Incidental findings detection using low tube potential for CT pulmonary angiography

While lowering the radiation dose using a reduced tube potential (kVp) strategy for CT pulmonary angiography (CTPA) maintains accuracy for pulmonary embolism detection, there is no data regarding the effect of increased noise from lower kVp on both the accuracy of lung and mediastinum lesion detection in the same patient cohort. This study compares the accuracy and diagnostic confidence of lung nodules and enlarged mediastinal lymph nodes detection between low and standard kVp CTPA. The study cohort included 272 CTPA studies acquired at low kVp and 274 studies at standard kVp. Each patient had a routine chest CT acquired within 60 days of the CTPA that served as a reference standard for lung and mediastinum lesions. In additional to the evaluation of image quality, two radiologists independently interpreted lung nodules and mediastinal lymph nodes on CTPA and recorded confidence level for each interpretation. Multivariate models assessed effect of kVp settings on diagnostic accuracy and confidence level in interpretation. Low kVp CTPAs had higher image noise. A significant decrease in the confidence levels for evaluation of mediastinal lymph nodes was observed at low kVp by one of two readers, although there was no significant correlation between accuracy of interpretation and kVp settings for lung and mediastinum lesion detection (adjusted odds ratios = 0.67-1.22, p values >0.2). While increased image noise may decrease the diagnostic confidence of the radiologist, the detection of lung nodules and enlarged mediastinal lymph nodes was not compromised. Referring clinicians can expect that lower radiation dose CTPA answers questions related to lungs and mediastinum.