Targeting the MERS virus: Chest CT findings reveal pattern in patients

Recognizing an organizing pneumonia pattern in acutely ill patients living in or traveling from endemic areas could assist in the early diagnosis of Middle East respiratory syndrome coronavirus (MERS-CoV), according to a study published online June 11 by the American Journal of Roentgenology.

Stemming from Saudi Arabia, MERS-CoV is an acute viral respiratory disease that has currently been identified in Jordan, Qatar, the United Arab Emirates, Kuwait, Oman, Tunisia, Germany, France, the U.K., Italy, Yemen, Egypt, Greece, Malaysia, the Philippines and the U.S. Two U.S. citizens were diagnosed with MERS in May, though the Centers for Disease Control and Prevention has confirmed the disease does not appear to have spread to the patients’ family members or care givers.

While the source of the disease is still unknown, the infection’s origin has been linked to camels. Many patients with MERS-CoV develop severe illness, particularly those with lower immunity or certain medical conditions.

Although MERS is gaining attention in both the media and the medical community, little is known about the description of the disease’s imaging features. Moreover, what is known is limited to nonimaging medical literature.

“In patients with acute respiratory symptoms who are living in or traveling from areas of the MERS-CoV outbreak, familiarity with suggestive imaging findings may help with early isolation and management,” wrote lead author Amr M. Ajlan, MD, of the King Faisal Specialist Hospital and Research Center in Jeddah, Saudi Arabia, and colleagues. The researchers conducted their study in order to review and describe the chest CT findings of laboratory-confirmed MERS-CoV cases.

Two fellowship-trained thoracic radiologists independently reviewed CT studies from seven patients. The patient group consisted of five men and two women, ranging between the ages of 19 and 83. The time from the onset of symptoms to hospital presentation ranged from two to 14 days and the main presenting symptoms were cough, fever, dyspnea, sputum production, abdominal pain, back pain, lethargy and myalgia. Four of the patients survived and were eventually discharged.

The radiologists assessed the scans for the presence of ground-glass opacities, consolidation, cavitation, centriobular nodules, tree-in-bud pattern, septal thickening, perilobular opacities, reticulation, architectural distortion, subpleural bands, traction bronchiectasis, bronchial wall thickening, intrathoracic lymph node enlargement and pleural effusions.

In the seven patients, airspace opacities were more common than interstitial changes on the CT studies. Five of the patients had ground-glass opacities and consolidation. One of the seven had isolated ground-glass opacities while another had isolated consolidation. In the patient with isolated ground-glass opacities, CT was performed 49 days after symptom onset and minimal subpleural bands and architectural distortion were present.

Smooth septal thickening was discovered in three of the seven patients. Minimal peripheral reticulation, traction bronchiectasis and perilobular opacities were observed in one patient. Only one patient had both mild bronchial wall thickening and ill-defined centriolobular ground-glass nodules, implicating involvement of small airways.

Lastly, small bilateral pleural effusions were present in three of the seven patients. None of the patients had tree-in-bud pattern, cavitation or intrathroacic lymph node enlargement.

Abnormalities were bilateral in six and unilateral in one of the seven patients. The patient who had unilateral involvement had a single focal consolidation in the left lower lobe. Subpleural and lower lung-predominant airspace involvement were identified in five of the seven patients. In the last two patients, abnormalities were extensive and diffuse, with no clear craniocaudal or transverse predominance.

In four of the five patients with subpleural predominant airspace involvement, variable degrees of periobronchovascular airspace involvement were present.

“The predilection of the abnormalities to the subpleural and peribronchovascular regions is suggestive of an organizing pneumonia pattern,” wrote Ajlan et al. “Recognizing this pattern in acutely ill patients living in or traveling from endemic areas may help in the early diagnosis of MERS-CoV infection,” they concluded.