Agreement between SPECT V/Q scan and CT angiography in patients with high clinical suspicion of PE.
OBJECTIVE
To track agreement between single positron emission computed tomography (SPECT) V/Q and CT angiography in patients with high clinical suspicion of pulmonary embolism (PE). If significant agreement occurs, a case could be made for more frequent use of chest radiography followed by SPECT V/Q scanning given its lower risk profile.


BACKGROUND
Diagnosis of PE can be difficult. CT pulmonary angiography (CTA) is the preferred initial test, but may be indeterminate, is a significant source of ionizing radiation, and is contraindicated in renal insufficiency. SPECT ventilation/perfusion imaging (V/Q) is therefore preferred in certain patients.


METHODS
Two thousand nine hundred and twenty patients admitted to a tertiary care hospital in New York City were screened and 100 consecutive high-risk patients who required both CTA and V/Q for an initial indeterminate or negative imaging test despite a high pre-test probability were identified. The agreement between these tests was evaluated.


RESULTS
There was no significant agreement between CTA and V/Q when positive, negative and indeterminate results were included (K = 0.18, SE = 0.09, p = 0.051). However, in the presence of a positive finding on either test, there was substantial agreement between the two (K = 0.62, SE = 0.27, p = 0.02). In 30 cases in which CTA was indeterminate, V/Q was diagnostic 93 % of the time. In 12 cases in which V/Q was indeterminate, CTA was diagnostic 83 % of the time and negative in 100 % of those cases.


CONCLUSIONS
In the presence of an indeterminate CTA in patients with high clinical suspicion of PE, SPECT V/Q often provides a diagnosis.
Division of Pulmonary-Critical Care, Department of Medicine, Lenox Hill Hospital, 100 East 77th Street, New York, NY, 10021, USA, ramyarm@hotmail.com.
Ramyar
R
Mahdavi
Jonathan
J
Caronia
Jazeela
J
Fayyaz
Georgia
G
Panagopoulos
Klaus D
KD
Lessnau
Stephen C
SC
Scharf
Bushra
B
Mina
Charles
C
Allred
Larry
L
DiFabrizio
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000792:Angiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011655:Pulmonary Embolism / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology*; D012189:Retrospective Studies; D015899:Tomography, Emission-Computed, Single-Photon; D014057:Tomography, X-Ray Computed; D014692:Ventilation-Perfusion Ratio; D055815:Young Adult