CT-Based Hounsfield Units for Pre-donation Liver Steatosis Assessment: Enhancing Transplant Outcomes and Efficiency.

Steatotic liver grafts are associated with increased post-transplant complications and graft failure. The field of transplantation faces a challenge in the absence of a reliable pre-donation protocol for quantitatively assessing steatosis in cadaveric liver grafts. Current pre-donation evaluation protocols often involve non-contrast computed tomography (CT) scans of the chest and/or abdomen as an initial step in organ donation assessment. These routine scans have the potential to identify and quantify hepatic fat content when more than 20% of the liver parenchyma is affected. By incorporating both abdominal and thoracic CT scans during the donor workup, an assessment of the quality of the liver and spleen can be achieved. Our study is based on the hypothesis that a precise pre-donation evaluation utilizing Hounsfield units (HU) derived from CT images of the liver and spleen can provide transplant programs with crucial data regarding the extent of steatosis. This approach is envisioned as a significant advancement that could potentially eliminate the need for preoperative liver biopsies by offering essential information to streamline the evaluation process.

Age estimation using postmortem computed tomography-based Hounsfield unit values of the palate and mandibular condyle and the Eichner classification.

Age estimation is important in forensic investigations of unidentified human remains. This study assessed the correlation between age and Hounsfield unit (HU) values of the palate and mandibular condyle based on postmortem computed tomography (CT) and analyzed the influence of occlusal support in developing an age estimation method for Japanese individuals, including older adults. The sample consisted of a training dataset (357 cadavers) and a validation dataset (300 cadavers) that underwent postmortem CT. Three measurements were selected: the respective HU values of the palate and mandibular condyle and the Eichner classification. The correlation coefficients between age and HU values were also evaluated. Multiple stepwise regression analysis was performed to evaluate the significance of four parameters (sex, respective HU values of the palate and mandibular condyle, and the Eichner classification) for age estimation and to determine the best age estimation formula. In the validation tests, inaccuracy and bias were calculated for the groups aged ≥65 or <65 years. Significant correlations between age and HU values of the palate and mandibular condyle were observed, regardless of sex. In multiple stepwise regression analysis, all variables except sex were significantly correlated with age. The age estimation formula from the regression analysis was useful, and the validation test exhibited high accuracy, especially in older adults. The HU values of the palate and mandibular condyle and the Eichner classification are useful for age estimation in Japanese individuals.

Computed Tomography-Based Coronary Artery Calcium Score Calculation at a Reduced Tube Voltage Utilizing Iterative Reconstruction and Threshold Modification Techniques: A Feasibility Study.

BACKGROUND: The coronary artery calcium score (CACS) indicates cardiovascular health. A concern in this regard is the ionizing radiation from computed tomography (CT). Recent studies have tried to introduce low-dose CT techniques to assess CACS. We aimed to investigate the accuracy of iterative reconstruction (IR) and threshold modification while applying low tube voltage in coronary artery calcium imaging. METHODS: The study population consisted of 107 patients. Each subject underwent an electrocardiogram-gated CT twice, once with a standard voltage of 120 kVp and then a reduced voltage of 80 kVp. The standard filtered back projection (FBP) reconstruction was applied in both voltages. Considering Hounsfield unit (HU) thresholds other than 130 (150, 170, and 190), CACS was calculated using the FBP-reconstructed 80 kVp images. Moreover, the 80 kVp images were reconstructed utilizing IR at different strength levels. CACS was measured in each set of images. The intraclass correlation coefficient (ICC) was used to compare the CACSs. RESULTS: A 64% reduction in the effective dose was observed in the 80 kVp protocol compared to the 120 kVp protocol. Excellent agreement existed between CACS at high-level (strength level = 5) IR in low-kVp images and the standard CACS protocol in scores ≥ 11 (ICC > 0.9 and p < 0.05). Increasing the threshold density to 190 HU in FBP-reconstructed low-kVp images yielded excellent agreement with the standard protocol in scores ≥ 11 (ICC > 0.9 and p < 0.05) and good agreement in score zero (ICC = 0.84 and p = 0.02). CONCLUSIONS: The modification of the density threshold and IR provides an accurate calculation of CACS in low-voltage CT with the potential to decrease patient radiation exposure.

Comparing Dose Calculation Algorithms for Heterogeneous Media: Analytical Anisotropic Algorithm Versus Acuros XB (Dm/Dw) With Continuous CT Value Variation.

BACKGROUND: To compare the doses calculated by the analytical anisotropic algorithm (AAA) and two dose reporting modes of Acuros XB (AXB(Dm) and AXB(Dw)) with varied CT values on the Eclipse (Varian Medical Systems, Palo Alto, CA). MATERIALS AND METHODS: Virtual phantoms with a central layer of heterogeneous material (thickness = 2 or 5 cm) were created with Eclipse. Using single or opposed fields, the field sizes were 5 x 5 cm2 or 10 x 10 cm2. The photon energies were 6 or 10 MV, and the source-to-target distance was 100 cm. The relative doses at the center of the heterogeneous material layer were evaluated with varied CT values, from -1000 to 3000 HU. Values were normalized with the dose at 0 HU (100%) for comparative analysis. RESULTS: The results obtained from continuous data for a single field, 6 MV, 5 x 5 cm2, and the heterogeneous material 5 cm, where the differences between algorithms were most pronounced, were as follows. In the low-density region (-1000 HU and -800 HU), the dose differences for AXB with reference to AAA were, respectively, -54.5% and +4.6% (AXB(Dm)) and -47.0% and +3.5% (AXB(Dw)), and in the high-density regions (1000 HU and 3000 HU) were -5.7% and -8.8% (AXB(Dm)) and +7.4% and +3.5% (AXB(Dw)), respectively. Consequently, dose differences at arbitrary CT values could be obtained. CONCLUSION: Dose differences between these algorithms were clarified for heterogeneous materials. The risk of dose reduction or escalation in clinical use was clearly visible between CT values from -1000 to 3000 HU.

Hounsfield unit as a predictor of symptomatic vasospasm and hydrocephalus in good-grade subarachnoid hemorrhage treated with endovascular coiling.

Background: Patients with good-grade subarachnoid hemorrhage (SAH) often expect favorable outcomes; however, several patients may experience secondary neurological deterioration. Hydrocephalus and vasospasm are significant complications affecting SAH prognosis. We aimed to evaluate the relationship between the incidence of symptomatic vasospasm or hydrocephalus and the Hounsfield unit (HU) value of the subarachnoid space on brain computed tomography (CT) in patients with good-grade SAH treated with endovascular coiling. Methods: We conducted a retrospective analysis of consecutive initially good-grade pure SAH patients (Hunt-Hess grade I or II, modified Fisher scale I or III) with ruptured anterior circulation aneurysms treated with endovascular coiling in a single tertiary neurosurgical center between January 2010 and December 2019. The HU value within each cisterns of enrolled patients was measured, and after setting an appropriate cutoff value, it was investigated whether it could be a predictor of the occurrence of vasospasm and hydrocephalus. Results: The study included 108 eligible patients (34 males, mean age 60.88±12.26 years): 26 (24.1%) showed symptomatic vasospasm and 31 (28.7%) developed hydrocephalus. Patients with symptomatic vasospasm had a greater proportion of those with Hunt-Hess grade II (77% vs. 51%, P=0.021) and modified Fisher scale III scores (58% vs. 22%, P=0.001). The hydrocephalus group presented an older mean age (65.90 vs. 58.86 years, P=0.006) and a greater proportion of Hunt-Hess grade II (74% vs. 51%, P=0.025) and modified Fisher scale III cases (45% vs. 25%, P=0.037). The mean HU values of the Sylvian cistern (53.23 vs. 43.99, P<0.001) and basal cisterns (47.04 vs. 40.18, P=0.003) were higher in the vasospasm group. In the hydrocephalus group, only the basal cistern HU value was significantly higher (45.60 vs. 40.32, P=0.016). The area under the receiver operating characteristic (ROC) curve to determine the best cut-off HU value for the prediction of patients with symptomatic vasospasm revealed a Sylvian cistern HU value of 50.375 (sensitivity: 0.692, specificity: 0.683) and basal cistern HU value of 44.875 (sensitivity: 0.615, specificity: 0.659). Multivariable logistic analysis showed that age >70 years and Sylvian cistern HU value were independent predictors of any neurological complication at 1 year. Conclusions: The HU value of the subarachnoid space on brain CT can predict vasospasm, hydrocephalus, and long-term prognosis in good-grade SAH patients.

Correlation between CT - derived bone density and optimal bone densities acquired from CBCT scans.

It is of interest to explore the correlation between preoperative bone density, assessed via CBCTT, and primary stability of dental implants, assessed by torque ratchet. A total of 100 patients who had implant placed were taken a sample for this retrospective study. The Hounsfield units (HU) derived preoperative bone densities at implant sites that were acquired with the help of the CBCT and the primary stability was achieved during the day of surgery. Both were compared to optimum bone densities. Statistical correlation was done between the HU and Bone density. Data suggests that evaluating HU values, along with other parameters, before performing implant surgery could lead to better primary implant stability.

Evaluation of bone density and skeletal muscle mass after sleeve gastrectomy using computed tomography method.

Introduction: Sleeve gastrectomy is the most common surgical procedure to reduce weight and treat metabolic complications in patients with moderate-to-severe obesity; however, it affects the musculoskeletal system. Dual-energy X-ray absorptiometry (DXA), which is commonly used to measure bone mineral density (BMD), may be affected by excess fat tissue around the bones, interrupting BMD measurement. Due to the strong correlation between DXA and the Hounsfield units (HU) obtained from computed tomography (CT) scans, BMD assessment using clinical abdominal CT scans has been useful. To date, there has been no report of detailed CT evaluation in patients with severe obesity after sleeve gastrectomy. Objective: This study investigated the effect of sleeve gastrectomy in severely obese patients on bone and psoas muscle density, and cross-sectional area using retrospective clinical CT scans. Methods: This was a retrospective observational study that included 86 patients (35 males and 51 females) who underwent sleeve gastrectomy between March 2012 and May 2019. Patients' clinical data (age at the time of surgery, sex, body weight, body mass index (BMI), comorbidities, and preoperative and postoperative blood test results, HU of the lumbar spine and psoas muscle and psoas muscle mass index (PMI)) were evaluated. Results: The mean age at the time of surgery was 43 years, and the body weight and BMI significantly reduced (p < 0.01) after surgery. The mean hemoglobin A1c level showed significant improvement in males and females. Serum calcium and phosphorus levels remained unchanged before and after surgery. In CT analysis, HU of the lumbar spine and psoas muscle showed no significant decrease, but PMI showed a significant decrease (p < 0.01). Conclusions: Sleeve gastrectomy could dramatically improve anthropometric measures without causing changes in serum calcium and phosphorus levels. Preoperative and postoperative abdominal CT revealed no significant difference in the bone and psoas muscle density, and the psoas muscle mass was significantly decreased after sleeve gastrectomy.

Evaluation of Dose Calculation Based on Cone-Beam CT Using Different Measuring Correction Methods for Head and Neck Cancer Patients.

Purpose: To investigate and compare 2 cone-beam computed tomography (CBCT) correction methods for CBCT-based dose calculation. Materials and Methods: Routine CBCT image sets of 12 head and neck cancer patients who received volumetric modulated arc therapy (VMAT) treatment were retrospectively analyzed. The CBCT images obtained using an on-board imager (OBI) at the first treatment fraction were firstly deformable registered and padded with the kVCT images to provide enough anatomical information about the tissues for dose calculation. Then, 2 CBCT correction methods were developed and applied to correct CBCT Hounsfield unit (HU) values. One method (HD method) is based on protocol-specific CBCT HU to physical density (HD) curve, and the other method (HM method) is based on histogram matching (HM) of HU value. The corrected CBCT images (CBCTHD and CBCTHM for HD and HM methods) were imported into the original planning system for dose calculation based on the HD curve of kVCT (the planning CT). The dose computation result was analyzed and discussed to compare these 2 CBCT-correction methods. Results: Dosimetric parameters, such as the Dmean, Dmax and D5% of the target volume in CBCT plan doses, were higher than those in the kVCT plan doses; however, the deviations were less than 2%. The D2%, in parallel organs such as the parotid glands, the deviations from the CBCTHM plan dose were less than those of the CBCTHD plan dose. The differences were statistically significant (P < .05). Meanwhile, the V30 value based on the HM method was better than that based on the HD method in the oral cavity region (P = .016). In addition, we also compared the γ passing rates of kVCT plan doses with the 2 CBCT plan doses, and negligible differences were found. Conclusion: The HM method was more suitable for head and neck cancer patients than the HD one. Furthermore, with the CBCTHM-based method, the dose calculation result better matches the kVCT-based dose calculation.

Surgical Management of Charcot Spinal Arthropathy in the Face of Possible Infection.

BACKGROUND: The design is a retrospective cohort study. Charcot spinal arthropathy (CSA) is a rare and poorly understood progressive destructive spine condition that usually affects patients with preexisting spinal cord injury. The complexity of this condition, especially when additionally burdened by superimposed infection in the CSA zone, can potentially lead to suboptimal management such as protracted antibiotic therapy, predisposition to hardware failure, and pseudarthrosis. While in noninfected CSA primary stabilization is the major goal, staged surgical management has not been stratified based upon presence of a superinfected CSA. We compare clinical and radiological outcomes of surgical treatment in CSA patients with and without concurrent spinal infections. METHODS: Our single-institution database was reviewed for all patients diagnosed with CSA and surgically treated, who were subsequently divided into 2 cohorts: spinal arthropathy with superimposed infection and those without. Those were comparatively studied for complications and reoperation rate. RESULTS: Fifteen patients with CSA underwent surgical intervention; mean follow up of 15.3 months (range, 0-43). Eleven patients received stabilization with a quadruple-rod thoracolumbopelvic construct, while 4 patients with superinfected CSA underwent a staged procedure. Patients treated with a staged approach experienced fewer intraoperative complications (0% versus 18%) and fewer revision surgeries (25% versus 36%). Both cohorts had the same eventual healing. CONCLUSIONS: Surgical management in CSA patients with primary emphasis on stability and modified surgical treatment based on presence of an active infection in the zone of neuropathic destruction will lead to similar eventual successful results with relatively few and manageable complications in this challenging patient population. LEVEL OF EVIDENCE: 4. CLINICAL RELEVANCE: The proposed treatment algorithm including the use of a quadruple-rod construct with lumbopelivic fixation and a staged approach in patients with superinfected CSA represents a reasonable option in the surgical treatment of CSA.

Estimation of mass apparent density and Young's modulus of femoral neck-head region.

The purpose of this study is to estimate mass apparent density and Young's modulus to investigate biomechanical properties of the proximal femur bone. In this study eleven specimens of sheep femur bone having age between 1-1.25 years and human femur bone having age between 14 and 81years are used. In the present study, the first technique attempts to estimate the density from the image-based Hounsfield unit which is obtained directly from a computed tomography image. The modulus of elasticity is estimated from density-elasticity relation which is available in the literature. Another technique is used to develop a correlation between computed apparent density and greyscale based coefficient obtained by material mapping method using commercial Simpleware ScanIP software. Estimated mean deviation in apparent mass density and Young's modulus is 4.34% and 4.69% in sheep bone and 4.35% and 4.94% in human bone respectively. It is found that apparent density and Young's modulus obtained shows close agreement with values reported in the literature. Moreover, the study attempts to build up a new material model between human and sheep for orthopaedics clinical trials and research in Indian context. In addition, it is also observed that bone mass density of sheep is 1.60 times human. This method can also be useful to study and analyse biomechanical properties of the human femur bone.

Extracorporeal shock wave lithotripsy for distal ureteric stones: which is the ideal approach?

OBJECTIVE: To compare the safety and efficacy of different approaches using ESWL for management of distal ureteric stone in an attempt to select the ideal one. PATIENTS AND METHODS: This is a prospective randomized single-center study conducted on patients with lower third single radiopaque ureteric stone with size less than 15 mm. Patients were randomized into three groups, group A: Supine transgluteal, group B: Modified prone and group C: Prone position (80 patients each). The success of the procedure was assessed by NCCT and is defined as complete stone removal or had only clinically insignificant fragments (< 3 mm) for a maximum of three sessions. The success rate, rate of complications, pain intensity by visual pain scale and patients' satisfaction rate were compared among the three study groups. RESULTS: Data of 240 patients were analyzed (80 in each group). Overall, no significant difference has been observed among all groups regarding demographic data, stone and treatment characteristics. The overall success rates for treatment after the last session were 86.3%, 65% and 62.5% in the three study groups, respectively, with a statistically significant difference for group A. Regarding pain perception and complication rate, all groups were comparable. Patient satisfaction is significantly better in group A versus the other two groups. CONCLUSION: Our study has confirmed better efficacy profile and patients' satisfaction rate of ESWL in the supine position (transgluteal approach) than other different known approaches for the treatment of distal ureteral stones.

Predicting lung mass density of patients with interstitial lung disease and healthy subjects using deep neural network and lung ultrasound surface wave elastography.

The Hounsfield unit (HU) obtained from high resolution computed tomography (HRCT) has been used to assess lung pathology. However, lung mass density has not been quantified in vivo noninvasively. The objective of this study was to develop a method for analyzing lung mass density of superficial lung tissue of patients with interstitial lung disease (ILD) and healthy subjects using a deep neural network (DNN) and lung ultrasound surface wave elastography (LUSWE). Surface wave speeds at three vibration frequencies (100, 150 and 200 Hz) from LUSWE and a pulmonary function test (PFT) including predicted forced expiratory volume (FEV1% pre) and ratio of forced expiratory volume to forced vital capacity (FEV1%/FVC%) were used. Predefined lung mass densities based on the HU for ILD patients and healthy subjects (77 in total) were also used to train the DNN model. The DNN was composed of four hidden layers of 1024 neurons for each layer and trained for 80 epochs with a batch size of 20. The learning rate was 0.001. Performances of two types of activation functions in the DNN, rectified linear activation unit (ReLU) and exponential linear unit (ELU), as well as, machine learning models (support vector regression, random forest, Adaboost) were evaluated. The test dataset of wave speeds, FEV1% pre and FEV%/FVC%, was used to predict lung mass density. The results showed that predictions using a DNN with ELU obtained a comparatively better performance in the testing dataset (accuracy = 0.89) than those of DNN with ReLU or machine learning models. This method may be useful to noninvasively analyze lung mass density by using the DNN model together with the measurements from LUSWE and PFT.

Improving the CT (140 kVp) to PET (511 keV) conversion in PET/MR hardware component attenuation correction.

PURPOSE: Today, attenuation correction (AC) of positron emission tomography/magnetic resonance (PET/MR) hardware components is performed by using an established method from PET/CT hybrid imaging. As shown in previous studies, the established mathematical conversion from computed tomography (CT) to PET attenuation coefficients may, however, lead to incorrect results in PET quantification when applied to AC of hardware components in PET/MR. The purpose of this study is to systematically investigate the attenuating properties of various materials and electronic components frequently used in the context of PET/MR hybrid imaging. The study, thus, aims at improving hardware component attenuation correction in PET/MR. MATERIALS AND METHODS: Overall, 38 different material samples were collected; a modular phantom was used to for CT, PET, and PET/MR scanning of all samples. Computed tomography-scans were acquired with a tube voltage of 140 kVp to determine Hounsfield Units (HU). PET transmission scans were performed with 511 keV to determine linear attenuation coefficients (LAC) of all materials. The attenuation coefficients were plotted to obtain a HU to LAC correlation graph, which was then compared to two established conversions from literature. Hardware attenuation maps of the different materials were created and applied to PET data reconstruction following a phantom validation experiment. From these measurements, PET difference maps were calculated to validate and compare all three conversion methods. RESULTS: For each material, the HU and corresponding LAC could be determined and a bi-linear HU to LAC conversion graph was derived. The corresponding equation was y = 1.64 ∗ 10 - 5 × HU + 1000 + 8.3 ∗ 10 - 2 . While the two established conversions lead to a mean quantification PET bias of 4.69% ± 0.27% and -2.84% ± 0.72% in a phantom experiment, PET difference measurements revealed only 0.5 % bias in PET quantification when applying the new conversion resulting from this study. CONCLUSIONS: An optimized method for the conversion of CT to PET attenuation coefficients has been derived by systematic measurement of 38 different materials. In contrast to established methods, the new conversion also considers highly attenuating materials, thus improving attenuation correction of hardware components in PET/MR hybrid imaging.

Evaluation and Correlation between craniofacial bone densities and C1 and C2 cervical vertebrae using multislice computed tomography / Avaliação e Correlação entre as densidades ósseas craniofaciais e vértebras cervicais C1 e C2 por meio de tomografia computadorizada multislice

Objective: To evaluate the use of computed tomography (CT) as an osteoporosis screening tool, evaluating the relation between the bone mineral density (BMD) from maxilla and mandible with the cervical vertebrae, using the Hounsfield units (HU). Material and Methods: It was included in this study a convenience sample of 118 multislice CT examinations from patients who underwent maxilla, mandible and cervical vertebrae (C1 and C2) simultaneously scans. For each patient, the following regions on both sides of head CT scans were assessed in sagittal slice: above maxillary central and lateral incisors apexes; maxillary tuberosity; mandible head; mandible body endosteum; mandible body trabeculae and vertebrae C1 and C2. HU were measured in each area using a 0.5 cm region of interest (ROI) positioned in the center of the slice. Results: It was verified that there is a correlation between the BMD of the C1 and C2 vertebrae and the anterior region of the maxilla. It was not found correlation between the vertebrae, C1 and C2, and the other structures analyzed. Conclusions: This study showed that this method can be a good screening tool to diagnosis of osteoporosis, when evaluated the correlation between C1 and C2 vertebrae and anterior region of maxilla. More studies are necessary to evaluate the possibility of using CT as an osteoporosis screening tool. (AU)

Objetivos: Avaliar o uso da tomografia computadorizada como ferramenta de rastreamento da osteoporose, avaliando a relação entre a densidade mineral óssea da maxila e mandíbula com as vértebras cervicais, utilizando as unidades de Hounsfield. Material e métodos: Neste estudo foram incluidos uma amostra de 118 pacientes submetidos à exames de tomografia computadorizada multislice que apresentavam as estruturas anatomicas da maxila, mandibula e as vértebras cervicais (C1 e C2) simultaneamente. Para cada paciente, as seguintes regiões dos dois lados da tomografia computadorizada da cabeça foram avaliadas em corte sagital: acima dos ápices dos incisivos centrais e laterais superiores; tuberosidade maxilar; cabeça da mandíbula; endósteo do corpo da mandíbula; trabéculas do corpo da mandíbula e vértebras C1 e C2. As unidades de Hounsfield foram medidas em cada área usando uma região de interesse de 0,5 cm (ROI) posicionada no centro do corte. Resultados: Verificou-se uma correlação positiva entre a densidade mineral óssea das vértebras C1 e C2 e a região anterior da maxila. Não foram encontradas correlação entre as vértebras C1 e C2 e as demais estruturas analisadas. Conclusão: Este estudo mostrou que esse método pode ser uma ferramenta de triagem para o diagnóstico de osteoporose, quando avaliada a correlação entre as vértebras C1 e C2 e a região anterior da maxila. Mais estudos são necessários para avaliar a possibilidade do uso da tomografia computadorizada como ferramenta de rastreamento da osteoporose. (AU)

X-ray computed tomography to study rice (Oryza sativa L.) panicle development.

Computational tomography is an important technique for developing digital agricultural models that may help farmers and breeders for increasing crop quality and yield. In the present study an attempt has been made to understand rice seed development within the panicle at different developmental stages using this technique. During the first phase of cell division the Hounsfield Unit (HU) value remained low, increased in the dry matter accumulation phase, and finally reached a maximum at the maturation stage. HU value and seed dry weight showed a linear relationship in the varieties studied. This relationship was confirmed subsequently using seven other varieties. This is therefore an easy, simple, and non-invasive technique which may help breeders to select the best varieties. In addition, it may also help farmers to optimize post-anthesis agronomic practices as well as deciding the crop harvest time for higher grain yield.

The study of bone density assessment on dental implant sites

INTRODUCTION: Bone density is one of the important factors for the long term success of endosseous implants. The bone density varies from site to site and from patient to patient. A preoperative evaluation of the bone density is quite useful to oral surgeons for planning dental implantation. More accurate information on the bone density will help surgeons identify suitable implant sites, thereby increase the success rate of dental implantation. This study examined the correlation between the bone density measured preoperatively by computed tomography (CT) and the implant primary stability measured by resonance frequency analysis. Furthermore, the effects of the implant sites, gender, age and generalized systemic disorder patients on the bone density and primary implant stability were examined. MATERIALS AND METHODS: One hundred and fourteen patients were selected. None of the patients had undergone a tooth extraction or bone graft history in the previous year. Preoperatively, the patients underwent CT scanning to evaluate the Hounsfield unit (HU), and resonance frequency analysis (RFA) was used to evaluate the implant primary stability at the time of implant installation. All implants were 4.0 mm diameter and 11.5 mm length US II. All patients were recorded and the HU and implant stability quotient (ISQ) value were evaluated according to the sites, gender and age. RESULTS: The highest HU values were found in the mandibular anterior site (827.6+/-151.4), followed by the mandibular molar site (797+/-135.1), mandibular premolar site (753.8+/-171.2), maxillary anterior site (726.3+/-154.4), maxillary premolar site (656.7+/-173.8) and maxillary molar site (621.5+/-164.9). The ISQ value was the highest in the mandibular premolar site (81.5+/-2.4) followed by the mandibular molar site (80.0+/-5.7), maxillary anterior site (77.4+/-4.1), mandibular anterior site (76.4+/-11.9), maxillary premolar site (74.2+/-14.3) and maxillary molar site (73.7+/-7.4). The mean HU and ISQ value were similar in females and males. (HU: P=0.331, ISQ: P=0.595) No significant difference was also found in the age group respectively. However, the correlation coefficients between the variables showed a closed correlation between the HU and ISQ value. CONCLUSION: These results showed close correlation between the bone density (HU) and primary stability value (ISQ) at the time of implant installation (Correlation coefficients=0.497, P<0.01). These results strengthen the hypothesis that it might be possible to predict and quantify the initial implant stability and bone density from a presurgical CT diagnosis. These results strengthen the hypothesis that it might be possible to predict and quantify the initial implant stability and bone density from a presurgical CT diagnosis.

Computed Tomographic Evaluation of Bone Quality of the Mandible Reconstructed by Particular Cellular Bone and Marrow Combined with Platelet Rich Plasma / Oral Science International

Concerning the bone structures of the mandible reconstructed by particular cellular bone and marrow (PCBM), platelet rich plasma (PRP) and tray, we have examined the possibility of implant insertion by clarifying the morphological conditions in each compact and cancellous bone on computed tomography (CT), and by observing the differences in their CT values.Using the computer software program Sim Plant (Materialize Dental, Leuven, Belgium), we morphologically observed 6 cases of implant inserted area after mandibular reconstruction and 11 cases of native bone, and examined the differences in their CT values. The osseointegration rate of each inserted implant was also evaluated.Compared with the native bone group, the PCBM reconstruction group had generally thin compact bone. In the over-3cm-length PCBM reconstruction group, the average CT value was 259.7 ± 94.4 HU (n = 3) in the cancellous bone, whereas in the native bone group, the average CT value was 528.9 ± 140.1 HU (n = 10). Therefore, the PCBM reconstruction group showed significantly lower CT value than the native bone group. However, in the under-3cm-length group, the PCBM reconstruction group showed no significant difference compared with the native bone group. The osseointegration rate of the inserted implants almost 6 months after insertion was 100% in the PCBM reconstruction group and 94.1% in the native bone group.Although the PCBM reconstructed bone had thinner cortical bone and showed lower CT value compared with the native bone, implant insertion was possible.