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OBJECTIVES: To compare the accuracy and precision of 3D-Dixon and 2D-SSFP MR-imaging for assessment of aortic diameter in Marfan patients. METHODS: This prospective single-center study investigated respiratory-gated 3D-Dixon and breath-hold 2D-SSFP non-contrast MR-imaging at 3 T in 47 Marfan patients (36.0 ± 13.2 years, 28â,19â). Two radiologists performed individual diameter measurements at five levels of the thoracic aorta and evaluated image quality on a four-grade scale (1 = poor, 4 = excellent) and artifacts (1 = severe, 4 = none). Aortic root diameters acquired by echocardiography served as a reference standard. Intraclass correlation coefficient, Bland-Altman analyses, F-test, t-test, and regression analyses were used to assess agreement between observers and methods. RESULTS: Greatest aortic diameters were observed at the level of the sinuses of Valsalva (SOV) for 3D-Dixon (38.2 ± 6.8 mm) and 2D-SSFP (38.3 ± 7.1 mm) (p = 0.53). Intra- and interobserver correlation of diameter measurements was excellent at all aortic levels for both 3D-Dixon (r = 0.94-0.99 and r = 0.94-0.98) and 2D-SSFP (r = 0.96-1.00 and r = 0.95-0.99). 3D-Dixon-derived and 2D-SSFP-derived diameter measurements at the level of the SOV revealed a strong correlation with echocardiographic measurements (r = 0.92, p < 0.001 and r = 0.93, p < 0.001, respectively). The estimated mean image quality at the level of SOV was higher for 2D-SSFP compared to that for 3D-Dixon (3.3 (95%-CI: 3.1-3.5) vs. 2.9 (95%-CI: 2.7-3.1)) (p < 0.001). Imaging artifacts were less at all aortic levels for 3D-Dixon compared to 2D-SSFP (3.4-3.8 vs. 2.8-3.1) (all p < 0.002). CONCLUSION: Respiratory-gated 3D-Dixon and breath-hold 2D-SSFP MR-imaging provide accurate and precise aortic diameter measurements. We recommend 3D-Dixon imaging for monitoring of aortic diameter in Marfan patients due to fewer imaging artifacts and the possibility of orthogonal multiplanar reformations of the aortic root. KEY POINTS: ⢠Respiratory-gated 3D-Dixon and breath-hold 2D-SSFP imaging provide accurate and precise aortic diameter measurements in patients suffering from Marfan syndrome. ⢠Imaging artifacts are stronger in 2D-SFFP imaging than in 3D-Dixon imaging. ⢠We recommend 3D-Dixon imaging for monitoring of aortic diameter in Marfan patients due to fewer imaging artifacts and the possibility of orthogonal multiplanar reformations.
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Síndrome de Marfan , Humanos , Síndrome de Marfan/diagnóstico por imagen , Estudios Prospectivos , Angiografía por Resonancia Magnética/métodos , Medios de Contraste , Imagenología Tridimensional/métodos , Imagen por Resonancia Magnética , Reproducibilidad de los ResultadosRESUMEN
BACKGROUND: Four-dimensional (4D) flow cardiovascular magnetic resonance (CMR) is feasible for portal blood flow evaluation after placement of transjugular intrahepatic portosystemic shunts (TIPS) in patients with liver cirrhosis. However, clinical acceptance of 4D flow CMR in TIPS patients is limited due to the lack of validation studies. The purpose of this study was to validate 4D flow CMR-derived measurements in TIPS stent grafts using a three-dimensional (3D)-printed flow phantom. METHODS: A translucent flow phantom of the portal vasculature was 3D-printed. The phantom consisted of the superior mesenteric vein and the splenic vein draining into the portal vein, the TIPS-tract, and the hepatic vein. A TIPS stent graft (Gore® Viatorr®) was positioned within the TIPS-tract. Superior mesenteric vein and splenic vein served as inlets for blood-mimicking fluid. 4D flow CMR acquisitions were performed at 3T at preset flow rates of 0.8 to 2.8 l/min using velocity encoding of both 1.0 and 2.0 m/s. Flow rates and velocities were measured at predefined levels in the portal vasculature and within the stent graft. Accuracy of 4D flow CMR was assessed through linear regression with reference measurements obtained by flow sensors and two-dimensional (2D) phase contrast (PC) CMR. Intra- and interobserver agreement were assessed through Bland-Altman analyses. RESULTS: At a velocity encoding of 2.0 m/s, 4D flow CMR-derived flow rates and velocities showed an excellent correlation with preset flow rates and 2D PC CMR-derived flow velocities at all vascular levels and within the stent graft (all r ≥ 0.958, p ≤ 0.003). At a velocity encoding of 1.0 m/s, aliasing artifacts were present within the stent graft at flow rates ≥ 2.0 l/min. 4D flow CMR-derived measurements revealed high intra- and interobserver agreement. CONCLUSIONS: The in vitro accuracy and precision of 4D flow CMR is unaffected by the presence of TIPS stent grafts, suggesting that 4D flow CMR may be used to monitor TIPS patency in patients with liver cirrhosis.
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Cirrosis Hepática , Stents , Humanos , Valor Predictivo de las Pruebas , Espectroscopía de Resonancia Magnética , Impresión TridimensionalRESUMEN
BACKGROUND: Aortic valve repair has become a treatment option for adults with symptomatic bicuspid (BAV) or unicuspid (UAV) aortic valve insufficiency. Our aim was to demonstrate the feasibility of 4D flow cardiovascular magnetic resonance (CMR) to assess the impact of aortic valve repair on changes in blood flow dynamics in patients with symptomatic BAV or UAV. METHODS: Twenty patients with adult congenital heart disease (median 35 years, range 18-64; 16 male) and symptomatic aortic valve regurgitation (15 BAV, 5 UAV) were prospectively studied. All patients underwent 4D flow CMR before and after aortic valve repair. Aortic valve regurgitant fraction and systolic peak velocity were estimated. The degree of helical and vortical flow was evaluated according to a 3-point scale. Relative flow displacement and wall shear stress (WSS) were quantified at predefined levels in the thoracic aorta. RESULTS: All patients underwent successful aortic valve repair with a significant reduction of aortic valve regurgitation (16.7 ± 9.8% to 6.4 ± 4.4%, p < 0.001) and systolic peak velocity (2.3 ± 0.9 to 1.9 ± 0.4 m/s, p = 0.014). Both helical flow (1.6 ± 0.6 vs. 0.9 ± 0.5, p < 0.001) and vortical flow (1.2 ± 0.8 vs. 0.5 ± 0.6, p = 0.002) as well as both flow displacement (0.3 ± 0.1 vs. 0.25 ± 0.1, p = 0.031) and WSS (0.8 ± 0.2 N/m2 vs. 0.5 ± 0.2 N/m2, p < 0.001) in the ascending aorta were significantly reduced after aortic valve repair. CONCLUSIONS: 4D flow CMR allows assessment of the impact of aortic valve repair on changes in blood flow dynamics in patients with bicuspid aortic valve disease.
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Aorta Torácica/diagnóstico por imagen , Insuficiencia de la Válvula Aórtica/cirugía , Válvula Aórtica/anomalías , Aortografía , Anuloplastia de la Válvula Cardíaca , Enfermedades de las Válvulas Cardíacas/cirugía , Hemodinámica , Interpretación de Imagen Asistida por Computador , Imagen por Resonancia Cinemagnética , Adulto , Aorta Torácica/fisiopatología , Válvula Aórtica/diagnóstico por imagen , Válvula Aórtica/fisiopatología , Válvula Aórtica/cirugía , Insuficiencia de la Válvula Aórtica/diagnóstico por imagen , Insuficiencia de la Válvula Aórtica/fisiopatología , Enfermedad de la Válvula Aórtica Bicúspide , Velocidad del Flujo Sanguíneo , Estudios de Factibilidad , Femenino , Enfermedades de las Válvulas Cardíacas/diagnóstico por imagen , Enfermedades de las Válvulas Cardíacas/fisiopatología , Humanos , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Estudios Prospectivos , Recuperación de la Función , Factores de Tiempo , Resultado del Tratamiento , Adulto JovenRESUMEN
Bisphosphonates are the most widely prescribed pharmacologic treatment for osteoporosis and reduce fracture risk in postmenopausal women by up to 50%. However, in the past decade these drugs have been associated with atypical femoral fractures (AFFs), rare fractures with a transverse, brittle morphology. The unusual fracture morphology suggests that bisphosphonate treatment may impair toughening mechanisms in cortical bone. The objective of this study was to compare the compositional and mechanical properties of bone biopsies from bisphosphonate-treated patients with AFFs to those from patients with typical osteoporotic fractures with and without bisphosphonate treatment. Biopsies of proximal femoral cortical bone adjacent to the fracture site were obtained from postmenopausal women during fracture repair surgery (fracture groups, n = 33) or total hip arthroplasty (nonfracture groups, n = 17). Patients were allocated to five groups based on fracture morphology and history of bisphosphonate treatment [+BIS Atypical: n = 12, BIS duration: 8.2 (3.0) y; +BIS Typical: n = 10, 7.7 (5.0) y; +BIS Nonfx: n = 5, 6.4 (3.5) y; -BIS Typical: n = 11; -BIS Nonfx: n = 12]. Vibrational spectroscopy and nanoindentation showed that tissue from bisphosphonate-treated women with atypical fractures was harder and more mineralized than that from bisphosphonate-treated women with typical osteoporotic fractures. In addition, fracture mechanics measurements showed that tissue from patients treated with bisphosphonates had deficits in fracture toughness, with lower crack-initiation toughness and less crack deflection at osteonal boundaries than that of bisphosphonate-naïve patients. Together, these results suggest a deficit in intrinsic and extrinsic toughening mechanisms, which contribute to AFFs in patients treated with long-term bisphosphonates.
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Conservadores de la Densidad Ósea/uso terapéutico , Difosfonatos/uso terapéutico , Fémur/efectos de los fármacos , Fracturas Osteoporóticas/tratamiento farmacológico , Anciano , Anciano de 80 o más Años , Densidad Ósea/efectos de los fármacos , Femenino , Humanos , Osteoporosis/tratamiento farmacológico , Posmenopausia/efectos de los fármacosRESUMEN
Mucopolysaccharidosis-I (MPS-I) is a lysosomal storage disease (LSD) caused by inactivating mutations of IDUA, encoding the glycosaminoglycan-degrading enzyme α-l-iduronidase. Although MPS-I is associated with skeletal abnormalities, the impact of IDUA deficiency on bone remodeling is poorly defined. Here we report that Idua-deficient mice progressively develop a high bone mass phenotype with pathological lysosomal storage in cells of the osteoblast lineage. Histomorphometric quantification identified shortening of bone-forming units and reduced osteoclast numbers per bone surface. This phenotype was not transferable into wild-type mice by bone marrow transplantation (BMT). In contrast, the high bone mass phenotype of Idua-deficient mice was prevented by BMT from wild-type donors. At the cellular level, BMT did not only normalize defects of Idua-deficient osteoblasts and osteocytes but additionally caused increased osteoclastogenesis. Based on clinical observations in an individual with MPS-I, previously subjected to BMT and enzyme replacement therapy (ERT), we treated Idua-deficient mice accordingly and found that combining both treatments normalized all histomorphometric parameters of bone remodeling. Our results demonstrate that BMT and ERT profoundly affect skeletal remodeling of Idua-deficient mice, thereby suggesting that individuals with MPS-I should be monitored for their bone remodeling status, before and after treatment, to avoid long-term skeletal complications.
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Remodelación Ósea , Iduronidasa/uso terapéutico , Mucopolisacaridosis I/fisiopatología , Mucopolisacaridosis I/terapia , Animales , Trasplante de Médula Ósea , Proliferación Celular , Células Cultivadas , Niño , Terapia Combinada , Modelos Animales de Enfermedad , Terapia de Reemplazo Enzimático , Femenino , Humanos , Iduronidasa/deficiencia , Iduronidasa/genética , Masculino , Ratones , Ratones Endogámicos C57BL , Mucopolisacaridosis I/patología , Osteoclastos/enzimologíaRESUMEN
The interest in plasmonic electro-optical modulators with nanoscale footprint and ultrafast low-energy performance has generated a demand for precise multiphysics modeling of the electrical and optical properties of plasmonic nanostructures. We perform combined simulations that account for the interaction of highly confined nearfields with charge accumulation and depletion on the nanoscale. Validation of our numerical model is done by comparison to a recently published reflective meta-absorber. The simulations show excellent agreement to the experimental mid-infrared data. We then use our model to propose electro-optical modulation of the extinction cross-section of a gold dimer nanoantenna at the telecom wavelength of 1550 nm. An ITO gap-loaded nanoantenna structure allows us to achieve a normalized modulation of 45% at 1550 nm, where the gap-load design circumvents resonance pinning of the structure. Resonance pinning limits the performance of simplistic designs such as a uniform coating of the nanoantenna with a sheet of indium tin oxide, which we also present for comparison. This large value is reached by a reduction of the capacitive coupling of the antenna arms, which breaks the necessity of a large volume overlap between the charge distribution and the optical nearfield. A parameter exploration shows a weak reliance on the exact device dimensions, as long as strong coupling inside the antenna gap is ensured. These results open the way for a new method in electro-optical tuning of plasmonic structures and can readily be adapted to plasmonic waveguides, metasurfaces and other electro-optical modulators.
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The objective of this study was to elucidate micromechanical properties of Biodentine and two experimental calcium silicate cements (CSCs) using Reference Point Indentation (RPI). Biomechanical characteristics of the cement type and the effects of a radiopacifier, liquid components, acid etching treatment and bioactivation in simulated body fluid (SBF) were investigated by measuring the microhardness, average unloading slope (Avg US) and indentation distance increase (IDI). Biodentine had a greater microhardness than the experimental CSCs, while the Avg US and IDI values were not significantly different among investigated materials. There was a statistically significant difference in microhardness and IDI values between pure CSCs and radiopacified cements (p < 0.05). Micromechanical properties were not affected by different liquid components used. Acid-etching treatment reduced Biodentine's microhardness while cements' immersion in SBF resulted in greater microhardness and higher IDI values compared to the control group. Clearly, the physiological environment and the cements' composition affect their surface micromechanical properties. The addition of calcium chloride and CSCs' immersion in SBF are beneficial for CSCs' micromechanical performance, while the addition of radiopacifiers and acid etching treatment weaken the CSCs' surface. Application of RPI aids with the characterization of micromechanical properties of synthetic materials' surfaces.
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Compuestos de Calcio , Materiales Dentales , Ensayo de Materiales/métodos , Fenómenos Mecánicos , Microtecnología/métodos , Silicatos , Propiedades de SuperficieRESUMEN
OBJECTIVES: Health risks due to chronic exposure to highly fluoridated groundwater could be underestimated because fluoride might not only influence the teeth in an aesthetic manner but also seems to led to dentoalveolar structure changes. Therefore, we studied the tooth and alveolar bone structures of Dorper sheep chronically exposed to very highly fluoridated and low calcium groundwater in the Kalahari Desert in comparison to controls consuming groundwater with low fluoride and normal calcium levels within the World Health Organization (WHO) recommended range. MATERIALS AND METHODS: Two flocks of Dorper ewes in Namibia were studied. Chemical analyses of water, blood and urine were performed. Mineralized tissue investigations included radiography, HR-pQCT analyses, histomorphometry, energy-dispersive X-ray spectroscopy and X-ray diffraction-analyses. RESULTS: Fluoride levels were significantly elevated in water, blood and urine samples in the Kalahari group compared to the low fluoride control samples. In addition to high fluoride, low calcium levels were detected in the Kalahari water. Tooth height and mandibular bone quality were significantly decreased in sheep, exposed to very high levels of fluoride and low levels of calcium in drinking water. Particularly, bone volume and cortical thickness of the mandibular bone were significantly reduced in these sheep. CONCLUSIONS: The current study suggests that chronic environmental fluoride exposure with levels above the recommended limits in combination with low calcium uptake can cause significant attrition of teeth and a significant impaired mandibular bone quality. CLINICAL RELEVANCE: In the presence of high fluoride and low calcium-associated dental changes, deterioration of the mandibular bone and a potential alveolar bone loss needs to be considered regardless whether other signs of systemic skeletal fluorosis are observed or not.
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Pérdida de Hueso Alveolar/inducido químicamente , Calcio/análisis , Agua Potable/química , Exposición a Riesgos Ambientales , Fluoruros/análisis , Enfermedades de las Ovejas/inducido químicamente , Enfermedades Dentales/inducido químicamente , Animales , Namibia , Ovinos , Oveja Doméstica , Espectrometría por Rayos X , Difracción de Rayos XRESUMEN
BACKGROUND: An abdominal aortic aneurysm (AAA) is defined as a localized dilatation of the abdominal aorta of ≥â3âcm. With a prevalence of 4-8â%, AAA is one of the most common vascular diseases in Western society. Radiological imaging is an elementary component in the diagnosis, monitoring, and treatment planning of AAA patients. METHOD: This is a narrative review article on preoperative imaging strategies of AAA, incorporating expert opinions based on the current literature and standard-of-care practices from our own center. Examples are provided to illustrate clinical cases from our institution. RESULTS AND CONCLUSION: Radiological imaging plays a pivotal role in the initial diagnosis and monitoring of patients with AAA. Ultrasound is the mainstay imaging modality for AAA screening and surveillance. Contrast-enhanced CT angiography is currently considered the gold standard for preoperative imaging and image-based treatment planning in AAA repair. New non-contrast MR angiography techniques are robustly applicable and allow precise determination of aortic diameters, which is of critical importance, particularly with regard to current diameter-based surgical treatment guidelines. 3D imaging with multiplanar reformation and automatic centerline positioning enables more accurate assessment of the maximum aortic diameter. Modern imaging techniques such as 4D flow MRI have the potential to further improve individualized risk stratification in patients with AAA. KEY POINTS: · Ultrasound is the mainstay imaging modality for AAA screening and monitoring. · Contrast-enhanced CT angiography is the gold standard for preoperative imaging in AAA repair. · Non-contrast MR angiography allows for accurate monitoring of aortic diameters in AAA patients. · Measurement of aortic diameters is more accurate with 3D-CT/MRI compared to ultrasound. · Research seeks new quantitative imaging biomarkers for AAA risk stratification, e.âg., using 4D flow MRI.
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Aneurisma de la Aorta Abdominal , Humanos , Aneurisma de la Aorta Abdominal/diagnóstico por imagen , Aneurisma de la Aorta Abdominal/cirugía , Aorta Abdominal/diagnóstico por imagen , Ultrasonografía/métodos , Angiografía por Tomografía Computarizada , Imagen por Resonancia MagnéticaRESUMEN
Background & Aims: Cirrhosis is associated with an increased surgical morbidity and mortality. Portal hypertension and the surgery type have been established as critical determinants of postoperative outcome. We aim to evaluate the hypothesis that preoperative transjugular intrahepatic portosystemic shunt (TIPS) placement in patients with cirrhosis is associated with a lower incidence of in-house mortality/liver transplantation (LT) after surgery. Methods: A retrospective database search for the years 2010-2020 was carried out. We identified 64 patients with cirrhosis who underwent surgery within 3 months after TIPS placement and 131 patients with cirrhosis who underwent surgery without it (controls). Operations were categorised into low-risk and high-risk procedures. The primary endpoint was in-house mortality/LT. We analysed the influence of high-risk surgery, preoperative TIPS placement, age, sex, baseline creatinine, presence of ascites, Chronic Liver Failure Consortium Acute Decompensation (CLIF-C AD), American Society of Anesthesiologists (ASA), and model for end-stage liver disease (MELD) scores on in-house mortality/LT by multivariable Cox proportional hazards regression. Results: In both the TIPS and the control cohort, most patients presented with a Child-Pugh B stage (37/64, 58% vs. 70/131, 53%) at the time of surgery, but the median MELD score was higher in the TIPS cohort (14 vs. 11 points). Low-risk and high-risk procedures amounted to 47% and 53% in both cohorts. The incidence of in-house mortality/LT was lower in the TIPS cohort (12/64, 19% vs. 52/131, 40%), also when further subdivided into low-risk (0/30, 0% vs. 10/61, 16%) and high-risk surgery (12/34, 35% vs. 42/70, 60%). Preoperative TIPS placement was associated with a lower rate for postoperative in-house mortality/LT (hazard ratio 0.44, 95% CI 0.19-1.00) on multivariable analysis. Conclusions: A preoperative TIPS might be associated with reduced postoperative in-house mortality in selected patients with cirrhosis. Impact and implications: Patients with cirrhosis are at risk for more complications and a higher mortality after surgical procedures. A transjugular intrahepatic portosystemic shunt (TIPS) is used to treat complications of cirrhosis, but it is unclear if it also helps to lower the risk of surgery. This study takes a look at complications and mortality of patients undergoing surgery with or without a TIPS, and we found that patients with a TIPS develop less complications and have an improved survival. Therefore, a preoperative TIPS should be considered in selected patients, especially if indicated by ascites.
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Background: Neurofibromatosis type 1 (NF1) is associated with the development of benign (BPNST) and malignant (MPNST) peripheral nerve sheath tumors. Recently described atypical neurofibromas (ANF) are considered pre-malignant precursor lesions to MPNSTs. Previous studies indicate that diffusion-weighted magnetic resonance imaging (DW-MRI) can reliably discriminate MPNSTs from BPNSTs. We therefore investigated the diagnostic accuracy of DW-MRI for the discrimination of benign, atypical, and malignant peripheral nerve sheath tumors. Methods: In this prospective explorative single-center phase II diagnostic study, 44 NF1 patients (23 male; 30.1â ±â 11.8 years) underwent DW-MRI (b-values 0-800 s/mm²) at 3T. Two radiologists independently assessed mean and minimum apparent diffusion coefficients (ADCmean/min) in areas of largest tumor diameters and ADCdark in areas of lowest signal intensity by manual contouring of the tumor margins of 60 BPNSTs, 13 ANFs, and 21 MPNSTs. Follow-up of ≥â 24 months (BPNSTs) or histopathological evaluation (ANFsâ +â MPNSTs) served as diagnostic reference standard. Diagnostic ADC-based cut-off values for discrimination of the three tumor groups were chosen to yield the highest possible specificity while maintaining a clinically acceptable sensitivity. Results: ADC values of pre-malignant ANFs clustered between BPNSTs and MPNSTs. Best BPNST vs. ANFâ +â MPNST discrimination was obtained using ADCdark at a cut-off value of 1.6â ×â 10-3 mm2/s (85.3% sensitivity, 93.3% specificity), corresponding to an AUC of 94.3% (95% confidence interval: 85.2-98.0). Regarding BPNSTâ +â ANF vs. MPNST, best discrimination was obtained using an ADCdark cut-off value of 1.4â ×â 10-3 mm2/s (83.3% sensitivity, 94.5% specificity). Conclusions: DW-MRI using ADCdark allows specific and noninvasive discrimination of benign, atypical, and malignant nerve sheath tumors in NF1.
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Portal hypertension is the underlying reason for complications like ascites or gastrointestinal varices in end-stage liver disease. On rare occasions, portal hypertension may be caused by extrahepatic arterioportal shunts. This report illustrates an outstanding case of extrahepatic arterioportal shunting as an uncommon cause of TIPS-refractory portal hypertension. Four-dimensional flow magnetic resonance imaging (4D flow MRI) is a novel non-invasive technique that enables the visualization of complex vascular disorders but has not been put into daily clinical practice in hepatology. In this case, 4D flow MRI enabled the visualization of three abdominal arterioportal shunts as the reason for TIPS-refractory portal hypertension. The quantification of individual shunt flow rates by 4D flow MRI guided our treatment strategy consisting of embolization during interventional angiography and surgical resection of all three arterioportal shunts. In conclusion, this case highlights the usefulness of 4D flow MRI for evaluating shunt flow in cases of complex vascular disorders and portal-hypertensive complications, thus helping to guide therapeutic decisions and monitoring the therapeutic success.
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Embolización Terapéutica , Hipertensión Portal , Humanos , Hipertensión Portal/etiología , Hipertensión Portal/cirugía , Imagen por Resonancia Magnética/efectos adversos , Embolización Terapéutica/efectos adversosRESUMEN
Gastrointestinal bleeding, as a potentially life-threatening condition, is typically diagnosed by radiation-based imaging modalities like computed tomography or more invasively catheter-based angiography. Endoscopy enables examination of the upper gastrointestinal tract and the colon but not of the entire small bowel. Magnetic Particle Imaging (MPI) enables non-invasive, volumetric imaging without ionizing radiation. The aim of this study was to evaluate the feasibility of detecting gastrointestinal bleeding by single- and multi-contrast MPI using human-sized organs. A 3D-printed small bowel phantom and porcine small bowel specimens were prepared with a defect within the bowel wall as the source of a bleeding. For multi-contrast MPI, the bowel lumen was filled with an intestinal tracer representing an orally administered tracer. MPI was performed to evaluate the fluid exchange between the vascular compartment of the bowel wall and the lumen while a blood pool tracer was applied. Leakage of the blood pool tracer was observed to the bowel lumen. Multi-contrast MPI enabled co-registration of both tracers at the same location within the bowel lumen indicating gastrointestinal bleeding. Single- and multi-contrast MPI are feasible to visualize gastrointestinal bleeding. Therefore, MPI might emerge as a useful tool for radiation-free detection of bleeding within the entire gastrointestinal tract.
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Imagen por Resonancia Magnética , Nanopartículas de Magnetita , Humanos , Animales , Porcinos , Imagen por Resonancia Magnética/métodos , Fantasmas de Imagen , Hemorragia Gastrointestinal/diagnóstico por imagen , Fenómenos MagnéticosRESUMEN
While fractures of the distal femur are often considered as fragility fractures, detailed knowledge of the bone microarchitecture at this skeletal site is largely unavailable. Initial evaluation of a patient cohort with distal femur fractures showed a markedly increased occurrence in elderly women. The purpose of this study was to determine the extent to which demographic characteristics of distal femur fractures are reflected by general age- and sex-specific variations in local microarchitectural parameters. Fifty cadaveric femora were collected from 25 subjects (12 females, 13 males, age 25-97 years). A volume of interest within 3 cm proximal to the condyles was analyzed using high-resolution peripheral quantitative computed tomography (HR-pQCT), which revealed impaired trabecular and cortical bone microarchitecture in women compared to men as well as in osteoporotic compared to normal or osteopenic subjects, as classified by dual-energy X-ray absorptiometry (DXA) T-score. Linear regression analyzes showed negative associations between age and HR-pQCT parameters in women (e.g., cortical thickness -14 µm/year, 95% CI: -21 to -7 µm/year), but not in men (e.g., cortical thickness 1 µm/year, 95% CI: -12 to 14 µm/year). HR-pQCT parameters showed strong positive associations with areal bone mineral density (aBMD) determined by DXA at the hip in both sexes. Taken together, our findings suggest that female sex, advanced age, and low aBMD represent major risk factors for impaired microarchitecture at the distal femur. Both the diagnostic value of DXA for predicting distal femur fractures and the efficacy of bone-specific agents on fracture risk reduction should be investigated in the future.
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Densidad Ósea , Fracturas Óseas , Absorciometría de Fotón/métodos , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Fémur/diagnóstico por imagen , Fracturas Óseas/epidemiología , Humanos , Masculino , Persona de Mediana Edad , Radio (Anatomía) , Tibia , Tomografía Computarizada por Rayos X/métodosRESUMEN
Degradation at the modular head-neck interface in total hip arthroplasty (THA) is predominately expressed in the form of corrosion and fretting, potentially causing peri-prosthetic failure by adverse reactions to metal debris. This retrieval study aimed to quantify variations in stem taper surface topographies and to assess the influence on the formation of corrosion and/or fretting in titanium alloy stem tapers combined with metal and ceramic heads. Four hip stem designs (Alloclassic, CLS, Bicontact and SL-Plus) were characterized using high-resolution 3D microscopy, and corrosion and fretting were rated using the Goldberg scoring scheme. Quantification of the taper surface topographies revealed a high variability in surface characteristics between threaded stem tapers: Alloclassic and CLS tapers feature deeply threaded trapezoid-shaped profiles with thread heights over 65 µm. The sawtooth-shaped Bicontact and triangular SL-Plus taper are characterized by low thread heights below 14 µm. Significantly lower corrosion and fretting scores were observed in lightly threaded compared to deeply threaded tapers in ceramic head combinations. No significant differences in corrosion or fretting scores with thread height were found in pairings with metal heads. Understanding the relationship between stem taper surface topography and the formation of corrosion and fretting could help to improve the performance of modern THAs and lead to longer-lasting clinical results.
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Artroplastia de Reemplazo de Cadera/efectos adversos , Artroplastia de Reemplazo de Cadera/instrumentación , Cerámica/química , Aleaciones de Cromo/química , Articulación de la Cadera/cirugía , Prótesis de Cadera/efectos adversos , Estrés Mecánico , Anciano , Corrosión , Femenino , Articulación de la Cadera/fisiopatología , Humanos , Masculino , Persona de Mediana Edad , Diseño de Prótesis , Falla de Prótesis , Estudios Retrospectivos , Factores de Riesgo , Propiedades de SuperficieRESUMEN
BACKGROUND: Four-dimensional flow magnetic resonance imaging (4D flow MRI) provides volumetric and time-resolved visualization and quantification of blood flow. This review presents an overview of possible applications of 4D flow MRI for non-invasive assessment of abdominal hemodynamics. METHOD: This review is based on the authors' experience and the current literature. A PubMed database literature research was performed in December 2019 focusing on abdominal applications of 4D flow MRI. We illustrated the review with exemplary figures and movies of clinical cases from our institution. RESULTS AND CONCLUSION: 4D flow MRI offers the possibility of comprehensive assessment of abdominal blood flows in different vascular territories and organ systems. Results of recent studies indicate that 4D flow MRI improves understanding of altered hemodynamics in patients with abdominal disease and may be useful for monitoring therapeutic response. Future studies with larger cohorts aiming to integrate 4D flow MRI in the clinical routine setting are needed. KEY POINTS: · 4D flow MRI enables comprehensive visualization of the complex abdominal vasculature. · 4D flow MRI enables quantification of abdominal blood flow velocities and flow rates. · 4D flow MRI may enable deeper understanding of altered hemodynamics in abdominal disease. · Further validation studies are needed prior to broad distribution of abdominal 4D flow MRI. CITATION FORMAT: · Riedel C, Lenz A, Fischer L etâal. Abdominal Applications of 4D Flow MRI. Fortschr Röntgenstr 2021; 193: 388â-â398.
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Abdomen , Hemodinámica , Imagen por Resonancia Magnética , Abdomen/irrigación sanguínea , Abdomen/diagnóstico por imagen , Velocidad del Flujo Sanguíneo , HumanosRESUMEN
Denosumab is a potent osteoclast inhibitor targeted to prevent osteoporotic bone loss and thereby reduce fractures in the aging population. Recently, an elevated risk of rebound fractures following denosumab discontinuation was identified, unless patients were transitioned to an alternative antiresorptive medication. How denosumab affects the interaction of mechanosensitive osteocytes and bone quality remains unknown. We hypothesized that denosumab influences osteocyte function contributing to bone reorganization and increased fractures during discontinuation. Bone quality and osteocytes were assessed in archived iliac crest bone biopsies obtained from patients with high fracture occurrence from 2011 to 2016. Biopsies were obtained due to high fracture occurrence prior and during osteoporosis therapy from (i) patients with at least two semiannual subcutaneous injections of 60 mg denosumab, (ii) patients with rebound fractures during discontinuation, and (iii) patients of a treatment-naive group. In total, biopsies from 43 individuals were analyzed (mean age, 65.5 ± 12.1 years). Our results showed that during denosumab treatment, iliac cortical bone had a higher bone tissue hardness compared to treatment-naive bone (p = 0.0077) and a higher percentage of mineralized osteocyte lacunae (p = 0.0095). The density of empty osteocyte lacunae was higher with denosumab compared to treatment-naive (p = 0.014) and remained high in trabecular bone during discontinuation (p = 0.0071). We conclude that during denosumab treatment, increased bone hardness may contribute to improved fracture resistance. In biopsies from patients with high fracture occurrence, denosumab treatment reduced osteocyte viability, an effect that persisted during treatment discontinuation. High-resolution imaging of osteocyte viability indicates a role for osteocytes as a potential future mechanistic target to understand rebound bone loss and increased fractures with denosumab discontinuation.
Asunto(s)
Conservadores de la Densidad Ósea/efectos adversos , Densidad Ósea/efectos de los fármacos , Resorción Ósea/patología , Denosumab/efectos adversos , Osteoporosis/tratamiento farmacológico , Síndrome de Abstinencia a Sustancias/etiología , Privación de Tratamiento/estadística & datos numéricos , Anciano , Conservadores de la Densidad Ósea/administración & dosificación , Resorción Ósea/inducido químicamente , Denosumab/administración & dosificación , Femenino , Estudios de Seguimiento , Fracturas Múltiples/inducido químicamente , Fracturas Múltiples/patología , Humanos , Masculino , Persona de Mediana Edad , Pronóstico , Síndrome de Abstinencia a Sustancias/diagnósticoRESUMEN
Bone fracture risk is influenced by bone quality, which encompasses bone's composition as well as its multiscale organization and architecture. Aging and disease deteriorate bone quality, leading to reduced mechanical properties and higher fracture incidence. Largely unexplored is how bone quality and mechanical competence progress during longitudinal bone growth. Human femoral cortical bone was acquired from fetal (n = 1), infantile (n = 3), and 2- to 14-year-old cases (n = 4) at the mid-diaphysis. Bone quality was assessed in terms of bone structure, osteocyte characteristics, mineralization, and collagen orientation. The mechanical properties were investigated by measuring tensile deformation at multiple length scales via synchrotron X-ray diffraction. We find dramatic differences in mechanical resistance with age. Specifically, cortical bone in 2- to 14-year-old cases exhibits a 160% greater stiffness and 83% higher strength than fetal/infantile cases. The higher mechanical resistance of the 2- to 14-year-old cases is associated with advantageous bone quality, specifically higher bone volume fraction, better micronscale organization (woven versus lamellar), and higher mean mineralization compared with fetal/infantile cases. Our study reveals that bone quality is superior after remodeling/modeling processes convert the primary woven bone structure to lamellar bone. In this cohort of female children, the microstructural differences at the femoral diaphysis were apparent between the 1- to 2-year-old cases. Indeed, the lamellar bone in 2- to 14-year-old cases had a superior structural organization (collagen and osteocyte characteristics) and composition for resisting deformation and fracture than fetal/infantile bone. Mechanistically, the changes in bone quality during longitudinal bone growth lead to higher fracture resistance because collagen fibrils are better aligned to resist tensile forces, while elevated mean mineralization reinforces the collagen scaffold. Thus, our results reveal inherent weaknesses of the fetal/infantile skeleton signifying its inferior bone quality. These results have implications for pediatric fracture risk, as bone produced at ossification centers during children's longitudinal bone growth could display similarly weak points. © 2019 American Society for Bone and Mineral Research.
Asunto(s)
Envejecimiento , Densidad Ósea , Desarrollo Óseo , Fémur/crecimiento & desarrollo , Adolescente , Preescolar , Femenino , Humanos , Lactante , Recién Nacido , Microtomografía por Rayos XRESUMEN
Within the mineralized bone, osteocytes form a multifunctional mechanosensitive network orchestrating bone remodelling. A preserved osteocyte population is a crucial determinant of bone quality. In human auditory ossicles, the early decrease in osteocyte numbers but maintained integrity remains an unexplained phenomenon that might serve for sound transmission from air to the labyrinth. Here we analysed the frequency, size and composition of osteocyte lacunae in the auditory ossicles of 22 individuals from early postnatal period to old age. Mineralization of the bone matrix was determined using backscattered electron imaging. No signs of bone remodelling were observed above the age of 1 year. We detected characteristics of early bone tissue aging, such as decrease in osteocytes, lower total lacunar density and lacunar area, as well as high matrix mineralization accompanied by distinct accumulation of micropetrotic lacunae and decreased indentation depths. The majority of these changes took place in the first months and years of life, while afterwards only minor reorganization was present. With osteocyte apoptosis potentially being a consequence of low mechanical stimuli, the early loss of osteocytes without initiation of bone remodelling indicates an adaptive response conserving the architecture of the auditory ossicles and ensuring stable sound transmission throughout life.
Asunto(s)
Envejecimiento/patología , Huesos/patología , Calcificación Fisiológica/fisiología , Calcinosis/patología , Muerte Celular/fisiología , Osículos del Oído/patología , Osteocitos/patología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Densidad Ósea/fisiología , Matriz Ósea/patología , Remodelación Ósea/fisiología , Niño , Preescolar , Femenino , Humanos , Lactante , Recién Nacido , Masculino , Persona de Mediana Edad , Adulto JovenRESUMEN
Strontium ranelate and fluoride salts are therapeutic options to reduce fracture risk in osteoporosis. Incorporation of these elements in the physiological hydroxyapatite matrix of bone is accompanied by changes in bone remodeling, composition, and structure. However, a direct comparison of the effectiveness of strontium and fluoride treatment in human cortical bone with a focus on the resulting mechanical properties remains to be established. Study groups are composed of undecalcified specimens from healthy controls, treatment-naïve osteoporosis cases, and strontium ranelate or fluoride-treated osteoporosis cases. Concentrations of both elements were determined using instrumental neutron activation analysis (INAA). Backscattered electron imaging was carried out to investigate the calcium content and the cortical microstructure. In comparison to osteoporotic patients, fluoride and strontium-treated patients have a lower cortical porosity indicating an improvement in bone microstructure. Mechanical properties were assessed via reference point indentation as a measure of bone's resistance to deformation. The strontium-incorporation led to significantly lower total indentation distance values compared to osteoporotic cases; controls have the highest resistance to indentation. In conclusion, osteoporosis treatment with strontium and fluoride showed positive effects on the microstructure and the mechanical characteristics of bone in comparison to treatment-naïve osteoporotic bone. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 433-442, 2017.