Open Journal of Clinical Diagnostics, 2011, 1, 22-25
doi:10.4236/ojcd.2011.13005 Published Online December 2011 (http://www.SciRP.org/journal/ojcd/
OJCD
).
Published Online December 2011 in SciRes. http://www.scirp.org/journal/OJCD
Differentiation of malignant and benign lesions of the osseous
spinal axis with three dimensional computed tomography
image appearences: dirty interface sign
Duzgun Y ildirim1, Cuneyt Tamam2, Ercan Karaaslan3, Abdullah Yakupoglu4
1İskenderun Military Hospital, Department of Radiology, Hatay, Turkey;
2Kasimpasa Military Hospital, Department of Orthopeadics, Istanbul, Turkey;
3Acibadem University, Department of Radiology, Istanbul, Turkey;
4Acibadem Maslak Hospital, Department of Radiology, Istanbul, Turkey.
Received 20 September 2011; revised 22 November 2011; accepted 30 November 2011.
ABSTRACT
Purpose: We aimed to make a fast and accurate dis-
tinction of malignant and benign lesion s in cases with
predominantly solitary or multifocal involvement
using latest technology software and hardware sys-
tems in computed tomography. Materials and Meth-
ods: 53 cases were included in the study. Primary (n
= 42, 31 benign, 11 malignant) or metastatic (n = 11)
tumors were detected at various locati ons in the bo ne
structure of the cervical to coccygeal vertebrae in all
cases. 3D CT images taken using the same system and
biopsy or post-operative histopathology findings were
available for all cases. Thin section images taken ret-
rospectively from the archives were converted to 3D
images using the same program and parameters,
which were then recorded in the same window set-
tings by two radiologists. Only 3D images were then
analyzed to investigate the presence or absence of the
dirty interface sign. Results: Dirty interface sign was
present in 17 malignant lesions and absent in the re-
maining 5 lesions. As for benign lesions, the sign was
present in only two lesions and the remaining 29 were
negative for the sign. There was a high level of con-
sistency between the two radiologists. In conclusion,
malignant and benign lesions affecting the bone spi-
nal axis were distinguished based on the presence or
absence of the dirty interface sign with 77.3% sensi-
tivity, 93.5% specificity and 86.8% accuracy. Conclu-
sion: When evaluated with standard bone window
views, 3D views can be used successfully for the dis-
tinction of malignant and benign bone tumors. At
least, 3D views generated using low dose regimes in
highly developed systems can be used with similar
purpose to that of diffusion weighted MRI sequences
that give roughly outlined but fast and accurate in-
formation about th e lesion .
Keywords: Three-Dimensional CT; Differentiation; Ma-
lignant-Benign; Bone Tumor
1. INTRODUCTION
With using of latest technology software and hardware
systems in CT, perfect and high quality three dimen-
sional images can be obtained even at low doses. 3D
analyses can be done in the form of both 3D maximum
intensity projection (MIP) and volume weighted colored
surface imaging. The views can be assessed step by step
using the fly around method by turning them around
themselves in the right-left, up-down direction or ran-
domly. Objects in the large gravity fields can be evalu-
ated with only one examination using these 3D views. In
this way, it will be possible to be oriented to the anatomy
and the pathology at least at the level of bone skeleton.
In this study, we assessed the benefits of this develop-
ment in the CT technology for the evaluation of tumor
lesions. By using surface weighted volume rendered 3D
views, we investigated the efficiency of using only 3D
viewing for the distinction of malignant and benign le-
sions.
2. MATERIALS AND METHODS
53 cases were included in the study. Primary (n = 42, 31
benign, 11 malignant) or metastatic (n = 11) tumors
were detected at various locations in the bone structure
of the cervical to coccygeal vertebrae in all cases. 3D CT
images taken using the same system and biopsy or
post-operative histopathology findings were available
for all cases. Reconstruction images of the thin section
views (Siemens 64 × 2 slice, dual source CT) taken ret-
rospectively from the archives were generated using the

D. Yildirim et al. / Open Journal of Clinical Diagnostics 1 (2011) 22-25 23
same parameters (B30-medium soft tissue, ≤2 mm sec-
tion thickness). These reconstruction images were con-
verted to 3D images in the workstation (Leonardo Run-
ning Space) using one of the automated bone algorithms
(same window for all cases). These 3D images were then
recorded in the same window settings by two radiolo-
gists. Whole evaluation time for these images were no
more longer than 5 minutes in all cases (mean 4.2 mins).
Only 3D images were then analyzed to investigate the
presence or absence of the dirty interface sign and the
findings were indicated in separate tables. If the surface
color is homogenous and bright, the sign accepted as
negative. Otherwise, in the existence of a heterogenous,
cloudy, dirty surface appearences of the vertebral lesion,
dirty interface sign was accepted as positive (and sup-
portive for malignancy).
3. RESULTS
Dirty interface sign was present in 17 malignant lesions
and absent in the remaining 5 lesions. As for benign le-
sions, the sign was present in only two lesions and the
remaining 29 were negative for the sign (Table 1). In
cases for which the view of the entire spinal column was
available, highly objective distinction of malignant and
benign lesions was possible for malignant focuses (Fig-
ure 1) and malignant or benign pathologies affecting the
vertebral corpus or the posterior elements (Figure 2).
There was a significant level of consistency between
the two radiologists (Ta ble 2) (P < 0.05). Malignant and
benign lesions affecting the bone spinal axis were dis-
tinguished based only on the presence or absence of the
dirty interface sign with 77.3% sensitivity, 93.5% speci-
ficity and 86.8% accuracy (Table 3). Furthermore, views
Figure 1. (a) Non-hodgkin lymphoma (large
cell lymphoma), areas with heterogenous
bold colored changes represent the involve-
ment of the distal dorsal vertebrae and re-
lated ribs (encircled area) (b) Focal hetero-
geneous lower density similar focus of the
left lateral sacral mass (encircled area) was
also associated with malignity (metastasis of
the left breast lobular carcinoma).
Table 1. The presence (+) or absence (–) of the dirty interface sign in all lesion groups and malignant-benign group.
Benign Sign (–) Benign Sign (+) Malignant Sign (–) Malignant Sign (+)
Aneurysmal bone cyst (n = 9) Giant cell tumor (GCT) Metastasis (n = 2) Ewing sarcoma
Histiocytosis (n = 2) Osteomyelitis Lymphoma (n = 2) Metastasis (n = 10)
Dyscitis Chondrosarcoma Lymphoma
Neurogenic tumor Osteosarcoma
Osseous anomaly (n = 2) Chordoma
Neurofibroma + hemangioma (n = 2) Osteosarcoma
Paget’s disease Rhabdomyosarcoma+
Osteoblastoma (n = 2) Multiple myeloma +
Porotic vertebral collapse (n = 4)
Osteomyelitis
Spondylodiscitis
Fibrous dysplaisa (n = 2)
Paget’s disease
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D. Yildirim et al. / Open Journal of Clinical Diagnostics 1 (2011) 22-25 24
Table 2. Consistency between the two readers for the distinc-
tion of malignant and benign lesions shown in numbers.
Lesions and
the sign
Readers
Benign – Benign + Malign – Malign +
Reader-I 29 2 5 17
Reader-II 27 4 4 18
Table 3. Analysis of the data into a 2 × 2 table separately.
Histopathology
+ –
+ 17 2
Malignity – 5 29
Figure 2. Miscalleneous lesion of the
spine. Lesions are pointed by circles. (a)
Porotic collapse fractures and (b) In
Paget’s disease cases, vertebra corpus
densities had homogenous surface
properties. In these pathologies 3D sur-
face brightness was homogenous like in
another case with porotic sompression
fracture in (c) However, (d) soft tissue
mass (multiple myeloma) destructing
posterior elements of the dorsal verte-
bra was dense heterogeneous and had a
remarkable heterogenous surface color
change which represents the malignant
interface sign.
leading to false positive or negative interpretation were
displayed also exampled in a figure (Figure 3).
4. DISCUSSION
Approximately 2000 malignant bone tumors are diag-
nosed every year in the USA [1]. And greater than 5% of
them is related only to axial skeleton As expected, the
number of benign tumor cases will be much higher than
this. For the management of malignant bone tumors,
Figure 3. A case with renal cell carcinoma: (a) MRI, sagittal
T1A view of a tumor lesion affecting the multiple compart-
ments thorough the anterio-posterior segments of the lower
dorsal axis. (b) as a false negative case; 3D reconstructing
image of the same lesion (arrow) is faint and cannot be neatly
distinguished (circled area) (c) Heterogeneous irregular 3D
views of the affected lower dorsal segments in another osteo-
myelitis case, leading to a false positive finding by mimicking
the malignancy (squared area).
Figure 4. Involvement of the dorsolumbar
spinal colon in a patient with non-Hodgkin
lymphoma. a) Posterior aspect of the colon
shows faint surface regularity and homoge-
nous colour pattern. b) But in anterior projec-
tion, the same case’s 3D-colored, volume
rendered CT image reveals the lytic, involved
sites as confirmatory for malignant changes.
moderate treatment regimens replaced radical excisions,
such as radical amputation [2]. Thus, early diagnosis
became important in terms of life quality. A large number
of studies are available on the advantages and superiority
of CT and MRI for the local staging of the muscu-
loskeletal neoplasms. Despite the high soft tissue resolu-
tion, MRI is insensitive to calcifications, susceptible to
artifacts especially in primary bone neoplasia., and have
been replaced by CT The general opinion is that CT is
superior for demonstrating the destruction of bone cortex
and displaying the osseous or calcific component. Also,
CT is also superior for displaying lung metastasis. The
presence of thin cross sections contributed in the in-
crease in resolution in both 2D and 3D.The develop-
ments in multidedector CT and multiplanar reformatte
(MPR) technology have equalized CT and MRI. With
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D. Yildirim et al. / Open Journal of Clinical Diagnostics 1 (2011) 22-25 25
sensitivity weighted or diffusion weighted like specific
sequences, MRI can differentiate calcification or benign
versus malignant compression fractures. MRI can com-
pensate its inadequacy against CT [4-6]. Without com-
paring the two methods, we evaluated 3D-CT views of
the osseous spinal column and attempted to detect le-
sions that affect the bony cortico-medullary area and
cause surface anomaly. By this method, we have tried to
evaluate the entire area included in the field of view,
similar to diffusion weighted MRI. Studies have shown
that 39% of metastatic bone lesions are localized in axial
skeleton and causes compression in time. The majority
of spinal malign tumors are metastatic tumors, lym-
phoma and myeloma. Because the clinical presentation
of vertebral tumors, whether primary or secondary are
non specific, differential diagnosis is crucial. Recent
studies have used different criteria (convex posterior
border of the vertebral body, abnormal signal intensity
of the pedicle or posterior element, an epidural mass, a
focal paraspinal mass, and other spinal metastases, i.e.)
with MRI and diffusion weighted MR imaging to dis-
tinguish porotic compression fractures from pathologic
vertebral fractures [7-10]. Generally overall diagnostic
accuracy in these studies was as following: sensitivity,
specificity, and accuracy were 85% - 100%, 79% - 100%,
and 86% - 95%, respectively [7-10]. Our aim was to
show that it is possible to make a fast and accurate dis-
tinction of malignant and benign lesions in cases with
predominantly solitary or multifocal involvement. And
our results were acceptable when compared the men-
tioned large scaled MRI studies.
5. CONCLUSIONS
When evaluated with standard bone window views, 3D
views can be used successfully for the distinction of ma-
lignant and benign bone tumors. At least, 3D views gen-
erated using low dose regimes in the highly developed
systems can be used with similar purpose to that of
whole body diffusion weighted MRI sequences that give
roughly outlined but fast and accurate (86.8%) informa-
tion about the lesion’s hystology.
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