Volumetric measurement of the tongue and oral cavity with cone-beam computed tomography: A systematic review

Purpose

The goal of this systematic review was to compare the use of cone-beam computed tomography (CBCT) with that of computed tomography (CT) for volumetric evaluations of the tongue and oral cavity.

Materials and Methods

A search for articles was conducted in accordance with the Preferred Reporting Items for Systematic Review and Meta-analyses guidelines. The PubMed, Scopus, ScienceDirect, and SAGE Journals databases were searched for articles published between 2011 and 2021. Articles were screened and assessed for eligibility. Screening involved checking for duplication, reading the title and abstract, and reading the full text.

Results

The initial search retrieved 25,780 articles. Application of the eligibility criteria yielded 16 articles for qualitative analysis. Multiple uses of CBCT were identified. In several studies, researchers assessed the volumetric correlation between tongue and oral cavity volumes, as well as other parameters. Post-treatment volumetric evaluations of the oral cavity were also reported, and the reliability of CBCT was assessed. The use of CT resembled that of CBCT.

Conclusion

CBCT has been used in the evaluation of tongue and oral cavity volumes to assess correlations between those volumes and with the upper airway. It has also been used for volumetric evaluation after surgical and non-surgical procedures and to assess the relationships between tongue volume, tooth position, occlusion, and body mass index. Participants with obstructive sleep apnea and malocclusion have been evaluated, and the reliability of CBCT has been assessed. In the included studies, CT was utilized for similar purposes as CBCT, but its reliability was not assessed.

Ascending Aortic Diameter after Dissection Does Not Reflect Size before Dissection

Introduction

Current guidelines for prophylactic resection of ascending aortic aneurysms are based on post-dissection aortic diameter. However, this may not reflect the diameter prior to dissection.

Report

Pre- and post-dissection aortic diameters were compared in 34 patients with available computerised tomography scans. The median time interval between these scans was 536 days (interquartile range 354 – 1237).

Discussion

There was a statistically significant difference in diameters from the sinotubular junction to the proximal abdominal aorta, the largest was in the ascending aorta with a mean of 7.6 mm (standard deviation 4.5). This suggests that the ascending aortic diameter is a poor predictor of dissection in most patients.

•

Ascending aortic diameter expands due to acute dissection.

•

Post-dissection aortic diameters probably overestimate pre-dissection diameters.

•

Following ascending dissection, diameter expansion is not limited to aorta ascendens.

•

In this sample, estimated pre-dissection ascending aortic diameters were below 60 mm in 91% of patients and below 50 mm in 85%.

Exception Points and Body Size Contribute to Gender Disparity in Liver Transplantation

BACKGROUND & AIMS

Women are significantly less likely than men to receive a liver transplant and more likely to die on the waitlist. We investigated potential reasons for these disparities, including match run positioning and organ declines caused by small stature of female recipients.

METHODS

We analyzed data from the United Network of Organ Sharing registry of candidates placed on the waitlist from May 10, 2007, through June 17, 2013. Primary outcomes included ranked in first position on a match run, having an organ declined while in first position, declining an organ while in first position because of size mismatch between donor and recipient (body surface area discordance), and death or becoming too sick for liver transplantation.

RESULTS

Among 64,995 patients on the waitlist for liver transplantation, 23.1% of men and 15.6% of women received exception points (P < .001). Women listed without exception points were less likely than men to be ranked first (odds ratio [OR], 0.93; 95% CI, 0.88-0.99). Women who achieved first position were more likely to decline an organ than men (OR, 1.15; 95% CI, 1.06-1.26); this difference was reduced after we accounted for recipient body surface area (OR, 1.08; 95% CI, 0.98-1.19). Women with a single organ decline were more likely than men with a single organ decline to die or become too sick for transplantation (OR, 1.26; 95% CI, 1.12-1.41). The difference was reduced after we accounted for exception points (OR, 1.16; 95% CI, 1.12-1.21) and recipient body surface area (OR, 1.01; 95% CI, 0.96-1.06).

CONCLUSIONS

In an analysis of data from the United Network of Organ Sharing registry, we found that women when compared with men on the waitlist for liver transplantation are disadvantaged by an imbalance in exception point allocation and organ declines because of small stature.

Normal Mastoid Air Cell System Geometry: Has Surface Area Been Overestimated?

OBJECTIVES

The aim of this study was to emphasize the necessity of a standard in segmentation threshold and algorithm for measuring volume and surface area of mastoid air cell system (MACS).

METHODS

First, we obtained axial computed tomography scans of 54 normal temporal bones from 27 subjects. Then, we manipulated Hounsfield units (HU) image data in DICOM (digital imaging and communications in medicine) files directly using our program. The volume and surface area of MACS were computed and compared at segmentation thresholds (HU) from -700 to 0 at intervals of 50 using 2 algorithms; square pixel based (SP) algorithm and marching square (MS) algorithm.

RESULTS

No significant difference was found between the volumes computed by SP and MS algorithms at each segmentation threshold. The surface area computed by SP algorithm, however, was significantly larger than that by MS algorithm. We could minimize this significant difference through a modification of the SP algorithm. As the lower HU threshold value was set, the smaller volume was measured. The surface area showed a plateau at a threshold of approximately -200 HU. The segmentation threshold had greater influence on the measured volume of MACS than the algorithm did.

CONCLUSION

A standard method for measuring volume and surface area of MACS is thought to be necessary. We suggest that the MS algorithm and -200 HU of the threshold could be a standard in the measurement of volume and surface area of MACS.