Evaluation of dose reduction and image quality in CT colonography: comparison of low-dose CT with iterative reconstruction and routine-dose CT with filtered back projection.

OBJECTIVE: To prospectively evaluate the radiation dose and image quality comparing low-dose CT colonography (CTC) reconstructed using different levels of iterative reconstruction techniques with routine-dose CTC reconstructed with filtered back projection. METHODS: Following institutional ethics clearance and informed consent procedures, 210 patients underwent screening CTC using automatic tube current modulation for dual positions. Examinations were performed in the supine position with a routine-dose protocol and in the prone position, randomly applying four different low-dose protocols. Supine images were reconstructed with filtered back projection and prone images with iterative reconstruction. Two blinded observers assessed the image quality of endoluminal images. Image noise was quantitatively assessed by region-of-interest measurements. RESULTS: The mean effective dose in the supine series was 1.88 mSv using routine-dose CTC, compared to 0.92, 0.69, 0.57, and 0.46 mSv at four different low doses in the prone series (p < 0.01). Overall image quality and noise of low-dose CTC with iterative reconstruction were significantly improved compared to routine-dose CTC using filtered back projection. The lowest dose group had image quality comparable to routine-dose images. CONCLUSIONS: Low-dose CTC with iterative reconstruction reduces the radiation dose by 48.5 to 75.1% without image quality degradation compared to routine-dose CTC with filtered back projection. KEY POINTS: • Low-dose CTC reduces radiation dose ≥ 48.5% compared to routine-dose CTC. • Iterative reconstruction improves overall CTC image quality compared with FBP. • Iterative reconstruction reduces overall CTC image noise compared with FBP. • Automated exposure control with iterative reconstruction is useful for low-dose CTC.

Colonic distention at CT colonography: randomized evaluation of both IV hyoscine butylbromide and automated carbon dioxide insufflation.

OBJECTIVE: The purpose of this article is to evaluate the efficacy of IV hyoscine butylbromide as a bowel relaxant and automated carbon dioxide insufflation in CT colonography in terms of colonic distention and perceived burden. SUBJECTS AND METHODS; Two hundred twenty-four participants were randomly allocated to one of four groups: control (no bowel relaxant and IV saline placebo before CT colonography with manual carbon dioxide insufflation), hyoscine butylbromide (IV hyoscine butylbromide before examination with manual carbon dioxide insufflation), automated (no bowel relaxant before examination with automated carbon dioxide insufflation), and combined (hyoscine butylbromide before examination with automated carbon dioxide insufflation). The degree of colonic distention on a 4-point scale, examination time, and participants' satisfaction, as measured by their responses to a questionnaire, were assessed. RESULTS: The mean distention grades of all the colonic segments and both positions were 3.22 in the control group, 3.28 in the hyoscine butylbromide group, 3.77 in the automated group, and 3.74 in the combined group. Compared with manual carbon dioxide insufflation, automated carbon dioxide insufflation significantly improved the clinical adequacy of colonic distention and shortened examination time. No statistically significant difference was seen in the clinical adequacy of distention between participants who received hyoscine butylbromide and those who did not, or in examination time. Overall, the participants' experiences were not different. CONCLUSION: Colonic distention was statistically significantly improved by automated carbon dioxide insufflation, but not by the administration of hyoscine butylbromide. The participants' tolerance was similar in each group.

Effect of listening to music and essential oil inhalation on patients undergoing screening CT colonography: a randomized controlled trial.

OBJECTIVE: To prospectively evaluate the effect of listening to music and inhaling aroma oil on patients undergoing screening computed tomography colonography. MATERIALS AND METHODS: Two hundred and twenty four participants were randomly allocated to one of the four groups including: (1) combined music and aroma, (2) music alone, (3) aroma alone, and (4)control. The visual analog scale for pain and a questionnaire were used for subjective outcomes. We also used a pre-test­post-test design to compare the differences in blood pressure and heart rate as objective outcomes. RESULTS: There were no statistical differences between the control group and other groups in the visual analog scale or changes in heart rate. Changes in blood pressure were similar. Participants reported good overall experiences. There were no differences in terms of overall satisfaction, pain rating, willingness to repeat the computed tomography colonography procedure in the future, or preference between colonoscopy and computed tomography colonography. More participants using music and/or aroma requested music and/or aroma during the next computed tomography colonography (P < 0.0001). CONCLUSION: Although audio and olfactory intervention had little effect on perceived pain or discomfort and vital signs, participants who listened to music and inhaled aroma during the computed tomography colonography preferred music and aroma during the next computed tomography colonography.