Eleven lesions of the brain were analyzed and compared; they had absorption coefficients uniformly at the cerebrospinal fluid (CSF) level following contrast enhancement, and ranged from benign to malignant and solid to cystic. Grossly solid tumors may have absorption coefficients on the CT scan equal to CSF even after contrast enhancement. Absorption coefficients are misleading as histological indicators and in diagnosis; it is impossible to separate cystic from non-cystic, benign from malignant, and neoplastic from non-neoplastic lesions by absorption coefficients alone.

Background and objectives The use of nonfluoroscopic three‐dimensional electroanatomic mapping (3DM) systems reduces radiation exposure during ablation procedures. In this study, we sought to determine the value of 3DM during routine device implant procedures. Methods Seventy nonselected patients underwent implantation of a single chamber, dual chamber, or biventricular device guided by Ensite (Abbott Laboratories) to limit fluoroscopy use and compared with 70 consecutive patients, who underwent matching procedures with standard fluoroscopy use (FL) in the period immediately preceding the use of 3DM. The venous anatomy, right atrium, and ventricle and coronary sinus were mapped with 0.035 inch J‐wire, quadripolar catheter, and/or angioplasty wire. The leads were advanced under real‐time visualization in Ensite. Results 3DM reduced both fluoroscopy time and dose. Median fluoroscopy time for FL vs 3DM was 5.5 minutes (interquartile range [IQR]: 3.8‐8.1) vs 0.9 minutes (IQR: 0.6‐1.9) (P < .001) for single chamber devices, 6.3 minutes (IQR: 5.1‐7.9) vs 3.3 minutes (IQR: 1.9‐4) (P < .001) for dual‐chamber devices, and 28.6 minutes (IQR: 19.6‐36.2) to 14.7 minutes (IQR: 10.4‐22.3) (P = .009) for biventricular devices, respectively. The median air kerma for FL vs 3DM was 15.4 mGy (IQR: 8.1‐30.2) vs 4 mGy (IQR: 1.8‐8) (P < .001) for single chamber devices, 16 mGy (IQR: 12‐18.5) to 9.4 mGy (IQR: 7.5‐11.3) (P = .001) for dual‐chamber devices, and 324 mGy (IQR: 143‐668.7) to 115 mGy (IQR:77‐204) (P = .014) for biventricular devices, respectively. There were no procedural complications. At 3‐month follow‐up, there was no difference in voltage threshold measurements between the groups. Conclusion The use of 3DM leads to significantly reduced fluoroscopy time and fluoroscopy dose during routine device implantation.

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