The increasing impact of multidetector row computed tomography in clinical practice

Helical computed tomography scanning of the larynx and upper trachea in rabbits

Background

Computed tomography (CT) is used to evaluate the human tracheobronchial tree because of its unsurpassed ability to visualize the airway and surrounding structures. To establish an ideal animal model for studying subglottic stenosis, we assessed the size and morphology of the normal rabbit’s laryngotracheal airway by helical CT. We measured luminal dimensions at the levels of the arytenoid and cricoid cartilages and the first, third, and eighth tracheal rings. At all levels, the axial slices were used to calculate the maximum anteroposterior (AP) dimension, transverse dimension, and cross-sectional areas. We measured the tracheal length from the cricoid to the third and eighth tracheal rings on sagittal reformation. We assessed the hyoid, thyroid, cricoid, arytenoid, and tracheal rings for the presence of calcific or soft tissue densities. We also addressed the presence or absence of pre-epiglottic and paraglottic fat.

Results

The mean AP tracheal dimension ± standard deviation (SD) was 8.6 ± 0.5 mm at the arytenoid level, 8.2 ± 0.7 mm at the cricoid level, and 7.7 ± 0.2 mm at the first tracheal ring level. The transverse tracheal dimension ±SD was 5.3 ± 0.1 mm at the arytenoid level, 5.5 ± 0.5 mm at the cricoid level, and 6.1 ± 0.6 mm at the first tracheal ring level. The mean tracheal area ±SD was 35.7 ± 2.2 mm² at the arytenoid level, 35.8 ± 5.1 mm² at the cricoid level, and 39.2 ± 4.3 mm² at the first tracheal ring level. The tracheal length ±SD was 10.7 ± 2.3 mm from the cricoid to the third tracheal ring and 19.1 ± 1.14 mm to the eighth tracheal ring. There was complete calcification of the hyoid in all rabbits. Only two rabbits showed complete thyroid, arytenoid, or tracheal ring calcification. The remaining airway components were otherwise either uncalcified or partially calcified. The uvula, epiglottis, aryepiglottic fold, vallecula, piriform sinus, true/false vocal cords, and pre-epiglottic/paraglottic fat were not seen in any rabbit.

Conclusions

Helical CT investigation provides good, highly definitive anatomic details of the larynx and trachea in rabbits. Such results may be used in further evaluation of the normal airway and in cases of subglottic stenosis.

Comparison of neutral and positive enteral contrast media for MDCT enteroclysis

OBJECTIVE

To compare neutral and positive enteral contrast media for MDCT enteroclysis (MDCTE) in various small bowel diseases.

MATERIALS AND METHODS

40 patients with suspicion of small bowel diseases were divided randomly into two equal groups. In one group, water was used as neutral enteral contrast and in other group, 2% water soluble iodinated contrast was used as positive enteral contrast. All MDCTE were done on a 16-slice multidetector row CT unit. The findings of MDCTE were compared with the standards of reference.

RESULTS

There were 12 cases of abdominal tuberculosis (30%), 5 cases of bowel masses (12%), 4 cases of Crohn's disease (10%), 3 cases of small bowel adhesions (7%), 2 cases of midgut volvulus (5%), 2 cases of segmental enteritis (5%) and 12 of all cases (30%) were normal. There was no statistically significant difference between neutral and positive enteral contrast with regards to bowel distention, contrast reflux and evaluation of duodenum. Abnormal bowel wall enhancement was appreciated only with use of neutral enteral contrast (n=12). Evaluation of ileocaecal junction was possible in all 20 patients (100%) with positive enteral contrast but in only 17 patients (85%) with neutral enteral contrast. Overall sensitivity and specificity of MDCTE with use of neutral contrast medium (100 and 88% respectively) was greater for evaluation of small bowel diseases, when compared to MDCTE using positive enteral contrast medium (92.8 and 83.3% respectively).

CONCLUSIONS

Water is a good enteral contrast medium for MDCT enteroclysis examination and allows better evaluation of abnormal bowel wall enhancement. Ileocaecal junction evaluation is better with positive enteral contrast medium.

Integration of multislice computed tomography with magnetic navigation facilitates percutaneous coronary interventions without additional contrast agents

OBJECTIVES

We hypothesized that percutaneous coronary intervention (PCI) without additional contrast agents can be performed by directly integrating multislice computed tomography coronary angiography (CTCA) within the magnetic navigation system (MNS).

BACKGROUND

Increasingly, CTCA is being used in the diagnostic work-up of patients with coronary disease. Its inherent 3-dimensional information should be exploited, as it potentially offers advantages over 2-dimensional radiography in guiding invasive diagnostic and therapeutic interventions.

METHODS

CTCA-derived centerlines from 15 patients were coregistered and overlaid on real-time fluoroscopic images employing the MNS. Vessels were manually wired with a magnetically enabled guidewire assisted by variable local magnetic fields. Fractional flow reserve (FFR) determined the lesion severity, and the dimensions were quantified by intravascular ultrasound (IVUS). Locations of the IVUS catheter probe along the lesion were incorporated in software to facilitate stenting without contrast agents.

RESULTS

The average crossing and fluoroscopic times were 105.3 +/- 35.5 s and 83.4 +/- 38.6 s, respectively, with no contrast agents used in 11 of 15 patients (73.3%). Contrast agents were used in only 1 of 10 patients (10%) in whom an IVUS was performed. In 4 patients, apart from a "blinded" safety check angiogram, the entire PCI (lesion crossing, stent sizing, positioning, and deployment) was performed without additional contrast agents following the coregistration of the IVUS probe position in the MNS.

CONCLUSIONS

The integration of pre-procedural CTCA within the MNS can facilitate PCI without additional contrast agents.

Small bowel vascular disorders from arterial etiology and impaired venous drainage

Intestinal ischemia of the small bowel represents an important diagnostic question to answer in an emergency. Although some findings could be appreciated with basic imaging methods, the MDCT as a modern noninvasive imaging method could be effective in evaluating intestinal disease caused by superior mesenteric artery or vein occlusion and making a diagnosis of ischemia from low-flow states. Looking at the features of the parietal layers with knowledge of the pathologic mechanism underlying the changes from the "normality" could be helpful in making a correct, prompt, and effective diagnosis of intestinal ischemia or disease from impaired venous drainage.