Effect of JPEG compression on the diagnostic accuracy of periapical images in the detection of root fracture

DICOM file format has better radiographic image quality than other file formats: an objective study

This study aimed to assess the influence of the file format on the image quality parameters (image noise, brightness, and uniformity) of periapical radiographs acquired with different digital systems. Radiographic images of an acrylic phantom were acquired with two digital systems - Digora Toto and Express, and exported into five different file formats - TIFF, BMP, DICOM, PNG, and JPEG. Image noise, image brightness (mean of gray values), and image uniformity (standard deviation of gray values) were evaluated in all images. A two-way analysis of variance with Tukey's test as a post-hoc test was used to compare the results, considering the file formats and radiographic systems as the studied factors. A significance level of 5% was adopted for all analyses. The DICOM image file format presented lower image noise, higher brightness (higher mean gray values), and greater image uniformity (p<0.001) than the other file formats, which did not differ from each other for both digital radiography systems (p>0.05). The Express system revealed lower image noise and greater image uniformity than the Digora Toto system regardless of the image file format (p<0.001). Moreover, the Express showed higher brightness than the Digora Toto for all image file formats (p<0.001), except for the DICOM image file format, which did not significantly differ between the digital radiography systems tested (p>0.05). The DICOM image file format showed lower image noise, higher brightness, and greater image uniformity than the other file formats (TIFF, BMP, PNG, and JPEG) in both digital radiography systems tested.

Digital file format does not influence the radiographic diagnosis of vertical root fracture

OBJECTIVE

To evaluate the influence of the file format of digital periapical radiographs on the diagnosis of vertical root fracture (VRF).

STUDY DESIGN

Periapical radiographic images of 34 single-rooted teeth-19 with VRF, and 15 without VRF were acquired using two digital systems-Digora Toto, and Digora Optime, and exported into four different file formats-TIFF, BMP, PNG, and JPEG, totaling 272 radiographs. The radiographs were assessed by five examiners for the detection of VRF, using a 5-point scale (1-definitely absent; 2-probably absent; 3-uncertain; 4-probably present; 5-definitely present). Diagnostic values of area under the ROC curve, specificity, and sensitivity for the diagnosis of VRF were calculated. The results were compared by two-way Analysis of Variance with post hoc Tukey's test. The intra- and inter-examiner agreements were measured by the Kappa test. The significance level was set at 5% for all analyses.

RESULTS

The values of intra-examiner agreement varied from moderate (0.56) to almost perfect (0.81), while the values of inter-examiner agreement varied from fair (0.29) to moderate (0.60). The image file format did not influence the diagnostic values for VRF for any of the radiographic systems tested (p > 0.05). Digora Toto had significantly greater values of area under the ROC curve than Digora Optime for all file formats (p = 0.001).

CONCLUSION

The image file format of periapical radiographs does not influence the diagnosis of VRF, regardless of the digital radiography system.

Influence of the image file format of digital periapical radiographs on the diagnosis of external and internal root resorptions

OBJECTIVES

To evaluate the influence of different image file formats of digital radiographic images on the diagnosis of external (ERR) and internal root resorption (IRR).

MATERIALS AND METHODS

Thirty-four human teeth were selected. For ERR, 20 teeth were used (10 control and 10 with simulated ERR), and for IRR, 14 teeth were used (before and after IRR simulation). Digital periapical radiographs were acquired using the Digora Toto system and exported in four different image file formats: TIFF, BMP, PNG, and JPEG, totaling 192 radiographs. Five examiners evaluated the images using the JPEGView software and scored the detection of ERR or IRR on a 5-point scale. Sensitivity, specificity, accuracy, and the area under the ROC curve were obtained for the diagnosis of ERR and IRR in the different image file formats. Two-way ANOVA compared the diagnostic values between the file formats and the Kappa test assessed intra- and inter-examiner agreement. The significance level was set at 5% (α = 0.05).

RESULTS

The mean values of intra-examiner agreement were substantial (0.740) for ERR and almost perfect (0.836) for IRR and, inter-examiner was fair (0.263) and moderate (0.421), respectively. No statistically significant differences were found among the different file formats for the diagnostic values of ERR and IRR.

CONCLUSION

The file format of digital radiographs does not influence the diagnosis of ERR and IRR.

CLINICAL RELEVANCE

Digital radiographic images may be susceptible to computational factors; however, they can be stored in multiple file formats without affecting the diagnosis of dental root resorptions.

Influence of the file format and transmission app on the radiographic diagnosis of caries lesions

OBJECTIVES

This in vitro study aimed to evaluate the influence of the radiographic image file format and the transmission application (app) on the diagnosis of proximal caries lesions.

STUDY DESIGN

Twenty bitewing radiographs of 40 posterior human teeth placed in phantoms were acquired using the Digora Toto digital sensor. All images were exported as TIFF (Tagged Image File Format), BMP (Windows Bitmap), PNG (Portable Network Graphics), and JPEG (Joint Photographic Experts Group) and transmitted online via WhatsApp and Messenger. Five examiners evaluated the radiographs with no online transmission and as transmitted through the 2 apps for the presence of proximal caries lesions using a 5-point scale. The reference standard for caries lesions was established using micro-computed tomography. Two-way analysis of variance compared values of sensitivity, specificity, accuracy, and area under the receiver operating characteristic curve (α = .05). The kappa test was used to assess intra- and interexaminer agreement.

RESULTS

Sensitivity, specificity, accuracy, and area under the receiver operating characteristic curve values showed no significant differences in the diagnosis of proximal caries lesions between the different image file formats (P ≥ .773) and transmission apps (P ≥ .608). Intraexaminer agreement was substantial (κ = 0.742) and interexaminer agreement was moderate (κ = 0.475).

CONCLUSION

The digital file format and transmission app did not influence the radiographic diagnosis of proximal caries lesions.

Effect of Resolution and Bit Depth on Inferior Alveolar Canal Visualization on Exported Mandibular Cone-Beam Computed Tomography Images

PURPOSE

Cone-beam computed tomography (CBCT) is commonly requested before dental implant treatment for the anatomic assessment of the inferior alveolar canal (IAC) to prevent its neurovascular content from being traumatized. CBCT images can be saved in different types of resolutions and bit depths; these parameters may significantly affect the diagnostic accuracy of images. This study aimed to assess the effect of resolution and bit depth on IAC visualization on exported mandibular CBCT images.

MATERIALS AND METHODS

Forty-one mandibular CBCT images of differing image resolutions and voxel sizes (0.16, 0.32, and 0.48 mm) and differing bit depths (12 and 15) were exported from a software program as a single file. Two observers evaluated the cross-sectional images in terms of IAC visibility using a 3-point scale (good, moderate, and poor). Disagreements were resolved by including a third observer, and the highest agreement was recorded.

RESULTS

Study interobserver agreement was acceptable (84.2%) for IAC observation. The percentage of IAC observation was from 84.1 to 100% with the 12- and 15-bit depths, with a constant image resolution of 0.16 and 0.32 mm, respectively. A significant difference (from 19.5 to 48.8%) was noted between the 2 bit depths in the percentage of good IAC visualization with a constant resolution of 0.48 mm. Reduction in the image resolution to 0.48 mm showed a significant difference (19.5 to 100%) between the 12- and 15-bit depths in good IAC visualization.

CONCLUSIONS

Exporting the mandibular CBCT images with 0.32 mm of resolution and a 12-bit depth will produce good and moderate radiographic IAC observation with the benefit of a smaller file size.

Effects of Image Compression on Linear Measurements of Digital Panoramic Radiographs

Abstract This study aimed to evaluate the accuracy of panoramic radiographs obtained by digital system based on charge coupled device (CCD) and a phosphor storage plate (PSP) system with two different file formats, JPEG irreversible type and BMP. Linear measurements of artificial bony defects were made in dry mandibles with a digital caliper. Measures of digital panoramic radiographs were taken in ImageJ(r) software. Each measurement was performed twice by an experienced examiner. The intra-rater agreement was considered very strong (Pearson's correlation coefficient of 0.97). There was no significant difference between the linear measurements of dry mandibles, considered the gold standard, in relation to measurements obtained from digital radiographs (p=0.47). The error of these measures for the CCD was 1.04 mm (9.97%) for JPEG images and 1.03 mm (9.99%) for those with BMP format. For the PSP images, these values were 1.48 mm (14.94%) and 1.43 mm (14.43%), respectively. Although there was no statistical difference between the images with JPEG and BMP format, for both digital systems (p=1.00 for CCD and p=0.98 for PSP system), errors made on radiographs obtained by PSP system were significantly higher than those of CCD (p<0.05). The size of the files saved in JPEG was also significantly lower (p=0.005) compared with the files saved in BMP. It may be concluded that the digital radiographs, both saved in JPEG and BMP formats, are accurate, regardless the used digital system, and JPEG images are more suitable for teleradiology.

Digital DICOM in Dentistry

Similar to Medicine, digital communication, information processing, and x-ray imaging have changed the face of dentistry. The incorporation of digital systems into medical and dental practice has necessitated development of a standard that allows reliable transmission of information between the devices taking the images, devices storing the images, and devices displaying the images. This standard is termed as DICOM. The following article briefly reviews how DICOM came about, how dentistry is involved, the various elements that are part of the DICOM system, and how DICOM is currently used in dentistry.

Imaging file management to support international telepathology

BACKGROUND

Telepathology practice across international borders has become increasingly popular. Our telepathology consultation service with a laboratory in China was hampered by latency issues when viewing whole slide images.

OBJECTIVE

The aim was to explore data transfer solutions to improve the viewing experience of digital consult cases.

METHODS

Whole slide image files residing on a server in China were transferred to our data center in the USA using an open source product (Fast Data Transfer). A faster more automated commercial high speed file transfer software solution (Aspera) was also tested.

RESULTS

Transferring files with the open source product provided transfer speeds of 2-3 Mbps, but suffered from intermittent dropped connections. Employing commercial software permitted more reliable transmission of digital files with 75-100 Mbps transfer speeds.

CONCLUSIONS

Successful global telepathology requires dedicated image management. Transfer of files to local servers by employing high speed data transfer tools helped overcome network latency issues, improved the overall turn-around time of digital consultations, and enhanced the viewing experience for end-user digital consultants.