the result of this novel pipeline, when applied to our hip - ct data of human kidney, was the generation the first open - source spatial graph of the intact human kidney arterial vasculature, ranging from renal artery to interlobular arteries. we were able to identify 97 % of vessels > 50 µm radius across the whole intact human kidney. the final network consisted of 10, 193 nodes, 376, 603 points and 10, 190 vessels. the total network volume was 1. 68 × 10 µm, with a length of 2. 3 × 10 µm. this spatial graph, which is provided in our supplementary information, captures the morphological features and connectivity of the human kidney arterial vasculature, which was then used for downstream analyses as described below. having created a reproducible spatial graph of the human kidney arterial vasculature, we then performed topological generation and truncated strahler ordering analyses. this resulted in nine truncated strahler orders ( fig. 3a ) and twenty - five topological generations ( fig. 3b ). as the main artery supplying the kidney was cut during autopsy, we inferred that 10 truncated strahler orders, representing 26 topological generations, were imaged over the intact human kidney with hip - ct. strahler ordering, and other approaches to classify vascular networks, have potential caveats ( see supplementary note 4 ), for example, the strahler ( or truncated strahler ) order of any individual vessel depends upon the downstream network, and thus on the identification of the network endpoint. ideally, this endpoint would correspond to the afferent arteriole entering the renal glomerulus. however, at 50 µm per voxel resolution, we were unable to detect afferent arterioles, and thus, the smallest vessels, defined as truncated strahler order 1 vessels, were the interlobular arteries. diameter - based statistical approaches to estimation of the strahler order of the kidney vascular network ’ s terminal ends were not appropriate to correct for this due to the ex vivo and non - perfused nature of hip - ct, as well as the connectivity of glomeruli relative to terminal vessel ends. thus, we applied truncated strahler ordering to our spatial graph and report how morphological features of vessels in the network vary with truncated strahler order. we also mapped our truncated strahler orders to known anatomical subdivisions of the arterial tree to give anatomical context. this resulted in the following classification: truncated strahler orders 7 – 9 ( n = 25 segments; mean radius = 929 ± 477 µm ) mapped to the branches of the kidney artery entering the kidney hilum. orders 5 – 6 comprised interlobar arteries ( n = 219 segments; mean radius = 417 ± 247 µm ), and orders 2 – 4 arcuate arteries ( n = 4841 segments; mean radius = 78 ± 45 µm ). finally, interlobular arteries fell within orders 1 – 3 ( n = 9430 segments; mean radius = 55 ± 23 µm ). we further plotted the cumulative volume of the kidney vascular network ( fig. 3cii ), finding that over 20 % of the volume of the network lies within strahler orders 1 – 4, corresponding to segments from interlobular arteries and arcuate arteries. we found 5105 truncated strahler order 1 segment and identified a logarithmic relationship between truncated strahler order and segment number ( fig. 3ci ). using this relationship, we determined the branching ratio within this subsection of the vascular tree to be 2. 92, a value which is similar to that of the human pulmonary arterial tree ( 3. 0 ) and the rat kidney vasculature ( 2. 85 ). to provide further context to the truncated strahler order and to investigate the small - calibre vessels within the human kidney, we leveraged the hierarchical capability of hip - ct. using high - resolution vois, we segmented and counted all glomeruli within each of the 3 high - resolution vois of the hip - ct data ( fig. 3d ). we extrapolated from these vois to the total of ~ 1. 2 million glomeruli in the intact kidney, which aligned well with estimates for adult males within a similar age range. given the 5105 truncated strahler order 1 segments, the branching ratio of 2. 921 and the total number of glomeruli, we estimated that there are a further 4 – 5 truncated strahler orders between the end of our whole organ network and the afferent arterioles. to further evaluate this estimate, we assessed on high - resolution voi, connecting six afferent arterioles of individual glomeruli back to the main vessel tree ( fig. 3e, supplementary movie 4 and supplementary fig. 8 ). of the 6 glomeruli, 5 originated from non - terminal arteries and one from a terminal artery ( fig. 3e, red arrows and black arrows respectively ). this supports recent findings, in the rat kidney, which similarly demonstrated the existence of non - terminal branch arterioles, with potential contributions to the synchronicity of blood flow within the kidney. the existence of non - terminal glomeruli also prevents the application of the statistical methods which have previously been used to estimate the true strahler order of a truncated network. given the presence of non - terminal glomeruli, statistical estimation of true strahler order would necessitate connecting a larger number ( ~ 1000 ) of glomeruli back to the main tree to generate an ac curate statistical representation of the proportion of terminal to non - terminal glomeruli. such an estimation cannot be made with this dataset as, even with our highest resolution scans, the small vessels connecting the glomeruli to the main vascular tree could not be annotate d reliably for a large number of cases. however, our estimation of total glomeruli number provides a data - driven estimate for the number of missing orders, and thus gives the context needed to support our use of the truncated strahler order for our ongoing analysis. vascular network geometric properties, including vessel diameters, lengths and branching angles, are key metrics for quantitative and objective comparison of vascular networks in health or disease. thus, we extracted and reported the metrics for the human kidney vasculature. data were grouped according to truncated strahler order ( fig. 4, table 1 ) to enable quantitative comparison to rat and other human organ data. the raw data for each segment, which may serve as inputs for computational models, have been provided as supplementary information. table 1 human kidney vascular branching metrics by truncated strahler generation ( means with standard deviation are shown ) truncated strahler order no. of segments radium ( µm ) length µm × 10 tortuosity length: diameter vol. × 10 µm branching angle ivd µm × 10 1 5105 45 ± 5 2. 6 ± 1. 7 1. 2 ± 0. 20 57. 4 ± 36 0. 18 ± 0. 22 129 ± 28 1. 1 ± 0. 4 2 3030 56 ± 15 1. 8 ± 1. 4 1. 1 ± 0. 16 32. 3 ± 26 0. 21 ± 0. 46 128 ± 29 0. 9 ± 0. 4 3 1295 95 ± 37 1. 8 ± 1. 4 1. 1 ± 0. 14 20. 2 ± 18 6. 7 ± 10. 3 128 ± 29 1. 1 ± 0. 4 4 516 165 ± 60 2. 3 ± 1. 9 1. 1 ± 0. 13 14. 6 ± 12 25. 5 ± 34. 9 135 ± 29 1. 4 ± 0. 5 5 150 294 ± 110 3. 3 ± 2. 6 1. 1 ± 0. 05 12. 2 ± 9. 4 11. 3 ± 17. 1 142 ± 25 1. 8 ± 0. 7 6 69 684 ± 250 4. 3 ± 3. 1 1. 1 ± 0. 06 6. 5 ± 4. 5 84. 6 ± 104 149 ± 21 2. 9 ± 0. 7 7 20 839 ± 251 7. 2 ± 4. 9 1. 1 ± 0. 05 8. 5 ± 4. 8 223 ± 302 148 ± 24 6. 1 ± 1. 5 8 4 877 ± 188 8. 1 ± 4. 7 1. 1 ± 0. 07 9. 6 ± 6. 3 227 ± 159 141 ± 6 4. 7 ± 1. 5 9 1 2923 669 1. 0 0. 2 180 - - source paper: pmc12408821 human kidney vascular branching metrics by truncated strahler generation ( means with standard deviation are shown ) source paper: pmc12408821 further quantitative analysis of the human kidney vascular network revealed that, as truncated strahler order increased, there was a reduction in the ratio of vessel length: diameter ( fig. 4b ). in contrast, the mean radius ( fig. 4e ) and inter - vessel distance increased ( fig. 4f ). tortuosity did not vary significantly with truncated strahler order ( fig. 4d ); with most segments possessing tortuosity close to 1, thus implying limited deviation from a straight path.