CT volumetry of normal pancreas: correlation with diameters, and relationship with gender, age and anthropometric parameters

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1 CT volumetry of normal pancreas: correlation with diameters, and relationship with gender, age and anthropometric parameters Poster No.: C-0018 Congress: ECR 2012 Type: Scientific Exhibit Authors: A. Djuric-Stefanovic, D. Masulovic, J. Kostic, K. Randjic, D. Saranovic; Belgrade/RS Keywords: DOI: Abdomen, Anatomy, CT /ecr2012/C-0018 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 13

2 Purpose The most common pathology that affects a pancreas is the enlargement of the pancreas (focal or generalised) which manifests as pancreatic neoplasm and acute pancreatitis, while in chronic pancreatitis, the pancreas decreases in size. In addition, reduction in the pancreatic size in diabetic patients has been reported. Using cross-sectional imaging, pancreatic size is commonly expressed by the anterior-posterior (AP) diameters of the tail, body and head. The volume of the normal pancreas, together with the other abdominal organs, using computed tomography (CT), have been accessed in a few studies published in the literature. However, the relationship between the diameters and the volume of the pancreas has not been analysed. The purposes of this study were: - to determine the range of volumes of the normal pancreas in the adult population using CT, - to analyse the correlation between the pancreatic volume and diameters, and - to estimate if the pancreas volume of is related to the age, gender, and body constitution of the patient. Methods and Materials Subject selection contrast-enhanced CT examinations of adult patients, who had no clinical or CT signs of pancreatic or peri-pancreatic pathology, were selected and retrospectively analysed females (45.4%), 118 males (54.6%). - Aged from 21 to 81 years; average: 55.0 ± 14.0 (women: 53.6 ± 13.6, men: 54.6 ± 14.4, p=0.184). - CT examinations were performed for routine clinical evaluation of the in- and outpatients due to various common indications for the abdominal CT. - Including criteria was the possibility of correct identification and exact isolation of the pancreas from the adjacent structures. Page 2 of 13

3 - Excluding criteria was the presence of either clinical or CT signs of any pancreatic or peri-pancreatic pathology. - According to the regulations of the institutional ethical board protocol, no informed consent from the patients was required for this type of study. Computed tomography - CT examinations were performed in the Center of Radiology and MR, Clinical Center of Serbia, from December 2008 to July CT examinations were performed with a helical scanner (SCT 7800 TC, Shimatzu, Japan) using the following scan parameters: tube current ma/s; voltage 120 kv; section thickness 5 or 7 mm; reconstructed slice thickness 5 mm CT examinations were performed with a 64-section multi-detector row scanner (GE Lightspeed 64-MDCT, General Electrics, USA) using the following scan parameters: tube current ma/s, adjusted to the patient's body build; voltage 120 kv; collimation 64 x mm; reconstructed slice thickness 5 mm. - All abdominal CT scans were done in the cranio-caudal direction, with patients lying in the supine position, and breath holding in deep inspiration, after intravenous injection of the iodinated contrast agent (1 ml/kg of body mass) in the portal-venous phase (55 s scan delay). Analysis of images After identification of the pancreas on CT scans, we applied the following measurements: cranio-caudal (CC) dimensions of the entire pancreas (CC pancreas ), body and tail (CC body&tail), body (CC body ), and head (CC head ). CC diameters were calculated as a product of the number of sections on which particular part of the pancreas is identified, and the section thickness; anterio-posterior (AP) diameters of the tail (AP tail ), body (AP body ), from the lienal vein to the anterior contour of the pancreatic body, and head (AP head ), at the level on which the pair of the superior mesenteric vein and artery is demonstrated; latero-lateral (LL) diameter of the head (LL head ), at the same slice, and length of body and tail (L body&tail ) (Figures 1 and 2). Page 3 of 13

4 Fig.: Figure 1. Anterio-posterior (AP) diameters of the pancreatic body and tail (AP body, AP tail), and lenth of the body and tail (L body&tail). References: A. Djuric-Stefanovic; Dep. for Digestive Radiology, Institute for Radiology - Clinical Center of Serbia, Belgrade, SERBIA Figure 1. Anterio-posterior (AP) diameters of the pancreatic body and tail (AP body, AP tail), and lenth of the body and tail (L body&tail ). Page 4 of 13

5 Fig.: Figure 2. Anterio-posterior (AP) and latero-lateral (LL) diameters of the pancreatic head (AP head, LL head). References: A. Djuric-Stefanovic; Dep. for Digestive Radiology, Institute for Radiology - Clinical Center of Serbia, Belgrade, SERBIA Figure 2. Anterio-posterior (AP) and latero-lateral (LL) diameters of the pancreatic head (AP head, LL head ). In addition, we measured the maximal latero-lateral diameter of the first lumbar vertebral body (LL L1), and the antero-posterior diameter of the subcutaneous fat in the middle line, on the same image (AP SCF), for assessing the body habitus (Figure 3). Page 5 of 13

6 Fig.: Figure 3. Maximal latero-lateral diameter of the first lumbar vertebral body (LL L1), and the antero-posterior diameter of the subcutaneous fat in the middle line (AP SCF). References: A. Djuric-Stefanovic; Dep. for Digestive Radiology, Institute for Radiology - Clinical Center of Serbia, Belgrade, SERBIA Figure 3. Maximal latero-lateral diameter of the first lumbar vertebral body (LL L1), and the antero-posterior diameter of the subcutaneous fat in the middle line (AP SCF). Volume calculation Page 6 of 13

7 Volume measuring was performed using the summation of area technique 7, 13, 14 : the pancreas parenchyma was manually outlined on each section using the free-hand region of interest (ROI) measuring option (Figure 4), and the outlined area was automatically calculated. Product of the pancreatic area and the section thickness represents the volume of pancreas on a single section. Total volume is computed by summing up all section volumes, manually or automatically (Figure 5). Fig.: Figure 4. Summation of area technique of CT volumetry for measuring the volume of the pancreas (pancreatic parenchyma that was manually outlined on each image has been automatically coloured in grey). References: A. Djuric-Stefanovic; Dep. for Digestive Radiology, Institute for Radiology - Clinical Center of Serbia, Belgrade, SERBIA Figure 4. Summation of area technique of CT volumetry for measuring the volume of the pancreas (pancreatic parenchyma that was manually outlined on each image has been automatically coloured in grey). Page 7 of 13

8 Fig.: Figure 5. Automatically computed volume of the pancreas measured by the summation of area technique. Volume of the same pancreas calculated using the proposed formula, according to the measured diameters of the pancreas, was 68.5 cm3. References: A. Djuric-Stefanovic; Dep. for Digestive Radiology, Institute for Radiology - Clinical Center of Serbia, Belgrade, SERBIA Figure 5. Automatically computed volume of the pancreas measured by the summation of area technique. Volume of the same pancreas calculated using the proposed formula, according to the measured diameters of the pancreas, was 68.5 cm 3. Statistical analysis - Independent samples t-test was used to estimate the sex related differences. Page 8 of 13

9 - Paired samples t-test was used to assess if the calculated volume of each pancreas significantly differs from its measured volume by CT volumetry. - Pearson correlation coefficient was used to evaluate the correlations of the volume of pancreas with the subject's age, parameters of body constitution, and pancreatic diameters. Results Pancreatic volume and diameters - Mean pancreatic volume was 79.2 ± 24.1 cm 3 (range: 37.4 cm 3 to cm 3 ). - Pancreatic volume significantly correlated with all enumerated diameters of the pancreas ( p < **). - Diameters of pancreas that were measured, are presented in Table 1. Diameters (mm) Mean ± SD Maximum Minimum Correlation with volume: r CC pancreas 71.0 ± ** CC body&tail 38.0 ± ** CC body 24.6 ± ** CC head 46.0 ± ** AP tail 18.7 ± ** AP body 21.4 ± ** AP head 28.0 ± ** LL head 28.7 ± ** L body&tail ± ** Table 1.Diameters of pancreas that were measured, and Pearson correlation coefficients ( r ) for every measured diameter with the volume of pancreas (** p < ). - We found that pancreatic volume could be computed employing the following formula: Page 9 of 13

10 V pancreas = (AP tail + AP body ) / 2 L body&tail CC body + (AP head / 2) CC head - The volume of pancreas calculated by this formula [79.9 ± 24.8 cm 3 (mean calculated ± SD calculated)], and actual volume measured by the summation-of-areas technique, in each patient, were compared using the paired-samples t-test, and no significant difference was found (t = , DF = 219, p = 0.092; r = 0.985, p < **). Pancreatic volume, gender, and age - The average pancreatic volume was significantly higher in males (86.1 ± 25.4 cm 3 ), than in females (72.8 ± 21.1 cm 3 ) (t = 3.129, DF = 219, p = 0.002**). - Volume of the pancreas did not significantly correlate with age (r = , p = 0.151), although volume, so as all pancreatic diameters, exept L body&tail, generally decreased as age increased. - As Heuck et al reffered that the vertebral body - pancreas diameter ratios, which represent the relative pancreatic size considering the body habitus, strongly correlate with age, we tested if vertebral body - pancreas volume ratio (VB - PV), correlates with age. VB - PV ratio is calculated as a percentage of the maximal transverse diameter of the L1 vertebral body (pancreatic volume divided by LL L1 x 100%). VB - PV ratio [Mean ± SD (177.9% ± 21.1%)], significantly negatively correlated with age (r = , p = 0.011**). Pancreatic volume and anthropometric parameters - Pancreatic volume significantly correlated with the transverse diameter of the L1 vertebral body (r = 0.183, p = 0.008**). - Pancreatic volume did not significantly correlate with the thickness of the abdominal subcutaneous fat (r = , p = 0.104). Page 10 of 13

11 Conclusion - Considerable individual variations in the volume of normal pancreas in the adult population are observed. - Pancreatic volume strongly correlates with the diameters of the pancreas that are commonly measured by the cross-sectional imaging. We found that applying the following formula: V pancreas = (AP tail + AP body ) / 2 L body&tail CC body + (AP head / 2) CC head pancreatic volume could be estimated using a few simple linear measurements, which could be useful in regular practice. - Pancreatic volume significantly correlates with the sex, and the transversal diameter of the first lumbar vertebral body, which represents a marker of body constitution. The volume of the pancreas itself does not significantly correlate with age, while vertebral body - pancreas volume ratio (which includes the influence of the individual's body habitus to the pancreatic size), significantly negatively correlates with age. References 1. Morgan DE, Stanley RJ. The pancreas. In: Lee JK, Sagel SS, Stanly RJ, Haiken JP, editors. Computed body tomography with MRI Corelation. Philadelphia: Lippincot Williams & Wilkins, 2006: Balthazar EJ, Megibow AJ, Pozzi Mucelli R, editors. Imaging of the pancreas. Acute and chronic pancreatitis. Berlin Heidelberg: Springer-Verlag, Gilbeau JP, Poncelet V, Libon E, Derue G, Heller FR. The density, contour and thickness of the pancreas in diabetics: CT findings in 57 patients. AJR 1992;159: Goda K, Sasaki E, Nagata K, Fukai M, Ohsawa N, Hahafusa T. Pancreatic volume in type 1 and type 2 diabetes mellitus. Acta Diabetol 2001;38: Migdalis IN, Voudouris G, Kalogeropoulou K, Iliopoulou V, Koutoulidis K, Samartzis M. Size of the pancreas in non-insulin-dependent diabetic patients. J Med 1991;22: Page 11 of 13

12 6. Alzaid A, Aideyan O, Nawaz S. The size of the pancreas in diabetes mellitus. Diabet Med 1993;10: Saisho Y, Butler AE, Meier JJ et al. Pancreas volumes in humans from birth to age one hundred taking into account sex, obesity, and presence of type-2 diabetes. Clin Anat 2007;20: Vesterhus M, Haldorsen IS, Reader H, Molven A, Njolstad PR. Reduced pancreatic volume in hepatocyte nuclear factor 1A-maturity-onset diabetes of the young. J Clin Endocrinool Metab 2008;93: Sakata N, Egawa S, Rikiyama T et al. Computed tomography reflected endokrine function of the pancreas. J Gastrointest Surg 2011;15: Heuck A, Maubach PA, Reiser M et al. Age-related morphology of the normal pancreas on computed tomography. Gastrointest Radiology 1987;12: Wegener OH. Whole Body Tomography. Boston: Blackwell Scientific Publications, 1993: Schulz Von HG, Christou A, Gursky S, Rother P. Computer-tomographic studies on the normal morphology and volumetry of parenchymatous epigastric organs of man. Anat Anz 1986;162: Geraghty EM, Boone JM, McGahan JP, Jain K. Normal organ volume assessment from abdominal CT. Abdom Imaging 2004;29: Prassopulos P, Daskalogiannaki M, Raissaki M, Hatjidakis A, Gourtsoyiannis N. Determination of normal splenic volume on computed tomography in relation to age, gender and body habitus. Eur Radiol 1997; Harris A, Kamishima T, Hao HY et al. Splenic volume measurements on computed tomography utilizing automatically contouring software and its relationship with age, gender and anthropometric parameters. Eur J Radiol 2010;75: Geraghty EM, Boone JM. Determination of height, weight, body mass index, and body surface area with a single abdominal CT image. Radiology 2003;228: Personal Information Corresponding author: Aleksandra Djuric-Stefanovic 1,2, Page 12 of 13

13 MD, Radiologist; Assistant Professor of Radiology, 2 School of Medicine, Belgrade University, Belgrade, Serbia; 1 First Surgical Clinic - Unit of Radiology, Center of Radiology and MR, Clinical Center of Serbia, Koste Todorovica 6, Beograd, Serbia. julijana.vuk@orion.rs, avstefan@eunet.rs Page 13 of 13