Associations of Texture Features of Proton Density Fat Fraction Maps between Lumbar Vertebral Bone Marrow and Paraspinal Musculature

Chemical shift encoding-based water−fat MRI (CSE-MRI)-derived proton density fat fraction (PDFF) has been used for non-invasive assessment of regional body fat distributions. More recently, texture analysis (TA) has been proposed to reveal even more detailed information about the vertebral or muscular composition beyond PDFF. The aim of this study was to investigate associations between vertebral bone marrow and paraspinal muscle texture features derived from CSE-MRI-based PDFF maps in a cohort of healthy subjects. In this study, 44 healthy subjects (13 males, 55 ± 30 years; 31 females, 39 ± 17 years) underwent 3T MRI including a six-echo three-dimensional (3D) spoiled gradient echo sequence used for CSE-MRI at the lumbar spine and the paraspinal musculature. The erector spinae muscles (ES), the psoas muscles (PS), and the vertebral bodies L1-4 (LS) were manually segmented. Mean PDFF values and texture features were extracted for each compartment. Features were compared between males and females using logistic regression analysis adjusted for age and body mass index (BMI). All texture features of ES except for Sum Average were significantly (p < 0.05) different between men and women. The three global texture features (Variance, Skewness, Kurtosis) for PS as well as LS showed a significant difference between male and female subjects (p < 0.05). Mean PDFF measured in PS and ES was significantly higher in females, but no difference was found for the vertebral bone marrow’s PDFF. Partial correlation analysis between the texture features of the spine and the paraspinal muscles revealed a highly significant correlation for Variance(global) (r = 0.61 for ES, r = 0.62 for PS; p < 0.001 respectively). Texture analysis using PDFF maps based on CSE-MRI revealed differences between healthy male and female subjects. Global texture features in the lumbar vertebral bone marrow allowed for differentiation between men and women, when the overall PDFF was not significantly different, indicating that PDFF maps may contain detailed and subtle textural information beyond fat fraction. The observed significant correlation of Variance(global) suggests a metabolic interrelationship between vertebral bone marrow and the paraspinal muscles.

Association Between Adipose Tissue Proton Density Fat Fraction, Resting Metabolic Rate and FTO Genotype in Humans

BACKGROUND

The difference of proton density fat fraction (PDFF) between supraclavicular and gluteal adipose tissue might indicate the presence of brown adipose tissue (BAT). Aim of this cross-sectional study was to investigate the association between PDFF over the supraclavicular fat region as a proxy of BAT proportion and resting metabolic rate (RMR). In addition, the association between the single nucleotide polymorphism (SNP) rs1421085 at the fat mass and obesity associated (FTO) gene locus and both PDFF and RMR was investigated.

METHODS

Anthropometric, clinical, and lifestyle data from 92 healthy adults (66.3% females, mean age: 36.2 ± 13.0 years, mean body mass index: 24.9 ± 5.4 kg/m²) were included in the analysis. The RMR was measured by indirect calorimetry. The magnetic resonance imaging (MRI) was used for the measurement of visceral and subcutaneous adipose tissue (VAT, SAT) volumes and for the measurement of adipose tissue PDFF.

RESULTS

Mean RMR of the whole group was 1 474.8 ± 242.2 kcal. Genotype data was available for 90 participants. After adjustment for age, sex, weight change and fat-free mass (FFM), no association was found between supraclavicular PDFF (p = 0.346) and gluteal PDFF (p = 0.252), respectively, and RMR, whereas statistically significant evidence for a negative association between delta PDFF (difference between gluteal PDFF and supraclavicular PDFF) and RMR (p = 0.027) was obtained. No statistically significant evidence was observed for per FTO risk allele change in RMR, gluteal and supraclavicular PDFF maps or volumes of VAT and SAT.

CONCLUSIONS

Supraclavicular PDFF as a surrogate marker of BAT presence is not a determinant of RMR under basal conditions. In the present study, the FTO rs1421085 variant is not associated with either RMR or PDFF. Further studies are needed to elucidate the effect of BAT on RMR.

Postmenopausal Chinese-Singaporean Women Have a Higher Ratio of Visceral to Subcutaneous Adipose Tissue Volume than Caucasian Women of the Same Age and BMI

Central fat accumulation is a significant determinant of cardio-metabolic health risk, known to differ between ethnically distinct human populations. Despite evidence for preferential central adiposity in Asian populations, the proportional distribution between the subcutaneous and visceral compartments in Chinese postmenopausal women has not been thoroughly investigated. For this analysis, volumetrically quantified subcutaneous and visceral adipose tissue (SAT, VAT) in the pelvic and abdominal regions of postmenopausal Asian (Chinese-Singaporean) and Caucasian (German) women matched for age and Body Mass Index (BMI) was undertaken, to examine such differences between the two groups. Volumes were calculated from segmentations of magnetic resonance imaging datasets of the abdomen and pelvis. Despite SAT, VAT, and the corresponding total adipose tissue (TAT) being similar between the groups, VAT/SAT and VAT/TAT were higher in the Asian group (by 24.5% and 18.2%, respectively, each p = 0.02). Further, VAT/SAT and VAT/TAT were positively correlated with BMI in the Caucasian group only (p = 0.02 and p = 0.01, respectively). We concluded that VAT is proportionally higher in the non-obese Asian women, compared to the Caucasian women of matched age and BMI. This conclusion is in agreement with existing literature showing higher abdominal adiposity in Asian populations. Additionally, in the Asian group, BMI did not correlate with visceral adiposity on a significant level. Further analysis is required to examine the extent to which this increased VAT may impact cardio-metabolic health. There is, however, a need to emphasize healthy lifestyle behaviors in non-obese post-menopausal women of Chinese ancestry.

Association of Cervical and Lumbar Paraspinal Muscle Composition Using Texture Analysis of MR-Based Proton Density Fat Fraction Maps

In this study, the associations of cervical and lumbar paraspinal musculature based on a texture analysis of proton density fat fraction (PDFF) maps were investigated to identify gender- and anatomical location-specific structural patterns. Seventy-nine volunteers (25 men, 54 women) participated in the present study (mean age ± standard deviation: men: 43.7 ± 24.6 years; women: 37.1 ± 14.0 years). Using manual segmentations of the PDFF maps, texture analysis was performed and texture features were extracted. A significant difference in the mean PDFF between men and women was observed in the erector spinae muscle (p < 0.0001), whereas the mean PDFF did not significantly differ in the cervical musculature and the psoas muscle (p > 0.05 each). Among others, Variance(global) and Kurtosis(global) showed significantly higher values in men than in women in all included muscle groups (p < 0.001). Not only the mean PDFF values (p < 0.001) but also Variance(global) (p < 0.001), Energy (p < 0.001), Entropy (p = 0.01), Homogeneity (p < 0.001), and Correlation (p = 0.037) differed significantly between the three muscle compartments. The cervical and lumbar paraspinal musculature composition seems to be gender-specific and has anatomical location-specific structural patterns.

Imaging modalities for diagnosis and monitoring of cancer cachexia

Cachexia, a multifactorial wasting syndrome, is highly prevalent among advanced-stage cancer patients. Unlike weight loss in healthy humans, the progressive loss of body weight in cancer cachexia primarily implicates lean body mass, caused by an aberrant metabolism and systemic inflammation. This may lead to disease aggravation, poorer quality of life, and increased mortality. Timely detection is, therefore, crucial, as is the careful monitoring of cancer progression, in an effort to improve management, facilitate individual treatment and minimize disease complications. A detailed analysis of body composition and tissue changes using imaging modalities—that is, computed tomography, magnetic resonance imaging, (¹⁸F) fluoro-2-deoxy-d-glucose (¹⁸FDG) PET and dual-energy X-ray absorptiometry—shows great premise for charting the course of cachexia. Quantitative and qualitative changes to adipose tissue, organs, and muscle compartments, particularly of the trunk and extremities, could present important biomarkers for phenotyping cachexia and determining its onset in patients. In this review, we present and compare the imaging techniques that have been used in the setting of cancer cachexia. Their individual limitations, drawbacks in the face of clinical routine care, and relevance in oncology are also discussed.

Ultrasound-based evaluation revealed reliable postoperative knee stability after combined acute ACL and MCL injuries

Purpose

Anterior cruciate ligament (ACL) injuries are often combined with lesions of the medial collateral ligament (MCL). The aim of this study was to evaluate treatment outcome of combined acute ACL and MCL lesions using functional US and clinical examination.

Methods

Patients aged > 18 years undergoing primary ACL reconstruction with concomitant operative (group 1) or non-operative treatment of the MCL (group 2) between 2014 and 2019 were included after a minimum follow-up of 12 months. Grade II MCL injuries with dislocated tibial or femoral avulsions and grade III MCL ruptures underwent ligament repair whereas grade II injuries without dislocated avulsions were treated non-operatively. Radiological outcome was assessed with functional US examinations. Medial knee joint width was determined in a supine position at 0° and 30° of knee flexion in unloaded and standardized loaded (= 15 Dekanewton) conditions using a fixation device. Clinical examination was performed and patient-reported outcomes were assessed by the use of the subjective knee form (IKDC), Lysholm score, and the Tegner activity scale.

Results

A total of 40 patients (20 per group) met inclusion criteria. Mean age of group 1 was 40 ± 12 years (60% female) with a mean follow-up of 33 ± 17 months. Group 2 showed a mean age of 33 ± 8 years (20% female) with a mean follow-up of 34 ± 15 months. Side-to-side differences in US examinations were 0.4 ± 1.5 mm (mm) in 0° and 0.4 ± 1.5 mm in 30° knee flexion in group 1, and 0.9 ± 1.1 mm in 0° and 0.5 ± 1.4 mm in 30° knee flexion in group 2, with no statistically significant differences between both groups. MCL repair resulted in lower Lysholm scores (75 ± 19 versus 86 ± 15; p < 0.05). No significant differences could be found for subjective IKDC or Tegner activity scores among the two groups.

Conclusion

A differentiated treatment concept in combined ACL and MCL injuries based on injury patterns leads to reliable postoperative ligamentous knee stability in US-based and clinical examinations. However, grade II and III MCL lesions with subsequent operative MCL repair (group 1) result in slightly poorer subjective outcome scores.

Level of evidence

Retrospective cohort study; Level III

MRI-Determined Psoas Muscle Fat Infiltration Correlates with Severity of Weight Loss during Cancer Cachexia

PURPOSE

To evaluate the suitability of psoas and erector spinae muscle proton density fat fraction (PDFF) and fat volume as biomarkers for monitoring cachexia severity in an oncological cohort, and to evaluate regional variances in muscle parameters over time.

METHODS

In this prospective study, 58 oncological patients were examined by a 3 T MRI receiving between one and five scans. Muscle volume and PDFF were measured, segmentation masks were divided into proximal, middle and distal muscle section.

RESULTS

A regional variation of fat distribution in erector spinae muscle at baseline was found (p < 0.01). During follow-ups significant relative change of muscle parameters was observed. Relative maximum change of erector spinae muscle showed a significant regional variation. Correlation testing with age as a covariate revealed significant correlations for baseline psoas fat volume (r = -0.55, p < 0.01) and baseline psoas PDFF (r = -0.52, p = 0.02) with maximum BMI change during the course of the disease.

CONCLUSION

In erector spinae muscles, a regional variation of fat distribution at baseline and relative maximum change of muscle parameters was observed. Our results indicate that psoas muscle PDFF and fat volume could serve as MRI-determined biomarkers for early risk stratification and disease monitoring regarding progression and severity of weight loss in cancer cachexia.

Longitudinal changes on liver proton density fat fraction differ between liver segments

Background

To study the spatial heterogeneity of liver fat fraction changes during a long-term lifestyle intervention study using magnetic resonance imaging (MRI).

Methods

Thirty-two subjects underwent two MRI-scans in a span of one year. A chemical shift encoding-based water-fat separation method was applied to measure liver proton density fat fraction (PDFF) maps. The PDFF changes in the two liver lobes and the Couinaud segments were compared with the mean liver PDFF change.

Results

The slope of the relationship between mean liver PDFF changes and PDFF liver lobe changes was higher in the right compared to the left lobe (slope_{mean PDFF whole liver ~ mean PDFF right lobe} =1.08, slope_{mean PDFF whole liver ~ mean PDFF left lobe} =0.93, P<0.001). The highest slope of agreement between PDFF changes in each specific liver segment and mean liver PDFF changes was observed in segment VII (slope =1.12). The lowest slope of agreement between PDFF changes in each specific liver segment and mean liver PDFF changes was observed in segment I (slope =0.77).

Conclusions

Larger PDFF changes in the right liver lobe were observed compared to PDFF changes in the left liver lobe (LLL) in subjects with both increasing and decreasing mean liver PDFF after one year. The results are in line with the existing literature reporting a heterogeneous spatial distribution of liver fat and highlight the need to spatially resolve liver fat fraction changes in longitudinal studies.

Lipid droplet-size mapping in human adipose tissue using a clinical 3T system

PURPOSE

To develop a methodology for probing lipid droplet sizes with a clinical system based on a diffusion-weighted stimulated echo-prepared turbo spin-echo sequence and to validate the methodology in water-fat emulsions and show its applicability in ex vivo adipose-tissue samples.

METHODS

A diffusion-weighted stimulated echo-prepared preparation was combined with a single-shot turbo spin-echo readout for measurements at different b-values and diffusion times. The droplet size was estimated with an analytical expression, and three fitting approaches were compared: magnitude-based spatial averaging with voxel-wise residual minimization, complex-based spatial averaging with voxel-wise residual minimization, and complex-based spatial averaging with neighborhood-regularized residual minimization. Simulations were performed to characterize the fitting residual landscape and the approaches' noise performance. The applicability was assessed in oil-in-water emulsions in comparison with laser deflection and in ten human white adipose tissue samples in comparison with histology.

RESULTS

The fitting residual landscape showed a minimum valley with increasing extent as the droplet size increased. In phantoms, a very good agreement of the mean droplet size was observed between the diffusion-weighted MRI-based and the laser deflection measurements, showing the best performance with complex-based spatial averaging with neighborhood-regularized residual minimization processing (R² /P: 0.971/0.014). In the human adipose-tissue samples, complex-based spatial averaging with neighborhood-regularized residual minimization processing showed a significant correlation (R² /P: 0.531/0.017) compared with histology.

CONCLUSION

The proposed acquisition and parameter-estimation methodology was able to probe restricted diffusion effects in lipid droplets. The methodology was validated using phantoms, and its feasibility in measuring an apparent lipid droplet size was demonstrated ex vivo in white adipose tissue.

Local Bone Mineral Density, Subcutaneous and Visceral Adipose Tissue Measurements in Routine Multi Detector Computed Tomography-Which Parameter Predicts Incident Vertebral Fractures Best?

In this case-control study the value of bone mineral density (BMD) at different vertebral levels, subcutaneous adipose tissue (SAT), and visceral adipose tissue (VAT) to identify patients with incident osteoporotic vertebral fractures in routine multi-detector computed tomography (MDCT) exams was assessed.

MATERIAL AND METHODS

Seventeen patients who underwent baseline and follow-up routine contrast-enhanced MDCT and had an incident osteoporotic vertebral fracture at follow-up were included. Seventeen age-, sex- and follow-up duration-matched controls were identified. Trabecular BMD (from Th5 to L5) as well as cross-sectional area of SAT and VAT were extracted.

RESULTS

BMD performed best to differentiate patients with an incident fracture from controls at the levels of Th5 (area under the curve [AUC] = 0.781, p = 0.014), Th7 (AUC = 0.877, p = 0.001), and Th9 (AUC = 0.818, p = 0.005). Applying multivariate logistic regression BMD at Th7 level remained the only significant predictor of incident vertebral fractures (Th5-L5) with an odds ratio of 1.07 per BMD SD decrease. VAT and SAT did not show significant differences between the fracture and control group (p > 0.05).

CONCLUSION

The local BMD measurement appears to be more suitable than standard mean BMD from L1-L3 for fracture risk assessment.

Physiological variation of the vertebral bone marrow water T2 relaxation time

The aim of this study was to investigate physiological variations of the water T2 relaxation time in vertebral bone marrow with respect to age, body mass index (BMI), sex and proton density fat fraction (PDFF) based on single-voxel magnetic resonance spectroscopy (MRS) at 3 T. Multi-TE single-voxel STEAM MRS data of a single lumbar vertebra (L4 or L5) from 260 subjects (160/100 female/male, age: 0.7/37.1/77.7 years, BMI: 13.6/26.2/44.5 kg/m² [min./median/max.]) with no history of vertebral bone marrow pathologies were retrospectively included. All data were processed using a joint series T2-constrained time domain-based water-fat model. Water T2 and PDFF data were analyzed using (a) Pearson's correlation r and (b) multiple linear regression without interactions of the independent variables. Min./median/max. water T2 and PDFF were 11.2/21.1/42.5 ms and 4.0%/36.8%/82.0%, respectively. Pearson's correlation coefficients were significant (P < .05) for water T2 versus age (r = -0.429/-0.210 female/male) and for water T2 versus PDFF (r = -0.580/-0.546 female/male) for females and males, respectively. Females showed significant higher water T2 values compared with males (P < .001). Multiple linear regression for water T2 without interactions revealed a R² = 0.407 with PDFF (P < .001) and sex (P < .001) as significant predictors. The current study suggests that under physiological conditions vertebral bone marrow water T2 is negatively correlated with age and PDFF and shows significant differences between females and males. The observed systematic trends are of relevance for the evaluation of T2 values and T2-weighted bone marrow parameters. Further research on the exact mechanisms and drivers of the observed water T2 behavior is required.

Estimating vertebral bone marrow fat unsaturation based on short-TE STEAM MRS

PURPOSE

To define a metric for the separability between water and olefinic fat peaks that defines a threshold beyond which the extraction of the olefinic fat peak from vertebral bone marrow short-echo time-stimulated echo acquisition mode MRS at 3T is feasible when using a constrained peak fitting based on the triglyceride fat model.

METHODS

The water and olefinic peak height difference was defined as a metric for quantifying the separability of water and olefinic fat peaks. Fat unsaturation was determined using an unconstrained olefinic peak fitting and a constrained fitting of all fat peaks to the triglyceride model. The agreement between the two peak-fitting methods was used to define a threshold on water and olefinic peak height difference separating two groups (A and B), based on L5 short-echo time-stimulated echo acquisition mode (TE = 11 ms) spectra from 252 subjects measured at 3T.

RESULTS

A threshold on water and olefinic peak height difference was defined. Group A with a good agreement of the olefinic fat peak between the two peak-fitting methods showed a mean number of double bounds = 2.95 ± 0.21, a mean number of methylene-interrupted double bounds = 0.94 ± 0.16 and also a significantly lower coefficient of variation for all fatty acid composition parameters compared to group B (p < .001). The water and olefinic peak height difference value showed an inverse association with fat fraction.

CONCLUSION

A threshold of a metric quantifying the separability of the water peak and the olefinic fat peaks was defined for the estimation of the vertebral bone marrow fat unsaturation from short-echo time-stimulated echo acquisition mode MRS. The proposed methodology shows that the assessment of vertebral bone marrow unsaturation is feasible with a short-echo time-stimulated echo acquisition mode MRS in subjects with a higher fat fraction.

Magnetic Resonance Imaging Techniques for Brown Adipose Tissue Detection

Magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) methods can non-invasively assess brown adipose tissue (BAT) structure and function. Recently, MRI and MRS have been proposed as a means to differentiate BAT from white adipose tissue (WAT) and to extract morphological and functional information on BAT inaccessible by other means. Specifically, proton MR (¹H) techniques, such as proton density fat fraction mapping, diffusion imaging, and intermolecular multiple quantum coherence imaging, have been employed to access BAT microstructure; MR thermometry, relaxometry, and MRI and MRS with ³¹P, ²H, ¹³C, and ¹²⁹Xe have shown to provide complementary information on BAT function. The purpose of the present review is to provide a comprehensive overview of MR imaging and spectroscopy techniques used to detect BAT in rodents and in humans. The present work discusses common challenges of current methods and provides an outlook on possible future directions of using MRI and MRS in BAT studies.

Investigation of the Relationship between MR-Based Supraclavicular Fat Fraction and Thyroid Hormones

PURPOSE

Brown adipose tissue (BAT) plays a potential role in energy and glucose metabolism in humans. Thyroid hormones (TH) are main regulators of BAT development and function. However, it remains unknown how the magnetic resonance (MR)-based proton density fat fraction (PDFF) of supraclavicular adipose tissue used as a surrogate marker for BAT presence relates to TH. Therefore, the purpose of this analysis was to investigate the relationship between supraclavicular PDFF and serum levels of TH.

METHODS

In total, 96 adult volunteers from a large cross-sectional study who underwent additional MR examination of the neck and pelvis were included in this analysis. Segmented PDFF maps of the supraclavicular and gluteal subcutaneous adipose tissue were generated. Delta PDFF was calculated as the difference between gluteal and supraclavicular PDFF and grouped as high (≥12%) or low (<12%) based on the median and the clinical rationale of a high versus low probability of BAT being present. Thyroid-stimulating hormone (mIU/L), free triiodothyronine (FT3, pg/mL) and free thyroxine (FT4, ng/dL) levels were determined in blood samples. Body mass index (BMI) was calculated as weight (kg)/height (m)2. Statistical analyses included the use of paired samples ttest, simple linear regression analysis and a multivariable linear regression analysis.

RESULTS

The median age of the subjects (77% female) was 33 years, BMI ranged from 17.2 to 43.1 kg/m2. Supraclavicular and gluteal PDFF differed significantly (76.5 ± 4.8 vs. 89.4 ± 3.5 %, p < 0.01). Supraclavicular PDFF was associated with FT3 in subjects with high delta PDFF (R2 = 0.17, p < 0.01), with higher FT3 being associated with lower supraclavicular PDFF (y = 85.2 + -3.6 x). In a multivariable linear regression analysis considering further potential prognostic factors, the interaction between the delta PDFF group and FT3 remained a predictor for supraclavicular PDFF (B = -4.65, p < 0.01).

DISCUSSION/CONCLUSIONS

Supraclavicular PDFF corresponds to the presence of BAT. In the present analysis, supraclavicular PDFF is correlated with FT3 in subjects with high delta PDFF. Therefore, the present findings suggest that biologically active T3 may be involved in the development of supraclavicular BAT.

Vertebral Bone Marrow Heterogeneity Using Texture Analysis of Chemical Shift Encoding-Based MRI: Variations in Age, Sex, and Anatomical Location

Objective: Vertebral bone marrow composition has been extensively studied in the past and shown potential as imaging biomarker for osteoporosis, hematopoietic, and metabolic disorders. However, beyond quantitative assessment of bone marrow fat, little is known about its heterogeneity. Therefore, we investigated bone marrow heterogeneity of the lumbar spine using texture analysis of chemical-shift-encoding (CSE-MRI) based proton density fat fraction (PDFF) maps and its association with age, sex, and anatomical location. Methods: One hundred and fifty-six healthy subjects were scanned (age range: 20-29 years, 12/30 males/females; 30-39, 15/9; 40-49, 5/13; 50-59, 9/27; ≥60: 9/27). A sagittal 8-echo 3D spoiled-gradient-echo sequence at 3T was used for CSE-MRI-based water-fat separation at the lumbar spine. Manual segmentation of vertebral bodies L1-4 was performed. Mean PDFF and texture features (global: variance, skewness, kurtosis; second-order: energy, entropy, contrast, homogeneity, correlation, sum-average, variance, dissimilarity) were extracted at each vertebral level and compared between age groups, sex, and anatomical location. Results: Mean PDFF significantly increased from L1 to L4 (35.89 ± 11.66 to 39.52 ± 11.18%, p = 0.017) and with age (females: 27.19 ± 6.01 to 49.34 ± 7.75%, p < 0.001; males: 31.97 ± 7.96 to 41.83 ± 7.03 %, p = 0.025), but showed no difference between females and males after adjustment for age and BMI (37.13 ± 11.63 vs. 37.17 ± 8.67%; p = 0.199). Bone marrow heterogeneity assessed by texture analysis, in contrast to PDFF, was significantly higher in females compared to males after adjustment for age and BMI (namely contrast and dissimilarity; p < 0.031), demonstrated age-dependent differences, in particular in females (p < 0.05), but showed no statistically significant dependence on vertebral location. Conclusion: Vertebral bone marrow heterogeneity, assessed by texture analysis of PDFF maps, is primarily dependent on sex and age but not on anatomical location. Future studies are needed to investigate bone marrow heterogeneity with regard to aging and disease.

Strain Elastography of Breast and Prostata Cancer: Similarities and Differences

Typically both breast and prostate cancer present as tissue with decreased elasticity. Palpation is the oldest technique of tumor detection in both organs and is based on this principle. Thus an operator can grade a palpable mass as suspicious for cancer. Strain elastography as modern ultrasound technique allows the visualization of tissue elasticity in a color coded elastogram and can be understood as technical finger. The following article shows similarities and differences of ultrasound strain elastography in the diagnosis of breast and prostate cancer.

KEY POINTS

• In prostata cancer elastography, in breast cancer B-mode is the primary sonographic search modality. • The diagnostic value of the search modalities change with increasing age.• A cut-off value for a strain ratio is hard to obtain in the elastography of the prostata, because there is no stabile reference tissue in the prostata.

Applications of technical fusion in uroradiology

Technical fusion is defined as the ultrasound-guided navigation through a previously generated 3 D imaging dataset such as a computed tomography (CT) or magnetic resonance imaging (MRI). This technique allows for moving the fused CT/MRI datasets synchroneously with the real-time ultrasound in the same plane. Established and furthermore not yet described applications, the technical principles and the limitations of this promising technique will be introduced.

Cerebral large vessel vasculitis in systemic lupus erythematosus

Neuropsychiatric systemic lupus erythematosus (NPSLE) is defined by involvement of the central nervous system in systemic lupus erythematosus (SLE), with a wide range of both neurological and psychiatric manifestations. Although its aetiopathogenesis is not fully elucidated, NPSLE seems to be a consequence of cerebral vascular pathology including thromboembolism, small-vessel vasculopathy and, in rare cases, true vasculitis. Cerebral vasculitis is rare, and cerebral large-vessel vasculitis in SLE is even more unusual. We report the case of a female patient with the diagnosis of SLE. She presented with stroke-like symptoms, headache and vertigo, and palpable purpura on her legs. Further investigations revealed that she suffered from both vasculitis of the cerebral large vessels and coexisting cutaneous small-vessel vasculitis.

Limited effect of recombinant porcine interleukin-12 on porcine lymphocytes due to a low level of IL-12 beta2 receptor

The cytokine interleukin-12 (IL-12) is a key molecule in the regulation of CD4 + T cell development and specifically potentiates T helper 1 responses in mouse and man. However, biological effects mediated by IL-12 have not been well defined in pigs. Herein, recombinant porcine IL-12 (rPoIL-12) was expressed in a swine poxvirus system as a biologically active heterodimer and used to stimulate bovine or swine lymphoblast cells. After 3 days of incubation, only bovine blasts were responsive to the rPoIL-12 treatment as monitored by cell proliferation in several independent trials. Similarly, i.m. administration of rPoIL-12 in the hind leg of 3-week-old pigs indicated a reduction in the number of interferon-gamma (IFN-gamma) producing lymphocytes isolated from inguinal lymph nodes. The porcine IL-12R beta2 (IL-12Rbeta2) sequence was cloned and results generated by reverse transcriptase polymerase chain reaction (RT-PCR) demonstrated that the expression of IL-12R on porcine blasts as measured by the relative levels of IL-12Rbeta2 mRNA was less than that in bovine blasts and are in agreement with the reduced proliferation response of swine blast cells to rPoIL-12 treatment. Real time PCR analysis demonstrated that after PBMC stimulation, bovine blasts had an 11-fold increase in IL-12Rbeta2 mRNA levels while porcine blasts had almost no change. These data support a mechanism for IL-12 stimulation in swine inconsistent with that observed in conventional models.

Embryo vaccination of turkeys against Newcastle disease infection with recombinant fowlpox virus constructs containing interferons as adjuvants

Recombinant fowlpox viruses (rFPV) expressing the fusion and hemagglutinin-neuraminidase glycoproteins of Newcastle disease virus (NDV) as well as chicken type I interferon (IFN) or type II IFN were used to vaccinate specific pathogen-free (SPF) turkeys in ovo. No significant changes in the hatchability, survival rate, performance and weight gain were observed after vaccination with the rFPV vaccines in comparison to diluent-inoculated embryos. The rFPV-NDV-IFN-II construct induced the onset of anti-NDV antibody production in SPF birds at one week post hatch, one week earlier than other vaccine constructs. Three to five weeks post hatch, the turkeys were challenged with the neurotropic velogenic NDV strain Texas GB (NDV-GB-Tx). The rFPV-NDV-IFN-II construct was the most protective vaccine against NDV. rFPV vaccines significantly (p<0.05) suppressed the mitogenic response of peripheral blood leukocytes in vaccinated turkeys in comparison to placebo inoculated controls at 25 days post vaccination. Birds vaccinated with rFPV-NDV-IFN-I construct did not have an inhibition in the mitogenic response.

Suppression of acquired immunity against Listeria monocytogenes by amphotericin B-mediated inhibition of CD8 T cell function

Amphotericin B is frequently used for the treatment of fungal infections of immunocompromised individuals. Whereas immunomodulatory side effects of this agent are known, the influence of amphotericin B was studied in the model of murine Listeria monocytogenes infection. Treatment of L. monocytogenes-immune mice with a nontoxic dose of amphotericin B (0.75 mg/kg) reduced antilisterial protection by 4-5 orders of magnitude, while it had no significant effect on natural immunity against L. monocytogenes in naive mice. Treatment of mice with amphotericin B also abolished the protection mediated by transfer of an L. monocytogenes-specific CD8 T cell line. Furthermore, in vitro analysis showed that amphotericin B impaired target cell lysis and interferon-gamma production by peptide-specific CD8 T cell lines and antigen presentation by L. monocytogenes-infected macrophagelike cells. These data indicate that amphotericin B has a strong suppressive effect on the function of CD8 T cells in vitro and in vivo.

Evolutionary implications of genetic variations in the S1 gene of infectious bronchitis virus

The large number of phenotypically distinct strains of infectious bronchitis virus (IBV) provide a broad genetic background for examining naturally occurring coronavirus variation. Comparisons of the published nucleotide sequence of S1 genes of strains isolated in Europe, Japan and the USA and four additional American strains described in this report identified 4 genetically distinct groups. The Dutch group was the most divergent sharing only about 60% identity with the American, Mass and European groups which were about 80% homologous with each other. Whereas the strains within the Mass, European and Dutch strains were at least 95% homologous, the strains within the American group were most variable, sharing about 80% identity. The hypervariable region (HVR) which tended to correlate with serotype extended from amino acid residue 53 to 148. In addition to the previously described putative recombination events in the S1 gene of PP14 and SE17, we have now described similar shifts in homology in the corresponding gene of the Gray, Holte, 6/82 (European strain), and Iowa strains. Although minor cross-over sites were identified in the more conserved 3' end at approximately nt 1000 and 1400, a frequently used hot-spot for recombination extended from nt 25 to a region immediately upstream of, but not including, the hypervariable region (HVR). In addition to point mutations, deletions, and insertions, recombination often involving Mass-like and Ark-like sequences, is a commonly used mechanism responsible for the evolution of IBV.

[Psychoses in encephalitis of uncertain etiology. Atypical course of multiple sclerosis?]

We report on 6 patients (4 female, 2 male, age 17-40 yrs.), admitted to hospital because of psychotic illness. In 2 patients paranoid-hallucinatory symptomatology was prominent, while a manic, a schizo-affective, a catatonic and a mixed organic brain syndrome were found in one case each. Neurological signs could be detected in 4 and EEG-abnormalities in 5 patients. On the basis of CSF findings typical of chronic encephalitis, together with evidence of demyelinating lesions on MRT we confirmed the presence of inflammatory brain disease in all six patients. As a specific etiology could not be established in any of the cases, we suggest the encephalitic variant of multiple sclerosis as the probable diagnosis. In view of our clinical observations, we assume that by using modern investigational techniques--especially sophisticated CSF analysis and MRT--an encephalitic etiology of schizophrenic and affective syndromes may be proven in higher frequency than in the past.

Evidence of natural recombination within the S1 gene of infectious bronchitis virus

During an outbreak of severe respiratory disease, a field strain of infectious bronchitis virus (IBV), PP14, was isolated from a bird in a Texas flock that had been previously vaccinated with an attenuated Mass serotype virus. After cloning and sequencing the S1 gene from several IBV strains, it was found that the 5' end of the cDNA was 96% identical to the published sequences of Mass41 and 77% identical with Ark99. The following 402 bases which included the hypervariable regions (HVR) of the S1 gene were 94% homologous with Ark99 and only 69% with Mass41. In addition, the HVR in the 3' noncoding region of the genome, which is totally absent in Mass41, was 99% homologous with the Ark99 strain. This abrupt shift in identity of PP14 in the S1 strongly indicated that a recombination event had occurred about 98 bases from the beginning of the S1 gene between an Ark-like and a Mass-like virus. Downstream, 33 bases from the PP14 recombination junction, a second putative "cross-over" site was identified in the S1 of the SE17 strain where the 5'131 bases of the S1 gene of the Ark99 and SE17 were found to be 95% identical and the following 368 base sequence was only 78% homologous. In addition, a second shift in homology in the S1 of SE17 was identified between nucleotide 1112 and 1460 which shared 95% identity with Mass41. The putative recombination junctions which were downstream of the signal sequence and upstream of the S1 HVR may represent a "hot spot," but not an exclusive region, for exchanging genetic material between IBV strains. Genetic shifts are apparently not only common mechanisms for variation in nature, but vaccine strains may actually play a critical role in these events in the evolution of virulent strains of IBV.

[Nuclear medicine--personnel exposure and release of radioactivity]

The Nuclear Medicine Division and 30 other groups at the University of Hannover School of Medicine are taken as examples to describe the diagnostic, therapeutic and research uses of radioactivity and the effectiveness of the associated radiation protection. The evolution of radiation exposures of 520 employees followed over the last six years and the methods used for the disposal of radioactive waste are explained. The adaptation of protective measures to individual and, in particular, specific working conditions has led to approximately 90% of all exposures remaining under the detection limit of the personal dosimeters during the entire observation period. Only a few people contributed to the collective radiation dose. In 1990, the average annual dose equivalent among personnel in the Nuclear Medicine Division was 0.12 mSv/person. By the installation of facilities for the storage of isotopes with short half-lives and of filters in the air circulation system, environmental contamination could be held much below the legal limits. Combustible and liquid waste containing radionuclides with long half-lives such as tritium and 14C had to be disposed of separately. However, they were a small fraction of the total radioactivity used.

Nuklearmedizin – Personalbelastung und Aktivitätsabgaben

The Nuclear Medicine Division and 30 other groups at the University of Hannover School of Medicine are taken as examples to describe the diagnostic, therapeutic and research uses of radioactivity and the effectiveness of the associated radiation protection. The evolution of radiation exposures of 520 employees followed over the last six years and the methods used for the disposal of radioactive waste are explained. The adaptation of protective measures to individual and, in particular, specific working conditions has led to approximately 90% of all exposures remaining under the detection limit of the personal dosimeters during the entire observation period. Only a few people contributed to the collective radiation dose. In 1990, the average annual dose equivalent among personnel in the Nuclear Medicine Division was 0.12 mSv/person. By the installation of facilities for the storage of isotopes with short half-lives and of filters in the air circulation system, environmental contamination could be held much below the legal limits. Combustible and liquid waste containing radionuclides with long half-lives such as tritium and 14C had to be disposed of separately. However, they were a small fraction of the total radioactivity used.

[Results of percutaneous transluminal irradiation of biliary tract carcinoma with 192Iridium]

In 22 patients with bile duct carcinoma's intratumoral irradiation was performed through a percutaneous biliary drainage. 17 of them had been found to be inoperable at laparotomy, 5 others had recurrent carcinoma at the site of a biliodigestive anastomosis. The applied dose ranged from 60 to 80 Gy at 6 mm distance of the centre of the Iridium source. In 12/22 patients a clear reduction in the degree of tumor stenosis could be established. Regarding the survival of the patients (8.6 months) results were relatively poor, due to extensive metastases. Patients with a documented dilatation of tumor stenosis showed a low significant longer survival period (12.3 months) than those without detectable response (4.2 months).

[Scintigraphic studies of gonadal burden in radiosynoviortheses of the knee joint with yttrium 90]

Yttrium-90 radiosynoviorthesis of the knee joint in rheumatic inflammatory diseases shows favourable results. Because of the supposed exposure of the patients gonads, Yttrium synoviorthesis has rarely been performed in patients below the age of 40. Scintigraphic studies in 20 patients with rheumatoid arthritis showed no significant leakage of the radionuclide from the knee joint. Gamma camera measurements both phantom and in vivo in the regions of ovary and testes revealed a local dose of 1.05 microGy/MBq (3.9 mrd/mCi) or 1.1 microGy/MBq (4.1 mrd/mCi) of the injected radioactivity. Calculation of the maximum possible load of the gonads, supposing even total leakage of the injected 90-Yttrium from the knee joint, yielded a maximum possible dose of 6 mGy (600 mrd). We conclude from these studies and calculations that Yttrium-90 synoviorthesis of the knee joint can safely be carried out in patients below the age of 40.

Six hundred years: Heidelberg University--crisis and achievements

Throughout its 600 years, Heidelberg University has endured the social and political upheavals of history, repeatedly rising like a phoenix from the ashes of a series of disasters to fulfill its mission as a center of learning and research. Founded in 1386, and buffeted by wars, plaques, and diverse political and social systems ever since, the university has developed along lines determined as much by regional, European, and world politics as by the dynamics inherent in its disciplines. Its history may be divided into the following six historical phases: (1) the scholastic university of the late Middle Ages (1386-1556); (2) the Protestant university (1556-1685); (3) the Catholic university (1685-1807); (4) the university in the age of liberalism and nationalism (1803-1933); (5) the university during National Socialism (1933-1945); and (6) the contemporary university and its efforts to cope with the explosion of knowledge, steadily growing student numbers, and other problems related to growth, expansion, and diversification in all disciplines (1945 to the present).

[Dosimetry of the hematopoietic system in radioiodine therapy of thyroid cancer]

Twenty patients were submitted to thyroidectomy and treated with iodine-131. Ten out of them received 100 mCi, the other ten 200 mCi. The activity of the total body and of the blood was determined by experimental proceeding. The doses absorbed by blood and bone marrow were calculated on the basis of the experimentally determined values. For the exposure of the blood, a medium value of 0.44 rd/mCi was found after 100 mCi and a medium value of 0.47 rd/mCi after 200 mCi. The corresponding values for the bone marrow are 0.24 and 0.3 rd/mCi, respectively. The total exposure is thus not so high as has been indicated hitherto in literature.

[Percutaneous transluminal irradiation of biliary tract cancer using iridium]

In ten patients with biliary carcinomas, percutaneous biliary drainage was instituted and intracavitary irradiation performed, using 192iridium with a dose of 40 to 80 Gy. Eight of these patients had been found to be inoperable at laparotomy and two had had a recurrence. In half the patients there was a reduction in the degree of stenosis due to the tumour, but in only one patient was it possible to remove the draining catheter. Survival time in eight patients was between one and eight months, average 5 months. Two patients survived for eleven and twelve months respectively. The relatively poor results are due to extensive metastases. On the other hand, there can be no doubt about the effectiveness of this treatment on locally confined tumours, in view of the reduction in the obstruction caused by the tumour.

Microvascular adjustments during irreversible hemorrhagic shock in rat skeletal muscle

A study was made of microvessel response to hemorrhagic hypotension and the subsequent restoration of blood volume. The experiments were conducted on anesthetized rats in which the cremaster muscle was exteriorized for intravital microscopy. Variables measured during hypotension (40 mm Hg for 60 min) and after blood restoration (120 min observation) included systemic blood pressure, heart rate, arteriolar and venular diameter, sensitivity to epinephrine, velocity and volumetric flow rate. These findings were correlated with 24-hr survival statistics. The response to hemorrhagic hypotension is a reflection of two separate adjustments, cardiac output and peripheral vascular behavior. In survivors, the microvascular sequelae following blood replacement was one of continuous improvement of muscle perfusion, whereas in nonsurvivors the picture was one of progressive deterioration. The consistent hallmark of irreversibility, arteriolar hyposensitivity, was associated with a continuous falling off in mean arterial pressure despite restoration of normal blood volume.

Improved hemagglutination inhibition assay for mammary tumor virus antigen

It is our experience that the use of sheep red blood cells pretreated with formaldehyde and pyruvaldehyde before sensitizing with viral antigen yields results that are comparable to that obtained by using the tannic acid method. The double aldehyde method provides the added advantage of being useful for assaying the viral antigen content in substances which contain high levels of interfering substances which would preclude the use of other assay methods.