Correlation of 18F-sodium fluoride uptake and radiodensity in extraosseous metastases of medullary thyroid carcinoma

ABSTRACT Objective: Although 18F-sodium fluoride (18F-NaF) uptake is frequently observed in extraosseous metastases of medullary thyroid carcinoma (MTC) with calcification, it can also occur in metastatic sites without visible calcium deposition, leading to the hypothesis that visually undetectable calcium accumulation may be responsible for this uptake. The aim of this study was to indirectly support this hypothesis by analyzing the correlation between the degree of 18F-NaF uptake and radiodensity in extraosseous MTC metastases, since calcium deposition can increase attenuation even when not visually detectable. Subjects and methods: Extraosseous metastatic lesions of 15 patients with MTC were evaluated using 18F-NaF positron-emission tomography (PET)/computed tomography (CT) and segmented by levels of standardized uptake value (SUV). The correlation between mean SUV and mean Hounsfield unit (HU) values was assessed for the entire group of segments and for two subgroups with different mean HU values. Results: Very high correlations were observed between mean SUV and mean HU values for both the entire group of segments and the subgroup with a mean HU value greater than 130 (p = 0.92 and p = 0.95, respectively; p < 0.01). High correlation (p = 0.71) was also observed in the subgroup with mean HU values ranging from 20 to 130 (p < 0.01). Conclusion: The findings of the present study suggest that there is an association between 18F-NaF uptake and calcium deposition in extraosseous metastases of MTC, supporting the hypothesis that visually undetectable calcium accumulation may be responsible for 18F-NaF uptake in regions without visible calcium deposition.

Differential radiologic characteristics of renal tumours on multiphasic computed tomography

<p><b>INTRODUCTION</b>This study analysed the tumour attenuation characteristics of different subtypes of renal cell carcinomas (RCCs), including clear cell RCC (ccRCC), papillary RCC (pRCC), mixed RCC, chromophobe RCC (chRCC) and oncocytoma.</p><p><b>METHODS</b>We randomly selected 100 RCC cases that underwent nephrectomy between 2004 and 2012 from a collaborative database. Of these cases, 36 were excluded due to the absence of available imaging. The remaining 64 cases comprised 35 ccRCCs, 11 pRCCs, eight chRCCs, seven mixed RCCs and three oncocytomas. The cases were classified as computed tomography (CT) kidney, CT urogram (with plain, nephrographic and pyelographic phases) or CT abdomen (with portovenous and delayed phases). A circular region of interest (ROI) ≥ 1 cmwas drawn and the same standard ROI size was used for each phase at the same site; three different circular ROIs were drawn per lesion per phase. Analysis of variance and t-test were used to examine differences in the radiological characteristics.</p><p><b>RESULTS</b>There was no statistical difference in the attenuation and degree of enhancement between mixed RCCs and ccRCCs. The attenuation and degree of enhancement of the oncocytomas were significantly higher than those of the other RCC subtypes.</p><p><b>CONCLUSION</b>While mixed RCCs did not have attenuation characteristics that differed significantly from those of ccRCCs, oncocytomas can be distinguished from ccRCCs, pRCCs, chRCCs and mixed RCCs by their high radiological density and enhancement. The ability to differentiate oncocytomas from these tumours potentially allows the preoperative selection of patients with small renal masses for conservative management.</p>

Evaluation of indirect pulp capping using three different materials: A randomized control trial using cone‑beam computed tomography.

Objective: The objective of this study was to determine the most suitable material for indirect pulp treatment (IPT) clinically and to determine the thickness (in mm) and type of tissue in terms of radiodensity (in Hounsfield units [HU]) formed after pulp capping using cone‑beam computed tomography (CBCT) scan. Materials and Methods: A longitudinal interventional single‑blind randomized clinical trial was conducted on 94 children (7–12 years) with a deep carious lesion in one or more primary second molar and permanent first molar without the history of spontaneous pain indicated for indirect pulp capping (IPC) procedure. About 109 teeth were treated using three materials, namely, calcium hydroxide (setting type), glass ionomer cement (Type VII), and mineral trioxide aggregate randomly. The teeth were followed up at an interval of 8 weeks, 6 months, and 1 year for success of IPT as per the American Academy of Pediatric Dentistry clinical criteria. For determining the thickness and type of dentin tissue formed, a CBCT scan was done immediately postoperative and another scan at an interval of 6 months. The scans were compared to evaluate the average thickness of the dentin bridge formed. Results and Conclusions: Success rate for IPC was 96.85%. A significant difference was obtained in the average thickness of reparative dentin at immediate postoperative and 6‑month postoperative values in all three groups suggesting distinct barrier formation. Similar significant findings were obtained in radiodensity of barrier formed (in HU). All three materials were found to be equally suitable as IPC agents suggesting mineral gain.

Quantitative computed tomography of the liver in dogs submitted to prednisone therapy / Tomografia computadorizada quantitativa do fígado de cães submetidos à terapia com prednisona

The aim of this study is to evaluate the possible alterations in radiodensity of the hepatic parenchyma and spleen resulting from the corticotherapy with prednisone, correlating these findings with serum biochemical hepatic transaminase activity. A clinical trial was performed on eight healthy dogs with the intent of evaluating possible hepatic alterations after prednisone therapy using quantitative computed tomography. All animals received prednisone orally at a dose of 2mg/kg of weight for 30 days. The radiodensity of the liver and spleen was determined before and after the period that the medication was administered. An increase in the radiodensity of the hepatic parenchyma between the initial and final experimental stages was observed. In the present study the existence of early hepatic alterations were verified, which are compatible with glycogen storage.

O objetivo deste estudo é avaliar as possíveis alterações na radiodensidade do parênquima hepático e esplênico decorrentes da corticoterapia com prednisona, correlacionando estes achados com níveis séricos de transaminase bioquímicas hepáticas. Um ensaio clínico foi realizado em oito cães sadios com o objetivo de avaliar possíveis alterações hepáticas após a terapia com prednisona por meio de tomografia computadorizada quantitativa. Todos os animais receberam prednisona por via oral na dose de 2mg / kg de peso por 30 dias. A radiodensidade do fígado e do baço foi determinada antes e após o período em que a medicação foi administrada. Foi observado aumento da radiodensidade do parênquima hepático entre os estágios iniciais e finais do experimento. No presente estudo, foi verificada a existência de alterações hepáticas precoces, que são compatíveis com o acúmulo de glicogênio.

Quantitative computed tomography of the renal cortex in healthy dogs and cats / Tomografia computadorizada quantitativa do córtex renal de cães e gatos hígidos

Este estudo caracteriza a radiodensidade do córtex renal de 10 cães e 10 gatos adultos, clinicamente saudáveis, por meio de exames de tomografia computadorizada helicoidal. Em cada rim, a radiodensidade renal foi estimada pelo valor médio das três regiões de interesse na região cortical, selecionados no polo cranial, polo caudal e hilo renal. A radiodensidade média do córtex renal nos cães e nos gatos foi, respectivamente, 28,4±4,7 e 22,4±3,6 unidades Hounsfield (HU). Verificou-se que os gatos possuem córtex renal hipoatenuante quando comparado com cães, um fato que está associado à maior deposição de conteúdo lipídico nos rins felinos. A diferença na radiodensidade encontrada entre o córtex renal de cães e de gatos é importante para uma correta interpretação dos achados renais no exame tomográfico.

The effects of image acquisition control of digital X-ray system on radiodensity quantification

OBJECTIVES: Aluminum step wedge (ASW) equivalent radiodensity (eRD) has been used to quantify restorative material's radiodensity. The aim of this study was to evaluate the effects of image acquisition control (IAC) of a digital X-ray system on the radiodensity quantification under different exposure time settings. MATERIALS AND METHODS: Three 1-mm thick restorative material samples with various opacities were prepared. Samples were radiographed alongside an ASW using one of three digital radiographic modes (linear mapping (L), nonlinear mapping (N), and nonlinear mapping and automatic exposure control activated (E)) under 3 exposure time settings (underexposure, normal-exposure, and overexposure). The ASW eRD of restorative materials, attenuation coefficients and contrasts of ASW, and the correlation coefficient of linear relationship between logarithms of gray-scale value and thicknesses of ASW were compared under 9 conditions. RESULTS: The ASW eRD measurements of restorative materials by three digital radiographic modes were statistically different (p = 0.049) but clinically similar. The relationship between logarithms of background corrected grey scale value and thickness of ASW was highly linear but attenuation coefficients and contrasts varied significantly among 3 radiographic modes. Varying exposure times did not affect ASW eRD significantly. CONCLUSIONS: Even though different digital radiographic modes induced large variation on attenuation of coefficient and contrast of ASW, E mode improved diagnostic quality of the image significantly under the under-exposure condition by improving contrasts, while maintaining ASW eRDs of restorative materials similar. Under the condition of this study, underexposure time may be acceptable clinically with digital X-ray system using automatic gain control that reduces radiation exposure for patient.

Utilização da tomografia computadorizada quantitativa como teste de resistência para avaliação de placas ósseas / Quantitative computed tomography as a test of endurance for evaluation of bony plates

Quantitative computed tomography was used to determine the radiodensity of bony plates. The CT scans provided information regarding radiodensity of bony plates and allowed to verify the uniformity of bone mineral density in their scope. The proposed methodology should be considered as another tool for determining the resistance of these biomaterials.

Radiographic Analysis of Instrumented Posterolateral Fusion Mass Using Mixture of Local Autologous Bone and b-TCP (PolyBone(R)) in a Lumbar Spinal Fusion Surgery

OBJECTIVE: Although iliac crest autograft is the gold standard for lumbar fusion, the morbidity of donor site leads us to find an alternatives to replace autologous bone graft. Ceramic-based synthetic bone grafts such as hydroxyapatite (HA) and b-tricalcium phosphate (b-TCP) provide scaffolds similar to those of autologous bone, are plentiful and inexpensive, and are not associated with donor morbidity. The present report describes the use of Polybone(R) (Kyungwon Medical, Korea), a beta-tricalcium phosphate, for lumbar posterolateral fusion and assesses clinical and radiological efficacy as a graft material. METHODS: This study retrospectively analyzed data from 32 patients (11 men, 21 women) who underwent posterolateral fusion (PLF) using PolyBone(R) from January to August, 2008. Back and leg pain were assessed using a Numeric Rating Scale (NRS), and clinical outcome was assessed using the Oswestry Disability Index (ODI). Serial radiological X-ray follow up were done at 1, 3, 6 12 month. A computed tomography (CT) scan was done in 12 month. Radiological fusion was assessed using simple anterior-posterior (AP) X-rays and computed tomography (CT). The changes of radiodensity of fusion mass showed on the X-ray image were analyzed into 4 stages to assess PLF status. RESULTS: The mean NRS scores for leg pain and back pain decreased over 12 months postoperatively, from 8.0 to 1.0 and from 6.7 to 1.7, respectively. The mean ODI score also decreased from 60.5 to 17.7. X-rays and CT showed that 25 cases had stage IV fusion bridges at 12 months postoperatively (83.3% success). The radiodensity of fusion mass on X-ray AP image significantly changed at 1 and 6 months. CONCLUSION: The present results indicate that the use of a mixture of local autologous bone and PolyBone(R) results in fusion rates comparable to those using autologous bone and has the advantage of reduced morbidity. In addition, the graft radiodensity ratio significantly changed at postoperative 1 and 6 months, possibly reflecting the inflammatory response and stabilization.

Radiodensidade hepática de cães hígidos por tomografia computadorizada helicoidal / Hepatic radiodensity in healthy dogs by helical computed tomography

Os objetivos do presente estudo são obter valores médios de radiodensidade do parênquima hepático de cães normais e descrever a adaptação na espécie canina de uma técnica de mensuração da densidade tomográfica já utilizada em humanos. Para a realização do estudo, foram adquiridos exames tomográficos do fígado de oito cães hígidos adultos jovens, sem distinção de sexo ou raça. Após a realização do exame, foram obtidos valores médios de radiodensidade de três regiões de interesse (ROIs) do parênquima hepático em três diferentes níveis de corte. Além disso, foi realizada a análise de uma região de interesse do parênquima esplênico em três diferentes níveis de corte para uma avaliação comparativa entre os órgãos. Observou-se, no grupo avaliado, um valor médio de atenuação HU de 59,58±3,34 unidades Hounsfield (HU). A diferença de densidade entre o parênquima hepático e o esplênico foi, em média, de 4,69±7,77HU. No presente estudo, o exame de tomografia computadorizada demonstrou ser uma técnica com alta sensibilidade para estimar a radiodensidade do parênquima hepático. O estabelecimento de valores de normalidade e a padronização de uma metodologia de avaliação permitem melhor caracterização de alterações na radiodensidade pelo exame tomográfico, auxiliando no estabelecimento de um diagnóstico e minimizando a necessidade de exames invasivos.

The objectives of the study reported here were to obtain medium values of hepatic parenchyma radiodensity in healthy dogs, and also describe the adaptation in canine specie of a tomographic density measurement technique, which has already been used in humans. For the accomplishment of this study tomographic exams were realized in eight young dogs without sex or breed definition. After the exams, the liver's degree of HU attenuation was determined through a mean value of three selected regions of interest (ROI) in hepatic parenchyma obtained in three different levels of cut. Additionally, a region of interest in the splenic parenchyma was analyzed in three different levels of cut for comparative evaluation between the organs. In the experimental group it was observed an X-ray attenuation mean value of 59.58±3.34 Hounsfield Units (HU). The density difference between hepatic and splenic parenchyma was a mean value of 4.69±7.77HU. In the present study, it was observed that computed tomography is a technique with high sensitivity to estimate hepatic parenchyma density. The establishment of reference values and the standardizing of an evaluation methodology allow a better characterization of radiodensity changes in the tomographic exams, assisting in establishing a diagnosis and minimizing the necessity of invasive testing to the patient.

The Predictability of Stone Composition According to the Radiodensity of Urinary Stone on KUB Film / 대한비뇨기과학회지

A plain abdominal X-ray film (simple abdomen or KUB) is often used to display several types of urinary stones in vivo, or at least for a differentiation between calcium-containing 'radio-opaque' and calcium-noncontaining 'non-opaque' stones. We evaluated whether a KUB film could offer the information on composition of urinary calculi or not. The radiodensity of stone itself, the ratio of radio-opacity between the stones and the 2nd lumbar vertebra or lower renal pole parenchyme were measured in each 20 patients with renal stones above 1cm in diameter and variable compositions. However, such a definite distinction could not be resulted in our study. Therefore, we think that it is not possible to achieve a predictability of stone composition by measuring of its radiodensity on KUB film.