Modified Takazawa anatomical classification of renal pelvicalyceal system based on three-dimensional virtual reconstruction models

Abstract

Background: Previous classification of renal pelvicalyceal anatomical structure may be difficult to intuitively understand and unpractical for endourological surgery. We aim to put forward a modified Takazawa anatomical classification of renal pelvicalyceal system based on three-dimensional (3D) virtual reconstruction models for endourological surgery.Methods: We retrospectively collected data on 225 patients (320 kidneys) in total between Apr. 2017 and Dec. 2020, spatial anatomical structure of renal pelvis and calyces were modeled and corresponding morphological parameters were measured after 3D virtual reconstruction of computed tomography urography (CTU). The modified Takazawa renal pelvicalyceal anatomical classification was advanced based on the renal pelvicalyceal morphological parameters [bifurcated branches of renal pelvis, cross sectional area of renal pelvis and ureteropelvic junction (UPJ), infundibuloureteral angle (IUA), lower pole infundibular calyceal length (IL)] by 3D virtual reconstruction models, and comparison of renal pelvicalyceal system morphological parameters were performed to evaluate the differences in various classification types of renal pelvis and calyces.Results: Anatomical structure of renal pelvis and calyces were divided into two main types (Type A and Type B) according to renal pelvic branch patterns. A single pelvis without bifurcated branch was regarded as Type A (62%) and subclassified into three subtypes: Type A1 (22%), Type A2 (27%) and Type A3 (13%), the slimline pelvis was classified as Type A1, the typical pelvis as Type A2 and the broad pelvis as Type A3. A divided pelvis with bifurcated branches was seen as Type B (38%) and subclassified into two subtypes: Type B1 (15%) with the wide and flat lower calyx branch, Type B2 (23%) with the narrow and steep lower calyx branch.Conclusions: Previous studies have reported that the visualization and classification of renal pelvicalyceal anatomical structure by endocast, autopsy, ultrasonography and excretory urography, the modified Takazawa classification system based on 3D virtual reconstruction models enables to standardized different anatomical morphology of renal pelvicalyceal system and provide intuitive and concise information on anatomy, thus leading to the improvement in treatment modality.

Kidney collecting system anatomy applied to endourology - a narrative review

“…A recent study proposed a variation of the classification of the renal collecting system including 5 types of renal pelvis: Type A - a single pelvis without bifurcated branch and subclassified into three subtypes according to the cross- sectional area of renal pelvis: Type A1 - If the cross-sectional area ratio of the pelvis to the UPJ is lower than 4 times, the pelvis is considered to be type A1, which is a slimline pelvis morphology, Type A2 - formed by a typical funnel shaped pelvis and the cross-sectional area of the pelvis is about 4–16 times larger than that of the UPJ, and this subtype is the most frequently observed standard morphology; and Type A3 - subtype that included a broad pelvis morphology forming a large box shaped pelvis with the cross-sectional area ratio of the pelvis to the UPJ greater than 16 times. A divided pelvis with bifurcated branches is seen as Type B and subclassified into two subtypes: Type B1 with the wide and flat lower calyx infundibulum, and Type B2 with the narrow and steep lower calyx infundibulum ( 30 ). However, in our opinion, this division proposed by these authors includes some alterations that already are considered by Sampaio ( 18 , 19 ).…”

The Effect of Laser Settings and Ureteral Access Sheath Size on Intrapelvic Temperature during Holmium Laser Lithotripsy

“…The interquartile range of the cross-sectional area of the renal pelvis in a single pelvis (Type A) spans a wide range, from 41 to 111 mm. Furthermore, in the case of a Type B pelvis, the crosssectional area of lower bifurcated branches in a divided pelvis constitutes a significantly smaller space (on average, 26 mm) [6]. The volume of fluid in which laser activation takes place is a crucial factor in determining the degree of temperature elevation [7].…”

The Number and Size of Individual Kidney Medullary Pyramids is Associated with Clinical Characteristics, Kidney Biopsy Findings, and CKD Outcomes among Kidney Donors

“…Studies have reported varying numbers of pyramids ranging between 5 and 20 pyramids. 9 However, studies have also reported the presence of subtle renal columns within pyramids; these subdivisions are sometimes described as fused secondary pyramids or subpyramids that share the same papillary tip. [10][11][12] Thus, the number of pyramids in a human kidney may be less than the original number of renal lobes because of these fusions.…”