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 outpatient 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.

EANM guideline for ventilation/perfusion single-photon emission computed tomography (SPECT) for diagnosis of pulmonary embolism and beyond

“…Applying these principles of interpretation, recent V/P SPECT studies amounting to over 5000 cases report a negative predictive value of 97–99%, sensitivities of 96–99% and specificities of 96–98% for PE diagnosis. Rates of nondiagnostic findings were 1–4% [61, 68, 69, 71–78].…”

Assessment of pulmonary embolism related to active SARS-CoV-2 infection in pregnant women

“…The main advantages of scintigraphy over computerized tomography (CT) angiography are its high diagnostic sensitivity (100% vs. 83% respectively 7 ) and less irradiation to the patient (effective estimated dose to the mother of 1.62 mSv with a scintigraphy with 111 MBq of 99m Tc-macroaggregate albumin or 99m Tc-MAA vs. 28.39 ± 2.61 with CT) 8 , 9 . In regard to the acquisition protocol, single photon emission computed tomography (SPECT) has been described as superior to planar images (sensitivity and specificity of 100% and 87% vs. 64% and 72%, respectively) 10 , 11 , 12 .…”