Detection of Pulmonary Embolism with Combined Ventilation–Perfusion SPECT and Low-Dose CT: Head-to-Head Comparison with Multidetector CT Angiography

Abstract

The diagnosis of pulmonary embolism (PE) is usually established by a combination of clinical assessment, D-dimer testing, and imaging with either pulmonary ventilation-perfusion (V/Q) scintigraphy or pulmonary multidetector CT (MDCT) angiography. Both V/Q SPECT and MDCT angiography seem to have high diagnostic accuracy. However, only limited data directly comparing these 2 modalities are available. Hybrid g-camera/MDCT systems have been introduced and allow simultaneous 3-dimensional lung V/Q SPECT and MDCT angiography, suitable for diagnosing PE. The aim of our study was to compare, in a prospective design, the diagnostic ability of V/Q SPECT, V/Q SPECT combined with low-dose CT, and pulmonary MDCT angiography obtained simultaneously using a combined SPECT/MDCT scanner in patients suspected of having PE. Methods: Consecutive patients from June 2006 to February 2008 suspected of having acute PE were referred to the Department of Nuclear Medicine at Rigshospitalet or Frederiksberg Hospital, Denmark, for V/Q SPECT as a first-line imaging procedure. The number of eligible patients was 196. Patients with positive D-dimer results (.0.5 mmol/mL) or a clinical assessment with a Wells score greater than 2 were included and underwent V/Q SPECT, lowdose CT, and pulmonary MDCT angiography in a single session. Patient follow-up was 6 mo. Results: A total of 81 simultaneous studies were available for analysis, of which 38% were from patients with PE. V/Q SPECT had a sensitivity of 97% and a specificity of 88%. When low-dose CT was added, the sensitivity was still 97% and the specificity increased to 100%. Perfusion SPECT with low-dose CT had a sensitivity of 93% and a specificity of 51%. MDCT angiography alone had a sensitivity of 68% and a specificity of 100%. Conclusion: We conclude that V/Q SPECT in combination with low-dose CT without contrast enhancement has an excellent diagnostic performance and should therefore probably be considered first-line imaging in the workup of PE in most cases.

The Economic Value of Hybrid Single‐photon Emission Computed Tomography With Computed Tomography Imaging in Pulmonary Embolism Diagnosis

“…SPECT/CT versus CTPA comparison using the study by Gutte et al 14. imaging parameters, our findings demonstrate the total cost burden to be approximately 3.1 million USD for SPECT/CT versus 3.0 million USD for CTPA, leading to an additional PPPM of $3.8 million for SPECT/CT.…”

“…To address some of the inherent limitations arising from using data from multiple studies that encompassed different settings of care (high volume vs. low volume), patient populations (clinical trial vs. retrospective analysis), a third scenario analysis was performed wherein SPECT/CT was explicitly compared to CTPA, the most commonly used imaging modality, the caveat being that the key imaging parameters—sensitivity (97% vs. 67.7%), specificity (100% for both) and nondiagnostic rates (0% for each)—would be derived from head‐to‐head studies alone 14. Similar to our study approach, these parameters would be required to be weighted by the studies’ sample sizes in case of multiple studies with the remaining parameters kept the same as in our base‐case analysis.…”

“…Fusing coregistered functional and anatomic data results in more accurate localization and definition of scintigraphic findings, thus giving SPECT/CT added clinical value over SPECT or stand‐alone CT imaging 5, 13. Gutte et al.,14 performing a head‐to‐head comparison of V/Q SPECT/CT, V/Q SPECT, and CTPA, demonstrated that V/Q SPECT/CT and SPECT had the highest sensitivity (97%), whereas V/Q SPECT/CT and CTPA had the highest specificity (100%), and that V/Q SPECT/CT alone had the highest accuracy rate (99%) among the three modalities. Specifically, the addition of low‐dose noncontrast CT to V/Q SPECT increased specificity from 88% to 100%, without affecting sensitivity.…”

Diagnostic Imaging in Acute Pulmonary Embolism

“…stratejiler önerilmiştir. Tek foton emisyon bilgisayarlı tomografi (SPECT) V/P ile toplanan multiplanar görün-tülerle tanısal olmayan tarama sıklığını azaltabileceği gösterilmiştir (17)(18)(19).…”

Good clinical practice in pulmonary embolism diagnosis: where do we stand today?

“…In the PIOPED II study the positive predictive value for a PE within a lobar pulmonary artery was 97 % but fell to 68 % and 25 % at the segmental and subsegmental levels, respectively. Bajc et al and a prospective study by Gutte et al showed that V/P SPECT has higher sensitivity and specificity and less non-diagnostic findings than MDCT [10,14]. A recent study by Mahdavi et al showed that in the presence of an indeterminate CT angiography (CTA) in patients with high clinical suspicion of PE, V/P SPECT often provides a diagnosis [15].…”