Prospective evaluation of unsuspected pulmonary embolism on contrast enhanced multidetector CT (MDCT) scanning

Abstract

Aim: To quantify the incidence of unsuspected pulmonary emboli (PE) in an unselected inpatient population undergoing contrast enhanced multidetector CT (MDCT) scanning of the thorax and to assess aetiological factors in their development. Methods: All inpatients undergoing MDCT scanning of the thorax over a 10 month period were prospectively identified. Patients with previous or suspected current PE were excluded. CT scans were reviewed and the degree of contrast enhancement and presence of PE recorded. Where PE was found, the level of the most proximal thrombus was identified. Patient age, length of admission, slice scan thickness and clinical indication were noted. Results: 547 inpatients who had undergone MDCT scanning were identified. Following exclusions 487 remained, 28 of whom (5.7%) had PE. Unsuspected PE was more common with increasing age, occurring in 9.2% (20/218) of all patients over 70 years and 16.7% (11/66) of those over 80 years (p,0.001). Eighteen of the 28 positive scans (64.3%) were at the segmental or subsegmental level. No other aetiological factor was identified which significantly increased the incidence of unsuspected PE. No significant difference was noted between 4-slice and 16-slice MDCT. Nine of the cases of incidental PE (32.1%) were not identified by the original reporting radiologists. Conclusion: PE is an unsuspected finding on contrast enhanced MDCT scanning of the thorax in 5.7% of all inpatients. The incidence is higher in older patients. Most are peripheral and .30% are missed on initial review. PE should be routinely sought in all contrast enhanced MDCT scans of the chest, irrespective of the indication for the CT scan.

Time Trends In Pulmonary Embolism In The United States: Evidence Of Overdiagnosis?

“…Signs of recent or prior pulmonary embolism can be identified in more than half of autopsies if the pulmonary arteries are meticulously examined. 9 Moreover, among consecutive patients undergoing contrast chest CT for unrelated reasons (e.g., cancer staging), unsuspected emboli are found in 4% overall, 25 in 17% of patients over age 80, 26 and in 24% of asymptomatic trauma patients. 27 Second, evidence of overdiagnosis of pulmonary embolism initially arose in the randomized trial comparing CTPA to ventilationperfusion scan: while the CTPA arm detected more patients with pulmonary embolism, there was no apparent improvement in outcomes.…”

Correlation Between Clot Load Burden with Neutrophil-Lymphocyte and Platelet-Lymphocyte Ratios in Patients with Acute Pulmonary Embolism

“…Ulutas Med J 2017;3(1): [13][14][15][16][17][18][19] and specificity values of CTPA increased, making it the first-line imaging method (17)(18)(19)(20). CTPA allows not only detection of presence of thrombus but also calculation of the pulmonary arterial computed tomographic obstruction index ratio (PACTOIR), which indicates the degree of thrombus and yields objective results (1).…”

“…Ulutas Med J 2017;3(1): [13][14][15][16][17][18][19] then calculated as: (n×d)/40×100 [n=score of embolus multiplied by the number of dependent segments; d=degree of obstruction].…”

Dual-energy computed tomography in pulmonary embolism

“…In a study by Ritchie et al [17], only 68% of patients with pulmonary emboli (19/28) were initially reported as having PE at the MDCT pulmonary angiogram. In the remaining 32% of cases (9/28) in which PE was not identified, the embolus was at the segmental level or located more distally.…”

“…All other contrast enhancement defects, such as patchy or band-like defects without segmental distribution or complete loss of colour coding (indicating lack of air-containing voxels owing to consolidation), were inconsistent with PE [19]. DECT angiography not only depicts the contrast enhancement defects resulting from acute PE (Figure 4), but also shows contrast enhancement defects associated with chronic clots ( Figure 5) [13,17,19,20,21]. Recently, Fink et al [19] reported that both the sensitivity and specificity of DECT for the assessment of PE were 100% on a per patient basis.…”