Influence of surgical intervention at the level of the dorsal spinous processes on the biomechanics of the equine thoracolumbar spine.

BACKGROUND: Surgical treatment options for horses with overriding dorsal spinous processes include interspinous ligament desmotomy and partial spinous process ostectomy. The impact of spinal surgery on the three-dimensional biomechanics of the equine thoracolumbar spine and the epaxial musculature is unclear. OBJECTIVES: To investigate the influence of interspinous ligament desmotomy and cranial wedge ostectomy on the biomechanics of the equine thoracolumbar spine and the paraspinal Musculi multifidi. STUDY DESIGN: Ex-vivo experiments. METHODS: Twelve equine thoracolumbar spine specimens were mounted in a custom-made mechanical test rig. Based on computed tomographic imaging, distances between dorsal spinous processes and the spinal range of motion (lateral bending, axial rotation, flexion, extension) were compared before and after desmotomy and cranial wedge ostectomy performed at two or five surgical sites. Anatomical dissection was subsequently conducted to document surgical trauma to the Musculi multifidi following desmotomy. RESULTS: The distance between spinous processes in neutral position did not increase significantly after desmotomy (median preoperative = 7.2 mm, interquartile range [IQR] = 3.6 mm; median postoperative = 7.4 mm, IQR = 3.7 mm; p = 0.09), but increased significantly after ostectomy (median preoperative = 8.8 mm, IQR = 4.2 mm; median postoperative = 13 mm, IQR = 6.1 mm; p < 0.001). Both surgical procedures significantly increased the rotational spinal range of motion (p = 0.001), particularly at the level T14/T15 (median preoperative = 6.4°, IQR = 3.2°; median postoperative = 8.2°, IQR = 3.5°; increase = 28.1%; p = 0.02). Musculi multifidi injury was evident at all desmotomy sites. MAIN LIMITATIONS: Ex-vivo study with limited sample size. CONCLUSIONS: Neither interspinous ligament desmotomy nor cranial wedge ostectomy resulted in an increased range of motion during flexion, extension or lateral bending but both procedures influenced the rotational component of the equine thoracolumbar spinal mobility.

Computed tomographic study analysing functional biomechanics in the thoracolumbar spine of horses with and without spinal pathology.

To better understand physiological and pathological movement patterns in the equine thoracolumbar spine, investigation of the biomechanics on a segmental level requires a constant moment. A constant moment along the spinal column means that the same torque acts on each vertebral segment, allowing the range of motion of different segments to be compared. The aims of this study were to investigate the range of motion of the equine thoracolumbar spine in horses with and without spinal pathology and to examine whether the pressure between the spinous processes depends on the direction of the applied moment. Thoracolumbar spine specimens (T8-L4) of 23 horses were mounted in a custom-made mechanical test rig to investigate spinal biomechanics during lateral bending, axial rotation, flexion and extension using computed tomographic imaging. Results were compared between horses with spondylosis, overriding spinous processes and specimens free of gross pathology. The interspinous space pressure was additionally determined using a foil sensor. The median lateral bending between T9 and L3 was 3.7°-4.1° (IQR 5.4°-8.0°). Maximum rotational movement with inconsistent coupled motion was observed at T9-T16 (p < 0.05). The dorsoventral range of motion was greatest in segments T9-T11 (p < 0.05). Spondylosis and overriding spinous processes restricted spinal mobility, depending on the severity of the condition. There was no significant difference in interspinous pressure during motion (p = 0.54). The biomechanical study confirmed that the range of motion of intervertebral joints depends on the anatomical position of the joint and the direction of the moment applied. Restricted mobility was evident in the presence of different grades of overriding spinous processes or spondylosis. A better understanding of equine spinal biomechanics in horses with spinal pathology facilitates individual rehabilitation.

Charge Dynamics of a CuO Thin Film on Picosecond to Microsecond Timescales Revealed by Transient Absorption Spectroscopy.

Understanding the mechanism of charge dynamics in photocatalysts is the key to design and optimize more efficient materials for renewable energy applications. In this study, the charge dynamics of a CuO thin film are unraveled via transient absorption spectroscopy (TAS) on the picosecond to microsecond timescale for three different excitation energies, i.e., above, near, and below the band gap, to explore the role of incoherent broadband light sources. The shape of the ps-TAS spectra changes with the delay time, while that of the ns-TAS spectra is invariant for all the excitation energies. Regardless of the excitations, three time constants, τ1 ∼ 0.34-0.59 ps, τ2 ∼ 162-175 ns, and τ3 ∼ 2.5-3.3 µs, are resolved, indicating the dominating charge dynamics at very different timescales. Based on these observations, the UV-vis absorption spectrum, and previous findings in the literature, a compelling transition energy diagram is proposed. Two conduction bands and two defect (deep and shallow) states dominate the initial photo-induced electron transitions, and a sub-valence band energy state is involved in the subsequent transient absorption. By solving the rate equations for the pump-induced population dynamics and implementing the assumed Lorentzian absorption spectral shape between two energy states, the TAS spectra are modeled which capture the main spectral and time-dependent features for t > 1 ps. By further considering the contributions from free-electron absorption during very early delay times, the modeled spectra reproduce the experimental spectra very well over the entire time range and under different excitation conditions.

Health Monitoring of Fattening Pigs - Use of Production Data, Farm Characteristics and On-Farm Examination.

BACKGROUND: The use of processed secondary data for health monitoring of fattening pigs has been established in various areas, such as the use of antibiotics or in the context of meat inspection. Standardized scores were calculated based on several sources of production data and can be used to describe animal health in a large collective of pig units. In the present study, the extent to which these scores are related to different farm characteristics and management decisions were investigated. In addition, slaughter scores were compared with the results of a veterinary examination on the farms. RESULTS: The comparison of the results of the uni- and multifactorial analyses revealed that almost all of the examined factors play a role in at least one of the scores when considered individually. However, when various significant influencing factors were taken into account at any one time, most of the variables lost their statistical significance due to confounding effects. In particular, production data such as production costs or daily feed intake remained in the final models of the scores on mortality, average daily gain and external lesions. Regarding the second part of the investigation, a basic technical correlation between the slaughter scores and the on-farm indicators could be established via principal component analysis. The modelling of the slaughter scores by the on-farm indicators showed that the score on external lesions could be represented by equivalent variables recorded on the farm (e.g., lesions caused by tail or ear biting). CONCLUSIONS: It has been demonstrated that the examined health scores are influenced by various farm and management characteristics. However, when several factors are taken into account, confounding occurs in some cases, which must be considered by consultants. Additionally, it was shown that on-farm examination content is related to the scores based on equivalent findings from slaughter pigs.

Health monitoring of finishing pigs by secondary data use - a longitudinal analysis.

BACKGROUND: In Germany, animal welfare has become an increasingly important issue. Since 2006, German legislation demands self-monitoring of animal welfare by farmers, but there is a lack of prescribed indicators for governmental monitoring. Since recording of the health status through examinations on individual farms requires many resources, secondary data use is obvious. Therefore, this study deals with the overall evaluation and utilization of existing production data from the German pork production. Performance data and information on antibiotic usage and meat inspection were used for a benchmarking system of animal health in finishing pigs. RESULTS: Seven health scores and one total score were evaluated for 184 finishing pig herds on semi-annual basis between July 2017 and June 2019, based on the health indicators mortality, average daily gain, feed conversion ratio, treatment frequency, respiratory lesions, exterior lesions and animal management. In preparation, the selected health indicators were brought to the same scale and skewed data were transformed to build scores (MOR, ADG, FCR, TF, RESP, EXT and MANG). A differentiated analysis was carried out for three classes of initial body weight regarding to farmers' fattening management strategies. CONCLUSIONS: The present study shows that existing production data of German finishing pigs are usable for welfare monitoring. However, preparatory editing steps are crucial. The total score can only be an estimate of health status because partly bad or good performance could be disguised. It has also been demonstrated, that relative benchmarking is suitable for depicting temporary fluctuations in the investigated collective.

Application of the voluntary human approach test on commercial pig fattening farms: a meaningful tool?

BACKGROUND: A Voluntary Human Approach Test (VHAT) was performed in pig pens, and relationships between environmental conditions and welfare indicators were investigated. Five variables were measured in 1668 pens in 214 fattening pig herds in Germany: time until the first contact (touching) between a pig and the person in the pen (TUFC), time until the observer was surrounded by pigs within a radius of approximately two meters, percentage of pigs relative to group size [%] surrounding the observer after 1 min (PPSO), percentage of pigs relative to group size [%] that completely avoided contact with the observer during the entire test period, and how the pigs contacted the observer (Score 0 [no touching] - 3 [biting]). Furthermore, variables indicative of the pigs' environment (e.g., feeding system, ventilation system), management (e.g., number of usable drinkers, number of usable manipulatable materials), and welfare (e.g., tail lesions, ear lesions) were documented. RESULTS: Pigs engaging in more forceful means of contact (nibbling, biting) approached the observer faster than those exhibiting more gentle types of contact (touching). A lower TUFC was associated with more manipulatable materials present, a higher number of drinkers, and with the control position of the caretaker located inside the pen. Pigs kept in larger groups showed a lower TUFC than those in smaller groups (P = 0.0191). However, PPSO was lower in pigs kept in smaller groups (1-12 pigs per pen) with more manipulatable materials available. In groups with low PPSOs, more tail lesions were observed (P = 0.0296). No relationship between contact type and tail or ear injuries was detected. In younger pigs, PPSO was higher (49.9 ± 23.2%) than for animals in the second half of the fattening period (45.1 ± 19.9%). CONCLUSIONS: In this on-farm study, the relationships between VHAT behavior and environmental factors revealed that external factors (e.g., management practices, housing conditions) impact animals' responses to this behavioral test. Therefore, using the VHAT as an animal welfare indicator is valid only if these variables are studied as well.

Implementation of a phase detection algorithm for dynamic cardiac computed tomography analysis based on time dependent contrast agent distribution.

This paper presents a phase detection algorithm for four-dimensional (4D) cardiac computed tomography (CT) analysis. The algorithm detects a phase, i.e. a specific three-dimensional (3D) image out of several time-distributed 3D images, with high contrast in the left ventricle and low contrast in the right ventricle. The purpose is to use the automatically detected phase in an existing algorithm that automatically aligns the images along the heart axis. Decision making is based on the contrast agent distribution over time. It was implemented in KardioPerfusion--a software framework currently being developed for 4D CT myocardial perfusion analysis. Agreement of the phase detection algorithm with two reference readers was 97% (95% CI: 82-100%). Mean duration for detection was 0.020 s (95% CI: 0.018-0.022 s), which was 800 times less than the readers needed (16±7 s, p<03001). Thus, this algorithm is an accurate and fast tool that can improve work flow of clinical examinations.

How influential is the duration of contrast material bolus injection in perfusion CT? evaluation in a swine model.

PURPOSE: To analyze the effect of the duration of contrast material bolus injection on perfusion values in a swine model by using the maximum slope method. MATERIALS AND METHODS: This study was approved by the institutional animal care committee. Twenty pigs (weight range, 63-77 kg) underwent dynamic volume computed tomography (CT) of the kidneys during suspended respiration. Before the CT examination, a miniature cuff-shaped ultrasonographic flow probe encircling the right renal artery was surgically implanted in each pig to obtain true perfusion values. Two sequential perfusion CT series were performed in 30 seconds, each comprising 30 volumes with identical parameters (100 kV, 200 mAs, 0.5 sec rotation time). The duration of contrast material bolus (0.5 mL/kg of body weight) was 3.8 seconds in the first series (short bolus series) and 11.5 seconds in the second series (long bolus series), and the injection flow rate was adapted accordingly. In each pig, cortical kidney volume was determined by using the volume with the highest cortical enhancement. CT perfusion values were calculated for both series by using the maximum slope method and were statistically compared and correlated with the true perfusion values from the flow probe by using linear regression analysis. RESULTS: Mean true perfusion and CT perfusion values (in minutes(-1)) for the short bolus series were 1.95 and 2.03, respectively (P = .22), and for the long bolus series, they were 2.02 and 1.92, respectively (P = .12). CT perfusion showed very good correlation with true perfusion in both the short (slope, 1.01; 95% confidence interval: 0.91, 1.11) and long (slope, 0.92; 95% confidence interval: 0.78, 1.04) series. On the basis of the regression analysis, CT perfusion values in the short bolus series were overestimated by 1% and those in the long bolus series were underestimated by 8%. CONCLUSION: Duration of contrast material bolus injection does not influence CT perfusion values substantially. The longer, clinically preferred intravenous injection scheme is sufficiently accurate for CT perfusion.

Reducing Radiation Dose in Emergency CT Scans While Maintaining Equal Image Quality: Just a Promise or Reality for Severely Injured Patients?

Objective. This study aims to assess the impact of adaptive statistical iterative reconstruction (ASIR) on CT imaging quality, diagnostic interpretability, and radiation dose reduction for a proven CT acquisition protocol for total body trauma. Methods. 18 patients with multiple trauma (ISS ≥ 16) were examined either with a routine protocol (n = 6), 30% (n = 6), or 40% (n = 6) of iterative reconstruction (IR) modification in the raw data domain of the routine protocol (140 kV, collimation: 40, noise index: 15). Study groups were matched by scan range and maximal abdominal diameter. Image noise was quantitatively measured. Image contrast, image noise, and overall interpretability were evaluated by two experienced and blinded readers. The amount of radiation dose reductions was evaluated. Results. No statistically significant differences between routine and IR protocols regarding image noise, contrast, and interpretability were present. Mean effective dose for the routine protocol was 25.3 ± 2.9 mSv, 19.7 ± 5.8 mSv for the IR 30, and 17.5 ± 4.2 mSv for the IR 40 protocol, that is, 22.1% effective dose reduction for IR 30 (P = 0.093) and 30.8% effective dose reduction for IR 40 (P = 0.0203). Conclusions. IR does not reduce study interpretability in total body trauma protocols while providing a significant reduction in effective radiation dose.

Comparison of free breathing versus breath-hold in perfusion imaging using dynamic volume CT.

OBJECTIVES: To compare two scanning protocols (free breathing versus breath-hold) for perfusion imaging using dynamic volume computed tomography (CT) and to evaluate their effects on image registration. MATERIAL AND METHODS: Forty patients underwent dynamic volume CT for pancreatic perfusion analysis and were randomly assigned to either a shallow-breathing (I) or breath-hold (II) group. Both dynamic CT protocols consisted of 17 low-dose volumetric scans. Rigid image registration was performed by using the volume with highest aortic attenuation as reference. All other volumes were visually matched with the pancreatic lesion serving as the volumetric region of interest. The overall demand for post-processing per patient was calculated as the median of three-dimensional vector lengths of all volumes in relation to the relative patient origin. The number of volumes not requiring registration was recorded per group. RESULTS: Registration mismatch for groups I and II was 2.61 mm (SD, 1.57) and 4.95 mm (SD, 2.71), respectively (P < 0.005). Twenty-eight volumes in group I (8.2%) and 47 volumes in group II (14.1%) did not require manual registration (P = 0.014). CONCLUSION: Shallow breathing during dynamic volume CT scanning reduces the overall demand for motion correction and thus may be beneficial in perfusion imaging of the pancreas MAIN MESSAGES: • Shallow breathing during perfusion CT scanning reduces the overall demand for motion correction. • Shallow breathing may be beneficial in perfusion imaging of the pancreas. • Image registration is crucial for CT perfusion imaging.

Effects of xylazine hydrochloride on hormonal, metabolic, and cardiorespiratory stress responses to lateral recumbency and claw trimming in dairy cows.

OBJECTIVE: To investigate the hormonal, metabolic, and cardiorespiratory effects of xylazine hydrochloride on dairy cows undergoing lateral recumbency and claw trimming. DESIGN: Prospective crossover study. ANIMALS: 6 healthy Holstein-Friesian cows. PROCEDURES: Cows were treated with xylazine (0.05 mg/kg [0.023 mg/lb], IM) or an equal volume of saline (0.9% NaCl) solution 15 minutes before being placed in lateral recumbency for claw trimming. As a third treatment, cows also received xylazine (0.05 mg/kg, IM) but underwent no further manipulation. At preset time intervals, heart rate (HR), respiratory rate (RR), systolic arterial blood pressure, diastolic arterial blood pressure, mean arterial blood pressure (MAP), blood gas values, and plasma concentrations of cortisol, insulin, glucose, lactate, and nonesterified fatty acids (NEFA) were measured, and signs of sedation and ruminal bloat were recorded. RESULTS: Saline solution treatment resulted in a temporary significant increase in SAP, diastolic arterial blood pressure, MAP, RR, and cortisol, lactate, and NEFA concentrations and a significant decrease in arterial oxygen saturation (Sao(2)). Xylazine treatment induced significant decreases in HR, RR, MAP, insulin and NEFA concentrations, and Sao(2) and induced significant increases in glucose concentration. Compared with saline solution treatment, HR, RR, MAP, Sao(2), and cortisol, lactate, and NEFA concentrations were significantly decreased with xylazine treatment. Xylazine treatment resulted in mild signs of sedation as well as clinically negligible ruminal bloat. CONCLUSIONS AND CLINICAL RELEVANCE: Xylazine administered in a low dose to cows preceding lateral recumbency for claw trimming decreased hormonal and metabolic stress responses, but augmented the respiratory depressive effect of lateral recumbency reflected by a decreased Pao and increased Paco(2).

The use of xylazine hydrochloride in an analgesic protocol for claw treatment of lame dairy cows in lateral recumbency on a surgical tipping table.

The objective of this study was to investigate the effect of xylazine on the stress and pain response of lame cows undergoing claw treatment in lateral recumbency (LR). Twenty-four lame, German Holstein-Friesian cows were included in a prospective, blinded, placebo-controlled clinical case study. Cows were randomly allocated to two groups (n=12) and either treated with xylazine (0.05 mg/kg BW, i.m.) or an equal volume of saline (controls) 15 min before placing them in LR. Before surgical treatment, each cow received retrograde intravenous local anaesthesia (LA). Over a period of 6h, heart rate (HR), respiratory rate (RR), plasma concentrations of cortisol, glucose, lactate and non-esterified fatty acids (NEFA) were determined at preset time intervals and the animals' behaviour was recorded via video recording and pedometer. All xylazine-treated cows showed signs of mild sedation, a reduced pain response on insertion of the needle for LA, reduced ear flicking during surgery, reduced lameness score and longer standing periods as well as improved appetite in the first hour postoperatively. Mean HR and RR, as well as plasma concentrations of NEFA were significantly reduced after xylazine treatment. Cortisol concentrations were significantly lower in xylazine-treated cows after being placed in LR but were similar to controls during surgery. The use of a low dose of xylazine in the analgesic protocol for the treatment of lame cows in LR alleviates stress and potentiates the analgesic effects of LA.

Comparison of isoflurane inhalation anaesthesia, injection anaesthesia and high volume caudal epidural anaesthesia for umbilical surgery in calves; metabolic, endocrine and cardiopulmonary effects.

OBJECTIVE: To compare three anaesthetic protocols for umbilical surgery in calves regarding adequacy of analgesia, and cardiopulmonary and hormonal responses. STUDY DESIGN: Prospective, randomised experimental study. ANIMALS: Thirty healthy German Holstein calves (7 female, 23 male) aged 45.9 ± 6.4 days. METHODS: All calves underwent umbilical surgery in dorsal recumbency. The anaesthetic protocols were as follows: group INH (n = 10), induction 0.1 mg kg(-1) xylazine IM and 2.0 mg kg(-1) ketamine IV, maintenance isoflurane in oxygen; Group INJ (n = 10), induction 0.2 mg kg(-1) xylazine IM and 5.0 mg kg(-1) ketamine IV, maintenance 2.5 mg kg(-1) ketamine IV every 15 minutes or as required; group EPI (n = 10), high volume caudal epidural anaesthesia with 0.2 mg kg(-1) xylazine diluted to 0.6 mL kg(-1) with procaine 2%. All calves received peri-umbilical infiltration of procaine and pre-operative IV flunixin (2.2 mg kg(-1) ). Cardiopulmonary variables were measured at preset intervals for up to 2 hours after surgery. The endocrine stress response was determined. Intra-operative nociception was assessed using a VAS scale. Data were compared between groups using appropriate statistical tests. A value of p < 0.05 was considered significant. RESULTS: All three protocols provided adequate anaesthesia for surgery although, as judged by the VAS scale, intra-operative response was greatest with INJ. Lowest mean cortisol levels during surgery occurred in EPI. Heart rate and cardiac output did not differ between groups, but mean arterial blood pressure, systemic vascular resistance, and partial pressure of carbon dioxide were higher and arterial pH lower in groups INH and INJ than in Group EPI. Group INJ became hypoxaemic and had a significantly greater vascular shunt than did the other groups. CONCLUSION AND CLINICAL RELEVANCE: Groups INH and EPI both proved acceptable protocols for calves undergoing umbilical surgery, whilst INJ resulted in variable anti-nociception and in hypoxaemia. High volume caudal epidural anaesthesia provides a practical inexpensive method of anaesthesia for umbilical surgery.

Radiation dose optimisation in dynamic volume CT of the heart: tube current adaptation based on anterior-posterior chest diameter.

To compare tube current adaptation based on 3 body mass index (BMI) categories versus anterior-posterior chest diameter (APD) for radiation dose optimisation in patients undergoing dynamic volume cardiac CT. Two cardiac imaging centres participated in the study. 20 patients underwent a prospectively triggered 320-slice single beat cardiac CT using the X-ray tube current [mA] manually adjusted to the patient's BMI (group I). In 20 subsequent patients, the tube current was adapted according to the patient's APD (group II). All other parameters were kept constant. Image noise was defined as the standard deviation of attenuation values and measured using a ROI in the descending aorta. Variation in image noise was statistically compared between both patient groups. Average and standard deviation of pixel noise were 29.1 HU and 14.8 HU in group I and 28.0 HU and 4.2 HU in group II. Inter-individual variation of pixel noise was significantly lower in group II compared to group I (p < 0.0001). Tube current adaptation based on APD is superior to stepwise adaptation based on BMI for optimising radiation dose in dynamic volume cardiac CT and therefore limits unnecessary radiation dose while ensuring diagnostic image quality in patients with diverse body habitus.

Cardiopulmonary effects of dorsal recumbency and high-volume caudal epidural anaesthesia with lidocaine or xylazine in calves.

The objective of this study was to investigate the cardiopulmonary effects of dorsal recumbency and high-volume caudal epidural anaesthesia induced by xylazine or lidocaine in calves. Twenty-eight German Holstein-Friesian calves (57.7 ± 5.8 kg bodyweight) were randomly allocated to four equal (n=7) groups for one of the following treatments, each injected into the caudal epidural space: (1) no treatment (control); (2) sterile saline (0.4 mL/kg); (3) lidocaine (2%), or (4) xylazine (0.1mg/kg), with the latter two treatments diluted with sterile saline to a final volume of 0.4 mL/kg. Cardiac output was measured by thermodilution and cardiopulmonary function parameters were determined at preset time intervals over an observation period of 335 min. After baseline measurements in the standing animals, the calves received the epidural injection and were positioned in dorsal recumbency for 95 min. In the control group, dorsal recumbency caused a significant (P < 0.05) decrease in cardiac index (CI) (baseline 210 ± 12 mL/kg/min, minimum value 174 ± 11 mL/kg/min), without significant change in blood-gas values. Calves treated with lidocaine or saline did not differ from the control group in any of the parameters measured. The epidural injection of xylazine caused a more pronounced decrease in CI (baseline 209 ± 12 mL/kg/min, minimum value 127 ± 11 mL/kg/min), compared to the control group. At the same time, the heart rate was significantly (P < 0.05) decreased (baseline 113 ± 7 beats per min, minimum value 86 ± 4 beats per min). Furthermore, a significant (P < 0.05) increase in the oxygen extraction ratio was observed in the xylazine group (baseline 39 ± 7%, maximum value 47 ± 7%). In all groups, cardiorespiratory parameters remained within physiological limits. Changes in cardiopulmonary function induced by dorsal recumbency and high-volume caudal epidural anaesthesia with lidocaine or xylazine were well tolerated in healthy calves.

Impact of image noise levels, scout scan dose and lens shield on image quality and radiation exposure in z-axis dose-modulated neck MSCT on 16- and 64-slice Toshiba Aquilion scanners.

OBJECTIVE: Assessing the impact of image noise (IN) levels, scout scan dose and lens shield use on image quality and radiation exposure in neck multislice CT (MSCT) when using z-axis dose modulation (DM). METHODS: Neck MSCT phantom studies with/without z-axis DM were performed by using different IN levels (S.D. 7.5-30HU) and scout scan tube currents (7.5-50mA) on Toshiba Aquilion scanners (16-/64-slice). Image quality indices were evaluated by two radiologists and radiation exposure parameters calculated. Cadaveric phantom measurements elucidated lens shield interactions with DM efficacy. The lowest dose scan protocol with diagnostic image quality was introduced into the clinical imaging routine and retrospectively evaluated in 20 age-matched patients undergoing neck MSCT with/without DM. RESULTS: The highest image noise level in DM neck studies with comparable image quality to standard neck CT amounted to 20HU, resulting in a mean tube current of 50mAs (CTDI(w) 6.3mGy). DM reduced effective dose by 35% and organ dose figures (lens, thyroid) by 33%. Scout scan dose lowering to 20mA resulted in an effective dose (ED) decrease of 0.06mSv (5%). Avoiding lens shield placement during scout scan effected an organ dose decrease of 20%. Overall contour sharpness and image contrast did not differ significantly (DM/without DM) whereas image noise was rated higher in DM neck CT studies (p<0.05). CONCLUSIONS: z-Axis dose modulation, as assessed on 16- and 64-slice Toshiba Aquilion scanners, is effective and mandatory in neck MSCT. DM efficacy can be enhanced by optimising scout scan doses and lens shield use.

Intra-individual comparison of average glandular dose of two digital mammography units using different anode/filter combinations.

RATIONALE AND OBJECTIVES: The aim of this study was to compare average glandular dose (AGD) in two full-field digital mammography units using different anode/filter combinations. MATERIALS AND METHODS: Mammographies of 50 consecutive patients on a mammography system using a tungsten/rhodium (W/Rh) anode/filter combination were retrospectively compared to prior examinations on a different mammography unit using combinations of Molybdenum (Mo) and Rhodium (Rh). To exclude effects of increasing patient age, two prior examinations within 5 years were used. Both views of one breast were chosen for analysis. AGD was recorded as stated by each mammography unit. Accuracy of stated AGD and contrast-detail resolution were assessed using different breast phantoms. RESULTS: The mean AGDs from the examinations using W/Rh were 0.95 mGy and 1.01 mGy for craniocaudal (CC) and mediolateral oblique (MLO) views compared to 1.51 mGy and 1.54 mGy, respectively, using combinations of Mo and Rh (P < .001). Relative reduction of AGD was independent of breast thickness but decreased with increasing breast density (partial correlation coefficient of 0.46, P < .005 and 0.57, P < .001, for CC and MLO views, respectively). Low-level contrast resolution was equal in both units using standard acquisition parameters. CONCLUSION: In clinical mammographies, higher energy beam spectra obtained using W/Rh anode/filter combinations may significantly contribute to lowering AGD compared to Mo/Mo, Mo/Rh, and Rh/Rh in breasts that are not extremely dense.

Whole-organ perfusion of the pancreas using dynamic volume CT in patients with primary pancreas carcinoma: acquisition technique, post-processing and initial results.

The purpose of this study was to evaluate a whole-organ perfusion protocol of the pancreas in patients with primary pancreas carcinoma and to analyse perfusion differences between normal and diseased pancreatic tissue. Thirty patients with primary pancreatic malignancy were imaged on a 320-slice CT unit. Twenty-nine cancers were histologically proven. CT data acquisition was started manually after contrast-material injection (8 ml/s, 350 mg iodine/ml) and dynamic density measurements in the right ventricle. After image registration, perfusion was determined with the gradient-relationship technique and volume regions-of-interest were defined for perfusion measurements. Contrast time-density curves and perfusion maps were generated. Statistical analysis was performed using the Kolmogorov-Smirnov test for analysis of normal distribution and Kruskal-Wallis test (nonparametric ANOVA) with Bonferroni correction for multiple stacked comparisons. In all 30 patients the entire pancreas was imaged, and registration could be completed in all cases. Perfusion of pancreatic carcinomas was significantly lower than of normal pancreatic tissue (P < 0.001) and could be visualized on colored perfusion maps. The 320-slice CT allows complete dynamic visualization of the pancreas and enables calculation of whole-organ perfusion maps. Perfusion imaging carries the potential to improve detection of pancreatic cancers due to the perfusion differences.

Joint experimental-theoretical investigation of the lower bound states of the NO(X2Pi)-Kr complex.

We describe the first measurement of the near IR spectrum of the NO-Kr van der Waals complex. A variant of IR-REMPI double-resonance spectroscopy is employed in which the IR and UV lasers are scanned simultaneously in such a way that throughout the scan the sum of the two photon energies is kept constant, matching a UV resonance of the system. In the region of the first overtone vibration of the NO monomer, we observe several rotationally resolved bands for the NO-Kr complex. In addition to the origin band located at 3723.046 cm(-1), we observe excited as well as hot bands involving the excitation of one or two quanta of z-axis rotation. Another band is assigned to the excitation of one quantum of bending vibration. The experimental spectra are compared with results of bound-state calculations for a new set of potential energy surfaces calculated at the spin-restricted coupled cluster level. For the average vibration-rotation energies, there is excellent agreement between the theoretical results based on the coupled states (CS) approximation and the full close-coupling (CC) treatment. Finer details like the electrostatic splitting and the P-type doubling of the rotational levels are accounted for only within the CC formalism. The comparison of the CC results with the measured spectra confirms the high quality of the PESs. However, the high resolution of the experiments is sufficient to identify some inaccuracies in the difference between the potential energy surfaces of A' and A'' reflection symmetry.

Thick slices from tomosynthesis data sets: phantom study for the evaluation of different algorithms.

Tomosynthesis is a 3-dimensional mammography technique that generates thin slices separated one to the other by typically 1 mm from source data sets. The relatively high image noise in these thin slices raises the value of 1-cm thick slices computed from the set of reconstructed slices for image interpretation. In an initial evaluation, we investigated the potential of different algorithms for generating thick slices from tomosynthesis source data (maximum intensity projection-MIP; average algorithm-AV, and image generation by means of a new algorithm, so-called softMip). The three postprocessing techniques were evaluated using a homogeneous phantom with one textured slab with a total thickness of about 5 cm in which two 0.5-cm-thick slabs contained objects to simulate microcalcifications, spiculated masses, and round masses. The phantom was examined by tomosynthesis (GE Healthcare). Microcalcifications were simulated by inclusion of calcium particles of four different sizes. The slabs containing the inclusions were examined in two different configurations: adjacent to each other and close to the detector and with the two slabs separated by two 1-cm thick breast equivalent material slabs. The reconstructed tomosynthesis slices were postprocessed using MIP, AV, and softMip to generate 1-cm thick slices with a lower noise level. The three postprocessing algorithms were assessed by calculating the resulting contrast versus background for the simulated microcalcifications and contrast-to-noise ratios (CNR) for the other objects. The CNRs of the simulated round and spiculated masses were most favorable for the thick slices generated with the average algorithm, followed by softMip and MIP. Contrast of the simulated microcalcifications was best for MIP, followed by softMip and average projections. Our results suggest that the additional generation of thick slices may improve the visualization of objects in tomosynthesis. This improvement differs from the different algorithms for microcalcifications, speculated objects, and round masses. SoftMip is a new approach combining features of MIP and average showing image properties in between MIP and AV.