The effect of varying low-dose protocols on perceived image quality in multidetector CT in a rabbit model of acute appendicitis.

The aim of this study was to evaluate the value of multidetector CT (MD-CT) with low-dose protocols in the diagnosis of acute appendicitis in a rabbit model. Ten New Zealand white rabbits underwent ligation of the appendix. MD-CT (Siemens Somatom Plus 4 Volume Zoom) was performed using three low-dose protocols: 80 kV/70 mAs; 80 kV/50 mAs; and 80 kV/20 mAs. Axial and coronal reformations were performed. Three experienced radiologists evaluated the images using a four-grade score: (1) excellent; (2) good; (3) moderate; and (4) not sufficient. Diagnosis was confirmed histopathologically. The overall score for the 80 kV/70 mAs was 1, for the 80 kV/50 mAs protocol 1.3, and the 80 kV/20 mAs protocol reached an overall score of 2. The coronal reformations reached with 1.1 (80 kV/70 mAs), 1.2 (80 kV/50 mAs), and 1.4 (80 kV/20 mAs) had a slightly better median score than the axial reconstructions. In cases of inconclusive ultrasound and clinical presentation, the use of MD-CT can be considered when evaluating children for suspected appendicitis.

Three-dimensional volume rendering of multidetector-row CT data: applicable for emergency radiology.

Multidetector-row computed tomography (MD-CT) not only creates new opportunities but also challenges for medical imaging. Isotropic imaging allows in-depth views into anatomy and disease but the concomitant dramatic increase of image data requires new approaches to visualize, analyze and store CT data. The common diagnostic reviewing process slice by slice becomes more and more time consuming as the number of slice increases, while on the other hand CT volume data sets could be used for three-dimensional visualization. These techniques allow for comprehensive interpretation of extent of fracture, amount of dislocation and fragmentation in a three-dimensional highly detailed setting. Further more, using minimal invasive techniques like CT angiography, new opportunities for fast emergency room patient's work up arise. But the most common application is still trauma of the musculoskeletal system as well as face and head. The following is a brief review of recent literature on volume rendering technique and some exemplary applications for the emergency room.

First experiences with multidetector CT in traumatized children.

INTRODUCTION: The aim of this study was to describe and discuss first experiences with multidetector CT (MDCT) in the assessment of traumatized children. MATERIAL AND METHODS: Since the implementation of a MDCT scanner in April 2002, 85 children (31 girls, 54 boys with a mean age of 9.2 years) consecutively underwent MDCT (Siemens, Erlangen, Germany) with different protocols depending on age, weight, trauma mechanism and clinical presentation. In all patients in whom pathology was suspected, multiplanar reformations (MPR) in coronal and or sagittal orientation was performed. Examinations were evaluated by two radiologists retrospectively and in consensus. RESULTS: In 55 (65%) children, a MDCT solely of the head was performed, in 46 there was no pathology found. In six (7%), head and facial bones were scanned. Head and abdomen was examined in two (2%), in two (2%) the abdomen only and in one (1%) the pelvis solely. Scans of the spine were obtained in seven (8%) children. A thorax and abdomen examination only was obtained in one (1%) child each. In 11 (13%) children, a polytrauma protocol was performed. In all patients, the time of examination did not exceed 17 min, including setup time. All children survived at the writing of this report. CONCLUSION: MDCT was promising in the management of traumatized children and seems to shorten the necessary time to reach diagnosis and to initiate life-saving treatment.

Four-channel multidetector CT in facial fractures: do we need 2 x 0.5 mm collimation?

OBJECTIVE: Our aim was to optimize acquisition protocols and multiplanar reformation algorithms for the evaluation of facial fractures using multidetector CT (MDCT) and to determine whether 2 x 0.5 mm collimation is necessary. MATERIALS AND METHODS: A cadaveric head with artificial blunt facial trauma was examined using a four-channel MDCT scanner. The influence of acquisition parameters (collimation, 2 x 0.5 mm, 4 x 1 mm, 4 x 2.5 mm; tube current, 120 mAs, 90 mAs, 60 mAs), image reconstruction algorithms (standard vs ultra-high-resolution modes; reconstructed slice thicknesses, 0.5 mm, 1 mm, 3 mm; increment, 0.3 mm, 0.6 mm, 1.5 mm), and reformation algorithms (slice thicknesses, 0.5 mm, 1 mm, 3 mm; overlap, 0.5 mm, 1 mm, 3 mm) on detectability of facial fractures in multiplanar reformations with MDCT was analyzed. RESULTS: Fracture detection was significantly higher with thin multiplanar reformations (0.5 and 0.5 mm, 1 and 0.5 mm, and 1 and 1 mm) (p < or = 0.014) acquired with 2 x 0.5 mm collimation (p < or = 0.046) in ultra-high-resolution mode (p < 0.0005) with 120 mAs (p < or = 0.025). Interobserver variability showed very good agreement (kappa > or = 0.942). Non-ultra-high-resolution mode, lower milliampere-seconds, and thick multiplanar reformations (3 and 0.5 mm, 3 and 1 mm, and 3 and 0.5 mm) showed significantly decreased fracture detectability. CONCLUSION: Although thin multiplanar reformations obtained from thin collimation (2 x 0.5 mm) are statistically superior for the detection of subtle fractures, 4 x 1 mm collimation is sufficient for routine diagnostic evaluation. Ultra-high-resolution mode with 120 mAs is mandatory for detection of clinically relevant fractures.