MR-based in vivo follow-up study of Achilles tendon volume and hydration state after ankle-loading activity.

The purpose of this study was to evaluate temporal alterations of the Achilles tendon volume and hydration state after cross-country-running. Achilles tendons of six untrained participants were examined on a 3T MR-scanner before running, immediately afterwards, and in the following 24, 48, and 72 h. Using a 3D-UTE sequence, caudal (CA) and cranial (CR) mid-portion tendon areas were examined with off-resonance saturation ratios (OSR) and T2* relaxation times. Tendon volume was measured with a self-written Matlab-based automated contour detection algorithm (AVAT) in submillimeter T2-weighted MR images. A significant influence of running in caudal (P = 0.017) and cranial OSR values (P = 0.001), tendon volume (P = 0.024), and cranial T2* measurements (P = 0.046), but not in caudal T2* values (P = 0.298) were found. In detail, mean individual OSR and tendon volume measurements demonstrated a similar but inverted course in their values after exercise: initially, OSR values increased after running (and tendon volume decreased), while subsequently a decrease of OSR values (with an increase of tendon volume) could be observed. OSR and tendon volume measurements are able to detect a physiological response of tendons to a mechanical stimulus. After a transient decrease of free water in the Achilles tendon, an increase with a maximum free water content 48 h after ankle loading and a tendency toward normalization after 72 h was found.

[Diagnostic accuracy of dual energy CT angiography in patients with diabetes mellitus]. / Diagnostische Genauigkeit der Dual-energy-CT-Angiographie bei Patienten mit Diabetes mellitus.

OBJECTIVES: Peripheral arterial disease (PAD) represents a major and highly prevalent complication in patients with diabetes mellitus. The diagnostic, non-invasive work-up by computed tomography angiography (CTA) is limited in the presence of extensive calcification. The aim of the study was to determine the diagnostic accuracy of dual energy CTA (DE-CTA) for the detection and characterization of PAD in patients with diabetes mellitus. MATERIAL AND METHODS: In this study 30 diabetic patients with suspected or known PAD were retrospectively included in the analysis. All subjects underwent DE-CTA (Somatom Definition Flash, Siemens Healthcare, Erlangen, Germany) prior to invasive angiography, which served as the reference standard. Blinded analysis included assessment of the presence and degree of peripheral stenosis on curved multiplanar reformatting (MPR) and maximum intensity projections (MIP). Conventional measures of diagnostic accuracy were derived. RESULTS: Among the 30 subjects included in the analysis (83% male, mean age 70.0 ± 10.5 years, 83% diabetes type 2), the prevalence of critical stenosis in 331 evaluated vessel segments was high (30%). Dual energy CT identified critical stenoses with a high sensitivity and good specificity using curved MPR (100% and 93.1%, respectively) and MIP images (99% and 91.8%, respectively). In stratified analysis, the diagnostic accuracy was higher for stenosis pertaining to the pelvic and thigh vessels as compared with the lower extremities (curved MPR accuracy 97.1% vs. 99.2 vs. 90.9%; respectively, p < 0.001). CONCLUSION: The use of DE-CTA allows reliable detection and characterization of peripheral arterial stenosis in patients with diabetes mellitus with higher accuracy in vessels in the pelvic and thigh regions compared with the vessels in the lower legs.

Assessment of the nature of residual masses at end of treatment in lymphoma patients using volume perfusion computed tomography.

OBJECTIVES: To determine the diagnostic benefit of volume perfusion computed tomography (VPCT) at end of treatment for response assessment in lymphoma patients. METHODS: Seventy-five patients with different lymphoma subtypes were included: 50/75 patients had residual masses at end of treatment, 26/50 patients underwent VPCT at baseline and at end of treatment, and 24/50 patients only had end-of-treatment VPCTs. We evaluated the size of the main lymphoma mass, its blood flow (BF), blood volume (BV) and k-trans, calculated ratios (baseline and end of treatment) as well as sensitivity/specificity/negative (NPV)/positive predictive values (PPV). For VPCT at end of treatment, a cutoff threshold between responders and non-responders was calculated. RESULTS: For patients undergoing VPCT at baseline and end of treatment, reduction in size, BF, BV and k-trans was significant (P < 0.001). Identification of non-response was reached at: <53% reduction in size (sensitivity/specificity/accuracy/PPV/NPV of 88.89%/62.5%/80.77%/84.21%/71.43%), <15% reduction of BF (sensitivity/specificity/accuracy/PPV/NPV of 100%/37.5%/80.77%/0.26%/100%), or <45% reduction of k-trans (sensitivity/specificity/accuracy/PPV/NPV of 88.89%/75%/84.62%/88.89%/75%). In the subgroup undergoing VPCT at end of treatment, BF >18.51 ml/100 ml indicated non-responsiveness (sensitivity 92.86%, specificity 72.73%, accuracy 84%, PPV 81.25%, NPV 88.89%). CONCLUSIONS: VPCT seems adequate for assessment of lymphoma response at end of treatment. The degree of residual lymphoma perfusion at end of treatment helps to identify patients likely to remain in remission 1 year after completion of therapy. KEY POINTS: • Volume perfusion computed tomography (VPCT) offers measurements for assessing tumour response. • Perfusion parameter changes measured by VPCT correlate with antitumour therapy response. • In lymphoma, baseline and end-of-treatment perfusion parameter ratios can predict response. • Perfusion measurements after treatment identify patients likely to remain in remission.

Computer-based quantification of the Achilles tendon thickness in sequential B-mode ultrasound images: a study of feasibility and reliability.

INTRODUCTION: Assessment of the Achilles tendon thickness (ATT) using B-mode ultrasound is a common technique for clinical evaluation of chronic mid-part tendinosis. Currently used image-based assessment is limited by relatively high inter- and intra-observer variability. In this study, it was tested whether a new sequence-based automated assessment of ATT provides more reliable and reproducible results than the standard image-based procedure. MATERIALS AND METHODS: A total of 118 non-operated tendons of 59 healthy subjects (44, range 28-50 years) were analysed using an automated image based as well as a newly developed automated sequence-based method. Correlation and agreement of both methods were evaluated. The root mean square deviation (RMSD) and a Bland-Altman analysis were performed to highlight observer (n = 18 tendons) as well as reader (n = 40 tendons) dependent variabilities of both methods. RESULTS: A strong correlation was found between image and sequence-based ATT assessment (p = 0.92). The Bland-Altman analysis showed a good agreement between both methods (mean difference 0.0018, 95 % CI: -0.046; 0.05). In repetitive examinations, sequence-based analysis showed a significant reduction concerning reader- and observer-dependent variability compared to image-based assessment. The RMSD for repetitive sequence-based measurements was approximately 0.3 mm (compared to 0.6 mm for image-based measurement), respectively. CONCLUSIONS: The study shows sequence-based automated assessment of ATT being clearly superior to the standard image-based procedure. The new method provides a clear reduction of reader as well as observer-dependent variability. Due to the decreased scattering of measurement data sequence-based measurement seems especially valuable for quantification of small tendon thickness changes such as exercise-induced hypertrophy.

In vitro stent lumen visualisation of various common and newly developed femoral artery stents using MR angiography at 1.5 and 3 tesla.

OBJECTIVES: To evaluate stent lumen assessment of various commonly used and newly developed stents for the superficial femoral artery (SFA) using MR angiography (MRA) at 1.5 and 3 T. METHODS: Eleven nitinol stents and one cobalt-chromium stent were compared regarding stent lumen visualisation using a common three-dimensional MRA sequence. Maximum visible stent lumen width and contrast ratio were analysed in three representative slices for each stent type. A scoring system for lumen visualisation was applied. RESULTS: Nitinol stents showed significantly better performance than the cobalt chromium stent (P < 0.05) at 1.5 and 3 T. Maximum visible stent lumen ranged between 43.4 and 95.5 %, contrast ratio between 7.2 and 110.6 %. Regarding both field strengths, seven of the nitinol stents were classified as "suitable". Three nitinol stents were "limited", and one nitinol stent and the cobalt chromium stent were "not suitable". CONCLUSIONS: Intraluminal loss of signal and artefacts of most of the SFA stents do not markedly limit assessment of stent lumen by MRA at 1.5 and 3 T. MRA can thus be considered a valid technique for detection of relevant in-stent restenosis. Applied field strength does not strongly influence stent lumen assessment in general, but proper choice of field strength might be helpful.

Computer-based quantification of the mean Achilles tendon thickness in ultrasound images: effect of tendinosis.

BACKGROUND: B-mode measurement of the sagital diameter of the Achilles tendon based on a manual tracing (MT) procedure is partly dependent on the subjectivity of the reader. The aim of this study is to establish a standardised automatic procedure to differentiate between normal and chronically degenerated tendons. For this comparison, the tracing results of the tendon boundaries of an automatic identification (AI) process, already established with the detection of intima-media thickness, are compared with computer-assisted MT. METHODS: The detection of the tendon boundaries was performed in 115 ultrasound images including the cranial border of the calcaneal tuberosity. The measured section (starting point 4 cm away from the anterior boundary of the calcaneal tuberosity) amounted to 3 cm, and was divided into three sub-segments (1 cm each). Intra- and inter-reader/observer variability for mean and maximum Achilles tendon thickness (ATT) with AI and MT were evaluated. A normal group and a group with clinically diagnosed chronic tendon degeneration had mean and maximum ATT readings compared. RESULTS: Using MT, the intra- and inter-reader variability was 3.0% and 6.8%, respectively, using AI the variability was 1.6% and 3.9%, respectively. Mean and maximum ATT were measured systematically lower by AI compared to MT in all regions by 0.4 mm. The AI procedure was most accurate in the second segment. The mean ATT and maximum ATT were correctly detected in 93.9% and 96.6% of the images. CONCLUSION: The AI procedure detected the ATT with a high level of precision in all three segments. The most robust measurement was reached in the second segment. It eliminates most of the inter-/intra-reader variability in ATT measurement using MT. We suggest this new method could be a new gold standard for quantification of chronic disorder in Achilles tendons.

Assessment of the parenchymal blood volume by C-arm computed tomography for radioembolization dosimetry.

PURPOSE: Aim of the study was to evaluate the impact of parenchymal blood volume (PBV) C-arm CT in transarterial radioembolization (TARE) planning procedure regarding the appropriateness of segmental blood supply from selective catheter positions defined by angiographic images compared to PBV mapsto determine the influence of changed target volumes on dose calculation. MATERIAL AND METHODS: A total of 22 consecutive patients (median age, 62 years) underwent a TARE planning procedure were included in this retrospective study. Selective angiograms and selective PBV C-arm CT (right and left liver lobe) were evaluated in a blinded fashion, regarding segmental hepatic artery variants. Volumetry of target volume and dosimetry of glass and resin microspheres were performed. RESULTS: Classification of segment IV and segment I to the corresponding target vascular bed supply was correct in 91.0% (20/22) and 86.4% (19/22) for angiography and C-arm CT, respectively. Except one case, all other liver segments were classified properly to the left and right hepatic arterial supply. Based on the mismatch of the angiographic and the C-arm CT approach, changes of target volume were evident in 27.3% of patients, resulting in a mean mismatch volume of 90±54ml (range, 51-198ml) and a percentage of dose differences of 14.2±11.8% and 12.6±10.6% for the right and 12.5±8.5% and 11.1±7.8% for the left liver lobe in glass and resin microspheres, respectively. CONCLUSION: The C-arm CT approach is superior to the angiographic determination of vascular supply of specific liver segments for dosimetry before radioembolization. Especially for unexperienced interventional radiologists or for a complex anatomy, C-arm CT improves individualized dosimetry concepts.

Bronchial Artery Embolization in Hemoptysis: 10-Year Survival and Recurrence-Free Survival in Benign and Malignant Etiologies - A Retrospective Study.

Purpose: The aim of the study was to evaluate safety, effectiveness, recurrence rate and 10-year survival after bronchial artery embolization (BAE) in benign and malignant etiologies. Methods: The retrospective study includes 100 BAE procedures in 88 patients. Underlying disease was classified as benign (n = 67) and malignant (n = 21) etiologies. Immediate bleeding control and procedure safety were evaluated in all patients. In 51 (58 %) patients, follow-up data with a median follow-up time of 1015 days (range, 494 to 3727 days) were acquired to assess overall survival, time-to-recurrence of bleeding and recurrence-free survival, using Kaplan-Maier estimates to compare differences between both subgroups. Results: Immediate bleeding control was achieved after 96/100 procedures (96 %), with a minor complication rate of 5.0 %. No major complications occurred. The overall survival was 74 % after 1 year and 59 % after 5 years and 10 years. There was a significant difference in survival between the malignant and benign groups (p < 0.0001). Survival was 90 %, 80 % and 76 % at 1 year, 3 years and 10 years, respectively, in the benign group and 18 % and 0 % at 1 year and 3 years, respectively in the malignant group. The median time to recurrence of bleeding and recurrence-free survival were 239 days and 94 % after 1 year and 87 % after 10 years in the benign group, compared to 66 days and 34 % after 1 year and 0 % after 3 years in the malignant group (p = 0.0107). Conclusion: BAE is a safe and highly effective treatment option in hemoptysis. However, the recurrence rate and survival are highly dependent on the underlying disease. Key Points: • BAE is a safe and highly effective treatment option in hemoptysis.• Recurrence rate and survival are strongly dependent on the underlying disease with significantly impaired results in patients with malignant diseases. • Coil embolization is an effective BAE treatment method. Nevertheless, it should be mentioned, that reinterventions can be impeded, if embolization is performed in the proximal part of bronchial arteries. Citation Format: • Syha R, Benz T, Hetzel J et al. Bronchial Artery Embolization in Hemoptysis: 10-Year Survival and Recurrence-Free Survival in Benign and Malignant Etiologies - A Retrospective Study. Fortschr Röntgenstr 2016; 188: 1061 - 1066.

Intradiurnal Fluctuations of Off-Resonance Saturation Effects in Healthy Human Achilles Tendons Assessed with a 3D Ultrashort Echo Time MRI Sequence at 3 Tesla.

PURPOSE: The purpose of this study was to evaluate whether gravitational interstitial fluid accumulation in healthy subjects has an impact on off-resonance saturation ratios (OSR) or the volume of the Achilles tendon after a prolonged time of reduced levels of physical activity. MATERIALS AND METHODS: 7 healthy volunteers were repeatedly investigated on 3 consecutive days on a 3 T whole body MR scanner using an ultrashort echo time (UTE) imaging sequence with a Gaussian off-resonance saturation pulse at a frequency offset of 2000 Hz to calculate OSR values. For accurate volumetric quantification of the Achilles tendon, a newly developed contour detection snake algorithm was applied on high-resolution isotropic T2-weighted SPACE sequence datasets. Single-measure intraclass correlation coefficients (ICC) were calculated to estimate test-retest reliability. RESULTS: For OSR and tendon volume measurements on three consecutive days, excellent reproducibility could be achieved with ICC values above 0.96 and 0.97, respectively. Comparing the results of all three days, a statistically significant mean individual percentage decrease (- 4.1  ±â€Š1.5 %; p = 0.001) of calculated tendon OSR values was found for the evening measurements. No statistically significant difference between tendon volumes in the morning and the evening could be detected (p = 0.589). CONCLUSION: The results of this in-vivo study demonstrate a significant influence of gravitational interstitial fluid accumulation after reduced physical activity on OSR values in the Achilles tendon, but not on tendon volume. Taken together with the demonstrated excellent reproducibility, these findings are important for future studies investigating temporal changes of the Achilles tendon microstructure.

Endovascular aneurysm repair of abdominal aortic aneurysms: standards, technical options and advanced indications.

UNLABELLED: Since the introduction of endovascular aneurysm repair (EVAR) in 1991, the endovascular therapy with newest stent grafts has assumed a prominent role in the clinical management of abdominal aortic aneurysms (AAA) with a superior perioperative mortality of EVAR and an equivalent mid-term outcome, compared to open surgery. Newest techniques using chimney or periscope grafts and customized fenestrated and branched stent grafts allow the endovascular treatment of complex pararenal AAA. This article reviews EVAR in the treatment of AAA, evidence based results and advanced indication by newest interventional techniques and technical developments. KEY POINTS: • EVAR has become standard treatment of abdominal aortic aneurysm with equivalent results to open surgery.• Technical advancements and the introduction of newest stent grafts continually expand the indication of EVAR.• Chimney- and periscope grafts as well as custom-made prothesis systems allow endovascular treatment of complex para- and suprarenal aneurysms.

The prevalence of acetabular anomalies associated with pistol-grip-deformity in osteoarthritic hips.

BACKGROUND: Acetabular retroversion, excessive acetabular coverage and abnormal head-neck-junction with a so-called "pistol-grip-deformity" were added to the classical description of hip dysplasia to describe pathological hip morphology. The aim of the current study was the detection of pathological acetabular geometry in patients with an abnormal head-neck-junction. HYPOTHESIS: Femoroacetabular impingement and hip dysplasia features are frequent in patients with end-stage osteoarthritis before 60 years of age. MATERIALS AND METHODS: We analysed our data bank retrospectively for all patients who received a Total Hip Arthroplasty (THA) due to end-stage osteoarthritis before the age of 60 years. The pelvic-views and the Dunn-view of these patients were screened for an abnormal head-neck-junction by measuring the head-ratio and the alpha-angle. An orthopaedic surgeon and a radiologist did this independently. These radiographies were measured for signs of acetabular dysplasia, excessive acetabular coverage and crossing sign. RESULTS: A consecutive series of 135 total hip arthroplasties were performed in patients aged less or equal to 60 years because of end-stage osteoarthritis. From these, 81 patients were classified as having an abnormal head-neck-junction. The mean head-ratio in these 81 patients was 1.52±0.35, the mean alpha-angle was 62.5°±9.3°. The mean CE-angle of these 81 patients was 35.8°±10.4°, the mean CA-angle was 36.7°±5.7°, the mean depth-width ratio was 49.1±10, the mean extrusion index was 19.1±9.2 and the mean CCD-angle was 131.7°±7.3°. Of these 81hips, 14 had isolated pistol-grip-deformity, while 11 hips had associated dysplasia, 38 had excessive acetabular coverage, and 14 had crossing sign. In addition, a crossing sign was identified in four of the 11 dysplastic hips and 19 of the 38 of the hips having excessive acetabular coverage. There was no statistically significant difference in regard to the age between the four groups (P=0.087). In contrast, the hips that had excessive acetabular coverage had increased CE-angle (44.6°±7.2°) and decreased extrusion index (12.6±6.5) (P<0.001), while dysplastic hips had increased roof obliquity (17.5°±4.5°) and increased extrusion index (29.6±9.1), as well as decreased CE-angle (20.7°±3.0°) (P<0.001). CONCLUSION: There is a high coincidence of radiographic findings associated with an abnormal head-neck-junction consisting in excessive acetabular coverage and retroversion as well as hip dysplasia. These results advocate for restoring of the normal anatomy at the early stage to prevent end-stage osteoarthritis. LEVEL OF EVIDENCE: Level IV retrospective historical study.

Achillodynia - radiological imaging of acute and chronic overuse injuries of the achilles tendon.

In the past decades the incidence of acute and chronic disorders of the Achilles tendon associated with sport-induced overuse has steadily increased. Besides acute complete or partial ruptures, achillodynia (Achilles tendon pain syndrome), which is often associated with tendon degeneration, represents the most challenging entity regarding clinical diagnostics and therapy. Therefore, the use of imaging techniques to differentiate tendon disorders and even characterize structure alterations is of growing interest. This review article discusses the potential of different imaging techniques with respect to the diagnosis of acute and chronic tendon disorders. In this context, the most commonly used imaging techniques are magnetic resonance imaging (MRI), B-mode ultrasound, and color-coded Doppler ultrasound (US). These modalities allow the detection of acute tendon ruptures and advanced chronic tendon disorders. However, the main disadvantages are still the low capabilities in the detection of early-stage degeneration and difficulties in the assessment of treatment responses during follow-up examinations. Furthermore, differentiation between chronic partial ruptures and degeneration remains challenging. The automatic contour detection and texture analysis may allow a more objective and quantitative interpretation, which might be helpful in the monitoring of tendon diseases during follow-up examinations. Other techniques to quantify tendon-specific MR properties, e. g. based on ultrashort echo time (UTE) sequences, also seem to have great potential with respect to the precise detection of degenerative tendon disorders and their differentiation at a very early stage.

Indications for total hip arthroplasty in young adults - idiopathic osteoarthritis seems to be overestimated.

PURPOSE: New aspects like acetabular overcoverage, acetabular retroversion and proximal femoral head-neck dysplasia have been detected as a main cause of osteoarthritis. The study addresses the detection of reasons for osteoarthritis requiring THA in young adults. We wanted to prove the hypothesis that idiopathic reasons play an overestimated role in osteoarthritis in young patients. MATERIALS AND METHODS: 228 total hip arthroplasties in patients aged ≤ 60 years were performed at our institution. After the detection of the primary reasons for osteoarthritis of the hip, the radiographic pictures of all other patients were analyzed for radiographic signs of hip dysplasia or femoroacetabular impingement. For interobserver quality testing, this was done by two different observers. RESULTS: 132 patients were initially classified as having idiopathic osteoarthritis of the hip.  There was no pathological radiographic finding in only 5 patients. 80 patients presented a reduced head-neck offset as a sign of CAM impingement with a mean head ratio of 1.52 ±â€Š0.35 and an alpha angle of 62.8 ±â€Š9.28°. 21 patients presented a figure-8 sign as an indicator for acetabular retroversion. 68 patients presented at least one radiographic finding for "dysplasia" and 60 patients at least one radiographic finding for excessive "overcoverage". The Bland-Altman Plot for testing interobserver reliability demonstrated good interobserver agreement. CONCLUSION: Idiopathic OA in young adults is rare if you look hard enough for the underlying pathology. If treated, patients might benefit and THA could be postponed for several years.

Human metapneumovirus (HMPV) associated pulmonary infections in immunocompromised adults--initial CT findings, disease course and comparison to respiratory-syncytial-virus (RSV) induced pulmonary infections.

AIM: To describe computed tomography (CT)-imaging findings in human metapneumovirus (HMPV)-related pulmonary infection as well as their temporal course and to analyze resemblances/differences to pulmonary infection induced by the closely related respiratory-syncytial-virus (RSV) in immunocompromised patients. MATERIALS AND METHODS: Chest-CT-scans of 10 HMPV PCR-positive patients experiencing pulmonary symptoms were evaluated retrospectively with respect to imaging findings and their distribution and results were then compared with data acquired in 13 patients with RSV pulmonary infection. Subsequently, we analyzed the course of chest-findings in HMPV patients. RESULTS: In HMPV, 8/10 patients showed asymmetric pulmonary findings, whereas 13/13 patients with RSV-pneumonia presented more symmetrical bilateral pulmonary infiltrates. Image analysis yielded in HMPV patients following results: ground-glass-opacity (GGO) (n=6), parenchymal airspace consolidations (n=5), ill-defined nodular-like centrilobular opacities (n=9), bronchial wall thickening (n=8). In comparison, results in RSV patients were: GGO (n=10), parenchymal airspace consolidations (n=9), ill-defined nodular-like centrilobular opacities (n=10), bronchial wall thickening (n=4). In the course of the disease, signs of acute HMPV interstitial pneumonia regressed transforming temporarily in part into findings compatible with bronchitis/bronchiolitis. CONCLUSIONS: Early chest-CT findings in patients with HMPV-related pulmonary symptoms are compatible with asymmetric acute interstitial pneumonia accompanied by signs of bronchitis; the former transforming with time into bronchitis and bronchiolitis before they resolve. On the contrary, RSV-induced pulmonary infection exhibits mainly symmetric acute interstitial pneumonia.

Automated volumetric assessment of the Achilles tendon (AVAT) using a 3D T2 weighted SPACE sequence at 3T in healthy and pathologic cases.

PURPOSE: Achilles tendinopathy has been reported to be frequently associated with increasing volume of the tendon. This work aims at reliable and accurate volumetric quantification of the Achilles tendon using a newly developed contour detection algorithm applied on high resolution MRI data sets recorded at 3T. MATERIALS AND METHODS: A total of 26 healthy tendons and 4 degenerated tendons were examined for this study. Automated identification (AI) of tendon boundaries was performed in transverse slices with isotropic resolution (0.8mm) gained with a T2-weighted SPACE sequence at 3T. For AI a snake algorithm was applied and compared to manual tracing (MT). RESULTS: AI was feasible in all examined tendons without further correction. AI of both tendons was performed in each participant within 2 min (2 × 37 slices) compared to MT lasting 20 min. MT and AI showed excellent agreement and correlation (R(2) = 0.99, p<0.0001). AI provided a reduction of measurement error (0.4 cm(3) vs. 0.5 cm(3)) and coefficient of variation (1% vs. 2%). DISCUSSION: Compared to MT the AI allows assessment of tendon volumes in highly resolved MRI data in a more accurate and reliable time-saving way. Therefore automated volume detection is seen as a helpful clinical tool for evaluation of small volumetric changes of the Achilles tendon.

Magnetization transfer in human Achilles tendon assessed by a 3D ultrashort echo time sequence: quantitative examinations in healthy volunteers at 3T.

PURPOSE: Magnetization transfer contrast (MTC) imaging provides insight into interactions between free and bounded water. Newly developed ultrashort echo time (UTE) sequences implemented on whole-body magnetic resonance (MR) scanners allow MTC imaging in tissues with extremely fast signal decay such as tendons. The aim of this study was to develop a technique for the quantification of the MT effect in healthy Achilles tendons in-vivo at 3 Tesla. MATERIALS AND METHODS: 16 normal tendons of volunteers with no history of tendinopathy were examined using a 3D-UTE sequence with a rectangular on-resonant excitation pulse and a Fermi-shaped off-resonant MT preparation pulse. The frequency of the MT pulse was varied from 1 to 5 kHz. MT effects were calculated in terms of the MT ratio (MTR) between measurements without and with MT preparation. Direct saturation effects of MT preparation on the signal intensity were evaluated using numerical simulation of Bloch equations. One patient with tendinopathy was examined to exemplarily show changes of MTR under pathologic conditions. RESULTS: Calculation of MTR data was feasible in all examined tendons and showed a decrease from 0.53 ± 0.05 to 0.25 ± 0.03 (1 kHz to 5 kHz) for healthy volunteers. Evaluation of variation with gender and dominance of ankle revealed no significant differences (p > 0.05). In contrast, the patient with confirmed tendinopathy showed MTR values between 0.36 (1 kHz) and 0.19 (5 kHz). CONCLUSION: MT effects in human Achilles tendons can be reliably assessed in-vivo using a 3D UTE sequence at 3 T. All healthy tendons showed similar MTR values (coefficient of variation 10.0 ± 1.2 %). The examined patient showed a clearly different MT effect revealing a changed microstructure in the case of tendinopathy.

Estimation of radiation exposure of prospectively triggered 128-slice computed tomography coronary angiography.

PURPOSE: To estimate the effective dose of prospectively triggered computed tomography coronary angiography (CTCA) in step-and-shoot (SAS) mode, depending on the tube current and tube voltage modulation. MATERIALS AND METHODS: For dose measurements, an Alderson-Rando-phantom equipped with thermoluminescent dosimeters was used. The effective dose was calculated according to ICRP 103. Exposure was performed on a 128-slice single source scanner providing a collimation of 128 × 0.6 mm and a rotation time of 0.38 seconds. CTCA in the SAS mode was acquired with variation of the tube current (160, 240, 320 mAs) and tube voltage (100, 120, 140 kV) at a simulated heart rate of 60 beats per minute and a scan range of 13.5 cm. RESULTS: Depending on gender, tube current and tube voltage, the effective dose of a CTCA in SAS mode varies from 2.8 to 10.8 mSv. Due to breast tissue in the primary scan range, exposure in the case of females showed an increase of up to 60.0 ± .4% compared to males. The dose reduction achieved by a reduction of tube current showed a significant positive, linear correlation to effective dose with a possible decrease in the effective dose of up to 60.4% (r = 0.998; p = 0.044). Disproportionately high, the estimated effective dose can be reduced by using a lower tube voltage with a dose reduction of up to 52.4%. CONCLUSION: Further substantial dose reduction of low-dose CTCA in SAS mode can be achieved by adapting the tube current and tube voltage and should be implemented in the clinical routine, i. e. adapting those protocol parameters to patient body weight.