Effects of Different Types of Mechanical Loading on Trabecular Bone Microarchitecture in Rats

Mechanical loading is generally considered to have a positive impact on the skeleton; however, not all types of mechanical loading have the same beneficial effect. Many researchers have investigated which types of mechanical loading are more effective for improving bone mass and strength. Among the various mechanical loads, high-impact loading, such as jumping, appears to be more beneficial for bones than low-impact loadings such as walking, running, or swimming. Therefore, the different forms of mechanical loading exerted by running, swimming, and jumping exercises may have different effects on bone adaptations. However, little is known about the relationships between the types of mechanical loading and their effects on trabecular bone structure. The purpose of this article is to review the recent reports on the effects of treadmill running, jumping, and swimming on the trabecular bone microarchitecture in small animals. The effects of loading on trabecular bone architecture appear to differ among these different exercises, as several reports have shown that jumping increases the trabecular bone mass by thickening the trabeculae, whereas treadmill running and swimming add to the trabecular bone mass by increasing the trabecular number, rather than the thickness. This suggests that different types of exercise promote gains in trabecular bone mass through different architectural patterns in small animals.

Utility of radius bone densitometry for the treatment of osteoporosis with once-weekly teriparatide therapy

OBJECTIVES: As clinics that treat patients with osteoporosis do not usually have central dual-energy X-ray absorptiometry (DXA), bone density is often measured with radial DXA. However, no long-term evidence exists for radius bone density outcomes following treatment with once-weekly teriparatide in actual medical treatment. METHODS: We evaluated changes in bone density at 6-, 12-, and 18-month intervals using radial DXA in patients treated with once-weekly teriparatide for more than 6 months. RESULTS: A significant increase in bone mineral density (BMD) was observed at the 1/3 and 1/10 radius sites 12 months after the initiation of once-weekly teriparatide. We also observed that the rate of change in BMD was greater at the distal 1/10 radius than at the 1/3 radius. CONCLUSIONS: Considering these points, the effect of once-weekly teriparatide therapy can be observed at the radius. In clinics that do not have central DXA, but instead have radial DXA, these findings can help to evaluate the effect of once-weekly teriparatide treatment on osteoporosis.

MRI Appearance of Prostatic Stromal Sarcoma in a Young Adult

Prostatic stromal sarcoma (PSS) is quite rare. Herein, we describe magnetic resonance imaging (MRI) features of a PSS identified in a 26-year-old man with dysuria and hematuria. MRI clearly depicted the extent and multinodular appearance of the tumor, which was mainly located in the central zone of the prostate. The tumor appeared as a heterogeneously signal-hyperintense mass with a pseudocapsule on T2-weighted imaging. Contrast-enhanced T1-weighted MRI showed necrotic portions in the gradually enhanced solid mass, and diffusion-weighted imaging permitted the accurate assessment of the local extent of the tumor. Thus, the appearance on MRI was quite different from that of adenocarcinoma of the prostate.

Diagnosis of Myocardial Viability by Fluorodeoxyglucose Distribution at the Border Zone of a Low Uptake Region

PURPOSE: In cardiac 2-[F-18]fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography (PET) examination, interpretation of myocardial viability in the low uptake region (LUR) has been difficult without additional perfusion imaging. We evaluated distribution patterns of FDG at the border zone of the LUR in the cardiac FDG-PET and established a novel parameter for diagnosing myocardial viability and for discriminating the LUR of normal variants. MATERIALS AND METHODS: Cardiac FDG-PET was performed in patients with a myocardial ischemic event (n = 22) and in healthy volunteers (n = 22). Whether the myocardium was not a viable myocardium (not-VM) or an ischemic but viable myocardium (isch-VM) was defined by an echocardiogram under a low dose of dobutamine infusion as the gold standard. FDG images were displayed as gray scaled-bull's eye mappings. FDG-plot profiles for LUR (= true ischemic region in the patients or normal variant region in healthy subjects) were calculated. Maximal values of FDG change at the LUR border zone (a steepness index; S(max) scale/pixel) were compared among not-VM, isch-VM, and normal myocardium. RESULTS: S(max) was significantly higher for n-VM compared to those with isch-VM or normal myocardium (ANOVA). A cut-off value of 0.30 in Smax demonstrated 100% sensitivity and 83% specificity for diagnosing n-VM and isch-VM. S(max) less than 0.23 discriminated LUR in normal myocardium from the LUR in patients with both n-VM and isch-VM with a 94% sensitivity and a 93% specificity. CONCLUSION: S(max) of the LUR in cardiac FDG-PET is a simple and useful parameter to diagnose n-VM and isch-VM, as well as to discriminate thr LUR of normal variants.