Ventilation/perfusion tomography – V/P-SPECT vs planar technique

Abstract

Pulmonary embolism (PE) can only be diagnosed with imaging techniques, which in practice is performed using ventilation/perfusion scintigraphy(V/P scintigraphy) or multi-detector computed tomography of the pulmonary arteries (MDCT). The basic principle for the diagnosis of PE based upon V/P scintigraphy is to recognize lung segments or subsegments without perfusion but preserved ventilation, i. e. mismatch. Ventilation/ perfusion single photon emission tomography - V/P SPECT has during the last 10 years started to replace V/P planar based on higher sensitivity, specificity and low non-diagnostic findings.

A twenty seven year old woman was suspected for PE when presented to the out-patient clinic due to dyspnea, frequent yawing, oppression in the throat, 3 days after being treated of superficial varices cruris with foam sclerotherapy - UGFS. She was first examined with chest x-ray, MDCT, hearth ultrasonography and V/P planar. V/P planar was reported as very low probability for PE. All the other initial examinations were normal. Patient symptoms did not decline, and reffering clinitian put her on therapy with LMWH. Fifth days later reffering doctor recomended V/P SPECT. V/P SPECT has shown billateral PE, with the cca 35% extent of PE. Patient was followed up clinically and with V/P SPECT one month later. The control V/P SPECT was normal. This case presented importance of high clinical probability and value of V/P SPECT over another imaging technique for detection of PE.