Using "iDose4" iterative reconstruction algorithm in adults' chest-abdomen-pelvis CT examinations: effect on image quality in relation to patient radiation exposure.

OBJECTIVE: The aim of this study is to examine the effect of iDose4 hybrid iterative reconstruction algorithm (Philips Healthcare, Cleveland, OH) on radiation dose and image quality in chest­abdomen­pelvis (CAP) CT scanning of adult patients. METHODS: CAP CT examinations were performed on 99 patients with the use of the "old standard" protocol performing filtered back projection reconstruction algorithm (FBP protocol) and on 84 patients with the use of iDose4 protocol on a 64-multidetector CT. Patients were subdivided into three weight groups (Group 1, 41­60kg; Group 2, 61­90kg; and Group 3, .90kg). Volume CT dose index and dose length product (DLP) were recorded, while effective dose was calculated from DLP measurements. Objective image noise, signal-to-noise ratio and contrast-to-noise ratio were calculated. Two radiologists reviewed images to evaluate image quality. RESULTS: Compared with the FBP protocol, there was an overall 46.5% significant decrease in effective dose with the use of iDose4 protocol. CONCLUSION: Objective image quality was higher in iDose4 images than in FBP images. Subjective image noise, sharpness, contrast and diagnostic confidence scores tended to be better for iDose4 protocol at the decreased radiation exposure level. Artefacts were minor for both protocols. ADVANCES IN KNOWLEDGE: Our results suggest that the iterative acquisition protocol provides great potential for reducing radiation exposure and maintaining or improving image quality in CAP CT examinations.

Modification of the Kestenbaum operation for correction of nystagmic torticollis and improvement of visual acuity with the use of convergence.

In five patients with congenital nystagmus and compensatory head turn we performed a modified Kestenbaum operation intended to correct the compensatory head turn and to improve visual acuity. All patients had nystagmus without strabismus and fully developed binocular function. The nystagmus decreased but did not cease completely during the lateral gaze, and the patients adopted compensatory head turn positions to improve their visual acuity. The near acuity was better than the distance and the head turn decreased on near fixation. In such cases the original Kestenbaum procedure transfers the neutral zone to the primary position and corrects the head turn, but does not improve the visual acuity because a considerable amount of nystagmus is still present. Our aim was to perform an asymmetric Kestenbaum operation with a greater amount of surgery to the eye that turns out and a lesser amount to the eye that turns in, thus creating a postoperative divergence of the eyes. The result of compensating for this divergence (through stimulation of the fusional reserve) blocks the residual nystagmus of the neutral zone and, consequently, improves visual acuity. The results obtained from performing this modified Kestenbaum operation in five patients were very satisfactory. The compensatory head turn was corrected in all patients and remained so during the follow-up period. In four cases, the postoperative visual acuity in the neutral zone was better than before. There was no improvement in one case.