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.

Prospective evaluation of syndesmotic ankle sprains without diastasis.

Sixty consecutive collegiate athletes with "high" ankle symptoms were prospectively evaluated over a 3-year period in an effort to better define this debilitating ankle injury. All athletes included in this study had tenderness over the distal anterior tibiofibular ligament, tenderness proximally along the interosseous membrane, and functional disability. No study subject had a fracture or frank tibia-fibula diastasis. The severity of the sprain was quantified using the interosseous "tenderness length." A standard rehabilitation protocol was followed by all patients. Athletes returned to competition when they could perform all functional testing without difficulty. Time to return to full competitive activity averaged 13.4 days. The number of days missed from competition was statistically related to the interosseous tenderness length (P = 0.0001) and to positive results on the squeeze test (P = 0.03). Fifty-three of the 60 injured athletes were evaluated at least 6 months after injury. Patients rated their outcomes as good or excellent. Six of the patients experienced occasional ankle pain and stiffness, four patients reported recurrent ankle sprains, and one patient had heterotopic ossification formation.

Comparative effects of inhaled volcanic ash and quartz in rats.

To investigate the relative toxicities of inhaled volcanic ash and quartz, we exposed matched groups of rats to either respirable volcanic ash (100 mg/m3), quartz (100 mg/m3), or clean air only for 6 h daily for 10 days. Thereafter, we examined animals sequentially for as long as 9 months, and measured changes in lung histopathologic aspects, air-space cells and lipids, and lung density. Neutron activation studies demonstrated that 3.3% of the inhaled daily dose of volcanic ash was detectable in the lung parenchyma. Volcanic ash was less toxic to the lung than quartz. Immediately after exposure, the lungs of animals treated with volcanic ash had ultrastructural evidence of damage to type I pneumocytes and early alveolar edema formation. By contrast, quartz-treated animals had an intense acute injury, with intraalveolar accumulation of lipid, protein, macrophages, and granulocytes. Six months after exposure, animals treated with volcanic ash had moderate interstitial thickening and fibrosis, whereas the quartz-treated animals had severe pulmonary fibrosis. Quartz, but not volcanic ash, caused a marked increase in lavage granulocytes, protein, and phospholipids. Lung density increased in quartz-exposed, but not in volcanic-ash-exposed animals. These data indicate that volcanic ash is less harmful to the lung parenchyma than is quartz. Persons exposed to volcanic ash for short periods are at much less risk of subsequent lung damage than are those who are exposed to similar amounts of quartz in the workplace.