3D Assessment of Lymph Nodes vs. RECIST 1.1.
ABSTRACT In today's clinical practice, the size of lymph nodes is assessed by measuring the long and the short axis in the axial plane. This study compares this approach with three-dimensional (3D) assessment.
For a representative set of 49 lymph nodes, the axes in the axial plane have been measured and a 3D model has been created manually. Based on the 3D model, the real axial long and short axis as well as the three 3D axes and the volume have been computed and compared to the measured axial axes.
The inter-observer variability is around 10% for all measured lengths and almost 16% for the computed volume. The average relative error of the measured long (short) axial axis is 9.73% (24.57%) to the computed axial axis and 25.05% (19.97%) to the computed 3D axis, respectively. The product of the axial long axis and the square of the axial short axis provides best correlation to the volume.
This study confirms Response Evaluation Criteria In Solid Tumours 1.1 that measuring the short axis is more robust than measuring the long axis because of less impact of the node's spatial orientation. Nonetheless it is shown that considering both axes is a better prognostic factor for the volume than measuring the short axis only.
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ABSTRACT: To compare the diagnostic performance in evaluating the response of neoadjuvant chemotherapy (NAC), between the response evaluation criteria in solid tumor (RECIST) 1.0 and RECIST 1.1, on magnetic resonance imaging (MRI) for advance breast cancer patients. Breast cancer patients, who underwent NAC between 2005 and 2010, were included. Both prechemotherapy and post-chemotherapy MRIs were performed within 1-4 weeks before and after NAC. Only the patients with subsequent surgery were included. The response to NAC was assessed by using RECIST 1.0 and RECIST 1.1. Patients with a complete or partial response on MRI were considered as responders, and those with stable or progressive disease were considered as non-responders. Tumor necrosis > 50% on pathology was defined as responders and necrosis < 50% was defined as non-responders. The diagnostic accuracy of both RECIST 1.0 and RECIST 1.1 was analyzed and compared by receiver operating characteristic curve analysis. Seventy-nine females (mean age 51.0 ± 9.3 years) were included. Pathology showed 45 responders and 34 non-responders. There were 49 responders and 30 non-responders on RECIST 1.0, and in 55 patients, RECIST 1.0 results agreed with pathologic results (69.6%). RECIST 1.1 showed 52 responders and 27 non-responders. In 60 patients, RECIST 1.1 results were in accordance with pathology results (75.9%). The area under the ROC curve was 0.809 for RECIST 1.0 and 0.853 for RECIST 1.1. RECIST 1.1 showed better diagnostic performance than RECIST 1.0, although there was no statistically significant difference between the two.Korean journal of radiology: official journal of the Korean Radiological Society 01/2013; 14(1):13-20. · 1.32 Impact Factor
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ABSTRACT: Therapy response evaluation in oncological patient care requires reproducible and accurate image evaluation. Today, common standard in measurement of tumour growth or shrinkage is one-dimensional RECIST 1.1. A proposed alternative method for therapy monitoring is computer aided volumetric analysis. In lung metastases volumetry proved high reliability and accuracy in experimental studies. High reliability and accuracy of volumetry in lung metastases has been proven. However, other metastatic lesions such as enlarged lymph nodes are far more challenging. The aim of this study was to investigate the reproducibility of semi-automated volumetric analysis of lymph node metastases as a function of both slice thickness and reconstruction kernel. In addition, manual long axis diameters (LAD) as well as short axis diameters (SAD) were compared to automated RECIST measurements. Multislice-CT of the chest, abdomen and pelvis of 15 patients with lymph node metastases of malignant melanoma were included. Raw data were reconstructed using different slice thicknesses (1-5mm) and varying reconstruction kernels (B20f, B40f, B60f). Volume and RECIST measurements were performed for 85 lymph nodes between 10 and 60mm using Oncology Prototype Software (Fraunhofer MEVIS, Siemens, Germany) and were compared to a defined reference volume and diameter by calculating absolute percentage errors (APE). Variability of the lymph node sizes was computed as relative measurement differences, precision of measurements was computed as relative measurement deviation. Mean absolute percentage error (APE) for volumetric analysis varied between 3.95% and 13.8% and increased significantly with slice thickness. Differences between reconstruction kernels were not significant, however, a trend towards middle soft tissue kernel could be observed.. Between automated and manual short axis diameter (SAD, RECIST 1.1) and long axis diameter (LAD, RECIST 1.0) no significant differences were found. The most unsatisfactory segmentation results occurred in higher slice thickness (3 and 5mm) and sharp tissue kernel. Volumetric analysis of lymph nodes works satisfying in a clinical setting. Thin slice reconstructions (≤3mm) and a middle soft tissue reconstruction kernel are recommended. LAD and SAD did not show significant differences regarding APE. Automated RECIST measurement showed lower APE than manual measurement in trend.European journal of radiology 03/2012; 81(11):3124-30. · 2.65 Impact Factor
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ABSTRACT: BACKGROUND: The purpose of this study was to compare the accuracy of volumetric (3D) measurements with that of unidimensional (1D) measurements by response evaluation criteria in solid tumors 1.1 (RECIST 1.1) in patients with breast cancer before and after neoadjuvant chemotherapy. METHODS: The study included 48 patients with breast cancer who underwent neoadjuvant chemotherapy. Dynamic contrast-enhanced magnetic resonance imaging was performed before the first cycle of chemotherapy and after the completion of the planned chemotherapy. The longest diameter and volume of each target lesion were measured using a TeraRecon Aquarius workstation (San Mateo, CA). Response was assessed both by using the RECIST 1.1 and volumetric criteria. Histologic response was assessed using the Sataloff criteria. The agreements between the two measures and the histologic response were analyzed statistically. RESULTS: In monitoring the response to neoadjuvant chemotherapy, the 1D and 3D measurements showed "good agreement" (κ = 0.610) for the treatment response categories and "moderate agreement" (κ = 0.565) for the responder/non-responder categories. Disagreement was observed in 9 out of 48 comparisons (18.75 %). The percent agreement of the 1D measurement of residual lesions (79.17 %) with the pathology was higher than that by volumetric measurement (70.83 %), but there was no statistically significant difference (p = 0.35). Both the 1D (rho = 0.67, p < 0.0001) and 3D measurements (rho = 0.52, p < 0.0001) showed a moderate degree of linear correlation with the pathologic diameter of residual lesions. CONCLUSION: There was generally good agreement between the 1D and 3D measurements and moderate predictive value using either approach for predicting pathological response.Breast Cancer 07/2012; · 1.33 Impact Factor
3D Assessment of Lymph Nodes vs.
Sebastian Steger, Dipl.-Ing., Fabio Franco, MD, Nicola Sverzellati, MD, Gianfranco Chiari, MD,
Ramon Colomer, MD
Rationaleand Objectives: Intoday’s clinicalpractice,the size oflymphnodes isassessedby measuringthelong andtheshortaxis inthe
axial plane. This study compares this approach with three-dimensional (3D) assessment.
Materials and Methods: For a representative set of 49 lymph nodes, the axes in the axial plane have been measured and a 3D model has
been created manually. Based on the 3D model, the real axial long and short axis as well as the three 3D axes and the volume have been
computed and compared to the measured axial axes.
Results: The inter-observer variability is around 10% for all measured lengths and almost 16% for the computed volume. The average
relative error of the measured long (short) axial axis is 9.73% (24.57%) to the computed axial axis and 25.05% (19.97%) to the computed
3D axis, respectively. The product of the axial long axis and the square of the axial short axis provides best correlation to the volume.
Conclusion: This study confirms Response Evaluation Criteria In Solid Tumours 1.1 that measuring the short axis is more robust than
measuring the long axis because of less impact of the node’s spatial orientation. Nonetheless it is shown that considering both axes is
a better prognostic factor for the volume than measuring the short axis only.
Key Words: Lymph node staging; RECIST; volumetry.
Malignant lymph nodes are common target and nontarget
lesions, whose sizes have to be assessed for staging and disease
For example in oral cancer, accurate staging is the most
important factor that guides therapeutic decision making.
Staging methods include radiological assessment that usually
entails imaging of the neck with computed tomography
(CT) or magnetic resonance imaging, or both. Lymphatic
metastases will develop in 20%–30% of patients with early
oral cancers and imply decreased survival (1).
The size can be measured using unidimensional, bidimen-
sional, and volumetric techniques (2). For liver malignomas
volumetric analysis is superior (3). However, in current clinical
practice the size is assessed inCT scans by measuring the axis in
the axial plane according to the Response Evaluation Criteria
In Solid Tumours (RECIST) criteria (4).
he presence and location of lymph node metastases (N
descriptor) is an important component of radiologic
staging in patients with cancer of different types.
Besides general limitations of planar assessment of three-
dimensional (3D) structures, the limitation to the axial plane
for assessing arbitrarily spatial oriented structures reduces
reliability. This issue was addressed by the revised RECIST
criteria (5,6), by considering the short axis only.
variability in the assessment of the lymph nodes’diameters and
tested which diameters in the axial plane better correlate with
MATERIALS AND METHODS
An experienced radiologist (I.R. with 15 years of experience)
identified a representative set of 49 lymph nodes in 13 head
and neck CT scans of oral cancer patients (5 male, 8 female,
age range 36–93 years). The setcontains benign aswell aspath-
and 24.3 mm. To avoid any kind of selection bias, the study
subjects were consecutive.
15, 3,3,3,and6years inoncologicimaging,respectively)from
two different hospitals evaluated those lymph nodes by
in which those measurements appeared to be maximal in the
whole node. Then the boundaries of each lymph node in
using an electronic free-hand region of interest, enabling the
creation of an accurate 3D model of the node. The time for
delineating was recorded for each node.
Acad Radiol 2011; -:1–4
Fraunhoferstrasse 5, 64283 Darmstadt, Germany (S.S.); Department of
Clinical Sciences, Section of Radiology, Parma Hospital, Parma, Italy (F.F.,
N.S., G.C.); Centro Oncol? ogico MD Anderson International, Madrid, Spain
(R.C.). Received August 19, 2010; accepted November 10, 2010. This work
is partially funded within the NeoMark project (FP7-ICT-2007-2-224483) by
the European Commission. Address correspondence to: S.S. e-mail:
From this model the ‘‘real’’ axial diameters were automati-
cally extracted by the following algorithm. In each slice, the
minimal area bounding rectangle is computed by applying
the rotating calipers algorithm (7) on the convex hull of all
pixels that are said to be part of the lymph node in the current
slice. The real long axial axis of the node is then said to be the
length of that rectangle with the largest length of all slices.
The real short axial axis is defined as the orthogonal axis to
the long axial axis in the slice where this axis is maximized.
Furthermore a similar computation is carried out to auto-
matically extract the real 3D axes of the lymph nodes. An
approximation of the minimum volume bounding box is
extracted by eigenvector analysis of the points of the lymph
node model’s convex hull. Please note that this box may have
an arbitrary spatial orientation in the 3D space (Fig 1).
axes as well as to the real 3D axes in terms of relative difference
Moreover the PMCC between the extracted volume and the
following measurements was computed:
(a) Third power of the real axial short axis
(b) Third power of the real 3D short axis
(c) Product of the real long axial axis and the second power of
the real short axial axis
(d) Product of all three 3D axes
Note that all of these expressions are volumes, justifying
a linear correlation to the volume of the node (prerequisite
for computing the PMCC).
The average duration for the manual 3D model creation was
roughly 4.5 minutes per lymph node. For large lymph nodes
this duration went up to 25 minutes. The average inter-
observer variability of all lymph nodes is given in Table 1
for all measurements. In the average case the measured long
axial axis differed by 9.73% from the model’s automatically
extracted long axial axis and even 24.57% for the short axial
axis. The reason for the short axis’ huge difference is mostly
due to the fact that long and short axis are always measured
in the same axial slice, whereas the automated extraction
to the node’s computed long axial axis is maximal.
Comparing the measured axial axes to the automatically
computed 3D axes of the model, it turns out that the relative
difference is 25.05% for the long axis and 19.97% for the short
axis, respectively. The larger average difference confirms that
measuring the short axis is less sensitive to the node’s spatial
for revising the RECIST criteria.
For the comparability of measurements, the relative differ-
ence between the measured and the actual size is not as impor-
tant as the correlation. Imagine a measuring technique that
results in a similar overestimation of the real size for all lymph
nodes. Although the relative difference to the actual size may
be quite large, this measuring technique is still a valuable
predictor, because the error is predictable, resulting in a high
correlation between the measured and the actual size.
Figure 2 shows the measured axial axis versus the real axis
extracted from the 3D model for the long and the short axis.
Measuring the long axis results in an underestimation of the
realsizeofthe nodewhereasthe shortaxissometimesisoveres-
timated. This observation is a consequence of the node’s spatial
orientation. Only in the case, when the real long axis is in the
axial plane, the radiologist is able to assess the correct length.
in the axial plane which in general is smaller.
The linear correlation coefficients are 0.8885 for the long
axis and 0.9325 for the short axis, respectively. This indicates
Figure 1. Axial two-dimensional vs. three-dimensional assessment
of the dimensions of a lymph node.
Figure 2. Measured axial axis vs. automatically extracted three-
STEGER ET ALAcademic Radiology, Vol -, No -, - 2011
axial long axis is not predictably and therefore once more
confirms that the short axis is less sensitive to the node’s spatial
orientation than the long axis.
Because of the different shapes of lymph nodes, the axes by
themselves do not perfectly correlate with the node’s volume.
Figure 3 points this out by comparing the volume of boxes
whose size corresponds to various combinations of measured
or computed axes with the actual volume of the node.
The correlation coefficient is 0.9379 for the third power of
the axial short axis, 0.9979 for the third power of the 3D short
short axial axis, and 0.9990 for the product of all three 3D axes.
nodes in the axial plane. But if a 3D model was available the
volume could be assessed directly and the axes wouldn’t be
needed to estimate the volume. However, if a 3D model is
not available—as it is not in today’s clinical practice—the
node can only be assessed in the axial plane. The presented
linear correlation coefficients indicate that the product of the
long axial axis and the squared short axial axis is a better
predictor the just the short axial axis. This is contrary to
RECIST 1.1, which requires assessment of the shortaxis only.
Although this study has confirmed that measuring the short
axes is less sensitive to the spatial orientation of the node
than measuring the long axis (as suggested by RECIST 1.1),
it indicates that measuring the short axis in the axial plane
by itself as a prognostic factor for the size of a lymph node is
worse than also incorporating the long axis. However, a really
goodestimationof the sizecan onlybe achieved bymeasuring
the axes in the 3D space or measuring the volume.
tages, manually delineating the lymph node in each CT slice is
not feasible in clinical routine because of the long time it takes
for the creation of the 3D model. The application of accurate
and robust automated segmentation algorithms, as reported
elsewhere (8), could compensate for that, thus significantly
improving the assessment of lymph node size while decreasing
evaluation time, thereby increasing the significance of disease
progression monitoring in cancer.
Future work includes the automated 3D model creation using
and applying it to the datasets used in this study. Moreover, the
significance of this study needs to be increased byapplying it to
a larger dataset.
The authors like to thank Inmaculada Rodriguez Jimenez and
Francisco Javier Garcia Prado from the Radio-Diagnosis
Department, Centro Oncol? ogico MDAnderson International
Spain for selecting the lymph nodes and assessing their proper-
the Department of Clinical Sciences, Section of Radiology,
Parma Hospital for assessing the lymph nodes’ properties.
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and Treatment of Cancer, National Cancer Institute of the United States,
National Cancer Institute of Canada. J Natl Cancer Inst 2000; 92:205–216.
TABLE 1. Inter-observer Variability
Measured long axial axis
Measured short axial axis
Computed long axial axis
Computed short axial axis
Computed long three-
Computed short three-
0.81 mm 8.83
Figure 3. Axes vs. volume.
Academic Radiology, Vol -, No -, - 20113D ASSESSMENT OF LYMPH NODES VS. RECIST 1.1
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