Correlation between gray values of cone-beam computed tomograms and Hounsfield units of computed tomograms: A systematic review and meta-analysis

Abstract

Purpose The aim of this review was to systematically analyze the available literature on the correlation between the gray values (GVs) of cone-beam computed tomography (CBCT) and the Hounsfield units (HUs) of computed tomography (CT) for assessing bone mineral density. Materials and Methods A literature search was carried out in PubMed, Cochrane Library, Google Scholar, Scopus, and LILACS for studies published through September 2021. In vitro , in vivo , and animal studies that analyzed the correlations GVs of CBCT and HUs of CT were included in this review. The review was prepared according to the PRISMA checklist for systematic reviews, and the risk of bias was assessed using the Quality Assessment of Diagnostic Accuracy Studies tool. A quantitative analysis was performed using a fixed-effects model. Results The literature search identified a total of 5,955 studies, of which 14 studies were included for the qualitative analysis and 2 studies for the quantitative analysis. A positive correlation was observed between the GVs of CBCT and HUs of CT. Out of the 14 studies, 100% had low risks of bias for the domains of patient selection, index test, and reference standards, while 95% of studies had a low risk of bias for the domain of flow and timing. The fixed-effects meta-analysis performed for Pearson correlation coefficients between CBCT and CT showed a moderate positive correlation (r=0.669; 95% CI, 0.388 to 0.836; P <0.05). Conclusion The available evidence showed a positive correlation between the GVs of CBCT and HUs of CT.

Radiographic alveolar bone assessment in correlation with primary implant stability: A systematic review and meta‐analysis

“…Despite that, many studies demonstrated a high correlation between HU and GV (Aranyarachkul et al, 2005;Cassetta et al, 2014;Naitoh et al, 2009;Parsa et al, 2012;Razi et al, 2019), which shows the potential of CBCT to assess bone density. This finding was confirmed by a systematic review and meta-analysis demonstrating a positive correlation between HU and GV (Selvaraj et al, 2022). Aforementioned bone assessment is important in treatment planning to determine the proper implant selection and surgical procedures that can affect successful dental implant treatment.…”

Radiographic and histological evaluation of bone formation induced by rhBMP-2-incorporated biomimetic calcium phosphate material in clinical alveolar sockets preservation

“…Some researchers compared HU from MSCT with GV from CBCT and concluded that the GV was more reliable for detecting and analyzing hypodense structures [ 18 ]. For bone evaluations, it was reported that high-resolution CBCT could be used for imaging quantitative bone morphometry assessment [ 19 ] and suggested there is a positive correlation between the GVs and the HUs values in quantifying bone tissue [ 20 ]. Similarly, it was reported that CBCT was as accurate and reliable as MSCT in predicting bone density and assessing changes in bone density around dental implants [ 21 ].…”

A Tailored and Transdisciplinary Approach to Cochlear Implants

“…This characteristic of MSCT was utilised for case 1, where the progression of changes in the bone density could be measured over time. However, the grey values in CBCT are at most moderately correlated with Hounsfield units and are dependent, among others, on the specific brand of the scanner [78]. This might make it difficult to track changes in bone density should the only image data be CBCT.…”