Oxygen-enhanced MRI, thin-section MDCT, and perfusion SPECT/CT: Comparison of clinical implications to patient care for lung volume reduction surgery

OBJECTIVE. The purpose of our study was to prospectively and directly compare capability of O₂-enhanced MRI, MDCT, and perfusion SPECT/CT to clinical outcome measurements in candidates for lung volume reduction surgery (LVRS). SUBJECTS AND METHODS. Twenty-five consecutive candidates for LVRS (20 men and five women; age range, 45-76 years) underwent MDCT, O ₂-enhanced MRI, and perfusion SPECT/CT before and after LVRS. Clinical outcomes for each candidate were evaluated in terms of differences between pre- and postoperative percentage forced expiratory volume in 1 second (%FEV₁), Pao₂, and 6-minute walking distance. Quantitatively assessed upper/lower lung ratios on O₂-enhanced MRI, MDCT, and SPECT/CT were calculated from regional relative enhancement ratios, functional lung volumes, and radioisotope uptakes between upper and lower lungs. Qualitatively assessed upper/lower lung ratios on O₂-enhanced MRI, MDCT, and SPECT/CT were estimated using visual scoring systems. To evaluate the correlation for individual upper/lower lung ratios and clinical outcomes, all upper/lower lung ratios were correlated with clinical outcomes. Improvements in mean relative enhancement ratio were directly correlated with clinical outcomes to assess the capability of O₂-enhanced MRI to assess therapeutic effect. RESULTS. All quantitatively (-0.63 ≤ r ≤ -0.47, p < 0.05) and qualitatively (0.41 ≤ r ≤ 0.57, p < 0.05) assessed upper/lower lung ratios showed moderate and statistically significant correlation with clinical outcomes, and improvement in mean relative enhancement ratio showed moderate or good correlation, both statistically significant (-0.44 ≤ r ≤ 0.71, p < 0.05). CONCLUSION. O₂-enhanced MRI shows potential for more accurate evaluation of postoperative clinical outcome for LVRS candidates than SPECT/CT and can be considered at least as reliable as MDCT.