clinical Decision Support
• PACS workflow
• Radiologist efficiency

However, radiologists remain indispensable for integrating imaging findings with clinical context and guiding patient management.

---

FAQ

What is pneumoperitoneum?

Pneumoperitoneum refers to the presence of free air within the peritoneal cavity. In approximately 90% of cases, it results from perforation of a hollow abdominal organ and requires urgent evaluation.

---

Can a chest X-ray detect bowel perforation?

Yes. An upright chest radiograph is often the first imaging study to reveal subdiaphragmatic free air, making it a valuable tool for diagnosing bowel perforation.

---

Why does dexamethasone increase perforation risk?

Prolonged corticosteroid therapy impairs mucosal healing, suppresses inflammation, and increases the risk of gastrointestinal ulceration and perforation, particularly in vulnerable patients.

---

Is CT better than chest X-ray?

CT is more sensitive and can localize the perforation site while identifying associated complications. However, chest radiography remains an excellent initial screening examination in emergency settings.

---

Can AI diagnose pneumoperitoneum?

AI systems can rapidly detect imaging patterns suggestive of pneumoperitoneum, prioritize urgent studies, and assist radiologists. Final diagnosis should always be confirmed by a qualified physician.

---

References

[1] A. Adam, A. K. Dixon, J. H. Gillard, and C. Schaefer-Prokop, Grainger & Allison's Diagnostic Radiology, 7th ed. Philadelphia, PA, USA: Elsevier, 2021. ISBN: 9780702075247. (Book; no DOI).

[2] J. S. Brant and V. M. Mellnick, Brant & Helms' Fundamentals of Diagnostic Radiology, 6th ed. Philadelphia, PA, USA: Wolters Kluwer, 2025. ISBN: 9781975199005. (Book; no DOI).

[3] A. Soto and B. Lucey, Diagnostic Imaging: Emergency, 3rd ed. Salt Lake City, UT, USA: Elsevier Amirsys, 2019. ISBN: 9780323524780. (Book; no DOI).

[4] P. Rajpurkar and M. P. Lungren, "The Current and Future State of AI Interpretation of Medical Images," New England Journal of Medicine, vol. 388, no. 21, pp. 1981–1990, May 2023. doi:10.1056/NEJMra2301725.

[5] G. Grassi, M. Romano, A. Pinto, et al., "Gastro-duodenal perforation: Conventional radiology, multidetector computed tomography and ultrasound findings," Insights into Imaging, vol. 12, no. 1, 2021. doi:10.1186/s13244-021-01060-4.

[6] A. M. Coppolino, A. Gatta, et al., "Gastrointestinal perforation: Ultrasonographic diagnosis," Critical Ultrasound Journal, vol. 5, Suppl. 1, 2013. doi:10.1186/2036-7902-5-S1-S4.

[7] S. Mularski, G. Sippel, and W. Osborne, "Pneumoperitoneum: A Review of Nonsurgical Causes," Critical Care Medicine, vol. 28, no. 7, pp. 2638–2644, 2000. doi:10.1097/00003246-200007000-00078.

[8] E. J. Topol, "High-performance medicine: the convergence of human and artificial intelligence," Nature Medicine, vol. 25, pp. 44–56, 2019. doi:10.1038/s41591-018-0300-7.

[9] D. Shen, G. Wu, and H.-I. Suk, "Deep Learning in Medical Image Analysis," Annual Review of Biomedical Engineering, vol. 19, pp. 221–248, 2017. doi:10.1146/annurev-bioeng-071516-044442.

[10] G. Litjens et al., "A Survey on Deep Learning in Medical Image Analysis," Medical Image Analysis, vol. 42, pp. 60–88, 2017. doi:10.1016/j.media.2017.07.005.

[11] S. Bommasani et al., "On the Opportunities and Risks of Foundation Models," Stanford Center for Research on Foundation Models, 2021. arXiv:2108.07258.

[12] H. Moor et al., "Foundation Models for Generalist Medical Artificial Intelligence," Nature, vol. 616, pp. 259–265, 2023. doi:10.1038/s41586-023-05881-4.

[13] J. Esteva et al., "A Guide to Deep Learning in Healthcare," Nature Medicine, vol. 25, pp. 24–29, 2019. doi:10.1038/s41591-018-0316-z.

[14] M. McKinney et al., "International Evaluation of an AI System for Breast Cancer Screening," Nature, vol. 577, pp. 89–94, 2020. doi:10.1038/s41586-019-1799-6.

[15] A. Rajkomar, J. Dean, and I. Kohane, "Machine Learning in Medicine," New England Journal of Medicine, vol. 380, no. 14, pp. 1347–1358, 2019. doi:10.1056/NEJMra1814259.