Role of spiral
volumetric computed tomographic scanning in the assessment
of patients with clinical suspicion of pulmonary embolism
and an abnormal ventilation/perfusion lung scan.
Ab Van Rossum, Fee
Treurniet, Gj Kieft, Sj Smith, R Schepers-Bok
Thorax 1996; 51:
Background: A study was carried out to
evaluate the potentiel place of spiral volumetric computed
tomography (SVCT) in the diagnostic strategy for pulmonary
Methods: In a prospective study 249
patients with clinical suspicion of pulmonary embolism were
evaluated with various imaging techniques. In all patients a
ventilation/perfusion (V/Q) scan was performed. Seventy
seven patients with an abnormal V/Q scan underwent SVCT.
Pulmonary angiography was then performed in all 42 patients
with a non-diagnostic V/Q scan and in three patients with a
high probability V/Q scan without emboli on the SVCT scan.
Patients with an abnormal perfusion scan also underwent
ultrasonography of the legs for the detection of deep vein
Results: One hundred and seventy two
patients (69%) had a normal V/Q scan. Forty two patients (17
%) had a non-diagnostic V/Q scan, and in five of these
patients pulmonary emboli were found both by SVCT and
pulmonary angiography. In one patient, although SVCT showed
no emboli, the angiogram was positive for pulmonary
embolism. In one of the 42 patients the SVCT scan showed an
embolus which was not confirmed by pulmonary angiography.
The other 35 patients showed no sign of emboli. Thirty five
patients (14 %) had a high probability V/Q scan, and in 32
patients emboli were seen on SVCT images. Two patients had
both a negative SVCT scan and a negative pulmonary
angiogram. In one who had an inconclusive SVCT scan
pulmonary angiography was positive. The sensitivity for
pulmonary embolism was 95 % and the specificity 97 %, the
positive and negative predicted values of SVCT were 97% and
Conclusions: SVCT is a relatively non-invasive test for
pulmonary embolism which is both sensitive and specific and
which may serve as an alternative to ventilation
scintigraphy and possibly to pulmonary angiography in the
diagnostic strategy for pulmonary embolism.