PT - JOURNAL ARTICLE AU - Michael S. Hofman AU - Jean-Mathieu Beauregard AU - Thomas W. Barber AU - Oliver C. Neels AU - Peter Eu AU - Rodney J. Hicks TI - <sup>68</sup>Ga PET/CT Ventilation–Perfusion Imaging for Pulmonary Embolism: A Pilot Study with Comparison to Conventional Scintigraphy AID - 10.2967/jnumed.111.093344 DP - 2011 Oct 01 TA - Journal of Nuclear Medicine PG - 1513--1519 VI - 52 IP - 10 4099 - http://jnm.snmjournals.org/content/52/10/1513.short 4100 - http://jnm.snmjournals.org/content/52/10/1513.full SO - J Nucl Med2011 Oct 01; 52 AB - Ventilation–perfusion (V/Q) scintigraphy is established for regional assessment of lung function in a variety of diseases, including pulmonary embolism (PE). PET/CT may further improve the accuracy and utility of V/Q imaging because of its superior technical characteristics. This pilot study assessed the feasibility of performing V/Q PET/CT and compared diagnostic utility with conventional V/Q imaging in patients with clinical suspicion of PE. Methods: Ten patients undergoing conventional V/Q imaging were prospectively recruited. PET/CT V/Q imaging was performed after inhalation of 68Ga-carbon nanoparticles (“Galligas”) and administration of 68Ga-macroaggregated albumin. Blinded to the results of the other study, SPECT/CT (n = 9) or SPECT (n = 1) images and PET/CT images were graded by a predefined scoring system for scan quality. The number of matched or unmatched defects and diagnosis were also measured and compared with a final diagnosis. Results: PET image quality was equivalent or superior to SPECT in all patients, with more homogeneous radiotracer distribution for both ventilation and perfusion studies (P &lt; 0.01). Based on conventional V/Q imaging, the diagnosis was acute PE in 2 patients and no PE in 7 patients, and the imaging results were nondiagnostic in 1 patient. The PET/CT diagnosis was concordant in 8 patients, and these studies demonstrated a similar number and distribution of matched and unmatched defects. In 1 discordant case, a patient with a SPECT/CT study that was nondiagnostic because of severe airway disease showed no PE on PET/CT. In another, the diagnosis of PE established on SPECT/CT was not reported on PET/CT 2 d later, possibly because of interval clot lysis or migration. Conclusion: This intraindividual comparative study demonstrated that V/Q PET/CT with 68Ga-labeled radiotracers can be performed in clinical practice. Compared with conventional V/Q imaging, advantages include higher-resolution, fully tomographic images with potentially better regional quantitation of lung function. The short half-life of 68Ga also enables more flexible acquisition protocols with the option of performing ventilation studies selectively on patients with abnormal perfusion. On the basis of our results, further studies are indicated to assess whether V/Q PET/CT can improve diagnostic algorithms for patients with suspected PE.