Quantitative anatomical analysis of lumbar interspaces based on 3D CT imaging: optimized segment selection for lumbar puncture in different age groups.

BACKGROUND: Optimal lumbar puncture segment selection remains controversial. This study aims to analyze anatomical differences among L3-4, L4-5, and L5-S1 segments across age groups and provide quantitative evidence for optimized selection. METHODS: 80 cases of CT images were collected with patients aged 10-80 years old. Threedimensional models containing L3-S1 vertebrae, dural sac, and nerve roots were reconstructed. Computer simulation determined the optimal puncture angles for the L3-4, L4-5, and L5-S1 segments. The effective dural sac area (ALDS), traversing nerve root area (ATNR), and area of the lumbar inter-laminar space (ALILS) were measured. Puncture efficacy ratio (ALDS/ALILS) and nerve injury risk ratio (ATNR/ALILS) were calculated. Cases were divided into four groups: A (10-20 years), B (21-40 years), C (41-60 years), and D (61-80 years). Statistical analysis was performed using SPSS. RESULTS: 1) ALDS was similar among segments; 2) ATNR was greatest at L5-S1; 3) ALILS was greatest at L5-S1; 4) Puncture efficacy ratio was highest at L3-4 and lowest at L5-S1; 5) Nerve injury risk was highest at L5-S1. In group D, L5-S1 ALDS was larger than L3-4 and L4-5. ALDS decreased after age 40. Age variations were minimal across parameters. CONCLUSION: The comprehensive analysis demonstrated L3-4 as the optimal first-choice segment for ages 10-60 years, conferring maximal efficacy and safety. L5-S1 can serve as an alternative option for ages 61-80 years when upper interspaces narrow. This study provides quantitative imaging evidence supporting age-specific, optimized lumbar puncture segment selection.

[Hydrological functions of the litters and soil of tropical montane rain forest in Xishuangbanna, Yunnan, China]. / è¥¿åŒç‰ˆçº³çƒ­å¸¦å±±åœ°é›¨æž—æž¯è½ç‰©åŠå ¶åœŸå£¤æ°´æ–‡åŠŸèƒ½.

A study of the hydrological functions of litters and soil of the tropical montane rain forest in Xishuangbanna was carried out. The results showed that the soil bulk density decreased with the increase of altitude, while the soil total porosity, the noncapillary porosity, the capillary porosity, the maximum soil moisture rate, the maximum water holding capacity, the effective water holding capacity, the soil moisture increased with the increase of altitude with local fluctuation. In addition, the soil moisture in early stage of rainy season, the saturated water content and the effective reservoir space increased with the increasing altitude, and the saturated water content and the effective reservoir space had a significant difference at different altitudes (P<0.05). The soil permeability had a significantly positive correlation to the soil total porosity and non-capillary porosity (P<0.01), moreover, the soil non-capillary porosity had a more significant effect on the soil permeability. The thickness of under-composed layer at different altitudes was half more than that of the total litter thickness, which showed that the under-composed layer > semi-decomposed layer. The total volume of litters and the ratio of the volume of semi-decomposed layer to the total volume of litters increased with the increasing altitude, which indicated that the decomposition speed of litters was slower at a low altitude and faster at a high altitude. The maximum capacity of soil moisture, the maximum rate of soil moisture, the natural moisture rate, the effective rate of interception and the effective capacity of interception increased with the increasing altitude in under-composed layer and semi-decomposed layer, and their values in under-composed layer were higher than those in semi-decomposed layer. However, the depth of effective capacity of interception decreased with the increasing altitude with local fluctuation. Comprehensive analysis demonstrated that the water conservation ability was stronger at a high altitude and weaker at a low altitude. The water holding capacity of litters at different altitudes increased and the water absorption rate of litter decreased with the soaking time, while after 12 hours, the water absorption rate of litters gradually became saturated. Moreover, the water holding capacity of litters at different altitudes and soaking time had a logarithmic relationship, and the relationship between the water absorption rate of litters and soaking time was described by power function. In short, there was a stronger water conservation function at high altitude compared with low altitude of the tropical montane rain forest in Xishuangbanna.