Feasibility of identifying viable myocardium in rest and stress magnetic resonance imaging (MRI) was evaluated using 3 hr occlusion and 30 min reperfusion model of left anterior descending (LAD) coronary artery in 12 felines. At rest MRI, viable myocardium confirmed by 2,3,5-triphenyl tetrazolium chloride (TTC)- staining showed rapid signal intensity (SI) rise followed by gradual decline not significantly different from normal myocardium that the two hyperperfused regions were distinguishable only from the hypoperfused nonviable myocardium. At stress MRI, hyperemia induced perfusion change was most pronounced in normal myocardium with earlier and greater peak enhancement followed by brisk 'washout' phase while minimally augmented enhancement in viable myocardium was still in 'washin' phase. From these findings, it was concluded that viable myocardium is identified in rest and stress MRI as redistributing hypo- perfusion compared to persistent hyper-perfusion of the normal myocardium and the persistent hypo-perfusion of the nonviable myocardium.
Animal ; Cats ; Heart/*radiography ; Hyperemia/*radiography ; Magnetic Resonance Imaging ; Myocardial Infarction/*radiography ; Myocardial Reperfusion Injury/*radiography ; Stress

PURPOSE: Traditionally, three-dimensional conformal radiation therapy (3D-CRT) is used for neoadjuvant chemoradiation in locally advanced rectal cancer. Intensity-modulated radiation therapy (IMRT) was later developed for more conformal dose distribution, with the potential for reduced toxicity across many disease sites. We sought to use the National Cancer Database (NCDB) to examine trends and predictors for IMRT use in rectal cancer. MATERIALS AND METHODS: We queried the NCDB from 2004 to 2015 for patients with rectal adenocarcinoma treated with neoadjuvant concurrent chemoradiation to standard doses followed by surgical resection. Odds ratios were used to determine predictors of IMRT use. Univariable and multivariable Cox regressions were used to determine potential predictors of overall survival (OS). Propensity matching was used to account for any indication bias. RESULTS: Among 21,490 eligible patients, 3,131 were treated with IMRT. IMRT use increased from 1% in 2004 to 22% in 2014. Predictors for IMRT use included increased N stage, higher comorbidity score, more recent year, treatment at an academic facility, increased income, and higher educational level. On propensity-adjusted, multivariable analysis, male gender, increased distance to facility, higher comorbidity score, IMRT technique, government insurance, African-American race, and non-metro location were predictive of worse OS. Of note, the complete response rate at time of surgery was 28% with non-IMRT and 21% with IMRT. CONCLUSION: IMRT use has steadily increased in the treatment of rectal cancer, but still remains only a fraction of overall treatment technique, more often reserved for higher disease burden.
Adenocarcinoma ; Bias (Epidemiology) ; Comorbidity ; Continental Population Groups ; Humans ; Insurance ; Male ; Odds Ratio ; Radiotherapy ; Radiotherapy, Intensity-Modulated ; Rectal Neoplasms