Background:
The COVID-19 pandemic has promoted adaptations in diagnostic algorithms. We explored the feasibility and accuracy of delayed phase (DP) chest computed tomography (CT) performed immediately after brain CT perfusion (CTP) for the identification of thrombotic complications and myocardial fibrosis among patients admitted with acute ischemic stroke (AIS).
Methods:
Since July, we have incorporated the use of low dose chest CT scans using a spectral CT scanner in all patients admitted with AIS, encouraging acquisitions, five min after brain CTP. All scans were non gated and comprised low dose chest CT scans, without additional contrast. Using virtual monochromatic imaging and iodine maps, we evaluated the presence of thrombotic complications, myocardial late enhancement, and myocardial extracellular volume (ECV), as a surrogate of edema and interstitial fibrosis.
Results:
We included 22 patients. The mean age was 66.2±19.6 years. In 5 patients, a cardioembolic (CE) source was later identified by transesophageal echocardiogram (TEE), [left atrial appendage (LAA) thrombus, n=1], transthoracic echocardiogram with agitated saline injection (patent foramen ovale n=2), or by EKG (atrial fibrillation). Seven patients further underwent either TEE or cardiac CT to identify CE sources. DP non gated chest CT had a sensitivity and specificity of 100% to identify CE sources, 1 LAA thrombus correctly detected. Chest CT identified pulmonary thromboembolism (PE), later confirmed with CT angiography. Chest CT identified myocardial late enhancement in 16 patients (80% in CE vs. 71% in non CE, p=0.68), myocardial fat in 1, and coronary calcification in 77% [with 2.6±2.2 vs 3.8±3.6 coronary calcified segments in CE vs. non CE strokes, p=0.36). The mean ECV was 35±4% in CE vs 32±6% in non CE strokes (p=0.17). The 2 patients with a positive PCR test for COVID-19 showed evidence of myocardial late iodine enhancement, and incremented ECV of the septal wall (38% and 40%, respectively).
Conclusions:
In this pilot study, DP, non ECG gated, low dose chest CT scan performed 5 min after brain CTP with a spectral scanner; enabled straightforward identification of CE sources among patients with AIS. This approach allowed detection of PE and myocardial injury.
Dual-Layer Spectral CTA for TAVI Planning Using a Split-Phase Protocol and Low-keV Virtual Monoenergetic Images: Improved Image Quality in Comparison with Single-Phase Conventional CTA