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CT localization of axillary lymph nodes in relation to the humeral head: Significance of arm position for radiation therapy planning
Radiotherapy and Oncology 77 (2005) 191–193 www.thegreenjournal.com
Medical physics
CT localization of axillary lymph nodes in relation to the humeral head: Significance of arm position for radiation therapy planning David B. Mansura,*, Feng-Ming Kongb, Issam El Naqaa, Marie E. Taylora, Imran Zoberia, Jeffrey D. Bradleya, Carlos A. Pereza, Eric E. Kleina a
Department of Radiation Oncology, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, MO, USA, b Department of Radiation Oncology, University of Michigan School of Medicine, Ann Arbor, MI, USA
Abstract Irradiation of the axillary nodes is often indicated in the clinical radiotherapy of patients with lymphoma and breast cancer. The relative location of the axillary nodes and the humeral head has historically been estimated based on lymphangiographic data. Since CT offers more precise definition, the axillary nodal region in relation to the humeral head was systematically studied in 61 patients undergoing CT simulation for breast conservation therapy. Differences in arm position (degree of abduction) significantly affected the location of the axillary nodal region in relation to the humeral head. With the arm abducted beyond 55 degrees, humeral head blocking would result in blocking of some of the axillary nodes. q 2005 Elsevier Ireland Ltd. All rights reserved. Radiotherapy and Oncology 77 (2005) 191–193. Keywords: Axillary lymph nodes; Radiation therapy
The axillary lymph node region is commonly included in the radiation therapy target volume in patients with carcinoma of the breast and lymphomas. Different techniques have been used, and whether or not to block the humeral head is often considered. Lymphangiographic data was historically used to estimate the position of the axillary nodes [6,9,10]. However, CT simulation allows precise localization of the entire axillary lymph node region [2]. In order to study the position of the axillary lymph nodes relative to the humeral head, the CT simulation images of 61 breast conservation patients were systematically investigated as a function of arm position.
and (c) the inferior-most aspect of the humeral head. At each of these levels, the transverse distance between the medial-most edge of the humeral head and the lateral-most edge of the axillary nodal region was recorded. If these structures overlapped, a negative value was recorded. This transverse distance was defined as the axillary node–humeral head (axn–hh) distance (Fig. 1B). In addition, for each axilla the humeral head angle, defined as the angle between the long axis of the humerus and the long axis of the body, was recorded (Fig. 1A). For this study, both axillas were analyzed, providing a wide range of humeral head angles. The axn–hh distance, especially the presence or absence of overlap, at the three axial levels was then examined as a function of humeral head angle.
Materials and methods Bilateral axillary nodal regions were identified in 61 consecutive breast conservation patients (122 axillas) undergoing CT simulation according to an axial CT atlas [3]. This region was defined based on the fat space around the axillary vessels, excluding the muscles. All patients were supine, with the ipsilateral hand raised over the head. The transition from axillary to supraclavicular nodes can be subjective. For this study, any nodes inferior to the clavicle were considered axillary. Specifically, three axial levels were examined with regard to the relative position of the axillary nodal region and the humeral head (Fig. 1A). These slices were located at, from superior to inferior: (a) the inferior aspect of the acromion process, (b) the midpoint of the coracoid process,
Results and discussion The axn–hh distances as a function of humeral head angle are presented in Fig. 2. The median axn–hh distances at the acromion, coracoid, and inferior humeral head measured 2.3, 0.0, and K2.9 cm, respectively, if the humeral angle was R1308 (Fig. 2A). For humeral head angles O90 and ! 1308, the median axn–hh distances measured 2.7, 0.2, and K1.8 cm at the acromion, coracoid, and inferior humeral head levels, respectively (Fig. 2B). For humeral head angles %558, the median axn–hh distances at the acromion, coracoid, and inferior humeral head measured 2.8, 1.0, and 1.6 cm, respectively (Fig. 2C).
0167-8140/$ - see front matter q 2005 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.radonc.2005.09.019
192
CT localization of axillary lymph nodes A
Levels
Acromion
Coracoid
Inferior
6
4
2
0
–2
–4
–2
–4
AXN-HH Distance (HH angles ≥130˚n=37) B
Levels
Acromion
Coracoid
Inferior
6
4
2
0
AXN-HH Distance (HH angles between 90˚ and 130˚n=27) C
Levels
Acromion
Fig. 1. (A) Digitally reconstructed radiograph illustrating the humeral head angle (d) and the three axial levels used for axillary– humeral head distance measurements: (a) acromion, (b) midcoracoid process, and (c) inferior humeral head. (B) Representative slice from CT simulation with localized axillary nodal region (axn), humeral head (hh), and axillary node–humeral head distance.
From viewing the figures, it is evident that at the most superior level examined, the inferior aspect of the acromion process, no significant overlap of axillary nodal region and humeral head is seen, even with humeral head angles greater than 1308. However, it is clear that the axillary nodal region overlaps the humeral head at the remaining two levels in a significant number of patients unless the humeral head angle is less than 558. Therefore, for treatment-planning purposes, with the arm abducted greater than 908, only the most cranial aspect of the humeral head can safely be blocked. In reality, the humeral head block is omitted altogether if the humeral head angle is greater than 908. On the contrary, with the arms abducted to less than 558 in the hands-on-hips (‘akimbo’) position, the entire humeral head can safely be blocked since there is no overlap with the axillary nodal region in any of the patients studied. Lymphangiographic imaging has historically been used to help guide radiation therapy treatment volumes of regional lymph nodes [4,6,9,10]. However, with the
Coracoid
Inferior
6
4
2
0
–2
–4
AXN-HH Distance (cm) (HH angles ≤ 55˚ n=58) Fig. 2. Box plots comparing axn–hh distances for levels examined as a function of humeral head angle. Data are pooled into three sets of humeral head angles A, B, and C. The boxed extent shows the 25 and 75% quartiles of the distribution with the box ‘cinched’ by the dotted line representing the median. The 95% confidence is represented by the horizontal dotted lines (whiskers). Points beyond this distribution are considered outliers (C).
advent of CT simulation, more precise definition of the axillary lymph node regions has been made possible [2]. The implications of CT based axillary node definition for breast radiotherapy has been investigated by several authors [1,5,7,8]. The current study utilizes CT information and confirms the prior lymphangiographic observations that the axillary nodes overlap the humeral head when the arm is abducted. The relative importance of including a humeral head block will vary depending on the specific clinical situation. It is hoped these CT-based anatomic data will help the clinician in defining required treatment portals.
D.B. Mansur et al. / Radiotherapy and Oncology 77 (2005) 191–193
There are several limitations to this study. To begin with, this CT information does not account for divergence. Therefore projection differences are not addressed here, as they were with older, fluoroscopic-based studies [9,10]. In addition, in this cohort of breast conservation patients, there were no humeral head angles between 55 and 908, therefore, no comment can be made with regard to the axillary node position relative to the humeral head for these angles. In addition, since this study included only women, it does not address potential gender-specific differences in nodal position. Therefore, extrapolation of this data to male populations should be done with caution. Bearing in mind these limitations, and acknowledging that these data have not been prospectively evaluated, this study does provide CT confirmation that axillary node position is dependent on arm position and the humeral head should only be blocked if the arm is adducted to 558 or less.
Acknowledgements The authors thank Ms Gail Countie for assistance with the manuscript.
* Corresponding author. David B. Mansur, Department of Radiation Oncology, Mallinckrodt Institute of Radiology, Washington University School of Medicine, 4921 Parkview Place, Box 8224, St Louis, MO 63110, USA. E-mail address: [email protected] Received 11 March 2005; received in revised form 17 August 2005; accepted 26 September 2005
193
References [1] Aristei C, Chionne F, Marsella AR, et al. Evaluation of level I and II axillary nodes included in the standard breast tangential fields and calculation of the administered dose: results of a prospective study. Int J Radiat Oncol Biol Phys 2001;51:69–73. [2] Dijkema IM, Hofman P, Raaijmakers CPJ, Lagendijk JJ, Battermann JJ, Hillen B. Loco-regional conformal radiotherapy of the breast: delineation of the regional lymph node clinical target volumes in treatment position. Radiother Oncol 2004;71: 287–95. [3] Martinez-Monge R, Fernandes PS, Gupta N, Gahbauer R. Crosssectional nodal atlas: a tool for the definition of clinical target volumes in three-dimensional radiation therapy planning. Radiology 1999;211:815–28. [4] Nisce LZ, D’Angio GJ. Radiation therapy for Hodgkin’s disease: memorial hospital techniques. In: Lacher MJ, editor. Hodgkin’s Disease. New York: Wiley; 1976. p. 145–77. [5] Reznik J, Cicchetti MG, Degaspe B, Fitzgerald TJ. Analysis of axillary coverage during tangential radiation therapy to the breast. Int J Radiat Oncol Biol Phys 2005;61:163–8. [6] Shibata HR, McLean P, Vezina JL, Inglis FG, Tabah EJ. Axillary lymphography in carcinoma of the breast. Surgery 1966;60: 329–35. [7] Smitt MC, Goffinet DR. Utility of three-dimensional planning for axillary node coverage with breast-conserving radiation therapy: early experience. Radiology 1999;210:221–6. [8] Takeda A, Shigematsu N, Kondo M, et al. The modified tangential irradiation technique for breast cancer: how to cover the entire axillary region. Int J Radiat Oncol Biol Phys 2000;46:815–22. [9] Weisenburger TH, Juillard GJF. Axillary lymphangiograms in radiation therapy of lymphomas. Radiology 1974;113:463–5. [10] Weisenburger TH, Juillard GJF. Upper extremity lymphangiography in the radiation therapy of lymphomas and carcinoma of the breast. Radiology 1977;122:227–30.
Medical physics
CT localization of axillary lymph nodes in relation to the humeral head: Significance of arm position for radiation therapy planning David B. Mansura,*, Feng-Ming Kongb, Issam El Naqaa, Marie E. Taylora, Imran Zoberia, Jeffrey D. Bradleya, Carlos A. Pereza, Eric E. Kleina a
Department of Radiation Oncology, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St Louis, MO, USA, b Department of Radiation Oncology, University of Michigan School of Medicine, Ann Arbor, MI, USA
Abstract Irradiation of the axillary nodes is often indicated in the clinical radiotherapy of patients with lymphoma and breast cancer. The relative location of the axillary nodes and the humeral head has historically been estimated based on lymphangiographic data. Since CT offers more precise definition, the axillary nodal region in relation to the humeral head was systematically studied in 61 patients undergoing CT simulation for breast conservation therapy. Differences in arm position (degree of abduction) significantly affected the location of the axillary nodal region in relation to the humeral head. With the arm abducted beyond 55 degrees, humeral head blocking would result in blocking of some of the axillary nodes. q 2005 Elsevier Ireland Ltd. All rights reserved. Radiotherapy and Oncology 77 (2005) 191–193. Keywords: Axillary lymph nodes; Radiation therapy
The axillary lymph node region is commonly included in the radiation therapy target volume in patients with carcinoma of the breast and lymphomas. Different techniques have been used, and whether or not to block the humeral head is often considered. Lymphangiographic data was historically used to estimate the position of the axillary nodes [6,9,10]. However, CT simulation allows precise localization of the entire axillary lymph node region [2]. In order to study the position of the axillary lymph nodes relative to the humeral head, the CT simulation images of 61 breast conservation patients were systematically investigated as a function of arm position.
and (c) the inferior-most aspect of the humeral head. At each of these levels, the transverse distance between the medial-most edge of the humeral head and the lateral-most edge of the axillary nodal region was recorded. If these structures overlapped, a negative value was recorded. This transverse distance was defined as the axillary node–humeral head (axn–hh) distance (Fig. 1B). In addition, for each axilla the humeral head angle, defined as the angle between the long axis of the humerus and the long axis of the body, was recorded (Fig. 1A). For this study, both axillas were analyzed, providing a wide range of humeral head angles. The axn–hh distance, especially the presence or absence of overlap, at the three axial levels was then examined as a function of humeral head angle.
Materials and methods Bilateral axillary nodal regions were identified in 61 consecutive breast conservation patients (122 axillas) undergoing CT simulation according to an axial CT atlas [3]. This region was defined based on the fat space around the axillary vessels, excluding the muscles. All patients were supine, with the ipsilateral hand raised over the head. The transition from axillary to supraclavicular nodes can be subjective. For this study, any nodes inferior to the clavicle were considered axillary. Specifically, three axial levels were examined with regard to the relative position of the axillary nodal region and the humeral head (Fig. 1A). These slices were located at, from superior to inferior: (a) the inferior aspect of the acromion process, (b) the midpoint of the coracoid process,
Results and discussion The axn–hh distances as a function of humeral head angle are presented in Fig. 2. The median axn–hh distances at the acromion, coracoid, and inferior humeral head measured 2.3, 0.0, and K2.9 cm, respectively, if the humeral angle was R1308 (Fig. 2A). For humeral head angles O90 and ! 1308, the median axn–hh distances measured 2.7, 0.2, and K1.8 cm at the acromion, coracoid, and inferior humeral head levels, respectively (Fig. 2B). For humeral head angles %558, the median axn–hh distances at the acromion, coracoid, and inferior humeral head measured 2.8, 1.0, and 1.6 cm, respectively (Fig. 2C).
0167-8140/$ - see front matter q 2005 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.radonc.2005.09.019
192
CT localization of axillary lymph nodes A
Levels
Acromion
Coracoid
Inferior
6
4
2
0
–2
–4
–2
–4
AXN-HH Distance (HH angles ≥130˚n=37) B
Levels
Acromion
Coracoid
Inferior
6
4
2
0
AXN-HH Distance (HH angles between 90˚ and 130˚n=27) C
Levels
Acromion
Fig. 1. (A) Digitally reconstructed radiograph illustrating the humeral head angle (d) and the three axial levels used for axillary– humeral head distance measurements: (a) acromion, (b) midcoracoid process, and (c) inferior humeral head. (B) Representative slice from CT simulation with localized axillary nodal region (axn), humeral head (hh), and axillary node–humeral head distance.
From viewing the figures, it is evident that at the most superior level examined, the inferior aspect of the acromion process, no significant overlap of axillary nodal region and humeral head is seen, even with humeral head angles greater than 1308. However, it is clear that the axillary nodal region overlaps the humeral head at the remaining two levels in a significant number of patients unless the humeral head angle is less than 558. Therefore, for treatment-planning purposes, with the arm abducted greater than 908, only the most cranial aspect of the humeral head can safely be blocked. In reality, the humeral head block is omitted altogether if the humeral head angle is greater than 908. On the contrary, with the arms abducted to less than 558 in the hands-on-hips (‘akimbo’) position, the entire humeral head can safely be blocked since there is no overlap with the axillary nodal region in any of the patients studied. Lymphangiographic imaging has historically been used to help guide radiation therapy treatment volumes of regional lymph nodes [4,6,9,10]. However, with the
Coracoid
Inferior
6
4
2
0
–2
–4
AXN-HH Distance (cm) (HH angles ≤ 55˚ n=58) Fig. 2. Box plots comparing axn–hh distances for levels examined as a function of humeral head angle. Data are pooled into three sets of humeral head angles A, B, and C. The boxed extent shows the 25 and 75% quartiles of the distribution with the box ‘cinched’ by the dotted line representing the median. The 95% confidence is represented by the horizontal dotted lines (whiskers). Points beyond this distribution are considered outliers (C).
advent of CT simulation, more precise definition of the axillary lymph node regions has been made possible [2]. The implications of CT based axillary node definition for breast radiotherapy has been investigated by several authors [1,5,7,8]. The current study utilizes CT information and confirms the prior lymphangiographic observations that the axillary nodes overlap the humeral head when the arm is abducted. The relative importance of including a humeral head block will vary depending on the specific clinical situation. It is hoped these CT-based anatomic data will help the clinician in defining required treatment portals.
D.B. Mansur et al. / Radiotherapy and Oncology 77 (2005) 191–193
There are several limitations to this study. To begin with, this CT information does not account for divergence. Therefore projection differences are not addressed here, as they were with older, fluoroscopic-based studies [9,10]. In addition, in this cohort of breast conservation patients, there were no humeral head angles between 55 and 908, therefore, no comment can be made with regard to the axillary node position relative to the humeral head for these angles. In addition, since this study included only women, it does not address potential gender-specific differences in nodal position. Therefore, extrapolation of this data to male populations should be done with caution. Bearing in mind these limitations, and acknowledging that these data have not been prospectively evaluated, this study does provide CT confirmation that axillary node position is dependent on arm position and the humeral head should only be blocked if the arm is adducted to 558 or less.
Acknowledgements The authors thank Ms Gail Countie for assistance with the manuscript.
* Corresponding author. David B. Mansur, Department of Radiation Oncology, Mallinckrodt Institute of Radiology, Washington University School of Medicine, 4921 Parkview Place, Box 8224, St Louis, MO 63110, USA. E-mail address: [email protected] Received 11 March 2005; received in revised form 17 August 2005; accepted 26 September 2005
193
References [1] Aristei C, Chionne F, Marsella AR, et al. Evaluation of level I and II axillary nodes included in the standard breast tangential fields and calculation of the administered dose: results of a prospective study. Int J Radiat Oncol Biol Phys 2001;51:69–73. [2] Dijkema IM, Hofman P, Raaijmakers CPJ, Lagendijk JJ, Battermann JJ, Hillen B. Loco-regional conformal radiotherapy of the breast: delineation of the regional lymph node clinical target volumes in treatment position. Radiother Oncol 2004;71: 287–95. [3] Martinez-Monge R, Fernandes PS, Gupta N, Gahbauer R. Crosssectional nodal atlas: a tool for the definition of clinical target volumes in three-dimensional radiation therapy planning. Radiology 1999;211:815–28. [4] Nisce LZ, D’Angio GJ. Radiation therapy for Hodgkin’s disease: memorial hospital techniques. In: Lacher MJ, editor. Hodgkin’s Disease. New York: Wiley; 1976. p. 145–77. [5] Reznik J, Cicchetti MG, Degaspe B, Fitzgerald TJ. Analysis of axillary coverage during tangential radiation therapy to the breast. Int J Radiat Oncol Biol Phys 2005;61:163–8. [6] Shibata HR, McLean P, Vezina JL, Inglis FG, Tabah EJ. Axillary lymphography in carcinoma of the breast. Surgery 1966;60: 329–35. [7] Smitt MC, Goffinet DR. Utility of three-dimensional planning for axillary node coverage with breast-conserving radiation therapy: early experience. Radiology 1999;210:221–6. [8] Takeda A, Shigematsu N, Kondo M, et al. The modified tangential irradiation technique for breast cancer: how to cover the entire axillary region. Int J Radiat Oncol Biol Phys 2000;46:815–22. [9] Weisenburger TH, Juillard GJF. Axillary lymphangiograms in radiation therapy of lymphomas. Radiology 1974;113:463–5. [10] Weisenburger TH, Juillard GJF. Upper extremity lymphangiography in the radiation therapy of lymphomas and carcinoma of the breast. Radiology 1977;122:227–30.