Computed Tomography Radiodensity Research Articles

Pulmonary volumes and signs of chronic airflow limitation in quantitative computed tomography.

Computed tomography (CT) offers pulmonary volumetric quantification but is not commonly used in healthy individuals due to radiation concerns. Chronic airflow limitation (CAL) is one of the diagnostic criteria for chronic obstructive pulmonary disease (COPD), where early diagnosis is important. Our aim was to present reference values for chest CT volumetric and radiodensity measurements and explore their potential in detecting early signs of CAL. From the population-based Swedish CArdioPulmonarybioImage Study (SCAPIS), 294 participants aged 50-64, were categorized into non-CAL (n = 258) and CAL (n = 36) groups based on spirometry. From inspiratory and expiratory CT images we compared lung volumes, mean lung density (MLD), percentage of low attenuation volume (LAV%) and LAV cluster volume between groups, and against reference values from static pulmonary function test (PFT). The CAL group exhibited larger lung volumes, higher LAV%, increased LAV cluster volume and lower MLD compared to the non-CAL group. Lung volumes significantly deviated from PFT values. Expiratory measurements yielded more reliable results for identifying CAL compared to inspiratory. Using a cut-off value of 0.6 for expiratory LAV%, we achieved sensitivity, specificity and positive/negative predictive values of 72%, 85% and 40%/96%, respectively. We present volumetric reference values from inspiratory and expiratory chest CT images for a middle-aged healthy cohort. These results are not directly comparable to those from PFTs. Measures of MLD and LAV can be valuable in the evaluation of suspected CAL. Further validation and refinement are necessary to demonstrate its potential as a decision support tool for early detection of COPD.

Adipose tissue composition determines its computed tomography radiodensity.

Adipose tissue radiodensity in computed tomography (CT) performed before surgeries can predict surgical difficulty. Despite its clinical importance, little is known about what influences radiodensity. This study combines desorption electrospray ionization mass spectrometry imaging (DESI-MSI) and electrospray ionization (ESI) with machine learning to unveil how chemical composition of adipose tissue determines its radiodensity. Patients in the study underwent abdominal surgeries. Before surgery, CT radiodensity of fat near operated sites was measured. Fifty-three fat samples were collected and analyzed by DESI-MSI, ESI, and histology, and then sorted by radiodensity, demographic parameters, and adipocyte size. A non-negative matrix factorization (NMF) algorithm was developed to differentiate between high and low radiodensities. No associations between radiodensity and patient age, gender, weight, height, or fat origin were found. Body mass index showed negative correlation with radiodensity. A substantial difference in chemical composition between adipose tissues of high and low radiodensities was observed. More radiodense tissues exhibited greater abundance of high molecular weight species, such as phospholipids of various types, ceramides, cholesterol esters and diglycerides, and about 70% smaller adipocyte size. Less radiodense tissue showed high abundance of short acyl-tail fatty acids. This study unveils the connection between abdominal adipose tissue radiodensity and its chemical composition. Because the radiodensity of the fat around the surgical site is associated with surgical difficulty, it is important to understand how adipose tissue composition affects this parameter. We conclude that fat tissue with a higher content of various phospholipids and waxy lipids is more CT radiodense. This study establishes the connection between the CT radiodensity of adipose tissue and its chemical composition. Clinicians may use this information for preoperative planning of surgical procedures, potentially modifying their surgical approach (for example, performing partial nephrectomy openly rather than laparoscopically). • Adipose tissue radiodensity values in computed tomography images taken prior to the surgery can potentially predict surgery difficulty. • Fifty-three human specimens were analyzed by advanced mass spectrometry, molecular imaging, and machine learning to establish the key features that determine Hounsfield units' values of adipose tissue. • The findings of this research will enable clinicians to better prepare for surgical procedures and select operative strategies.

Quantitative Assessment and Comparative Analysis of Longitudinal Lung CT Scans of Chest-Irradiated Nonhuman Primates.

Computed tomography (CT) imaging has been used to diagnose radiation-induced lung injury for decades. However, histogram-based quantitative tools have rarely been applied to assess lung abnormality due to radiation-induced lung injury (RILI). Here, we used first-order summary statistics to derive and assess threshold measures extracted from whole lung histograms of CT radiodensity in rhesus macaques. For the present study, CT scans of animals exposed to 10 Gy of whole thorax irradiation were utilized from a previous study spanning 2-9 months postirradiation. These animals were grouped into survivors and non-survivors based on their clinical and experimental endpoints. We quantified the change in lung attenuation after irradiation relative to baseline using three density parameters; average lung density (ALD), percent change in hyper-dense lung volume (PCHV), hyperdense volume as a percent of total volume (PCHV/TV) at 2-month intervals and compared each parameter between the two irradiated groups (non-survivors and survivors). We also correlated our results with histological findings. All the three indices (ALD, PCHV, PCHV/TV) obtained from density histograms showed a significant increase in lung injury in non-survivors relative to survivors, with PCHV relatively more sensitive to detect early RILI changes. We observed a significant positive correlation between histologic pneumonitis scores and each of the three CT measurements, indicating that CT density is useful as a surrogate for histologic disease severity in RILI. CT-based three density parameters, ALD, PCHV, PCHV/TV, may serve as surrogates for likely histopathology patterns in future studies of RILI disease progression.

Intravenous Glibenclamide Reduces Lesional Water Uptake in Large Hemispheric Infarction.

Background and Purpose- Prior studies have shown a linear relationship between computed tomography (CT)-derived radiodensity and water uptake, or brain edema, within stroke lesions. To test the hypothesis that intravenous glibenclamide (glyburide; BIIB093) reduces ischemic brain water uptake, we quantified the lesional net water uptake (NWU) on serial CT scans from patients enrolled in the phase 2 GAMES-RP Trial (Glyburide Advantage in Malignant Edema and Stroke). Methods- This was a post hoc exploratory analysis of the GAMES-RP study. Noncontrast CT scans performed between admission and day 7 (n=264) were analyzed in the GAMES-RP modified intention-to-treat sample. Quantitative change in CT radiodensity (ie, NWU) and midline shift (MLS) was measured. The gray and white matter NWU were also examined separately. Repeated-measures mixed-effects models were used to assess the effect of intravenous glibenclamide on MLS or NWU. Results- A median of 3 CT scans (interquartile range, 2-4) were performed per patient during the first 7 days after stroke. In a repeated-measures regression model, greater NWU was associated with increased MLS (β=0.23; 95% CI, 0.20-0.26; P<0.001). Treatment with intravenous glibenclamide was associated with reduced NWU (β=-2.80; 95% CI, -5.07 to -0.53; P=0.016) and reduced MLS (β=-1.50; 95% CI, -2.71 to -0.28; P=0.016). Treatment with intravenous glibenclamide reduced both gray and white matter water uptake. In mediation analysis, gray matter NWU (β=0.15; 95% CI, 0.11-0.20; P<0.001) contributed to a greater proportion of MLS mass effect, as compared with white matter NWU (β=0.08; 95% CI, 0.03-0.13; P=0.001). Conclusions- In this phase 2 post hoc analysis, intravenous glibenclamide reduced both water accumulation and mass effect after large hemispheric infarction. This study demonstrates NWU is a quantitative and modifiable biomarker of ischemic brain edema accumulation. Clinical Trial Registration- URL: https://www.clinicaltrials.gov. Unique identifier: NCT01794182.

Diagnostic facilities of methods of ultrasound diagnostics in urolithiasis in children

There are presented data of the integrated ultrasound (US) examination of 85 children with urolithiasis (IBC) at the age of from 3 months up to 17 years. In traditional ultrasound study (in gray scale mode), the main criterion for the presence of stone - distal acoustic «shadow» was evaluated in dependence on its intensity from 0 to 4 scores. When using color Doppler mapping (CDM) there was established the existence of flaring artifact (FA), which occurred in the reflection of the ultrasonic wave from the reflective stone structure. According to the density index (DI) the presence and density of calculus were detected with the use of Acoustic Structure Quantification (ASQ) methodology for quantifying the structure. The obtained data were compared with data of computed tomography (CT). It has been established that in case of the presence of the «shadow» accounted of 4 scores, FA has been clearly defined, DI ranged from 5,5 to 6,8, CT indices exceed 1100-1500 Hu. When the severity of the «shadow» was of 3 scores, FA remained to be intensive, DI was in the range of 3,5-5,5 and CT density ranged from 800 to 1100 Hu. «Shadow» at 2 scores came from the central department of calculus, FA spectrum corresponded to its width, DI ranged from 3,5 to 2,0 and CT radiodensity - 250 to 800 Hu. Weak «shadow» at 1 score corresponds to a low density stone, FA was narrow, DI ranged from 2,0 to 1,5. At 0 score DI was less than 0,9 and easily permitted ultrasound through. Established patterns indicate to the feasibility of the integrated use of ultrasonic methods in the evaluation of the density of the stone in preparing the patient for performing remote lithotripsy.

HRCT morphological characteristics distinguishing minimally invasive pulmonary adenocarcinoma from invasive pulmonary adenocarcinoma appearing as subsolid nodules with a diameter of ≤3 cm

To differentiate retrospectively the morphological characteristics at high-resolution computed tomography (CT) between minimally invasive pulmonary adenocarcinoma (MIA) and invasive pulmonary adenocarcinoma (IAC) appearing as subsolid nodules (SNs) with a diameter of ≤3cm and to provide information to help operative decision-making. The patient notes of 260 patients with SNs of ≤3cm in diameter (98 with MIA and 162 with IAC) confirmed at surgery and histopathology from September 2008 to June 2012 were reviewed retrospectively at the Department of Radiology, Weifang Respiratory Disease Hospital. Sixty-seven patients had pure ground-glass nodules (PGGNs) and 193 had mixed ground-glass nodules (MGGNs). Patients were grouped according to the final pathology: minimally invasive MIA and IAC. The HRCT characteristics were compared between the two groups. There were statistically significant differences in the pattern, shape, diameter of solid components, proportion of solid components, CT radiodensity values of the ground-glass and solid components, borders, margins, air bronchograms, microvascular signs, and pleural indentations of the nodules between the two groups (all p<0.05). Multivariate and receiver operating characteristic (ROC) analyses indicated significant predictors of MIAs were as follows: small lesion diameter (≤14.7mm), solid components ≤7mm, <50% of solid components, low CT radiodensity values of the solid components (≤-107HU), air bronchograms in the ground-glass opacity components, and microvascular signs. The morphological characteristics at high-resolution CT can be used to differentiate between MIAs and IACs appearing as SNs with a diameter of ≤3cm and provide information to help operative decision-making.

Diagnostic performance of unenhanced computed tomography and 18 F-fluorodeoxyglucose positron emission tomography in indeterminate adrenal tumours.

Evidence on the diagnostic performance of adrenal imaging is limited. We aimed to assess the diagnostic performance of unenhanced computed tomography (CT) and 18 F-fluorodeoxyglucose (18 FDG) positron emission tomography (PET)/CT imaging in a high-risk population for adrenal malignancy using an optimal reference standard. Retrospective cohort study. Imaging studies of patients with adrenal nodules who underwent adrenal biopsy and/or adrenalectomy between 1994 and 2014 were reviewed and compared to the reference standard of histology. Eighty % of patients presented with known or suspected extra-adrenal malignancy. Unenhanced abdominal CT was performed in 353 patients with adrenal lesions; median size was 3 (0.7-15) cm and median radiodensity was 33 (-21-78) Hounsfield units (HU). Radiodensity of >10HU diagnosed malignancy with a sensitivity of 100%, specificity of 33%, positive predictive value (PPV) of 72% and negative predictive value (NPV) of 100%. 18 FDG-PET/CT was performed in 89 patients; median tumour size was 2.1 (0.7-9.2) cm. Maximum standardized uptake (SUV max) was higher in malignant lesions when compared to benign lesions (median=10 [2.3-29.4] vs 3.7 [1.4-24.5], respectively, P<.0001). Similarly, median SUV max lesion to SUV max liver ratio (ALR) in malignant lesions was higher than in benign lesions (median=3 [0.74-13.4] vs 1.2 [0.5-6.6], respectively, P<.0001). 18 FDG-PET/CT ALR >1.8 diagnosed malignancy with a sensitivity of 87%, specificity of 84%, PPV of 85% and NPV of 86%. Noncontract CT radiodensity of ≤10HU excludes malignancy even in a high-risk population. For indeterminate adrenal lesions, given a superior specificity, 18 FDG-PET/CT could be considered as a second stage imaging study.

Human Brown Fat Radiodensity Indicates Underlying Tissue Composition and Systemic Metabolic Health.

Metabolic imaging studying brown adipose tissue (BAT) physiology has increased, in which computed tomography (CT) is commonly used as an anatomical reference for metabolic positron emission tomography (PET) imaging. However, the capacity of CT to provide metabolic information has been underexploited. To evaluate whether CT radiodensity of BAT could noninvasively estimate underlying tissue morphology, regarding amount of stored triglycerides. Furthermore, could the alteration in tissue characteristics due to cold stimulus, as a marker for active BAT, be detected with radiodensity? Can BAT be differentiated from white adipose tissue (WAT) solely using CT-based measurements? A cross-sectional study evaluating 66 healthy human subjects with CT, PET, and 1H-magnetic resonance spectroscopy (1H-MRS). BAT radiodensity was measured with CT. BAT-stored triglyceride content was measured with 1H-MRS. Arterial blood volume in BAT, as a marker of tissue vascularity, was measured with [15O]H2O, along with glucose or fatty acid uptake using [18F]2-fluoro-2-deoxy-D-glucose or 14(R,S)-[18F]fluoro-6-thia-heptadecanoic acid PET imaging, respectively. BAT radiodensity was found to be correlating with tissue-retained blood and triglyceride content. Cold stimulus induced an increase in BAT radiodensity. Active BAT depots had higher radiodensity than both nonactive BAT and WAT. BAT radiodensity associated with systemic metabolic health parameters. BAT radiodensity can be used as a marker of underlying tissue morphology. Active BAT can be identified using CT, exploiting tissue composition information. Moreover, BAT radiodensity provides an insight into whole-body systemic metabolic health.

Ultrashort echo time MRI biomarkers of asthma.

To develop and assess ultrashort echo-time (UTE) magnetic resonance imaging (MRI) biomarkers of lung function in asthma patients. Thirty participants including 13 healthy volunteers and 17 asthmatics provided written informed consent to UTE and pulmonary function tests in addition to hyperpolarized-noble-gas 3T MRI and computed tomography (CT) for asthmatics only. The difference in MRI signal-intensity (SI) across four lung volumes (full-expiration, functional-residual-capacity [FRC], FRC+1L, and full-inspiration) was determined on a voxel-by-voxel basis to generate dynamic proton-density (DPD) maps. MRI ventilation-defect-percent (VDP), UTE SI, and DPD values as well as CT radiodensity were determined for whole lung and individual lobes. Mean SI at full-expiration (P < 0.01), FRC (P < 0.05), and DPD (P < 0.01) were greater in healthy volunteers compared to asthmatics. In asthmatics, UTE SI at full-expiration and DPD were correlated with FEV1 /FVC (SI r = 0.73/P = 0.002; DPD r = 0.75/P = 0.003), RV/TLC (SI r = -0.57/P = 0.02), or RV (DPD r = -0.62/P = 0.02), CT radiodensity (SI r = 0.83/P = 0.006; DPD r = 0.71/P = 0.01), and lobar VDP (SI rs = -0.33/P = 0.02; DPD rs = -0.47/P = 0.01). In patients with asthma, UTE SI and dynamic proton-density were related to pulmonary function measurements, whole lung and lobar VDP, as well as CT radiodensity. Thus, UTE MRI biomarkers may reflect ventilation heterogeneity and/or gas-trapping in asthmatics using conventional equipment, making this approach potentially amenable for clinical use. 2 J. Magn. Reson. Imaging 2017;45:1204-1215.

A simple evaluation method for early detection of bisphosphonate-related osteonecrosis of the mandible using computed tomography

ObjectivesThe aim of this study was to establish a simple method for the early detection of bisphosphonate-related osteonecrosis of the jaw (BRONJ) using computed tomography (CT). Materials and methodsCT images of the mandible were obtained from a total of 20 patients with BRONJ and 20 control subjects. BRONJ was classified into 2 groups, with bone exposure (Stage 1–3 BRONJ) or without (Stage 0 BRONJ). In each patient, 15 transaxial CT images were selected and 30 configured regions of interest (ROI) were identified. The ANOVA test was applied to test the relationship between the severity of systemic risk factors. ResultsRegarding the local status of the mandible, significant differences were observed among the Stage 0 BRONJ, Stage 1–3 BRONJ, non-BRONJ and control groups in the cancellous bone CT radiodensity values, but there were no significant differences between the Stage 0 and Stage 1–3 BRONJ groups. In the cortical bone widths, significant differences were observed only between BRONJ and the controls. ConclusionsMeasuring cancellous bone CT radiodensity value has the potential to be a simple and quantitative method to detect the early stages of BRONJ.

Creation and Characterization of an Ultrasound and CT Phantom for Noninvasive Ultrasound Thermometry Calibration

Ultrasound thermometry provides noninvasive 2-D temperature monitoring, and in this paper, we have investigated the use of computed tomography (CT) radiodensity to characterize tissues to improve the accuracy of ultrasound thermometry. Agarose-based tissue-mimicking phantoms were created with glyceryl trioleate (a fat-mimicking material) concentration of 0%, 10%, 20%, 30%, 40%, and 50%. The speed of sound (SOS) of the phantoms was measured over a temperature range of 22.1-41.1 °C. CT images of the phantoms were acquired by a clinical dedicated breast CT scanner, followed by calculation of the Hounsfield units (HU). The phantom was heated with a therapeutic acoustic pulse (1.54 MHz), while RF data were acquired with a 10-MHz linear-array transducer. Two-dimensional speckle tracking was used to calculate the thermal strain offline. The tissue-dependent thermal strain parameter required for ultrasound thermometry was analyzed and correlated with CT radiodensity, followed by the validation of the temperature prediction. Results showed that the change in SOS with the temperature increase was opposite in sign between the 0%-10% and 20%-50% trioleate phantoms. The inverse of the tissue-dependent thermal strain parameter of the phantoms was correlated with the CT radiodensity (R(2) = 0.99). A blinded ultrasound thermometry study on phantoms with a trioleate range of 5%-35% demonstrated the capability to estimate the tissue-dependent thermal strain parameter and estimate temperature with error less than ~1 °C. In conclusion, CT radiodensity may provide a method for improving ultrasound thermometry in heterogeneous tissues.

Image quality and radiation exposure in CT of the pancreas: 320-MDCT with and without adaptive iterative dose reduction versus 64-MDCT

To compare the image quality and radiation exposure in computed tomography (CT) of the pancreas acquired using 320-multidetector (MD)CT versus 64-MDCT and to demonstrate the effects of adaptive iterative dose reduction (AIDR) on 320-MDCT. One hundred and fifty patients were randomized into three groups including 320-section volume imaging using AIDR (group A), 320-slice volume scan without AIDR (group B), and 64-section helical imaging without AIDR (group C). Transaxial arterial, pancreatic phase, and volume-rendered CT angiographic images were reconstructed. CT radiodensity of the abdominal aorta, pancreas, signal-to-noise ratios (SNR), dose-length products (DLPs; mGycm), and image quality were measured. No significant difference in CT radiodensity of the abdominal aorta or pancreas was noted between groups. Mean DLPs were 600.9±145.8, 681.6±97.5, and 1231.5±271.4 in groups A, B, and C, respectively. The DLP was reduced by 51% in group A and 45% in group B compared to group C (p<0.001). SNRs of the pancreas during the pancreatic phase were comparable between groups A and C, but were significantly lower in group B (p<0.001). Image quality, including the depiction of some small arterial branches on the arterial and CT angiographic images and the main pancreatic duct on the pancreatic-phase images, were significantly lower in group B than in groups A and C (p=0.008-0.038). Radiation dose can be markedly reduced for contrast-enhanced CT imaging of the pancreas without compromising image quality using a 320-MDCT with AIDR, compared with 64-section helical CT.

The radiopacity of ingested medications

We investigated prospectively the radiopacity of 312 pills found on a university hospital formulary by first radiographing them through 15 and 25 cm of water to duplicate the radiodensity of the human body. The pills that were radiodense through water were studied in a human cadaver model, and their densities were quantified by computed tomography (CT). Thirty-five of 312 pills were radiopaque in 15 cm or more of water, and 23 of these pills were radiopaque on a plain radiograph when placed in the stomach of a cadaver. Common mnemonics used to identify radiopaque pills were found to be incomplete and inadequate. Chloral hydrate, iron-containing preparations, calcium carbonate, iodinated compounds, acetazolamide, busulfan, and potassium preparations were consistently radiopaque. Antihistamines, phenothiazines, and tricyclic antidepressants demonstrated varying radiopacity. There was varying radiopacity among the same medications made by different manufacturers. The presence of an enteric coating did not assure that the pill would be radiopaque. Merely radiographing a pill that has been placed on a standard radiograph cassette will make pills that are actually radiolucent in the body appear radiopaque. This test cannot be used to predict radiopacity in vivo. Visibility when radiographed through 15 cm or more of water and a CT radiodensity of more than 1,300 Hounsfield units are predictors of the radiopacity of a pill in the stomach of a cadaver model on a standard KUB radiograph. Variables, such as the size of the patient, the arrangement of pills in the stomach, air contrasting a pill, and the specific composition of the enteric coating or the pillmatrix, affect the radiodensity of pills.(ABSTRACT TRUNCATED AT 250 WORDS)