Computed Tomography Attenuation Coefficient Research Articles

Computed tomography measured psoas muscle attenuation predicts mortality after transcatheter aortic valve implantation.

The aim of this study was to determine if computed tomography (CT) psoas muscular attenuation measurements may predict all-cause mortality in patients undergoing TAVI. Ninety-four consecutive patients undergoing TAVI were analysed. The CT axial slice at the level of the fourth lumbar vertebra was selected. The psoas muscle areas were manually contoured. The circumferential surface area (CSA) of both psoas muscles was determined by selecting the voxels with attenuation values, ranging from 0 to 100 Hounsfield Units (HU). The mean CT attenuation coefficient of the psoas muscle (Psoas mean HU) was measured. The muscle was subdivided into a low-density muscle (LDM) (0-29 HU) and high-density muscle (HDM) (30-100 HU) portion. The HDM/LDM ratio was calculated. We searched for a correlation between HDM/LDM, CSA LDM (%), Psoas mean HU and all-cause mortality. The mean age was 81.2 ± 7.5 years. Thirty patients had adverse outcome (all-cause mortality). Compared with patients with the lowest CSA LDM (%), patients in the third and second tertiles had an increased hazard ratio for mortality (2.871; 95% confidence interval 0.880-9.371 and 5.044; 95% confidence interval 1.641-15.795, respectively) in a multivariable model with EuroSCORE II, Barthel frailty index and CSA LDM (%) (P = 0.231, 0.097 and 0.019, respectively). HDM/LDM and Psoas mean HU (as continuous variable) were also independent predictors of all-cause mortality (P = 0.019, P = 0.013, respectively). CSA LDM (%), Psoas mean HU and HDM/LDM are independent and incremental predictors of all-cause mortality in patients undergoing TAVI.

Evaluation of femoral head bone quality by Hounsfield units: a comparison with dual-energy X-ray absorptiometry.

Osteoporosis is associated with decreases in bone mineral density (BMD) and is diagnosed using dual-energy X-ray absorptiometry (DXA). Computed tomography (CT), performed in routine practice, can also be used to evaluate bone quality without additional cost. To determine whether Hounsfield units (HU), a standardized CT attenuation coefficient, measured from the femoral head correlated with DXA-measured BMD. We evaluated 82 patients (14 men, 68 women; mean age, 67 years) undergoing femoral DXA and CT (non-enhanced abdominopelvic and hip scans) with 130 kV to determine whether HU correlated with T-scores. HU were measured by two radiologists using the largest spherical region of interest including the medullary bone of the femoral head from the junction point of the most caudal section of the femoral head with the femoral neck in 5-mm axial sections. The correlations of both sides' HU values with their ages and DXA femur T-score were evaluated. HU values obtained from both femoral heads showed significant variation between the osteoporotic and non-osteoporotic groups (both P = 0.000) and strongly correlated with each other and DXA femur T-scores (left r = 0.75, right r = 0.73, respectively). In ROC curve analysis, predictive power of left HU values in identifying patients with osteoporotic femur DXA T-score was 0.905, and for right HU values it was 0.924. Osteoporosis cutoff values were 198 HU and 204 HU for the left and right hips, respectively. HU obtained from CT performed in routine practice correlated with the DXA scores, thus providing an alternative method to determine regional bone quality without additional cost. This may be useful when choosing a fixation method, especially in trauma cases with already-performed abdominopelvic or pelvic CT in emergency services.

Application of metastatic biopsy based on "When, Who, Why, Where, How (4W1H)" principle in diagnosis and treatment of metastatic castration-resistance prostate cancer.

BackgroundTo determine the feasibility of secondary biopsy of metastatic castration-resistance prostate cancer based on the “4W1H—When, Who, Why, Where, How” principle and analyze the factors that affect tumor detection. Its application will further direct the patients for individualized precision therapy.MethodsA total of 55 patients were collected for secondary biopsy (27 prostate biopsies and 55 metastases biopsies). The parameters of biopsy location, computed tomography attenuation coefficient, lesion size, core number, laboratory tests, and the use of bone protection were evaluated. Histopathological data and the pathogenesis and etiology classification were used to guide precision treatment.ResultsFifteen/27 patients had a positive prostate biopsy, and 47/55 had positive metastasis biopsy. Bone metastasis biopsy was positive in 21/29 of cases. Also, parenchymal organs and lymph node biopsies were positive. In the prostate rebiopsy, significant differences were observed between total prostate volume (P=0.028), prostate-specific antigen (PSA) density (P=0.047), PSA velocity (P=0.036), and positive biopsy results. In the bone metastasis biopsy, we divided the patients into biopsy-positive and -negative groups. The computed tomography attenuation coefficient, PSA, alkaline phosphatase, and hemoglobin were related to tumor positive detection. However, the lesion size, core number, bone-sparing agents and previous treatments did not affect tumor detection.ConclusionsIn metastatic castration-resistant prostate cancer (mCRPC) patients, the “4W1H” principle was applied in the second biopsy. The biopsy site, image, and laboratory variables affected the positive of tumor tissue. Further pathological analysis of tumor tissue is essential to guide the precision medicine of mCRPC etiological classification.

Novel Logistic Regression Model of Chest CT Attenuation Coefficient Distributions for the Automated Detection of Abnormal (Emphysema or ILD) Versus Normal Lung

We evaluated the role of automated quantitative computed tomography (CT) scan interpretation algorithm in detecting interstitial lung disease (ILD) and/or emphysema in a sample of elderly subjects with mild lung disease. We hypothesized that the quantification and distributions of CT attenuation values on lung CT, over a subset of Hounsfield units (HUs) range (-1000 HU, 0 HU), can differentiate early or mild disease from normal lung. We compared the results of quantitative spiral rapid end-exhalation (functional residual capacity, FRC) and end-inhalation (total lung capacity, TLC) CT scan analyses of 52 subjects with radiographic evidence of mild fibrotic lung disease to the results of 17 normal subjects. Several CT value distributions were explored, including (1) that from the peripheral lung taken at TLC (with peels at 15 or 65 mm), (2) the ratio of (1) to that from the core of lung, and (3) the ratio of (2) to its FRC counterpart. We developed a fused-lasso logistic regression model that can automatically identify sub-intervals of -1000 HU and 0 HU over which a CT value distribution provides optimal discrimination between abnormal and normal scans. The fused-lasso logistic regression model based on (2) with 15-mm peel identified the relative frequency of CT values of over -1000 HU and -900 and those over -450 HU and -200 HU as a means of discriminating abnormal versus normal lung, resulting in a zero out-sample false-positive rate, and 15% false-negative rate of that was lowered to 12% by pooling information. We demonstrated the potential usefulness of this novel quantitative imaging analysis method in discriminating ILD and/or emphysema from normal lungs.

Ultrasmall dopamine-coated nanogolds: preparation, characteristics, and CT imaging

ABSTRACTWater-dispersible ultrasmall nanogolds (WDU AuNPs) and their dopamine-coated nanogolds (WDU AuNPs@DPAs) were prepared by a reduction method with sodium borohydride as a reducing agent and a stabilised agent of 2-mercaptosuccinic acid in aqueous solution. The effects of these nanoparticles on computed tomography (CT) imaging were evaluated. The size distributions and Zeta potential of the nanoparticles were measured with a Malvern size analyser, and nanoparticle morphology was observed by transmission electron microscopy. These characteristics were confirmed by Fourier transform spectroscopy and ultraviolet/visible spectra. It was found that WDU AuNPs@DPAs were 5.4 nm in size with clear core–shell structure. The 3-(4, 5-Dimethyl-2-thiazolyl)-2, 5-diphenyltetrazolium bromide assay results showed that the WDU AuNPs and WDU AuNPs@DPAs were hypotoxic to different cells. The WDU AuNPs@DPAs showed a much longer circulation time and a larger CT attenuation coefficient than iohexol and could be excreted by the kidney and bladder. These nanoparticles showed considerable potential for future application in CT imaging.

Validation of the CT iterative reconstruction technique for low-dose CT attenuation correction for improving the quality of PET images in an obesity-simulating body phantom and clinical study

The aim of this study was to validate the efficacy of computed tomography (CT) iterative reconstruction (CT-IR) for low-dose CT attenuation correction in terms of the estimation of attenuation coefficient and quality of PET images. We used normal and obesity-simulating body phantoms. PET images were reconstructed using two attenuation correction maps obtained using filtered back projection (CT-FBP) and CT-IR. The CT numbers, attenuation coefficients, contrast-to-noise ratio (CNR10 mm), and coefficient of variation were evaluated. Fifty-two consecutive patients who underwent F-FDG PET/CT with low-dose CT scans were selected for the clinical study. Clinical PET images were reconstructed using CT-FBP and CT-IR, and the effects of CT-IR were examined according to the maximum standardized uptake value (SUVmax), contrast-to-noise ratio in the tumor (CNRtumor), and signal-to-noise ratio in the liver (SNRliver). The CT number on the CT-IR was significantly lower than that of CT-FBP in the obesity-simulating body phantom. The decrease in attenuation coefficients obtained using CT-IR was smaller than that obtained using CT-FBP. The CNR10 mm and coefficient of variation obtained using CT-IR were superior to those obtained using CT-FBP. The SUVmax was not significantly different between the CT-FBP and CT-IR. Although the difference in the SNRliver between the CT-FBP and CT-IR was not significant, the CNRtumor of the CT-IR was significantly higher than that obtained using CT-FBP in obese patients. We demonstrated that CT-IR improved the estimation of the attenuation coefficient and provided significant improvement in the CNR of the clinical PET images.

Assessment of a Model-Based, Iterative Reconstruction Algorithm (MBIR) Regarding Image Quality and Dose Reduction in Liver Computed Tomography

The purpose of this study was to assess the image quality of half-dose (HD) liver computed tomography (CT) using a model-based iterative reconstruction algorithm (MBIR) compared with reference dose (RD) using filtered back projection (FBP) and the HD CT images using FBP and adaptive statistical iterative reconstruction (ASIR). A total of 103 patients suspected of having liver metastases underwent liver CT including HD portal venous phase imaging. Among these patients, 73 had undergone RD liver CT reconstructed using FBP, and the HD portal phase CT scans were separately reconstructed using FBP and MBIR. For the other 30 patients, the HD CT images were reconstructed using FBP, ASIR, and MBIR. The CT attenuation coefficients and the mean image noise of various sites, including the liver, the aorta, the main portal vein (MPV), and the subcutaneous fat, were measured, and the contrast-to-noise ratios (CNRs) of the metastatic lesion to the liver and the MPV to the liver were calculated. Two radiologists reviewed each image set with regard to image noise, image quality, lesion conspicuity, and diagnostic acceptability. Compared with RD CT, there was a 46.1% decrease in CT dose index volume with HD CT. Image noise was significantly lower in the HD images reconstructed with MBIR than in both the HD FBP images and the RD FBP images (P < 0.001). Compared with the RD FBP and HD FBP images, the CNRs of the metastatic lesion to the liver and the MPV to the liver were higher in the HD MBIR images (P < 0.001). Despite the presence of the unique whirling artifacts of the MBIR images, the HD MBIR images were of good to excellent quality and were not inferior to RD FBP images regarding the lesion conspicuity, the image quality, and the diagnostic acceptability (P > 0.05). Half-dose MBIR also showed less image noise, higher CNRs, and superior image quality compared with HD ASIR (P < 0.001). The HD MBIR images showed less noise, higher CNR, and better image quality than the HD ASIR and HD FBP images did; they also provided less image noise, higher CNR, and similar image quality compared with those of RD FBP images.

A retrospective comparison of smart prep and test bolus multi-detector CT pulmonary angiography protocols.

IntroductionOptimal arterial opacification is crucial in imaging the pulmonary arteries using computed tomography (CT). This poses the challenge of precisely timing data acquisition to coincide with the transit of the contrast bolus through the pulmonary vasculature. The aim of this quality assurance exercise was to investigate if a change in CT pulmonary angiography (CTPA) scanning protocol resulted in improved opacification of the pulmonary arteries. Comparison was made between the smart prep protocol (SPP) and the test bolus protocol (TBP) for opacification in the pulmonary trunk.MethodsA total of 160 CTPA examinations (80 using each protocol) performed between January 2010 and February 2011 were assessed retrospectively. CT attenuation coefficients were measured in Hounsfield Units (HU) using regions of interest at the level of the pulmonary trunk. The average pixel value, standard deviation (SD), maximum, and minimum were recorded. For each of these variables a mean value was then calculated and compared for these two CTPA protocols.ResultsMinimum opacification of 200 HU was achieved in 98% of the TBP sample but only 90% of the SPP sample. The average CT attenuation over the pulmonary trunk for the SPP was 329 (SD = ±21) HU, whereas for the TBP it was 396 (SD = ±22) HU (P = 0.0017). The TBP also recorded higher maximum (P = 0.0024) and minimum (P = 0.0039) levels of opacification.ConclusionThis study has found that a TBP resulted in significantly better opacification of the pulmonary trunk than the SPP.

Differentitation between Primary Central Nervous System Lymphoma and Glioblastoma: Added Value of Quantitative Analysis of CT Attenuation and Apparent Diffusion Coefficient

Purpose : Purpose of this study was to determine if quantitative measures of CT attenuation and ADC values in combination with conventional imaging features can differentiate primary central nervous system lymphoma (PCNSL) and glioblastoma (GBM). Materials and Methods: Twenty-six patients with histologically-proven GBM (14 men and 12 women; median age, 50 years; age range, 22 73 years) and 14 patients with PCNSL (11 men and 3 women; median age, 61 years; age range, 41 74 years) were enrolled. Maximum CT attenuation, minimum ADC, and lesion to normal parenchyma minimum ADC ratios were measured in solid tumor regions. Conventional imaging features were evaluated for the following: ill-defined margin, homogeneous enhancement pattern, degree of necrosis, extent of tumor involvement and multiplicity. The Mann-Whitney test was used to compare maximum CT attenuation and minimum ADC values for PCNSL and GBM. Fisher’s exact test was used to evaluate relationships between pathologic diagnoses and imaging features. Results: The CT attenuations were similar for PCNSL and GBM (37.84 ± 6.90 HU versus 37.00 ± 5.54 HU, p = 0.68), but minimum ADC and minimum ADC ratio were significant lower in PCNSL than in GBM (595.01 ± 228.28 10 mm/s versus 736.52 ± 162.05 10 mm/s; p = 0.028, 0.87 ± 0.26 versus 1.14 ± 0.29; p = 0.007). PCNSL showed greater homogeneous enhancement and smaller necrotic areas than GBM (p = 0.003 and p < 0.001, respectively) and was more likely to have multiple tumors than GBM (p = 0.039). When necrotic PCNSL (n = 4) and necrotic GBM (n = 24) were compared, minimum ADC and minimum ADC ratios were also significantly lower in PCNSL, but CT attenuation were not. Conclusion: Although CT attenuation does not provide valuable information, minimum ADC and minimum ADC ratio and some imaging features can aid the differentiation of PCNSL and GBM. Index words : Central Nervous System∙Lymphoma∙Glioblastoma∙Computed tomography (CT) Diffusion weighted imaging (DWI)

CT Tumor Volume Measurement in Advanced Non-small-cell Lung Cancer: Performance Characteristics of an Emerging Clinical Tool

Determine inter- and intraobserver variability of computed tomography (CT) tumor volume measurements in advanced non-small-cell lung cancer (NSCLC) patients treated in a Phase II clinical trial using chest CT. Twenty-three advanced NSCLC patients with a total of 53 measurable lung lesions enrolled in a Phase II, multicenter, open-label clinical trial of erlotinib were retrospectively studied with institutional review board approval. Two radiologists independently measured the tumor size, volume, and CT attenuation coefficient using commercially available volume analysis software. Concordance correlation coefficients (CCCs) and Bland-Altman plots were used to assess inter- and intraobserver agreement. High CCCs (0.949-0.990) were observed in all types of measurements for interobserver agreement. The 95% limits of agreements for volume, unidimensional, and bidimensional measurements were (-26.0%, 18.6%), (-23.1%, 24.4%), and (-34.0%, 48.6%), respectively. Volume measurement had slightly higher CCC and narrower 95% limits of agreement compared to uni- and bidimensional measurements. CCCs for intraobserver agreement were high (range, 0.946-0.996) with CCC for volume being slightly higher than CCCs of uni- and bidimensional measurements. The smaller the tumor volume was, the larger the interobserver difference of CT attenuation. Location, morphology, or adjacent atelectasis had no significant impact on inter- or intraobserver variability. CT tumor volume measurement in advanced NSCLC patients using clinical chest CT and commercially available software demonstrated high inter- and intraobserver agreement, indicating that the method may be used routinely in clinical practice.

Radiofrequency ablation as a treatment for hilar cholangiocarcinoma

To explore the role of radio-frequency ablation (RFA) as a treatment for hilar cholangiocarcinoma. Eleven patients with obstructive cholestasis underwent Computed Tomography (CT) examination, occupying lesions were observed in the hepatic hilar region in each patient. All lesions were confirmed as cholangioadenocarcinoma by biopsy and were classified as type III or IV by percutaneous transhepatic cholangiography. Patients were treated with multiple electrodes RFA combined with other adjuvant therapy. The survival rate, change of CT attenuation coefficient of the tumor and tumor size were studied in these patients after RFA. In a follow-up CT scan one month after RFA, a size reduction of about 30% was observed in six masses, and two masses were reduced by about 20% in size, three of the eleven masses remained unchanged. In a follow-up CT scan 6 mo after RFA, all the masses were reduced in size (overall 35%), in which the most significant size reduction was 60%. The survival follow-up among these eleven cases was 18 mo in average. Ongoing follow-up showed that the longest survival case was 30 mo and the shortest case was 10 mo. RFA is a microinvasive and effective treatment for hilar cholangiocarcinoma.

AAPM CT 성능 평가용 팬텀을 이용한 전산화단층촬영의 영상 평가를 위한 정도관리 사례 연구

전산화단층촬영(CT)은 영상의학에서 매우 유용한 검사의 진단법으로 적절한 정도관리에 의한 영상의 평가가 필요하다. CT의 정도관리 항목에서 영상의 질을 결정하는 중요한 요소를 위해 AAPM CT 팬텀으로 영상검사를 수행하였다. 정도관리 평가항목은 "특수의료장비의 설치 및 운영에 관한 규칙"에서 정한 기준으로 물의 CT 감약계수, 노이즈, 균일도, 공간분해능, 대조도 분해능, 절편 두께, 인공물 존재 유무를 평가하였다. 획득한 영상은 규칙의 합격기준에 충족하였다. CT 영상의 질을 최적으로 유지하기 위해서는 지속적으로 팬텀 및 임상검사를 통해 영상의 질을 평가하기 위해 정도관리를 시행하여야 한다. The increasing use of computed tomography (CT) as a diagnostic tool creates the need from and efficient means of evaluating the performance of the CT scanner now in use. Accordingly, acceptance testing and quality assurance of CT is of great importance. The aim of this study is to analyze of AAPM CT performance phantom in the CT accreditation program. The modular phantom offers the CT system with which to measure eight performance parameters. The parameters are listed of CT attenuation coefficient of water, noise, uniformity, spatial resolution, contrast resolution, slice thickness (5 and 10 mm), artifacts and alignment. The phantom evaluation was done by two radiologists. The acceptance testing protocol described here in demonstrates the successful of the guidelines for the quality assurance using AAPM CT performance phantom. We need to be upgraded for the CT image quality and make the standard reference of the quality assurance in the CT.

Computed tomographic evaluation of osmotica on shrinkage and recovery of lupin ( Lupinus angustifolius L.) and radish ( Raphanus sativus L.) roots

X-ray computed tomography (CT) may be a useful tool to evaluate in situ root response to environmental change. The effects of increasing strength of NaCl osmotic solution on the shrinkage and recovery of radish and lupin roots were examined using X-ray computed tomography (CT). The radish and lupin roots showed different patterns of response to osmotic treatments depending on the level of osmotic potential applied. For the highest osmotic potential treatment (−0.10 MPa), radish root cross-sectional areas decreased slightly (1.4%) while the lupin root cross-sectional area increased slightly (2.6%). For the lowest osmotic potential treatments (−2.0 MPa), radish roots shrank by 72.3% as compared to 54% for lupin roots. Recovery patterns of both roots were remarkably different. While radish roots exposed to the lowest osmotic treatment were able to recover all but 14% of their original volume after removal of osmotic treatments, lupin roots were fatally injured by this extreme treatment and died. The physical density of the radish and lupin roots, as reflected by X-ray CT attenuation coefficients, differed by a factor of 18. Differences in physical density reflected changes in root water content, extent and volume of Donnan free space as well as root composition. Furthermore, increases or decreases in CT Hounsfield unit values were associated with a parallel increase or decrease in root physical density which in turn reflects the direction of water movement. Data obtained in this study illustrate the dramatic variation in response in which different plant species can tolerate salinity and the usefulness of CT as a tool to study these effects.

Diagnostic Usefulness of CT Attenuation Coefficients of Urine after Enteral Administration of Iodinated Water (Iohexol) in Neonates with NEC

Purpose: We wanted to evaluate the clinical efficacy of an increased computed tomography attenuation coefficient (CTAC) of urine after the oral administration of iohexol in neonates who are suspected of suffering with neonatal necrotizing enterocolitis (NEC). Materials and Methods: During a recent 1 year-period, seventeen neonates were admitted for suspected NEC, and they were divided into the suspected and definite groups based on their clinical signs and radiographic findings; we also included ten normal neonates as the control group. Diluted iohexol was administered and the CTACs of collected urine samples at 8-12 hour intervals were measured. Comparative analysis of the three groups was done and statistical significance was determined by the Scheffe test. Results: Among 17 neonates, there were 13 neonates in the suspect group and 4 neonates in the definite group. The mean CTACs of urine in each group were 2711 HU (control group), 3411 HU (suspected group), and 7625 HU (definite group), respectively. There was a significant difference between the mean CTAC of the definite group and that of the control or suspected groups (Scheffe t >2.65). However, no statistically significant difference was seen between the suspected and control groups (Scheffe t=1.14). Conclusion: Although measurements of the CTAC of urine showed no significant diagnostic efficacy in the suspected group, the CTAC of urine, which reflects the correlated degree of bowel mucosal injury, can be a useful aid for determining the severity and progression of NEC.

Computed Tomography Features of an Intraductal Polypoid Mass

To determine the computed tomography (CT) features capable of differentiating hepatocellular carcinoma (HCC) with bile duct tumor invasion (BDTI) from intraductal cholangiocarcinoma (IDCC). Multiphasic CT images of 14 patients with HCC with BDTI and 18 patients with IDCC were retrospectively reviewed. Analysis of the CT findings included the size, location, and margin of the intraductal mass; enhancement pattern of intraductal lesions; degree of ductal dilatation; presence of downstream ductal dilatation and ductal wall thickening; presence of a parenchymal mass and its size; continuity of the parenchymal mass with the intraductal mass; and liver cirrhosis. Objective evaluation of the enhancement patterns of intraductal tumors was done by measuring the CT attenuation coefficients of the tumors and the uninvolved hepatic parenchyma in each phase. Among these findings, statistically significant variables were then determined using the Fisher's exact test or Mann-Whitney U test. Significant variables that helped to differentiate HCC with BDTI from IDCC included the presence of a parenchymal mass, liver cirrhosis, and a hyperattenuating intraductal tumor on the hepatic arterial phase (HAP). On unenhanced images, the tumor-to-liver contrast of IDCC (16.7+/-8.1) was greater than that of HCC with BDTI (6.4+/-10.4), but on the HAP, that of HCC with BDTI (26.5+/-28.2) was greater than that of IDCC (5.9+/-18.7) (P<0.05). In addition, there was a significant difference in the enhancement ratio of the intraductal tumors on the portal venous phase between the 2 conditions (P=0.003). Several objective and subjective multiphasic CT findings may help to differentiate HCC with BDTI from IDCC.

A validation study of a new software for computed tomography lung measurement

The use of computed tomography (CT) in the management of ALI/ARDS patients is quite common, due to the possible additional clinical information and the influence on the patient's treatment. With the new spiral CT scan it is possible to measure the total lung volume, the percentage of lung tissue and gas, there being a linear correlation between the physical density and the CT coefficient of attenuation. The aim of this study was to evaluate in vitro the new computer program 'Maluna' (University of Mannheim, Germany) dedicated to measuring the lung volume, weight and gas/tissue ratio. A series of different known volumes of water (100, 500, 1500 and 2000 ml) were studied. In addition, the contrast material was diluted with water to obtain solutions of increasing concentrations (0, 0.5, 1, 1.5, 2.5 and 5%). The spiral CT was performed at 120 KV and 240 mA. Each CT section was manually delineated by a physician. The total volume was computed as the total number of voxels present in a given region times the volume of the voxels, while the CT number was directly related to the physical density. Figure ​Figure11 shows the Bland–Altman analysis between the known volumes of water and the measured volumes by 'Maluna'; Fig. ​Fig.22 shows the linear regression between the CT attenuation coefficient with increasing concentrations of contrast material in the solution. These data show that 'Maluna' is able to correctly compute the volumes and CT number. Figure 1 Figure 2

Benign and malignant adrenal masses: CT distinction with attenuation coefficients, size, and observer analysis.

In a retrospective study of adrenal masses evaluated with computed tomography (CT), lesion x-ray attenuation was compared with size and radiologists' interpretations in discriminating benign lesions from malignant ones. Unenhanced CT attenuation coefficient and size were analyzed electronically in 55 patients with 66 adrenal masses. There were 38 nonhyperfunctioning adenomas in 33 patients and 28 malignant masses in 22 patients. Primary extraadrenal malignancies were present in 45 of the 55 patients. Three blinded readers characterized the adrenal masses using a seven-point scale of certainty. Results were subjected to receiver operating characteristic (ROC) analysis. The mean CT attenuation coefficient for benign adrenal masses was -2.2 HU +/- 16.0 and was significantly different from the mean for malignant lesions (28.9 HU +/- 10.6). The area under the ROC curve for CT attenuation coefficients (0.91 +/- 0.04) was significantly larger than that for lesion size (0.84 +/- 0.05) or best observer interpretation (0.84 +/- 0.05). A threshold CT attenuation value of 0 HU had a sensitivity-to-specificity ratio of 47%:100% for characterizing benign adrenal masses, whereas a threshold attenuation of 10 HU had a ratio of 79%:96%.