Revisiting the morphology of pelvicalyceal system in human cadaveric kidneys with a systematic review of literature

ASSIST-U: A system for segmentation and image style transfer for ureteroscopy

Kidney stones require surgical removal when they grow too large to be broken up externally or to pass on their own. Upper tract urothelial carcinoma is also sometimes treated endoscopically in a similar procedure. These surgeries are difficult, particularly for trainees who often miss tumours, stones or stone fragments, requiring re-operation. Furthermore, there are no patient-specific simulators to facilitate training or standardized visualization tools for ureteroscopy despite its high prevalence. Here a system ASSIST-U is proposed to create realistic ureteroscopy images and videos solely using preoperative computerized tomography (CT) images to address these unmet needs. A 3D UNet model is trained to automatically segment CT images and construct 3D surfaces. These surfaces are then skeletonized for rendering. Finally, a style transfer model is trained using contrastive unpaired translation (CUT) to synthesize realistic ureteroscopy images. Cross validation on the CT segmentation model achieved a Dice score of 0.853 ± 0.084. CUT style transfer produced visually plausible images; the kernel inception distance to real ureteroscopy images was reduced from 0.198 (rendered) to 0.089 (synthesized). The entire pipeline from CT to synthesized ureteroscopy is also qualitatively demonstrated. The proposed ASSIST-U system shows promise for aiding surgeons in the visualization of kidney ureteroscopy.

Kidney collecting system anatomy applied to endourology - a narrative review

OBJECTIVE

To evaluate the surgical anatomy of the kidney collecting system through a narrative review of the literature, highlighting its importance during diagnosis and its approach during surgical procedures for the treatment of renal stones.

MATERIAL AND METHODS

We carried out a review about the anatomy of the kidney collecting system. We analyzed papers published in the past 40 years in the databases Pubmed, Embase and Scielo, and we included only papers in English and excluded case reports, editorials and opinions of specialists.

RESULTS

Renal collecting system could be divided in four groups: A1 - kidney midzone (KM), drained by minor calyx that are dependent on the superior or the inferior caliceal groups; A2 - KM drained by crossed calyx, one draining into the superior caliceal group and another draining into the inferior caliceal group; B1 - KM drained by a major caliceal group independent of both the superior and inferior groups; and B2 - KM drained by minor calyx entering directly into the renal pelvis. Some details and anatomic variations of the collecting system are related to clinical and radiological aspects, particularly perpendicular calyces, interpyelocalyx space, position of calyces in relation to renal border, classification of the renal collecting system, infundibular diameter and the angle between the lower infundibulum and renal pelvis.

CONCLUSION

The knowledge of intra-renal collecting system divisions and variations as the angle between the renal pelvis and lower infundibula, position of the calices in relationship with renal edge and the diameter and position of the calyces are important for the planning of minimally invasive renal surgeries.

Classification and clinical significance of the posterior group of renal calyces

To study the anatomical orientation of the posterior group of calyces based on reconstructed images of computerized tomography urography (CTU) and provide a novel classification with its clinical significance. Clinical data of a total of 1321 patients, who underwent CTU examination in our hospital were retrospectively analyzed. Among these, a total of 2642 3-dimensional reconstructed images of CTU scans were considered in this study. Based on the morphology of the renal calyces and the influence on the establishment of surgical access, the posterior group renal calyces are classified into 3 major types including pot-belly type, classically branched and elongated branched. The classically branched type is further classified into 3 sub-types: a, b and c, based on the association of minor calyces of the posterior group to the major calyces. Type a is derived from 1 group of major calyces only, type b is derived from 2 groups of major calyces simultaneously, and type c is derived from 3 groups of major calyces simultaneously. Statistical findings revealed that all kidneys possess posterior group calyces. The percentage of occurrence of pot-belly type, classically branched and elongated branched is 8.06%, 73.13%, and 18.81%, respectively. The anatomical typing of the classical branching type occurred in 19.36%, 68.17%, and 12.47% for types a, b, and c, respectively. In this study, the posterior group calyces were found to be present across all patients. The posterior group calyces were highest in the classical branching type, of which anatomical typing was highest in type b. The typing of the posterior group of calyces could provide an anatomical basis for percutaneous nephrolithotomy (PCNL) puncture from the posterior group.

Mineralogy, geochemistry, and micromorphology of human kidney stones (urolithiasis) from Mersin, the southern Turkey

This study describes the primary characteristics of the selected kidney stones surgically removed from the patients at the Mersin University Hospital in the southern Turkey and interprets their formation via petrographic, geochemical, XRD, SEM-EDX, and ICP-MS/OES analyses. The analytical results revealed that the kidney stones are composed of the minerals whewellite, struvite, hydroxyapatite, and uric acid alone or in different combinations. The samples occur in staghorn, bean-shaped composite, and individual rounded particle shapes, which are controlled by the shape of the nucleus and the site of stone formation. The cross-section of the samples shows concentric growth layers due to variations in saturation, characterizing the metastable phase. Kidney stone formation includes two main stages: (i) nucleation and (ii) aggregation and/or growth. Nucleation was either Randall plaque of hydroxyapatite in tissue on the surface of the papilla or a coating of whewellite on the plaque, or crystallization as free particles in the urine. Subsequently, aggregation or growth occurs by precipitation of stone-forming materials around the plaque or coating carried into the urine, or around the nucleus formed in situ in the urine. Urinary supersaturation is the main driving force of crystallization processes; and is controlled by many factors including bacterially induced supersaturation.

Ureter-first Approach and Reduction of Pelvis: Standardizing Handling of Ureteropelvic Junction During Pyeloplasty

OBJECTIVE

To present our "ureter-first" approach as a standardized step-wise incision-making technique to deal with all types of uretero-pelvic junction (UPJ) anatomy during pyeloplasty. Pyeloplasty is a common surgery performed for UPJ obstruction, with Anderson-Hynes' pyeloplasty being the commonest. However, there is great variability in handling UPJ and incision-making among the surgeons with no detailed standardized description that can be followed in all cases, notwithstanding broad descriptions of incision lines. We underscore this aspect of pyeloplasty and present our universal technique with a goal to minimize surgical errors.

METHODS

A standardized step-by-step handling of UPJ and sequential incision-making was developed for pyeloplasty. It avoids unwarranted loss of any pelvis tissue before confirming individual UPJ anatomy, emphasizes preservation of lower lip of pelvis and minimizes tension on anastomosis. This standardized technique was uniformly used in all cases over 5 years. The peri-operative and functional outcome results are presented.

RESULTS

Fifty-one consecutive cases were done using ureter-first approach. UPJ was >1 cm in eight cases. Three of these had UPJ >2 cm. Eight other cases had a low-insertion below level of kidney while three had high insertion of ureter. There were no cases which were deemed to be done under tension or unsatisfactory repair by the surgeon. There were no failures requiring any kind of redo repair at mean follow up of 39 months.

CONCLUSION

A uniform standardized approach saves the surgeon from unwarranted or wrongly designed incisions on the pelvis and thus has the potential to reduce surgical mistakes.

Pelviureteric Junction Obstruction in Ectopic Kidneys with Extrarenal Calyces: A Rare Renal Anomaly

Extrarenal calyces (ERC) is a rare renal anomaly where calyces lie outside the renal parenchyma and are connected to pelvis by draining infundibulum. Its presentation with pelviureteric junction obstruction presents a confusing intraoperative finding. We report two cases of ERC with pelviureteric junction obstruction in the ectopic kidney. Emphasis is laid on the defining the anatomy so that reader can identify the condition if he comes across similar situation. The two patients were managed by minimal access approach. Management of these cases and review of pediatric cases reported in literature are discussed.