Incidental central pulmonary emboli in outpatients with deep vein thrombosis.

BACKGROUND: While it has been demonstrated that large asymptomatic pulmonary embolism (PE) can occur, many studies have assessed inpatients or patients with known risk factors for venous thromboembolism (such as malignancy). There are few data regarding incidental PE in outpatients with deep vein thrombosis (DVT) or assessing whether these emboli occur centrally or peripherally in the pulmonary arteries. AIMS: To determine the rates of incidental central and peripheral PE in outpatients with proximal and distal DVT. METHODS: This was a retrospective cross-sectional study of 120 patients attending our community imaging clinic between January 2015 and March 2020, with ultrasound-confirmed lower limb DVT, and subsequent computed tomography pulmonary angiogram (CTPA) within 24 h. Exclusion criteria were symptoms indicative of PE. Imaging reports were retrospectively reviewed to record the proximity of DVT and the location of any PE as either central (pulmonary trunk or main pulmonary arteries) or peripheral (lobar, segmental or subsegmental pulmonary arteries). RESULTS: Incidental PE occurred in 71 patients (59.2%), with a rate of 77.5% in proximal and 50.0% in distal DVT. Sixteen patients had central PE (13.3% of all patients with DVT; 22.5% of all patients with PE). Two patients (both with proximal DVT) had PE in the pulmonary trunk. CONCLUSIONS: Incidental PE occur frequently in outpatients with lower limb DVT, including the possibility of asymptomatic central emboli. Further studies with larger patient cohorts would be useful to assess the utility of baseline chest imaging in outpatients with DVT.

Dynamic four-dimensional computed tomography (4D CT) imaging for re-entry risk assessment in re-do sternotomy - first experience.

BACKGROUND: Repeat cardiac surgeries are well known to have higher rates of complications, one of the important reasons being injuries associated with re-do sternotomy. Routine imaging with CT can help to minimise this risk by pre-operatively assessing the anatomical relation between the sternum and the underlying cardiovascular structures, but is limited by its inability to determine the presence and severity of functional tethering and adhesions between these structures. However, with the evolution of wide area detector MD CT scanners, it is possible to assess the presence of tethering using the dynamic four-dimensional CT (4D CT) imaging technique. METHODS: Nineteen patients undergoing re-do cardiac surgery were pre-operatively imaged using dynamic 4D CT during regulated respiration. The datasets were assessed in cine mode for presence of differential motion between sternum and underlying cardiovascular structures which indicates lack of significant tethering. RESULTS: Overall, there was excellent correlation between preoperative imaging and intraoperative findings. The technique enabled our surgeons to meticulously plan the procedures and to avoid re-entry related injuries. CONCLUSIONS: Our initial experience shows that dynamic 4D CT is useful in risk stratification prior to re-do sternotomy by determining the presence or absence of tethering between sternum and underlying structures based on assessment of differential motion. Furthermore we determined the technique to be superior to non-dynamic assessment of retrocardiac tethering.