Head-to-head comparison of ventilation/perfusion single photon emission computed tomography/computed tomography and multidetector computed tomography angiography for the detection of acute pulmonary embolism in clinical practice

Abstract

Introduction Computed tomography angiography (CTA) and ventilation/perfusion (V/Q) single photon emission computed tomography/CT (SPECT/CT) images have been widely used to detect PE, but few studies have performed a direct comparison between them. We aimed to evaluate the performance of these tests in the same group of patients, selected from the routine practice of a general hospital. Methods Patients with suspected acute PE were prospectively submitted to CTA and V/Q SPECT/CT. General radiologists and nuclear physicians, respectively, interpreted the images. Data regarding age, sex, time between examinations, symptoms, and Wells score were also recorded. The final diagnosis was decided through a consensus among the clinicians, taking into account clinical, laboratory, follow-up, and all imaging procedures data. Results Twenty-eight patients (15 male, 13 female, and median age of 51.5 years) were studied. Median duration of the onset of symptoms was 4 (1–14) days, and the median Wells score was 3.5 (1.5–6). Sensitivity, specificity, positive and negative predictive values, and accuracy were 84.6%, 80.0%, 78.6%, 85.7%, and 82.1% for V/Q SPECT/CT, and 46.1%, 100%, 100%, 68.2%, and 75.0% for CTA. The overall agreement between the methods was 57.1%. Of the 22 patients with negative CTA, 10 (45.4%) had positives V/Q SPECT/CT and seven of them classified as true positives. Conclusions Our results suggest that V/Q SPECT/CT is more sensitive and accurate than CTA when interpreted by general radiologists and nuclear medicine physicians.

Diagnostic Accuracy of V/Q and Q SPECT/CT in Patients with Suspected Acute Pulmonary Embolism: A Systematic Review and Meta-analysis

“…The number of enrolled patients ranged from 28 44 to 314 41 patients, for a total of 1,086 patients. One study 45 included all patients with cancer, while Bhatia and colleagues 46 included patients with or without pre-existing lung disease.…”

“…SPECT acquisitions were conducted using the following parameters: energy window was 140 KeV for 99m Tc in 5 studies 43 45 46 47 48 (no data were reported in the other 3 studies 41 42 44 ); time for projection ranges from 10 to 25 seconds; number of projection ranges from 30 to 128 for an orbit of 180° to 360° in 6 studies 42 43 44 46 47 48 (no data were reported in the other 2 studies 41 45 ); matrix was 128 * 128 in all studies.…”

“…41 Slice thickness varied between 2.5 and 5 mm in seven studies. 41 43 44 45 46 47 48 One study did not report these data. 42…”

“…mean sensitivity and specificity of V/Q SPECT/CT were 96% (95% CI, 89-98%) and 96% (95% CI, 91-99%), respectively, in 5 studies 41,42,44,45,48 Bivariate weighted mean sensitivity and specificity of Q SPECT/CT were 96% (95% CI, 92-98%) and 84% (95% CI, 66-93%) in 5 studies 42,43,45,46,47 .…”

“…When evaluating the 4 studies 41,43,45,48 with lower concerns of applicability, bivariate weighted mean sensitivity and specificity of SPECT/CT were 94% (95% CI, 85-98%) and 95% (95% CI, 89-98%), respectively.…”