PT - JOURNAL ARTICLE AU - Seung Hur AU - Adam Bauer AU - Natalie McMillan AU - Elizabeth A. Krupinski AU - Phillip H. Kuo TI - Optimizing the Ventilation–Perfusion Lung Scan for Image Quality and Radiation Exposure AID - 10.2967/jnmt.113.128900 DP - 2014 Mar 01 TA - Journal of Nuclear Medicine Technology PG - 51--54 VI - 42 IP - 1 4099 - http://tech.snmjournals.org/content/42/1/51.short 4100 - http://tech.snmjournals.org/content/42/1/51.full SO - J. Nucl. Med. Technol.2014 Mar 01; 42 AB - Our purpose was to compare the performance of an initial ventilation–perfusion (V/Q) scan protocol with that of a data-driven modified protocol to improve diagnostic quality without increasing radiation dose to the patient. Methods: The initial V/Q scan protocol consisted of a ventilation scan after inhalation of 99mTc-diethylenetriaminepentaacetic acid (DTPA) aerosol for 5 min followed by a 99mTc-macroaggregated albumin perfusion scan. Interim analysis after 34 scans under an initial protocol included calculations of ventilation efficiency, perfusion efficiency, and perfusion-to-ventilation counting rate ratio (Q:V). Ventilation efficiency was defined as ventilation counting rate divided by ventilation dose, perfusion efficiency as perfusion counting rate divided by perfusion dose, and Q:V as perfusion counting rate divided by ventilation counting rate. From these data, the protocol was modified to improve the Q:V ratio and was applied to 60 patients. Results from the 94 scans were tabulated, and a comparison of ventilation efficiency, perfusion efficiency, and Q:V between the 2 protocols was statistically analyzed. Results: The initial protocol returned a mean ventilation efficiency of 7.8% (SD, 4.6%; range, 1.4%–19%), mean perfusion efficiency of 100% (SD, 31%; range, 39%–160%), and mean Q:V of 2.4 (SD, 1.9; range, 0.51–9.0). All 3 parameters displayed a wide range. Fifty-four percent of these cases demonstrated an unacceptable Q:V (≤2) indicating that the perfusion dose did not overwhelm the ventilation dose. To improve Q:V, options included decreasing ventilation dose, increasing perfusion dose, or performing the ventilation scan with a much higher dose after the perfusion scan. To minimize radiation, the protocol was modified to decrease the ventilation from 5 min to 2.5 min. The modified protocol yielded a mean ventilation efficiency of 5.1% (SD, 1.8; range, 2.0–11), mean perfusion efficiency of 120% (SD, 27%; range, 65%–170%), and mean Q:V of 3.6 (SD, 1.7; range, 1.2–12). Differences between protocols were statistically significant for ventilation efficiency, perfusion efficiency, and Q:V (P < 0.02). Less than 8% of cases under the modified protocol exhibited an unacceptable Q:V. Conclusion: The initial V/Q scan protocol was successfully modified to improve image quality with less radiation. By decreasing the ventilation time by half, the percentage of studies with an unacceptable Q:V decreased from 54% to 8%. This analysis may help others to optimize their V/Q protocols.