Analysis of Morphometry of Calyceal Pattern in Kidney Donors Using CT Angiogram Images

Kumaresan M1, Balaji Karunakaran1, Sangeetha A*2, Gunapriya Raghunath1, Karthikeyan G1, Yuvaraj Maria Francis1, Zareena Begum1 1Department of Anatomy, Saveetha Medical College, Saveetha Institute of Medical and Technical Sciences, Thandalam, Chennai 602 105, Tamil Nadu, India 2Department of Physiology, Saveetha Medical College, Saveetha Institute of Medical and Technical Sciences, Thandalam, Chennai 602 105, Tamil Nadu, India


INTRODUCTION
Each kidney has two or three or even multicalyceal pattern. Each major calyx is formed by the minor calyces and these major calyxes' drains into the renal pelvis. When renal stones are formed in the kidney it deposits in renal calyx. These renal stones are usually smaller stones and will be passed in the urine. When the stones are larger in size it will be located in any of the major calyx which leads to obstruction in the urinary pathway. This may cause hydronephrosis, hydrouretronephrosis and even renal failure. Hence the best method for renal stone treatment is broadly accepted by urologist is extracorporeal shockwave lithotripsy (ESWL), which is the treatment of choice for renal stones with a maximal length of 2 cm or less. Various literatures have explained the correlation of lower pole calyceal system anatomy and ESWL (Sampaio and Passos, 1992). After the measurement of lower calyceal anatomy in intravenous urography (IVU) initially demonstrated by a researcher and later many authors raised different viewpoints about the measurement of the lower calyceal anatomy (Elbahnasy et al., 1998). The clearance rate of stone fragments is worse over the lower calyces than over the middle or upper calyces (Lingeman et al., 1994). Calculi in the lower calyceal group represent 24%-44% of all calculi requiring treatment (Sampaio et al., 1997). Detailed anatomy of calyceal pattern will help in kidney stone treatment (Sampaio, 2001).

MATERIALS AND METHODS
The present study was carried out after getting approval from Institutional Human Ethics Committee, Saveetha Medical College and Hospital. The study was conducted in specialized scan center located in Chennai after getting appropriate permission from medical director of the center. The study group was drawn from kidney donors who approached the scan center had no diseases related to kidney. The study spanned a period of 3 years, 2months. In this study, a total of 99 kidney donors, CT Angiogram images were included. This was a prospective cross-sectional study conducted from June 2014 to September 2017.
Sample size was estimated by SigmaStat 13.0 (Systat software,USA). The kidney donors who approach Specialized Scan Center, Chennai were included for the proposed study. The donors were subjected to CT angiogram. The CT machine used was light speed VCTXTe, ADW4.5 Version. 64 slice Computed Tomography Angiography.

Gender differences in the infundibular length of lower calyx
In this study, the lower infundibular length and width of calyx were measured and also compared with types of calyceal pattern, side and gender Figure 3.

Morphometrical changes in the infundibular length of lower calyx
The mean and standard deviation of lower infundibular length of male and female on right and left side are given in Table 1. Comparison of lower infundibular length between right and left side and between male and female were done. p and t Values are given in Figure 1. Figure 1 shows that, The values of mean ± SD (n -male=54; female=45). The t' and P' Values are by student t' test is signi icantly different from male. The respective right and left lower infundibular length of calyx of male and female are also compared by student t' test.For the male the t' and P' Value are 0.234 and 0.815 respectively. For the female the t' and P' Values are 0.092 and 0.927 respectively.signi icantly different from signi icantly different from the respective side.

Comparison of lower infundibular length of different calyceal pattern
In this study we also compared the lower infundibular length of different calyceal pattern by one way ANOVA. Right side F=1.407, p=0.250; left side F=2.472, p=0.090. Mean and standard deviation are given in Table 1. Student t test values, one way ANOVA values are given in Figure 1. Lower infundibular length of tricalyceal pattern on right and left side shows statistically signi icant t = 2.068 p =0.043.

Comparison of lower infundibular width of different calyceal pattern
We compared the lower Infundibular width of different calyceal pattern by one way ANOVA. Right side F= 4.554, p=0.013; left side F = 0.334, p=0.717. Mean and standard deviation are given in Table 2. Student t est values, one way ANOVA values are given in Figure 2. Figure 2 Shows that, Different calyceal pattern are compared by one way ANOVA right side F=4.554, p=0.013; left side F=0.334, p=0.717. Comparison was also made between right and left. signi icantly different from bicalyx. Student t test values are given in Table 1.
The measurement of lower infundibular length is very essential for selection for the best method of kidney stone treatment for a speci ic patient. There is no statistical association between sides and gender. In our study lower infundibular length on right side 1.87 cm; on left side it was 1.5 cm which is slightly lower than the study conducted by (Pankaj and Wadekar, 2014). The measurement of lower infundibular length is essential for indicating and predicting the outcome of extracorporeal shock wave lithotripsy for treating lower pole nephrolithiasis and also for the retrograde lexible ureteronephroscopy in treatment of lower pole calyx stones. Lower infundibular width is also a reliable factor for predicting the success of extracorporeal shock wave lithotripsy in lower pole kidney stone. The lower infundibular width less than 0.4 cm is clinically important. In this study we found13kidneysshowslessthan0.4cm. Despite the fact that most of them studied the lower pole anatomy using intravenous urogram pretreatment examinations to measure anatomic factors, it has been discussed that some of these factors like infundibular width or infundibular height should not be used because its measurement can change with different urography phases, respiration and/or postural movements or poor quality images (Ghoneim et al., 2005;Gallagher and Tolley, 2000;Pace et al., 2003). Although there have been some groups that evaluated the possibility of using   a three dimensional helical computed tomography to measure the anatomy of the collecting system to avoid potential bias as described above instead of using an urography some authors did not ind any statistical difference which concluded that IVU remains a good method to analyze renal collecting system (Gallagher and Tolley, 2000;Filho et al., 2007). To perform these endourologic procedures safely and ef iciently it is essential to have a clear understanding of pelvicalyceal anatomy and its variations. Thus the in-depth knowledge of pelvicalyceal anatomy will be of immense value to the clinicians of related specialties.

CONCLUSIONS
To conclude, this study suggests that apart from detailed clinical history and examination, a thorough and depth anatomical knowledge of renal morphometry of calyceal pattern is also important for donor selection. Regional anatomy is evaluated in detail to decide the precise surgical approach which will avoid donor complication and to ensure good recipient graftfunction.