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Estimating Lengths of Renal Arteries and Infrarenal Aorta on Contrast CT Scans- A Retrospective Study |
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KS Sachin, Joish Upendra Kumar, Praveen Shenoy, Shardul Gund, Meghavardhan Guptha 1. Associate Professor, Department of Anatomy, KVG Medical College, Sullia, Karnataka, India. 2. Associate Professor, Department of Radiology, KVG Medical College, Sullia, Karnataka, India. 3. Associate Professor, Department of Anatomy, KVG Medical College, Sullia, Karnataka, India. 4. Resident, Department of Radiology, KVG Medical College, Sullia, Karnataka, India. 5. Resident, Department of Radiology, KVG Medical College, Sullia, Karnataka, India. |
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Correspondence Address : Joish Upendra Kumar, Associate Professor, Department of Radiology, KVG Medical College, Kurunjibagh, Sullia-574327, Karnataka, India. E-mail: joishupendra@gmail.com |
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| ABSTRACT |  | |||||||||||||||||||||||||||||||||||||||||||||||||||
: Introduction: Anatomy of renal arteries and length of infrarenal aorta play a vital role in various renal and aortic vascular interventions and surgical procedures including renal transplantation. Aim: To estimate mean lengths of renal arteries, the vertical distance between origins of both renal arteries, infrarenal aortic lengths, and presence of accessory renal arteries on contrast Computed Tomography (CT) scans. Materials and Methods: A retrospective hospital-based study was conducted at KVG Medical College and Hospital, Sullia, Karnataka, India in which contrast enhanced CT scans of the abdomen was performed between October and December 2021. The CT image datasets of 61 individuals were evaluated in the study, of which 45 were males and 16 were females. The arterial phase images were anonymised and loaded in the curved Multiplanar Reformatted (MPR) algorithm. The lengths of both Renal Arteries (RA), vertical distance between origins of both Renal Arteries (RAD), infrarenal Aortic Lengths (AL), and presence of accessory renal arteries were noted. For statistical analysis Statistical Package for the Social Sciences (SPSS) software version 22.0 was used and Pearson’s Chi-square test and independent t-test were used for calculation. Results: The mean age of the participants was 50.7±7.5 years. Mean right RA was 3.75±1.25 cm and left RA was 2.89±0.98 cm. Right RA was significantly longer than left RA (p=0.019). Mean RAD was 0.61 cm. In 35 cases of (57%) right RA originated at a higher level than the left RA. The mean AL was 9.68±1.18 cm. Accessory renal arteries were seen in nine of cases (14.8%). Conclusion: The mean measurements obtained can provide vital guidance during renal and aortic surgeries and vascular interventions. | ||||||||||||||||||||||||||||||||||||||||||||||||||||
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| Keywords : Accessory renal artery, Computed tomography, Curved multiplanar reformatted, Renal artery branching | ||||||||||||||||||||||||||||||||||||||||||||||||||||
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DOI and Others :
DOI: 10.7860/IJARS/2022/56715.2819
Date of Submission: Mar 28, 2022 Date of Peer Review: Apr 19, 2022 Date of Acceptance: May 06, 2022 Date of Publishing: Jul 01, 2022 AUTHOR DECLARATION: • Financial or Other Competing Interests: None • Was Ethics Committee Approval Obtained for this study? Yes • Was informed consent obtained from the subjects involved in the study? Yes • For any images presented appropriate consent has been obtained from the subjects. Yes PLAGIARISM CHECKING MET |
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| INTRODUCTION |
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The anatomy of the renal arteries and length of infrarenal aorta plays a vital role in various interventions and surgical procedures including renal vascular interventions, aortic aneurysmal repair, selection of kidney donors for renal transplant. Renal arteries arise as lateral branches of the abdominal aorta at the level of L1-L2 and divide close to the hilum. Around 70% of individuals, the kidney is supplied by a single renal artery arising from the abdominal aorta. Infrarenal aorta is the segment of the aorta extending from the origin of the renal arteries to its bifurcation at the L4 vertebral level (1). Length of the renal artery, presence of accessory renal arteries, and the exact site of origin of renal arteries from the abdominal aorta are crucial factors for many interventional procedures and surgeries (2),(3),(4). The ideal donor of kidney is the one with a single renal artery with good length and diameter for the ease of vascular anastomosis. However, renal artery variations are common regarding their origin and number (5),(6),(7),(8),(9). The present study was done to estimate the mean lengths of Renal Arteries (RA) and infrarenal Aortic Length (AL) on contrast Computed Tomography (CT) scans. A secondary objective was to determine whether any correlation exists between the presence of accessory renal arteries and the length of main RA till their first branching point. | ||||||||||||||||||||||||||||||||||||||||||||||||||||
| Material and Methods |
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A retrospective hospital-based study was conducted at KVG Medical College and Hospital, Sullia, Karnataka, India, on individuals who had undergone contrast CT between October to December 2021. The study procedure followed the guidelines provided by declaration of Helsinki and prior Institutional Ethical Committee Clearance was taken for the study. Sample size calculation: The sample size was calculated using power based sample size calculation formula with a confidence interval of 95% which yielded a sample size of 54. Inclusion criteria: Initially the CT requisition forms of the study period were screened to include those individuals who had undergone contrast CT of the abdomen in the arterial phase for various indications other than aortic and renal pathologies. Exclusion criteria: Any case in which there was a gross distortion of anatomy due to large masses, moderate to severe ascites, and vascular thrombosis was excluded from the study. Study Procedure The department follows a standard protocol of injecting iohexol contrast agent (300 mg/mL of iodine) intravenously (1-1.5 mL/kg body weight) using a single head pressure injector. Bolus tracking method was used by drawing a 1 cm2 circle (Region Of Interest-ROI), in the centre of the lumen of aorta just below its diaphragmatic hiatus. A Hounsfield Units (HU) of 100 was set as a trigger for the scan with a minimum delay of four seconds to acquire images in the arterial phase. The personal identification data of the Digital Imaging and Communication in Medicine (DICOM) image datasets of the eligible individuals were anonymised and retrieved on the Osirix application in an Apple workstation. Thin 1 mm image datasets were used and curved Multiplanar Reformatted (MPR) images were generated. A radiologist with nine years of experience in abdominal radiology evaluated the images and assessed the following in each case: Distance between origin from the abdominal aorta to first branching of renal artery on both sides (length of the renal artery) right and left RA (Table/Fig 1). Vertical distance between origin of both the renal arteries from aorta (RAD) (Table/Fig 2). Length of the aorta between origin of the lower renal artery and aortic bifurcation AL (Table/Fig 3). Presence/absence of accessory renal arteries (Table/Fig 4). The smaller vessels arising from the aorta and supplying the kidneys were considered accessory renal arteries (10). The distances were measured using digitised calipers on curved MPR images using straight line or curved line tools. In the case of tortuous anatomy, the parts were virtually uncoiled to obtain images for accurate measurements. STATISTICAL ANALYSIS The values obtained were tabulated in Statistical Package for the Social Sciences (SPSS) software version 22.0. Mean values and standard deviations were obtained. Independent sample t-test was used to find out the association between the length of the right and left RA and Pearson’s Chi-square test was used to determine dependence of branching pattern of renal arteries on the presence of accessory renal arteries. | ||||||||||||||||||||||||||||||||||||||||||||||||||||
| Results |
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Contrast CT image datasets of 61 individuals were evaluated in the study, of which 45 were males and 16 were females. The mean age of the participants was 50.7±7.5 years. The indications for contrast CT ranged from suspected bowel pathologies including appendicitis (n=12), inflammatory (n=15), infective conditions (n=20), liver lesions (n=10) and miscellaneous (n=4) etc. The mean length of the right RA was 3.75±1.25 cm and the left RA was 2.89±0.98 cm (Table/Fig 5). The mean sum length of right and left renal arteries was 6.64±2.23 cm. On the independent sample t-test, right RA was significantly longer than left RA (p=0.019). The mean infrarenal AL was 9.68±1.18 cm. The mean vertical distance between the origins of both renal arteries (RAD) was 0.61±0.56 cm. In 11 cases (18%), both right and left renal arteries originated at the same level from the aorta (RAD≤0.1 cm) (Table/Fig 6). In 35 (57%) cases right RA originated at a higher level as compared to the left RA [Table/Fig-7,8]. In remaining 15 cases (25%) left RA originated at a higher level as compared to right RA (Table/Fig 7), (Table/Fig 8). Accessory renal arteries were seen in nine cases (14.8%), in four of which cases were seen bilaterally. Right accessory renal arteries were seen in five cases of which three arose superior to main renal arteries and two inferior to them. Left accessory renal arteries were seen in eight cases of which seven were superior to main renal arteries. On Pearson’s Chi-square test to assess statistical independence, it was found that the presence of accessory renal arteries and lengths of main renal arteries (i.e. branching pattern of renal arteries) were statistically independent (Chi-squared probability p=0.23). | ||||||||||||||||||||||||||||||||||||||||||||||||||||
| Discussion |
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The results obtained from the present study reflect important measurements that can help guide renal and abdominal aortic vascular interventions and surgeries. The precise length of the renal arteries, their site of origin from the aorta and the presence of accessory renal arteries are critical for donor selection, renal harvesting and anastomoses during renal transplantation. Comparing renal artery lengths and their origins (Table/Fig 9): In this study, the mean renal artery lengths found were significantly shorter compared to the results of Mohiuddin M et al., (11) which found the mean right and left RA to be 4.5 cm and 3.5 cm respectively in Pakistan (Table/Fig 9). All these studies found that right RA was significantly longer than left RA owing to their origin from the aorta which is located more towards the left of the midline. Ahmed MAAS et al., found the left renal arteries arose significantly lower than the right renal arteries from the abdominal aorta (2), as was found in the present study. This is inspite of the fact that the right kidney is located much inferior compared to the left kidney. Accessory renal arteries (Table/Fig 10): Accessory renal arteries were found in 14.8% of the cases in the present study more frequently on the left side which is similar to incidences obtained by Majos M et al., (19.35%) and Ahmed MAAS et al., who found accessory renal arteries in 14%, more commonly on the right side (2),(15) (Table/Fig 10) (2),(12),(15),(16),(17). Infrarenal aorta: The mean length of the infrarenal aorta obtained in the present study was 9.68 cm. A similar dimension was obtained by Yang SS et al., (9.5 cm). A significantly lengthier infrarenal aorta (<0.7 cm) has been reported among the elderly in comparison with the younger population (18). No other significant study was found focussed on the evaluation of AL. Limitation(s) The current study did not cater for gender and age related differences in the renal arteries and infrarenal aorta. Renal artery diameters and lengths of accessory renal arteries were not measured in this study which could also potentially influence the pathophysiology of renal vascular diseases and surgical interventions. | ||||||||||||||||||||||||||||||||||||||||||||||||||||
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