Liver stiffness measurement using acoustic radiation force impulse elastography in overweight and obese patients.

BACKGROUND: Obesity and overweight are global health problems. AIM: To evaluate the diagnostic accuracy of liver stiffness measurement (LSM) using acoustic radiation force impulse (ARFI) elastography in overweight and obese patients for staging liver fibrosis. METHODS: Ninety-seven patients (mean age: 50 years, 50% male) with body mass index (BMI) ≥25 kg/m(2) (mean BMI: 31 kg/m(2) ) were prospectively enrolled. All patients underwent ARFI elastography and liver biopsy. In 87/97 patients, transient elastography (TE) was performed (M- and XL-probes). Patients were divided into two groups respectively: overweight: BMI <30 kg/m(2) (n = 61); and obese: BMI ≥30 kg/m(2) (n = 26). RESULTS: Acoustic radiation force impulse elastography correlated with liver fibrosis in overweight (r = 0.84, P < 0.0001) and obese patients (r = 0.85, P < 0.0001), while no correlation was observed with steatosis, steatohepatitis and BMI. Area under the curve detecting liver cirrhosis for ARFI and TE were 0.97 in overweight and 0.94 and 0.92 in obese patients. In both groups, the failure rate was lower for ARFI than TE. ARFI of liver segment 8 showed a lower discordance than TE in both groups (overweight: 3% vs. 12%, P = 0.002; obese: 8% vs. 27%, P = 0.034). Steatosis and steatohepatitis were neither predictors of discordance nor of performance in LSM by ARFI or TE in both groups. CONCLUSIONS: In overweight and obese patients, acoustic radiation force impulse can diagnose liver cirrhosis and significant fibrosis with high diagnostic accuracy. Liver stiffness measurement using the XL-probe reduces the influence of BMI, steatosis and steatohepatitis. The failure and discordance rates were lower for acoustic radiation force impulse than transient elastography in both patients groups.

Evaluation of Liver and Spleen Stiffness with Acoustic Radiation Force Impulse Quantification Elastography for Diagnosing Clinically Significant Portal Hypertension.

PURPOSE: Hepatic vein pressure gradient (HVPG) is the gold standard for diagnosing clinically significant portal hypertension (CSPH). The aim of this study was to investigate-in comparison to HVPG-the ability to diagnose CSPH by liver and spleen stiffness measurements obtained by acoustic radiation force impulse (ARFI) imaging. MATERIALS AND METHODS: A total of 78 patients (mean age: 53 ±â€Š13 years, 62 % male) with chronic liver disease were enrolled in this study. Each patient received liver (LSM) and spleen (SSM) stiffness measurements by ARFI, an HVPG measurement and a transjugular liver biopsy on the same day. Patients were classified according to their HVPG into three different groups: HVPG < 10 mmHg, HVPG ≥ 10-< 12 mmHg and HVPG ≥ 12 mmHg. RESULTS: LSM, SSM were significantly higher in patients with HVPG ≥ 10 - < 12 in comparison to HVPG < 10 mmHg (p < 0.001 and p < 0.001, respectively), and in patients with HVPG ≥ 12 mmHg in comparison to ≥ 10 - < 12 mmHg (p < 0.001 and p < 0.001, respectively). LSM and SSM were able to diagnose HVPG ≥ 10 mmHg and HVPG ≥ 12 mmHg with high diagnostic performance (AUC LSM: 0.93 and 0.87, respectively; AUC SSM: 0.97 and 0.95, respectively). The AUC of SSM in predicting esophageal varices (EVs) plus HVPG ≥ 10 mmHg and EVs plus HVPG ≥ 12 mmHg were higher compared to LSM in both groups of patients (SSM: 0.90 and 0.93 vs. LSM: 0.84 and 0.88, respectively). No significant difference between both AUCs was detected in the different HVPG groups. In the multivariate -analysis SSM remained a factor predicting HVPG (HVPG > 10 mmHg p = 0.007; HVPG ≥ 12 mmHg p = 0.003). CONCLUSION: LSM and SSM by ARFI are noninvasive diagnostic tools that may help in diagnosing CSPH. LSM and SSM could be used as a guiding noninvasive screening tool in patients with esophageal varices requiring endoscopic evaluation.

xPIPE--Reception of DICOM Data from any Sender via the Internet.

PURPOSE: Various technologies have been established for DICOM data exchange in radiology. In addition to the patient CD, online transfers via VPN (virtual private network) or DICOM email are common practice. However, dedicated network solutions are generally not appropriate for data exchange with occasional and spontaneous partners due to missing infrastructure at the partner institutions and/or complex setup procedures. The purpose was to develop a practical solution to complement the established technologies to allow users worldwide to transfer images without registration. MATERIALS AND METHODS: The development of the xPIPE system is based on Java and various software libraries. A client hosted on a website enables sending DICOM data to a receiving system of the hospital. RESULTS: The new xPIPE system creates a gateway to a receiving hospital which is accessible from any point worldwide, giving other hospitals, clinics and patients a simple and secure method to transmit DICOM data without intermediate storage on external servers. CONCLUSION: The system was deployed at the University Hospital Münster and subsequently widely used even without information events and training. Data protection during transfer is ensured by the use of signatures and encryption. From the user's perspective the system has only minor technical requirements and can be used with minimal setup effort.

Relationship between detector size and the need for extra images and their effect on radiation exposure in digital mammography screening.

PURPOSE: To determine the number of extra images (EI) that are necessary for imaging large breasts when using a detector smaller than 24 cm × 30 cm and to calculate the additional average glandular dose (AGD) for these images. MATERIALS AND METHODS: The screening mammograms taken between 2007 and 2011 were assessed for a photon counting full-field digital mammography (PCM) system (detector size: 24 cm × 26 cm) and a computed radiography (CR) system (24 cm × 30 cm). The number of EI was recorded and the AGD calculated. This AGD was compared with the mean AGD of 47 conventional full-field digital mammography (FFDM) systems. RESULTS: A total of 62,466 examinations were analyzed. EI had to be taken in 0.6 % (199/32,766) of all PCM examinations and 0.3 % (90/29 700) of all CR examinations. This corresponded to a total of 327 and 191 EI for the PCM and CR systems, respectively. More than one quarter of the examinations with EI were necessary because the breast was not properly positioned in the original image (PCM 31 %, CR 29 %). The mean AGD per EI was 0.7 ±â€¯0.1 mGy for the PCM and 2.6 ±â€¯1.2 mGy for the CR system. The mean AGD for all breast thicknesses for FFDM was 1.4 ±â€¯0.3 mGy. CONCLUSION: In general, large breasts cannot be imaged with just one image per view. The number of examinations where EI are needed is doubled with the 24 cm × 26 cm detector of the PCM system. However, the absolute number is small. The total dose, as the sum of the original and the EI, is equal to the mean AGD of a single image of the FFDM systems and lower than the dose of a single image with the CR system.

[Central online quality assurance in radiology: an IT solution exemplified by the German Breast Cancer Screening Program]. / Zentrale Online-Qualitätssicherung in der Radiologie:eine IT-Lösung am Beispiel des deutschenMammografie-Screening-Programms.

PURPOSE: Physical-technical quality assurance is one of the essential tasks of the National Reference Centers in the German Breast Cancer Screening Program. For this purpose the mammography units are required to transfer the measured values of the constancy tests on a daily basis and all phantom images created for this purpose on a weekly basis to the reference centers. This is a serious logistical challenge. To meet these requirements, we developed an innovative software tool. MATERIALS AND METHODS: By the end of 2005, we had already developed web-based software (MammoControl) allowing the transmission of constancy test results via entry forms. For automatic analysis and transmission of the phantom images, we then introduced an extension (MammoControl DIANA). This was based on Java, Java Web Start, the NetBeans Rich Client Platform, the Pixelmed Java DICOM Toolkit and the ImageJ library. RESULTS: MammoControl DIANA was designed to run locally in the mammography units. This allows automated on-site image analysis. Both results and compressed images can then be transmitted to the reference center. We developed analysis modules for the daily and monthly consistency tests and additionally for a homogeneity test. CONCLUSION: The software we developed facilitates the immediate availability of measurement results, phantom images, and DICOM header data in all reference centers. This allows both targeted guidance and short response time in the case of errors. We achieved a consistent IT-based evaluation with standardized tools for the entire screening program in Germany.

[Devolvement of an objective rating system for the annual physical quality control for digital mammography systems]. / Entwicklung eines objektiven Bewertungssystems für die jährliche physikalische Qualitätssicherung an digitalen Mammografie-Systemen.

PURPOSE: For the non-subjective evaluation of physical-technical defects of digital mammography systems within the German breast screening program, an automatic rating system (RS) on the basis of the annual quality control (AQC) was developed. The aim was to design a modular algorithm which could also be adjusted for other test procedures. MATERIALS AND METHODS: This algorithm enables the separate evaluation of different test parts of the AQC (PAS 1054 and EPQC). To take into account the value of different test positions (TP) in these two parts, a weighting scheme was used. This scheme relates to the scope of different TP as well as variability through different types of systems. For the creation of the final result, both scores of the different test parts must be merged together. The final result is divided into 4 categories. EVALUATION: The evaluation of the RS was based on the AQC. Here, the tester of the system was asked to classify the system in one of the 4 categories on the basis of his expert knowledge. In 78 % of the cases, the results of the tester were reproduced by the automatic RS, in 17 % the RS was more stringent and in 5 % the tester was more stringent. CONCLUSION: The RS allows non-subjective physical-technical evaluation of mammography systems. It acts as a good guide for the tester but is not a replacement for experience. In addition, the RS makes the results of different institutions and testers more comparable. The modular algorithm of the RS is able to react to future changes in the different test parts and can be modified for other X-ray modalities.

[Guideline for the additional test positions according to the EPQC 4th Edition for Digital Mammography Systems]. / Prüfanleitung für die Durchführung der ergänzenden Prüfpositionen nach EPQC 4th Edition für digitale Mammografie-Systeme.

Within the physical-technical quality assurance of the German breast cancer screening program all digital mammography systems have to perform the contrast resolution test and the determination of the average glandular dose based on the European guidelines for quality assurance in breast cancer screening and diagnosis (4th Edition). Since 1.1.2009 this applies to digital systems outside the screening program too. To accomplish uniform measurements in all federal states of Germany, the physical board of the reference centers developed together a special guideline for these test position. This Guideline describes the determination of the average glandular dose for different types of mammography systems, the CDMAM image acquisition and the CDMAM image evaluation as well. This guideline was verified by the German task group "Röntgenverordnung".

[Physical and technical quality assurance in German breast cancer screening: progress report of the Reference Center Muenster after three years]. / Physikalisch-technische Qualitätssicherung im deutschen Mammografie-Screening-Programm: Erfahrungsbericht des Referenzzentrums Münster nach drei Jahren.

PURPOSE: German breast cancer screening is monitored by a large physical quality assurance program. This report refers to the first experiences of the Reference Center (RC) Muenster after three years of the technical quality control of digital and analog mammography units (MU). This paper also shows whether the presently used quality assurance (QA) method is able to ensure that the MUs in the screening program are functioning without any serious problems. MATERIALS AND METHODS: RC Muenster supervises 95 units (May 2008). The daily, weekly and monthly quality assurance of these units is controlled by web-based QA software named "MammoConrol" and developed by RC Muenster. The annual QA for the units must be conducted in the form of an on-site inspection by medical physics experts of the RC and is scored by an objective ranking system. The results of these QA routines were evaluated and analyzed for this paper. RESULTS: During the period from 3/1/2006 to 5/31/2008, 8 % of the analog systems and 1 % of the digital systems exhibited problems in the daily QA. For 9 % of the analog MUs and 17 % of the digital MUs, failures appeared in the monthly QA. In the annual control, 86.7 % of the analog units exhibited slight problems and 13.3 % had serious problems. With respect to the digital units, 12 % were without any defects, 58 % had slight problems, 27 % had serious failures and 3 % had to be reported to the responsible authorities and were temporarily shut down. CONCLUSION: The special quality control requirements for German breast cancer screening, including annual on-site checks of the units, have shown in the last three years that QA with a high monitoring standard can be ensured for a large number of decentralized MUs. The currently used QA method sufficiently ensures that the screening program is technically safe. Further studies must show whether the density and focus of the QA measures must be reconfigured.

[Comments on the standards for acceptance and consistency testing of systems for digital radiography]. / Kommentierungen zu den Normen zu Abnahme- und Konstanzprüfungen bei digitalen Radiographiesystemen (Projektionsradiographie).

Due to German regulations, acceptance and consistency tests have to be obtained by 12.31.2005 for all equipment used for computed radiography according to special standards published in DIN 6868. This article familiarizes all users with the most important aspects of these standards. In addition, explanatory and background information for establishing these regulations are provided.

[Painless jaundice after holidays in Tanzania]. / Schmerzloser Ikterus nach Urlaub in Tansania.

The side effects caused by malaria prophylaxis with mefloquine (Lariam) are well known. We describe the case of a 42-year-old female Caucasian patient suffering from painless jaundice and showing elevated liver, cholestasis and inflammation laboratory findings 7 days after returning from Tanzania. Acute cholecystitis was diagnosed by ultrasound. Treatment with parenteral nutrition and antibiotic therapy did not show any beneficial effect. Excluding the possibility of infectious diseases, the elevated laboratory and ultrasound findings were normalized after the discontinuation of the malaria prophylaxis.

[Selenium-based digital radiography of the cervical spine: comparison with screen-film radiography for the depiction of anatomic details]. / Digitale Selenradiographie der HWS: Vergleich mit der konventionellen Film-Folien-Radiographie bezüglich der Erkennbarkeit anatomischer Details.

PURPOSE: To compare selenium-based digital radiography with conventional screen-film radiography of the cervical spine. MATERIALS AND METHODS: In a prospective study X-ray images of the cervical spine were obtained in 25 patients using selenium- based digital radiography and conventional screen-film radiography. All images were clinically indicated. Selenium-based digital radiography and conventional screen-film radiography were used in a randomized order. Four radiologists independently evaluated all 50 examinations for the visibility of 76 anatomic details according to a five-level confidence scale (1 = not visible, 5 = very good visibility). From the evaluation of these anatomic details scores for the upper and middle cervical spine, the cervicothoracic junction and the cervical soft tissues were calculated. The scores for selenium-based digital radiography and conventional screen-film radiography were compared using Wilcoxon's signed rank test. RESULTS: From a total of 15,200 observations (608 per patient) the following scores were calculated for selenium-based digital radiography and for screen-film radiography, respectively: Upper cervical spine 3.88 and 3.94; middle cervical spine 4.60 and 4.48; cervico-thoracic junction 3.64 and 2.62; cervical soft tissue 4.47 and 3.46. The differences between the last two scores were statistically significant (p < 0.05). CONCLUSION: The use of selenium-based digital radiography is superior to conventional screen-film radiography in the depiction of anatomic details of the cervicothoracic junction and the cervical soft tissues.

Abdominal spiral CT in children: which radiation exposure is required?

We decided to test to what extent dose reduction is possible in abdominal spiral computed tomography (CT) in young children without loss of anatomic diagnostic information. A retrospective study was performed of 30 abdominal CT examinations of children aged 3 months to 7 years. These were divided into two groups: group A with reduced radiation exposure (tube current 50 mA, CT dose index CTDIFDA < or =0.83 mGy) and group B with standard radiation exposure (tube current > or =100 mA, CTDIFDA > or =1.66 mGy). Image quality was assessed using a four-part scale ('excellent', 'good', 'sufficient', 'poor') on visual image impression and visibility of 32 anatomical details. Five experienced radiologists read the CT scans independently who were blinded to the examination parameters. Differences in ranked data were evaluated with Wilcoxon's rank sum test. No difference between groups A and B was observed in visual image impression. Detail visibility was significantly lower in group A, but the differences were limited to right upper quadrant structures (portal vein, common bile duct, pancreatic head, adrenals) and to arterial branches. Significant differences in visibility rated as 'poor' were only found for the hepatic, splenic and renal arteries; all other structures showed no difference between groups A and B. A protocol with reduced radiation exposure (50 mA, CTDIFDA < or =0.83 mGy) allowed the demonstration of most anatomic structures in abdominal spiral CT in young children. For the precise demonstration of small details (e.g. structures of the right upper quadrant), a protocol with standard radiation exposure (> or =100 mAs) was superior.

[Multi-slice spiral CT of the abdomen in oncological patients: influence of table support and detector configuration on image quality and radiation exposure]. / Mehrschicht-Spiral-CT des Abdomens bei onkologischen Patienten: Einfluss von Tischvorschub und Detektorkonfiguration auf Bildqualität und Strahlenexposition.

PURPOSE: To evaluate the image quality and radiation exposure of different spiral CT scanning parameters for routine staging examination of the abdomen in oncologic patients using a multi-slice CT scanner. METHODS/MATERIALS: Examination of 40 patients in 4 groups on a multi-slice CT scanner (Somatom VolumeZoom, Siemens AG, Forchheim). Functional detector width (4 x 2.5, 4 x 5 mm) and pitch (table feed in relation to collimated slice width) were varied (3 and 5). Tube voltage (120 kV), effective tube current (160 mAs), slice-thickness (6 mm), increment (4 mm), kernel (B 30), and contrast injection parameters were kept constant. Axial images were assessed by three radiologists regarding delineation of anatomic structures, artifacts, and overall image quality. RESULTS: Significantly reduced image quality especially due to artifacts was observed using a 5 mm detector configuration with a pitch of 5 (scan time 9 sec). Image quality was rated best for a 2.5 mm detector configuration with a pitch of 3 and a scan time of 28 sec. The effective dose was independent of the pitch. However, the mean effective dose was 9% higher using the smaller detector configuration (9.9 mSv vs 10.9 mSv). CONCLUSIONS: For routine staging CT of the abdomen use of a 4 x 2.5 mm detector configuration with a pitch between 3 and 5 is recommended. A 4 x 5 mm detector configuration using overlapping data acquisition can also be recommended, but additional thin slice reformations are not possible.

Selenium-based digital radiography in the detection of bone lesions: preliminary experience with experimentally created defects.

PURPOSE: To compare the diagnostic performance of selenium-based digital radiography with that of conventional screen-film radiography and storage phosphor radiography for the detection of bone lesions simulating osteolyses. MATERIALS AND METHODS: Artificial osseous lesions 1.0-3.0 mm in diameter were created in 80 of 160 predefined regions in 16 porcine femoral specimens. Specimens were enclosed in containers filled with paraffin to ensure accurate repositioning and to obtain an absorption condition comparable to that of a human extremity. Imaging was performed with a selenium-based digital radiography system, a conventional screen-film system, and a storage phosphor radiography system with an exposure identical to that used during clinical imaging. The presence of a lesion was assessed with a five-point confidence scale. Receiver operating characteristic (ROC) analysis was performed for a total of 1,440 observations (480 per modality), and diagnostic performance was estimated with the area under the ROC curve (A(z)). Differences in diagnostic performance were assessed with the paired Student t test. RESULTS: ROC analysis results showed A(z) values of 0.656 for selenium-based digital radiography, 0.679 for storage phosphor radiography, and 0.680 for conventional screen-film radiography. Differences between the three modalities were not significant (P =.60-.93). CONCLUSION: Image quality with selenium-based digital radiography was comparable to that with conventional screen-film radiography and storage phosphor radiography.

LDL cholesterol upregulates synthesis of asymmetrical dimethylarginine in human endothelial cells: involvement of S-adenosylmethionine-dependent methyltransferases.

Asymmetrical dimethylarginine (ADMA) is an endogenous nitric oxide synthase inhibitor. It is formed by protein arginine N-methyltransferases (PRMTs), which utilize S-adenosylmethionine as methyl group donor. ADMA plasma concentration is elevated in hypercholesterolemia, leading to endothelial dysfunction and producing proatherogenic changes of endothelial cell function. Four different isoforms of human PRMTs have been identified. Because the release of ADMA from human endothelial cells is increased in the presence of native or oxidized LDL cholesterol, we investigated the potential involvement of PRMT activity and gene expression in this effect. We found that the production of ADMA by human endothelial cells is upregulated in the presence of methionine or homocysteine and inhibited by either of the methyltransferase inhibitors S-adenosylhomocysteine, adenosine dialdehyde, or cycloleucine. This effect is specific for ADMA but not symmetrical dimethylarginine. The upregulation of ADMA release by native and oxidized LDL is abolished by S-adenosylhomocysteine and by the antioxidant pyrrollidine dithiocarbamate. Furthermore, a methyl-(14)C label is transferred from S-adenosylmethionine to ADMA but not symmetrical dimethylarginine, in human endothelial cells. The expression of PRMTs is upregulated in the presence of native or oxidized LDL. Our data suggest that the production of ADMA by human endothelial cells is regulated by S-adenosylmethionine-dependent methyltransferases. This activity is upregulated by LDL cholesterol, which may be due in part to the enhanced gene expression of PRMTs. In concentrations reached by stimulation of methyltransferases (5 to 50 micromol/L), ADMA significantly inhibited the formation of (15)N-nitrite from L-[guanidino-(15)N(2)]arginine. These findings suggest a novel mechanism by which ADMA concentration is elevated in hypercholesterolemia, leading to endothelial dysfunction and atherosclerosis.

Radiation exposure associated with imaging of the chest: comparison of different radiographic and computed tomography techniques.

Exposure to ionizing radiation due to radiologic examinations is associated with the risk of induction of malignancy. This has to be balanced against the potential benefits of detection of a malignant tumor with radiologic examinations. For comparison of radiation exposure levels from different sources, the concept of effective dose equivalent was developed, which is used to assess an individual's risk of developing malignancy. Effective dose equivalent ranges from 0.06 to 0.25 millisieverts (mSv) with chest radiography in 2 views, 3-27 mSv with computed tomography (CT) using conventional examination parameters, and 0.3-0.55 mSv using low dose CT settings. These values can be compared with radiation exposure levels from natural sources (on average 2.4 mSv per year in Germany). Based on considerations by the International Commission on Radiological Protection, it can be expected that radiation exposure with an effective dose equivalent of 1 mSv would lead to 5 additional malignancies in 100,000 individuals exposed.

Screening for asymptomatic early bronchogenic carcinoma with low dose CT of the chest.

BACKGROUND: Survival of patients with lung carcinoma is very poor, particularly for patients with advanced disease. There are no early clinical symptoms, and screening with chest radiography has not been recommended. Computed tomography (CT) is superior to radiography for detection of pulmonary nodules but usually is associated with relatively high radiation exposure. Recently, accuracy of low dose CT has been shown to be similar to conventional dose CT. The goal of the current study was to assess the findings of low dose CT of the chest in heavy smokers. METHODS: More than 700 heavy smokers (> 20 pack years; age: > 40 years) underwent unenhanced low dose CT of the chest. Detected nodules were classified according to their density (soft tissue, calcified, fat) and size (< 6 mm, 6-10 mm, > 10 mm). In nodules larger than 10 mm with no CT features to suggest a benign lesion, histology was obtained. RESULTS: In approximately 40% of smokers, nodules smaller than or equal to 10 mm were detected. None was resected. In less than 3% of individuals, lesions larger than 10 mm were detected; 8 were bronchogenic carcinoma. All eight carcinomas were resectable. Lesions for which no histology was obtained were followed with low dose CT. CONCLUSIONS: Low dose CT detected 8 bronchogenic carcinomas in more than 700 heavy smokers. All eight were resectable. Pulmonary nodules measuring up to 10 mm were found in 40% of smokers. The significance of these small lesions has remained unclear.

Pulmonary nodules: experimental and clinical studies at low-dose CT.

PURPOSE: To compare the number of pulmonary nodules detected at helical low- and standard-dose computed tomography (CT) and to investigate the diagnostic value of low-dose CT with a radiation exposure equivalent to that used at chest radiography. MATERIALS AND METHODS: Two radiologists recorded pulmonary nodules at standard-dose (250 or 100 mA, pitch of 1; 200 mA, pitch of 2) or low-dose CT (50 or 25 mA, pitch of 1 or 2) in five postmortem specimens and 75 patients. Nodules were assessed by size (5 mm or smaller, 6-10 mm, or larger than 10 mm) and by diagnostic confidence ("definite nodule," "definite lesion, not classic nodule," or "questionable lesion, possibly representing a vessel") with the Wilcoxon signed rank test. Artifacts depicted at low-dose CT were recorded. RESULTS: There were no statistically significant differences in the number of nodules detected at standard- or low-dose CT except in nodules 5 mm or smaller that were assessed as definite nodules at standard- or low-dose CT (25 mA, pitch of 2) (472 vs 397, P < .05). Artifacts that possibly interfered with nodule detection were observed exclusively at CT with 25 mA and a pitch of 2. CONCLUSION: Pulmonary nodules were detected reliably at CT with 50 mA and pitch of 2 or with 25 mA and a pitch of 1. However, further reduction of the dose to that used at chest radiography was associated with a significant decrease in the number of nodules 5 mm or smaller that were detected, possibly due to artifacts.

[The texture-analysis of high-resolution computed tomograms as an additional procedure in osteoporosis diagnosis: in-vitro studies on vertebral segments]. / Strukturanalyse hochauflösender Computertomogramme als ergänzendes Verfahren in der Osteoporosediagnostik: in-vitro-Untersuchungen an Wirbelsäulensegmenten.

PURPOSE: The purpose of this study was to perform texture analysis of high-resolution CT images obtained from human vertebral specimens and to correlate these parameters with the biomechanical stability of the specimens. In addition, structure data were compared with bone mineral density (BMD) assessed by quantitative CT (QCT). MATERIAL AND METHODS: High-resolution CT images and standard QCT sections were obtained in 36 vertebral motion segments, each consisting of two vertebrae with intact ligaments and intervertebral disc. The trabecular structure in the CT images was assessed using three texture analysis techniques: Trabecular threshold area ratio (TTAR), fractal dimension without thresholding (OTS) and fractal dimension with thresholding (ITS). Finally, the maximum compressive strength (MCS) was determined using a biomechanical testing device. RESULTS: A correlation of r = 0.76 (p < 0.01) was obtained for TTAR versus MCS, of r = 0.83 (p < 0.01) for ITS versus MCS, and of r = 0.35 (p > 0.01) for OTS versus MCS, while r = 0.76 (p < 0.01) was found for BMD versus MCS. Best results were obtained by combining structure measures and BMD (r = 0.85, p < 0.01). CONCLUSIONS: This in vitro study showed a significant correlation between structure measures and biomechanical strength, which was comparable to BMD and strength. However, best correlations were obtained by combining both measures. Using both BMD and structure measures therefore may improve the prediction of biomechanically determined bone strength.