MDCT diagnosis of appendicitis using only coronal reformations

CT diagnosis of appendicitis in children: comparison of orthogonal planes and assessment of contrast opacification of the appendix

OBJECTIVE

The aim of this study was to determine which plane is best for identification of the appendix and to assess if opacification of the appendix impacts visualization.

METHODS

Retrospective review of 218 computed tomography examinations performed for suspected appendicitis was conducted by 2 pediatric radiologists evaluating conspicuity of the appendix depending on orthogonal plane and enteric contrast.

RESULTS

Of the 180 cases in which the appendix was visualized, 154 were performed with multiplanar reformations. The best plane for identification of the appendix was coronal in 96, axial in 41, and sagittal in 17. Of the 218 computed tomography examinations, 169 had enteric contrast. The appendix was identified in 180 cases and completely opacified in 62, partially opacified in 26, without opacification in 59, and air filled in 33. Of the 38 cases in which the appendix was not identified, 29 had enteric contrast administration.In 131 of the 218 cases, the appendix was normal, and 58% demonstrated partial or complete opacification of the appendix. In 35 of the 218 cases, appendicitis was found, and there was predominantly no opacification or at most partial opacification of the appendix.

CONCLUSIONS

The coronal plane is best to identify the appendix. No enteric contrast is required to visualize appendicitis.

Visual search in abdominopelvic CT interpretation: accuracy and time efficiency between coronal MPR and axial images

RATIONALE AND OBJECTIVES

The objective of this study was to compare reader accuracy and time efficiency between coronal reformats of abdominopelvic computed tomography (CT) and axial images, by means of a visual search task.

MATERIALS AND METHODS

In this experimental crossover study, a novel visual search task, containing targets placed on actual CT images, was constructed to assess reader performance on both planes. Six trials were shown to participants in each plane, at a fixed time of 0.5 seconds per slice. The task was presented to 43 junior doctors. On each trial, participants were assessed for accuracy and confidence in finding the target on a five-point scale. Statistical analysis was performed using the Wilcoxon signed rank test, and Fleiss kappa.

RESULTS

Coronal images took 40% less time to view overall. No significant difference was found in reader accuracy or reader confidence between the two planes. Interrater agreement was observed as fair, across a very large number of raters (43).

CONCLUSIONS

Target identification in the coronal plane is extremely similar to the axial plane on abdominopelvic CT in this study and offers a substantial time benefit. A perceptual limit to visual processing of CT images may contribute to this similarity. Greater use of coronal reformats in day-to-day practice could substantially improve radiologist workflow.

Influence of multiplanar reformations on low-contrast performance in thin-collimated multidetector computed tomography

OBJECTIVES

: To analyze the influence of multiplanar reformations of thin-collimated multidetector computed tomography datasets on low-contrast performance.

MATERIALS AND METHODS

: A low-contrast phantom simulating focal hypodense lesions (-20 HU object contrast) was scanned on a 64-slice spiral CT scanner at 4 different dose levels (25 mAs, 50 mAs, 100 mAs, 200 mAs, and no dose modulation). Other scanner parameters were as follows: tube voltage = 120 kVp, rotation time = 0.8 s, reconstructed slice thickness = 0.625 mm, reconstruction interval = 0.5 mm, reconstruction kernel = standard. Coronal reformations were created using the open-source software OsiriX. A sliding-thin-slab (STS) averaging algorithm was applied to each axial and each reformatted dataset with an increasing slab thickness from 1 to 20 slices. The low-contrast performance of all datasets was calculated semiautomatically using a reader-independent, statistical approach and is expressed as the visibility index. The results were analyzed for differences between the coronal reformations and the original axial datasets. In addition, the statistical approach used herein was validated against a reader study.

RESULTS

: The visibility index of the coronal reformatted datasets over all lesion sizes was inferior when compared with the original axial datasets and reached 75.4% (±11.7%), 79.9% (±16.3%), 79.4% (±5.5%), and 93.7% (±14.6%) for dose levels of 25, 50, 100, and 200 mAs, respectively. The overall mean low-contrast performance was 82.1% of the axial dataset (P < 0.05, except for 200 mAs). The deterioration of low-contrast performance was inversely correlated with lesion size (R = 0.91). The use of the STS averaging algorithm significantly improved image quality for all datasets (112.6%-180.2%) with the beneficial effect being stronger for the coronal reformations. There was no statistically significant difference in the evaluation of low-contrast performance between the statistical approach and the ready study.

CONCLUSION

: Coronal reformations of thin-collimated multidetector computed tomography datasets show a significant reduction of low-contrast performance when compared with the original axial dataset, especially in high noise data. The use of an STS averaging algorithm had a significant benefit for both, coronal and axial orientations. The effect was more pronounced with coronal reformations and should be routinely applied to improve image quality.

Are multiplanar reconstructions necessary in routine body computed tomography practice?: what is the published evidence?

OBJECTIVE

During computed tomography interpretation, some anatomical regions are optimally displayed in planes other than axial. The purpose of this review was to define best interpretative practice, by demonstrating through literature review and case demonstration the computed tomography applications that should routinely include multiplanar viewing of the volume.

CONCLUSIONS

Owing to multidetector-row computed tomography technology, multiplanar reconstructions not only have become realistic and reliable but also, in some clinical settings, have been shown to improve diagnostic accuracy and interpretation speed.

Identification of the normal appendix in healthy adults by 64-slice MDCT: the value of adding coronal reformation images

The aim of this study was to assess retrospectively the value of adding coronal reformation images to the identification of the normal appendix using 64-slice multidetector CT (MDCT). 200 consecutive healthy adults with no history of abdominal surgery underwent abdominal CT using 64-slice MDCT without oral contrast administration and were enrolled in the study. Two gastrointestinal radiologists first interpreted the axial images only; after a 2-week interval, they then interpreted both the axial and the coronal images while blinded to the first interpretation. The identification of the normal appendix was interpreted using a four-point scale: 1, not identified; 2, identified with low confidence; 3, probably identified; 4, definitely identified. Agreement between the readers was determined with the use of weighted kappa statistics. Differences in confidence ratings for identification of the appendix were determined with the Wilcoxon signed rank test. The agreement between the readers was higher when both axial and coronal images were reviewed (kappa = 0.85) than when only the axial scans images were reviewed (kappa = 0.43). The mean confidence scores for the identification of the normal appendix by the two readers were significantly higher when both the axial and coronal images were reviewed (mean, 3.81+/-0.498 and 3.83+/-0.485 for the two readers, respectively) than when only the axial images were reviewed (mean, 3.27+/-0.819 and 3.47+/-0.856, respectively) (all p<0.01). Therefore, adding coronal reformation images to 64-slice MDCT significantly improves inter-reader agreement and confidence in the identification of the normal appendix.