Introduction of helical computed tomography affects patient selection for V/Q lung scan

Retrospective analysis for determination of the effect of helical computed tomography (HCT) on utilization of V/Q lung scanning to diagnose pulmonary embolism (PE) in a large general hospital.

A total number of 2676 V/Q scans of in- and out-patients referred to our department between March 1992 and December 1998 and between April 1997 and December 1998 were analyzed by an identical group of nuclear physicians.

Neither the total number of annually performed V/Q scans (446 +/- 135) nor the mean age of patients (56 years +/- 17) changed significantly since the introduction of HCT. However, the referral pattern was different. The percentage of patients with high and intermediate probability for PE decreased significantly from 15.2% to 9.4% (p < 0.01) and from 10.2% to 7.3% (p < 0.05), respectively. Low probability scans significantly increased from 37.8% to 42.7% (p < 0.05). The percentage of normal scans did not change significantly, however, there was a highly significant increase summarizing patients with normal and low probability scans (74.6% to 83.3%; p < 0.01).

The introduction of HCT affected the selection of patients referred for V/Q lung scanning since V/Q scanning was primarily used to exclude rather to confirm PE.