|Year : 2021 | Volume
| Issue : 1 | Page : 259-263
Role of magnetic resonance imaging in diagnosis of pediatric bone tumors
Zynab A Ali, Rehab M Habib, Shrief R Abd Elkhalek
Department of Radiology, Faculty of Medicine, Menoufia University, Menoufia, Egypt
|Date of Submission||15-Jul-2019|
|Date of Decision||04-Sep-2019|
|Date of Acceptance||06-Sep-2019|
|Date of Web Publication||27-Mar-2021|
Shrief R Abd Elkhalek
Source of Support: None, Conflict of Interest: None
To evaluate the diagnostic effect of MRI in pediatric patients with suspected bone tumors and other bone pathologies.
Bony lesions in pediatric age group is a frequent cause of pain and swelling. MRI is used to evaluate such patients, and information delivered by MRI is used to diagnose these lesions, whether benign or malignant. In addition, information delivered by MRI is used to guide biopsy procedure.
Patients and methods
This was a prospective study that included 50 patients. All were referred to the MRI unit in the diagnostic Radiology Department at Menoufia University Hospital from Menoufia University Hospital clinics and private clinics from June 2015 to November 2018.
Our study revealed that MRI plays a sensitive diagnostic role in most cases not solved by plain radiography, for example, characterization of bony lesions like fatty content, cysts with and without fluid–fluid levels, and cartilaginous matrix, and also in aggressive bone lesions, MRI is used for locoregional staging and noninvasive evaluation of response to neoadjuvant treatment.
MRI is a sensitive and specific tool in primary detection and staging of pediatric bone tumors and tumor-like conditions. MRI helps guide biopsy from the soft tissue components and increases the chance of obtaining a definitive diagnostic result.
Keywords: biopsy, bone tumors, diagnosis, magnetic resonance imaging, pediatrics
|How to cite this article:|
Ali ZA, Habib RM, Abd Elkhalek SR. Role of magnetic resonance imaging in diagnosis of pediatric bone tumors. Menoufia Med J 2021;34:259-63
|How to cite this URL:|
Ali ZA, Habib RM, Abd Elkhalek SR. Role of magnetic resonance imaging in diagnosis of pediatric bone tumors. Menoufia Med J [serial online] 2021 [cited 2021 May 8];34:259-63. Available from: http://www.mmj.eg.net/text.asp?2021/34/1/259/312017
| Introduction|| |
The primary assessment of pediatric bone lesions is performed using radiographic imaging and is categorized according to criteria of aggressiveness. MRI plays a complementary diagnostic role in select cases, for example, when there are characteristics of fatty content, cysts with and without fluid–fluid levels, cartilaginous matrix, and low signal intensity on T2 sequences. In bone lesions presenting an aggressive pattern, MRI is the chosen method for locoregional staging and noninvasive evaluation of response to neoadjuvant treatment .
MRI can extend the diagnostic evaluation by demonstrating several tissue components. Even when a specific diagnosis cannot be made, the differential diagnosis can be narrowed. MRI is superior to other imaging modalities in detecting bone marrow lesions and tumoral tissue (faint lytic/sclerotic bone lesions can be difficult to visualize using only radiographs). Contrast-enhanced MRI can reveal the most vascularized parts of the tumor, and MRI guidance makes it possible to avoid biopsy from necrotic areas. MRI is very helpful in local staging and surgical planning by assessing the degree of intramedullary extension and invasion of the adjacent physeal plates, joints, muscle compartments, and neurovascular bundles. It can be used in assessing response to neoadjuvant therapy and further restaging. The posttherapeutic follow-up should also be done using MRI .
The neoplastic processes can be categorized as benign and malignant, and the latter may be subcategorized as primary and secondary. It is estimated that primary benign tumors are ten times more common than primary malignant tumors. Despite encompassing more than 20 different histological varieties, most primary malignant tumors are osteosarcomas (52%) and Ewing's sarcomas (34%) .
The secondary bone involvement by metastasis or primary bone tumors, such as chondrosarcoma, is common among adults, whereas it is an exception among children. Inversely, lesions such as eosinophilic granuloma, simple bone cysts, and aneurysmal bone cysts (ABCs) are typical in children .
The aim of this study was to determine the role of MRI in diagnosis of pediatric bone tumors and tumor-like conditions.
| Patients and methods|| |
We conducted a prospective study that included 50 pediatric patients. All participants were referred to the Diagnostic Radiology Department MRI unit at Menoufia University Hospital from June 2015 to November 2018. This study was approved by the Ethics Committee at Menoufia University, and all patients' parents signed a written informed consent.
Pediatric patients experiencing bony pain and swelling during this given period were examined clinically. Those who had findings with suspected underlying bone pathology on clinical examination underwent plain radiography and MRI examination to resolve the diagnosis.
The following were the exclusion criteria:
- Patients unable to cooperate for MRI (some pediatric patients need sedatives)
- Contraindications to MRI
- Aneurysmal clips
- Metal implants in the field of view.
All the patients were subjected to the following:
- Detailed history analysis: age and sex of the patients, any history of the trauma, the duration since symptoms begin, any intervention history, and history of medical disorders
- History of previous radiological investigations such as radiography, computed tomography, or ultrasound was reviewed if present
- Full clinical examination and evaluation of the vital signs. We also searched for signs of suspect inflammation like redness, hotness, or any swelling and examined the site of drainage lymph nodes
- MRI examination: all patients underwent MRI examination by superconductive MRI MR System Toshiba Vantage 1.5 tesla machine (Toshiba, Minato City, Japan). The patients were asked to remove all metallic objects. All patients on any metallic (nontitanium) body implants such as cardiac pacemakers, brain aneurysm clips, cochlear implants, and vascular stents were considered as an absolute contraindication to the performance of the procedure. The procedure was explained to the patient. Patients were instructed to keep quite during the scan and informed about its duration.
In this technique, the patients were positioned supine and head-first in the magnet bore. The MR protocol consisted exclusively of the following sequences: first, coronal T1 spin echo-weighted images were obtained with the following parameters: TR/TE, 490/11; number of signals acquired (averages), six; matrix, 192 × 256; FOV, 320 × 320 mm; and section thickness, 4 mm.
Second, coronal T2-weighted images were obtained, with short time inversion recovery (STIR) sequences. STIR images were obtained with the following parameters: 7020/87; inversion time, 150 MS; echo-train length, 15; averages, 4; matrix, 192 × 256; FOV, 320 × 320 mm; and section thickness, 4 mm.
Third, axial T1 spin echo-weighted images were obtained with the following parameters: TR/TE, 430/12; number of signals acquired (averages), six; matrix, 192 × 256; FOV, 160 × 160 mm; and section thickness, 4 mm. Fourth, axial T2-weighted images were obtained with the following parameters: TR/TE, 2000/95; number of signals acquired (averages), six; matrix, 192 × 256; FOV, 160 × 160 mm; and section thickness, 4 mm. Lastly, T2-weighted image fat saturated was done.
Contrast-enhanced dynamic sequences were preceded by a routine spin echo imaging protocol. For dynamic imaging, coronal plane was chosen on the basis of the T1-weighted spin-echo images in all patients.
The section thickness was 1.0 mm in all instances. This plane always exhibited a representative intramedullary and, if present, extramedullary tumor component.
The scans were meticulously assessed for detecting any abnormal intramedullary signals, associated soft tissue components, other surrounding lesions, and detection of any abnormal enhancement.
Analysis of data was done by DELL computer using Statistical Packages for the Social Sciences (SPSS), version 22 (SPSS Inc., Chicago, Illinois, USA) as follows: quantitative data were expressed to measure the mean, central tendency and diversion around the mean, and SD, and qualitative data were expressed in number and percentage.
| Results|| |
Our study was conducted on 50 patients with suspected bony lesions. The age of the patients ranged from 8 to 16 years, with mean age of 12 years.
On close analysis of the data obtained in the study, a collection of statistical data was observed that had a unique role in giving us an idea about the role of MRI in assessment of bony lesions at the pediatric age group.
Our study revealed the mean age of the studied group was 12 years. Overall, 62% of the studied group was males and 38% was females.
Most of the lesions are seen involving the long bones (64%), and 32% affected the axial skeleton [Table 1].
Our study revealed 36% affecting the soft tissue. Most of the lesions are seen involving the metaphysis (36%), metadiaphyseal (20%), diaphyseal (14%), and flat bones (26%). Most of the lesions are single 90% and 10% are multiple. Most of the lesions are lytic 64%, 22% are sclerotic, and 14% are mixed. Overall, 36% of the lesions were associated with soft tissue components, for example, an 8-year-old male patient with pain around the knee and swelling showed the following features: (a) plain radiography shows sclerotic bony lesion at the metadiaphysis of the distal femur with surrounding periosteal reaction and (b–d) MRI selected images (coronal T1, STIR, and axial T1 with contrast) confirm the presence of the lesion extending beyond the margin seen in radiography with surrounding periosteal reaction and enhancing surrounding soft tissue, pathologically proven osteosarcoma [Figure 1].
|Figure 1: An 8-year-old male patient with osteosarcoma. (a) x ray (b) MRI coronal T1 shows predominantly low signal intensity lesion (c) MRI (d) MRI|
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About 74% of the lesions are associated with periosteal reaction, and 26% are not associated with periosteal reaction. Overall, 20% of the lesions were biopsied under ultrasound guidance, 16% under computed tomography guidance, and 4% by excision. A 10-year-old male patient with right iliac region pain swelling and limping had the following indications: (a) radiography showed large well-defined bubbly lytic lesion affecting the right iliac bone, (b) MRI coronal T1 shows predominantly low signal intensity lesion, (c) pathologically proven desmoplastic fibroma, and (d) radiography postoperative management [Figure 2].
|Figure 2: A 10-year-old male patient with desmoplastic fibroma. (a) x ray (b) MRI (c) pathology report (d) x ray|
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Most of the lesions are benign in nature (90%), and only 10% are malignant [Figure 3] and [Table 2].
| Discussion|| |
MRI is very helpful in local staging and surgical planning by assessing the degree of intramedullary extension and invasion of the adjacent joints, muscle compartments, and neurovascular bundles. It can be used in assessing response to neoadjuvant therapy and further restaging. The posttherapeutic follow-up should also be done using MRI . MRI has a relatively high resolution in soft tissues, helping in accurate estimation of tumor invasion. This helps in the diagnosis of distant skip lesions and epiphyseal invasion . MRI is superior for evaluating the extent of intramedullary and soft tissue masses. MRI is also markedly more efficient at detecting skip lesions ,. Functional MRI techniques for the evaluation of bone tumors include the following: (a) quantitative dynamic contrast-enhancedMRI can be used to estimate the extent of necrosis in bone tumors. The percentage of tumor necrosis is the most important outcome measure for evaluating whether or not neoadjuvant therapy is clinically effective . In the current study, the age of the patients ranged from 8 to 16 years, with mean age of 11 years. Overall, 62% of the studied group were males and 38% were females. In the study conducted by Neubauer et al. , which included 44 consecutive patients, there were 26 females and 18 males, with a mean age of 11 ± 6 years (range, 4–19 years), who had been examined in a 3-year period. In the current study, most of the lesions are seen involving the long bones (70%), and 26% are seen affecting the axial skeleton and 36% are associated with soft tissue components [Table 1]. The present study showed that most of the lesions are seen involving the metaphysis (36%), metadiaphyseal (20%), diaphyseal (14%), and flat bones (26%). Approximately 56% of the lesions are located at the metaphysis of the long bones, and the femur (50%) and tibia (25%) are the most commonly affected bones founded by Yarmish et al.  Dilated blood-containing cavities with fluidfluid levels that are in the tumor are characteristic features and resemble ABCs. However, a thickened cyst wall and septum in a telangiectatic osteosarcoma can appear as a solid node on enhanced imaging . Concerning the types of the lesions and presence of soft tissue components, the current study indicated that most of the lesions are lytic (64%), 22% are sclerotic, and 14% are mixed. Overall, 36% of the lesions were associated with soft tissue components. Our study revealed that 74% of the lesions are associated with periosteal reaction, and 26% are not associated with periosteal reaction. Neubauer et al.  found that periosteal reaction was found in a total of 37 (71.15%) cases. The Codman triangle (namely, periosteum triangle) is a relatively common type of osteosarcoma periosteal reaction, suggesting that disease progresses rapidly . On the contrary, in terms of lamellar periosteal reaction, there is no tumor tissue to infiltrate in between the layers of new periosteum at the early stage . Results of the current study indicated that 20% of the lesions were biopsied under ultrasound guidance, 16% under computed tomography guidance, and 4% by excision. In the study conducted by Meuwly et al. , it was found that malignant tumors of bone and soft tissue are less common but present an important differential diagnosis. Imaging studies should help to guide invasive diagnostic measures and limit the proportion of patients with benign disease who undergo biopsy . Recent studies have reported that the diagnostic accuracy of needle biopsy ranges from 70 to 98% for musculoskeletal tumors . The radiological diagnosis of the studied group showed that most of the lesions are benign in nature 90% and only 10% are malignant. MRI features of the lesions and radiological diagnosis are accurate, which are confirmed by biopsy and histopathological results. Secondary ABC formation within a primary bone lesion (e.g. giant cell tumor, osteoblastoma, chondroblastoma, and fibrous dysplasia), which occurs with a frequency of up to 35% in several large series, may be the cause of a large number of bone tumors that may present withFluid-fluid levels (FFLs) .
| Conclusion|| |
MRI may provide greater specificity in the diagnosis through signal patterns captured in its wide array of modalities and by enhanced pattern, in which case being more informative than dynamic sequences. In aggressive lesions, MRI is the optimum method for locoregional staging and has shown promising results in determining the degree of tumoral necrosis both during and after chemotherapy treatment, by utilizing advanced sequences.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2]