Pulmonary fat embolism syndrome: CT findings in six patients

A Fatal Case of Cerebral Fat Embolism: A Case Report

Fat embolism syndrome (FES) is a rare but serious multisystem syndrome that occurs after 0.9% to 2.2% of fractures, with long bone and pelvic fractures being the most common. The classic triad of FES consists of neurological impairment, respiratory insufficiency, and petechial rash, which develops 12-72 hours after the initial incident. We hereby present a case of a patient who developed persistent altered consciousness, seizures, and hypoxia secondary to a comminuted sacral fracture. Although the patient could not survive owing to multiple factors, imaging played a pivotal role in expediting the diagnostic process and aiding early management.

Systemic Lupus Erythematosus Presenting as Pulmonary Embolism After Liposuction: A Clinical Conundrum

Systemic lupus erythematosus (SLE) is an autoimmune disorder with a wide array of presentations and a predilection to affect women of certain ethnic backgrounds. The hallmark of the disease is multisystem involvement, dispersed in time and severity. Usual pulmonary involvement includes pleuritis, pleural effusions, pneumonitis, shrinking lung syndrome, pulmonary hypertension, and alveolar hemorrhage. Pulmonary embolism (PE) is a relatively unusual presentation of SLE. We present the case of a 28-year-old Hispanic female who presented with shortness of breath and chest pain after liposuction and was found to have a PE. Fat embolism was ruled out. The absence of overt signs and symptoms and traditional risk factors prompted a fragmentary workup. This led to the detection of antibodies sensitive and specific for SLE, in the absence of overt signs and symptoms. We revive the concept of latent lupus, a condition construed as early lupus. Since our patient was lost to follow up, we were unable to complete workup for SLE, but firmly suspect direct causation between SLE and PE. Further studies are needed to establish pathogenesis in order to facilitate early diagnosis and prevent morbidity and mortality from PE.

Approaching pulmonary fat embolism on postmortem computed tomography

PURPOSE

Pulmonary fat embolism (PFE) is a relevant diagnosis playing a role as a sign of vitality or a cause of death. Its severity is assessed according to histological grading systems like that of Falzi. The aim of this study was to determine the utility of unenhanced postmortem computed tomography (PMCT) for PFE diagnosis based on the detection of fat layers.

METHODS

Consecutive cases with PMCT and autopsy were studied retrospectively. The case group consisted of cases with positive PFE, and the control group included cases with negative PFE. Three observers independently assessed PMCT data for fat layers in the pulmonary trunk and the right and left pulmonary artery. For cases with fat layers, autopsy protocols were assessed for the cause of death, relation to trauma, and undertaken resuscitation measures.

RESULTS

Eight hundred thirty cases were included: 366 PFE positive cases (144 of Falzi grade 1, 63 of 1.5, 99 of 2, 28 of 2.5, and 32 of 3) and 464 PFE negative cases. Interrater reliabilities varied between substantial and almost perfect, and discrepancies were solved according to majority. Eighteen cases showed fat layers on PMCT (2 controls-traumatic instantaneous deaths-, 16 PFE positive cases). PMCT showed low sensitivity but high specificity for PFE diagnosis. The layers were located at the same position in the pulmonary trunk directly adjacent to the pulmonary valve distal to the right ventricle.

CONCLUSION

Fat layer on PMCT is a rare finding but relates to PFE diagnosis, especially of severe histological grade. It is to be expected in a typical position within the pulmonary trunk.

Post-traumatic Severe Fat Embolism Syndrome with Uncommon CT Findings

Although the diagnosis of fat embolism syndrome is usually based on clinical findings, we describe ill-defined centrilobular and subpleural nodules in addition to ground-glass opacities and consolidation on a computed tomography scan of the chest in a trauma patient with fat embolism syndrome. The nodules presumably represent alveolar oedema, microhaemorrhage and an inflammatory response secondary to ischaemia and cytotoxic emboli in fat embolism syndrome. The literature of computed tomography findings in patients with fat embolism syndrome is reviewed and summarized.

Case 254: Posttraumatic Migrating Fat Embolus Causing Fat Emboli Syndrome

History An otherwise healthy 18-year-old man was admitted to the emergency department with a closed displaced fracture of the left femoral shaft ( Fig 1 ) after a high-velocity motorbike accident. At admission, other physical examination findings were unremarkable. Initial unenhanced and contrast material-enhanced (120 mL of Iomeron 400; Bracco Imaging, Milan, Italy) computed tomography (CT) was performed in the arterial and venous phases from the head to the knees. No abnormalities were noted in the brain or chest at initial CT. [Figure: see text] Within a few hours, the patient developed sudden mental confusion and severe hypoxemia, with rapidly worsening tachypnea and perturbed arterial blood gas with low partial pressure of oxygen (61 mmHg [8.1 kPa]; normal range, 75-100 mmHg [10.0-13.3 kPa]) and low partial pressure of carbon dioxide (32 mmHg [4.3 kPa]; normal range, 38-42 mmHg [5.1-5.6 kPa]). A second contrast-enhanced chest CT examination and initial brain magnetic resonance (MR) imaging were performed. Femoral fracture was stabilized with external fixation, and the patient was admitted to the intensive care unit, with progressive neurologic recovery at day 3 and respiratory improvement at day 4. Treatment included intubation with mechanical ventilation and intravenous administration of steroids and noradrenaline. Afterward, the femoral fracture was stabilized with an intramedullary nail. The patient made a full neurologic recovery 1 month after the accident.

Rare imaging of a known entity: fat embolism seen on CT in lower extremity vein after trauma

Fat embolism occurs in the vast majority of patients who have had trauma (approximately 90%). The most common occurrence is after long bone fracture. It has also been noted in cases after orthopedic surgery. Fat embolism is most often diagnosed when the clinical manifestations of fat embolism syndrome become apparent. Reported cases of fat emboli in transit are unusual. In our case, we present the rare finding of fat embolism seen on computed tomography in the lower extremity after a trauma.

Fat Embolism Syndrome: Lung Computed Tomography Findings in 18 Patients

OBJECTIVE

The purpose of this study was to evaluate the lung computed tomography (CT) findings in fat embolism (FE) syndrome.

METHODS

We retrospectively evaluated 19 CT examinations of 18 patients with FE syndrome, diagnosed clinically using the Gurd and Wilson criteria.

RESULT

Fat embolism syndrome showed 3 patterns: negative examination, bilateral interstitial-alveolar involvement, and adult respiratory distress syndrome like. Frequent findings included consolidations (17 patients), mostly with gravity dependent distribution, and ground-glass opacities (17 patients), mostly with patchy distribution. Fifteen patients showed an overlapping random nodular pattern. Less common findings included lobular ground-glass opacities and lobular consolidations, smooth septal thickening, thickening of the bronchial wall, and areas of crazy paving. The extension of the consolidations correlates with the duration of assisted ventilation.

CONCLUSIONS

In FE syndrome, pulmonary CT findings are ground-glass opacities and dependent consolidations, associated with other variably overlapping signs, such as lobular opacities, random nodules, septal thickening, and bronchial wall thickening.

Detection of pulmonary fat embolism with dual-energy CT: an experimental study in rabbits

OBJECTIVES

To evaluate the use of dual-energy CT imaging of the lung perfused blood volume (PBV) for the detection of pulmonary fat embolism (PFE).

METHODS

Dual-energy CT was performed in 24 rabbits before and 1 hour, 1 day, 4 days and 7 days after artificial induction of PFE via the right ear vein. CT pulmonary angiography (CTPA) and lung PBV images were evaluated by two radiologists, who recorded the presence, number, and location of PFE on a per-lobe basis. Sensitivity, specificity, and accuracy of CTPA and lung PBV for detecting PFE were calculated using histopathological evaluation as the reference standard.

RESULTS

A total of 144 lung lobes in 24 rabbits were evaluated and 70 fat emboli were detected on histopathological analysis. The overall sensitivity, specificity and accuracy were 25.4 %, 98.6 %, and 62.5 % for CTPA, and 82.6 %, 76.0 %, and 79.2 % for lung PBV. Higher sensitivity (p < 0.001) and accuracy (p < 0.01), but lower specificity (p < 0.001), were found for lung PBV compared with CTPA. Dual-energy CT can detect PFE earlier than CTPA (all p < 0.01).

CONCLUSION

Dual-energy CT provided higher sensitivity and accuracy in the detection of PFE as well as earlier detection compared with conventional CTPA in this animal model study.

KEY POINTS

• Fat embolism occurs commonly in patients with traumatic bone injury. • Dual-energy CT improves diagnostic performance for pulmonary fat embolism detection. • Dual-energy CT can detect pulmonary fat embolism earlier than CTPA.

Fat embolism syndrome: State-of-the-art review focused on pulmonary imaging findings

BACKGROUND

Fat embolism syndrome (FES) is a rare but potentially fatal complication of trauma or orthopedic surgery, which presents predominantly with pulmonary symptoms. Modern intensive care has improved the mortality rates, however diagnosis remains difficult, relying predominantly on a combination of a classic triad of symptoms and non-specific, but characteristic radiological features. The aim of this review is to describe the main clinical and imaging aspects of FES, ranging from pathophysiology to treatment with emphasis on pulmonary involvement.

METHODS

We reviewed the currently published literature on the main characteristics of FES.

RESULTS

In a hypoxic patient with recent trauma or orthopedic surgery, the presence of diffuse, well-demarcated ground glass opacities or ill-defined centrilobular nodules on computed tomography (CT) of the chest are suggestive of FES.

CONCLUSIONS

Combination of the classic clinical syndrome in the appropriate clinical setting, together with the characteristic imaging findings on chest CT, can help to achieve the correct diagnosis. Management remains predominantly supportive care, and the benefit of medical therapies such as corticosteroids and heparin remains unclear.

Non-infectious Parenchymal Lung Disease

Acute dyspnea is a common presenting complaint in the emergency room, emergency medicine and intensive care. It may have a cardiovascular or a non-cardiovascular origin, the latter including pulmonary parenchymal diseases. Depending on the cause, it may be associated with fever, cough, hemoptysis, and/or chest pain, with a duration of symptoms that can range from hours to days.

Prompt identification of the underlying cause of acute dyspnea is essential in guiding appropriate therapy and management, as patients may rapidly progress to acute respiratory failure. Evaluation with chest radiography is vital for initial assessment and may reveal diffuse parenchymal abnormalities, which may require further assessment with computed tomography (HRCT).

Acute non-infectious parenchymal lung diseases are often overlooked and may be under-diagnosed. Their diagnosis requires the evaluation, along with the HRCT pattern, of the clinical and laboratory features and of the bronchoalveolar lavage. Biopsy may be necessary in more complex cases.

Although the most frequent cause of diffuse non-infectious parenchymal lung involvement is acute hydrostatic pulmonary edema, there is a wide variety of diseases that may be encountered, including acute drug toxicity, hypersensitivity pneumonitis (HP), acute respiratory distress syndrome (ARDS) and diffuse alveolar hemorrhage (DAH). In trauma patients, fat embolism syndrome (FES) must be taken into account. Acute respiratory failure is an eventuality that can occur during the course of chronic lung diseases (UIP for example), which may have been unknown until then.

Massive systemic fat embolism detected by postmortem imaging and biopsy

Postmortem computed tomography (pmCT) and pmCT angiography (pmCTA) provide a minimally invasive method to determine the cause of death. Postmortem image-guided biopsy allows for precise sampling of histological specimens. This case study describes the findings of lethal systemic fat embolism (FE) on whole-body unenhanced pmCT, pmCTA, and image-guided biopsy, with autopsy and histopathologic correlation. Unenhanced pmCT revealed a distinct fat level on top of sedimented layers of corpuscular blood particles and serum in the arterial system and pulmonary trunk. Subsequent pmCTA showed reproducible results, and image-guided biopsy confirmed fatal FE. pm CT/pmCTA combined with image-guided biopsy established the cause of death as right heart failure as a result of systemic fatal FE prior to autopsy. All imaging findings were consistent with traditional autopsy and histological specimens. This unique case demonstrates new imaging findings in massive, fatal FE and highlights that postmortem imaging, supplemented by image-guided biopsy, may detect the cause of death prior to traditional autopsy.

Acute respiratory distress following intravenous injection of an oil-steroid solution

A case of acute respiratory distress and hypoxemia following accidental intravenous injection of an oil-steroid solution in a body builder is presented. Chest roentography at the time of presentation showed diffuse bilateral opacities, and computed tomography revealed predominantly peripheral ground-glass opacifications. The patient's symptoms gradually improved over 48 h and imaging of the chest was unremarkable one week later. The pathophysiology, diagnosis and treatment of this rare but potentially lifethreatening complication of intravenous oil injection are discussed.

Interstitial lung disease outcomes by high-resolution computed tomography (HRCT) in Anti-Jo1 antibody-positive polymyositis patients: a single centre study and review of the literature

Interstitial lung disease (ILD) is a frequent complication of inflammatory myopathies with high rates of morbidity and mortality. Antibodies against aminoacyl-tRNA-synthetases are the strongest predictive factors in ILD. In this study, we reviewed the literature and we retrospectively analysed high-resolution computed tomography (HRCT) findings in a cohort of 131 consecutive subjects: 75 with polymyositis (PM), 43 with dermatomyositis (DM), one with amyophatic PM, two with paraneoplastic syndromes, and 10 with overlapping syndromes. The inclusion criteria were PM/DM, anti-Jo1 antibody positivity, and HRCT-assessed ILD. The effect of 12 months' treatment with cyclophosphamide (CYC) or cyclosporin A (CsA) plus steroids was assessed by comparing baseline and follow-up HRCT scans for evidence of stability, improvement or worsening. Fifteen patients (11.5%) had ILD and were Jo-1 positive. They were all women with PM, and had a mean age of 47.33 years and a median duration of symptoms of 7.26 months. At baseline, HRCT showed ground-glass attenuations in eight cases, septal thickening in seven, and honeycombing in four. Twelve months after diagnosis, ILD had worsened in nine patients (60%; exact confidence interval [ECI] 32-84) and was stable in four (two patients were lost to follow-up). Seven of the 15 patients were treated with CsA, and 12-month HRCT revealed a worsening in ILD in five cases (71%; ECI 0.29-0.96); ILD also worsened (ECI 16-84) in four of the eight patients treated with CYC pulses (50%). The evolution of the HRCT findings was not significantly different between the two groups. Our findings confirm that ILD is a common early manifestation in patients with Jo1-positive PM. Over twelve months, HRCT showed worsening ILD in most of our patients, with no difference in the HRCT changes between those treated with CYC or CsA.

Experimental pulmonary fat embolism: computed tomography and pathologic findings of the sequential changes

This study was done to demonstrate the computed tomography (CT) and pathologic findings of the sequential changes for experimental pulmonary fat embolism (PFE), and to correlate the CT and pathologic findings of rabbit lung. PFE was induced by an intravenous injection of 0.2 mL linoleic acid in 24 rabbits. The rabbits were divided into 4 groups of 6 rabbits each. CT scans were obtained sequentially at 2 hr (n= 24), day 1 (n=18), day 3 (n=12) and day 7 (n=6) after fat embolization. The pathologic findings were analyzed and CT-pathologic correlation was done. CT scans showed bilateral ground-glass opacity (GGO), consolidation and nodule in all cases. The findings of PFE at 2 hr after fat embolization were areas of decreased attenuation, GGO, consolidation and nodule. These findings were aggravated on the follow- up CT after 1 day and 3 days. The follow-up CT revealed linear density in the subpleural lungs after 7 days. On CT-pathology correlation, wedge-shaped ischemic necrosis in the subpleural lungs correlated with nodule at 2 hr. GGO and consolidation at day 1 on CT correlated with congestion and edema, and these findings at day 3 were correlated with inflammation and hemorrhagic edema. The linear density in the subpleural lungs correlated with interstitial fibrosis and pleural contraction at day 7. In conclusion, PFE was caused by using linoleic acid which is kind of free fatty acid and this study served as one model of the occurrence of nontraumatic PFE. CT accurately depicted the natural evolution of PFE in the serial followup, and this correlated well with the pathologic findings.

Pulmonary Fat Embolism

Fat embolism syndrome (FES) is a common complication of fractures, usually of the long bones and pelvis. Common computed tomography findings of pulmonary FES include areas of consolidation, ground-glass opacities, and small nodules of various sizes, whereas filling defects in pulmonary arteries are rarely described in nonfulminant syndromes. We present an unusual case of nonfulminant pulmonary FES in which computed tomography disclosed multiple macroscopic pulmonary fat emboli associated to diffuse ground-glass attenuation in both lungs.

Fatal cerebral emboli in the absence of a cardiac arterial-venous shunt: case report

Cerebral embolism in patients undergoing total joint arthroplasty has an incidence rate of 0.5%. In those cases where cerebral emboli were confirmed, a venous-to-arterial circulation shunt, most commonly a patent foramen ovale, was identified. We report a case of severe cerebral fat emboli during cementless total hip arthroplasty in the absence of an intracardiac defect.

Nodular Pattern at Lung Computed Tomography in Fat Embolism Syndrome

The purpose of this study is to describe the computed tomography (CT) findings in pulmonary fat embolism syndrome (FES). The chest radiographs and CT scans of 5 patients with the diagnosis of FES as determined by the presence of at least 1 major and 4 minor criteria were reviewed. The radiologic features included ground-glass opacities, with different patterns of presentation seen in all patients. Three patients presented with alveolar opacities, and small (<1 cm) ill-defined nodules were seen in 4 of 5 patients. In the context of a patient with previous trauma and the clinical suspicion of FES, the presence of nodules at CT examination may be a helpful finding in the diagnosis of this entity. The chest radiographs and CT scans of 5 patients with the diagnosis of FES as determined by the presence of at least 1 major and 4 minor criteria as defined by Gurd and Wilson were reviewed.

High-resolution CT findings in mild pulmonary fat embolism

OBJECTIVE

The aim of this article is to describe the high-resolution CT (HRCT) findings in mild cases of fat embolism syndrome (FES).

MATERIAL AND METHODS

Nine patients with FES were examined with HRCT of the lungs (collimation, 1 mm/edge-enhancement algorithm). The median age of the patients was 26 years (range, 17 to 35 years). Five cases were included prospectively, and four cases were reviewed retrospectively. Of the major clinical criteria for FES, respiratory signs were present in six patients, CNS signs were present in two patients, and petechiae was present in six patients. HRCT patterns were recorded and analyzed. The type of injury and FES-associated clinical findings were also recorded.

RESULTS

HRCT findings included ground-glass opacities in seven patients, associated with thickened interlobular septa in five patients and a patchy distribution resulting in a geographic appearance in four patients. A nodular pattern was observed in two patients. Resolution of the abnormalities occurred within 16.4 days (range, 7 to 25 days).

CONCLUSION

The HRCT findings of mild fat embolism consist of bilateral ground-glass opacities and thickening of the interlobular septa. Centrilobular nodular opacities are present in some patients.

Radiographic approach to multifocal consolidation

Consolidation in the lung is seen on radiographs or computed tomography (CT) as increased areas of attenuation that obscure the underlying pulmonary vasculature. There are numerous causes of multifocal consolidative opacities. If the symptoms are acute (days to weeks), the most common causes include edema, pneumonia, and hemorrhage. Depending on the patient's history, signs, and symptoms, the less common causes such as radiation pneumonitis or acute eosinophilic syndrome may be considered. If the symptoms are more chronic (weeks to months), the differential may include alveolar proteinosis, neoplasms such as lymphoma or bronchoalveolar cell carcinoma, granulomatous or inflammatory conditions, and lipoid pneumonia. In this article, we review and discuss characteristic radiographic and clinical findings that can aid the radiologist in prioritizing the differential considerations when faced with multifocal parenchymal consolidative disease.

Computed tomography diagnosis of macroscopic pulmonary fat embolism

Pulmonary fat embolism probably occurs commonly after major orthopedic injuries and after orthopedic surgery. Furthermore, tiny fat emboli can often be shown by transesophageal echocardiography during orthopedic surgery. However, large macroscopic are rarely identified radiologically. Macroscopic fat emboli have been previously described in the common femoral vein and inferior vena cava on abdominal imaging. To the authors' knowledge, a macroscopic fat embolus in the pulmonary arteries has not been previously described. The authors report a case of a woman who, on computed tomography, had a large fat embolus after intramedullary rod placement for an isolated left femur fracture.

Nontraumatic pulmonary fat embolism syndrome: radiologic and pathologic correlations

The authors report a case of pulmonary fat embolism syndrome without identifiable cause that was seen on chest radiographs and high-resolution computed tomography as diffuse ground-glass attenuation, particularly in nondependent portions of both lungs. The radiologic findings were shown on open-lung biopsy to represent diffuse pulmonary hemorrhage caused by fat embolism.

Monitoring for suspected pulmonary embolism

It is fortunate that serious embolic phenomena are uncommon because, with the exception of neurosurgery in the sitting position and cardiac surgery, thoracic echocardiography and the precordial Doppler device, the most sensitive indicators of embolism, are seldom used. Vigilance is required of the anesthesiologist to recognize the rapid fall in end-tidal PCO2, the usual first indicator of a clinically significant PE. Any sudden deterioration in the patient's vital signs should include embolism in the differential diagnosis, particularly during procedures that carry a high risk of the complication.