Download MR evaluation of normal pelvic and inguinal lymph nodes

MR evaluation of normal pelvic and inguinal lymph nodes
Poster No.:
C-1979
Congress:
ECR 2011
Type:
Scientific Exhibit
Authors:
M. RAMIREZ-BAILLOEUIL, J.-P. Tasu; Poitiers/FR
Keywords:
Pelvis, MR, Imaging sequences, Metastases, Neoplasia
DOI:
10.1594/ecr2011/C-1979
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Purpose
To estimate pelvic, mesorectal and inguinal lymph nodes (LN) normal size and to
determine superior thresholds in order to differenciate benign versus malignant LN with
conventional MR cross-sectional imaging.
In pelvic malignancies, metastatic lymphatic spread conditions patient's prognostic.
The most important criterion for LN involvement in cross-sectional imaging is still
enlargement.
Very few studies are about pelvic and inguinal LN normal size with MRI.
# Superior thresholds used in routine for short axis are:
› 8 to 10 mm for pelvic and inguinal nodes
› 3 to 5 mm for mesorectal nodes
Methods and Materials
Patient population:
Thirty six healthy volunteers aged 20 to 33 year old were included after informed consent.
People who had absolute or relative MRI contraindication (included pregnancy), pelvic
malignancy history, or infectious or inflammatory symptoms during the six last months
were excluded from the study.
MRI:
Acquisitions were performed on a 1.5 Tesla superconductive magnet (Philips Intera,
Nederland) using a sense body phased array coil. Images were obtained in the strict axial
plane using a steady state gradient echo (balanced-FFE) sequence.
Parameters were as follows: TR 5,3 ms, TE 2,7 ms, #=90°, 3 mm thick contiguous slices,
matrix 512x512.
Slices covered the anatomic region from aorto-iliac fork to the pubic symphysis. Imaging
were read on post-treatment console Adavantage Window (General Electric). Imaging
was performed without enhancement.
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Each lymph node was measured in the maximal short and long axis in a perpendicular
way, in order to realise tenth millimeters measures.
Anatomy:
Each lymph node was caracterized by laterality (right, left, median), size and anatomic
territory, following vascular axis. Eight territory were defined: inguinal, external iliac,
internal iliac, common iliac, obturator, mesorectum, presacral and around bladder, and
described as:
- Inguinal: into the Scarpa area. Upper limit inguinal ligament; lateral limit medial side
of Sartorius muscle; medial limit lateral side of long adductor; anterior limit is the groin
superficial fascia and posterior limit is ilio-psoas and pectine muscle.
- External iliac: between common iliac fork and inguinal ligament. Posterior limit is the
pelvic part of ureter and anterior limit is the femoral septum.
- Internal iliac: along internal iliac artery and its visceral and parietal division. Anterior limit
is the pelvic part of ureter, posterior limit is sacro-iliac joint, upper limit is iliac fork and
inferior limit is levator ani muscle.
- Common iliac: along common iliac artery between aortic and iliac forks.
- Obturator: along obturator axis that is anterior division of internal iliac vessels, near
obturator canal.
- Mesorectum: fatty tissue around rectum limited by the fascia recti.
- Presacral: anterior limit is the posterior fascia recti, posterior limit is the anterior part
of the sacrum.
- Around bladder: fatty tissue around bladder.
Lymph nodes were described as oval or round images, with intermediate signal
surrounded by a low signal piping. Lymph nodes were different from vascular or nervous
structures that are like tubes followed on several contiguous slices.
Statistical method:
Size of maximal long and short axis diameter of each lymph node was analysed
and their distribution was represented on graph with a histogram (empiric distribution)
superimposed on a curve (theoretical distribution)
Skewness and kurtosis were estimated and adequacy to normal distribution was
evaluated by Shapiro-Wilk normality test.
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In order to normalize data, a logarithmic transformation was performed.
In a second time, patient variation sources like age or gender, and lymph node
characteristics variation sources like laterality or anatomic territory were analysed by
mixed models variance-covariance analysis for repeated datas.
Use of mixed models is here necessary because of non-independence of collected datas
for the same person and imbalance number of analysed lymph nodes.
Only statistically significant variables on lymph nodes size were kept (p<0.05, F test).
Transformed data variance homogeneity (or homoscedasticity) was a condition for
analysis validity. Levene's test of variance comparison was applied.
Considering the heterogeneity of variances and means between territories, a superior
th
threshold was proposed in each anatomic territory, corresponding to the 95 percentile
of normal distribution. Superior thresholds were calculated first in transformed scale
(logarithmic unit) then the opposite transformation was performed to obtain millimetric
scale.
Lim log= m+ z 95% S
Lim log = superior threshold (logarithmic scale)
m = arithmetical mean in logarithmic scale
S = standard deviation
z95% = 1,645
Images for this section:
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Fig. 1: Pelvic and inguinal lymph nodes anatomic territories
Fig. 2: Balanced-FFE gradient echo axial sequence, showing natural contrast between
liquids like bladder or vessels (high signal) and other tissues (intermediate or low signal)
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Fig. 3: Mesorectal lymph node
Fig. 4: Deep inguinal lymph node maximal short and long axis diameters
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Results
A total of 1147 lymph nodes were identified: 678 inguinal, 159 external iliac, 131 internal
iliac, 69 common iliac, 92 in mesorectal territory, 9 presacral, 7 obturator and 2 arround
bladder.
Distribution of short and long axis values was represented by two different assymetrical
curves before logarithmic transformation (figure 1). A normal distribution was obtained
after logarithmic transformation (Gauss curve) (figure 2).
A minimum of 14 and a maximum of 46 lymph nodes were measured by person on
imaging of 36 volunteers, 22 women and 14 men, aged from 20 to 33 years old (mean
age 24,6).
Statistical study (Levene test, F test) of different parameters showed that age, gender
and laterality had no significant influence whereas anatomic territory had a meaningful
influence on size (p<0,05 ; F test).
Presacal, obturator and around bladder territories were insufficiently represented to be
included in the study.
Statistic analysis showed a mean size and a upper size respectively of 2,6 and 3,9 mm;
3,3 and 4,8 mm; 2,6 and 2,9mm for short axis and 3,7 and 5,3 mm; 5,8 and 9,8 mm; 6,5
and 8,3 mm for long axis diameter.
These lymph nodes were excluded of the study.
A total of 1129 lymph nodes was included, and the only effect retained was the anatomic
territory.
Superior thresholds and mean values are reported on figures 3 and 4 in logarithmic scale
and after reverse transformation in millimetric scale.
Images for this section:
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Fig. 1: Assymetrical curve before logarithmic transformation. Example for maximal short
axis diameters. On the abscissa:size of nodes (mm); on the ordinate:number of nodes
(percent)
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Fig. 2: Gauss curve after logarithmic transformation. Example for maximal short axis
diameters.On the abscissa:size of nodes (mm); on the ordinate:number of nodes
(percent)
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Fig. 3: Values for short axis diameter; g= arithmetic mean in logarithmic scale Slog=
standard deviation in logarithmic scale mm= millimeter
Fig. 4: Values for long axis diameters; g= arithmetic mean in logarithmic scale Slog=
standard deviation in logarithmic scale mm= millimeter
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Conclusion
Maximal short axis diameter is more reproductible than long axis whatever the plane
section and is a criterion for evaluation of LN involvement (RECIST: response evaluation
criteria in solid tumours 2009).
Age, gender and laterality have no influence on size.
Only anatomic territory has a significant influence on size.
We decided to round up short axis superior thresholds values (95
nearest millimeter to improve reproductibility between observers:
External iliac
5,3
6
Internal iliac
4,4
5
Common iliac
5,3
6
Mesorectal
3,9
4
th
percentile) to the
Inguinal
6,3
7
Superior thresholds (millimeter) before and after rounding
These values are shorter than those used in routine by radiologists and their application
could improve metastatic LN detection.
Steady state gradient echo sequence (balanced-FFE) with axial thin slices can be used
to detect pelvic, mesorectal and inguinal lymph nodes.
References
[1] McMahon CJ, Rofsky NM, Pedrosa I. Lymphatic metastases from pelvic tumors:
anatomic classification, characterization, and staging. Radiology, 2010 Jan;254(1):31-46.
[2] Eisenhauer EA, Therasse P, Bogaerts J, Schwartz LH, Sargent D, Ford R, et al. New
response evaluation criteria in solid tumours: revised RECIST guideline (version 1.1).
Eur J Cancer. 2009 Jan;45(2):228-47.
Page 12 of 14
[3] Vinnicombe SJ, Norman AR, Nicolson V, Husband JE. Normal pelvic lymph nodes:
evaluation with CT after bipedal lymphangiography. Radiology. 1995 Feb;194(2):349-55.
[4] Grubnic S, Vinnicombe SJ, Norman AR, Husband JE. MR evaluation of normal
retroperitoneal and pelvic lymph nodes. Clinical radiology. 2002 Mar;57(3):193-200;
discussion 1-4.
[5] Kamina P, Demondon, X, Richer, JP, Scépi, M, Faure, JP. Anatomie clinique de
l'appareil génital féminin. Encyclopédie Médico-Chirurgicale: Elsevier Masson 2003.
[6] Brown G, Richards CJ, Bourne MW, Newcombe RG, Radcliffe AG, Dallimore
NS, et al. Morphologic predictors of lymph node status in rectal cancer with use of
high-spatial-resolution MR imaging with histopathologic comparison. Radiology. 2003
May;227(2):371-7.
[7] Grey AC, Carrington BM, Hulse PA, Swindell R, Yates W. Magnetic resonance
appearance of normal inguinal nodes. Clinical radiology. 2000 Feb;55(2):124-30.
[8] Matsuoka H, Masaki T, Kobayashi T, Sato K, Sugiyama M, Atomi Y, et al.
Morphological criteria for metastatic mesorectal lymph nodes in rectal cancer. Hepatogastroenterology. 2009 Nov-Dec;56(96):1661-4.
[9] Perez RO, Pereira DD, Proscurshim I, Gama-Rodrigues J, Rawet V, Sao Juliao GP,
et al. Lymph node size in rectal cancer following neoadjuvant chemoradiation--can we
rely on radiologic nodal staging after chemoradiation? Diseases of the colon and rectum.
2009 Jul;52(7):1278-84.
[10] Oyen RH, Van Poppel HP, Ameye FE, Van de Voorde WA, Baert AL, Baert LV.
Lymph node staging of localized prostatic carcinoma with CT and CT-guided fine-needle
aspiration biopsy: prospective study of 285 patients. Radiology. 1994 Feb;190(2):315-22.
[11] Hilton S, Herr HW, Teitcher JB, Begg CB, Castellino RA. CT detection of
retroperitoneal lymph node metastases in patients with clinical stage I testicular
nonseminomatous germ cell cancer: assessment of size and distribution criteria. Ajr.
1997 Aug;169(2):521-5.
[12] Damin DC, Tolfo GC, Rosito MA, Spiro BL, Kliemann LM. Sentinel lymph node in
patients with rectal cancer invading the anal canal. Techniques in coloproctology. 2010
Jun;14(2):133-9.
[13] Lengele B, Scalliet P. Anatomical bases for the radiological delineation of lymph
node areas. Part III: Pelvis and lower limbs. Radiother Oncol. 2009 Jul;92(1):22-33.
[14] Mangan CE, Rubin SC, Rabin DS, Mikuta JJ. Lymph node nomenclature in
gynecologic oncology. Gynecologic oncology. 1986 Feb;23(2):222-6.
Page 13 of 14
[15]Morisawa N, Koyama T, Togashi K. Metastatic lymph nodes in urogenital cancers:
contribution of imaging findings. Abdominal imaging. 2006 Sep-Oct;31(5):620-9.
[16] Rouvière H. Anatomie des lymphatiques de l'homme: Masson 1932.
[17] Poirier P, Cunéo,B, Delamere, G, ed. The lymphatics: Westminster: Archibald
Constable & co. Ltd 1903.
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