CT spots COVID-19 lung abnormalities in Diamond Princess cruise ship passengers

Chest computed tomography imaging performed in patients aboard the Diamond Princess cruise ship revealed lung abnormalities between asymptomatic and symptomatic patients with COVID-19.

Imaging experts from Japan retrospectively looked at the scan data from more than 100 individuals with the coronavirus who were aboard the quarantined ship in February. The findings, published March 18 in Radiology: Cardiothoracic Imaging, showed abnormalities in patients both with and without virus symptoms.

Shohei Inui, with Japan Self-Defense Forces Central Hospital’s Department of Radiology and colleagues, however, pointed to one finding in particular.

“Although lung parenchymal and airway abnormalities were more frequent in symptomatically than asymptomatic cases, noticeably, we found lung parenchymal changes on CT in up to 54% of the asymptomatic cases,” the authors wrote.

The Diamond Princess cruise ship was carrying nearly 3,700 passengers when it was forced into quarantine at Yokohama Bay, in Japan, on Feb. 3. At that time, it was considered the largest cluster of COVID-19 cases outside of China. After leaving the ship on Feb. 14, passengers underwent real-time reverse transcription polymerase chain-reaction testing and were sent to the Japan Self-Defense Forces Central Hospital by the government.

For their research, Inui et al. analyzed 112 cases of the coronavirus in patients with an average age of 62 years. The team calculated a severity score for each lung lobe and the entire organ from CT images, comparing asymptomatic (82 cases) and symptomatic (30) patients.

Out of the asymptomatic cases, 54% showed signs of pneumonia; while 80% of CT scans from symptomatic cases showed abnormal findings. Additionally, those without symptoms showed more ground-glass opacity predominance over consolidation. Symptomatic cases more often yielded consolidation.

The authors also noted that asymptomatic images showed milder CT severity scores compared to the others.

Additional investigations will be required, especially to pin-down radiological findings in asymptomatic cases, the group noted.

And while this study shouldn’t encourage clinicians to use chest CT for screening patients, its sensitivity is “unquestionable and encouraged for cases where there is need to determine the extension of disease and alternative diagnoses,” Inui and colleagues wrote.

“Before arriving at any such conclusion, the bioactivity and clinical impact of asymptomatic CT findings in COVID-19 infection will have to be investigated,” they added.

The American College of Radiology recently released its own CT recommendations for radiologists, telling physicians not to use it as a first-line test. Meanwhile, a March 12 study published in the European Journal of Radiology found specific CT imaging features could also help clinicians determine the severity of the coronavirus in individual patients.