Objective: To compare, in patients with suspected pulmonary emboli (PE), the probabilistic information provided by V/Q planar scintigraphy to the results obtained with a new home-made lung SPECT methodology.

Methods: 97 consecutive patients (40M, 57F; age 69yrs +/-16) referred to V/Q scintigraphy for clinically suspected PE, were studied between March and September 2008. Planar and SPECT ventilation (Technegas) and perfusion images were sequentially obtained in each patient. Reports were only based on planar imaging and respected PIOPED criteria. Lung SPECT images were retrospectively interpreted according to holistic criteria and using home-made software. SPECT results were compared to the PIOPED interpretation and to the final clinical diagnosis.

Results: SPECT showed PE in 56 (57.7%) of the 97 patients studied, and was negative in 41 (42.3%). SPECT was positive for PE in all patients with a clinical decision to treat PE; none of the negative cases was treated for PE. SPECT showed PE in 49.3% of patients with a low probability report; in 41% of patients from this SPECT positive group, the clinical decision was to treat PE. In the intermediate probability group, SPECT showed PE in 87.5% and, from these, 71% were treated for PE. All the 14 patients in the high probability group had a positive SPECT and were treated.

Conclusion: Our preliminary results show that lung SPECT is more sensitive than planar imaging for the detection of pulmonary emboli and that there is a good agreement between SPECT information and the final diagnosis.