Differentiation of malignant and benign lesions of the osseous spinal axis with three dimensional computed tomography image appearences: dirty interface sign

doi:10.4236/ojcd.2011.13005

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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.

Email: [email protected]

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

D. Yildirim et al. / Open Journal of Clinical Diagnostics 1 (2011) 22-25

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

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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