Dose reduction of 69% for CT Pulmonary Angiography: Reduced z-axis CTPA retains accuracy in those <40 years old JCAT
Date
10/01/2013Abstract
OBJECTIVE
We sought to determine whether reduced scan range (z-axis) CTPA technique in 18-40 year age group can accurately detect PE and other important conditions and to quantify the resulting dose reduction.
METHODS AND MATERIALS
We retrospectively identified 200 patients in the age group of 18-40 years who underwent CTPA over a period of three years. These included 86 patients with PEs and 114 randomly selected patients negative for PE (controls). The scans were modified by reducing the scan coverage by eliminating images above the aortic arch and below the base of the heart. Two blinded experienced radiologists rescored them for PE and incidental and pertinent non PE findings. Discrepancies between these and the original report were assessed by a third experienced radiologist.
Separately, a departmental quality control (QC) project was conducted in 15 patients to assess the dose length product along the z-axis across the three zones of thorax.
RESULTS
PE was diagnosed in all 86 patients. No pertinent additional findings were missed. Only seven incidental findings were missed, (e.g. benign thyroid nodules (4), benign adrenal adenoma (1), gallstones (1) and hepatic hemangioma (1)). None affected clinical outcome or management.
DLP was reduced by a mean of 69%. (60-79%)
CONCLUSIONS
Reduced z-axis CTPA for PE is definitely feasible in 18-40 years age-group. There is a
significant radiation reduction (69%) and, hence, should be considered in selected subgroups of patients.