Traditional gamma cameras are preferred.

Although the new solid-state dedicated cardiac cameras provide excellent spatial and energy resolution and allow for markedly reduced SPECT acquisition times and/or injected radiopharmaceutical activity, they have some distinct disadvantages compared to traditional sodium iodide SPECT cameras. They are expensive. Attenuation correction is not available. Cardio-focused collimation, advantageous to increase depth-dependent resolution and myocardial count density, accentuates diaphragmatic attenuation and scatter from subdiaphragmatic structures. Although supplemental prone imaging is therefore routinely advised, many patients cannot tolerate it. Moreover, very large patients cannot be accommodated in the solid-state camera gantries. Since data are acquired simultaneously with an arc of solid-state detectors around the chest, no temporally dependent "rotating" projection images are obtained. Therefore, patient motion can be neither detected nor corrected. In contrast, traditional sodium iodide SPECT cameras provide rotating projection images to allow technologists and physicians to detect and correct patient motion and to accurately detect the position of soft tissue attenuators and to anticipate associated artifacts. Very large patients are easily accommodated. Low-dose x-ray attenuation correction is widely available. Also, relatively inexpensive low-count density software is provided by many vendors, allowing shorter SPECT acquisition times and reduced injected activity approaching that achievable with solid-state cameras.

First experience with microprobe transoesophageal echocardiography in non-sedated adults undergoing atrial fibrillation ablation: feasibility study and comparison with intracardiac echocardiography.

AIMS: Imaging of the left atrium (LA) is mandatory during catheter ablation of atrial fibrillation (AF) and may be achieved by echocardiography. The aim of the present study was to assess the feasibility of using a recently released transoesophageal echocardiography (TEE) microprobe (micro-TEE) in non-sedated adult patients undergoing AF ablation and to directly compare this new technique with intracardiac echocardiography (ICE). METHODS AND RESULTS: The study group consisted of 12 consecutive patients (8 males, mean age 49 ± 14 years) who underwent first radiofrequency AF ablation. All patients underwent standard TEE, computed tomography, intraprocedural micro-TEE, and ICE. The easiness of introducing the microprobe in the supine position in non-sedated patients in the electrophysiology laboratory, its tolerability, and quality of obtained images were assessed using a five-point scale. There were no problems with microprobe introduction and obtaining images for a mean of 54 ± 17 min. The microprobe was significantly better tolerated than the standard TEE probe (4.3 ± 0.5 vs. 3.4 ± 0.6 points, P < 0.01). The micro-TEE was scored as significantly better than ICE in the assessment of the LA and LA appendage (LAA) anatomy and function. Both techniques were very useful in guiding transseptal puncture, although micro-TEE images were ranked higher by an echocardiographer than by an electrophysiologist (tenting 4.8 ± 0.6 vs. 4.0 ± 0.6 points, P < 0.01), whereas ICE images were ranked equally excellent by both observers. CONCLUSION: In non-sedated patients undergoing AF ablation, the micro-TEE can be used for the assessment of the LA, LAA, and pulmonary veins anatomy as well as the guidance of transseptal puncture.