The dynamic enhanced characterization with low mechanical index gray-scale harmonic imaging inflammatory pseudotumor of liver compared with hepatic VX2 tumor and normal liver.

BACKGROUND: Inflammatory pseudotumor of the liver (IPTL) is misdiagnosed usually as a malignant tumor based on the imaging findings. Differential diagnosis should be established to avoid hepatic resection. At imaging, IPTL has been misdiagnosed usually as hepatocellular carcinoma (HCC). It is usually found firstly using conventional ultrasonic examination, which cannot give a definitive diagnosis. Because of its atypical clinical presentation and radiological appearance, a presumptive diagnosis of malignancy is frequently made. With the development of ultrasound systems and ultrasound contrast agents (UCA), contrast-enhanced ultrasound is widely used in diagnosing focal lesions of the liver. OBJECTIVES: To delineate the hemodynamic features of IPTL compared with hepatic VX2 tumor and normal liver using contrast-enhanced ultrasound. MATERIAL AND METHODS: Freund's complete adjuvant (FCA) was injected using a modified method into the desirable portion of the liver in rabbits. Two weeks after the injection, solitary IPTLs were formed (which was proved with pathological examination). Ten rabbits with IPTL, 10 rabbits with VX2 carcinoma and 10 healthy rabbits were studied using contrast-enhanced ultrasound with bolus injection of SonoVueTM through the peripheral vein. Corresponding parameters such as time to enhancement (ET), time to peak intensity (PIT), time to ascent (AT), and time to lighten (LT) were measured with wash-in/wash-out curve. RESULTS: Contrast-enhanced imaging clearly delineated the dynamic enhancement of the lesions and liver parenchyma during the whole phase. Inflammatory pseudotumor of the liver showed the same enhanced features as the liver parenchyma. In VX2 tumors, hyperechoic enhancement in arterial phase and hypoechoic enhancement was observed in the portal and delayed phase compared with the surrounding hepatic parenchyma. The normal liver showed whole of liver parenchyma enhanced in portal phase. CONCLUSIONS: The study showed that contrast-enhanced ultrasound provided useful information about perfusion in IPTL and VX2 carcinoma. Contrast-enhanced ultrasound is a useful technique in the differential diagnosis of focal liver lesions if combined with time-intensity curve.

Snowmelt and early to mid-growing season water availability augment tree growth during rapid warming in southern Asian boreal forests.

Boreal forests are facing profound changes in their growth environment, including warming-induced water deficits, extended growing seasons, accelerated snowmelt, and permafrost thaw. The influence of warming on trees varies regionally, but in most boreal forests studied to date, tree growth has been found to be negatively affected by increasing temperatures. Here, we used a network of Pinus sylvestris tree-ring collections spanning a wide climate gradient the southern end of the boreal forest in Asia to assess their response to climate change for the period 1958-2014. Contrary to findings in other boreal regions, we found that previously negative effects of temperature on tree growth turned positive in the northern portion of the study network after the onset of rapid warming. Trees in the drier portion did not show this reversal in their climatic response during the period of rapid warming. Abundant water availability during the growing season, particularly in the early to mid-growing season (May-July), is key to the reversal of tree sensitivity to climate. Advancement in the onset of growth appears to allow trees to take advantage of snowmelt water, such that tree growth increases with increasing temperatures during the rapidly warming period. The region's monsoonal climate delivers limited precipitation during the early growing season, and thus snowmelt likely covers the water deficit so trees are less stressed from the onset of earlier growth. Our results indicate that the growth response of P. sylvestris to increasing temperatures strongly related to increased early season water availability. Hence, boreal forests with sufficient water available during crucial parts of the growing season might be more able to withstand or even increase growth during periods of rising temperatures. We suspect that other regions of the boreal forest may be affected by similar dynamics.

Altitudinal disparity in growth of Dahurian larch (Larix gmelinii Rupr.) in response to recent climate change in northeast China.

Forests are sensitive to climate change at high altitude and high latitude. Dahurian larch (Larix gmelinii Rupr.) has experienced an unprecedented forest retreat northward during the last century. Whether the response of growth to climate has dissimilar patterns at different altitudes, and what the "altitudinal trends" of forest development will be in the future, remains unclear. We dendroclimatically investigated the impacts of climate change on the growth of larch forests along an altitudinal gradient. In total, 721 trees from 25 forest stands, representing an altitudinal range from 400 to 950 m a.s.l. in the Great Xing'an Mountains, northeast China, were sampled and used to develop tree-ring width chronologies. The results suggest that warming caused a decline in larch growth at low altitude, while tree growth increased at high altitude. The growth-climate relationships indicate that October-February temperatures were positively correlated with larch growth at low- and high-altitude sites, but negatively correlated at medium-altitude sites (ca. 600-700 m a.s.l.). April-May (early spring) temperatures and October-January precipitation had positive effects on growth in general (ca. 75% of all sites). The effects of summer temperature/precipitation on larch growth at high-altitude sites were opposite to that at low-altitude sites. This change of response from significantly positive/negative correlation to significantly negative/positive correlation occurred gradually along the altitudinal gradient. The relationships varied significantly with altitude both in the case of temperature (R2 = 0.425, P < 0.001) and precipitation (R2 = 0.613, P < 0.001). The shift in response of larch forest to changes in summer temperature and precipitation occurred in the areas with a mean annual temperature of ca. -4 °C and ca. -5 °C, respectively; larch growth at temperatures lower or higher than these thresholds was limited by temperature and precipitation, respectively.