Rand F.doc J Bagh College Dentistry Vol. 25(2), June 2013 Sonographic assessment Oral Diagnosis 94 Sonographic assessment of normal cervical lymph nodes in a sample of Syrian population Rand Sh. Al-Ani, B.D.S., M.Sc. (1) Ammar M. Mashlah, B.D.S., M.Sc., Ph.D. (2) Mohammad Iyad Al-Hafar, B.D.S., M.Sc., Ph.D. (3) ABSTRACT Background: Sonographic examination is an important tool in assessment of normal and abnormal cervical lymph nodes. The aim of the study is to assess the distribution and the characteristic features of normal cervical lymph nodes in a sample of Syrian population. Materials and Methods: Fifty healthy Syrian subjects (25 men and 25 women) with an age of 20 -60years old, who had their cervical lymph nodes examined by ultrasound. Three hundred and two lymph nodes were detected. Lymph nodes were evaluated for their number, size, site, echogenic hilus, shape, as well as for the border sharpness. The subjects were categorized by age into four groups, (20 -30, 31 - 40 , 41 - 50 , 51- 60 years ). Statistical analysis of data was done using SPSS software (version 11.5), and analytical one way analysis of variance (ANOVA), Duncan’s Multiple Range Test. Results: The results showed that there was no significant difference in mean number of nodes between different age groups. All lymph nodes were hypoechoic; majority of them possessed an echogenic hilus, with transverse diameter of 8 mm or less. All lymph nodes were oval except for submandibular and parotid nodes which appeared round. Conclusions: This study provides a sonographic appearance of normal cervical lymph nodes in relation to their site, size, shape, numbers, border sharpness, and echogenic hilum, in a sample of Syrian population. Key words: Gray scale sonography, cervical lymph node, Syrian population. (J Bagh Coll Dentistry 2013; 25(2):94- 100). الخالصة توزیع وخصائص العقد اللمفاویة تقییم : الھدف من البحث. یعتبر الفحص باألمواج فوق الصوتیة من األدوات المھمة لتقییم العقد اللمفاویة العنقیة السلیمة وغیر السلیمة:.البحث خلفیة . العنقیة السلیمة لدى عینة من المجتمع السوري سنة، باستخدام جھاز األمواج فوق الصوتیة، تم الكشف عن 60-20بعمر ) أنثى 25ذكرا و 25(تم فحص العقد اللمفاویة العنقیة السلیمة لخمسین فردا سوریا : مواد وطرائق البحث - 30،31-20(ُقسمت أفراد العینة إلى الفئات العمریة التالیة . یمت ھذه العقد من ناحیة العدد،والحجم،والموقع، ووجود السرة، والشكل، فضال عن وضوح الحافاتعقدة لمفاویة، ُق 302 .Duncan's Multiple Range ,(ANOVA)، واختبارات SPSS(version 11.5)تم انجاز التحلیل اإلحصائي باستخدام برنامج ). سنة 50،51-60- 40،41 جمیع العقد .ملیمتر 8≤ ستعرض أظھرت النتائج عدم وجود اختالفات معنویة بین الفئات العمریة ، جمیع العقد اللمفاویة منخفضة الصدى،ومعظمھا تحتوي على سرة ،وبقطر م:النتائج ).0.5≥القطر الطولي /نسبة القطر المستعرض(تحت الفك األسفل والنكفیة كانت دائریة الشكل ،باستثناء العقد اللمفاویة )0.5<القطر الطولي/نسبة القطر المستعرض(بیضویة الشكل ل، والعدد، ووضوح الحافات، ھذه الدراسة أوضحت مظاھر العقد اللمفاویة العنقیة السلیمة في الفحص باألمواج فوق الصوتیة بما یتعلق بموقع العقد ، والحجم ، والشك: االستنتاج .رة لدى عینة من المجتمع السوري ووجود الس . األمواج فوق الصوتیة،العقد اللمفاویة الرقبیة، المجتمع السوري :كلمات مفتاحیھ INTRODUCTION Ultrasound (US) is a useful imaging modality in the evaluation of cervical lymphadenopathy (1,2). Gray-scale sonography is widely used in evaluation of the number, size, site, shape, borders, matting, adjacent soft-tissue edema, and internal architectures of cervical lymph nodes (3,4). Ultrasonography allows the evaluation of not only lymph nodes that are 10 mm in diameter or more, which are generally diagnosed as cervical lymph node metastasis-positive by computed tomography (CT) or magnetic resonance imaging (MRI), but also lymph nodes of less than 10 mm diameter, based on sufficient image information (5). Although CT and MRI are used to evaluate cervical lymph nodes, the nature and internal architecture of small lymph nodes (<5 mm) may not be readily assessed (6). (1) PhD. Student. Department of Oral Medicine, Dentistry College, Damascus University. (2) Professor. Department of Oral Medicine, Dentistry College, Damascus University. (3) Assistant. Professor. Department of Oral Medicine, Dentistry College, Damascus University. The inaccuracy of clinical palpation paved the way for further studies in search of other more accurate diagnostic means for detecting neck nodes. Debate persists over the relative merits of imaging in the evaluation of the neck for metastatic disease. Imaging techniques like CT and MRI have been popularized to detect metastatic neck nodes (7). Many previous researches have usually studied pathologic nodes, and few studies have examined normal cervical lymph nodes (8-10) and these were predominantly in Caucasians. To our knowledge, the distributions of normal cervical lymph nodes in a sample of Syrian population have not been described previously. A clear understanding of the distribution and sonographic appearances of normal cervical lymph nodes is necessary in differentiating normal from abnormal nodes. The purpose of this study was to assess the sonographic features of normal cervical lymph nodes in different regions of the neck, in a sample of Syrian population. J Bagh College Dentistry Vol. 25(2), June 2013 Sonographic assessment Oral Diagnosis 95 MATERIALS AND METHODS Fifty healthy Syrian subjects (25 men and 25 women) with no history of neck surgery, glandular fever, chronic tonsillitis, tuberculosis, head and neck malignancy, or lymphomas, were included in the study. The age for the subjects was 20-60 years, average age: 40 years. All the scans were performed with Convex Scanner/Convex/Linear Ultrasonic Scanner (HS- 4000 Honda Electronic CO., LTD-Japan) and 10 MHz linear-array transducer. The subjects lay supine on the couch with the shoulders supported by a pillow. The neck was hyper extended. Since the shape of the nodes depends on the scan plane, scans were obtained with the transducer placed transversely and longitudinally until the plane showed the maximum cross-sectional area of the lymph node. Eight regions in the neck were delineated as described by Hajek et al. (11): (1) submental ,(2) submandibular, (3) parotid , (4) upper cervical, above the hyoid bone and along the common carotid artery ( CCA ) and internal jugular vein ( IJV ), (5) middle cervical, between the hyoid bone and the cricoid cartilage and along the CCA and IJV, (6) lower cervical, below the cricoid cartilage and along the CCA and IJV, (7) supraclavicular fossa , and (8) posterior triangle (also known as accessory chain),as shown in figure 1. All lymph nodes were divided into left and right site, except the submental nodes, which are located in the midline. All detected lymph nodes were assessed for their site, size, numbers, shape (short-to-long-axis [S/L] ratio), and border sharpness , as well as for the presence of an echogenic hilum. The parameters which were considered in this study and their definition are as follows: 1. Distribution: the cervical lymph nodes were categorized into eight regions or levels on the basis of their location in the neck (11). 2. Mean long axis (L), which is the largest dimension of the lymph node. 3. Mean short axis (S), which is the greatest dimension perpendicular to (L). 4. Shape index (S/L): the ratio of S and L. The nodes were divided into 2 groups as S/L < 0.5 indicates a long or oval node, whereas S/L ≥0.5 indicates a rounded node. 5. Echotexture and homogenicity: lymph nodes were divided as hypoechoic, isoechoic, or hyperechoic to surrounding muscles (12). 6. Echogenic hilus: the major vascular hilus appears as a hyperechoic linear structure within a lymph node and is continuous with the surrounding connective tissue (13) as shown in figure 2. 7. The nodal border was assessed for its sharpness, which determined by the smoothness of the margin between the lymph node and the surrounding tissue; this border is either well-defined/ sharp border or ill-defined/ unsharp border (9). The maximum transverse diameter of each node was used to determine mean nodal size. The shape of a lymph node, as visualized on sonography, varies by scan plane, so the short and long axis of the lymph nodes were measured in the plane that showed the maximum cross- sectional area .The subjects were categorized by age into groups, ( 20 -30 years, 31 - 40 years, 41 - 50 years, 51-60 years). Statistical analysis of data was done using SPSS software (version 11.5), include descriptive (frequency, percentage, mean, standard deviation),and analytical one way analysis of variance (ANOVA), followed by Duncan's Multiple Range Test . Difference was considered as significant when P < 0.05. RESULTS In 50 subjects, 302 lymph nodes were detected. All subjects had bilateral lymph nodes. The smallest node detected in this study measured 2.0 mm x 4.5 mm , and the largest node measured 8.3 ×19.9 mm . There were 162 nodes in the 25 male subjects and 140 nodes in the 25 female subjects. The mean number of lymph nodes in male subjects (6.48 nodes) is higher than that in female subjects (5.60 nodes). When the subjects were classified into five different age groups (20 -30 , 31 - 40 , 41 - 50 , 51-60 years), no significant difference was found in mean number of nodes between different age groups, as shown in tables 1,2,3. The number, shape, border sharpness, short axis, and long axis of the lymph nodes in different regions of the neck are shown in table 4. Majority of lymph nodes detected in this study (98.8%) had a transverse diameter of 8 mm or less as shown in figure 3. Evaluation of lymph node size based on short axis were less than 5mm as shown in figure 4 , while evaluation of lymph node size based on long axis shows that , the majority of nodes in the cervical chain, and posterior triangle were larger than 8 mm as in figure 5. The optimum cut-off value of the S/L ratio was determined in different regions of the neck: submental (0.43), submandibular (0.61), parotid (0.58), upper cervical (0.42), middle cervical J Bagh College Dentistry Vol. 25(2), June 2013 Sonographic assessment Oral Diagnosis 96 (0.36), lower cervical(0.31), supraclavicular(0.41) and posterior triangle (0.42),as shown in figure 6. DISCUSSION This study was done in Department of Oral Medicine, Dentistry College, Damascus University. Normal superficial lymph nodes are not palpable and, quite often, they are not seen with US. Inflammatory or reactive nodes may become apparent on US, still being impalpable. Palpable and visible nodes may be benign or malignant (14,15) . All subjects in this study had at least five lymph nodes detected , and there is no age and gender difference in the average number of normal cervical nodes, this results agree with Ying et al (10) and Ying et al (15). The normal lymph nodes that were detected in the present study were the submandibular (region 2), 41.3%, parotid (region 3) 25.8%, upper cervical (region4) 13.2%, submental (region 1) 5.6%, middle cervical (region 5) 4.3%, supraclavical (region 7) 3.9%, posterior triangle (region 8) 3.9%, and lower cervical (region 6) 1.6%.The distribution of the nodes are almost similar to previous studies (9,15). As multiple lymph node involvement is common in lymphoma and metastasis, the solitariness of lymph nodes may be useful in diagnosis (16). All lymph nodes found in submental, middle cervical, lower cervical, supraclavicular, and posterior regions are solitary 100% , while submandibular region shows 82.35% (solitary), 13.73% (paired), 3.92% (multiple), the parotid region 98.68% (solitary), 1.32% (multiple), and the upper cervical region 67.44% (solitary), 2.56% (paired). This result is in agreement with Ying et al (9) and Ying et al (15) ,except in posterior triangle lymph nodes which appear multiple in their study, they suggested that, since multiple lymph nodes are common in posterior triangle, multiplicity of lymph nodes alone is not useful for diagnosis in this region, and other features need to be elicited. The echogenicity of normal lymph nodes varies between hypoechoic and isoechoic in comparison to the surrounding fatty tissue. Both reactive and malignant lymph nodes are hypoechoic compared to neighboring strap muscles. Lymphomatous, tuberculous and lymphadenitis nodes are also hypoechoic; therefore hypoechogenicity is not a useful diagnostic sign (3,4). In the eight regions studied, all lymph nodes (100%) are hypoechoic. The normal parenchyma exhibits homogeneous and low echogenicity because of the predominance of a homogeneous cell population of lymphocytes without much tissue interface (17). Majority of lymph nodes detected in this study (98.8%) had a transverse diameter of 8 mm or less as shown in figure 3,4, this result is in agreement with Ying et al (15), who investigated that most nodes in white and Chinese subjects had a maximum transverse diameter of 8 mm or less (96% and 98%, respectively), and in agreement with other studies (8,9) , which shows that (95%) of the nodes had a maximum transverse diameter of 8 mm or less. Evaluation of size based on long axis of the nodes shows that, the majority of nodes in the cervical chain, and posterior triangle were larger than 8 mm as in figure 5. This is also similar to the finding of Bruneton et al (8), who stated that cervical nodes except submental and submaxillary groups usually demonstrate a larger longitudinal diameter and a shorter transverse diameter. Shape has been stated to be a useful criterion in differentiating normal or reactive nodes from malignant nodes. An oval node (S/L ratio < 0.5) indicates normal or reactive node, whereas malignant nodes tend to be round (S/L ratio ≥ 0.5) (3,18). Lymph nodes that were detected in this study were oval in shape (S/L ratio < 0.5) , with the exception of submandibular and parotid nodes which appeared round ( S/L ratio ≥ 0.5) ,similar to the results of Ying et al (9),Ying et al (15) and Ying and Ahuja (19). Although pathologic nodes are usually round, normal submandibular and parotid nodes can also be round in shape (95% and 59% respectively) (9) .This may be due to inflammation in the oral cavity which predisposes to the development of reactive hyperplasia in these lymph nodes ,leading to proliferation of lymphocytes within the lymphoid follicles, and cortical widening occurs in every region of the lymph node, and their shape becomes ovoid to round (20) .Therefore, shape of lymph nodes cannot be the sole criterion in the diagnosis . Normal and reactive nodes present a central echogenic hilum that interrupts the continuity of the cortical and is continued with the perinodal fat tissue. This appearance is due to the abutment of multiple medullar sinuses acting as interfaces (3, 4, 21) . It has been shown that about 90% of benign cervical nodes with a diameter above 5mm display an echogenic hilum (4) .This study shows that 89.53% of detected nodes possessed an echogenic hilus, while 10.47% of nodes do not show echogenic hilus. Nodes without echogenic hilus have a transverse axis less than 3mm (small lymph nodes). This result is in agreement with J Bagh College Dentistry Vol. 25(2), June 2013 Sonographic assessment Oral Diagnosis 97 Ying et al (22), who stated that echogenic hilus is a normal sonographic feature of most of the normal cervical lymph nodes (86%) , and small lymph nodes may not show echogenic hilus. This study showed that normal lymph nodes in the upper neck (submental, submandibular , parotid , and upper cervical regions) usually have illdefind borders (88.24% , 81.6% , 94.9% , 72.5% respectively), whereas lymph nodes in middle cervical (92.3%) , lower cervical (80%) , supraclavicular (91.6%) , and posterior region(83.3%) predominantly have well defined borders, which is in agreement with Ying et al (22) .The high frequency of unsharp borders of submental , submandibular , and parotid nodes may be due to poor transducer contact, as these nodes are under the ramus of the mandible , and may also be related to the deposition of fat within the nodes . Thus , nodes with sharp borders are seen predominantly in lower neck and posterior triangle , whereas unsharp nodes are common in the upper neck (23). As the longitudinal diameter of the nodes is an unreliable criterion in the differential diagnosis of cervical nodes (24), only the maximum transverse diameter of each node was used to determine mean nodal size. When combining size and shape and using 5 mm, 8 mm, and 1 cm as cut-off point in short axis, this study shows that, with 5 mm as cut-off point 57.2% fulfilled both criteria for normality, with 8 mm as cut- off point 49.1% fulfilled both criteria, and with I cm as cut-off point 48.3% fulfilled both criteria for normality . Therefore, we suggested that, nodal size (short axis) greater than 10 mm combined with an S/L ratio greater than 0.5 may be useful to identify pathologic nodes. Similar findings also have been reported by Sugama and Kitamura (25), who showed that lymph nodes with a transverse diameter of 10 rnm and an S/L ratio greater than 0.5 were likely to be metastatic. The optimum cut-off value of the S/L ratio was determined in different regions of the neck: submental (0.43), submandibular (0.61), parotid (0.58), upper cervical (0.42), middle cervical (0.36), lower cervical(0.31), supraclavicular(0.41) and posterior triangle (0.42), this result is almost similar to Ying et al (26), they concluded that the optimum cut-off value in different regions of the neck was: submental (0.5), submandibular (0.7), parotid (0.5), upper cervical (0.4), middle cervical (0.3) and posterior triangle (0.4). This study evaluates the distribution and the characteristic features of normal cervical lymph nodes in a sample of Syrian population. Normal cervical nodes are found in eight regions of all subjects, particularly in the submandibular, parotid, and upper cervical regions. All nodes are hypoechoic. The majority of nodes demonstrate an echogenic hilus, and with a maximum transverse diameter ≤ 8 mm. The shapes of nodes are oval except the submandibular and parotid regions are round. Normal lymph nodes in the upper neck have ill- defind borders, while lymph nodes in middle cervical, lower cervical, supraclavicular and posterior regions have well defined borders. The S/L ratio in all regions ≤ 0.5 except the submandibular and parotid regions, as these nodes normally have an S/ L ratio greater than 0.5. REFERENCES 1. Haberal I, Celik H, Göçmen H, Akmansu H, Yörük M, Ozeri C. Which is important in the evaluation of metastatic Lymph Nodes in Head and Neck cancer: Palpation, Ultrasonography, or Computed tomography. Otolaryngol Head Neck Surg 2004; 130: 197-201. 2. Esen G. Ultrasound of Superficial Lymph Nodes. Eur J Radiol 2006; 58: 345-59. 3. Ahuja A, Ying M. Sonographic evaluation of cervical lymph nodes. Am J Roentgenol 2005; 184:1691-1699. 4. Ahuja A , Ying M , Ho SY, Antonio G, Lee YP, King AD, Wong KT. Ultrasound of malignant cervical lymph nodes. Cancer Imaging 2008; 8(1): 48–56. 5. Nibu K, Inoue H, Kawabata K, Ebihara Y, Onitsuka T, Fujii T, Saikawa M. Quality of life after neck dissection. JAMA Otolaryngol Head Neck Surg 2005; 31(3): 391-395. 6. Ahuja A, Ying M. An overview of neck node sonography. Invest Radiol 2002; 37: 333. 7. Sureshkannan P, Vijayprabhu, John R. Role of ultrasound in detection of metastatic neck nodes in patients with oral cancer. Indian Journal of Dental Research 2011; 22(3): 419-423. 8. Bruneton JN, Balu-Maestro C, Marcy PY, Melia P, Mourou MY. Very high frequency (13 MHz) ultrasonographic examination of the normal neck: Detection of normal lymph nodes and thyroid nodules. J Ultrasound Med 1994; 13: 87 . 9. Ying M, Ahuja A, Brook F, Brown B , Metreweli C .Sonographic Appearance and Distribution of Normal Cervical Lymph Nodes in a Chinese Population . J Ultrasound Med 1996; 15:431-436 10. Ying M, Ahuja A, Brook F. Sonographic appearances of cervical lymph nodes: Variations by age and sex. Journal of Clinical Ultrasound 2002; 30(1): 1–11. 11. Hajek PC, Salomonowitz E, Turk R, Tscholakoff D, Kumpan W, Czembirek H. Lymph nodes of the neck: Evaluation with US. Radiology 1986; 158:739. 12. Gupta A, Rahman K, Shahid M, Kumar A, Qaseem SM, Hassan SA, Siddiqui FA. Sonographic assessment of cervical lymphadenopathy: Role of high-resolution and color doppler imaging. Head & Neck 2011; 33: 297–302. J Bagh College Dentistry Vol. 25(2), June 2013 Sonographic assessment Oral Diagnosis 98 13. Evans RM, Ahuja A, Metreweli C. The linear echogenic hilus in cervical lymphadenopathy - a sign of benignity or malignancy? Clin Radiol 1993; 47: 262. 14. Ahuja A, Ying M, King A, Yuen HY. Lymph node hilus: gray scale and power Doppler sonography of cervical nodes. J Ultrasound Med 2001;20:987-992. 15. Ying M, Ahuja A, Brook F, Metreweli C. Vascularity and grey-scale sonographic features of normal cervical lymph nodes: variations with nodal size. Clin Radiol 2001; 56: 416-419. 16. Solbiati L, Cioffi V, Ballarati E. Ultrasonography of the neck. Radiol Clin North Am 1992; 30:941. 17. Ariji Y, Kimura Y, Hayashi N, Onitsuka T, Yonetsu K, Hayashi K, Ariji E, Kobayashi T, Nakamura T.Power Doppler sonography of cervical lymph nodes in patients with head and neck cancer. Am J Neuroradiol 1998; 19: 303–307. 18. Khanna R, Sharma AD, Khanna S, Kumar M, Shukla RC.Usefulness of ultrasonography for the evaluation of cervical lymphadenopathy. World J Surg Oncol 2011; 9: 29. 19. Ying M, Ahuja A. Sonography of neck lymph nodes. I. Normal lymph nodes. Clin Radiol 2003; 58:351 – 358. 20. Gritzmann N. Sonography of the neck: Current Potentials and Limitations. J Ultrasound Med 2005; 26:185-196. 21. Ahuja A, Ying M. Sonography of neck lymph nodes. Part II: abnormal lymph nodes. Clin Radiol 2003; 58: 359-366. 22. Ying M, Ahuja A, Brook F, Metreweli C. Vascularity and grayscale sonographic features of normal cervical lymph nodes: variations with nodal size. Clin Radiol 2001; 56: 416-9. 23. Shozushima M, Suzuki M, Nakasirna T, Yanagisawa Y, Sakamaki K, Takeda Y: Ultrasound diagnosis of lymph node metastasis in head and neck cancer. Dentomaxillofac Radiol 1990; 19(4):165-170. 24. Chikui T, Yonetsu K, Nakamura T. Multivariate analysis of sonographic findings on metastatic cervical lymph nodes: contribution of blood flow features revealed by power Doppler sonography in predicting metastasis. Am J Neuroradiol 2000; 21: 561–567. 25. Sugama Y, Kitamura S. Ultrasonographic evaluation of neck and supraclavicular lymph nodes metastasized from lung cancer. Intern Med 1992; 31: 160. 26. Ying M, Ahuja A, Brook F, Brown B, Metreweli C. Nodal shape (S/L) and its combination with size for assessment of cervical lymphadenopathy: which cut- off should be used? Ultrasound Med Biol 1999; 25(8):1169-75. Figure 1: Radiological classification of cervical lymph nodes (11) Figure 2: Gray-scale sonograph of A. upper cervical lymph node. B. Submandibular lymph node. In a healthy 56-years old man, which appear hypoechoic and oval, with echogenic hilus (arrows). A B J Bagh College Dentistry Vol. 25(2), June 2013 Sonographic assessment Oral Diagnosis 99 Table 1: Descriptive statistics of lymph nodes number and age groups Age Group No. Mean + SD 20–30 14 5.50 2.175 31–40 9 6.89 3.296 41–50 10 4.90 2.514 51–60 17 6.71 4.283 SD: Standard deviation Table 2: ANOVA test shows mean number of lymph nodes between different age groups SS Df MS F–value p–value Between groups 31.102 3 10.367 0.956 0.422 Within groups 498.818 46 10.844 Total 529.920 49 P-value> 0.05: not significant Table 3: Duncan's Multiple Range Test shows mean number of lymph nodes between different age groups Age Group No. Mean + SD Duncan's Grouping 20–30 14 5.50 2.175 A 31–40 9 6.89 3.296 A 41–50 10 4.90 2.514 A 51–60 17 6.71 4.283 A SD: Standard deviation Table 4: Features of the lymph nodes in different regions of the neck Features of Nodes Regions of the Neck 1 2 3 4 5 6 7 8 Number 1 Node 100% 82.35% 98.68% 97.44% 100% 100% 100% 100% 2 Nodes 0% 13.73% 0% 2.56% 0% 0% 0% 0% > 3 Nodes 0% 3.92% 1.32% 0% 0% 0% 0% 0% Shape S/L < 0.5 88.2% 28.8% 25.6% 90% 100% 100% 83.3% 91.7% S/L > 0.5 11.8% 71.2% 74.4% 10% 0% 0% 16.7% 8.3% Nodal Border Well–Defined 11.76% 18.4% 5.1% 27.5% 92.3% 80% 91.6% 83.3% Ill–Defined 88.24% 81.6% 94.9% 72.5% 7.7% 20% 8.4% 16.7% Short Axis < 5 mm 94.1% 52.0% 87.2% 87.5% 84.6% 100% 100% 91.7% 5–8 mm 5.9% 42.4% 11.5% 10.0% 15.4% 0% 0% 8.3% > 8 mm 0% 5.6% 1.3% 2.5% 0% 0% 0% 0% Long Axis < 5 mm 0% 8.0% 21.8% 7.5% 15.4% 0% 0% 8.3% 5–8 mm 70.6% 37.6% 56.4% 40.0% 7.7% 60% 91.7% 16.7% > 8 mm 29.4% 54.4% 21.8% 52.5% 76.9% 40% 8.3% 75.0% Echogenic hilus Present Absent 82.7% 98.9% 72.4% 100% 100% 98.1% 80.3% 83.8% 17.3% 1.1% 27.6% 0% 0% 1.9% 19.7% 16.2% J Bagh College Dentistry Vol. 25(2), June 2013 Sonographic assessment Oral Diagnosis 100 R:Region Figure 3: Percentage of lymph nodes with short axis of ≤ 8. R:Region. S:Short axis. Figure 4 : Percentage of lymph nodes size in relation to short axis R:Region. L:Long axis. Figure 5 : Percentage of lymph nodes size in relation to long axis R:Region Figure 6: The optimum cut-off value of the S/L ratio in different regions of the neck.